JP2017177323A - Machine tool and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machine tool and a control method which can prevent damage of a main spindle even if a difference between rotational speed of the main spindle and target rotational speed is large.SOLUTION: A machine tool includes: a main spindle on which a tool is mounted; a moving mechanism which moves in an axial direction of the main spindle; a motor which rotates the main spindle around axis thereof; a control device which sequentially reads a plurality of instructions configuring a machining program and controls driving of the moving mechanism and the motor; a first detection section which detects an axial direction position of the main spindle; and a second detection section which detects a circumferential direction position of the main spindle. A vertical direction position of the main spindle is calculated from the circumferential direction position of the main spindle which is detected in the second detection section and a screw cutting command. When a difference between the present vertical direction position of the main spindle which is detected in the first detection section and the calculated vertical direction position of the main spindle exceeds a threshold, first termination processing for terminating the machining program after the completion of execution of the screw cutting command is executed or second termination processing for terminating the machining program before the completion of the execution of the screw cutting command is executed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a machine tool and a control method for controlling an axial position of a spindle on which a tool is mounted and a rotational speed around the axis.

  The machine tool includes a spindle on which a tool is mounted, a moving mechanism that moves the spindle in the axial direction, a motor that rotates the spindle around the axis, and a controller that controls the movement mechanism and the driving of the motor. The control device controls the rotational speed of the main shaft so as to coincide with the target rotational speed at a predetermined position in the axial direction (see, for example, Patent Document 1).

JP2013-206330A

  When a machine tool is threaded, if the difference between the amount of rotation of the main shaft and the amount of vertical movement of the main shaft is large, the tool may be locked to the workpiece and the tool or the main shaft may be damaged.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a machine tool and a control method that can prevent damage to the spindle even if the difference between the rotation speed of the spindle and the target rotation speed is large. .

  A machine tool according to the present invention sequentially receives a spindle on which a tool is mounted, a moving mechanism that moves the spindle in the axial direction, a motor that rotates the spindle around an axis, and a plurality of commands that constitute a machining program. A machine tool comprising: a control device that reads and controls driving of the moving mechanism and the motor; a first detection unit that detects an axial position of the main shaft; and a second detection unit that detects a circumferential position of the main shaft. The control device, when the read command includes a screw cutting command for screwing a workpiece with a tool, the circumferential position of the first spindle detected by the second detection unit, the second detection unit The vertical position of the main shaft is calculated based on the circumferential position of the second main shaft detected in step S and the screw cutting command, and the calculated vertical position of the main shaft and the first detection unit Above the detected spindle A determination unit that determines whether or not the difference between the position of the direction exceeds a predetermined threshold, and when the determination unit determines that the difference exceeds the threshold, after the execution of the screw cutting command is completed, And an end unit that stops either the first end process for ending the execution of the machining program or the second end process for stopping the execution of the machining program. .

  In the machine tool according to the present invention, the control device includes a setting unit configured to set execution of the first end process or the second end process, and the end unit is configured according to the setting in the setting unit. An end process or a second end process is executed.

  In the machine tool according to the present invention, the command includes an extraction command for extracting a tool from a screw hole formed in the workpiece, the threshold includes a first threshold and a second threshold, and the determination unit executes the screw cutting command. A first determination unit that determines whether or not the difference exceeds the first threshold; and a second determination that determines whether or not the difference exceeds the second threshold when the extraction command is executed. And a section.

  In the machine tool according to the present invention, the threshold includes a third threshold and a fourth threshold larger than the third threshold, and the determination unit determines whether the difference exceeds the third threshold. A determination unit, and a fourth determination unit that determines whether or not the difference exceeds the fourth threshold, wherein the third determination unit determines that the difference exceeds the third threshold and the fourth When the determination unit determines that the difference does not exceed the fourth threshold, the end unit executes the first end process, and the fourth determination unit determines that the difference exceeds the fourth threshold When the determination is made, the end unit executes the second end process.

