EP3829792A2

EP3829792A2 - Bending device and method for determining at least one material parameter and/or processing parameter for a workpiece-processing device

Info

Publication number: EP3829792A2
Application number: EP19759491.4A
Authority: EP
Inventors: Gerhard Angerer; Klemens Freudenthaler; Florian Hausmann; Matthias HÖRL; Nenad KOVJENIC; Florian Maier; Michael SCHERNHAMMER; Verena STEININGER; Helmut Theis
Original assignee: Trumpf Maschinen Austria GmbH and Co KG
Current assignee: Trumpf Maschinen Austria GmbH and Co KG
Priority date: 2018-07-27
Filing date: 2019-07-25
Publication date: 2021-06-09
Also published as: AT521529A1; CN112512714A; AT521529B1; WO2020019011A2; CN112512714B; WO2020019011A3

Abstract

The invention relates to a method for determining at least one material parameter (19) and/or at least one processing parameter (20) and/or for selecting or creating a processing program for the control system (8) of a workpiece-processing device (10), preferably a bending machine, in particular a press brake or a folding machine, and/or a welding device, in particular a laser welding device, comprising the steps of: (a) removing a workpiece sample (2) of a sheet-like material, in particular sheet metal, preferably from a sheet metal piece (3) or from a charge (4) of sheet metal pieces (3), (b) carrying out at least one measurement on the workpiece sample (2), (c) determining at least one material parameter (19) and/or at least one processing parameter (20) and/or selecting or creating a processing program for the control system (8) of a workpiece-processing device (10) depending on the result of the at least one measurement on the workpiece sample (2), characterized by the step of (d) bending the workpiece sample (2) by means of a bending device (1), the at least one measurement being carried out on the workpiece sample (2) when the workpiece sample (2) is in at least one bent state.

Description

BENDING DEVICE AND METHOD FOR DETERMINING AT LEAST ONE MATERIAL PARAMETER OR. MACHINING PARAMETERS FOR A WORKPIECE MACHINING DEVICE

The invention relates to a method for determining at least one material parameter and / or at least one machining parameter and / or for selecting or creating a machining program for the control of a workpiece machining device, preferably a bending machine, in particular a bending press or a folding machine, and / or one Cutting and / or welding device, in particular laser cutting and / or laser welding device, comprising the steps: (a) taking a workpiece sample of a plate-shaped material, in particular a sheet, preferably from a piece of sheet metal or from a batch of sheet metal pieces, (b) performing at least one measurement on the workpiece sample, and (c) determining at least one material parameter and / or at least one machining parameter and / or selecting or creating a machining program for controlling a workpiece machining device depending on the result it of the at least one measurement on the workpiece sample.

When machining workpieces, precise information about the properties of the material to be machined is often missing. In addition, batch fluctuations often lead to large differences between actual machining parameters and optimal machining parameters. Such deviations in the technology parameters lead to reduced processing quality. For bending presses e.g. this circumstance leads to considerable bending inaccuracies, in particular non-tolerable deviations of a desired bending angle from an actual bending angle.

EP 2 134 483 B1 discloses a method for determining a setting parameter value of a bending press, in which parameters of a workpiece to be bent in a bending process are fed to a control device of the bending press. Before the bending process is completed, the workpiece is subjected to an eddy current measurement. A measured value of the electromagnetic reaction of the workpiece to an alternating field is determined. One of the parameters is formed by this measured value. This measure is intended to provide a bending process in which a particularly high bending accuracy is achieved is determined by fluctuations in the properties of the starting material and taken into account in the bending process.

It has been shown that the material properties taken into account in the prior art or the way in which they are determined, for the setting of processing parameters - such as the immersion depth of a punch, the bending force to be applied or a deflection compensation parameter on the bending press - are insufficient or are only of limited suitability for optimal setting. Taking material-related data into account, this leads to quality-reducing deviations between the intended processing result and the processing result actually achieved.

The object of the present invention was to overcome the disadvantages of the prior art and to provide a method or a device with which the setting of machining parameters or the selection or creation of machining programs is further optimized. The aim is to minimize the difference between the desired and the achieved machining result. The process should also be able to take fluctuations in material properties into account in different batches or within one batch.

This object is achieved with a method mentioned at the outset by: (d) bending the workpiece sample by means of a bending device, the at least one measurement being carried out on the workpiece sample in at least one bent state of the workpiece sample.

With this measure, much more precise machining parameters can be determined or optimally coordinated machining programs can be selected on the basis of the process-related material parameters obtained by the measurement. The advantage of the invention is, inter alia, that the deviation between the desired processing result and the processing result actually achieved can be significantly reduced. If the material data are determined before cutting, the cutting can also be adapted, in particular by means of a laser cutting machine (for example in relation to the rolling direction of a piece of sheet metal). The designation of steps (a) - (d) has no chronological meaning. In particular, steps (b) and (d) can be carried out simultaneously or in immediate succession. Properties of the workpiece sample in the bent state should be determined. Steps (b) and (d) can preferably also be repeated several times, in particular in order to be able to carry out measurements in the case of states bent to different degrees. Only the taking of the workpiece sample is at the beginning of the process.

If the processing device is a bending machine, in particular a bending press, the accuracy of the bent parts is increased by the invention. With laser welding e.g. compliance with defined gap dimensions is of great importance for process quality. With more precise technology data (material / processing parameters), the defined gap dimension can be better maintained. Knowing material properties obtained in connection with a bent workpiece sample can also lead to a better machining result in other machining processes.

The steps (b) and (d) of the method according to the invention carried out on the workpiece sample are carried out before the actual machining of a workpiece, which is carried out by means of the determined material and / or machining parameters and / or the selected machining program. The workpiece sample on which the measurement is carried out and the workpiece to be machined later are different pieces. In other words: workpiece sample and workpiece are not one and the same part. In the present invention, it is, so to speak, a test method carried out beforehand, which is carried out separately from the subsequent machining process and on a workpiece sample specially taken for this purpose. Steps (b) and (d) are preferably carried out on a workpiece sample in a test device provided for this purpose, while the machining of a workpiece (with the previously determined material or machining parameters and / or the previously selected machining program) in one of the testing device independent processing device (eg bending press).

