JP6617474B2 - Numerical control device and control method - Google Patents

Description

  The present invention relates to a numerical control device and a control method.

  The numerical control device controls the operation of the machine tool. The machine tool disclosed in Patent Document 1 includes a spindle head, a spindle, and a tool changer. The spindle head is provided so as to be movable up and down along a column standing on the base, and supports the spindle in a rotatable manner. The tool is installed in a mounting hole provided at the tip of the spindle. The clamp shaft provided in the main shaft pulls and holds the tool mounted in the mounting hole with a spring force. The spindle head descends to the machining area of the work material. The tool rotates together with the main spindle, and performs machining such as drilling the work material. During the machining, the tool moves in a direction approaching the work material, and after cutting, moves in a direction away from the work material. The tool may bite the work piece during machining. When the tool is moved in a direction away from the work material in a state where the blade of the tool is caught on the work material, a tool omission occurs in which the tool comes off from the main shaft. Tool breakage can be detected by a tool breakage detector. The tool breakage detection device detects a tool omission by contacting the contact with the tool and detecting the rotation angle of the contact.

JP 2014-161974 A

  Since the tool breakage detecting device is fixed at a predetermined position of the machine tool, it is necessary to move the tool to the predetermined position for each processing. Therefore, the problem that the cycle time which processes a work material becomes long arises.

  An object of the present invention is to provide a numerical control device and a control method that can easily monitor tool removal.

A numerical control device according to a first aspect of the present invention includes a spindle head that can approach or separate from a table that supports a work material, a spindle provided rotatably on the spindle head, and a spring provided on the spindle. A clamp shaft that clamps a tool holder that holds a tool by the force of the spring to the main shaft, a motor that drives the main shaft head in a direction toward and away from the table, and a motor connected to the motor. In a numerical control apparatus for controlling a machine tool including an encoder for detecting drive information of the machine tool, the spindle head is moved to the machine origin side in a machining area on the table side from the machine origin of the machine tool. And when the table does not move, the first acquisition means for acquiring the drive information from the encoder at predetermined time intervals, and the first acquisition means at every predetermined time interval Based on the obtained drive information, first calculation means for calculating first difference information, which is a difference between previous drive information and current drive information, and the first difference information calculated by the first calculation means are stored in advance. If the first determination means determines that there is a change exceeding the first threshold in the first difference information, a tool omission occurs in the spindle. And a first output means for outputting abnormality information indicating the occurrence . The clamp shaft clamps the tool holder with a spring force. During machining of the workpiece, if the spindle head rises with the workpiece biting on the tool and a force greater than the spring force is applied to the tool, the tool holder may come off from the spindle. Since a force different from the normal time is applied to the clamp shaft when the tool is missing, the information acquired from the encoder of the motor that drives the spindle head to move up and down changes differently from the normal time. The numerical control device acquires information from the motor encoder when the spindle head is raised in the machining area, and outputs abnormal information by assuming that a tool missing has occurred when the acquired information has a change exceeding a threshold value. Therefore, the numerical control device can detect missing tools without using other monitoring devices such as an image recognition device and a tool breakage detection device. The numerical control device can eliminate the need for measurement preparation and the like necessary when using another monitoring device. Costs are not high because no other monitoring device is used. Since the numerical control device does not need to redo the measurement preparation for each machining, it is possible to easily and constantly monitor tool missing even in continuous machining. The numerical control device acquires motor drive information from the encoder, and can determine whether a tool is missing by monitoring changes in the time difference of the acquired drive information.

A numerical control device according to a second aspect includes a spindle head that can approach or separate from a table that supports a work material, a spindle provided rotatably on the spindle head, a spring provided on the spindle, and the spring A clamp shaft that clamps a tool holder that holds a tool by the force of the spindle to the spindle, a motor that drives the spindle head in a direction toward and away from the table, and a drive information of the motor connected to the motor In a numerical control apparatus for controlling a machine tool provided with an encoder for detecting the position of the machine tool, the spindle head is moved to the machine origin side in a machining area on the table side with respect to the machine origin of the machine tool, and When the table does not move, a first acquisition unit that acquires the drive information from the encoder every predetermined time, and the first acquisition unit acquires the predetermined time Second acquisition means for acquiring command information which is input information of the motor corresponding to each of the drive information, the drive information acquired by the first acquisition means at every predetermined time, and the second acquisition means A second calculation unit that calculates second difference information that is difference information from the command information acquired, and a change that exceeds a second threshold stored in advance in the second difference information calculated by the second calculation unit. Second determination means for determining whether or not there is abnormality information indicating that a missing tool has occurred in the spindle when the second determination means determines that the second difference information has a change exceeding the second threshold. And a second output means for outputting . The numerical control apparatus acquires motor drive information from the encoder and command information that is input information corresponding to the motor output result in the drive information. The numerical control device can detect a missing tool by monitoring a change in the difference between the drive information and the command information.

A numerical control device according to a third aspect of the present invention includes a spindle head capable of approaching or moving away from a table supporting a work material, a spindle provided rotatably on the spindle head, a spring provided on the spindle, and the spring A clamp shaft that clamps a tool holder that holds a tool by the force of the spindle to the spindle, a motor that drives the spindle head in a direction toward and away from the table, and a drive information of the motor connected to the motor In a numerical control apparatus for controlling a machine tool provided with an encoder for detecting the position of the machine tool, the spindle head is moved to the machine origin side in a machining area on the table side with respect to the machine origin of the machine tool, and When the table does not move, a first acquisition unit that acquires the drive information from the encoder every predetermined time, and the first acquisition unit acquires the predetermined time Third acquisition means for acquiring command information which is input information of the motor corresponding to each of the drive information, and previous drive information based on the drive information acquired by the first acquisition means at every predetermined time And third calculation means for calculating third difference information, which is the difference between the current drive information and the third difference information calculated by the third calculation means to determine whether there is a change exceeding a first threshold stored in advance. A third determination unit and a fourth difference information that is information on a difference between the drive information acquired by the first acquisition unit every predetermined time and the command information acquired by the third acquisition unit. Four calculating means, fourth determining means for determining whether the fourth difference information calculated by the fourth calculating means has a change exceeding a second threshold stored in advance, and the third determining means is the third difference information. Changes exceeding the first threshold If it is determined that that, or when the fourth determining means determines that change exceeding the second threshold value is present in the fourth difference information, it outputs abnormality information indicating that the missing tool is generated in the main shaft And a third output means . The numerical control device monitors the difference information between the current information and the previous information with respect to the drive information acquired every predetermined time, and the drive information acquired every predetermined time and the command information corresponding to the drive information Since the difference information is monitored, the accuracy of the tool missing determination can be improved.

According to a fourth aspect of the present invention, in addition to the configuration of the invention according to any one of the first to third aspects, the drive information is torque information of the motor. Since a large force is applied to the clamp shaft when the tool is removed, a large change occurs in the torque of the motor that drives the spindle head to move up and down. Therefore, the numerical control device can detect the tool omission accurately and promptly by determining whether there is a change exceeding the threshold based on the torque information of the motor.

