METHOD OF MONITORING MACHINE PROCESSES IN WORKPLACE PROCESSING

Abstract

A method for monitoring machining processes in workpiece processing including steps of planning a processing process on the basis of a predetermined final shape of a workpiece to be achieved in the processing process and of quality features of the final shape of the workpiece and simulating the planned processing process in a computer-aided simulation. Target values of parameters of the simulated processing process occurring during the simulated processing process are detected and stored in the context of the computer-aided simulation. During the real processing process carried out according to the planned and simulated processing process, the parameters considered in the simulation are monitored and the actual values thereof are detected. By comparing actual values of parameters detected during the real processing process with the target values of these parameters detected during the simulation, the quality of the processing process and/or of the processed workpiece is assessed.

Claims

1. A method for monitoring machining processes in workpiece processing, comprising steps of: a. planning a processing process on the basis of a predetermined final shape of a workpiece to be achieved in the processing process and of quality features of a final shape of the workpiece to be obtained; b. simulating the planned processing process in a simulation carried out in a computer-aided manner; c. detecting and storing target values of parameters of the simulated processing process occurring during the simulated processing process in a context of the computer-aided simulation; d. during the real processing process carried out according to the planned and simulated processing process, monitoring the parameters considered in the simulation and detecting the actual values thereof; and e. assessing the quality of the processing process or the processed workpiece by comparing the actual values of the parameters detected during the real processing process with the target values of these parameters detected during the simulation.

2. The method according to claim 1, wherein compliance of the processed workpiece with quality specifications is determined in the case of correspondence, within a tolerance range, of the actual values of the parameters determined during the real processing process with the target values of the parameters determined during the simulation.

3. The method according to claim 1, wherein as parameters of the processing process: forces or bending moments occurring on a processing tool acting on the workpiece during the processing process, or torques or power consumption of axis or spindle motors of a machine tool executing the processing process; or accelerations or vibrations or generated structure-borne sound, are observed and the target values thereof in the simulation and the actual values during the real processing process of step d are detected and compared in step e.

4. The method according to claim 1, wherein the detection of the target values of the parameters in the simulation of step c and the detection of the actual values of the parameters during the real processing process of step d are resolved according to location and/or time.

5. The method according to claim 1, wherein the comparison in step e is carried out in a computer-aided manner and in real time.

6. The method according to claim 5, wherein, in the case of a determined deviation, exceeding a tolerance threshold, of the actual values of at least one of the parameters from the target values of the at least one parameter, the processing process is paused or stopped.

7. The method according to claim 1, wherein the actual values of the parameters detected in step d during the real processing process are stored together with the target values of the parameters detected in step c during the simulation in a processing protocol assigned to the workpiece processed in the real processing process.

8. The method according to claim 6, wherein the processing process is paused or stopped after completion of a currently executed partial processing step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the following, a procedure according to the method according to the invention is explained once again in the context of a possible embodiment described on the basis of the accompanying figures. In the drawings:

[0027] FIG. 1 schematically shows a sequence of the method with the simulation, the recording of the parameters during the simulation, a definition of a tolerance range and the subsequent measurement of the parameters in the real process with associated evaluation in comparison with the parameters detected in the simulation; and

[0028] FIG. 2, in representations a to c, illustrates examples of a real profiles of a parameter deviating from the specification as an indicator of a process profile not corresponding to the specifications.

DETAILED DESCRIPTION

[0029] FIG. 1 schematically shows as an example a sequence for a method according to the invention for monitoring machining processes in workpiece processing on the basis of a possible design variant. A solid arrow in the upper part of the figure symbolizes a timeline and indicates that the steps denoted by Ito IV, described in more detail below, lie in temporal succession in a manner explained in more detail below.

