Working machinery

Abstract

To provide a machine tool that can accurately determine whether the chuck is in a state where a tool can be attached or detached, based on the signal from a detection sensor. [Solution] The machine tool 100 includes a pressing mechanism 16, a detection sensor 19 that detects a first measuring section 351 and a second measuring section 352 of a pin 35, and a control unit 18. When the pressing mechanism 16 moves the pin 35 in the Z2 direction, the control unit 18 recognizes a normal attachment / detachment signal pattern in the following order: an ON signal indicating that the detection sensor 19 has detected the first measuring section 351, an OFF signal indicating that the detection sensor 19 has not detected either the first measuring section 351 or the second measuring section 352, and an ON signal indicating that the detection sensor 19 has detected the second measuring section 352. If the control unit 18 recognizes a signal pattern other than the normal attachment / detachment signal pattern, it determines that the chuck 32 is not in a state where the tool 8 can be attached or detached.

Description

Technical Field

[0001] The present invention relates to a machine tool.

Background Art

[0002] A machine tool equipped with a tool holding device is described in Patent Document 1. The machine tool of Patent Document 1 includes a tool holding device for holding a tool, a tool changing device for changing the tool, a spindle motor for rotating the tool, and a control unit. The tool holding device includes a spindle, a gripping portion provided at the tip of the spindle for gripping the tool, a shaft portion connected to the gripping portion, a spring that constantly biases the shaft portion upward, and a pin fixed to the shaft portion and protruding from a hole provided in the spindle. When the shaft portion is biased upward by the spring, the gripping portion is drawn into the spindle and grips the pull stud of the tool.

[0003] Further, the tool holding device includes a crank lever that contacts the pin from above and a drive mechanism that rotates the crank lever so as to push down the pin. When the pin is pushed down by the crank lever, the shaft portion also moves downward as the pin moves. As a result, the gripping portion is in a state where the tool can be detached.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In machine tools like the one described in Patent Document 1, the tool gripping device is equipped with a detection sensor that detects the position of a pin. The control unit determines whether the gripping part is in a state where the tool can be attached or detached based on the signal from the detection sensor. The detection sensor detects the pin when the gripping part is gripping the tool, and does not detect the pin when the pin has moved downward and the gripping part is in a state where the tool can be attached or detached. Therefore, when the pin is pushed downward by the crank lever, the control unit, upon recognizing the OFF signal from the detection sensor (which does not detect the pin) after the ON signal (which indicates the detection of the pin) of the detection sensor, determines that the gripping part is in a state where the tool can be attached or detached, and operates the tool changer to change the tool.

[0006] Here, if the pin breaks when it is pushed downward by the crank lever, the shaft cannot be moved downward, and the tool cannot be attached or detached. If the pin breaks, the detection sensor will not detect the pin, so even if the gripping part is not in a state where the tool can be attached or detached, the control unit will recognize the OFF signal from the detection sensor, which does not detect the pin, instead of the ON signal from when the detection sensor detected the pin. As a result, the control unit has the problem of operating the tool changer and changing the tool even when the gripping part is not in a state where the tool can be attached or detached.

[0007] In view of the above problems, the object of the present invention is to provide a machine tool that can accurately determine whether the gripping part is in a state where a tool can be attached to or detached, based on the signal of a detection sensor that detects a pin. [Means for solving the problem]

[0008] To solve the above problems, one aspect of a machine tool according to the present invention includes a tool gripping device that grips a tool supplied from a tool changing device for changing tools, A control unit that controls the operation of the tool gripping device, Equipped with, The tool gripping device is A main shaft that rotates with respect to the motor and has a shaft hole formed therein that extends along the axial direction along the rotation axis of the motor, A chuck is provided on the tip side within the shaft hole for gripping the tool, A drawbar is provided within the shaft hole so as to be movable in the axial direction, with its first end connected to the chuck, A biasing member provided in the shaft hole and biasing the drawbar in a first direction which is the direction in which the chuck connected to the drawbar is pulled into the shaft hole, A pin provided on the opposite side of the first end of the drawbar, extending in a direction perpendicular to the axial direction, and protruding outward from a hole formed in the side wall of the main shaft, wherein the pin has a side end face perpendicular to the axial direction, with a first measuring portion and a second measuring portion arranged in order toward the first direction, A pressing mechanism comprising a lever that can contact the pin from the first direction, and a lever drive unit that moves the lever in a second direction opposite to the first direction in order to attach or detach the tool by the chuck, A detection sensor for detecting the first measurement unit and the second measurement unit, Equipped with, The control unit, when the pressing mechanism moves the lever in the second direction and moves the pin in the second direction, When the detection sensor recognizes a normal attachment / detachment signal pattern consisting of an ON signal indicating detection of the first measuring unit, an OFF signal indicating that neither the first nor the second measuring unit is detected by the detection sensor, and an ON signal indicating detection of the second measuring unit by the detection sensor, it is determined that the chuck is in a state where the tool can be attached or detached. The system is characterized in that, if it recognizes a signal pattern other than the normal attachment / detachment signal pattern, it determines that the chuck is not in a state where the tool can be attached or detached.

