Work clamping device and hobbing machine

Abstract

To improve processing accuracy by reducing influence of inclination of a core grid in a pull-in operation given to the processing accuracy.SOLUTION: A workpiece holding device 23 according to the present disclosure comprises: a core pushing device 25 which has a core grid 87, a pusher 91 that is attached to the core grid 87 and a float mechanism 85 that holds the core grid 87 in a tiltable manner; a main spindle device 23 which has a contact metal 63 on which a workpiece W is seated, an insertion hole 73 to which the core grid 87 is inserted and a pull-in device 45 that pulls in the core grid 87 inserted to the insertion hole 73 to the depth side of the insertion hole 73; and a movement device which moves the core pushing device 25 in a direction in parallel to the spindle of the main spindle device 23. The movement device moves the core pushing device 25 in a direction approaching the main spindle device 23. The pull-in device 45 pulls in the core grid 87 to make the workpiece W held between the pusher 91 and the contact metal 63. The float mechanism 85 allows tilting of the core grid 87 to the direction in parallel to the spindle in the pull-in operation by the pull-in device 45 to hold it.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure relates to a work clamping device that clamps a work between a tailstock device and a spindle device. [Background technology]

[0002] Various work clamping devices for clamping a workpiece to be machined have been proposed. For example, Patent Document 1 below describes a work clamping device that clamps a workpiece seated on a reference stopper of a rotary table with a stopper attached to a support. The work clamping device in Patent Document 1 moves the support axially to approach the rotary table, and inserts a rod attached to the support into an insertion hole provided in the slider of the rotary table. The work clamping device centers the workpiece by inserting and opening a collet provided around the rod into the workpiece, and then retracts the slider with a power chuck to clamp the workpiece axially between the stopper attached to the rod and the reference stopper. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 59-017137 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described types of workpiece clamping devices, the clamping force must be set according to the machining load to maintain machining accuracy, such as when performing gear cutting on a workpiece using a hob. For example, if the retraction force of the power chuck is increased to accommodate high-load machining, the rod tilts more when retracted, which may cause the center of rotation of the rod to deviate from the center of rotation of the rotary table during machining. Specifically, the rod tilts when retracted due to factors such as the machining accuracy of the reference stopper and the end face of the workpiece that contacts the stopper, and the assembly accuracy of each component relative to the center of rotation. As a result, there is a risk of the rod's center of rotation being misaligned, resulting in a decrease in machining accuracy.

[0005] The present disclosure has been made in consideration of the above problems, and aims to provide a work clamping device and a hobbing machine that can reduce the effect of the inclination of the core bar during the pulling operation on machining accuracy and improve machining accuracy. [Means for solving the problem]

[0006] In order to solve the above problems, this specification provides a core pushing device having a core, a pusher attached to the core, and a float mechanism that tiltably holds the core, a spindle unit having a backing plate for seating a workpiece, an insertion hole into which the core is inserted, and a retraction device that retracts the core inserted into the insertion hole into the back side of the insertion hole, and a moving device that moves the core pushing device in a direction parallel to the spindle of the spindle unit, wherein the moving device moves the core pushing device in a direction approaching the spindle unit, the retraction device retracts the core and holds the workpiece between the pusher and the backing plate, and the float mechanism allows tilting of the core in a direction parallel to the spindle during the retraction operation by the retraction device. The core metal A work clamping device is disclosed. The contents of the present disclosure are not limited to implementation as a work clamping device, and are extremely effective even when implemented as a hobbing machine equipped with a work clamping device. [Effects of the Invention]

[0007] According to the workpiece clamping device and hobbing machine disclosed herein, the tailstock device tiltably holds the mandrel and pusher using a float mechanism. When the retraction device retracts the mandrel in response to clamping the workpiece, a force for clamping the workpiece is applied to the pusher and the backing metal. For example, if the retraction force of the retraction device is increased to handle high loads during machining, the float mechanism causes the mandrel and pusher to tilt relative to the main body of the tailstock device. Therefore, the tailstock device does not tilt as a whole, and the center of rotation is prevented from shifting relative to the spindle of the spindle device during machining operations. As a result, machining accuracy can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of a hob module according to the present embodiment. [Figure 2] Block diagram of the hob module. [Figure 3] FIG. [Figure 4] 8 is a cross-sectional view taken along line II in FIG. 7. [Figure 5] FIG. [Figure 6] FIG. 10 is a cross-sectional view of the tailstock device and the spindle device at the workpiece centering position. [Figure 7] FIG. 10 is a cross-sectional view of the tailstock device and the spindle device when the tailstock hydraulic cylinder is operated. [Figure 8] FIG. 10 is a cross-sectional view of the tailstock device and the spindle device when the spindle hydraulic cylinder is operated. DETAILED DESCRIPTION OF THE INVENTION

[0009] A hob module, which is an embodiment of a hob machine according to the present disclosure, will be described below with reference to the drawings. FIG. 1 shows a perspective view of a hob module 10 according to this embodiment. FIG. 1 also shows the hob module 10 with an exterior cover (not shown) removed. FIG. 2 shows a block diagram of the hob module 10. In the following description, as shown in FIG. 1, the direction along the spindle 11 of the spindle unit 23 is referred to as the Z-axis direction, the direction perpendicular to the Z-axis direction and corresponding to the front-to-rear direction of the device is referred to as the X-axis direction, and the direction perpendicular to the X-axis and Z-axis directions is referred to as the Y-axis direction (left-right direction). The X-axis direction and Y-axis direction are, for example, directions parallel to the installation surface of the hob module 10.

[0010] The hob module 10 is installed, for example, as one of a plurality of modules lined up in the Y-axis direction. A system (hereinafter referred to as a machine tool system) equipped with a plurality of modules including the hob module 10 performs machining or the like on a workpiece using the plurality of modules lined up in the Y-axis direction. The machine tool system includes a workpiece transport robot 15 that moves in the Y-axis direction along slide rails 13 provided on the front of each module. The workpiece transport robot 15 is an articulated robot that transfers workpieces between each module including the hob module 10 and moves in the Y-axis direction to transport the workpiece from a module in a previous process to a module in a subsequent process.

