Chuck for workpiece, machining device equipped with the same, and machining method using the same

Abstract

To highly accurately and easily machine a workpiece having correlation between front and rear surfaces.SOLUTION: Provided is a chuck for a workpiece, including: a C-axis workpiece head 10 for holding a workpiece W having machining surfaces of a front surface and a rear surface correlated with each other on a chuck 20 for the workpiece so as to be rotatable around a C-axis; a chucking body 21 which is provided on the C-axis workpiece head 10 so as to be integrally rotatable; a chucking part 22 which is provided so as to be rotatable around a workpiece front / rear surface reversing shaft 22b perpendicular to the C-axis with respect to the chucking body 21 and detachably grips the workpiece W; and a front / rear surface reversing driving part 23 which drives the chucking part 22 so as to rotate around the workpiece front / rear surface reversing shaft 22b.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a chuck for a workpiece having front and back machined surfaces that are correlated with each other, a machining apparatus including the same, and a machining method using the same. [Background technology]

[0002] Conventionally, there is known a technique for machining multiple surfaces with high precision by gripping the workpiece at one time, such as a five-surface machining center.

[0003] For example, a known machining apparatus for a scroll-shaped workpiece is described in Patent Document 1, which has an X-axis parallel to the diameter of the base circle of the involute curve of the workpiece, a Y-axis perpendicular to the X-axis, a Z-axis parallel to the central axis of the tool, and a C-axis parallel to the Z-axis.

[0004] Furthermore, for a workpiece in which the front and back sides are correlated, when attempting to process both sides with a single grip, the workpiece is rotated along one axis, either around the A-axis parallel to the X-axis or the B-axis parallel to the Y-axis, which are located away from the C-axis. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-283235 A Summary of the Invention [Problem to be solved by the invention]

[0006] In a conventional work chuck, for example, as shown in FIG. 8(a), a case is assumed in which the back surface of a work W', which is a scroll-shaped workpiece, is machined.

[0007] After machining in a state where the tool is displaced in the Y-axis direction by a positional offset O1' between the workpiece center C1' and the machining center C2' due to thermal deformation, if the workpiece W' is then inverted around the A-axis, which is parallel to the X-axis, as shown in Figure 8(b), the position of the spiral rib portion Wc' on the front side will also be displaced in the Y-axis direction by the positional offset O1'. For this reason, the direction of the positional offset in the front side machining is opposite to that in the back side machining, and the amount of positional offset can be up to twice as large (2 x O1). Even if the workpiece is rotated around the A-axis in a state where it is displaced in the Y direction, a maximum of twice the offset occurs.

[0008] If machining is performed with the surface shifted upward in the Y direction, for example in Fig. 8, the position of the back surface will shift upward on the paper, but if it is rotated around the B axis parallel to the shifted direction, the spiral rib will also shift upward on the paper, so the amount of shift from the machining reference will be O1', but no shift will occur on the front and back surfaces. This phenomenon occurs similarly with the shift in the X direction and with rotation around the A axis.

[0009] As shown in this example, if there is an initial error or thermal deformation in the X-axis or Y-axis direction due to improper assembly of the chuck part of the machining device, the workpiece, etc., when the product is turned over, a misalignment will occur between the front and back.

[0010] To adjust for machining deviations caused by thermal deformation or the like, a relatively tedious correction process based on three-dimensional measurements using a three-dimensional measuring device is required.

[0011] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to enable a workpiece having a correlation between its front and back surfaces to be machined easily with high precision. [Means for solving the problem]

[0012] In order to achieve the above object, in the present invention, a front-back reversing axis is provided on the chuck body on the C-axis.

[0013] Specifically, the work chuck of the first invention includes a C-axis work head that holds a workpiece having a front and back machined surfaces that are correlated with each other so as to be rotatable about the C-axis; A chuck body provided integrally with the C-axis work head; A chuck portion that is rotatably provided around a workpiece front / back inversion axis perpendicular to the C axis with respect to the chuck body and that detachably holds the workpiece; The workpiece reversing device has a front-back reversing drive unit that drives the chuck unit to rotate around the workpiece reversing axis.

