SMX FORGING STRATEGY

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a national stage application, filed under 35 U.S.C. § 371, of International Patent Application PCT/EP2023/063572, filed on May 22, 2023, which claims the benefit of German Patent Applications DE 10 2022 206 670.7, filed on Jun. 30, 2022, and DE 10 2022 206 855.6, filed on Jul. 5, 2022.

TECHNICAL FIELD

The disclosure relates to a method for radial forging of a workpiece from an initial state to an end state by means of a radial forging machine, comprising forging tools, preferably four forging tools, arranged around the periphery of the workpiece, and a radial forging machine for carrying out such a method.

BACKGROUND

Radial forging machines are well known to the person skilled in the art and have a plurality of tools, usually four, which typically act on the workpiece simultaneously. This almost completely prevents the workpiece from widening, which means that the radial forging process typically only results in workpiece elongation when shaping from an initial state to an end state with corresponding geometries.

Once the workpiece has been shaped over its entire length, it is referred to as a forging cycle or a pass. During a pass, the workpiece is shaped by the repeated action of the tools, an action of the tools can also be referred to as a stroke or tool stroke. As a rule, the entire shaping of the workpiece is effected by a sequence of passes in the form of a pass schedule. Thus, a pass schedule consists of a plurality of passes and describes the development of the workpiece geometry from the initial state to the desired end state.

In principle, the shaping process on a radial forging machine can be divided into two types of shaping, namely, on the one hand, the shaping in which the workpiece structure is formed in such a manner that the required workpiece quality is achieved with the highest possible productivity, and, on the other hand, so-called finishing, in which the surface is correspondingly optimized. When finishing round cross-sections, a small angle of rotation with a small workpiece feed rate is typically used in order to achieve the smoothest and most attractive surface possible.

SUMMARY

The shaping process on a radial forging machine can be divided into two types of shaping, namely, on the one hand, the shaping in which the workpiece structure is formed in such a manner that the required workpiece quality is achieved with the highest possible productivity, and, on the other hand, so-called finishing, in which the surface is correspondingly optimized. When finishing round cross-sections, a small angle of rotation with a small workpiece feed rate is typically used in order to achieve the smoothest and most attractive surface possible.

Various forging strategies or modes of operation can be used in the radial forging machines:

A) The most common strategy is effected such that the workpiece shaping is carried out in a spiral forging mode. The workpiece is rotated by a defined angle after each tool stroke and moved in such a manner that a region that has not yet been fully shaped is shaped with the aid of the tools in the following stroke. This ensures that the tool completely covers the surface of the workpiece throughout the entire pass. In this spiral forging mode, the movement, i.e. the possible feed rate, is limited by the maximum tool length and the angle of rotation for rotating the workpiece. With this spiral forging strategy, all, preferably four, forging tools are always in motion with each stroke and thus participate in the shaping and shape the workpiece in the same shape.

B) A further known forging strategy is that all, preferably 4, forging tools also shape the workpiece with each stroke, but a workpiece rotation is not effected between the strokes. This strategy is referred to as “straight mode” and is somewhat similar to the common forging methods on open-die forging presses. By dispensing with workpiece rotation after a stroke, it is possible to increase the feed rate compared to the spiral forging strategy. When forging an octagonal cross-section, for example, there is no complete over-forging of the workpiece surface in this pass.

C) A forging strategy for radial forging machines that has only rarely been used to date is one in which the available tools are controlled in pairs. In doing so, opposite tools are controlled together and participate in the shaping, while other tools are controlled at a different point in time or with a different target dimension. This forging strategy is also referred to as flat mode. In flat mode, it is also possible for a pair of tools to remain on a target dimension during the pass and at least limit the free material flow in the lateral direction, which is caused by the pair of tools participating fully in the shaping.

Typically, one of the three forging strategies mentioned above is used to shape a workpiece. After the desired shaping has been effected, a finishing process is then typically effected to ensure an attractive surface, with shaping limited around the periphery of the workpiece to shape a workpiece with the desired final geometry and desired surface quality and appearance.

The present disclosure provides a method for radial forging of a workpiece along with a radial forging machine that is designed and configured to perform this method, which results in an optimized pass schedule and an optimized workpiece condition.

DETAILED DESCRIPTION

A method for radial forging a workpiece from an initial state to an end state is provided, wherein the radial forging is preferably effected following a pass schedule multiple times from an initial state to an end state by means of a radial forging machine, which comprises forging tools arranged around the periphery of the workpiece. Preferably, four forging tools are arranged around the periphery of the workpiece. The radial forging machine is designed and configured so that it can carry out radial forging in at least three modes of operation, namely A) in spiral mode, B) in straight mode and C) in flat mode. The shaping of the workpiece is effected from an initial state to an end state in a sequence of radial forging passes, wherein at least two of the three different modes of operation are applied consecutively, i.e. directly and without an intermediate pass.

