Processing method using an attachment spindle

Abstract

Measure the displacement of the attachment spindle with respect to the spindle that easily and quickly attaches the attachment spindle, easily correct the machining error when machining with the attachment spindle, and machine the workpiece with high precision. 【Solution means】In a machining method in which machining is performed with a tool attached to an attachment spindle, with the attachment spindle attached to the spindle, the position of the rotation axis of the attachment spindle is determined in a first direction orthogonal to the rotation axis of the attachment spindle at a plurality of rotation indexing positions of the spindle, and from the positions of the rotation axes obtained at each of the plurality of rotation indexing positions, the amount of displacement in the first direction of the position of the rotation axis of the attachment spindle with respect to the rotation axis of the spindle, and the amount of displacement in a second direction, which is a direction orthogonal to the rotation axis of the attachment spindle and the first direction, are calculated, and based on this, while correcting to compensate for the amount of displacement in the first direction and the amount of displacement in the second direction, the workpiece is machined with the tool of the attachment spindle.

Description

Technical Field

[0001] The present invention relates to a machining method using an attachment spindle mounted on the spindle of a machine tool.

Background Art

[0002] Patent Document 1 describes a correction method in which a touch probe having a spherical touch sensor is placed stationary on a table, a reference tool is attached to the spindle, the reference tool is moved in the X-axis, Y-axis, and Z-axis directions, and the coordinates when it contacts the touch probe are obtained, and based on this, the correction value of the attachment spindle is obtained.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the correction method of Patent Document 1, since the reference tool is brought into contact with the touch probe, the obtained correction value includes an error caused by the lost motion that the touch probe inevitably has. Also, since the touch probe includes an error depending on the direction in which the measurement object contacts, the correction value obtained by the correction method of Patent Document 1 varies depending on the direction in which the reference tool approaches the touch probe. Furthermore, in the correction method of Patent Document 1, since the reference tool is physically brought into contact with the touch probe, it cannot be measured with a rotating tool.

[0005] The technical problem of the present invention is to solve such problems of the prior art, and it aims to provide a machining method capable of easily and quickly measuring the displacement of the attachment spindle with respect to the spindle for attaching the attachment spindle, easily correcting the machining error when using the attachment spindle, and machining a workpiece with high precision.

Means for Solving the Problem

[0006] In order to achieve the above object, according to the present invention, It is supported by a spindle head so as to be rotatable around a rotation axis, and a tapered hole for mounting a tool holder is formed at the tip portion on a machine tool equipped with a spindle , turn an attachment spindle incorporating a rotary actuator is instead of the tool holder attached to the the tapered hole of spindle, and with the spindle rotated at the origin position around the axis and stopped, , mounted in the tapered hole in a machining method of rotating a tool attached to the attachment spindle by a rotary actuator for machining, a step of attaching a tool holder with a first tool to the the tapered hole of spindle, a step of rotating the tool holder with the spindle to machine a workpiece with the first tool placed on a table, the a step of attaching an attachment spindle with a second tool to the instead of the tool holder spindle, the tapered hole of a step of moving the spindle while the attachment spindle is attached to a plurality of is the rotational position around the rotation axis positions, measurement a step of obtaining the position of the rotation axis of the attachment spindle in a first direction orthogonal to the rotation axis of the attachment spindle at each of the plurality of movement positions using a sensor placed on a table, a step of calculating the displacement amount in the first direction of the rotation axis of the attachment spindle with respect to the rotation axis of the spindle and the displacement amount in a second direction which is a direction orthogonal to the rotation axis of the attachment spindle and the first direction from the positions of the rotation axis of the attachment spindle in the first direction obtained at each of the plurality of measurement positions, measurement and a step of calculating the displacement amount in the first direction and the displacement amount in the second direction of the rotation axis of the attachment spindle obtained at each of the plurality of and based on the angle between the origin position centered on the rotation axis of the spindle and each of the plurality of measurement positions, when the spindle is at the origin position positions, and a step of compensating for the displacement amount in the first direction and the displacement amount in the second direction while correcting, a step of moving and fixing the spindle to the origin position; while correcting to compensate for the displacement amount in the first direction and the displacement amount in the second direction, with the spindle fixed at the origin position,A machining method is provided, which includes a step of machining the workpiece placed on the table with a second tool rotated by a rotary actuator.

Effect of the Invention

[0007] According to the present invention, by obtaining the amount of displacement in the first direction orthogonal to the amount of displacement in the second direction between the rotation axis of the attachment spindle mounted on the spindle of the machine tool and the rotation axis of the spindle of the machine tool using a sensor on the machine tool, it becomes possible to easily and quickly obtain the correction amount of the machining error, and it becomes possible to machine the workpiece with high precision.

Brief Description of the Drawings

[0008]

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Best Mode for Carrying Out the Invention

[0009] FIG. 1 is a schematic side view showing an example of a machine tool to which the invention of the present application 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, and Z-axis).

[0010] 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). The X slider 106 has a block 106a that slides along an X-axis guide rail 108 extending in the X-axis direction.

