Method and apparatus for quality assessment of machining operations

Abstract

This invention relates to a method and apparatus for evaluating the quality of machining operations, wherein a specific machining parameter (P) is used along a machining trajectory (X). i (x)) Machining workpiece (W), wherein the 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) is recorded. j (x)), and based on at least one sensor signal (S) j (x) Determine at least one quality parameter (Q) k (x)), and at least one quality parameter (Q) k (x) and the quality parameter threshold (Q) k,o (x), Q k,u (x) is compared to evaluate the quality of the machining result (R(x)) of the machining operation. According to the invention, during the quality evaluation of the machining operation, the machining parameters are automatically considered from the target value (P) of the machining parameters during the machining of the workpiece (W) along the machining trajectory (X). i,soll The change (ΔP) made by (x) i (x)) replaces the quality parameter threshold (Q) k,o (x), Q k,u (x)), determined by changes in processing parameters (ΔP) i (x)) Adapted quality parameter threshold (Q') k,o (x), Q' k,u (x)), and at least one quality parameter (Q) will be used to evaluate the quality of the machining result (R(x)) of the machining operation along the machining trajectory (X). k (x) and the appropriate quality parameter threshold (Q') k,o (x), Q' k,u (x) is compared.

Description

Technical Field

[0001] The present invention relates to a method for evaluating the quality of a machining operation, wherein a workpiece is machined along a machining trajectory with specific machining parameters, the machining result of the machining operation is measured along the machining trajectory using at least one sensor and at least one sensor signal is recorded, at least one quality parameter is determined from the at least one sensor signal, and the at least one quality parameter is compared with a quality parameter threshold to evaluate the quality of the machining result of the machining operation along the machining trajectory.

[0002] Furthermore, the present invention relates to an apparatus for evaluating the quality of machining operations on a workpiece performed along a machining trajectory with specific machining parameters. Background Technology

[0003] Processing operations specifically include joining processes, such as welding or brazing, where workpieces are joined together or coated, but also surface treatment processes, such as plasma processing operations, where workpieces are processed with plasma to prepare them for subsequent processing operations. For example, the surface of a workpiece may be treated with plasma before painting to remove residues from the surface and / or improve the adhesion of the paint layer.

[0004] It is well known that monitoring or evaluating the quality of machining operations is necessary to remove defective workpieces or adjust machining parameters accordingly to improve quality. For this purpose, the machining trajectory is evaluated after the machining operation, and the quality of the machining operation is assessed from it. In the simplest case, quality assessment can be performed by a professional in the form of visual evaluation. However, typically, the machining results along the machining trajectory are automatically measured using appropriate sensors, and at least one quality parameter is determined from the sensor signals. To assess quality, at least one quality parameter is compared with a quality parameter threshold. For example, the weld seam, which is the machining trajectory of a welding process, can be measured after the welding process using a camera, preferably with illumination, and the weld seam width and height can be determined using appropriate image processing algorithms, thereby deriving the quality parameter. Depending on the machining or 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 may also be 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 therefore sufficient penetration depth may be more important. At least one quality parameter suitable for the corresponding machining operation is defined accordingly and then compared with specific quality parameter thresholds (e.g., upper and lower thresholds) to enable automatic quality evaluation. Quality parameters are typically determined by evaluating the workpiece optimally machined using an IO ("ordered") machining trajectory. In welding, for example, the size of the weld undercut, the so-called 'a' dimension, the weld height, and the end crater at the weld end can be used as quality parameters.

[0005] EP 3 566 806 A1 describes a welding process as a machining operation, wherein, in order to achieve specific quality standards, optimal welding parameters determined based on test welds on a test workpiece are automatically applied to the welding process. The optimal welding parameters for the corresponding welding task are determined by calculating the optimal value of a quality function from the corresponding optimal welding parameters of the test welds.

[0006] EP 1 642 366 B1 and WO 00 / 35622 A1 describe methods for monitoring the quality of a welding process, wherein information about the resulting weld is compared with predetermined values, and welding parameters are adjusted accordingly in case of deviation, or a warning is issued in case of large deviation. In this case, the processing parameters are adjusted to predetermined target values.

[0007] DE 10 2019 200 482 A1 describes a machining operation in which a workpiece is machined with predetermined machining parameters, and the machining parameters are adjusted accordingly in case of deviations in the machining results, so as to always achieve a machining result that remains as constant as possible.

