Machine tool, workpiece machining method, and control program

Abstract

This machine tool is provided with: a tool post (31) having a holder (36) capable of holding a workpiece; a tool main spindle (41); and a control device (51) for controlling the machine tool. The control device (51) controls the tool main spindle (41) to machine the workpiece so as to obtain an intermediate workpiece (W') including a first part (160), a second part (170), and a linking part (180) that links the first part (160) and the second part (170), controls the tool post (31) to hold the first part (160) by means of the holder (36), and controls the tool main spindle (41) to cut the linking part (180) while holding the first part (160) by means of the holder (36).

Description

Machine tool, workpiece processing method and control program

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

[0002] For example, Japanese Patent No. 7033240 (Patent Document 1) discloses a machine tool including a tool spindle, first and second spindles for holding a workpiece, and an articulated robot for transporting the workpiece. The workpiece is machined to provide a necessary portion that will become the final part and a frame-shaped unnecessary portion to which the necessary portion is connected via multiple connecting portions. Furthermore, while the workpiece is held by the hand of the articulated robot, the connecting portions are cut to separate the necessary portion from the unnecessary portion.

[0003] Patent No. 7033240 specification

[0004] In the machine tool disclosed in the above-mentioned Patent Document 1, the workpiece is gripped by the hand of the articulated robot when cutting the connecting portion. However, if the rigidity of the articulated robot or the gripping force of the hand on the workpiece is insufficient, there is a possibility that the machining point of the workpiece by the tool may shift or the workpiece may fall off the hand when cutting the connecting portion.

[0005] An object of the present invention is to provide a machine tool, a workpiece processing method, and a control program that can smoothly perform cutting processing of a connecting portion of an intermediate workpiece that includes a first portion, a second portion, and a connecting portion that connects the first portion and the second portion.

[0006] A machine tool according to the present invention includes a tool post 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 to machine the workpiece to obtain an intermediate workpiece including a first portion, a second portion, and a connecting portion connecting the first and second portions, controls the tool post to hold the first portion with the holder, and controls the tool spindle to cut the connecting portion while holding the first portion with the holder.

[0007] A method for machining a workpiece according to the present invention includes the steps of machining the workpiece to obtain an intermediate product including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion; holding the first portion with a holder attached to a tool post; and cutting the connecting portion while holding the first portion with the holder.

[0008] A control program according to the present invention is for a machine tool including a tool rest, and causes the machine tool to execute the steps of: machining a workpiece to obtain an intermediate workpiece including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion; holding the first portion with a holder attached to the tool rest; and cutting the connecting portion while holding the first portion with the holder.

[0009] According to the present invention, it is possible to provide a machine tool, a workpiece processing method, and a control program that can smoothly perform cutting processing of a connecting portion of an intermediate workpiece that includes a first portion, a second portion, and a connecting portion that connects the first portion and the second portion.

[0010] FIG. 1 is a front view showing a machine tool in an embodiment of the present invention. FIG. 2 is a perspective view showing cutting processing of a connecting portion of an intermediate workpiece in the machine tool in FIG. 1. FIG. 3 is a block diagram showing a control system of the machine tool in FIG. 1. FIG. 4 is a flowchart showing a flow of workpiece machining using the machine tool in FIG. 1. FIG. 5 is a front view schematically showing a first step of workpiece machining using the machine tool in FIG. 1. FIG. 6 is a front view schematically showing a second step of workpiece machining using the machine tool in FIG. 1. FIG. 7 is a front view schematically showing a third step of workpiece machining using the machine tool in FIG. 1. FIG. 8 is a front view schematically showing a fourth step of workpiece machining using the machine tool in FIG. 1. FIG. 9 is a front view schematically showing a fifth step of workpiece machining using the machine tool in FIG. 1. FIG. 11 is a front view schematically showing a sixth step of workpiece machining using the machine tool in FIG. 1.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings, in which the same or equivalent components are designated by the same reference numerals.

