Method and apparatus for quality evaluation of machining operations

Abstract

The present invention uses specific processing parameters (P i The present invention relates to a method and an apparatus (1) for evaluating the quality of a machining operation, in which a workpiece (W) is machined along a machining trajectory (X) using a machining result (R(x)) of the machining operation along the machining trajectory (X) is measured by at least one sensor (2) and at least one sensor signal (S j (x)) is recorded and at least one quality parameter (Q k (x)) is the signal from at least one sensor (S j and determining at least one quality parameter (Q) based on the processing result (R(x)) of the processing operation to evaluate the quality of the processing result (R(x)). k (x)) is the threshold of the quality parameter (Q k,o (x), Q k,u( In the present invention, the target value (P i,soll (x)) to the change in processing parameters (ΔP i (x)) is automatically taken into account during the evaluation of the quality of the machining operation, whereby the quality parameter threshold (Q k,o (x), (Q k,u (x)), instead of the change in processing parameters (ΔP i (x)) and the quality parameter threshold (Q k,o (x), (Q k,u (x)) is determined, and at least one quality parameter (Q k (x)) is the adapted quality parameter threshold (Q k,o (x), (Q k,u (x)).

Description

Technical Field

[0001] The present invention relates to a method for evaluating the quality of a machining operation, which comprises machining a workpiece along a machining path using specific machining parameters, measuring the machining result of the machining operation along the machining path with at least one sensor, recording at least one sensor signal, determining at least one quality parameter from the at least one sensor signal, and comparing the at least one quality parameter with a quality parameter threshold for quality evaluation of the machining result of the machining operation along the machining path.

[0002] Furthermore, the present invention relates to an apparatus for evaluating the quality of a machining operation of a workpiece using specific machining parameters along a machining locus.

Background Art

[0003] Machining operations include, in particular, joining operations in which workpieces are joined to each other or workpieces are coated, such as, for example, welding or soldering operations, but also surface treatment operations in which workpieces are treated with plasma to prepare them for subsequent machining operations, such as, for example, plasma treatment operations. For example, the surface of a workpiece can be treated with plasma before lacquer coating in order to remove residues from the surface and / or to improve the adhesion of the lacquer layer.

[0004] It is well known to monitor or evaluate the quality of a processing operation in order to eliminate defective products or to adapt the processing parameters as appropriate to improve quality. To this end, the processing trajectory is evaluated after the machining operation, from which the quality of the machining operation is evaluated. In the simplest case, the quality assessment can be carried out in the form of a visual assessment by a qualified person. Typically, however, the processing results of the processing operation along the processing trajectory are automatically measured by corresponding sensors, and at least one quality parameter is determined from the sensor signals. To evaluate the quality, at least one quality parameter is compared with a threshold value of the quality parameter. For example, a weld seam as a processing trajectory of a welding process can be measured with a camera after the welding process, preferably with illumination, from which the seam width and seam height of the weld seam can be determined with a suitable image processing algorithm, and from which the quality parameter can be derived. Depending on the processing task or the welding task, different quality parameters can be used to define the quality of the weld seam. For example, in the case of a visible weld seam, in addition to the mechanical properties of the weld seam, it is also important that the weld seam is as narrow and regular as possible, while in the case of an invisible weld seam, the strength of the joint, and thus a sufficient weld penetration depth, is more important. At least one quality parameter suitable for each processing operation is correspondingly defined and compared with a threshold value of a specific quality parameter, for example, an upper and lower threshold value, in order to be able to automatically evaluate the quality. Quality parameters are usually determined by evaluating the optimally processed workpiece using the IO ("in order") processing trajectory. In welding, for example, the size of the weld undercut, the so-called a dimension, the seam height, the end capper at the weld seam end, etc. can be used as quality parameters.

[0005] EP 3 566 806 A1 describes a welding process as a processing operation in which optimal welding parameters determined based on test welds of a test workpiece are automatically used in the welding process to achieve specific quality criteria. The determination of the optimal welding parameters for each welding operation is performed via the optimal values of the calculated quality function via the respective optimal welding parameters of the test welds.

[0006] EP 1 642 366 B1 and WO 00 / 35622 A1 describe a method for monitoring the quality of a welding process, in which information about the generated weld seam is compared with a predetermined value, and if there is a deviation, the welding parameters are adapted accordingly, and if there is a large deviation, a warning is issued. In this case, the processing parameters are adjusted to a predetermined target value.

