Tool life determination device

Abstract

Tool life determination device (1), comprising: a test workpiece carrier (2) capable of supporting a test workpiece (T); a load sensor (3) arranged between the test workpiece carrier (2) and a lower part (101, 200) of a machine tool (100, 200) capable of detecting a load acting on the test workpiece (T) when the test workpiece (Z) is machined using a cutting tool (102) of the machine tool (100, 200); a storage unit (4) that stores a load pattern acting on the test workpiece (T) and detected by the load sensor (3);and a determination unit (5) that determines a wear state of the cutting tool (102) or a probability that the cutting tool (102) may break by obtaining a wear reference value and a breakage reference value based on the load pattern stored in the storage unit (4) with the load and comparing the wear reference value and the breakage reference value with the load acting on the test workpiece (T) and being detected by the load sensor (3) at a suitable time during an actual work operation performed on a workpiece (W); wherein the determination unit (5) outputs a determination result indicating an excessive wear state of the cutting tool (102) when the load acting on the test workpiece (T) is higher than the wear reference value and lower than the breakage reference value, and issues an end-of-operation command when the load acting on the test workpiece (T) is higher than the breakage reference value.;

Description

TECHNICAL AREA

[0001] The present invention relates to tool life determination devices. STATE OF THE ART

[0002] A known fracture prediction method in the prior art involves setting a cutting tool fracture risk torque threshold value with a magnitude just before reaching fracture of a cutting tool from a cutting torque pattern obtained when a test workpiece is experimentally machined using a new cutting tool and comparing the set cutting tool fracture risk torque threshold value with a cutting torque pattern detected when an actual workpiece is machined in order to predict fracture of the cutting tool (see, for example, patent literature 1).

[0003] In this fracture prediction method, the torque pattern is detected by placing a torque sensor between a tool holder that holds the cutting tool and a motor that drives the tool. LITERATURE LIST PATENT LITERATURE

[0004] PTL 1 Japanese unexamined patent application, publication number Hei 6-198547 SUMMARY OF THE INVENTIONAL ENGINEERING TASK

[0005] Although the cutting torque pattern detected when machining the actual workpiece is compared with the cutting tool breakage risk torque threshold in the breakage prediction method according to patent literature 1, the machining surface of the cutting tool is not uniform depending on the shape of the workpiece, causing the load to fluctuate considerably during the process. This is problematic because it is difficult to determine the tool life.

[0006] Furthermore, since the torque sensor detects torque applied to a section that includes not only the tool but also a heavy object, such as the tool holder, an expensive sensor with a large dynamic range is required to detect variations in the torque pattern caused by tool wear. Using a less expensive sensor with a small dynamic range makes achieving the highest measurement accuracy difficult.

[0007] The present invention has been made in view of the circumstances described above, and one object of it is to provide a tool life determination device that can accurately determine the wear state of a cutting tool using a cost-effective sensor. SOLUTION TO THE TASK

[0008] To fulfill the problem described above, the present invention provides the following solutions.

[0009] One aspect of the present invention provides a tool life determination device comprising: a test workpiece carrier having a cutting tool attached thereto, which rotates the cutting tool and carries a test workpiece positioned in a machinable area of ​​the cutting tool of a machine tool performing a machining operation while changing a relative position between the cutting tool and a workpiece; a load sensor positioned between the test workpiece carrier and a lower part of the machine tool attached to a mounting surface, which detects a load acting on the test workpiece; a storage unit that stores a load pattern acting on the test workpiece and detected by the load sensor when the test workpiece is machined using a new cutting tool;a determination unit that determines the wear state of the cutting tool by comparing the load pattern stored in the memory unit with the load acting on the test workpiece and detected by the load sensor at a suitable time during an actual work operation carried out on the workpiece.

[0010] According to this principle, when a new cutting tool is attached, it is first positioned on the test workpiece, which is located within the machinable area. The test tool is then used to machine the workpiece under a predefined machining condition, and the load pattern acting on the test workpiece, detected by the load sensor at that time, is stored in the memory unit. When the actual workpiece is to be machined using the same cutting tool, the cutting tool is positioned on the test workpiece at a suitable time. The test workpiece is then machined under the same machining conditions as the first time, and the load is detected by the load sensor at that time.The determination unit determines the wear state of the cutting tool by comparing the detected load with the load pattern stored in the storage unit with respect to the new cutting tool.