[0012] Fig. 1 is a front view showing a machine tool according to an embodiment of the present invention, in which the interior of the machine tool is shown through a cover body that forms the exterior of the machine tool.

[0013] Referring to FIG. 1, machine tool 100 is a multi-tasking machine equipped with both a milling function for machining a workpiece by bringing a rotating tool into contact with a stationary workpiece, and a turning function for machining a workpiece by bringing a tool into contact with a rotating workpiece.

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

[0015] In this specification, for the convenience of explaining the configuration of machine tool 100, the axis that is parallel to the rotation axis of the workpiece and extends horizontally will be referred to as the "Z-axis," the axis that is perpendicular to the Z-axis and extends horizontally will be referred to as the "Y-axis," and the axis that extends vertically will be referred to as the "X-axis."

[0016] Machine tool 100 has bed 16, workpiece spindle 21, counter workpiece spindle 26, tool spindle 41, tool rest 31, and cover body 12. Workpiece spindle 21, counter workpiece spindle 26, tool spindle 41, and tool rest 31 are arranged in machining area 210. Machining area 210 is a space where workpiece machining is performed, and is sealed by cover body 12 to prevent foreign matter such as chips or cutting oil resulting from workpiece machining from leaking outside machining area 210.

[0017] The bed 16 is a base member for supporting the workpiece spindle 21, the counter workpiece spindle 26, the tool spindle 41, the tool rest 31, etc., and is installed on the floor of a factory, etc. The bed 16 is made of metal such as cast metal.

[0018] The workpiece spindle 21 and the opposing workpiece spindle 26 are capable of holding a workpiece. The workpiece spindle 21 is driven by a motor to rotate about a rotation center axis 110 parallel to the Z axis. The workpiece spindle 21 is provided with a chuck mechanism having multiple jaws 22 for detachably holding the workpiece. Each jaw 22 is driven to slide in the radial direction of the rotation center axis 110 by hydraulic pressure or the like. The multiple jaws 22 grip the outer peripheral surface of the workpiece by sliding radially inward from the rotation center axis 110, or grip the inner peripheral surface of the workpiece by sliding radially outward from the rotation center axis 110.

[0019] The counter work spindle 26 is disposed opposite the work spindle 21 in the Z-axis direction. The counter work spindle 26 is driven by a motor to rotate 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 counter work spindle 26 is provided with a chuck mechanism having multiple jaws 27 for detachably holding a workpiece. The multiple jaws 27 correspond to the multiple jaws 22 on the work spindle 21.

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

[0021] The tool spindle 41 can hold a tool. The tool spindle 41 is driven by a motor to rotate about a rotation center axis 140 parallel to the X-axis in a reference posture described below. The tool spindle 41 has a built-in clamping mechanism (not shown) for detachably holding a tool.

[0022] The tool spindle 41 can also rotate about a rotation center axis 150 that is parallel to the Y axis (B-axis rotation). The rotation center axis 150 intersects with the rotation center axis 140. The rotation range of the tool spindle 41 is, for example, within a range of ±120° based on a reference position (the position of the tool spindle 41 shown in FIG. 1 ) in which the spindle end surface 42 of the tool spindle 41 faces downward.

[0023] The tool spindle 41 can be moved in the X-axis, Y-axis, and Z-axis directions by various feed mechanisms, guide mechanisms, and motors. Although not shown in Fig. 1, an automatic tool changer (ATC) for automatically changing the tools held by the tool spindle 41 and a tool magazine for storing replacement tools are provided around the work spindle 21.

[0024] The tool rest 31 is capable of holding tools. The tool rest 31 is provided below the tool spindle 41. The tool spindle 41 is disposed above the rotational axis 110 of the work spindle 21 and the rotational axis 120 of the counter work spindle 26, while the tool rest 31 is disposed below the rotational axis 110 of the work spindle 21 and the rotational axis 120 of the counter work spindle 26. The tool rest 31 is of a so-called turret type, and multiple tools are attached radially to perform rotational indexing.