[0007] DE 10 2019 200 482 A1 describes a processing operation in which a workpiece is processed with predetermined processing parameters, and if the processing result deviates, the processing parameters are correspondingly adapted to always achieve a processing result that is as constant as possible.

[0008] A welding system with monitoring of a welding process aimed at keeping the conditions of the processing result constant and the quality constant is known from US 2009 / 0173726 A1. Adapting the quality evaluation to intentional changes in the processing parameters during the processing of the workpiece has not been discussed and is not desirable.

[0009] In known quality assessment systems for machining operations, especially welding operations, it is checked whether certain criteria are within predetermined limits. For example, a manufactured weld seam is compared to a predefined "ideal weld seam", from which the quality of the manufactured weld seam is evaluated. However, if the machining parameters are intentionally changed manually or automatically during machining, the automatic adaptation of the quality criteria is not performed during quality assessment and must be done manually, which is time-consuming. This can lead to the quality of the machining operation being evaluated as insufficient because the changes in the machining parameters intentionally made during the processing operation were not automatically taken into account. Also, the quality of the machining operation may be positively evaluated even though the results do not meet the quality criteria. For example, in a welding process, it may be necessary to adapt certain welding parameters due to the tolerances of the workpieces. For example, if the gap width increases due to the tolerances of the workpiece or the clamping device, it may be necessary to adapt the wire feed and other welding parameters. If the change in the target value of the welding parameters is not automatically notified to the quality assessment system, the quality of the welding may not be correctly evaluated.

Summary of the Invention

[0010] The object of the present invention is to provide the above-described method and apparatus for evaluating the quality of a machining operation, whereby the above-described drawbacks related to the intentional execution of machining parameters during the machining operation do not occur, and a reproducible explanation regarding the quality of the machining operation and the machined workpiece becomes possible. The automatic quality assessment system should also be able to be used in the case of intentionally executed manual or automatic changes in the processing parameters and should be able to provide a reliable explanation regarding the quality of the processing operation or the quality of the processed workpiece.

[0011] The object according to the present invention is achieved from the perspective of a method by the fact that, in the evaluation of the quality of a machining operation, the executed changes in the machining parameters are automatically taken into account from the target value during the machining of the workpiece along the machining path. That is, instead of the quality parameter threshold, a quality parameter threshold adapted to the change in the machining parameter is determined, and at least one quality parameter for evaluating the quality of the machining result of the machining operation along the machining path is compared with the adapted quality parameter threshold. In this way, the method according to the present invention provides that the actual value of the processing parameter is transmitted to the quality evaluation system during the processing operation, and as a result, the intentionally made change in the target value of the processing parameter is automatically taken into account when evaluating the quality of the processing operation by adapting the quality parameter threshold according to the change in the processing parameter. As a result, the quality of the machined workpiece can be evaluated more reliably, for example, it is possible to prevent workpieces evaluated as being of poor quality or workpieces that are positively evaluated due to force majeure despite not meeting the quality standards from being improperly rejected. Importantly, only the intentional changes in the machining parameters are considered, and changes due to confusion are not considered. Manual changes in the target value of the processing parameter, or automatic changes in the target value of the processing parameter as a result of an adaptive processing operation, are considered intentional changes. The target value of the machining parameter can be an integrated parameter such as, for example, the set average welding current or average wire feed, and these machining parameters may deviate from these set values during machining. The intentionally made change in the target value of the machining parameter can be transmitted to the location where the quality evaluation is performed, either standardly or only when it occurs. By considering the change in the target value of the machining parameter and adapting the threshold of the quality parameter to the change in the machining parameter, the reliability of the quality evaluation can be enhanced. The influence of the change in the machining parameter on the quality parameter varies greatly depending on the type of machining. The relationship between the change in the machining parameter and the change in the quality parameter for evaluating the quality of the machining operation and the machining result can be determined based on test machining and stored in a table or a functional relationship.Due to automatic consideration during quality evaluation, even if the processing parameters are changed according to the normal tolerances of the workpiece, the quality evaluation system can be used and it is possible to provide reliable results.

[0012] The executed changes to the processing parameters can be determined from the target values by comparing the actually transmitted values of the processing parameters with the transmitted target values of the processing parameters during the processing of the workpiece along the processing trajectory. In this case, the target value is the one before the change and the actual value is the one after the change. Thus, in the so-called "online method", since the changes in the processing parameters are virtually determined and transmitted in real time, the quality monitoring of the processing operation along the processing trajectory can be carried out at any time using real data. Also, the changes in the processing parameters include, for example, system-related changes that can occur when replacing parts subject to wear of the processing device. For example, when replacing the contact tube of the welding torch, the welding voltage decreases. If these intended changes in the processing parameters and the related changed quality parameter thresholds are also considered when evaluating the quality of the processing operation, a more reliable explanation regarding the quality of the processing operation or the quality of the workpiece being processed during the processing operation is obtained as a result.