[0014] With the above configuration, since the workpiece front-back inversion axis is on the C-axis, for example, any deviation due to thermal deformation in the cutting direction will result in a positional deviation in the outer diameter direction because the C-axis rotation is used for indexing machining. Therefore, when the hole size in the center of the workpiece is checked with a micrometer or the like, half of the increase or decrease in the hole diameter is a positional deviation due to thermal deformation. By correcting this, it is also possible to correct the deviation in the machining position, and machining can be performed while accurately maintaining the correlation between the front and back.

[0015] On the other hand, deviations due to thermal deformation in a direction perpendicular to the cutting direction have almost no effect on the diameter of the central hole. The surrounding holes are machined as if they were shifted in the rotation direction. Furthermore, even in the machining of spiral ribs, it has almost no effect on the shape accuracy. For example, if a deviation of 0.02 mm occurs in the vertical direction and the surrounding holes have a PCD of 80 mm, the angular deviation is, tan -1 (0.02 / 40)=0.0286° However, the deviation of the spiral rib formed by the involute curve is as follows, assuming that the base circle radius is 2.4 mm: 0.0286×2.4×π÷180=0.0012 mm And it has almost no impact.

[0016] In the second invention, in the first invention, The workpiece is a disk-shaped workpiece, The chuck portion is A circular ring portion that grips the workpiece from an outer periphery side; The workpiece has a pair of rotating shafts extending from the outer periphery of the annular portion and constituting the workpiece front-back inversion axis.

[0017] According to the above-mentioned configuration, the chuck portion grips the outer periphery of the disk-shaped workpiece and rotates it around the pair of rotating shafts, so that the front and back machined surfaces can be easily machined with a simple configuration.

[0018] In a third aspect of the present invention, in the first aspect of the present invention, The workpiece inversion drive unit is a hydraulic or pneumatic rotary actuator that drives the workpiece inversion shaft, Power is supplied from a rotary joint provided on the C-axis work head.

[0019] According to the above configuration, even if the rotation inversion drive unit is rotated together with the C-axis, power can be reliably supplied from the rotary joint to the rotary actuator to rotate the workpiece.

[0020] In a fourth aspect of the present invention, in the first aspect of the present invention, A counterweight for balancing the weight of the front / back inversion drive unit is provided on the chuck body so as to rotate integrally with the chuck body around the C-axis.

[0021] According to the above-mentioned configuration, even when the front / back inversion drive unit rotates around the C-axis together with the chuck body, the counterweight balances the weight, so that adverse effects such as vibration and noise due to rotation are unlikely to occur.

[0022] A machining apparatus according to a fifth aspect of the present invention comprises: a Y-axis table that is provided on the bed and supports the C-axis work head movably in a Y-axis direction; A work chuck according to any one of the first to fourth aspects of the present invention; A column provided on the bed adjacent to the Y-axis table; a Z-axis table movable in the column along a Z-axis direction; an X-axis table that is movable in an X-axis direction perpendicular to the Z-axis with respect to the Z-axis table; A spindle provided on the X-axis table and to which a tool is rotatably attached; The machine includes a control unit that controls at least the front / back inversion drive unit and machines the front and back surfaces of the workpiece without changing the grip of the workpiece.

[0023] According to the above configuration, a highly marketable machining device can be obtained, which can perform machining while accurately maintaining the correlation between the front and back.

[0024] The machining method of the sixth invention comprises the steps of: A process of gripping a workpiece having a front and back machined surfaces correlated with each other in a chuck portion of a chuck provided integrally with a C-axis for rotation; indexing one of the front and back surfaces of the workpiece with a tool of a machining device around the C-axis; a step of rotating the chuck portion around a workpiece inversion axis provided on the C-axis and perpendicular to the C-axis, without changing the grip, to invert the workpiece; indexing the other of the front and back surfaces of the workpiece with a tool of the machining device around the C-axis; and removing the workpiece whose front and back surfaces have been machined from the chuck portion.