[0030] A processing process, which has been planned beforehand on the basis of a predetermined final shape of a workpiece to be achieved in the processing process and of quality features of the final shape of the workpiece to be obtained, is simulated in a computer-assisted manner in the portion denoted by I. In this case, path movements are calculated which are carried out by a tool relative to the workpiece, and which are obtained in practice by a movement of the workpiece and/or of the tool. Furthermore, during the simulation, the material removal is calculated, which, starting from a blank form of the workpiece, takes place along the respective traversed paths in a manner resolved according to location and time. From the data calculated in this way, it is then possible, on the basis of the movement coordinates of the tool relative to the workpiece and the thickness of the material to be respectively removed along the path, to determine value profiles of predeterminable parameters as target values, taking into account the material properties, which values can then be recognized as theoretical signal profiles of sensors which detect the values of the parameters. This can be, for example, a signal profile for a bending moment acting on the tool or a tool holder. However, other parameters are also conceivable, such as forces or moments applied to the tool or also torque or power consumption of spindle motors for tool drives and/or workpiece drives or the like, the signal profiles of which are simulated.

[0031] FIG. 1 shows by way of example a profile of the simulated value of a parameter, plotted over time, for example, in a dashed line in the window provided with the reference sign 1. Instead of plotting over time, plotting depending on the location can also be provided here, for example. A resolution of data according to location and time is equally conceivable.

[0032] In a following step, denoted by II in FIG. 1, a tolerance band is defined here within the scope of a calculation, in this exemplary embodiment by a percentage deviation of ±XY %, wherein XY indicates a value which is suitable for the process and which is determined by the person skilled in the art on the basis of their experience, possibly based on simple experiments. Accordingly, in the representation in the window provided with reference sign 2, two dashed lines can be seen, of which a lower line indicates the profile of a lower limit value of the tolerance window, and an upper line indicates the profile of an upper value of the tolerance window. This simulation and calculation can, in particular, also be defined once for performing a large number of processing processes to be carried out, for example in batch production. However, these steps can also be carried out for a single subsequent individual processing process.

[0033] Furthermore, FIG. 1 shows the already mentioned processing process, which is referred to here as a real process and which takes place in the portion designated by III. In the context of this process, the profile of the parameter which was previously determined in the simulation as a simulated parameter for the comparison is detected as an actual value.

[0034] In the context of an evaluation, which is illustrated in the sequence shown in FIG. 1 at IV, the profile of the actual value of the parameter detected by means of sensors in the real processing process is compared with the possible profile of the target value determined by specifying the tolerance band. This evaluation can take place downstream of the processing process, i.e., in a temporally decoupled manner. However, it can also be carried out in situ while the processing process is being carried out. FIG. 1 shows, in the window designated by 3, a result in which the profile of the actual value of parameter shown in a solid line and determined by means of the suitable sensors lies within the tolerance band determined by the two dashed lines, previously determined in the step described under II, so that the real process carried out is evaluated as “good” and corresponding to expectations or specifications. The data or profiles as shown in window 3 can in particular be stored and associated with and assigned to the processed workpiece as a processing protocol.

[0035] FIG. 2 shows, in three different representations a, b and c, the profiles of the actual value (in each case in a solid line) determined by sensors with respect to the tolerance band previously determined under step II (the two dashed-line profiles), in which the profile of the actual value of the parameter lies at least partially outside the specified tolerance band, so that the process carried out in each case is evaluated as not complying with the specifications and thus as “poor.” If such a determination occurs in the context of the evaluation, the current process can in particular be paused in order to determine a cause for the deviation from the values predetermined by the simulation and to readjust the process or the processing machine in order to again obtain an evaluation which corresponds to the specifications and is recognized in the result of the evaluation as in FIG. 1 in the window designated by 3, and thereby to obtain a processing of the workpiece in the machining process qualitatively corresponding to the specifications.

[0036] It is again illustrated by the above description that the method according to the invention can be used to carry out monitoring of a machining process that can dispense with an analysis of the finished workpiece, for example in the context of a complex measurement, in that it only performs a comparison of simulation data for the determined parameter, in the form of target values, with the actual values determined during the real processing for these parameters, and identifies and confirms the consistent quality of the processing in the event of correspondence within a tolerance range, while, on the other hand, identifying an error and a possible quality deficiency in the case of a deviation.

[0037] The above description of the exemplary embodiment shown is again used to illustrate and explain the invention and its advantages, without describing all possible embodiments of the invention, as defined in the following claims, for example.