  A control method according to the present invention sequentially includes a spindle on which a tool is mounted, a moving mechanism that moves the spindle in the axial direction, a motor that rotates the spindle around an axis, and a plurality of commands that constitute a machining program. A machine tool comprising: a control device that controls reading and a driving device of a motor; a first detection unit that detects an axial position of the main shaft; and a second detection unit that detects a circumferential position of the main shaft. In the control method, when the read command includes a thread cutting command for threading the workpiece with a tool, the circumferential position of the first spindle detected by the second detection unit is detected by the second detection unit. Based on the circumferential position of the second spindle and the threading command, the vertical position of the spindle is calculated, and the calculated vertical position of the spindle and the spindle detected by the first detector Vertical position of A first end process of ending execution of the machining program after completion of execution of the screw cutting instruction when it is determined whether or not the difference exceeds a predetermined threshold, and when it is determined that the difference exceeds the threshold Alternatively, the execution of the screw cutting command is stopped, and any one of the second end processes for ending the execution of the machining program is executed.

  In the present invention, the vertical position of the main spindle is calculated from the circumferential position of the main spindle detected by the second detector and the screw cutting command. A first ending process for ending the machining program after completion of execution of the threading command when the difference between the current vertical position of the main spindle detected by the first detection unit and the calculated vertical position of the main spindle exceeds a threshold value Or a second end process for ending the machining program before the completion of execution of the thread cutting command.

  In the present invention, either the first end process or the second end process can be set by the setting unit, and an appropriate end process corresponding to the characteristics of the tool and the workpiece can be executed.

  In the present invention, when the workpiece is threaded and the difference between the current vertical position of the main spindle detected by the first detector and the calculated vertical position of the main spindle exceeds a threshold value, the main spindle is being cut during threading. When the rotation of the tool is stopped, the work enters the groove of the tool and the tool and the work are easily locked. When the tool is extracted from the screw hole and the difference exceeds the threshold value, when the main shaft moves in the axial direction, the tool locked to the workpiece is detached from the main shaft and the main shaft is easily damaged. The present invention determines whether or not the difference exceeds the threshold value when performing screw cutting and when extracting, and even if the tool is locked to the workpiece, an appropriate operation of the spindle according to each case To prevent damage to the tool or spindle.

  In the present invention, when the difference exceeds the third threshold value and is equal to or less than the fourth threshold value, it is considered that the degree of locking of the tool to the work is low. Complete execution. When the difference exceeds the fourth threshold value, it is considered that the degree of locking of the tool to the workpiece is high, so the second end process is executed and the execution of the thread cutting command is immediately stopped.

  Calculates the vertical position of the main spindle from the circumferential position of the main spindle detected by the second detector and the threading command, and calculates the current vertical position of the main spindle detected by the first detector and the calculated vertical axis of the main spindle. If the difference in position exceeds the threshold value, the first end process is executed to end the machining program after the completion of execution of the screw cutting command, or the second end process is executed to end the processing program before the completion of execution of the screw cutting instruction. To do. For this reason, even if the tool is locked to the workpiece, an appropriate operation of the spindle according to the situation is executed to prevent the tool or the spindle from being damaged.

1 is a perspective view showing a machine tool according to Embodiment 1. FIG. It is a block diagram which shows a control apparatus. It is a conceptual diagram which shows an example of a process program. It is explanatory drawing explaining operation | movement of a main axis | shaft. It is a flowchart explaining a thread cutting process. It is a flowchart explaining a thread cutting process. 12 is a flowchart for explaining a thread cutting process according to the second embodiment.

(Embodiment 1)
Hereinafter, the present invention will be described based on the drawings showing the machine tool 100 according to the first embodiment. FIG. 1 is a perspective view showing a machine tool 100 according to the first embodiment. In the following description, the top, bottom, left and right, front and back indicated by arrows in the figure are used.

  As shown in FIG. 1, the machine tool 100 includes a rectangular base 1 extending in the front-rear direction. The work holding part 3 is provided on the front side of the upper part of the base 1. The work holding unit 3 can rotate around the A axis extending in the left and right directions and the C axis extending in the up and down directions. The support base 2 is provided on the rear side of the upper part of the base 1 and supports the upright column 4.

