Tool base and machine tool

Abstract

When a tool that does not rotate is mounted on a tool base capable of rotating the tool via a wheel train having backlash and is used with the tool being stopped, the present invention, in order to prevent rattling due to the backlash of the tool without having a complicated structure, comprises: a spindle (33) that detachably holds a cutting tool (85) in the direction of an axis (C3); a gear wheel train (33) that transmits rotation to the held cutting tool (85); a draw bar (34) that moves the cutting tool (85) in the direction of the axis (C3); and a piston (36) that is movably provided in the direction of the axis (C3), between the rearmost position and the front-most position. Couplings (protruding and recessed shapes (36c, 34c)) that integrally rotate in the contacted state are formed at the piston (36) and the draw bar (34). The piston (36) is stopped at an intermediate position between the rearmost position and the front-most position.

Description

Tool benches and machine tools

[0001] The present invention relates to a tool rest and a machine tool equipped with the tool rest.

[0002] A tool table is known in which a tool holder that detachably holds a rotary tool that rotates to machine a workpiece is rotatably provided, and the tool holder to which the rotary tool is attached is rotated to machine a specified workpiece with the rotary tool, and a machine tool equipped with this tool table is also known.

[0003] This machine tool has a draw bar on the tool table as an attachment / detachment operating means for attaching / detaching a rotary tool, which is integral with the tool holding part in the rotational direction and can move back and forth in the direction of the rotation axis, and a piston as an operation driving means for driving the draw bar back and forth.By pressing and moving the draw bar with the piston, it is possible to remove the rotary tool from the tool holding part and replace the tool (see, for example, Patent Document 1).

[0004] Japanese Patent Application Publication No. 7-040104

[0005] In this machine tool, there are cases where it is necessary to restrict the rotation of the tool holding unit and fix the rotational position of the tool on the tool mounting unit. For example, when a fixed tool such as a cutting tool is mounted on the tool holding unit instead of the rotating tool and contour machining or boring is performed on a rotating workpiece using the fixed tool without rotating the fixed tool, the rotating tool may be held while maintaining its phase. However, there is a problem in that it is not easy to fix the rotational position of the tool on the tool mounting unit.

[0006] The present invention has been made in consideration of the above circumstances, and has as its object to provide a tool rest that can prevent, with a simple structure, misalignment in the rotational direction of a tool held in a tool holding portion, and a machine tool equipped with this tool rest.

[0007] A first aspect of the present invention is a tool stand comprising: a tool holding section that detachably holds a tool for machining a workpiece and that is rotatable around the axis of the tool; an attachment / detachment operation means for the tool that is integral with the tool holding section in the direction of rotation about the axis and that is movable back and forth in the axial direction of the tool; and an operation drive means that drives the attachment / detachment operation means to move back and forth, wherein the tool holding section to which the tool is attached is rotated to machine the workpiece with the tool, and the operation drive means presses the attachment / detachment operation means to move it in the axial direction, thereby allowing the tool to be removed from the tool holding section, and a position is provided within the movement range of the operation drive means where the operation drive means abuts against the attachment / detachment operation means to restrict rotation of the attachment / detachment operation means.

[0008] A second aspect of the present invention is a machine tool comprising a spindle that grips a workpiece, a tool table according to the present invention, and a control unit that controls each operation of the spindle and the tool table, wherein the control unit stops the operation drive means at a position away from the attachment / detachment operation means, a position where the attachment / detachment operation means allows the tool to be attached or detached, and a position where the operation drive means abuts against the attachment / detachment operation means to restrict rotation of the attachment / detachment operation means.

[0009] The tool rest and machine tool equipped with the tool rest according to the present invention can easily restrict rotation of the tool mounting unit and fix the tool mounting unit without complicating the structure by positioning the operating drive means in contact with the mounting / detaching operating means so as to position the mounting / detaching operating means at a position where the tool is maintained. This makes it possible to prevent misalignment of the tool in the rotational direction and prevent a decrease in machining accuracy when, for example, the tool is stopped to machine a workpiece, and also makes it possible to maintain the rotational phase of the tool that rotates to perform machining as needed.

