CN109605102B

CN109605102B - Machine tool

Info

Publication number: CN109605102B
Application number: CN201811122869.8A
Authority: CN
Inventors: 加藤育也; 清田大
Original assignee: JTEKT Corp
Current assignee: JTEKT Corp
Priority date: 2017-10-04
Filing date: 2018-09-26
Publication date: 2022-08-30
Anticipated expiration: 2038-09-26
Also published as: CN109605102A; DE102018124305A1; JP7000785B2; JP2019063962A

Abstract

A machine tool (1) is provided with: a support device (12, 13, 14) that supports a workpiece (W) having an eccentric section (Wa) so as to be rotatable about a rotation axis (P2) of the workpiece (W); a parallel link mechanism (30) provided swingably about an axis (P7) parallel to a rotational axis (P2) of the workpiece W; a contact probe (40) attached to the parallel link mechanism (30) and provided with a tip detection unit (41); and a control device (25) that swings the parallel link mechanism (30) and rotates the workpiece (W), thereby bringing the distal end detection section (41) of the contact probe (40) into contact with the eccentric section (Wa), and calculates the phase of the eccentric section (Wa) based on the swing position when the distal end detection section (41) of the parallel link mechanism (30) comes into contact with the eccentric section (Wa) and the rotation angles (theta 12, theta 22) of the support devices (12, 13, 14).

Description

Machine tool

Technical Field

The present invention relates to machine tools.

Background

For example, in the case of machining a crank pin of a crankshaft, it is necessary to determine the phase of the crank pin before machining the crank pin. The phase determination method is described in, for example, japanese patent laid-open nos. 2005-262331 and 2004-142076.

Jp 2005-262331 a describes that the phase of a crank pin is determined by rotating a support device supporting the crank shaft using a reference member that is movable in a direction orthogonal to the rotation axis of the crank shaft and pressing the crank pin against the reference member.

Jp 2004-142076 a describes that the phase of a crank pin is calculated using a rectangular parallelepiped reference block provided in a tool spindle housing. That is, the first plane of the reference block is brought into contact with the crankpin by rotating the support device that supports the crankshaft, and the phase of the crankpin is calculated based on the rotation angle of the support device when the contact is made. Further, japanese patent application laid-open No. 2004-142076 discloses that the second plane of the reference block is brought into contact with the crankpin by reversing the support device, and the phase of the crankpin is calculated based on the rotation angle of the support device when the second plane and the first plane are brought into contact with each other.

Further, japanese patent nos. 2531609 and 4998078 disclose apparatuses for detecting the diameter, phase, and position of an end face of a non-circular workpiece using a contact probe. Further, japanese patent No. 3777825 discloses a device for managing the diameter of a grindstone using a contact probe.

The reference member of japanese patent laid-open No. 2005-262331 is movable only in a predetermined linear direction. Therefore, when the workpiece is changed to a crankshaft of a different type, the workpiece needs to be changed to a reference member of a different size and shape depending on the position of the crankpin. Therefore, the replacement of the reference member is required along with the change of the workpiece.

In japanese patent laid-open No. 2004-142076, a reference block is fixed to a spindle housing that is movable in two directions (Y direction and Z direction) orthogonal to the rotation axis of a workpiece. Therefore, even when the workpiece is changed to a crankshaft of a different type, the phase of the crankpin can be calculated without changing the reference block. However, since the reference block is fixed to the tool spindle housing, the reference block must be located at a position that does not become an obstacle during machining, and the arrangement is not easy.

In addition, in japanese patent application laid-open No. 2004-142076, when calculating a phase with high accuracy, the crankpin is brought into contact with the first plane and the second plane of the reference block. In other words, the two locations for the crank pin to contact are different. Thus, the direction of contact detection with the reference block is different. However, in order to calculate the phase with higher accuracy, it is preferable that the directions of contact detection with the crank pin be substantially the same in both locations.

Disclosure of Invention

The invention aims to provide a machine tool, which uses a contact type measuring head to calculate the phase of an eccentric part such as a crank pin with high precision and does not need to change production even if a workpiece is changed into a different type.

A machine tool according to an aspect of the present invention includes:

a support device that supports a workpiece having an eccentric portion so as to be rotatable about a rotation axis of the workpiece;

a parallel link mechanism provided swingably about an axis parallel to the rotation axis of the workpiece;

a contact probe attached to the parallel link mechanism and including a tip detection section; and

and a control device that causes the parallel link mechanism to swing and the workpiece to rotate, thereby bringing the tip detection portion of the contact probe into contact with the eccentric portion, and calculates a phase of the eccentric portion based on a swing position of the parallel link mechanism and a rotation angle of the support device when the tip detection portion comes into contact with the eccentric portion.