According to a fifth aspect of the present invention, there is provided a control method comprising: a spindle head capable of approaching or moving away from a table supporting a work material; a spindle provided rotatably on the spindle head; a spring provided on the spindle; A clamp shaft that clamps a tool holder that holds a tool by force on the spindle, a motor that drives the spindle head in a direction toward and away from the table, and a motor that is connected to the motor. In a control method of a numerical control device for controlling a machine tool provided with an encoder for detection, the spindle head is moved to the machine origin side in a machining area on the table side with respect to the machine origin of the machine tool, And when the table does not move, a first acquisition step of acquiring the drive information from the encoder every predetermined time, and the predetermined time in the first acquisition step Based on the drive information acquired in step 1, the first calculation step for calculating the first difference information, which is the difference between the previous drive information and the current drive information, and the first difference information calculated in the first calculation step in advance A first determination step for determining whether there is a change exceeding the stored first threshold value, and if it is determined in the first determination step that the first difference information has a change exceeding the first threshold value, a tool omission in the spindle And a first output step for outputting abnormality information indicating that the occurrence has occurred . The numerical control device can obtain the effect of the first aspect by performing the above-described steps.
According to a sixth aspect of the present invention, there is provided a spindle head capable of approaching or moving away from a table supporting a work material, a spindle provided rotatably on the spindle head, a spring provided on the spindle, A clamp shaft that clamps a tool holder that holds a tool by force on the spindle, a motor that drives the spindle head in a direction toward and away from the table, and a motor that is connected to the motor. In a control method of a numerical control device for controlling a machine tool provided with an encoder for detection, the spindle head is moved to the machine origin side in a machining area on the table side with respect to the machine origin of the machine tool, And when the table does not move, a first acquisition step of acquiring the drive information from the encoder every predetermined time, and the predetermined time in the first acquisition step A second acquisition step of acquiring command information that is input information of the motor corresponding to each of the drive information acquired at a time, the drive information acquired at the predetermined time in the first acquisition step, and the first A second calculation step for calculating second difference information, which is difference information from the command information acquired in the second acquisition step, and a second threshold value stored in advance in the second difference information calculated in the second calculation step. When it is determined that there is a change exceeding the second threshold value in the second difference information in the second determination step for determining whether there is a change exceeding, it indicates that a tool missing has occurred in the spindle. And a second output step for outputting abnormality information. The numerical control device can obtain the effect described in claim 2 by performing the above steps.

1 is a perspective view of a machine tool 1. FIG. 3 is a longitudinal sectional view around the spindle head 7. The longitudinal cross-sectional view inside the main axis | shaft 9. FIG. Explanatory drawing of a process area | region and a tool exchange area | region. FIG. 3 is a block diagram showing an electrical configuration of the machine tool 1 and the numerical control device 30. The flowchart of a tool omission determination process (1st embodiment). The chart which shows change of torque monitor value (fast-forward override 100%). The chart which shows change of torque monitor value (fast-forward override α). The chart which shows the change of the time difference (fast-forward override 100%) of a torque monitor value. The chart which shows the change of the time difference (fast-forward override alpha) of a torque monitor value. The flowchart of a tool omission determination process (2nd embodiment). The chart which shows the change (fast-forward override 100%) of the torque command value and torque monitor value at the time of normal rise. The chart which shows the change (fast-forward override 100%) of the torque command value and torque monitor value at the time of tool omission occurrence. The chart which shows change (fast-forward override α) of a torque command value and a torque monitor value at the time of normal rise. The chart which shows the change (fast-forward override α) of the torque command value and the torque monitor value at the time of tool omission occurrence. The chart which shows the change (fast-forward override 100%) of the difference of the torque command value and torque monitor value at the time of a normal rise and the time of tool missing. The chart which shows the change (fast-forward override alpha) of the difference of the torque command value and torque monitor value at the time of a normal rise and the time of tool missing. The flowchart of a tool omission determination process (3rd embodiment).

  A first embodiment of the present invention will be described with reference to the drawings. In the following description, left, right, front, back, and top and bottom indicated by arrows in the figure are used. The left-right direction, the front-rear direction, and the vertical direction of the machine tool 1 are an X-axis direction, a Y-axis direction, and a Z-axis direction, respectively. A machine tool 1 shown in FIG. 1 is a machine that rotates a tool 4 mounted on a spindle 9 and performs cutting on a work material held on the upper surface of a table 13. The numerical control device 30 (see FIG. 5) controls the operation of the machine tool 1.

  The structure of the machine tool 1 will be described with reference to FIGS. The machine tool 1 includes a base 2, a column 5, a spindle head 7, a spindle 9, a table device 10, a tool changer 20, a control box 6, an operation panel 15 (see FIG. 5), and the like. The base 2 is a substantially rectangular parallelepiped metal base. The column 5 is erected on the upper rear side of the base 2.

  The spindle head 7 moves up and down in the Z-axis direction by a Z-axis moving mechanism provided on the front surface of the column 5. The Z-axis moving mechanism includes a pair of Z-axis linear guides (not shown), a Z-axis ball screw 26 (see FIG. 2), and a Z-axis motor 51 (see FIG. 5). The Z-axis linear guide extends along the Z-axis direction and guides the spindle head 7 in the Z-axis direction. The Z-axis ball screw 26 is disposed between a pair of Z-axis linear guides. The upper bearing portion 27 and the lower bearing portion (not shown) support the Z-axis ball screw 26 rotatably. The spindle head 7 includes a nut 29 on the back surface. The nut 29 is screwed into the Z-axis ball screw 26. The Z-axis motor 51 rotates the Z-axis ball screw 26 in the forward and reverse directions. Therefore, the spindle head 7 moves in the Z-axis direction together with the nut 29. The spindle head 7 includes a spindle motor 52 at the top. The main shaft 9 is rotatably provided inside the main shaft head 7. The main shaft 9 has a mounting hole 9B at its lower end (front end). The mounting hole 9B is located below the spindle head 7. The spindle 9 is mounted with the tool holder 17 in the mounting hole 9 </ b> B and is rotated by driving the spindle motor 52. The tool holder 17 holds the tool 4.

  The table device 10 includes a Y-axis moving mechanism (not shown), a Y-axis table 12, an X-axis moving mechanism (not shown), a table 13, and the like. The Y-axis moving mechanism is provided on the front surface of the base 2 and includes a pair of Y-axis rails, a Y-axis ball screw, a Y-axis motor 54 (see FIG. 5), and the like. The pair of Y-axis rails and the Y-axis ball screw extend along the Y-axis direction. The pair of Y-axis rails guides the Y-axis table 12 on the upper surface in the Y-axis direction. The Y-axis table 12 is formed in a substantially rectangular parallelepiped shape, and includes a nut (not shown) on the bottom outer surface. The nut is screwed onto the Y-axis ball screw. When the Y-axis motor 54 rotates the Y-axis ball screw, the Y-axis table 12 moves along the pair of Y-axis rails together with the nut. Therefore, the Y-axis moving mechanism supports the Y-axis table 12 so as to be movable in the Y-axis direction.

