JP2019177471A - Machine tool, control method and computer program - Google Patents

Abstract

To provide a machine tool, a control method and a computer program for determining the existence of an increase in resistance of a spring by abrasion powder.SOLUTION: Whether or not resistance generated by an energization member is increased more than initial resistance, is determined on the basis of a first difference between a magazine side movement time maximum current value of a motor detected in a first section in the movement direction for replacing a tool when a spindle head moves to the tool magazine side and a magazine side movement time average current value of the motor detected in a second section on the tool magazine side more than the first section when the spindle head moves to the tool magazine side or a second difference between a work side movement time maximum current value of the motor detected in the first section when the spindle head moves to the work side and a work side movement time average current value of the motor detected in the second section when the spindle head moves to the work side.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a machine tool for machining a workpiece, a control method, and a computer program.

  2. Description of the Related Art Conventionally, a machine tool includes a vertical pole, a spindle head that is provided on the vertical pole and that can move in the vertical direction, a motor that moves the spindle head, and a detection unit that detects a current value of the motor. The spindle head has a cylindrical spindle with the vertical direction as the axial direction. A draw bar for attaching and detaching the tool at one end and a spring for biasing the draw bar at the other end of the draw bar are provided inside the main shaft. A roller is provided on the vertical column, and a lever is provided on the spindle head. The lever has a cam surface and is connected to the draw bar. When changing the tool, the spindle head moves up and down, the roller moves on the cam surface, and the lever moves the draw bar up and down. The machine tool includes a control device. The control device detects the current value of the motor, and determines whether or not the spring has deteriorated based on the detected current value.

JP 2009-160690 A

  The drawbar and lever are connected by a pin. A long hole extending in the axial direction is formed in the main shaft. The pin protrudes from the long hole. When the draw bar moves, the pin moves along the slot. The pin comes into contact with the edge of the slot and wear powder is generated. The wear powder adheres to the spring and affects the expansion and contraction of the spring. However, the control device determines the deterioration of the spring without considering the wear powder.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a machine tool, a control method, and a computer program for determining whether or not there is an increase in spring resistance due to wear powder.

  A machine tool according to the present invention includes a spindle for mounting a tool for machining a workpiece, a tool magazine for storing a plurality of tools, a spindle rotatably supported, and the spindle moved to the tool magazine side and the workpiece side. A spindle head, a motor that moves the spindle head, a detection unit that detects a current value of the motor, a draw bar that is disposed inside the spindle and that attaches and detaches a tool at one end, and An urging member that is arranged inside the main shaft and urges the draw bar, and one end side of the draw bar against the urging force of the urging member when the main shaft head moves to the tool magazine side In a machine tool comprising a moving mechanism for moving the draw bar and a control device for controlling the motor, the control device moves the tool when the spindle head is moved toward the tool magazine. The maximum current value at the time of movement of the motor on the magazine side detected in the first section of the moving direction to be changed, and the tool magazine side of the first section when the spindle head is moved to the tool magazine side. The first difference from the average current value at the time of the magazine side movement of the motor detected in the second section, or the motor detected in the first section when the spindle head is moving to the work side Based on the second difference between the maximum current value during movement of the workpiece and the average current value during movement of the motor on the workpiece side detected in the second section when the spindle head is moving toward the workpiece. A determination unit for determining whether or not the resistance generated in the biasing member has increased from the initial resistance is provided.

  In the present invention, the biasing member is generated based on the first difference when the spindle head is moving toward the tool magazine or the second difference when the spindle head is moving toward the workpiece. It is determined whether the resistance has increased from the initial resistance.

  The determination unit of the machine tool according to the present invention includes a first determination unit that determines that the resistance has increased when the first difference is greater than or equal to a first threshold value.

  In the present invention, when the first difference is greater than or equal to the first threshold, it is determined that the resistance of the biasing member has increased.

  The control device for a machine tool according to the present invention includes a second determination unit that determines that the biasing member has deteriorated when the first difference is equal to or less than a second threshold value that is smaller than the first threshold value. And

  In this invention, when a 1st difference is below a 2nd threshold value, it determines with the biasing member having degraded.

  The determination part of the machine tool which concerns on this invention determines that the said resistance increased and the said urging | biasing member deteriorated, when the said 2nd difference is below the 3rd threshold value smaller than the said 2nd threshold value. It comprises a part.

  In the present invention, when the second difference is equal to or smaller than the third threshold value, it is determined that the resistance of the biasing member has increased and the biasing member has deteriorated.

  The control device for a machine tool according to the present invention includes a calculation unit that calculates an average of the first difference and the second difference, and the determination unit has a third difference that is a difference between the first difference and the average as a first difference. A fourth determination unit that determines that the resistance has increased when the fourth difference is equal to or greater than four thresholds, or the fourth difference that is the difference between the second difference and the average is equal to or less than a fifth threshold that is smaller than the fourth threshold. It is characterized by providing.

  In the present invention, the average of the first difference and the second difference is calculated, and the third difference, which is the difference between the first difference and the average, is greater than or equal to a fourth threshold, or the second difference and the average difference If the fourth difference is less than or equal to the fifth threshold value, which is smaller than the fourth threshold value, it is determined that the resistance of the biasing member has increased.

  The machine tool control device according to the present invention includes a fifth determination unit that determines that the biasing member has deteriorated when the average is equal to or less than a sixth threshold value.

  In this invention, when the said average is below a 6th threshold value, it determines with the said urging | biasing member having degraded.