[0011] As shown in FIGS. 1 and 2 , the hob module 10 includes a base 21, a spindle unit 23, a tailstock unit 25, a tailstock moving unit 27, a hob 29, a hob drive unit 31, a control panel 33, an operation panel 35, a control device 37, and the like. The hob module 10 is, for example, a modularized hobbing machine, and performs gear cutting on a workpiece using the hob 29. The base 21 has a generally rectangular parallelepiped shape that is long in the X-axis direction and has a predetermined thickness in the Z-axis direction. The slide rail 13 described above is provided on the front surface of the base 21. A bed 39 is provided on the base 21. The bed 39 is slidable in the X-axis direction relative to the base 21 by a plurality of wheels 38. The spindle unit 23, the tailstock unit 25, the tailstock moving unit 27, the hob 29, the hob drive unit 31, the control panel 33, the operation panel 35, the control device 37, and the like are provided on the base 21 and are slidable together with the base 21.

[0012] The spindle device 23 extends along the spindle 11 and has a stopper 63 (see FIG. 3) on its top for seating the workpiece W (see FIG. 3). The spindle device 23 includes a spindle motor 41, an encoder 43, and a stopper 63 (see FIG. 3) for supporting the workpiece W. The spindle device 23 has the rotation of the spindle motor 41 controlled under the control of the control device 37, and rotates the workpiece W around the spindle 11. The encoder 43 outputs information on the rotation position of the spindle motor 41 to the control device 37. This enables the control device 37 to control the rotation speed, acceleration, etc. of the spindle device 23.

[0013] The tailstock device 25 is supported by a tailstock moving device 27 at a position above the spindle device 23. The tailstock device 25 moves in the Z-axis direction along the spindle 11 based on the drive of the tailstock moving device 27. The tailstock device 25 holds a workpiece W (see FIG. 3) between itself and the spindle device 23, and rotates around the spindle 11. Details of the spindle device 23, the tailstock device 25, and the tailstock moving device 27 will be described later.

[0014] The hob 29 is a cutting tool having, for example, a cylindrical shape with its axis oriented in the Y-axis direction and a cutting edge on its outer periphery for performing gear cutting. The hob drive device 31 includes a hob motor 31A (see FIG. 2) that rotates the hob 29 about a B-axis 51 that is parallel to the Y-axis direction. The hob drive device 31 also includes an X-axis slide mechanism 31B that changes the position of the hob 29 in the X-axis direction and a Z-axis slide mechanism 31C that changes the position of the hob 29 in the Z-axis direction. The control device 37 controls the hob drive device 31, for example, to change the rotational speed and position of the hob 29 and perform gear cutting by bringing the rotating hob 29 into contact with the workpiece W clamped between the spindle device 23 and the tailstock device 25.

[0015] The control panel 33 is provided at the rear of the hob module 10 and is provided with a breaker and the like that switches the power supply from the power supply device to each device of the hob module 10. The operation panel 35 is a user interface and is provided, for example, on the front surface of an exterior cover (not shown) of the hob module 10 and is provided with a touch panel, operation switches, and the like.

[0016] The control device 37 is a processing device equipped with a CPU 53 and mainly composed of a computer, which executes numerical control and sequence control to comprehensively control the operation of the hob module 10. The control device 37 is electrically connected to each device of the hob module 10 (such as the spindle motor 41 and the hob motor 31A) via a drive circuit 55, and is capable of controlling the operation of each device. The drive circuit 55 is, for example, an amplifier circuit that controls the power supply to the spindle motor 41, etc. The control device 37 also includes a storage device 57. The storage device 57 includes, for example, RAM, ROM, flash memory, a hard disk, etc. Various control data D1 are stored in the storage device 57.

[0017] The control data D1 contains, for example, programs for controlling the operation of the spindle unit 23, the tailstock moving unit 27, and the hob driving unit 31, the type of workpiece W to be produced, the position of the hob 29 relative to the workpiece W during operation, and other data. The programs referred to here include, for example, a sequence control program (ladder circuit) and an NC program. The control data D1 also stores a control program for controlling the clamping operation of the workpiece W by the spindle unit 23 and the tailstock moving unit 27, which will be described later. The control device 37 controls the operation of each device by executing the program of the control data D1 using the CPU 53. In the following description, the control of each device by the control device 37 executing the program of the control data D1 may be referred to simply by the device name. For example, "the control device 37 controls the spindle motor 41 of the spindle unit 23" means "the control device 37 executes the program of the control data D1 using the CPU 53 and controls the spindle motor 41 via the drive circuit 55."

[0018] The control device 37 controls each device with the above-mentioned configuration to perform gear cutting on the workpiece W. For example, when the workpiece W is set on the stopper 63 (see FIG. 3) of the spindle device 23 by the workpiece transfer robot 15, the control device 37 controls the tailstock moving device 27 to lower the tailstock device 25, and the workpiece W is clamped between the spindle device 23 and the tailstock device 25. Control device The control device 37 controls the spindle motor 41 to rotate the workpiece W, while the hob drive device 31 rotates the hob 29, causing it to come into contact with the workpiece W and perform machining. When machining is completed, the control device 37 controls the tailstock moving device 27 to raise the tailstock device 25. The workpiece transport robot 15 receives the machined workpiece W from the spindle device 23 and transports it to a module for a subsequent process, etc. This allows the desired machining to be performed on the workpiece W by multiple modules.

[0019] (Regarding the spindle unit 23 and the tailstock unit 25) Next, the spindle unit 23 and the tailstock unit 25 will be described in detail. Fig. 3 shows a cross-sectional view of the tailstock unit 25 and the spindle unit 23 cut along a plane parallel to the Y-axis direction and the Z-axis direction. As shown in Fig. 3, the spindle unit 23 has a device main body 61 and a stopper 63 fixed to the upper surface of the device main body 61. The spindle unit 23 rotates the stopper 63 and the workpiece W seated on the stopper 63 about the spindle 11 based on the rotation of a spindle motor 41 provided in the device main body 61. In the following description, the side closer to the spindle 11 in the direction perpendicular to the spindle 11 will be referred to as the inner side, and the side farther from the spindle 11 will be referred to as the outer side.

