Workpiece inversion method and machine tool

Abstract

To disclose a work reversing method capable of reversing work of various forms with a simple structure.SOLUTION: A hand device 30 movably provided in a machine tool 10 grips a first grip position GPf of work 100 held by a headstock 18, removes the work 100 from the headstock 18, and then reverses a posture of the work 100 to attach the work 100 to the headstock 18 again. The machine tool 10 has a temporarily placing table 36 on which the work 100 can be placed. The hand device 30 places the work 100 on the temporarily placing table 36 during a period from the removal to the re-attachment of the work 100, and changes a grip position of the work 100 from the first grip position GPf to a second grip position GPs.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present specification discloses a workpiece reversing method for removing a workpiece from a headstock, reversing the workpiece, and then remounting the workpiece on the headstock, and a machine tool capable of reversing a workpiece. [Background Art]

[0002] The head station rotatably holds a first end of a workpiece. Then, a portion of the workpiece exposed outside the headstock is machined with a tool attached to a tool post or a spindle head. When predetermined machining of the workpiece is completed, the workpiece may be removed from the headstock, reversed, and a second end opposite to the first end of the workpiece may be remounted on the headstock. After remounting, additional machining is performed on the area around the first end of the workpiece.

[0003] In recent years, in order to reduce the burden on operators, it has been proposed to automatically perform such workpiece reversing and remounting using a hand device. For example, Patent Document 1 discloses a loading device in which a first work hand and a second work hand are attached to a horizontally movable carrier. In Patent Document 1, after a workpiece is gripped by the first work hand, the workpiece is transferred to the second work hand, and the second work hand rotates to reverse the posture of the workpiece by 180 degrees. According to the technique of Patent Document 1, reversing and remounting of the workpiece can be performed automatically, so the burden on the operator can be reduced. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 6-55308 [Patent Document 2] Japanese Patent Application Laid-Open No. 5-16003 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, Patent Document 1 requires two work hands (i.e., hand devices), which leads to larger machine tools and increased costs. Furthermore, in Patent Document 1, the horizontal distance between the first and second work hands can hardly be changed. Therefore, the technology in Patent Document 1 limits the positions of the workpiece that can be gripped by the work hands. As a result, the technology in Patent Document 1 has a limited range of workpiece shapes that can be properly reversed, resulting in poor versatility.

[0006] Furthermore, Patent Document 2 discloses a configuration in which a temporary support stand for temporarily placing a workpiece is attached to the tool post. However, Patent Document 2 does not suggest anything regarding the inversion of the workpiece.

[0007] Therefore, this specification discloses a workpiece inversion method and a machine tool that can invert workpieces of various shapes with a simple configuration. [Means for solving the problem]

[0008] The method for inverting a workpiece disclosed herein is a method for inverting a workpiece, characterized in that a hand device movably provided in a machine tool grips the workpiece held by the headstock at a first gripping position, removes the workpiece from the headstock, then inverts the orientation of the workpiece, and then reattaches the workpiece to the headstock, the machine tool having a temporary stand on which the workpiece can be placed, and the hand device places the workpiece on the temporary stand between the removal and reattachment of the workpiece, and then changes the gripping position of the workpiece from the first gripping position to a second gripping position.

[0009] In this case, the machine tool has one or more tool mounting sections, a tool rest that can change the position and orientation of the tools attached to the tool mounting sections, the temporary rest is attached to the tool mounting section, and the tool rest may change the orientation of the temporary rest to an orientation on which the workpiece can be placed, and position the temporary rest within the movable range of the hand device, prior to placing the workpiece on the temporary rest.

[0010] Furthermore, the workpiece has a first end that is held by the headstock before inversion and a second end that is held by the headstock when it is remounted, and the second gripping position may be further away from the second end than the first gripping position.

[0011] Furthermore, the temporary support stand may have a pair of mounting claws spaced apart from each other, and when the hand device places the workpiece on the temporary support stand, it may position the center of gravity of the workpiece between the pair of mounting claws.