[0025] According to the above configuration, since the workpiece front-back inversion axis is on the C-axis, for example, a deviation due to thermal deformation in the cutting direction results in a positional deviation in the outer diameter direction because the workpiece is indexed by rotating the C-axis. When the hole size in the center of the workpiece is checked with a micrometer or the like, half of the increase or decrease in the hole diameter is a positional deviation due to thermal deformation. By correcting this, the deviation in the machining position can also be corrected, and machining can be performed while accurately maintaining the correlation between the front and back. In addition, a deviation due to thermal deformation in the direction perpendicular to the cutting direction has almost no effect on the correlation between the front and back and the machining accuracy, allowing accurate machining. Effect of the Invention

[0026] As described above, according to the present invention, the chuck body is provided with a chuck portion that is rotatable around the workpiece front / back inversion axis perpendicular to the C axis, and the workpiece is removably held by this chuck portion, so that workpieces whose front and back sides are correlated can be machined with high precision. [Brief description of the drawings]

[0027] [Figure 1] 1 is a perspective view showing an overview of a machining device equipped with a workpiece chuck according to an embodiment of the present invention; [Diagram 2] 2 is an enlarged perspective view showing a workpiece chuck and its surroundings in the machining device; FIG. [Diagram 3] FIG. 2 is a cross-sectional view for explaining a schematic configuration of a work chuck. [Figure 4] FIG. 2A is a perspective view showing the work chuck and its surroundings when the back side of the workpiece is machined, and FIG. 2B is a bottom view of the workpiece as seen from the back side. [Diagram 5] FIG. 2A is a perspective view showing the work chuck and its surroundings when the front surface side of the workpiece is machined, and FIG. 2B is a bottom view of the workpiece as viewed from the front surface side. [Figure 6] 4 is a flowchart showing the steps of a method for machining a workpiece. [Figure 7] FIG. 1 is a plan view for explaining the displacement caused by thermal deformation when a workpiece is inverted using a work chuck according to an embodiment of the present invention, in which (a) shows the back side of the workpiece and (b) shows the front side of the workpiece, the solid line shows the ideal machined shape, and the two-dot chain line shows the machined result. [Figure 8] FIG. 1 is a plan view for explaining the displacement caused by thermal deformation when a workpiece is inverted using a workpiece chuck according to the conventional technology, in which (a) shows the back side of the workpiece and (b) shows the front side of the workpiece, the solid line shows the ideal machined shape, and the two-dot chain line shows the machined result. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0029] -Configuration of machining equipment- FIG. 1 shows a machining device 1, such as an NC machine tool, equipped with a workpiece chuck 20 according to an embodiment of the present invention. This machining device 1 includes a bed 2 placed on a factory floor or the like, a Y-axis table 3 mounted on the bed 2 so as to be slidable in the Y-axis direction, a column 4 mounted adjacent to the Y-axis table 3 on the bed 2, a Z-axis table 5 which is slidable in the Z-axis direction on the column 4, and an X-axis table 6 which is slidable in the X-axis direction perpendicular to the Z-axis relative to the Z-axis table 5.

[0030] The Y-axis table 3, Z-axis table 5 and X-axis table 6 can be slid by actuators (not shown) under instructions from the control unit 50. The control unit 50 is, for example, a programmable logic controller (PLC), and controls the entire machining apparatus 1, for example.

[0031] 2, the X-axis table 6 is provided with a spindle 8 to which a tool such as an end mill 7, a drill tool, a tapping tool, a turning tool, a boring tool, a milling tool, etc. (none of which are shown) is rotatably attached. The spindle 8 is rotated by a tool rotation motor 9 under the control of a control unit 50.

[0032] 3, a C-axis work head 10 for gripping a workpiece W is provided on the Y-axis table 3. The C-axis work head 10 is provided with a workpiece chuck 20 that is rotatable about the C-axis that is parallel to the Z-axis.

[0033] The workpiece W in this embodiment is, for example, a compressor part as a disk-shaped workpiece having machined front and back surfaces that are correlated with each other, as shown in Figures 4 and 5. The shape of the workpiece W is not particularly limited as long as it has machined front and back surfaces that are correlated with each other.