[0009] In the machine tool of the present invention, the control unit determines that the chuck is in a state where the tool can be attached or detached when it recognizes a normal attachment / detachment signal pattern, and determines that the chuck is not in a state where the tool can be attached or detached when it recognizes a signal pattern other than a normal attachment / detachment signal pattern. Therefore, even if the pin breaks or deforms when the lever moves the pin in the second direction, the control unit can accurately determine whether the chuck is in a state where the tool can be attached or detached based on the signal from the detection sensor that detects the pin.

[0010] In the present invention, in the first state in which the chuck is not gripping the tool, the pin is positioned in a first direction relative to the detection sensor compared to the second state in which the chuck is gripping the tool. In the first state, the detection sensor does not detect either the first measurement unit or the second measurement unit, and in the second state, it detects the first measurement unit. In the first state, the control unit, before the pressing mechanism moves the lever in the second direction and moves the pin in the second direction, When the detection sensor recognizes an OFF signal that is not detected by either the first measurement unit or the second measurement unit, it is determined that the chuck is in a normal state. When the detection sensor recognizes the ON signal indicating that the first measuring unit has detected the chuck, it is preferable to determine that the chuck is not in a normal state. This allows the control unit to determine whether the chuck is normal when it is in the first state.

[0011] In the present invention, after the control unit determines that the chuck is in a state where the tool can be attached to or detached, when a new tool is supplied from the tool changing device and the pushing mechanism moves the lever in the first direction, the biasing member moves the chuck in the first direction, When the detection sensor recognizes a normal gripping signal pattern consisting of an ON signal indicating detection of the second measuring unit, an OFF signal indicating that neither the first nor the second measuring unit is detected by the detection sensor, and an ON signal indicating detection of the first measuring unit by the detection sensor, it is determined that the chuck is gripping the tool. It is preferable that the control unit determines that the chuck is not gripping the tool when it recognizes a signal pattern other than the normal gripping signal pattern. As a result, when the control unit recognizes a signal pattern other than the normal gripping signal pattern, it determines that the chuck is gripping the tool, and when it recognizes a signal pattern other than the normal gripping signal pattern, it determines that the chuck is not gripping the tool. Therefore, the control unit can determine that the chuck is gripping the tool normally based on the signal from the detection sensor that detects the pin.

[0012] In the present invention, in the first state in which the chuck is not gripping the tool, the pin is positioned in a first direction relative to the detection sensor compared to the second state in which the chuck is gripping the tool. In the first state, the detection sensor does not detect either the first measurement unit or the second measurement unit, and in the second state, it detects the first measurement unit. In the second state, the origin position of the main shaft is the position where the detection sensor detects the first measuring unit. In the second state, after the spindle has rotated, when the tool is being replaced by the tool changer, it is preferable that the control unit stops the tool replacement if the detection sensor does not detect the first measuring unit. This allows the control unit to determine whether the spindle is in the origin position, and if a malfunction occurs in the tool gripping device and the spindle is not in the origin position, the control unit can quickly stop the tool replacement.

[0013] The present invention further comprises a tool changing device that supplies the tool to the tool gripping device in order to change the tool, The control unit preferably controls the operation of the tool changer. Thereby, the control unit can appropriately control the operation of the tool changer based on a determination of whether the chuck is in a state where the tool can be detached or attached.

Brief Description of the Drawings

[0014] [Figure 1] FIG. 1 is a schematic perspective view of a machine tool. [Figure 2] FIG. 2 is a perspective view of the tool holding device of the present embodiment. [Figure 3] FIG. 3 is a sectional view taken along line A-A in FIG. 1. [Figure 4] FIG. 4 is a sectional view of the spindle device. [Figure 5] FIG. 5 is a perspective view showing the relationship between the spindle and the tool. [Figure 6] FIG. 6 is a perspective view for explaining the pin. [Figure 7] FIG. 7 is a diagram for explaining the relationship between the pin and the detection sensor. [Figure 8] FIG. 8 is a diagram for explaining the relationship between the pin and the detection sensor when the pin moves downward. [Figure 9] FIG. 9 is a diagram for explaining the relationship between the pin and the detection sensor when the pin moves upward.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of a tool holding device to which the present invention is applied will be described with reference to the drawings.