[0011] 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, as an X coordinate detection device for detecting the position of the X-axis feed device, an X-axis digital scale (not shown) is provided on the column 104. The X coordinate detection device may include a rotary encoder (not shown) for detecting the rotational position of the X-axis servo motor Mx.

[0012] On the front surface of the X slider 106, the spindle head 110 is attached so as to be reciprocally movable in the Z-axis direction which is the vertical direction. The spindle head 110 has a block 110a that slides along a Z-axis guide rail 112 extending in the Z-axis direction. As a Z-axis feed device for reciprocally driving the spindle head 110, 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. A nut (not shown) engaging with the ball screw is attached to the column 104. Further, as a Z coordinate detection device for detecting the position of the Z-axis feed device, the X slider 106 is provided with a Z-axis digital scale (not shown). The Z coordinate detection device may include a rotary encoder (not shown) for detecting the rotational position of the Z-axis servo motor Mz.

[0013] In the spindle head 110, the spindle 114 is rotatably supported by a bearing 116 about a rotation axis Os extending in the vertical direction. The spindle head 110 includes a spindle servo motor Ms for rotationally driving the spindle 114 and a rotary encoder 118 attached to the spindle 114 as a rotational position detection device for detecting the rotational position of the spindle 114 around the rotation axis Os.

[0014] On the front end side (left side in FIG. 1) of the bed 102, a table 120 is disposed so as to be reciprocally movable in the Y-axis direction which is the horizontal front-rear direction perpendicular to the X-axis. The table 120 has a block 120a that slides along a Y-axis guide rail 122 extending in the Y-axis direction. The workpiece W to be machined by the machine tool 100 is fixed to the upper surface of the table 120 facing the spindle 114 using a pallet (not shown) and a jig (not shown).

[0015] As a Y-axis feed device for reciprocally driving the table 120, the bed 102 is provided with a ball screw 124 extending in the Y-axis direction and a Y-axis servo motor My connected to one end of the ball screw 124. The table 120 is attached with a nut 126 engaged with the ball screw 124. Further, as a Y-coordinate detection device for detecting the position of the Y-axis feed device, the bed 102 is provided with a Y-axis digital scale 128. The Y-coordinate detection device may include a rotary encoder (not shown) for detecting the rotational position of the Y-axis servo motor My.

[0016] A rotary cutting tool T (hereinafter simply referred to as tool T), such as an end mill or a drill, as a first tool, can be mounted on the tip of the spindle 114. In FIG. 1, a tapered hole (not shown) conforming to a predetermined standard such as the HSK standard (DIN69893) or ISO7388 is formed at the tip of the spindle 114, and the tool T is mounted on the tip of the spindle 114 via a tool holder 130 conforming to the standard. 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 114.

[0017] The machine tool 100 can be provided with a cleaning air supply device for cleaning the inner peripheral surface of the tapered hole of the spindle 114 or blowing out air from the tool mounted on the spindle 114 to blow out chips and remove the chips. The cleaning air supply device can include an air supply pipeline (not shown) or an air supply passage (not shown) provided in the spindle 114 along the rotation axis Os, and a compressed air supply device (not shown) that supplies compressed air to the air supply pipeline or the air supply passage. The compressed air supply device can include a compressor (not shown) that compresses air, an accumulator (not shown) that stores the compressed air, a pressure regulating valve (not shown) disposed at the outlet of the accumulator, and the like. The compressed air supply device can include an ON / OFF valve (not shown) that communicates / shuts off the accumulator and the air supply pipeline or the air supply passage of the spindle 114. The ON / OFF valve can be, for example, a solenoid valve. The compressed air supply device not only cleans the inner peripheral surface of the tapered hole of the spindle 114 or blows out air from the tool to remove chips, but also serves as an attachment spindle drive source 64 (see FIG. 4) for supplying compressed air as a power source to the attachment spindle 10 described later.

[0018] The machine tool 100 is provided with a control device 200. The control device 200 can be composed of a computer including a CPU (central processing unit), 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 that interconnects these, and related software, and can include an NC device that controls the servo motors Mx, My, Mz of the X-axis, Y-axis, Z-axis and the servo motor Ms of the spindle 114, and a machine control device that controls peripheral devices (not shown) of the machine tool 100. The peripheral devices of the machine tool can include a tool magazine (not shown), an automatic tool changer (not shown), a compressed air supply device, and a machining fluid supply device (not shown).

[0019] In this embodiment, the machine tool 100 can control the rotational angle position of the spindle 114 around the rotation axis Os (Cs-axis control). Specifically, in this embodiment, the spindle 114 can be controlled by both a speed control mode and a position control mode (sometimes referred to as the Cs-axis control mode). That is, the machine tool 100 to which the present invention is applied can perform Cs-axis control in addition to the axis feed control of the X-axis, Y-axis, and Z-axis.

[0020] In the speed control mode, the spindle 114 is controlled based on the speed (rotation speed). In this case, the rotational angle position of the spindle 114 around the rotation axis Os is not controlled. In contrast, in the Cs-axis control mode, the spindle 114 is controlled based on both the rotation speed and the amount of rotation angle from the origin position around the rotation axis Os. Therefore, the rotational angle position of the spindle 114 around the rotation axis Os can be controlled. The origin of the rotation angle can be set at a predetermined position defined with respect to a certain position of the spindle head 110, for example. Furthermore, the origin can also be changed to an arbitrary position deviated from this predetermined position.