It has been shown that the bending of a workpiece sample, including measurements of the bending state of the workpiece sample, makes it possible to carry out the machining of the workpiece or a batch of workpieces (from which the workpiece sample was taken) much more precisely. Material parameters in the sense of the present invention are understood not only as individual values that can characterize a workpiece or workpiece sample (e.g. dimensions, in particular thickness, weight, density, modulus of elasticity, hardness, etc.), but also courses or dependencies such as the flow curve or bending flow curve. Bending flow curve is understood to mean in particular the yield stress as a function of the degree of deformation, the deformation being effected by bending. This applies equally to the bending process, in particular in the bending or testing device, as well as to calculations or simulations of the flow curve under bending conditions.

In a preferred embodiment, an apparatus is provided in which a material sample is deformed by means of bending. The material data can be determined on the basis of the forming force / moment and the resulting forming, in particular curvature or bending radius or angle, on the material sample and then optimized. Depending on the type of forming in the test device (torque bending, free bending), a suitable process model will be used to optimize the material data. With the optimized material data, the process data (material parameters, machining parameters, in particular bending angle, angle, springback, immersion depth, bending radius, etc.) can be determined using process simulation.

A preferred embodiment is characterized in that the bending of the workpiece sample is carried out by means of the bending device by free bending. The at least one measurement on the workpiece sample is carried out here in a bending state which is achieved exclusively by free bending, and thus in the freely bent state of the workpiece sample. With free bending, the (bent) shape of the workpiece sample caused by the (free) bending process is not included in the tools involved in the bending process. In other words: the workpiece sample does not take the form of a tool. The forming of the workpiece sample is only controlled by the movement of the tools. This enables material properties to be determined regardless of the tool used. The material or machining parameters obtained by freely bending a workpiece sample provide particularly precise machining results in a (subsequent) machining process in a workpiece machining device on a workpiece (which comes from the same piece or the same batch as the workpiece sample). A preferred embodiment is characterized in that the bending of the workpiece sample is carried out by means of the bending device without lateral force. The at least one measurement on the workpiece sample is carried out here in a bending state which is achieved by bending without lateral force. Bending without shear forces results in pure bending stress without additional shear forces. There are only bending stresses in the forming zone. With bending force-free bending, the ends of the workpiece sample are clamped and moved towards each other. The at least one measurement on the workpiece sample is thus carried out in this bending state of the workpiece sample which is free from external transverse forces. This enables a particularly authentic bending flow curve of the workpiece material to be determined.

A preferred embodiment is characterized in that the bending of the workpiece sample takes place by means of the bending device by pure moment bending. In the case of pure torque bending, there are only bending moments in the workpiece sample. Such a method enables a particularly precise and optimized determination of material / processing parameters.

Another embodiment is characterized in that the bending of the workpiece sample is carried out by means of the bending device by die bending or swivel bending.

A preferred embodiment is characterized in that the at least one measurement is carried out on the workpiece sample by means of at least one sensor which is integrated in the bending device. The bending device takes on the function of a fully equipped test device.

A preferred embodiment is characterized in that the at least one measurement comprises the measurement of the bending radius of the workpiece sample, the bending radius preferably being measured by means of an optical sensor, in particular a laser sensor, or a tactile sensor. The bending radius is a meaningful characteristic of the bending condition. In the case of free bending in particular, the bending radius is only influenced by the movement of the tools, but not by their shape. The bending radius thus provides immediate information about the degree of deformation caused by a load condition. A preferred embodiment is characterized in that the at least one measurement comprises the measurement of the bending angle of the workpiece sample, the bending angle preferably being measured by means of an incremental encoder. The bending angle, like the bending radius, is a characteristic feature of a bending state. In particular in the case of transverse force-free bending or pure moment bending, the bending angle can be measured in a simple manner in the region of the clamped ends of the workpiece sample, for example with an incremental encoder designed as an angle sensor.

A preferred embodiment is characterized in that the at least one measurement comprises the measurement of the force and / or the bending moment with which the workpiece sample is subjected during the bending process, preferably the force and / or the bending moment by means of a Piezo sensor and / or a strain sensor (DMS) is measured ge. The information about the force or the bending moment that causes a certain degree of deformation give information about the moment-strain relationships in the material.

A preferred embodiment is characterized in that measurements are carried out in step c) at different bending states of the workpiece sample. In this way, stress-strain relationships, preferably a bending flow curve, can be recorded, the course of which represents a characteristic of the workpiece sample or the workpiece.

A preferred embodiment is characterized in that a bending flow curve (i.e. the yield stress depending on the degree of deformation) is determined from the measurements on the workpiece sample, in particular the yield stress depending on the degree of deformation.

It has been shown that with the data of a bending flow curve, preferably obtained by free, in particular transverse, force-free bending, or with the processing parameters determined on the basis of these data, particularly precise processing results can be achieved on the workpiece.

A preferred embodiment is characterized in that, depending on the at least one measurement on the workpiece sample and / or depending on the evaluation of the at least one measurement on the workpiece sample, at least one machining parameter for the control of the workpiece machining device can be determined.

A preferred embodiment is characterized in that the workpiece processing device is a bending machine, in particular a bending press or a swivel bending machine, and the processing parameters determined as a function of the at least one measurement on the workpiece sample are the immersion depth and / or springback and / or Bending shortening and / or the type of one or more bending tools (s), in particular the size, shape and / or material of the bending tool (s) to be used and / or the amount of the pressing force, in particular the maximum pressing force, and / or the time profile the pressing force and / or the reversal position (immersion depth) of a bending tool and / or the stop position of at least one back stop. The bending carried out according to step (d) and the measurement (s) carried out in the bending state are particularly advantageous in particular for bending machines because the bending behavior is tested beforehand on a workpiece sample. Free, in particular shear-free bending is particularly suitable for step (d) because the degree of deformation is independent of the shape of the tool used and therefore provides general (i.e. independent of the test facility) parameters. Knowing this workpiece property (s), the machining parameters of the bending machine, which also includes the selection of the bending tools, can now be determined.