By attaching the contact type probe to the parallel link mechanism, the contact type probe always maintains the same posture (state of extending in a predetermined direction) regardless of the swing position of the parallel link mechanism. Further, the contact probe swings in conjunction with the swing of the parallel link mechanism. In other words, the trajectory of the distal end detection portion of the contact probe is circular arc. Further, the parallel link mechanism swings about an axis parallel to the rotation axis of the workpiece.

In other words, the tip detection portion of the contact probe moves in an arc shape on a plane (X-Y plane) orthogonal to the rotation axis (Z-axis direction) of the workpiece while maintaining the posture of the contact probe. In other words, the tip detection section of the contact probe moves two-dimensionally on a plane orthogonal to the rotation axis of the workpiece. Therefore, even if the eccentric amount and the size of the eccentric portion differ among different types of workpieces, the posture of the contact probe is maintained, and the tip detection portion of the contact probe can be brought into contact with the eccentric portion of the workpiece. As a result, even if the type of the workpiece is changed, the phase calculation can be performed with high accuracy without performing setup adjustment for the phase calculation.

Drawings

The above and still further features and advantages of the present invention will become apparent from the following detailed description of the embodiments with reference to the accompanying drawings, in which like elements are given like numerals.

Fig. 1 is a plan view of a machine tool.

Fig. 2 is a left side view of the first measuring device.

Fig. 3 is a front view of the first measuring device (view viewed from the right side of fig. 2).

Fig. 4 is a flowchart of the grinding process by the control device.

Fig. 5A is a flowchart of phase calculation processing in the phase calculation processing.

Fig. 5B is a flowchart of phase calculation processing in the phase calculation processing.

Fig. 6 is a schematic view of the first measuring device and the workpiece in S21 of fig. 5A as viewed from the axial direction.

Fig. 7 is a schematic view of the first measurement device and the workpiece in S22 of fig. 5A as viewed from the axial direction.

Fig. 8 is a schematic view of the first measuring device and the workpiece in S23 of fig. 5A as viewed from the axial direction.

Fig. 9 is a schematic view of the first measurement device and the workpiece in S24 of fig. 5A as viewed from the axial direction.

Fig. 10 is a schematic view of the first measuring device and the workpiece in S25 of fig. 5A as viewed from the axial direction.

Fig. 11 is a schematic view of the first measurement device and the workpiece in S28 of fig. 5B as viewed from the axial direction.

Fig. 12 is a schematic view of the first measuring device and the workpiece in S29 of fig. 5B as viewed from the axial direction.

Fig. 13 is a schematic view of the first measuring device and the workpiece in S30 of fig. 5B as viewed from the axial direction.

Fig. 14 is a schematic view of the first measuring device and the workpiece in S33 of fig. 5B as viewed from the axial direction.

Detailed Description

The structure of the machine tool 1 will be described with reference to fig. 1. The machine tool 1 is a machine for machining a workpiece W. The workpiece W is a shaft-like member having an eccentric portion Wa. The eccentric portion Wa is a portion centered on an axis eccentric with respect to the rotation axis of the workpiece W. In particular, the eccentric portion Wa has a cylindrical outer peripheral surface, and the central axis of the eccentric portion Wa is eccentric with respect to the rotational axis of the workpiece.

In the present embodiment, a crankshaft is exemplified as the workpiece W. However, the workpiece W is not limited to the crankshaft. The workpiece W as a crankshaft includes a crankpin as an eccentric section Wa. In fig. 1, for example, a crankshaft (workpiece W) includes four crank pins Wa. The axis of rotation of the crankshaft coincides with the central axis of the crank journal.

The machine tool 1 is, for example, a grinding machine, a lathe, a machining center, or the like. The machine tool 1 machines the outer peripheral surface of the eccentric portion Wa while rotating the workpiece W about the rotation axis of the workpiece W. The machine tool 1 can also machine the end surfaces of the crank arms as the connecting portions located at both ends of the eccentric portion Wa, while machining the outer peripheral surface of the eccentric portion Wa.

In the present embodiment, a grinding machine capable of grinding the eccentric section Wa as the crank pin is exemplified as the machine tool 1. However, the configuration for machining the eccentric section Wa in the present embodiment can be similarly applied to a lathe and a machining center. The grinding machine includes the grindstones 17 and 21 as tools, but differs from the lathe and the machining center in that a cutting tool is provided as a tool.

The machine tool 1 as a grinding machine is exemplified by a wheel slide traverse type. However, the machine tool 1 as a grinding machine can be of a table traverse type. Further, the machine tool 1 is exemplified to have a configuration including 2 grindstones 17 and 21, but a configuration including only one first grindstone 17 may be applied.

The machine tool 1 as a grinding machine mainly includes a machine base 11, a headstock 12, a chuck 13, a tailstock 14, a first traverse base 15, a first grinding wheel base 16, a first grinding wheel 17, a first measuring device 18, a second traverse base 19, a second grinding wheel base 20, a second grinding wheel 21, a second measuring device 22, a vibration isolation device 23, a dresser 24, and a controller 25.

