Waveform extraction device

Abstract

To extract the operational state of a rotary tool during machining.SOLUTION: A waveform extraction device 6 for extracting an operational waveform during machining of a workpiece 2 by a tap 7, comprises: an acquisition part that acquires time-series waveform data on a main shaft current of a motor 8 that drives the tap 7; an extraction part that extracts partial waveform data from the waveform data, the partial waveform data being within a predetermined range set in advance as upper and lower limits of the main shaft current value during the machining; and a selection part that selects, partial waveform data, from among the partial waveform data extracted by the extraction part, those having a time width equal to or greater than a predetermined value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a waveform extraction device.

Background Art

[0002] For example, a workpiece is processed using a rotary tool such as a tap. For example, Patent Document 1 describes calculating an increase in power consumption of an electric motor that drives a rotary tool to determine its lifespan.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when processing using a rotary tool, it includes operations such as moving the rotary tool to a predetermined position and standby operations between processes, which are operations not actually performing processing on the workpiece (non-processing operations). For example, the increase in power consumption in Patent Document 1 may include power consumption generated by such non-processing operations, which may affect the accuracy of lifespan determination. That is, for example, for determining the wear state, etc., it is important to extract the state of parameters related to the operating state of the motor that drives the rotary tool during workpiece processing.

[0005] In view of the above problems, an object of the present invention is to provide a waveform extraction device that can extract the operating state of a rotary tool during processing.

Means for Solving the Problems

[0006] In order to solve the above problems, a waveform extraction device according to the present invention is a waveform extraction device that extracts an operation waveform during the processing of a rotary tool for processing a workpiece, and includes an acquisition unit that acquires time-series waveform data of parameters related to the operation state of a motor that drives the rotary tool, an extraction unit that extracts partial waveform data from the waveform data, where the value of the parameter is within a predetermined range preset as the upper limit value and the lower limit value of the parameter during the processing, and a selection unit that selects the partial waveform data whose time width is equal to or greater than a predetermined value from the partial waveform data extracted by the extraction unit.

[0007] Further, in the waveform extraction device, the waveform extraction device further includes an extraction unit that extracts a waveform of a partial time width including the center from the waveform of the overall time width of the partial waveform data selected by the selection unit to obtain processed waveform data.

[0008] Further, in the waveform extraction device, the waveform extraction device further includes a correction unit that corrects the processed waveform data, and the correction unit includes a specifying unit that specifies the waveform of the waveform data in a target period a predetermined period before the start point of the partial waveform data before extracting the processed waveform data to be corrected, a difference calculation unit that calculates the average value of the specified waveform and calculates the difference between the processed waveform data to be corrected and the average value.

[0009] Further, in the waveform extraction device, the rotary tool is a tap.

[0010] Further, in the waveform extraction device, the waveform extraction device further includes a determination unit that determines the wear state of the rotary tool based on the processed waveform data corrected by the correction unit.

Advantages of the Invention

[0011] According to the waveform extraction device of the present invention, the operation state of the rotary tool during processing can be extracted.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are given the same reference numerals as much as possible, and duplicate descriptions are omitted as appropriate.

[0014] ===Embodiment=== <Overall Configuration> FIG. 1 is a schematic diagram showing an example of the overall configuration of a processing system 1 including a waveform extraction device 6 according to the present embodiment. The processing system 1 performs processing on a workpiece 2.

[0015] As shown in FIG. 1, the processing system 1 mainly includes a processing machine 4, a measuring instrument 5, and a waveform extraction device 6.

[0016] The processing machine 4 is provided with a tap 7 as a rotary tool. The tap 7 is a kind of processing tool and is a tool for machining a screw inside a hole of the workpiece 2. For example, by rotating the tap 7 forward and applying a feed, a screw is machined on the workpiece 2, and by rotating the tap 7 backward and applying a feed in the opposite direction, the tap 7 is removed from the workpiece 2.