  The Y-axis direction moving mechanism 10 is provided on the upper portion of the support base 2 and moves the moving plate 16 in the front-rear direction. The Y-axis direction moving mechanism 10 includes two tracks 11 extending in the front-rear direction, a Y-axis screw shaft 12, a Y-axis motor 13, and a bearing 14. The track 11 is provided on the left and right of the upper part of the support base 2. The Y-axis screw shaft 12 extends in the front-rear direction and is provided between the two tracks 11. The bearings 14 are provided at the front end portion and midway portion (not shown) of the Y-axis screw shaft 12. The Y-axis motor 13 is connected to the rear end portion of the Y-axis screw shaft 12. A nut (not shown) is screwed onto the Y-axis screw shaft 12 via a rolling element (not shown). The rolling element is, for example, a ball. The plurality of sliders 15 are provided on each track 11 so as to be slidable. The moving plate 16 extends in the horizontal direction and is connected to the nut and the upper portion of the slider 15. The Y-axis screw shaft 12 rotates by the rotation of the Y-axis motor 13, the nut moves in the front-rear direction, and the moving plate 16 moves in the front-rear direction.

  The X-axis direction moving mechanism 20 is provided on the upper surface of the moving plate 16 and moves the upright column 4 in the left-right direction. The X-axis direction moving mechanism 20 includes two tracks 21 extending to the left and right, an X-axis screw shaft 22, an X-axis motor 23 (see FIG. 2), and a bearing 24. The track 21 is provided before and after the upper surface of the movable plate 16. The X-axis screw shaft 22 extends left and right and is provided between the two tracks 21. The bearings 24 are provided at the left end portion and midway portion (not shown) of the X-axis screw shaft 22. The X-axis motor 23 is connected to the right end portion of the X-axis screw shaft 22. A nut (not shown) is screwed onto the X-axis screw shaft 22 via a rolling element (not shown). The plurality of sliders 26 are provided on each track 21 so as to be slidable. The upright column 4 is connected to the nut and the upper part of the slider 26. The X-axis screw shaft 22 rotates by the rotation of the X-axis motor 23, the nut moves in the left-right direction, and the upright column 4 moves in the left-right direction.

  The Z-axis direction moving mechanism 30 is provided on the front surface of the upright column 4 and moves the spindle head 5 in the vertical direction. The Z-axis direction moving mechanism 30 includes two tracks 31 extending vertically, a Z-axis screw shaft 32, a Z-axis motor 33, and a bearing 34. The track 31 is provided on the left and right of the front surface of the upright column 4. The Z-axis screw shaft 32 extends vertically and is provided between the two tracks 31. The bearings 34 are provided at the lower end portion and midway portion (not shown) of the Z-axis screw shaft 32. The Z-axis motor 33 is connected to the upper end portion of the Z-axis screw shaft 32. A nut (not shown) is screwed onto the Z-axis screw shaft 32 via a rolling element (not shown). The plurality of sliders 35 are slidably provided on each track 31. The spindle head 5 is connected to the nut and the front part of the slider 35. The Z-axis screw shaft 32 is rotated by the rotation of the Z-axis motor 33, the nut moves in the vertical direction, and the spindle head 5 moves in the vertical direction.

  A main shaft 51 extending vertically is provided in the main shaft head 5. The main shaft 51 rotates around the axis. A spindle motor 6 (motor) is provided at the upper end of the spindle head 5. A tool is attached to the lower end of the main shaft 51. The spindle 51 is rotated by the rotation of the spindle motor 6, and the tool is rotated. The rotated tool processes the workpiece held by the workpiece holding unit 3.

  The machine tool 100 includes a tool changer (not shown) that changes tools. The tool changer exchanges a tool housed in a tool magazine (not shown) and a tool attached to the spindle 51.

  2 is a block diagram showing the control device 60, FIG. 3 is a conceptual diagram showing an example of a machining program, and FIG. 4 is an explanatory diagram for explaining the operation of the spindle. The machine tool 100 includes a control device 60 that controls driving of the motors 6, 13, 23, 33, the work holding unit 3, a tool changer, and the like. As shown in FIG. 2, the control device 60 includes a CPU 61, a ROM 62, a RAM 63, a nonvolatile storage device 64 such as an EEPROM, an input interface 65, an output interface 66, and the like. The CPU 61 reads out a control program stored in the ROM 62 to the RAM 63 and controls driving of the motors 6, 23, 13, 33, the work holding unit 3, the tool changer, and the like.

  The storage device 64 stores a variable n indicating a line number of the machining program, a first threshold C1, a second threshold C2, a cutting level, an extraction level, a machining program for machining the workpiece, and the like. Cutting levels are L and H, and extraction levels are L and H. The operator operates the reception unit 67 to set L or H for the cutting level and the extraction level.