[0016] FIG. 1 is a schematic perspective view of a machine tool. FIG. 2 is a perspective view of the tool holding device of the present embodiment. FIG. 3 is a sectional view taken along line A-A in FIG. 1. FIG. 4 is a sectional view of the spindle device. FIG. 5 is a perspective view showing the relationship between the spindle and the tool. FIG. 6 is a perspective view for explaining the pin. FIG. 7 is a diagram for explaining the relationship between the pin and the detection sensor.

[0017] (Configuration of Machine Tool) As shown in Figure 1, the machine tool 100 includes a tool gripping device 10 for gripping the tool 8, a tool changing device 20 for supplying the tool 8 to the tool gripping device 10 for replacement, a spindle motor 17 for rotating the tool 8, and a control unit 18. The tool gripping device 10 includes a spindle device 15 for gripping the tool 8, a push mechanism 16 for releasing the tool 8 from the spindle device 15, and a detection sensor 19.

[0018] The machine tool 100 comprises a main frame 11, a support frame 14 that supports the spindle unit 15, a base 12 positioned below the spindle unit 15, and a table 13 provided on the base 12. The spindle unit 15 is positioned inside the support frame 14. The support frame 14 is mounted on the main frame 11 so as to be movable in the Z-axis direction and moves in the Z-axis direction by a drive mechanism 140. The drive mechanism 140 is, for example, an electric slider with a ball screw mechanism. As the support frame 14 moves in the Z-axis direction, the spindle unit 15 moves in the Z-axis direction. The table 13 moves on the base 12 by a drive mechanism (not shown). A workpiece to be machined by the tool 8 is placed on the table 13.

[0019] In the following explanation, the three mutually orthogonal axes are referred to as the X-axis, Y-axis, and Z-axis. The Z-axis coincides with the rotation axis L of the main shaft motor 17. The Z-axis direction is vertical, with Z1 direction (first direction) being upward and Z2 direction (second direction) being downward. The X-axis direction is front-back, with X1 direction being forward and X2 direction being backward. The Y-axis direction is width-wise.

[0020] As shown in Figure 1, the tool changer 20 is provided in the X1 direction of the spindle unit 15. The tool changer 20 is, for example, a turret type. The tool changer 20 includes a grip arm 21 for gripping the tool 8. The tool changer 20 operates the grip arm 21 to change the tool 8 of the tool gripping device 10.

[0021] As shown in Figures 3 and 4, the spindle device 15 comprises a spindle 31, a chuck 32, a drawbar 33, a biasing member 34, and a pin 35.

[0022] As shown in Figures 3 and 4, the spindle 31 is connected to the spindle motor 17 via a coupling and rotated by the spindle motor 17. The spindle 31 has a shaft hole 310 that extends axially along the rotation axis L of the spindle motor 17. The shaft hole 310 of the spindle 31 is composed of a tapered hole portion 313 and a housing hole portion 314. The tapered hole portion 313 is located in the Z2 direction, which is the tip side of the shaft hole 310. The tapered portion 81 of the tool 8 is housed on the inner circumferential surface of the tapered hole portion 313. The drawbar 33 is housed in the housing hole portion 314. A cylindrical inner cylinder portion 312 for receiving a biasing member 34 is arranged on the Z2 direction side of the housing hole portion 314. As shown in Figure 5, the Z2 direction end of the spindle 31 is provided with a claw portion 315 that fits into a notch portion 83 formed in the tool 8. The tool 8 is positioned around the rotation axis L relative to the spindle 31 by the claw portion 315 fitting into the notch portion 83. When the tool changer 20 changes the tool 8, the spindle 31 is positioned at the origin position where the tool 8 can be changed, and the tool changer 20 supplies the tool 8 to the spindle 31 so that the notch portion 83 fits into the claw portion 315 of the tool 8.

[0023] As shown in Figures 3 and 4, the chuck 32 is provided in the Z2 direction, which is the tip side of the housing hole 314, and grips the tool 8. The chuck 32 in this embodiment is a collet chuck. The chuck 32 comprises a plurality of jaw portions 321 for gripping the tool 8, and a retaining ring 322 for connecting the jaw portions 321 to the drawbar 33.

[0024] As shown in Figures 3 and 4, the drawbar 33 is movable in the direction of the rotation axis L within the shaft hole 310. The drawbar 33 moves in the direction of the rotation axis L within the shaft hole 310, thereby allowing the chuck 32 to detachably grip the pull stud 82 of the tool 8.

