NEAR-ISOTHERMAL HOT SPIN FORMING METHOD AND HEAT COMPLEMENTING METHOD FOR METAL WORKPIECE

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application serial no. CN 202411229815.7, filed on Sep. 3, 2024. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The present invention relates to the technical field of hot spinning, and in particular to a near-isothermal hot spin forming method and a heat complementing method for a metal workpiece.

Background Art

High-temperature alloy, titanium alloy and other difficult-to-deform alloy materials have high strength, good corrosion resistance, high temperature resistance, high toughness, and good weldability. The casing made from such materials has been widely used in the aero-engine. At present, this kind of parts are mainly manufactured by ring workblanks by ring rolling forming+machining. There is a problem of large machining allowance, which leads to high cost of raw materials, high machining cost caused by large amount of machining removal and part deformation caused by large residual stress. Thus, the development and application of near-net forming technology is very urgent in the manufacture of difficult-to-deform metal ring forgings.

The spin forming process is a kind of method that the metal blank is processed by the plastic deformation of metal into a variety of rotational symmetric hollow workpiece by means of rotation and local pressurization. The process has the characteristics of high machining accuracy and efficiency. The thin wall thickness of the prepared parts is relatively close to the wall thickness of the parts in use. The prepared parts have the characteristics of small machining allowance. It is a near-net forming process that has been widely used in the fields of aerospace, military equipment, automotive parts and so on. At present, the aeroengine casing parts are typical revolving ring parts, which are very suitable for spin forming. However, the difficult-to-deform alloy materials have some problems, such as poor plasticity at room temperature, high forming temperature and narrow deformation temperature window. In the process of hot spin forming difficult-to-deform metal parts, higher requirements are put forward for accurate deformation temperature control.

At present, flame heating is the main heating method in the hot spin forming process, with the flame to heat the blank and spinning roller respectively, which has the advantages of simple heating, high heating efficiency and large temperature range. This heating method belongs to open heating, with the flame only covering a part of the blank. Although various parts of the spinning blank can be covered by reciprocating sweeping, the size of the flame, the heated area, and the distance between the flame and the blank are all manually adjusted, and there is great fluctuation and randomness. The ambient temperature has a great influence on the heating temperature. The heating time and flame size required to ensure the normal processing of the spinning blank are different in different seasons. The heating rate is different. The temperature distribution of each region of the blank is also different. In order to ensure the forming quality, the forming temperature range and temperature uniformity are very strict because of the narrow forming temperature range of the difficult-to-deform metal parts such as titanium alloy and high-temperature alloy. However, the flame heating method has the disadvantages of large temperature fluctuation, low heating accuracy and low heating efficiency, which cannot realize the temperature stability. As a result, the difficult-to-deform metal parts have the defects of instability, wrinkling, poor uniformity of wall thickness and sticking-to-mold, and even the mechanical properties cannot meet the requirements.

In order to improve the accuracy and stability of the temperature, a large number of studies have been performed by the predecessors. In some studies, the temperature of the blank is measured by a temperature device and is fed back to a heating device to control the heating. For example, Patent documents CN103706716B, CN106964682A, and CN111842603B. CN103706716B discloses an accurate temperature control method for hot spinning of a thin-walled titanium alloy member. In the hot spinning process of this method, the deformation zone of the titanium alloy blank is monitored in real time by an infrared thermal imaging device. According to the actual temperature in the deformation zone of the titanium alloy blank fed back by the infrared thermal imaging device, the temperature in the deformation zone of the titanium alloy blank is adjusted in real time by using the local heating device, and the temperature in the deformation zone of the titanium alloy blank is controlled within a certain range, i.e., the accurate temperature control in the hot spinning of the thin-walled titanium alloy member is realized to obtain the thin-walled titanium alloy member. Under the condition of open heating, the measurement error of the workpiece is too large with the multi-point infrared thermometer, and the actual temperature of the material deformation zone cannot be accurately obtained, adjusted and controlled in the spinning process, which cannot meet the requirements of temperature measurement accuracy.

There are also studies using composite heating. For example, the Patent CN109108139 B discloses a spin forming method for a titanium-based alloy material based on composite heating, wherein firstly, a blank, a mandrel and a spinning roller is preheated by a flame gun, then the blank is heated by a follow-up induction heating coil to a spinning temperature. During the spinning process, the temperature is monitored by an infrared thermal imager, and the heating and temperature complementing are provided by the flame gun to the spinning region of the blank behind the spinning roller. However, the difficult-to-deform alloy materials have high forming temperature, narrow hot working window, sensitivity to temperature and strain rate, complex composite heating method, and poor temperature uniformity in different zones, which can not meet the manufacturing requirements of high-precision workpieces.

Therefore, in order to improve the deformability of the material while reducing the deformation resistance, improving the forming quality and efficiency, it is necessary to develop a novel near-isothermal hot spin forming method for the manufacture of difficult-to-deform alloy material workpieces.

SUMMARY

The object of the present invention provides a near-isothermal hot spin forming method and a heat complementing method for a metal workpiece to solve the problem that the existing hot spin forming method for a difficult-to-deform alloy material cannot accurately regulate and control the temperature of a material deformation zone, and the temperature uniformity is poor, resulting in the problem that the requirements for manufacturing a workpiece cannot be met.

In order to achieve the purpose, the invention provides the following technical solutions.

A near-isothermal hot spin forming method for a metal workpiece comprises the steps of:

• • heating a blank to a spin preheating temperature;
  • transferring and clamping the heated blank on a workbench rotating with a main shaft of a spinning device, wherein a heat complementing system is mounted on the periphery of the workbench; the blank is located in an effective heat complementing zone provided by the heat complementing system;
  • measuring the temperature of the blank after the clamping and fixing, and judging whether a temperature T_blank of the blank meets a pre-spinning temperature T_{b spinning} of the blank required by the process; if T_blank≥T_{b spinning}, starting the spinning device to perform spinning; if T_blank<T_{b spinning}, heating and temperature complementing the blank by the heat complementing system until T_blank≥T_{b spinning} is satisfied, and then starting the spinning device to perform spinning; and applying the near-isothermal hot spinning process in the spinning device to spinning form the blank; wherein during the near isothermal spinning, the blank is actively heated and temperature complemented by the heat complementing system, and the spinning temperature is monitored in the spinning deformation zone of the blank in real time to ensure that the fluctuation range of the spinning temperature does not exceed ±20° C. from the beginning of the spinning deformation to the end.

