SHOT PROCESSING APPARATUS AND METHOD FOR DETECTING ABNORMALITY OF NOZZLE

Description

TECHNICAL FIELD

The present disclosure relates to a shot processing apparatus and a method for detecting an abnormality of a nozzle. This application claims priority from Japanese Patent Application No. 2024-207101 filed on November 28, 2024, and Japanese Patent Application No. 2025-117519 filed on July 11, 2025, the entire contents of both of which are incorporated herein by reference.

BACKGROUND

A nozzle of a shot processing apparatus intensely projects shot media, so that its interior is gradually worn. When shot processing is continued with a worn nozzle, the projection pressure and the density of the shot media are reduced. As a result, the processing accuracy is affected which can lead to the occurrence of products with processing defects. Therefore, in this technical field, it is desired to detect wear of the nozzle at an earlier stage.

The nozzle disclosed in Japanese Unexamined Patent Publication No. 2021-62433 has, on its outer circumferential surface, a detection part that detects the usage limit of the nozzle. The thickness of the wall of the detection part is less than that of the walls of the portions other than the detection part, so that the detection part is worn earlier than the portions other than the detection part. An operator detects the usage limit of the nozzle by a through hole forming in the detection part due to wear and the shot media flowing out to the outside.

SUMMARY

When the nozzle is damaged due to wear and the shot media flows out therefrom to the outside during shot processing, the projection pressure is reduced. As a result, the processing accuracy is affected which can lead to the occurrence of products with processing defects. That is, in the nozzle disclosed in Patent Literature 1, the frequency at which the shot media flows out of the nozzle is higher compared to ordinary nozzles, so that there is a risk that the frequency of occurrence of products with processing defects increases. In this technical field, it is desired to detect abnormalities such as wear of the nozzle before the nozzle is damaged. The present disclosure provides a technology that enables an abnormality of a nozzle to be detected before the processing accuracy is affected.

A shot processing apparatus according to one aspect of the present disclosure includes: a storage part configured to store a shot media; a nozzle configured to project, together with compressed air, the shot media sucked in by negative pressure; a conveyance path configured to convey the shot media from the storage part to the nozzle; a compressed air supply part configured to supply the compressed air to the nozzle; a pressure gauge configured to detect a pressure in the conveyance path; and an abnormality detection part configured to detect an abnormality of the nozzle based on a detection result from the pressure gauge.

A method for detecting an abnormality of a nozzle according to another aspect of the present disclosure is a method for detecting an abnormality of a nozzle of a shot processing apparatus configured to project, together with compressed air, a shot media sucked in by negative pressure, the method including: detecting a pressure in a conveyance path configured to convey the shot media from a storage part to the nozzle; and detecting an abnormality of the nozzle based on a detection result of the pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram of a shot processing apparatus according to a first embodiment.

FIG. 2 is a configuration diagram of a shot processing apparatus according to a second embodiment.

FIG. 3 is a graph illustrating the results of experimentally examining the relationship between projection pressure and negative pressure when the shot processing apparatuses according to the first and second embodiments are used.

FIG. 4 is a graph illustrating the results of experimentally examining the relationship between nozzle diameter and negative pressure for each nozzle projection pressure.

FIG. 5 is a flowchart illustrating a method for detecting an abnormality of a nozzle according to an embodiment.

DETAILED DESCRIPTION

Embodiments will be described below with reference to the drawings. Same reference signs are given to the same or corresponding elements in the description below, and redundant explanation will be omitted. The scale of dimensions in the drawings is not necessarily consistent with those in the description. The terms “upper,” “lower,” “left,” and “right” are based on the illustrated state and are used for convenience.

Shot Processing Apparatus

FIG. 1 is a configuration diagram of a shot processing apparatus according to a first embodiment. A shot processing apparatus 1 illustrated in FIG. 1 is an apparatus for performing surface treatment such as blasting and shot peening by projecting shot media 2 toward a workpiece W. The shot processing apparatus 1 includes a hopper 3 (storage part) that stores the shot media 2, a nozzle 4, a hose 5 (conveyance path), a compressor 6 (compressed air supply part), a vacuum gauge 7 (pressure gauge), and a control part 10.