[0025] The drawbar 33 comprises a mounting shaft portion (first end) 331 connected to the chuck 32, a main shaft portion 333 provided coaxially with the mounting shaft portion 331, a flange portion 332 provided between the mounting shaft portion 331 and the main shaft portion 333 and extending radially outward, and a fixing member 334 provided at the end of the main shaft portion 333. The external dimensions of the fixing member 334 are larger than the external dimensions of the main shaft portion 333. The fixing member 334 is fixed to the Z1 end of the main shaft portion 333 by a screw 4. The fixing member 334 has a hole 335 formed therein for fixing a pin 35.

[0026] As shown in Figures 3 and 4, the biasing member 34 is provided in the shaft hole 310 and biases the drawbar 33 in the Z1 direction, which is the direction that pulls the chuck 32 connected to the drawbar 33 into the shaft hole 310. In this embodiment, the biasing member 34 consists of a plurality of disc springs 340. The disc springs 340 are positioned in an elastically deformed state between a washer 5, which is placed on the end face 316 of the inner cylinder portion 312 facing the Z1 direction, and a fixing member 334. Therefore, the disc springs 340 maintain an elastically deformed state, and when the chuck 32 grips the pull stud 82 of the tool 8, the tapered portion 81 of the tool 8 is pressed against the inner circumferential surface of the tapered hole portion 313 by the biasing force of the disc springs 340.

[0027] As shown in Figures 3, 4, and 6, the pin 35 is provided in the Z1 direction of the drawbar 33, extends in a direction perpendicular to the rotation axis L, and protrudes outward from a hole 311 formed in the side wall of the main shaft 31. The pin 35 is inserted into a hole 335 of the fixing member 334 and fixed to the fixing member 334 by a screw 6. The movement of the drawbar 33 in the Z-axis direction is restricted by the pin 35 contacting the Z-axis end of the hole 335.

[0028] As shown in Figure 6, the pin 35 has a first measuring portion 351 and a second measuring portion 352 on its side end face 350 in the Y2 direction in the Y axis direction, in the Z1 direction. The first measuring portion 351 and the second measuring portion 352 are projections that protrude from the side end face 350. The first measuring portion 351 and the second measuring portion 352 are separated in the Z axis direction.

[0029] As shown in Figures 2 and 3, the pressing mechanism 16 includes a lever 41 that can contact the pin 35 from the Z1 direction, and a lever drive unit 42 that moves the lever 41 in the Z2 direction to move the pin 35 in the Z2 direction in order to attach and detach the tool 8 by the chuck 32.

[0030] The lever 41 comprises a first lever 411 that can contact the pin 35 from the Z1 direction, a second lever 412 that receives driving force from the lever drive unit 42, and a connecting shaft 413 that connects the first lever 411 and the second lever 412. The connecting shaft 413 is rotatably supported on the support frame 14. As a result, the lever 41 is rotatably mounted on the support frame 14 and moves in the Z-axis direction together with the support frame 14.

[0031] The lever drive unit 42 includes a cam follower 421 provided at the Z1 end of the second lever 412, a cam 422 in contact with the cam follower 421, a base plate 424 to which the cam 422 is fixed, a spring 425 for bringing the cam follower 421 into contact with the cam 422, a support member 423 for fixing the cam 422 to the main frame 11 via the base plate 424, and a drive mechanism 140 for moving the cam follower 421 relative to the cam 422 in the Z-axis direction.

[0032] The spring 425 is fixed at one end to the top plate portion 141 of the support frame 14 and at the other end to the second lever 412. The spring 425 biases the lever 41 so that the cam follower 421 is always in contact with the cam 422. The support member 423 is fixed to the main frame 11. As the drive mechanism 140 moves the lever 41 in the Z1 direction via the support frame 14, the cam follower 421 moves up the cam surface of the cam 422, causing the lever 41 to rotate around the connecting shaft 413 in a direction in which the first lever 411 contacts the pin 35, pushing the pin 35 down in the Z2 direction. As a result, the drawbar 33 moves in the Z2 direction, and the chuck 32 releases its grip on the pull stud 82. Consequently, the tool 8 becomes unclamped. When the tool 8 becomes unclamped, the tool 8 is replaced by the tool changer 20.

[0033] As the drive mechanism 140 moves the lever 41 in the Z2 direction via the support frame 14, the cam follower 421 moves down the cam surface of the cam 422, causing the lever 41 to rotate around the connecting shaft 413 in a direction away from the pin 35. As the first lever 411 rotates away from the pin 35, the biasing member 34 moves the drawbar 33 in the Z1 direction. As the drawbar 33 moves in the Z1 direction, the chuck 32 is retracted into the shaft hole 310 and grips the pull stud 82. As a result, the tool 8 supplied by the tool changer 20 is clamped.