In the technical solution of the present invention, the blank is first heated to a spin preheating temperature in a heating device, and then is transferred and clamped on a workbench of the spinning device. The workbench rotates with the main shaft of the spinning device and can drive the selection of the blank for subsequent spinning. The spinning device is provided with a spinning system and a heat complementing system. The spinning system is configured for realizing local spinning deformation on the blank and for shaping the shape of the workpiece and ensuring the dimensional accuracy. The periphery of the workbench is provided with a heat complementing system which forms an effective temperature complementing zone. The blank is located in the effective temperature complementing zone. That is to say, by the above-mentioned arrangement, the effective temperature complementing zone can envelop the whole blank so as to, in the subsequent process, supplement the heat lost by heat transfer between the blank during fixing and spinning and the environmental heat conduction. At the same time, the heat complementing system on the spinning device does not interfere with the movement of the spinning system in the radial direction and the axial direction of the blank, so as to ensure the synchronous implementation of spinning and heating and temperature complementing during the workpiece forming process. The temperature of the clamped and fixed blank is measured before spinning to judge whether the temperature of the blank meets the pre-spinning temperature of the blank required by the spinning process. If the temperature of the blank at this moment meets the pre-spinning temperature of the blank required by the spinning process, the spinning device is started for spinning. If the temperature of the blank at this moment is lower than the pre-spinning temperature of the blank required by the spinning process, it is necessary to wait for the heat complementing system to actively heat and temperature complement the blank to the pre-spinning temperature of the blank and then start the spinning. Namely, in this step, the temperature is rapidly increased by starting the heat complementing system, and the blank is continuously heated and temperature complemented in the effective temperature complementing zone of the heat complementing system so as to prevent the continuous loss of the temperature of the blank and enable the temperature of the blank to reach the spinning condition required by the process, namely, reaching the pre-spinning temperature. It starts the spinning under the condition that the temperature of the blank reaches the pre-spinning temperature of the blank. In the spinning process, it continues to use a heating system to heat and temperature complement the blank, with real-time monitoring and recording of the deformation temperature in the spinning deformation zone of the blank, namely, the spinning temperature, so that the fluctuation of the spinning temperature does not exceed ±20° C. during the process from the beginning to the end of spinning. At the same time, the maximum value and the minimum value of the spinning temperature T_spinning are both within the temperature fluctuation range required by the process. That is to say, the deformation temperature of the metal material is maintained within a small fluctuation range by a measurable and controllable heating system during the forming process, thereby achieving near-isothermal spinning deformation. Such an arrangement can reduce the deformation resistance of the difficult-to-deform metal material, maintain a high deformation capacity of the metal material during the spinning process, improve the forming quality and efficiency, and meet the requirements for the manufacture of the workpiece. The technical solution has good consistency and traceability of the deformation parameters of the hot spinning product.

According to the above-mentioned technical solution, the spinning temperature is higher than the recrystallization temperature of the metal material. The spin forming process of the present invention is hot working. The dynamic recrystallization occurs in the metal material, which helps to eliminate work hardening, thereby improving the plasticity and toughness of the metal material. The consistency of the formed workpiece product is very good, which can meet the requirements for manufacturing a high-precision workpiece. The technical solution of the present invention is applicable to a difficult-to-deform metal with a narrow forming temperature range, and a non-difficult-to-deform metal is also applicable.

In the present invention, the effective temperature complementing zone refers to a zone formed in the heat complementing system which can make the workpiece reach the required temperature after heating and temperature complement and have a uniform temperature distribution. The heating zone which can achieve the heating and temperature complement effect in the heat complementing system may be a zone larger than the effective heating zone, because part of the heating region has a lower temperature or a non-uniform temperature distribution due to the arrangement problem of the heating elements, and thus is not suitable for the heating and temperature complement and control of the blank. The effective temperature complementing zone of the heat complementing system is ensured by a reasonable arrangement of the heating elements to ensure the quality of the workpiece.

The pre-spinning temperature T_{b spinning} is the starting temperature of spinning. When the temperature of blank reaches the pre-spinning temperature, the difficult-to-deform metal material has a high deformation capacity and can provide a temperature basis for the spinning temperature fluctuation range within ±20° C. in the near-isothermal hot spinning process. The pre-spinning temperature of the blank is within the temperature range of the spinning temperature. The pre-spinning temperature of the blank can be determined according to the processing experience of the metal material. For a new metal material, the pre-spinning temperature of the blank can be obtained using a numerical simulation software or a calculation formula.

The spinning temperature T_spinning refers to the temperature in the spinning deformation zone of the blank when the spinning roller is in contact with the blank and after the spinning force is applied. The spinning temperature is the instantaneous spinning temperature. The spinning temperature shall be determined according to the deformation temperature range according to the specific material type and spinning condition, i.e., the spinning temperature is not a fixed value but a temperature range with a certain fluctuation range. In the near-isothermal hot spinning process of the present invention, the range of the spinning temperature fluctuation is between the maximum value and the minimum value required by the process, so as to realize strict control of the spinning temperature, which can ensure that the metal material has sufficient plasticity, and also avoid the occurrence of cracks, metal accumulation and other spinning defects caused by too high or too low temperature. The spinning temperature T_spinning of the blank fluctuates within a spinning pass (namely, from the beginning to the end of single-pass spinning) within a range of not more than ±20° C. Namely, within a spinning pass, the difference between the maximum value T_{spinning max} and the minimum value T_{spinning min} of the spinning temperature is not more than 40° C. The spinning temperature can be obtained according to the corresponding thermal processing map of workpiece material. For the spinning temperature of specific metal material as range value, it can be obtained by the material manual or thermal simulation test.

As a preferred embodiment of the present invention, the spin preheating temperature is 300-1200° C., and the spin preheating temperature of the blank is determined according to the spinning process for different metal materials.

As a preferred embodiment of the present invention, the time taken to complete the transferring and clamping of the heated blank on the workbench of the spinning device is taken as the transferring time which is required not to exceed 90 s. In the above-mentioned technical solution, there is a heat loss during the transfer process and the clamping and fixing process of the blank heated to the pre-heating temperature of the spinning, resulting in a temperature drop of the blank. Before the spinning is performed, it may result in that the temperature of the blank may not reach the temperature condition for starting the spinning which is allowed by the process, and the hot spinning of the difficult-to-deform metal cannot be performed immediately. It is necessary to start the spinning when the spinning condition is satisfied after the blank is heated and temperature complemented by the heat complementing system, which results in a complicated process flow. Therefore, the shorter the transfer time is, the better the transfer time is, which can reduce the heat loss of the blank during the transfer and fixing process, and the temperature drop. It is beneficial to reduce the waiting time for temperature complementing of the blank and reduce the energy consumption at the same time, but the shorter the transfer time, the higher the requirements for the flexibility of the transfer device and the fixing device. Considering comprehensively, the range of the transfer time is 40-90 s. For different metal materials, the transfer time of different metal materials is determined according to the spinning processing requirements, device status and other factors. The shorter the transfer time, the better the effect.

As a preferred solution of the present invention, the spinning device comprises a machine body, a heat complementing system and a spinning roller system, wherein the heat complementing system and the spinning roller system are provided on the machine body; a workbench is mounted on a main shaft of the machine body; the spinning roller system comprises a spinning roller assembly; the heat complementing system comprises a furnace body and a temperature control system, and the temperature control system comprises a furnace body temperature measurement module, a control module and a heating module; the heating module comprises a plurality of heating elements; a furnace cavity is formed in the furnace body, wherein the heating element is arranged on the inner wall of the furnace cavity for forming an effective temperature complementing zone in the furnace cavity; a spinning roller movement groove is provided on the furnace body, and the spinning roller assembly passes through the spinning roller movement groove for ensuring that the spinning roller assembly can move freely in the radial direction and the axial direction of the blank; the furnace body temperature measurement module is configured for detecting the temperature of the effective temperature complementing zone; and the furnace body temperature measurement module and the heating module are both electrically connected to the control module.