A preferred embodiment is characterized in that by means of a process simulation program, which is based on the at least one determined material parameter and / or the at least one determined machining parameter and / or the selected machining program, a machining process of a workpiece is simulated in a workpiece machining device , at least one machining parameter for the control of the workpiece machining device being adapted as a function of the simulation result. The simulation result can be compared with a target bending result (ie the desired bending result) and, for example, a processing parameter can be adjusted (ie changed) depending on the deviation between the simulation and the target bending result. The simulation can then be repeated one or more times with the machining parameter (s) that have now been adjusted. With this method, the machining parameter (s) for the actual bending process on a piece (in the workpiece processing device) are successively optimized. This process preferably does not take place on the workpiece to be machined, but on the workpiece sample. The workpiece sample is preferably bent only once and by optimizing the parameters for the simulation, very good machine setting parameters should then be determined.

A preferred embodiment is characterized in that the bending of the workpiece sample is simulated by means of a bending device according to step (d) by means of a calculation based on at least one material parameter, and that, depending on the deviation of the simulation result from the result, that is obtained from the at least one measurement on the workpiece sample in at least one bent state of the workpiece sample, at least one material parameter is adapted, the calculation for simulating the bending process preferably being repeated at least once with an adapted material parameter and / or preferably the at least one material parameter, which is used as the basis for the calculation and adjusted, comprises the bending flow curve. According to this embodiment, the test method itself, which is carried out in the bending device, is simulated. The simulation in comparison to the (test) bending process actually carried out enables precise determination of optimized material parameters, such as the course of the optimized bending flow curve. The bending flow curve is a curve of the yield stress as a function of the degree of deformation, which is approximated, for example, using approximation equations.

A preferred embodiment is characterized in that the at least one material parameter comprises a flow curve, in particular a bending flow curve, and that, based on an initial flow curve, a variable, in particular a torque-curvature relationship, is determined by calculation, which is determined by means of the bending device Measurement he is averaged, and that depending on the deviation of the size calculated from the flow curve and the size obtained from measurements, the flow curve is adjusted, preferably in iterative steps, preferably until the deviation falls below a predetermined limit. This measure enables an optimized material parameter - (bending) flow curve - to be provided, which also enables the machining of the workpiece in the bending machine to be optimized. The goal is also achieved by a method for machining, preferably bending and / or cutting and / or welding, a plate-shaped, preferably sheet-shaped workpiece in a workpiece machining device, the control of the workpiece machining device depending on at least one material parameter of the workpiece and / or at least one machining parameter and / or one machining program is carried out. The determination of the at least one material parameter and / or that of the at least one machining parameter and / or the selection or creation of the machining program for controlling the workpiece machining device is carried out according to the invention, in particular according to one of the preceding embodiments. The advantage of the invention is particularly evident in connection with bending machines (for example bending presses). As bending processes take place in a bending machine, knowledge of the bending properties previously determined on a test specimen is particularly important, especially if these are determined by free bending - and thus essentially independent of the tool. The tool independence is made possible by the process simulation; shear-free bending is not absolutely necessary.

A preferred embodiment is characterized in that the bending device by means of which the workpiece sample is bent is a device separate from the workpiece processing device, the bending device preferably being operable independently of the workpiece processing device. The bending device is a test device specially designed for testing workpiece samples. As already mentioned several times, the bending device is preferably designed to carry out a free, in particular transverse force-free, bending process. This means that the material parameters can be determined more or less independently of the tool. In many cases, such independence makes it possible to determine optimized machining parameters for the machining process in the workpiece machining device.

A preferred embodiment is characterized in that the workpiece processing device is a bending machine, preferably a bending press or a swivel bending machine, wherein preferably the bending of the workpiece in the bending machine and the bending of the workpiece sample in the bending device are of different types, preferably that The workpiece is bent in the bending machine by die bending and / or the workpiece sample is bent in the bending device by die bending or by free bending, in particular by bending without lateral force. Bending "different types" in this context means that the bending process in the bending machine and the bending device in the bending device differ in qualitative terms, in particular by the type of tools used or by the forming process itself - for example, die bending, in which the workpiece at least partially assumes the shape of the bending tool, vs. free bending, in which the bending state or the shape of the workpiece sample caused by the bending process (on which the measurements are also carried out) is independent of the tool shape.

A preferred embodiment is characterized in that the workpiece processing device and the bending device communicate with one another via a data connection, preferably the measurement results and / or the evaluation of the measurement results of the at least one measurement on the workpiece sample and / or at least one of the Measurement results of determined material parameters and / or machining parameters and / or a selected machining program are transmitted to the control of the workpiece machining device. The otherwise independent devices communicate with each other here and thus ensure automated integration of the test procedure (on a workpiece sample) and its results in the subsequent machining process (on a workpiece).

The object of the invention is also achieved with a bending device for bending a workpiece sample comprising at least one receptacle for the workpiece sample and at least one sensor for carrying out at least one measurement on the workpiece sample in at least one bent state of the workpiece sample, the bending device preferably being a die bending device or a bending device for free bending, before preferably shear-free bending, preferably pure moment bending, is a workpiece sample. This provides a bending device as a test device for use in a method according to the invention.

A preferred embodiment is characterized in that the receptacle has a first bearing block and a second bearing block, one bearing block being displaceable relative to the other bearing block along a displacement direction and the bearing blocks are each rotatable relative to one another about an axis of rotation, preferably the axes of rotation being substantially normal to the direction of displacement. In this way, a transverse force-free bending process is made possible, the opposite ends of the workpiece sample are each fixed to one of the bearing blocks.

A preferred embodiment is characterized in that the bearing blocks each have a clamping device, in particular a screw or hydraulic clamping device or a wedge connection, with which one side of the workpiece sample can be clamped in each case.

A preferred embodiment is characterized in that the bearing blocks are each connected to a lever and can be rotated by this. By - preferably synchronously - actuating the levers, e.g. by spreading them apart, the clamped workpiece sample can be brought into a bent state particularly easily and reproducibly or successively into states with an increasing degree of deformation.