[0034] As shown in Figs. 3 to 5, the work chuck 20 is provided with, for example, a columnar or cylindrical C-axis work head 10 that holds the work chuck 20 rotatably about the C-axis. The C-axis work head 10 is rotatable on the Y-axis table 3 via a rotary joint 11, and is controlled to rotate at a predetermined rotation speed and angle by an electric motor (not shown) or the like in response to an instruction from the control unit 50. The Y-axis table 3 is slidable on the Y-axis table rail 2a of the bed 2 that extends in the Y-axis direction, and is slidable together with the Y-axis table 3 together with the rotary joint 11 connected to the C-axis work head 10 and the air or hydraulic piping and electric wires that pass through it.

[0035] The workpiece chuck 20 includes a chuck body 21 that is provided to rotate integrally with the C-axis work head 10. The shape of this chuck body 21 is not particularly limited, but for example, as shown in Figures 2 and 3, it is concave-shaped or U-shaped when viewed from the front, and this chuck body 21 is provided to be rotatable around a workpiece front / back inversion axis 22b (A-axis) perpendicular to the C-axis, and includes a chuck portion 22 that detachably grips the workpiece W.

[0036] The chuck portion 22 has an annular portion 22a that grips the workpiece W from the outer periphery, and a workpiece front / back inversion shaft 22b (see FIG. 3) that extends from the outer periphery of the annular portion 22a and is made up of a pair of rotating shafts. The annular portion 22a is capable of gripping only the outer periphery of the workpiece W with the front and back surfaces of the workpiece W exposed by expanding or contracting the inner diameter thereof, for example, by supplying compressed air.

[0037] The chuck body 21 also has a front-back inversion drive unit 23 that drives the chuck portion 22 to rotate around the A-axis serving as the workpiece inversion axis 22b. The front-back inversion drive unit 23 is instructed by the control unit 50 to rotate the workpiece inversion axis 22b, thereby inverting the workpiece W together with the chuck portion 22.

[0038] As described in more detail below, the control unit 50 controls the front / back inversion drive unit 23 in this manner, making it possible to machine the front and back surfaces of the workpiece W without having to change the workpiece W over.

[0039] For example, the front / back inversion drive unit 23 is a pneumatically driven rotary actuator that drives the workpiece front / back inversion shaft 22b, and is configured so that power is supplied from the rotary joint 11 provided on the C-axis work head 10.

[0040] Specifically, as shown in Fig. 3, for example, air pressure from a compressor is sent to A port and B port provided on the workpiece inversion drive unit 23 (rotary actuator) on the A axis (workpiece inversion axis 22b) via a control valve (not shown). Air pressure from the compressor is also sent to the chuck clamp 22c and chuck seating confirmation unit 22d provided on the workpiece inversion axis 22b on the opposite side via a control valve. With this configuration, the control valve is appropriately switched upon receiving a signal from the control unit 50, and the workpiece W can be gripped by the chuck clamp 22c, confirmed to be seated, and also the workpiece W can be inverted.

[0041] A counterweight 24 for balancing the weight of the front / back inversion drive unit 23 is provided on the chuck body 21 and rotates integrally with the chuck body 21 about the C axis. This weight balance may be adjusted by increasing the weight of the counterweight 24 or by shifting its position.

[0042] -Machining method- Next, a machining method using the workpiece chuck 20 according to this embodiment will be described with reference to FIG.

[0043] In the workpiece gripping process of step S01, a workpiece W having a front and back machined surfaces that are correlated with each other is gripped by the chuck portion 22 of the chuck body 21 that is provided on the C axis and rotates integrally with the C axis. For example, a transport device such as an operator or a robot hand (not shown) attaches or loads the workpiece W to the chuck portion 22. At this time, as shown in FIG. 4(a), the back surface of the workpiece W faces the end mill 7 side.

[0044] Next, in the workpiece back surface machining process S02 in step S02, the back surface of the workpiece W is indexed around the C-axis by the end mill 7 of the machining device 1. Holes concentric with the C-axis center can be machined into a highly accurate circle by rotating the C-axis and moving in the cutting direction. End face machining can also be machined into a highly accurate flat surface by rotating the C-axis and cutting in the Z direction. On the other hand, holes that are not concentric with the center are indexed using the C-axis. Since the indexing process itself is a known technique, a detailed description will be omitted, but in the indexing process, holes that are not concentric are indexed to the same position as the X-axis, and the C-axis is fixed vertically, and the end mill 7 is machined while moving relatively in the X-axis and Y-axis directions. Then, when the entire machining is completed, the back surface machining of the workpiece W is completed in step S03.