[0017] The processing machine 4 is a device that controls the rotation and feed of the tap 7. With the control of the processing machine 4, the desired processing is performed on the workpiece 2 using the tap 7. The processing machine 4 is provided with a motor 8 that rotationally drives the tap 7 and a feed motor (not shown) that provides the feed. The tap 7 is rotated by the motor 8, and in synchronization therewith, the feed motor is rotated to provide the feed, thereby processing the workpiece 2.

[0018] The measuring instrument 5 measures parameters related to the operating states of the motor 8 and the feed motor. In this embodiment, the measuring instrument 5 measures the currents in the motor 8 and the feed motor of the processing machine 4. That is, the measuring instrument 5 measures the currents flowing through the motor 8 and the feed motor as the tap 7 is driven. The current flowing through the motor 8 is referred to as the "main spindle current". The current flowing through the feed motor is referred to as the "feed axis current". Hereinafter, unless otherwise specified, the term "current" shall refer to the main spindle current. The measurement result of the main spindle current by the measuring instrument 5 is output to the waveform extraction device 6.

[0019] The waveform extraction device 6 is an information processing device that extracts the operation waveform during the processing of the tap 7 that processes the workpiece 2. The waveform extraction device 6 includes, for example, a control device 20, a communication device 21, a storage device 22, an operation device 23, and a display device 24. The control device 20 is mainly configured to include a CPU (Central Processing Unit) 26 and a memory 27. In the control device 20, the CPU 26 executes a predetermined program stored in the memory 27 or the storage device 22 or the like, and functions as various functional configurations described later. The communication device 21 is composed of a communication interface or the like for communicating with an external device. The storage device 22 is composed of a hard disk or the like, and stores various programs, various information, and information on processing results necessary for the execution of processing in the control device 20. The operation device 23 is a device for performing operations on the waveform extraction device 6, and is, for example, a keyboard, a mouse, or a touch panel. The display device 24 is a device for displaying various information and processing results, and is, for example, a display or a touch panel. Note that the waveform extraction device 6 may be composed of a single information processing device or a plurality of information processing devices. Also, FIG. 1 only shows a part of the main hardware configuration of the waveform extraction device 6, and the waveform extraction device 6 can be provided with other configurations. The waveform extraction device 6 can be configured using a CPU unit or an arithmetic unit such as a PC or a PLC.

[0020] <Functional configuration> FIG. 2 is a block diagram showing an example of various functions in the waveform extraction device 6. Waveform extraction processing is executed by the functions in each block.

[0021] The waveform extraction device 6 includes an acquisition unit 31, a cutout unit 32, a count unit 33, a calculation unit 34, a recording unit 35, a determination unit 36, and a display unit 37. In this embodiment, as an example, the operation waveform during processing extracted by the cutout unit 32 is used by the determination unit 36 for determining the wear state, but the operation waveform may be used for other purposes.

[0022] The acquisition unit 31 acquires time-series waveform data A of parameters related to the operating state of the motor 8 that drives the rotary tool. Specifically, the acquisition unit 31 acquires the spindle current of the motor 8 measured by the measuring instrument 5. That is, the acquisition unit 31 acquires the time-series waveform data A of the spindle current of the motor 8. For example, the acquisition unit 31 performs A / D conversion (analog-digital conversion) on the analog data to acquire the time-series data of the spindle current as digital data.

[0023] FIG. 3 is a diagram showing an example of the time-series waveform data A of the spindle current. In FIG. 3, the vertical axis represents the current value and the horizontal axis represents time. As shown in FIG. 3, the spindle current changes greatly according to the machining operation. For example, at time T1, the tap 7 starts rotating forward, and a large spindle current flows accordingly. Then, at time T2, the tap 7 enters the air cut state. Then, from time T3, the tap 7 starts to contact the workpiece 2, and the spindle current increases accordingly. Then, at time T4, the forward rotation of the tap 7 starts to decelerate, and the spindle current increases accordingly. Thus, the waveform data A includes each state associated with the machining by the tap 7.