[0025] The tool rest 31 has a swivel unit 32 and multiple tool holders (not shown). The swivel unit 32 is swivelable around a swivel center axis 130 parallel to the Z axis. The swivel unit 32 has a disk shape with its thickness direction aligned with the axial direction of the swivel center axis 130. Multiple tool holders (not shown) are capable of holding tools. The multiple tool holders are attached to the outer peripheral surface of the swivel unit 32. The multiple tool holders are lined up in the circumferential direction of the swivel center axis 130. As the swivel unit 32 swivels around the swivel center axis 130, the tools held in the tool holders move 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] Machine tool 100 may further include an automatic tool changer for automatically changing a tool held in tool post 31. In this case, a clamping mechanism for automatically clamping and unclamping a tool in conjunction with automatic change of a tool held in a tool holder may be built into tool post 31. Tool post 31 may also be provided with a milling function for rotating a tool held in a tool holder.

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

[0028] Figure 2 is a perspective view showing cutting of a joint portion of an intermediate workpiece in the machine tool in Figure 1. Referring to Figures 1 and 2, the tool post 31 further has a holder 36. The holder 36 is capable of holding a workpiece. The holder 36 is attached to the outer peripheral surface of the swivel unit 32. The holder 36, together with a plurality of tool holders, is arranged in the circumferential direction of the swivel central axis 130.

[0029] The holder 36 is made up of a clamp unit that automatically operates between a clamp state in which the workpiece is clamped and an unclamped state in which the workpiece is unclamped.

[0030] To explain 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 gap between them. The pair of gripping claws 38 are guided so as to be slidable in the opposing direction. The holder base 37 has a built-in actuator (corresponding to actuator 74 in FIG. 3) for sliding the pair of gripping claws 38. The power source of the actuator is not particularly limited and may be, for example, a motor or a hydraulic cylinder.

[0031] A workpiece is placed between the pair of gripping jaws 38, and the pair of gripping jaws 38 slide toward each other to obtain a clamped state in which the workpiece is gripped by the pair of gripping jaws 38. The pair of gripping jaws 38 slide away from each other to obtain an unclamped state in which the workpiece is released from the pair of gripping jaws 38.

[0032] Referring to Figure 1, machine tool 100 further has a workpiece stocker 91 and a workpiece transport mechanism 80. Workpiece stocker 91 is installed in external area 220 outside machining area 210. Workpiece stocker 91 is adjacent to machining area 210 in the Z-axis direction. Workpiece stocker 91 is capable of storing workpieces W before and after machining. In Figure 1, a table on which workpieces W can be placed is shown as workpiece stocker 91, but the form of workpiece stocker 91 is not particularly limited.

[0033] The workpiece transport mechanism 80 is a mechanism for transporting the workpiece W between the working area 210 and the external area 220. The workpiece transport mechanism 80 has a moving device 81 and a robot arm 86. Note that Fig. 1 shows the moving device 81 and robot arm 86 that transport the workpiece W into the working area 210, and the moving device 81 and robot arm 86 that transport the workpiece W into the external area 220.

[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 guide mechanism such as a linear guide, a feed mechanism such as a rack and pinion, and a power source such as a motor.

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

[0036] The workpiece transport mechanism 80 is not limited to the above configuration, and may be, for example, a gantry loader consisting of a hand capable of gripping a workpiece and a moving device for sliding the hand along the X and Y axes.

[0037] Fig. 3 is a block diagram showing a control system of the machine tool in Fig. 1. With reference to Figs. 1 and 3, machine tool 100 further has a control device 51. Control device 51 controls machine tool 100.

[0038] The components of the control device 51 are realized by hardware including computing units such as a CPU (Central Processing Unit) and various computer processors, storage devices such as memory or storage, and wired or wireless communication lines connecting them, as well as software stored in the storage devices and supplying processing instructions to the computing units. The computer programs may be configured by device drivers, an operating system, various application programs located at higher levels than these, or libraries that provide common functions to these programs.

[0039] The control device 51 has a program storage unit 52 , a program execution unit 53 , a tool spindle control unit 54 , a tool rest control unit 71 , a workpiece spindle control unit 55 , and an opposing workpiece spindle control unit 56 .