[0012] The machine tool disclosed herein comprises a headstock for holding the end of a workpiece, a hand device movably provided in the machine tool for gripping the workpiece held by the headstock at a first gripping position, removing the workpiece from the headstock, then reversing the orientation of the workpiece, and then reattaching the workpiece to the headstock, and a temporary stand on which the workpiece can be placed, characterized in that, between the removal and reattachment of the workpiece, the hand device places the workpiece on the temporary stand and then changes the gripping position of the workpiece from the first gripping position to a second gripping position. [Effects of the Invention]

[0013] The technology disclosed herein allows the gripping position of the workpiece by the hand device to be changed between the removal and re-mounting of the workpiece, thereby preventing interference between the hand device and the headstock during re-mounting. This enables the inversion of various types of workpieces with a simple configuration. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic side view of a machine tool. [Figure 2] This is a schematic diagram showing the main components of a machine tool viewed from above. [Figure 3] This diagram shows the process of removing a workpiece from a chuck. [Figure 4] This figure shows the workpiece after it has been inverted and placed on a temporary support stand. [Figure 5] It is a diagram showing how a hand device changes the gripping position of a workpiece. [Figure 6] It is a diagram showing how a workpiece is re-mounted. [Figure 7] It is a diagram showing how a workpiece having a tapered portion is gripped. [Figure 8] It is a perspective view showing another example of a temporary placement table. [Figure 9] It is a diagram showing how a workpiece is re-mounted without changing the gripping position of the workpiece.

Mode for Carrying Out the Invention

[0015] Hereinafter, the configuration of a machine tool 10 will be described with reference to the drawings. Figure 1 is a schematic side view of the machine tool 10. Figure 2 is a schematic view of a main part of the machine tool 10 as seen from above. In the following description, a direction parallel to the rotation axis of a spindle 17 is defined as the Z-axis. A tool post 20 moves in a first direction parallel to the Z-axis and a second direction orthogonal to the first direction, and a direction parallel to this second direction is defined as the X-axis. Furthermore, a direction orthogonal to the X-axis and the Z-axis is defined as the Y-axis. On the Z-axis, a direction approaching the tool post 20 from the spindle 17 is defined as the positive direction; on the X-axis, a direction approaching the tool post 20 from the spindle 17 is defined as the positive direction; and on the Y-axis, a direction upward from the spindle 17 is defined as the positive direction.

[0016] This machine tool 10 is a lathe having a spindle 17 that rotationally holds a workpiece 100. More specifically, the machine tool 10 of the present example is a turning center having a turret 22 that holds a plurality of types of tools 110. However, the machine tool 10 exemplified herein is merely an example, and the technology disclosed in the present specification may be applied to other forms of machine tools as long as turning can be performed. For example, the technology disclosed in the present specification may be mounted on a combined machining machine that combines a lathe and a milling machine. In the following description, the machine tool 10 will be described as a turning center.

[0017] A periphery of a machining chamber 12 of a machine tool 10 is covered by a cover 16. A large opening is formed on a front surface of the machining chamber 12, and the opening is opened and closed by a door 14. An operator accesses each part in the machining chamber 12 through this opening. During machining, the door 14 provided at the opening is closed. This is for ensuring safety, environmental performance and the like.

[0018] The machine tool 10 includes a headstock 18 that rotatably holds one end of a workpiece 100, and a tool post 20 that holds a tool 110. The headstock 18 has a spindle 17 rotatable by a motor (not shown). A chuck 24 and a collet for detachably holding the workpiece 100 are provided on an end face of the spindle 17. The spindle 17 and the chuck 24 rotate on their own axes about a rotation axis extending in the horizontal direction (Z-axis direction).

[0019] The tool post 20 is a tool holding device that holds the tool 110. The tool post 20 is movable along the Z-axis, that is, in a direction parallel to the workpiece 100 held by the spindle 17. The tool post 20 is also capable of advancing and retracting in a direction parallel to the X-axis, that is, in a radial direction of the workpiece 100. As is clear from the drawings, the X-axis is inclined with respect to the horizontal direction such that when viewed from the opening of the machining chamber 12, the X-axis goes upward as it goes deeper.

[0020] A turret 22 capable of holding a plurality of tools 110 is provided on an end face of the tool post 20 in the Z-direction. The turret 22 has a polygonal shape when viewed in the Z-axis direction, and is rotatable about an axis parallel to the Z-axis. A plurality of tool mounting portions 26 to which the tools 110 can be attached are provided on a peripheral surface of the turret 22. By rotating the turret 22, the tool 110 to be used for machining can be changed.