[0024] Returning to FIG. 2, the cut-out unit 32 performs a machining process on the waveform data A acquired by the acquisition unit 31. The cut-out unit 32 cuts out the waveform during the machining of the workpiece 2 by the tap 7 from the waveform data A as the machining waveform data C. "During machining" means the state in which the tap 7 is performing the machining process on the workpiece 2. That is, the state in which the tap 7 is performing the female thread machining of the workpiece 2 is "during machining". The cut-out unit 32 discards the waveforms corresponding to the operations that do not actually perform machining on the workpiece 2 (non-machining operations) such as the operation of moving the tap 7 to a predetermined position and the standby operation between machinings from the waveform data A, and cuts out the waveform during machining as the machining waveform data C.

[0025] Specifically, the cut-out unit 32 includes an extraction unit 41, a selection unit 42, an extraction unit 43, and a correction unit 44.

[0026] The extraction unit 41 extracts partial waveform data B in which the value of the spindle current is within a predetermined range R1 from the waveform data A. The predetermined range R1 is a range preset as the upper limit value and the lower limit value of the value of the spindle current (parameter) during machining. The predetermined range R1 is preset as the range of the value of the spindle current in the state where the tap 7 is machining the workpiece 2.

[0027] The extraction unit 41 extracts a partial waveform in which the value of the spindle current is within the predetermined range R1 from the entire waveform indicated by the waveform data A. Then, each of the extracted partial waveforms is set as the partial waveform data B. In this way, the extraction unit 41 performs an extraction process on the waveform data A from the viewpoint of the value of the spindle current.

[0028] For example, FIG. 3 shows an example of the predetermined range R1. When the extraction unit 41 performs processing on the waveform data A as shown in FIG. 3, it extracts each of the partial waveform data B in which the value of the spindle current is within the predetermined range R1. In the example of FIG. 3, partial waveform data B1, partial waveform data B2, partial waveform data B3, partial waveform data B4, and partial waveform data B5 are extracted as the partial waveform data B, respectively.

[0029] Returning to FIG. 2, the selection unit 42 performs selection on the partial waveform data B extracted by the extraction unit 41. Specifically, the selection unit 42 selects the partial waveform data B whose time width is equal to or greater than a predetermined value R2 from among the plurality of partial waveform data B. The predetermined value R2 is preset according to the machining time of the workpiece 2 by the tap 7. In this way, the selection unit 42 performs a selection process on the waveform data A from the viewpoint of the value of the time width. Note that the selection is not limited to the case where the time width is equal to or greater than the predetermined value R2, and selection may be performed when the time width is within a predetermined range.

[0030] In the example of FIG. 3, the selection unit 42 compares the time width of each of the partial waveform data B with a predetermined value R2. Then, the selection unit 42 selects the partial waveform data B3 from among the partial waveform data B. Note that, if the time width of the partial waveform data B3 is ΔT, ΔT is equal to or greater than the predetermined value R2, and the time widths of the partial waveform data B1, the partial waveform data B2, the partial waveform data B4, and the partial waveform data B5 are less than the predetermined value R2. As a result, the operation waveform during processing is selected as the partial waveform data B3.

[0031] Returning to FIG. 2, the extraction unit 43 further extracts the partial waveform data B3 selected by the selection unit 42. Specifically, the extraction unit 43 extracts a waveform having a partial time width from among the waveforms having the entire time width of the partial waveform data B3. For example, when the entire time width of the partial waveform data B3 is 100%, the extraction unit 43 truncates 20% from each of both ends of the entire time width. That is, the extraction unit 43 truncates 20% of each of the end portions on the start side and the end side of the partial waveform data B3 from the entire time width. In this way, the time widths of both ends to be truncated are set according to the entire time width of the partial waveform data B3. As a result, a waveform having a 60% time width including the center of the entire time width of the partial waveform data B3 is extracted. Note that the 20% to be truncated is an example, and the specific ratio is not limited to the above. Also, the time widths to be truncated may be set separately for the start side and the end side of the partial waveform data B3. In this manner, the extraction unit 43 extracts a waveform having a partial time width including the center from among the waveforms having the entire time width of the partial waveform data B3, thereby further extracting the operation waveform during processing to obtain the processed waveform data C.

