METHOD FOR ERROR DETECTION AND INSTALLATION FOR MACHINING A WORKPIECE

Abstract

Method for error detection and for local limitation of a cause of the error in an installation for machining a workpiece which is preferably formed at least in sections from wood, a wood material, and/or a synthetic material, the installation having several segments, comprising the steps: Detecting a workpiece parameter in at least two segments of the installation; determining whether there is an error on the basis of the detected workpiece parameter; if there is an error, identifying in which of the at least two segments of the installation the error is present for local limitation of the cause of the error; and outputting a signal containing the information regarding which segment the error is in.

Claims

1. A method for error detection and for local limitation of a cause of the error in an installation for machining a workpiece, the installation having several segments, comprising the steps: detecting a workpiece parameter in at least two segments of the installation; determining, on the basis of the detected workpiece parameter, whether there is an error with respect to the installation; if there is an error, identifying which of the at least two segments of the installation the error is in, for local limitation of the cause of the error; and outputting a signal that contains information regarding which segment the error is in.

2. The method of claim 1, wherein the workpiece is formed at least in sections from wood, a wood material, and/or a synthetic material.

3. The method of claim 1, wherein the determining whether there is an error comprises determining whether a future performance loss of the installation is to be expected, and wherein it is determined that there is an error if a future performance loss is expected.

4. The method according to claim 1, wherein the performance loss is defined as a falling beneath a predetermined threshold value of a quantity of workpieces processed by the installation during a predetermined time unit or as another parameter quantifying the performance of the installation.

5. The method according to claim 1, wherein the presence of an error is determined before the performance loss actually occurs.

6. The method according to claim 1, wherein the error is determined on the basis of a temporal development of a plurality of detected status information.

7. The method according to claim 1, wherein the installation has two or more aggregates for machining or inspecting workpieces and at least two aggregates are assigned to different segments.

8. The method according to claim 7, wherein the identification includes that the error is assigned to a specific aggregate or a specific part of the installation between two aggregates, and the output signal contains the information regarding which aggregate or which part of the installation between two aggregates is faulty.

9. The method according to claim 1, wherein at least one of the detected workpiece parameters is a distance from a sensor to a workpiece and/or a thickness, height, length, or width of the workpiece.

10. The method according to claim 1, wherein it is checked whether a workpiece has an undesired bend by measuring distances from one sensor or several sensors to at least two different positions of the workpiece, and for each of the measured distances it is determined whether the respective distance is below or above a lower or upper threshold value, or it is determined whether the sum of the distances or a different parameter which is a function of the distances is below or above a lower or upper threshold value.

11. The method according to claim 1, wherein it is checked whether the detected workpiece parameter or a parameter which is a function of the detected workpiece parameter or the detected workpiece parameters is within a predetermined tolerance range.

12. The method according to claim 1, wherein it is counted how often the same error occurs and it is determined whether the number of the same error exceeds a predetermined threshold value, and an error message is output if the threshold value is exceeded.

13. The method according to claim 1, wherein an error is recognized from a tendency of detected values of a workpiece parameter or from tendencies of a plurality of detected workpiece parameters.

14. The method according to claim 1, wherein at least one detected workpiece parameter is a number of conveyed workpieces, scraper blade swarf, loose edge band, cover layer projection, a cupping, a groove, a bore, a surface feature.

15. The use of the method according to claim 1 in an edging installation for machining an edge of a workpiece and/or for applying an edge element to a workpiece.

16. The use according to claim 15, wherein a diagonal of a surface of a workpiece is calculated or measured, and a tolerance value is set to a value in the range of 0.1% to 1% of the diagonal, and it being checked whether a thickness and/or a flatness of at least one part of a workpiece no longer deviates from a predetermined target value than by the tolerance value.

17. The use according to claim 16, wherein the diagonal is a largest diagonal of the largest surface of the workpiece, and wherein the tolerance value is set to a value between 300 m and 2.5 mm.

18. A data carrier upon which a program is stored which is suited to be executed on a data processing system which can be operated together with an installation for machining a workpiece, so that the method is carried out according to claim 1.

19. Sensor equipment set for equipping an installation for machining a workpiece, with a sensor system for setting up the installation to perform a method for detecting an error and for local limitation of an error, the sensor system having a plurality of sensors suitable for the detection of a workpiece parameter, the sensor equipment set having a data carrier according to claim 18.

20. The sensor equipment set according to claim 19 comprising at least one sensor unit having at least one of the sensors, the sensor unit being configured to transmit a signal to a receiver via a cable connection or wirelessly.

21. An installation for machining a workpiece, the installation having several segments and each segment having at least one sensor for detecting a workpiece parameter characterized in that the installation further has a controller which is configured to carry out the method according to claim 1.

22. The installation according to claim 21 which is provided with a sensor equipment set for equipping an installation for machining a workpiece formed at least in sections from wood, a wood material, and/or a synthetic material, with a sensor system for setting up the installation to perform a method for detecting an error and for local limitation of an error, the sensor system having a plurality of sensors suitable for the detection of a workpiece parameter.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0036] In the following, preferred embodiments of the present invention will be described with reference to the figures.

[0037] FIG. 1 is a schematic view of an installation for machining a workpiece.

[0038] FIG. 1 is a schematic view of an installation 100 for machining a workpiece w that is formed at least in sections from wood or a wood material. Specifically, the shown installation 100 is an edging installation for applying solid wood edges or paper edges to wooden workpieces or wood material workpieces.

[0039] To perform a method for detecting an error and for local limitation of a cause of the error in the installation 100, the installation 100 is divided into segments. In some embodiments, the total number of segments is two, in other embodiments, the number is higher, sometimes even significantly higher. The installation of FIG. 1, for example, is divided into eight segments, S1 to S8.

[0040] The installation 100 furthermore has four machining aggregates 1, 2, 3, 4, for machining. Other embodiments can have a diverging number of machining aggregates. Moreover, installations in which the method is performed can also have inspection aggregates and/or aggregates which carry out one or more machining functions and/or inspection functions. One example for an aggregate is an edge coating aggregate that applies an edge to a wood workpiece, for example, when manufacturing a table. Other examples are a sawing aggregate, a drilling aggregate, a milling aggregate, a gluing aggregate and/or a welding aggregate.

[0041] In the case of FIG. 1, all aggregates 1 to 4 are assigned to different segments, namely segments S2, S4, S5 and S7. In other embodiments, a segment can also have two or more aggregates.

[0042] The first segment S1 has a conveyor belt section 10 which leads to the first machining aggregate 1. The second segment S2 has the first machining aggregate 1. The third segment S3 has a further conveyor belt section 20 which leads from the first machining aggregate 1 to the second machining aggregate 2. The fourth segment S4 has the second machining aggregate 2 as well a further conveyor belt section 30 which leads from the second machining aggregate 2 to the third machining aggregate 3. In other embodiments, the installation is, on the other hand, more finely divided such that each aggregate is assigned to its own segment. In other embodiments, several belt sections and/or one or more aggregates are, in turn, assigned to the same segment.

[0043] The fifth segment S5 has the third machining aggregate 3. The sixth segment S6 has a further conveyor belt section that leads from the third machining aggregate 3 to the fourth machining aggregate 4. The seventh segment S7 has the fourth machining aggregate 4. The eighth segment S8 lastly has a conveyor belt section 50 which leads downstream from the fourth machining aggregate 4 with respect to workpiece throughflow direction.

[0044] A high throughflow of workpieces takes place in the installation 100. In this embodiment, between 10000 and 12000 machined workpieces are transported per day on the belt section 50 during normal operation of the installation 100.

[0045] The installation 100 also further has a controller 101 which controls an operation of the installation 100. Among other things, this embodiment includes regulations of aggregates and conveyor belt sections. The controller 101 communicates wirelessly with aggregates and collects, for example, data information from sensors that are arranged in the aggregates.

[0046] Moreover, the installation 100 is equipped with special sensors which serve to perform the error detection method. For this, the installation was equipped with a sensor retrofitting set (not shown separately) which has sensors that are each suited to detecting a workpiece parameter or a plurality of workpiece parameters, as well as a data carrier (not shown) upon which a program is stored which is suited to be performed with the controller 101 so that the controller 101 together with the other components of the installation 100 can carry out the error detection method.

[0047] For this, sensors 11 are arranged above and below the conveyor belt section 10 in the first segment S1. In this embodiment, the sensors 11 each serve to detect a first distance d1 to the workpiece (from above the workpiece) and to detect a second distance d2 from the workpiece (from below the workpiece).

[0048] Furthermore, a sensor 12 is arranged in the first aggregate 1 (i.e. in the second segment S2). A sensor 21 is arranged at the belt section 20 in the third segment S3. A further sensor 22 is arranged at the belt section 30 in the fourth segment S4, directly downstream from the second aggregate 2. The fifth segment S5 has further sensors 31 and 32 in the third aggregate 3. Sensors 41 are also arranged above and below the conveyor belt section 40 in the sixth segment S6. The seventh segment S7 has a sensor 42 in the fourth aggregate 4, and a sensor 51 is also arranged in the eight segment S8 at the belt section 50.