A preferred embodiment is characterized in that the bending device has at least one sensor, preferably an optical sensor, in particular a laser sensor, and / or a tactile sensor, which is preferably set up to measure the bending radius of the workpiece sample.

A preferred embodiment is characterized in that the bending device has at least one force and / or pressure and / or moment sensor, in particular a piezo sensor and / or a strain sensor (DMS), which preferably for measuring the on at least one the bearing blocks acting forces is set up.

A preferred embodiment is characterized in that the bending device has at least one position and / or displacement and / or angle sensor, preferably in the form of an incremental encoder, for determining the position and / or the relative position and / or the angle of rotation of the bearing blocks.

The aim is also achieved by arranging a workpiece machining device for machining a workpiece, preferably a bending machine, in particular one Bending press or a swivel bending machine, and / or a cutting and / or welding device, in particular laser cutting and / or laser welding device, and a bending device according to the invention, the workpiece processing device and the bending device being separate, in particular independently operable devices, preferably in the are arranged in the same room or directly next to one another and / or are connected to one another via a data connection.

Finally, the invention also relates to the use of a Biegevor device according to the invention or an arrangement according to the invention in a method according to the invention.

Possible application examples of the invention are described in more detail below. also include some of the previously described aspects.

For example, one or more samples can be taken from a sheet of metal to be processed (e.g. at an angle of 0 °, 90 °, 45 ° to the rolling direction), these samples being shaped in the bending device serving as a test device and from the forming or out measure of the deformation material data are determined. With this material data, the technology parameters are determined according to the orientation on the sheet. The bending device (for determining the material or processing parameters) can comprise a unit for forming the sheet, a measuring unit for force measurement or bending moment measurement, a unit for displacement measurement or angle measurement and / or a unit for detecting the sheet sample curvature.

In a first variant, the bending device is designed for pure moment bending. The measurement or material data determination takes place here in a bending state of the workpiece sample, which is achieved by pure torque bending.

In a second variant, the bending device is designed for a so-called 3-point bending (comparable to die bending). The bending state is achieved here in that the workpiece sample lies on two outer points and a shear force is applied at a further point between the outer points. In the first variant, the process for determining the material data or parameters can proceed as follows: The sheet metal sample is placed in the bending device (manually or automatically) and preferably clamped there. Now the measuring process is started, a moment is introduced into the sample (e.g. using a lever or directly with a motor). This moment is measured. At the same time, the curvature and / or the bending angle are recorded. The measurement data are then processed, and a (bending) flow curve is calculated (for example, according to the Nadai bending theory).

The flow curve can then be optimized, the previously determined flow curve serving as the starting value. In the optimization, the flow curve is now varied until the deviation of the calculated torque curvature curve and the measured torque curvature curve falls below a defined error measure. With this flow curve, e.g. suitable machining parameters (bending technology parameters) are calculated using a semi-analytical calculation model and / or the machining programs are selected, corrected or newly created accordingly.

According to the second variant, the sheet metal sample can be inserted (manually or automatically) into the bending device. The "die width", ie the distance between the outer support points, can be adjusted according to the sheet thickness. Then the measuring process takes place. It is applied by applying force - preferably centrally - between the support points e.g. bent the sheet with a (radius) stamp. A force measurement and / or a displacement measurement is carried out (e.g. on a movable Fager block or on the (radius) punch). At the same time, the curvature curve on the outer edge of the sheet metal or (additionally) the bending angle can be determined. Using e.g. The test process can be simulated using semi-analytical calculations. This calculation approach is now used to optimize the flow curve. The starting value for the flow curve can be e.g. an artificial flow curve over the parameters: standard yield strength, standard tensile strength, standard elongation and modulus of elasticity; to be generated.

A bilinear flow curve can thus be created, which in turn is fitted with the flow curve approximation used below. This fitted flow curve in turn serves as a starting value for the flow curve optimization, which contributes to a further improvement the determination of the material parameters. During the optimization, the (previously generated) flow curve is varied and the test process is recalculated with it using, for example, semi-analytical simulation. The flow curve is varied until the deviation of the bending force curvature between test and calculation falls below a defined error measure. With this variant it can also be taken into account that the curvature is not constant. With the optimized flow curve, the processing parameters (bending technology data) can in turn be determined by means of semi-analytical calculation and / or the programs can be selected, corrected or created accordingly. At the customer's request, rolling direction influences can also be taken into account here.

The data determined specifically for the material can be "attached" to the production order if the production is networked accordingly (keyword: Industry 4.0). So it will be possible to e.g. for parts with very high accuracy requirements (e.g.

Parts with laser welding) technology data generated specifically.

The (test) bending device can be used by a service provider to determine technology data for customers who send the material samples. Alternatively, the customer, who also carries out the subsequent machining on the workpiece, can be provided with a (test) bending device with which he can determine the technology data himself. This device can be networked with production planning and provide technology data for the material of an order.

Cutting (e.g. using a laser cutting machine) and bending program (for a bending machine) can be corrected according to the technology data calculated for this. The bending device can function independently (e.g. you can determine technology data (material or processing parameters) at the time of goods receipt for each batch of sheet metal, or you can integrate the bending device and the results obtained with it into the laser cutting process (e.g. the laser cutting machine first cuts samples and based on the determined technology values of the samples, the cutting program and the bending program are adapted, corrected or optimized)

Alternatively, the (test) bending device can also be arranged on the bending machine in order to determine the material and / or processing parameters on site (although the cutting can are no longer corrected here; but the bending program can be automatically corrected so that tolerated leg lengths fit and the cutting error is distributed to the other legs (with lower accuracy requirements).

Alternatively, the measuring technology can be integrated into a bending tool and the measurement can be carried out directly in the bending machine. The free bending method, but also the 3-point bending or the die bending, is easy to implement, for example by an adjustable die with appropriate sensors for measuring force, curvature and / or immersion depth is provided. A blade tool with an integrated force measurement could be used as the upper tool. The immersion depth can in turn be detected with its own length measurement between the upper and lower tool.