[0021] Within the processing chamber 12, a robot 28 is provided to assist with the processing work. This robot 28 is an articulated robot or serial link manipulator having multiple links connected via joints. An end effector is attached to the tip of the robot 28. The end effector attached to the robot 28 can be changed depending on the situation. In this example, a hand device 30 is attached to the tip of the robot 28 as the end effector.

[0022] The hand device 30 is a device for grasping an object. This hand device 30 has a plurality of (two in the illustrated example) grasping arms 32 that grasp and release an object by moving closer to and further apart from each other. This hand device 30 is attached to the tip of the robot 28 via a base member 34. In this example, this hand device 30 is used to transport the workpiece 100.

[0023] The controller 40 controls the drive of each part of the machine tool 10 in response to instructions from the operator. This controller 40 includes, for example, a processor 42 that performs various calculations and a memory 44 that stores various control programs and control parameters. The controller 40 also has a communication function and can exchange various data, such as machining program data, with other devices. This controller 40 may also include, for example, a numerical control device that calculates the position of the tool 110 and the workpiece 100 in real time. Furthermore, the controller 40 may be a single computer or may be configured by combining multiple physically separated computers.

[0024] The controller 40 controls the movement of the spindle head 18 and the tool post 20 when machining the workpiece 100 with the tool 110. In addition, the controller 40 in this example also drives the hand device 30 to reverse the workpiece 100 attached to the spindle 17, which will be described later.

[0025] Next, we will briefly explain the process of turning the workpiece 100 using the machine tool 10. In the following, one axial end of the workpiece 100 will be referred to as the "first end Ef," and the other axial end as the "second end Es."

[0026] When turning workpiece 100, the workpiece 100 is mounted on the chuck 24 of the headstock 18. The tool 110 is mounted on the turret 22. The controller 40 rotates the spindle 17 and moves the tool post 20 according to the machining program, and performs machining on the workpiece 100.

[0027] Here, during the machining of the workpiece 100, the orientation of the workpiece 100 may be reversed. For example, first, with the first end Ef of the workpiece 100 held by the chuck 24, machining is performed on the area around the second end Es and the middle portion. Hereinafter, machining performed while holding the first end Ef will be called "primary machining". After the primary machining is completed, the workpiece 100 is removed from the chuck 24, rotated 180 degrees, and then the second end Es of the workpiece 100 is reattached to the chuck 24. Then, with the second end Es held by the chuck 24, machining is performed on the area around the first end Ef and the middle portion. Hereinafter, machining performed while holding the second end Es will be called "secondary machining". By performing primary and secondary machining in this way, the entire workpiece can be machined appropriately.

[0028] As is clear from the above explanation, in order to perform secondary processing after primary processing, it is necessary to remove the workpiece 100 from the chuck 24, reverse the orientation of the workpiece 100, and then reattach the workpiece 100 to the chuck 24. In this example, the removal, reversal, and reattachment of the workpiece 100 are performed automatically using the robot 28 and the hand device 30. This configuration reduces the burden on the operator.

[0029] However, depending on the shape of the workpiece 100, it was sometimes difficult to easily reverse and reattach the workpiece 100. To solve this problem, in this example, between the removal and reattachment of the workpiece 100, the workpiece 100 is temporarily placed on the temporary support table 36, and the gripping position of the workpiece 100 is changed by the hand device 30. This will be explained below with reference to Figures 3 to 6. Figures 3 to 6 are schematic diagrams showing the process from the removal of the workpiece 100 from the chuck 24 to its reattachment. Note that in Figures 3 to 6, the links of the robot 28 are schematically shown with simple dashed straight lines.

[0030] First, let's describe the temporary support stand 36. As mentioned above, the temporary support stand 36 is a stand on which the workpiece 100 to be remounted is temporarily placed. This temporary support stand 36 may be fixedly positioned within the processing chamber 12, or it may be provided in a movable manner. In this example, the temporary support stand 36 is attached to the tool mounting section 26 of the turret 22. In addition, multiple types of temporary support stands 36 may be prepared to suit the form of the workpiece 100 being handled. In this case, the temporary support stand 36 attached to the turret 22 may be changed depending on the form of the workpiece 100 that can be handled. Alternatively, multiple types of temporary support stands 36 may be pre-installed on a single turret 22, and the turret 22 may be rotated according to the form of the workpiece 100 being handled.