[0021] As shown in FIG. 2, an attachment spindle 10 can be attached to the tip of the spindle 114 instead of the tool T. Referring to FIG. 3, the attachment spindle 10 shown as an example has a housing 12. The housing 12 is formed with a tapered shank portion 12a at the proximal end that fits into the tapered hole of the spindle 114. In this embodiment, the housing 12 has a two-face restraint type tool holder shape conforming to the HSK standard (DIN69893). The housing 12 may have the shape of a 7 / 24 taper tool holder as defined by ISO7388. The housing 12 also has a V-groove 12b that engages with an exchange arm (not shown) of the automatic tool changer of the machine tool 100. In addition, in order for the tool holder to receive the supply of compressed air from the air passage of the spindle 114 to the attachment spindle, a separable compressed air supply path from the spindle 114 is provided, such as a coolant pipe for an HSK standard tool holder or a pull stud bolt with a center hole for a 7 / 24 taper tool holder.

[0022] Inside the housing 12, a main shaft 14 is rotatably supported by a bearing 16 around a rotation axis Oa. The rotation axis Oa of the attachment main shaft 10 coincides with the rotation axis Os of the main shaft 114 when the attachment main shaft 10 is attached to the tip of the main shaft 114.

[0023] The attachment main shaft 10 further includes a main shaft driving device for rotationally driving the main shaft 14. In this embodiment, the main shaft driving device includes an air turbine 20 as a rotary actuator disposed in an air chamber 18 of the housing 12. The air turbine 20 is coupled to the main shaft 14 so as to rotate around the rotation axis Oa. The housing 12 has an air supply passage 22 for supplying air to the air chamber 18 and an exhaust passage 24 for exhausting air from the air chamber 18 to the outside. The air supply passage 22 communicates with the air passage of the main shaft 114 when the attachment main shaft 10 is attached to the main shaft 114 of the machine tool 100.

[0024] The housing 12 also has a positioning projection 26. The positioning projection 26 includes a recess 26a extending parallel to the rotation axis Oa, a ball 28 accommodated in the recess 26a so as to be movable in the direction of the rotation axis Oa, and a coil spring 30 as a biasing member disposed in the recess 26a. After the ball 28 is accommodated in the recess 26a, a cap 32 is attached to the opening of the recess 26a. The cap 32 has a shape such that, as shown in FIG. 3, part of the ball 28 can project outside, but the ball 28 cannot be detached from the cap 32 beyond the opening of the cap 32. Thus, the ball 28 is biased with respect to the cap 32 by the coil spring 30 so that part of the ball 28 projects outside from the opening of the cap 32. The ball 28 engages with a positioning engagement portion 132 of the spindle head 110 when the attachment main shaft 10 is attached to the main shaft 114 of the machine tool 100. Thereby, the attachment main shaft 10 is positioned at the origin position around the rotation axis Oa in the Cs-axis control mode.

[0025] The housing 12 further has an opening at the central portion of the end portion on the opposite side of the tapered shank portion 12a, and the main shaft 14 projects through the opening. A tool mounting hole 14a is formed at the front end portion of the main shaft 14, and a tool 34 as a second tool is mounted in the tool mounting hole 14a. In the present embodiment, the tool 34 is fixed to the tool mounting hole 14a by a collet chuck 36. In the present embodiment, the collet chuck 36 is screwed and tightened with a nut 38 to a screw portion formed on the outer peripheral surface of the front end portion of the main shaft 14, and is pushed into the tool mounting hole 14a and grips the tool 34.

[0026] Hereinafter, taking the case where the present invention is applied to a machine tool 100 as an example, the attachment spindle error measurement system and measurement method of the present invention will be described. FIG. 4 is a block diagram showing a preferred embodiment of the attachment spindle error measurement system of the present invention. In FIG. 4, the attachment spindle error measurement system 50 mainly includes a control device 52, an input unit 54, a servo amplifier 56, a servo motor 58, a position detection device 60, a storage device 62, and a tool measurement device 70 as a sensor.

[0027] The control device 52 controls the current output from the servo amplifier to the servo motor 58 according to the tool measurement program input from the input unit 54, and relatively moves the attachment spindle 10 mounted on the main shaft 114 and the tool measurement device 70. The control device 52 can be configured by the control device 200 in the embodiments of FIGS. 1 and 2. That is, it can be configured as a part of the NC device or the machine control device of the machine tool to which the present invention is applied.

[0028] The input unit 54 is an element that inputs a tool measurement program to the control device 52, and can include an input device such as a keyboard (not shown) or a touch panel (not shown) connected to the input / output port of the control device 52 (control device 200 in the embodiments of FIGS. 1 and 2), a server (not shown), a personal computer (not shown), or a CAM (Computer Aided Manufacturing) device connected to the control device 52 via a communication network.

[0029] The servo motor 58 is an element that drives the feed axis of the machine tool on which the attachment spindle 10 is mounted, and in the embodiments of FIGS. 1 and 2, can be composed of the X-axis servo motor Mx, Y-axis servo motor My, Z-axis servo motor Mz, and spindle servo motor Ms of the machine tool 100.

