Process monitor for free-form forging
Patent Information
- Application Number
- EP2023728316
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-07-12
- Filing Date
- 2023-05-22
- Publication Date
- 2025-05-21
AI Technical Summary
Existing open-die forging processes require cost-intensive measurement technologies for optimizing the forging process, which are not effective for online temperature calculations or control, especially for complex workpiece geometries like round blocks, stepped shafts, and conical blocks, leading to suboptimal results.
A method that calculates geometry development, workpiece temperature, and shape change distribution using empirical models and sensors, allowing for real-time monitoring and regulation of the open-die forging process without relying on expensive measurement systems, incorporating a control and regulation unit that adjusts algorithms based on recorded data for optimal forging results.
Enables comprehensive process monitoring and control of open-die forging, reducing costs and improving the quality of forged workpieces by predicting geometry changes, managing temperature, and achieving ideal shape distributions, even for complex geometries, through a self-learning system that minimizes sensor usage.
Smart Images
Figure 1.1
Abstract
Description
[0001] Process monitor for open-die forging
[0002] 1 . Field of the invention
[0003] The invention relates to a method for monitoring and controlling open-die forging presses and to an open-die forging press which is connected to a control and regulation unit and is designed and configured to carry out this method.
[0004] 2. State of the art
[0005] Open-die forging is a forming technique related to forging, the aim of which is to improve the mechanical properties of a workpiece and to produce blanks. In open-die forging, a workpiece is formed under pressure using tools moving against each other. The tools can be smooth or partially contain the shape of the workpiece itself. The workpiece shape is created by carefully guiding the workpiece and controlling the forming force exerted by the tools. Typically, many tool strokes are required until the workpiece assumes its desired shape.
[0006] The workpieces are typically gripped by a forging manipulator and formed step by step over the entire length to be formed, between a base line at the beginning of the forming area and a hood line at the end of the forming area. The workpiece length can thus be determined from the distance between the hood line and the base line.
[0007] Open-die forging is a hot forming process within a predetermined temperature window for the workpiece. This workpiece temperature depends on the material and also typically takes into account the desired forming of the workpiece to its final geometry, as well as the forming energy introduced into the workpiece as specified by the pass schedule.
[0008] US 2005 / 0247092 A1 discloses a method and a device for optimizing the forging process. WO 23005 / 113172 A1 also discloses a method and a device for optimizing the forging process. However, these devices and methods known from the prior art require extremely cost-intensive measurement technology to optimize the forging process and do not allow for online temperature calculations or control of the open-die forging process. Furthermore, the solutions known from the prior art do not consider round ingots, stepped shafts, partially over-forged areas, and conical cast ingots when calculating the deformation or deformation distribution within the workpiece. The solutions known from the prior art are therefore cost-intensive and do not produce the desired results for controlling various types of open-die forging processes.
[0009] 3. Object of the invention
[0010] It was therefore an object of the invention to provide a method and an open-die forging press capable of providing a comprehensive solution for process monitoring during open-die forging without having to resort to cost-intensive measurement systems. This object is achieved according to the invention with a method comprising the features of claim 1 and with an open-die forging press comprising the features of claim 13. Advantageous embodiments of the invention are set forth in particular in the dependent claims.
[0011] 4. Summary of the invention
[0012] According to the invention, a method for monitoring and controlling
[0013] Open-die forging presses are provided, which comprises the steps of (a) calculating the geometric development of a workpiece during open-die forging using empirical models, (b) parallel, i.e. simultaneously or at least partially overlapping in time, to step (a) of calculating the workpiece temperature over the cross section of the forged workpiece, (c) calculating the strain distribution over the workpiece length, preferably using the geometric development calculated in step (a), and (d) automatically or manually controlling the strain distribution in a predetermined area based on the strain distribution calculated in step (c).