  The control method according to the present invention detects the current value of the motor that moves the spindle head that moves the spindle to the tool magazine side and the workpiece side, and biases the draw bar that attaches and detaches the tool at one end by the biasing member. In the machine tool control method, when the spindle head is moving to the tool magazine side, the maximum current value at the time of movement of the motor on the magazine side detected in the first section in the moving direction for exchanging the tool; When the spindle head is moving to the tool magazine side, the first difference from the average current value during movement of the motor on the magazine side detected in the second section on the tool magazine side than the first section Or, when the spindle head is moving to the workpiece side, the maximum current value during movement of the motor detected in the first section and the spindle head is moving to the workpiece side. In addition, whether or not the resistance generated in the biasing member has increased from the initial resistance based on the second difference from the average current value during movement of the motor on the workpiece side detected in the second section. It is characterized by determining.

  In the present invention, based on the first difference when the spindle head is raised or the second difference when the spindle head is lowered, the resistance generated in the biasing member is higher than the initial resistance. Determine whether it has increased.

  The computer program according to the present invention detects the current value of the motor that moves the spindle head that moves the spindle to the tool magazine side and the workpiece side, and biases the draw bar that attaches and detaches the tool at one end by the biasing member. A computer program executable by a control device of a machine tool that detects the motor detected in a first section in a moving direction in which the tool is replaced when the spindle head is moving toward the tool magazine. Maximum current value when moving on the magazine side, and when the spindle head moves to the tool magazine side, and when the motor moves on the magazine side detected in the second section on the tool magazine side rather than the first section The first difference from the average current value, or the maximum when moving the workpiece side of the motor detected in the first section when the spindle head is moving to the workpiece side Based on the second difference between the flow value and the average current value during movement of the motor on the workpiece side detected in the second section when the spindle head moves to the workpiece side, the biasing member The process of determining whether or not the generated resistance has increased from the initial resistance is performed.

  In the present invention, based on the first difference when the spindle head is raised or the second difference when the spindle head is lowered, the resistance generated in the biasing member is higher than the initial resistance. Determine whether it has increased.

  In the machine tool, the control method, and the computer program according to the present invention, the bias is based on the first difference when the spindle head is raised or the second difference when the spindle head is lowered. It is possible to determine whether or not the resistance generated in the member has increased from the initial resistance, and to determine whether or not the resistance of the biasing member has increased due to wear powder.

1 is a perspective view showing a machine tool according to Embodiment 1. FIG. It is a fragmentary sectional view showing a tool magazine and a spindle head. It is sectional drawing which shows a main shaft apparatus schematically. It is a block diagram which briefly shows the structure of a control apparatus. It is a flowchart explaining the spring resistance increase and deterioration detection process at the time of a tool exchange. It is a flowchart explaining the spring resistance increase and deterioration detection process at the time of a tool exchange. It is a table | surface which shows the relationship between the vertical position of a spindle head and the drive current value of a Z-axis motor when resistance of a coil spring increases. It is a table | surface which shows the relationship between the vertical position of a spindle head and the drive current value of a Z-axis motor when a coil spring deteriorates. It is a table | surface which shows the relationship between the up-and-down position of a spindle head, and the drive current value of a Z-axis motor when resistance of a coil spring increases and a coil spring deteriorates. 10 is a table showing the relationship between the vertical position of the spindle head and the drive current value of the Z-axis motor when the resistance of the coil spring increases in the second embodiment. It is a table | surface which shows the relationship between the vertical position of a spindle head and the drive current value of a Z-axis motor when a coil spring deteriorates. It is a table | surface which shows the relationship between the up-and-down position of a spindle head, and the drive current value of a Z-axis motor when resistance of a coil spring increases and a coil spring deteriorates. Difference (U1-U2) between maximum drive current value U1 and average drive current value U2 when rising, difference (D1-D2) between maximum drive current value D1 and average drive current value D2 when falling, U1-U2 and D1- It is a table | surface which shows the relationship of the average X of D2, (U1-U2) -X, (D1-D2) -X. It is a flowchart explaining the spring resistance increase and deterioration detection process at the time of a tool exchange. It is a flowchart explaining the spring resistance increase and deterioration detection process at the time of a tool exchange.

(Embodiment 1)
Hereinafter, the present invention will be described with reference to the drawings showing a machine tool according to a first embodiment. In the following description, up, down, front, back, left, and right shown in the figure are used. FIG. 1 is a perspective view showing a machine tool, and FIG. 2 is a partial sectional view showing a tool magazine 60 and a spindle head 5. In FIG. 1, the description of the tool magazine 60 is omitted.

  The machine tool 100 includes a rectangular base 1 extending forward and backward. A work holding unit 3 that holds a work is provided on the front side of the upper portion of the base 1. The work holding unit 3 can rotate around the A axis with the left-right direction as the axial direction and the C axis with the up-down direction as the axial direction.

  On the rear side of the upper part of the base 1, there is provided a support base 2 for supporting a vertical pole 4 described later. A Y-axis direction moving mechanism 10 for moving the moving plate 16 in the front-rear direction is provided on the support base 2. The Y-axis direction moving mechanism 10 includes two rails 11 extending in the front-rear direction, a Y-axis screw shaft 12, a Y-axis motor 13, and a bearing 14.

  The rails 11 are provided on the left and right of the upper part of the support base 2, respectively. The Y-axis screw shaft 12 extends in the front-rear direction and is provided between the two rails 11. A bearing 14 is provided at each of the front end portion and the middle portion of the Y-axis screw shaft 12. In addition, illustration of the bearing provided in the middle part is abbreviate | omitted. 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. A plurality of sliders 15 are slidably provided on each rail 11. A moving plate 16 is connected to the upper part of the nut and the slider 15. The moving plate 16 extends in the horizontal direction. As the Y-axis motor 13 rotates, the Y-axis screw shaft 12 rotates, the nut moves in the front-rear direction, and the moving plate 16 moves in the front-rear direction.