[0040] Program storage unit 52 stores an execution program for machining a workpiece (a control program for machine tool 100) created by an operator of machine tool 100. 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 the tool spindle control unit 54, the tool post control unit 71, the workpiece spindle control unit 55, and the counter workpiece spindle control unit 56.

[0042] In accordance with control signals from the program execution unit 53, the tool spindle control unit 54 controls a tool spindle turning motor 61 for turning the tool spindle 41 in the B-axis direction, a tool spindle feed motor 62 for moving the tool spindle 41 in each of the X-axis, Y-axis, and Z-axis directions, and a tool spindle rotation motor 63 for rotating the tool spindle 41 around the rotation central axis 140.

[0043] The tool post control unit 71 controls, in accordance with control signals from the program execution unit 53, a tool post rotation motor 72 for rotating the tool post 31 around the rotation center axis 130, a tool post feed motor 73 for moving the tool post 31 in each of the X-axis and Z-axis directions, and an actuator 74 for operating the holder 36 in a clamped or unclamped state.

[0044] The work spindle control unit 55 controls a work spindle rotation motor 64 for rotating the work spindle 21 around the rotation central axis 110 in accordance with a control signal from the program execution unit 53. The counter work spindle control unit 56 controls a counter work spindle rotation motor 65 for rotating the counter work spindle 26 around the rotation central axis 120 and a counter work spindle feed motor 66 for moving the counter work spindle 26 in the Z-axis direction in accordance with 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] 1 to 10, the control device 51 controls the tool spindle 41 to process the workpiece W 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, controls the tool post 31 to hold the first portion 160 with the holder 36, and controls the tool spindle 41 to cut the connecting portion 180 while holding the first portion 160 with the holder 36.

[0047] In addition, the method for machining a workpiece in this embodiment includes steps (S103, S105) of machining the workpiece W 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, a step (S107) of holding the first portion 160 with a holder 36 attached to the tool post 31, and a step (S108) of cutting the connecting portion 180 while holding the first portion 160 with the holder 36.

[0048] The control program in this embodiment is a control program for machine tool 100 that includes tool rest 31. The control program causes machine tool 100 to execute the steps of: machining workpiece W to obtain intermediate workpiece W′ that includes first portion 160, second portion 170, and connecting portion 180 that connects first portion 160 and second portion 170 (S103, S105); holding first portion 160 with holder 36 attached to tool rest 31 (S107); and cutting connecting portion 180 while holding first portion 160 with holder 36 (S108).

[0049] 4 and 5 , first, the workpiece W is carried into the machining 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 grasped 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 machining area 210.

[0050] 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 placed inside the multiple claws 22. The control device 51 controls the workpiece spindle 21 so that the workpiece W is gripped by the multiple claws 22. The workpiece W has one end 191 that is gripped by the multiple claws 22. The control device 51 controls the robot arm 86 so that the grip 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 to form the first portion 160, the second portion 170, and the connecting portion 180 in the workpiece W.

[0052] More specifically, the tool spindle 41 is positioned opposite the workpiece W in the X-axis direction (vertical direction). A tool T, such as a milling cutter, held by the tool spindle 41 is used to machine the outer circumferential surface of the workpiece W into a flat surface. The workpiece spindle 21 is then rotated 180° around the central axis of rotation 110. Again, a tool T, such as a milling cutter, held by the tool spindle 41 is used to machine the outer circumferential surface of the workpiece W into a flat surface, thereby obtaining a flat plate shape whose thickness direction is in the X-axis direction. By using various tools T held by the tool spindle 41 to machine the flat portion of the workpiece W, the first portion 160, the second portion 170, and the connecting portion 180 are formed in the workpiece W, leaving one end portion 191.