[0032] In the example of FIG. 3, the extraction unit 43 truncates waveforms having a 20% time width at each of both ends with the time width of the selected partial waveform data B3 being 100%. As a result, waveform portions with large fluctuations in the current values at both ends of the partial waveform data B3 are truncated, and the net forward rotation processing location by the tap 7 is extracted. The net forward rotation processing location is the waveform of the spindle current while the tap 7 rotating forward is performing a processing operation on the workpiece 2. In this way, the extraction unit 43 obtains the net forward rotation processing location as the processed waveform data C.

[0033] Returning to FIG. 2, the correction unit 44 corrects the processed waveform data C. The correction unit 44 sets the processed waveform data C as the correction target and corrects the processed waveform data C that is the correction target. When there are a plurality of processed waveform data C, the correction unit 44 sets one of the processed waveform data C as the correction target and performs correction processing on each of the processed waveform data C.

[0034] Specifically, the correction unit 44 includes a specifying unit 46 and a differentiating unit 47.

[0035] The specifying unit 46 specifies the air cut waveform data D corresponding to the processed waveform data C that is the correction target. Air cutting is a state in which the tap 7 rotates without touching other members before contacting the work 2. That is, the time-series waveform of the spindle current corresponding to the state where the tap 7 is in the air cut state becomes the air cut waveform data D.

[0036] Specifically, the specifying unit 46 first specifies the start point P1 of the partial waveform data B3 before extracting the processed waveform data C that is the correction target in the waveform data A. Then, the specifying unit 46 specifies a predetermined period H1 immediately before the start point P1. Then, the specifying unit 46 sets a certain period immediately before the predetermined period H1 as the target period H2. That is, the predetermined period H1 is between the partial waveform data B3 and the target period H2. In this way, the specifying unit 46 specifies the waveform data A of the target period H2 that is a predetermined period H1 before the start point P1 and sets it as the air cut waveform data D.

[0037] In the example of FIG. 3, the specifying unit 46 specifies a predetermined period H1 immediately before the start point P1 of the partial waveform data B3. The waveform data A of the predetermined period H1 shows, for example, a transition state in which the tap 7 is pressed from the air cut state to the work 2. Then, the specifying unit 46 specifies the waveform data A in the target period H2 immediately before the predetermined period H1 as the air cut waveform data D. In this way, the air cut waveform data D corresponding to the processed waveform data C that is the correction target is specified. The air cut waveform data D is the base state of the spindle current in the rotating state.

[0038] Returning to FIG. 2, the difference unit 47 corrects the machining waveform data C to be corrected according to the specified air cut waveform data D. Specifically, the difference unit 47 calculates the average value of the spindle current of the waveform indicated by the air cut waveform data D. Then, the difference unit 47 calculates the difference between the waveform of the machining waveform data C to be corrected and the average value. As a result, the base portion is removed from the waveform of the machining waveform data C. That is, the corrected machining waveform data C becomes the net spindle current during machining.

[0039] The counting unit 33 counts the number of machining operations, which is the number of times the workpiece 2 is machined by the tap 7. For example, the counting unit 33 performs counting each time the machining waveform data C (or the partial waveform data B3), which is the net forward machining location in the cutting unit 32, is cut out. Note that the counting by the counting unit 33 is not limited to the above timing as long as the number of machining operations can be counted. Also, the count value of the counting unit 33 is reset to the initial value when, for example, the tap 7 is replaced.

