Machine tool, workpiece processing method and control program

Abstract

To provide a machine tool, a workpiece processing method, and a control program, which can smoothly perform cutting work of a connection part for connecting a first part and a second part on an intermediate workpiece including the first part, the second part, and the connection part.SOLUTION: A machine tool includes a tool rest 31 having a holder 36 capable of holding a workpiece, a tool main spindle 41, and a control device for controlling the machine tool. The control device controls the tool main spindle 41 so as to obtain an intermediate workpiece W' including a first part 160, a second pat 170, and a connection part 180 for connecting the first part 160 and the second part 170, controls the tool rest 31 so as to hold the first part 160 by the holder 36, and controls the tool main spindle 41 so as to cut the connection part 180 while holding the first part 160 by the holder 36.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a machine tool, a method for machining a workpiece, and a control program.

Background Art

[0002] For example, Japanese Patent No. 7033240 (Patent Document 1) discloses a machine tool including a tool spindle, a first spindle and a second spindle for holding a workpiece, and an articulated robot for transporting a workpiece (workpiece). The workpiece is machined such that the workpiece is provided with a necessary part that becomes a final part and a frame-shaped unnecessary part to which the necessary part is connected via a plurality of connecting parts. Further, while holding the workpiece with the hand of the articulated robot, the connecting part is cut to separate the necessary part from the unnecessary part.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the machine tool disclosed in Patent Document 1 above, the workpiece is held by the hand of the articulated robot during the cutting process of the connecting part. However, if the rigidity of the articulated robot or the gripping force of the workpiece by the hand is insufficient, the machining point of the workpiece by the tool may shift or the workpiece may fall off the hand during the cutting process of the connecting part.

[0005] An object of this invention is to provide a machine tool, a method for machining a workpiece, and a control program capable of smoothly performing the cutting process of a connecting part on an intermediate workpiece including a first part, a second part, and a connecting part connecting the first part and the second part.

Means for Solving the Problems

[0006] The machine tool according to the present invention includes a tool rest having a holder capable of holding a workpiece, a tool spindle, and a control device for controlling the machine tool. The control device controls the tool spindle so as to obtain an intermediate workpiece including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion by machining the workpiece, controls the tool rest so as to hold the first portion by the holder, and controls the tool spindle so as to cut the connecting portion while holding the first portion by the holder.

[0007] The method for machining a workpiece according to the present invention includes a step of obtaining an intermediate workpiece including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion by machining the workpiece, a step of holding the first portion by a holder attached to the tool rest, and a step of cutting the connecting portion while holding the first portion by the holder.

[0008] The control program according to the present invention is a control program for a machine tool including a tool rest. The control program causes the machine tool to perform a step of obtaining an intermediate workpiece including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion by machining the workpiece, a step of holding the first portion by a holder attached to the tool rest, and a step of cutting the connecting portion while holding the first portion by the holder.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a machine tool, a method for machining a workpiece, and a control program capable of smoothly performing cutting processing of a connecting portion on an intermediate workpiece including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0011] Embodiments of this invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are given the same numbers.

[0012] Fig. 1 is a front view showing the machine tool in the embodiments of this invention. In Fig. 1, the inside of the machine tool is shown by seeing through the cover body forming the appearance of the machine tool.

[0013] Referring to Fig. 1, the machine tool 100 is a composite machining machine equipped with both a milling function for performing workpiece processing by bringing a rotating tool into contact with a stationary workpiece and a turning function for performing workpiece processing by bringing a tool into contact with a rotating workpiece.

[0014] The machine tool 100 is an NC (Numerically Controlled) machine tool in which various operations for workpiece machining are automated by numerical control by a computer.

[0015] In this specification, for the convenience of explaining the configuration of the machine tool 100, an axis parallel to the rotation axis of the workpiece and extending in the horizontal direction is referred to as the "Z-axis", an axis orthogonal to the Z-axis and extending in the horizontal direction is referred to as the "Y-axis", and an axis extending in the vertical direction is referred to as the "X-axis".