In the above-mentioned technical solution, the spinning device integrates a heat complementing system and a spinning roller system. The heat complementing system and the spinning roller system are provided on the machine body, and the spinning roller assembly of the spinning roller system locally pressurizes the blank and can form the shape and size of the workpiece. A furnace cavity is formed in the furnace body of the heat complementing system. A heating element is arranged in the furnace cavity wall body, the uniform arrangement of the heating elements enables an effective temperature complementing zone to be formed in the furnace body, and the blank is located in the effective temperature complementing zone and can perform heating and temperature complementing on the blank. At the same time, a spinning roller movement groove is provided on the furnace body of the heat complementing system. The spinning roller assembly passes through the spinning roller movement groove and is located in the spinning roller movement groove. Such an arrangement ensures that the spinning roller assembly can freely move in a radial direction and an axial direction along the blank. The above-mentioned furnace body provided with the heat complementing system is a semi-closed structure, and a semi-closed furnace cavity is formed in the furnace body. The heat complementing system on the spinning device does not interfere with the movement of the spinning system in the radial direction and the axial direction of the blank, so as to ensure the synchronous implementation of spinning and heating and temperature complementing during the forming of the workpiece. The furnace body temperature measurement module of the temperature control system detects the temperature of the effective temperature complementing zone, and feeds back a temperature signal to the control module. The control module receives the temperature signal from the furnace body temperature measurement module, compares and processes same according to the target complement temperature set by the temperature control system, and outputs a corresponding control signal to the heating module. The heating module is managed by the control module, so as to adjust the heating power of the heating element according to the temperature signal fed back by the furnace body temperature measurement module, and keep the temperature stable near to the target complement temperature by continuous adjustment. The connection among the furnace temperature measurement module, the heating module and the control module of the temperature control system constitutes a temperature closed-loop control system for accurately monitoring and adjusting the temperature of the effective temperature complementing zone. By the accurate temperature measurement of the furnace temperature measurement module, the temperature control of the control module and the accurate regulation and control of the heating module, the temperature uniformity of the effective temperature complementing zone is ±15° C., and the temperature control accuracy is ±1° C. The connection mode between the control module and the furnace temperature measurement module or the heating module is a field bus, an industrial Ethernet, etc., and these connection modes can be understood by a person skilled in the art so as to realize the transmission of data and the reception of the control signal.

As a more preferable aspect of the present invention, the workbench of the machine body is installed with a quick clamping structure of the blank, and the bottom of the furnace body is connected to the workbench for supporting the blank. The clamping structure is used for fixing the blank on the workbench.

As a preferred embodiment of the present invention, the control module of the heat complementing system is provided with a target complement temperature ranging from 300° C. to 1200° C. The control module comprises a user interface, such as a display screen and a control panel, which allows the user to set the target complement temperature, monitor the real-time temperature and other parameters. The temperature control accuracy and temperature measurement mode of the temperature complementing system meet the requirements of the standard.

As a preferred embodiment of the present invention, the furnace body temperature measurement module comprises a plurality of temperature measurement sensors; and the installation position and insertion depth of the plurality of temperature measurement sensors are designed on the furnace body to reflect the real temperature of the effective temperature complementing zone. The temperature measurement sensor is a thermocouple, a sensor for temperature measurement based on the thermoelectric effect.

As a preferred solution of the present invention, the spinning roller assembly comprises an inner spinning roller and an outer spinning roller; during the operation of the spinning roller assembly, all the structures of the inner spinning roller and part of the structures of the outer spinning roller are located in the effective temperature complementing zone of the heat complementing system; the inner spinning roller is located on the inner side of the blank and can abut against the inner wall of the blank of the workpiece; the outer spinning roller is located on the outer side of the blank and can abut against the outer wall of the blank of the workpiece; and the inner spinning roller and the outer spinning roller pass through the spinning roller movement groove and are located in the spinning roller movement groove, ensuring that the inner spinning roller and the outer spinning roller are free to move independently in radial and axial directions along the blank.

In the above-mentioned technical solution, all of the inner spinning roller and a part of the outer spinning roller are located in an effective temperature complementing zone, and the effective temperature complementing zone can perform heat preservation and preheating on the inner spinning roller and the outer spinning roller, so as to reduce the temperature difference between the inner spinning roller, the outer spinning roller and the blank, and further reduce the temperature drop of the workpiece during spinning, which is more beneficial to control the spinning temperature of the blank during near isothermal spinning. The inner spinning roller is located at the inner side of the blank, and the outer spinning roller is located at the outer side of the blank, wherein the inner spinning roller and the outer spinning roller pass through the spinning roller movement groove and are located in the spinning roller movement groove, so as to ensure that the inner spinning roller and the outer spinning roller can independently move in the radial direction and the axial direction of the workbench, and perform spatial spinning on the wheel according to the spinning track required by the process. At the same time, the diameter and width of the spinning roller movement groove should be greater than the diameters of the inner spinning roller and the outer spinning roller, so as to prevent interference during the spinning process. During the spinning process, the inner spinning roller and the outer spinning roller respectively abut against the inner wall and the outer wall of the blank to locally pressurize the blank. Under the action of the rotation of the blank, the inner spinning roller and the outer spinning roller move along the radial direction and the axial direction of the blank to spin and form the blank. The movement between the inner spinning roller and the outer spinning roller does not affect the operation of the heat complementing system, and the spinning process and the heat complementing process do not interfere with each other, so as to respectively ensure the realization of spinning and heating and temperature complementing in the workpiece forming process.

Further, the spinning roller movement groove are provided on the top and side surfaces of the furnace body to ensure independent free movement of the spinning roller assembly in the radial and axial directions of the blank.

As a preferred solution of the present invention, the furnace body comprises a furnace body I and a furnace body II which are provided opposite to each other; wherein a furnace cavity I is formed in the furnace body I, a furnace cavity II is formed in the furnace body II, and the furnace cavity I and the furnace cavity II form a furnace cavity of the furnace body; the furnace body I and the furnace body II can be close to or away from the workbench; the furnace body I and the furnace body II are close to each other to form a furnace cavity, so that the blank is located in the effective temperature complementing zone; a first spinning roller movement groove is provided on the furnace body I; a second spinning roller movement groove is provided on the furnace body II; and the first spinning roller movement groove and the second spinning roller movement groove form the spinning roller movement groove.

In the above-mentioned technical solution, the furnace body structure of the heat complementing system is a semi-closed movable split-type structure. The furnace body I and the furnace body II can approach or move away from the workbench to facilitate the taking or placing of the workpiece blank. When the blank is to be placed on a workbench or the blank is taken out of the workbench after the spinning is completed, the furnace body I and the furnace body II are away from the workbench, and at this time, the furnace body is in an open state. When the blank is fixed on the workbench of the spinning device, the furnace body I and the furnace body II are close to the workbench, the furnace body is in a closed state, and the furnace cavity I and the furnace cavity II form a furnace cavity. The first spinning roller movement groove and the second spinning roller movement groove form the spinning roller movement groove. The spinning roller assembly passes through the spinning roller movement groove and is located in the spinning roller movement groove. An effective temperature complementing zone is provided in the furnace cavity. When the furnace body is closed, the blank is located in the effective temperature complementing zone, and the heat complementing system can accurately monitor and adjust the temperature of the effective temperature complementing zone by the closed loop control among a furnace body temperature measurement module, a heating module and a control module of a temperature control system, so that the effective temperature complementing zone provides a uniform temperature field for heating and temperature complement of the blank.