[0008] A welding system is known from US 2009 / 0173726A1, which monitors the welding process with the aim of maintaining constant conditions and consistent quality of the finished product. Adapting quality assessment to intentional changes in machining parameters during workpiece processing is not discussed and is even undesirable.

[0009] In known quality assessment systems for machining operations, particularly welding processes, specific standards are checked to ensure they are within predetermined limits. For example, the resulting weld is compared to a previously defined "ideal weld," thereby assessing its quality. However, if machining parameters are intentionally changed manually or automatically during the machining operation, the quality standards are not automatically adjusted during quality assessment; instead, they must be manually adjusted, which is time-consuming. This can lead to an inadequate quality assessment of the machining operation because the intentional changes to machining parameters during the operation are not automatically considered. The quality of the machining operation can also be positively assessed, but the results may not meet the quality standards. For example, during welding, specific welding parameters may need adjustment due to workpiece tolerances. For instance, a large gap width due to workpiece or clamping device tolerances may require adjustment of wire feed and other welding parameters. Without automatic notification to the quality assessment system of changes in target values ​​for welding parameters, incorrect assessments of weld quality may occur. Summary of the Invention

[0010] The object of this invention is to provide the aforementioned method and apparatus for evaluating the quality of machining operations, which avoids the disadvantages associated with intentional changes to machining parameters during machining operations and enables reproducible descriptions of the quality of the machining operation and the workpiece. The automated quality evaluation system should also be usable even with intentional manual or automatic changes to machining parameters and capable of providing reliable descriptions of the quality of the machining operation or the workpiece.

[0011] The objective of the invention is achieved in terms of method by automatically considering changes in machining parameters from target values ​​during the machining of a workpiece along a machining trajectory in the quality assessment of a machining operation. This is done by determining a quality parameter threshold adapted to the changes in machining parameters, instead of a quality parameter threshold, and comparing at least one quality parameter with the adapted quality parameter threshold to assess the quality of the machining result of the machining operation along the machining trajectory. Therefore, the method according to the invention provides actual values ​​of machining parameters transmitted to the quality assessment system during the machining operation, thereby automatically considering intentional changes in the target values ​​of machining parameters by adapting the quality parameter thresholds accordingly to the changes in machining parameters when assessing the quality of the machining operation. As a result, the quality of the machined workpiece can be assessed more reliably, and, for example, unreasonable rejection of workpieces assessed as poor quality or of substandard quality can be prevented, even though they do not meet quality standards. Importantly, only intentional or deliberate changes in machining parameters are considered, not changes caused by disturbances. Due to the adaptive machining operation, manually made changes to the target values ​​of machining parameters or automatically made changes to the target values ​​of machining parameters are considered intentional changes. The target values ​​for machining parameters can be global parameters, such as the average welding current or average wire feed to be set, even if these parameters deviate from these settings during machining. Intentional changes to machining parameters from their target values ​​can be transmitted to the location for quality assessment, either standardly or only when necessary. The reliability of quality assessment can be improved by considering changes in machining parameters from their target values ​​and adapting quality parameter thresholds to these changes. The impact of changed machining parameters on quality parameters can vary significantly depending on the type of machining. The relationship between changes in machining parameters and changes in quality parameters used to evaluate the quality of machining operations or results can be determined based on test machining operations and stored in tables or functional relationships. Due to automatic consideration during quality assessment, it is possible to use the quality assessment system and provide reliable results even when machining parameters change due to general workpiece tolerances.

[0012] Changes to machining parameters can be determined from the target value by comparing the actual value of the transmitted machining parameters with the target value of the transmitted machining parameters during machining along the machining path. In this case, the target value represents the value before the change, and the actual value is the value after the change. In this so-called "online method," changes to machining parameters are determined and transmitted almost in real time, allowing for continuous quality monitoring of machining operations along the machining path using real-time data. Changes to machining parameters also include system-related changes that may occur, such as when replacing worn parts of the machining equipment. For example, the welding voltage will decrease after replacing the contact tube of a welding torch. If these intentional changes to machining parameters and related changes to quality parameter thresholds are also considered when evaluating the quality of the machining operation, a more reliable description of the quality of the machining operation or the workpiece machined during the machining operation is obtained.