[0020] The device main body 61 includes a spindle hydraulic cylinder 45 that functions as a drive source for the retraction device of this embodiment. A shaft 65 is connected to the output rod of the spindle hydraulic cylinder 45. The shaft 65 advances and retreats in the Z-axis direction along the spindle 11 in response to the drive of the spindle hydraulic cylinder 45. A pair of tops 67 are provided at the upper end of the shaft 65. The tops 67 are attached to the upper end of the shaft 65 by pins 69. The tops 67 are arranged to face each other in a direction perpendicular to the spindle 11 and are movable toward each other. The tops 67 are arranged with their protrusions facing each other. The tops 67 move in the Z-axis direction together with the shaft 65 based on the movement of the shaft 65, i.e., the drive of the spindle hydraulic cylinder 45. For example, when hydraulic oil is not supplied to the spindle hydraulic cylinder 45 and the pair of tops 67 is not driven, the pair of tops 67 are urged upward by elastic members 71 provided on the outer periphery of the shaft 65 and are disposed in the position shown in Fig. 3 (hereinafter referred to as the initial position). The elastic members 71 are, for example, compression springs. As the spindle hydraulic cylinder 45 is driven, the pair of tops 67 are retracted downward from the initial position shown in Fig. 3 and retract the core bar 87. Therefore, the spindle hydraulic cylinder 45, the shaft 65, and the tops 67 function as the retraction device of the present disclosure.

[0021] Insertion holes 73 are provided in the center of the upper portion of the device main body 61 and the center of the abutment 63, into which a core metal 87 of the tailstock device 25 (described later) is inserted. The insertion hole 73 is a hole formed along the spindle 11. A shaft hole 65A is also formed in the center of the shaft 65. The shaft hole 65A is formed along the spindle 11 and has an opening on the upper surface of the shaft 65. The bottom of the insertion hole 73 communicates with the opening of the shaft hole 65A. The insertion hole 73 widens outward in a direction perpendicular to the spindle 11 at a portion that serves as the initial position of the top 67, forming a recess that accommodates the top 67. The diameter of the insertion hole 73 is shorter below the initial position of the top 67. Therefore, when the pair of tops 67 are pulled toward the back of the insertion hole 73, i.e., downward, by the drive of the spindle hydraulic cylinder 45, they are guided by the inner wall of the insertion hole 73 and move inward toward each other. The pair of pieces 67 sandwich an engaging portion 87G (see FIG. 5) at the tip of the core metal 87 from both sides in the direction perpendicular to the main shaft 11 with their respective convex portions, and pull the core metal 87 downward.

[0022] FIG. 4 shows a cross section taken along line II shown in FIG. 7, which will be described later. As shown in FIGS. 3 and 4, abutment 63 is a metal member that is disposed around insertion hole 73 and has a ring shape in a plan view (when viewed in the Z-axis direction). The center of abutment 63 is disposed on main shaft 11. A groove 63A that opens upward is formed in abutment 63. The inner diameter of groove 63A increases from the bottom to the top, and the groove 63A has a ring shape centered on main shaft 11 in a plan view. The backing metal 63 is fixed to the upper end of the device main body 61 by a bolt 75 inserted into the bottom 63B of the groove 63A. The backing metal 63 is changed depending on the type of workpiece W. Therefore, the shapes of the workpiece W and backing metal 63 shown in FIG. 3 are merely examples.

[0023] A collet 77 is provided at the upper end of the insertion hole 73, at a position that corresponds to the upper center of the abutment plate 63. The collet 77 has, for example, multiple slits that are parallel to the Z-axis direction. The collet 77 is pushed downward by an abutment member 109 (see FIG. 5 ) of the core support device 25, which will be described later, and is thereby pushed open (spread) outward. When the collet 77 opens, it positions (centers) the workpiece W seated on the abutment plate 63 so that the center of the workpiece W is on the spindle 11, thereby clamping the workpiece W. A collet elastic member 79 and a collet pusher 81 are provided below the collet 77 at a portion that is inserted into the abutment plate 63 at the top of the device main body 61. The collet elastic member 79 is, for example, a compression spring, and urges the collet pusher 81, which is provided above it, upward. When the collet 77 is not being pushed downward by the core support device 25, the collet pusher 81 urges the collet 77 upward by the urging force of the collet elastic member 79, closing the collet 77. When the collet 77 is closed, it is in an unclamped state in which it releases the workpiece W from its holding position.

[0024] The workpiece W is, for example, a ring-shaped member, and is placed on the backing plate 63 by the workpiece transfer robot 15 (see FIG. 1). The workpiece W is placed, for example, on a portion of the backing plate 63 where the groove 63A is not formed, with a part of the workpiece W inserted into the groove 63A. The outer diameter of the workpiece W is, for example, about 10 cm.

[0025] FIG. 5 shows an enlarged view of the tailstock device 25. As shown in FIGS. 3 and 5, the tailstock device 25 includes a device main body 83, a rotor 84, a float mechanism 85, a mandrel 87, a pusher mounting member 89, and a pusher 91. The device main body 83 moves in the Z-axis direction along the spindle 11 based on the drive of the tailstock moving device 27. The tailstock moving device 27 includes a servo motor 93 and a tailstock hydraulic cylinder 95 as a drive source for moving the device main body 83 (see FIG. 2). As shown in FIG. 1, the tailstock moving device 27 includes a pair of Z-axis guide rails 27A extending parallel to the Z-axis direction and a Z-axis slide 27B that is slidable relative to the Z-axis guide rails 27A. The pair of Z-axis guide rails 27A are disposed parallel to the Z-axis direction with a predetermined gap between them in the X-axis direction, and support the Z-axis slide 27B so that it can slide in the Z-axis direction. The Z-axis slide 27B is attached to the device main body 83 of the tailstock device 25. The tailstock moving device 27 transmits the rotation output of the servo motor 93 to the Z-axis slide 27B via a transmission mechanism (such as a ball screw), for example, and moves the Z-axis slide 27B, i.e., the tailstock device 25, in the Z-axis direction.