  L indicates that the execution of the machining program is terminated after the machining command has been executed. H indicates that the execution of the machining command is stopped without waiting for the completion of execution of the machining command, and the execution of the machining program is terminated.

  The machine tool 100 includes a receiving unit 67 (setting unit), a Z-axis sensor 68 (first detection unit), and a spindle sensor 69 (second detection unit). The reception unit 67 includes, for example, a keyboard, a touch panel, a display screen, and the like, and receives user operations. The user sets, for example, execution of a first end process or a second end process, which will be described later, in the storage device 64 via the reception unit 67. The Z-axis sensor 68 detects the vertical position of the main shaft 51, in other words, the axial position of the main shaft 51. The main shaft sensor 69 detects the circumferential position of the main shaft 51. The control device 60 inputs a command from the receiving unit 67 via the input interface 65, inputs an axial position from the Z-axis sensor 68, and inputs a rotation speed from the spindle sensor 69. The control device 60 outputs drive signals to the spindle motor 6, the X-axis motor 23, the Y-axis motor 13, and the Z-axis motor 33 via the output interface 66. Since the spindle sensor 69 inputs the rotation amount per unit time to the control device 60, the input is the rotation speed. Further, when the input items are accumulated, the rotation position of the main shaft 51 is obtained.

  As shown in FIG. 3, the “number” column indicates a line number, and the “command” column indicates a process to be executed. The storage device 64 stores a machining program for machining a workpiece. The machining program includes a plurality of lines (commands). The CPU 61 reads the rows in order and executes the instructions. G100 on the N1 line indicates a tool change command, and T1 indicates the number of the tool to be mounted on the spindle 51 next. X-60 represents the horizontal standby position of the main shaft 51 after tool replacement, Y-20 represents the front-rear standby position of the main shaft 51 after tool replacement, and Z20 represents the vertical standby position of the main shaft 51 after tool replacement. Show. The numerical values after X, Y, and Z indicate the position when the processing origin is 0, and the unit is mm. The movement in one direction is indicated by +, and the movement in the other direction is indicated by-. N84, G84 indicates a thread cutting command, M03 indicates that the main shaft 51 rotates forward, S25000 indicates a target rotational speed of the main shaft 51 of 25000 rpm, and Z-5 reaches the vertical direction in thread cutting processing. Indicates the position. I2 indicates that the thread pitch is 2. M04 indicates the reverse rotation of the main shaft 51, S15000 indicates the target rotation speed of the main shaft 51 is 15000 rmp, and Z10 indicates the position reached in the vertical direction in the operation of extracting the main shaft 51 from the screw hole. The main shaft 51 rotates in the forward direction, moves from the standby position to a position reached in the vertical direction in the thread cutting process, threads the workpiece, and forms screw holes in the workpiece. After the screw hole is formed, the main shaft 51 rotates in the reverse direction and moves to a position where it reaches the vertical direction in the extraction operation. M30 on the Nn-th line indicates an end command for the machining program. Note that the cutting level and the extraction level are stored in advance in the storage device 64 by the operator operating the receiving unit 67.

  5 and 6 are flowcharts for explaining the thread cutting process. As shown in FIGS. 5 and 6, the CPU 61 sets 1 to the variable n (step S1), and reads the Nn-th line of the machining program (step S2). The CPU 61 determines whether or not an end command (M30) has been read (step S3). When the end command is read (step S3: YES), the CPU 61 ends the execution of the machining program. If the end command has not been read (step S3: NO), the CPU 61 determines whether or not a screw cutting command has been read (step S4). When the thread cutting instruction is not read (step S4: NO), the CPU 61 executes the read instruction (step S5), adds one variable n (step S6), and returns the process to step S2.

  When the thread cutting command is read (step S4: YES), the CPU 61 refers to the target rotation speed (for example, S25000 in FIG. 3), rotates the main shaft 51 forward, and descends toward the workpiece. Before the main shaft 51 rotates and descends, the current circumferential position of the main shaft 51 is acquired from the main shaft sensor 69 and the current vertical position of the main shaft 51 is acquired from the Z-axis sensor 68 (step S7).