The machine 11 is fixed on the setting surface. A guide rail 11a extending in the Z-axis direction (the left-right direction in fig. 1) is formed on the upper surface of the base 11. A first ball screw 11b extending in a direction parallel to the Z-axis direction and a first motor 11c for driving and rotating the first ball screw 11b are provided on the upper surface of the machine base 11. Further, a second ball screw 11d extending in a direction parallel to the Z-axis direction and a second motor 11e for driving and rotating the second ball screw 11d are provided on the upper surface of the base 11.

The headstock 12 functions as a support device that rotatably supports the workpiece W. The headstock 12 is provided on the upper surface of the machine base 11 on the front side in the X-axis direction (lower side in fig. 1) and on one end side in the Z-axis direction (right side in fig. 1), and is movable in the Z-axis direction. The headstock 12 includes a main spindle center 12a rotatable about the Z axis, and a main spindle motor 12b for driving and rotating the main spindle center 12 a. The main spindle center 12a supports the center of one end of the workpiece W.

The chuck 13 is provided on an end surface of the head stock 12 and is driven to rotate by a spindle motor 12 b. The chuck 13 holds an outer peripheral surface of one end of the workpiece W. In other words, the chuck 13 rotates together with the main spindle center 12a in a state in which the workpiece W is rotatably supported. Therefore, the chuck 13 also functions as a supporting device for rotatably supporting the workpiece W.

The tailstock 14 is provided on the upper surface of the machine base 11 at a position facing the headstock 12 in the Z-axis direction, that is, at the front side (lower side in fig. 1) in the X-axis direction and at the other end side (left side in fig. 1) in the Z-axis direction. The tailstock 14 is movable in the Z-axis direction, similarly to the headstock 12. The tailstock 14 includes a tailstock center 14a that supports the center of the other end of the workpiece W. In other words, the tailstock 14 functions as a support device that rotatably supports the workpiece W together with the headstock 12 and the chuck 13. The tailstock center 14a may be configured to rotate together with the workpiece W, or may be configured to slide relative to the workpiece W without rotating.

The first traverse base 15 is provided on the guide rail 11a so as to be movable in the Z-axis direction. The first traverse base 15 is fixed to a nut of the first ball screw 11b, and is moved in the Z-axis direction by driving of the first motor 11 c. A guide rail 15a extending in an X-axis direction (vertical direction in fig. 1) orthogonal to (intersecting) the Z-axis direction is formed on the upper surface of the first traverse base 15. A ball screw 15b extending in a direction parallel to the X-axis direction and a motor 15c for driving and rotating the ball screw 15b are provided on the upper surface of the first traverse base 15. The first traverse base 15 may be driven by a linear motor by changing the drive of the ball screw 15b and the motor 15c in the X-axis direction.

The first wheel slide 16 (moving table) is provided on the guide rail 15a of the first traverse base 15 so as to be linearly movable in the X-axis direction (direction orthogonal to (intersecting with) the rotation axis of the workpiece W). The first wheel slide 16 is moved in the X-axis direction by the rotational drive of the motor 15 c. The first wheel head 16 supports a first grinding wheel 17 as a tool to be rotatable about the Z axis. The first wheel head 16 includes a cover 16a that exposes a grinding portion of the first grinding wheel 17 and covers the other portions. The first wheel slide 16 is provided with a motor 16b for driving and rotating the first grinding wheel 17.

The first measuring device 18 is provided on the front surface (lower side in fig. 1) of the first wheel slide 16, and measures the workpiece W and the detection pin (not shown) in the dresser 24. The detailed configuration of the first measuring device 18 will be described later.

The second traverse base 19 is arranged on the guide rail 11a in parallel with the first traverse base 15. The second traverse base 19 is movable in the Z-axis direction, similarly to the first traverse base 15. The second traverse base 19 is fixed to a nut of the second ball screw 11d, and is moved in the Z-axis direction by driving of the second motor 11 e. A guide rail 19a extending in an X-axis direction (vertical direction in fig. 1) orthogonal to (intersecting with) the Z-axis direction is formed on the upper surface of the second traverse base 19. A ball screw 19b extending in a direction parallel to the X-axis direction and a motor 19c for driving and rotating the ball screw 19b are provided on the upper surface of the second traverse base 19. The second traverse base 19 may be driven by a linear motor by changing the drive of the ball screw 19b and the motor 19c in the X-axis direction.

The second wheel slide 20 is provided on the guide rail 19a of the second traverse base 19 so as to be movable in the X-axis direction. The second wheel slide 20 is moved in the X-axis direction by the rotational drive of the motor 19 c. The second wheel slide 20 supports a second grinding wheel 21 as a tool to be rotatable about the Z axis. The second wheel head 20 includes a cover 20a that exposes a grinding portion of the second grinding wheel 21 and covers the other portions. The second wheel slide 20 is provided with a motor 20b for driving and rotating the second grinding wheel 21.