[0013] Alternatively or additionally, changes in machining parameters from target values ​​and / or actual values ​​of transmitted machining parameters and / or target values ​​of transmitted machining parameters can be recorded during workpiece machining along the machining path, and can later be used for automatic consideration in the quality assessment of machining operations along the machining path. In this so-called "offline method," changes in machining parameters and quality parameter-related thresholds are recorded and stored for later use, allowing them to be taken into account during quality monitoring of the machining operation.

[0014] According to another feature of the invention, a quality parameter threshold adapted to changes in the processing parameters is determined from a stored quality parameter threshold for a specific processing parameter. If thresholds of the obtained quality parameters that can be used to evaluate processing results for a majority of different processing conditions and a majority of different processing parameters are stored, then the quality parameter threshold can be determined from these stored values ​​based on the corresponding actual processing parameters. The upper and lower quality parameter thresholds can be defined as quality parameter thresholds, or they can be defined as the average value of the quality parameters having a specific maximum range of fluctuation. The stored quality parameter thresholds can be stored in the same memory or database as the processing parameters, or in a different memory or database.

[0015] For example, stored quality parameter thresholds can be determined from testing processing operations or processing tests, such as test welding processes or welding tests for specific processing parameters and specific faults.

[0016] Preferably, the quality parameter threshold adapted to changes in processing parameters is determined by interpolation of stored quality parameter thresholds for specific processing parameters. This interpolation method allows for the rapid determination of appropriate quality parameter thresholds for a wide range of different processing parameters without significant computational overhead.

[0017] Preferably, when determining at least one quality parameter from at least one sensor signal used to measure the processing result, changes to at least one processing parameter are taken into account. For example, when determining the weld width as a quality parameter of the welding process, changes in the wire feed rate, which has a significant impact on the weld width, can be taken into account.

[0018] When evaluating the quality of a machining operation, additional environmental parameters, such as workpiece temperature, ambient temperature, and air humidity, can be considered. Including such environmental parameters, which may also depend on the machining trajectory, further improves the quality assessment results.

[0019] The machining results along the machining path can be measured using non-destructive measurement methods, such as optical sensors (especially laser scanners, cameras, etc.), X-ray sensors, and / or temperature sensors, which serve as at least one sensor, and the signal from at least one sensor can be recorded. The advantage of recording the machining results using non-destructive measurement methods and, preferably, non-contact sensors, is that the measurement can be performed particularly quickly and along the entire machining path without altering the workpiece. Under certain influencing factors, it may be advantageous to measure the machining results along the machining path immediately after machining the workpiece. For example, the temperature distribution in the workpiece material can provide information about the material structure of the machining results within and around the machining path immediately after machining. Using specific quality parameters, it may also be advantageous to measure the machining results along the machining path only at a certain time after machining the workpiece, since the quality of the machining operation can only be evaluated after that time.

[0020] Alternatively or additionally, destructive measurement methods that damage the workpiece can be used, such as by creating cuts through the workpiece at various points along the machining path and, in particular, by taking images of the cut surfaces using at least one sensor, to measure the machining results along the machining path, and at least one sensor signal can be recorded. For example, microsections can be created along the machining path at specific intervals of the machining results, and specific quality parameters can be derived from this. Naturally, more complex measurement methods of this kind also provide important insights into the internal structure of the machining results along the machining path, which cannot be detected or can only be "poorly" detected using non-contact measurement methods. The recorded microsections of the machining results along the machining path can be analyzed using various methods, especially with the aid of cameras and related image processing methods. The use of specific chemicals can improve the identification of the microstructure of the microsections of the machining results. Macroscopic inspection of the microsections after the machining operation can also provide characteristic quality parameters. The microsections are analyzed and identified and stored in the form of specific sensor signals and subsequent characteristic quality parameters of the machining results along the machining path. In addition to generating microsections, it is conceivable to perform tensile tests, bending tests, etc., on the workpiece.

[0021] According to another feature of the invention, during the machining of the workpiece, the machining result along the machining trajectory is measured by at least one sensor, the speed at which the machining trajectory is measured preferably corresponding to the machining speed. In this variant of the embodiment, the quality assessment of the machining operation or the measurement of the workpiece's machining trajectory is performed immediately after the workpiece machining or within a relatively short period of time after the workpiece machining. In this case, it is advantageous that the quality assessment system moves synchronously with the machining system relative to the workpiece. For example, a camera measuring the machining trajectory can be mounted on the same robotic arm that also carries the machining tool, and the machining trajectory can be analyzed after the workpiece is machined. In this case, the measurement of the machining result along the machining trajectory is performed at the same speed as the workpiece machining. Of course, the quality assessment system and the machining system can also be stationary and the workpiece can move during machining, or not only the quality assessment system and the machining system but also the workpiece can move relative to each other.

