Numerical control device, machine-tool, control method, program, and storage media

Abstract

To provide a numerical control device, a machine-tool, a control method, a program, and a storage media that can monitor the machining load obtained during the desired period in the machining of a workpiece.SOLUTION: A numerical control device controls a machine-tool that process a workpiece using tools based on an NC program. The CPU reads M341, which indicates the start time for acquiring the processing load for workpiece processing, and M340, which indicates the end time for acquiring the processing load, from the NC program instructions (S101). The CPU acquires the machining load during the period from reading M341 to reading M340. The CPU executes monitoring based on the acquired machining load (S123, S125).SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a numerical control device, a machine tool, a control method, a program, and a storage medium.

Background Art

[0002] The detection device described in Patent Document 1 monitors the machining load of a tool. The detection device includes an actual machining load amount acquisition unit and a detection unit. The actual machining load amount acquisition unit acquires the load amount of the tool during the air feed operation and the actual machining operation as the machining load. The air feed operation is an operation mode in which machining of the workpiece by the tool is not performed. The actual machining operation is an operation mode in which machining of the workpiece by the tool is performed. When the air feed operation is executed, the detection unit detects whether the machining load exceeds the air feed threshold value. When the actual machining operation is executed, the detection unit detects whether the machining load exceeds the actual machining threshold value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above detection device, the cutting feed of the tool is performed during the actual machining operation, but a time difference occurs until the tool contacts the workpiece during this cutting feed period. In this case, the detection device cannot monitor the machining load only for the period during which the tool and the workpiece are in contact, for example, during the cutting feed period of the actual machining operation.

[0005] An object of the present invention is to provide a numerical control device, a machine tool, a control method, a program, and a storage medium that can monitor the machining load acquired during a desired period in the machining of a workpiece.

Means for Solving the Problems

[0006] The numerical control device according to claim 1 is a numerical control device that controls a machine tool for machining a workpiece with a tool based on an NC program. Among the commands of the NC program, a first command indicating an acquisition start time for starting the acquisition of the machining load in the machining of the workpiece, and a reading unit that reads a second command indicating an acquisition end time for ending the acquisition of the machining load, and from the time when the reading unit reads the first command until the reading unit reads the second command, a first load acquisition unit that acquires the machining load, and a monitoring unit that executes monitoring based on the machining load acquired by the first load acquisition unit. It is characterized by comprising the above.

[0007] The above numerical control device designates the acquisition start time and the acquisition end time of the machining load by the first command and the second command of the NC program. Therefore, the numerical control device can monitor the machining load acquired during a desired period.

[0008] The numerical control device according to claim 2 includes a second load acquisition unit that acquires a reference machining load serving as a reference for monitoring from the time when the reading unit reads the first command until the reading unit reads the second command, and a storage control unit that stores the reference machining load acquired by the second load acquisition unit. The monitoring unit may monitor the machining load acquired by the first load acquisition unit based on the reference machining load stored by the storage control unit. The numerical control device can monitor the machining load based on the reference machining load.

[0009] The numerical control device according to claim 3 includes a first setting unit that sets a monitoring start time for starting monitoring of the processing load by the monitoring unit during the period from reading the first instruction to reading the second instruction based on the reference processing load stored in the storage control unit; and a second setting unit that sets a monitoring end time for ending monitoring of the processing load by the monitoring unit during the period from reading the first instruction to reading the second instruction based on the reference processing load stored in the storage control unit. The monitoring unit may monitor the processing load acquired by the first load acquisition unit during the period from the monitoring start time set by the first setting unit to the monitoring end time set by the second setting unit. The numerical control device can execute monitoring of the processing load for the period required for monitoring from the monitoring start time to the monitoring end time among the acquired processing loads.

[0010] The numerical control device according to claim 4 includes a third setting unit that sets an upper limit load based on the reference processing load stored in the storage control unit, and a fourth setting unit that sets a lower limit load based on the reference processing load stored in the storage control unit. The monitoring unit may monitor the processing load acquired by the first load acquisition unit based on the upper limit load set by the third setting unit and the lower limit load set by the fourth setting unit. The numerical control device can monitor the processing load based on the upper limit load and the lower limit load based on the reference processing load.

[0011] In the numerical control device according to claim 5, the monitoring unit may include a first notification control unit that notifies of an abnormality in the processing load when it is determined that the processing load acquired by the first load acquisition unit is greater than the upper limit load set by the third setting unit, and a second notification control unit that notifies of an abnormality in the processing load when it is determined that the processing load acquired by the first load acquisition unit is lower than the lower limit load set by the fourth setting unit. The user of the numerical control device can recognize an abnormality in the processing load.

[0012] The numerical control device according to claim 6 includes a third setting unit that sets an upper limit load based on the reference processing load stored in the storage control unit. The monitoring unit may include a first notification control unit that notifies an abnormality in the processing load when it determines that the processing load acquired by the first load acquisition unit is greater than the upper limit load set by the third setting unit. The user of the numerical control device can recognize an abnormality in the processing load.

[0013] The numerical control device according to claim 7 includes a fourth setting unit that sets a lower limit load based on the reference processing load stored in the storage control unit. The monitoring unit may include a second notification control unit that notifies an abnormality in the processing load when it determines that the processing load acquired by the first load acquisition unit is lower than the lower limit load set by the fourth setting unit. The user of the numerical control device can recognize an abnormality in the processing load.

[0014] The numerical control device according to claim 8 may include a display control unit that superimposes and displays on a display unit the reference processing load stored in the storage control unit, the upper limit load set by the third setting unit, the lower limit load set by the fourth setting unit, and the processing load acquired by the first load acquisition unit. In the numerical control device, the user can visually confirm the processing load.

[0015] In the numerical control device according to claim 9, the upper limit load is obtained by adding an upper limit processing load, which is a predetermined offset amount, to the reference processing load, and the lower limit load is obtained by subtracting a lower limit processing load, which is a predetermined offset amount, from the reference processing load. The numerical control device includes a first correction unit that corrects the upper limit processing load based on the amount of change in the reference processing load with respect to the sampling time of the reference processing load, and a second correction unit that corrects the lower limit processing load set by the fourth setting unit based on the amount of change. The third setting unit sets, as the upper limit load, a value obtained by adding the corrected upper limit processing load to the reference processing load, and the fourth setting unit may set, as the lower limit load, a value obtained by subtracting the corrected lower limit processing load from the reference processing load. The numerical control device can appropriately correct the upper limit processing load and the lower limit processing load based on the magnitude of the amount of change in the reference processing load.