The second measuring device 22 is provided on the front surface (lower side in fig. 1) of the second wheel slide 20, and measures the workpiece W and the detection pin (not shown) in the dresser 24. The second measuring device 22 includes a contact type probe (not shown) provided to extend in the Y-axis direction. The contact probe is supported by an arm that is rotatable about the Y axis, and a spherical tip detection unit of the contact probe moves in an arc shape on the X-Z plane while keeping the Y axis coordinate constant. The contact probe is movable to a retracted position (shown in fig. 1) where it does not contact the workpiece W and a contact position (not shown) where it can contact the workpiece W and the detection pins.

The vibration isolator 23 is provided on the upper surface of the machine base 11 at a position facing the first grinding wheel 17 and the second grinding wheel 21 with the workpiece W interposed therebetween. The vibration isolator 23 supports a surface (lower surface in fig. 1) of the workpiece W on the side opposite to the grinding portion. In fig. 1, the vibration isolator 23 supports the crank journal located at the axial center.

The truing device 24 is, for example, a device that is provided near the center of the headstock 12 and the tailstock 14 on the upper surface of the machine base 11 and trus the first grinding wheel 17 and the second grinding wheel 21. The dresser device 24 includes a known dresser and a detection pin, not shown. In the present embodiment, the truing device 24 performs truing of the first grindstone 17 and the second grindstone 21 in a state where the workpiece W is carried out.

The control device 25 controls the

motors

11c, 11e, 12b, 15c, 16b, 19c, 20b, and the like to execute grinding processing of the workpiece W, support processing of the workpiece W, phase calculation processing of the eccentric portion Wa of the workpiece W, end face measurement processing of the workpiece W, finishing processing, and the like.

Referring to fig. 2 and 3, the detailed structure of the first measuring device 18 will be described. A first measuring device 18 is provided at an end face of the first wheel slide 16 adjacent to the first wheel 17. Here, in fig. 2, the rotation axis of the first grinding wheel 17 is P1, and the rotation axis of the workpiece W is P2. The rotation axes P1, P2 are separated in the X-axis direction, and a plane passing through the rotation axes P1, P2 is an X-Z plane.

The first measuring device 18 includes a parallel link mechanism 30, a contact probe 40, and a driving device 50. As shown in fig. 2, the parallel link mechanism 30 is provided on the end surface of the first wheel slide 16 so as to be swingable about axes P3 and P4 parallel to the rotation axis P2 of the workpiece W. The parallel link mechanism 30 includes a first link member 31, a second link member 32, and a connecting member 33.

The first connecting rod member 31 is rotatably provided on an end surface of the first wheel slide 16 via a bearing, not shown. The rotation axis P3 of the first link member 31 is parallel to the rotation axis P2 of the workpiece W and is located above the X-Z plane passing through the rotation axes P1 and P2. The first link member 31 is formed in an elongated shape that tapers from a base end toward a leading end. Thus, the first link member 31 has rigidity corresponding to the moment generated by the swing. Therefore, the first link member 31 can suppress the occurrence of flexural deformation.

The second link member 32 is rotatably provided on the end surface of the first wheel slide 16 via a bearing, not shown. The rotation axis P4 of the second link member 32 is parallel to the rotation axis P3 of the first link member 31 and is located above the rotation axis P3 in the Y-axis direction. The second link member 32 is formed in the same shape as the first link member 31. In other words, the second link member 32 is formed in an elongated shape that tapers from the base end toward the leading end. Thus, the second link member 32 has rigidity corresponding to the moment generated by the swing, similarly to the first link member 31. Therefore, the second link member 32 can suppress the occurrence of flexural deformation.

The coupling member 33 is supported by bearings, not shown, so as to be rotatable about a rotation axis P5 at the tip of the first link member 31 and a rotation axis P6 at the tip of the second link member 32. Here, the separation distance of the rotation axes P5, P6 of the coupling member 33 is equal to the separation distance of the rotation axis P3 of the first link member 31 and the rotation axis P4 of the second link member 32. Therefore, the quadrangle connecting the rotation axes P3, P4, P5, and P6 always becomes a parallelogram in all postures. In other words, the first link member 31 and the second link member 32 always maintain a parallel state and swing with respect to the first wheel slide 16. Therefore, the connecting member 33 always maintains the posture extending in the Y-axis direction.

The contact probe 40 is attached to the connecting member 33 of the parallel link mechanism 30, and includes a spherical distal end detection portion 41. The contact probe 40 also swings relative to the first wheel slide 16 in conjunction with the swinging motion of the first link member 31 and the second link member 32 of the parallel link mechanism 30. At this time, the contact probe 40 attached to the coupling member 33 always maintains the same posture (state of extending in a predetermined direction) regardless of the position of the parallel link mechanism 30.