[0014] This provides a comprehensive solution for process monitoring during open-die forging. Cost-intensive metrology systems can be largely, preferably entirely, avoided. During open-die forging, the workpiece elongates along its longitudinal axis, so that with each stroke, the length increases by the value AL, while the width increases by AB due to the free side surfaces of the workpiece. The ratio of the change in length to the change in width, the so-called stretching, is highly dependent on the material, temperature, and tool. Thus, the prediction or pre-calculation of the geometry is only possible to a limited extent. Existing metrology solutions for determining geometry development have the disadvantage that they are extremely complex and cost-intensive due to the harsh environmental conditions and can therefore only be used in a few forging shops.
[0015] The inventive solution to overcome these problems provides for the workpiece to be moved to a defined starting position, where a base line for the forging process is preferably established. The workpiece is then forged and moved step by step through the press to a predetermined end position, which is preferably defined as the hood line. On the manipulator side, the hood line is defined as the beginning of the workpiece, which extends to the above-described base line.
[0016] The difference between the hood line and the foot line results in the workpiece length.
[0017] During forging, the geometry development is then calculated using the pass plan and the expansion relationships known to the expert.
[0018] At predetermined times, e.g., after every second pass, the measurement of the distance between the base line and the cap line can now be repeated, making it possible to capture the actual geometry development and correct any errors that may occur in the geometry calculation. In relation to the model for the geometry calculation, this makes it possible to capture the material-dependent stretching and expansion behavior.
[0019] Furthermore, it is preferred if the press stroke, press force, and / or manipulator position are recorded using suitable sensors and used by the press and, if necessary, the manipulator to determine the expansion and length change of the workpiece. This is typically implemented in operation with one or two manipulators; when using two forging manipulators, the transfer of the workpiece from the first to the second manipulator is preferably also taken into account.
[0020] It is preferred if all of the above-mentioned parameters are stored in a database in parallel with the process, which makes it possible to obtain a self-learning and continuously improving model for geometry measurement and calculation in open-die forging.
[0021] Temperature is a crucial target parameter in open-die forging because it significantly influences the material properties, particularly the microstructure of the workpiece. During forging, the temperature can only be measured at the surface, while the temperature inside cannot be measured. The method according to the invention thus provides for calculating the workpiece temperature across the cross-section of the forged workpiece. This calculation of the workpiece temperature takes place simultaneously or at least partially overlapping, thus parallel to the step of calculating the geometric development of the workpiece during open-die forging using empirical models.
[0022] The temperature distribution is preferably calculated using one or more measuring systems, e.g., pyrometers or thermography systems, which measure the surface temperature at one or more points on the workpiece surface. The temperature distribution inside the workpiece is then calculated using temperature models known to those skilled in the art. The calculated temperature distribution is preferably displayed to the press operator, which advantageously supports the monitoring and control of the open-die forging process. In particular, this gives the operator the option of interrupting the process at any time or modifying it as desired.
[0023] Calculating the geometry development of the workpiece during open-die forging preferably forms the basis for another essential step of the method according to the invention, namely calculating the strain distribution over the workpiece length. The geometric parameters obtained when calculating the geometry development are then used as input variables for a strain model to calculate the strain distribution and thus the core densification during open-die forging in parallel with the process. A common strain model for this purpose is described, for example, by Dominik Recker in the 2014 publication "Development of Fast Process Models and Optimization Options for Open-Die Forging," published by Shacker-Verlag, Aachen.Calculating the strain distribution over the workpiece length is of great importance for open-die forging, since the process characteristics of open-die forging result in an inhomogeneous distribution of strain in the workpiece.
[0024] According to the invention, it is preferred if the deformation model, in particular the above-described Recker deformation model, is expanded to include additional geometries of the workpiece to be forged, particularly with regard to partially over-forged blocks, conical blocks, polygonal blocks, and round blocks. For this purpose, the deformation distribution, depending on the specific geometries of the workpieces to be produced, must be taken into account when using the deformation model, in a manner known per se to those skilled in the art.
[0025] Finally, according to the invention, the strain distribution is controlled within a predetermined range based on the pre-calculated strain distribution. The invention thus provides a holistic system for process control in open-die forging, in which the process and quality parameters of geometry, strain, and temperature are used using process data and control algorithms.