  An X-axis direction moving mechanism 20 that moves the upright 4 in the left-right direction is provided on the upper surface of the moving plate 16. The X-axis direction moving mechanism 20 includes two rails 21 extending left and right, an X-axis screw shaft 22, an X-axis motor 23 (see FIG. 4), and a bearing 24.

  The rails 21 are provided at the front and rear sides of the upper surface of the movable plate 16. The X-axis screw shaft 22 extends left and right and is provided between the two rails 21. A bearing 24 is provided at each of the left end portion and midway portion of the X-axis screw shaft 22. In addition, description of the bearing provided in the middle part of the X-axis screw shaft 22 is abbreviate | omitted. The X-axis motor 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). A plurality of sliders 26 are slidably provided on each rail 21. The upright column 4 is connected to the upper part of the nut and the slider 26. The upright column 4 has a column shape. As the X-axis motor 23 rotates, the X-axis screw shaft 22 rotates, the nut moves in the left-right direction, and the upright 4 moves in the left-right direction.

  A Z-axis direction moving mechanism 30 for moving the spindle head 5 in the vertical direction is provided on the front surface of the upright column 4. The Z-axis direction moving mechanism 30 includes two rails 31 extending vertically, a Z-axis screw shaft 32, a Z-axis motor 33, and a bearing 34.

  The rails 31 are provided on the left and right of the front surface of the upright column 4 respectively. The Z-axis screw shaft 32 extends vertically and is provided between the two rails 31. A bearing 34 is provided at each of a lower end portion and a midway portion of the Z-axis screw shaft 32. In addition, illustration of the bearing provided in the middle part is abbreviate | omitted. The Z-axis motor 33 is connected to the upper end portion of the Z-axis screw shaft 32. A roller 33 c is provided on the front surface of the Z-axis motor 33. The roller 33c rotates with the left-right direction as the rotation axis direction.

  A nut (not shown) is screwed onto the Z-axis screw shaft 32 via a rolling element (not shown). A plurality of sliders 35 are slidably provided on each rail 31. The spindle head 5 is connected to the front part of the nut and 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. The upper side is the tool magazine side, and the lower side is the workpiece side. The Z-axis motor 33, the Z-axis screw shaft 32, the nut and the rolling element constitute a ball screw mechanism.

  A cam 70 is provided on the front surface of the spindle head 5. A spindle device 50 is provided on the spindle head 5. The main shaft device 50 has a cylindrical main shaft 51 extending vertically. The main shaft 51 rotates around the axis. A spindle motor 6 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 in the workpiece holding unit 3.

  The machine tool 100 includes a tool magazine 60. The tool magazine 60 is a circular turret type and is arranged on the front side of the spindle head 5. The upright column 4 supports the tool magazine 60. The tool magazine 60 is tilted so that the shaft center descends diagonally forward and downward. The tool magazine 60 rotates around its axis. A plurality of arms 61 for holding the tool 80 are provided on the peripheral portion of the tool magazine 60. The arm 61 includes a rotating shaft 62 whose axial direction is the left-right direction and a cam follower 63. When the spindle head 5 moves up and down, the cam follower 63 contacts the cam 70, and the arm 61 rotates to exchange the tool 80 between the spindle 51 and the tool magazine 60. A lever 71 is provided inside the spindle head 5. A cam surface 71 a is provided on the rear surface of the lever 71. In the front-rear direction, the cam surface 71a faces the roller 33c. The roller 33c contacts the cam surface 71a.

  FIG. 3 is a cross-sectional view schematically showing the spindle device 50. The spindle device 50 includes a cylindrical spindle 51, a chuck mechanism 52 that holds a tool, a draw bar 53, and a coil spring 54. A partition wall 51 c is provided inside the main shaft 51. A first chamber 51a is provided above the partition wall 51c, and a second chamber 51b is provided below the partition wall 51c.

  A draw bar 53 is inserted into the main shaft 51 along the axial direction. The draw bar 53 is movable in the axial direction. A rod-shaped main body 53a, a connecting shaft 53b, a flange 53c, and a screw shaft 53d are provided. The connecting shaft portion 53 b protrudes in the axial direction from one end portion of the main body portion 53 a and is connected to the chuck mechanism 52. The flange portion 53c has a larger diameter than the main body portion 53a and the connecting shaft portion 53b, and is provided at a connecting portion between the connecting shaft portion 53b and the main body portion 53a. The screw shaft 53d is provided at the other end of the main body 53a.

  The main body portion 53a and the flange portion 53c are located in the first chamber 51a. The connecting shaft portion 53b penetrates the partition wall 51c and is located in the first chamber 51a and the second chamber 51b. The chuck mechanism 52 is provided at the end of the second chamber 51b. The connecting shaft portion 53 b is connected to the chuck mechanism 52.

  A spring receiver 59 is provided around the flange portion 53c. The spring receiver 59 is located in the first chamber 51a. The spring receiver 59 includes a cylindrical portion 59a and an annular portion 59b. The annular portion 59b is provided coaxially at the end of the cylindrical portion 59a. The diameter of the opening of the annular part 59b is smaller than the diameter of the flange part 53c. The main body portion 53a is inserted into the opening of the annular portion 59b from the cylindrical portion 59a side.

  An extension member 57 is provided at the upper end of the first chamber 51a. The screw shaft 53d is screwed to the extension member 57. In the first chamber 51a, a coil spring 54 (biasing member) is provided around the main body 53a. The coil spring 54 is located between the extension member 57 and the spring receiver 59, and the upper and lower ends of the coil spring 54 are in contact with the extension member 57 and the spring receiver 59, respectively. The coil spring 54 urges the extension member 57 and the draw bar 53 upward.

