Process monitoring for freeform forging

Abstract

The invention relates to a method for monitoring and adjusting a freeform forging process, the method comprising the steps of: a) calculating the geometry development of a workpiece during the freeform forging using an empirical model; b) calculating the workpiece temperature on the cross-section of the forged workpiece in parallel with step a), i.e. Simultaneously with step a) or at least partially overlapping in time; c) calculating a shape change distribution along the length of the workpiece, preferably using the geometry development calculated in step a); and d) manually or automatically adjusting the shape change distribution within a predetermined range as a function of the shape change distribution calculated in step c). The invention also relates to a free-forming forging press designed and arranged to carry out the method.

Description

Technical Field

[0001] The invention relates to a method for monitoring and regulating a free-form forging press and to a free-form forging press which is connected to a control and regulating unit and is designed and configured to carry out the method. Background Art

[0002] Free-form forging is a forming technology belonging to forging, the purpose of which is to improve the mechanical properties of the workpiece and to produce blanks. In free-form forging, the workpiece is formed under pressure using tools that move relative to each other, wherein the tools can be flat or partially have the shape of the workpiece itself. The shape of the workpiece is produced by targeted guidance of the workpiece and by controlling the forming forces of the tool on the workpiece. In this process, it is usually necessary to make several machining passes of the tool until the workpiece has the desired shape.

[0003] In this case, the workpiece is usually gripped by means of a forging manipulator and is gradually formed over the entire length to be formed between a foot line at the beginning of the area to be formed and a cover line at the end of the area to be formed. The length of the workpiece can therefore be determined by the distance between the cover line and the foot line.

[0004] The open-form forging is carried out as a hot forming process within a temperature window predetermined for the workpiece. The workpiece temperature depends on the material and generally also takes into account the desired forming of the workpiece to the final geometry and the forming energy predetermined by the pass plan and introduced into the workpiece.

[0005] A method and a device for optimizing a forging process are known from the document US2005 / 0247092 A1. Similarly, the document WO 23005 / 113172 A1 also discloses a method and a device for optimizing a forging process. However, the devices and methods known from the prior art require extremely cost-intensive measurement technology to optimize the forging process and cannot realize online temperature calculation or regulation of the free-forming forging process. The solutions known from the prior art also do not take into account round ingots, shafts with shoulders, partially overforged areas, and tapered ingots when calculating the shape change or shape change distribution in the workpiece. Therefore, the solutions known from the prior art are cost-intensive and cannot bring the desired results for regulating different types of free-forming forging processes. Summary of the invention

[0006] The object of the present invention is therefore to provide a method and a free-form forging press which allow a comprehensive solution for monitoring the process in a free-form forging press without having to use cost-intensive measurement technology systems for this purpose. In the sense of the invention, this object is achieved by a method comprising the features of claim 1 and a free-form forging press comprising the features of claim 13. Advantageous embodiments of the invention are set forth in particular in the dependent claims.

[0007] According to the present invention, a method for monitoring and adjusting a free-form forging machine is provided, the method comprising the following steps: (a) calculating the geometric shape development of a workpiece during free-form forging using an empirical model; (b) calculating the workpiece temperature on a cross-section of the forged workpiece in parallel with step (a), i.e. simultaneously or at least partially overlapping in time; (c) calculating the shape change distribution along the length of the workpiece, preferably using the geometric shape development calculated in step (a); and (d) automatically or manually adjusting the shape change distribution to a predetermined range based on the shape change distribution calculated in step (c).

[0008] This provides a comprehensive solution for process monitoring during free-form forging. Cost-intensive measurement technology systems can be largely, preferably completely, avoided. During free-form forging, the workpiece is intended to be elongated along its longitudinal axis dfes, so that the length increases by ΔL with each stroke, while the width increases by ΔB due to the free side surface of the workpiece. The ratio of the change in length to the change in width, the so-called elongation, is very dependent on the material, temperature and tool. Therefore, the geometry can only be predicted or calculated in advance to a limited extent. Existing measurement technology solutions for detecting the development of the geometry have the disadvantage that they are extremely complex and cost-intensive due to the harsh environmental conditions and can therefore only be used for a small number of forgings.

