Working machinery

Abstract

To provide a machine tool which can correct a center hole without lowering a workpiece from the machine tool.SOLUTION: A machine tool 1 includes: a center member 20 which is rotatable integrally with a workpiece W; a drive mechanism 30 which generates rotary driving force; a rotation suppression mechanism 40 which suppresses rotation of one of the workpiece W and the center member 20; a machining control section 3a which machines the workpiece W by integrating and rotating the workpiece W and the center member 20; and a center hole correction control section 3b which corrects center holes W1, W2 by fitting the center member 20 and the center holes W1, W2 into which the center member 20 is fitted by relatively rotating the workpiece W and the center member 20 by rotating the other of the workpiece W and the center member 20 by rotary driving force in a state that rotation of the one of the workpiece W and the center member 20 is suppressed by the rotation suppression mechanism 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a machine tool. [Background technology]

[0002] Conventionally, some machine tools, such as cylindrical grinders and lathes, have a configuration in which a workpiece is supported in the axial direction by a center member, as shown in Patent Document 1. In this configuration, the center member is configured so that the workpiece is fitted into a center hole at the end. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-180934 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the center hole forming accuracy is low in the configuration disclosed in Patent Document 1, the contact state (contact) between the center member and the workpiece deteriorates, the workpiece cannot be properly supported, and the machining accuracy of the workpiece decreases. In such cases, the center hole needs to be corrected. Furthermore, if the center member rotates integrally with the workpiece, the center hole cannot be corrected on the machine, so the workpiece must be removed from the machine tool and the center hole corrected using a center hole correction machine. As a result, correcting the center hole is time-consuming, which reduces work efficiency and makes it difficult to automate center hole correction.

[0005] SUMMARY OF THE INVENTION The present invention provides a machine tool that allows for the correction of a center hole without removing the workpiece from the machine tool. [Means for solving the problem]

[0006] One aspect of the present invention is a center member that is fitted into a center hole provided at an end of a workpiece to support the workpiece in the axial direction and rotate integrally with the workpiece; a drive mechanism that generates a rotational drive force; a rotation suppression mechanism that suppresses rotation of one of the workpiece and the center member; a machining control unit that, when machining the workpiece, rotates the workpiece and the center member as a unit using the rotational drive force to machine the workpiece; and a center hole correction control unit that, during center hole correction to correct the center hole, suppresses rotation of one of the workpiece and the center member with the rotation suppression mechanism, and rotates the other of the workpiece and the center member with the rotational driving force, thereby rotating the workpiece and the center member relative to each other and grinding the center member and the center hole to correct the center hole. [Effects of the Invention]

[0007] According to the above aspect, the center hole correction control unit rotates the other of the workpiece and the center member using the rotation suppression mechanism while suppressing rotation of either the workpiece or the center member using the rotation drive force, thereby rotating the workpiece and the center member relative to each other and grinding the center member and the center hole to correct the center hole. Therefore, the center hole can be corrected and alignment can be performed to improve the contact between the center member and the center hole without removing the workpiece from the machine tool. As a result, the work efficiency of center hole correction can be improved and center hole correction can be easily automated. Furthermore, since the center hole is corrected using the center member that supports the workpiece when machining the workpiece, center hole correction can be performed with higher accuracy.

[0008] As described above, according to the above aspect, it is possible to provide a machine tool that is capable of correcting a center hole without removing the workpiece from the machine tool. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a conceptual diagram showing the configuration of a machine tool according to a first embodiment. [Figure 2] FIG. 3 is an enlarged view of the vicinity of the center member in the first embodiment. [Figure 3] (a) Cross-section along line IIIa-IIIa in Figure 2, (b) Cross-section along line IIIb-IIIb, and (c) Cross-section along line IIIc-IIIc in Figure 2 [Figure 4] FIG. 4 is a flow chart of center hole correction control in the first embodiment. [Figure 5] FIG. 3 is a cross-sectional view taken along line IIIb-IIIb in the second embodiment. [Figure 6] FIG. 11 is a cross-sectional view corresponding to the position of line IIIb-IIIb in the third embodiment. [Figure 7] 10A is a cross-sectional view taken along line IIIb-IIIb in a first state, and FIG. 10B is a cross-sectional view taken along line IIIb-IIIb in a second state in a fourth embodiment. [Figure 8] FIG. 11 is a conceptual diagram showing the configuration of a machine tool in a fifth embodiment. [Figure 9] FIG. 4 is a flow chart of a control process for determining whether or not a center hole needs to be corrected in the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Embodiment 1) 1. Configuration of machine tool 1 A machine tool 1 in the present embodiment 1 will be described with reference to Fig. 1. The machine tool 1 includes a grinding machine 2 as a processing device, and a processing section 3.