As a more preferred solution of the present invention, the furnace body I and the furnace body II close the furnace body of the heat complementing system by approaching the workbench; the furnace body I and the furnace body II open the furnace body of the heat complementing system by being away from the workbench; the time taken for the furnace body to complete the closing is controlled within 15 s; and the time taken for the furnace body to complete the opening is controlled within 15 s. The furnace body structure of the heat complementing system is a semi-closed movable split-type structure, and the completion of the closing or opening of the furnace body is achieved by the furnace body I and the furnace body II respectively being close to or far from the workbench. In their process of being close to or far from the workbench, the effective heating zone is open, resulting in heat loss in the effective temperature complementing zone. Therefore, the time for completing the closing or opening is required to be strictly controlled so as to avoid excessive loss of ambient temperature in the effective temperature complementing zone caused by the opening of the furnace body.

As a more preferable embodiment of the present invention, the maximum target temperature of the complement temperature after the closing of the furnace body of the heat complementing system coincides with the pre-spinning temperature required for the process. The set value of the target complement temperature shall take full account of the temperature rise effect caused by deformation heat generation in the spinning deformation zone, and the sum of the set spinning temperature value and the temperature rise caused by deformation heat generation is the measured spinning temperature in the actual deformation process of the workpiece.

As a more preferable aspect of the present invention, the furnace body I or the furnace body II is connected to the spinning device body by a sliding member or an articulated member so that the furnace body I and the furnace body II can slide closer to or farther from the work stage, or the furnace body I and the furnace body II can rotate closer to or farther from the work stage. By means of the above-mentioned arrangement, a semi-closed effective temperature complementing zone is formed in the furnace body I and the furnace body II. The furnace body I and the furnace body II are away from the workbench before the blank is transferred and clamped on the workbench. After the fixing is completed, the furnace body I and the furnace body II are close to the workbench to form an effective temperature complementing zone. The blank is heated and temperature complemented by a heat complementing system until the blank reaches the spinning temperature.

As a more preferred embodiment of the present invention, the furnace body I and the furnace body II have a semi-cylindrical cavity structure with a wall thickness of 50-100 mm.

As a preferred embodiment of the present invention, the blank temperature T_blank is measured on the blank after clamping and fixing, and compared with the pre-spinning temperature T_{b spinning} required by the process; if T_blank<T_{b spinning}, it starts the heat complementing system to heat and temperature complement the blank; the heat complementing system adjusts the heating power of the heating element to increase a temperature rising rate of the temperature complementing, actively complement and heat the blank within the heat complementing time, so that the temperature of the blank reaches the temperature before spinning, and then the spinning device is started for spinning the workpiece according to a predetermined spinning program; if T_blank≥T_{b spinning}, the heat complementing system is started to temperature complement the preform; at the same time, it starts the spinning device to start workpiece spinning according to a predetermined spinning program; and the heat complementing system will maintain the heating power of the heating element, so as to maintain the temperature of the blank within the spinning temperature range.

In the above-mentioned technical solution, the heat of the blank heated to the spin preheating temperature is lost in the process of transferring and fixing the blank to the workbench, resulting in a decrease in the temperature of the blank. Thus, the temperature of the blank cannot reach the pre-spinning temperature T_{b spinning}, and near-isothermal spinning cannot be achieved. By measuring the temperature T of the blank, and comparing same with the pre-spinning temperature T_{b spinning} required by the process, it is judged whether to start spinning immediately or to wait for the heat complementing system to temperature complement the blank to the pre-spinning temperature before starting spinning. When the temperature of the blank T_blank is lower than the pre-spinning temperature T_{b spinning} required by the process, which indicates that the temperature drop of the blank is large in the process of transferring and fixing to the workbench and does not meet the starting spinning temperature condition required by the spinning process, the heat complementing system will increase the heating power of the heating element, increase the temperature rise rate of the heat complement, and perform active and rapid complement heating on the blank within the specified heat complement time, so as to offset the heat loss of the blank. It makes the temperature of the blank reach the pre-spinning temperature. When the temperature of the blank T is higher than the pre-spinning temperature T_{b spinning} required by the process, it means that the temperature drop of the blank is small during the transfer process and the process of fixing same to the workbench, so as to meet the starting-spinning temperature condition required by the spinning process. The heat complementing system will maintain the heating power of the heating element and maintain the spinning temperature, so as to prevent the loss of the temperature of the blank during the spinning process. When the heat complementing system is started to temperature complement the blank, the spinning device is started to perform the workpiece spinning according to the predetermined spinning program.

As a more preferred solution of the present invention, the temperature of the effective temperature complementing zone of the heat complementing system is not higher than the preheating temperature of spinning; if T_blank<T_{b spinning}, it starts the heat complementing system to heat and temperature complement the blank; and the heat complementing time of the heat complementing system does not exceed 5 min. The spinning temperatures of workpieces of different metal materials are different, the corresponding heat complementing time is different. The temperature complementing time is determined according to the processed metal materials to control the heat complementing system. In the present invention, the fixed blank is located in an effective temperature complementing zone of the heat complementing system, and the holding temperature of the effective temperature complementing zone before the heat complementing system is turned on should be lower than the spin preheating temperature, so as to prevent the defect of microstructure caused by the increase in the temperature of the blank. The heat complementing time should be controlled not to exceed 5 min, and thus the heating rate for heat complementing should be as fast as possible.

As a preferred solution of the present invention, the spinning device is further provided with a blank temperature measurement module for detecting the temperature of the blank located in the effective temperature complementing zone to obtain a blank temperature T_blank or a spinning temperature T_spinning, and the blank temperature measurement module is externally provided on the heat complementing system or the machine body of the spinning device.

In the above-mentioned technical solution, after the clamping is completed, the temperature of the blank is detected via the blank temperature measurement module, and the detected temperature of the blank is fed back to the heat complementing system, thereby controlling the heat complementing system to heat and temperature complement the blank. In addition, when the heat complementing system comprises a furnace body and a temperature control system, the temperature control system comprises a furnace body temperature measurement module, a control module and a heating module. The furnace body temperature measurement module is configured for detecting the temperature of the effective heat complementing zone. The furnace body temperature measurement module and the blank temperature measurement module cooperate to respectively test the temperature of the effective heating zone and the blank, so as to obtain the real-time temperature of the effective heat complementing zone for heating and temperature complementing of the blank, providing a basis for the parameter adjustment of the heat complementing system, stabilizing the adjustment range of the heat complementing system, and improving the stability and reliability of the heat complementing system.

As a more preferred solution of the present invention, the blank temperature measurement module comprises at least one infrared temperature measurement sensor, wherein the infrared temperature measurement sensor is in non-contact with the target temperature-measurement blank. The infrared temperature measurement sensor is located between the blank and the heating element. The infrared temperature measurement sensor is always directed onto the blank. The installation of the infrared temperature measurement sensor does not affect the movement of the spinning assembly.