  The X-axis moving mechanism is provided on the upper surface of the Y-axis table 12, and includes a pair of X-axis rails (not shown), an X-axis ball screw (not shown), an X-axis motor 53 (see FIG. 5), and the like. The X-axis rail and the X-axis ball screw extend along the X-axis direction. The table 13 is formed in a rectangular plate shape in plan view and provided on the upper surface of the Y-axis table 12. The table 13 includes a nut (not shown) at the bottom. The nut is screwed into the X-axis ball screw. When the X-axis motor 53 rotates the X-axis ball screw, the table 13 moves along the pair of X-axis rails together with the nut. Therefore, the X-axis moving mechanism supports the table 13 so as to be movable in the X-axis direction. Therefore, the table 13 can be moved on the base 2 in the X-axis direction and the Y-axis direction by the Y-axis moving mechanism, the Y-axis table 12, and the X-axis moving mechanism.

  The tool changer 20 is provided on the front side of the spindle head 7 and includes a disk-shaped tool magazine 21. The tool magazine 21 is provided with a plurality of grip arms 90 radially on the outer periphery. The grip arm 90 holds the tool holder 17. The tool changer 20 drives the magazine motor 55 to rotate the tool magazine 21 and positions the tool 4 indicated by the tool change command at the tool change position. The tool change command is commanded by the NC program. The tool change position is the lowest position of the tool magazine 21. The tool changer 20 is in the tool change position with the tool 4 currently mounted on the spindle 9 by the raising / lowering operation of the spindle head 7 and the swinging action of the grip arm 90 in a tool change area (see FIG. 4) described later. Replace and replace the next tool.

  The control box 6 is attached to the back side of the column 5 and stores the numerical control device 30 (see FIG. 5). The numerical control device 30 controls the Z-axis motor 51, the main-axis motor 52, the X-axis motor 53, and the Y-axis motor 54, respectively, so that the work material held on the table 13 and the tool 4 mounted on the main shaft 9 are relative to each other. By moving, various processing is performed on the work material. The various types of processing include, for example, drilling using a drill, a tap or the like, side processing using an end mill, a milling cutter, or the like.

  The operation panel 15 is provided, for example, on the outer wall of a cover (not shown) that covers the machine tool 1. The operation panel 15 includes an input unit 24 (see FIG. 5) and a display unit 25 (see FIG. 5). The input unit 24 receives input of various information, operation instructions, etc., and outputs the input information to the numerical controller 30 described later. The display unit 25 displays various screens, abnormality information, and the like based on commands from the numerical controller 30 described later.

  The internal structure of the spindle head 7 and the spindle 9 will be described with reference to FIGS. The spindle head 7 rotatably supports the spindle 9 inside the lower front part. The main shaft 9 has a rotation axis in the vertical direction. The main shaft 9 is connected to a drive shaft extending below the main shaft motor 52 via a coupling 23. Therefore, the main shaft 9 rotates by driving the main shaft motor 52. As shown in FIG. 3, the main shaft 9 includes a shaft hole 9A, a mounting hole 9B, a space 9C, a lower sliding hole 9D, a clamp shaft 81, and a spring 82. The shaft hole 9 </ b> A passes through the center of the main shaft 9. As described above, the mounting hole 9 </ b> B is provided at the tip (lower end) of the main shaft 9. The tool holder 17 is mounted in the mounting hole 9B. The tool holder 17 holds the tool 4 on one end side, and includes a taper mounting portion 17A and a pull stud 17B on the other end side. The taper mounting portion 17A has a conical shape. The pull stud 17B protrudes in the axial direction from the top of the taper mounting portion 17A. The taper mounting portion 17A is mounted in close contact with the mounting hole 9B of the main shaft 9. The space 9C is provided continuously above the mounting hole 9B. The lower sliding hole 9D is provided continuously between the lower end portion of the shaft hole 9A and the space 9C.

  The clamp shaft 81 is provided so as to be inserted into the shaft hole 9A and movable in the vertical direction. The clamp shaft 81 includes a pin support portion 81A, a shaft portion 81B, and a holder gripping portion 81C. The pin support portion 81A has a cylindrical shape, is positioned at the upper end of the clamp shaft 81, and supports a pin 58 described later. The diameter of the pin support portion 81A is slightly smaller than the diameter of the shaft hole 9A of the main shaft 9. The shaft portion 81B has a cylindrical shape and extends downward from the pin support portion 81A. The diameter of the shaft portion 81B is smaller than the diameter of the pin support portion 81A. The holder gripping portion 81C is located at the lower end of the shaft portion 81B and has a plurality of steel balls (not shown). The spring 82 is inserted into the shaft hole 9A, and the upper end of the spring 82 is engaged with the pin support portion 81A. The clamp shaft 81 is always urged upward by the spring force Q1. When the clamp shaft 81 moves downward against the spring force Q1 of the spring 82, the spring 82 contracts and the holder gripping portion 81C comes out of the lower sliding hole 9D into the space 9C, and the pull stud of the tool holder 17 Release the 17B clamp. The force Q2 required when the clamp shaft 81 is pushed down to release the clamp of the pull stud 17B is about 3000 N, for example. When the clamp shaft 81 moves upward from the lower position, the holder gripping portion 81C moves from the space 9C to the lower sliding hole 9D, and the steel ball is drawn inward to clamp the pull stud 17B. Therefore, the clamp shaft 81 holds the tool holder 17 in a state of being pulled upward by the spring 82.

  As shown in FIG. 2, the spindle head 7 includes a lever 60 inside the rear upper part. The lever 60 is substantially L-shaped and swings around the support shaft 61. The spindle 61 is fixed in the spindle head 7. The lever 60 includes a vertical lever 63 and a horizontal lever 62. The longitudinal lever 63 extends obliquely upward from the support shaft 61 to the column 5 side, bends upward at the intermediate portion 65, and further extends upward. The lateral lever 62 extends substantially horizontally from the support shaft 61 to the front of the column 5. The tip of the lateral lever 62 can be engaged from above with a pin 58 projecting perpendicular to the clamp shaft 81. The vertical lever 63 includes a plate cam body 66 on the back surface of the upper end portion. The plate cam body 66 has a cam surface on the column 5 side. The cam surface of the plate cam body 66 can be brought into and out of contact with a cam follower 67 fixed to the upper bearing portion 27. The cam follower 67 slides on the cam surface of the plate cam body 66. A tension coil spring (not shown) is elastically provided between the longitudinal lever 63 and the spindle head 7. When the lever 60 is viewed from the right side, the tension coil spring constantly urges the lever 60 clockwise. Therefore, the lever 60 always releases the downward pressing of the pin 58 by the lateral lever 62.

