JPH0563701U - Spindle device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent radial vibration of the draw bar that pulls the clamp mechanism when the spindle rotates at high speed. [Structure] The drawbar 30 is attached to the axis of the hollow spindle 21.
Has been inserted. A large number of disc springs 33 are inserted around the draw bar 30. A thrust ball bearing 36 is press-fitted between the outer periphery of the intermediate portion of the draw bar 30 and the inner periphery 21d of the spindle so as to be axially rollable. [Effect] The surfaces of the thrust ball bearings 36, 37 and the outer periphery of the draw bar 30 and the inner periphery of the spindle 21d are in close contact with each other without a minute gap, so that the spindle 2
Even when 1 rotates at a high speed, the intermediate portion of the laminated disc springs 33 does not bend, and it is possible to prevent vibration in the radial direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improved spindle device for suppressing radial vibration of a draw bar that pulls a clamp mechanism when a spindle rotates at high speed.

[0002]

[Prior Art]

 As a conventional spindle device, there is one having a structure as shown in FIG. A spindle 1 is rotatably supported on a shaft center of a housing 15 provided on a base (not shown) of a machine tool via bearings 2-5. A taper hole 1b into which a tool 6 is inserted is formed at the tip end 1a of the spindle 1, and a clamp mechanism 7 for detachably holding the tool 6 is provided inside the taper hole 1b. A drawbar 10 is inserted through the shaft center of the spindle 1, and the drawbar 10 is urged to the right in the figure by a disc spring (a part of which is not shown) 11 which is inserted in the outer periphery of the drawbar 10. The collet chuck 8 connected to the front end of the drawbar 10 (the left side in the drawing is the front) is pulled backward by the repulsive force of the plate spring, so that the collet chuck 8 grips the pull stud 9 of the tool 6. In this state, the tool 6 is pulled rearward, whereby the tool 6 is closely held in the tapered hole 1b. When the tool 6 is removed, the piston 13 of the hydraulic cylinder 12 is projected and the rear end 10a of the drawbar 10 is pushed forward, so that the collet chuck 8 opens while moving forward to open the pull stud 9. Can be removed. In the conventional spindle device, one sleeve 14 is provided at the intermediate portion of the drawbar 10 in order to prevent the intermediate portion of the Belleville springs 11 stacked upon rotation of the spindle 1 from being displaced in the radial direction and vibrating. It had been inserted more than once.

[0003]

[Problems to be solved by the device]

 However, in the above conventional example, the drawbar 10 is allowed to move back and forth in the axial direction along with the attachment / detachment operation of the tool 6 between the inner circumference of the sleeve 14 and the outer circumference of the drawbar 10. Is also provided between the outer circumference of the sleeve 14 and the inner circumference of the spindle 1 so as to allow the sleeve 14 to slide in the axial direction. Therefore, when the spindle 1 rotates, especially when rotating at a high speed, the intermediate portion of the disc spring 11 stacked with the sleeve 14 by the amount of the minute gap is displaced in the radial direction and vibrates, which lowers the machining accuracy. There is something to invite.

[0004]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, a spindle device of the present invention includes a hollow spindle rotatably supported in a housing provided in a base of a machine tool, and a spindle provided in a front end portion of the spindle to mount a tool. A clamp mechanism that detachably engages and holds, a drawbar that is connected to the clamp mechanism and that is inserted into the spindle, and a large number of inserts on the outer periphery of the drawbar, and urges the drawbar in a direction to pull the clamp mechanism. A disc spring, the tool is engaged with and held by the clamp mechanism by pulling the clamp mechanism by the draw bar, and the tool is released from the clamp mechanism by pushing the draw bar against the repulsive force of the disc spring. In the spindle device configured as above, the thrust ball bearing is rolled between the outer circumference of the intermediate part of the drawbar and the inner circumference of the spindle. Pressed into ability and is characterized in that a said disc springs on both sides of the thrust ball bearing.