  A plurality of bearings 55 are fitted to the outside of the lower portion of the main shaft 51, and support the main shaft 51 so as to be rotatable around the shaft. A non-mounting cylinder 56 is fitted outside the upper portion of the main shaft 51. A flange 56 a is provided at the lower end of the non-mounting cylinder 56. The non-mounting cylinder 56 is located on the radially outer side of the extension member 57.

  Two oblong holes (not shown) extending in the axial direction are provided in the upper part of the main shaft 51. The two oblong holes are opposed in the radial direction. The extending member 57 is provided with a pin hole 57a penetrating in the radial direction. The pin hole 57a is at a position corresponding to the oval hole. A pin 58 is inserted into the oblong hole and the pin hole 57 a, and both ends of the pin 58 are connected to the non-mounted cylinder 56.

  The roller 33c pushes the cam surface 71a of the lever 71, and the lever 71 pushes the non-mounted cylinder 56 downward through the pin 58. When the lever 71 pushes the flange 56a downward, the draw bar 53 moves downward against the biasing force of the coil spring 54.

  A chuck mechanism 52 is provided at the lower end of the main shaft 51. When exchanging the tool mounted on the chuck mechanism 52, the spindle head 5 is raised to the exchange position, the draw bar 53 is lowered when the lever 71 pushes the flange 56a downward, the coil spring 54 is shortened, and the chuck mechanism 52 is Release the tool. The arm 61 grips the tool 80 whose holding has been released. When the magazine motor 64 (see FIG. 4) is driven, the tool magazine 60 rotates, and the arm 61 that holds another tool 80 is allocated. The spindle head 5 is lowered, the lever 71 releases the depression of the flange 56a, the draw bar 53 is moved upward by the coil spring 54, and the chuck mechanism 52 holds another tool.

  The machine tool 100 includes a control device 90. FIG. 4 is a block diagram schematically showing the configuration of the control device 90. The control device 90 includes a CPU 91, a storage unit 92, a RAM 93, and an input / output interface 94. The storage unit 92 is a rewritable memory, such as an EPROM or an EEPROM. The storage unit 92 stores a machining program for machining a workpiece. The control device 90 controls the machine tool based on the control program stored in the storage unit 92. The control program can be stored in a storage medium such as a CD-ROM or HDD (not shown), and can be stored in the storage unit 92 from the storage medium via a reader or a network. The control device 90 may include a ROM that stores a control program in advance. The control device 90 may include a logic circuit such as an FPGA instead of the CPU 91.

  When the operator operates the operation unit 7, a signal is input from the operation unit 7 to the input / output interface 94. The operation unit 7 is a keyboard, a button, a touch panel, or the like, for example. The input / output interface 94 outputs a signal to the display unit 8. The display unit 8 displays characters, figures, symbols, and the like. The display unit 8 is, for example, a liquid crystal display panel.

  The control device 90 includes an X-axis control circuit 95 corresponding to the X-axis motor 23, a servo amplifier 95a, a differentiator 23b, and a current detector 95b. The X-axis motor 23 includes an encoder 23a. The X-axis control circuit 95 outputs a command indicating the amount of current to the servo amplifier 95a based on a command from the CPU 91. The servo amplifier 95 a receives the command and outputs a drive current to the X-axis motor 23.

  The encoder 23 a outputs a position feedback signal to the X-axis control circuit 95. The X-axis control circuit 95 executes position feedback control based on the position feedback signal.

  The encoder 23a outputs a position feedback signal to the differentiator 23b, and the differentiator 23b converts the position feedback signal into a speed feedback signal and outputs it to the X-axis control circuit 95. The X-axis control circuit 95 executes speed feedback control based on the speed feedback signal.

  The current detector 95b detects the value of the drive current output from the servo amplifier 95a. The current detector 95b feeds back the value of the drive current to the X-axis control circuit 95. The X axis control circuit 95 executes current control based on the value of the drive current.

  The control device 90 includes a Y-axis control circuit 96 corresponding to the Y-axis motor 13, a servo amplifier 96a, a differentiator 13b, and a current detector 96b. The Y-axis motor 13 includes an encoder 13a. The Y-axis control circuit 96, the servo amplifier 96a, the differentiator 13b, the Y-axis motor 13, the encoder 13a, and the current detector 96b are the same as those for the X-axis, and the description thereof is omitted.

  The control device 90 includes a Z-axis control circuit 97 corresponding to the Z-axis motor 33, a servo amplifier 97a, a current detector 97b, and a differentiator 33b. The Z-axis motor 33 includes an encoder 33a. The Z-axis control circuit 97, the servo amplifier 97a, the differentiator 33b, the Z-axis motor 33, the encoder 33a, and the current detector 97b are the same as those for the X-axis, and the description thereof is omitted.

  The control device 90 includes a magazine control circuit 98 corresponding to the magazine motor 64, a servo amplifier 98a, a current detector 98b, and a differentiator 64b. The magazine motor 64 includes an encoder 64a. The magazine control circuit 98, the servo amplifier 98a, the differentiator 64b, the magazine motor 64, the encoder 64a, and the current detector 98b are the same as those of the X axis, and the description thereof is omitted.

  The control device 90 includes a spindle control circuit 79 corresponding to the spindle motor 6, a servo amplifier 79a, a current detector 79b, and a differentiator 6b. The spindle motor 6 includes an encoder 6a. The spindle control circuit 79, the servo amplifier 79a, the differentiator 6b, the spindle motor 6, the encoder 6a, and the current detector 79b are the same as those of the X axis, and the description thereof is omitted.