  The CPU 61 acquires the circumferential position of the spindle 51 from the spindle sensor 69 and cumulatively adds the circumferential position of the spindle 51 acquired in step 7 to the acquired circumferential position of the spindle 51. At the same time, the CPU 61 acquires the vertical position of the main shaft 51 from the Z-axis sensor 68, and cumulatively adds the vertical position acquired in step 7 to the acquired vertical position of the main shaft 51 (current vertical position of the main shaft 51). The vertical position of the main shaft 51 is calculated from the circumferential position of the main shaft 51 and the thread pitch (accumulated addition) (target vertical position of the main shaft 51), and the calculated vertical position of the main shaft 51 (target vertical direction of the main shaft 51). The difference (first difference) between the position) and the accumulated vertical position (the current vertical position of the spindle 51) is calculated (step S8). The CPU 61 determines whether or not the first difference has exceeded the first threshold C1 (step S9). When the first difference exceeds the first threshold C1 (step S9: YES), the CPU 61 sets 1 to the first flag of the storage device 64 (step S10) and determines whether or not the cutting level is L (step S10). Step S11). When the first difference exceeds the first threshold C1, the tool is easily locked to the workpiece.

  When the cutting level is L (step S11: YES), the CPU 61 determines whether or not the spindle 51 has reached the position where the extraction operation starts, that is, whether or not the vertical position has been reached (step S12). Specifically, the CPU 61 acquires the vertical position of the main shaft 51 from the Z-axis sensor 68, and determines whether or not the main shaft 51 is positioned at Z-5 (see FIG. 3). When the spindle 51 has not reached the vertical position (step S12: NO), that is, when the tool still threads the workpiece, the CPU 61 returns the process to step S8.

  When the main shaft 51 has reached the vertical position (step S12: YES), the current circumferential position of the main shaft 51 is acquired from the main shaft sensor 69 and the current vertical position of the main shaft 51 is acquired from the Z-axis sensor 68. (Step S13). The CPU 61 refers to the target rotational speed (for example, S15000 in FIG. 3), and reversely rotates and raises the main shaft 51 (step S14).

  The CPU 61 obtains the circumferential position of the spindle 51 from the spindle sensor 69 and cumulatively adds the circumferential position of the spindle 51 obtained in step 13 to the obtained circumferential position of the spindle 51. At the same time, the CPU 61 acquires the vertical position of the main shaft 51 from the Z-axis sensor 68, and cumulatively adds the vertical position acquired in step 13 to the acquired vertical position of the main shaft 51 (the vertical position of the main shaft 51). The vertical position of the main shaft 51 is calculated from the circumferential position of the main shaft 51 and the screw cutting pitch (the target vertical position of the main shaft 51), and the calculated vertical position of the main shaft 51 (the target vertical position of the main shaft 51). ) And the cumulatively added vertical position (current vertical position of the spindle 51) (second difference) is calculated (step S15).

  The CPU 61 determines whether or not the second difference has exceeded the second threshold value C2 (step S16). When the second difference exceeds the second threshold C2 (step S16: YES), the CPU 61 sets 1 to the second flag of the storage device 64 (step S17). When the second difference exceeds the second threshold C2, the tool is easily locked on the workpiece. Thereafter, the CPU 61 determines whether or not the extraction level is L (step S18). When the extraction level is L (step S18: YES), the CPU 61 determines whether or not the extraction operation is finished (step S19). Specifically, the CPU 61 acquires the vertical position of the main shaft 51 from the Z-axis sensor 68, and determines whether or not the main shaft 51 is positioned at Z10 (see FIG. 3). When the extraction operation is not completed (step S19: NO), the CPU 61 returns the process to step S15.

  When the extraction operation has been completed (step S19: YES), the CPU 61 determines whether or not a value other than 0 is set in the first flag or the second flag (step S20). When the first flag and the second flag are both 0 (step S20: NO), the CPU 61 adds one variable n (step S23), and returns the process to step S2.

  When both the first flag and the second flag are 0, the possibility that the tool is locked to the workpiece is low. Therefore, the CPU 61 sequentially reads the machining program lines and continuously executes the machining program until an end command is read. When the end command is read, execution of the machining program is terminated. Since there is a low possibility that the tool will be locked to the workpiece, the CPU 61 executes normal thread cutting and also performs subsequent processing.

  If either the first flag or the second flag is not 0 in step S20 (step S20: YES), the CPU 61 ends the machining program (step S21) and ends the thread cutting process.