[0026] The tailstock moving device 27 is provided with an encoder 97 that outputs information about the rotational position of the servo motor 93. The control device 37 can move the Z-axis slide 27B to any position in the Z-axis direction based on the rotational position information output from the encoder 97. The device for detecting the position of the Z-axis slide 27B is not limited to the encoder 97, and other devices such as a linear scale may also be used. The tailstock hydraulic cylinder 95 urges a rotating body 84 of the tailstock device 25 (described later) downward, and urges a mandrel 87 downward via the rotating body 84. The tailstock hydraulic cylinder 95 urges the rotating body 84 and mandrel 87 downward along the Z-axis direction based on the control of the control device 37.

[0027] The rotating body 84 is rotatably attached to the device main body 83 via, for example, a bearing member 99 (such as a ball bearing), and rotates around the Z-axis direction. A float mechanism 85 is attached below the rotating body 84. The float mechanism 85 includes a support member 86 and a screw member 88. The support member 86 is attached to the rotating body 84 by, for example, a bolt 101. The support member 86 is fixed to the rotor 84 and rotates together with the rotor 84. The support member 86 is, for example, a metal member that is substantially circular when viewed from the Z-axis direction. A recess 86A is formed in the center of the support member 86. The recess 86A is formed by recessing the support member 86 from bottom to top. A protrusion 87C of the core metal 87, which will be described later, is inserted into the recess 86A. The recess 86A is, for example, a substantially conical groove, and a center 86B of the bottom is located on the main shaft 11 (see FIG. 5). A tapered surface 86C is formed on the inner circumferential surface of the recess 86A. The tapered surface 86C is inclined at a predetermined angle and is inclined upward from the outside to the inside in a direction perpendicular to the main shaft 11.

[0028] The core metal 87 has a base portion 87A and a rod portion 87B. The base portion 87A is, for example, a substantially disc-shaped member having a predetermined thickness in the Z-axis direction. The core metal 87 is tiltably held by the float mechanism 85. A convex portion 87C is formed on the upper surface of the core metal 87. The convex portion 87C protrudes upward from the upper surface of the center of the base portion 87A. The convex portion 87C has, for example, a substantially circular shape when viewed from the Z-axis direction. The upper surface of the convex portion 87C is, for example, formed by a spherical surface 87D curved at a certain curvature (see the enlarged view of Figure 5), and bulges upward. The support member 86 supports the core metal 87 with the spherical surface 87D of the convex portion 87C inserted into the recessed portion 86A and the tapered surface 86C in contact with the spherical surface 87D. A center 87E of spherical surface 87D (the apex of convex portion 87C) is located on main shaft 11 when core bar 87 is not tilted (see the enlarged view in FIG. 5). In other words, when viewed from the Z-axis direction when core bar 87 is not tilted, spherical surface 87D has a circular shape centered on main shaft 11, and center 87E coincides with (overlaps with) center 86B of recess 86A.

[0029] Furthermore, a through-hole 87F is formed in the base 87A outside the protrusion 87C. The through-hole 87F is formed penetrating the base 87A in a direction parallel to the Z-axis direction. A threaded member 88 of the float mechanism 85 is inserted into the through-hole 87F. The threaded member 88 is, for example, a bolt, and has a tip end 88A threaded into the support member 86 and a head end 88B housed within the through-hole 87F. Note that the threaded member 88 is not limited to a bolt, and may be another threadable member such as a screw.

[0030] The threaded member 88 is fixed in the through hole 87F with a gap 105 between the head 88B in the Z-axis direction and the bottom of the portion of the through hole 87F that accommodates the head 88B. In other words, the core bar 87 is in a state in which the head 88B of the threaded member 88 contacts the bottom of the through hole 87F, i.e., in a state in which the threaded member 88 is slightly loosened from its normal tightening state. For example, the shape and size of the portion of the through hole 87F that accommodates the head 88B are adjusted so that a gap 105 is formed between the head 88B and the through hole 87F when the male thread provided on the tip end 88A of the threaded member 88 is fully tightened onto the female thread of the support member 86. The core bar 87 is tiltable within a predetermined angle range with respect to the spindle 11 by having the spherical surface 87D contact the tapered surface 86C and being held in the through hole 87F with the gap 105. In other words, the core metal 87 is held in a state where it rattles slightly relative to the support member 86. The angle by which the core metal 87 can tilt relative to the main shaft 11 is, for example, about 0.1 to 0.2 degrees.

[0031] The rod portion 87B is a substantially cylindrical member and extends downward from the lower surface at the center of the base portion 87A. When no external force is applied, the core metal 87 is disposed in the posture shown in FIGS. 3 and 5, i.e., in a state where it is not tilted with respect to the main shaft 11, due to, for example, its own weight or the weight of the pusher mounting member 89 or the pusher 91. In this posture, the axial direction of the rod portion 87B is aligned with the main shaft 11. In other words, when the core metal 87 is not tilted, the rod portion 87B extends from the base portion 87A along the main shaft 11.

[0032] An engagement portion 87G is formed at the tip of the rod portion 87B. The engagement portion 87G is formed at a position slightly back from the tip of the rod portion 87B toward the base portion 87A (base end), and is connected to the other portion. The rod portion 87B has a cylindrical shape with a smaller diameter than the main spindle unit 23. Therefore, the rod portion 87B has an inwardly recessed portion formed on the outer periphery at the portion where the engaging portion 87G is formed. The engaging portion 87G engages with a pair of blocks 67 of the main spindle unit 23 and is pulled downward by the main spindle hydraulic cylinder 45.

[0033] The pusher mounting member 89 is attached below the base 87A around the base end of the rod portion 87B. The pusher mounting member 89 is fixed to the base 87A with a bolt 107 and tilts together with the core 87. An abutment member 109 is provided in the center of the pusher mounting member 89. The abutment member 109 is, for example, a substantially cylindrical member that covers the outer periphery of the rod portion 87B and has a bottom at the bottom. The bottom of the abutment member 109 is formed with, for example, a hole 109B into which the rod portion 87B is inserted and an annular collet projection 109A surrounding the hole 109B. The collet projection 109A is formed in a position close to the rod portion 87B and protrudes downward. An elastic member 111 is provided within the abutment member 109. The elastic member 111 is, for example, a compression spring, and is provided on the outer periphery of the rod portion 87B. Elastic member 111 is compressed as contact member 109 (collet protrusion 109A) is pushed upward, and elastic force urges contact member 109 downward. Tailstock device 25 pushes open collet 77 of spindle device 23 with collet protrusion 109A.