  5 and 6 are flowcharts for explaining the spring resistance increase and deterioration detection process at the time of tool replacement, and FIG. 7 is the vertical position of the spindle head 5 and the drive current of the Z-axis motor 33 when the resistance of the coil spring 54 is increased. 8 is a table showing the relationship between values, FIG. 8 is a table showing the relationship between the vertical position of the spindle head 5 and the drive current value of the Z-axis motor 33 when the coil spring 54 is deteriorated, and FIG. 9 is a diagram showing an increase in resistance of the coil spring 54. 7 is a table showing the relationship between the vertical position of the spindle head 5 and the drive current value of the Z-axis motor 33 when the coil spring 54 is deteriorated. 7 to 9, the vertical axis I indicates the drive current value, and the horizontal axis Z indicates the vertical position of the spindle head 5. A broken line indicates an initial driving current value, and a solid line indicates a driving current value at the time of detection. 7A, FIG. 8A and FIG. 9A show drive current values when the spindle head 5 is raised, and FIGS. 7B, 8B and 9B show drive current values when the spindle head 5 is lowered.

When an external load is applied to the Z-axis motor 33, a speed change occurs. The speed change is detected by the position feedback signal and the speed feedback signal. The Z-axis control circuit 97 controls the drive power to restore the detected speed change. Therefore, the control device 90 controls the drive current according to the load applied to the Z-axis motor 33 during feedback control, and therefore detects the spring force of the coil spring 54 based on the drive current correlated with the load.
The lever 71 operates the pin 58 according to the shape of the cam surface 71a. At this time, the spring force of the coil spring 54 is transmitted to the lever 71 via the pin 58, and a vertical force is generated at the point where the cam surface 71a of the lever 71 and the roller 33c act. Therefore, a load is generated in the Z-axis motor 33 and the spring force of the coil spring 54 can be detected.

  The cam surface 71a has an inclined portion 71c and a straight portion 71d. When the roller 33c slides on the inclined portion 71c, the lever 71 rotates counterclockwise around the rotation shaft 71b and engages with the pin 58. Thereafter, when the roller 33c slides on the linear portion 71d, no vertical force is generated at the point where the cam surface 71a and the roller 33c act. Therefore, no load is generated on the Z-axis motor 33.

  The CPU 91 of the control device 90 determines whether or not the spindle head 5 is raised and the position of the spindle head 5 is equal to or greater than the position Za (step S1). When the spindle head 5 is raised and the position of the spindle head 5 is not equal to or higher than the position Za (step S1: NO), the CPU 91 returns the process to step S1. When the spindle head 5 is raised and the position of the spindle head 5 is not less than the position Za (step S1: YES), the CPU 91 determines that the spindle head 5 is between the position Za and the position Zb (Za <Zb) in the vertical direction, that is, the first position. It is determined whether or not it exists in one section (step S2). The first section corresponds to a section in which the roller 33c slides on the inclined portion 71c of the cam surface 71a.

When the spindle head 5 exists in the first section (step S2: YES), the CPU 91 detects the drive current value with the current detector 97b (step S3), and returns the process to step S2. While the spindle head 5 exists in the first section, the CPU 91 continuously detects and stores the drive current value. When the spindle head 5 does not exist in the first section (step S2: NO), that is, when the spindle head 5 moves to a position higher than the position Zb, the CPU 91, based on the drive current value detected in step S3, The maximum drive current value U1 in the first section is determined (step S4). The CPU 91 determines whether or not the position of the spindle head 5 is not less than the position Zc in the vertical direction and the spindle head 5 exists between the position Zc and the position Zd (Zb <Zc <Zd), that is, in the second section (step). S5). The second section corresponds to a section in which the roller 33c slides on the straight portion 71d of the cam surface 71a.
Strictly speaking, the section corresponding to the straight portion 71d of the cam surface 71a is Zb to Zd, but the section of Zb to Zc is excluded because there is a risk that the speed change is large and the drive current value becomes unstable. Zc to Zd, in which the drive current value is stable, were employed.

  When the spindle head 5 exists in the second section (step S5: YES), the CPU 91 detects the drive current value with the current detector 97b (step S6), and returns the process to step S5. While the spindle head 5 exists in the second section, the CPU 91 continuously detects and stores the drive current value. When the position of the spindle head 5 is not less than the position Za and does not exist in the second section (step S5: NO), that is, when the spindle head 5 moves to a position higher than the position Zd, the CPU 91 detects the drive detected in step S6. Based on the current value, an average U2 of the drive current values in the second section is calculated (step S7).

  The CPU 91 determines whether or not the spindle head 5 is lowered (step S8). When the spindle head 5 is not lowered (step S8: NO), the process is returned to step S8. When the spindle head 5 is lowered (step S8: YES), the CPU 91 determines whether or not the spindle head 5 exists in the second section (step S9).

  When the spindle head 5 exists in the second section (step S9: YES), the CPU 91 detects the drive current value with the current detector 97b (step S10), and returns the process to step S9. While the spindle head 5 exists in the second section, the CPU 91 continuously detects and stores the drive current value. When the spindle head 5 does not exist in the second section (step S9: NO), that is, when the spindle head 5 moves to a position lower than the position Zc, the CPU 91, based on the drive current value detected in step S10, An average D2 of drive current values in the second section is calculated (step S11). Then, it waits until the position of the spindle head 5 becomes equal to or less than the position Zb (step S12: NO). When the position of the spindle head 5 is equal to or less than the position Zb (step S12: YES), the CPU 91 determines whether or not the spindle head 5 exists in the first section (step S13).

  When the spindle head 5 exists in the first section (step S13: YES), the CPU 91 detects the drive current value with the current detector 97b (step S14), and returns the process to step S13. When the spindle head 5 does not exist in the first section (step S13: NO), the CPU 91 determines the maximum drive current value D1 in the first section based on the drive current value detected in step S14 (step S15).