At a lower end part 21 of the hopper 3, an end part 23 of a large diameter pipe 22 (conveyance path) and an end part 25 of a small diameter pipe 24 are disposed so as to be inserted from opposite sides. The large diameter pipe 22 and the small diameter pipe 24 form a shot media feed device 20. The end part 23 is cut diagonally. The end part 25 is disposed so as to be inserted into the end part 23. A gap 26 into which the shot media 2 can enter is formed between an inner surface of the end part 23 and an outer surface of the end part 25.

The other end of the pipe 22 is located outside the hopper 3 and is coupled to one end of the hose 5 by a metal coupling pipe 27 (conveyance path). The other end of the hose 5 is coupled to the nozzle 4. The hose 5, the pipe 22, and the coupling pipe 27 form a conveyance path that conveys the shot media 2 from the hopper 3 to the nozzle 4. The vacuum gauge 7 is attached to the coupling pipe 27 that forms a part of the conveyance path of the shot media 2, and detects the pressure in the conveyance path. The vacuum gauge 7 may be attached to the path (hose 5) from the hopper 3 to the nozzle 4 or may be attached to the nozzle 4. The vacuum gauge 7 is, for example, a pressure sensor. The other end of the pipe 24 is located outside the hopper 3. The other end of the pipe 24 is connected to a valve 28. When the valve 28 is opened, the pipe 24 is opened to atmospheric pressure.

The nozzle 4 sucks the shot media 2 into the nozzle 4 by negative pressure generated inside the nozzle 4. The nozzle 4 mixes the shot media 2 with compressed air inside the nozzle 4 and projects the shot media 2 together with the compressed air as a gas–solid two-phase flow. The nozzle 4 is a so-called suction nozzle. The nozzle 4 includes a nozzle body 30, a nozzle tip 31, and an air jet nozzle 32. The nozzle body 30 has a body conduit 33 and a shot media introduction conduit 34. The body conduit 33 extends in one direction. The shot media introduction conduit 34 joins the body conduit 33 at an oblique angle from the side. The shot media introduction conduit 34 is connected to the hose 5.

The body conduit 33 has a narrow diameter part 35, a central enlarged diameter part 36, and a tip enlarged diameter part 37. The air jet nozzle 32 is fitted into the narrow diameter part 35. The nozzle tip 31 is fitted into the tip enlarged diameter part 37. The nozzle tip 31 includes a shot media projection hole 31a that extends in its central axis direction. The shot media projection hole 31a has an inner diameter smaller than an inner diameter of the central enlarged diameter part 36 of the body conduit 33.

The air jet nozzle 32 includes a compressed air projection hole 32a that extends in its central axis direction. A tip end part of the air jet nozzle 32 is located inside the central enlarged diameter part 36. The compressed air projection hole 32a has an inner diameter smaller than the inner diameter of the central enlarged diameter part 36. During operation of the shot processing apparatus 1, the inside of the central enlarged diameter part 36 is under negative pressure as described below. The other end of the air jet nozzle 32 is located outside the nozzle body 30.

The compressor 6 is connected to the other end of the air jet nozzle 32 and supplies the compressed air to the nozzle 4. The compressed air supplied from the compressor 6 is supplied to the air jet nozzle 32 and is blown out of the nozzle 4 from a tip end of the air jet nozzle 32 through the nozzle tip 31. The compressed air is introduced into the nozzle tip 31 having a small inner diameter dimension through the central enlarged diameter part 36 having a large inner diameter dimension, so that the pressure in the central enlarged diameter part 36 becomes negative due to the Venturi effect. As a result, negative pressure is generated in the shot media introduction conduit 34 and the hose 5.

Due to this negative pressure, the shot media 2 is sucked into the pipe 22, together with the air opened to atmospheric pressure, from the gap 26 between the end part 23 of the pipe 22 and the end part 25 of the pipe 24. The shot media 2 sucked in passes through the hose 5 and is conveyed to the nozzle 4. The conveyed shot media 2 passes through the shot media introduction conduit 34 of the nozzle body 30, is mixed with the compressed air blowing out from the tip end of the air jet nozzle 32 at the central enlarged diameter part 36, and is projected toward the workpiece W from a tip end of the nozzle tip 31.