Here, the contact probe 40 is provided to extend in a direction intersecting the linear movement direction (X-axis direction) of the first wheel slide 16. More specifically, the contact probe 40 is provided to extend in the Y-axis direction, i.e., in a direction orthogonal to the linear movement direction (X-axis direction) of the first wheel slide 16. In other words, the contact probe 40 always maintains the posture extending in the Y-axis direction when the parallel link mechanism 30 swings.

Since the contact probe 40 is attached to the coupling member 33, the locus 41a of the spherical tip detection portion 41 swings about the axis P7 parallel to the rotation axis P2 of the workpiece W. In other words, the distal end detector 41 moves in an arc shape about the rotation axis P7 on the X-Y plane orthogonal to the rotation axis P2 (Z-axis direction) of the workpiece W. In other words, the tip detection unit 41 moves two-dimensionally on the X-Y plane. In particular, the rotation axis P7 of the leading end detecting portion 41 is disposed parallel to the rotation axes P1, P2 on a plane passing through the rotation axis P1 of the first grinding wheel 17 and the rotation axis P2 of the workpiece W.

As shown in fig. 3, the driving device 50 includes a motor 51 and a speed reducer 52. The rotation axes of the motor 51 and the reduction gear 52 are arranged on the same shaft, and coincide with the rotation axis P3 of the first link member 31. The motor 51 and the reduction gear 52 drive and rotate the first link member 31. In other words, the first link member 31 is rotated about the rotation axis P3 by the driving of the motor 51. The first link member 31 constitutes the parallel link mechanism 30 together with the second link member 32 and the coupling member 33, so that the second link member 32 and the coupling member 33 follow the first link member 31. As a result, the driving of the motor 51 swings the contact type gauge head 40.

Next, a method of grinding the eccentric portion Wa of the workpiece W by the machine tool 1 as a grinding machine will be described with reference to fig. 4. The grinding method is performed by the control device 25. First, the controller 25 determines whether or not the workpiece W is carried into the machine tool 1 (step S1). If no workpiece W is loaded (S1: no), the control device 25 waits until the workpiece W is loaded.

When the workpiece W is loaded (S1: YES), the controller 25 advances the headstock 12 and the tailstock 14, respectively (step S2). Thus, the workpiece W is fixedly supported by both ends of the spindle center 12a and the tailstock center 14 a. Next, the controller 25 closes the chuck 13, and grips the workpiece W by the chuck 13 (step S3).

Next, the control device 25 executes phase calculation processing for calculating the phase of the eccentric portion Wa of the workpiece W in the state of being supported by the spindle center 12a, the chuck 13, and the tailstock center 14a, using the first measuring device 18 (step S4).

Next, the control device 25 performs a measurement process of the end surface located at the end portion of the eccentric portion Wa of the workpiece W using the first measuring device 18 and the second measuring device 22 (step S5). The front end detecting portion 41 of the contact probe 40 of the first measuring device 18 is brought into contact with the end surface of the workpiece W, thereby calculating the positional relationship in the Z-axis direction between the first wheel slide 16 and the end surface of the workpiece W. Further, the distal end detection portion of the contact probe of the second measuring device 22 is brought into contact with the end surface of the workpiece W, and the positional relationship in the Z-axis direction between the second wheel slide 20 and the end surface of the workpiece W is calculated.

Next, the control device 25 executes a grinding process according to the NC program based on the phase calculated in step S4 and the end face information measured in step S5 (step S6). For example, the first grinding wheel 17 and the second grinding wheel 21 grind different eccentric portions Wa simultaneously. Of course, the first grinding wheel 17 and the second grinding wheel 21 may grind different eccentric portions Wa in different machines.

In order to grind the workpiece W with the first grinding wheel 17, the controller 25 rotates the workpiece W by the spindle motor 12b, rotates the first grinding wheel 17 by the motor 16b, and moves the first grinding wheel 17 relative to the workpiece W by the

motors

11c and 15 c. In order to grind the workpiece W by the second grinding wheel 21, the controller 25 rotates the workpiece W by the spindle motor 12b, rotates the second grinding wheel 21 by the motor 20b, and moves the second grinding wheel 21 relative to the workpiece W by the motors 11e and 19 c.

When the grinding process is completed, the controller 25 opens the chuck 13 (step S7) and retracts the headstock 12 and the tailstock 14 (step S8). Thus, the support of the workpiece W is released. Next, the controller 25 determines whether or not the workpiece W has been carried out (step S9). Then, the controller 25 stands by until the workpiece W is carried out (S9: no).

When the workpiece W is carried out (yes in S9), the control device 25 determines whether dressing of the first grindstone 17 and the second grindstone 21 is necessary (step S10). For example, whether or not dressing is necessary is determined based on the number of workpieces W that have been ground. If trimming is not necessary (no in S10), control device 25 returns the process to repeat the process from step S1.