[0016] In the numerical control device according to claim 10, the second load acquisition unit acquires the reference machining load for each of the tools used in machining the workpiece based on the NC program, the storage control unit stores the reference machining load acquired by the second load acquisition unit for each tool in association with the corresponding tool, the first load acquisition unit acquires the machining load when machining the workpiece with any one specific tool among the tools, and the monitoring unit may monitor the machining load acquired by the first load acquisition unit based on the reference machining load associated with the specific tool among the reference machining loads stored in association with each tool by the storage control unit. The numerical control device can monitor the machining load based on the reference machining load associated with each tool.

[0017] The numerical control device according to claim 11 includes a fifth setting unit that sets an upper limit value that is the upper limit value of the machining load, and a sixth setting unit that sets a lower limit value that is the lower limit value of the machining load, and the monitoring unit may monitor the machining load acquired by the first load acquisition unit based on the upper limit value set by the fifth setting unit and the lower limit value set by the sixth setting unit. The numerical control device can monitor the machining load based on the upper limit value and the lower limit value.

[0018] In the numerical control device according to claim 12, the monitoring unit includes a third notification control unit that notifies an abnormality of the machining load when it is determined that the machining load acquired by the first load acquisition unit is greater than the upper limit value set by the fifth setting unit, and a fourth notification control unit that notifies an abnormality of the machining load when it is determined that the machining load acquired by the first load acquisition unit is lower than the lower limit value set by the sixth setting unit. The user of the numerical control device can recognize an abnormality of the machining load.

[0019] The numerical control device according to claim 13 includes a fifth setting unit that sets an upper limit value that is the upper limit value of the machining load, and the monitoring unit may include a third notification control unit that notifies an abnormality of the machining load when it is determined that the machining load acquired by the first load acquisition unit is greater than the upper limit value set by the fifth setting unit. The user of the numerical control device can recognize an abnormality of the machining load.

[0020] The numerical control device according to claim 14 includes a sixth setting unit that sets a lower limit value which is the lower limit value of the machining load. The monitoring unit may include a fourth notification control unit that notifies an abnormality of the machining load when it is determined that the machining load acquired by the first load acquisition unit is lower than the lower limit value set by the sixth setting unit. The user of the numerical control device can recognize an abnormality of the machining load.

[0021] The machine tool according to claim 15 is a machine tool that machines a workpiece with a tool based on an NC program, and includes a reading step of reading a first command indicating an acquisition start time at which acquisition of a machining load in machining of the workpiece starts and a second command indicating an acquisition end time at which acquisition of the machining load ends among the commands of the NC program, a first load acquisition step of acquiring the machining load over a period from when the first command is read in the reading step to when the second command is read in the reading step, and a monitoring step of performing monitoring based on the machining load acquired in the first load acquisition step.

[0022] The above machine tool obtains the same effects as the numerical control device according to claim 1.

[0023] The control method according to claim 16 is a control method of a numerical control device that controls a machine tool that machines a workpiece with a tool based on an NC program, and includes a reading step of reading a first command indicating an acquisition start time at which acquisition of a machining load in machining of the workpiece starts and a second command indicating an acquisition end time at which acquisition of the machining load ends among the commands of the NC program, a first load acquisition step of acquiring the machining load over a period from when the first command is read in the reading step to when the second command is read in the reading step, and a monitoring step of performing monitoring based on the machining load acquired in the first load acquisition step.

[0024] The above control method obtains the same effects as the numerical control device according to claim 1.

[0025] The program according to claim 17 causes a computer of a numerical control device that controls a machine tool for machining a workpiece with a tool based on an NC program to execute a reading step of reading, from the commands of the NC program, a first command indicating an acquisition start timing at which acquisition of a machining load in machining of the workpiece is started and a second command indicating an acquisition end timing at which acquisition of the machining load is ended, a first load acquisition step of acquiring the machining load over a period from when the first command is read in the reading step to when the second command is read in the reading step, and a monitoring step of executing monitoring based on the machining load acquired in the first load acquisition step.

[0026] The above program obtains the same effects as the numerical control device according to claim 1.

[0027] The storage medium according to claim 18 stores a program that causes a computer of a numerical control device that controls a machine tool for machining a workpiece with a tool based on an NC program to execute a reading step of reading, from the commands of the NC program, a first command indicating an acquisition start timing at which acquisition of a machining load in machining of the workpiece is started and a second command indicating an acquisition end timing at which acquisition of the machining load is ended, a first load acquisition step of acquiring the machining load over a period from when the first command is read in the reading step to when the second command is read in the reading step, and a monitoring step of executing monitoring based on the machining load acquired in the first load acquisition step.

[0028] The above storage medium obtains the same effects as the numerical control device according to claim 1.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

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Figure 4

Figure 5

Figure 6

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Figure 8

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Figure 10

Figure 11

Figure 12

Figure 13

MODE FOR CARRYING OUT THE INVENTION

[0030] Referring to FIGS. 1 and 2, the machine tool 1 according to the present invention will be described. The upper side, lower side, left side, right side, front side, and back side in FIG. 1 are defined as the upper side, lower side, left side, right side, front side, and back side of the machine tool 1, respectively. The machine tool 1 shown in FIG. 1 is a machine that rotates a tool to perform cutting on a workpiece.

[0031] The machine tool 1 shown in FIGS. 1 and 2 is a vertical machine tool in which a spindle (not shown) extends in the Z-axis direction. The machine tool 1 includes a base portion 2, a machine body 3, and a cover 5. The base portion 2 is an iron base. The machine body 3 is provided above the base portion 2. The machine body 3 performs cutting on a workpiece (not shown) fixed on the upper surface of a worktable (not shown). The worktable is installed on the upper surface of the base portion 2. The cover 5 is fixed above the base portion 2 and surrounds the periphery of the machine body 3. The operation of the machine tool 1 is controlled by a numerical control device 30 (see FIG. 2).

[0032] As shown in FIGS. 1 and 2, the machine tool 1 further includes an operation panel 13. The operation panel 13 is provided at the right part of the front surface 5B of the cover 5. The operation panel 13 includes a display unit 15 and an operation unit 24. The display unit 15 displays various setting screens for selecting various programs, setting machining conditions of the NC program, etc. Further, the display unit 15 displays waveforms of the machining load F (see FIGS. 5 and 7) described later, etc.

[0033] The operator uses the operation unit 24 to input settings of various operations, etc. to the machine tool 1. The operator operates the operation unit 24 while checking the display unit 15 to set various operations of the machine tool 1, machining conditions of the workpiece material, etc. The operator selects and executes the NC program by the operation unit 24.

[0034] Referring to FIG. 2, the electrical configuration of the machine tool 1 will be described. The machine tool 1 includes a numerical control device 30, an operation panel 13, drive circuits 201 to 204, an X-axis motor 51, a Y-axis motor 52, a Z-axis motor 53, a spindle motor 54, etc. The numerical control device 30 includes a CPU 31, a ROM 32, a RAM 33, a timer 23, a storage device 29, a disturbance estimation unit 25, and interfaces 34, 35.