[0016] The machine tool 100 includes a bed 16, a workpiece spindle 21, an opposing workpiece spindle 26, a tool spindle 41, a tool post 31, and a cover body 12. The workpiece spindle 21, the opposing workpiece spindle 26, the tool spindle 41, and the tool post 31 are arranged in the working area 210. The working area 210 is a space where workpiece machining is performed, and is sealed by the cover body 12 so that foreign matters such as chips or cutting oil accompanying workpiece machining do not leak outside the working area 210.

[0017] The bed 16 is a base member for supporting the workpiece spindle 21, the opposing workpiece spindle 26, the tool spindle 41, the tool post 31, etc., and is installed on the floor surface of a factory or the like. The bed 16 is made of metal such as a casting.

[0018] The workpiece spindle 21 and the opposing workpiece spindle 26 can hold a workpiece. The workpiece spindle 21 is rotationally driven by a motor about a rotation center axis 110 parallel to the Z-axis. The workpiece spindle 21 has a plurality of claw portions 22, and a chuck mechanism for detachably holding the workpiece is provided. Each claw portion 22 is slidably driven in the radial direction of the rotation center axis 110 by hydraulic pressure or the like. The plurality of claw portions 22 grip the outer peripheral surface of the workpiece by sliding inward in the radial direction of the rotation center axis 110, or grip the inner peripheral surface of the workpiece by sliding outward in the radial direction of the rotation center axis 110.

[0019] The opposed work spindle 26 is arranged to face the work spindle 21 in the Z-axis direction. The opposed work spindle 26 is rotationally driven by a motor about a rotation center axis 120 that is parallel to the Z-axis and extends in a straight line with the rotation center axis 110. The opposed work spindle 26 has a plurality of claw portions 27, and a chuck mechanism for detachably holding the work is provided. The plurality of claw portions 27 correspond to the plurality of claw portions 22 on the work spindle 21.

[0020] The work spindle 21 is fixed to the bed 16. The opposed work spindle 26 is movable in the Z-axis direction by various feed mechanisms, guide mechanisms, and motors.

[0021] The tool spindle 41 is capable of holding a tool. The tool spindle 41 is rotationally driven by a motor about a rotation center axis 140 that is parallel to the X-axis in a reference posture described later. A clamp mechanism (not shown) for detachably holding the tool is built into the tool spindle 41.

[0022] The tool spindle 41 is further pivotable about a pivot center axis 150 parallel to the Y-axis (B-axis pivot). The pivot center axis 150 intersects the rotation center axis 140. The pivot range of the tool spindle 41 is, for example, in the range of ±120° with reference to a reference posture in which the spindle end face 42 of the tool spindle 41 faces downward (the posture of the tool spindle 41 shown in FIG. 1).

[0023] The tool spindle 41 is movable in the X-axis direction, Y-axis direction, and Z-axis direction by various feed mechanisms, guide mechanisms, and motors. Although not shown in FIG. 1, around the work spindle 21, an automatic tool changer (ATC: Automatic Tool Changer) for automatically exchanging the tool held by the tool spindle 41 and a tool magazine for accommodating the replacement tool are provided.

[0024] The tool rest 31 can hold tools. The tool rest 31 is provided below the tool spindle 41. The tool spindle 41 is disposed on the upper side sandwiching the rotation center axis 110 of the work spindle 21 and the rotation center axis 120 of the opposed work spindle 26, and the tool rest 31 is disposed on the lower side sandwiching the rotation center axis 110 of the work spindle 21 and the rotation center axis 120 of the opposed work spindle 26. The tool rest 31 is of a so-called turret type, and a plurality of tools are radially attached and perform indexing rotation.

[0025] The tool rest 31 has a swivel part 32 and a plurality of tool holders (not shown). The swivel part 32 can swivel about a swivel center axis 130 parallel to the Z axis. The swivel part 32 as a whole has a disk shape in which the axial direction of the swivel center axis 130 is the thickness direction. The plurality of tool holders (not shown) can hold tools. The plurality of tool holders are attached to the outer peripheral surface of the swivel part 32. The plurality of tool holders are arranged in the circumferential direction of the swivel center axis 130. When the swivel part 32 swivels about the swivel center axis 130, the tool held by the tool holder moves in the circumferential direction. The tool used for workpiece machining is indexed to a position at a predetermined angle in the circumferential direction of the swivel center axis 130.