[0030] The position detection device 60 is an element that outputs the coordinates of the feed axis of the machine tool on which the attachment spindle 10 is mounted to the control device 52, and in the embodiments of FIGS. 1 and 2, can be composed of an X-axis digital scale, Y-axis digital scale 128, Z-axis digital scale, and rotary encoder 118. The position detection device 60 may be composed of rotary encoders (not shown) provided on the X-axis servo motor Mx, Y-axis servo motor My, and Z-axis servo motor Mz instead of the X-axis digital scale, Y-axis digital scale 128, and Z-axis digital scale.

[0031] The storage device 62 is an element that stores the measured error of the attachment spindle, and in the embodiments of FIGS. 1 and 2, can be composed of a memory device such as a RAM (Random Access Memory) or ROM (Read Only Memory) provided in the control device 200 and / or a storage device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive).

[0032] The tool measuring device 70 can be configured by a non-contact tool measuring device that outputs a skip signal when detecting a tool to be measured. Referring to FIG. 6, as an example, the tool measuring device 70 shown includes a laser irradiation unit that irradiates a straight and thin laser beam, and a laser light receiving unit that receives the laser beam. When the measuring object crosses the laser beam between the laser irradiation unit and the laser light receiving unit, it is a laser type measuring device that outputs a skip signal. To bring the tool closer to the laser beam, a command to move the tool in any of the X-axis, Y-axis, and Z-axis is given for axis feed. However, when a skip signal is output before the tool moves to the commanded target position, the movement of the axis stops, and the next program (block) is moved to without reaching the commanded target position. A signal that becomes a trigger for stopping the movement and skipping the command although the movement command is not completed is called a skip signal.

[0033] More specifically, the tool measuring device 70 has a frame that arranges the laser irradiation unit and the laser light receiving unit at predetermined positions. The frame has a base portion 72 that is fixed to an appropriate part of a machine tool that mounts the attachment spindle 10. A predetermined part of the machine tool to which the base portion 72 is attached can be a support member that is horizontally relative to the rotation axis of the spindle that mounts the attachment spindle 10, for example, the rotation axis Os of the spindle 114 of the machine tool 100, and is relatively movable with respect to the spindle, such as the table 120 of the machine tool 100.

[0034] The frame of the tool measuring device 70 has a pair of arm portions 74a and 74b that are parallel to the rotation axis of the main shaft when the base portion 72 is fixed to the support member of the machine tool. At the tip portions of the pair of arm portions 74a and 74b, a laser irradiation portion 76a that irradiates the laser beam L and a laser light receiving portion 76b (see FIG. 7) that receives the laser beam L are arranged so as to face each other. In this way, the laser measuring device that constitutes the tool measuring device 70 includes a substantially U-shaped frame composed of the base portion 72 and the pair of arm portions 74a and 74b, and is configured to irradiate the laser beam L between the arm portions 74a and 74b. The laser measuring device further includes a skip signal generation circuit (not shown) that outputs a skip signal when the laser beam L irradiated from the laser irradiation portion 76a toward the laser light receiving portion 76b is blocked.

[0035] The tool measuring device 70 is fixed to the table 120 so as to irradiate the laser beam L in a direction perpendicular to the rotation axis Os of the main shaft 114 of the machine tool 100. The tool measuring device 70 is preferably fixed to the table 120 so as to irradiate the laser beam Lx or Ly parallel to the X-axis or Y-axis. Hereinafter, the tool measuring device 70 is arranged on the table 120 so as to irradiate the laser beam Ly in the Y-axis direction as shown in FIG. 2, and the attachment spindle error measurement method will be described. However, it may be arranged so as to irradiate in the X-axis direction (the direction perpendicular to the paper surface).

[0036] When machining the workpiece W, since a very thin tool is attached to the main shaft 14 of the attachment spindle 10 as the second tool, the attachment spindle 10 is usually used after the workpiece W is machined by a cutting tool T such as an end mill or a drill that is attached to the tip of the main shaft 114 of the machine tool 100 as the first step.

[0037] The attachment spindle 10 has been described as being mounted on the spindle 114 such that its rotation axis Oa coincides with the rotation axis Os of the spindle 114 of the machine tool 100. However, in reality, the rotation axis Oa of the attachment spindle 10 mounted on the spindle 114 does not exactly coincide with the rotation axis Os of the machine tool 100. In the present invention, before machining by the attachment spindle 10 is started, the amount of deviation of the rotation axis Oa of the attachment spindle 10 from the rotation axis Os of the machine tool 100 is measured by the attachment spindle error measurement method described below.

[0038] In FIG. 5, after machining of the workpiece W by the tool T as the first tool, the attachment spindle 10 is mounted on the tip of the spindle 114 in order to machine the workpiece W by the attachment spindle 10 (step S10). This may be performed manually by the operator, but is usually performed by the automatic tool changer of the machine tool 100 according to the machining program input to the control device 52. At the time of automatic tool change, the spindle 114 of the machine tool 100 is indexed to the origin position by Cs-axis control. Further, when the attachment spindle 10 is mounted on the spindle 114, the ball 28 of the attachment spindle 10 engages with the positioning engagement portion 132 of the spindle head 110 of the machine tool 100, and the attachment spindle 10 is positioned at the origin position P0 (see FIG. 8) in the Cs-axis control mode.