[0035] The CPU 31 comprehensively controls the operation of the machine tool 1. The ROM 32 stores various programs such as a trial machining program and a monitoring program. The trial machining program executes a trial machining process (see FIG. 3) described later. The monitoring program executes a main process (see FIG. 8) described later. The RAM 33 temporarily stores various data, etc.

[0036] The storage device 29 is non-volatile and stores a plurality of NC programs for machining various workpiece materials. The NC program is a program executed for machining the workpiece material. The storage device 29 further stores a reference machining load Fr described later. The machining conditions of the workpiece material can be set in detail by the operator's operation of the operation panel 13.

[0037] The external disturbance estimation unit 25 estimates, for example, the estimated external disturbance force of the spindle motor 54. Any known method may be used for this estimation. For example, it may be estimated from information such as torque, inertia angular acceleration, viscosity, speed, and friction. The estimated external disturbance force of the spindle motor 54 is hereinafter referred to as the "processing load F". Note that, as the processing load F, the forces applied to the work material in the Z-axis, Y-axis, and Z-axis by a force sensor may be used. Further, as the processing load F, the torque around the spindle applied to the work material by a torque sensor may be used. Further, as the processing load F, the vibration amplitude, vibration work, of the work material in the X-axis, Y-axis, and Z-axis by an acceleration sensor, or the vibration amplitude and vibration work of the spindle head in the X-axis, Y-axis, and Z-axis directions may be used. The timer 23 measures, for example, the elapsed time from the acquisition to the end of the processing load F.

[0038] The display unit 15 and the operation unit 24 are connected to the CPU 31 via the interface 34. The CPU 31 controls the drive circuits 201 to 204 via the interface 35. Each of the drive circuits 201 to 204 controls the X-axis motor 51, Y-axis motor 52, Z-axis motor 53, spindle motor 54, etc., respectively. Each of the encoders 51a to 54a detects the position information of the rotational positions of the X-axis motor 51, Y-axis motor 52, Z-axis motor 53, spindle motor 54, etc., respectively. Each of the drive circuits 201 to 204 transmits the detection results of the position information, etc., to the CPU 31 via the interface 35. The CPU 31 controls each of the drive circuits 201 to 204 based on the position information, etc., to perform the processing of the work material.

[0039] Referring to FIG. 3, the trial processing will be described. The operator sets the settings of the machine tool 1 to trial processing operation. The operator attaches a tool to the spindle and sets the work material on the table. The operator operates the operation unit 24 to select and execute an NC program. The CPU 31 reads out the trial processing program stored in the ROM 32 and starts the trial processing. When starting the trial processing, the CPU 31 executes the processing of the work material based on the selected NC program (S1).

[0040] An example of machining based on the NC program (see Figure 4) will be described. For example, the CPU 31 executes machining based on the instructions of each code shown in Figure 4. The machining is tapping with a tap. Assume that the height of the workpiece is, for example, 145 mm in the Z-axis position. For example, the spindle moves at rapid feed up to the Z-axis position of 200 mm (see code G90 G00 Z200. M03 S3000). Also, the spindle executes cutting feed from the Z-axis height of 200 mm to the Z-axis height of 100 mm (see code G01 Z100. F1000). Thereafter, the spindle rises from the Z-axis position of 100 mm to 150 mm (see code G01 Z150. F2000). The spindle moves at rapid feed from the Z-axis position of 150 mm to the Z-axis position of 200 mm (see code G00 Z200.).

[0041] An example of machining based on the NC program (see Figure 6) will be described. For example, the CPU 31 executes machining based on the instructions indicated by each code shown in Figure 6. The machining is tapping with a tap. Assume that the height of the workpiece is, for example, 145 mm in the Z-axis position. The spindle moves at rapid feed up to the Z-axis position of 200 mm (see code G90 G00 Z200. M03 S3000). Cutting feed is executed from the Z-axis height of 200 mm to 100 mm, and the spindle rises from the Z-axis position of 100 to 150 mm (see code G84 Z100. R150. F6000 S3000). The spindle moves at rapid feed from the Z-axis position of 150 mm to the Z-axis position of 200 mm (see code G00 Z200.).

[0042] With reference to Figures 4 and 6, the M code will be described. The M code includes M341 and M340. M341 indicates the acquisition start timing for starting the acquisition of the machining load F in the machining of the workpiece. That is, when the CPU 31 reads M341, it starts the acquisition of the machining load F. M340 indicates the acquisition end timing for ending the acquisition of the machining load F. That is, when the CPU 31 reads the instruction of M340, it ends the acquisition of the machining load F. Therefore, the operator can set the acquisition timing of the machining load F in the NC program. The example of the M code shown in Figures 4 and 6 targets only the section where the cutting feed of the workpiece is executed.

[0043] The CPU 31 acquires the machining load F output from the disturbance estimation unit 25 as the reference machining load Fr (S3). The period for acquiring the reference machining load Fr is from when the M code 341 is read until the M code 340 is read. The reference machining load Fr is acquired at a predetermined sampling time. The sampling time may be set as appropriate. After the acquisition of the reference machining load Fr is completed, the CPU 31 displays the waveform of the acquired reference machining load Fr (see FIGS. 5 and 7) on the display unit 15 (S5). For example, the operator checks the waveform of the machining load F displayed on the display unit 15 and presses the registration button ("Set as reference") (see FIGS. 5 and 7). Thereby, the CPU 31 stores the reference machining load Fr in the storage device 29 (S7). The reference machining load Fr is stored in association with, for example, the NC program number of the NC program, the machining conditions of the workpiece to be machined (type of tool, tool number), etc. The reference machining load Fr serves as a reference for monitoring the machining load F. The NC program number is identification information assigned to identify the NC program.

[0044] The operator removes the workpiece to be machined and sets a new workpiece on the table. The operator reselects and executes the NC program executed in S1. When the NC program is executed, the CPU 31 executes the machining of the workpiece to be machined (S9). The CPU 31 acquires the machining load F during the machining of the workpiece to be machined from the disturbance estimation unit 25 (S11). The acquisition timing of the machining load F is the same period as in the case of S3, from when the M341 is read until the M340 is read. The CPU 31 displays the acquired machining load F on the display unit 15 (S13). In this case, the display unit 15 overlays and displays the machining load F acquired in S11 with respect to the reference machining load Fr (see FIGS. 5 and 7).

[0045] The CPU 31 sets the time constant of the LPF (S15). The operator checks the waveform of the machining load F on the display unit 15 and adjusts the time constant of the LPF. By performing the LPF process, the waveforms of the machining load F and the reference machining load Fr can be smoothly adjusted. Therefore, by appropriately adjusting the time constant of the LPF, the CPU 31 can reduce the influence on monitoring due to variations in the machining load F.