As a preferred solution of the present invention, the spinning temperature is 900-1150° C. for blanks of high temperature alloy material. The blank of high-temperature alloy material includes but is not limited to one of Waspaloy, GH4169, IN718, GH3536, IN783, IN625 and GH4698. For different models of high-temperature alloy materials, the spinning temperature is different. The spinning temperature range is determined according to the specific material designation, but is within 900-1150° C.

When spinning the high-temperature alloy material, the high-temperature alloy material, as a difficult-to-deform alloy material, is required to avoid the grain growth caused by excessive temperature, which will affect the mechanical properties of the material. At the same time, the excessively low forging temperature will increase the difficulty of spinning deformation, resulting in the production of cracks in the workpiece. Therefore, in the present invention, the near-isothermal hot spinning process is used for the high-temperature alloy material. In the spin forming, the heat complementing system is used to heat and temperature complement the blank, so that the fluctuation range of the spinning temperature of the blank is controlled within ±20° C., and the maximum value and the minimum value of the spinning temperature are both within the spinning temperature range required by the process. Such an arrangement can ensure good deformation capability of the metal material in the spinning process, reduce the deformation resistance, improve the forming quality and forming efficiency, and meet the requirements of workpiece manufacturing. The precise temperature control is the key to ensure the quality of high temperature alloy forgings.

During the spinning process, the forming performance and the final structure of the workpiece are optimized by controlling the spinning process parameters, and the cooling rate of the workpiece has a significant effect on the final structure and properties after the forming.

As a preferred solution of the present invention, the spinning temperature is 700-900° C. for blanks of titanium alloy materials. The titanium-based alloy blank includes, but is not limited to, one of Ti6242, Ti64, TC11, TC4, TA12A, TA7, TA15, etc. For different types of titanium alloy materials, the spinning temperature is different, and the spinning temperature is adjusted according to the phase transition temperature of specific material designation, so as to ensure that the titanium alloy has higher plasticity and lower deformation resistance at the spinning temperature.

During spinning, the spinning temperature at which the titanium alloy material begins to spin is generally above its β transformation temperature to ensure that the titanium alloy has good plasticity in the beta phase region. At the same time, the spinning temperature before finishing the spinning should be controlled in a α+β two-phase region to ensure the structure and mechanical properties of forgings. In addition, the spinning temperature range of titanium alloy is narrow, which requires that the heating and temperature complementing time of the heat complementing system on the blank should be strictly controlled in the spinning manufacturing process, and the spinning temperature fluctuation range of the blank should be controlled within ±20° C., so as to avoid grain growth or other unfavorable microstructure.

As a preferred embodiment of the present invention, during the near-isothermal spinning, the blank is heated and temperature complemented by the heat complementing system, so as to ensure that the fluctuation range of the spinning temperature does not exceed ±10° C. from the beginning to the end of the spinning deformation. The spinning temperature is controlled more accurately, the deformation coefficient of metal material is smaller, and the consistency of formed workpiece products is better.

As a preferred embodiment of the present invention, the rotation speed of the blank is 50-300 r/min during the spin forming of the blank by the near-isothermal hot spinning process; the feed ratio of the spinning roller is 0.1-3 cm/r; the radius of the round corner of the spinning roller is 0.3 t-2.5 t, where t is the wall thickness of the blank, mm; and the reduction rate of each pass is 10%-40%, and the reduction rate of each pass shall not be greater than the limit reduction rate of metallic materials.

In the above-mentioned technical solution, in order to ensure the mechanical performance and processing accuracy of the workpiece, the spinning process parameters are controlled during the spinning process. The main shaft of the spinning device drives the rotation of the workbench and the blank. The rotation speed of the blank is rationally selected in the range of 50-300 revolutions/minute, and the feed ratio of the spinning roller is rationally selected in the range of 0.1-3 mm/revolution. The round radius of the wheel is reasonably selected within the range of 0.3 t-2.5 t. The reduction rate of each spinning pass shall be no greater than the limit reduction rate. Generally, it is selected within the range of 10%-40% and rationally selected. After at least one spinning pass, the blank is spun to the design requirements of the workpiece. If the reduction rate of one spinning pass does not exceed the limit reduction rate φ_max of the material, the blank can be made to meet the wall thickness and dimension requirements of the ring by single-pass spinning, and then the spin forming is completed. If the single-pass reduction rate exceeds the limit reduction rate φ_max, the spinning shall be performed in two passes, wherein the reduction rate of the first pass may be set as the limit reduction rate φ_max. If the reduction rate of the second pass also exceeds the limit reduction rate φ_max, and the workpiece still does not reach the required thickness, the spinning shall be performed in three passes, and so on, until the thickness of the workpiece reaches the process requirements after the last pass of spinning. During the spinning process, the forming performance and the final structure of the workpiece are optimized by controlling the spinning process parameters.

As a preferred solution of the present invention, during the spin forming process, a staggered distance or no staggered distance is used by the spinning roller assembly of the spinning device. When the staggered distance is used, the radial and axial staggered distances are selected according to the spinning process and the material of the workpiece. The mode of rotation is forward rotation or reverse rotation.

According to another aspect of the present invention, there is provided a metal workpiece prepared by the near-isothermal hot spin forming method described above.

As a preferred solution of the present invention, the cross section of the workpiece includes, but is not limited to, one of a rectangular workpiece, a flange workpiece, an I-shaped workpiece, an L-shaped workpiece, a long cylindrical workpiece, a cone part, an irregular part, and the like, which is suitable for the spinning process.

The present invention also refers to a heat complementing method for the heat complementing system in the near-isothermal hot spin forming, the heat complementing method comprising the steps below. After the heated blank is transferred and clamped on the workbench rotating with the main shaft of the spinning device, the blank is located in the effective temperature complementing zone of the heat complementing system, and the heat complementing system is configured for heating and temperature complementing the blank; by setting a target complement temperature Tcomp and a heating rate v of the heat complementing system, the blank temperature T_blank reaches the pre-spinning temperature T_{b spinning} required by the process, and the calculation formula of the pre-spinning temperature T_{b spinning} is as follows:

T b ⁢ spinning = T spinning - Δ ⁢ T

• • where T_spinning is the spinning temperature measured in the spinning deformation zone during the spinning process of the workpiece, in the unit of ° C.; ΔT is the temperature rise caused by the heat generated by spinning deformation, in the unit of ° C.;
  • after the blank temperature T_blank reaches the pre-spinning temperature T_{b spinning} required by the process, the spinning device is started to perform spinning according to the pre-spinning program; and at the same time, the heating and temperature complementing system is configured for heating the blank so that the spinning temperature is controlled within the range required by the process, with the fluctuation range not exceeding ±20° C. from the beginning to the end of spinning deformation.

As a preferred embodiment of the present invention, the calculation formula of ΔT is as follows:

Δ ⁢ T = Q m ⁢ C

• • where Q is the heat generated by plastic deformation, in the unit of J; m is the mass of blank, in the unit of kg; and C is the specific heat capacity of the blank material, in the unit of J/(kg·° C.).