The sheet metal curvature can be determined with the help of a laser line scanner, the force or the bending moment using piezo force sensors (e.g. load cells), the bending angle and the device geometry the bending moment with an angle sensor. In principle, however, these measurements can also be carried out with other suitable sensors.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Each show in a highly simplified, schematic representation:

Figure 1 shows a method according to the invention in a schematic representation.

2 shows a bending device for bending a workpiece sample without lateral force;

3 shows the dependency between the moment applied and the reciprocal of the bending radius for a bending process according to FIG. 2;

4 shows a bending device for freely bending a workpiece sample;

5 shows an embodiment of a bending device; 6 shows a bending device in a side view;

7 shows an arrangement of a bending device and a workpiece processing device;

8 shows a bending flow curve (solid line) obtained by means of the method according to the invention in comparison with a train flow curve (dashed line);

9 shows a method for determining a bending flow curve;

10 shows a bending device for pivot bending a workpiece sample.

In the introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component designations, and the disclosures contained in the entire description can be analogously applied to the same parts with the same reference numerals or the same component designations. The location information selected in the description, e.g. above, below, laterally, etc. based on the immediately described and illustrated figure and this position information is to be transferred to the new position in the event of a change of position.

The exemplary embodiments show possible design variants, it being noted at this point that the invention is not restricted to the specifically illustrated design variants of the same, but rather also various combinations of the individual design variants are possible with one another and this variation possibility is based on the teaching of the technical Acting through the subject invention lies in the ability of the person skilled in the art in this technical field.

The scope of protection is determined by the claims. However, the description and drawings are to be used to interpret the claims. Finzelmerkmale or feature combinations from the shown and described different Ausführungsbeispie len can represent independent inventive solutions. The task underlying the independent inventive solutions can be found in the description of who. All information on value ranges in the present description is to be understood in such a way that it includes any and all sub-areas from it, for example, the information 1 to 10 is to be understood such that all sub-areas, starting from the lower limit 1 and the upper limit 10, are included are, ie all sub-areas begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, for example 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

For the sake of order, it should finally be pointed out that, for a better understanding of the structure, elements have sometimes been shown to scale and / or enlarged and / or reduced.

1 shows a schematic representation of a method for determining at least one material parameter 19 and / or at least one machining parameter 20 and / or for selecting or creating a machining program for the control 8 of a workpiece machining device 10. The workpiece machining device 10 is preferably a bending machine , preferably a bending press with two tools which can be moved against one another by a press drive and which are preferably designed as upper and lower tools. In an alternative embodiment, the bending machine could also be designed as a folding machine. The workpiece machining device 10 could, however, also be a cutting and / or welding device, in particular a laser cutting and / or laser welding device.

Such a method comprises the steps - depicted from right to left in FIG. 1:

(a) taking a workpiece sample 2 of a plate-shaped material, in particular a metal sheet, preferably from a sheet metal piece 3 or from a batch 4 of sheet metal pieces 3,

(d) bending the workpiece sample 2 by means of a bending device 1,

(b) performing at least one measurement on the workpiece sample 2 in at least one bent state of the workpiece sample 2, (c) Determination of at least one material parameter 19 and / or at least one machining parameter 20 and / or selection or creation of a machining program for the control 8 of a workpiece machining device 10 as a function of the result of the at least one measurement on the workpiece sample 2.

The bending of the workpiece sample 2 by means of the bending device 1 according to step (d) is preferably carried out by free bending, particularly preferably free of lateral forces. Fig. 2 shows a bending device 1, in which a workpiece sample 2 is clamped in a receptacle (shown schematically by the side bearings). One of the bearings is movable relative to the other bearing. Both bearings can be swiveled around a swivel axis. By means of a relative movement and / or by pivoting, the workpiece sample 2 present as a sheet metal piece can be bent as shown in FIG. 2 without the action of transverse forces by pure moment bending. In addition to the receptacle for the workpiece sample 2, the bending device 1 comprises at least one sensor, here an optical sensor 5, for carrying out at least one measurement on the workpiece sample 2 in at least one bent state of the workpiece sample 2. The sensor itself is preferably in the bending device 1 integrated.

The sensor, especially if it is e.g. is a force or pressure sensor, can also be integrated in a bending tool (in the embodiment of FIG. 2 this would be one or both bearings) of the bending device 1. If such a preliminary measurement is carried out directly in a bending machine as a workpiece machining device 10, a sensor could also be integrated in a bending tool of the bending machine.

As indicated in FIGS. 2 and 3, the at least one measurement can include measuring the curvature and / or the bending radius R of the workpiece sample 2. The curvature and / or the bending radius R are preferably measured by means of an optical sensor 5, in particular a laser sensor, with other measurement methods, such as e.g. the use of a tactile sensor is possible.

Subsequently, a relationship between the introduced bending moment M and the bending radius R or its reciprocal l / R can be determined from the measured values (see Fig.

3). Additionally or alternatively, a measurement of the bending angle of the workpiece sample 2 can also be carried out. The bending angle is preferably measured by means of an incremental encoder 6 (shown in the embodiment in FIG. 5).

While the principle of shear force-free or pure torque bending is illustrated schematically in FIG. 2, a possible embodiment of a bending device 1 is shown in FIGS. 5 and 6. The receptacle for the workpiece sample here comprises a first bearing block 13 and a second bearing block 14. A bearing block 13 can be displaced relative to the other bearing block 14 along a displacement direction 15. The bearing blocks 13, 14 can also be rotated relative to one another about an axis of rotation 16. The axes of rotation 16 are here essentially perpendicular to the direction of displacement 15. The bearing blocks 13, 14 each have one

Clamping device (e.g. a wedge connection) with which one side of the workpiece sample 2 can be clamped. In the preferred embodiment shown, the bearing blocks 13, 14 are each connected to a lever 17, 18 and can be rotated by this. 6 that the levers 17, 18 can be provided with rollers at their upper end. This enables the bending device 1 to be acted upon and thus to induce a bending moment in the workpiece sample with a vertical force F. Force and / or pressure sensor (s) 7 can be arranged below a mounting plate. Alternatively, the sensors can also be arranged in the area or directly when the force is applied.