[0049] All of the aforementioned additional sensors 11, 12, 21, 22, 31, 32, 41, 42 and 51 (additional to those sensors already in a conventional installation which are not formed to perform the error detection according to this disclosure) are suited to detecting a workpiece parameter. The workpiece parameter to be detected is thereby not the same for all of the sensors mentioned.

[0050] For example, the sensor 12 is formed to detect scraper blade swarf. For example, the sensor 51 detects a loose edge band. For example, the sensor 42 is formed to detect a reflectance of the workpiece. The sensor 32 is formed to detect a bore, and the sensor 31 is formed to detect a cupping (irregularity). Furthermore, the sensor 22 is formed to detect a groove, and the sensor 21 is formed to detect a cover layer projection.

[0051] The sensors 11 are suited to detecting a distance d1 from a sensor above the workpiece w to the workpiece and a distance d2 from a sensor below the workpiece w to the workpiece. The sensors 42 are also suitable for detecting a distance d1 from the sensor above the workpiece w to the workpiece and a distance d2 from the sensor below the workpiece w to the workpiece. Both the two (of the upper and the lower) sensors 11, as well as the two (of the upper and the lower) sensors 41 are formed as laser sensors.

[0052] In this embodiment, the upper sensors 11 and 41 each has a range of up to approximately 130 mm, and the lower sensors 11 and 41 each have a range of up to approximately 60 mm.

[0053] More generally, in these embodiments of an installation 100, the described sensors 11, 12, 21, 22, 31, 32, 41, 42 and 51 are each connected with corresponding units that are configured to transmit data via a wireless communication to the controller 101 which receives and continuously processes this data. In other embodiments, the communication is implemented via a cable connection. The controller 101 has a receiver which is suited to receive the wirelessly transmitted data.

[0054] The installation 100, and in particular the controller 101, are configured to perform a method for the detection of an error in the installation 100 and the local limitation of a cause of the error.

[0055] The method comprises the respective detection of the above-described workpiece parameters, with each of the sensors 11, 12, 21, 22, 31, 32, 41, 42 and 51 in the segments S1 to S8 of the installation 100.

[0056] The respective status information is transmitted to the controller 101, and in this embodiment, for each of the transmitted values of the respective status information it compares whether the value is beneath a lower threshold value or if it exceeds an upper threshold value.

[0057] Moreover, in this embodiment, a series of calculations are carried out on the basis of the distance values transmitted by the sensors 11 and 41. The distance between the respective upper sensor and the respective lower sensor is thereby known (or can be determined by a measurement). The distance between the two sensors 11 is called dsum, and the distance between the two sensors 11 is called dsum.

[0058] Moreover, in this embodiment, also the length l and the width b of a workpiece is known (these are both significantly larger than the thickness d of the workpieces processed in the installation 100), and a diagonal of a side surface is calculated from these: =l.sup.2+b.sup.2. In function of this diagonal, a dimension is defined for the tolerance as =0.2%.Math.. Moreover, according to preferred embodiments, the tolerance is set in a range between 394 m and 2 mm. If the above calculation establishes a smaller or a larger value, is set to 394 m or 2 mm. These values are particularly suited to wood processing.

[0059] In each case the controller calculates as a method step the thickness d or d of a workpiece, as well as for the position of the sensors 11 as well as for the position of the sensors 41, as follows: d=dsum(d1+d2) for the position of the sensors 11; and then d=dsum(d1+d2) for the position of the sensors 41. Then it is determined in each case whether the thickness deviates by more than the tolerance value of a predetermined target thickness dsoll, i.e. it is checked whether ddsoll>, and whether ddsoll>. If one these inequalities is fulfilled, it is determined at the respective position of the sensors in the installation that the workpiece passing by is too thick. Furthermore, in this embodiment, it is checked whether the inequality dsolld>, and whether dsolld> is fulfilled. If one of these inequalities is fulfilled, the corresponding workpiece is too thin at the respective location in the installation. In the method according to the described embodiment, the corresponding workpiece is also automatically marked as faulty once it has been determined that it is too thin or too thick. For this, a corresponding marking element is provided which is controlled via a control process. In addition or alternatively, an error message can be output. In some embodiments, an error message is only then issued if a critical threshold percentage of faulty workpieces has been detected.

[0060] In this embodiment, the respective target values for the upper distance d1Soll and the lower distance d2Soll are also specified. It is then checked in each case whether the inequality d1Solld1> and/or whether d1Solld1> is fulfilled. If yes, the affected workpiece bends upwards (i.e. there is cupping). Furthermore, it is checked whether the inequality d1d1Soll> or d1d1Soll> is fulfilled. If yes, the affected workpiece bends downwards (i.e. there is cupping). It is also monitored whether the inequality d2Solld2> or d2Solld2> is fulfilled. If yes, the affected workpiece bends downwards (cupping). Furthermore, it is checked whether the inequality d2d2Soll> or d2d2Soll> is fulfilled. If yes, the affected workpiece bends upwards (cupping). If none of the inequalities is fulfilled, the workpiece (at least with respect to the absence of bending deformation) is to be categorized as acceptable.

[0061] Furthermore, it is also determined by means of the sensors 11 and 41 whether a workpiece is present between the respective upper and lower sensors. The presence of a workpiece is then concluded if the sum of the measured distances of the sensors is equal to or greater than the distance between the sensors.

[0062] The aforementioned errors are monitored by the controller 101, in particular, whether workpieces are too thin, too thick, bend downwards or upwards. A signal is thereby output with an error message if a predetermined threshold value is exceededfor example, if an error is detected more often than a predetermined number of times in a day, or if a deviation from the tolerance value deviates by more than one threshold value. In the present embodiment, threshold values can be configured or changed by a user.

[0063] Furthermore, in this embodiment the controller 101 is configured to calculate trends. For example, it is therefore monitored whether an error rate increases. If the rate of workpieces that are too thin, too thick, bending upwards or bending downwards, for example, has increased by more than a predetermined threshold value, an error message is output. In this manner, an actual performance loss of the installation 100 (for example, a lower quantity of acceptable workpieces processed per day) can be prevented since gradual performance losses and/or tendencies can already be detected. Consequently, a part of the installation can be examined and/or maintained in time, for example, during a regular maintenance and/or downtime of the installation 100.

[0064] In more general terms, the controller determines whether there is an error depending on the detected and transmitted workpiece parameter data. An error is thereby not concluded alone from the presence of a deviation of a value from a target range, but rather threshold value can be set. For example, it can therefore be determined that an error is present at sensor 41, if during a longer time period, a too high percentage of workpieces with workpiece parameters deviating from target ranges has been detected.

[0065] In other words, the method comprises determining that there is an error, based on the workpiece parameters. The method also comprises, if there is an error, identifying in which of the at least two segments of the installation the error is, for local limitation of the cause of the error. This is carried out with this embodiment of the controller 101.

[0066] In the embodiment of FIG. 1, for example, a limitation of the cause of the error is carried out from the information at which sensor unusual values for the workpiece parameter have been determined. For example, in some embodiments, the fact that a sensor in segment S delivers different values leads to the conclusion that the error is in segment S. On the other hand, in other embodiments, and therefore also in the embodiment of FIG. 1, an error owing to a sensor in one segment can indicate the error source in a different installation segment. An example is the detection of a workpiece which bends downwards or upwards with the sensors 41 in segment S6. If it is simultaneously determined that in segments S1 to S4 there are normal (i.e. within corresponding target ranges) workpiece parameter values, the cause of the error is limited to segment S5, in this embodiment.

[0067] Furthermore, the method comprises outputting a signal that contains the information regarding which segment the error is (most likely) in. In the present embodiment, the signal is output by the controller 101 and displayed to the operating personnel of the system, for example, on a screen of a data processing system. In other embodiments, acoustic signals are output, for example, at certain positions in the installation. Alternatively or additionally, optical warnings can also be output. Thus, for example, a light can show that an error source is suspected in the third segment, etc.

[0068] In the method carried out in the installation according to the embodiment of FIG. 1, the identifying includes that the error is assigned to one specific aggregate or one specific part of the installation between two aggregates (in this case: a conveyor belt section), and the signal output from the controller 101 contains the information regarding which aggregate or which part of the installation between two aggregates is faulty.

[0069] In other words, in this embodiment, the error is assigned to one of the belt sections 10, 20, 30, 40, 50, or one of the aggregates 1, 2, 3, or 4. However, in other embodiments the local resolution of the error limitation is higher (thus, for example, an error can be assigned to one specific part of the aggregate or of a conveyor belt section) or alternatively, less precisely (thus, for example, an error is assigned to the part of the installation upstream from a specific point, etc.). The resolution of the error source allocation can also vary, depending on which type of error has been detected.

[0070] The invention also covers numerous modifications and modified embodiments.