Sealing surface processing method and machine tool

Abstract

To provide a machining method and a machining device of a seal surface capable of machining the seal surface having no cutter marks in the leak direction by using an inexpensive general-purpose tool.SOLUTION: A machining method of a seal surface includes: subjecting a shafted polishing tool T to revolving motion relative to a workpiece W along a closed loop of seal surfaces to be machined while bringing a tip surface of the shafted polishing tool T into contact with the workpiece W; and, while the shafted polishing tool T is performing the revolving motion, polishing, by the shafted polishing tool T, the surfaces 204a, 220a of the workpiece W by subjecting the shafted polishing tool T to rotating motion in a same direction as the revolving motion with a difference in phase within ±180° with respect to the revolving motion.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a method for processing a seal surface for polishing a seal surface of a workpiece with an axially attached polishing tool and Machine tool relates to.

Background Art

[0002] When joining two members whose joint surfaces require airtightness, such as a vacuum chamber used in a semiconductor manufacturing apparatus, a PVD (Physical Vapor Deposition) apparatus, a CVD (Chemical Vapor Deposition) apparatus, etc., and a pipe for applying a vacuum to the vacuum chamber, the joint surface between the two members is generally polished. However, by using a polishing tool such as a grinding stone, streaks called cutter marks and grinding surface marks are inevitably formed on the joint surface along the moving direction of the abrasive grains. These streaks are usually on the order of μm and it is difficult to completely fill them with a sealing member such as an O-ring or a gasket. Therefore, if cutter marks exist in the direction (hereinafter referred to as the leak direction) that allows communication between the inside and outside of the joint surface, leakage will occur due to these cutter marks. In addition, when a leak is discovered after the vacuum chamber device is assembled, large-scale disassembly and reassembly are required. Therefore, a visual inspection is performed to check whether the cutter marks on the seal surface are concentric before assembly, and if necessary, a polishing operation is performed manually.

[0003] Therefore, Patent Document 1 describes a processing method and a processing apparatus for polishing a joint surface so that cutter marks do not occur in the leak direction by moving a polishing tool that rotates around a rotation axis parallel to the joint surface while the direction of the rotation axis of the polishing tool is perpendicular to the direction of relative feed along the contour shape of the joint surface.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the processing method and processing apparatus of Patent Document 1, a dedicated polishing tool is required, which increases the processing cost. Furthermore, since the polishing tool of Patent Document 1 is a belt polishing tool that runs a polishing belt between two pulleys, there is a problem that a narrow groove for accommodating an O-ring and a small-diameter sealing surface cannot be polished.

[0006] An object of the present invention is to solve such problems of the prior art, and to polish using an inexpensive general-purpose tool so that cutter marks do not occur in the leakage direction, and to polish the bottom surface of a narrow groove and a small-diameter sealing surface so that cutter marks do not occur in the leakage direction. A processing method and Machine tool are provided.

Means for Solving the Problems

[0007] To achieve the above object, Attached to the spindle of the machine tool by a shaft-mounted polishing tool Placed on the table of the machine tool In a method for processing a sealing surface for polishing the sealing surface of a workpiece, while bringing the tip surface of the shaft-mounted polishing tool into contact with the workpiece, the shaft-mounted polishing tool is revolved relative to the workpiece along a closed loop Using one or both of a linear feed axis and a rotary feed axis for relative movement between the spindle and the table of the machine tool and while the shaft-mounted polishing tool is One revolution revolving, the shaft-mounted polishing tool is rotated When the circumferential angle is 360°, within ±180° A value that has no common divisor with 360 out of phase with the revolution motion in the same direction as the revolution motion Using the spindle of the machine tool to provide a method for processing a sealing surface.