If dressing is required (S10: YES), control device 25 executes dressing (step S11). Trimming is performed using a trimming device 24. For example, the control device 25 causes the first grinding wheel 17 to contact the detection pin, and measures the position of the detection pin by the contact probe 40 of the first measuring device 18, thereby calculating the outer diameter of the first grinding wheel 17. Next, the control device 25 dresses the first grinding wheel 17 with a dresser based on the calculated outer diameter. Next, the control device 25 grinds the inspection pin by the dressed first grinding wheel 17, measures the position of the inspection pin by the contact probe 40 of the first measuring device 18, and calculates the outer diameter of the dressed first grinding wheel 17. The information on the outside diameter of the dressed first grinding wheel 17 is used for grinding. In addition, the second grinding wheel 21 is also subjected to the same process.

The phase calculation process (S4) in the grinding method shown in fig. 4 will be described in detail with reference to fig. 5A to 14. The phase calculation process uses the first measurement device 18. As shown in fig. 6, the controller 25 moves the first grinding wheel head 16 forward to the preliminary position in a state where the contact probe 40 is located at the upper end position (the retracted position T3) in the movement range (step S21). The retracted position T3 of the contact probe 40 is a position at which the contact probe 40 does not interfere with grinding by the first grinding wheel 17. The standby position is located rearward of a predetermined position (fig. 9) described later. At this time, the distance between the rotation axis P2 of the workpiece W and the tip detection section 41 of the contact probe 40 in the X-axis direction is X0.

Next, as shown in fig. 7, the control unit 25 drives the motor 51 of the drive unit 50 to move the contact probe 40 to the first contact position T1 (step S22). In the first contact position T1, the distal end detector 41 is located at a position spaced upward by a predetermined distance from a plane (X-Z plane) connecting the center P7 of the circular arc trajectory 41a of the distal end detector 41 and the rotation axis P2 of the workpiece W. The first contact position T1 is a position for bringing the distal end detection portion 41 of the contact probe 40 into contact with the eccentric portion Wa of the workpiece W. At this time, the distance in the X axis direction between the rotation axis P2 of the workpiece W and the distal end detection portion 41 of the contact probe 40 becomes shorter than X1 of X0.

Next, as shown in fig. 8, the control device 25 rotates the spindle motor 12b in the normal direction (counterclockwise rotation in fig. 7) to position the eccentric portion Wa at the first preliminary angle θ 11 (step S23). The state in which the eccentric portion Wa is located at the first preliminary angle θ 11 is a state in which the eccentric portion Wa is located above an X-Z plane passing through the axes P2 and P7 and faces the tip detection portion 41 of the contact probe 40 located at the first contact position T1 in the X-axis direction.

Next, as shown in fig. 9, the controller 25 moves the first wheel slide 16 forward to the predetermined position (step S24). At this time, the contact probe 40 is located at the first contact position T1. Then, the distance between the rotation axis P2 of the workpiece W and the tip detection section 41 of the contact probe 40 in the X-axis direction is X2 which is shorter than X1.

Next, as shown in fig. 10, the control device 25 rotates the spindle motor 12b in the normal direction (counterclockwise rotation in fig. 10) (step S25). Then, the control device 25 determines whether or not the distal end detecting portion 41 of the contact probe 40 is in contact with the eccentric portion Wa of the workpiece W (step S26). The workpiece W is rotated in the normal direction until the eccentric portion Wa comes into contact with the tip detecting portion 41 of the contact probe 40 (S26: no).

When the contact is made (S26: YES), the controller 25 stops the spindle motor 12b and stores the first angle θ 12 at that time, as shown in FIG. 10 (step S27). When the tip detection portion 41 of the contact probe 40 is in contact with the eccentric portion Wa of the workpiece W, the Y-axis direction position of the tip detection portion 41 is located at the same position as the Y-axis direction position of the eccentric portion Wa. Therefore, the force acts in the X-axis direction on the tip detection portion 41 by the tip detection portion 41 contacting the eccentric portion Wa, and the contact probe 40 detects the contact.

Next, as shown in fig. 11, the controller 25 rotates the spindle motor 12b in the reverse direction (clockwise rotation in fig. 11) to position the eccentric section Wa at the second preliminary angle θ 21 (step S28). The state in which the eccentric section Wa is located at the second preliminary angle θ 21 is a state in which the eccentric section Wa is located below an X-Z plane passing through the axes P2 and P7.

Next, as shown in fig. 12, the control unit 25 drives the motor 51 of the drive unit 50 to move the contact probe 40 to the second contact position T2 (step S29). In the second contact position T2, the distal end detecting unit 41 is located at a position separated downward by a predetermined distance from a plane (X-Z plane) connecting the center P7 of the circular arc trajectory 41a of the distal end detecting unit 41 and the rotation axis P2 of the workpiece W. The second contact position T2 is a position for bringing the distal end detecting portion 41 of the contact probe 40 into contact with the eccentric portion Wa of the workpiece W. At this time, the distance between the rotation axis P2 of the workpiece W and the tip detection section 41 of the contact probe 40 in the X-axis direction is X2. In other words, the position of the tip detection section 41 of the contact probe 40 in the X axis direction is the same in the state where the contact probe 40 is located at the first contact position T1 and in the state where the contact probe 40 is located at the second contact position T2. The tip end detection portion 41 of the contact probe 40 located at the second contact position T2 faces the eccentric portion Wa located at the second preliminary angle θ 21 in the X axis direction.