[0045] In this embodiment, even when the front / back inversion drive unit 23 rotates together with the chuck body 21, the counterweight 24 balances the weight, so that adverse effects due to the rotation are unlikely to occur. If the weight balance is not achieved, the counterweight 24 may be fine-tuned.

[0046] Next, in a front-back inversion process in step S04, the workpiece W is inverted from its back surface to its front surface by rotating about a workpiece front-back inversion axis 22b (A axis) that is provided on the C axis and perpendicular to the C axis, without changing the grip of the chuck portion 22. As shown in the figure, in the case of a vertical machine, chips remaining in holes, etc. during inversion fall to the bottom by gravity and are collected, which has the advantage that no chips remain on the workpiece W.

[0047] In this embodiment, even if the rotation drive unit 23 is configured to rotate together with the C-axis, the workpiece W can be rotated by reliably supplying power from the rotary joint 11.

[0048] Next, in the surface machining process of step S05, surface machining is started. Here, the surface of the workpiece W is machined with the end mill 7 of the machining device 1 by synchronizing the C-axis, X-axis, and Y-axis as disclosed in, for example, JP-A-7-51916, thereby enabling high-speed machining with high precision.

[0049] Then, in step S06, the surface processing is completed.

[0050] Next, in step S07, the workpiece W is turned over again and the workpiece is placed in the workpiece exchange position. As shown in the figure, in the case of a vertical machine, chips remaining in holes, etc., during turning over fall to the bottom by gravity and are collected, which has the advantage that no chips remain on the workpiece W.

[0051] In this embodiment, with a simple configuration, the chuck portion 22 grasps the outer periphery of the workpiece W, which is a disk-shaped workpiece, and rotates it around the workpiece front / back inversion axis 22b, thereby easily machining the front and back machined surfaces of the workpiece W.

[0052] Next, in an unloading process in step S07, the worker or the conveying device removes the workpiece W whose front and back surfaces have been machined from the chuck portion 22. After that, the process returns to step S01.

[0053] The correction of the deviation of the workpiece center C1 will be specifically explained with reference to the drawings. Since the workpiece front-back inversion axis 22b (A-axis) is on the C-axis, for example, deviation due to thermal deformation in the cutting direction is indexed to the workpiece center C1 by rotating the C-axis, so that the deviation is a position deviation in the outer diameter direction of the outer peripheral hole Wb, as shown by the two-dot chain line in FIG. 7(a). When the size of the hole Wa in the workpiece center C1 is checked with a micrometer or the like, half of the increase or decrease in the hole diameter is a position deviation due to thermal deformation. By correcting this, the deviation of the machining position can also be corrected, and machining can be performed while accurately maintaining the correlation between the front and back. The measurement here is not a complicated task such as measurement using a three-dimensional measuring device, but is merely a radial measurement, so it is an extremely easy task.

[0054] As shown by the two-dot chain line in Fig. 7(b), in machining the front side, the workpiece front / back inversion axis 22b (A-axis) is on the C-axis, so that deviation in the cutting direction due to thermal deformation, for example, results in a thickness error in the spiral rib portion Wc because machining is performed by synchronizing the C-axis with the X-axis and Y-axis as shown in JP-A-7-51916. Fig. 7(b) shows the spiral rib portion Wc as being thin, but it may be thick depending on the machining position and direction. However, the error can be absorbed by correcting the deviation in the machining position by measuring the back side, so the thickness of the spiral rib portion Wc can also be corrected at the same time.

[0055] Therefore, according to the workpiece chuck 20 of this embodiment, the chuck body 21 is provided with a chuck portion 22 that is rotatable around the workpiece front / back inversion axis 22b perpendicular to the C axis, and the workpiece W is removably held by this chuck portion 22, so that the workpiece W, which has a correlation between its front and back surfaces, can be easily machined with high precision.