[0010] 1 is a schematic perspective view of an automatic lathe; 2 is a perspective view of the interior of the automatic lathe as seen from the machining chamber side; 3 is a cross-sectional view of the tool spindle taken along a vertical plane including axis C3, showing the state in which the piston is at its most forward position; 4 is a partial detailed view showing details of part A in FIG. 5A; 5 is a cross-sectional view of the tool spindle taken along a vertical plane including axis C3, showing the state in which the piston is at its most forward position; 6 is a partial detailed view showing details of part A in FIG. 4A; 7 is a cross-sectional view of the tool spindle taken along a vertical plane including axis C3, showing the state in which the piston is at its most rearward position; 8 is a partial detailed view showing details of part A in FIG. 3A; 9 is a cross-sectional view of the vertical plane taken along line B-B in FIGS. 3A, 4A, and 5A; 10 is a cross-sectional view of the vertical plane taken along line CC in FIGS. 3A, 4A, and 5A; 11 is a perspective view schematically showing the concave-convex shape formed on the front surface of the piston; 12 is a side view schematically showing the concave-convex shape of the piston and the concave-convex shape of the draw bar, showing the state in which the front surface of the piston and the rear end surface of the draw bar are separated. FIG. 1 is a side view schematically illustrating the concave-convex shape of the piston and the concave-convex shape of the draw bar, showing a state in which the front surface of the piston and the rear end surface of the draw bar are in contact with each other and the concave-convex shape of the piston and the concave-convex shape of the draw bar are meshed with each other.

[0011] An automatic lathe 100 shown in Fig. 1 is one embodiment of a machine tool according to the present invention. As shown in Fig. 2, the automatic lathe 100 includes, inside a cover, a spindle 10, a gang tool rest 20, and a tool spindle 30, which is an example of a tool rest according to the present invention.

[0012] In the automatic lathe 100 , a control unit 80 housed in a cover below the operation panel 90 controls the operations of the spindle 10 , the gang tool rest 20 and the tool spindle 30 based on the operation of the operation panel 90 .

[0013] The main shaft 10 is supported so as to be movable in the z-axis direction parallel to the axis, and is driven to rotate around an axis C1.

[0014] A guide bush 55 is provided on a guide bush support base 51 arranged in front of the spindle 10 , and the tip side of the workpiece held by the spindle 10 protrudes from the guide bush 55 into the machining chamber 50 .

[0015] The gang tool rest 20 and the tool spindle 30 are disposed in a machining chamber 50. The gang tool rest 20 supports a plurality of tools 21, 22, . . . , 25.

[0016] The automatic lathe 100 selects one of the tools 21, ..., 25 to be used for machining by moving the gang tool rest 20 along the y-axis perpendicular to the z-axis. The selected tool 21, ..., 25 turns the workpiece by moving the gang tool rest 20 along the x-axis perpendicular to the z-axis and y-axis.

[0017] 3A, a rotary tool 86 and a cutting tool 85 integrally mounted in a holder are mounted on the tool spindle 30. The rotary tool 86 is detachably inserted into a tool drive shaft that is rotatably supported on the main body of the tool spindle 30. The cutting tool 85 is detachably mounted on a spindle 33 that is rotatably supported about an axis C3 below the tool drive shaft.

[0018] By moving the tool spindle 30 along the x-axis, it is possible to select a cutting tool 85 or a rotary tool 86 as the tool to be used for machining the workpiece. By moving the tool spindle 30 along the y-axis, it is possible to machine the workpiece with the selected cutting tool 85 or rotary tool 86.

[0019] The tool spindle 30 is rotatable about an axis C2 parallel to the x-axis, and the cutting tool 85 or the rotary tool 86 can be tilted relative to the y-axis to machine the workpiece.

[0020] The control unit 80 controls the movement of the tool spindle 30 along the x-axis, the movement along the y-axis, the rotation about the axis C2, and the rotation of the cutting tool 85 and the rotary tool 86 about the axis C3.