[0040] The calculation unit 34 calculates the average value in the corrected machining waveform data C. That is, the average value of the spindle current related to the machining of the workpiece 2 by the tap 7 is obtained. Then, the calculation unit 34 outputs the calculated average value and the count value of the counting unit 33 to the recording unit 35 in association with each other.

[0041] The recording unit 35 receives the average value and the count value from the calculation unit 34, and records the average value and the count value in association with each other in the storage device 22. That is, the average value of the spindle current related to the machining of the workpiece 2 by the tap 7 and the machining number of the machining are associated with each other and recorded as the history information of the tap 7.

[0042] The determination unit 36 determines the wear state of the tap 7 using the recorded history information. That is, based on the machining waveform data C corrected by the correction unit 44, the wear state of the tap 7 is determined.

[0043] First, the determination unit 36 performs regression processing (approximation processing) on the time-series distribution K of the respective average values of the processed waveform data C to obtain a cubic function (a cubic polynomial with the processing number as a variable) representing the cubic curve L. FIG. 4 is a diagram showing an example of the time-series distribution of the respective average values of a plurality of processed waveform data C. As shown in FIG. 4, by arranging the respective average values according to the processing number, a distribution K1 is obtained as the distribution K. The tap 7 progresses in the order of the initial wear state, the steady wear state, and the abnormal wear state with use. FIG. 4 shows an example of the distribution K1 when the wear state of the tap 7 has progressed to the abnormal wear state. In the example of FIG. 4, the period W1 is the initial wear state, the period W2 is the steady wear state, and the period W3 corresponds to the abnormal wear state. The initial wear state is a wear state that occurs in the initial stage of the use of the tap 7. The steady wear state is a wear state that progresses after the initial wear state with the use of the tap 7. The initial wear state and the steady wear state are wear states of the tap 7 for which use is permitted. The abnormal wear state is a wear state that progresses after the steady wear state with the use of the tap 7. The abnormal wear state is an abnormal wear state in which the wear of the tap 7 has progressed significantly, and there is a possibility of processing defects, damage to the workpiece 2 or the tap 7, etc. That is, the abnormal wear state is a wear state of the tap 7 for which use is not permitted. Then, the determination unit 36 performs regression processing on the distribution K1 to obtain a cubic curve L1 as the cubic curve L (a regression curve with the processing number as an explanatory variable and the average value as an objective variable).

[0044] Then, the determination unit 36 differentiates the cubic function representing the cubic curve L1 to obtain a quadratic function (a quadratic polynomial with the processing number as a variable) representing the quadratic curve M. In the example of FIG. 4, the determination unit 36 differentiates the cubic curve L1 to obtain a quadratic curve M1. The quadratic curve M1 has a minimum value at the processing number N1. In the example of FIG. 4, the quadratic curve M1 of a certain tap 7 is shown. For example, when the tap 7 is coated with a coating that is more wear-resistant than the original coating, the minimum value is located at a processing number higher than N1. Also, when the tap 7 is coated with a coating that is less wear-resistant than the original coating, the minimum value is located at a processing number lower than N1.

[0045] Then, the determination unit 36 determines the wear state of the tap 7 based on the presence or absence of a minimum value in the quadratic curve M. Specifically, the determination unit 36 determines whether the extreme value of the quadratic curve M is a minimum value, a maximum value, or no extreme value. And when the quadratic curve M has a minimum value, the determination unit 36 determines that the tap 7 is in an abnormal wear state. Also, when the quadratic curve M has a maximum value or no extreme value, the determination unit 36 determines that the tap 7 is not in an abnormal wear state (initial wear or steady wear). In the example of FIG. 4, since the quadratic curve M1 has a minimum value, the determination unit 36 determines that the tap 7 is in an abnormal wear state.