[0013] Alternatively or additionally, the executed changes from the target values of the processing parameters and / or the actually transmitted values of the processing parameters and / or the transmitted target values of the processing parameters can also be recorded during the processing of the workpiece along the processing trajectory and used later for automatic consideration in the evaluation of the quality of the processing operation along the processing trajectory. In this so-called "offline method", the changes in the processing parameters and the related thresholds of the quality parameters are recorded and saved for later use, so that they can be used when implementing the quality monitoring of the processing operation.

[0014] According to a further feature of the present invention, the threshold value of the quality parameter adapted to the change in the process parameter is determined from the stored threshold value of the quality parameter for a specific process parameter. When the threshold value of the result quality parameter capable of evaluating the process result is stored for the most changed process situation and the most changed process parameter, the quality parameter threshold value can be determined from these stored values as a function of each actual process parameter. As the quality parameter threshold value, an upper limit value and a lower limit value can be defined, and a quality parameter average value having a specific maximum quality parameter variation width can also be defined. The stored quality parameter threshold value can be stored in the same memory or the same database as the process parameter, or can be stored in another memory or database.

[0015] The stored quality parameter threshold value can be determined, for example, from a test processing operation or a processing test for a specific processing parameter and a specific defect, such as a test welding operation or a welding test.

[0016] The quality parameter threshold value adapted to the change in the processing parameter is preferably determined by interpolation of the stored quality parameter threshold value for a specific processing parameter. By such an interpolation method, each quality parameter threshold value can be determined for the most changed process parameter without a large computational effort quickly.

[0017] Preferably, when determining at least one quality parameter from at least one sensor signal for measuring the processing result, a change in at least one processing parameter is taken into account. For example, when determining the seam width of the weld seam as a quality parameter of the welding process, a change in the feed rate of the welding wire that has a great influence on the seam width can be considered.

[0018] When evaluating the quality of a machining operation, for example, environmental parameters such as workpiece temperature, ambient temperature, air humidity, etc. can be added and considered. By including such environmental parameters that may depend on the machining trajectory, the result of quality evaluation can be further improved.

[0019] The machining results along the machining trajectory can be measured with the help of workpiece non-destructive measurement means, for example, using at least one sensor such as an optical sensor, especially a laser scanner, a camera, etc., an X-ray sensor, and / or a temperature sensor, and it is possible to record at least one sensor signal. Recording the machining results with the help of non-destructive measurement methods, preferably non-contact sensors, can perform the measurement of the machining results particularly quickly along the entire machining trajectory and has the advantage that the machined workpiece is not changed in the process. When there are specific influencing factors, it may be advantageous to perform the measurement of the machining results along the machining trajectory immediately after machining the workpiece. For example, the temperature profile in the material of the workpiece to be machined can provide information about the material structure of the machining results within and around the machining trajectory immediately after machining is performed. For certain quality parameters, since the quality of the machining operation can be evaluated only after this period, it may be advantageous to measure the machining results along the machining trajectory some time after machining the workpiece.

[0020] Alternatively or additionally, the machining result along the machining path can be measured, for example, by making incisions through the workpiece at various points of the machining result along the machining path and, in particular, by using at least one sensor to create an image of the surface of the incision, with the help of a destructive measurement method that destroys the workpiece, and at least one sensor signal can be recorded. For example, micro-incisions can be made at specific intervals of the machining result along the machining path, from which specific quality parameters can be derived. Such a measurement method is, of course, more complex but also provides essential insights into the internal structure of the machining result along the machining path that could not be detected or could only be detected "insufficiently" by non-contact measurement methods. The micro-incisions of the machining result recorded along the machining path can be analyzed using various methods, especially image processing methods associated with a camera. By using specific chemical substances, the recognition of the microstructure of the microsections of the machining result can be improved. Also, macroscopic inspection of the microsections after the machining operation can yield characteristic quality parameters. The microsections are analyzed, determined in the form of specific sensor signals, stored, and then the quality parameters of the machining result along the machining path can be characterized. In addition to the production of microsections, tensile tests, bending tests, etc. of the workpiece can also be considered.