[0022] The machining results along the machining path can also be measured using at least one sensor after the workpiece machining is completed. The speed at which the machining results are measured along the machining path is preferably greater than the machining speed of the machining operation. If the measurement of the machining results along the machining path is performed independently of the workpiece machining, the measurement speed can also be chosen to be significantly higher than the machining speed. For example, optical scanning of the machining results along the machining path after the workpiece machining can be performed much faster than machining the workpiece itself. Furthermore, several measurements of the machining results along the machining path can be performed using different sensors, and quality parameters can then be determined from the signals from the different sensors. Moreover, workpieces from multiple machining stations can thus be evaluated using a single measuring station.

[0023] If at least one quality parameter exceeds a quality parameter threshold or an appropriate quality parameter threshold, a warning can be output and / or the exceedance can be stored. For example, the warning can be issued acoustically, optically, or mechanically via a vibration mechanism. In this way, the exceeded quality parameter can be indicated accordingly. The warning can also be forwarded to a higher-level location via a corresponding communication channel.

[0024] Warnings can be modified based on the degree to which at least one quality parameter exceeds a quality parameter threshold or an appropriate quality parameter threshold. For example, the volume of an acoustic warning or the light intensity or flashing frequency of an optical warning can be adapted to the magnitude of the quality deviation, and the warning can be used to notify personnel of the magnitude of the quality deviation.

[0025] When the weld seam is used as the machining trajectory, the machining parameters of the welding process are preferably considered: welding current, welding voltage, wire feed speed, angle of attack of the welding torch relative to the workpiece, relative position of the welding torch relative to the workpiece, and / or welding speed. Such welding processes also include brazing processes, where, unlike welding, the base material of the workpiece is not melted or only minimally melted.

[0026] Similarly, the objective of the invention is achieved by the aforementioned apparatus for evaluating the quality of a processing operation, the apparatus being configured to perform the aforementioned method. Regarding the advantages that can be achieved thereby, refer to the description of the method above. The apparatus for quality evaluation is characterized by a corresponding connection with the processing apparatus, through which changes in processing parameters during processing are transmitted to the apparatus for quality monitoring, such that the threshold values ​​of the quality parameters can automatically adapt to the changes in processing parameters. Attached Figure Description

[0027] The invention will be further explained with reference to the accompanying drawings. In the drawings:

[0028] Figure 1 A schematic machining operation is shown, in which a workpiece with specific machining parameters is machined along a machining trajectory;

[0029] Figures 2A to 2D This schematically illustrates a method for evaluating the quality of machining operations using various sensors that measure machining results along the machining trajectory;

[0030] Figure 3 A schematic diagram of a method for evaluating the quality of machining operations on a workpiece according to the present invention is shown; and

[0031] Figure 4 This is an example of the intentional alteration of processing parameters during processing operations and its consideration in the quality assessment of processing operations. Detailed Implementation

[0032] Figure 1 This illustrates a schematic machining operation, in which machining with specific machining parameters P is performed along a machining trajectory X. i The workpiece W is processed to form the machining result R(x). The machining device 10 includes a machining robot 11, which carries a corresponding machining head 12 for machining the workpiece W and is guided along the machining trajectory X to form the machining result R(x). In order to machine the workpiece W, multiple possible machining parameters P are selected from, for example, stored in a database or memory 9. i (x) Select a specific target value P for the processing parameters i，soll(x), the workpiece W is processed using the specific target value to achieve the desired processing result. Manual intervention of the processing device 10 or automatic mechanical intervention in adaptive processing operation (indicated by the dotted line) can result in the target value P of the processing parameters during the processing operation. i，soll The change in (x) and the resulting desired or necessary change in the processing parameters ΔP i (x). Under the condition of subsequent quality monitoring of the machining result R(x) by appropriately inspecting the workpiece W along the machining trajectory X, the machining parameters are adjusted from the target value P of the machining parameters. i，soll This change ΔP in (x) i (x) This is not typically considered automatically in known methods, which may lead to incorrect assessments of the quality of workpiece W. This is because conventional quality control systems intentionally alter the machining parameter ΔP. i The fact that the process fails at (x) means that since the altered processing result R′(x) does not correspond to the expected processing result R(x), it is usually necessary to intentionally change the processing parameter ΔP. i (x) Complex manual inspection of the workpiece W being processed.