[0021] 3A, 4A, and 5A, the tool spindle 30 has a bevel gear 32a1 inserted into it through an opening 31 at its upper end. The bevel gear 32a1 engages with a drive gear (not shown), and the gear 32b is rotationally driven via a spur gear 32a2. The gear 32b engages with a gear 32c that is integrally provided on the tool drive shaft, and the gear 32c engages with a gear 32e via a gear (not shown), so that the rotational drive force of the gear 32b is transmitted in sequence from the gear 32c to the gear 32e.

[0022] The tool drive shaft is rotated by the rotational driving force transmitted to the gear 32c, thereby rotating the rotary tool 86. The gear 32e is integrally mounted on the spindle 33 (an example of a tool holding portion).

[0023] The spindle 33 is a tool holder that holds the cutting tool 85 so that it can be attached / detached along the axis C3 and can rotate freely around the axis C3. The cutting tool 85 is configured such that a tool body 85a is integrally held in a holder 85b by a collet chuck. A pull stud 85d is integrally provided with the holder 85b, and the pull stud 85d protrudes from the opposite side of the tool body 85a.

[0024] The holder 85b is formed in a conical shape. The spindle 33 has a tapered hole formed inside. When the holder 85b is inserted into the hole of the spindle 33, the inclined surface 85c of the holder 85b comes into contact with and tightly adheres to the inner circumferential surface 33a of the hole, and the cutting tool 85 is attached to the spindle 33.

[0025] The hole of the spindle 33 has a tapered inner circumferential surface 33a, and a recessed groove 33b having an inner diameter larger than the minimum inner diameter of the taper formed around the entire circumference. Further inside the hole of the spindle 33 than the recessed groove 33b, a ball pressing portion 33c is formed as an inner circumferential surface having an inner diameter smaller than the inner diameter of the recessed groove 33b.

[0026] The drawbar 34 (an example of an attachment / detachment operating means) is disposed inside the spindle 33 so as to be movable (freely advance and retreat) along the axis C3. The front end of the drawbar 34 is provided with a plurality of balls 34a that engage from the outside with pull studs 85d provided on the holder 85b. A coil spring 35 is provided on the outside of the drawbar 34.

[0027] The coil spring 35 is provided between a stopper integrally provided at the rear end of the draw bar 34 and a step formed in the hole of the spindle 33. The draw bar 34 is biased rearward by the coil spring 35. The draw bar 34 hits a stopper 33d formed on the spindle 33, thereby restricting rearward movement beyond a certain distance.

[0028] When the ball 34a of the drawbar 34 is positioned opposite the recessed groove 33b of the spindle 33 against the biasing force of the coil spring 35, as shown in FIG. 3A, the ball 34a escapes from the inside of the front end of the drawbar 34 to the radially outer recessed groove 33b, allowing the pull stud 85d to be attached to and detached from the inside of the front end of the drawbar 34.

[0029] With the ball 34a escaping from the inside of the front end of the draw bar 34 to the radially outer recessed groove 33b, the holder 85b is inserted into the hole in the spindle 33, and when the cutting tool 85 is attached to the spindle 33, the pull stud 85d is inserted into the inside of the front end of the draw bar 34.

[0030] When cutting tool 85 is attached to spindle 33 and draw bar 34 is moved rearward by the bias of coil spring 35, ball 34a of draw bar 34 moves from a position facing recessed groove 33b to a position facing ball pressing portion 33c. Ball 34a is pressed radially inward by ball pressing portion 33c, with a portion of ball 34a protruding inside the front end of draw bar 34 and engaging with pull stud 85d. Holder 85b of cutting tool 85 is held integrally with spindle 33, and cutting tool 85 becomes rotatable integrally with spindle 33.

[0031] As shown in Figure 6, the splines 34s of the draw bar 34 mesh with the splines 34s on the inner surface of the spindle 33, allowing the draw bar 34 to move along the axis C3 relative to the spindle 33 while restricting its rotation around the axis C3.

[0032] A cylinder 38 is formed on the outer periphery of the rear of the spindle 33 in the main body of the tool spindle 30. A piston 36 (an example of an operating drive means) is provided within the cylinder 38 so as to be able to move forward and backward along the axis C3. A rod portion 36b of the piston 36 protruding rearward is passed through a through-hole formed in a seal receiving member 37 of the main body of the tool spindle 30, and the piston 36 moves forward (forward) and backward (rearward) along the axis C3. The piston 36 drives the draw bar 34 to move forward and backward.