[0005]

[Action]

 Since the thrust ball bearing is formed by arranging spheres in the circumferential direction, it can be rolled in the axial direction of the drawbar, and the sleeve 13 and the sleeve 13 in the above-described conventional example that allow smooth forward and backward movement of the drawbar and eliminate the bias of the disc spring. It has the same effect. In addition, the thrust ball bearing is press-fitted with a small interference between the outer periphery of the intermediate part of the drawbar and the spindle, so that the thrust ball bearing surface and the outer periphery of the drawbar as well as the inner periphery of the spindle. Is in close contact with. As a result, even when the spindle rotates at high speed, the central part of the stacked disc springs is supported by the thrust ball bearings so as not to bend, so that the disc springs can be prevented from vibrating in the radial direction. ..

[0006]

【Example】

 An embodiment of a spindle device according to the present invention will be described below with reference to the drawings. A hollow spindle 21 is rotatably supported by bearings 22 to 25 on the shaft center of a housing 20 provided on a base (not shown) of a machine tool. The spindle 21 is rotated by a built-in motor (not shown) arranged on the outer periphery of the central portion 21c of the spindle 21, and rotates the tool 26 engaged and held by the tip portion 21a of the spindle 21.

A taper hole 21b into which a tool 26 is fitted is formed at the tip end 21a of the spindle 21, and a clamp mechanism 27 that detachably holds the tool 26 is provided inside the taper hole 21b. ing. The clamp mechanism 27 uses a collet chuck 28. A draw bar 30 is inserted through the shaft center of the spindle 21, a front end of the draw bar 30 (the left side in the drawing is the front) is connected to a collet chuck 28, and a rear end 30 a thereof projects from the rear end of the spindle 21. ing. A cylindrical disc spring retainer 31 is screwed onto the rear end 30a of the draw bar 30, and the disc spring retainer 31 is slidable within the inner circumference 21d of the spindle 21. Further, a cylindrical disc spring receiver 32, which comes into contact with a step portion 21f in the spindle 21 formed at the rear of the clamp mechanism 27, is slidably inserted in the front portion of the draw bar 30. The disc spring receiver 32 can also slide on the inner circumference 21 of the spindle 21. A large number of disc springs (intermediate portion not shown) 33 are inserted between the disc spring retainer 31 and the disc spring receiver 32. These disc springs 33 are formed by stacking three umbrella-shaped disc springs as a set, and are arranged so that the opening directions of the disc springs of an adjacent set are opposite to each other. By screwing the disc spring retainer 31 into the drawbar 30, the disc spring 33 is compressed between the disc spring retainer 31 and the disc spring receiver 32. Therefore, the disc spring 33 pushes the disc spring retainer 31 rearward by the repulsive force, and the drawbar 30 with which the disc spring retainer 31 is screwed is also biased rearward.

When the draw bar 30 is pulled backward, the collet chuck 28 is pulled backward, and the cam 21 e formed on the inner circumference of the spindle 21 and the projection 28 a formed on the outer circumference of the collet chuck 28 are disengaged from each other. Since the collet chuck 28 is closed, the pull stud 29 at the rear end of the tool 26 is gripped by the collet chuck 28 and closely held in the tapered hole 21b. When the tool 26 is removed, the piston 42 projects by supplying hydraulic pressure to the hydraulic cylinder 41 from a hydraulic pump (not shown), and the piston 42 pushes the rear end 30a of the draw bar 30 forward. As a result, the drawer 30 moves forward against the repulsive force of the disc spring 33, and the cam 21e engages with the projection 28a while the collet chuck 28 moves forward as shown by the imaginary line in the figure, and opens. Open the pull stud 29. Therefore, the tool 26 can be extracted from the clamp mechanism 27.