[0011] The grinding machine 2 rotates the workpiece W about the center line C, rotates the grinding wheel 16 as a tool that is a rotating body, and moves the grinding wheel 16 relatively close to the workpiece W in a direction intersecting the axis of the workpiece W, thereby grinding the outer or inner peripheral surface of the workpiece W. The grinding machine 2 can be a table traverse type grinding machine, a wheelhead traverse type grinding machine, or the like. The grinding machine 2 can also be a cylindrical grinding machine, a cam grinding machine, or the like.

[0012] In this embodiment, as shown in Fig. 1, the workpiece W is, for example, a member formed in a shaft shape, and the outer circumferential surface of the workpiece W is the part to be machined. However, the shape of the workpiece W is not limited to a shaft shape, and it can be any shape, such as a cylindrical shape having an inner circumferential surface. When the workpiece W is cylindrical, the inner circumferential surface of the workpiece W can be the part to be machined.

[0013] In this embodiment, the workpiece W is generally rod-shaped and is supported by a center member 20 (described later) via center holes W1, W2 formed at both ends. The center holes W1, W2 have a conical concave shape that conforms to the shape of the center member 20. However, if the forming accuracy of the center holes W1, W2 is low or if the center holes W1, W2 are unintentionally deformed during machining of the workpiece W, the shapes of the center holes W1, W2 may not accurately conform to the shape of the center member 20. In such cases, center hole correction (described later) is required. Note that the workpiece W shown in FIG. 1 is just an example, and the grinding machine 2 can grind workpieces having various shapes.

[0014] The processing unit 3 includes a processing control unit 3a and a center hole correction control unit 3b. The processing control unit 3a controls the processing of the workpiece W. The center hole correction control unit 3b controls the center hole correction, which will be described later. The processing unit 3 can be configured with a computer, and the processing control of the workpiece W and the center hole correction control can be computer-controlled.

[0015] 2. Grinding machine 2 configuration The configuration of the grinding machine 2 will be described with reference to Fig. 1. In this embodiment 1, a wheelhead traverse type cylindrical grinding machine is taken as an example of the grinding machine 2. The grinding machine 2 mainly includes a bed 11, a headstock 12, a tailstock 13, a traverse base 14, a wheelhead 15, a grinding wheel 16, a center member 20, a drive mechanism 30, and a rotation suppression mechanism 40.

[0016] Bed 11 is fixed on an installation surface. Headstock 12 is provided on the upper surface of bed 11, on the near side in the X-axis direction (lower side in FIG. 1) and on one end side in the Z-axis direction (left side in FIG. 1). Tailstock 13 is provided on the upper surface of bed 11, in a position facing headstock 12 in the Z-axis direction, i.e., on the near side in the X-axis direction (lower side in FIG. 1) and on the other end side in the Z-axis direction (right side in FIG. 1).

[0017] 2-1. Center member 20 As shown in Fig. 1, the center member 20 includes a spindle-side center member 21 and a tailstock-side center member 22. The spindle-side center member 21 is mounted on the headstock 12, and the tailstock-side center member 22 is mounted on the tailstock 13. As shown in Fig. 2, the spindle-side center member 21 is conical, with its tip fitted into a center hole W1 formed in one end of the workpiece W. The tailstock-side center member 22 is also conical, with its tip fitted into a center hole W2 formed in the other end of the workpiece W.

[0018] The tailstock 13 is provided with a spring (not shown), which urges the tailstock-side center member 22 toward the workpiece W. As a result, the workpiece W is supported in the axial direction by the spindle-side center member 21 and the tailstock-side center member 22 that constitute the center member 20.

[0019] Both the spindle-side center member 21 and the tailstock-side center member 22 are made of a material that is harder than the workpiece W. Therefore, even when the spindle-side center member 21 and the tailstock-side center member 22 are rubbed against the center holes W1 and W2 of the workpiece W during center hole adjustment, which will be described later, the shapes of the spindle-side center member 21 and the tailstock-side center member 22 do not change, and the shapes of the center holes W1 and W2 of the workpiece W are smoothed to match the shapes of the spindle-side center member 21 and the tailstock-side center member 22.

[0020] 2-2. Drive mechanism 30 As shown in Fig. 1, a drive mechanism 30 is connected to the headstock 12. The drive mechanism 30 includes a motor 31, a drive fitting 32, and a drive pin 33. The motor 31 functions as a drive force generating unit that generates a rotational drive force. In the first embodiment, the drive fitting 32 is annular and has a protrusion that protrudes outward as shown in Fig. 3(a), and is attached to the spindle side end of the workpiece W so that the spindle side end of the workpiece W fits into the annular portion of the drive fitting 32 as shown in Fig. 2(a).