  With reference to FIG. 2, the operation of detaching the tool holder 17 from the mounting hole 9 </ b> B of the main shaft 9 will be described. The spindle head 7 ascends while the taper mounting portion 17A of the tool holder 17 is mounted in the mounting hole 9B of the spindle 9. The plate cam body 66 provided on the lever 60 slides in contact with the cam follower 67. When the cam follower 67 slides along the cam shape of the plate cam body 66, the lever 60 rotates counterclockwise around the support shaft 61 when viewed from the right side. The lateral lever 62 engages with the pin 58 from above and presses the clamp shaft 81 downward. The clamp shaft 81 urges the holder gripping portion 81 </ b> C downward against the spring force Q <b> 1 of the spring 82. The holder gripping portion 81 </ b> C releases the clamp of the pull stud 17 </ b> B of the tool holder 17. The tool holder 17 can be removed from the mounting hole 9 </ b> B of the main shaft 9.

  When the tool holder 17 is mounted in the mounting hole 9B of the spindle 9, the spindle head 7 is lowered with the taper mounting portion 17A of the tool holder 17 inserted into the mounting hole 9B of the spindle 9. When the plate cam body 66 provided on the lever 60 slides on the cam follower 67, the lever 60 rotates clockwise around the support shaft 61 when viewed from the right side. Therefore, the lateral lever 62 is separated from the pin 58 to release the downward pressing of the clamp shaft 81. Since the clamp shaft 81 releases the downward bias of the holder gripping portion 81C and moves upward by the spring force of the spring 82, the holder gripping portion 81C pulls the pull stud 17B upward. Therefore, the mounting of the taper mounting portion 17A of the tool holder 17 in the mounting hole 9B of the main shaft 9 is completed.

  The tool missing detection range will be described with reference to FIG. Tool removal is a phenomenon in which the taper mounting portion 17A of the tool holder 17 is removed from the mounting hole 9B of the main shaft 9. In this embodiment, the machine origin of the Z axis is referred to as the Z axis origin. The machine origin is a position where the machine coordinates of the X axis and the Y axis are zero, and the machine coordinate of the Z axis is a position at which the work material can be machined. The area closer to the table 13 (see FIG. 1) than the Z-axis origin is a machining area, and the area opposite to the machining area with respect to the Z-axis origin is a tool change area. The machining area is an area for performing a machining operation of the work material. The tool change area is an area for performing tool change by the tool changer 20. In the present embodiment, the machining area is set as a tool missing detection range. As will be described later, the numerical control device 30 detects tool removal when the spindle head 7 is raised in the Z-axis direction (Z-axis rise) in the tool removal detection range, and outputs abnormality information when tool removal is detected.

  With reference to FIG. 5, the electrical configuration of the numerical controller 30 and the machine tool 1 will be described. The numerical control device 30 and the machine tool 1 include a CPU 31, a ROM 32, a RAM 33, a storage device 34, an input / output unit 35, drive circuits 51A to 55A, and the like. The CPU 31 performs overall control of the numerical control device 30. The ROM 32 stores various programs including a main program and a tool missing determination program. The main program executes main processing. The main process reads the NC program line by line and executes various operations. The NC program is composed of a plurality of lines including various control commands, and controls various operations including axis movement of the machine tool 1, tool change, etc. in line units. The tool missing determination program executes a tool missing determination process (see FIG. 6) described later. The RAM 33 temporarily stores various information. The storage device 34 is non-volatile and stores various data such as an NC program and a threshold value described later. The CPU 31 can store, in the storage device 34, an NC program read by an external input in addition to the NC program input by the operator through the input unit 24 of the operation panel 15.

  The drive circuit 51A is connected to the Z-axis motor 51 and the encoder 51B. The drive circuit 52A is connected to the spindle motor 52 and the encoder 52B. The drive circuit 53A is connected to the X-axis motor 53 and the encoder 53B. The drive circuit 54A is connected to the Y-axis motor 54 and the encoder 54B. The drive circuit 55A is connected to a magazine motor 55 that drives the tool magazine 21 and an encoder 55B. The Z-axis motor 51, the main shaft motor 52, the X-axis motor 53, the Y-axis motor 54, and the magazine motor 55 are all servo motors. The drive circuits 51A to 55A receive commands from the CPU 31 and output drive currents to the corresponding motors 51 to 55, respectively. The drive circuits 51A to 55A receive encoder information (an example of drive information of the present invention) from the encoders 51B to 55B, and perform feedback control of position and speed. The encoder information includes various information such as a torque monitor value, speed, position, and position deviation. The encoder information can be read by the CPU 31 via the input / output unit 35. The input / output unit 35 is connected to the input unit 24 and the display unit 25 of the operation panel 15, respectively.

  In addition to the input unit 24 and the display unit 25, the operation panel 15 includes a rapid feed override switch, a cutting feed override switch, a spindle override switch, and the like (not shown). The rapid feed override switch is a switch for overriding the positioning operation of the spindle 9. For example, a plurality of override speeds may be set, and the user may switch among them. The cutting feed override switch is a switch for overriding the cutting feed operation. The ratio is 0-200%. The spindle override switch is a switch for overriding the spindle rotation. The ratio is 50 to 200%.

  With reference to FIG. 3, the relationship between the mechanism of tool removal occurrence and the torque of the Z-axis motor 51 will be described. The Z-axis lifting force Z1 of the spindle head 7 is caused by the torque of the Z-axis motor 51. When the Z-axis raising force Z1 is larger than the gravity Z2 of the spindle head 7, the spindle head 7 rises. For example, after the drilling of the work material by the tool 4 is completed, the tool 4 sometimes bites the work material strongly. Even if the numerical control device 30 tries to raise the spindle head 7 to the Z-axis in this state, there are times when the tool 4 cannot be pulled out from the work material. When the spindle head 7 is raised while the position of the tool 4 is fixed by the work material, the tool holder 17 pulls the clamp shaft 81 downward against the spring force Q1 of the spring 82 via the holder gripping portion 81C. A force Q2 is applied to the spindle head 7 to try to contract the spring 82. The spindle head 7 is subjected to the force Q2 and the force of gravity Z2 of the spindle head 7. When the Z-axis lifting force Z1 becomes larger than the combined force of gravity Z2 and force Q2 of the spindle head 7, tool removal occurs. After the torque of the Z-axis motor 51 increases at the time of tool removal, the aforementioned force Q2 suddenly disappears, so that the spring 82 expands and contracts and the change in torque becomes severe. Therefore, the numerical control apparatus 30 can detect the tool missing in the machining area with high accuracy by executing a tool missing determining process (see FIG. 6) described later.