[0011] In this respect, the load acting on the cutting tool during a machining operation on the actual workpiece is not detected, but instead compared with the load acting on the test workpiece. This allows for the maintenance of a fixed machining condition, thus increasing the accuracy for determining the wear state. Furthermore, the load sensor is located on the test workpiece side, which is relatively light, rather than on the cutting tool side. This ensures that changes in the wear state can be accurately detected, even when using a less expensive sensor with a smaller dynamic range than the load sensor. This is advantageous because it allows for the precise determination of the tool's service life.

[0012] In the aspect described above, the lower part can be a platform of the machine for fixing the workpiece, and the platform can be moved in relation to the cutting tool to change the relative position between the cutting tool and the workpiece and also to position the test workpiece within the machinable area.

[0013] Accordingly, the test workpiece carrier is fixed via the load sensor to a part of the platform used to secure the workpiece in the machine. This allows the cutting tool to be quickly positioned on the workpiece or the test tool by moving the cutting tool and the platform relative to each other. The test workpiece can therefore be quickly machined at a suitable point during a machining operation, enabling precise determination of the tool's service life.

[0014] Furthermore, in the aspect described above, the lower part can be a robot whose remote end carries the test workpiece carrier, and the robot can be moved in relation to the cutting tool to position the test workpiece within the machinable area.

[0015] Accordingly, the robot, which holds the test workpiece attached to the test workpiece carrier at the remote end, is actuated so that the test workpiece is positioned within the machinable area of ​​the cutting tool, allowing it to be machined using the cutting tool. The platform on which the workpiece is to be mounted does not need to be provided with an additional stroke for the test workpiece.

[0016] Furthermore, in the aspect described above, the test workpiece can comprise a plurality of areas with which the cutting tool can be touched under identical machining conditions, and the determination unit can include a correction table to correct the load detected by the load sensor according to the respective area.

[0017] Accordingly, the wear condition can be determined multiple times without replacing the test workpiece during a machining operation performed on the workpiece using the cutting tool. Even if the load pattern detected by the load sensor changes as a result of machining different areas of the same test workpiece, the load detected for each area is corrected based on the correction table, allowing the wear condition to be determined based on a fixed criterion. Furthermore, since the test workpiece is not replaced during a machining operation, variations in the machining conditions with respect to the test workpiece are prevented, thus increasing the accuracy of the determination. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0018] The present invention is advantageous in that it can accurately determine the wear state of a cutting tool using a cost-effective sensor. List of characters Fig. Figure 1 is a block diagram showing a machining system comprising a tool life determination device according to an embodiment of the present invention. Fig. 2 is a front view showing one in the tool life determination device in Fig. 1 included test workpiece carrier and a test workpiece. Fig. Figure 3 shows an example of a load pattern detected by a load sensor in the tool life determination device in Fig. 1 was detected. Fig. Figure 4 is a flowchart that illustrates a procedure for machining a workpiece using the machining system in Fig. 1 shows. Fig. 5 is a flowchart that shows a wear determination process in the flowchart in Fig. 4 shows. Fig. Figure 6 is a top view showing an example of how the test workpiece and the load sensor are installed in the machining system. Fig. are arranged in 1. Fig. Figure 7 shows a modification of the tool life determination device in Fig. 1 and is a perspective partial view showing a case where the test workpiece carrier consists of a robot. Fig. Figure 8 shows another example of the processing system in Fig. 7. Fig. Figure 9 is a block diagram showing a stage in which the robot moves the test workpiece within a machinable area of ​​a cutting tool in the machining system. Fig. 7 orders. Fig. Figure 10 is a perspective partial view showing a stage in which a tool is being inserted by a robot hand into the machining system in Fig. 7 is seized. Fig. Figure 11 is a perspective partial view showing a stage in which the test workpiece is being moved by a robotic hand within the machining system. Fig. 7 is seized. DESCRIPTION OF EXECUTION FORMS

[0019] A tool life determination device 1 According to one embodiment of the present invention, the following is described with reference to the drawings.

[0020] The tool life determination device 1 According to this embodiment, in a working machine 100 to use, which are in Fig. 1 is shown.

[0021] The work machine 100 includes, for example, a platform (lower part) 101 , which are located on a floor surface (mounting surface)F is mounted and a workpiece W moved horizontally while moving the workpiece W fixed, a processing head 103 , which is above the platform 101 is arranged and a cutting tool 102 rotating the cutting tool 102 carries a lifting shaft 104 , which the processing head 103 caused to rise and fall in a vertical direction, and a control 105 , which the processing head 103 , the platform 101 , and the lifting shaft 104 controls 105 is with a monitor 106 tied together.

[0022] The processing head 103 causes the cutting tool 102 , arranged in such a way that the cutting edge is oriented vertically downwards.

[0023] In the drawings, reference symbols denote 107 , 108 , 109 ,110 and 111 Each has a motor located in the machining head. 103 is provided and a driving force for rotating the cutting tool. 102 generated, a linear guide that the lifting shaft 104 forms a slide that is guided by a linear guide 108 carried in an ascending / descending manner, a motor that generates a driving force, and a ball screw that drives the carriage 109 caused to use the motor 110 to rise and fall. Furthermore, reference symbols denote 112 a motor that provides driving force to propel the platform 101 generated.

[0024] The tool life determination device 1 According to this embodiment, it comprises: a test workpiece carrier 2 , which is on part of the platform 101 is arranged, which the workpiece W the working machine 100fixed, and the test workpiece T carries; a load sensor 3 , which is between the test workpiece carrier 2 and the platform 101 is arranged; a storage unit 4 , which is measured by the load sensor 3 The detected load pattern is stored when the test workpiece T is processed at a stage in which a new cutting tool is used. 102 is appropriate; and a unit of determination 5 , which indicate the wear condition of the cutting tool 102 determined by a load that is detected when the test workpiece T at a suitable time during a work process carried out on the workpiece W is processed with the storage unit 4 The stored load patterns are compared.

[0025] The test piece T For example, a rectangular metal block. The test workpiece carrier. 2The test piece T , so that one surface of it is perpendicular to the axis of the cutting tool 102 is arranged. In the case of a Fig. The test workpiece carrier is included in the second example shown. 2 a supporting structure 6 with a recording surface 6a , on which the test workpiece T is recorded, and a fixing unit 7 , which the test workpiece T fixed by friction, by being placed on the receiving surface 6a of the supporting structure 6 recorded test workpiece T against the supporting structure 6 is pressed.

[0026] The load sensor 3 For example, it detects a vertical compressive force exerted by the test workpiece. T from the cutting tool 102 during one of the test pieces T through the cutting tool 102 The machining process is recorded.

[0027] The storage unit 4 stores a time-dependent change in the load sensor reading 3 detected compressive force as a load pattern when the test workpiece T machining is carried out at a stage in which a new cutting tool is used. 102 appropriate.

[0028] The unit of determination 5 establishes reference values ​​(i.e., a wear reference value and a fraction reference value in a Fig. 3 (example shown) for the storage unit 4 Stored load patterns determine that the cutting tool 102 has been excessively worn and therefore has a reduced service life, if the load sensor 3 The detected pressure force exceeds the wear reference value, and it is determined that there is a high probability that the cutting tool 102 It can break if the compressive force exceeds the fracture reference value.

[0029] In a case where the wear reference value is, for example, 20% higher than the maximum value in relation to the new cutting tool 102 detected load pattern and the fracture reference value is, for example, 70% higher than the maximum value in relation to the new cutting tool 102 Based on the detected load pattern, it is determined that the cutting edge is broken, or if no load is applied, it is determined that the entire cutting tool is broken.

[0030] The wear determination process is carried out by the determination unit. 5 regularly at a predetermined interval or at a suitable time when the workpiece W The replacement is carried out after the machining process is completed.