[0056] In this embodiment, the method of machining using one end mill 7 has been described, but a boring tool, a milling tool, a drill tool, or the like may be used for each machining step.

[0057] (Other embodiments) The present invention may be configured as follows with respect to the above embodiment.

[0058] That is, in the above embodiment, the front-back reversing drive unit 23 is a pneumatically driven rotary actuator, but it may be a hydraulically driven rotary actuator, or may be directly driven by pneumatic, hydraulic or electric drive, or may be driven by a timing belt or a rack and pinion. Also, pneumatic, hydraulic or electric power may be supplied through a rotatable C-axis, or a structure may be adopted in which pneumatic, hydraulic or electric power can be connected when stopped.

[0059] In the above embodiment, a programmable logic controller (PLC) has been described as an example of the control unit 50. However, the control unit 50 may be configured in any physical manner as long as it controls the "machining device 1." For example, the control unit 50 may use software (programs) such as a microcomputer. Alternatively, the control unit may be realized by combining hardware (circuit components).

[0060] It should be noted that the above-described embodiments are essentially preferred examples, and are not intended to limit the scope of the present invention, its applications, or uses. [Explanation of symbols]

[0061] 1 Machining equipment 2 beds 2a Y-axis table rail 3 Y-axis table 4. Column 5 Z-axis table 6 X-axis table 7 End Mill 8 Spindle 9 Tool rotation motor 10 C-axis work head 11 Rotary joint 20 Chuck 21 Chuck body 22 Chuck part 22a Circular section 22b Workpiece front / back inversion axis (rotating shaft) 22c Chuck Clamp 22d Chuck seating confirmation part 23 Front / reverse drive unit 24 Counterweight 50 Control section

Claims

1. A C-axis work head that holds a workpiece having front and back machined surfaces that are correlated with each other so as to be rotatable about the C-axis; A chuck body that is rotatably mounted on the C-axis work head; A chuck portion that is rotatably provided on the chuck body around a workpiece front / back inversion axis perpendicular to the C-axis and that detachably holds the workpiece; A workpiece reversing drive unit that drives the chuck unit to rotate around the workpiece reversing axis. A workpiece chuck characterized by:

2. The workpiece is a disk-shaped workpiece, The chuck portion is A circular ring portion that grips the workpiece from an outer periphery side; A pair of rotating shafts extending from the outer periphery of the annular portion and constituting the workpiece front-back inversion axis are provided.

2. The workpiece chuck according to claim 1 .

3. The workpiece inversion drive unit is a hydraulic or pneumatic rotary actuator that drives the workpiece inversion shaft, Power is supplied from a rotary joint provided on the C-axis work head.

2. The workpiece chuck according to claim 1 .

4. A counterweight for balancing the weight of the front / back inversion drive unit is provided on the chuck body and rotates integrally with the chuck body around the C-axis.

2. The workpiece chuck according to claim 1 .

5. A bed and a Y-axis table that is provided on the bed and supports the C-axis work head movably in a Y-axis direction; A workpiece chuck according to any one of claims 1 to 4; A column provided on the bed adjacent to the Y-axis table; a Z-axis table movable in the column along a Z-axis direction; an X-axis table movable in an X-axis direction perpendicular to the Z-axis with respect to the Z-axis table; a spindle provided on the X-axis table and to which a tool is rotatably attached; A control unit that controls at least the front / back inversion drive unit and machines the front and back surfaces of the workpiece without changing the grip of the workpiece. A machining apparatus comprising:

6. A process of gripping a workpiece having a front and back machined surfaces correlated with each other in a chuck portion of a chuck provided on a C-axis so as to rotate integrally with the workpiece; indexing one of the front and back surfaces of the workpiece with a tool of a machining device around the C-axis; a step of rotating the chuck portion around a workpiece inversion axis that is provided on the C-axis and perpendicular to the C-axis, without changing the grip, to invert the workpiece; indexing the other of the front and back surfaces of the workpiece with a tool of the machining device around the C-axis; and removing the workpiece whose front and back surfaces have been machined from the chuck portion. A machining method comprising the steps of:

Images