[0033] For example, the processing apparatus 10 may be a welding apparatus for performing a joining process on workpieces W. In this case, a welding torch is fastened to a welding robot, by which two or more workpieces W are joined together, or a layer may be applied to workpieces W. In this case, the processing result R(x) is the weld between the two or more workpieces W to be joined or the weld bead on the surface of the workpieces W. Furthermore, the processing apparatus 10 may also be formed by a device for treating the surface of workpieces W with a plasma spray gun, a spraying device, and more. Depending on the processing operation, the processing result R(x) along the processing trajectory X varies, and the quality evaluation of the processing operation along the processing trajectory X and the corresponding processing result R(x) also varies.

[0034] Figures 2A to 2D A method for evaluating the quality of a machining operation using various sensors 2 is illustrated, the sensors being used to measure the corresponding machining result R(x) of the machining operation along the machining trajectory X based on the welding process as the machining operation.

[0035] Figure 2AThis illustrates a quality assessment (so-called "online" quality assessment) of a machining operation performed during or immediately after machining workpiece W. Accordingly, a sensor 2 for measuring the machining result R(x) of the machining operation is positioned at or after the machining head 12 along the machining trajectory X of workpiece W, allowing the machining result R(x) to be measured immediately after the machining operation along the machining trajectory X. For example, the machining head 12 can be a welding torch 8, through which a consumable welding wire 7 is fed to the workpiece W for performing a joining or surfacing process. An electric arc LB burns between the end of the welding wire 7 and the workpiece W, thereby melting both the welding wire 7 and the workpiece W. Possible sensors 2 for measuring the machining result R(x) along the machining trajectory X of workpiece W include, for example, an optical sensor 3, a camera 4, an X-ray sensor 5, or a temperature sensor 6, which measures the machining result R(x) along the machining trajectory X and provides a corresponding sensor signal S based on the point along the machining trajectory X. j (x). In "online" quality assessment, the speed of the machining result measured by sensor 2 along the machining trajectory X preferably corresponds to the speed of the machining operation, that is, the machining speed, such as the welding speed v in the welding process. s (x).

[0036] As an alternative to or supplement to "online" quality assessment, according to Figure 2B It can also perform "offline" quality assessment, in which, after the machining operation, the workpiece W or machining result R(x) is measured along the machining trajectory X using corresponding sensors 2, such as optical sensors 3, cameras 4, or X-ray sensors 5, and the corresponding sensor signals S are provided. j (x). In the case of "offline" quality assessment, the speed at which the machining result R(x) along the machining trajectory X is measured by sensor 2 after the machining of workpiece W is completed can be higher than the machining speed. However, unlike "online" quality assessment, "offline" quality assessment represents an additional time expenditure.

[0037] exist Figure 2C The paper describes a method for quality assessment of machining operations, in which workpiece W is destroyed along the machining trajectory X to analyze the machining result R(x). This is achieved by generating microscopic sections of workpiece W at multiple points along the machining trajectory X within the region of the machining result R(x). These microscopic sections can be measured using a corresponding sensor 2 and image processing methods, providing sensor signals S. j Similarly, it provides information about the quality of the machining operation on the workpiece W and the machining result R(x) at a specific point along the machining trajectory X. For example, during a welding process, such a microsection can provide an indication of the weld penetration depth as the machining result R(x).

[0038] like Figure 2DAs shown, various sensor signals s from the processing result R(x) j (x) Determine the mass parameter Q k Q(x) represents the quality of the processing result R(x) of the corresponding processing task. Depending on the processing task, different quality parameters Q can exist. k (x), which quantifies the quality of the processing result R(x) along the processing trajectory X. To evaluate the quality, at least one quality parameter Q is now used. k (x) and the quality parameter threshold, such as the upper quality parameter threshold Q. k，o (x) and the lower mass parameter threshold Q k，u (x) is compared. If it exceeds the quality parameter threshold Q, ... k，o (x), Q k，u If (x), then it is assumed that the quality is not met, which is marked with "NIO" (non-compliant). If all quality parameters Q k (x) at its quality parameter threshold Q k，o (x), Q k，u If (x) is within the range, the quality of the machining operation is considered to be met, and the workpiece W is classified as "IO" (qualified). If there is an intentional manual or automatic change ΔP in the machining parameters during the machining operation... i If (x) is changed, then the processing result R′(x) will change accordingly. If we now use sensor 2 to measure this changed processing result R′(x), and thus determine the quality parameter Q′ k (x) and then compare it with the original quality parameter threshold Q. k，o (x), Q k，u Comparing (x) with the actual machining result R′(x) typically produces incorrect quality descriptions. Therefore, the object of this invention is to automatically consider intentional changes ΔP in the machining parameters during the machining operation and in the evaluation of the quality of the changed machining result R′(x). i (x). This will preferably result in an adapted and altered quality parameter threshold Q′. k，o (x), Q′ k，u (x).