[0009] The solution according to the invention to overcome these problems provides that the workpiece is moved to a defined initial position and preferably a foot line of the forging process is set there. The workpiece is then forged and gradually moved through the forging press until a predetermined end position, which is preferably defined as the cover line. On the side of the manipulator, the cover line defines the starting point of the workpiece extending to the above-mentioned foot line. The workpiece length is thus obtained from the difference between the cover line and the foot line.

[0010] During forging, the geometric development is then calculated via the pass plan and the relationship to the widening known to those skilled in the art.

[0011] At predetermined times, for example after every two passes, the distance between the foot line and the cover line can be repeatedly measured, thereby recording the actual geometric development and correcting any errors in the geometry calculation. In conjunction with the model for the geometry calculation, material-dependent extension and widening properties can thus be recorded.

[0012] Furthermore, it is preferred that the compression stroke, the compression force and / or the actuator position are detected by means of suitable sensors and that the forging press and, if applicable, the actuator use the compression stroke, the compression force and / or the actuator position to determine the widening and length change of the workpiece. During operation, one or two actuators are usually used for this conversion, wherein, when two forging actuators are used, preferably also the transfer of the workpiece from the first actuator to the second actuator is taken into account.

[0013] Preferably, all of the mentioned parameters are stored in parallel with the process in a database, thereby making it possible to obtain a self-learning and continuously improving model for geometric measurement and calculation in open-form forging.

[0014] Temperature is a key target variable in free-form forging, since temperature significantly influences material properties, in particular the microstructure of the workpiece. During forging, only the surface temperature can be measured, but not the internal temperature. Therefore, the method according to the invention proposes to calculate the workpiece temperature in a cross section of the forged workpiece, wherein the workpiece temperature is calculated simultaneously or at least partially overlapping in time, thus in parallel, with the step of calculating the geometrical development of the workpiece during free-form forging using an empirical model.

[0015] The temperature distribution is preferably calculated with the aid of one or more measuring systems, such as pyrometers or thermography systems, which measure the surface temperature at one or more points on the workpiece surface. The temperature distribution within the workpiece is then calculated with the aid of temperature models known to those skilled in the art. The calculated temperature distribution is preferably displayed to the forging press operator, thereby advantageously supporting the monitoring and regulation of the free-form forging. In particular, this enables the operator to interrupt the process at any time or to change the process in the manner desired by the operator.

[0016] The calculation of the geometric development of the workpiece during free-form forging is preferably the basis for a further important step of the method according to the invention, namely the step of calculating the shape change distribution along the length of the workpiece. The geometric variables obtained when calculating the geometric development are then used as input variables for a shape change model in order to calculate the shape change distribution and thus the degree of core compression during free-form forging in parallel with the process. For example, Dominik Recker in the publication "Entwicklung von schnellen Prozessmodellen und der Forschungsform" published by the publishing house Shacker-Verlag in Aachen in 2014. A general shape change model for this is described in the article "Advances in fast process models and optimization options for free-form forging". The calculation of the shape change distribution along the length of the workpiece is very important for free-form forging, because the process characteristics of free-form forging lead to an uneven distribution of the shape change in the workpiece.

[0017] According to the invention, it is preferred to extend the shape change model, in particular the above-mentioned shape change model proposed by Recker, to cover further geometries of the workpiece to be forged, in particular with regard to partially overforged ingots, conical ingots, polygonal ingots and round ingots. For this purpose, when using the shape change model, the shape change distribution, which depends on the specific geometry of the workpiece to be produced, must be taken into account in a manner known to a person skilled in the art.

[0018] According to the invention, the shape change distribution is finally adjusted within a predetermined range based on the previously calculated shape change distribution. Thus, the invention provides an overall system for process regulation in free-form forging, in which process variables, quality variables, geometry, shape change and temperature are used by means of process data and regulation algorithms.

[0019] In this context, it is particularly preferred that a predetermined temperature window for the free-form forging process is checked and that a warning is preferably issued to the forging press operator when the temperature window permitted for the workpiece is left. It is particularly preferred that the method preferably automatically proposes a proposal to continue the free-form forging process with the aim of achieving a desired shape change profile and, if necessary, implements it independently or at least after approval by the forging press operator.