As a preferred embodiment of the present invention, the calculation formula of the amount of heat Q due to plastic deformation is as follows:

Q = θ * σ ¯ * ε ˙

• • where θ is the thermal effect coefficient of deformation, and 0.9 is generally taken in the plastic deformation of metals; σ is the equivalent stress at the deformation temperature, and it is convenient to calculate the yield strength σs of material at the deformation temperature; {dot over (ε)} is the equivalent strain rate of spinning deformation; and the formula for calculating the equivalent strain rate is as follows:

ε ˙ = n 2 ⁢ π ⁢ ln ⁡ ( 1 1 - φ )

• • where n is the rotational speed of the main shaft of the spinning, in the unit of r/min; φ is the spinning reduction rate; and

φ = t 0 - t f t 0 ,

• •  t₀ and t_r are the thickness of the blank before and after the spinning, respectively, in the unit of mm.

The invention has the following beneficial effects compared to prior art.

• • 1. According to the hot spin forming method provided in the present invention, the blank is located in the effective temperature complementing zone, the temperature of the blank is measured after clamping and fixing before the spinning to judge whether the temperature of the blank meets the pre-spinning temperature of the blank required by the spinning process. If the temperature of the blank at this moment meets the pre-spinning temperature of the blank required by the spinning process, the spinning device is started for spinning. If the temperature of the blank at this time is lower than the pre-spinning temperature of the blank required by the process, it waits for the heat complementing system to heat and complement the blank to the pre-spinning temperature of the blank and then starts the spinning, rapidly increasing the temperature by starting the heat complementing system. The effective temperature complementing zone of the heat complementing system continuously heated and temperature complements the blank so as to prevent the continuous loss of the temperature of the blank, so that the temperature of the blank reaches the spinning condition required by the process, namely, reaching the pre-spinning temperature, and starting the spinning under the condition that the temperature of the blank reaches the pre-spinning temperature of the blank. In the spinning process, the blank is heated and temperature complemented by the heat complementing system continuously, so that the temperature fluctuation range of the blank in the process from the beginning to the end of spinning is not more than ±20° C. That is to say, the deformation temperature of the metal material in the forming process is maintained within a small fluctuation range by using the measurable and controllable heat complementing system. Such setting can ensure that the metal material in the spinning process has a good deformation capacity, reduce the deformation resistance, and improve the forming quality and efficiency. The formed workpiece has good consistency, and can meet the manufacturing requirements of high-precision workpieces. The technical solution of the present invention is applicable to difficult-to-deform metals having a narrow forming temperature range, and non-difficult-to-deform metals are also applicable.
  • 2. The spinning device of the present invention integrates a heat complementing system and a spinning roller system. The heat complementing system and the spinning roller system are provided on the machine body. The spinning roller assembly of the spinning roller system locally pressurizes a blank and is able to form the shape and size of a workpiece. The furnace body of the heat complementing system is of a semi-closed structure. The furnace cavity is formed in the furnace body. The heating element is provided in the furnace cavity. The heating elements are arranged in the furnace body to form an effective temperature complementing zone, and can heat and temperature complement the blank when the blank is located in the effective temperature complementing zone. At the same time, the furnace body of the heat complementing system is provided with a spinning roller movement groove. The spinning roller assembly passes through the spinning roller movement groove and is located in the spinning roller movement groove, so as to ensure that the spinning roller assembly can move independently in the radial direction and the axial direction of the workbench, and no interference occurs between the spinning process and the heat complementing process, so as to respectively ensure the realization of spinning and heating and temperature complementing during the workpiece forming process.
  • 3. According to the furnace body and the temperature control system of the heat complementing system of the present invention, the temperature control system comprises a furnace body temperature measurement module, a control module and a heating module. The furnace body temperature measurement module, and the heating module and the control module of the temperature control system are connected to constitute a closed-loop control system for the temperature. By the accurate temperature measurement of the furnace temperature measurement module, the temperature control of the control module and the accurate regulation and control of the heating module, the temperature uniformity of the effective temperature complementing zone is ±15° C., and the temperature control accuracy is ±1° C., which provides an equipment basis for accurate control of the spinning temperature in the spinning process.
  • 4. In the spin forming process of the present invention, the blank is heated and temperature complemented by the heat complementing system so as to realize the near-isothermal hot spinning process, which can improve the deformation compatibility of the blank, and the forming quality and production efficiency of the workpiece. The results of the examples show that the high-temperature alloy or titanium alloy is spun by the near-isothermal hot spinning method of the present invention, and the obtained spun workpiece has a uniform wall thickness, so as to avoid the cracking of the workpiece during multi-pass spinning. The forming quality is good, and defects such as instability and wrinkling do not occur during the spinning process. It also reduces the occurrence of cracks and the risk of grinding. The mechanical properties of the workpiece obtained by spinning can meet the performance requirements of the part. At the same time, the structure uniformity of the workpiece is improved, and the grain size can reach Grades 7-9.
  • 5. The near-isothermal hot spin forming method of the present invention can realize the forming of a thin-walled workpiece by controlling the temperature and the spinning process parameters. The process flow is simple and can be implemented, saving materials and reducing processing costs. Meanwhile, the temperature during the spinning deformation is controllable and measurable, thereby effectively improving the quality consistency and stability of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a blank prepared in Example 1.

FIG. 2 is a schematic cross-sectional view of a workpiece prepared in Example 1.

FIG. 3 is a schematic view showing a structure of a heat complementing system and a spinning roller system of a spinning device of the present invention.

FIG. 4 is a schematic cross-sectional view showing opening and closing states of the heat complementing system of the spinning device according to the present invention.

FIG. 5 is a schematic top view of the heat complementing system and the spinning roller system of the spinning device according to the present invention.

FIG. 6 is a schematic cross-sectional view of a blank prepared according to Example 2.

FIG. 7 is a schematic cross-sectional view of a workpiece prepared in Example 2.

REFERENCE NUMERALS

• • 1—machine body, 2—workbench, 31—furnace body I, 32—furnace body II, 41—outer spinning roller, 42—inner spinning roller, 5—blank, 6—workpiece.

DETAILED DESCRIPTION OF THE INVENTION

In order to more clearly describe the objects, technical solutions and advantages of the present invention in specific embodiments thereof, the solutions in specific embodiments is described below in detail in combination with the accompanying drawings of the invention. The specific examples described below are intended only to provide a clear and complete description of the inventive aspects of the present invention, which are only a part of the specific examples that can be adopted by the invention, not all embodiments, and are not to be construed as limiting the inventive aspects of the present invention in any way. Any solution employing the same inventive concept of the present invention should be included in the scope of the present invention.

Secondly, the description related to the drawings in the specific examples of the present invention is merely for the convenience of a person skilled in the art to understand the solution of the present invention, and some details are shown in the drawings for the purpose of facilitating the clear presentation of the technical solution. It should not be considered that all the technical features in the drawings must be included in the specific examples, and the detailed features in the drawings may not be considered as additional limitations on the technical solution of the present invention. The components of the various examples described and illustrated in the figures may be combined in various configurations, and variations of such combinations are considered to be part of all examples of the inventive solutions and are intended to be within the scope of the invention.