[0039] Figure 3 A schematic diagram of a method according to the present invention for evaluating the quality of a machining operation and machining result R(x) along a machining trajectory x on a workpiece W is shown. The device 1 for quality evaluation of the machining operation receives various sensor signals S. j (x), which during the machining operation, is measured by a sensor 2 mounted on the machining head 12 of the machining apparatus 10 along the machining trajectory X as a machining result R(x) ("online" quality assessment). Alternatively or additionally, after the machining operation, a sensor signal S is recorded by measuring the machining result R(x) along the machining trajectory X using a corresponding sensor 2. j(x) is provided to the device 1 for quality assessment. From at least one sensor signal S j (x) Determine at least one quality parameter Q k (x), and at least one quality parameter Q k (x) and the quality parameter threshold Q k，o (x), Q k，u (x) is compared to evaluate the quality of the machining operation and the machining result R(x) along the machining trajectory X. If it exceeds the quality parameter threshold Q... k，o (x), Q k，u (x), then it is assumed that the quality is not met and the workpiece is classified as "NIO" (non-conforming), which is indicated, for example, on display 13. If all quality parameters Q k (x) at its quality parameter threshold Q k，o (x), Q k，u If the quality of the workpiece W is within the range of (x), it is considered to meet the quality requirements of the processing operation and processing result R(x), and the workpiece W is classified as "IO" (qualified), which is indicated, for example, on the display 13. Additionally, if the quality parameter threshold Q is exceeded... k，o (x), Q k，u (x) can also output warnings, such as acoustic warnings on speaker 14.

[0040] According to the present invention, when evaluating the quality of the machining operation and the machining result R(x) along the machining trajectory X, the machining parameters are automatically considered from the target value P of the machining parameters during the machining of the workpiece W along the machining trajectory X. i，soll The change ΔP of (x) i (x), shown through the connection of the processing device 10 to the device 1 for quality assessment of the processing operation. This can be done, for example, by defining an appropriate quality parameter threshold Q′ based on the changing conditions. k，o (x), Q′ k，u (x), which is related to the change in processing parameters ΔP i (x) is stored or defined by corresponding calculation rules. The quality of the processing operation and the changed processing result R′(x) is therefore automatically evaluated based on an adapted quality parameter threshold Q′. k，o (x), Q′ k，u (x), thus improving the reliability of quality monitoring. Furthermore, this makes quality assessment suitable for adaptive machining systems. As a result, even with changes in machining parameters ΔP due to commonly occurring tolerances, the reliability of quality assessment is improved. i Workpiece W (x) processed with modified processing parameters and capable of providing other processing results R′(x) can also be determined as "IO" (qualified) by a quality assessment system, without the need for complex manual inspection. The appropriate quality parameter threshold Q′ k，o (x), Q′k，u (x) can be derived from P for a specific processing parameter. i The storage quality parameter threshold Q determined by the test processing operation of (x) k，o，g (x), Q k，u，g (x) For example, by storing the quality parameter threshold Q k，o，g (x), Q k，u，g The interpolation of (x) is determined.

[0041] Figure 4 This illustrates the intentional change ΔP of the machining parameters during the machining operation. i (x) and an example of its consideration in the quality assessment of machining operations using the welding process. In the left portion of the figure, the workpiece W is shown above in the cross-sectional view before machining and below after machining or after the welding process. This involves forming a lap weld on two lap-arranged workpieces W. The workpieces W are typically stacked one on top of the other 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 N are determined as quality parameters along the machining trajectory X, and are correlated with the width B of the weld N. o (x), B u (x) and height H o (x), H u The threshold of (x) is compared. If condition B is met... u (x) <B<B o (x) and H u (x) <H<H o If (x), the quality of the machining operation is evaluated as positive and the workpiece is classified as "IO".