[0031] The operation of the tool life determination device 1 This embodiment with the previously described configuration is described below.

[0032] As in Fig. As shown in section 4, this is done to extend the service life of the cutting tool. 102 using the tool life determination device 1 To determine according to this embodiment, it is first determined whether the cutting tool 102 is new or not (step S1 ). If the cutting tool 102 What is new is that a load pattern is created by machining the test workpiece. T detected (step S2 ) and the detected load pattern is stored in the storage unit 4 saved (step S3 ). If, in contrast, in step S1 It is determined that the cutting tool 102 Since it's not new, the process continues directly with step S4 on.

[0033] Once the load pattern is saved, a machining operation is performed on an actual workpiece. W using the cutting tool 102 performed (step S4Then, during the machining process of the workpiece... W determines whether a wear determination point has been reached or not (step 5 When a wear determination point is reached, a wear determination process is carried out (step S6 ).

[0034] As it is in Fig. As shown in step 5, this is done in the wear determination step. S6 the platform 101 actuated, so that the test workpiece carrier 2 worn test piece T is moved into a position where it is vertically below the cutting tool 102 is arranged (step S61 ), and a machining process is performed on the test workpiece. T performed (step S62 ).

[0035] During the test workpiece T The load sensor detects the machining process that has been carried out. 3 one on the test workpiece Tfrom the cutting tool 102 applied load (step S63 ), and is based on the one in the storage unit 4 The wear reference value defined in the stored load pattern was compared with the magnitude of the detected load (step S64 ). If the unit of determination 5 determined that the load sensor 3 If the detected load is higher than the wear reference value, it is further determined whether the load is higher than the breakage reference value or not (step S65 ).

[0036] If the load is lower than or equal to the fracture reference value in step S65 If the condition of wear is excessive, it is determined that the wear is excessive, and a determination result is sent to the control system. 105 spent to power the monitor 106 to cause a message to be displayed indicating excessive wear (step S66If the load is higher than the breaking point, it is determined that there is a risk of the cutting tool breaking. 102 exists, and an end-of-operation command and a determination result are sent to the control system. 105 spent to power the monitor 106 to cause a message to be displayed indicating such a risk of breakage (step S67 The process then proceeds with step S7 continues. The process proceeds similarly with step S7 further, if the load sensor 3 detected load as lower than or equal to the wear reference value in step S64 is determined.

[0037] Then in step S7 Determines whether the process is complete or not. If the process is not complete, the steps from step 1 are skipped. S4 and repeated progressively.

[0038] Accordingly, the tool life determination device compares 1According to this embodiment, a reference value is obtained based on a test workpiece machined by machining it. T , when a new cutting tool 102 is appropriate, the detected load pattern is determined, with a load that is detected when the same test workpiece is used. T at a suitable time after the work on a workpiece W The process is being carried out to extend the service life of the cutting tool. 102 to determine. Therefore, unlike in a case where the cutting tool 102 acting load during a process on the actual workpiece W Once a process is detected, a fixed processing condition can be maintained. This is advantageous because it increases the accuracy for determining the wear state.

[0039] Furthermore, the load sensor 3 on the side of the test piece Tis arranged in a way that is relatively easy, instead of being on the side of the cutting tool. 102 , a change in the wear state can be accurately detected, even if a cost-effective sensor with a smaller dynamic range than the load sensor is used. 3 is used. This is advantageous because the tool's service life can be precisely determined.

[0040] As an alternative to this embodiment, in which the excessive wear condition is determined by comparing a single wear reference value with the load, a plurality of wear reference values ​​can be prepared so that the wear condition is determined step by step.

[0041] Furthermore, as an alternative to the above-described example of setting the wear reference value and the breakage reference value, the reference values ​​can be set to other freely chosen values.

[0042] In this embodiment, the same test workpiece is used. T processed when a load pattern results from the machining of the test workpiece T using a new cutting tool 102 is recorded and when a load is applied as a result of machining the test workpiece. T using a cutting tool 102 after machining a workpiece W is detected. Alternatively, different positions on the same surface of the same test workpiece can be used. T They are machined to achieve a fixed machining condition. For example, in Fig. As shown in section 6, the surface of the test workpiece can be examined. T in a number of areas A be subdivided so that another area A can be edited for each load detection process.