[0046] The CPU 31 sets the monitoring start time ts (S17). The monitoring start time ts is the time when the monitoring of the processing load F starts within the period from reading the M code 341 to reading the M code 340. The operator checks the reference processing load Fr and the processing load F on the display unit 15 and enters the desired time t in the "Monitoring Start Time" column (see FIGS. 5 and 7). For example, the monitoring start time ts is 1000 msec after the acquisition of the processing load F starts (see FIGS. 5 and 7).

[0047] The CPU 31 sets the monitoring end time te (S19). The monitoring end time te is the time when the monitoring of the processing load F ends within the period from reading the M code 341 to reading the M code 340. The operator checks the reference processing load Fr and the processing load F displayed on the display unit 15 and enters the desired time t in the "Monitoring End Time" column (see FIGS. 5 and 7). For example, the monitoring end time te is 2000 msec after the acquisition of the processing load F starts. For example, in FIG. 5, the operator can specify only the period during which the processing load F is stable during the cutting feed period.

[0048] The CPU 31 determines whether it is set in the absolute monitoring mode or the relative monitoring mode (S21). Each monitoring mode is an example of a monitoring method for the processing load F. The absolute monitoring mode is, for example, a method suitable when the change amount of the processing load F is small. The case where the change amount of the processing load F is small refers to, for example, the case of the waveform of the processing load F shown in FIG. 5. On the other hand, the relative monitoring mode is, for example, a method suitable when the change amount of the processing load F is large. The case where the change amount of the processing load F is large refers to, for example, the case of the waveform of the processing load F shown in FIG. 7. For example, the operator selects "Absolute" or "Relative" in the "Judgment Method" on the display unit 15 (see FIGS. 5 and 7). "Absolute" corresponds to the absolute monitoring mode, and "Relative" corresponds to the relative monitoring mode.

[0049] When it is determined that the absolute monitoring mode is selected (S21: YES), the CPU 31 enables setting of the upper limit value Fmax, which is the upper limit value of the processing load F (S23). For example, the operator operates the operation panel 13 to set the upper limit value Fmax on the display unit 15 to "9.1" (see Fig. 5). The CPU 31 enables setting of the lower limit value Fmin, which is the lower limit value of the processing load F (S25). For example, the operator operates the operation panel 13 to set the lower limit value Fmin on the display unit 15 to "7.0" (see Fig. 5). These set values are used in the absolute monitoring process described later. The CPU 31 ends the trial processing.

[0050] On the other hand, when it is determined that the relative monitoring mode is selected (S21: NO), the CPU 31 enables setting of the upper limit processing load A (S27). The upper limit processing load A indicates the offset amount upward from the waveform of the reference processing load Fr (see Fig. 7). The CPU 31 enables setting of the lower limit processing load B (S29). The lower limit processing load B indicates the offset amount downward from the waveform of the reference processing load Fr (see Fig. 7). The offset amounts of the upper limit processing load A and the lower limit processing load B may be the same or different. For example, the operator operates the operation unit 24 to set the upper limit processing load A and the lower limit processing load B. These set values are used in the relative monitoring process described later. The CPU 31 ends the trial processing.

[0051] The operator executes the above-described trial processing for each NC program. The processing conditions of the workpiece to be machined differ for each NC program. Therefore, the numerical control device 30 can obtain the reference processing load Fr for each processing condition of the NC program, for example, for each tool used.

[0052] The main process will be described with reference to Fig. 8. The operator sets the setting of the machine tool 1 to the monitoring operation. The operator operates the operation unit 24 to select and execute an NC program. The CPU 31 reads out the monitoring program stored in the ROM 32 and starts the main process.

[0053] When the main process starts, the CPU 31 reads one block of the NC program (S101). The CPU 31 determines whether it has read M341 indicating the monitoring start time ts among the instructions of the NC program (S103). If it is determined that it is not M341 indicating the monitoring start time ts (S103: NO), the CPU 31 determines whether it has read M340 indicating the monitoring end time te (S105). If it is determined that it is not M340 indicating the monitoring end time te (S105: NO), the CPU 31 executes the instruction indicated by the code of one block (S107). For example, the CPU 31 executes the spindle overspeed.

[0054] The CPU 31 determines whether the monitoring mode is set to ON (S115). If it is determined that the monitoring mode is set to OFF (S115: NO), the CPU 31 advances the process to S129. Note that in the initial setting, the monitoring mode is set to OFF.

[0055] On the other hand, if it is determined that M341 indicating the monitoring start time ts has been read (S103: YES), the CPU 31 sets the monitoring mode to ON (S111). The CPU 31 initializes the time t of timer 23 to 0 (S113). The CPU 31 advances the process to S115.

[0056] On the other hand, when the monitoring mode is set to ON (S115: YES), the CPU 31 determines whether it is in the absolute monitoring mode (S117). If it is determined that it is in the absolute monitoring mode (S117: YES), the CPU 31 executes the absolute monitoring process shown in FIG. 9 (S123).

[0057] When the CPU 31 executes the absolute monitoring process shown in Fig. 9, it acquires the processing load F from the disturbance estimation unit 25 (S201). The CPU 31 performs LPF processing on the acquired processing load F based on the time constant set in the trial processing (S203). The CPU 31 determines whether the time t indicated by the timer 23 has reached the monitoring start time ts set in the trial processing (S205). If it is determined that the time t indicated by the timer 23 has not reached the monitoring start time ts (S205: NO), the CPU 31 ends the absolute monitoring process and returns the process to the main process.

[0058] On the other hand, if it is determined that the time t indicated by the timer 23 has reached the monitoring start time ts (S205: YES), the CPU 31 determines whether the time t indicated by the timer 23 has reached the monitoring end time te (S207). If it is determined that the time t indicated by the timer 23 has not reached the monitoring end time te (S207: YES), the CPU 31 determines whether the processing load F is greater than the upper limit value Fmax (S209).

[0059] If it is determined that the processing load F is less than or equal to the upper limit value Fmax (S209: NO), the CPU 31 determines whether the processing load F is lower than the lower limit value Fmin (S211). If it is determined that the processing load F is greater than or equal to the lower limit value Fmin (S211: NO), the CPU 31 returns the process to the main process assuming that there is no abnormality in the processing load F.

[0060] On the other hand, if it is determined that the processing load F is greater than the upper limit value Fmax (S209: YES), that is, if an abnormality in the acquired processing load F is detected, the CPU 31 alarms and notifies that the upper limit value Fmax has been exceeded (S213). The alarm notification may, for example, display a string such as "There is an abnormality in the processing load" on the display unit 15. Also, the alarm notification may give a warning with a buzzer or the like. The CPU 31 stops the drive of the machine tool 1 (S217). The CPU 31 ends the absolute monitoring process and returns the process to the main process.