[0046] On the other hand, FIG. 5 shows the initial wear state in the distribution K1 of FIG. 4 and a part of the steady wear state as a distribution K2. A cubic curve L2 is regressed from the distribution K2, and differentiating the cubic curve L2 gives a quadratic curve M2. The quadratic curve M2 is in a state with a maximum value (a state without a minimum value). Therefore, the determination unit 36 determines that the tap 7 is not in an abnormal wear state. Since FIG. 4 includes the distribution K1 up to the abnormal wear state, the determination unit 36 determines that it is in the abnormal wear state, and since FIG. 5 does not include the distribution K2 up to the abnormal wear state, the determination unit 36 determines that it is not in the abnormal wear state.

[0047] FIG. 6 is a diagram showing an example of the distribution K3 when wear progresses from the distribution K2 in FIG. 5. Specifically, FIG. 6 is a diagram showing the distribution K3 of the average value when the tap 7 is used up to the processing number N2, which is the change point from the state of the distribution K2 in FIG. 5 to the abnormal wear state in FIG. 4. That is, the distribution K3 includes the average value of the processing number N2, which is the change point of the abnormal wear state. When the distribution K3 is regressed to obtain the cubic curve L3 and the cubic curve L3 is differentiated, the quadratic curve M3 is obtained. The quadratic curve M3 is in a state with a minimum value. Note that the distribution that does not include the average value of the processing number N2 (that is, the distribution up to the processing number N2 - 1) is in a state with a maximum value (a state without a minimum value), similar to the case of the distribution K2 in FIG. 5. Therefore, the example of the distribution K3 in FIG. 6 is the case where the quadratic curve M3 changes from a state without a minimum value to a state with a minimum value, and the determination unit 36 determines that the tap 7 has changed to the abnormal wear state, that is, it is the starting point of the abnormal wear state.

[0048] The determination unit 36 outputs the determination result of the wear state of the tap 7 to the recording unit 35 for recording. For example, the recording unit 35 records the average value, the processing number, and the determination result of the wear state based on the distribution K of the average value up to the processing number in association with each other. Note that by executing the above processing in real time for the processing by the tap 7, the determination result of the wear state of the tap 7 is recorded in real time.

[0049] The display unit 37 controls the display device 24 to perform display. Specifically, the display unit 37 causes the display device 24 to display, for example, the information processed by the waveform extraction device 6 such as the information recorded in the recording unit 35. In particular, the display unit 37 displays the determination result of the wear state of the tap 7. By checking the display of the determination result, the user can recognize the current wear state of the tap 7. Also, by checking the determination result that it is the starting point of the abnormal wear state, it can be recognized that the tap 7 has entered the abnormal wear state.

[0050] <Flow of processing> FIG. 7 is a flowchart showing an example of the flow of waveform extraction processing according to the present embodiment. Each process of the following steps is started when the user gives an instruction to start the process after a new tap 7 is provided, for example, replacement of tap 7. Note that the order and content of each of the following steps can be changed as appropriate.

[0051] (Step SP10) The counting unit 33 initializes the count value indicating the number of processed items. That is, the count value becomes 0. Then, the process proceeds to step SP11.

[0052] (Step SP11) The acquisition unit 31 acquires the waveform data A of the time series of the spindle current of tap 7. Then, the process proceeds to step SP12.

[0053] (Step SP12) The extraction unit 41 extracts the partial waveform data B in which the value of the spindle current is within the predetermined range R1 from the waveform data A. Then, the process proceeds to step SP13.

[0054] (Step SP13) The selection unit 42 selects the partial waveform data B having a time width of a predetermined value R2 or more from the extracted partial waveform data B. For example, the partial waveform data B3 is selected as described above. Then, the process proceeds to step SP14.

[0055] (Step SP14) The extraction unit 43 truncates both ends of the selected partial waveform data B by 20% of the total time width to obtain the processed waveform data C. That is, the extraction unit 43 sets the waveform having a time width of 60% including the center of the selected partial waveform data B as the processed waveform data C. Then, the process proceeds to step SP15.