  The tool missing determination process will be described with reference to FIGS. When starting the machine tool 1 and executing the NC program, the CPU 31 reads out the tool missing determination program from the ROM 32 and executes this processing at predetermined intervals. First, the CPU 31 determines whether or not the spindle head 7 is raised (whether the Z-axis is raised) (S1). When the spindle head 7 does not rise (S1: NO), the CPU 31 ends this process. When the spindle head 7 moves up (S1: YES), the CPU 31 determines whether the Z-axis coordinate of the spindle head 7 is equal to or less than the Z-axis origin (S2). When the Z-axis coordinate is above the Z-axis origin (S2: NO), as shown in FIG. 4, the spindle head 7 is located in the tool change area and is outside the tool missing detection range. Exit. In the main process, the CPU 31 stores in the RAM 33 that the Z-axis is raised if the operation to be executed is the Z-axis rise. When determining whether or not the Z-axis is rising, the CPU 31 determines whether or not it is stored in the RAM 33 that the Z-axis is rising. As another determination method, the value of the Z-axis coordinate may be stored in the RAM 33, and it may be determined whether or not the Z-axis is raised from the previously stored Z-axis coordinate value and the currently stored Z-axis coordinate value.

  When the Z-axis coordinate is below the Z-axis origin (S2: YES), the spindle head 7 is located within the tool missing detection range, so the CPU 31 drives the X-axis and Y-axis drive axes of the spindle head 7, respectively. It is determined whether or not is moving (S3). When at least one of the X-axis and the Y-axis moves (S3: NO), the Z-axis rise is a movement including the X-axis and the Y-axis, and is different from the condition for detecting tool removal, so the CPU 31 performs this process. finish. If neither the X-axis nor the Y-axis is moving (S3: YES), the CPU 31 acquires a torque monitor value as encoder information of the Z-axis motor 51 from the encoder 51B every predetermined time (for example, 0.5 msec). (S4). If the operation to be executed is X-axis movement or Y-axis movement in the main process, the CPU 31 stores in the RAM 33 that the X-axis movement or Y-axis movement is performed. Therefore, the determination in S3 is made based on the information stored in the RAM 33.

  The chart shown in FIG. 7 shows the change in the torque monitor value when the spindle head 7 is normally raised and when the tool is missing, at 100% rapid traverse override. (A) shows the change in the torque monitor value both during the normal rise and when the tool is missing, and (b) shows the change in the torque monitor value only during the normal rise. The rapid feed override 100% is, for example, 56000 mm / min. The horizontal axis represents time (msec), and the vertical axis represents the torque monitor value (× 0.1%). A dotted line indicates a change in the torque monitor value when the spindle head 7 is normally raised, and a solid line indicates a change in the torque monitor value when the tool is missing. In the process of raising the spindle head 7 from the machining position of the work material to a predetermined position, t1 to t2 are acceleration regions, t2 to t3 are constant speed regions, and t3 to t4 are deceleration regions. Therefore, the spindle head 7 rises while accelerating in the acceleration range, rises at the maximum speed in the constant speed range, and stops at a predetermined position while decelerating in the deceleration range. At the time of normal increase, the torque monitor value, for example, increases to about 2800 (× 0.1%) in the acceleration range, then decreases to about 700 (× 0.1%), and about 700 (×× in the constant speed range). 0.1%), and decreases to about −1500 (× 0.1%) in the deceleration region, and then increases to about 500 (× 0.1%) and maintains a constant value.

  When a tool is missing, the torque monitor value waveform changes with respect to the normal rise. For example, in the acceleration region, the point p1 in the waveform of the torque monitor value is a portion where the inclination is changed, and at the time when the spindle head 7 is raised while the blade of the tool 4 is biting the work material. It seems to correspond. The portion p2 in the waveform of the torque monitor value is a portion where the inclination changes in small increments, and the load of the Z-axis motor 51 fluctuates because the tool holder 17 comes out of the mounting hole 9B of the main shaft 9 and the spring 82 expands and contracts. It seems to correspond to the time to do. Therefore, the numerical control device 30 may be able to detect the occurrence of tool omission based on the change in the waveform of the torque monitor value. In order to determine whether or not the change in the waveform is an abnormal value, a method is generally performed in which a threshold value is set. However, since the torque monitor value changes with the rising speed of the spindle head 7, the threshold value is set. It is difficult to set.

  The chart shown in FIG. 8 shows the change in the torque monitor value at the time of normal rise and rapid tool override α. (A) shows the change in the torque monitor value both during the normal rise and when the tool is missing, and (b) shows the change in the torque monitor value only during the normal rise. The torque monitor value at the time of normal ascent is indicated by a dotted line only in the vicinity of the acceleration region and the deceleration region, and other portions are indicated by a solid line. The rapid feed override α is, for example, 10,000 mm / min. In the process of raising the spindle head 7 from the machining position of the work material to a predetermined position, t5 to t6 are acceleration regions, t6 to t7 are constant speed regions, and t7 to t8 are deceleration regions. Even in the rapid traverse override α, the waveform of the torque monitor value changes when the tool is missing or when it is normally raised. For example, in the acceleration region, the point p3 in the waveform of the torque monitor value is a portion where the inclination changes, and corresponds to the time when the spindle head 7 is raised while the blade of the tool 4 is biting the work material. It seems to be. The portion p4 in the waveform of the torque monitor value is a portion where the inclination changes in small increments, and the load of the Z-axis motor 51 fluctuates because the tool holder 17 comes out of the mounting hole 9B of the main shaft 9 and the spring 82 expands and contracts. It seems to correspond to the time to do. As a result of comparison with the chart shown in FIG. 7, it can be seen that the torque monitor value also changes when the rising speed of the spindle head 7 changes. Therefore, since it is difficult to set a threshold value for the change in the torque monitor value, the CPU 31 continues to execute the following processing.

  As shown in FIG. 6, the CPU 31 calculates a time difference between torque monitor values (S5). The time difference is a difference between the torque monitor value acquired last time and the torque monitor value acquired this time. Since this embodiment acquires a torque monitor value every 0.5 msec, CPU31 calculates the difference of the torque monitor value for 0.5 msec. The chart shown in FIG. 9 shows the change in the time difference between the torque monitor values when the normal rise and the tool removal occur when the rapid traverse override is 100%. The horizontal axis represents time (msec), and the vertical axis represents the torque monitor value (× 0.1%). (A) shows the change in the difference between the torque monitor values at both the normal rise and when the tool is missing, and (b) shows the change in the difference between the torque monitor values only at the normal rise. A dotted line indicates a change in the time difference of the torque monitor value when the spindle head 7 is normally raised, and a solid line indicates a change in the time difference of the torque monitor value when the tool is missing. The change in the time difference at the time of tool occlusion has a plurality of large peaks in the vicinity of 1950 to 2000.0 (msec) with respect to the change in the time difference at the normal rise.

  The chart shown in FIG. 10 shows the change in the time difference between the torque monitor values when the rapid feed override α is normally raised and when the tool is missing. (A) shows the change of the time difference of the torque monitor value at the time of tool omission, and (b) shows the change of the time difference of the torque monitor value at the time of normal increase. The change in the time difference when the tool omission occurs has a plurality of large peaks in the vicinity of 1700 to 1900.0 (msec) with respect to the change in the time difference during normal ascent. Therefore, it can be seen that the change in the time difference of the torque monitor does not depend on the rising speed of the spindle head 7 and the same tendency is seen. Therefore, according to the present embodiment, it is possible to determine whether a tool is missing by providing a threshold value for the time difference information of the torque monitor value. As shown in FIGS. 9 and 10, the present embodiment can provide, for example, two threshold values (100 and −100) for the time difference between the torque monitor values.