[0026] In this context, it is particularly preferred if the predefined temperature window for the open-die forging process is monitored and, preferably, a warning is issued to the press operator when the temperature window defined as permissible for the workpiece is exceeded. It is particularly preferred if the method, preferably in an automated manner, proposes suggestions for continuing the open-die forging process with the aim of achieving an ideal strain distribution and, if necessary, implements them independently or at least after approval by the press operator.
[0027] It is particularly preferred if the method according to the invention does not use any further measurement data besides measuring the workpiece temperature and any measurement signals from the open-die forging press and / or the at least one workpiece manipulator, preferably the press stroke, the press force, and the manipulator position(s). This limits the use of measurement sensors and the associated complexity to the necessary minimum while simultaneously enabling complete process monitoring of the open-die forging process.
[0028] It is particularly preferred if steps (a) - (c), i.e. calculating the geometry development, calculating the workpiece temperature across the cross section in parallel and calculating the strain distribution across the workpiece length, are calculated online during the open-die forging process in order to enable the fastest possible readjustment of the open-die forging process.
[0029] In particular, it is preferred if the calculation of the geometry development includes the calculation of the stretching and expansion behavior of the workpiece, preferably depending on the material. This advantageously supports both the monitoring and control of the open-die forging process itself.
[0030] In a further preferred embodiment of the method according to the invention, the parameters determined during the calculation of the geometry development of the workpiece using empirical models are used as input variables for a deformation model, for which the deformation distribution and, preferably in the case of inhomogeneous deformation distribution across the cross-section and / or length of the workpiece, also the core compaction are determined. This provides a method that allows the best possible conclusions about the open-die forging process and the properties of the machined workpiece, particularly for workpiece geometries that deviate from round geometries, in particular for stepped shafts. In this context, it is preferred if a control and regulation unit is provided which is connected to a database in which all recorded measurement data and calculated parameters are stored.This creates a process that is preferably self-learning and capable of adjusting the control algorithms so that the best possible forging result is achieved, even when producing complex workpiece geometries and special workpiece qualities.
[0031] It is particularly preferred if the control and regulation unit displays the calculated variables of the geometric distribution and / or the strain distribution and / or the temperature change distribution to the operator, preferably also issues warnings in the event of deviations from predefined ranges and / or provides suggestions for controlling the open-die forging process with the aim of maintaining the predefined ranges and / or achieving an ideal strain distribution. This provides a method capable of producing optimal open-die forging results, optimized pass schedules, and optimal workpiece qualities.
[0032] According to a further aspect of the invention, an open-die forging press is provided which is connected to a control and regulation unit and which is designed and configured to carry out the method according to the invention according to the first aspect described above.
[0033] All advantages and technical effects associated with the method according to the invention can thus also be achieved by means of such an open-die forging press according to the invention.
[0034] 5. Description of the characters
[0035] The invention will be explained in more detail below with reference to two figures, in which preferred embodiments of the invention are explained in more detail, without these being suitable for limiting the scope of the invention, which is defined in the claims. In the figures,
[0036] Figure 1 shows a first view of an open-die forging press at the beginning of the method according to the invention and
[0037] Figure 2 shows a view of an open-die forging press at the end of the open-die forging process.
[0038] 6. Detailed description of the characters
[0039] Figure 1 shows an open-die forging press 1 with two forging tools 2, 3 arranged so as to be movable relative to one another. The upper forging tool 3 is arranged so as to be movable relative to the lower forging tool 2 within the open-die forging press 1, with the workpiece 4, held by a forging manipulator 5, being brought to the forging tools 2, 3 at the beginning of the open-die forging process. At this point in time, a base line 7 is defined, which defines the beginning of the workpiece 4 or at least its length to be forged.
[0040] Figure 2 shows the same open-die forging press 1 as in Figure 1, wherein the workpiece 4 has been completely formed between the forging tools 2, 3 at the end of the open-die forging process. At this time, a hood line 8 is defined, which defines the end of the workpiece 4 to be formed. The elongation AL of the workpiece 4 during the open-die forging process can then be determined from the difference between the base line 7 from Figure 1 and the hood line 8. From this, the person skilled in the art can also determine the material-dependent spreading AB due to the constant mass and volume. During the forging process, the geometry development can be calculated using the pass schedule carried out during the forming of the workpiece 4 as well as known relationships to the spreading. The person skilled in the art will know such material-dependent relationships, for example, from Tomlinson, A; Stringer, JD: “Spread and elongation in flat tool forging” from the Journal of the Iron and Steel Institute 193, 1959, p.157 - 162, are well known. This can prevent errors caused by unknown workpiece behavior, which would otherwise accumulate continuously.
[0041] List of reference symbols
[0042] 1 open-die forging press 2 forging tool
[0043] 3 blacksmith tools
[0044] 4 Workpiece
[0045] 5 forging manipulator
[0046] 7 Foot line 8 Hood line
Claims
Patent claims:
1. Method for monitoring and controlling open-die forging processes, comprising the steps of: a) calculating the geometric development of a workpiece during open-die forging using empirical models, b) in parallel, i.e. simultaneously or at least partially overlapping, to step a) calculating the Workpiece temperature across the cross-section of the forged workpiece, c) calculating the strain distribution across the workpiece length, preferably using the geometry development calculated in step a), and d) manually or automatically controlling the strain distribution within a predetermined range based on the strain distribution calculated in step c).
2. Method according to claim 1, characterized in that in step a) a foot line and a hood line are defined for the open-die forging process and the geometry development is corrected if necessary.
3. Method according to one of the preceding claims, characterized in that in step b) a measurement of the workpiece temperature, preferably by means of a pyrometer or a thermography system, and optionally a control of the open-die forging process with the aim of maintaining a predetermined workpiece temperature range takes place.
4. Method according to claim 3, characterized in that the measured temperature is used as a comparison value in a calculation model which calculates the temperature distribution over the entire Cross-section of the workpiece, preferably also over the length of the workpiece, is calculated.
5. Method according to one of claims 3 or 4, characterized in that the material-dependent compliance with a predetermined workpiece temperature range is monitored and preferably controlled.
6. Method according to one of claims 3 to 5, characterized in that the method does not use any further measurement data in addition to the measurement of the workpiece temperature and any measurement signals present from the open-die forging press and / or the at least one workpiece manipulator, preferably the press stroke, the press force and the manipulator position(s).
7. Method according to one of the preceding claims, characterized in that steps a) to c) are calculated online during the open-die forging process.
8. Method according to one of the preceding claims, characterized in that the workpieces are round blocks, stepped shafts and / or conical cast blocks and / or can have partially over-forged areas.
9. Method according to one of the preceding claims, characterized in that the calculation of the geometry development comprises the calculation of the stretching and spreading behavior of the workpiece, preferably material-dependent.
10. Method according to 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 deformation model can be used to determine the strain distribution and, preferably in the case of inhomogeneous strain distribution over the cross-section and / or the length of the workpiece, the core compaction.
11. Method according to one of the preceding claims, characterized in that a control and regulation unit is provided which is connected to a database in which all recorded measurement data and calculated parameters are stored.
12. Method according to claim 11, characterized in that the control and regulation unit displays the calculated variables of geometry distribution and / or deformation distribution and / or temperature distribution to the operator, preferably also issues warnings in the event of deviations from the target state, preferably due to areas with insufficient deformation, and / or issues suggestions for regulating the open-die forging process with the aim of adhering to the predefined areas and / or achieving an ideal deformation distribution.
13. Open-die forging press, connected to a control and regulation unit which is designed and arranged to carry out the method according to one of the preceding claims.
14. Open-die forging press according to claim 13, characterized in that the control and regulation unit is connected to a database in which all measurement data recorded by sensors and parameters calculated by a deformation model can be stored. Open-die forging press according to one of claims 13 or 14, characterized in that the control and regulation unit is connected to a display unit by means of which the calculated variables of geometric distribution and / or deformation distribution and / or temperature distribution can be displayed to the operator, preferably also warnings in the event of deviations from predefined ranges and / or suggestions for regulating the open-die forging process with the aim of adhering to the predefined ranges and / or achieving an ideal, preferably uniform, deformation distribution can be output.