  If it is determined in step S9 that the first difference does not exceed the first threshold C1 (step S9: NO), the CPU 61 advances the process to step S12. When the first difference does not exceed the first threshold C1, the possibility that the tool is locked to the workpiece is low. If it is determined in step S16 that the second difference does not exceed the second threshold C2 (step S16: NO), the CPU 61 advances the process to step S19. When the second difference does not exceed the second threshold C2, the possibility that the tool is locked to the workpiece is low.

  If it is determined in step S11 that the cutting level is not L (step S11: NO), that is, if it is determined that the cutting level is H, the CPU 61 stops the thread cutting process (step S22), and the process proceeds to step S20. Proceed. Since 1 is set to the first flag in Step S10 (Step S20: YES), the CPU 61 ends the execution of the machining program (Step S21).

  If it is determined in step S18 that the extraction level is not L (step S18: NO), that is, if it is determined that the extraction level is H, the CPU 61 stops the extraction operation (step S22) and proceeds to step S20. Since 1 is set in the second flag in step S17 (step S20: YES), the CPU 61 ends the execution of the machining program (step S21). The CPU 61 that executes S9 and S16 corresponds to a determination unit.

  S11 and S18 are determined as NO, processing through S22, S20, and S21 corresponds to the second end processing, S11 and S18 are determined as YES, and processing through S20 and S21 is equivalent to the first end processing. To do. The CPU 61 that executes the first end process and the second end process corresponds to an end unit. The CPU 61 that executes S9 corresponds to a first determination unit, and the CPU 61 that executes S16 corresponds to a second determination unit.

  In the machine tool 100 according to the first embodiment, when the difference between the current vertical position of the spindle 51 and the target vertical position of the spindle 51 exceeds the first threshold C1 or the second threshold C2, that is, the determination in step S11 or step S18. Accordingly, after the execution of the thread cutting command or the extraction command is completed, the processing program is terminated (the first termination process is executed), or the execution of the thread cutting command or the extraction command is stopped and the processing program is terminated. (The second end process is executed). Therefore, even if the tool is locked to the workpiece, the main shaft 51 operates appropriately, and the tool or the main shaft 51 can be prevented from being damaged.

  The operator can set either the first end process or the second end process at the receiving unit 67, and can execute an appropriate end process according to the characteristics of the tool and the workpiece.

  When the workpiece is threaded, if the difference between the current vertical position of the main shaft 51 and the target vertical position of the main shaft 51 exceeds the first threshold C1 and the rotation of the main shaft 51 is stopped, the tool is easily locked to the work. When the tool is being extracted from the screw hole, if the difference between the current vertical position of the main shaft 51 and the target vertical position of the main shaft 51 exceeds the second threshold C2 and the main shaft 51 moves in the axial direction, the tool locked to the workpiece is The main shaft 51 is easily damaged by slipping out of the main shaft 51. In the present embodiment, when the screw cutting and the extraction are performed, it is determined whether the difference exceeds the first threshold C1 or the second threshold C2, and even when the tool is locked to the workpiece, Appropriate spindle 51 motion is performed to prevent damage to the tool or spindle 51.

For example, when threading is performed, by setting the cutting level to L, the machine tool does not stop machining during the threading operation even if the difference exceeds the first threshold C1. If the machining is stopped during the screw cutting operation, the tool is locked to the workpiece, and the operator needs to remove the tool from the workpiece. The difference exceeds the first threshold C1 and becomes a defective product as a workpiece, but by setting the cutting level to L, the machine tool can eliminate the above-mentioned work of the operator.
When performing the extraction operation from the screw hole, the extraction level is set to H, the extraction operation is stopped, the machining program is terminated, and the tool 51 is prevented from being detached from the main shaft 51 and being damaged.

(Embodiment 2)
A machine tool 100 according to Embodiment 2 will be described with reference to the drawings. Of the configurations according to the second embodiment, configurations similar to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 7 is a flowchart for explaining the thread cutting process. The storage device 64 stores a third threshold C3 and a fourth threshold C4 that is larger than the third threshold C3. As shown in FIG. 7, the CPU 61 sets 1 to the variable n (step S31), and reads the Nn-th line of the machining program (step S32). The CPU 61 determines whether or not an end command (M30) has been read (step S33). When the end command is read (step S33: YES), the CPU 61 ends the execution of the machining program. When the end command has not been read (step S33: NO), the CPU 61 determines whether or not a screw cutting command has been read (step S34).