[0034] The pusher mounting member 89 holds the pusher 91 relative to the core metal 87. The pusher 91 is mounted below the pusher mounting member 89. The pusher 91 is, for example, a ring-shaped metal member (see FIG. 4 ) and is fixed to the pusher mounting member 89 by a screw member (such as a bolt) 113. Therefore, the pusher 91, together with the pusher mounting member 89 and the core metal 87, is tiltable relative to the support member 86. A contact surface 91A that comes into contact with the workpiece W is formed on the underside of the pusher 91. The pusher 91 clamps the workpiece W between this contact surface 91A and the abutment metal 63.

[0035] (Workpiece W clamping operation) Next, the clamping operation of the workpiece W by the tailstock device 25 and the spindle device 23 will be described. For example, when the machining of the workpiece W by the upstream process module is completed, the machine tool system controls the workpiece transfer robot 15 to transfer the workpiece W from the upstream process module to the hob module 10. The workpiece transfer robot 15 moves to the front of the hob module 10 and sets the workpiece on the backing plate 63 of the spindle device 23. Before the workpiece transfer robot 15 sets the workpiece W, the control device 37 of the hob module 10 moves the tailstock device 25 upward to a position where the rod portion 87B of the mandrel 87 is removed from the insertion hole 73 of the spindle device 23. In this state, the workpiece transfer robot 15 inserts the hole of the workpiece W into the collet 77 of the spindle device 23 and places the workpiece W on the backing plate 63.

[0036] The control device 37 supplies air from the spindle unit 23 through, for example, a pipe 63C (see FIG. 3) provided in the backing member 63, and determines whether the workpiece W has been set (seated) on the backing member 63 based on the air pressure (leakage amount). The control device 37 confirms the retraction of the workpiece transport robot 15, and when it detects that the workpiece W has been set, starts the lowering of the tailstock device 25. The control device 37 drives the servo motor 93 of the tailstock moving device 27 to lower the Z-axis slide 27B, thereby lowering the tailstock device 25. As shown in FIG. 3, the control device 37 inserts the tip of the rod portion 87B of the core 87 into the insertion hole 73 of the spindle unit 23. In the state shown in FIG. 3, the tailstock hydraulic cylinder 95 is not supplied with hydraulic oil, for example, and the output rod is raised to the upper end position. Furthermore, for example, hydraulic oil is not supplied to spindle hydraulic cylinder 45, and no pulling force is applied to shaft 65 via the output rod, and the output rod (shaft 65) is pulled up to the upper end position by the elastic force of elastic member 71. Also, collet 77 is pushed upward by collet elastic member 79, and is in an unclamped state (closed state).

[0037] The control device 37 continues to lower the tailstock device 25 even after the tip of the rod portion 87B is inserted into the insertion hole 73. When the tailstock device 25 is lowered to the position shown in FIG. 6 (hereinafter referred to as the workpiece centering position), the control device 37 temporarily stops the lowering of the tailstock device 25. At the workpiece centering position, the collet projection 109A of the abutting member 109 is positioned to contact the collet 77 from above, and the elastic force of the elastic member 111 pushes the collet 77 open (see the enlarged view in FIG. 6). As described above, the pusher mounting member 89 of this embodiment includes the elastic member 111 and the abutting member 109 that is biased downward by the elastic member 111 when it contacts the collet 77, pushing the collet 77 open. As a result, when the abutting member 109 contacts the collet 77, the elastic member 111 is compressed and deformed in the Z-axis direction, and the elastic force pushes the collet projection 109A downward, opening the collet 77. The collet 77 allows the workpiece W to be positioned (centered) appropriately.

[0038] Meanwhile, the pusher 91 is positioned slightly above the top surface of the workpiece W, with a gap 115 between the contact surface 91A and the workpiece W in the Z-axis direction (see the enlarged view in FIG. 6 ). In other words, the control device 37 feedback-controls the servo motor 93 based on the position information of the encoder 97, and stops the descent of the tailstock device 25 at a position where the collet projection 109A contacts the collet 77 but the contact surface 91A does not contact the workpiece W. When the workpiece W and the pusher 91 come into contact with each other, a frictional force between the pusher 91 and the abutment 63 and a clamping force between the pusher 91 and the abutment 63 are generated on the workpiece W. This restricts the movement of the workpiece W. Therefore, if the pusher 91 comes into contact with the workpiece W when the collet 77 is opened to clamp the workpiece W and center it at a predetermined position, the collet 77 will not open properly, and the workpiece W will not be positioned in the desired position or orientation.

[0039] Therefore, the control device 37 of the present disclosure keeps the pusher 91 out of contact with the workpiece W when opening and clamping the collet 77 (see FIG. 6). The control device 37 of this embodiment controls the servo motor 93 of the tailstock moving device 27 to stop the tailstock device 25 at a position where the workpiece W seated on the stopper 63 and the contact surface 91A of the pusher 91 are separated and the abutment member 109 comes into contact with the collet 77 to push the collet 77 open. This prevents the movement of the workpiece W from being hindered by the pusher 91, and the workpiece W follows the collet 77 to assume a desired position and orientation. The desired position and orientation here refers to, for example, a state in which the center of the workpiece W is on the spindle 11 and the plane of the workpiece W is approximately parallel to the X-axis direction and the Y-axis direction (centered state).