The disclosure refers to a pass as a sequence of shaping processes in a predetermined mode of operation over the entire length of the workpiece or at least a predetermined partial length of the workpiece. The method for radial forging comprises at least two different and successive modes of operation, for example a first pass in spiral mode, followed by a second pass in straight mode, followed again by a third pass in spiral mode, possibly followed by a flat mode. Any conceivable combination of modes of operation in the pass sequence is covered by the concept in accordance with the disclosure as long as two successive passes implement different modes of operation. This means that the method also covers pass sequences with which a plurality of successive passes implement the same mode of operation, but are then followed by a different mode of operation. If necessary and preferred, a surface optimization is achieved at the end of the shaping process within the method by means of a finishing pass. The finishing pass is not taken into account as a shaping operation and therefore does not represent a separate mode of operation.

With the method in accordance with the disclosure, an improvement in the local change in shape and thus an improvement in product quality can be achieved. Additionally, a shortening of the process chain can be achieved by reducing pre-forging processes. The method enables a shaping method optimally adapted to the workpiece and its material quality, in particular with the best possible through-forging of the workpiece as a whole and taking into account the distribution of changes to shape within the workpiece.

It is preferable if the application and/or the order of the different modes of operation is effected as a function of the material of the workpiece. Advantageously, the specific requirements that need to be particularly considered for certain materials can be utilized when creating the pass schedule. In particular, it is preferable if different materials can be grouped into material classes, which can be subjected to the same sequence of modes of operation if necessary. These material classes are, for example: Carbon steels, heat-treatable steels, high-speed steels, cold-work steels, hot-work steels, rust and acid-resistant steels, nickel-based alloys, high-temperature steels and titanium alloys, to name but a few. Each material class can have special requirements with regard to the radial forging method, which can then have an influence on the selection of the modes of operation and the order of the modes of operation to be used, depending on the material.

In this connection, it is preferable if a rotation of the workpiece is effected about its longitudinal axis at a previously set angle of rotation after each forging tool stroke in the mode of operation of spiral mode. In doing so, it is preferable if all forging tools participate equally in the shaping.

In an equally preferred embodiment, no rotation whatsoever of the workpiece about its longitudinal axis is effected after each tool stroke in the mode of operation of straight mode. In this connection, it is particularly preferable if all forging tools participate equally in the shaping.

In a further preferred embodiment, in the mode of operation of flat mode, shaping is effected only by oppositely arranged forging tools, preferably by two oppositely arranged forging tools out of a total number of four forging tools arranged around the periphery of the workpiece. In flat mode, the tools that do not participate in a first shaping operation or only participate to a limited extent can be controlled differently with regard to time or shaping dimension than the forging tools described above that participate in the shaping. Likewise, the forging tools that do not participate in the shaping can only be positioned close to the workpiece in order to at least limit and preferably completely prevent a lateral widening of the workpiece during the radial forging process. Finally, the forging tools that do not participate in the shaping can of course also remain in an initial position and not make contact with the workpiece, at least for a limited time.

Preferably, the method is carried out with a control device, which is designed and configured to calculate an optimum pass sequence for the workpiece and then preset the radial forging machine such that the optimum pass sequence is carried out. In this connection, it is particularly preferable if the control of the radial forging machine is performed on the basis of a pass schedule calculation program, which generates an optimum pass sequence taking into account the optimum forging strategies. Preferably, in addition to the start and end geometry of the workpiece, the start temperature, for example the furnace temperature, and particularly preferably the material quality is also preset. The technology program can then calculate the best pass sequence using all possible forging strategies. It is particularly preferable if the intermediate dimensions after each tool stroke and the forging strategy are calculated in such a manner that the best distribution of changes to shape is achieved at the end of the pass sequence. This can be effected, for example, by comparing the distribution of changes to shape at the end of the process by calculating all possible combinations of pass sequences along with passes of different modes of operation. In particular, the design of the forging strategy is preferably effected taking into account the system force along with the available tool geometries.

A technology program for calculating pass schedules particularly suitable for such purposes is the Comforge® technology package, which, with its data on all industrially relevant materials, possesses all the prerequisites to calculate the corresponding pass schedules. Comforge® provides system operators with a comprehensive database for trouble-free and technologically proven forging processes. It is particularly preferable if an automation system monitors and controls all system components, control devices and sensors. As a result, through the appropriate application of the Comforge® technology package, the entire forging process from start to finish can be pre-calculated and modeled, including the geometry of the shaping, the forces thereby involved, the temperatures to be observed along with the time required for each pass throughout the entire forging process.

In accordance with a second aspect, a radial forging machine is provided for carrying out the method in accordance with the first aspect of the disclosure. The radial forging machine is provided with a control device, which is designed and configured to perform the control of the radial forging machine on the basis of a pass schedule calculation program. This pass schedule calculation program gives priority to the start and desired end geometry along with the start temperature of the radial forging process along with the material quality of the workpiece itself.

In this connection, it is particularly preferable if the pass schedule calculation program also takes into account intermediate dimensions of the workpiece with the aim of achieving an optimum distribution of changes to shape on the workpiece.

The system operator is provided with a method and a radial forging machine intended for this purpose, which are capable of enabling optimum shaping of the workpiece adapted to the material quality and using a sequence of comparatively easily controllable processes.