Next, as shown in fig. 13, the controller 25 rotates the spindle motor 12b in the reverse direction (clockwise rotation in fig. 13) (step S30). Then, the control device 25 determines whether or not the distal end detecting portion 41 of the contact probe 40 is in contact with the eccentric portion Wa of the workpiece W (step S31). The workpiece W is reversed until the eccentric portion Wa comes into contact with the tip end detecting portion 41 of the contact probe 40 (S31: no).

When the contact is made (S31: Yes), the controller 25 stops the spindle motor 12b and stores the second angle θ 22 (step S32) as shown in FIG. 13. When the tip detection portion 41 of the contact probe 40 is in contact with the eccentric portion Wa of the workpiece W, the Y-axis direction position of the tip detection portion 41 is located at the same position as the Y-axis direction position of the eccentric portion Wa. Therefore, the force acts in the X-axis direction on the tip detection portion 41 by the tip detection portion 41 contacting the eccentric portion Wa, and the contact probe 40 detects the contact. In other words, the direction of the force acting on the tip detection portion 41 by the contact between the tip detection portion 41 and the eccentric portion Wa when the contact probe 40 is located at the first contact position T1 and the direction of the force acting on the tip detection portion 41 by the contact between the tip detection portion 41 and the eccentric portion Wa when the contact probe 40 is located at the second contact position T2 substantially coincide with each other. Therefore, the contact probe 40 can detect the contact position at two positions of contact with each other with high accuracy.

Next, the controller 25 moves the contact probe 40 to the retracted position T3 while retracting the first wheel slide 16 (step S33). Then, the distance in the X axis direction between the rotation axis P2 of the workpiece W and the distal end detection portion 41 of the contact probe 40 becomes X3 longer than X0. Next, the control device 25 calculates the phase of the eccentric portion Wa based on the swing angle and the first angle θ 12 of the parallel link mechanism 30 when the contact probe 40 is located at the first contact position T1, and the swing angle and the second angle θ 22 of the parallel link mechanism 30 when the contact probe 40 is located at the second contact position T2 (step S34). Then, the process is ended.

Further, as described above, the control device 25 calculates the phase of the eccentric portion Wa using the swing angle and the first angle θ 12 of the parallel link mechanism 30 at the first contact position T1, and the swing angle and the second angle θ 22 of the parallel link mechanism 30 at the second contact position T2. When there is a difference in the outer diameter of the eccentric section Wa, the phase of the eccentric section Wa can be calculated with high accuracy by the above-described processing. However, when the difference in the outer diameter of the eccentric portion Wa is within the allowable range, the phase of the eccentric portion Wa can be calculated using only the outer diameter of the eccentric portion Wa, the swing angle of the parallel link mechanism 30 at the first contact position T1, and the first angle θ 12, which are input in advance.

In addition, in the phase calculation process (S4), it is necessary to position the first traverse base 15 in the Z-axis direction so that the contact probe 40 can contact the eccentric portion Wa of the workpiece W. The position of the first traverse base 15 in the Z-axis direction may be determined based on information such as the shape of the workpiece W, or may be determined based on detection information that causes the contact probe 40 to move in the Z-axis direction and come into contact with the workpiece W. In addition, although the moving mechanism is a ball screw mechanism as described above, a linear motor may be used.

As described above, the controller 25 rotates the workpiece W while swinging the parallel link mechanism 30, thereby bringing the tip detection portion 41 of the contact probe 40 into contact with the eccentric portion Wa, and calculates the phase of the eccentric portion Wa based on the swing position of the parallel link mechanism 30 when the tip detection portion 41 comes into contact with the eccentric portion Wa and the rotation angles θ 12 and θ 22 of the support devices (the headstock 12, the chuck 13, and the tailstock 14).

The contact probe 40 is attached to the parallel link mechanism 30, and thus the contact probe 40 always maintains the same posture (a state of extending in a predetermined direction) regardless of the swing position of the parallel link mechanism 30. Therefore, when the tip detection portion 41 of the contact probe 40 is in contact with the eccentric portion Wa of the workpiece W, the posture of the contact probe 40 can be made constant. This enables a highly accurate contact position to be obtained.