[0040] Next, the control device 37 drives the tailstock hydraulic cylinder 95 of the tailstock moving device 27 while stopping the servo motor 93 at the workpiece centering position shown in FIG. 6. The tailstock device 25 and the spindle device 23 are in the state shown in FIG. 7. The control device 37 supplies hydraulic oil to the tailstock hydraulic cylinder 95, for example, and causes the tailstock hydraulic cylinder 95 to urge the tailstock device 25 downward with a predetermined hydraulic pressure. Furthermore, in the state shown in FIG. 7, the control device 37 does not drive the spindle hydraulic cylinder 45, maintaining a state in which no pulling force is applied to the shaft 65. The pusher 91 is urged downward in response to the force applied by the tailstock hydraulic cylinder 95, causing the contact surface 91A to contact the workpiece W. The gap 115 shown in FIG. 6 described above is no longer present. The workpiece W is sandwiched between the pusher 91 and the retaining plate 63 in the Z-axis direction. The pusher 91 is tiltably held by the float mechanism 85 via the pusher mounting member 89, and therefore tilts when a reaction force is applied from the workpiece W. The pusher 91 presses the workpiece W while tilting in accordance with the position and posture of the workpiece W positioned by the collet 77. In other words, by tilting due to the float mechanism 85, the pusher 91 can apply a clamping force to the workpiece W without changing the position or posture of the workpiece W that has been placed in a desired position or posture.

[0041] Next, the control device 37 drives the main shaft hydraulic cylinder 45 of the main shaft device 23 to lower the top 67 and retract the mandrel 87. As shown in FIG. 7, the main shaft hydraulic cylinder 9 When the shaft 65 is driven, the engaging portion 87G of the core 87 is positioned between the pair of pieces 67. As shown in FIG. 8, the control device 37 drives the spindle hydraulic cylinder 45 to move the shaft 65 downward. For example, the control device 37 stops the spindle motor 41 at the workpiece centering position shown in FIG. 6 and drives the spindle hydraulic cylinder 45 while maintaining the hydraulic pressure of the tailstock hydraulic cylinder 95 at the predetermined level when the spindle motor 41 is driven as shown in FIG. 7. That is, the control device 37 drives the spindle hydraulic cylinder 45 while maintaining the spindle motor 41 and the tailstock hydraulic cylinder 95 in the same states as before driving the spindle hydraulic cylinder 45. The pair of pieces 67 move downward as the shaft 65 descends, and also move inward toward each other by following the insertion hole 73. The pair of pieces 67 descend while sandwiching the engaging portion 87G, thereby drawing the core 87 downward, i.e., toward the back of the insertion hole 73.

[0042] Here, for example, if the load generated during gear cutting is high, it may be difficult to firmly fix the workpiece W using only the clamping force of the collet 77 or the pressing force of the tailstock hydraulic cylinder 95, which could result in the workpiece W being misaligned and reduced machining accuracy. Therefore, the core 87 is retracted using the stronger force of the spindle hydraulic cylinder 45, and the workpiece W is clamped from both axial sides by the pusher 91 and the backing plate 63. For example, the output of the spindle hydraulic cylinder 45 is several tons, which is greater than the output of the tailstock hydraulic cylinder 95. However, if the output (retraction force) of the spindle hydraulic cylinder 45 is increased in response to an increase in the load during gear cutting, there is a risk that the core 87 will tilt. Specifically, depending on the machining accuracy of the top and bottom surfaces of the workpiece W, the retraction operation may cause tilt between the workpiece W and the backing plate 63 or between the workpiece W and the pusher 91. Alternatively, an error in the assembly of the components involved in clamping the workpiece W, such as the backing plate 63, pusher mounting member 89, pusher 91, and mandrel 87, relative to the main shaft 11, i.e., the center of rotation, can cause the components to tilt during the retraction operation. If the position and orientation of the mandrel 87 were fixed relative to the support member 86, the tilt of the mandrel 87 would result in a tilt of the support member 86 and the rotating body 84, and thus a tilt of the entire tailstock device 25. As a result, the center of rotation of the tailstock device 25 would shift, resulting in a decrease in machining accuracy.

[0043] Therefore, the tailstock device 25 of this embodiment holds the mandrel 87 tiltably using a float mechanism 85. As a result, for example, in the example shown in FIG. 8 , when the mandrel 87 is retracted, the mandrel 87, the pusher mounting member 89 attached to the mandrel 87, and the pusher 91 are tilted slightly leftward with respect to the spindle 11. In this way, the tilt generated in the mandrel 87 via the pusher 91 is absorbed by the float mechanism 85, so that the tilt of the entire tailstock device 25 with respect to the spindle 11 can be eliminated. As a result, it is possible to ensure a sufficient clamping force on the workpiece W while reducing the deviation of the rotation center of the tailstock device 25, and therefore the machining accuracy of the workpiece W can be improved.

[0044] 5 , the support member 86 of the float mechanism 85 has a recess 86A with a tapered surface 86C, and supports the core 87 by bringing the tapered surface 86C into contact with the spherical surface 87D of the core 87. The threaded member 88 of the float mechanism 85 is inserted into the through-hole 87F of the core 87, and its tip 88A is screwed into the support member 86. In this screwed state, a gap 105 is provided between the head 88B and the bottom of the portion of the through-hole 87F that accommodates the head 88B. This allows the core 87 to move slightly freely relative to the threaded member 88 without being completely tightened and fixed by the threaded member 88. The spherical surface 87D of the core 87 is brought into contact with the tapered surface 86C of the support member 86, allowing the core 87 to tilt smoothly.

[0045] The support member 86 has a recess 86A into which the protrusion 87C of the core 87 is inserted, and a tapered surface 86C is provided on the inner peripheral surface of the recess 86A. With the protrusion 87C inserted into the recess 86A, the tapered surface 86C comes into contact with the spherical surface 87D to support the core 87. The center 86B of the recess 86A is located on the spindle 11 of the spindle device 23 (see FIG. 5). For example, by aligning the center 86B of the recess 86A with the position of the main shaft 11 and inserting the protrusion 87C into the recess 86A, the core bar 87 can be tilted around the main shaft 11.