[0061] On the other hand, when it is determined that the processing load F is lower than the upper limit value Fmax (S211: YES), that is, when an abnormality in the acquired processing load F is detected, the CPU 31 issues an alarm notification indicating that the value has fallen below the lower limit value Fmim (S215). The alarm notification is executed in the same manner as when the upper limit value Fmax is exceeded, for example. The CPU 31 stops the drive of the machine tool 1 (S217). The CPU 31 ends the absolute monitoring process and returns the process to the main process.

[0062] On the other hand, when it is determined in S117 of the main process that it is in the relative monitoring mode (S117: NO), the CPU 31 executes the relative monitoring process shown in FIG. 10 (S125).

[0063] When the relative monitoring process shown in FIG. 10 is executed, the CPU 31 acquires the processing load F from the disturbance estimation unit 25 (S301). The CPU 31 acquires the reference processing load Fr from the storage device 29 (S303). In this case, the CPU 31 acquires the reference processing load Fr acquired at the same time as the time t indicated by the timer 23. The CPU 31 performs LPF processing on the processing load F and the reference processing load Fr with a time constant set in the trial machining process (S305).

[0064] The CPU 31 acquires the slope α with reference to the following (Equation 1) (S307). The CPU 31 calculates the slope α per unit time by dividing the absolute value of the difference between the reference processing load Fr at the time t-1 of the previous sampling and the reference processing load Fr at the time t of the current sampling by the sampling time. α = |Fr t ―Fr t-1 | ÷ sampling time ··· (Equation 1)

[0065] The CPU 31 corrects the upper limit processing load A set in the trial machining process based on the slope α. Here, the following mathematical formula (Equation 2) is used for the correction of the upper limit processing load A. A' = α × tc when α × tc > A, A when α × tc ≤ A ··· (Equation 2) Here, A' is the corrected upper limit machining load. α is the slope. tc is the allowable time for variation. The allowable time for variation tc is a parameter determined according to the variations of the machine tool 1, the workpiece, the tool, etc. Therefore, when the slope α is greater than A, the corrected upper limit machining load A' increases proportionally, and when the slope α is less than or equal to A, the corrected upper limit machining load A' is the same as A before correction (see Fig. 11). Similarly, the CPU 31 corrects the lower limit machining load B (S310). The following mathematical formula (Equation 3) is used for the correction of the lower limit machining load B. B' = α × tc when α × tc > B, B when α × tc ≤ B...(Equation 3) Here, B' is the corrected lower limit machining load. α is the slope. tc is the allowable time for variation.

[0066] The CPU 31 sets the upper limit load Fh (S311). In this case, in principle, the CPU 31 adds the corrected upper limit machining load A' to the reference machining load Fr (see Fig. 7). The value after addition is referred to as the "upper limit load Fh". The upper limit load Fh is a value based on the reference machining load Fr.

[0067] The CPU 31 sets the lower limit load Fl (S313). In this case, in principle, the CPU 31 subtracts the corrected lower limit machining load B' from the reference machining load Fr. The value after subtraction is referred to as the "lower limit load Fl". The lower limit load Fl is a value based on the reference machining load Fr.

[0068] As shown in FIG. 12, when there is no correction between the upper limit processing load A and the lower limit processing load B, the distances between the reference processing load Fr, the upper limit load Fh, and the lower limit load Fl are close to each other. Therefore, when the processing load F varies in the time axis direction due to variations in the machine tool 1, the workpiece, the tool, etc., the CPU 31 is likely to erroneously detect an abnormality in the processing load F. On the other hand, as shown in FIG. 13, when the upper limit processing load A and the lower limit processing load B are corrected, that is, when the corrected upper limit processing load A' and the lower limit processing load B' are used, the distances between the upper limit load Fh and the lower limit load Fl with respect to the reference processing load Fr increase. Therefore, even when the processing load F varies in the time axis direction due to variations in the machine tool 1, the workpiece, the tool, etc., the CPU 31 is less likely to erroneously detect an abnormality in the processing load F. Thus, such correction is effective in that it does not affect the detection ability during a period when the variation in the processing load F is small, and makes it less likely to be affected by variations in the machine tool 1, the workpiece, the tool, etc. during a period when the variation in the processing load F is large.

[0069] The CPU 31 determines whether or not the time t indicated by the timer 23 has reached the monitoring start time ts (S315). If it is determined that the time t indicated by the timer 23 has not reached the monitoring start time ts (S315: NO), the CPU 31 ends the relative monitoring process and returns the process to the main process.

[0070] If it is determined that the time t indicated by the timer 23 has reached the monitoring start time ts (S315: YES), the CPU 31 determines whether or not the time t has reached the monitoring end time te (S317). If it is determined that the time t indicated by the timer 23 has exceeded the monitoring end time te (S317: NO), the CPU 31 ends the relative monitoring process and returns the process to the main process.

[0071] On the other hand, when it is determined that the time t indicated by the timer 23 has not reached the monitoring end time te (S317: YES), the CPU 31 determines whether the acquired processing load F is greater than the upper limit load Fh (S319). When it is determined that the processing load F is equal to or less than the upper limit load Fh (S319: NO), the CPU 31 determines whether the processing load F is lower than the lower limit load Fl (S321). When it is determined that the processing load F is equal to or greater than the lower limit load Fl (S321: NO), the CPU 31 ends the relative monitoring process and returns the process to the main process.

[0072] On the other hand, when it is determined that the processing load F is greater than the upper limit load Fh (S319: YES), that is, when an abnormality has occurred in the processing load F, the CPU 31, similar to S213, notifies an alarm indicating that the upper limit load Fh has been exceeded (S323). The CPU 31 stops the drive of the machine tool 1 (S327). Also, when it is determined that the processing load F is lower than the lower limit load Fl (S321: YES), the CPU 31, similar to S213, notifies an alarm indicating that the lower limit load Fl has been fallen below (S325). The CPU 31 stops the drive of the machine tool 1 (S327). The CPU 31 ends the relative monitoring process and returns the process to the main process.

[0073] When the absolute monitoring process or the relative monitoring process ends, the CPU 31 determines whether there has been a machine stop (S127). When it is determined that the machine has stopped (S127: YES), the CPU 31 ends the process. When it is determined that the machine has not stopped (S127: NO), the CPU 31 advances the process to S129.

[0074] On the other hand, in S129, it is determined whether the read code is M30 (S129). When it is determined that the read code is not M30 (S129: NO), the CPU 31 increments the time t indicated by the timer 23. The CPU 31 returns the process to S101.