[0039] Referring to FIG. 8 here, the position Pr0 of the rotation axis Oa of the spindle 14 of the attachment spindle 10 when the Cs-axis is at the origin position P0 is shown. The amount of positional deviation (deviation) of the rotation axis Oa of the spindle 14 of the attachment spindle 10 from the rotation axis Os of the spindle 114 of the machine tool 100 is expressed by the following formula. δx = X ca(0) -Xs = rcosφ…(1) δy = Y ca(0) -Ys = rsinφ…(2)

[0040] After the attachment spindle 10 is mounted on the spindle 114 of the machine tool 100, the attachment spindle error measurement method is executed at step S12 or below. This can be automatically performed, for example, by writing a command to read the attachment spindle error measurement program into the machining program input to the control device 52. Irrespective of the execution of the machining program, only the attachment spindle error measurement program may be executed.

[0041] First, the spindle 14 of the attachment spindle 10 is rotated at a predetermined rotational speed, for example, the rotational speed during machining (step S12). Preferably, this is continued for a predetermined time to perform a warm-up operation of the attachment spindle 10 (step S14). By the warm-up operation, the rotation of the attachment spindle 10 becomes stable.

[0042] Next, by Cs-axis control, the spindle 114 of the machine tool 100 is moved to the first measurement position Pr1, which is a predetermined rotational position around the rotational axis Os (step S16). In the example of FIG. 8, it is the rotational position of an angle θ1 from the origin position Pr0 around the rotational axis Os. The rotation of the spindle 114 to the first measurement position Pr1 can be performed in the Cs-axis control mode. At this time, the ball 28 of the attachment spindle 10 disengages from the positioning engagement portion 132 of the spindle head 110.

[0043] Next, the tool 34 of the attachment spindle 10 is relatively moved with respect to the table 120 by the spindle 114 of the machine tool 100 so as to cross the laser beam L from the + side and the - side. Based on the coordinates when the tool 34 of the attachment spindle 10 blocks the laser beam L, the moving direction coordinate value of the rotational axis Os is calculated (step S18). This can be executed, for example, as follows when the tool measuring device 70 is fixed to the table 120 such that the laser beam L is irradiated in the Y-axis direction as shown in FIG. 7, by moving the spindle 114 in the X-axis direction.

[0044] In this embodiment, the X-axis direction is the first direction orthogonal to the rotation axis line Oa of the attachment spindle 10, and the Y-axis direction is the second direction orthogonal to the rotation axis line of the attachment spindle and the first direction.

[0045] (1) Control the X-axis, Y-axis, and Z-axis so that the tool 34 of the attachment spindle 10 is arranged at a predetermined first measurement start position P1 that is separated from the laser beam L by a predetermined distance in the -X-axis direction. (2) Control the X-axis, and as shown by the arrow A1, move the spindle 114 from the first measurement start position P1 along the X-axis in the + direction, and approach the tool 34 of the attachment spindle 10 toward the laser beam L. At this time, the tool 34 may be stopped, but it is preferably approached toward the laser beam L while rotating. (3) When the tool 34 of the attachment spindle 10 blocks the laser beam L, a skip signal is output from the skip signal circuit of the tool measuring device 70 to the control device 52. The control device 52 reads the X coordinate value X - (1) from the position detection device 60.

[0046] (4) Next, control the X-axis, Y-axis, and Z-axis so that the tool 34 of the attachment spindle 10 is arranged at a predetermined second measurement start position P2 that is separated from the laser beam L by a predetermined distance in the +X-axis direction. (5) Control the X-axis, and as shown by the arrow A2, move the spindle 114 from the second measurement start position P2 along the X-axis in the - direction, and approach the tool 34 of the attachment spindle 10 toward the laser beam L. At this time, the tool 34 may be stopped, but it is preferably approached toward the laser beam L while rotating. (6) When the tool 34 of the attachment spindle 10 blocks the laser beam L, a skip signal is output from the skip signal circuit of the tool measuring device 70 to the control device 52. The control device 52 reads the X coordinate value X + (1) from the position detection device 60.

[0047] The coordinate value of the moving direction of the rotation axis Oa of the attachment spindle 10 at the first measurement position Pr1 (in this case, the coordinate value of the rotation axis Oa measured by moving the spindle 114 in the X-axis direction), the X coordinate value X ca(1) can be expressed by the following formula (3). X ca(1) =(X - (1) +X + (1) ) / 2 = Xs + rcos(φ + θ1)…(3)

[0048] Next, in the Cs-axis control mode, the spindle 114 of the machine tool 100 is moved to the second measurement position Pr2, which is a predetermined rotation position around the rotation axis Os (step S20). In the example of FIG. 8, the second measurement position Pr2 is a rotation position at an angle θ2 from the origin position Pr0 around the rotation axis Os.