[0031] Once the primary processing is complete, the controller 40 drives the robot 28 and the hand device 30 to cause the hand device 30 to grip the workpiece 100. Figure 3 shows this state. As is clear from Figure 3, at this time the chuck 24 is holding the first end Ef of the workpiece 100. The hand device 30 is gripping the first gripping position GPf, which is near the second end Es.

[0032] Next, the controller 40 releases the chuck 24 and drives the robot 28 to pull the workpiece 100 out of the chuck 24. Furthermore, the controller 40 then changes the posture of the robot 28 to reverse the posture of the workpiece 100 by 180 degrees. That is, the posture is changed so that the first end Ef faces the positive Z direction and the second end Es faces the negative Z direction.

[0033] After reversing the orientation of the workpiece 100, the controller 40 drives the robot 28 to place the workpiece 100 on the temporary support table 36. Figure 4 shows the workpiece 100 placed on the temporary support table 36. At this time, the controller 40 has previously changed the temporary support table 36 to an appropriate position and orientation. Specifically, the controller 40 rotates the turret 22 so that the mounting surface of the temporary support table 36 is almost horizontal. The controller 40 also moves the tool post 20 so that the temporary support table 36 is within the range of motion of the robot 28.

[0034] Once the workpiece 100 is placed on the temporary support table 36, the controller 40 changes the gripping position of the workpiece 100 by the hand device 30 from the first gripping position GPf to the second gripping position GPs. Figure 5 shows the changes in the gripping position. As is clear from Figure 5, the second gripping position GPs is closer to the first end Ef than the first gripping position GPf.

[0035] If the gripping position can be changed, the controller 40 drives the robot 28 and the chuck 24 to remount the workpiece 100 in the chuck 24. Figure 6 shows the remounting process. As is clear from Figure 6, at this time the chuck 24 holds the second end Es, and the hand device 30 grips the second gripping position GPs, which is away from the second end Es. Once the remounting of the workpiece 100 is complete, the controller 40 moves the robot 28 to a predetermined retracted position and starts secondary processing on the workpiece 100.

[0036] As is clear from the above explanation, in this example, the gripping position of the workpiece 100 by the hand device 30 is changed between the time the workpiece 100 is removed and the time it is reinstalled. The reason for performing this process will be explained with reference to Figure 9.

[0037] Figure 9 shows how the workpiece 100 is remounted without changing the gripping position. As shown in Figure 9, if the gripping position is not changed, the hand device 30 will continue to grip the first gripping position GPf, which is close to the second end Es. In this state, if an attempt is made to mount the second end Es of the workpiece 100 onto the chuck 24, the hand device 30 or its surrounding components may interfere with the chuck 24 or the headstock 18, as shown in Figure 9. In Figure 9, even if an attempt is made to mount the second end Es onto the chuck 24, the base member 34 interferes with the chuck 24, making it impossible to remount the workpiece 100.

[0038] These problems can, of course, be solved by gripping the workpiece 100 at a position away from the second end Es when removing it from the chuck 24 (as in Figure 3), that is, by moving the first gripping position GPf away from the second end Es. However, depending on the shape of the workpiece 100, it may be difficult to move the first gripping position GPf away from the second end Es. For example, in the case shown in Figure 3, because the axial dimension of the workpiece 100 is small, the positions in which the hand device 30 can grip the workpiece without interfering with other members are limited. As a result, it is difficult to move the first gripping position GPf away from the second end Es.

[0039] Furthermore, even if the axial dimension of the workpiece 100 is large, the gripping position may be limited. For example, as shown in Figure 7, a taper may be formed in the central part of the workpiece 100 (the part with cross-hatching in Figure 7). Depending on the type of gripping device 30, it may not be possible to properly grip the part where such a taper is formed. In this case, when the gripping device 30 removes the workpiece 100 from the chuck 24, it can only grip the vicinity of the second end Es of the workpiece 100. As a result, it is difficult to move the first gripping position GPf away from the second end Es.

[0040] In this example, as described above, between removing the workpiece 100 from the chuck 24 and reattaching it, the workpiece 100 can be temporarily placed on the temporary support table 36, and the gripping position can be changed. This allows the second end Es of the workpiece 100 to be reattached to the chuck 24 while preventing interference between the hand device 30 and other components, as shown in Figure 6.