[0043] In this case, since each area is arranged to have a different positional relationship to the load sensor, 3 to exhibit, which is essentially at the center of the test piece T is arranged, the unit of determination 5 be equipped with a correction table that stores a correction coefficient used to correct the magnitude of the signal generated by the load sensor 3 load to be detected in connection with each area A is used. Accordingly, every time a load is to be detected, an unmachined surface of the test workpiece can always be used. T They can be processed. This is advantageous because consistent processing conditions can be easily achieved, and the accuracy for determining the wear state can be increased.

[0044] In this embodiment, the test workpiece carrier 2 to fix the test workpiece T on the platform101 intended, which the workpiece W fixed so that the test workpiece T within a machinable area of ​​the cutting tool 102 is arranged. As it is in Fig. As shown in figure 7, the test workpiece carrier can 2 alternatively from one to the remote end of a robot (working machine, lower part) 200 attached robot hand 201 exist. In the case of the Fig. The example shown in section 7 shows the load sensor. 3 between the robot hand 201 and a wrist end 202 be arranged.

[0045] In particular, the test workpiece T be withdrawn when the workpiece W using the cutting tool 102 is processed as it is in Fig. 8 is shown, and the test piece can T within the machinable area of ​​the cutting tool 102 be arranged by the robot200 is activated when the wear determination process is to be carried out, as described in Fig. Figure 9 shows that similar advantages can be gained as when the test workpiece carrier is used. 2 on the platform 101 is ordered, to be achieved.

[0046] Furthermore, a robot can be used to pick up a tool. 210 from a (not shown) tool supply and for attaching the tool 210 on the work machine 100 as the robot 200 can be used. In this case, the shape of the test workpiece can be T identical to the shape of a part of the robot hand 201 to seize tool 210 be, as it is in the Fig. 10 and Fig. Figure 11 is shown. Thus, the robot can 200 , which is used to attach a tool, as a robot can be used to move a test workpiece. The robot 200It is described as a six-axis articulated robot, but is not limited to that.

[0047] Although a pressure force is considered a load by the load sensor 3 In this embodiment, a disturbance moment, the amplitude of vibrations, the acceleration of vibrations or any other load can alternatively be detected. Reference symbol list 1 Tool life determination device 2 test workpiece carriers 3 Load sensor 4 storage units 5 Unit of determination 100 working machines 101 Platform (lower part) 102 Cutting tool 200 robots (working machine, lower part) Area F Floor area (mounting area) T Test workpiece W workpiece QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 6198547

[0004]

Claims

[1] Tool life determination device, comprising: a test workpiece carrier having a cutting tool attached to it, rotating the cutting tool and carrying a test workpiece positioned in a machinable area of ​​the cutting tool of a machine tool performing a machining operation while changing a relative position between the cutting tool and a workpiece; a load sensor that is arranged between the test workpiece support and a lower part of the machine attached to a mounting surface and detects a load acting on the test workpiece; a storage unit that stores a load pattern acting on the test workpiece and detected by the load sensor when the test workpiece is machined using a new cutting tool; and a determination unit that determines a wear state of the cutting tool by comparing the load pattern stored in the storage unit with the load acting on the test workpiece and detected by the load sensor at a suitable time during an actual work operation carried out on the workpiece. [2] Tool life determination device according to claim 1, wherein the lower part is a platform of the machine for fixing the workpiece, and the platform is moved in relation to the cutting tool to change the relative position between the cutting tool and the workpiece, and also to position the test workpiece within the machinable area. [3] Tool life determination device according to claim 1, the lower part is a robot whose remote end carries the test workpiece carrier, and the robot is moved in relation to the cutting tool to position the test workpiece within the machinable area. [4] Tool life determination device according to one of claims 1 to 3, wherein the test workpiece comprises a plurality of areas with which the cutting tool can be contacted under identical machining conditions, and wherein the determination unit includes a correction table for correcting the load detected by the load sensor according to the respective range.

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