[0046] Furthermore, after the control device 37 pushes open the collet 77 with the abutment member 109 (FIG. 6), it controls the tailstock hydraulic cylinder 95 to urge the tailstock device 25 downward toward the spindle device 23, bringing the pusher 91 into contact with the workpiece W and sandwiching the workpiece W between the pusher 91 and the abutment 63 (FIG. 7). After controlling the tailstock hydraulic cylinder 95 to sandwich the workpiece W, the control device 37 drives the spindle hydraulic cylinder 45 to retract the mandrel 87 into the back side of the insertion hole 73. According to this, first, the collet 77 is opened by the abutment member 109 to clamp the workpiece W, and then the tailstock hydraulic cylinder 95 brings the pusher 91 and the workpiece W into contact with each other. Thereafter, the spindle hydraulic cylinder 45 retracts the workpiece W with a stronger force. By filling the gap 105 between the pusher 91 and the workpiece W before retracting with the spindle hydraulic cylinder 45, it is possible to avoid a collision between the workpiece W and the pusher 91 due to the retraction of the spindle hydraulic cylinder 45. Furthermore, by temporarily determining the position of the workpiece W using the collet 77 and the tailstock hydraulic cylinder 95, which have weaker restricting force than the spindle hydraulic cylinder 45, and then positioning it with the strong force of the spindle hydraulic cylinder 45, it is possible to accurately position the workpiece W at the desired centering position.

[0047] 7, the control device 37 controls the tailstock hydraulic cylinder 95 to bias the tailstock device 25 with a predetermined hydraulic pressure, thereby sandwiching the workpiece W between the pusher 91 and the backing 63. Then, in the retraction operation of FIG. 8, the control device 37 executes retraction by the spindle hydraulic cylinder 45 while maintaining the hydraulic pressure of the tailstock hydraulic cylinder 95 at the above-mentioned predetermined hydraulic pressure. By keeping the pushing force of the tailstock hydraulic cylinder 95 constant when the spindle hydraulic cylinder 45 is retracted, it is possible to prevent the workpiece W from shifting position when retracted.

[0048] 8, the control device 37 drives the spindle hydraulic cylinder 45 to sandwich the workpiece W between the spindle device 23 and the tailstock device 25, and then drives the hob drive device 31 to rotate the hob 29 to perform gear cutting on the workpiece W. This allows machining to be performed while suppressing misalignment of the rotation center of the tailstock device 25 with respect to the spindle 11, thereby improving machining accuracy.

[0049] Incidentally, the hob module 10 is an example of a hobbing machine. The spindle device 23 and tailstock device 25 are examples of a work clamping device. The tailstock moving device 27 is an example of a moving device and a work clamping device. The spindle hydraulic cylinder 45, shaft 65, and top 67 are examples of a retraction device. The servo motor 93 is an example of a motor. The tailstock hydraulic cylinder 95 is an example of a fluid pressure cylinder. The spherical surface 87D is an example of a curved surface.

[0050] As described above, the present embodiment has the following advantages. The float mechanism 85 of the hob module 10 according to one aspect of the present application allows and holds the mandrel 87 tilted relative to the spindle 11 during the retraction operation of the spindle hydraulic cylinder 45. This allows the float mechanism 85 to absorb any tilt that occurs in the mandrel 87, eliminating or significantly minimizing any deviation of the rotation center of the tailstock device 25 (rotating body 84) from the spindle 11. As a result, the effect of the tilt of the mandrel 87 during the retraction operation on the accuracy of subsequent machining can be reduced, improving machining accuracy.

[0051] Furthermore, the contents of the present disclosure are not limited to the above-described examples, but can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. For example, in the above embodiment, the hob module 10, which is a module incorporated into a machine tool system, is used as the hobbing machine of the present disclosure, but this is not limited to this. The hobbing machine of the present disclosure may be a single device. Also, the hobbing machine may not be equipped with a workpiece transport robot 15 or the like, and may be a device in which the user manually positions the workpiece W. Also, the hobbing machine is not limited to an NC type machining device. The hobbing machine may be configured without the control device 37. In this case, the hobbing machine may be a device that drives the main shaft hydraulic cylinder 45, the servo motor 93, and the tailstock hydraulic cylinder 95 by a predetermined movement amount in response to a button operation by a user. Furthermore, the device for transferring the workpiece to the hobbing machine is not limited to an articulated robot such as the workpiece transfer robot 15, but may be, for example, a gantry type loader. Furthermore, the direction of the spindle 11 of the spindle device 23 is not limited to the vertical direction of the device, but may be the horizontal direction. That is, the hobbing machine of the present disclosure may be a horizontal hobbing machine.

[0052] The configurations of the spindle unit 23 and tailstock unit 25 in the above embodiment are merely examples. For example, the spindle unit 23 does not have to be equipped with the collet 77. Furthermore, the tailstock unit 25 does not have to be equipped with the pusher mounting member 89. Furthermore, the output of the tailstock hydraulic cylinder 95 may be the same as or greater than the output of the spindle hydraulic cylinder 45. The above-described configuration of the float mechanism 85 is merely an example. For example, in the above embodiment, the curved surface of the present disclosure is a spherical surface 87D curved at a constant curvature, but this is not limiting. The curved surface may be a surface having an elliptical cross section, or may be a surface that is curved multiple times. Alternatively, the above relationship may be reversed, with a recess formed in the core 87 and a protrusion formed in the support member 86 that contacts the recess. The float mechanism 85 may be configured to tiltably hold the core 87 using an elastic member such as a spring. The support member 86 may have, for example, a hole into which the tip of the protrusion 87C of the core 87 is inserted and a tapered surface 86C surrounding the hole, and the tapered surface 86C may support the protrusion 87C with a portion of the tip inserted into the hole. Furthermore, the center 86B of the recess 86A does not have to be located on the spindle 11 of the spindle device 23. The motor of the present disclosure is not limited to the servo motor 93, but may be another motor such as a stepping motor.