[0034] As shown in Figure 1, the detection sensor 19 is fixed to the side of the support frame 14 in the Y2 direction. As shown in Figures 2 and 6, the detection sensor 19 is a proximity sensor and detects the first measuring unit 351 and the second measuring unit 352 when they are located within a predetermined range. In this embodiment, since the first measuring unit 351 and the second measuring unit 352 are separated in the Z-axis direction, the detection sensor 19 does not detect both the first measuring unit 351 and the second measuring unit 352 simultaneously. That is, when the detection sensor 19 detects an object, it detects either the first measuring unit 351 or the second measuring unit 352.

[0035] Here, as shown in Figure 7, when the chuck 32 is retracted into the shaft hole 310, in the first state when the chuck 32 is not gripping the tool 8, the pin 35 is positioned in the Z1 direction relative to the sensor than in the second state when the chuck 32 is gripping the tool 8. Specifically, in the first state, the chuck 32 is completely retracted into the shaft hole 310, but in the second state, the tapered portion 81 of the tool 8 contacts the inner circumferential surface of the tapered hole portion 313, preventing the chuck 32 from being completely retracted into the shaft hole 310. Therefore, the position of the pin 35 in the first state is positioned in the Z1 direction relative to the position of the pin 35 in the second state. Consequently, in the first state, the position of the pin 35 is position P0, and the detection sensor 19 does not detect anything in either the first measuring section 351 or the second measuring section 352. In the second state, the position of pin 35 is at position P1, which is located in the Z2 direction from position P0, so the detection sensor 19 detects the first measuring unit 351 in the second state. Here, the origin position of the spindle 31 in the second state is the position where the detection sensor 19 detects the first measuring unit 351. Therefore, when the spindle 31 rotates and stops in the second state, the spindle 31 is at the origin position, and the detection sensor 19 detects the first measuring unit 351.

[0036] The control unit 18 controls the overall operation of the machine tool 100, including the tool gripping device 10, the tool changing device 20, and the spindle motor 17. As shown in Figure 1, the control unit 18 is fixed to the main frame 11. The control unit 18 also determines the state of the chuck 32 based on the ON signal detected by the detection sensor 19 and the OFF signal when the detection sensor 19 does not detect anything, when the pressing mechanism 16 moves the lever 41 in the Z-axis direction and moves the pin 35 in the Z-axis direction.

[0037] (Tool changing operation on a machine tool) Next, the tool changing operation of the machine tool 100 will be described. Figure 8 is a diagram illustrating the relationship between the pin and the detection sensor when the pin moves downward. Figure 9 is a diagram illustrating the relationship between the pin and the detection sensor when the pin moves upward.

[0038] As shown in Figure 8, in the first state, before the pressing mechanism 16 moves the lever 41 in the Z2 direction and moves the pin 35 in the Z2 direction, if the detection sensor 19 recognizes an OFF signal that is not detected by either the first measuring unit 351 or the second measuring unit 352, the control unit 18 determines that the position of the pin 35 is position P0 and that the chuck 32 is functioning normally.

[0039] On the other hand, when the control unit 18 detects an ON signal from the detection sensor 19 indicating that either the first measuring unit 351 or the second measuring unit 352 has detected an ON signal, it determines that the chuck 32 is not in a normal state. In this case, the control unit 18 displays on the monitor of the machine tool 100 that the chuck 32 is not in a normal state and stops the operation of the tool gripping device 10 and the tool changing device 20, etc.

[0040] Next, after the control unit 18 determines that the chuck 32 is functioning normally, the control unit 18 detects when the pressing mechanism 16 moves the lever 41 in the Z2 direction, causing the pin 35 to move in the Z2 direction. When the pin 35 is at position P1, the control unit 18 recognizes an ON signal from the detection sensor 19 indicating that the first measuring unit 351 has been detected. When the pin 35 is at position P2, the control unit 18 recognizes an OFF signal from the detection sensor 19 indicating that neither the first measuring unit 351 nor the second measuring unit 352 has been detected. When the control unit 18 detects an ON signal from the detection sensor 19 indicating that the second measuring unit 352 has been detected, the control unit 18 determines that the chuck 32 is in a state where a tool can be attached or detached. In other words, when the machine tool 100 changes the tool 8 in the first state, the control unit 18 recognizes an OFF signal and a normal attachment / detachment signal pattern from the detection sensor 19 and determines that the chuck 32 is in a state where the tool can be attached or detached. When the control unit 18 determines that the chuck 32 is in a state where the tool can be attached or detached, it operates the tool changer 20 and supplies a new tool 8 to the spindle unit 15.

[0041] On the other hand, if the control unit 18 recognizes a signal pattern other than the normal attachment / detachment signal pattern, it determines that the chuck 32 is not in a state where the tool can be attached or detached because the pin 35 is not in the attachment / detachment position P3. For example, if the pin 35 breaks, the control unit 18 will recognize a signal pattern from the detection sensor 19 that is in the order of ON signal, then OFF signal. In this case, because the pin 35 has broken, the drawbar 33 does not move in the Z2 direction, so the chuck 32 is not in a state where the tool 8 can be attached or detached. Therefore, the control unit 18 displays on the monitor of the machine tool 100 that the chuck 32 is not in a state where the tool 8 can be attached or detached, and stops the operation of the tool gripping device 10 and the tool changing device 20, etc.

[0042] Here, as shown in Figure 8, in the second state where the chuck 32 is gripping the tool 8, the pin 35 is located at position P1. When the machine tool 100 replaces the tool 8 in the second state, the control unit 18, similar to the first state described above, recognizes a normal attachment / detachment signal pattern from the detection sensor 19 in the order of ON signal, OFF signal, ON signal, and determines that the chuck 32 is in a state where the tool can be attached or detached. On the other hand, if the control unit 18 recognizes a signal pattern other than the normal attachment / detachment signal pattern, it determines that the chuck 32 is not in a state where the tool can be attached or detached because the pin 35 is not in the attachment / detachment position P3.

[0043] Next, when a new tool 8 is supplied from the tool changer 20 to the spindle unit 15, the push mechanism 16 moves the lever 41 in the Z1 direction, causing the biasing member 34 to move the chuck 32 in the Z1 direction. In this case, as shown in Figure 9, the control unit 18 recognizes an ON signal when the pin 35 is at position P4 and the detection sensor 19 detects the second measuring unit 352. The control unit 18 recognizes an OFF signal when the pin 35 is at position P5 and the detection sensor 19 does not detect either the first measuring unit 351 or the second measuring unit 352. The control unit 18 recognizes an ON signal when the pin 35 is at position P6 and the detection sensor 19 detects the first measuring unit 351. When the control unit 18 recognizes a normal gripping signal pattern from the detection sensor 19 in the order of ON signal, OFF signal, ON signal, it recognizes that the chuck 32 is gripping the tool 8. The control unit 18 determines that the chuck 32 is gripping the tool 8, and then operates the spindle motor 17, etc., to perform machining with the tool 8.

[0044] On the other hand, if the control unit 18 recognizes a signal pattern other than the normal gripping signal pattern, it determines that the chuck 32 is not gripping the tool 8 because the pin 35 is not in position P6, which is the position in which the tool 8 is gripped. For example, if the chuck 32 only partially grips the pull stud 82, the control unit 18 will recognize a signal pattern from the detection sensor 19 that is in the order of ON signal, then OFF signal. Also, if the pin 35 breaks, the control unit 18 will recognize a signal pattern from the detection sensor 19 that is in the order of OFF signal only. Furthermore, if the tool 8 is not supplied from the tool changer 20, the control unit 18 will recognize a signal pattern from the detection sensor 19 that is in the order of ON signal, OFF signal, ON signal, OFF signal. In this case, the chuck 32 is not gripping the tool 8. Therefore, the control unit 18 displays on the monitor of the machine tool 100 that the chuck 32 is not gripping the tool 8 and stops the operation of the tool gripping device 10 and the tool changer 20, etc.

[0045] Here, after machining with tool 8, when tool 8 is replaced by the tool changer 20, the control unit 18 determines, based on the signal from the detection sensor 19, whether the spindle 31 in the second state is at the origin position. Specifically, when the control unit 18 recognizes the ON signal from the detection sensor 19 that the first measuring unit 351 has been detected, it determines that the spindle 31 in the second state is at the origin position. If the control unit 18 determines that the spindle 31 in the second state is at the origin position, it operates the push mechanism 16 to move the pin 35 in the Z2 direction.

[0046] On the other hand, if the control unit 18 recognizes an OFF signal from the detection sensor 19 indicating that it does not detect the first measuring unit 351, it determines that the spindle 31 is not in the origin position in the second state. For example, the spindle 31 may shift from its origin position if the coupling connecting the spindle motor 17 and the spindle 31 becomes loose. In this case, the position of the notch 83 of the tool 8 supplied by the tool changer 20 does not match the position of the claw 315 of the spindle 31, making it impossible to change the tool 8 properly. Therefore, if the control unit 18 determines that the spindle 31 is not in the origin position in the second state, it displays this information on the monitor of the machine tool 100, stops the operation of the tool gripping device 10 and the tool changer 20, and stops changing the tool 8.

[0047] (Effects and Benefits) In this embodiment of the machine tool 100, when the push mechanism 16 moves the lever 41 in the Z2 direction and moves the pin 35 in the Z2 direction, the control unit 18 recognizes a normal attachment / detachment signal pattern in the following order: an ON signal indicating that the detection sensor 19 has detected the first measuring unit 351, an OFF signal indicating that the detection sensor 19 has not detected either the first measuring unit 351 or the second measuring unit 352, and an ON signal indicating that the detection sensor 19 has detected the second measuring unit 352. In this case, the control unit 18 determines that the chuck 32 is in a state where the tool 8 can be attached or detached. On the other hand, if the control unit 18 recognizes a signal pattern other than the normal attachment / detachment signal pattern, it determines that the chuck 32 is not in a state where the tool 8 can be attached or detached. As a result, even if the pin 35 breaks or deforms when the lever 41 moves the pin 35 in the Z2 direction, the control unit 18 can accurately determine whether the chuck 32 is in a state where the tool 8 can be attached or detached based on the signal from the detection sensor 19 that detects the pin 35.

[0048] In the first state, when the chuck 32 is not gripping the tool 8, the pin 35 is positioned in the Z1 direction relative to the detection sensor 19 compared to the second state, when the chuck 32 is gripping the tool 8. In the first state, the detection sensor 19 does not detect either the first measuring unit 351 or the second measuring unit 352, but in the second state, it detects the first measuring unit 351. In the first state, the control unit 18 turns OFF when the detection sensor 19 does not detect either the first measuring unit 351 or the second measuring unit 352, before the pressing mechanism 16 moves the lever 41 in the Z2 direction and moves the pin 35 in the Z2 direction. When the signal is recognized, the control unit 18 determines that the chuck 32 is in a normal state. On the other hand, when the control unit 18 recognizes the ON signal that the detection sensor 19 has detected the first measuring unit 351, it determines that the chuck 32 is not in a normal state. Thus, when the chuck 32 is in the first state, the control unit 18 can determine whether the chuck 32 is normal or not.

[0049] After the control unit 18 determines that the chuck 32 is in a state where the tool 8 can be attached or detached, a new tool 8 is supplied from the tool changer 20, and the pushing mechanism 16 moves the lever 41 in the Z1 direction, causing the biasing member 34 to move the chuck 32 in the Z1 direction. When the control unit 18 recognizes a normal gripping signal pattern in the following order: an ON signal indicating that the second measuring unit 352 has been detected by the detection sensor 19, an OFF signal indicating that neither the first measuring unit 351 nor the second measuring unit 352 has been detected by the detection sensor 19, and an ON signal indicating that the first measuring unit 351 has been detected by the detection sensor 19, the control unit 18 determines that the chuck 32 is gripping the tool 8. On the other hand, if the control unit 18 recognizes a signal pattern other than the normal gripping signal pattern, it determines that the chuck 32 is not gripping the tool 8. As a result, the control unit 18 can determine that the chuck 32 has properly gripped the tool 8 based on the signal from the detection sensor 19 that detects the pin 35.

[0050] In the second state, after the spindle 31 has rotated, when the tool 8 is being replaced by the tool changer 20, the control unit 18 stops the tool replacement if the detection sensor 19 does not detect the first measuring unit 351. This allows the control unit 18 to determine whether the spindle 31 is in the origin position, and if a malfunction occurs in the tool gripping device 10 and the spindle 31 is not in the origin position, the control unit 18 can quickly stop the tool replacement.

[0051] In this embodiment of the machine tool 100, the control unit 18 can appropriately control the operation of the tool changer 20 based on its determination of whether the chuck 32 is in a state where the tool 8 can be attached or detached.

[0052] (modified version) In the above embodiment, the first measuring section 351 and the second measuring section 352 were projections protruding from the side end face 350, but are not limited to projections. The shape of the first measuring section 351 and the second measuring section 352 is sufficient as long as the detection sensor 19 can detect two positions in the Z-axis direction on a single pin 35. Furthermore, the detection sensor 19 can be any sensor as long as it can detect two positions in the Z-axis direction on a single pin 35.

[0053] In the above embodiment, the cam follower 421 moves in the Z-axis direction relative to the fixed cam 422. However, in a modified example, the cam follower 421 may be fixed, and the cam 422 may move in the Z-axis direction relative to the fixed cam follower 421. [Explanation of Symbols]

[0054] 100...Machine tool, 10...Tool gripping device, 20...Tool changing device, 4...Screw, 5...Washer, 6...Screw, 8...Tool, 11...Main frame, 12...Base, 13...Table, 14...Support frame, 15...Spindle unit, 16...Push mechanism, 17...Spindle motor, 18...Control unit, 19...Detection sensor, 21...Grip arm, 31...Spindle, 32...Chuck, 33...Drawbar, 34...Biasing member, 35...Pin, 41...Lever, 42...Lever drive unit, 81...Tapered section, 82...Pull stud, 83...Notch, 140...Drive mechanism, 141...Top plate section 310... Shaft hole, 311... Hole section, 312... Inner cylinder section, 313... Tapered hole section, 314... Housing hole section, 315... Claw section, 316... End face, 321... Claw section, 322... Retaining ring, 331... Mounting shaft section, 332... Flange section, 333... Main shaft section, 334... Fixing member, 335... Hole section, 340... Disc spring, 350... Side end face, 351... First measuring section, 352... Second measuring section, 411... First lever, 412... Second lever, 413... Connecting shaft, 421... Cam follower, 422... Cam, 423... Support member, 424... Base plate, 425... Spring, L... Rotating shaft.

Claims

1. A tool gripping device for gripping the tool supplied from a tool changing device for changing tools, A control unit that controls the operation of the tool gripping device, Equipped with, The tool gripping device is A main shaft that rotates with respect to the motor and has a shaft hole formed therein that extends along the axial direction along the rotation axis of the motor, A chuck is provided on the tip side within the shaft hole for gripping the tool, A drawbar is provided within the shaft hole so as to be movable in the axial direction, with its first end connected to the chuck, A biasing member provided in the shaft hole and biasing the drawbar in a first direction which is the direction in which the chuck connected to the drawbar is pulled into the shaft hole, A pin provided on the side opposite to the first end of the drawbar, extending in a direction perpendicular to the axial direction, and protruding outward from a hole formed in the side wall of the main shaft, wherein the side end face of the pin in the direction perpendicular to the axial direction is provided with a first measuring portion and a second measuring portion in order toward the first direction, A pressing mechanism comprising a lever that can contact the pin from the first direction, and a lever drive unit that moves the lever in a second direction opposite to the first direction in order to move the pin in a second direction opposite to the first direction in order to attach or detach the tool by the chuck, A detection sensor for detecting the first measurement unit and the second measurement unit, Equipped with, The control unit, when the pressing mechanism moves the lever in the second direction and moves the pin in the second direction, When the detection sensor recognizes a normal attachment / detachment signal pattern consisting of an ON signal indicating detection of the first measuring unit, an OFF signal indicating that neither the first nor the second measuring unit is detected by the detection sensor, and an ON signal indicating detection of the second measuring unit by the detection sensor, it is determined that the chuck is in a state where the tool can be attached or detached. A machine tool characterized in that, upon recognizing a signal pattern other than the normal attachment / detachment signal pattern, it determines that the chuck is not in a state where the tool can be attached or detached.

2. In the first state, when the chuck is not gripping the tool, the pin is positioned in a first direction relative to the detection sensor, compared to the second state, when the chuck is gripping the tool. In the first state, the detection sensor does not detect either the first measurement unit or the second measurement unit, and in the second state, it detects the first measurement unit. In the first state, the control unit, before the pressing mechanism moves the lever in the second direction and moves the pin in the second direction, When the detection sensor recognizes an OFF signal that is not detected by either the first measurement unit or the second measurement unit, it is determined that the chuck is in a normal state. The machine tool according to claim 1, characterized in that when the detection sensor recognizes an ON signal indicating that the first measuring unit has been detected, it is determined that the chuck is not in a normal state.

3. After the control unit determines that the chuck is in a state where the tool can be attached to or detached, when a new tool is supplied from the tool changing device and the pushing mechanism moves the lever in the first direction, the biasing member moves the chuck in the first direction, When the detection sensor recognizes a normal gripping signal pattern consisting of an ON signal indicating detection of the second measuring unit, an OFF signal indicating that neither the first nor the second measuring unit is detected by the detection sensor, and an ON signal indicating detection of the first measuring unit by the detection sensor, it is determined that the chuck is gripping the tool. The machine tool according to claim 1, characterized in that when a signal pattern other than the normal gripping signal pattern is recognized, it is determined that the chuck is not gripping the tool.

4. In the first state, when the chuck is not gripping the tool, the pin is positioned in a first direction relative to the detection sensor, compared to the second state, when the chuck is gripping the tool. In the first state, the detection sensor does not detect either the first measurement unit or the second measurement unit, and in the second state, it detects the first measurement unit. In the second state, the origin position of the main shaft is the position where the detection sensor detects the first measuring unit. The machine tool according to claim 1, characterized in that, when the control unit replaces the tool by the tool changer after the spindle has rotated in the second state, if the detection sensor does not detect the first measuring unit, the tool changer stops replacing the tool.

5. The system further comprises a tool changing device that supplies the tool to the tool gripping device in order to replace the tool, The machine tool according to any one of claims 1 to 4, characterized in that the control unit controls the operation of the tool changing device.

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