[0021] The drive pin 33 is configured to rotate integrally with the spindle-side center member 21 in the first direction R1 as shown in FIG. 3(a) by the rotational driving force of the motor 31. As shown in FIGS. 2(a) and 2(c), the drive pin 33 is configured to be able to advance and retreat toward the drive fitting 32. When the drive pin 33 advances toward the drive fitting 32 as shown in FIG. 2(a), the drive pin 33 engages with the drive fitting 32, establishing an engaged state in which the rotational driving force of the motor 31 is transmitted to the workpiece W. On the other hand, when the drive pin 33 retreats from the drive fitting 32 as shown in FIG. 2(c), the drive pin 33 is disengaged from the drive fitting 32, establishing a disengaged state in which the rotational driving force of the motor 31 is not transmitted to the workpiece W. In this way, the drive pin 33 functions as a rotational driving force transmission unit that can be switched between an engaged state and a disengaged state with respect to the drive fitting 32.

[0022] 2-3.Rotation suppression mechanism 40 As shown in Fig. 1, rotation suppressing mechanism 40 includes a spindle-side rotation suppressing mechanism 41 and a tailstock-side rotation suppressing mechanism 42. As shown in Figs. 3(a) and 3(c), spindle-side rotation suppressing mechanism 41 is fixed to a position below drive fitting 32 on the upper surface of bed 11. As a result, the rotational drive force of motor 31 is not transmitted to spindle-side rotation suppressing mechanism 41, and spindle-side rotation suppressing mechanism 41 remains stationary on bed 11.

[0023] As shown in Figures 3(a) and 3(c), the spindle-side rotation suppression mechanism 41 has a drive pin 41a that can advance and retreat toward the drive fitting 32. As shown in Figure 3(a), when the drive pin 41a is retracted and away from the drive fitting 32, the drive pin 41a is not engaged with the drive fitting 32, and a rotation-permitting state is established in which rotation of the drive fitting 32 in the first direction R1 is not suppressed. On the other hand, as shown in Figure 3(c), when the drive pin 41a advances toward the drive fitting 32, it engages with the drive fitting 32, and a rotation-suppressing state is established in which rotation of the drive fitting 32 in the first direction R1 is suppressed.

[0024] The tailstock-side rotation suppression mechanism 42 is fixed to a position below the tailstock-side center member 22 on the upper surface of the bed 11. As a result, the rotational driving force of the motor 31 is not transmitted, and the tailstock-side rotation suppression mechanism 42 remains stationary on the bed 11. As shown in FIGS. 2(a) and 2(c), the tailstock-side rotation suppression mechanism 42 has a drive pin 42a that can advance and retreat toward the tailstock-side center member 22. When the drive pin 42a is retracted to a position away from the tailstock side center member 22 as shown in Figure 2(a), the drive pin 42a is not engaged with the tailstock side center member 22, and a rotation-permitting state is established in which the tailstock side center member 22 is allowed to rotate.When the drive pin 42a advances toward the tailstock side center member 22 as shown in Figures 2(b) and 3(b), the drive pin 42a enters the groove 22a formed on the outer periphery of the tailstock side center member 22 and engages with the tailstock side center member 22, and a rotation-suppressing state is established in which the rotation of the tailstock side center member 22 is suppressed.

[0025] 2-4.Other configurations The traverse base 14 shown in FIG. 1 is provided on the upper surface of the bed 11 so as to be movable in the Z-axis direction. The traverse base 14 is moved by driving a motor 14a provided on the bed 11. The grinding wheel head 15 is provided on the upper surface of the traverse base 14 so as to be movable in the X-axis direction. The grinding wheel head 15 is moved by driving a motor 15a provided on the traverse base 14. The grinding wheel 16 is rotatably supported on the grinding wheel head 15. The grinding wheel 16 is rotated by driving a motor 16a provided on the grinding wheel head 15. The grinding wheel 16 is composed of a plurality of abrasive grains fixed with a bond material.

[0026] 3. Machining of workpiece W The machining control unit 3a controls the machining of the workpiece W. The machining control unit 3a grinds the workpiece W by controlling the driving of the grinding wheel 16 and the like in the grinding machine 2 based on an NC program generated based on operation command data including various conditions such as the shape of the workpiece W, grinding conditions, and the shape of the grinding wheel 16.

[0027] 2(a) and 3(a), during machining, the drive mechanism 30 is in an engaged state in which the drive pin 33 is engaged with the drive fitting 32, the spindle-side rotation suppression mechanism 41 in the rotation suppression mechanism 40 has the drive pin 41a not engaged with the drive fitting 32, and the tailstock-side rotation suppression mechanism 42 has the drive pin 42a not engaged with the tailstock-side center member 22, all of which are in a rotation-permitted state. Then, as the drive pin 33 rotates in the first direction R1 due to the rotational driving force of the motor 31, the workpiece W rotates in the first direction R1 via the drive fitting 32.