The bending device 1 from FIG. 5 has (here: above the receptacle or the workpiece sample used) at least one optical sensor 5, in particular a laser sensor, which is preferably set up to measure the bending radius of the workpiece sample 2. Furthermore, the bending device 1 has at least one force and / or pressure sensor 7, in particular a piezo sensor or a strain sensor (e.g. strain gauge), which is preferably set up to measure the forces acting on at least one of the bearing blocks 13, 14. Finally, the bending device 1 can also have at least one position and / or displacement and / or angle sensor 6 (e.g. in the form of an incremental encoder) for determining the position and / or the relative position and / or the angle of rotation of the bearing blocks 13, 14.

Fig. 4 shows a bending device 1 for free bending, here the workpiece sample 2 rests since Lich and a force F is applied in the middle by a tool. there the relationship between the force F and the distance traveled s of the middle tool can be determined. Likewise, with variable lateral tools (supports), a relationship between the bending radius R or l / R and the distance L between the lateral tools can be determined. The course of the bending radius R or the bending curvature l / R can also be determined over the distance L.

Furthermore, the at least one measurement can include the measurement of the force F and / or the bending element M with which the workpiece sample 2 is subjected during the bending process. The force F and / or the bending moment M are preferably measured by means of a piezo sensor 7 (see, for example, embodiment of a bending device according to FIG. 5).

10 shows a variant of a bending device 1, in which the workpiece sample 2 is deformed by pivot bending. The workpiece sample 2 is clamped on one side between two tools and is bent at another point using a tool (here: downwards) (see arrow F). At this point it should be mentioned that in an alternative embodiment the bending device could also be a die bending device.

In order to be able to determine such force- or torque-dependent relationships, measurements are carried out in step c) at different bending states of the workpiece sample 2. It is particularly preferred if a bending flow curve is determined from the measurements on the workpiece sample 2, which curve shows in particular the yield stress as a function of the degree of deformation. Such a bending flow curve determined by (transverse force) free bending and subsequent optimization is shown in FIG. 8 (continuous line) and contrasted with a flow curve from tensile tests (dashed line). This difference also makes the great advantage of the invention clear: the data obtained by bending are much closer to the later machining process and allow the setting of optimized parameters.

Depending on the at least one measurement on the workpiece sample 2 and / or depending on the evaluation of the at least one measurement on the workpiece sample 2, at least one machining parameter can now be determined for the control of the workpiece machining device 10. As already mentioned, the workpiece processing device 10 can be a bending machine, in particular a bending press. In this case, it is preferred if the machining parameter 20 determined as a function of the at least one measurement on the workpiece sample 2 is the type of one or more bending tools (s) 21, 22 (see FIG. 7), in particular the size, shape and material of the / the bending tools (s) 21, 22 to be used, the amount of the pressing force (caused by the press drive of the bending press), in particular the maximum pressing force, and / or the chronological course of the pressing force and / or the reversal position of a bending tool 21, 22 includes. The tool is usually defined by the customer, while other manufacturing parameters (such as shortening the bend, immersion depth, etc.) are influenced.

It is preferred that a machining process of a workpiece is simulated in a workpiece machining device 10 by means of a process simulation program, which is based on the at least one determined material parameter 19 and / or the at least one determined machining parameter 20 and / or the selected machining program. Depending on the simulation result, at least one machining parameter 20 can be adapted for the control 8 of the workpiece machining device 10, as a result of which an optimal machining parameter 20 can be found in iterative steps. It is preferred if the iterative steps already take place in the testing device, that is to say in the bending device, and - if possible - not first in the bending machine.

Likewise, the bending of the workpiece sample 2 by means of a bending device 1 according to step (d) can be simulated by a calculation based on at least one material parameter 19. Depending on the deviation of the simulation result from the result obtained from the at least one measurement on the workpiece sample 2 in at least one bent state of the workpiece sample 2, at least one material parameter 19 can be adapted (i.e. optimized). The calculation for simulating the bending process can be repeated at least once with an adapted material parameter 19. It is preferred if the at least one material parameter 19 on which the calculation is based and adapted comprises the bending flow curve.

FIG. 7 schematically shows a method for processing (here: bending) a plate-shaped, preferably sheet-shaped workpiece 11 in a workpiece processing device 10 (here: bending press). The control 8 of the workpiece machining device 10 takes place as a function of at least one material parameter 19 of the workpiece 11 and / or at least one machining parameter 20 and / or a machining program. The at least one material parameter 19 and / or the at least one machining parameter 20 and / or the selection or creation of the machining program for the control of the workpiece machining device 10 can be determined, for example, as described above.

FIG. 9 shows a possible embodiment for determining the bending flow curve as a material parameter. An initial bending flow curve 23 is assumed, which can be found, for example, in a database for a specific workpiece. From this bending flow curve, a size is determined by means of a calculation model 24, which can also be determined with the bending device 1 by means of measurements. This size can be, for example, the moment curvature curve M / p. The size (M / p) _caic determined by means of the calculation model 24 is compared with the size (M / p) test obtained from measurements in the bending device 1 (see box 25). In the event that the deviation err is less than a predetermined limit value p _limit , the optimal bending flow curve has been reached. If not, a new bending flow curve is generated (see box 27). From this the size (M / p) _{caic is} determined again and the comparison 25 is repeated. This loop is run through until the deviation err is less than a predetermined limit value p _limit , with which an optimal bending flow curve has been obtained. With a bending flow curve determined in this way, which represents a material parameter according to the present invention, the actual bending process on a workpiece in the bending machine can now be optimized.

In general terms, such an embodiment is characterized in that the at least one material parameter 19 comprises a flow curve, in particular a bending flow curve, and that, based on an initial flow curve, a variable, in particular a torque-curvature relationship, is determined by means of calculation, which is determined by means of the bending device 1 is determined by measurement, and that depending on the deviation err the size calculated from the flow curve and the size obtained from measurements, the flow curve is adjusted, preferably in iterative steps, preferably until the deviation err _falls below a predetermined limit value pg _limit . It is preferred if the bending device 1 by means of which the workpiece sample 2 is bent is a device separate from the workpiece processing device 10 (FIG. 7). The bending device 1 can be actuated independently of the workpiece machining device 10.