[0053] In this embodiment, the first portion 160 is a product portion. The first portion 160 has a shape that corresponds to the final product after the processing 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 disposed at a distance from the first portion 160. The second portion 170 is aligned with the first portion 160 at a distance in the Z-axis direction. The second portion 170 has a shape that can be grasped by the multiple claw portions 27 of 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 that surrounds 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 an edge of the first portion 160 and is connected to an 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 of ​​the connecting portion 180 when cut by a plane perpendicular to the Z-axis direction is equal to or smaller than the cross-sectional area of ​​the first portion 160 when cut by a plane perpendicular to the Z-axis direction at the position where the connecting portion 180 is connected to the first portion 160. The cross-sectional area of ​​the connecting portion 180 when cut by a plane perpendicular to the Z-axis direction is equal to or smaller than the cross-sectional area of ​​the second portion 170 when cut by a plane perpendicular 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 connected by a plurality of connecting portions 180. In the processing for forming the first portion 160, the second portion 170, and the connecting portions 180 in the workpiece W, various tools held by the tool post 31 may be used in addition to the tool T held by the tool spindle 41.

[0057] 4 and 7 , next, the workpiece W is held by the counter workpiece spindle 26 (S104). In this step, the control device 51 controls the counter workpiece spindle 26 so that the second portion 170 of the workpiece W is positioned inside the multiple claw portions 27 and is gripped by the multiple claw portions 22.

[0058] Next, the cutting step of the workpiece W is performed by the tool spindle 41 (S105). In this step, the control device 51 controls the tool spindle 41 so that the base portion of the first portion 160 relative to the one end portion 191 of the workpiece W is cut off. The one end portion 191, which is gripped by the multiple claw portions 22 of the workpiece spindle 21, is cut off from the first portion 160. As a result, an intermediate workpiece W' including the first portion 160, the second portion 170, and the connecting portion 180 is obtained.

[0059] 4 and 8, the tool rest 31 is then rotated and moved in the Z-axis and X-axis directions (S106).Then, the first portion 160 is held by the holder 36 (S107).

[0060] In step S106, the control device 51 controls the tool post 31 so that the swivel unit 32 rotates about the central pivot axis 130 and the holder 36 is indexed to a predetermined position. The control device 51 controls the tool post 31 so that the tool post 31 moves in the Z-axis direction and the X-axis direction and the first portion 160 is positioned between the pair of gripping jaws 38 of the holder 36. In step S107, the control device 51 controls the tool post 31 so that the pair of gripping jaws 38 grip the first portion 160.

[0061] 4, 9, and 10, next, the tool spindle 41 executes the step of cutting the connecting portion 180 (S108). In this step, the control device 51 controls the tool spindle 41 so as to cut the connecting portion 180. By cutting the connecting portion 180, the first portion 160 is separated from the second portion 170. At this time, the first portion 160 is held by the holder 36. The second portion 170 is held by the counter work spindle 26.

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

[0063] In this step, the control device 51 controls the robot arm 86 so that the hand 87 grasps the first part 160, and then controls the tool post 31 so that the pair of grasping jaws 38 release the grasp of the first part 160. The control device 51 controls the movement device 81 so that the robot arm 86 moves from the work area 210 to the external area 220. The control device 51 controls the robot arm 86 so that the first part 160 grasped by the hand 87 is placed on the work stocker 91.

[0064] The control device 51 controls the robot arm 86 so that the hand 87 grasps the second portion 170, and then controls the opposing workpiece spindle 26 so that the multiple claws 27 release the grasp of the second portion 170. 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 portion 170 grasped by the hand 87 is placed on the workpiece stocker 91.

[0065] In this embodiment, in the step of cutting off the connecting portion 180 (S108), the first portion 160 is held by the holder 36 attached to the tool post 31, so that the intermediate workpiece W' can be held more firmly. This prevents 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 allows the step of cutting off the connecting portion 180 to proceed smoothly.

[0066] Furthermore, in the step of cutting the connecting portion 180, the second portion 170 is held by the opposing workpiece spindle 26, so that the intermediate workpiece W' can be held even more firmly. Furthermore, after the step of cutting the connecting portion 180, the first portion 160 is held by the tool post 31, and the second portion 170 is held by the opposing workpiece spindle 26, so that the first portion 160 and the second portion 170 can be collected separately.