[0028] 4. Correction of center holes W1 and W2 Next, the correction of the center holes W1 and W2 by the center hole correction control unit 3b shown in Fig. 1 will be described using the control flow of Fig. 4. First, in step S1, the center hole correction control unit 3b determines whether the timing for center hole correction has arrived. In this embodiment 1, the timing for center hole correction is, for example, the timing when it is determined that the machining accuracy of the previously machined workpiece W is low and it is determined that correction of the center holes W1 and W2 is necessary. However, the timing for center hole correction is not limited to this. If the required machining accuracy of the workpiece W is high, the timing for center hole correction may be immediately before the start of machining of the workpiece W, so that machining of the workpiece W can be started with the shape accuracy of the center holes W1 and W2 reliably high.

[0029] If it is determined in step S1 that the timing for correcting the center hole has not arrived, the process proceeds to No in step S1 and executes step S1 again. On the other hand, if it is determined in step S1 that the timing for correcting the center hole has arrived, the process proceeds to Yes in step S1.

[0030] Then, in step S2, the center hole correction control unit 3b engages the drive pin 42a of the tailstock-side rotation suppression mechanism 42 with the tailstock-side center member 22 to place the tailstock-side center member 22 in a rotation suppressed state.

[0031] Next, in step S3, the center hole correction control unit 3b engages the drive pin 33 of the drive mechanism 30 with the drive fitting 32, and drives the motor 31 to rotate the workpiece W. This causes the workpiece W and the tailstock-side center member 22 to rotate relative to each other.

[0032] Then, in step S4, the relative rotation causes the tailstock-side center member 22 to rub against the tailstock-side center hole W2 of the workpiece W, thereby leveling the shape of the tailstock-side center hole W2 to match the shape of the tailstock-side center member 22 and correcting the tailstock-side center hole W2. The duration of the correction of the tailstock-side center hole W2 is not particularly limited and can be, for example, a preset time, and the correction of the tailstock-side center hole W2 may be terminated when the preset time has elapsed.

[0033] After the tailstock side center hole W2 has been corrected, in step S5, the center hole correction control unit 3b stops the drive of the motor 31 to stop the rotation of the workpiece W, and disengages the drive pin 42a in the tailstock side rotation suppression mechanism 42 from the tailstock side center member 22 to allow the tailstock side center member 22 to rotate.

[0034] Then, in step S6, the center hole correction control unit 3b engages the drive pin 41a of the spindle-side rotation suppression mechanism 41 with the drive fitting 32, thereby suppressing the rotation of the workpiece W via the drive fitting 32.

[0035] Thereafter, in step S7, the center hole correction control unit 3b disengages the drive pin 33 and the drive fitting 32 in the drive mechanism 30. Next, in step S8, the center hole correction control unit 3b drives the motor 31 to rotate the spindle-side center member 21 while the workpiece W is stationary. This causes the workpiece W and the spindle-side center member 21 to rotate relative to each other.

[0036] Then, in step S9, the spindle side center member 21 is rubbed against the spindle side center hole W1, and the shape of the spindle side center hole W1 is leveled to match the shape of the spindle side center member 21, thereby correcting the spindle side center hole W1. The duration of the correction of the spindle side center hole W1 is not particularly limited and can be, for example, a preset time, and the correction of the spindle side center hole W1 may be terminated when the preset time has elapsed.

[0037] After the correction of the spindle-side center hole W1 is completed, in step S10, the center hole correction control unit 3b stops the drive of the motor 31 to stop the rotation of the spindle-side center member 21, and disengages the drive pin 41a of the spindle-side rotation suppression mechanism 41 from the drive fitting 32, thereby allowing the workpiece W to rotate.

[0038] Thereafter, in step S11, the center hole correction control section 3b engages the drive pin 33 in the drive mechanism 30 with the drive fitting 32, thereby completing the center hole correction.

[0039] 5. Effects According to the machine tool 1 of the first embodiment, the center hole correction control unit 3b rotates the other of the workpiece W and the center member 20 using the rotation suppression mechanism 40 while suppressing rotation of either the workpiece W or the center member 20 using the rotation drive force, thereby rotating the workpiece W and the center member 20 relative to each other and grinding the center member 20 against the center holes W1, W2 to correct the center holes W1, W2. Therefore, the center holes W1, W2 can be corrected and alignment can be performed to improve the contact between the center member and the center holes W1, W2 without removing the workpiece W from the machine tool 1. As a result, the work efficiency of correcting the center holes W1, W2 can be improved, and the correction of the center holes W1, W2 can be easily automated. Furthermore, the center holes W1, W2 are corrected using the center member 20 that supports the workpiece W during machining, so the center holes W1, W2 can be corrected with higher accuracy.