[0042] In practice, tolerances are common; tolerances, for example, can cause a gap d between workpieces W, such as in... Figure 4 As shown in the right-hand section. During the welding process, these altered conditions are applied, for example, manually or automatically (in adaptive welding processes), by increasing the wire feed speed v. d (x) and welding current I(x) and reduce welding speed v s (x). This results in weld N having a higher weld quality than when the workpiece W is machined without gap d. Figure 4 The left portion of the weld N has a larger width B′ and a larger height H′. If a quality assessment is performed without automatically taking into account the changed conditions and intentional changes to the processing parameters, the width B′ and height H′ of weld N will be assessed as unacceptable and the quality of the processing operation will be negatively evaluated. The workpiece will be marked as scrap (“NIO”: non-conforming) or sent for manual inspection or reprocessing.

[0043] In the method for quality assessment according to the present invention, the change ΔP of the processing parameters is now taken into consideration. i (X), which is achieved by intentionally changing the processing parameters ΔP. i (x)(Here, for example, the transmission speed v) d The increase of welding current I(x) and welding speed vs(x) is known for quality assessment and is taken into account in the quality assessment. For example, based on the change of processing parameters ΔP i (x) Threshold Q′ of the adapted quality parameter k，o (x), Q′ k，u (x) is limited to evaluating the quality of the processing operation. In the example shown, the width B′ of weld N is... o (x), B′ u The upper and lower thresholds of (x) and the height H′ of weld N o (x), H′ u The upper and lower thresholds of (x) will be adapted to the changed welding parameters. As a result, in Figure 4 The altered processing result R′(x) or altered weld N′ in the right-hand portion is also correctly evaluated as positive in terms of quality because it satisfies condition B′. u (x) <B′<B′ o (x) and H′ u (x) <H′<H′ o (x). Due to the intentional changes in processing parameters ΔP automatically considered. i (x), therefore, in quality monitoring, workpiece W can also be correctly classified as "IO" in this case and manual inspection of workpiece W can be omitted.

[0044] Changes in processing parameters ΔP i In the case of (x), the fitting threshold Q′ of the quality parameter k，o (x), Q′ k，u (x) and normal processing parameters P i The mass parameter Q of (x) k,o (x), Q k,u The original threshold of (x) is either in a table or archived and stored according to specific rules. This is located in the quality parameter Q. k,o (x), Q k,u The processing parameter P between the stored value and the threshold of (x) i (x) can be determined by interpolation. The quality assessment system can access this data, regardless of where it is available or stored. This replaces the quality parameter Q. k，o (x), Q k，u The upper and lower thresholds of (x) can also be determined using the average quality parameter Q. k，m(x) and the range of maximum mass parameter fluctuation ΔQ around this average value. k To evaluate the quality of the processing result R(x).

Claims

1. A method for evaluating the quality of a machining operation, wherein a specific machining parameter (P) is used along a machining trajectory (X). i (x)) Machining workpiece (W), wherein the 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) is recorded. j (x)), and based on at least one sensor signal (S) j (x) Determine at least one quality parameter (Q) k (x)), and the at least one quality parameter (Q) k (x) and the quality parameter threshold (Q) k,o (x), Q k,u (x) is compared to evaluate the quality of the processing result (R(x)) of the processing operation, characterized in that, During the quality assessment of the machining operation, the machining parameters are automatically considered from the target value (P) of the machining parameters during the machining of the workpiece (W) along the machining trajectory (X). i,soll (x) Intentional manual or automatic changes (ΔP) i (x) replaces the quality parameter threshold (Q). k,o (x), Q k,u (x)) determines the change in the processing parameters (ΔP) i (x)) Adapted quality parameter threshold (Q') k,o (x), Q' k,u (x)), and at least one quality parameter (Q) used to evaluate the quality of the machining result (R(x)) of the machining operation along the machining trajectory (X). k (x) and the adapted quality parameter threshold (Q') k,o (x), Q' k,u (x) is compared.

2. The method according to claim 1, characterized in that, During the machining of the workpiece (W) along the machining trajectory (X), the actual values ​​(P) of the transmitted machining parameters are passed through... i / ist (x) and the target value of the transmitted processing parameters (P) i / soll (x) is compared to determine the change (ΔP) in the processing parameters from the target value. i (x)).