7 shows such an arrangement of a workpiece processing device 10 for processing a workpiece 11, here a bending press, and an (additional) bending device 1 according to the invention. Workpiece processing device 10 and bending device 1 can be arranged in the same space or directly next to one another and / or be connected to one another via a data link 9.

The workpiece processing device 10 can comprise an upper bending tool 21 and a lower bending tool 22, wherein one bending tool can be moved towards the other. The workpiece 11 to be machined is arranged between the bending tools 21, 22.

The workpiece processing device 10 can, as already mentioned several times, be a bending machine. In this case, it is preferred if the bending of the workpiece 11 in the bending machine and the bending of the workpiece sample 2 in the bending device 1 are of different types. The bending of the workpiece 11 in the bending machine can e.g. done by die bending. The workpiece sample 2 can be bent in the bending device 1 by (transverse force) free bending, in particular by pure moment bending. Alternatively, the workpiece sample can also be bent using 3-point bending.

As can be seen from FIG. 7, the workpiece processing device 10 and the bending device 1 communicate with one another via a data connection 9. The measurement results and / or the evaluation of the measurement results of the at least one measurement on the workpiece sample 2 and / or at least one material parameter 19 determined from the measurement results and / or machining parameters 20 and / or a selected machining program can be sent to the controller 8 of the workpiece machining device 10 are transmitted.

As already mentioned, direction-dependent measurements can be carried out on workpiece samples 2 in order to be able to record any anisotropic properties of the workpiece. The information obtained from such measurements can also be transferred to other processing devices. For example, the orientation of the blank can be taken into account when cutting the individual workpieces. As already mentioned, improvements in processing could also be achieved with cutting and welding devices using the data obtained from a bending process, in particular a free bending process. The processing parameters there relate, for example, to the (welding) temperature, geometric shape of a cutting beam or its frequency (of the impulses), intensity, wavelength, etc. Their optimum setting can also be achieved with the data obtained according to the invention.

Reference number in position

1 bending device path

2 workpiece sample

3 sheet

4 batch

5 Optical sensor

6 position and / or path and / or

angle sensor

7 force and / or pressure sensor

8 control

9 Data connection

10 workpiece machining s device

11 workpiece

12 recording

13 First bearing block

14 Second bearing block

15 direction of displacement

16 axis of rotation

17 First lever

18 Second lever

19 material parameters

20 machining parameters

21 upper bending tool

22 lower bending tool

28 steps to determine a flow

Curve

F force

L distance between the bearing blocks

CKEN

M moment

R bending radius

Claims

Patent claims

1. A method for determining at least one material parameter (19) and / or at least one machining parameter (20) and / or for selecting or creating a machining program for the control (8) of a workpiece machining device (10), preferably a bending machine, in particular a bending press or a folding machine, and / or a cutting and / or welding device, in particular laser cutting and / or laser welding device, comprising the steps:

(a) taking a workpiece sample (2) of a plate-shaped material, in particular a sheet, preferably from a piece of sheet metal (3) or from a batch (4) of sheet pieces (3),

(b) performing at least one measurement on the workpiece sample (2),

(c) Determination of at least one material parameter (19) and / or at least one machining parameter (20) and / or selection or creation of a machining program for the control (8) of a workpiece machining device (10) depending on the result of the at least one measurement on the Workpiece sample (2),

marked by

(d) bending the workpiece sample (2) by means of a bending device (1), the at least one measurement being carried out on the workpiece sample (2) in at least one bent state of the workpiece sample (2).

2. The method according to claim 1, characterized in that the bending of the workpiece sample (2) by means of the bending device (1) by free bending and / or free of shear force.

3. The method according to any one of the preceding claims, characterized in that the bending of the workpiece sample (2) by means of the bending device (1) takes place by pure moment bending.

4. The method according to any one of the preceding claims, characterized in that the bending of the workpiece sample (2) by means of the bending device (1) by die bending or swivel bending.

5. The method according to any one of the preceding claims, characterized in that the at least one measurement on the workpiece sample (2) is carried out by means of at least one sensor (5, 6, 7) which is integrated in the bending device (1).

6. The method according to any one of the preceding claims, characterized in that the at least one measurement on the workpiece sample (2) by means of at least one sensor (5, 6, 7) which in a bending tool (21, 22) of the bending device (1) or the workpiece machining s device (10) is integrated, is carried out.

7. The method according to any one of the preceding claims, characterized in that the at least one measurement comprises the measurement of the curvature and / or the bending radius (R) of the workpiece sample (2), preferably the curvature and / or the bending radius (R) by means of an optical sensor (5), in particular a laser sensor, or a tactile sensor is measured.

8. The method according to any one of the preceding claims, characterized in that the at least one measurement comprises the measurement of the bending angle of the workpiece sample (2), wherein preferably the bending angle is measured by means of an incremental encoder (6).

9. The method according to any one of the preceding claims, characterized in that the at least one measurement comprises the measurement of the force (F) and / or the bending moment (M) with which the workpiece sample (2) is acted upon during the bending process, wherein preferably the force (F) and / or the bending moment (M) is measured by means of a piezo sensor (7) or a strain sensor.

10. The method according to any one of the preceding claims, characterized in that in step c) measurements are carried out at different bending states of the workpiece sample (2).

11. The method according to any one of the preceding claims, characterized in that a bending flow curve is determined from the measurements on the workpiece sample (2), which in particular represents the yield stress as a function of the degree of deformation.

12. The method according to any one of the preceding claims, characterized in that at least one processing parameter for the control (depending on the at least one measurement on the workpiece sample (2) and / or depending on the evaluation of the at least one measurement on the workpiece sample (2) 8) the workpiece processing device (10) can be determined.