[0026] The machine tool 100 may further have an automatic tool changer for automatically changing the tool held by the tool rest 31. In this case, a clamping mechanism for automatically clamping and unclamping the tool may be incorporated in the tool rest 31 along with the automatic change of the tool held by the tool holder. Also, a milling function for rotating the tool held by the tool holder may be provided in the tool rest 31.

[0027] The tool rest 31 is movable in the X-axis direction and the Z-axis direction by various feed mechanisms, guide mechanisms, and motors.

[0028] FIG. 2 is a perspective view showing cutting of a connecting portion in an intermediate workpiece in the machine tool shown in FIG. 1. Referring to FIGS. 1 and 2, the tool rest 31 further has a holder 36. The holder 36 can hold a workpiece. The holder 36 is attached to the outer peripheral surface of the swivel part 32. The holder 36 is arranged in the circumferential direction of the swivel center axis 130 together with a plurality of tool holders.

[0029] The holder 36 consists of a clamping unit that automatically operates between a clamping state of clamping the workpiece and an unclamping state of unclamping the workpiece.

[0030] Regarding an example of the structure of the holder 36, the holder 36 has a holder base 37 and a pair of gripping claws 38. The pair of gripping claws 38 are attached to the holder base 37. The pair of gripping claws 38 face each other with a space therebetween. The pair of gripping claws 38 are guided so as to be slidable in the facing direction. The holder base 37 incorporates an actuator (corresponding to the actuator 74 in FIG. 3) for sliding the pair of gripping claws 38. The power source of the actuator is not particularly limited, and for example, it may be a motor or a hydraulic cylinder.

[0031] When the workpiece is placed between the pair of gripping claws 38 and the pair of gripping claws 38 slide in a direction approaching each other, a clamping state in which the workpiece is gripped by the pair of gripping claws 38 is obtained. When the pair of gripping claws 38 slide in a direction away from each other, an unclamping state in which the workpiece is released from the pair of gripping claws 38 is obtained.

[0032] Referring to FIG. 1, the machine tool 100 further includes a workpiece stocker 91 and a workpiece transfer mechanism 80. The workpiece stocker 91 is installed in an external area 220 outside the working area 210. The workpiece stocker 91 is adjacent to the working area 210 in the Z-axis direction. The workpiece stocker 91 can store workpieces W before and after processing. In FIG. 1, a table on which the workpiece W can be placed is shown as the workpiece stocker 91, but the form of the workpiece stocker 91 is not particularly limited.

[0033] The workpiece transfer mechanism 80 is a mechanism for transferring the workpiece W between the working area 210 and the external area 220. The workpiece transfer mechanism 80 includes a moving device 81 and a robot arm 86. In FIG. 1, the moving device 81 and the robot arm 86 for loading the workpiece W into the working area 210 and the moving device 81 and the robot arm 86 for loading the workpiece W into the external area 220 are shown.

[0034] The moving device 81 is movable between the working area 210 and the external area 220. The moving device 81 moves the robot arm 86 between the working area 210 and the external area 220. The moving device 81 slides the robot arm 86 in the Z-axis direction. The moving device 81 is composed of, for example, a guiding mechanism such as a linear guide, a feeding mechanism such as a rack and pinion, and a power source such as a motor.

[0035] The robot arm 86 can hold the workpiece W. A hand 87 for gripping the workpiece W is attached to the robot arm 86 as an end effector. The robot arm 86 is an articulated robot, for example, a six-axis articulated robot capable of six-axis control.

[0036] Note that the workpiece transfer mechanism 80 is not limited to the above configuration, and may be, for example, a gantry loader including a hand capable of gripping a workpiece and a moving device for sliding the hand in the X-axis and Y-axis directions.

[0037] FIG. 3 is a block diagram showing the control system of the machine tool in FIG. 1. Referring to FIGS. 1 and 3, the machine tool 100 further includes a control device 51. The control device 51 controls the machine tool 100.

[0038] Each component of the control device 51 is realized by hardware including an arithmetic unit such as a CPU (Central Processing Unit) and various computer processors, a storage device such as a memory or a storage, and a wired or wireless communication line connecting them, and software stored in the storage device and supplying processing instructions to the arithmetic unit. The computer program may be constituted by a device driver, an operating system, various application programs located in upper layers thereof, or a library providing common functions to these programs.