  The CPU 91 determines whether or not the difference between the maximum drive current value U1 and the drive current value average U2 at the time of increase is greater than or equal to a predetermined first threshold value (step S16). When the difference between the maximum drive current value U1 and the drive current value average U2 at the time of increase is equal to or greater than a predetermined first threshold value (step S16: YES, see FIG. 7A), the CPU 91 notifies the resistance increase of the coil spring 54. (Step S17). For example, an increase in resistance of the coil spring 54 is displayed on the display unit 8. A lamp or buzzer may be provided to turn on the lamp or sound the buzzer. In FIG. 7A, the value A corresponds to the sum of the first threshold value and the drive current value average U2. When the difference between the maximum drive current value U1 and the drive current value average U2 is greater than or equal to a predetermined first threshold, the maximum drive current value U1 is greater than or equal to the value A.

  When the difference between the maximum drive current value U1 and the average drive current value U2 at the time of increase is less than a predetermined first threshold (step S16: NO), or after notifying the increase in resistance at step S17, the CPU 91 increases. It is determined whether or not the difference between the maximum driving current value U1 and the driving current value average U2 is equal to or smaller than a second threshold value that is smaller than the first threshold value (step S18). When the difference between the maximum drive current value U1 and the drive current value average U2 at the time of increase is equal to or less than the second threshold (step S18: YES, see FIG. 8A), the CPU 91 notifies the deterioration of the coil spring 54 (step S19). For example, the display unit 8 displays the deterioration of the coil spring 54. A lamp or buzzer may be provided to turn on the lamp or sound the buzzer. In FIG. 8A, the value B corresponds to the sum of the second threshold value and the drive current value average U2. When the difference between the maximum drive current value U1 and the drive current value average U2 is equal to or less than the second threshold value, the maximum drive current value U1 is equal to or less than the value B.

  When the difference between the maximum drive current value U1 at the time of increase and the average drive current value U2 is not less than the second threshold value (step S18: NO), or after notifying the deterioration at step S19, the CPU 91 determines the maximum drive current at the time of decrease. It is determined whether or not the difference between the value D1 and the drive current value average D2 is equal to or smaller than a third threshold value that is smaller than the second threshold value (step S20).

  When the difference between the maximum drive current value D1 and the average drive current value D2 during the descent is equal to or less than the third threshold (step S20: YES, see FIG. 9B), the CPU 91 notifies the resistance increase and deterioration of the coil spring 54 (step S21), the process ends. For example, the display unit 8 displays the resistance increase and deterioration of the coil spring 54. A lamp or buzzer may be provided to turn on the lamp or sound the buzzer. When the difference between the maximum drive current value D1 and the drive current value average D2 when descending is not less than or equal to the third threshold value (step S20: NO), the CPU 91 ends the process. In FIG. 9B, the value C corresponds to the sum of the third threshold value and the drive current value average D2. When the difference between the maximum drive current value D1 and the drive current value average D2 is not more than the third threshold value, the maximum drive current value D1 is not more than the value C.

  In the machine tool according to the first embodiment, the coil spring 54 is based on the first difference when the spindle head 5 is raised or the second difference when the spindle head is lowered. It can be determined whether or not the generated resistance has increased from the initial resistance, and it can be determined whether or not the resistance of the coil spring 54 has increased due to wear powder.

  If the first difference is equal to or greater than the first threshold, it is determined that the resistance of the biasing member has increased. When the first difference is equal to or smaller than the second threshold value, it is determined that the urging member has deteriorated. When the second difference is equal to or smaller than the third threshold value, it is determined that the resistance of the biasing member has increased and the biasing member has deteriorated.

(Embodiment 2)
Hereinafter, the present invention will be described with reference to the drawings showing a machine tool according to a second embodiment. FIG. 10 is a table showing the relationship between the vertical position of the spindle head 5 and the drive current value of the Z-axis motor 33 when the resistance of the coil spring 54 increases, and FIG. 11 shows the vertical axis of the spindle head 5 when the coil spring 54 deteriorates. FIG. 12 is a table showing the relationship between the position and the drive current value of the Z-axis motor 33. FIG. 12 shows the vertical position of the spindle head 5 and the drive current value of the Z-axis motor 33 when the resistance of the coil spring 54 increases and the coil spring 54 deteriorates. It is a table | surface which shows these relationships. 10 to 12, the vertical axis I represents the drive current value, and the horizontal axis Z represents the vertical position of the spindle head 5. A broken line indicates an initial driving current value, and a solid line indicates a driving current value at the time of detection. 10A, FIG. 11A, and FIG. 12A show the drive current value when the spindle head 5 is raised, and FIGS. 10B, 11B, and 12B show the drive current value when the spindle head 5 is lowered.

  As shown in FIG. 10, when the resistance of the coil spring 54 is increased, the maximum drive current value U1 when rising is larger than the initial state by a, and the maximum drive current value D1 when falling is higher than the initial state. b is small. As shown in FIG. 11, when the coil spring 54 is deteriorated, at the time of current detection, the maximum drive current value U1 when rising is smaller by c than the initial state, and the maximum drive current value D1 when falling is d smaller than the initial state. . As shown in FIG. 12, when the resistance of the coil spring 54 increases and the coil spring 54 deteriorates, the maximum drive current value U1 at the time of rising is larger by ac than the initial state at the time of current detection, and the maximum driving at the time of falling. The current value D1 is smaller than the initial state by b + d.