  As shown in FIG. 6, the CPU 31 determines whether or not the calculated time difference exceeds a threshold value (S6). When the time difference exceeds the threshold value (S6: YES), there is a high possibility that tool removal has occurred, so the CPU 31 outputs abnormality information (S7). When the abnormality information is output, for example, the CPU 31 stops the ascent of the spindle head 7 and displays an error on the display unit 25. Therefore, the numerical controller 30 can promptly notify the operator that a tool omission has occurred. The operator can respond quickly to tool removal. After outputting the abnormality information, the CPU 31 ends this process.

  When the time difference does not exceed the threshold value (S6: NO), no tool removal has occurred, so the CPU 31 determines whether or not the Z-axis raising of the spindle head 7 has been completed (S8). When the Z-axis ascending has not ended (S8: NO), the CPU 31 returns to S2, continuously acquires the torque monitor value, calculates the time difference between the torque monitor values, and monitors the tool removal. When the Z-axis rise is finished (S8: YES), the CPU 31 finishes this process.

  As described above, the numerical controller 30 of the first embodiment controls the operation of the machine tool 1. The machine tool 1 includes a spindle head 7, a spindle 9, a clamp shaft 81, a spring 82, a Z-axis motor 51, and an encoder 51B. The spindle head 7 can approach or leave the table 13 that supports the work material. The main shaft 9 is rotatably provided on the main shaft head 7. The spring 82 is provided inside the main shaft 9. The clamp shaft 81 clamps the tool holder 17 to the main shaft 9 by the force of the spring 82. The Z-axis motor 51 drives the spindle head 7 in a direction to approach and separate from the table 13. The encoder 51B is connected to the Z-axis motor 51 and detects encoder information of the Z-axis motor 51. The CPU 31 of the numerical control device 30 obtains a torque monitor value from the encoder 51B every predetermined time when the spindle head 7 is moved to the machine origin side in the machining area on the table 13 side from the machine origin of the machine tool 1. get. Based on the torque monitor value acquired every predetermined time, the CPU 31 determines that there is a change exceeding a threshold stored in advance, thereby determining that a tool removal that causes the tool holder 17 to come off from the spindle 9 has occurred. When there is a change exceeding the threshold, the CPU 31 stops the movement of the spindle head 7 and outputs abnormality information to the display unit 25.

  The numerical control device 30 can constantly monitor the missing tool by comparing the change in the drive information acquired from the encoder 51B of the Z-axis motor 51 with the threshold value when the spindle head 7 is raised in the machining area. Therefore, since the numerical control device 30 does not require another monitoring device such as a tool breakage detection device, it does not require time and effort for measurement preparation and the cost does not increase. In the present invention, it is not necessary to move the tool for detecting tool breakage. Therefore, the numerical controller 30 can reduce the processing cycle time.

  The CPU 31 of the above embodiment calculates the time difference between the previous torque monitor value and the current torque monitor value based on the torque monitor value acquired every predetermined time, and determines whether the calculated time difference exceeds the threshold value. When the CPU 31 determines that there is a change in the time difference that exceeds the threshold value, it determines that tool removal has occurred. The numerical control device 30 can quickly and accurately determine tool removal by monitoring changes in the time difference of the monitor torque value.

In the above description, the Z-axis motor 51 is an example of the motor of the present invention. The spring 82 is an example of the spring of the present invention. The encoder information is an example of drive information of the present invention. CPU31 which performs the process of S4 of FIG. 6 is an example of a 1st acquisition means. The CPU 31 that executes the process of S7 is an example of the first output means of the present invention. CPU31 which performs the process of S5 is an example of the 1st calculation means of this invention. CPU31 which performs the process of S6 is an example of the 1st judgment means of this invention.
A plurality of threshold values may be provided corresponding to the rotation speed of the Z-axis motor 51. In this case, the CPU 31 can determine whether the tool is missing only from the torque monitor value detected this time.

  A second embodiment of the present invention will be described with reference to FIGS. The second embodiment is a modification of the first embodiment. In the second embodiment, the difference between the torque monitor value and the torque command value is calculated, and when the difference exceeds a threshold value, it is considered that a tool missing has occurred, and abnormality information is output. The numerical control device of the second embodiment has the same configuration as that of the first embodiment, and executes the tool missing determination process shown in FIG. The tool omission determination process of the second embodiment will be described with a focus on the different parts since the processes after S4 are partially different from those of the first embodiment.

  The tool missing determination process will be described with reference to FIG. As in the first embodiment, when the spindle head 7 moves up to the Z axis in the machining area (S1: YES, S2: YES, S3: YES), the CPU 31 performs torque as encoder information of the Z axis motor 51 from the encoder 51B. A monitor value is acquired every predetermined time (for example, 0.5 msec) (S4). Subsequently, the CPU 31 acquires a torque command value (S11). The torque command value corresponds to the torque monitor value acquired in the process of S4, and is command information input to the drive circuit 51A by the CPU 31 to drive the Z-axis motor 51.

  The chart shown in FIG. 12 shows changes in the torque command value and the torque monitor value when the spindle head 7 is normally raised when the rapid traverse override is 100%. The horizontal axis represents time (msec), and the vertical axis represents the torque monitor value (× 0.1%). (A) shows a change in the torque monitor value, and (b) shows a change in the torque command value. A dotted line indicates a change in the torque command value, and a solid line indicates a change in the torque monitor value. In the process of raising the spindle head 7 from the machining position of the work material to a predetermined position, t9 to t10 are acceleration regions, t10 to t11 are constant speed regions, and t11 to t12 are deceleration regions. When the rapid traverse override 100 is normally raised, there is almost no difference between the torque command value and the torque monitor value.

  The chart shown in FIG. 13 shows changes in the torque command value and the torque monitor value at the time of tool missing when the rapid traverse override is 100%. (A) shows the change of the torque command value and the torque monitor value, and (b) shows the change of the torque command value. When the tool is missing, a large change has occurred in the torque command value at the point p5, so that a difference can be confirmed between the torque command value and the torque monitor value. Therefore, there is a possibility that the numerical controller 30 can detect the occurrence of tool omission by comparing changes in the waveforms of the torque command value and the torque monitor value. However, as in the first embodiment, it is difficult to determine whether or not the change in waveform is an abnormal value from the chart shown in FIG.

  The chart shown in FIG. 14 shows changes in the torque command value and the torque monitor value during normal increase in the fast-forward override α. (A) shows the change of the torque command value and the torque monitor value, and (b) shows the change of the torque command value. The horizontal axis represents time (msec), and the vertical axis represents the torque monitor value (× 0.1%). In the process of raising the spindle head 7 from the machining position of the work material to a predetermined position, t13 to t14 are acceleration regions, t14 to t15 are constant speed regions, and t15 to t16 are deceleration regions. Even when the rapid traverse override α is normally increased, a difference between the torque command value and the torque monitor value can hardly be confirmed as in the case of the rapid traverse override 100%.