[0008] Furthermore, according to the present invention, in a processing apparatus for a sealing surface for polishing the sealing surface of a workpiece by a shaft-mounted polishing tool, the shaft-mounted polishing tool To mounted Do on a main shaft, a table on which the workpiece is mounted, and the Main recordMove the shaft relative to the table Having one or both of a linear feed axis and a rotary feed axis A feed shaft device and the front Main record Comprising a control device for controlling the rotation of the shaft and the feed shaft device, While the control device brings the tip surface of the shaft-mounted grinding tool into contact with the workpiece, the shaft-mounted grinding tool is revolved relative to the workpiece along a closed loop Using one or both of the linear feed axis and the rotary feed axis When the shaft-mounted grinding tool revolves relative to the workpiece, and during one revolution of the shaft-mounted grinding tool, when the circumferential angle with respect to the revolution is 360°, the shaft-mounted grinding tool is rotated in the same direction as the revolution with a phase difference that is a value within ±180° and has no common divisor with 360, for the sealing surface Machine tool is provided.

Advantages of the Invention

[0009] According to the present invention, since the rotation is performed with a phase difference within ±180° with respect to the revolution, even when an inexpensive shaft-mounted grinding tool is used, cutter marks are not formed in the leakage direction, and it becomes possible to grind a uniform and good sealing surface. Further, as an example, by using a thin shaft-mounted grinding tool, it is possible to process even a narrow sealing surface such as a groove for accommodating an O-ring.

Brief Description of the Drawings

[0010]

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Embodiments for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic side view showing an example of a machine tool to which the present invention is applicable. In FIG. 1, the machine tool 100 is a vertical machining center. In the present embodiment, the machine tool 100 is a three-axis machining machine having feed axes of three orthogonal axes (X-axis, Y-axis, Z-axis).

[0012] The machine tool 100 includes a bed 102 as a base fixed to the floor surface of a factory or the like. A column 104 is erected on the rear end side of the upper surface of the bed 102. On the front surface of the column 104, an X slider 106 is attached so as to be reciprocally movable in the X-axis direction which is the horizontal left-right direction (the direction perpendicular to the paper surface in FIG. 1).

[0013] The column 104 is provided with a ball screw (not shown) extending in the X-axis direction and an X-axis servo motor Mx connected to one end of the ball screw as an X-axis feed device for reciprocally driving the X slider 106. A nut (not shown) engaging with the ball screw is attached to the X slider 106. Further, in order to detect the position of the X-axis feed device, an X-axis digital scale (not shown) is provided on the column 104.

[0014] On the front surface of the X slider 106, a spindle head 114 is disposed so as to be reciprocally movable in the Z-axis direction which is the vertical direction. The X slider 106 is provided with a ball screw (not shown) extending in the Z-axis direction and a Z-axis servo motor Mz connected to one end of the ball screw as a Z-axis feed device for reciprocally driving the spindle head 114. A nut (not shown) engaging with the ball screw is attached to the spindle head 114. Further, in order to detect the position of the Z-axis feed device, a Z-axis digital scale (not shown) is provided on the X slider 106.

[0015] The spindle head 114 rotatably supports the spindle 112 about a rotation axis Os extending in the vertical direction. The spindle head 114 includes a spindle servo motor Ms for rotationally driving the spindle 112 and a rotary encoder (not shown) for detecting the rotational position and rotational speed of the spindle 112 around the rotation axis Os.

[0016] A tool T is detachably mounted on the tip of the spindle 112. In FIG. 1, the tool T is mounted on the tip of the spindle 112 via a tool holder 116. The machine tool 100 can be provided with a tool magazine (not shown) storing a plurality of tools T and an automatic tool changer (not shown) for exchanging the tool T between the tool magazine and the spindle 112.

[0017] A table 108 is disposed on the front end side (the left side in FIG. 1) of the bed 102. The table 108 is adapted to fix a workpiece W to be machined on the upper surface facing the spindle 112. The table 108 is mounted on a Y slider 110 movable in the Y-axis direction which is a horizontal front-rear direction perpendicular to the X axis. As a Y-axis feed device for reciprocally driving the Y slider 110, the bed 102 is provided with a ball screw (not shown) extending in the Y-axis direction and a Y-axis servo motor My connected to one end of the ball screw. A nut (not shown) engaging with the ball screw is attached to the Y slider 110. Further, in order to detect the position of the Y-axis feed device, the bed 102 is provided with a Y-axis digital scale (not shown).

[0018] A rotary cutting tool (not shown) such as an end mill or a drill can be mounted as the tool T on the tip of the spindle 112. However, in the present invention, in particular, a shaft-mounted polishing tool is used as the tool T. The shaft-mounted polishing tool includes a shaft portion extending along a central axis and a polishing action portion provided at one end of the shaft portion.