[0040] In the first embodiment, the center member 20 is provided on the headstock 12 having the drive mechanism 30 and includes a spindle-side center member 21 that fits into a spindle-side center hole W1 provided at an end of the workpiece W as a center hole, and the rotation suppression mechanism 40 includes a spindle-side rotation suppression mechanism 41 that suppresses rotation of the workpiece W. During machining of the workpiece W, the machining control unit 3a uses the rotational drive force of the motor 31 to rotate the workpiece W and the spindle-side center member 21 as a unit to machine the workpiece W. During center hole correction, the center hole correction control unit 3b rotates the spindle-side center member 21 using the rotational drive force of the motor 31 while suppressing rotation of the workpiece W with the spindle-side rotation suppression mechanism 41, thereby rotating the workpiece W and the spindle-side center member 21 relative to each other to correct the spindle-side center hole W1. This allows the spindle-side center hole W1 to be corrected without removing the workpiece W from the machine tool 1.

[0041] Furthermore, in the first embodiment, the drive mechanism 30 includes a drive force generating unit (motor 31) that generates a rotational drive force, a drive fitting 32 connected to the workpiece W, and a rotational drive force transmitting unit (drive pin 33) that can switch between an engaged state in which the drive fitting 32 is engaged to transmit the rotational drive force to the workpiece W, and a disengaged state in which the drive fitting 32 is disengaged to not transmit the rotational drive force of the motor 31 to the workpiece W. During center hole correction, the center hole correction control unit 3b disengages the drive pin 33 and drive fitting 32 and rotates the spindle-side center member 21 using the rotational drive force of the motor 31 while suppressing rotation of the workpiece W with the rotation suppression mechanism 40, thereby rotating the workpiece W and the spindle-side center member 21 relative to each other to correct the spindle-side center hole W1. This allows the spindle side center hole W1 to be corrected by utilizing the rotational driving force of the driving force generating unit (motor 31), which is the power source during processing. Therefore, no separate power source is required to correct the spindle side center hole W1, and the configuration of the machine tool 1 does not become complicated.

[0042] In the first embodiment, the center member 20 is provided on the tailstock 13, which presses the workpiece W in one axial direction, and includes a tailstock-side center member 22 that fits into a tailstock-side center hole W2 provided at an end of the workpiece W as a center hole, and the rotation suppression mechanism 40 includes a tailstock-side rotation suppression mechanism 42 that suppresses rotation of the tailstock-side center member 22. During machining of the workpiece W, the machining control unit 3a uses the rotational drive force of the motor 31 to rotate the workpiece W and the tailstock-side center member 22 as a unit to machine the workpiece W. During center hole correction, the center hole correction control unit 3b rotates the workpiece W using the rotational drive force of the motor 31 while suppressing rotation of the tailstock-side center member 22 using the tailstock-side rotation suppression mechanism 42, thereby rotating the workpiece W and the tailstock-side center member 22 relative to each other to correct the tailstock-side center hole W2. This allows the tailstock-side center hole W2 to be corrected without removing the workpiece W from the machine tool 1.

[0043] In the first embodiment, the drive mechanism 30 includes a drive force generating unit (motor 31) that generates a rotational drive force, a drive fitting 32 connected to the workpiece W, and a power transmission unit (drive pin 33) that can switch between an engaged state in which the drive fitting 32 is engaged to transmit the rotational drive force to the workpiece W, and a disengaged state in which the drive fitting 32 is disengaged to not transmit the rotational drive force to the workpiece W. During center hole correction, the center hole correction control unit 3b rotates the workpiece W using the rotational drive force of the motor 31 by engaging the drive pin 33 and the drive fitting 32 while suppressing rotation of the tailstock-side center member 22 with the tailstock-side rotation suppressing mechanism 42, thereby rotating the workpiece W and the tailstock-side center member 22 relative to each other, thereby correcting the tailstock-side center hole W2. This allows the spindle side center hole W1 to be corrected by utilizing the rotational driving force of the driving force generating unit (motor 31), which is the power source during processing. Therefore, no separate power source is required to correct the spindle side center hole W1, and the configuration of the machine tool 1 does not become complicated.

[0044] In this embodiment 1, the machine tool 1 is configured such that both the spindle-side center member 21 and the tailstock-side center member 22 rotate integrally with the workpiece W during machining, but this is not limiting, and a configuration may be adopted in which only one of the spindle-side center member 21 and the tailstock-side center member 22 rotates integrally with the workpiece W. In this case, the configuration of this embodiment 1 described above can be applied to a center hole into which a center member that rotates integrally with the workpiece W is fitted, to correct that center hole. In this case, for a center member that does not rotate integrally with the workpiece W, the workpiece W and the center member can be rotated relatively by rotating the workpiece W in the same manner as during machining, to correct the center hole into which a center member that does not rotate integrally with the workpiece W is fitted.

[0045] The driving fitting 32 may be configured as a chuck that grips the spindle-side end of the workpiece W. In this case, the spindle-side center member 21 and the spindle-side center hole W1 are not provided, and therefore there is no need to consider the correction of the spindle-side center hole.