  The chart shown in FIG. 15 shows changes in the torque command value and the torque monitor value when the tool removal rises in the rapid traverse override α. Even when the tool missing of the rapid traverse override α occurs, a large change has occurred in the torque command value at the position p6, so that a difference can be confirmed between the torque command value and the torque monitor value. As a result of comparison with the chart shown in FIG. 13, when the rising speed of the spindle head 7 changes, the torque command value and the torque monitor value also change. Therefore, it is difficult to set a threshold for changes in the torque command value and the torque monitor value, so the CPU 31 continues to execute the following processing.

  As shown in FIG. 11, the CPU 31 calculates the difference between the torque monitor value and the torque command value acquired every predetermined time (S12). The difference is a difference between the acquired torque monitor value and a torque command value corresponding to the acquired torque monitor value. The chart shown in FIG. 16 shows a change in the difference between the torque monitor value and the torque command value at the time of normal increase and tool missing when the rapid traverse override is 100%. (A) shows the change of the difference at the time of normal ascent and tool missing, and (b) shows the change of the difference only at the time of normal ascent. The horizontal axis represents time (msec), and the vertical axis represents the torque monitor value (× 0.1%). A dotted line indicates a change in the difference when the tool is normally raised, and a solid line indicates a change in the difference when the tool is missing. The change in the difference at the time of tool missing has a large peak in the vicinity of 2000.0 (msec) with respect to the change in the difference at the normal rise.

  The chart shown in FIG. 17 shows changes in the difference between the torque monitor value and the torque command value at the time of the normal increase and the occurrence of tool removal in the rapid traverse override α. (A) shows the change of the difference at the time of normal ascent and tool missing, and (b) shows the change of the difference only at the time of normal ascent. The change in the difference at the time of tool removal has a large peak in the vicinity of 1800.0 (msec) with respect to the change in the difference during normal ascent. Therefore, it can be seen that the change in the difference between the torque monitor and the torque command value does not depend on the rising speed of the spindle head 7 and the same tendency is seen. Therefore, in the second embodiment, since a threshold value can be provided for information on the difference between the torque monitor value and the torque command value, it is possible to determine whether a tool is missing. As shown in FIGS. 16 and 17, in the second embodiment, for example, two threshold values (500 and -500) can be provided for the difference between the torque monitor value and the torque command value. Therefore, like the first embodiment, the second embodiment can always monitor tool missing.

  In the above description, the CPU 31 that executes the process of S11 of FIG. 11 is an example of the second acquisition unit of the present invention. CPU31 which performs the process of S12 is an example of the 2nd calculation means of this invention. CPU31 which performs the process of S6 is an example of the 2nd judgment means of this invention.

  A third embodiment of the present invention will be described with reference to FIG. The third embodiment is an example in which the first embodiment and the second embodiment are combined. In the third embodiment, when any of the time difference between the torque monitor values and the difference between the torque monitor value and the torque command value exceeds the respective threshold values, it is assumed that the tool has been removed and outputs abnormality information. The numerical control device of the third embodiment has the same configuration as that of the first embodiment, and executes the tool missing determination process shown in FIG. The tool missing determination process of the third embodiment includes the processes of S21 to S25 that combine the first embodiment and the second embodiment after the process of S4. Therefore, 3rd embodiment demonstrates centering around the process of S21-S25.

  As shown in FIG. 18, as in the first and second embodiments, when the spindle head 7 moves up to the Z axis in the machining area (S1: YES, S2: YES, S3: YES), the CPU 31 moves from the encoder 51B to Z. A torque monitor value as encoder information of the shaft motor 51 is acquired every predetermined time (for example, 0.5 msec) (S4). Subsequently, the CPU 31 acquires a torque command value (S21). The CPU 31 calculates a time difference (an example of third difference information of the present invention) of the torque monitor value acquired in S4 (S22), and determines whether or not the time difference exceeds a threshold value (S23). When the time difference exceeds the threshold (S23: YES), the CPU 31 outputs abnormality information (S7).

  Conversely, when the time difference does not exceed the threshold (S23: NO), the CPU 31 calculates the difference between the torque monitor value and the torque command value (an example of fourth difference information of the present invention) (S24), and the calculated difference is It is determined whether or not the threshold is exceeded (S25). When the calculated difference exceeds the threshold (S25: YES), the CPU 31 outputs abnormality information (S7). When the calculated difference does not exceed the threshold (S25: NO), the CPU 31 repeats the process until the Z-axis ascent is finished (S8). Therefore, the third embodiment monitors the time difference between the torque monitor values and the difference between the torque monitor value and the torque command value, thereby improving the accuracy of detecting the tool removal compared to the first and second embodiments. It can be improved.

  In the above description, the CPU 31 that executes the process of S21 in FIG. 18 is an example of the third acquisition unit of the present invention. The CPU 31 that executes the process of S22 is an example of a third calculation unit of the present invention. The CPU 31 that executes the processing of S23 is an example of third determination means of the present invention. The CPU 31 that executes the process of S24 is an example of a fourth calculation unit of the present invention. The CPU 31 that executes the process of S25 is an example of a fourth determination unit of the present invention.

  Needless to say, the present invention is not limited to the first, second, and third embodiments, and various modifications are possible. The machine tool 1 of the above embodiment is a machine tool in which the main shaft 9 on which the tool holder 17 is mounted is movable in the Z-axis direction, and the table 13 is movable in two axes in the X-axis and Y-axis directions. The mechanism of the moving mechanism of the main shaft 9 that moves relative to the table 13 in the X-axis, Y-axis, and Z-axis directions is not limited to the above embodiment. For example, a machine tool in which the main shaft is movable in three axes in the X-axis, Y-axis, and Z-axis directions and the work table is fixed may be used. The machine tool 1 of the above embodiment is a vertical machine tool, but may be a horizontal machine tool. In the case of a horizontal machine tool, a torque monitor value may be acquired from drive information of a motor that drives in a direction in which the main shaft approaches or separates from the table.

  In the first and third embodiments, the time difference between the torque monitor values is calculated and compared with a threshold value to detect the missing tool. However, the time, such as the speed, position, and position deviation of the Z-axis motor 51, is detected. Tool omission may be detected by calculating the difference and comparing it with a threshold value. The speed, position, and position deviation of the Z-axis motor 51 may be acquired from the drive information fed back from the encoder 51B. Further, in the second embodiment, the difference between the torque monitor value and the command value is calculated and compared with a threshold value to detect a tool missing, but the command value at the same time for the speed and position of the Z-axis motor 51 The tool omission may be detected by calculating a difference between and a threshold value.

  In the tool missing determination process (FIGS. 6, 11, and 18) of the above-described embodiment, when the tool missing is detected, the CPU 31 outputs abnormality information (S7) to stop the spindle head 7 from being raised and displayed. An error is displayed on the unit 25. For example, the notification of the error may be performed by combining light emission, sound, or the like in addition to the display on the display unit 25, or may be notified by either light emission or sound. The CPU 31 may store the time information when the abnormality information is output in the storage device 34. For example, when the operator is working away from the machine tool 1 and the tool is missing and the operation of the machine tool 1 is stopped, the operator checks the time information stored in the storage device 34 to check the tool information. You can check the time when the omission occurred.