In summary, the solutions or descriptions presented in the specific examples and figures of the present invention are not intended to limit the scope of the claims, but merely represent selected examples/cases that help the skilled person understand the relevant innovative solutions. Based on these examples, all other equivalent or parallel examples obtained by a person skilled in the art without inventive effort fall within the scope of the claimed invention.

It should be noted that in the description of the specific examples of the present invention, the terms “upper”, “lower”, “left”, “right”, “center”, “inner”, “outer”, etc. designate directions or positional relationships, unless specifically stated otherwise, based on the expressions of the directions or positional relationships shown in the drawings, or the directions or positional relationships in which the product/device/apparatus of the present invention is conventionally used. These terms of orientation or positional relationship are merely used to facilitate the description of solutions of the present invention or to simplify the description of specific examples for the skilled artisan to quickly understand aspects, and do not indicate or imply that a particular device/component/element must have a particular orientation or be constructed and operated in a particular positional relationship, and thus should not be construed as limiting the present invention.

In addition, in the description of the technical solution of the present invention, unless explicitly stipulated/defined/limited otherwise, where the terms “providing”, “mounting”, “connecting”, “connecting”, and “providing” appear, it should be understood in a broad sense. For example, it may be a fixed connection, or a detachable connection, or an integral connection, and may be a connection means commonly used in the art, such as welding, riveting, bolting, screwing and the like. This connection may be a mechanical connection, or may be an electrical connection or a communication connection. They may be connected directly or indirectly via an intermediate medium, and may be in communication internal to two elements.

Embodiment 1

The material of the blank is a high-temperature alloy GH4169. The initial wall thickness of the blank 5 before spinning is 15 mm, as shown in FIG. 1. The minimum wall thickness of the workpiece 6 after spinning is designed to be 10.5 mm, as shown in FIG. 2. The spinning reduction rate is 30%. According to the production experience of hot spinning of nickel-based high-temperature alloy, the limit single-pass reduction rate of the workpiece is generally 50-60%, and the maximum reduction rate of the workpiece is less than the limit reduction rate. The single-pass spin forming can be used. In the spinning design, it is made to 10.5 mm by one-pass spinning, with the deformation of 30%, and the length of the spinning section increased from 145 mm to 200 mm. The near-isothermal hot spinning is applied in the spinning of the workpiece, and the spinning is performed in the spinning device.

As shown in FIGS. 3 and 4, the spinning device integrates a heat complementing system and a spinning roller system. A workbench 2 is mounted on a main shaft of a spinning device body 1. The main shaft may drive the workbench 2 to rotate. The heat complementing system comprises a furnace body and a temperature control system. The temperature control system comprises a furnace body temperature measurement module, a control module and a heating module, and the heating module comprises several heating rods. The structure of the furnace body is a semi-closed movable split-type structure. A furnace cavity is formed in the furnace body. A heating rod is arranged on the inner wall of the furnace cavity for forming an effective temperature complementing zone in the furnace cavity. The furnace body comprises a furnace body I 31 and a furnace body II 32, which are semi-cylindrical cavity structures. The furnace body I 31 and the furnace body II 32 are arranged opposite to each other. The furnace body I 31 and the furnace body II 32 may approach or move away from the workbench 2. The furnace cavity I is formed in the furnace body I 31, the furnace cavity II is formed in the furnace body II 32, and the blank 5 is located in the effective temperature complementing zone when the furnace body I 31 and the furnace body II 32 approach the workbench 1. The furnace body I 31 is provided with a first spinning roller movement groove. The furnace body II 32 is provided with a second spinning roller movement groove. The first spinning roller movement groove and the second spinning roller movement groove form a spinning roller movement groove. The spinning roller system comprises an inner spinning roller 42 and an outer spinning roller 41. When the spinning roller assembly is in operation, all the structures of the inner spinning roller 42 and part of the structures of the outer spinning roller 41 are located in an effective temperature complementing zone of the heat complementing system. The inner spinning roller 42 is located at the inner side of the blank 5 and can abut against the inner wall of the blank 5 of the workpiece. The outer spinning roller 41 is located at the outer side of the blank 5, and the outer spinning roller 41 can abut against the outer wall of the blank 5 of the workpiece. The inner spinning roller 42 and the outer spinning roller 41 pass through the spinning roller movement groove and are located in the spinning roller movement groove. The inner spinning roller 42 and the outer spinning roller 41 may freely move in a radial direction and an axial direction along the blank. The blank radial direction refers to a direction perpendicular to the central axis of the blank. The axial direction of the blank refers to the direction parallel to the central axis of the blank workpiece. The diameter and width of the spinning roller movement groove shall be greater than the diameter of the inner spinning roller and outer spinning roller. The spinning roller movement groove is C-shaped, as shown in FIG. 5, so as to prevent the interference of spinning process.

The spinning device is provided with a control system for controlling the operation of the heat complementing system and the spinning system. The spinning device is further provided with a blank temperature measurement module, which is externally arranged on the heat complementing system, and the blank temperature measurement module is an infrared temperature measurement sensor for detecting the temperature of the blank located in the effective temperature complementing zone, so as to obtain the blank temperature T_blank or the spinning temperature T_spinning.

In the spinning process, only when the temperature of the blank reaches the pre-spinning temperature required by the process can the spinning be started. The pre-spinning temperature is obtained empirically or obtained by the calculation formula. The calculation formula of the pre-spinning temperature T_{b spinning} is as follows:

T b ⁢ spinning = T spinning - Δ ⁢ T

• • where T_spinning is the spinning temperature measured in the spinning deformation zone during the spinning process of the workpiece, in the unit of ° C.; the spinning temperature can be obtained according to the corresponding thermal processing map of workpiece material; for the spinning temperature of specific metal material as range value, it can be obtained by the material manual or thermal simulation test; ΔT is the temperature rise in ° C. caused by the heat generated by spinning deformation, and the calculation formula of ΔT is as follows:

Δ ⁢ T = Q m ⁢ C

• • where Q is the heat generated by plastic deformation, in the unit of J; m is the mass of blank, in the unit of kg; C is the specific heat capacity of the blank material, in the unit of J/(kg·° C.); the calculation formula for the heat Q generated by plastic deformation is as follows:

Q = θ * σ ¯ * ε ˙

• • where θ is the thermal effect coefficient of deformation, and 0.9 is generally taken in the plastic deformation of metals; θ is the equivalent stress at the deformation temperature, and it is convenient to calculate the yield strength σs of material at the deformation temperature; {dot over (ε)} is the equivalent strain rate of spinning deformation;

ε ˙ = n 2 ⁢ π ⁢ ln ⁡ ( 1 1 - φ )

• • where n is the rotational speed of the main shaft of the spinning, in the unit of r/min; φ is the spinning reduction rate; and

φ = t 0 - t f t 0 ,

• •  t0 and tf are the thickness of the blank before and after the spinning, respectively, in the unit of mm.

The near-isothermal hot spin forming process comprises the following steps.