  When the thread cutting command is not read (step S34: NO), the CPU 61 executes the read command (step S35), adds one variable n (step S36), and returns the process to step S32. When the thread cutting command is read (step S34: YES), the CPU 61 acquires the current circumferential position of the spindle 51 from the spindle sensor 69 and the current vertical position of the spindle 51 from the Z-axis sensor 68. (Step S37).

  The CPU 61 refers to the target rotation speed (for example, S25000 in FIG. 3), rotates the spindle 51 forward, and descends toward the workpiece (step S38). After completing the forward rotation and lowering operation of the main shaft 51, the CPU 61 automatically executes reverse rotation and upward movement of the main shaft 51, that is, an extraction operation. The CPU 61 acquires the circumferential position of the spindle 51 from the spindle sensor 69, and cumulatively adds the circumferential position of the spindle 51 acquired in S37 to the acquired circumferential position of the spindle 51. The CPU 61 simultaneously acquires the vertical position of the main shaft 51 from the Z-axis sensor 68, and cumulatively adds the vertical position acquired in S37 to the acquired vertical position of the main shaft 51 (current vertical position of the main shaft 51). The vertical position of the main shaft 51 is calculated from the circumferentially added position of the main shaft 51 and the thread cutting pitch (target vertical position of the main shaft 51), and the calculated vertical position of the main shaft 51 (target vertical direction of the main shaft 51) The difference (first difference) between the position) and the accumulated vertical position (the current vertical position of the spindle 51) is calculated (step S39).

  The CPU 61 determines whether or not the difference exceeds the third threshold C3 (step S40). When the difference exceeds the third threshold C3 (step S40: YES), the CPU 61 sets 1 in the flag of the storage device 64 (step S41), and the CPU 61 determines whether the difference exceeds the fourth threshold C4. Determination is made (step S42). If the difference does not exceed the fourth threshold value C4 (step S42: NO), that is, if the difference exceeds the third threshold value C3 and is equal to or less than the fourth threshold value C4, the CPU 61 determines whether or not the extraction operation has ended. Determination is made (step S43).

  When the extraction operation is not completed (step S43: NO), the CPU 61 returns the process to step S39. When the extraction operation has been completed (step S43: YES), the CPU 61 determines whether or not 1 is set in the flag of the storage device 64 (step S44). When 1 is set in the flag (step S44: YES), the CPU 61 ends the machining program (step S45) and ends the process. That is, after completion of the screw cutting and extraction operation, the machining program is terminated without reading other lines. When the difference exceeds the third threshold value C3 and is equal to or less than the fourth threshold value C4, the degree of locking is not large even when the tool is locked to the workpiece. Therefore, after completing the screw cutting and extracting operation, the machining program is terminated without reading other lines.

  If it is determined in step S40 that the difference does not exceed the third threshold C3 (step S40: NO), the CPU 61 advances the process to steps S43 and S44. Since step S41 is not executed, the CPU 61 does not set 1 in the flag of the storage device 64 (step S44: NO).

  The CPU 61 adds one variable n (step S47), and returns the process to step S32. The CPU 61 sequentially reads the lines of the machining program and continuously executes the machining program. When the end command for the machining program is read (step S33: YES), the CPU 61 ends the execution of the machining program. If the flag is not set to 1, that is, if the difference does not exceed the third threshold C3, the tool is not locked to the workpiece. Therefore, the CPU 61 sequentially reads the machining program lines and continuously executes the machining program until an end command is read.

  If it is determined in step S42 that the difference has exceeded the fourth threshold C4 (step S42: YES), the CPU 61 stops the thread cutting process or the extracting operation (step S46), and the process proceeds to step S44. Since the CPU 61 has already set 1 in the flag in step S40 (step S44: YES), the execution of the machining program is terminated (step S45). When the difference exceeds the fourth threshold C4, the tool is locked to the workpiece. Therefore, the thread cutting or extracting operation is immediately stopped, the other lines of the machining program are not read, and the execution of the machining program is terminated.

  When the difference exceeds the third threshold value and is equal to or less than the fourth threshold value, the degree to which the tool is locked to the workpiece is low. Therefore, the machine tool 100 according to the second embodiment completes the thread cutting process and the extraction operation. . Thereafter, the machining program is terminated without waiting for the end command to be read. When the difference exceeds the fourth threshold value, the degree to which the tool is locked to the workpiece is high, and therefore the machine tool 100 immediately stops the execution of the thread cutting process and the extraction operation and ends the machining program. Even if the tool is locked to the workpiece, an appropriate operation of the spindle is executed to prevent damage to the tool or the spindle. When the difference is less than or equal to the third threshold value, the possibility that the tool is locked to the workpiece is low, and therefore the normal thread cutting process is executed and the execution of the machining program is continued until the end command is read.