[0046] In the first embodiment, the tailstock-side rotation suppression mechanism 42 is fixed to the upper surface of the bed 11, but this is not limiting, and the tailstock-side rotation suppression mechanism 42 may be provided inside the tailstock 13. For example, the tailstock-side rotation suppression mechanism 42 may be provided in the housing of the tailstock 13 so as to be able to advance and retreat, and configured to be switchable between a state in which it is engaged with the tailstock-side center member 22 and a state in which the engagement is released.

[0047] Furthermore, in the first embodiment, the spindle-side rotation suppressing mechanism 41 suppresses the rotation of the workpiece W via the drive fitting 32, but this is not limiting, and the spindle-side rotation suppressing mechanism 41 may directly engage with the workpiece W to suppress the rotation of the workpiece W. In this case, it is preferable that the portion of the workpiece W that comes into direct contact with the spindle-side rotation suppressing mechanism 41 is a portion other than the portion to be machined. Furthermore, if the machine tool 1 has a rest device on the opposite side from the grinding wheel 16 that prevents the workpiece W from being pushed away by the grinding wheel 16, the rest device may be pressed against the workpiece W to suppress the rotation of the workpiece W, and the rest device may constitute the spindle-side rotation suppressing mechanism 41.

[0048] In this embodiment 1, the drive mechanism 30 is provided on the headstock 12, but this is not limited to this, and the drive mechanism 30 may be provided on both the headstock 12 and the tailstock 13, and the two drive mechanisms 30 may be used in synchronization.

[0049] (Embodiment 2) In the above-described first embodiment, the motor 31 generates only a rotational driving force in the first direction R1, and the tailstock-side rotation suppression mechanism 42 is equipped with a drive pin 42a that can move back and forth. However, in the second embodiment, instead, the motor 31 is configured to switch between generating a rotational driving force in the first direction R1 and a rotational driving force in the second direction R2, and as shown in FIG. 5, the tailstock-side rotation suppression mechanism 42 is equipped with a ratchet member 420a.

[0050] As shown in FIG. 5, the tip of the ratchet member 420a has a gently curved inclined surface on the side facing the first direction R1. The ratchet member 420a is constantly biased toward the tailstock-side center member 22 by a spring 420b held by the tailstock-side rotation suppression mechanism 42. As a result, when the tailstock-side rotation suppression mechanism 42 is driven with a rotational driving force in the first direction R1 during machining, the ratchet member 420a can overcome the groove 22a of the tailstock-side center member 22, thereby allowing rotation of the tailstock-side center member 22. On the other hand, when correcting the center hole, the tailstock-side rotation suppression mechanism 42 is driven with a rotational driving force in the second direction R2, so the ratchet member 420a engages with the groove 22a of the tailstock-side center member 22 and suppresses rotation of the tailstock-side center member 22. Note that other configurations are the same as those in the first embodiment, and the same reference numerals are used, and their description will be omitted.

[0051] In addition, a configuration similar to the ratchet member 420a of the tailstock side rotation suppression mechanism 42 in this embodiment 2 may be provided in the spindle side rotation suppression mechanism 41, so that rotation of the workpiece W is suppressed and allowed in the same way as rotation of the tailstock side center member 22 is suppressed and allowed by the ratchet member 420a.

[0052] That is, in the second embodiment, the drive mechanism 30 is configured to alternately generate a rotational drive force in a first direction R1 and a rotational drive force in a second direction R2 opposite to the first direction R1, and the rotation suppression mechanism 40 includes a ratchet member 420a that allows one of the workpiece W and the center member 20 to rotate in the first direction R1 but suppresses rotation in the second direction R2. The machining control unit 3a rotates the workpiece W and the center member 20 as a unit using the rotational drive force in the first direction R1 to machine the workpiece. Meanwhile, the center hole correction control unit 3b rotates the workpiece W and the center member 20 relative to each other to correct the center hole, while suppressing rotation of one of the workpiece W and the center member 20 using the rotation suppression mechanism 40, by rotating the other of the workpiece W and the center member 20 using the rotational drive force in the second direction R2.

[0053] In the second embodiment, the ratchet member 420a provided in the tailstock-side rotation suppression mechanism 42 can switch between allowing and suppressing rotation of the tailstock-side center member 22 simply by reversing the rotation direction of the rotational drive force of the motor 31. Furthermore, by providing the spindle-side rotation suppression mechanism 41 with a mechanism similar to the ratchet member 420a provided in the tailstock-side rotation suppression mechanism 42, it is possible to switch between allowing and suppressing rotation of the workpiece W simply by reversing the rotation direction of the rotational drive force of the motor 31. As a result, the control load can be reduced with a simple configuration. The second embodiment also achieves the same effects as the first embodiment.