The control part 10 is a device that integrally controls the shot processing apparatus 1. The control part 10 is formed, for example, as a programmable logic controller (PLC). The control part 10 may be formed as a computer system including a processor such as a central processing unit (CPU), a memory such as a random access memory (RAM) and a read only memory (ROM), an input/output device such as a touch panel, a mouse, a keyboard, and a display, and a communication device such as a network card. The functions of the control part 10 are implemented by operating each hardware under the control of the processor based on the computer program stored in the memory. The control part 10 may be incorporated as a circuit. The control part 10 may be realized by a plurality of control parts (i.e., it may be physically divided).

The control part 10 has a threshold setting part 51, an abnormality detection part 52, and a warning part 53 as individual function processing parts. Each function processing part is, for example, a region on a control board that forms the control part 10 and is composed of an IC chip, a buffer, and the like. The control part 10 is communicably connected to the vacuum gauge 7 and the valve 28.

The threshold setting part 51 is a function processing part that sets a normal range of the negative pressure, for example, based on a projection pressure and an inner diameter of the nozzle 4 (specifically, an initial value of the inner diameter of the nozzle tip 31) currently in use (or to be used) in the shot processing apparatus 1. The threshold setting part 51 stores in advance in a database the upper and lower limits of the normal range of the negative pressure, for example, for each projection pressure and inner diameter of the nozzle 4 usable in the shot processing apparatus 1. These thresholds are, for example, input to the threshold setting part 51 via an input device during manufacture of the shot processing apparatus 1 and stored in a storage part in the threshold setting part 51.

When the projection pressure and the inner diameter of the nozzle 4 currently in use in the shot processing apparatus 1 are input, the threshold setting part 51 refers to the database in the storage part and sets the lower and upper limits of the normal range of the negative pressure corresponding to the input projection pressure and inner diameter as the thresholds. The threshold setting part 51 is configured so as to be able to output the set thresholds to the abnormality detection part 52. The projection pressure and the inner diameter of the nozzle 4 currently in use are input to the threshold setting part 51, for example, by an input operation by an operator using an input device. It can be said that the normal range of the negative pressure is set corresponding to the projection pressure and the inner diameter of the nozzle 4 currently in use.

In a case where the shot processing apparatus 1 is a dedicated machine used only at a specific nozzle projection pressure and a specific nozzle diameter, the upper and lower limits of the normal range of the negative pressure may be set in advance as the thresholds in the shot processing apparatus 1. In this case, the threshold setting part 51 may simply be a storage part that stores the thresholds in advance, or the shot processing apparatus 1 need not include the threshold setting part 51.

FIG. 2 is a configuration diagram of a shot processing apparatus according to a second embodiment. A shot processing apparatus 101 according to the second embodiment will be described below focusing on the portions different from the shot processing apparatus 1 illustrated in FIG. 1. The shot processing apparatus 101 illustrated in FIG. 2 includes a hopper 102 (storage part) that stores the shot media 2, a quantitative supply device 103 (conveyance path), a receiving container 104 (conveyance path), a hose 105 (conveyance path), the nozzle 4 (conveyance path), the hose 5 (conveyance path), the compressor 6 (compressed air supply part), the vacuum gauge 7, and the control part 10. The configurations of the shot media 2, the nozzle 4, the hose 5, the compressor 6, the vacuum gauge 7, and the control part 10 are the same as those in the shot processing apparatus 1.

The quantitative supply device 103 has a trough 106, a screw 107, a motor 108, and a regulating plate 109. The trough 106 has a cylindrical shape closed at both ends. One end part 106a of the trough 106 is located below the hopper 102 and a supply port 106c is formed on an upper surface thereof. The supply port 106c is coupled to a lower end part of the hopper 102. A discharge port 106d is formed on a lower surface of the other end part 106b of the trough 106.

The screw 107 is housed in the trough 106. The screw 107 includes a conveyance shaft 107a and blades 107b. The conveyance shaft 107a penetrates a side wall that closes the end part 106a and is coupled to the motor 108. The blades 107b are fixed helically to an outer circumferential surface of the conveyance shaft 107a such that two adjacent blades 107b are arranged at predetermined intervals. The motor 108 rotates the screw 107. The control part 10 may be communicably connected to the motor 108.