[0056] (Step SP15) The specifying unit 46 specifies the air cut waveform data D corresponding to the processed waveform data C. Then, the process proceeds to step SP16.

[0057] (Step SP16) The difference part 47 calculates the average value of the waveform indicated by the air cut waveform data D. Then, it proceeds to step SP17.

[0058] (Step SP17) The difference part 47 subtracts (takes the difference) the average value calculated from the processed waveform data C and corrects the processed waveform data C. Then, it proceeds to step SP18.

[0059] (Step SP18) The count part 33 counts the number of processes to obtain a count value. Specifically, the count part 33 adds 1 to the number of processes (counts up) to obtain a count value. Then, it proceeds to step SP19.

[0060] (Step SP19) The calculation part 34 calculates the average value for the corrected processed waveform data C. Then, it proceeds to step SP20.

[0061] (Step SP20) The recording part 35 associates the average value calculated by the calculation part 34 with the count value (processing number) counted by the count part 33 and records it as processing history information. Then, it proceeds to step SP21.

[0062] (Step SP21) The determination part 36 determines the wear state of the tap 7 based on the processing history information. Then, it proceeds to step SP22.

[0063] (Step SP22) The display part 37 displays the determination result by the determination part 36. Specifically, it displays whether the wear state of the tap 7 is an abnormal wear state or not (initial wear state or steady wear state). Also, when it is determined in step SP22 that it is the starting point of the abnormal wear state, it displays that it has become the starting point of the abnormal wear state. Then, it proceeds to step SP23.

[0064] (Step SP23) The determination unit 36 determines whether there is a next process. The presence or absence of the next process can be set by the user, for example. Also, for example, it may be possible for the user who has confirmed the display to select whether to continue or end. If there is a next process, return to step SP11 and repeat the process. If there is no next process, end the process.

[0065] By executing the process as described above, the processed waveform data C is cut out according to the process of tap 7 and recorded as an average value. Also, by determining the wear state according to the process, the user can confirm the determination result in real time every time the process progresses.

[0066] <Function and effect> As described above, in the present embodiment, the waveform extraction device 6 is a waveform extraction device 6 that extracts the operation waveform during the processing of the rotary tool that processes the workpiece 2, and includes an acquisition unit 31 that acquires the time-series waveform data A of the parameters related to the operation state of the motor 8 that drives the rotary tool, an extraction unit 41 that extracts from the waveform data A the partial waveform data B in which the parameter value is within a predetermined range R1 preset as the upper limit value and the lower limit value of the parameter value during processing, and a selection unit 42 that selects the partial waveform data B in which the time width is equal to or greater than a predetermined value R2 from the partial waveform data B extracted by the extraction unit 41. According to this configuration, the partial waveform data B that is the operation waveform during processing can be specified from the waveform data A by the predetermined range R1 set for the parameter value and the predetermined value R2 set for the time width. As a result, the operations that do not actually perform processing on the workpiece 2 (non-processing operations) such as the operation of moving the rotary tool to a predetermined position and the standby operation between processes are removed, and the operation state of the rotary tool during processing can be extracted.

[0067] Further, in the waveform extraction device 6 according to the present embodiment, it further includes an extraction unit 43 that extracts a partial time-width waveform including the center from the waveforms of the entire time width of the partial waveform data B selected by the selection unit 42 and uses it as the processed waveform data C. According to this configuration, by extracting a waveform of a partial time width including the center, it is possible to cut off waveform portions with large fluctuations in current values on both end sides. The operating state of the rotary tool during machining can be further extracted.

[0068] Further, in the waveform extraction device 6 according to the present embodiment, a correction unit 44 that corrects the machining waveform data C is further provided. The correction unit 44 includes a specifying unit 46 that specifies the waveform of the waveform data A of the target period H2 that is a predetermined period H1 before the start point of the partial waveform data B before extracting the machining waveform data C to be corrected, and a difference calculation unit 47 that calculates the average value of the specified waveform and calculates the difference between the machining waveform data C to be corrected and the average value. According to this configuration, it is possible to exclude the base state related to the air cut state from the waveform of the machining waveform data C.