[0019] Referring to FIG. 3, as an example of the shaft-mounted polishing tool used in the present invention, a shaft-mounted brush tool is shown. The shaft-mounted brush tool 300 includes a shaft portion 302 extending along a central axis Ot, and a plurality of brushes 304 extending substantially parallel to the central axis Ot as a polishing action portion provided at the tip of the shaft portion 302. The brushes 304 are held by a holding portion 306 provided at the tip of the shaft portion 302 so as to generally exhibit a cylindrical shape as a whole. The brushes 304 project from the holding portion 306 with the same length such that the tips of the respective brushes 304 are arranged in a plane Pe perpendicular to the central axis Ot, and the tips of the brushes 304 as an aggregate form the tip surface of the shaft-mounted brush tool 300. Further, in this example, the tip of each brush 304 provides a polishing action point of the shaft-mounted polishing tool. Here, as the material of the brush 304, nylon with abrasive grains, ceramic wire, metal wire, natural hair, etc. can be used.

[0020] Referring to FIG. 4, as another example of the shaft-mounted polishing tool, a shaft-mounted grinding stone is shown. The shaft-mounted grinding stone 310 includes a shaft portion 312 extending along a central axis Ot, and a grinding stone 314 as a polishing action portion provided at the tip of the shaft portion 312. The grinding stone 314 can be formed by binding abrasive grains with a forming agent and forming them into a columnar shape. The grinding stone 314 has a tip surface perpendicular to the central axis Ot. That is, the abrasive grains on the end surface of the grinding stone 314 are arranged in a plane Pe perpendicular to the central axis Ot. It is configured to provide a polishing action point of the shaft-mounted polishing tool.

[0021] Next, the workpiece W to be processed according to the present invention will be described. Referring to FIGS. 5 to 7, as an example of the workpiece W to be processed according to the present invention, for example, a joint portion between a vacuum chamber used in a semiconductor manufacturing apparatus, a PVD apparatus, a CVD apparatus, etc. and a pipe for applying a vacuum to the vacuum chamber is shown.

[0022] In FIGS. 5 to 7, a pipeline 208 is joined to a side wall 220 by a flange 200. The side wall 220 can be one of the side walls forming a vacuum chamber. A port hole 222 is formed in the side wall 220. The port hole 222 can be a circular or cylindrical hole centered on an axis O. A plurality of bolt holes 224 with internal threads are formed in the side wall 220. In this embodiment, four bolt holes 224 are arranged at equal angular intervals around the axis O.

[0023] The pipeline 208 is joined to the side wall 220 by the flange 200. A central opening 202 and a plurality of through holes 210 are formed in the flange 200. In this embodiment, a circular central opening 202 centered on the axis O and four through holes 210 arranged at equal angular intervals around the axis O are formed. The pipeline 208 is joined to the flange 200 by a known joining method such as welding so as to be coaxial with the central opening 202. By passing bolts 212 through the four through holes 210 and screwing the bolts 212 into the bolt holes 224, the flange 200 is coupled to the side wall 220. When the flange 200 is coupled to the side wall 220, the pipeline 208, the central opening 202, and the port hole 222 are coaxial with respect to the common axis O.

[0024] In the flange 200, a groove 204 for receiving a seal member is formed on the surface facing and contacting the side wall 220. In this embodiment, a circular groove 204 centered on the axis O is formed, and an O-ring 206 as a seal member is accommodated in the groove 204. When the flange 200 is coupled to the side wall 220, the O-ring 206 in the groove 204 contacts the bottom surface 204a of the groove 204 and the surface portion 220a of the side wall 220 facing the bottom surface 204a. Therefore, in order to maintain a high degree of vacuum in the vacuum chamber, it is necessary to prevent leakage from between the O-ring 206 and the bottom surface 204a and the surface portion 220a. For this purpose, the seal surfaces with which the seal member contacts, namely the bottom surface 204a and the surface portion 220a in this embodiment, are polished by an axial polishing tool T as described later.