[0041] Naturally, if the first gripping position GPf can be sufficiently far from the second end Es, the workpiece 100 may be directly reattached to the chuck 24 without temporarily placing the workpiece 100 or changing its gripping position. Also, in this example, the workpiece 100 is placed on the temporary placement table 36 after its orientation has been reversed, but this order may be reversed. That is, the workpiece 100 may be placed on the temporary placement table 36, the gripping position by the hand device 30 may be changed, and then the orientation of the workpiece 100 may be reversed by 180 degrees.

[0042] Furthermore, when placing the workpiece 100 on the temporary support table 36, the center of gravity CG of the workpiece 100 is positioned between the pair of support claws 38, as shown in Figure 4. This effectively prevents the workpiece 100 from falling off the temporary support table 36 during temporary placement. In addition, some workpieces 100 have a stepped shape, as shown in Figure 8. When handling such workpieces 100, the installation heights of the two support claws 38 may be varied according to the step.

[0043] In this example, the temporary support table 36 is attached to the turret 22, but the temporary support table 36 may be provided independently of the turret 22. For example, the temporary support table 36 may be attached to the tailstock (not shown) or to a robot other than the robot 28. Alternatively, the temporary support table 36 may be permanently installed inside the machining chamber.

[0044] In this example, the hand device 30 is attached to the robot 28, but the hand device 30 may be attached to other components as long as it is movable. For example, a gantry crane may be installed in the processing room 12, and the hand device 30 may be attached to this gantry crane. [Explanation of Symbols]

[0045] 10 Machine tool, 12 Machining chamber, 14 Door, 16 Cover, 17 Spindle, 18 Headstock, 20 Tool post, 22 Turret, 24 Chuck, 26 Tool mounting section, 28 Robot, 30 Hand device, 32 Gripping arm, 34 Base member, 36 Temporary stand, 38 Mounting jaws, 40 Controller, 42 Processor, 44 Memory, 100 Workpiece, 110 Tool, CG Center of gravity, Ef First end, Es Second end, GPf First gripping position, GPs Second gripping position.

Claims

1. A method for inverting a rod-shaped workpiece, A movable hand device in a machine tool grasps the first gripping position of the workpiece held by the headstock, removes the workpiece from the headstock, then reverses the orientation of the workpiece, and then reattaches the workpiece to the headstock. The machine tool has a temporary stand on which the workpiece can be placed, The hand device, during the period from the removal of the workpiece to its reattachment, places the workpiece on the temporary support table and then changes the gripping position of the workpiece from the first gripping position to the second gripping position. The aforementioned hand device grips the workpiece from a direction perpendicular to the axis of the workpiece. A method for inverting a workpiece, characterized by the following features.

2. A method for inverting a workpiece according to claim 1, The machine tool has one or more tool mounting sections, and a tool post that can change the position and orientation of the tool attached to the tool mounting section. The temporary support stand is attached to the tool mounting section, Prior to placing the workpiece on the temporary support, the tool holder changes the orientation of the temporary support to an orientation on which the workpiece can be placed, and positions the temporary support within the movable range of the hand device. A method for inverting a workpiece, characterized by the following features.

3. A method for inverting a workpiece according to claim 1, The workpiece has a first end that is held by the headstock before inversion, and a second end that is held by the headstock when it is remounted. The second gripping position is further away from the second end than the first gripping position. A method for inverting a workpiece, characterized by the following features.

4. A method for inverting a workpiece according to claim 1, The temporary support platform has a pair of support claws spaced apart from each other, The hand device, when placing the workpiece on the temporary support table, positions the center of gravity of the workpiece between the pair of support claws. A method for inverting a workpiece, characterized by the following features.

5. It is a machine tool, A spindle head that holds the end of a rod-shaped workpiece, A hand device, which is movably mounted in a machine tool, grips the workpiece held by the headstock at a first gripping position, removes the workpiece from the headstock, then reverses the orientation of the workpiece, and then reattaches the workpiece to the headstock. A temporary stand on which the aforementioned workpiece can be placed, The hand device, during the period from the removal of the workpiece to its reattachment, places the workpiece on the temporary support table and then changes the gripping position of the workpiece from the first gripping position to the second gripping position. The aforementioned hand device grips the workpiece from a direction perpendicular to the axis of the workpiece. A machine tool characterized by the following features.

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