The regulating plate 109 is a member for increasing a bulk density (filling ratio) of the shot media 2 in the trough 106. The regulating plate 109 has a shape that partitions an inner space of the trough 106. In this embodiment, the regulating plate 109 is a circular plate-like member. The regulating plate 109 is provided at a tip end of the conveyance shaft 107a and is fixed to the tip end of the conveyance shaft 107a. A peripheral part of the regulating plate 109 may be fixed to an inner wall of the trough 106. The regulating plate 109 is provided with one or more through holes through which the shot media 2 can pass. The one or more through holes extend through the regulating plate 109 in a direction in which the conveyance shaft 107a extends. An open area ratio of the regulating plate 109 is set according to the particle size, the desired bulk density, and the like, of the shot media 2. The open area ratio of the regulating plate 109 is the proportion of the area enclosed by an outer circumference of the regulating plate 109 that is occupied by the one or more through holes when the regulating plate 109 is viewed in a direction in which the conveyance shaft 107a extends.

A fixed amount of the shot media 2 stored in the hopper 102 is introduced into the trough 106 from the supply port 106c and advances at a constant speed from the end part 106a toward the end part 106b by the rotation of the screw 107. When the shot media 2 reaches the regulating plate 109, the air between the particles of the shot media 2 is removed by the shot media 2 being compressed by the regulating plate 109, thereby increasing the bulk density of the shot media 2. The bulk density of the shot media 2 thus reaches a predetermined density just before the regulating plate 109 and forms a large mass. This mass is broken up as it passes through the one or more through holes and the shot media 2 reaches the end part 106b. Since the conveyance shaft 107a is not disposed in the end part 106b, the shot media 2 that has passed through the regulating plate 109 does not adhere to the conveyance shaft 107a and is discharged from the discharge port 106d to the outside.

The receiving container 104 is disposed below the discharge port 106d and receives the shot media 2 discharged from the quantitative supply device 103 in fixed amounts. The receiving container 104 has a funnel shape and discharges the shot media 2 from a lower end opening. One end of the hose 105 is connected to the lower end opening of the receiving container 104 and the other end of the hose 105 is connected to the coupling pipe 27. The coupling pipe 27 couples the hose 105 and the hose 5. The quantitative supply device 103, the receiving container 104, the hose 105, the coupling pipe 27, and the hose 5 form the conveyance path that conveys the shot media 2 from the hopper 102 to the nozzle 4. The vacuum gauge 7 may be attached to the receiving container 104, the hose 105, the hose 5, or the nozzle 4.

In the shot processing apparatus 101, the quantitative supply device 103 and the receiving container 104 are not physically connected and the conveyance path from the hopper 102 to the nozzle 4 is open to atmospheric pressure at an intermediate point. By the conveyance path being open to atmospheric pressure at an intermediate point in this manner, chattering in the measured values from the vacuum gauge 7 is suppressed, thereby suppressing variation in the measured values of the negative pressure. Consequently, the sampling interval can be reduced in the shot processing apparatus 101. In the shot processing apparatus 1 (first embodiment), chattering tends to occur more than in the shot processing apparatus 101 (second embodiment), but the negative pressure can be measured by increasing the sampling interval of the data or by performing a smoothing operation on the obtained data. Since the shot processing apparatus 101 can directly measure the negative pressure, the measurement accuracy is high and an abnormality of the nozzle can be detected with higher accuracy.

FIG. 3 is a graph illustrating the results of experimentally examining the relationship between the projection pressure (MPa) and the negative pressure (kPa) when the shot processing apparatuses according to the first and second embodiments are used. The data of the shot processing apparatus of the first embodiment is obtained by smoothing the sampled data. As illustrated in FIG. 3, a similar trend in the negative pressure was observed regardless of the shot processing apparatus used.

FIG. 4 is a graph illustrating the results of experimentally examining the relationship between the nozzle diameter and the negative pressure for each nozzle projection pressure. In this experiment, a blasting apparatus having a configuration corresponding to that of the shot processing apparatus 101 was used, and iron nozzles having nozzle diameters of 8 mm, 8.5 mm, 9 mm, and 9.5 mm were attached to measure the negative pressure. The projection conditions were such that only projection air was used (no shot media). The nozzle projection pressure (set pressure of the compressor) was set to 0.2 MPa, 0.3 MPa, 0.4 MPa, and 0.5 MPa. As illustrated in FIG. 4, there is a clear correlation between the nozzle diameter and the negative pressure, and as the nozzle diameter increases, the negative pressure decreases. Additionally, the negative pressure tends to decrease as the nozzle projection pressure increases. As is apparent from the experimental results in FIG. 3, the same trend is observed when a blasting apparatus that has a configuration corresponding to that of the shot processing apparatus 1 is used.