[0025] Referring to FIG. 1, the machine tool 100 further includes a control device 10 for controlling the machine tool 100. The control device 10 includes an NC device for controlling the servo motors Mx, My, Mz of each of the feed devices of the three orthogonal axes of the X-axis, Y-axis, and Z-axis and the servo motor Ms of the main shaft 112, and a tool magazine (not shown), an automatic tool changer (not shown), a machining fluid supply device (not shown), an oil-air supply device (not shown), and a compressed air supply device (not shown) of the machine tool, and can include a machine control device for controlling the attached devices of the machine tool.

[0026] Referring to FIG. 2, the control device 10 includes a numerical control unit 12 and a rotation control unit 14 as main components. The numerical control unit 12 can be constituted by a general NC device. The rotation control unit 14 can be constituted by a computer including a CPU (central processing element), a memory device such as a RAM (random access memory) and a ROM (read only memory), a storage device such as an HDD (hard disk drive) and an SSD (solid state drive), an input / output port, and a bidirectional bus for interconnecting these, and related software. The rotation control unit 14 can be configured software-wise as a part of the NC device or the machine control device.

[0027] Based on the NC program 22 input by the operator or received from a CAM (not shown) and the coordinate values detected by the digital scales of the X-axis, Y-axis, and Z-axis and the rotary encoder of the main shaft servo motor Ms, the numerical control unit 12 controls the servo motors 26 (Mx, My, Mz, Ms) of the feed devices of the X-axis, Y-axis, and Z-axis and the main shaft 112, relatively moves the table 108 and the spindle head 114, and machines the workpiece W with the tool T.

[0028] The rotation control unit 14 includes a tool position calculation unit 16, a phase difference memory unit 18, and a spindle rotation angle calculation unit 20. The tool position calculation unit 16 receives the current position coordinates of the tool T from the numerical control unit 12. The current position coordinates of the tool T can be a position command generated in the numerical control unit 12 according to an NC program. Alternatively, the current position coordinates of the tool T may be generated based on readings of digital scales on the X-axis, Y-axis, and Z-axis.

[0029] Next, the tool position calculation unit 16 converts the position coordinates of the tool T into polar coordinates with respect to the axis O of the closed-loop shape of the seal surface to be machined, and calculates the revolution angle θ of the tool T around the axis O. In the present invention, for polar coordinates, since the seal surface to be machined is a plane, a plane perpendicular to the axis O including the seal surface and the intersection of the axis O are taken as the pole, and it includes one radial coordinate and one angular coordinate. The revolution angle θ of the tool T around the axis O is given by one of the angular coordinates of the polar coordinates thus obtained.

[0030] The phase difference memory unit 18 stores the phase difference Δφ (FIG. 9) input by the operator from the phase difference input unit 24. The phase difference input unit 24 can be, for example, a touch panel (not shown) provided on an operation panel (not shown) of the machine tool 100 or a keyboard (not shown). The phase difference is the difference between the revolution angle (rotation angle of the revolution motion) θ of the tool T and the rotation angle (rotation angle of the rotation motion) φ (FIGS. 6 and 7). In the present invention, the revolution motion is the relative rotation of the tool T with respect to the workpiece W around the axis O which is the center of the seal surfaces 204a and 220a to be machined, and is generated by simultaneous two-axis control of the X-axis and the Y-axis, and the rotation motion is the rotation around the rotation axis Os of the spindle 112.

[0031] The spindle rotation angle calculation unit 20 calculates the rotation angle φ of the spindle 112 according to the following formula based on the current revolution angle θ of the tool T received from the tool position calculation unit 16 and the phase difference Δφ received from the phase difference memory unit 18. The rotation angle φ of the spindle 112 calculated by the spindle rotation angle calculation unit 20 is input to the numerical control unit 12 as a position command for the servo motor Ms of the spindle 112. φ = θ - Δφ × N × θ / 360…(1) Here, φ: Rotation angle of the main shaft (degrees) θ: Revolution angle of the tool (degrees) Δφ: Phase difference (degrees) N: Revolution speed of the tool T is as follows.

[0032] In Equation (1), -Δφ means that the phase difference is set so that the rotation motion lags behind the revolution motion. By making the rotation motion lag behind the revolution motion, the machining chips generated during machining are easily discharged.