  The CPU 61 that executes S40 corresponds to a third determination unit. The CPU 61 that executes S42 corresponds to a fourth determination unit. Processing in which S40 is determined as YES and S42 is determined as NO, processing through S43 to S45 is equivalent to first end processing, processing in S42 is determined as YES, and processing through S46, S44, and S45 is second processing. It corresponds to processing. The CPU 61 that executes the first end process and the second end process corresponds to an end unit.

6 Spindle motor 30 Z-axis direction moving mechanism 51 Spindle 60 Control device 61 CPU
62 ROM
63 RAM
64 Storage Device 67 Reception Unit 68 Z-axis Sensor 69 Spindle Sensor 100 Machine Tool

Claims (5)

A spindle that mounts a tool, a moving mechanism that moves the spindle in the axial direction, a motor that rotates the spindle around an axis, and a plurality of commands that constitute a machining program are sequentially read, and the moving mechanism and the motor In a machine tool comprising: a control device that controls driving; a first detection unit that detects an axial position of the main shaft; and a second detection unit that detects a circumferential position of the main shaft.
The controller is
When the read command includes a thread cutting command for threading a workpiece with a tool, the circumferential position of the first spindle detected by the second detector, the second detected by the second detector Based on the circumferential position of the main shaft and the screw cutting command, the vertical position of the main shaft is calculated, and the calculated vertical position of the main shaft and the vertical direction of the main shaft detected by the first detection unit A determination unit for determining whether or not a difference between the position of the first position and the second position exceeds a predetermined threshold;
When the determination unit determines that the difference has exceeded the threshold value, after the execution of the screw cutting command is completed, the determination unit stops the first end process to end the execution of the machining program or the execution of the screw cutting command, A machine tool comprising: an end unit that executes any one of second end processes for ending execution of the machining program. The control device includes a setting unit configured to set execution of the first end process or the second end process,
The machine tool according to claim 1, wherein the end unit executes the first end process or the second end process according to a setting in the setting unit. The command includes an extraction command for extracting a tool from a screw hole formed in the workpiece,
The threshold includes a first threshold and a second threshold;
The determination unit
When executing the screw cutting command, a first determination unit that determines whether or not the difference exceeds the first threshold;
The machine tool according to claim 1, further comprising: a second determination unit configured to determine whether or not the difference exceeds the second threshold when the extraction command is executed. The threshold includes a third threshold and a fourth threshold greater than the third threshold;
The determination unit
A third determination unit for determining whether or not the difference exceeds the third threshold;
A fourth determination unit that determines whether or not the difference exceeds the fourth threshold,
When the third determination unit determines that the difference exceeds the third threshold and the fourth determination unit determines that the difference does not exceed the fourth threshold, the end unit is the first The end process is executed, and when the fourth determination unit determines that the difference exceeds the fourth threshold, the end unit executes the second end process. Machine Tools. A spindle for mounting a tool, a moving mechanism for moving the spindle in the axial direction, a motor for rotating the spindle around the axis, and a plurality of commands constituting a machining program are sequentially read, and the moving mechanism and the motor are driven. In a method for controlling a machine tool, comprising: a control device that controls the first spindle; a first detector that detects an axial position of the spindle; and a second detector that detects a circumferential position of the spindle.
When the read command includes a thread cutting command for threading the workpiece with a tool, the circumferential position of the first spindle detected by the second detector, the second detected by the second detector Based on the circumferential position of the main shaft and the screw cutting command, the vertical position of the main shaft is calculated, and the calculated vertical position of the main shaft and the vertical direction of the main shaft detected by the first detection unit are calculated. Determine whether the difference with the position exceeds a predetermined threshold,
When it is determined that the difference exceeds the threshold value, after the execution of the thread cutting command is completed, the first termination process for terminating the execution of the machining program or the execution of the screw cutting instruction is stopped, and the execution of the machining program is executed. One of the 2nd completion processing which completes is performed. The control method of the machine tool characterized by the above-mentioned.

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