In a case where the nozzle diameter (initial value) is 8 mm, a range R1 from 8 mm to 9 mm, for example, can be defined as the normal range of the nozzle diameter. The range of the negative pressure corresponding to the range R1 is the normal range of the negative pressure. The normal range of the negative pressure varies depending on the projection pressure. Additionally, when the nozzle diameter is different, the range R1 is different, and the normal range of the negative pressure is also different. Therefore, the threshold setting part 51 stores the lower and upper limits of the normal range of the negative pressure for each nozzle projection pressure and nozzle diameter as described above.

In the example of FIG. 4, ranges R2, R3, and R4 of the nozzle diameter are each outside the normal range. In the ranges R2 and R3 where the nozzle diameter exceeds 9 mm, the nozzle (specifically, the nozzle tip) is worn. When shot processing is performed with a worn nozzle, the surface finish of the workpiece W may deteriorate, making it necessary to replace the nozzle tip. Here, the range R2 defined for the nozzle diameters from 9 mm to 9.5 mm is particularly provided, and the negative pressure range corresponding to the range R2 is set as a range in which the user is prompted to perform visual inspection and replace the nozzle as necessary. The range R3 is a range in which the nozzle diameter exceeds 9.5 mm. The negative pressure range corresponding to the range R3 is set as a range in which the user is prompted to immediately replace the nozzle.

The range R4 is a range in which the nozzle diameter is less than 8 mm. The nozzle diameter after use does not normally fall below a set value (initial value). Consequently, if the negative pressure indicates a value in the negative pressure range corresponding to the range R4, there is a possibility that a nozzle abnormality has occurred, such as mistakenly attaching a nozzle having a smaller diameter than the nozzle that should originally be attached. Therefore, in this embodiment, the negative pressure range corresponding to the range R4 is set as a range in which the user is prompted to perform visual inspection and replace the nozzle as necessary.

The threshold setting part 51 stores the thresholds of the negative pressure range corresponding not only to the range R1 but also to the ranges R2, R3, and R4 for each projection pressure and nozzle diameter of the nozzle 4. The thresholds of the negative pressure range corresponding to the range R2 include the lower and upper limits. The threshold of the negative pressure range corresponding to the range R3 includes only the upper limit. The threshold of the negative pressure range corresponding to the range R4 includes only the lower limit.

For example, at a site where only the nozzle 4 with a nozzle diameter of 8 mm is used, it is unlikely that the nozzle 4 will be incorrectly attached, and thus the range R4 may be included in the normal range of the nozzle diameter. In this case, the threshold of the normal range of the negative pressure corresponding to the ranges R2 and R4 includes only the lower limit.

The abnormality detection part 52 is a function processing part that detects an abnormality of the nozzle 4 based on a detection result from the vacuum gauge 7. Specifically, the abnormality detection part 52 obtains the detection result from the vacuum gauge 7, which the control part 10 monitors, and the thresholds from the threshold setting part 51 to determine whether there is an abnormality of the nozzle 4. The abnormality detection part 52 determines that there is an abnormality in the nozzle 4 when the detection result is outside the normal range.

In particular, when the detection result from the vacuum gauge 7 is lower than the normal range set in advance, the abnormality detection part 52 determines that the nozzle 4 is worn and the inner diameter of the nozzle 4 is greater than a design value. If the detection result from the vacuum gauge 7 is higher than the normal range set in advance, the abnormality detection part 52 determines that the inner diameter of the nozzle 4 is smaller than the design value due to an incorrect attachment of the nozzle 4.

The abnormality detection part 52 performs an abnormality detection process for the nozzle 4 based on the detection result from the vacuum gauge 7 in a state where the shot media 2 is not supplied from the hoppers 3, 102 to the nozzle 4, and the compressed air is supplied from the compressor 6 to the nozzle 4. The abnormality detection part 52 outputs an abnormality detection result for the nozzle 4 to the warning part 53.