[0075] In this way, the CPU 31 executes the acquisition of the processing load F for each sampling time from the monitoring start time ts to the monitoring end time te. When it is determined that the M code 340 indicating the monitoring end time te has been read (S105: YES), the monitoring mode is set to OFF (S109). The CPU 31 proceeds to S115 with the processing.

[0076] On the other hand, when it is determined that the read code is M30 (S129: YES), the CPU 31 displays the processing load F on the display unit 15 (S133). In the case of the absolute monitoring mode, for example, the display unit 15 only displays the processing load F in FIG. 5. In the case of the relative monitoring mode, the display unit 15 overlays and displays the reference processing load Fr, the upper limit load Fh, and the lower limit load Fl as shown in FIG. 7 on the processing load F. Note that in the case of the absolute monitoring mode, when there is a reference processing load Fr, it may be displayed overlapped with the processing load F.

[0077] As described above, the CPU 31 reads the M code 341 indicating the acquisition start time for starting the acquisition of the processing load F in the machining of the workpiece among the commands of the NC program, and the M code 340 indicating the acquisition end time for ending the acquisition of the processing load F. The CPU 31 acquires the processing load F over the period from reading the M code 341 until reading the M code 340. The CPU 31 executes monitoring based on the acquired processing load F.

[0078] The numerical control device 30 designates the acquisition start time and the acquisition end time of the processing load F with the M code 341 and the M code 340 of the NC program. Therefore, the numerical control device 30 can monitor the processing load F acquired during a desired period.

[0079] The CPU 31 acquires the reference processing load Fr serving as a reference for monitoring over the period from reading the M code 341 until reading the M code 340. The CPU 31 stores the acquired reference processing load Fr. The CPU 31 monitors the acquired processing load F based on the stored reference processing load Fr. The numerical control device 30 can monitor the processing load F based on the reference processing load Fr.

[0080] Based on the stored reference processing load Fr, the CPU 31 sets the monitoring start time ts at which to start monitoring the processing load F during the period from reading the M code 341 to reading the M code 340. Based on the stored reference processing load Fr, the CPU 31 sets the monitoring end time te at which to end the monitoring of the processing load F during the period from reading the M code 341 to reading the M code 340. The CPU 31 monitors the acquired processing load F during the period from the set monitoring start time ts to the set monitoring end time te. The numerical control device 30 can execute monitoring of the processing load F for the period required for monitoring from the monitoring start time ts to the monitoring end time te among the acquired processing loads F.

[0081] The CPU 31 sets the upper limit load Fh based on the stored reference processing load Fr. The CPU 31 sets the lower limit load Fl based on the stored reference processing load Fr. The CPU 31 monitors the processing load F based on the set upper limit load Fh and the set lower limit load Fl. The numerical control device 30 can monitor the processing load F based on the upper limit load Fh and the lower limit load Fl based on the reference processing load Fr. The numerical control device 30 can execute appropriate monitoring even when, for example, the variation in the reference processing load Fr is large.

[0082] When the CPU 31 determines that the acquired processing load F is greater than the set upper limit load Fh, it notifies an abnormality in the processing load F. When the CPU 31 determines that the acquired processing load F is lower than the set lower limit load Fl, it notifies an abnormality in the processing load F. The user of the numerical control device 30 can recognize an abnormality in the processing load F.

[0083] The CPU 31 superimposes and displays the stored reference processing load Fr, the set upper limit load Fh, the set lower limit load Fl, and the acquired processing load F on the display unit 15. With the numerical control device 30, the user can visually confirm the processing load F.

[0084] The upper limit load Fh is obtained by adding the upper limit machining load A, which is a predetermined offset amount, to the reference machining load Fr. The lower limit load Fl is obtained by subtracting the lower limit machining load B, which is a predetermined offset amount, from the reference machining load Fr. The CPU 31 corrects the set upper limit machining load A based on the change amount of the reference machining load Fr with respect to the sampling time of the reference machining load Fr. The CPU 31 corrects the set lower limit machining load B based on the change amount. The numerical control device 30 can appropriately correct the upper limit machining load A and the lower limit machining load B based on the magnitude of the change amount of the reference machining load Fr.

[0085] The CPU 31 acquires the reference machining load Fr for each tool used in machining the workpiece based on the NC program. The CPU 31 stores the reference machining load Fr acquired for each tool in association with the corresponding tool. The CPU 31 acquires the machining load F when machining the workpiece with any one of the tools. The CPU 31 monitors the acquired machining load F based on the reference machining load Fr associated with the current tool among the reference machining loads Fr stored in association with each tool. The numerical control device 30 can monitor the machining load F based on the reference machining load Fr associated with each tool.

[0086] The CPU 31 sets the upper limit value Fmax, which is the upper limit value of the machining load F. The CPU 31 sets the lower limit value Fmim, which is the lower limit value of the machining load F. The CPU 31 monitors the acquired machining load F based on the set upper limit value Fmax and the set lower limit value Fmim. The numerical control device 30 can monitor the machining load F based on the upper limit value Fmax and the lower limit value Fmim. The numerical control device 30 can monitor the machining load F, for example, for a stable period with little variation in the reference machining load Fr.

[0087] When the CPU 31 determines that the acquired machining load F is greater than the set upper limit value Fmax, it notifies an abnormality of the machining load F. When the CPU 31 determines that the acquired machining load F is lower than the set lower limit value Fmim, it notifies an abnormality of the machining load F. The user of the numerical control device 30 can recognize the abnormality of the machining load F.

[0088] In the above description, the M code 341 is an example of the first command of the present invention. The M code 340 is an example of the second command of the present invention. The inclination α is an example of the amount of change of the present invention. The CPU 31 that executes the process of S101 is an example of the reading unit of the present invention. The CPU 31 that executes the processes of S201 and S301 is an example of the first load acquisition unit of the present invention. The CPU 31 that executes the processes of S209, S211, S319, and S321 is an example of the monitoring unit of the present invention. The CPU 31 that executes the process of S3 is an example of the second load acquisition unit of the present invention. The CPU 31 that performs the process of S7 is an example of the memory control unit of the present invention. The CPU 31 that performs the process of S17 is an example of the first setting unit of the present invention. The CPU 31 that performs the process of S19 is an example of the second setting unit of the present invention. The CPU 31 that performs the process of S311 is an example of the third setting unit of the present invention. The CPU 31 that performs the process of S313 is an example of the fourth setting unit of the present invention. The CPU 31 that performs the process of S133 is an example of the display control unit of the present invention. The CPU 31 that performs the process of S309 is an example of the first correction unit of the present invention. The CPU 31 that performs the process of S310 is an example of the second correction unit of the present invention. The CPU 31 that performs the process of S23 is an example of the fifth setting unit of the present invention. The CPU 31 that performs the process of S25 is an example of the sixth setting unit of the present invention. The CPU 31 that performs the process of S323 is an example of the first notification control unit of the present invention. The CPU 31 that performs the process of S325 is an example of the second notification control unit of the present invention. The CPU 31 that performs the process of S213 is an example of the third notification control unit of the present invention. The CPU 31 that performs the process of S215 is an example of the fourth notification control unit of the present invention.