[0033] 7, the rod portion 36b has an outer peripheral surface 36s formed with a hexagonal cross-sectional contour, and the through hole of the seal receiving member 37 is formed as a hexagonal hole having an inner peripheral surface 37s with a hexagonal cross-sectional contour corresponding to the hexagonal cross-sectional contour of the rod portion 36b. The rod portion 36b is movable along an axis C3 relative to the seal receiving member 37, but its rotation about the axis C3 is restricted. The piston 36 moves while its rotation about the axis C3 is restricted.

[0034] The piston 36 can be moved forward by supplying a working fluid such as air to the compartment within the cylinder 38 to the left of the piston 36 as shown in the figure under the control of the control unit 80, and the piston 36 can be moved backward by supplying a working fluid such as air to the compartment within the cylinder 38 to the right of the piston 36 as shown in the figure under the control of the control unit 80.

[0035] The piston 36 is movable within a range between the rearmost position shown in Figures 5A and 5B, where it is the most rearward position, and the forwardmost position shown in Figures 3A and 3B, where it is the most forward position, under the control of the control unit 80. The piston 36 is also controlled by the control unit 80 so as to stop at a predetermined intermediate position (position) shown in Figures 4A and 4B within the range of movement between the rearmost position and the forwardmost position.

[0036] When the piston 36 is disposed at its rearmost position, the front surface 36a is spaced rearward from the rear end surface 34b of the draw bar 34. When the piston 36 is at its rearmost position, the cutting tool 85 is held on the spindle 33 by the draw bar 34, and the cutting tool 85 can be rotated or stopped by the spindle 33.

[0037] As shown in Fig. 8, a concave-convex shape 36c is formed on a front surface 36a of the piston 36 facing the rear end surface 34b of the draw bar 34, in which concave and convex portions each extend radially from the axis C3 as a center, and these concave and convex portions alternate at equal intervals along the circumferential direction around the axis C3. As shown in Figs. 9A and 9B, a concave-convex shape 34c corresponding to the concave-convex shape 36c is formed on the rear end surface 34b of the draw bar 34 facing the front surface 36a of the piston 36.

[0038] The concave-convex shape 36c of the piston 36 and the concave-convex shape 34c of the draw bar 34 can engage with each other.

[0039] When the piston 36 advances from the rearmost position shown in FIGS. 5A and 5B to the intermediate position shown in FIGS. 4A and 4B, the front surface 36a of the piston 36 and the rear end surface 34b of the draw bar 34 come into contact with each other, and the concave-convex shape 36c and the concave-convex shape 34c shown in FIG. 9B are coupled together.

[0040] The concave-convex shape 36c and the concave-convex shape 34c of the draw bar 34 engage with each other, so that the piston 36 and the draw bar 34 become one unit around the axis C3. At the intermediate position, the piston 36 does not press the draw bar 34 to move it in the direction of the axis C3, and the draw bar 34 stops without moving forward or backward relative to the spindle 33. The spindle 33 continues to hold the cutting tool 85, and the position of the cutting tool 85 in the rotational direction is maintained.

[0041] It should be noted that the piston 36 may be in an intermediate position and push the draw bar 34 to move it within a range in which the spindle 33 maintains the holding of the cutting tool 85 .

[0042] The control unit 80 controls the piston 36 to move forward and stop it at the forwardmost position, causing the piston 36 to press the draw bar 34 and move the draw bar 34 to a position that allows the pull stud 85d to be attached and detached, thereby attaching and detaching the holder 85b to and from the spindle 33 and detaching the cutting tool 85.

[0043] Furthermore, when the automatic lathe 100 processes a workpiece rotating around the axis C1 while the cutting tool 85 is stopped and not rotating, the control unit 80 stops the driving source such as a motor that drives the gear train 32 to rotate, or prevents the rotation from being transmitted to a driving gear (not shown) connected to the gear train 32.

[0044] Even when the transmission of driving force to the drive gear is stopped so as to stop the rotational drive of the spindle 33, misalignment in the rotational direction that may occur due to backlash between the connected gears 32a, 32b, 32c, and 32e is prevented by moving the piston 36 to the intermediate position, and the cutting tool 85 is fixed while being prevented from misalignment in the rotational direction.