The warning part 53 is a function processing part that receives the abnormality detection result for the nozzle 4 from the abnormality detection part 52 and issues a warning to the operator regarding the abnormality of the nozzle 4. The warning part 53 displays, for example, a warning using a display. This enables the operator to replace the nozzle 4 at an appropriate timing. The warning part 53 may display that there is no abnormality in the nozzle 4 when no abnormality is detected in the nozzle 4.

Method for Detecting an Abnormality of a Nozzle

FIG. 5 is a flowchart illustrating a method for detecting an abnormality of a nozzle according to an embodiment. The method for detecting an abnormality according to the embodiment detects an abnormality of the nozzle 4 of the shot processing apparatuses 1, 101 that project, together with compressed air, the shot media 2 sucked in by negative pressure. As illustrated in FIG. 5, the method for detecting an abnormality includes steps S1 to S6.

The method for detecting an abnormality is performed when the shot processing apparatuses 1, 101 are not carrying out shot processing. The method for detecting an abnormality may, for example, be performed as a pre-operation inspection before the shot processing apparatuses 1, 101 are operated, or by temporarily suspending the operation of the shot processing apparatus 1, 101. The method for detecting an abnormality may, for example, be started based on a start instruction input by the operator via an input device such as a touch panel. As an example, the operator may select an automatic equipment diagnostic mode from an operation screen of the touch panel and press a start button to input the start instruction.

The step S1 is a threshold setting step in which the threshold setting part 51 sets the thresholds of the normal range of the negative pressure. For example, the threshold setting part 51 sets the corresponding thresholds of the normal range of the negative pressure based on the projection pressure and the inner diameter of the nozzle 4 currently in use (or to be used) input by the operator via the input device such as a touch panel. As described above, in the case where the shot processing apparatuses 1, 101 are dedicated machines, the thresholds of the normal range of the negative pressure is set in advance in the shot processing apparatuses 1, 101, so that the method for detecting an abnormality need not include the step S1.

The step S2 is a shot media supply stopping step of stopping the supply of the shot media 2 from the hoppers 3, 102 to the nozzle 4. In the case of the shot processing apparatus 1, the valve 28 is closed by an instruction from the control part 10 in the step S2. This stops the supply of the shot media 2 from the hopper 3 to the nozzle 4 even when negative pressure is generated in the nozzle 4 since a pressure difference does not occur in the conveyance path. In the case of the shot processing apparatus 101, the operator stops the operation of the motor 108 in the step S2. This stops the supply of the shot media 2 from the hopper 102 to the nozzle 4.

The step S3 is a compressed air supply step of operating the compressor 6 at a predetermined pressure set in advance and supplying the compressed air to the nozzle 4. This causes negative pressure to be generated in the nozzle 4. Additionally, air is projected from the nozzle 4 at a projection pressure corresponding to the set pressure of the compressor 6.

The step S4 is a pressure detection step of detecting the pressure (negative pressure) in the conveyance path that conveys the shot media 2 from the hoppers 3, 102 to the nozzle 4. The step S4 is performed by the vacuum gauge 7. The step S4 detects the pressure in the conveyance path in the state where the shot media 2 is not supplied to the nozzle 4 and the compressed air is supplied to the nozzle 4. The step S4 is performed after the steps S2 and S3 are performed.

The step S5 is an abnormality detection step of detecting an abnormality of the nozzle 4 based on the detection result of the pressure detected in the step S4. The step S5 is performed by the abnormality detection part 52.

The step S6 is a warning step of issuing a warning regarding an abnormality of the nozzle 4 when an abnormality of the nozzle 4 is detected by the step S5. The step S6 is performed by the warning part 53 using an output device such as a display. For example, the abnormality detection result for the nozzle 4 may be displayed on a screen of a touch panel as a diagnostic result of an automatic equipment diagnostic mode. If there is no abnormality, the processing using the shot processing apparatuses 1, 101 may be continued without replacing the nozzle 4. If there is an abnormality, visual inspection is performed and the nozzle 4 can be replaced as necessary.