[0039] The control device 51 includes a program storage unit 52, a program execution unit 53, a tool spindle control unit 54, a tool post control unit 71, a work spindle control unit 55, and an opposed work spindle control unit 56.

[0040] The program storage unit 52 stores an execution program (control program of the machine tool 100) for workpiece machining created by an operator of the machine tool 100. The program storage unit 52 is, for example, a flash memory.

[0041] The program execution unit 53 executes the execution program stored in the program storage unit 52. The program execution unit 53 reads the instructions of the execution program and outputs control signals to each of the tool spindle control unit 54, the tool post control unit 71, the work spindle control unit 55, and the opposed work spindle control unit 56.

[0042] The tool spindle control unit 54 controls a tool spindle turning motor 61 for turning the tool spindle 41 about the B axis, a tool spindle feed motor 62 for moving the tool spindle 41 in each of the X-axis direction, Y-axis direction, and Z-axis direction, and a tool spindle rotation motor 63 for rotating the tool spindle 41 about the rotation center axis 140 according to a control signal from the program execution unit 53.

[0043] The tool post control unit 71 controls a tool post turning motor 72 for turning the tool post 31 about the turning center axis 130, a tool post feed motor 73 for moving the tool post 31 in each of the X-axis direction and Z-axis direction, and an actuator 74 for operating the holder 36 in a clamped state or an unclamped state according to a control signal from the program execution unit 53.

[0044] The workpiece spindle control unit 55 controls a workpiece spindle rotation motor 64 for rotating the workpiece spindle 21 about the rotation center axis 110 according to a control signal from the program execution unit 53. The opposed workpiece spindle control unit 56 controls an opposed workpiece spindle rotation motor 65 for rotating the opposed workpiece spindle 26 about the rotation center axis 120 and an opposed workpiece spindle feed motor 66 for moving the opposed workpiece spindle 26 in the Z-axis direction according to a control signal from the program execution unit 53.

[0045] FIG. 4 is a flowchart showing the flow of workpiece machining using the machine tool in FIG. 1. FIGS. 5 to 10 are front views schematically showing each step of workpiece machining using the machine tool in FIG. 1.

[0046] Referring to FIGS. 1 to 10, the control device 51 controls the tool spindle 41 so as to obtain an intermediate workpiece W' including a first portion 160, a second portion 170, and a connecting portion 180 connecting the first portion 160 and the second portion 170 by machining the workpiece W, controls the tool post 31 so as to hold the first portion 160 by the holder 36, and controls the tool spindle 41 so as to cut the connecting portion 180 while holding the first portion 160 by the holder 36.

[0047] Also, the method for machining the workpiece in the present embodiment includes steps (S103, S105) of obtaining an intermediate workpiece W' including a first portion 160, a second portion 170, and a connecting portion 180 connecting the first portion 160 and the second portion 170 by machining the workpiece W, a step (S107) of holding the first portion 160 by a holder 36 attached to the tool rest 31, and a step (S108) of cutting the connecting portion 180 while holding the first portion 160 by the holder 36.

[0048] Also, the control program in the present embodiment is a control program for a machine tool 100 including a tool rest 31. The control program causes the machine tool 100 to execute steps (S103, S105) of obtaining an intermediate workpiece W' including a first portion 160, a second portion 170, and a connecting portion 180 connecting the first portion 160 and the second portion 170 by machining the workpiece W, a step (S107) of holding the first portion 160 by a holder 36 attached to the tool rest 31, and a step (S108) of cutting the connecting portion 180 while holding the first portion 160 by the holder 36.

[0049] As shown in FIGS. 4 and 5, first, the workpiece W is carried into the working area 210 (S101). In this step, the control device 51 controls the robot arm 86 so that the workpiece W placed on the workpiece stocker 91 is gripped by the hand 87. The workpiece W has a cylindrical shape. The control device 51 controls the moving device 81 so that the robot arm 86 moves from the external area 220 to the working area 210.