3. The method according to claim 1 or 2, characterized in that, During machining of the workpiece (W) along the machining trajectory (X), machining parameters are recorded from the target value (P) of the machining parameters. i / soll (x)) and / or the actual value of the transmitted processing parameters (P) i / ist (x)) and / or the target value of the transmitted processing parameters (P) i / soll The change (ΔP) made by (x) i (x)), and is subsequently used automatically in the evaluation of the quality of the machining operation along the machining trajectory (X).

4. The method according to claim 1, characterized in that, From the specific processing parameters (P) i The storage quality parameter threshold (Q) of (x) k,o,g (x), Q k,u,g (x) determines the change in the processing parameters (ΔP) i (x)) Adapted quality parameter threshold (Q') k,o (x), Q' k,u (x)).

5. The method according to claim 4, characterized in that, From the specific processing parameters (P) i The test processing operation (x) determines the storage quality parameter threshold (Q). k,o,g (x), Q k,u,g (x)).

6. The method according to claim 4 or 5, characterized in that, By using specific processing parameters (P) i The storage quality parameter threshold (Q) of (x) k,o,g (x), Q k,u,g The interpolation of (x) is used to determine the relationship with the change in the processing parameters (ΔP). i (x)) Adapted quality parameter threshold (Q') k,o (x), Q' k,u (x)).

7. The method according to claim 1, characterized in that, From at least one sensor signal (S) j (x) Determine at least one quality parameter (Q) k When considering (x)), take into account the change of at least one processing parameter (ΔP). i (x)).

8. The method according to claim 1, characterized in that, Additional environmental parameters (UPs) should be considered in the quality assessment of processing operations. i UP i (x)).

9. The method according to claim 1, characterized in that, The machining result R(x) along the machining trajectory (X) can be measured using a non-destructive measurement method on the workpiece (W), and at least one sensor signal (S) can be recorded. j (x)).

10. The method according to claim 1, characterized in that, The machining result R(x) along the machining trajectory (X) is measured by means of a measurement method that destroys the workpiece (W), and at least one sensor signal (S) is recorded. j (x)).

11. The method according to claim 1, characterized in that, During the machining of the workpiece (W), at least one sensor (2) is used to measure the machining result R(x) along the machining trajectory (X).

12. The method according to claim 1, characterized in that, After the workpiece (W) is machined, the machining result R(x) along the machining trajectory (X) is measured by the at least one sensor (2).

13. The method according to claim 1, characterized in that, If at least one quality parameter (Q) k (x) exceeds the quality parameter threshold (Q) k,o (x), Q k,u (x) or the appropriate quality parameter threshold (Q') k,o (x), Q' k,u If (x) is exceeded, a warning and / or storage will be output.

14. The method according to claim 1, characterized in that, When the weld is taken as the machining trajectory (X), the machining parameters (P) of the welding process are considered. i (x): Welding current (I(x)), welding voltage (U(x)), and wire (7) feed speed (v) d (x)), the mounting angle (α(x)) of the welding torch (8) relative to the workpiece (W), the relative position of the welding torch (8) relative to the workpiece (W), and / or the welding speed (v). s (x)).

15. The method according to claim 8, characterized in that, In the quality assessment of machining operations, workpiece temperature, ambient temperature, or air humidity are considered as additional environmental parameters (UP). i UP i (x)).

16. The method according to claim 9, characterized in that, The non-destructive measurement method includes using an optical sensor (3), an X-ray sensor (5), or a temperature sensor (6) as at least one of the sensors (2).

17. The method according to claim 16, characterized in that, The optical sensor (3) includes a laser scanner or a camera (4).

18. The method according to claim 10, characterized in that, The method for measuring damage to the workpiece (W) includes making cuts through the workpiece (W) at various points along the machining trajectory (X) and taking images of the surface of the cuts using at least one sensor (2).

19. The method according to claim 11, characterized in that, The measured speed of the machining trajectory (X) corresponds to the machining speed.

20. The method according to claim 12, characterized in that, The measured speed of the machining trajectory (X) is greater than the machining speed.

21. A method for evaluating machining along a machining trajectory (X) with specific machining parameters (P) i (x)) is a device (1) for improving the quality of the machining operation of the workpiece (W) and is designed to perform the method according to any one of claims 1 to 20.

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