[0067] Furthermore, the tool spindle 41 is disposed above the central axis of rotation 120 of the opposing work spindle 26, and the tool rest 31 is disposed below the central axis of rotation 120 of the opposing work spindle 26. This makes it less likely that the tool spindle 41 will interfere with the tool rest 31 that holds the intermediate workpiece W' during the cutting process of the connecting portion 180, thereby minimizing restrictions on the movement range of the tool spindle 41.

[0068] Furthermore, 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. With this configuration, the shape or operating mode of the pair of gripping claws 38 on the holder 36 has a higher degree of freedom in design compared to the shape or operating mode of the multiple claw portions 27 on the opposing work spindle 26, making it easier for the holder 36 to hold the first portion 160 in a manner that matches the product shape formed in the first portion 160.

[0069] Furthermore, in the step of cutting off connecting portion 180, second portion 170, which is an unnecessary portion, is held by opposing work spindle 26. As a result, after processing is performed on first portion 160 to form the product shape while second portion 170 is held by opposing work spindle 26, it is possible to smoothly move on to the step of cutting off connecting portion 180 while first portion 160 and second portion 170 are held by tool rest 31 and opposing work spindle 26, respectively.

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

[0071] Furthermore, when the intermediate workpiece W' is held by the holder 36 of the tool rest 31, the gripping claws 38 may be configured so that the intermediate workpiece W' is gripped in the narrowest direction (thickness direction) of the intermediate workpiece W'. For example, in FIG. 2, the gripping claws 38 may be configured to contact the face plate portion of the first portion 160 facing up or down. With this configuration, even in the case of an 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 branch-like manner from the edge of the first portion 160 toward the second portion 170, it is possible to hold both the first portion 160 and the second portion 170 by using a structure similar to that of the hand of the articulated robot disclosed in Patent Document 1 for the gripping claws 38. Furthermore, when the second part 170 has a frame shape, a tool attachment that is detachably attached to the tool spindle 41 and can rotate the tool around a rotation axis in a direction (Y-axis direction) perpendicular to the rotation axis direction (X-axis direction) of the tool spindle 41 can also be effectively used as a means for detaching the connecting part 180 while holding the intermediate workpiece W' with the holder 36 of the tool post 31.

[0072] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0073] 12 Cover body, 16 Bed, 21 Work spindle, 22, 27 Claw portion, 26 Counter work spindle, 31 Tool rest, 32 Swivel portion, 36 Holder, 37 Holder base, 38 Pair of gripping jaws, 41 Tool spindle, 42 Spindle end surface, 51 Control device, 52 Program memory unit, 53 Program execution unit, 54 Tool spindle control unit, 55 Work spindle control unit, 56 Counter 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 Counter work spindle rotation motor, 66 Counter 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 machining area, 220 external area, T tool, W' intermediate workpiece, W workpiece.

Claims

1. A machine tool comprising: a tool post 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 to machine the workpiece to obtain an intermediate workpiece including a first part, a second part, and a connecting portion connecting the first part and the second part; controls the tool post to hold the first part with the holder; and controls the tool spindle to cut the connecting portion while holding the first part with the holder.

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

3. A machine tool as claimed in claim 1 or 2, wherein the first portion corresponds to a product portion, and the second portion corresponds to an unnecessary portion.

4. A method for processing a workpiece, comprising the steps of: machining a workpiece to obtain an intermediate product including a first portion, a second portion, and a connecting portion connecting the first portion and the second portion; holding the first portion with a holder attached to a tool post; and cutting the connecting portion while holding the first portion with the holder.

5. A control program for a machine tool equipped with a tool post, the control program causing the machine tool to execute the steps of: machining a workpiece to obtain an intermediate workpiece including a first part, a second part, and a connecting portion connecting the first part and the second part; holding the first part with a holder attached to the tool post; and cutting the connecting portion while holding the first part with the holder.

Images