[0045] For example, when a fixed tool such as a cutting tool bit that processes a workpiece without rotating is attached to the tool body 85a of the cutting tool 85 and a workpiece that is rotating around the axis C1 is processed, the cutting edge of the tool body 85a is prevented from shifting from a pre-set position due to friction with the rotating workpiece, or vibrations known as chattering are prevented from occurring due to fluctuations in friction, and it is possible to prevent a decrease in processing accuracy when boring the workpiece or processing the outer surface of the workpiece.

[0046] As described above in detail, the automatic lathe 100 of this embodiment has a simple structure in which, when a fixed tool is attached to the tool spindle 30 as the tool body 85a and the spindle 33 is stopped for use, the front surface 36a of the piston 36 is brought into contact with the rear end surface 34b of the draw bar 34, and with the control unit 80 simply controlling the stopping of the piston 36 at a predetermined position (intermediate position) set within a range between the rearmost position and the frontmost position, it is possible to prevent the tool body 85a from shifting in the rotational direction and to prevent the cutting edge of the tool body 85a from moving.

[0047] It is also possible to form concave-convex shapes 36c, 34c that serve as a coupling on the front surface 36a of the piston 36 and the rear end surface 34b of the draw bar 34, and to engage the concave-convex shapes 36c, 34c so that the front surface 36a of the piston 36 and the rear end surface 34b of the draw bar 34 come into contact with each other.

[0048] Instead of forming the uneven shapes 36c, 34c on the front surface 36a of the piston 36 and the rear end surface 34b of the draw bar 34, respectively, the front surface 36a of the piston 36 and the rear end surface 34b of the draw bar 34 may be formed to have a high coefficient of friction or a member with a high coefficient of friction may be provided so that the front surface 36a of the piston 36 and the rear end surface 34b of the draw bar 34 come into contact with each other in a state of high friction. CROSS-REFERENCE TO RELATED APPLICATIONS

[0049] This application claims priority based on Japanese Patent Application No. 2023-207519, filed with the Japan Patent Office on December 8, 2023, the entire disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A tool table comprising: a tool holding section for removably holding a tool for machining a workpiece, the tool being rotatable about the axis of the tool; an attachment / detachment operation means for the tool, which is integral with the tool holding section in the direction of rotation about the axis and which is capable of moving forward and backward in the axial direction of the tool; and an operation drive means for driving the attachment / detachment operation means forward and backward, wherein the tool can be removed from the tool holding section by rotating the tool holding section to machine the workpiece with the tool and by pressing the attachment / detachment operation means with the operation drive means to move it in the axial direction, and wherein a position is provided within the movement range of the operation drive means where the operation drive means abuts against the attachment / detachment operation means to restrict the rotation of the attachment / detachment operation means.

2. A tool stand as described in claim 1, wherein the surfaces where the operating drive means and the attachment / detachment operating means come into contact with each other are each formed with a concave-convex shape that interlocks with the operating drive means and the attachment / detachment operating means when they come into contact with each other.

3. A tool stand as described in claim 2, wherein the concave and convex shapes are such that the concave and convex parts each extend radially from the axis of the operating drive means and the attachment / detachment operating means as a center, and the concave and convex parts are repeated alternately at equal intervals along the circumferential direction around the axis.

4. A tool table as described in claim 1, wherein the cross-sectional contour shape of the outer peripheral surface of the rod portion of the operating drive means and the cross-sectional contour shape of the inner peripheral surface of a seal receiving member through which the rod portion passes are formed in a shape that allows the operating drive means to move along the axial direction but prevents the operating drive means from rotating around the axis.

5. A machine tool comprising: a spindle for gripping a workpiece; a tool table as described in any one of claims 1 to 4; and a control unit for controlling each operation of the spindle and the tool table, wherein the control unit stops the operation drive means at a position away from the attachment / detachment operation means, a position at which the attachment / detachment operation means enables the tool to be attached or detached, and a position at which the operation drive means abuts against the attachment / detachment operation means to restrict rotation of the attachment / detachment operation means.

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