[0050] As shown in FIGS. 4 and 6, next, the workpiece W is held by the workpiece spindle 21 (S102). In this step, the control device 51 controls the robot arm 86 so that the workpiece W is disposed inside the plurality of claw portions 22. The control device 51 controls the workpiece spindle 21 so that the workpiece W is gripped by the plurality of claw portions 22. The workpiece W has one end portion 191 that is gripped by the plurality of claw portions 22. The control device 51 controls the robot arm 86 so that the gripping of the workpiece W by the hand 87 is released.

[0051] Next, the workpiece W is machined by the tool spindle 41 (S103). In this step, the control device 51 controls the tool spindle 41 so as to form the first portion 160, the second portion 170, and the connecting portion 180 on the workpiece W.

[0052] More specifically, the tool spindle 41 is arranged to face the workpiece W in the X-axis direction (vertical direction). Using a tool T such as a milling cutter held by the tool spindle 41, the outer peripheral surface of the workpiece W is machined into a planar shape. The workpiece spindle 21 is rotated 180° about the rotation center axis 110. Again, by using a tool T such as a milling cutter held by the tool spindle 41 to machine the outer peripheral surface of the workpiece W into a planar shape, a flat plate shape in which the X-axis direction becomes the thickness direction is obtained. By machining the flat plate portion of the workpiece W using various tools T held by the tool spindle 41, the first portion 160, the second portion 170, and the connecting portion 180 are formed on the workpiece W while leaving one end portion 191.

[0053] In the present embodiment, the first portion 160 is the product portion. The first portion 160 has a shape corresponding to the final product after the machining of the workpiece W is completed. The second portion 170 is an unnecessary portion. The second portion 170 has a shape that does not correspond to the final product.

[0054] The second portion 170 is arranged at a distance from the first portion 160. The second portion 170 is arranged side by side at a distance from the first portion 160 in the Z-axis direction. The second portion 170 has a shape that can be gripped by a plurality of claw portions 27 on the opposing workpiece spindle 26. The second portion 170 has a flat plate shape. The volume of the second portion 170 is smaller than the volume of the first portion 160. The second portion 170 may have a frame shape surrounding the edge of the first portion 160.

[0055] The connecting portion 180 extends between the first portion 160 and the second portion 170. The connecting portion 180 extends from the edge of the first portion 160 and is connected to the edge of the second portion 170. The connecting portion 180 is disposed between the first portion 160 and the second portion 170 in the Z-axis direction. One end of the connecting portion 180 in the Z-axis direction is connected to the first portion 160, and the other end in the Z-axis direction is connected to the second portion 170. The cross-sectional area when the connecting portion 180 is cut by a plane orthogonal to the Z-axis direction is equal to or less than the cross-sectional area when the first portion 160 is cut by a plane orthogonal to the Z-axis direction at the position where the connecting portion 180 is connected to the first portion 160. The cross-sectional area when the connecting portion 180 is cut by a plane orthogonal to the Z-axis direction is equal to or less than the cross-sectional area when the second portion 170 is cut by a plane orthogonal to the Z-axis direction at the position where the connecting portion 180 is connected to the second portion 170.

[0056] The first portion 160 and the second portion 170 may be configured to be connected by a plurality of connecting portions 180. For the processing for forming the first portion 160, the second portion 170, and the connecting portion 180 on the workpiece W, in addition to the tool T held by the tool spindle 41, various tools held by the tool rest 31 may be used.

[0057] Next, as shown in FIGS. 4 and 7, the workpiece W is held by the opposing workpiece spindle 26 (S104). In this step, the control device 51 controls the opposing workpiece spindle 26 such that the second portion 170 of the workpiece W is disposed inside the plurality of claw portions 27 and is gripped by the plurality of claw portions 22.

[0058] Next, the cutting process of the workpiece W is performed by the tool spindle 41 (S105). In this step, the control device 51 controls the tool spindle 41 such that the root portion of the first portion 160 with respect to one end portion 191 of the workpiece W is cut. The one end portion 191 gripped by the plurality of claw portions 22 of the workpiece spindle 21 is separated from the first portion 160. Thereby, an intermediate workpiece W' including the first portion 160, the second portion 170, and the connecting portion 180 is obtained.