[0033] Referring to FIGS. 8 and 9 in which the rotation angle of the main shaft 112 is indicated by an arrow, when Δφ = 0°, that is, when there is no phase difference between the revolution motion and the rotation motion (the rotation angle φ of the main shaft 112 is equal to the revolution angle θ of the tool T), when the tool T rotates from the rotation position T0 (θ = 0°) counterclockwise around the axis O to the rotation positions T1 (θ = 90°), T2 (θ = 180°), T3 (θ = 270°) and then returns to the rotation position T0 (θ = 360° = 0°), as shown in FIG. 8, it can be understood that the main shaft 112 returns to the original rotation angle (φ = 0°).

[0034] On the other hand, when a phase difference Δφ is provided between the revolution motion and the rotation motion, when the tool T rotates from the rotation position T0 (θ = 0°) counterclockwise around the axis O to the rotation positions T1 (θ = 90°), T2 (θ = 180°), T3 (θ = 270°) and then returns to the rotation position T0 (θ = 360° = 0°), as shown in FIG. 9, it can be understood that the rotation angle of the tool T is φ = 360° - Δφ. When the tool T makes two revolutions around the axis O, φ = 360° - (2×Δφ). When the tool T revolves N times around the axis O, the rotation angle of the main shaft 112 is φ = 360° - (N×Δφ).

[0035] Next, referring to FIGS. 10 to 12, the effects of the present embodiment will be described. FIGS. 10 to 12 are photographic images of a seal surface obtained by polishing a flat surface such as the side wall 220 with the shaft-mounted brush tool 300. FIG. 10 shows a phase difference Δφ = 23°, FIG. 11 shows Δφ = 0°, and FIG. 12 shows the seal surface when the main shaft 112 is rotated at a high speed of approximately several hundred rpm.

[0036] According to this embodiment, as shown in FIG. 10, the abrasive grains on the tip surface of the brush 304 of the shaft-mounted brush tool 300 or the tip surface of the grinding wheel 314 of the shaft-mounted grinding wheel 310 grind the surface portion 220a of the side wall 220, so that the cutter marks formed thereby are not formed in the leak direction in which air leaks, that is, generally in the radial direction, and a uniform and good sealing surface without unevenness in the concentric circle direction can be obtained.

[0037] On the other hand, when no phase difference is given, that is, when Δφ = 0°, as shown in FIG. 11, cutter marks are not formed in the leak direction, but the unevenness in the concentric circle direction is large, and a good sealing surface with uniform roughness cannot be obtained. Also, when the main shaft 112 is rotated at a high speed of approximately several hundred rpm for polishing, as shown in FIG. 12, a large number of cutter marks are formed in the leak direction, and a good sealing surface cannot be obtained.

[0038] In the above-described embodiment, the phase difference Δφ is set such that when returning to the rotation position T0 (θ = 360° = 0°), that is, when the tool T makes one revolution around the axis, the rotation angle becomes smaller than the rotation angle at the start of the revolution. However, the phase difference Δφ may be set such that the rotation angle becomes larger when the tool T makes one revolution around the axis. That is, in the formula (1), Δφ may be a negative value.

[0039] In the above-described embodiment, the phase difference was Δφ = 23°, but the present invention is not limited to this, and other values of the phase difference, -180° ≤ Δφ ≤ 180°, may be set. FIG. 13 shows the locus of the polishing action point when the revolution motion is performed one round with the phase difference being 180°. In this case, the locus passes through all the way from the inner contact point of the outer edge of the seal area indicated by the dashed line to the inner contact point of the inner edge. Therefore, if the phase difference is increased further, cutter marks in the leakage direction will occur, so the upper limit of the phase difference is ±180°. If the phase difference has a common divisor with 360°, which is the rotation angle of one round of revolution, the cutter marks formed on the polished seal surface will have periodicity (specific parts will be polished more strongly than other parts). Therefore, it is desirable that the phase difference Δφ does not have a common divisor with 360. Also, according to the experiments of the inventors, when a phase difference larger than ±60° is set, cutter marks in a streaky pattern may be formed on the polished seal surface. This is not preferable for the seal surface of a vacuum device where concentric cutter marks are required, and it will be regarded as unacceptable by visual inspection before actual performance. Therefore, it is preferable to set the phase difference as -60° ≤ Δφ ≤ 60°. Δφ = ±23° shown in the above-described embodiment is one of the preferable values. Δφ = ±17°, ±19°, ±31°, ±35°, ±41°, etc. also give preferable results. It is desirable that the number of revolutions of the revolution is performed until the cumulative phase difference exceeds at least 360°. This is to obtain a non-uniform polishing surface by returning the abrasive grains to the polishing start point. For example, in the above-described embodiment where the phase difference Δφ = 23°, 16 revolutions with the cumulative phase difference being 368° are the minimum number of revolutions.