Further, the contact probe 40 swings in conjunction with the swing of the parallel link mechanism 30. In other words, the locus 41a of the tip detection portion 41 of the contact probe 40 has an arc shape. Further, the parallel link mechanism 30 swings about an axis P7 parallel to the rotation axis P2 of the workpiece W. In other words, the distal end detection portion 41 of the contact probe 40 moves in an arc shape on a plane (X-Y plane) orthogonal to the rotation axis P2 (Z-axis direction) of the workpiece W. In other words, the distal end detection portion 41 of the contact probe 40 moves two-dimensionally on a plane orthogonal to the rotation axis P2 of the workpiece W.

Therefore, even if the eccentric amount and the size of the eccentric portion Wa are different in different types of workpieces W, the distal end detection portion 41 of the contact probe 40 can be reliably brought into contact with the eccentric portion Wa of the workpiece W. In other words, even if the kind of the work W is changed, setup adjustment for phase calculation is not required.

Further, the parallel link mechanism 30 and the contact probe 40 are provided to the first wheel head 16, and the contact probe 40 linearly moves in accordance with the linear movement of the first wheel head 16. In addition, the contact probe 40 is provided to extend in a direction intersecting the linear movement direction of the first wheel slide 16. Thus, the distal end detection portion 41 of the contact probe 40 can move in a wide range on a plane (X-Y plane) orthogonal to the rotation axis P2 (Z-axis direction) of the workpiece W. Therefore, the distal end detection portion 41 of the contact probe 40 can be brought into contact with the eccentric portion Wa more reliably for different types of workpieces W.

Further, when the first grinding wheel 17 grinds the workpiece W, the control device 25 swings the parallel link mechanism 30, thereby moving the contact probe 40 to the retreat position T3 apart from the contact position of the contact probe 40 and the eccentric portion Wa.

By moving the contact probe 40 to the retracted position T3, the contact probe 40 does not interfere with grinding of the first grinding wheel 17. Here, the contact probe 40 is provided to extend in a direction intersecting the linear movement direction of the first wheel slide 16. Therefore, the amount by which the contact probe 40 protrudes from the first grinding wheel base 16 toward the workpiece W can be reduced as compared to a case where the contact probe 40 extends in a direction parallel to the linear movement direction of the first grinding wheel base 16. Further, the angle of swinging the parallel link mechanism 30 can be reduced in order to move the contact probe 40 to the retracted position T3. As a result, the structure of the first wheel slide 16, the parallel link mechanism 30, and the like becomes simple and small.

The controller 25 causes the tip detection section 41 of the contact probe 40 to contact the eccentric section Wa at least at two positions T1, T2 of the contact probe 40. The controller 25 calculates the phase of the eccentric portion Wa based on the swing positions of the parallel link mechanism 30 at two positions where the tip end detecting portion 41 of the contact probe 40 comes into contact with the eccentric portion Wa and the rotation angles θ 12 and θ 22 of the support device (the headstock 12, the chuck 13, and the tailstock 14). Even if there is a difference in the outer diameter of the eccentric section Wa, the phase of the eccentric section Wa can be calculated with high accuracy by bringing the tip detection sections 41 of the contact probes 40 at two locations into contact with the eccentric section Wa.

When a plane connecting the center P7 of the circular arc trajectory 41a of the distal end detection section 41 of the contact probe 40 and the rotation axis P2 of the workpiece W is used as a reference, the distal end detection sections 41 of the contact probe 40 at two positions are symmetrical with respect to the reference plane. This makes it easy to calculate the eccentric section Wa, and improves the calculation accuracy.

Claims

1. A machine tool is characterized by comprising:

a support device that supports a workpiece having an eccentric portion eccentric with respect to a rotation axis of the workpiece so as to be rotatable about the rotation axis of the workpiece;

a parallel link mechanism provided swingably about an axis parallel to a rotation axis of the workpiece;

and a control device that swings the parallel link mechanism and rotates the workpiece, thereby rotating the workpiece around the rotation axis of the workpiece at positions of the contact type probe at least two places where the parallel link mechanism is swung around an axis parallel to the rotation axis of the workpiece, thereby bringing the tip detection portion of the contact type probe into contact with the eccentric portion, and calculating a phase of the eccentric portion around the rotation axis based on the swing positions of the parallel link mechanism at the at least two places where the tip detection portion is brought into contact with the eccentric portion and the rotation angle of the support device.

2. The machine tool of claim 1,

further comprises a moving table linearly moving in a direction intersecting with the rotation axis of the workpiece,

the parallel link mechanism is swingably provided to the moving stage,

the contact probe is provided to extend in a direction intersecting a linear movement direction of the moving stage.

3. The machine tool of claim 2,

further comprising a tool provided on the mobile station,

the control device swings the parallel link mechanism when the tool is used to machine the workpiece, thereby moving the contact probe to a retreat position away from a contact position between the contact probe and the eccentric portion.

4. A machine tool according to any one of claims 1 to 3,

with reference to a plane connecting the center of an arc locus of the tip detection portion of the contact probe and the rotation axis of the workpiece,

the tip end detection portions of the two contact probes are positioned symmetrically with respect to the plane as the reference.