  In the tool missing determination process of the third embodiment, the order of obtaining the encoder information and the torque command value may be reversed. After calculating the difference between the torque monitor value and the torque command value to determine tool removal, the time difference between the torque monitor values may be calculated to determine tool removal.

  Although the drive circuits 51A to 55A of the above embodiment are provided in the numerical controller 30, the drive circuits 51A to 55A may be provided in the machine tool 1.

DESCRIPTION OF SYMBOLS 1 Machine tool 4 Tool 7 Spindle head 9 Spindle 13 Table 17 Tool holder 30 Numerical control apparatus 31 CPU
51 Z-axis motor 51B Encoder Q1 Spring force

Claims (6)

A spindle head capable of approaching or moving away from a table supporting a work material, a spindle provided rotatably on the spindle head, a spring provided on the spindle, and a tool holder for holding a tool by the force of the spring A machine tool comprising: a clamp shaft that clamps to the main shaft; a motor that drives the main shaft head toward and away from the table; and an encoder that is connected to the motor and detects drive information of the motor. In the numerical control device for controlling
When the spindle head is moved to the machine origin side within the machining area on the table side from the machine origin of the machine tool , and the table does not move , the drive information is sent from the encoder every predetermined time. A first acquisition means for acquiring;
First calculation means for calculating first difference information, which is a difference between previous drive information and current drive information, based on the drive information acquired by the first acquisition means every predetermined time;
First determination means for determining whether the first difference information calculated by the first calculation means has a change exceeding a first threshold stored in advance;
A first output unit that outputs abnormality information indicating that a tool omission has occurred in the spindle when the first determination unit determines that the first difference information has a change exceeding the first threshold value; A numerical controller characterized by that. A spindle head capable of approaching or moving away from a table supporting a work material, a spindle provided rotatably on the spindle head, a spring provided on the spindle, and a tool holder for holding a tool by the force of the spring A machine tool comprising: a clamp shaft that clamps to the main shaft; a motor that drives the main shaft head toward and away from the table; and an encoder that is connected to the motor and detects drive information of the motor. In the numerical control device for controlling
When the spindle head is moved to the machine origin side within the machining area on the table side from the machine origin of the machine tool, and the table does not move, the drive information is sent from the encoder every predetermined time. A first acquisition means for acquiring;
Second acquisition means for acquiring command information that is input information of the motor corresponding to each of the drive information acquired by the first acquisition means at each predetermined time ;
Said driving information previous SL first acquisition means has acquired every predetermined time, a second calculating means for calculating a second difference information is difference information between the command information the second acquisition means has acquired,
Second determination means for determining whether the second difference information calculated by the second calculation means has a change exceeding a second threshold stored in advance ;
If the previous SL second determining unit determines that change exceeding the second threshold value to the second difference information is present, and a second output means for outputting the abnormality information indicating that the missing tool is generated in the main shaft
Numerical control apparatus characterized by comprising a. A spindle head capable of approaching or moving away from a table supporting a work material, a spindle provided rotatably on the spindle head, a spring provided on the spindle, and a tool holder for holding a tool by the force of the spring A machine tool comprising: a clamp shaft that clamps to the main shaft; a motor that drives the main shaft head toward and away from the table; and an encoder that is connected to the motor and detects drive information of the motor. In the numerical control device for controlling
When the spindle head is moved to the machine origin side within the machining area on the table side from the machine origin of the machine tool, and the table does not move, the drive information is sent from the encoder every predetermined time. A first acquisition means for acquiring;
Third acquisition means for acquiring command information which is input information of the motor corresponding to each of the drive information acquired by the first acquisition means at each predetermined time;
Third calculation means for calculating third difference information, which is a difference between the previous drive information and the current drive information, based on the drive information acquired by the first acquisition means every predetermined time ;
A third determining means for determining whether changes before Symbol third calculating means exceeds a first threshold value which is previously stored in the calculated said third differential information is present,
Fourth calculation means for calculating fourth difference information, which is information on a difference between the drive information acquired by the first acquisition means every predetermined time and the command information acquired by the third acquisition means;
Fourth determination means for determining whether the fourth difference information calculated by the fourth calculation means has a change exceeding a second threshold stored in advance ;
If the previous SL third determining unit determines that change exceeding the first threshold value to the third difference information is present, or the change of the fourth determination means exceeds said second threshold value to said fourth differential information is present A third output means for outputting abnormality information indicating that a tool omission has occurred in the spindle,
Numerical control apparatus characterized by comprising a. The drive information, numerical controller according to any one of claims 1 to 3, characterized in that the torque information of the motor. A spindle head capable of approaching or moving away from a table supporting a work material, a spindle provided rotatably on the spindle head, a spring provided on the spindle, and a tool holder for holding a tool by the force of the spring A machine tool comprising: a clamp shaft that clamps to the main shaft; a motor that drives the main shaft head toward and away from the table; and an encoder that is connected to the motor and detects drive information of the motor. In a control method of a numerical control device for controlling
When the spindle head is moved to the machine origin side within the machining area on the table side from the machine origin of the machine tool, and the table does not move, the drive information is sent from the encoder every predetermined time. A first acquisition step to acquire;
A first calculation step of calculating first difference information which is a difference between the previous drive information and the current drive information based on the drive information acquired at the predetermined time in the first acquisition step;
A first determination step of determining whether there is a change exceeding a first threshold stored in advance in the first difference information calculated in the first calculation step;
A first output step for outputting abnormality information indicating that a missing tool has occurred in the spindle when it is determined in the first determination step that the first difference information has a change exceeding the first threshold;
A control method comprising: A spindle head capable of approaching or moving away from a table supporting a work material, a spindle provided rotatably on the spindle head, a spring provided on the spindle, and a tool holder for holding a tool by the force of the spring A machine tool comprising: a clamp shaft that clamps to the main shaft; a motor that drives the main shaft head toward and away from the table; and an encoder that is connected to the motor and detects drive information of the motor. In a control method of a numerical control device for controlling
When the spindle head is moved to the machine origin side within the machining area on the table side from the machine origin of the machine tool, and the table does not move, the drive information is sent from the encoder every predetermined time. A first acquisition step to acquire;
A second acquisition step of acquiring command information that is input information of the motor corresponding to each of the drive information acquired at the predetermined time in the first acquisition step;
A second calculation step of calculating second difference information, which is difference information between the drive information acquired at the predetermined time in the first acquisition step and the command information acquired in the second acquisition step;
A second determination step of determining whether there is a change exceeding a second threshold stored in advance in the second difference information calculated in the second calculation step;
A second output step of outputting abnormality information indicating that tool missing has occurred in the spindle when it is determined in the second determination step that the second difference information has a change exceeding the second threshold;
A control method comprising: