Machine tool equipped with workpiece changer, and machining system

Abstract

[Problem] To provide a machine tool equipped with a workpiece changer capable of reducing machining cycle time by reducing non-machining time, and also provide a corresponding machining system. [Solution] A workpiece changer 4 comprises: first and second hands 5A, 5B having a pair of fingers 51, 52 that grip a workpiece 9 and an actuator 53 that rotates the pair of fingers 51, 52; an arm 61 to which the first and second hands 5A, 5B are attached; a rotary drive device 8 that rotates the arm 61 about a rotary axis O3; and a workpiece change control unit 302 that controls the actuator 53 and the rotary drive device 8. The workpiece change control unit 302 controls the rotary drive device 8 to rotate the arm 61 a half-turn between a first rotary position where the workpiece 9 can be set on first and second headstocks 35, 36 by the first hand 5A and a second rotary position where the workpiece 9 can be set on the first and second headstocks 35, 36 by the second hand 5B.

Description

Machine tool and machining system equipped with workpiece changer

[0001] The present invention relates to a machine tool equipped with a workpiece changer that changes a workpiece before machining for a workpiece after machining, and to a machining system using the machine tool.

[0002] Patent Document 1 describes a lathe equipped with a workpiece loading / unloading device that unloads a machined workpiece outside the machine and loads a next-machined workpiece into the machine. The workpiece loading / unloading device includes a workpiece holder that supports the machined workpiece and the next-machined workpiece, and a workpiece loader that unloads the machined workpiece supported by the workpiece holder and supplies the next-machined workpiece to the workpiece holder. The workpiece holder includes a support member having a first support portion that supports the machined workpiece and a second support portion that supports the next-machined workpiece, and is configured to move between a workpiece receiving position that receives the machined workpiece and a position outside the machining area. When machining of the workpiece is completed, the support member moves to the workpiece receiving position, receives the machined workpiece on the first support portion, and moves outside the machine. The workloader includes a first workpiece gripping portion that grips the machined workpiece supported by the first support portion and a second workpiece gripping portion that places the previously gripped next-machined workpiece on the second support portion, and transfers the machined workpiece and the next-machined workpiece between the support member of the workpiece holder. Thereafter, the support member moves, and the next workpiece placed on the second support portion is attached to the spindle, and the next workpiece is machined.

[0003] Patent Document 2 describes a lathe in which two steady rests for gripping a workpiece during machining are attached to both ends of a mounting arm. During machining of the workpiece, one of the two steady rests grips the workpiece, while the other grips a workpiece fed by a conveyor. When machining of the workpiece is completed, the mounting arm rotates 180 degrees, and the workpiece fed by the conveyor is transported to the machining position, and the completed workpiece is transported onto the conveyor.

[0004] JP 2007-105846 A JP 61-121852 A

[0005] In the system described in Patent Document 1, the time during which the machined workpiece and the next machined workpiece are transferred between the work holder and the work loader is non-machining time during which the workpiece cannot be machined. Also, in the system described in Patent Document 2, the workpiece before machining can be swapped with the machined workpiece by rotating the mounting arm, which shortens the time required to change the workpiece, but there is a risk of restrictions being placed on the machining location of the workpiece because it is necessary to avoid interference between the steady rest and tools, etc.

[0006] Therefore, the present invention aims to provide a machine tool and a machining system equipped with a workpiece exchange device that can easily avoid interference between the workpiece exchange device and tools, etc., while shortening the machining cycle time by reducing non-machining time.

[0007] In order to achieve the above-mentioned object, the present invention provides a machine tool including a tool for machining a workpiece, a workpiece holding device that holds the workpiece and drives it to rotate, and a feed device that moves the tool toward and away from the workpiece, the machine tool further including a work changer that exchanges the workpiece between the workpiece holding device and the workpiece, the work changer including first and second hands having a pair of fingers that grip the workpiece and an actuator that rotates the pair of fingers, an arm to which the first and second hands are attached, a rotation drive device that rotates the arm about a rotation axis, and a control unit that controls the actuator and the rotation drive device, the first and second hands being attached to two positions on the arm that are sandwiched between the rotation axis, The control unit controls the rotation drive device to rotate the arm half a turn between a first rotation position where the first hand can set the workpiece on the workpiece holding device and a second rotation position where the second hand can set the workpiece on the workpiece holding device, and controls the actuator to open the pair of fingers that have been holding the workpiece before machining after setting the workpiece on the workpiece holding device to a position that avoids interference with components of the machine tool including the tool, and to close the pair of fingers to hold the machined workpiece after machining of the workpiece is completed and the feed device moves the tool away from the workpiece.

[0008] Furthermore, in order to achieve the above-mentioned object, the present invention provides a machining system comprising a machine tool equipped with the above-mentioned workpiece exchange device, and a loader that transports the workpiece between a plurality of machine tools, wherein the control unit sets the workpiece on the workpiece holding device with one of the first and second hands, and then controls the actuator of the other of the first and second hands to transfer the workpiece between the loader and the other hand until machining of the workpiece set on the workpiece holding device is completed.

[0009] According to the machine tool and machining system equipped with the workpiece exchange device of the present invention, it is possible to easily avoid interference between the workpiece exchange device and tools, etc., while also shortening the machining cycle time by reducing non-machining time.

[0010] FIG. 1 is a schematic diagram showing an example of the configuration of a machining system according to an embodiment of the present invention. FIG. 2A is a configuration diagram showing some components of a machine tool indicated by a two-dot chain line. FIG. 2B is a configuration diagram showing some components of the machine tool omitted. FIG. 2A is a configuration diagram showing some components of the machine tool including a workpiece changer, viewed from a direction parallel to the rotation axis of a workpiece. FIG. 5A is a configuration diagram showing one end of a first hand and an arm. FIG. 5B is a configuration diagram showing one end of a first hand and an arm. FIG. 6A is a cross-sectional view showing an example of the configuration of a rotation drive device. FIG. 6B is a cross-sectional view showing an example of the configuration of a rotation drive device. FIG. 7A is a configuration diagram showing an example of the configuration of a rotation stopper unit for positioning the arm in the rotational direction. FIG. 7B is a cross-sectional view taken along line A-A in FIG. 7A. FIG. 7B is a cross-sectional view showing the configuration of a fixing mechanism.

[0011] [Embodiments] The following describes embodiments of the present invention with reference to the drawings. The embodiments described below are shown as preferred specific examples for carrying out the present invention, and while some of the embodiments specifically exemplify various technically preferred aspects, the technical scope of the present invention is not limited to these specific embodiments.

[0012] Fig. 1 is a configuration diagram showing an example of the configuration of a processing system 1 according to an embodiment of the present invention. Fig. 2A is a configuration diagram showing some components of the processing system 1 by two-dot chain lines. Fig. 2B is a configuration diagram showing some components of the processing system 1 without showing them.

[0013] The machining system 1 includes a plurality of machine tools and a loader 10 that transports workpieces 9 between the plurality of machine tools. The machining system 1 includes, as the plurality of machine tools, machine tools 21 and 22 that perform pre- and post-grinding processes, and a grinding machine 3 that performs grinding. The grinding machine 3 is controlled by a control device 300 and performs grinding of the workpieces 9. The grinding machine 3 also includes a workpiece changer 4 that transfers the workpieces 9 between the grinding machine 3 and the loader 10.

[0014] The loader 10 transports the workpiece 9 from the machine tool 21 that performs the pre-grinding process to the grinding machine 3, and also transports the workpiece 9 that has been ground by the grinding machine 3 to the machine tool 22 that performs the post-grinding process.

[0015] The grinding machine 3 rotates the workpiece 9 and presses a grinding wheel 30 as a tool against the workpiece 9 to perform grinding. １ The horizontal direction along the Z-axis is defined as the Z-axis direction, and the horizontal direction perpendicular to the Z-axis is defined as the X-axis direction. The vertical direction perpendicular to the Z-axis and X-axis is defined as the Y-axis direction. The grinding machine 3 grinds the workpiece 9 by moving the grinding wheel 30 back and forth in the X-axis direction relative to the workpiece 9.

[0016] The grinding machine 3 comprises a bed 31 serving as a base, a traverse table 32 movable in the Z-axis direction relative to the bed 31, a grinding wheel head base 33 movable in the X-axis direction relative to the traverse table 32, a grinding wheel head body 34 attached to the grinding wheel head base 33, first and second headstocks 35, 36 serving as workpiece holding devices that hold and rotate the workpiece 9, and a sizing device 37 that measures the outer diameter of the workpiece 9.

[0017] The first and second headstocks 35, 36 respectively have headstock motors 351, 361 that generate torque to rotate the workpiece 9, and centers 352, 362 that hold the workpiece 9 by sandwiching it in the axial direction. The pair of centers 352, 362 have their tip ends fitted into center holes formed in the axial end faces of the workpiece 9 to position the workpiece 9, and also rotate the workpiece 9 by the torque of the headstock motors 351, 361.

[0018] The bed 31 is provided with Z-axis guide rails 321, 322 that guide the traverse table 32 in the Z-axis direction, and the traverse table 32 moves along the Z-axis guide rails 321, 322 by rotation of a ball screw 324 driven by a Z-axis motor 323. The traverse table 32 is provided with X-axis guide rails 331, 332 that guide the wheel head base 33, and the wheel head base 33 moves along the X-axis guide rails 331, 332 relative to the traverse table 32 by rotation of a ball screw 334 driven by an X-axis motor 333. The X-axis guide rails 331, 332, X-axis motor 333, and ball screw 334 constitute a feed device that moves the grinding wheel 30 toward or away from the workpiece 9.

[0019] The wheel head body 34 has a housing 340 fixed to the wheel head base 33, and a wheel drive motor 341 is accommodated in the housing 340 as a built-in motor. The wheel drive motor 341 rotates the wheel 30 via a wheel spindle 342 supported by a bearing in the housing 340. The wheel 30 is driven to rotate by the wheel drive motor 341 to grind the workpiece 9. The rotation axis O of the wheel 30 ２ is the rotation axis O of the workpiece 9 １ is parallel to

[0020] 3 and 4 show a part of the loader 10, the grinding wheel 30, the wheel head base 33, the grinding wheel motor 341, the first headstock 35, the sizing device 37, the workpiece 9, and the workpiece changer 4 as viewed from the Z-axis direction, along with the coolant nozzle 19 that supplies coolant to the grinding location of the workpiece 9. The coolant nozzle 19 moves in the X-axis and Z-axis directions together with the wheel head base 33. Fig. 3 shows the state immediately before grinding the workpiece 9. Fig. 4 shows the state during grinding.

[0021] 1, the loader 10 has three-axis drive motors 101 to 103, and is capable of traveling along a rail 100 and moving a loader hand 104 in a vertical direction and a horizontal direction perpendicular to the rail 100. The rail 100 crosses above the machine tool 2, and part of the rail 100 is not shown in FIG.

[0022] The loader hand 104 of the loader 10 has first and second gripping portions 105, 106 for gripping a workpiece 9, and is capable of simultaneously transporting two workpieces 9 using the first and second gripping portions 105, 106. The loader 10 also has a loader arm 107 extending vertically and a wrist portion 108 that can rotate the loader hand 104 180° relative to the lower end of the loader arm 107. The axis O of rotation of the loader hand 104 by the wrist portion 108 is inclined 45° relative to the vertical. When the loader hand 104 is rotated 180° by the wrist portion 108, the first gripping portion 105 and the second gripping portion 106 are interchanged. When the loader hand 104 is rotated by the wrist portion 108, the loader arm 107 rises to prevent interference.

[0023] The sizing device 37 includes a sizing device main body 370, a first measuring head 371 having a first stylus 371a at its tip, a second measuring head 372 having a second stylus 372a at its tip, and a moving mechanism 38 that moves the sizing device main body 370 together with the first measuring head 371 and the second measuring head 372. The sizing device 37 holds the workpiece 9 between the first measuring head 371 and the second measuring head 372, and detects the outer diameter of the workpiece 9 by bringing the first stylus 371a and the second stylus 372a into contact with the surface of the workpiece 9. Information on the detection results by the sizing device 37 is sent to the control device 300. The grinding of the workpiece 9 is performed while the sizing device 37 measures the outer diameter of the portion ground by the grinding wheel 30.

[0024] The moving mechanism 38 moves the sizing device main body 370 in the Z-axis direction, and moves the sizing device main body 370 toward and away from the workpiece 9 along a moving direction inclined with respect to the X-axis and Y-axis directions. In Figures 3 and 4, the direction of approach and separation of the sizing device main body 370 is indicated by arrow D １ The approaching and retracting direction of the sizing device main body 370 is inclined downward in the vertical direction as it moves away from the workpiece 9 with respect to the X-axis direction, which is the approaching and retracting direction of the grinding wheel 30 due to the rotation of the X-axis motor 333. Also, the sizing device main body 370 moves downward in the vertical direction as it moves away from the workpiece 9. ３ In the Y-axis direction, the

[0025] 2B, the moving mechanism 38 includes a moving table 381, a ball screw 382, ​​a guide rail 383, a sizing device moving motor 384 that rotates the ball screw 382, ​​and a first slide table 385. As shown in FIGS. 3 and 4, the moving mechanism 38 includes a ball screw nut 386, a hydraulic cylinder 387, and a drive shaft 388 that is driven by the hydraulic cylinder 387 in the direction of arrow D. １ and a second slide table 388 that moves in the first direction. The ball screw nut 386 is threadedly engaged with the ball screw 382 via a plurality of balls.

[0026] The movable table 381 is fixed to the bed 31. The ball screw 382 and guide rail 383 extend in the Z-axis direction and are supported by the movable table 381. A ball screw nut 386 is fixed to the first slide table 385, and when the sizing device moving motor 384 rotates the ball screw 382, ​​the first slide table 385 is guided by the guide rail 383 and moves in the Z-axis direction. An upper surface 385a of the first slide table 385 is a guide surface inclined with respect to the X-axis direction and the Y-axis direction, and the second slide table 388 moves along this upper surface 385a. The sizing device main body 370 is fixed to the second slide table 388.

[0027] The moving mechanism 38 moves the sizing device 37 between the retracted position shown in Fig. 3 and the measurement position shown in Fig. 4. When moving the sizing device 37 from the retracted position to the measurement position, the hydraulic cylinder 387 advances the second slide table 388 toward the workpiece 9 along the upper surface 385a of the first slide table 385. During this advancement, the sizing device 37 also moves in the Y-axis direction, and rises vertically as it approaches the workpiece 9.

[0028] The sizing device 37 has a center line C perpendicular to the arrangement direction of the first measuring head 371 and the second measuring head 372 inclined with respect to the X-axis direction and the Y-axis direction, similar to the upper surface 385a of the first slide table 385. This inclined posture of the sizing device 37 contributes to making it easier to avoid interference with the first and second hands 5A and 5B of the workpiece exchange device 4, which will be described later.

[0029] The control device 300 has a machining control section 301 that controls the moving parts of the grinding machine 3 to machine the workpiece 9, and a workpiece change control section 302 that controls the moving parts of the workpiece changer 4. The machining control section 301 controls the Z-axis motor 323, the X-axis motor 333, the grinding wheel motor 341, the headstock motors 351 and 361, the sizing device moving motor 384, and the hydraulic cylinder 387. In this embodiment, the machining control section 301 and the workpiece change control section 302 are included in one control device 300, but the machining control section 301 and the workpiece change control section 302 may be separate, independent entities. The workpiece change control section 302 is a component of the workpiece changer 4.

[0030] 2B, the workpiece 9 integrally includes a first processed portion 91 and a second processed portion 92 to be ground by the grinding wheel 30, an intermediate portion 93 between the first processed portion 91 and the second processed portion 92, a cylindrical portion 94 at one end on the first headstock 35 side, and a cylindrical portion 95 at the other end on the second headstock 35 side. The first processed portion 91 and the second processed portion 92 are aligned with each other on the rotation axis O. １ The intermediate portion 93 is a non-machined portion that is not ground, and has an outer diameter smaller than the outer diameters of the first and second machined portions 91, 92. When machining the workpiece 9, after the first machined portion 91 is ground, the traverse table 32 is moved in the Z-axis direction, and the second machined portion 92 is ground.

[0031] The workpiece changer 4 receives the unmachined workpiece 9 from the loader 10 and sets it on the first and second headstocks 35, 36. The workpiece changer 4 also removes the machined workpiece 9 from the first and second headstocks 35, 36 and delivers it to the loader 10.

[0032] The workpiece exchange device 4 includes first and second hands 5A and 5B, an arm 61 to which the first and second hands 5A and 5B are attached, a shaft 62 that rotates integrally with the arm 61, a fixing mechanism 7 that fixes the arm 61 to the shaft 62, and a rotation axis O of the arm 61 and the shaft 62 together with the fixing mechanism 7. ３The rotational axis O of the arm 61 and the shaft 62 is a center of rotation of the workpiece change control unit 302. ３ is the rotation axis O of the workpiece 9 １ and the rotation axis O of the workpiece 9. １ It is located vertically higher than

[0033] The arm 61 has a rotation axis O ３ The arm 61 is a long, flat plate whose longitudinal direction is perpendicular to the X-axis. ３ The position of is farther from the grinding wheel 30 than the positions of the pair of centers 352, 362 of the first and second headstocks 35, 36 in the X-axis direction, i.e., the holding position of the workpiece 9. The workpiece 9 is located in the X-axis direction along the axis of rotation O of the grinding wheel 30 and the arm 61. ３ It is set between

[0034] The first and second hands 5A and 5B are aligned along a rotation axis O. ３ In this embodiment, the first hand 5A is fixed to one end of the arm 61, and the second hand 5B is fixed to the other end of the arm 61. ３ the distance from the first hand 5A to the rotation axis O ３ The distances from the first hand 5A to the second hand 5B are equal, and the first hand 5A and the second hand 5B are interchanged by the arm 61 rotating half a turn.

[0035] 5A and 5B are configuration diagrams showing the first hand 5A and one end of the arm 61. Fig. 5A shows a state in which the first hand 5A is gripping a workpiece 9, and Fig. 5B shows a state in which the first hand 5A is not gripping a workpiece 9. In Figs. 5A and 5B, a portion of the first hand 5A is broken away to show the internal structure. The second hand 5B is configured in the same manner as the first hand 5A.

[0036] The first hand 5A has a pair of fingers 51, 52 that grip the workpiece 9, an actuator 53 that rotates the pair of fingers 51, 52, and a case 54 that houses the actuator 53. The actuator 53 includes a rack shaft 531 disposed between the pair of fingers 51, 52 and a cylinder 532 that moves the rack shaft 531 back and forth, and is configured so that the pair of fingers 51, 52 rotates as the rack shaft 531 moves back and forth. The same applies to the second hand 5B. The case 54 is fastened to the arm 61 by, for example, bolts.

[0037] The moving direction of the rack shaft 531 is inclined with respect to the longitudinal direction of the arm 61. In FIG. 5A, the moving direction of the rack shaft 531 relative to the case 54 is indicated by a dashed line D ２ and the axis of rotation O ３ The longitudinal direction of the arm 61 perpendicular to the arrow D ３ The inclination angle θ of the moving direction of the rack shaft 531 relative to the longitudinal direction of the arm 61 １ is set at an angle that can avoid interference between the first hand 5A and the sizing device 37 and the coolant nozzle 19. When the moving direction of the rack shaft 531 is the direction of the central axes of the first and second hands 5A and 5B, the direction of inclination of the central axes of the first and second hands 5A and 5B with respect to the longitudinal direction of the arm 61 is set at an angle that can avoid interference between the first hand 5A and the sizing device 37 and the coolant nozzle 19. ３ The workpiece 9 is set at a position closer to the grinding wheel 30 in the X-axis direction than the rotation axis O of the arm 61. ３ This is the direction in which the workpiece 9 is transferred to and from the loader 10 at a position on the opposite side of the grinding wheel 30 in the X-axis direction.

[0038] The pair of fingers 51, 52 each have a plurality of claws 511, 521 for gripping the workpiece 9. Pinion gears 512, 522 are integrally attached to the base ends of the pair of fingers 51, 52 by welding or the like. The pinion gears 512, 522 have pinion teeth 512a, 522a that mesh with rack teeth 531a of the rack shaft 531. Bifurcated support portions 541, 542 are formed at one end of the case 54 and protrude toward the opposite side from the rack shaft 531. The pinion gears 512, 522 are housed in the space between the bifurcated support portions 541, 542. Support shafts 543, 544 are press-fitted and fixed into the support portions 541, 542, and the support shafts 543, 544 are clearance-fitted into the pinion gears 512, 522. The pair of fingers 51, 52 are rotatably supported by supports 541, 542 via support shafts 543, 544. As the rack shaft 531 moves, the pair of fingers 51, 52 rotate in opposite directions around the support shafts 543, 544.

[0039] The closing operation of the first hand 5A is performed by moving the rack shaft 531 to the rear end as shown in Fig. 5A. The opening operation of the first hand 5A is performed by moving the rack shaft 531 to the forward end as shown in Fig. 5B. A piston portion 531b provided on the rack shaft 531 is housed in the cylinder 532, and the rack shaft 531 is moved backward by supplying compressed air as a working medium to one side of the piston portion 531b, and the rack shaft 531 is moved forward by supplying compressed air as a working medium to the other side of the piston portion 531b. As shown in Fig. 5B, the opening angle θ of the pair of fingers 51, 52 when the first hand 5A is opened is ２ is greater than 180°. As a result, when the pair of fingers 51, 52 open to release the workpiece 9, the pair of fingers 51, 52 rotate to a side farther from the workpiece 9 than the support shafts 543, 544. In the example shown in FIG. 5B , the opening angle θ ２ When the pair of fingers 51 and 52 are opened, a portion of each of the pair of fingers 51 and 52 overlaps with the arm 61 when viewed in the Z-axis direction.

[0040] In this embodiment, the workpiece change control unit 302 controls the actuators 53 of the first and second hands 5A and 5B by supplying compressed air to the cylinders 532. However, the actuators 53 are not limited to those that use compressed air, and may be those that use hydraulic oil as a working medium, or those that use an electric motor.

[0041] 6A and 6B are cross-sectional views showing an example configuration of the rotation drive device 8. Fig. 7A is a configuration diagram showing an example configuration of a rotation stopper portion 80 for positioning the arm 61 in the rotation direction. Fig. 7B is a cross-sectional view taken along line A-A in Fig. 7A. In this embodiment, similar to the first and second hands 5A and 5B, the rotation drive device 8 is operated using compressed air as the working medium.

[0042] The rotary drive device 8 has a housing 81 in which first and second cylinder chambers 811, 812 are formed, a first piston member 82 housed in the first cylinder chamber 811, a second piston member 83 housed in the second cylinder chamber 812, a pinion gear 84 arranged between the first piston member 82 and the second piston member 83, and first and second ports 851, 852 to which compressed air is supplied.

[0043] 1 and 2A, the housing 81 is fixed to the front part of the bed 31 on the operator's side by a support member 311. In the example shown in FIGS. 1 and 2A, the attachment part 311a of the support member 311 is fixed directly to the bed 31, but the support member 311 may be fixed to the bed 31 via another member.

[0044] As shown in FIG. 7B, the shaft 62 is inserted into a through-hole 311b formed in the support member 311, and is aligned with the rotation axis O together with the arm 61. ３The shaft 62 is a hollow cylinder having a space 620 formed in the center thereof. This space 620 accommodates a plurality of tubes 530 for supplying compressed air to the actuators 53 of the first and second hands 5A and 5B. As shown in FIGS. 3 and 4, the plurality of tubes 530 extend from the tip of the shaft 62 on the side opposite to the rotation drive device 8 and are connected to the first and second hands 5A and 5B, respectively. Note that the plurality of tubes 530 are not shown in the drawings other than FIGS. 3, 4, and 7B.

[0045] The housing 81 of the rotation drive device 8 has a partition wall 813 that separates the first cylinder chamber 811 and the second cylinder chamber 812, and an accommodating portion 813a that accommodates the pinion gear 74 is formed in this partition wall 813. The pinion gear 74 is coaxially connected to the shaft 62, and rotation of the pinion gear 74 rotates the shaft 62. A plurality of rack teeth 821, 831 that mesh with the pinion gear 74 are formed on the first and second piston members 82, 83, respectively.

[0046] 6A and 6B, the left-right direction in the drawings corresponds to the X-axis direction. The first and second cylinder chambers 811, 812 are formed to extend in the X-axis direction, and compressed air supplied to the first and second ports 851, 852 moves the first and second piston members 82, 83 toward the grinding wheel 30 in the X-axis direction. FIG. 6A shows a state in which compressed air is supplied to the first port 851, and FIG. 6A shows a state in which compressed air is supplied to the second port 852. The first and second piston members 82, 83 move in opposite directions across the pinion gear 74, rotating the pinion gear 74. The workpiece change control unit 302 controls the rotation drive device 8 by switching the compressed air supply destination between the first port 851 and the second port 852.

[0047] As shown in Figures 7A and 7B, the rotation stopper portion 80 comprises a disk-shaped disk 800 fixed coaxially to the shaft 62, a stopper 802 fixed to the disk 800 by a plurality of bolts 801, first and second L-shaped mounting brackets 804, 805 fixed to the support member 311 by a plurality of bolts 803, a first abutment member 806 inserted into the first mounting bracket 804, a second abutment member 807 inserted into the second mounting bracket 805, a pair of nuts 808 that fix the first abutment member 806 to the first mounting bracket 804, and a pair of nuts 809 that fix the second abutment member 807 to the second mounting bracket 805.

[0048] The disk 800 and the stopper 802 rotate integrally with the shaft 62. The arm 61 and the shaft 62 can rotate 180° between a first rotation position where the stopper 802 abuts against a first abutment member 806 and a second rotation position where the stopper 802 abuts against a second abutment member 807. The rotation stopper unit 80 can adjust both ends of the 180° rotation in the direction of rotation of the arm 61 and the shaft 62 by adjusting the position where the first abutment member 806 is fixed to the first mounting bracket 804 and the position where the second abutment member 807 is fixed to the second mounting bracket 805. In FIG. 7A , the stopper 802 abutting against the first abutment member 806 is indicated by a solid line, and the stopper 802 abutting against the second abutment member 807 is indicated by a two-dot chain line.

[0049] When the arm 61 is in the first rotation position, as shown in Fig. 3, the first hand 5A can set the unmachined workpiece 9 on the first and second headstocks 35, 36. When the arm 61 is in the second rotation position, the second hand 5B can set the unmachined workpiece 9 on the first and second headstocks 35, 36. The workpiece change control unit 302 controls the rotation drive device 8 to rotate the arm 61 a half turn between the first and second rotation positions every time machining of one workpiece 9 is completed.

[0050] 8 is a cross-sectional view showing the configuration of the fixing mechanism 7. The fixing mechanism 7 can fix the arm 61 at any position in the longitudinal direction of the shaft 62 depending on the shape of the workpiece 9, etc. In this embodiment, the arm 61 is fixed at a position where the pair of fingers 51, 52 of the first and second hands 5A, 5B can grip the middle portion 93 of the workpiece 9 held on the first and second headstocks 35, 36.

[0051] The fixing mechanism 7 is disposed between the inner peripheral surface 611a of the protrusion 611 of the arm 61 and the outer peripheral surface 62a of the shaft 62 and serves to fix the arm 61 to the shaft 62 so as to be movable in the axial direction. The fixing mechanism 7 includes a cylindrical outer diameter side fitting member 71 that is elastically deformable in the radial direction and is disposed on the inner diameter side of the inner peripheral surface 611a of the protrusion 611 of the arm 61; an inner diameter side fitting member 72 that is elastically deformable in the radial direction and disposed on the outer diameter side of the outer peripheral surface 62a of the shaft 62 and is axially movable relative to the shaft 62; and a plurality of clamp bolts 73 that move the outer diameter side fitting member 71 in the axial direction relative to the inner diameter side fitting member 72. The outer diameter side fitting member 71 and the inner diameter side fitting member 72 form a double cylindrical structure. A through hole 61a through which the shaft 62 is inserted is formed in the arm 61, and a cylindrical protrusion 611 is provided on the outer diameter side of the through hole 61a. An inner peripheral surface 71 a of the outer diameter side fitting member 71 is a tapered surface that is inclined with respect to the axial direction of the shaft 62 .

[0052] The inner diameter side fitting member 72 has an inner cylindrical portion 721 having a tapered outer peripheral surface 721a facing the inner peripheral surface 71a of the outer diameter side fitting member 71, a wall portion 722 formed with a plurality of bolt insertion holes 722a through which a plurality of clamp bolts 73 are inserted, and an outer peripheral cylindrical portion 723 covering the outer peripheral surface 71b of the outer diameter side fitting member 71. Threaded holes 711 are formed in the outer diameter side fitting member 71 at positions aligned with the plurality of bolt insertion holes 722a of the inner diameter side fitting member 72. Each clamp bolt 73 is inserted into the bolt insertion hole 722a of the inner diameter side fitting member 72 and threadedly engages with the threaded hole 711 of the outer diameter side fitting member 71.

[0053] When fixing the arm 61 to the shaft 62, the clamp bolt 73 is tightened, and the axial force of the clamp bolt 73 draws the protrusion 611 of the arm 61 and the outer diameter side fitting member 71 toward the inner diameter side fitting member 72. As a result, the outer diameter side fitting member 71 expands in diameter, and the outer peripheral surface 71b of the outer diameter side fitting member 71 is pressed against the inner peripheral surface 611a of the protrusion 611 of the arm 61, and the inner diameter side fitting member 72 contracts in diameter, and the inner peripheral surface 721b of the inner cylindrical portion 721 is pressed against the outer peripheral surface 62a of the shaft 62. Then, the arm 61 is fixed to the shaft 62 by the frictional force generated between the inner peripheral surface 721b of the inner cylindrical portion 721 and the outer peripheral surface 62a of the shaft 62.

[0054] Next, we will explain the procedure for continuously machining a plurality of workpieces 9 by the machine tool 2. The machine tool 2 rotates the arm 61 to quickly switch the workpiece 9 held by the first hand 5A with the workpiece 9 held by the second hand 5B, thereby reducing non-machining time and shortening the cycle time.

[0055] More specifically, for example, while the first hand 5A is processing the workpiece 9 it has held, the second hand 5B delivers the already processed workpiece 9 to the loader 10. Then, the loader arm 107 is lifted once, and the loader hand 104 is rotated 180° by the wrist 108, and the unprocessed workpiece 9 is delivered from the loader 10 to the second hand 5B. At this time, the first hand 5A moves in the same direction as the rotation axis O. ３ The second hand 5B is positioned vertically below the rotation axis O ３ After that, when the machining of the workpiece 9 held by the first hand 5A is completed, the workpiece 9 is held by the first hand 5A, and the arm 61 is rotated to set the workpiece 9 held by the second hand 5B on the first and second headstocks 35, 36. The machined workpiece 9 is then transferred from the first hand 5A to the loader 10.

[0056] While the workpiece 9 is being transferred between the second hand 5B and the loader 10, the first hand 5A must be kept waiting near the first and second headstocks 35, 36. As described above, the workpiece 9 is machined by sequentially moving the traverse table 32 in the Z-axis direction to machine the first workpiece portion 91 and the second workpiece portion 92, which sandwich the intermediate portion 93. Therefore, it is necessary to avoid interference between the grinding wheel 30 and the coolant nozzle 19 and the first hand 5A when the traverse table 32 moves. Furthermore, since the sizing device main body 370 and the first and second measuring heads 371 and 372 also move in the Z-axis direction as the traverse table 32 moves, it is also necessary to avoid interference between the sizing device main body 370 and the first and second measuring heads 371 and 372 and the first hand 5A.

[0057] For this reason, the workpiece change control unit 302 controls the actuators 53 of the first and second hands 5A and 5B so that, after the unmachined workpiece 9 is set on the first and second headstocks 35 and 36, the pair of fingers 51 and 52 that have been gripping the workpiece 9 are opened to a position that avoids interference with the components of the machine tool 2, and after the machining of the workpiece 9 is completed and the grinding wheel 30 is moved away from the workpiece 9 by the X-axis motor 333, the pair of fingers 51 and 52 are closed to grip the machined workpiece 9. Here, the components of the machine tool 2 specifically refer to the grinding wheel 30, the coolant nozzle 19, and the sizing device 37. In other words, after the first and second hands 5A, 5B set the workpiece 9 on the first and second headstocks 35, 36, the pair of fingers 51, 52 are opened wide to a position where interference with the grinding wheel 30, coolant nozzle 19, and sizing device 37 can be avoided.

[0058] Furthermore, after the workpiece 9 is set on the first and second headstocks 35 and 36 by one of the first and second hands 5A and 5B, the workpiece exchange control unit 302 controls the actuator 53 of the other of the first and second hands 5A and 5B to transfer the workpiece 9 to and from the loader 10 until machining of the set workpiece 9 is completed. This makes it possible to quickly exchange the unmachined workpiece 9 for a machined workpiece 9, thereby shortening the cycle time. In other words, according to the present embodiment described above, it is possible to shorten the machining cycle time by reducing non-machining time.

[0059] (Note) While the present invention has been described above based on the embodiments, the invention as claimed is not limited to these embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. The present invention can be appropriately modified by omitting some components or adding or substituting components without departing from the spirit of the invention. While the above embodiments have been described using a grinding machine as an example, the present invention is not limited to this, and can also be applied to cutting machines and assembly machines, for example.

[0060] DESCRIPTION OF SYMBOLS 1... Machining system 10... Loader 2... Grinding machine (machine tool) 302... Workpiece change control unit 30... Grinding wheel (tool) 331, 332... X-axis guide rail (feeding device) 333... X-axis motor (feeding device) 334... Ball screw (feeding device) 35, 36... First and second spindles (workpiece holding device) 37... Sizing device 370... Sizing device main body 371... First measuring head 372... Second measuring head 38... Moving mechanism 4... Workpiece changer 51, 52... Fingers 53... Actuator 5A... First hand 5B... Second hand 61... Arm 8... Rotation drive device 9... Workpiece

Claims

1. A machine tool comprising: a tool for machining a workpiece; a workpiece holding device that holds the workpiece and rotates it about a horizontal rotation axis; and a feed device that moves the tool toward and away from the workpiece held by the workpiece holding device in a horizontal direction intersecting the rotation axis of the workpiece, a workpiece exchange device for exchanging the workpiece between the workpiece holding device and the workpiece exchange device, The workpiece changer includes: a first hand and a second hand each having a pair of fingers for gripping the workpiece and an actuator for rotating the pair of fingers; an arm to which the first and second hands are attached; a rotation drive device that rotates the arm about a rotation axis parallel to the rotation axis of the workpiece; a control unit for controlling the actuator and the rotary drive device, the first and second hands are attached to two positions of the arm that are symmetrical with respect to a rotation axis of the arm, The control unit is controlling the rotation drive device to rotate the arm half a turn between a first rotation position where the workpiece can be set on the workpiece holding device by the first hand and a second rotation position where the workpiece can be set on the workpiece holding device by the second hand; controlling the actuator so that after the workpiece to be machined is set on the workpiece holding device, the pair of fingers that have been holding the workpiece are opened to a position that avoids interference with components of the machine tool including the tool, and after the machining of the workpiece is completed and the tool is moved away from the workpiece by the feed device, the pair of fingers are closed to hold the machined workpiece; The arm is a flat, long plate whose longitudinal direction is perpendicular to the axis of rotation of the arm, the control unit controls the actuator so that the longitudinal direction of the arm is a vertical direction at the first rotation position and the second rotation position; a position where the workpiece holding device holds the workpiece is on the tool side of a vertical line passing through a rotation axis of the arm, the first hand is attached at an angle with respect to the longitudinal direction of the arm such that a gripping position of the workpiece in the first rotation position is on the tool side of a vertical line passing through a rotation axis of the arm, the second hand is attached at an angle with respect to the longitudinal direction of the arm so that a gripping position of the workpiece in the second rotation position is on the tool side of a vertical line passing through a rotation axis of the arm. A machine tool equipped with a workpiece changer.

2. the tool is a grinding wheel, and the grinding process of the workpiece is performed while supplying coolant from a coolant nozzle to a portion of the workpiece to be ground and measuring an outer diameter of the portion to be ground by the grinding wheel with a sizing device; After the workpiece is set on the workpiece holding device, the pair of fingers are opened by the opening operation to a position where interference with the grindstone, the coolant nozzle, and the sizing device can be avoided. A machine tool comprising the workpiece changer according to claim 1.

3. The sizing device has a sizing device main body, a first measuring head having a first measuring element at its tip that contacts the workpiece, a second measuring head having a second measuring element at its tip that contacts the workpiece, and a moving mechanism for moving the sizing device main body toward and away from the workpiece, wherein the workpiece is sandwiched between the first measuring head and the second measuring head, and the first measuring element and the second measuring element are brought into contact with a surface of the workpiece to detect an outer diameter of the workpiece, The sizing device body is disposed vertically below the rotation axis of the arm, The approaching and moving away direction of the sizing device body is inclined in a direction that descends vertically as it moves away from the tool. A machine tool comprising the workpiece changer according to claim 2.

4. the actuator includes a rack shaft disposed between the pair of finger portions, a pair of pinion gears having pinion teeth that mesh with rack teeth of the rack shaft, and a cylinder that moves the rack shaft back and forth, and is configured such that the pair of finger portions rotate in opposite directions about a support shaft that supports the pair of pinion gears as the rack shaft moves back and forth, The moving direction of the rack shaft is inclined with respect to the longitudinal direction of the arm, In a direction in which the tool is moved toward or away from the feed device, a rotation axis of the arm is located farther from the grindstone than a holding position of the workpiece by the workpiece holding device. A machine tool comprising the workpiece changer according to claim 2 or 3.

5. The opening angle of the pair of fingers when the finger opening operation is performed is greater than 180°. A machine tool comprising the workpiece changer according to claim 4.

6. A machine tool equipped with the workpiece changer according to claim 1; a loader for transporting the workpiece between a plurality of machine tools, the control unit controls the actuator of the other hand of the first and second hands to transfer the workpiece between the loader and the other hand until the machining of the workpiece set on the workpiece holding device is completed after the workpiece is set on the workpiece holding device by one of the first and second hands. Processing system.