[0059] Next, as shown in FIGS. 4 and 8, the tool rest 31 is pivoted and moved in the Z-axis direction and the X-axis direction (S106). Next, the first part 160 is held by the holder 36 (S107).

[0060] In step S106, the control device 51 controls the tool rest 31 such that the swivel part 32 pivots about the swivel center axis 130 and the holder 36 is indexed to a predetermined position. The control device 51 controls the tool rest 31 such that the tool rest 31 moves in the Z-axis direction and the X-axis direction and the first part 160 is disposed between the pair of gripping claws 38 of the holder 36. In step S107, the control device 51 controls the tool rest 31 such that the first part 160 is gripped by the pair of gripping claws 38.

[0061] Next, as shown in FIGS. 4, 9, and 10, the cutting process of the connecting part 180 is performed by the tool spindle 41 (S108). In this step, the control device 51 controls the tool spindle 41 such that the connecting part 180 is cut. By cutting the connecting part 180, the first part 160 is separated from the second part 170. At this time, the first part 160 is held by the holder 36. The second part 170 is held by the opposing work spindle 26.

[0062] As shown in FIG. 4, the first part 160, which is the product part, and the second part 170, which is the unnecessary part, are recovered (S109).

[0063] In this step, the control device 51 controls the robot arm 86 such that the first part 160 is gripped by the hand 87, and then controls the tool rest 31 such that the gripping of the first part 160 by the pair of gripping claws 38 is released. The control device 51 controls the moving device 81 such that the robot arm 86 moves from the machining area 210 to the external area 220. The control device 51 controls the robot arm 86 such that the first part 160 gripped by the hand 87 is placed on the work stocker 91.

[0064] The control device 51 controls the robot arm 86 so that the second part 170 is gripped by the hand 87, and then controls the opposing work spindle 26 so that the gripping of the second part 170 by the plurality of claw parts 27 is released. The control device 51 controls the moving device 81 so that the robot arm 86 moves from the machining area 210 to the external area 220. The control device 51 controls the robot arm 86 so that the second part 170 gripped by the hand 87 is placed on the workpiece stocker 91.

[0065] In the present embodiment, in the cutting step (S108) of the connecting portion 180, since the first part 160 is held by the holder 36 attached to the tool rest 31, the intermediate workpiece W' can be held more firmly. Thereby, it is possible to prevent the intermediate workpiece W' from falling off or the machining point of the intermediate workpiece W' by the tool held by the tool spindle 41 from shifting, and the cutting step of the connecting portion 180 can proceed smoothly.

[0066] Also, in the cutting step of the connecting portion 180, since the second part 170 is held by the opposing work spindle 26, the intermediate workpiece W' can be held even more firmly. Further, after the cutting step of the connecting portion 180, since the first part 160 is held by the tool rest 31 and the second part 170 is held by the opposing work spindle 26, the first part 160 and the second part 170 can be collected separately.

[0067] Also, the tool spindle 41 is disposed above the rotation center axis 120 of the opposing work spindle 26 with the rotation center axis 120 of the opposing work spindle 26 interposed therebetween, and the tool rest 31 is disposed below the rotation center axis 120 of the opposing work spindle 26 with the rotation center axis 120 of the opposing work spindle 26 interposed therebetween. Thereby, during the cutting step of the connecting portion 180, it becomes difficult for the tool spindle 41 to interfere with the tool rest 31 holding the intermediate workpiece W', so that the restriction on the movement range of the tool spindle 41 can be suppressed.

[0068] Also, in the cutting process of the connecting portion 180, the first portion 160 held by the tool rest 31 is the product portion, and the second portion 170 held by the opposing work spindle 26 is the unnecessary portion. According to such a configuration, the shape or operation mode of the pair of gripping claws 38 in the holder 36 has a higher degree of design freedom compared to the shape or operation mode of the plurality of claw portions 27 in the opposing work spindle 26. Therefore, it becomes easier to hold the first portion 160 by the holder 36 according to the product shape formed in the first portion 160.