Advantageous Effects of the Present Disclosure

As described above, in the shot processing apparatuses 1, 101 and the method of detecting an abnormality of the nozzle 4 according to the embodiments, an abnormality of the nozzle 4 is detected based on the detection result from the vacuum gauge 7 connected indirectly or directly to the nozzle 4. Since the abnormality of the nozzle 4 can be detected before performing the shot processing, an impact on the processing accuracy of the shot processing caused by an abnormality of the nozzle 4 can be prevented from occurring. That is, the abnormality of the nozzle 4 can be detected before the processing accuracy of the shot processing is affected.

The method of this embodiment enables quantitative evaluation, so that human measurement errors can be suppressed, for example, compared with the conventional method of inserting a go gauge into the nozzle to inspect the nozzle for wear. In the method using a go gauge, the go gauge may get caught when inserting or removing the go gauge and damage such as chipping may occur in the nozzle. In contrast, the method of this embodiment makes it possible to detect an abnormality of the nozzle 4 without damaging the nozzle 4 compared with the method of directly inspecting the wear condition of the nozzle 4 by using a physical measurement instrument such as a go gauge.

In some cases, measurements using a go gauge may not be possible unless the nozzle 4 is removed. The nozzle 4 is disposed in a processing chamber, so that, in order to remove the nozzle 4, the operator must open a work door leading to the processing chamber and perform the work. This embodiment enables abnormality detection without removing the nozzle 4. Thus, the efforts required for removing the nozzle 4 and opening and closing the work door are reduced, and the time required for abnormality detection can be reduced. The time can also be reduced since there is no need to check reproducibility upon restoration. Health hazards caused by the operator entering the processing chamber and inhaling dust can be suppressed.

Although the embodiments have been described above, it will be understood that the present invention is not limited to these embodiments, and various modifications may be made without departing from the gist thereof.

In the first embodiment above, the abnormality detection part 52 performs the abnormality detection process for the nozzle 4 in the state where the shot media 2 is not supplied from the hopper 3 to the nozzle 4 by closing the valve 28, but the abnormality detection process for the nozzle 4 may be performed in a state where the shot media 2 is supplied from the hopper 3 to the nozzle 4 without closing the valve 28. In the second embodiment above, the abnormality detection process for the nozzle 4 is performed in the state where the shot media 2 is not supplied from the hopper 102 to the nozzle 4 by the operator stopping the operation of the motor 108, but the abnormality detection process for the nozzle 4 may be performed in a state where the shot media 2 is supplied from the hopper 102 to the nozzle 4 without stopping the operation of the motor 108. The method for detecting an abnormality need not include the shot media supply stopping step of the step S2.

In the first embodiment above, the pipe 24 is connected to the valve 28 and is opened to atmospheric pressure only when the valve 28 is opened, but the pipe 24 need not be connected to the valve 28 and may be constantly open to atmospheric pressure. In this case, for example, the abnormality detection process may be performed by the abnormality detection part 52 in a state where the shot media 2 is not stored in the hopper 3. Since the shot media 2 is not stored in the hopper 3, the state where the shot media 2 is not supplied from the hopper 3 to the nozzle 4 can be achieved even if negative pressure is generated inside the nozzle 4. Since the variation in the measured values is reduced, the measurement accuracy is increased.

In the first embodiment above, the hopper 3 and the nozzle 4 form a space in communication with each other together with the shot media feed device 20, the coupling pipe 27, and the hose 5, but the hopper 3 and the nozzle 4 need not form a space in communication with each other. Also in this case, for example, the shot media 2 can be supplied to the nozzle 4 independently of the negative pressure by the shot processing apparatus 1 including a quantitative supply device instead of the shot media feed device 20. The quantitative supply device, for example, has a screw provided at the lower end part 21 of the hopper 3 and delivers a fixed amount of the shot media 2 to a supply port by the rotation of the screw and supplies it to the other end of the hose 5 opened to the atmosphere. By stopping the operation of the quantitative supply device, the state where the shot media 2 is not supplied from the hopper 3 to the nozzle 4 can be achieved even if negative pressure is generated inside the nozzle 4. Since the variation in the measured values is reduced, the measurement accuracy is increased.

In the embodiments above, the wear of the nozzle tip 31 is detected as the wear of the nozzle 4, but the wear of the air jet nozzle 32 can also be detected. The shot media 2 is introduced into the nozzle body 30 through the shot media introduction conduit 34 and impinges on the air jet nozzle 32, causing wear of the air jet nozzle 32. The distance between the tip end of the air jet nozzle 32 and a wall surface of the inside of the nozzle body 30 changes due to the wear of the air jet nozzle 32 and affects the negative pressure.