• • (1) The blank is heated to a spinning preheat temperature of 1000° C. by a heating device. In the heating process, the set heating temperature of the heating device is 1000° C., and the blank is placed in the heating device and is required to be kept warm. The temperature-holding time is calculated according to the wall thickness of the blank by 0.4-0.8 min/mm, so that the temperature of the blank reaches 1000° C.
  • (2) The target complement temperature after the furnace body of the heat complementing system is closed is consistent with the spinning temperature required by the process. When the blank is to be placed into the workbench, the furnace body I and the furnace body II of the heat complementing system are away from the workbench to a certain distance to open the furnace body, and the time for opening the furnace body is controlled within 15 s.

The mechanical arm rapidly transfers and clamps the heated blank and fixes same on the working platform of the spinning device, and the furnace body I and the furnace body II of the heat complementing system are close to the working platform after the clamping, so that the furnace bodies are quickly closed, and the time for the furnace bodies to be closed is controlled within 15 s.

• • (3) The infrared temperature measurement sensor detects the temperature of the blank at this time, and the control system compares the temperature T_blank of the blank with the calculated pre-spinning temperature T_{b spinning}. If T_blank<T_{b spinning}, the heating and temperature complement is started for the blank by the heat complementing system which would adjust the heating power of the heating element, increase the temperature rising rate of the temperature complement, and increase the ambient temperature in the effective temperature zone of the heat complementing system, so as to supplement the temperature loss of the workpiece by actively complementing and heating the blank in the heat complementing time. If T_blank≥T_{b spinning}, the heat complementing system is started for complementing the blank, and the spinning device is started for spinning the workpiece according to the preset spinning program.
  • (4) In the spinning device, the spin forming is performed on the blank by the near-isothermal hot spinning process. The inner spinning roller and the outer spinning roller start hot spinning according to a pre-set movement track, the spinning start point of the pre-prepared groove channel movement knife on the furnace body of the heat complementing system, and the preset spinning trajectory. In the spinning process, it continues to use the heat complementing system to heat and temperature complement the blank. At the same time, the real-time monitoring and recording are performed on the deformation temperature in the spinning deformation zone of the blank, namely, the spinning temperature, so that the fluctuation of the spinning temperature during the process from the beginning to the end of spinning does not exceed ±20° C. The spinning process parameters were as follows. The rotation speed of the workbench for driving the blank to rotate is 100 revolutions/min; the feed ratio of the spinning roller is 0.5-0.8 mm/revolution; the fillet radius of the spinning roller is 1 t; the reduction rate of pass is 30%; and the spinning mode is positive spinning.

The formed part was inspected, and the wall thickness of the formed workpiece was uniform without crack defects. According to the mechanical property test standard for the workpiece of high-temperature alloy material, the mechanical properties of the workpiece meet the requirements in a plurality of test results. The grain size of the formed workpiece can reach Grades 7-9 after the test, indicating that the forming accuracy of the forming method of the present invention is very high, and the quality of the workpiece can be ensured, so as to meet the requirements of reliability and durability of the workpiece in various engineering applications.

Embodiment 2

The material of the blank is Ti64 titanium alloy. The initial wall thickness of the blank 5 before spinning is 26 mm, as shown in FIG. 6. After spinning, the wall thickness of the workpiece 6 is designed to be 15 mm, and the workpiece is a workpiece with a flange, as shown in FIG. 7. The spinning reduction rate is 42%, and it is made to 15 mm by two passes of spinning in the spinning design. The spinning of the workpiece is performed by the near-isothermal hot spinning. The spinning of this example is performed in the spinning device of Example 1.

The pre-spinning temperature of the Ti64 titanium alloy blank is obtained according to experience or is calculated according to the relationship between the spinning deformation temperature and the deformation temperature rise. In this embodiment, referring to the hot working drawing of Ti64 alloy and in combination with the production experience, the spinning temperature T_spinning is 30-50° C. below the phase transition point. In this embodiment, T_spinning is selected to be 900° C. According to this calculation, the pre-spinning temperature T_{b spinning} of the blank is about 870° C. The near-isothermal hot spin forming method comprises the following steps.

• • (1) The blank is heated to a spinning pre-heating temperature of 900° C. by the heating device. In the heating process, the set heating temperature of the heating device is 900° C., and the blank is placed in the heating device and is required to be kept warm. The temperature-holding time is calculated according to the wall thickness of the blank by 0.6-0.8 min/mm.
  • (2) The target complement temperature after the furnace body of the heat complementing system is closed is consistent with the spinning temperature required by the process. When the blank is to be placed into the workbench, the furnace body I and the furnace body II of the heat complementing system are away from the workbench to a certain distance to open the furnace body, and the time for opening the furnace body is controlled within 15 s.

The mechanical arm rapidly transfers and clamps the heated blank and fixes same on the working platform of the spinning device, and the furnace body I and the furnace body II of the heat complementing system are close to the working platform after the clamping, so that the furnace bodies are quickly closed, and the time for the furnace bodies to be closed is controlled within 15 s.

• • (3) The infrared temperature measurement sensor detects the temperature of the blank at this time, and the control system compares the temperature T_blank of the blank with the calculated pre-spinning temperature T_{b spinning}. If T_blank<T_{b spinning}, the heating and temperature complement is started for the blank by the heat complementing system which would adjust the heating power of the heating element, increase the temperature rising rate of the temperature complement, and increase the ambient temperature in the effective temperature zone of the heat complementing system, so as to supplement the temperature loss of the workpiece by actively complementing and heating the blank in the heat complementing time. If T_blank≥T_{b spinning}, the heat complementing system is started for complementing the blank, and the spinning device is started for spinning the workpiece according to the preset spinning program.
  • (4) In the spinning device, the spin forming is performed on the blank by the near-isothermal hot spinning process. The inner spinning roller and the outer spinning roller start hot spinning according to a pre-set movement track, the spinning start point of the pre-prepared groove channel movement knife on the furnace body of the heat complementing system, and the preset spinning trajectory. In the spinning process, it continues to use the heat complementing system to heat and temperature complement the blank. At the same time, the real-time monitoring and recording are performed on the deformation temperature in the spinning deformation zone of the blank, namely, the spinning temperature, so that the fluctuation of the spinning temperature during the process from the beginning to the end of spinning does not exceed ±20° C. The spinning process parameters were as follows. The rotation speed of the workbench for driving the blank to rotate is 180 revolutions/min; the feed ratio of the spinning roller is 1-1.2 mm/revolution; the fillet radius of the spinning roller is 1 t; the reduction rate of pass is 20-25%; and the spinning mode is positive spinning.

The above steps are repeated to complete two spinning passes until the blank reaches the design size of the workpiece. According to the mechanical property test standard for the titanium alloy workpiece, the mechanical properties of the workpiece meet the requirements in a plurality of test results, and the grain size of the formed workpiece can reach Grades 7-9.

For a person skilled in the art, when understanding the solutions described in the specific embodiments of the present invention, reference can be made to conventional technical manuals in the art. The reference can be made to make an appropriate understanding or adjustment in those places where the above-mentioned terms appear, and the same or similar technical solutions can be achieved without involving any inventive effort.

While the above-described embodiments illustrate only the basic principles, main features and/or advantages of the present invention, it will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and that the above-described embodiments and the summary of the invention are merely illustrative of the principles and embodiments of the invention. Without deviating from the essence of the innovative idea of the invention, the innovative solution of the invention has various changes and improvements, which fall within the scope of protection required by the invention.