[0054] (Embodiment 3) 6, the ratchet member 421a has a rectangular cross section, but the recess 220a of the tailstock-side center member 22 has a wall surface that faces the first direction R1 as an upright surface, and the wall surface on the opposite side of the recess 220a is a gently curved inclined surface that has a shape that continues smoothly to the bottom of the recess 220a, thereby realizing a ratchet structure. This embodiment 3 also achieves the same effects as the first and second embodiments.

[0055] (Embodiment 4) In the first embodiment described above, the spindle-side rotation suppressing mechanism 41 includes a retractable drive pin 41a. However, in the fourth embodiment, as shown in FIGS. 7(a) and 7(b), the spindle-side rotation suppressing mechanism 41 includes a rotatable cam member 410a. As shown in FIG. 7(a), the cam member 410a of the spindle-side rotation suppressing mechanism 41 can be rotated so that the tip of the cam member 410a is separated from the drive fitting 32, thereby disengaging the cam member 410a and the drive fitting 32 and allowing rotation of the workpiece W. On the other hand, as shown in FIG. 7(b), the cam member 410a can be rotated so that the tip of the cam member 410a is close to the drive fitting 32, thereby engaging the cam member 410a and the drive fitting 32 and suppressing rotation of the workpiece W. The fourth embodiment also provides the same advantageous effects as the first embodiment.

[0056] It is also possible to provide the tailstock-side rotation suppression mechanism 42 with a configuration similar to the cam member 410a in the spindle-side rotation suppression mechanism 41 in this embodiment 4, so that rotation of the tailstock-side center member 22 is suppressed and allowed in the same way as rotation of the workpiece W is suppressed and allowed by the cam member 410a.

[0057] (Embodiment 5) 9, the machine tool 1 of this embodiment 5 further includes a machining accuracy determination unit 3c and a center hole correction necessity determination unit 3d in addition to the configuration of the above-mentioned embodiment 1. With regard to other configurations, the same components as those of embodiment 1 are assigned the same reference numerals, and the description thereof will be omitted.

[0058] The machining accuracy determination unit 3c shown in Fig. 9 determines the machining accuracy of the workpiece W. The timing for determining the machining accuracy can be during machining or at the end of machining. The method for determining the machining accuracy is not limited, but examples include measuring the size of the workpiece W using a sizing device (not shown) and detecting the difference from a target shape, or acquiring an image of the workpiece W with a camera and comparing it with the target shape through image processing. The determination result by the machining accuracy determination unit 3c can be a numerical representation of the difference between the shape of the workpiece W during machining or after machining is completed and the target shape.

[0059] 9 determines whether or not center hole correction is necessary based on the determination result of the machining accuracy determination unit 3c. The center hole correction necessity determination unit 3d can compare, for example, a preset reference value with the numerical value of the determination result by the machining accuracy determination unit 3c, and determine that center hole correction is necessary if the numerical value of the determination result by the machining accuracy determination unit 3c is greater than the reference value.

[0060] Next, a flow of determining whether or not the center hole needs to be corrected will be described with reference to Fig. 9. First, in step S20 of Fig. 9, the machining control unit 3a starts machining of the workpiece W. Then, in step S21, the machining accuracy determination unit 3c determines the machining accuracy of the workpiece W.

[0061] Then, in step S22, the center hole correction necessity determination unit 3d compares the machining accuracy determined by the machining accuracy determination unit 3c with a reference value. If it is determined in step S22 that the machining accuracy is equal to or less than the reference value, the process proceeds to Yes in step S22, and in step S23, the center hole correction necessity determination unit 3d determines that center hole correction is necessary. Then, steps S2 and onward in the control flow for center hole correction of embodiment 1 shown in Figure 4 are carried out.

[0062] On the other hand, if it is determined in step S22 that the machining accuracy is not equal to or less than the reference value, the process proceeds to No in step S22, and in step S24, the center hole correction necessity determination unit 3d determines that center hole correction is not necessary. After that, in step S25, the machining control unit 3a determines whether machining of the workpiece W has been completed.

[0063] If it is determined in step S25 that the machining of the workpiece W has not been completed, the process proceeds to No in step S25, and in step S26, the machining control unit 3a continues machining of the workpiece W, and then the process returns to step S21 again to perform the subsequent steps. On the other hand, if it is determined in step S25 that the machining of the workpiece W has been completed, the process proceeds to Yes in step S25, and the control flow ends.

[0064] In the fifth embodiment, the center holes W1 and W2 can be corrected at an appropriate timing, improving work efficiency and maintaining machining accuracy.