13. The method according to any one of the preceding claims, characterized in that the workpiece processing device (10) is a bending machine, in particular a press or a swivel bending machine, and the processing parameters (20) determined as a function of the at least one measurement on the workpiece sample (2) Immersion depth and / or springback and / or bending shortening and / or the type of one or more bending tools (21), in particular the size, shape and material of the bending tool (s) (21) and (21) and / or the amount of the pressing force, in particular the maximum pressing force, and / or the chronological course of the pressing force and / or the reversal position of a bending tool (21, 22) and / or the stop position of at least one backgauge.

14. The method according to any one of the preceding claims, characterized in that by means of a process simulation program, which is based on the at least one determined material parameter (19) and / or the at least one determined machining parameter (20) and / or the selected machining program, a machining process of a workpiece is simulated in a workpiece machining device (10), preference being given to adapting at least one machining parameter (20) for the control (8) of the workpiece machining device (10) as a function of the simulation result.

15. The method according to any one of the preceding claims, characterized in that the bending of the workpiece sample (2) by means of a bending device (1) according to step (d) is simulated by a calculation based on at least one material parameter (19), and that, depending on the deviation of the simulation result from the result obtained from the at least one measurement on the workpiece sample (2) in at least one bent state of the workpiece sample (2), at least one material parameter Meter (19) is adjusted, the calculation for simulating the bending process preferably being repeated at least once with an adapted material parameter (19) and / or preferably the at least one material parameter (19) on which the calculation is based and adapted, the Bending flow curve includes.

16. The method according to any one of the preceding claims, characterized in that the at least one material parameter (19) comprises a flow curve, in particular a bending flow curve, and that starting from an initial flow curve by means of calculation, a size, in particular a moment-curvature relationship, is determined, which is determined by means of the bending device (1) by measurement, and that, depending on the deviation (err) of the size calculated from the flow curve and the size obtained from measurements, the flow curve is adapted, preferably in iterative steps, preferably to the deviation (err) exceeds a predetermined limit value (p Renz _g) below.

17. A method for processing, preferably bending and / or cutting and / or welding, a plate-shaped, preferably sheet-shaped workpiece (11) in a workpiece processing device (10), the control (8) of the workpiece processing device (10) depending on at least one material parameter of the workpiece (11) and / or at least one machining parameter and / or a machining program, characterized in that the determination of the at least one material parameter and / or the at least one machining parameter and / or the selection or creation of the machining program for the control (8 ) the workpiece machining device (10) according to one of the preceding claims.

18. The method according to claim 17, characterized in that the Biegevorrich device (1), by means of which the workpiece sample (2) is bent, is a separate device from the workpiece processing device (10), preferably the bending device (1) independently of the Workpiece processing device (10) can be actuated.

19. The method according to claim 17 or 18, characterized in that the workpiece machining device (10) is a bending machine, in particular a bending press or a swivel bending machine, wherein preferably the bending of the workpiece (11) in the Bending machine and the bending of the workpiece sample (2) in the bending device (1) are of different types, preferably the bending of the workpiece (11) in the bending machine by die bending and / or the bending of the workpiece sample (2) in the bending device (1) by free bending, in particular by bending without lateral force.

20. The method according to any one of claims 17 to 19, characterized in that the workpiece machining device (10) and the bending device (1) communicate with one another via a data connection (9), preferably the measurement results and / or the evaluation of the measurement results the at least one measurement on the workpiece sample (2) and / or at least one material parameter (19) and / or machining parameter (20) determined from the measurement results and / or a selected machining program are transmitted to the controller (8) of the workpiece machining device (10) ,

21. Bending device (1) for bending a workpiece sample (2) comprising at least one receptacle (12) for the workpiece sample (2) and at least one sensor (5, 6, 7) for carrying out at least one measurement on the workpiece sample (2) in at least one bent state of the workpiece sample (2), the bending device (1) preferably being a bending device for bending a workpiece sample (2) without shear force, preferably pure moment bending.

22. Bending device according to claim 21, characterized in that the acquisition has a first bearing block (13) and a second bearing block (14), a bearing block (13) being displaceable along a displacement direction (15) relative to the other bearing block (14) and wherein the bearing blocks (13, 14) can be rotated relative to one another about at least one axis of rotation (16), the at least one axis of rotation (16) preferably being essentially normal to the direction of displacement (15).

23. Bending device according to claim 21 or 22, characterized in that the bearing blocks (13, 14) each have a clamping device, in particular a screw or hyd raul clamping device or a wedge connection, with which one side of the workpiece sample (2) can be clamped ,

24. Bending device according to one of claims 21 to 23, characterized in that the bearing blocks (13, 14) are each connected to a lever (17, 18) and can be rotated through them.

25. Bending device according to one of claims 21 to 24, characterized in that the bending device (1) has at least one sensor, preferably an optical sensor (5), in particular a laser sensor, and / or a tactile sensor, preference being given to the at least one Sensor for measuring the bending radius of the workpiece sample (2) is set up.

26. Bending device according to one of claims 21 to 25, characterized in that the bending device (1) has at least one force and / or pressure sensor (7), in particular a piezo sensor or a strain sensor, which preferably for measuring the at least one of the bearing blocks (13, 14) and / or on at least one of the levers (17,

18) acting forces is established.

27. Bending device according to one of claims 21 to 26, characterized in that the bending device (1) at least one position and / or displacement and / or angle sensor (6), preferably in the form of an incremental encoder, for determining the position and / or the relative position and / or the angle of rotation of the bearing blocks (13, 14).

28. Arrangement of a workpiece processing device (10) for processing a workpiece (11), preferably a bending machine, in particular a bending press or a swivel bending machine, and / or a cutting and / or welding device, in particular special laser cutting and / or laser welding device, and a bending device (1) according to any one of claims 21 to 27, wherein the workpiece processing device (10) and the bending device (1) are separate, in particular independently operable devices that are arranged in the same room or directly next to each other and / or via a data connection (9) are communicative with each other.

29. Use of a bending device (1) according to one of claims 21 to 27 and / or an arrangement according to claim 28 in a method according to one of claims 1 to 20.