[0049] After moving the spindle 114 to the second measurement position Pr2, the same steps as the above steps (1) to (6) are executed to obtain X - (2) and X + (2) , and based on this, the X coordinate value X ca(2) of the rotation axis Oa of the attachment spindle 10 at the second measurement position is calculated by the following formula (4) (step S22). X ca(2) =(X - (2) +X + (2) ) / 2 = Xs + rcos(φ + θ2)…(4)

[0050] Furthermore, in the Cs-axis control mode, the spindle 114 of the machine tool 100 is moved to the third measurement position Pr3, which is a predetermined rotation position around the rotation axis Os (step S24). In the example of FIG. 8, the third measurement position Pr3 is a rotation position at an angle θ3 from the origin position Pr0 around the rotation axis Os.

[0051] After moving the spindle 114 to the third measurement position Pr3, the same steps as the above steps (1) to (6) are executed to obtain X - (3)and X + (3) Find them, and based on this, find the X coordinate value X of the rotation axis Oa of the attachment spindle 10 at the third measurement position Pr3 ca(3) Calculate it by the following formula (5) (step S26). X ca(3) =(X - (3) +X + (3) ) / 2 = Xs + rcos(φ + θ3)…(5)

[0052] Furthermore, in the Cs axis control mode, move the spindle 114 of the machine tool 100 to the fourth measurement position PR4, which is a predetermined rotation position around the rotation axis Os (step S28). In the example of FIG. 8, the fourth measurement position Pr4 is a rotation position at an angle θ4 from the origin position Pr0 around the rotation axis Os.

[0053] After moving the spindle 114 to the fourth measurement position Pr4, execute the same steps as the above steps (1) to (6) to find X - (4) and X+(4), and based on this, calculate the X coordinate value X of the rotation axis Oa of the attachment spindle 10 at the fourth measurement position Pr4 by the formula (6) (step S30). ca(4) X ca(4) =(X - (4) +X + (4) ) / 2 = Xs + rcos(φ + θ4)…(6)

[0054] Based on the obtained X ca(1) , X ca(2) , X ca(3) , X ca(4) , X ca(1) and formulas (1) to (6), the positional deviation (deviation amount in the first direction) δx in the X-axis direction and the positional deviation (deviation amount in the second direction) δy in the Y-axis direction of the rotation axis Oa of the attachment spindle 10 from the rotation axis Os of the spindle 114 of the machine tool 100 are shown by the following formulas (7) and (8).

[0055]

Equation

Number

[0056] The control device 200 of the machine tool 100 calculates the correction amount of the machining error based on the positional deviations δx and δy in the X-axis direction and the Y-axis direction (step S32). The control device 200 further rotates the spindle 114 of the machine tool 100 to the origin position P0 in the Cs-axis control mode and fixes it at this position (step S34). At this time, the ball 28 of the attachment spindle 10 engages with the positioning engagement portion 132 of the spindle head 110 of the machine tool 100. The workpiece W is machined with the tool 34 as the second tool rotated by the attachment spindle 10 (step S36).

[0057] According to the present embodiment, the displacement amount in the X-axis direction (the first direction) and the displacement amount in the Y-axis direction between the rotation axis line Oa of the spindle 14 of the attachment spindle 10 attached to the spindle 114 of the machine tool 100 and the rotation axis line Os of the spindle 114 of the machine tool 100 are obtained by using the tool measuring device 70 as a sensor placed on the table 120 of the machine tool 100, whereby it is possible to easily and quickly obtain the correction amount of the machining error.

[0058] In addition, in the above method, it has been described that the spindle 114 is moved in the + direction along the X-axis from the first measurement start position P1 and then in the - direction along the X-axis from the second measurement start position P2, but it is not limited to this approach method, and the spindle 114 may be first moved in the - direction along the X-axis from the second measurement start position P2 and then in the + direction along the X-axis from the first measurement start position P1.

[0059] Also, as described above, using one laser beam L irradiated in the Y-axis direction, the spindle 114 of the machine tool 100 is positioned at a plurality of rotation indexing positions in the Cs-axis control mode, and in the above-described embodiment, at four measurement positions Pr1, Pr2, Pr3, and Pr4, and the position X of the rotation axis Oa of the attachment spindle 10 in the X-axis direction as the first direction orthogonal to the rotation axis Oa of the attachment spindle 10 ca(1) , X ca(2) , X ca(3) , X ca(4) , X

[0060] The present invention is not limited to this. As shown in FIGS. 9 to 11, in addition to the laser beam Ly irradiated in the Y-axis direction, a laser beam is also irradiated in the X-axis direction, and the spindle 114 of the machine tool 100 is positioned at two measurement positions in the Cs-axis control mode, and the positional deviation in the first direction (X-axis direction) and the positional deviation in the second direction (Y-axis direction) are obtained, and based on this, the axis deviation of the rotation axis Oa of the attachment spindle 10 in the first and second directions may be calculated.