  FIG. 13 shows the difference (U1-U2) between the maximum drive current value U1 and the drive current value average U2 when rising, the difference (D1-D2) between the maximum drive current value D1 and the drive current value average D2 when falling, U1- It is a table | surface which shows the relationship of the average X of U2 and D1-D2, (U1-U2) -X, (D1-D2) -X. “Initial” in the left end column indicates an initial state, “Deterioration” indicates a case where the coil spring 54 is deteriorated, “Resistance” indicates a case where the resistance of the coil spring 54 is increased, and “Deterioration + resistance” indicates a coil The case where the spring 54 deteriorates and the resistance of the coil spring 54 increases is shown. In FIG. 13, the initial U1-U2 and D1-D2 are set to 100. In FIG. 13, a = b = c = d = 30, the fourth threshold is 20, the fifth threshold is −20, and the sixth threshold is 75.

  In FIG. 13, when (U1-U2) -X ≧ fourth threshold value, the coil spring 54 deteriorates, and when (D1-D2) -X ≦ fifth threshold value, the resistance of the coil spring 54 increases. When X ≦ the sixth threshold value, the coil spring 54 is deteriorated and the resistance of the coil spring 54 is increased. Each threshold value is determined based on the current value after determining the maximum drive current values U1 and D1 in a predetermined next period, for example, at the time of shipment from the factory or during replacement of parts.

  FIG. 14 and FIG. 15 are flowcharts for explaining the spring resistance increase and deterioration detection process during tool replacement. The CPU 91 of the control device 90 determines whether or not the spindle head 5 is raised and the position of the spindle head 5 is not less than the position Za (step S31). When the spindle head 5 is raised and the position of the spindle head 5 is not equal to or higher than the position Za (step S31: NO), the CPU 91 returns the process to step S31. When the spindle head 5 is raised and the position of the spindle head 5 is not less than the position Za (step S31: YES), the CPU 91 determines whether or not the spindle head 5 exists in the first section in the vertical direction (step S31). S32).

  When the spindle head 5 exists in the first section (step S32: YES), the CPU 91 detects the drive current value with the current detector 97b (step S33), and returns the process to step S32. While the spindle head 5 exists in the first section, the CPU 91 continuously detects and stores the drive current value. When the spindle head 5 does not exist in the first section (step S32: NO), that is, when the spindle head 5 moves to a position higher than the position Zb, the CPU 91, based on the drive current value detected in step S33, The maximum drive current value U1 in the first section is determined (step S34). The CPU 91 determines whether or not the position of the spindle head 5 is not less than the position Zc in the vertical direction and the spindle head 5 exists between the position Zc and the position Zd (Zb <Zc <Zd), that is, in the second section (step). S35).

  When the spindle head 5 exists in the second section (step S35: YES), the CPU 91 detects the drive current value with the current detector 97b (step S36), and returns the process to step S35. While the spindle head 5 exists in the second section, the CPU 91 continuously detects and stores the drive current value. When the position of the spindle head 5 is not less than the position Za and does not exist in the second section (step S35: NO), that is, when the spindle head 5 moves to a position higher than the position Zd, the CPU 91 detects the drive detected in step S36. Based on the current value, an average U2 of the drive current values in the second section is calculated (step S37).

  The CPU 91 determines whether or not the spindle head 5 is lowered (step S38). When the spindle head 5 is not lowered (step S38: NO), the process is returned to step S38. When the spindle head 5 is lowered (step S38: YES), the CPU 91 determines whether or not the spindle head 5 is present in the second section (step S39).

  When the spindle head 5 exists in the second section (step S39: YES), the CPU 91 detects the drive current value with the current detector 97b (step S40), and returns the process to step S39. While the spindle head 5 exists in the second section, the CPU 91 continuously detects and stores the drive current value. When the spindle head 5 does not exist in the second section (step S39: NO), that is, when the spindle head 5 moves to a position lower than the position Zc, the CPU 91, based on the drive current value detected in step S40, An average D2 of drive current values in the second section is calculated (step S41). Then, it waits until the position of the spindle head 5 becomes equal to or less than the position Zb (step S42: NO). When the position of the spindle head 5 is equal to or less than the position Zb (step S42: YES), the CPU 91 determines whether or not the spindle head 5 exists in the first section (step S43).

  When the spindle head 5 exists in the first section (step S43: YES), the CPU 91 detects the drive current value with the current detector 97b (step S44), and returns the process to step S43. When the spindle head 5 does not exist in the first section (step S43: NO), the CPU 91 determines the maximum drive current value D1 in the first section based on the drive current value detected in step S44 (step S45).

  The CPU 91 calculates the average X of the first difference (U1-U2) and the second difference (D1-D2) (step S46), and the difference between the first difference and the average X (third difference) is greater than or equal to the fourth threshold value. It is determined whether or not there is (step S47). When the difference between the first difference and the average X is not greater than or equal to the fourth threshold (step S47: NO), it is determined whether or not the difference between the second difference and the average X (fourth difference) is equal to or less than the fifth threshold (step). S48). When the difference between the first difference and the average X is equal to or greater than the fourth threshold (step S47: YES), or when the difference between the second difference and the average X is equal to or less than the fifth threshold (step S48: YES), the CPU 91 An increase in the resistance of the spring 54 is notified (step S49).

  After the process of step S49, or when the difference between the second difference and the average X is not less than or equal to the fifth threshold (step S48: NO), the CPU 91 determines whether or not the average X is less than or equal to the sixth threshold (step S50). ). When the average X is equal to or less than the sixth threshold (step S50: YES), the CPU 91 notifies the deterioration of the coil spring 54 (step S51), and ends the process. When the average X is not equal to or less than the sixth threshold (step S50: NO), the CPU 91 ends the process.