[0040] Here, a particular explanation will be given regarding the phase difference between the rotation and revolution in the present invention. Even if, while the tool makes one revolution, that is, a 360° revolution along the contour shape of the seal surface, the spindle 112 gives the tool T a high-speed rotation, for example, 100 rotations, that is, a 36000° rotation for machining, it can be regarded as machining having a phase difference between the rotation and revolution. However, in this case, as shown in FIG. 12, a large number of cutter marks are generated in the leakage direction, and a good seal surface cannot be obtained. The intention of the present invention is to make the locus of the abrasive grains on the tip surface of the shaft-mounted brush tool 300 or the shaft-mounted grinding wheel 310 spiral by giving a phase difference within a maximum range of ±180° between the rotation and revolution, and it should be noted that this is essentially different from performing the high-speed rotation as described above.

[0041] Furthermore, in the above-described embodiment, the tool T revolves along a circular closed loop, but the present invention is not limited to this, and the tool T may be revolved along a closed loop of other shapes. FIG. 14 shows the locus of the polishing action point when the tool T is revolved along an oval-shaped closed loop formed by combining two parallel line segments of equal length and two semi-circles, FIG. 15 shows the locus of the polishing action point when revolved along an elliptical closed loop, and FIG. 16 shows the locus of the polishing action point when revolved along a substantially rectangular (rounded square) closed loop formed by combining four line segments of the same length and four quarter circles connecting the line segments. Thus, this machining method can be applied to seal surfaces of any shape whose contour shape is a closed loop.

[0042] Furthermore, in the above-described embodiment, a shaft-mounted polishing tool having a diameter equal to the width of the groove 204 is used to polish the bottom surface 204a and the surface portion 220a, but a thinner polishing tool may be used, and polishing with a predetermined width may be performed by changing the revolution radius and performing polishing a plurality of times.

[0043] Also, although not shown, if it is a closed loop composed of a part of a circle and a straight line portion, it is also possible to perform a revolution only in the circular portion. That is, the machining along the above-described circular closed loop may be divided and performed, and they may be connected by a linear motion.

[0044] In FIGS. 14 to 16, since each closed loop has a shape with a center (there are two symmetry axes), the revolution angle θ of the tool T can be determined with the center as the pole. When the closed loop has only one symmetry axis, for example, an oval or oval shape, or a shape without a symmetry axis, the revolution angle θ of the tool T can be defined with the center of gravity of the shape as the pole.

[0045] Furthermore, in the above-described embodiment, the tool T revolves along a circular closed loop with respect to the table 108 by the two linear feed devices of the main shaft 112 in the X-axis and Y-axis directions, but the present invention is not limited to this. By rotating the table 108, the tool T may be revolved along a circular closed loop with respect to the workpiece W. Alternatively, a mechanism for revolving the main shaft for each tool may be provided specially and used. FIG. 17 shows another example of a machine tool to which the present invention is applicable. In FIG. 17, the same reference numerals are assigned to the same components as in FIG. 1, and redundant descriptions will be omitted below.

[0046] In the machine tool 100 shown in FIG. 1, the table 108 was a non-rotating table provided on the Y-slider 110, but the machine tool 150 shown in FIG. 17 includes a rotating table 152 provided on the Y-slider 110. That is, the machine tool 150 is a four-axis processing machine. The rotating table 152 is rotatably provided around a turning axis Oc extending in the vertical direction, and includes a C-axis servo motor Mc for rotationally driving the rotating table 152 inside. The C-axis servo motor Mc can include a rotary encoder.