[0061] Referring to FIG. 11, similar to the above-described step S10, when the attachment spindle 10 is attached to the tip of the spindle 114 of the machine tool 100, the amount of positional deviation (deviation) of the rotation axis Oa of the spindle 14 of the attachment spindle 10 from the rotation axis Os of the spindle 114 of the machine tool 100 is expressed by the following formula. δx = X ca(0) - Xs = rcosφ…(9) δy = Y ca(0) - Ys = rsinφ…(10)

[0062] (7) Next, after performing a warm-up operation in the same manner as in the above steps S12 and S14, the main spindle 114 of the machine tool 100 is moved to a first measurement position Pr1, which is a predetermined rotational position around the rotational axis Os, by Cs-axis control. In the example of FIG. 11, it is a rotational position at an angle θ1 from the origin position Pr0 around the rotational axis Os.

[0063] (8) Next, as shown in FIG. 9, by controlling the X-axis, Y-axis, and Z-axis, the tool 34 of the attachment spindle 10 is arranged at a predetermined first measurement start position P1 that is separated from the laser beam Ly irradiated in the Y-axis direction by a predetermined distance in the -X-axis direction. (9) By controlling the X-axis, as shown by the arrow A1, the main spindle 114 is moved in the + direction along the X-axis from the first measurement start position P1, and the tool 34 of the attachment spindle 10 is approached toward the laser beam Ly. At this time, the tool 34 may be stopped, but it is preferable to approach the laser beam Ly while rotating. (10) When the tool 34 of the attachment spindle 10 blocks the laser beam Ly, a skip signal is output from the skip signal circuit of the tool measuring device 70 to the control device 52. The control device 52 reads the X coordinate value X - (1) from the position detection device 60.

[0064] (11) Next, by controlling the X-axis, Y-axis, and Z-axis, the tool 34 of the attachment spindle 10 is arranged at a predetermined second measurement start position P2 that is separated from the laser beam Ly by a predetermined distance in the +X-axis direction. (12) By controlling the X-axis, as shown by the arrow A2, the main spindle 114 is moved in the - direction along the X-axis from the second measurement start position P2, and the tool 34 of the attachment spindle 10 is approached toward the laser beam Ly. At this time, the tool 34 may be stopped, but it is preferable to approach the laser beam Ly while rotating. (13) When the tool 34 of the attachment spindle 10 blocks the laser beam Ly, a skip signal is output from the skip signal circuit of the tool measuring device 70 to the control device 52. The control device 52 reads the X coordinate value X+ (1) Read from the position detection device 60.

[0065] The X coordinate value X of the moving direction coordinate of the rotation axis Oa of the attachment spindle 10 at the first measurement position Pr1 ca(1) Can be expressed by the following formula (11). X ca(1) =(X - (1) +X + (1) ) / 2 = Xs + rcos(φ + θ1)…(11)

[0066] Next, in the Cs axis control mode, the main spindle 114 of the machine tool 100 is moved to the second measurement position Pr2, which is a predetermined rotation position around the rotation axis Os. In the example of FIG. 11, the second measurement position Pr2 is a rotation position at an angle θ2 from the origin position Pr0 around the rotation axis Os.

[0067] After moving the main spindle 114 to the second measurement position Pr2, the same steps as the above steps (8) to (13) are executed to obtain X - (2) And X + (2) Based on this, the X coordinate value X of the rotation axis Oa of the attachment spindle 10 at the second measurement position is calculated by the following formula (12). ca(2) The following formula (12) is used for the calculation. X ca(2) =(X - (2) +X + (2) ) / 2 = Xs + rcos(φ + θ2)…(12)

[0068] (14) Next, by Cs axis control, the main spindle 114 of the machine tool 100 is moved again to the first measurement position Pr1, which is a predetermined rotation position around the rotation axis Os. (15) Next, as shown in FIG. 10, the X axis, Y axis, and Z axis are controlled so that the tool 34 of the attachment spindle 10 is arranged at a predetermined third measurement start position P3 that is separated from the laser beam Lx irradiated in the X axis direction by a predetermined distance in the -Y axis direction. (16) Control the Y-axis and move the spindle 114 in the + direction along the Y-axis from the third measurement start position P3 as indicated by arrow B1, and approach the tool 34 of the attachment spindle 10 toward the laser beam Lx. At this time, the tool 34 may be stopped, but it is preferable to approach the laser beam Lx while rotating the tool 34. (17) When the tool 34 of the attachment spindle 10 blocks the laser beam Lx, a skip signal is output from the skip signal circuit of the tool measuring device 70 to the control device 52. The control device 52 reads the X coordinate value Y - (1) from the position detection device 60.

[0069] (18) Next, control the X-axis, Y-axis, and Z-axis to place the tool 34 of the attachment spindle 10 at a predetermined fourth measurement start position P4 that is separated from the laser beam Lx by a predetermined distance in the +Y-axis direction. (19) Control the Y-axis and move the spindle 114 in the - direction along the Y-axis from the fourth measurement start position P4 as indicated by arrow B2, and approach the tool 34 of the attachment spindle 10 toward the laser beam Lx. At this time, the tool 34 may be stopped, but it is preferable to approach the laser beam Lx while rotating the tool 34. (20) When the tool 34 of the attachment spindle 10 blocks the laser beam Lx, a skip signal is output from the skip signal circuit of the tool measuring device 70 to the control device 52. The control device 52 reads the Y coordinate value Y + (1) from the position detection device 60.