[0089] The present invention is not limited to the above embodiments. The machine tool 1 in the above embodiment is a vertical machine tool whose spindle extends in the Z-axis direction, but the present invention can also be applied to a horizontal machine tool whose spindle extends in the horizontal direction. Further, the machine tool 1 may be of a table traverse type in which the table moves on the XY plane or a column traverse type in which the spindle moves in the XY plane.

[0090] In the above embodiment, M341 and M340 of the machining program are read during cutting feed, but the present invention is not limited to this. M341 and M340 may be appropriately specified by the operator.

[0091] In the above-described embodiment, the monitoring start time ts is set to 1000 msec, and the monitoring end time te is set to 2000 msec or 3000 msec, but it is not limited thereto. For example, the monitoring start time ts may be the same as the time t0, i.e., the processing load acquisition start time. The monitoring start time ts may be appropriately set according to the reference processing load Fr. The same applies to the monitoring end time te.

[0092] In the above-described embodiment, the reference processing load Fr is acquired once, but it is not limited thereto. The reference processing load Fr may be updated according to the situation.

[0093] In the above-described embodiment, in the absolute monitoring mode, the monitoring is performed using the upper limit value Fmax and the lower limit value Fmim, but it is not limited thereto. For example, the monitoring may be executed using only one of the upper limit value Fmax and the lower limit value Fmin. For example, the CPU 31 may only set the upper limit value Fmax, which is the upper limit value of the processing load F. When the CPU 31 determines that the acquired processing load F is greater than the set upper limit value Fmax, it notifies an abnormality in the processing load F. Also, the CPU 31 may only set the lower limit value Fmin, which is the lower limit value of the processing load F. When the CPU 31 determines that the acquired processing load F is lower than the set lower limit value Fmin, it notifies an abnormality in the processing load F. Even in this case, the user of the numerical control device 30 can recognize an abnormality in the processing load F. Also, the monitoring of the processing load F may be performed by looking at the deviation between the reference processing load Fr and the processing load F.

[0094] In the above-described embodiment, in the relative monitoring mode, the upper limit processing load A and the lower limit processing load B are corrected using the slope α, but they do not have to be corrected. In order to exclude locations where the slope α is steep, the monitoring start time ts and the monitoring end time te may be appropriately set as appropriate.

[0095] In the above-described embodiment, in the relative monitoring mode, the comparison was made between the upper limit load Fh and the lower limit load Fl, but it is not limited thereto. For example, the monitoring may be executed using only one of the upper limit load Fh and the lower limit load Fl. For example, the CPU 31 may only set the upper limit load Fh based on the stored reference processing load Fr. When the CPU 31 determines that the acquired processing load F is greater than the set upper limit load Fh, it notifies an abnormality in the processing load F. On the other hand, the CPU 31 may only set the lower limit load Fl based on the stored reference processing load Fr. When the CPU 31 determines that the acquired processing load F is lower than the set lower limit load Fl, it notifies an abnormality in the processing load F. Even in this case, the user of the numerical control device 30 can recognize an abnormality in the processing load F. Further, the monitoring of the processing load F may be performed by looking at the deviation between the reference processing load Fr and the processing load F. For example, as a comparison value, the change amount around the sampling time of the reference processing load Fr and the change amount of the processing load F may be compared.

[0096] In the above-described embodiment, in the relative monitoring mode, the upper limit load Fh is calculated by adding the upper limit processing load A, which is a predetermined offset amount, to the reference processing load Fr, and the lower limit load Fl is calculated by subtracting the lower limit processing load B, which is a predetermined offset amount, from the reference processing load Fr, but it is not limited thereto. For example, the upper limit load Fh may be calculated by multiplying the reference processing load Fr by a predetermined coefficient Ar. Also, the lower limit load Fl may be calculated by multiplying the reference processing load Fr by a predetermined coefficient Br.

[0097] In the above-described embodiment, in the relative monitoring mode, the reference processing load Fr, the upper limit load Fh, the lower limit load Fl, and the processing load F were displayed superimposed, but it is not limited thereto. For example, at least one of the reference processing load Fr, the upper limit load Fh, the lower limit load Fl, and the processing load F may be displayed. The waveform to be displayed may be set appropriately by the operator.

[0098] In the above-described embodiment, the reference machining load Fr is stored in the storage device 29 without performing the LPF process, but it is not limited to this. The reference machining load Fr may be stored after performing the LPF process. In this case, for the machining load F to be acquired, the monitoring may be executed by performing the LPF process with the same time constant.

Explanation of Signs

[0099] 1 : Machine tool 15 : Display unit 29 : Storage device 30 : Numerical control device 31 : CPU M341 : M code M340 : M code ts : Monitoring start time te : Monitoring end time F : Machining load Fr : Reference machining load A, A': Upper limit machining load B, B': Lower limit machining load Fh : Upper limit load Fl : Lower limit load Fmax : Upper limit value Fmim : Lower limit value α : Slope

Claims

1. In a numerical control device that controls a machine tool for machining a workpiece with a tool based on an NC program, a reading unit that reads a first command indicating an acquisition start time for starting acquisition of a machining load in machining of the workpiece and a second command indicating an acquisition end time for ending acquisition of the machining load among the commands of the NC program; a first load acquisition unit that acquires the machining load over a period from when the reading unit reads the first command until the reading unit reads the second command; a monitoring unit that executes monitoring based on the machining load acquired by the first load acquisition unit characterized in that the numerical control device comprises the above components.

2. a second load acquisition unit that acquires a reference machining load serving as a reference for monitoring over a period from when the reading unit reads the first command until the reading unit reads the second command; a storage control unit that stores the reference machining load acquired by the second load acquisition unit characterized in that the numerical control device comprises the above components, wherein the monitoring unit monitors the machining load acquired by the first load acquisition unit based on the reference machining load stored by the storage control unit. The numerical control device according to claim 1, characterized by the above.

3. a first setting unit that sets a monitoring start time for starting monitoring of the machining load by the monitoring unit during a period from when the first command is read until the second command is read based on the reference machining load stored by the storage control unit; a second setting unit that sets a monitoring end time for ending monitoring of the machining load by the monitoring unit during a period from when the first command is read until the second command is read based on the reference machining load stored by the storage control unit characterized in that the numerical control device comprises the above components, wherein the monitoring unit monitors the machining load acquired by the first load acquisition unit during a period from the monitoring start time set by the first setting unit to the monitoring end time set by the second setting unit. The numerical control device according to claim 2, characterized by the above.