[0069] Further, in the waveform extraction device 6 according to the present embodiment, the rotary tool is a tap 7. According to this configuration, when the rotary tool is the tap 7, if the tap 7 is in an abnormal wear state, there is a possibility that the tap 7 will break or the female thread accuracy of the workpiece 2 will be poor. However, since the wear state of the tap 7 can be determined, accidents as described above can be prevented.

[0070] Further, in the waveform extraction device 6 according to the present embodiment, a determination unit 36 that determines the wear state of the rotary tool based on the machining waveform data C corrected by the correction unit 44 is further provided. According to this configuration, by using the machining waveform data C which is the waveform during machining, the determination accuracy of the wear state can be improved.

[0071] <Modification Example> Note that the present invention is not limited to the above-described embodiments. That is, those obtained by appropriately making design changes by those skilled in the art to the above-described specific examples are also included in the scope of the present invention as long as they have the features of the present invention. Further, each element included in the above-described embodiments and the following modification examples can be combined as much as technically possible, and those obtained by combining them are also included in the scope of the present invention as long as they include the features of the present invention.

[0072] For example, in the above embodiment, the case where the tap 7 is used as the rotary tool is described as an example. However, the tool is not limited to the tap 7 as long as it rotates during machining. For example, a drill or the like may be used as the rotary tool.

[0073] Also, in the above embodiment, the case where the current flowing through the motor 8 is used as a parameter related to the operating state of the motor 8 is described as an example. However, the parameter is not limited to the above as long as it indicates the operating state of the motor 8. For example, the torque of the motor 8 may be used as a parameter related to the operating state of the motor 8. Note that the torque of the motor 8 has a correlation with the current of the motor 8. Also, voltage or power consumption may be used as a parameter related to the operating state of the motor 8.

[0074] Also, in the above embodiment, the correction unit 44 corrects the machining waveform data C with the air cut waveform data D, but the correction process may be omitted.

Explanation of Reference Numerals

[0075] 2: Workpiece 6: Waveform extraction device 7: Tap (rotary tool) 8: Motor 31: Acquisition unit 41: Extraction unit 42: Selection unit 43: Excerpt unit A: Waveform data B: Partial waveform data R1: Predetermined range R2: Predetermined value

Claims

1. A waveform extraction device for extracting an operation waveform during machining of a rotary tool for machining a workpiece, an acquisition unit that acquires time-series waveform data of parameters related to the operation state of a motor that drives the rotary tool, an extraction unit that extracts partial waveform data from the waveform data, where the value of the parameter is within a predetermined range preset as the upper limit value and the lower limit value of the parameter during the machining, a selection unit that selects the partial waveform data whose time width is equal to or greater than a predetermined value from the partial waveform data extracted by the extraction unit, and a waveform extraction device comprising the same.

2. an extraction unit that extracts a waveform of a partial time width including the center from the waveform of the overall time width of the partial waveform data selected by the selection unit to obtain processed waveform data, The waveform extraction device according to claim 1, further comprising the same.

3. a correction unit that corrects the processed waveform data, further comprising the same, and the correction unit a specifying unit that specifies the waveform of the waveform data in a target period a predetermined period before the start point of the partial waveform data before extracting the processed waveform data to be corrected, calculates the average value of the specified waveform, and a difference unit that calculates the difference between the processed waveform data to be corrected and the average value, The waveform extraction device according to claim 2, comprising the same.

4. The rotary tool is a tap, The waveform extraction device according to any one of claims 1 to 3.

5. a determination unit that determines the wear state of the rotary tool based on the processed waveform data corrected by the correction unit, The waveform extraction device according to claim 3, further comprising the same.

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