[0047] FIG. 18 shows the control device 50 of the machine tool 150. The control device 50 has substantially the same configuration as the control device 10 shown in FIG. 2. In FIG. 18, the same reference numerals are assigned to the same components as in FIG. 2, and redundant descriptions will be omitted below.

[0048] The rotation control unit 52 of the control device 50 in Fig. 18 includes a phase difference memory unit 18 and a spindle rotation angle calculation unit 54. In a machine tool 150 equipped with a rotary table 152, since the rotation angle of the rotary table 152 is described in the NC program, the spindle rotation angle calculation unit 54 of the control device 50 receives the rotation angle of the rotary table 152 from the numerical control unit 12 as the revolution angle θ of the tool T, and based on this and the phase difference Δφ received from the phase difference memory unit 18, calculates the rotation angle φ of the spindle 112 according to the above formula (1). The rotation angle φ of the spindle 112 calculated by the spindle rotation angle calculation unit 54 is input to the numerical control unit 12 as a position command for the servo motor Ms of the spindle 112. The numerical control unit 12 controls the servo motors 56 (Mx, My, Mz, Mc, Ms) of the feed devices for the X-axis, Y-axis, and Z-axis, the rotary table 152, and the spindle 112 based on the NC program 22, the digital scales for the X-axis, Y-axis, and Z-axis, and the coordinate values detected by the rotary encoder of the C-axis servo motor Mc.

[0049] In addition, the configuration for imparting a revolution motion to the tool T may alternatively be of a type in which the spindle head performs a feed motion in the three axial directions of X, Y, and Z, or a type in which the table performs a feed motion in the two axial directions of X and Y. Also, a type may be adopted in which a mechanism for the spindle 112 to revolve together with the tool T is specially provided separately from the feed axes of the X, Y, and Z axes.

Explanation of Reference Numerals

[0050] 10 Control device 12 Numerical control unit 14 Rotation control unit 16 Tool position calculation unit 18 Phase difference memory unit 20 Spindle rotation angle calculation unit 100 Machine tool 108 Table 112 Spindle 220a Sealing surface 300 Shaft-mounted brush tool 310 Shaft-mounted grinding wheel

Claims

1. In a method for machining a seal surface for polishing a seal surface of a workpiece placed on a table of a machine tool by a shaft-mounted polishing tool attached to a spindle of the machine tool, while bringing the tip surface of the shaft-mounted polishing tool into contact with the workpiece, the shaft-mounted polishing tool is revolved relatively using one or both of a linear feed shaft and a rotary feed shaft that relatively move the spindle and the table of the machine tool with respect to the workpiece along a closed loop, while the shaft-mounted polishing tool makes one revolution of the revolving motion, when the shaft-mounted polishing tool has a circumferential angle of 360° with respect to the revolving motion, the spindle of the machine tool is rotated in the same direction as the revolving motion with a phase difference of a value that has no common divisor with 360 within ±180°. A method for machining a seal surface characterized by this.

2. The machining method according to Claim 1, wherein the phase difference is a value smaller than ±60°.

3. The machining method according to Claim 1, wherein the seal surface is formed on the bottom surface of a groove for accommodating a seal member and on a surface facing the bottom surface.

4. In a seal surface machining apparatus for polishing a seal surface of a workpiece by a shaft-mounted polishing tool, a spindle to which the shaft-mounted polishing tool is attached, a table to which the workpiece is attached, a feed shaft device having one or both of a linear feed shaft and a rotary feed shaft for relatively moving the spindle with respect to the table, and a control device for controlling the rotation of the spindle and the feed shaft device, wherein the control device while bringing the tip surface of the shaft-mounted polishing tool into contact with the workpiece, the shaft-mounted polishing tool is revolved relatively using one or both of the linear feed shaft and the rotary feed shaft with respect to the workpiece along a closed loop, while the shaft-mounted polishing tool makes one revolution of the revolving motion, when the shaft-mounted polishing tool has a circumferential angle of 360° with respect to the revolving motion, the shaft-mounted polishing tool is rotated in the same direction as the revolving motion with a phase difference of a value that has no common divisor with 360 within ±180°. A machine tool for machining a seal surface characterized by this.

Images