[0053] In addition, in the above embodiment, the axial direction of the rod portion 87B of the core bar 87 is the direction along the main shaft 11 when the workpiece W is not clamped, but this is not limited to this. For example, the axial direction of the rod portion 87B and the main shaft 11 may be misaligned in the X-axis direction or the Y-axis direction. Furthermore, although the direction in which the tailstock device 25 is moved is along the main shaft 11, the present invention is not limited to this. The direction in which the tailstock device 25 is moved may be a direction that forms a predetermined angle with the main shaft 11 and that approaches the main shaft device 23. Alternatively, the direction in which the tailstock device 25 is moved may be a direction that is parallel to the main shaft 11 and that is offset from the main shaft 11 in the X-axis direction and the Y-axis direction. In the above embodiment, a hydraulic cylinder is used as the fluid pressure cylinder of the present disclosure, but this is not limited thereto. The fluid pressure cylinder of the present disclosure may be a cylinder that uses other fluids, such as an air cylinder. Furthermore, the drive source for the core stock moving device 27 to push the mandrel 87 and the drive source for the spindle device 23 to retract the mandrel 87 are not limited to hydraulic cylinders and may be other drive sources, such as actuators. In the above embodiment, the control device 37 drives the tailstock hydraulic cylinder 95 (FIG. 7) and then the spindle hydraulic cylinder 45 (FIG. 8), but this is not limited to this. The control device 37 may drive the tailstock hydraulic cylinder 95 and the spindle hydraulic cylinder 45 simultaneously, or may drive the spindle hydraulic cylinder 45 before the tailstock hydraulic cylinder 95. Furthermore, although the control device 37 maintained the hydraulic pressure of the tailstock hydraulic cylinder 95 at a predetermined pressure during the retraction operation in which the spindle hydraulic cylinder 45 was driven, it may, for example, be increased to push the cylinder further without maintaining the hydraulic pressure. Similarly, the control device 37 stopped the servo motor 93 during the retraction operation in which the spindle hydraulic cylinder 45 was driven, but it may also be possible to change the rotational position of the servo motor 93 and perform pushing by the servo motor 93. Furthermore, the control device 37 may change the rotational position of the servo motor 93 during the pushing operation of the tailstock hydraulic cylinder 95. [Explanation of symbols]

[0054] 10 Hob module (hobbing machine), 23 Spindle device (work clamping device), 25 Core pusher position, 27 tailstock moving device (moving device, work clamping device), 29 hob, 37 control device, 45 spindle hydraulic cylinder (retraction device), 63 stopper, 65 shaft (retraction device), 67 block (retraction device), 73 insertion hole, 77 collet, 85 float mechanism, 86 support member, 86A recess, 87 core bar, 87A base, 87B rod portion, 87C convex portion, 87D tapered surface, 87E through hole, 88 threaded member, 88A tip portion, 88B head portion, 89 pusher mounting member, 91 pusher, 93 servo motor (motor), 95 tailstock hydraulic cylinder (fluid pressure cylinder), 105 gap, 109 abutment member, 111 elastic member, W work.

Claims

1. a core support device including a core bar, a pusher attached to the core bar, and a float mechanism that tiltably holds the core bar; a spindle device having a backing plate for seating a workpiece, an insertion hole into which the core bar is inserted, and a retraction device for retracting the core bar inserted into the insertion hole to the inner side of the insertion hole; a moving device that moves the tailstock device in a direction parallel to the main shaft of the main spindle device; Equipped with The moving device is moving the tailstock device in a direction approaching the spindle device; The retraction device is The core metal is pulled in, and the workpiece is sandwiched between the pusher and the backing metal. The float mechanism is A work clamping device that holds the core bar while allowing the core bar to tilt in a direction parallel to the main shaft during the retraction operation by the retraction device.

2. The core metal has A curved surface is formed, The float mechanism is a support member having a tapered surface inclined at a predetermined angle, the tapered surface being in contact with the curved surface of the core, and supporting the core; a screw member that is inserted into a through hole provided in the core metal, has a tip portion that is screwed into the support member, and is disposed with a gap between a head portion and the core metal in a screwed state; The workpiece clamping device according to claim 1 , further comprising:

3. The core metal is a convex portion having the curved surface formed thereon, The support member is a recess into which the protrusion is inserted, the tapered surface being provided on an inner peripheral surface of the recess, and the tapered surface being brought into contact with the curved surface to support the core bar when the protrusion is inserted into the recess, The center of the recess is The workpiece clamping device according to claim 2 , which is disposed on the main spindle of the main spindle device.

4. The spindle device is a collet that is provided on the outer periphery of the backing metal, that holds the workpiece when opened, and that releases the hold of the workpiece when closed; The collet is The insertion hole is provided at an upper end thereof, and the insertion hole is provided at a position corresponding to the upper center of the abutment. The core metal is a base portion held by the float mechanism; a rod portion extending in one direction from the base portion; and The tailstock device is a pusher attachment member attached to the base side of the rod portion and configured to hold the pusher relative to the core metal; The pusher mounting member is An elastic member; a contact member that is biased by the elastic member when it comes into contact with the collet and pushes the collet open; The workpiece clamping device according to any one of claims 1 to 3, further comprising:

5. Further provided is a control device for controlling the retraction device and the movement device, The moving device is A motor is provided. The control device 5. A work clamping device as described in claim 4, wherein the motor is controlled to stop the core support device at a position where the work seated on the retaining member and the pusher are separated and the abutment member contacts the collet to push open the collet.

6. The moving device is A fluid pressure cylinder is provided. The control device After the collet is pushed open by the abutment member, the fluid pressure cylinder is controlled to urge the tailstock device in a direction approaching the spindle device, and the pusher is brought into contact with the workpiece, thereby sandwiching the workpiece between the pusher and the abutment.

6. The work clamping device according to claim 5, wherein the fluid pressure cylinder is controlled to clamp the work between the pusher and the abutment, and then the retracting device is driven to retract the core metal into the inner side of the insertion hole.

7. The control device The fluid pressure cylinder is controlled to bias the tailstock device with a predetermined fluid pressure, and the workpiece is sandwiched between the pusher and the backing metal.

7. The workpiece clamping device according to claim 6, wherein the retraction operation by the retraction device is performed while maintaining the fluid pressure of the fluid pressure cylinder at the predetermined fluid pressure.

8. The work clamping device according to any one of claims 1 to 7, a hob having a cutting edge on its outer periphery, which rotates to bring the cutting edge into contact with the work clamped by the work clamping device when the core pushing device is retracted by the retraction device, and performs machining; A hobbing machine equipped with

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