4. a third setting unit that sets an upper limit load based on the reference machining load stored by the storage control unit; a fourth setting unit that sets a lower limit load based on the reference machining load stored by the storage control unit characterized in that the numerical control device comprises the above components, wherein the monitoring unit monitors the machining load acquired by the first load acquisition unit based on the upper limit load set by the third setting unit and the lower limit load set by the fourth setting unit. The numerical control device according to claim 2, characterized by the above.

5. The monitoring unit When it is determined that the processing load acquired by the first load acquisition unit is greater than the upper limit load set by the third setting unit, a first notification control unit that notifies an abnormality in the processing load; When it is determined that the processing load acquired by the first load acquisition unit is lower than the lower limit load set by the fourth setting unit, a second notification control unit that notifies an abnormality in the processing load comprising The numerical control device according to claim 4, characterized in that.

6. Comprising a third setting unit that sets an upper limit load based on the reference processing load stored by the storage control unit, The monitoring unit, When it is determined that the processing load acquired by the first load acquisition unit is greater than the upper limit load set by the third setting unit, a first notification control unit that notifies an abnormality in the processing load comprising The numerical control device according to claim 2, characterized in that.

7. Comprising a fourth setting unit that sets a lower limit load based on the reference processing load stored by the storage control unit, The monitoring unit, When it is determined that the processing load acquired by the first load acquisition unit is lower than the lower limit load set by the fourth setting unit, a second notification control unit that notifies an abnormality in the processing load comprising The numerical control device according to claim 2, characterized in that.

8. A display control unit that superimposes and displays on a display unit the reference processing load stored by the storage control unit, the upper limit load set by the third setting unit, the lower limit load set by the fourth setting unit, and the processing load acquired by the first load acquisition unit The numerical control device according to claim 4, characterized by comprising.

9. The upper limit load is obtained by adding an upper limit processing load, which is a predetermined offset amount, to the reference processing load, The lower limit load is obtained by subtracting a lower limit processing load, which is a predetermined offset amount, from the reference processing load, A first correction unit that corrects the upper limit processing load based on the change amount of the reference processing load with respect to the sampling time of the reference processing load, A second correction unit that corrects the lower limit processing load set by the fourth setting unit based on the change amount comprising The third setting unit sets, as the upper limit load, a value obtained by adding the corrected upper limit processing load to the reference processing load, The fourth setting unit sets, as the lower limit load, a value obtained by subtracting the corrected lower limit processing load from the reference processing load The numerical control device according to claim 4, characterized in that.

10. The second load acquisition unit acquires the reference machining load for each of the tools used in machining the work material based on the NC program, The storage control unit stores the reference machining loads acquired for each tool by the second load acquisition unit in association with the corresponding tools, The first load acquisition unit acquires the machining load when machining the work material with any one specific tool among the tools, The monitoring unit monitors the machining load acquired by the first load acquisition unit based on the reference machining load associated with the specific tool among the reference machining loads stored in association with each tool by the storage control unit The numerical control device according to claim 2, characterized in that.

11. A fifth setting unit that sets an upper limit value that is the upper limit value of the machining load, A sixth setting unit that sets a lower limit value that is the lower limit value of the machining load and The monitoring unit monitors the machining load acquired by the first load acquisition unit based on the upper limit value set by the fifth setting unit and the lower limit value set by the sixth setting unit The numerical control device according to claim 1 or 3, characterized in that.

12. The monitoring unit, When it is determined that the machining load acquired by the first load acquisition unit is greater than the upper limit value set by the fifth setting unit, a third notification control unit that notifies an abnormality of the machining load, When it is determined that the machining load acquired by the first load acquisition unit is lower than the lower limit value set by the sixth setting unit, a fourth notification control unit that notifies an abnormality of the machining load equipped with The numerical control device according to claim 11, characterized in that.

13. It includes a fifth setting unit that sets an upper limit value that is the upper limit value of the machining load, The monitoring unit, When it is determined that the machining load acquired by the first load acquisition unit is greater than the upper limit value set by the fifth setting unit, a third notification control unit that notifies an abnormality of the machining load equipped with The numerical control device according to claim 1 or 3, characterized in that.

14. It includes a sixth setting unit that sets a lower limit value that is the lower limit value of the machining load, The monitoring unit, When it is determined that the machining load acquired by the first load acquisition unit is lower than the lower limit value set by the sixth setting unit, a fourth notification control unit that notifies an abnormality of the machining load equipped with The numerical control device according to claim 1 or 3, characterized in that.

15. In a machine tool that machines a work material with a tool based on an NC program, Among the instructions of the NC program, a reading step of reading a first instruction indicating an acquisition start time at which acquisition of a machining load in machining of the workpiece starts and a second instruction indicating an acquisition end time at which acquisition of the machining load ends; A first load acquisition step of acquiring the machining load over a period from when the first instruction is read in the reading step until when the second instruction is read in the reading step; A monitoring step of executing monitoring based on the machining load acquired in the first load acquisition step A machine tool characterized by comprising the above.

16. In a control method of a numerical control device that controls a machine tool for machining a workpiece with a tool based on an NC program, Among the instructions of the NC program, a reading step of reading a first instruction indicating an acquisition start time at which acquisition of a machining load in machining of the workpiece starts and a second instruction indicating an acquisition end time at which acquisition of the machining load ends; A first load acquisition step of acquiring the machining load over a period from when the first instruction is read in the reading step until when the second instruction is read in the reading step; A monitoring step of executing monitoring based on the machining load acquired in the first load acquisition step A control method characterized by executing the above.

17. In a computer of a numerical control device that controls a machine tool for machining a workpiece with a tool based on an NC program, Among the instructions of the NC program, a reading step of reading a first instruction indicating an acquisition start time at which acquisition of a machining load in machining of the workpiece starts and a second instruction indicating an acquisition end time at which acquisition of the machining load ends; A first load acquisition step of acquiring the machining load over a period from when the first instruction is read in the reading step until when the second instruction is read in the reading step; A monitoring step of executing monitoring based on the machining load acquired in the first load acquisition step A program characterized by causing the above to be executed.

18. In a computer of a numerical control device that controls a machine tool for machining a workpiece with a tool based on an NC program, Among the instructions of the NC program, a reading step of reading a first instruction indicating an acquisition start time at which acquisition of a machining load in machining of the workpiece starts and a second instruction indicating an acquisition end time at which acquisition of the machining load ends; A first load acquisition step of acquiring the processing load over a period from reading the first instruction in the reading step until reading the second instruction in the reading step; A monitoring step of performing monitoring based on the processing load acquired in the first load acquisition step; A storage medium storing a program for executing the above.

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