[0065] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments within the scope of the present invention. [Explanation of symbols]

[0066] 1 Machine tools 3a Machining control section 3b Center hole correction control unit 3c Machining accuracy judgment section 3d Center hole correction necessity judgment section 12 Headstock 13 Tailstock 20 Center member 21 Spindle side center member 22 Tailstock side center member 30 Drive mechanism 31 Motor 32 Drive fittings 33, 41a, 42a drive pin 40 Rotation suppression mechanism 41 Spindle side rotation suppression mechanism 42 Tailstock side rotation suppression mechanism 420a, 421a ratchet members

Claims

1. a center member that is fitted into a center hole formed in an end of the workpiece to support the workpiece in the axial direction and that is rotatable integrally with the workpiece; a drive mechanism that generates a rotational drive force; a rotation suppression mechanism that suppresses rotation of one of the workpiece and the center member; a machining control unit that, when machining the workpiece, rotates the workpiece and the center member as a unit using the rotational drive force to machine the workpiece; and a center hole correction control unit that, during center hole correction to correct the center hole, rotates the other of the workpiece and the center member using the rotation drive force while suppressing rotation of either the workpiece or the center member using the rotation suppression mechanism, thereby rotating the workpiece and the center member relative to each other and grinding the center member and the center hole together to correct the center hole.

2. the center member is provided on a headstock having the drive mechanism and includes a spindle-side center member that fits into a spindle-side center hole provided at an end of the workpiece as the center hole, the rotation suppression mechanism includes a spindle-side rotation suppression mechanism that suppresses rotation of the workpiece, the machining control unit, when machining the workpiece, rotates the workpiece and the spindle-side center member as a unit using the rotational drive force to machine the workpiece, 2. The machine tool according to claim 1, wherein, during the center hole correction, the center hole correction control section rotates the spindle-side center member by the rotational drive force while suppressing rotation of the workpiece by the spindle-side rotation suppression mechanism, thereby causing relative rotation between the workpiece and the spindle-side center member to correct the spindle-side center hole.

3. The drive mechanism includes a drive force generating unit that generates the rotational drive force, a drive fitting connected to the workpiece, and a rotational drive force transmitting unit that is switchable between an engaged state in which the drive fitting is engaged with the drive fitting to transmit the rotational drive force to the workpiece and a disengaged state in which the drive fitting is disengaged from the drive fitting to not transmit the rotational drive force to the workpiece, 3. The machine tool according to claim 2, wherein, during center hole correction, the center hole correction control section disengages the rotation drive force transmission section from the drive fitting and rotates the spindle side center member using the rotation drive force while suppressing rotation of the workpiece with the rotation suppression mechanism, thereby rotating the workpiece and the spindle side center member relative to each other and correcting the spindle side center hole.

4. the center member is provided on a tailstock that presses the workpiece in one axial direction, and includes a tailstock-side center member that fits into a tailstock-side center hole that is provided at an end of the workpiece as the center hole, the rotation suppression mechanism includes a tailstock-side rotation suppression mechanism that suppresses rotation of the tailstock-side center member, the machining control unit, when machining the workpiece, rotates the workpiece and the tailstock-side center member as a unit using the rotational drive force to machine the workpiece, 3. The machine tool according to claim 1, wherein the center hole correction control unit, during the center hole correction, rotates the workpiece using the rotational drive force while suppressing rotation of the tailstock-side center member using the tailstock-side rotation suppression mechanism, thereby causing relative rotation between the workpiece and the tailstock-side center member to correct the tailstock-side center hole.

5. The drive mechanism includes a drive force generating unit that generates the rotational drive force, a drive fitting connected to the workpiece, and a power transmission unit that is switchable between an engaged state in which the drive fitting is engaged with the drive fitting to transmit the rotational drive force to the workpiece and a disengaged state in which the drive fitting is disengaged from the drive fitting to not transmit the rotational drive force to the workpiece, 5. The machine tool according to claim 4, wherein, during the center hole correction, the center hole correction control section, while suppressing rotation of the tailstock-side center member by the tailstock-side rotation suppression mechanism, engages the power transmission section with the drive fitting and rotates the workpiece by the rotational drive force, thereby rotating the workpiece and the tailstock-side center member relative to each other to correct the tailstock-side center hole.

6. the drive mechanism is configured to switch between generating a rotational drive force in a first direction and a rotational drive force in a second direction opposite to the first direction, as the rotational drive force; the rotation suppression mechanism includes a ratchet member that allows one of the workpiece and the center member to rotate in the first direction and suppresses rotation in the second direction, the machining control unit rotates the workpiece and the center member as a unit by the rotational driving force in the first direction, thereby machining the workpiece; 3. The machine tool according to claim 1, wherein the center hole correction control unit corrects the center hole by rotating the workpiece and the center member relative to each other by rotating the other of the workpiece and the center member using the rotation drive force in the second direction while the rotation of one of the workpiece and the center member is suppressed by the rotation suppression mechanism.

7. a machining accuracy determination unit that determines the machining accuracy of the workpiece; a center hole correction necessity determining unit that determines whether or not the center hole needs to be corrected based on the determination result of the machining accuracy of the workpiece, 3. The machine tool according to claim 1, wherein the center hole correction control unit corrects the center hole when the center hole correction necessity determining unit determines that correction of the center hole is necessary.

Images