[0070] The coordinate value of the moving direction of the rotation axis Oa of the attachment spindle 10 at the first measurement position Pr1 (the coordinate value of the rotation axis Oa measured by moving the spindle 114 in the Y-axis direction) as the Y coordinate value Y ca(1) can be expressed by the following formula (13). Y ca(1) = (Y - (1) + Y + (1) ) / 2 = Ys + rsin(φ + θ1)…(13)

[0071] Next, in the Cs axis control mode, the spindle 114 of the machine tool 100 is moved to a second measurement position Pr2, which is a predetermined rotational position around the rotational axis Os.

[0072] After moving the spindle 114 to the second measurement position Pr2, the same steps as the above steps (15) to (20) are executed to obtain Y - (2) and Y + (2) and based on this, the moving direction coordinate value of the rotational axis Oa of the attachment spindle 10 at the second measurement position (the coordinate value of the rotational axis Oa measured by moving the spindle 114 in the Y-axis direction) Y coordinate value Y ca(2) is calculated by the following formula (12). Y ca(2) =(Y - (2) +Y + (2) ) / 2 = Ys + rsin(φ + θ2)…(14)

[0073] The obtained X ca(1) , X ca(2) , Y ca(1) , Y ca(2) Based on and the formulas (9) to (14), the positional deviation in the X-axis direction (the deviation amount in the first direction) δx and the positional deviation in the Y-axis direction (the deviation amount in the second direction) δy of the rotational axis Oa of the attachment spindle 10 from the rotational axis Os of the spindle 114 of the machine tool 100 are shown by the following formulas (15) and (16).

[0074]

Equation

Equation

Explanation of Symbols

[0075] 10 Attachment spindle 12 Housing 12a Taper shank portion 12b V-groove 14 Spindle 14a Tool mounting hole 15 Process 16 Bearing 18 Air chamber 20 Air turbine 22 Air supply passage 24 Exhaust passage 26 Projection 26a Recess 28 Ball 32 Cap 34 Tool 36 Collet chuck 38 Jam nut 50 Attachment spindle error measurement system 52 Control device 54 Input section 56 Servo amplifier 58 Servo motor 60 Position detection device 62 Memory device 70 Tool measurement device 72 Base portion 74a Arm portion 74b Arm portion 76a Laser irradiation section 76b Laser light receiving section 100 Machine tool 102 Bed 104 Column 106 X slider 106a Block 108 X-axis guide rail 110 Spindle head 110a Block 112 Z-axis guide rail 114 Spindle 116 Bearing 118 Rotary encoder 120 Table 120a Block 122 Y-axis guide rail 126 Nut 128 Y-axis digital scale 130 Tool holder 132 Engaging portion 200 Control device

Claims

1. A machining method for a machine tool equipped with a spindle that is supported by a spindle head so as to be rotatable about its axis of rotation and has a tapered hole at its tip for mounting a tool holder, comprising the steps of: mounting an attachment spindle having a built-in rotary actuator in the tapered hole of the spindle in place of a tool holder; and rotating a tool mounted on the attachment spindle mounted in the tapered hole with the rotary actuator while the spindle is stopped at an origin position about the axis of rotation, A step of mounting a tool holder having a first tool attached thereto in a tapered hole of a spindle; A step of rotating the tool holder by a spindle and machining a workpiece placed on a table with a first tool; a step of mounting an attachment spindle having a second tool mounted thereon in a tapered hole of the spindle in place of the tool holder; a step of moving the attachment spindle to a plurality of measurement positions, which are rotation positions around a rotation axis, while the attachment spindle is attached; determining a position of a rotation axis of the attachment spindle in a first direction perpendicular to the rotation axis of the attachment spindle using a sensor mounted on a table at each of a plurality of measurement positions; calculating an amount of deviation in a first direction of the position of the rotation axis of the attachment spindle relative to the rotation axis of the spindle when the spindle is at the origin position, and an amount of deviation in a second direction that is perpendicular to the rotation axis of the attachment spindle and the first direction, based on a position in a first direction of the rotation axis of the attachment spindle obtained at each of the plurality of measurement positions and an angle between an origin position centered on the rotation axis of the spindle and each of the plurality of measurement positions; A step of moving and fixing the spindle to an origin position; and machining the workpiece placed on a table with a second tool rotated by a rotary actuator with the spindle fixed at an origin position while compensating for the deviation in the first direction and the deviation in the second direction.

2. 2. The machining method according to claim 1, wherein the step of determining the position of the rotation axis of the attachment spindle determines the position of the rotation axis of the attachment spindle while rotating a rotary actuator.

3. 2. The processing method according to claim 1, wherein the sensor includes a laser emitting section that emits a laser beam in a linear manner and a laser receiving section that receives the laser beam, and outputs a skip signal when the laser beam is interrupted.

4. 4. The machining method according to claim 3, further comprising: positioning the sensor so that the laser beam is irradiated in an X-axis or Y-axis direction of the machine tool; and causing a spindle of the machine tool to approach the laser beam from both directions along the Y-axis or the X-axis so that a second tool attached to the attachment spindle crosses the laser beam.

Images