[0020] Particularly preferably, the method according to the invention uses no additional measured data, apart from the workpiece temperature and, if applicable, existing measurement signals of the open-form forging press and / or at least one workpiece manipulator, preferably compression stroke, compression force and manipulator position. This limits the use of measuring sensors and the associated complexity to a necessary minimum, while still allowing complete process monitoring of the open-form forging process.

[0021] Particularly preferably, steps a) to c) are calculated together online during the free-form forging process, i.e. the calculation of the geometry development, the parallel calculation of the workpiece temperature in the cross section and the calculation of the shape change distribution along the workpiece length, in order to be able to readjust the free-form forging process as quickly as possible.

[0022] Particularly preferably, the calculation of the geometric development includes the calculation of the extension and widening characteristics of the workpiece, preferably as a function of the material. This advantageously supports the monitoring and control of the open-form forging process itself.

[0023] In a further preferred embodiment of the method according to the invention, the parameters obtained by means of the empirical model in the calculation of the geometric development of the workpiece are used as input variables for a shape change model, for which the shape change distribution and, preferably in the case of a non-uniform shape change distribution along the cross section and / or the length of the workpiece, the degree of core compression is determined. This provides a method that allows an optimal description of the free-form forging process and the properties of the processed workpiece, in particular in the case of workpiece geometries that deviate from a circular geometry, in particular in the case of shafts with shoulders.

[0024] In this context, it is preferred to provide a control and regulation unit that is connected to a database in which all detected measurement data and calculated parameters are stored. This provides a method that can preferably self-learn to adjust the regulation algorithm even when producing complex workpiece geometries and special workpiece qualities, so that the best possible forging result is achieved.

[0025] It is particularly preferred that the control and regulation unit displays the calculated variables of the geometry distribution and / or the shape change distribution and / or the temperature change distribution to the operator, preferably also issues a warning in the event of deviations from a predetermined range, and / or makes a suggestion for regulating the free-form forging process with the aim of maintaining the predetermined range and / or achieving the desired shape change distribution. This provides a method that produces the best free-form forging results, an optimized pass sequence and an optimal workpiece quality.

[0026] According to a further aspect of the invention, a free-form forging press is provided, which is connected to a control and regulating unit and is designed and arranged to carry out the method according to the invention according to the above-mentioned first aspect.

[0027] The advantages and technical effects associated with the method according to the invention can therefore also be achieved with the aid of such a free-form forging press according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The invention is explained in more detail below with reference to two drawings, in which preferred embodiments of the invention are explained in more detail, but these embodiments do not limit the scope of protection of the invention defined in the claims. In the drawings:

[0029] Figure 1 is a first view of the open-form forging press at the start of the method according to the invention; and

[0030] Figure 2 is a view of a free-form forging press at the end of the free-form forging process. DETAILED DESCRIPTION

[0031] Figure 1 A free-form forging press 1 is shown, which has two forging tools 2, 3 arranged movably relative to each other. The upper forging tool 3 is arranged movably relative to the lower forging tool 2 within the free-form forging press 1, wherein a workpiece 4 held by a forging manipulator 5 is brought to the forging tools 2, 3 at the beginning of the free-form forging process. In this case, a foot line 7 is determined, which determines the beginning of the workpiece 4 or at least the beginning of its length to be forged.

[0032] Figure 2 Shown with Figure 1 The same open-form forging press 1 is shown, wherein at the end of the open-form forging process the workpiece 4 is completely formed between the forging tools 2, 3. At this point, a cover line 8 is determined, which defines the end of the workpiece 4 to be formed. Figure 1The difference in the leg line 7 in the forging process can determine the extension ΔL of the workpiece 4 during the free-forming forging process. Based on the conservation of mass and volume, the person skilled in the art can also determine the material-dependent widening ΔB. During the forging process, the geometric development can be calculated via the pass scheme carried out during the forming of the workpiece 4 and the known relationship for the widening. For example, according to the article "Spread and elongation in flat tool forging" written by Tomlinson, A and Stringer, JD, published in the publication Journal of the Iron and Steel Institute 193 (Journal of the Iron and Steel Institute 193) in 1959, pages 157 to 162, this material-dependent relationship is sufficiently known to the person skilled in the art. In this way, errors caused by unknown workpiece properties can be avoided, which would otherwise accumulate.