[0069] Also, in the cutting process of the connecting portion 180, the second portion 170, which is the unnecessary portion, is held by the opposing work spindle 26. Thereby, after performing the processing for forming the product shape on the first portion 160 while holding the second portion 170 by the opposing work spindle 26, it is possible to smoothly shift to the process of cutting the connecting portion 180 while holding the first portion 160 and the second portion 170 by the tool rest 31 and the opposing work spindle 26, respectively.

[0070] In addition, in the cutting process of the connecting portion 180 shown in FIG. 2, the second portion 170 may be held by the work spindle 21. Also, in the cutting process of the connecting portion 180 shown in FIG. 2, in addition to the first portion 160, the second portion 170 may be held by the tool rest 31.

[0071] Also, when holding the intermediate workpiece W' by the holder 36 of the tool rest 31, the gripping claws 38 may be configured such that the intermediate workpiece W' is gripped in the direction (thickness direction) with the smallest width in the intermediate workpiece W'. For example, in FIG. 2, the gripping claws 38 may be configured to contact the flat plate portion of the first portion 160 where the gripping claws 38 face the vertical direction. According to such a configuration, even in the intermediate workpiece W' in which the second portion 170 has a frame shape surrounding the edge of the first portion 160 and the connecting portion 180 extends in a branched manner from the edge of the first portion 160 toward the second portion 170, by using a structure similar to the hand of the multi-joint robot in Patent Document 1 described above for the gripping claws 38, it becomes possible to hold both the first portion 160 and the second portion 170. Further, when the second portion 170 has a frame shape, as a means for separating the connecting portion 180 while holding the intermediate workpiece W' by the holder 36 of the tool rest 31, a tool attachment that is detachably attached to the tool spindle 41 and can rotate the tool with the direction (Y-axis direction) orthogonal to the rotation axis direction (X-axis direction) of the tool spindle 41 as the rotation axis is also effectively utilized.

[0072] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0073] 12 Cover body, 16 Bed, 21 Work spindle, 22, 27 Claw parts, 26 Opposite work spindle, 31 Tool rest, 32 Swivel part, 36 Holder, 37 Holder base, 38 Pair of gripping claws, 41 Tool spindle, 42 Spindle end face, 51 Control device, 52 Program storage unit, 53 Program execution unit, 54 Tool spindle control unit, 55 Work spindle control unit, 56 Opposite work spindle control unit, 61 Tool spindle swivel motor, 62 Tool spindle feed motor, 63 Tool spindle rotation motor, 64 Work spindle rotation motor, 65 Opposite work spindle rotation motor, 66 Opposite work spindle feed motor, 71 Tool rest control unit, 72 Tool rest swivel motor, 73 Tool rest feed motor, 74 Actuator, 80 Work transfer mechanism, 81 Moving device, 86 Robot arm, 87 Hand, 91 Work stocker, 100 Machine tool, 110, 120, 140 Rotation center axis, 130, 150 Swivel center axis, 160 First part, 170 Second part, 180 Connecting part, 191 End part, 210 Working area, 220 External area, T Tool, W’ Intermediate workpiece, W Workpiece.

Claims

1. A machine tool, comprising: a tool rest having a holder capable of holding a workpiece; a tool spindle; and a control device for controlling the machine tool, wherein the control device: controls the tool spindle so as to obtain an intermediate workpiece including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion by machining the workpiece; controls the tool rest so as to hold the first portion by the holder; and controls the tool spindle so as to cut the connecting portion while holding the first portion by the holder.

2. further comprising a workpiece spindle, wherein the control device controls the workpiece spindle so as to hold the workpiece by the workpiece spindle, and at the time of cutting the connecting portion, the second portion is held by the workpiece spindle. The machine tool according to claim 1.

3. wherein the first portion corresponds to a product portion, and the second portion corresponds to an unnecessary portion. The machine tool according to claim 1 or 2.

4. A method for machining a workpiece, comprising: obtaining an intermediate workpiece including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion by machining the workpiece; holding the first portion by a holder attached to a tool rest; and cutting the connecting portion while holding the first portion by the holder.

5. A control program for a machine tool including a tool rest, wherein the control program causes the machine tool to: obtain an intermediate workpiece including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion by machining the workpiece; hold the first portion by a holder attached to the tool rest; and cut the connecting portion while holding the first portion by the holder.

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