  In the second embodiment, two steps of step S47 and step S48 are executed, but only one of step S47 or step S48 may be executed. When the difference between the first difference and the average X is equal to or greater than the fourth threshold (step S47: YES), or when the difference between the second difference and the average X is equal to or less than the fifth threshold (step S48: YES), the CPU 91 You may alert | report the resistance increase of the spring 54 (step S49). If the difference between the first difference and the average X is not equal to or greater than the fourth threshold (step S47: NO), or if the difference between the second difference and the average X is not equal to or less than the fifth threshold (step S48: NO), the process proceeds to step S50. You may proceed.

  In the machine tool according to the second embodiment, the average X of the first difference (U1-U2) and the second difference (D1-D2) is calculated, and a third that is the difference between the first difference and the average X is calculated. If the difference is greater than or equal to the fourth threshold, or if the fourth difference, which is the difference between the second difference and the average X, is less than or equal to the fifth threshold smaller than the fourth threshold, the resistance of the coil spring 54 has increased. judge.

  Further, when the average X is equal to or smaller than the sixth threshold value that is larger than the fifth threshold value, it is determined that the coil spring 54 has deteriorated.

  Although the first and second embodiments describe a vertical machine tool in which the spindle head 5 moves up and down, the configurations of the first and second embodiments also apply to a horizontal machine tool in which the spindle head moves left and right or back and forth. Applicable. In the first and second embodiments, the tool magazine is not rotated by the tool change command. However, when the tool magazine is rotated, the tool magazine rotation command is executed before the spindle head is lowered. Further, it is not necessary to execute the spring resistance increase and deterioration detection process at the time of tool change every time there is a tool change command, and it may be executed at a predetermined time such as when the power is turned on or at a rest time.

5 Spindle head 51 Spindle 53 Draw bar 54 Coil spring (biasing member)
33 Z-axis motor (motor)
33c Roller (movement mechanism)
71 Lever (movement mechanism)
71a Cam surface (moving mechanism)
90 Control device 97b Current detector (detector)

Claims (8)

A spindle for mounting a tool for machining a workpiece, a tool magazine for storing a plurality of tools, a spindle head that rotatably supports the spindle and moves the spindle to the tool magazine side and the workpiece side, and the spindle head A motor that moves the motor, a detection unit that detects a current value of the motor, a draw bar that is attached to and detached from the spindle at one end, and an inner side of the spindle An urging member for urging the draw bar, and a moving mechanism for moving the draw bar toward one end of the draw bar against the urging force of the urging member when the spindle head moves toward the tool magazine. And a machine tool comprising a control device for controlling the motor,
The controller is
When the spindle head is moved to the tool magazine side, the maximum current value at the time of movement of the motor on the magazine side detected in the first section in the movement direction for exchanging the tool, and the spindle head is the tool magazine A first difference from the average current value during movement of the motor on the magazine side detected in the second section on the tool magazine side relative to the first section, or when the spindle head is a workpiece Detected in the first section, and detected in the second section when the spindle head is moving to the workpiece side. A determination unit configured to determine whether or not the resistance generated in the biasing member has increased from an initial resistance based on a second difference from the average current value during movement of the motor on the workpiece side. Machine tool . The machine tool according to claim 1, wherein the determination unit includes a first determination unit that determines that the resistance has increased when the first difference is greater than or equal to a first threshold value. The controller is
The machine tool according to claim 2, further comprising a second determination unit that determines that the biasing member has deteriorated when the first difference is equal to or less than a second threshold value that is smaller than the first threshold value. The determination unit
4. A third determination unit that determines that the resistance increases and the urging member has deteriorated when the second difference is equal to or less than a third threshold value that is smaller than the second threshold value. The machine tool described in 1. The controller is
An arithmetic unit that calculates an average of the first difference and the second difference;
The determination unit
The third difference, which is the difference between the first difference and the average, is greater than or equal to a fourth threshold, or the fourth difference, which is the difference between the second difference and the average, is less than or equal to a fifth threshold that is smaller than the fourth threshold. If there is, a machine tool according to any one of claims 1 to 4, further comprising a fourth determination unit that determines that the resistance has increased. The controller is
The machine tool according to claim 5, further comprising a fifth determination unit that determines that the urging member has deteriorated when the average is equal to or less than a sixth threshold value. In a control method of a machine tool that detects a current value of a motor that moves a spindle head that moves a spindle to a tool magazine side and a workpiece side, and biases a draw bar that attaches and detaches a tool at one end by a biasing member.
When the spindle head is moved to the tool magazine side, the maximum current value at the time of movement of the motor on the magazine side detected in the first section in the movement direction for exchanging the tool, and the spindle head is the tool magazine A first difference from the average current value during movement of the motor on the magazine side detected in the second section on the tool magazine side relative to the first section, or when the spindle head is a workpiece Detected in the first section, and detected in the second section when the spindle head is moving to the workpiece side. And determining whether or not the resistance generated by the biasing member has increased from an initial resistance based on a second difference from the average current value during movement of the motor on the workpiece side. . Executed by the machine tool controller that detects the current value of the motor that moves the spindle head that moves the spindle to the tool magazine side and workpiece side, and biases the draw bar that attaches and detaches the tool at one end by the biasing member. A possible computer program,
When the spindle head is moved to the tool magazine side, the maximum current value at the time of movement of the motor on the magazine side detected in the first section in the movement direction for exchanging the tool, and the spindle head is the tool magazine The first difference from the average current value at the time of movement on the magazine side of the motor detected in the second section on the tool magazine side than the first section, or when the spindle head is a workpiece Detected in the first section, and detected in the second section when the spindle head is moving to the workpiece side. And determining whether or not the resistance generated in the biasing member has increased from the initial resistance based on a second difference from the average current value during movement of the motor on the workpiece side. Comp Computer program.

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