[0021] According to a further feature of the present invention, the machining result along the machining path is measured during machining of the workpiece by at least one sensor, and the measurement speed of the machining path preferably corresponds to the machining speed. In a variant of this embodiment, the evaluation of the quality of the machining operation or the measurement of the machining path of the workpiece is carried out directly after machining of the workpiece or in a relatively short time. In this case, it is advantageous for the quality evaluation system to be moved in synchronization with the machining system with respect to the workpiece. For example, a camera for measuring the machining path can be attached to the same robotic arm that also carries the machining tool, and the machining path can be analyzed following machining of the workpiece. In this case, the measurement of the machining result along the machining path is carried out at the same speed as the machining of the workpiece. Of course, the quality evaluation system and the processing system can be stationary, the workpiece can move during processing, or it is also possible to move both the quality evaluation system and the processing system and the workpiece in opposite directions relative to each other.

[0022] The machining result along the machining path can also be measured after completion of machining of the workpiece by at least one sensor, and the measurement speed of the machining result along the machining path is preferably greater than the machining speed of the machining operation. When the measurement of the processing result along the processing path is carried out independently of the processing of the workpiece, it is also possible to select the measurement speed to be substantially faster than the processing speed. For example, the optical scanning of the machining result along the machining path after machining of the workpiece can be carried out much faster than the machining of the workpiece itself. Furthermore, several executions of the measurement of the machining result along the machining path can be carried out with different sensors, and then the quality parameters can be determined from the different sensor signals. Furthermore, it is also possible to evaluate workpieces from multiple machining stations at one measurement station.

[0023] If at least one quality parameter exceeds a quality parameter threshold or a conformity quality parameter threshold, a warning can be output and / or the excess can be saved. The warning can be given, for example, in an acoustic, optical, or mechanical form via a vibration mechanism. In this way, it can be pointed out that the quality parameter is exceeded. This warning can also be transferred to a higher-level location via a corresponding communication channel.

[0024] The warning can be changed as a function of the degree to which at least one quality parameter exceeds the quality parameter threshold or the conformity quality parameter threshold. For example, the volume of an acoustic warning, the luminous intensity of an optical warning, or the flashing frequency can be adapted to the magnitude of the quality deviation, and the magnitude of the quality deviation can be notified to the staff by the warning.

[0025] When using a welding seam as the processing track, the processing parameters of the welding process: welding current, welding voltage, the conveying speed of the welding wire, the incident angle of the welding torch with respect to the workpiece, the relative position of the welding torch with respect to the workpiece, and / or the welding speed are preferably considered. Such a welding process includes, in contrast to welding, a soldering process in which melting of the base material of the workpiece hardly occurs.

[0026] The object according to the present invention is likewise achieved by the above-described apparatus for evaluating the quality of a processing operation, and this apparatus is installed for carrying out the above method. With regard to the advantages that can be achieved thereby, reference is made to the above description of the method. The apparatus for quality evaluation is characterized by a corresponding connection to a processing device, and this connection enables the transmitted executed changes of the processing parameters during the processing of the apparatus for quality monitoring, and the threshold value of the quality parameter can be automatically adapted to the change of the processing parameter.

Brief Description of the Drawings

[0027] The present invention will be further described with reference to the accompanying drawings.

[0028]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3

Figure 4

DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 shows a schematic machining operation in which a workpiece W having specific machining parameters P i (x) is machined along a machining trajectory X to form a machining result R(x). The machining apparatus 10 mounts each machining head 12 on which the workpiece W is machined, and includes a machining robot 11 that leads to the formation of the machining result R(x) along the machining trajectory X. To machine the workpiece W, a specific target value of the machining parameter P i,soll (x) is selected from a plurality of possible machining parameters P i (x) stored in, for example, a database or a memory 9, and the workpiece W is machined with this machining parameter P i (x) to achieve a desired machining result. By manual intervention on the machining apparatus 10 or also by automatic machine intervention (symbolized by a dotted line) in an adaptive machining operation, the machining parameter Pi,soll Change of the target value of (x), thus the machining parameter ΔP during the machining operation i Can bring about the desired or necessary changes to (x). In the case of subsequent quality monitoring of the machining result R(x) of the machining operation by appropriate inspection of the machined workpiece W along the machining trajectory X, the machining parameter ΔP i Such a change in (x) is usually not automatically taken into account from the target value of the machining parameter P i,soll by known methods, and as a result, an incorrect evaluation of the quality of the workpiece W may occur. Since the changed machining result R′(x) does not correspond to the expected machining result R(x), the machining parameter ΔP i is intentionally changed due to the fact that the conventional quality control system fails, and usually, a complex manual inspection of the workpiece W machined using the intentionally changed machining parameter ΔP i is required for the workpiece W machined using (x).

[0030] The processing device 10 may be, for example, a welding device for performing a joining process on the workpiece W. In this case, the welding torch is fixed to the welding robot, and with this welding torch, two or more workpieces W can be joined to each other or a layer can be applied to the workpiece W. The machining result R(x) in this case is the weld seam between two or more workpieces W to be joined or the weld bead on the surface of the workpiece W. Furthermore, the processing device 10 can also be formed by a device for treating the surface of the workpiece W with a plasma torch, a painting device, etc. Depending on the machining operation, the machining result R(x) along the machining trajectory X, and furthermore, the quality of the machining operation and the evaluation of each machining result R(x) along the machining trajectory X also differ.

[0031] Figures 2A to 2D schematically show a method for evaluating the quality of a machining operation by various sensors 2 for measuring each machining result R(x) of the machining operation along the machining trajectory X based on a welding process as the machining operation.

[0032] Figure 2A shows the quality evaluation of the machining operation (so-called "online" quality evaluation) performed during or immediately after machining the workpiece W. Thus, the sensor 2 for measuring the machining result R(x) of the machining operation is arranged along the machining trajectory X of the workpiece W at or behind the machining head 12 so that the machining result R(x) can be measured along the machining trajectory X immediately after the machining operation. The machining head 12 is, for example, a welding torch 8, through which the consumable welding wire 7 is supplied to the workpiece W, and joining processes and build-up welding processes can be carried out. An arc LB burns between the end of the welding wire 7 and the workpiece W, melting the welding wire 7 and the workpiece W. Possible sensors 2 for measuring the machining result R(x) along the machining trajectory X of the workpiece W are, for example, an optical sensor 3, a camera 4, an X-ray sensor 5 or a temperature sensor 6, which measure the machining result R(x) along the machining trajectory X and give a corresponding sensor signal Sj(x) as a function of the points along the machining trajectory X. In the "online" quality evaluation, the speed of measuring the machining result along the machining trajectory X by the sensor 2 is preferably the speed of the machining operation, i.e., the machining speed, for example, the welding speed v s (x).

[0033] As an alternative or addition to the "online" quality evaluation, according to Figure 2B, an "offline" quality evaluation can also be performed. In this case, the workpiece W or the machining result R(x) is measured along the machining trajectory X by a corresponding sensor 2, such as an optical sensor 3, a camera 4, or an X-ray sensor 5, etc., after the machining operation has been performed, and a corresponding sensor signal S j (x) is provided. In the case of "offline" quality evaluation, the speed of measuring the machining result R(x) along the machining trajectory X by the sensor 2 after the machining of the workpiece W is completed can be higher than the machining speed. Nevertheless, in contrast to the "online" quality evaluation, the "offline" quality evaluation represents additional time consumption.

[0034] In Figure 2C, a method for evaluating the quality of a machining operation is outlined. For the analysis of the machining result R(x), the workpiece W is destroyed along the machining trajectory X, and at multiple points of the machining result R(x) along the machining trajectory X, a microsection of the workpiece W is generated in the area of the machining result R(x), and the analysis of the machining result is performed. These microsections can be measured by the corresponding sensor 2 and image processing means, and the sensor signal S j (x) is provided. Similarly, information regarding the machining operation and the quality of the machining result R(x) for the workpiece W at a specific point along the machining trajectory X is provided. For example, during a welding process, such microsections can provide an indicator of the penetration depth of the weld seam as the machining result R(x).

[0035] As shown in Figure 2D, a quality parameter Q k (x) that characterizes the quality of the processing result R(x) of the processing operation for each processing task can be determined from various sensor signals S j (x) of the processing result R(x). Depending on the processing task, different quality parameters Q k (x) that quantify the quality of the processing result R(x) along the processing trajectory X may exist. To evaluate the quality, here, at least one quality parameter Q k (x) is compared with quality parameter thresholds, for example, an upper quality parameter threshold Q k,o (x) and a lower quality parameter threshold Q k,u (x). If the quality parameter Q k,o (x), Q k,u (x) is exceeded, the quality is considered not to be met and is indicated as "NIO" (not in order). If all quality parameters Q k (x) are within their quality parameter thresholds Q k,o (x), Q k,u (x), the quality of the machining operation is considered to be met, and the workpiece W is classified as "IO" (in order). During the machining operation, machining parameter ΔP iIf there are intentional manual or automatic changes in (x), the processing result R′(x) will consequently change. This changed processing result R′(x) is then measured by sensor 2, and from this, the quality parameter Q′ k (x) is determined, and compared with the original quality parameter threshold Q k,o (x), Q k,u (x), generally an incorrect quality indication will occur. Therefore, the object of the present invention is to automatically take into account the intentionally made changes in the processing parameter ΔP i (x) during the processing operation in the evaluation of the quality of the processing operation and the changed processing result R′(x). This is preferably the adapted and changed quality parameter threshold Q′ k,o (x), Q′ k,u (x).

[0036] Figure 3 shows a schematic of the method according to the present invention for evaluating the quality of a machining operation and the machining result R(x) along a machining path X on a workpiece W. The device 1 for evaluating the quality of the machining operation measures various sensor signals S j (x) along the machining path X during the machining operation by means of a sensor 2 attached to the machining head 12 of the machining device 10 (``online'' quality evaluation). Alternatively or additionally, after the processing operation, the sensor signals S j (x) measured and recorded by the corresponding sensor 2 along the processing path X are provided to the device 1 for quality evaluation. At least one quality parameter Q j (x) is determined from at least one sensor signal S k (x), and at least one quality parameter Q k (x) is compared with the quality parameter thresholds Q k,o (x), Q k,u (x) for evaluating the quality of the processing operation and the processing result R(x) along the processing path X. If the quality parameter thresholds Q k,o (x), Q k,u (x) are exceeded, the quality is considered not to be met, and the workpiece is classified as ``NIO'' (not in order) and, for example, displayed on the display 13. Also, all quality parameters Q kIf (x) is within its quality parameter threshold Q k,o (x), Q k,u If it is within (x), it is determined that the quality of the processing operation and the processing result R(x) is satisfied, and the workpiece W is classified as "IO" (in order) and displayed on, for example, the display 13. Also, the quality parameter threshold Q k,o (x), Q k,u If it exceeds (x), it is also possible to output an acoustic warning with the speaker 14, for example.

[0037] According to the invention, when the processing apparatus 10 evaluates the quality of the processing operation and the processing result R(x) along the processing locus X, by connecting the processing apparatus 10 and the apparatus 1 for evaluating the quality of the processing operation, during the processing of the processing locus X of the workpiece W, the processing parameter P i,soll The processing parameter ΔP from the target value of (x) i The change of (x) is automatically taken into account. This is, for example, based on the changed situation, an adapted quality parameter threshold Q′ k,o (x), Q′ k,u (x) may be defined and carried out, and these are stored with respect to the change of the processing parameter ΔP i (x) or are defined by the corresponding calculation rules. The automatic evaluation of the quality of the processing operation and the changed processing result R′(x) is thus based automatically on the adapted quality parameter threshold Q′ k,o (x), Q′ k,u (x), and as a result, the reliability of quality monitoring can be enhanced. Furthermore, thereby, the quality evaluation becomes suitable for an adaptive processing system. As a result, based on the tolerances that occur conventionally, the change ΔP i (x) of the processing parameter is changed for processing, and even for a workpiece W that can provide other processing results R′(x) as an ideal workpiece W, it is determined to be "IO" (in order) by the quality evaluation system and does not require complicated manual checking. The adapted quality parameter threshold Q′ k,o (x), Q′ k,u (x) is for a specific processing parameter P iThe stored quality parameter threshold Q, which can be defined from the test machining operation for (x) k,o,g (x), Q k,u,g From (x), for example, the stored quality parameter threshold Q k,o,g (x), Q k,u,g Is determined by interpolation of (x).

[0038] FIG. 4 shows an example of intentionally changing the machining parameter ΔP i (x) and considering it in the quality evaluation of the machining operation using the welding process. On the left side of the figure, the workpiece W before machining is shown at the top, and below it, the workpiece W after machining or after the welding process is shown in a cross-sectional view. The workpieces W usually overlap without gaps, and the welding process is performed with preset welding parameters. In quality monitoring, for example, the width B(x) and height H(x) of the weld seam N are determined as quality parameters along the machining trajectory X, and the width B o (x), B u (x) and height H o (x), H u (x) are compared with the thresholds for (x), and the conditions B u (x) < B < B o (x) and H u (x) < H < H o (x) are satisfied, the quality of the machining operation is positively evaluated and the workpiece is classified as "IO".

[0039] In practice, usually, tolerances occur. For example, as shown on the right side of FIG. 4, a gap d occurs between the workpieces W. During the welding process, these changed conditions cause, for example, the feed rate v d (x) and the welding current I(x) to increase, and the welding speed v s(x) is reduced, and it is manually or automatically (adaptive welding process) applied. As a result, a weld seam N having a large width B' and a large height H' is obtained as compared with the case of processing the workpiece W without the gap d (the left part in FIG. 4). If the quality evaluation is performed without automatically considering the changed conditions and the intentionally made changes of the processing parameters, the width B' and the height H' of the weld seam N are considered unacceptable, the quality of the processing operation is negatively evaluated, and for example, the workpiece is marked as non-conforming ( "NIO": not in order) or will be sent for manual inspection or post-processing.

[0040] In the method according to the invention for quality evaluation, the processing parameter ΔP i the intentionally made change of (x) (here, for example, the transport speed v d (x) and the increase of the welding current I(x) and the welding speed v s (x) decrease) is notified to the quality evaluation and taken into account in the quality evaluation. For example, the quality parameter Q' i adapted based on the change of the processing parameter ΔP k,o (x), Q' k,u (x) threshold values are defined for the evaluation of the quality of the processing operation. In the illustrated example, the upper and lower threshold values for the width B' o (x), B' u of the weld seam N and the upper and lower threshold values for the height H' o (x), H' u (x) of the weld seam N are adapted to the changed welding parameters. As a result, since the condition of B' u (x) < B' < B' o (x) and H' u (x) < H' < H' o (x) is satisfied, the processed result R'(x) after the change or the changed weld seam N' in the right part in FIG. 4 is also correctly evaluated with respect to the quality. Due to the automatic consideration of the intentionally made changes of the processing parameter ΔP i in the quality monitoring, the workpiece W is also correctly classified as "IO" in this case, and the manual inspection of the workpiece W can be omitted.

[0041] Processing parameter ΔP i Quality parameter Q' adapted to the change in (x) k,o (x), Q' k,u The holding value of (x) is the normal processing parameter P i Quality parameter Q for (x) k,o (x), Q k,u It can be filed and stored according to a table or specific rules like the original threshold value of (x). The stored value and quality parameter Q k,o (x), Q k,u Processing parameter P between the thresholds of (x) i (x) can be determined by interpolation. The quality evaluation system can access this data regardless of where this data is available or stored. Quality parameter Q k,o (x), Q k,u Instead of the upper and lower threshold values of (x), the average value of the quality parameter Q k,m (x) and the maximum variation width ΔQ of the quality parameter around this average value k It is also possible to evaluate the quality of the processing result R(x) using these.

Claims

**Claim 1** A method for evaluating the quality of a machining operation for machining a workpiece (W) along a machining trajectory (X) using specific machining parameters (P ｉ (x)), comprising: The machining result (R(x)) of a machining operation along a machining trajectory (X) is measured by at least one sensor (2), and at least one sensor signal (S ｊ (x)) is recorded, and at least one quality parameter (Q ｋ (x)) is determined based on at least one sensor signal (S ｊ (x)) in order to evaluate the quality of the machining result (R(x)) of the processing operation, and at least one quality parameter (Q ｋ (x)) is compared with a threshold value (Q ｋ，ｏ (x), Q ｋ，ｕ（ x)) During the evaluation of the quality of a machining operation, during the machining of a workpiece (W) along a machining trajectory (X), an intentional manual or automatic change (ΔP ｉ，ｓｏｌｌ (x)) added to the machining parameters is automatically taken into account, whereupon a threshold value (Q ｉ (x), (Q ｋ，ｏ (x)) is replaced by a quality parameter threshold value (Q ｋ，ｕ (x), (Q ｉ (x)) adapted to the change (ΔP ｋ，ｏ (x), (Q ｋ，ｕ (x))) is determined, and at least one quality parameter (Q ｋ (x)) for evaluating the quality of the machining result (R(x)) of the machining operation along the machining trajectory (X) is compared with the adapted quality parameter threshold value (Q ｋ，ｏ (x), (Q ｋ，ｕ (x)). The machining result R(x) along the machining path (X) is measured using a non-destructive measurement method of the workpiece (W) or a measurement method that destroys the workpiece (W), and at least one sensor signal (S j (x)) is recorded. **Claim 2** The actual value (P ｉ／ｉｓｔ (x)) of the transmitted processing parameter and the target value (P ｉ／ｓｏｌｌ (x)) of the transmitted processing parameter are compared, and during the machining of the workpiece (W) along the machining locus (X), the change (ΔPi(x)) added to the processing parameter is determined from the target value. The method according to claim 1, characterized in that. **Claim 3** The target value of the machining parameter (P ｉ／ｓｏｌｌ (x)) and / or the actual value of the transmitted machining parameter (P ｉ／ｉｓｔ (x)) and / or the target value of the transmitted machining parameter (P ｉ／ｓｏｌｌ (x)), the change (ΔP ｉ (x)) added to the machining parameter is recorded during machining of the workpiece (W) along the machining trajectory (X) and subsequently used to be automatically considered in the quality evaluation of the machining operation along the machining trajectory (X). The method according to claim 1 or 2, characterized in that. **Claim 4** Change in processing parameters (ΔP ｉ (x))-adapted quality parameter threshold (Q' ｋ，ｏ (x), (Q' ｋ，ｕ (x)) is determined from the quality parameter threshold (Q ｉ (x)) stored for a specific processing parameter (P ｋ，ｏ，ｇ (x), (Q ｋ，ｕ，ｇ (x))), the method according to any one of claims 1 to 3, characterized in that. **Claim 5** The stored quality parameter threshold (Q ｋ，ｏ，ｇ (x), (Q ｋ，ｕ，ｇ (x)) is determined from a test processing operation for a specific processing parameter (P ｉ (x)), the method according to claim 4, characterized in that. **Claim 6** Change in processing parameter (ΔP ｉ (x))-adapted quality parameter threshold (Q' ｋ，ｏ (x), (Q' ｋ，ｕ (x)) is the stored quality parameter threshold (Q ｉ (x)) for a specific processing parameter (P ｋ，ｏ，ｇ (x), (Q ｋ，ｕ，ｇ (x)) obtained by interpolation of the method according to claim 4 or 5, characterized in that. **Claim 7** At least one quality parameter (Q ｊ (x)) is determined from at least one sensor signal (S ｋ (x)), wherein a change in at least one process parameter (ΔP ｉ (x)) is taken into account. The method according to any one of claims 1 to 6, characterized in that. **Claim 8** In the evaluation of the quality of a machining operation, additional environmental parameters (UP ｉ , UP ｉ (x)) such as, for example, workpiece temperature, ambient temperature, air humidity, etc. are taken into account, the method according to any one of claims 1 to 7. **Claim 9** The machining result R(x) along the machining path (X) is measured by an optical sensor (3), in particular a laser scanner, a camera (4), etc., an X-ray sensor (5), and / or a temperature sensor (6) as at least one sensor (2). The method according to any one of claims 1 to 8, characterized in that **Claim 10** The machining result R(x) along the machining path (X) is measured by making incisions in the workpiece (W) at various points along the machining path (X) and creating an image of the surface of the incision. The method according to any one of claims 1 to 9, characterized in that **Claim 11** The machining result R(x) is measured along the machining path (X) during the machining of the workpiece (W) using at least one sensor (2), and the measurement speed of the machining path (X) preferably corresponds to the machining speed. The method according to any one of claims 1 to 10, characterized in that **Claim 12** After the completion of the processing of the workpiece (W) using at least one sensor (2), the processing result R(x) is measured along the machining path (X), and the measurement speed of the machining path (X) is preferably greater than the processing speed. The method according to any one of claims 1 to 10, characterized in that **Claim 13** At least one quality parameter (Q ｋ (x)) exceeds the quality parameter threshold value (Q ｋ，ｏ (x), Q ｋ，ｕ (x)), or the applied quality parameter threshold value (Q' ｋ，ｏ (x), (Q' ｋ，ｕ (x)), a warning is output and / or the excess is stored, according to any one of claims 1 to 12. **Claim 14** In the case of a welding seam as a machining locus (X), the machining parameters (P ｉ (x)) include welding current (I(x)), welding voltage (U(x)), the conveying speed (v ｄ (x)) of the welding wire (7), the set angle (α(x)) of the welding torch (8) with respect to the workpiece (W), the relative position of the welding torch (8) with respect to the workpiece (W), and / or the welding speed (v ｓ (x)), characterized in that the method according to any one of claims 1 to 13 is considered. **Claim 15** An apparatus (1) for evaluating the quality of a machining operation of a workpiece (W) using specific machining parameters (P ｉ (x)) along a machining locus (X), the apparatus being designed to carry out the method according to any one of claims 1 to 14.

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