Further, a thrust ball bearing 36 is rotatably press-fitted between the outer periphery of the intermediate portion of the draw bar 30 and the inner periphery 21d of the spindle. The thrust ball bearing 36 has a plurality of spheres 37 having a diameter that is extremely smaller than the distance between the outer circumference of the drawbar 30 and the inner circumference 21d of the spindle, arranged in a row around the drawbar 30 and arranged in two rows in the axial direction of the drawbar 30. It is a thing. Further, the thrust ball bearing 36 is provided with an annular retainer 38 which has a hole into which the sphere 37 is fitted and is positioned and which contacts the surface of the sphere with a smooth surface to fill the gap between the spheres. Further, the thrust ball bearing 36 is provided with flat plate annular collars 34, 35 interposed between the retainer 38 and the disc spring 33.

Since the ball bearing 36 is press-fitted between the drawbar 30 and the spindle inner circumference 21d with an appropriate tightening margin (for example, several μm), the surface of the thrust ball bearing 36 and the outer circumference of the drawbar 30 are separated from each other. There is no gap between the space and the inner circumference 21d of the spindle. Therefore, the draw bar 30 does not even have a slight bending at least in the portion supported by the thrust ball bearing 36. Further, since the intermediate portion of the laminated disc springs 33 is also supported by the spindle 21 via the collars 34, 35, the retainer 38, and the spherical body 37, the disc springs 33 do not bend. As a result, even when the spindle 21 rotates at a high speed, the laminated disc springs 33 can be prevented from vibrating in the radial direction.

Further, when the draw bar 30 moves forward and backward in the axial direction when the tool 26 is attached and detached, the thrust ball bearings 36 and 37 roll in the axial direction to allow the forward and backward movement of the draw bar 30. Further, when the compression density of the disc spring 33 is biased, the thrust ball bearings 36 and 37 are pressed from the side having a large compression reaction force to a position where the compression density of the disc spring 33 becomes uniform. As a result, the bias of the disc spring 33 can be eliminated.

It should be noted that the thrust ball bearing may be installed at any position where the middle part of the drawbar 30 needs to be prevented from bending, and the number of the seated ball bearings is not limited. Further, the clamp mechanism 27 may be other than the one having the collet chuck 28, and the present invention can be applied as long as the tool 26 can be grasped and released by moving the draw bar 30 forward and backward.

[0013]

[Effect of the device]

 As described in detail above, in the spindle device of the present invention, the thrust ball bearing is rotatably press-fitted between the outer periphery of the intermediate portion of the drawbar and the inner periphery of the spindle, so that the surface of the thrust ball bearing and the drawbar bearing are By eliminating the minute gaps between the outer circumference and the inner circumference of the spindle, it is possible to prevent the middle part of the laminated disc springs from bending in the radial direction, which allows the laminated discs to rotate even when the spindle rotates at high speed. The spring does not vibrate in the radial direction. Therefore, the spindle device of the present invention enables the spindle to rotate at high speed, and even when the spindle rotates at high speed, the machining accuracy does not deteriorate due to the radial vibration of the laminated disc springs. High-precision machining is possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a spindle device according to the present invention.

FIG. 2 is a sectional view of an example of a conventional spindle device.

[Explanation of symbols]

20 ... Housing 21 ... Spindle 26 ... Tool 27 ... Clamping mechanism 30 ... Drawbar 33 ... Disc spring 36 ... Thrust ball bearing

Claims (1)

[Scope of utility model registration request] 1. A hollow spindle rotatably supported in a housing provided in a base of a machine tool, and a clamp mechanism provided in a tip portion of the spindle for detachably engaging and holding a tool. The draw mechanism includes a drawbar connected to the clamp mechanism and inserted into the spindle, and a large number of disc springs inserted through the outer periphery of the drawbar and biasing the drawbar in a direction to pull the clamp mechanism. By holding the tool in engagement with the clamp mechanism by pulling the drawbar, and pushing the drawbar against the repulsive force of the disc spring to separate the tool from the clamp mechanism. The thrust ball bearing is press-fitted between the outer circumference of the part and the inner circumference of the spindle so that it can roll. Spindle device being characterized in that arranging the disc springs on both sides of the.