[0033] List of reference numerals:

[0034] 1 Free Forming Press

[0035] 2 Forging tools

[0036] 3 Forging tools

[0037] 4 Workpiece

[0038] 5 Forging control mechanism

[0039] 7-foot line

[0040] 8 Shield line.

Claims

1. A method for monitoring and regulating a free-form forging process, the method comprising the following steps: a) Calculation of the geometric development of the workpiece during free-form forging using empirical models, b) calculating the workpiece temperature in a cross section of the forged workpiece in parallel with step a), ie simultaneously or at least partially overlapping in time, c) preferably calculating the shape change distribution along the length of the workpiece using the geometry calculated in step a), and d) manually or automatically adjusting the shape change distribution to a predetermined range based on the shape change distribution calculated in step c).

2. The method according to claim 1, characterized in that In step a), the foot line and the cover line are defined for the open-form forging process and the geometric development is corrected if necessary.

3. The method according to any one of the preceding claims, characterized in that In step b), the workpiece temperature is preferably measured by means of a pyrometer or a thermal imaging system and the open-form forging process is regulated, if necessary, with the aim of maintaining a predetermined workpiece temperature range.

4. The method according to claim 3, characterized in that The measured temperature is used as a comparison variable in a calculation model which calculates the temperature distribution along the entire cross section of the workpiece, preferably also along the length of the workpiece.

5. The method according to any one of claims 3 or 4, characterized in that The maintenance of a material-dependent temperature range for a predetermined workpiece is monitored and preferably regulated.

6. The method according to any one of claims 3 to 5, characterized in that Apart from measuring the workpiece temperature and, if applicable, using existing measurement signals of the open-form forging press and / or at least one workpiece actuator, preferably compression path, compression force and actuator position, the method does not use any further measurement data.

7. The method according to any one of the preceding claims, characterized in that Steps a) to c) are calculated together in-line during the open-form forging process.

8. The method according to any one of the preceding claims, characterized in that The workpiece is a round ingot, a shaft with a shoulder and / or a conical ingot and / or can have partially overforged areas.

9. The method according to any one of the preceding claims, characterized in that The calculation of the geometric development includes a preferably material-dependent calculation of the extension and widening characteristics of the workpiece.

10. The method according to any one of the preceding claims, characterized in that The variables calculated in step a) for the geometry development are used as input variables for a shape change model, with which the shape change distribution and, preferably in the case of a non-uniform shape change distribution along the cross section and / or length of the workpiece, the degree of core compression is determined.

11. The method according to any one of the preceding claims, characterized in that A control and regulating unit is provided which is connected to a database in which all acquired measurement data and calculated parameters are stored.

12. The method according to claim 11, characterized in that The control and regulation unit displays the calculated variables of the geometric shape distribution and / or shape change distribution and / or temperature distribution to the operator and preferably also issues a warning in the event of deviations from the target state, preferably due to areas of too low shape change, and / or makes recommendations for regulating the free-form forging process with the aim of maintaining a predetermined range and / or achieving an ideal shape change distribution.

13. A free-form forging press which is connected to a control and regulating unit which is designed and arranged to carry out the method according to one of the preceding claims.

14. The free-forming forging machine according to claim 13, characterized in that The control and regulating unit is connected to a database in which all measurement data acquired by the sensors and the parameters calculated by the shape change model can be stored.

15. A free-forming forging machine according to any one of claims 13 or 14, characterized in that The control and regulation unit is connected to a display unit, by means of which calculated variables of the geometric shape distribution and / or shape change distribution and / or temperature distribution can be displayed to an operator, preferably also warnings can be issued in the event of deviations from predetermined areas, and / or suggestions can be made for regulating the free-form forging process with the aim of maintaining a predetermined range and / or achieving an ideal, preferably uniform shape change distribution.

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