In the embodiments above, when the detection result from the vacuum gauge 7 is lower than the normal range set in advance, the abnormality detection part 52 determines that the nozzle 4 is worn and the inner diameter of the nozzle 4 is greater than the design value, but it may determine, immediately after replacing the nozzle 4, that the inner diameter of the nozzle 4 is greater than the design value due to an incorrect attachment of the nozzle 4. When replacing the worn nozzle 4 with a new nozzle 4, human errors may occur such as reattaching the original worn nozzle 4 or attaching a nozzle 4 with a larger diameter than intended. Performing the abnormality detection process for the nozzle 4 immediately after replacing the nozzle 4 makes it possible to detect such incorrect attachment of the nozzle 4.

Summary of Embodiments of the Present Disclosure

The present disclosure includes the following aspects.

Clause 1. A shot processing apparatus, comprising:

a storage part configured to store a shot media;

a nozzle configured to project, together with compressed air, the shot media sucked in by negative pressure;

a conveyance path configured to convey the shot media from the storage part to the nozzle;

a compressed air supply part configured to supply the compressed air to the nozzle;

a pressure gauge configured to detect a pressure in the conveyance path; and

an abnormality detection part configured to detect an abnormality of the nozzle based on a detection result from the pressure gauge.

Clause 2. The shot processing apparatus according to clause 1, wherein the abnormality detection part performs an abnormality detection process for the nozzle based on the detection result from the pressure gauge in a state where the shot media is not supplied from the storage part to the nozzle and the compressed air is supplied from the compressed air supply part to the nozzle.

Clause 3. The shot processing apparatus according to clause 1, wherein the abnormality detection part determines that there is an abnormality in the nozzle when the detection result from the pressure gauge is outside a normal range set in advance.

Clause 4. The shot processing apparatus according to clause 3, wherein the abnormality detection part determines that the nozzle is worn when the detection result is lower than the normal range.

Clause 5. The shot processing apparatus according to clause 3, wherein the abnormality detection part determines that an incorrect attachment of the nozzle has occurred when the detection result is higher than the normal range.

Clause 6. The shot processing apparatus according to any one of clauses 3 to 5, wherein the normal range is set corresponding to a projection pressure of the nozzle.

Clause 7. The shot processing apparatus according to any one of clauses 3 to 6, wherein the normal range is set corresponding to an inner diameter of the nozzle.

Clause 8. The shot processing apparatus according to any one of clauses 1 to 7, wherein the conveyance path is open to atmospheric pressure at an intermediate point.

Clause 9. A method for detecting an abnormality of a nozzle of a shot processing apparatus configured to project, together with compressed air, a shot media sucked in by negative pressure, the method comprising:

detecting a pressure in a conveyance path configured to convey the shot media from a storage part to the nozzle; and

detecting an abnormality of the nozzle based on a detection result of the pressure.

In the shot processing apparatus of clause 1, the abnormality of the nozzle is detected based on the detection result from the vacuum gauge, thereby enabling the abnormality of the nozzle to be detected before the processing accuracy is affected.

In the shot processing apparatus of clause 2, the abnormality detection process for the nozzle is performed without the shot media, thereby eliminating the influence of the type of the shot media on the detection result.

In the shot processing apparatus of clause 3, the abnormality of the nozzle can be easily determined.

In the shot processing apparatus of clause 4, the wear of the nozzle can be easily determined.

In the shot processing apparatus of clause 5, the incorrect attachment of the nozzle can be easily determined.

In the shot processing apparatus of clause 6, the abnormality of the nozzle can be determined for each projection pressure of the nozzle.

In the shot processing apparatus of clause 7, the abnormality of the nozzle can be determined for each inner diameter of the nozzle.

In the shot processing apparatus of clause 8, the variation in the measured values is suppressed, thereby increasing the measurement accuracy.

In the method for detecting an abnormality of a nozzle of clause 9, the abnormality of the nozzle is detected based on the detection result of the pressure, thereby enabling the abnormality of the nozzle to be detected without damaging the nozzle.