JPH0976106A - Finger chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the life of a cam mechanism and to shorten the axial dimension of a chuck. SOLUTION: A spider 9 is driven by a draw screw 8, a drawbar 16 is turned and slid through a cam mechanism 26, and a work W is grasped by a finger jaw 18. The cam mechanism 26 is constituted of a twisted cam surface 27 provided on the drawbar 16, and a cam pin 28 provided on the spider 9. A fitting hole 9a to which the drawbar 16 is to be fitted is formed on the spider 9, and a supporting hole 9b for supporting the cam pin 28 is so provided as to traverse the edge of the fitting hole 9a. The cam pin 28 is brought in linear-contact with the cam surface 27a at the overlapping part of the supporting hole 9b to the fitting hole 9a, and it is supported by the spider 9 on both sides of the line contact part in the both ends supporting state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finger chuck in which a draw bar is rotated and slid by a spider via a cam mechanism to grip a work by finger jaws, and more particularly to an improved technique of the cam mechanism. .

[0002]

2. Description of the Related Art In a conventional finger chuck,
As shown in FIG. 3, a draw screw 32 is provided at the center of the chuck body 31 so as to be slidable in the chuck axial direction, and a spider 33 is supported on the draw screw 32. A plurality of draw bars 34 are rotatably and slidably supported on the outer peripheral portion of the chuck body 311 via a sleeve 35, a finger jaw 36 is attached to the front end thereof, and a rear end portion thereof is connected via a cam mechanism 37. Is connected to the spider 33. The draw bar 34 is biased forward by a spring 45, and an abutting portion 34 a provided on the outer periphery of the draw bar 34 is brought into contact with the sleeve 35.

The cam mechanism 37 is composed of a twisted cam groove 38 formed in the draw bar 34, and a cam pin 39 fitted in the cam groove 38. The cam pin 39 is supported by the base 40 in a cantilever state, and the base 40 is fixed to the rear side surface of the spider 33. And drawbar 3
4, when the contact portion 34a is slid in the chuck axial direction with the movement of the spider 33 to the position where the contact portion 34a contacts the sleeve 35, it is rotated about its own axis through the cam pin 39 and the cam groove 38. The finger jaw 36 is adapted to be disengaged from the work W.

[0004]

However, according to the conventional finger chuck, since the cam pin 39 is cantilevered by the base 40 and the projecting end thereof is fitted in the cam groove 38, both engaging portions are worn. However, the cam pin 39 may be broken, and the life of the cam mechanism 37 has a problem. Further, since the cam pin 39 is assembled to the spider 33 via the base 40, there is also a problem that the axial dimension of the chuck is increased by the thickness of the base 40.

Therefore, an object of the present invention is to provide a finger chuck that can improve the life of the cam mechanism, and also to provide a finger chuck that can shorten the axial dimension of the chuck.

[0006]

In order to solve the above-mentioned problems, the invention of claim 1 is such that the drawbar is slid in the axial direction as the spider moves in the chuck axial direction, and the cam mechanism is provided. In the finger chuck that rotates the draw bar around its own axis via the finger chuck and engages and disengages the finger jaws with the work, the cam mechanism is configured to make linear contact with the cam surface of the twist shape provided on the draw bar side. It is characterized by being composed of a cam pin provided on the side of the spider.

A finger chuck according to a second aspect of the present invention is characterized in that the cam pin is assembled by being supported by the spider on both sides of the contact portion with the cam surface.

In the finger chuck according to the third aspect of the present invention, a fitting hole into which the drawbar is rotatably fitted is formed in the spider, and a support hole for supporting the cam pin is provided so as to cross the edge of the fitting hole. The cam pin is in line contact with the cam surface at the overlapping portion of the support hole and the fitting hole.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The chuck body 1 of the finger chuck is composed of a cup-shaped body 2 and a rear wall plate 3, and is attached to a spindle of a machine tool by a bolt 4. A receiving seat 5 on which the work W is placed is fixed to the front surface of the cup-shaped body 2, and a plurality of positioning pins 6 for centering the work W are provided on the front surface thereof in a protruding manner.

A draw screw 8 is arranged on the center line of the chuck body 1, and a large diameter portion 8a slidably fitted in the center hole 2a of the cup-shaped body 2 is formed at the front end of the draw screw 8 and the rear end thereof. Is provided with a screw portion 8b connected to a rod moved by a rotary cylinder (not shown) on the spindle side. On the draw screw 8, spherical washers 11, 10,
The spider 9 and the draw sleeve 12 are inserted and assembled by a nut 14 that is screwed into the screw portion 8b. The spider 9 is formed in a substantially triangular shape, and the draw sleeve 12 is slidably inserted into the center hole 3 a of the rear wall plate 3.

A sleeve 1 having three drawbars 16 fixed to the cup-shaped body 2 on the outer peripheral portion of the cup-shaped body 2.
7 are rotatably and slidably supported via the finger jaws 18 for holding the work W at their front ends.
It is replaceably attached at 9. A collar-shaped abutting portion 16b is integrally formed on the outer periphery of the intermediate portion of the draw bar 16, and the sliding plate 6 made of resin having a small frictional resistance is attached to the sleeve 17 at the forward end.
The contact is made through 0. The rear end portion of each draw bar 16 is rotatably fitted into fitting holes 9a provided at three corners of the spider 9, and a screw portion 16a is provided at a portion projecting rearward from the spider 9. The draw bar 16 has a nut member 20 that is screwed into the screw portion 16a.
Is rotatably coupled to the spider 9 via the spherical washer 21 and the slide washer 22. A recess 3b for accommodating the nut member 20 is provided in the rear wall plate 3, and a spring 24 supported by a support pin 23 implanted in the rear wall plate 3 is provided between the recess 3b and the drawbar 16. The drawbar 16 and the spider 9 are urged forward by the spring force of the spring 24.

A cam mechanism 26 for transmitting the driving force of the spider 9 to the drawbar 16 is interposed between the spider 9 and each drawbar 16. The cam mechanism 26 is
It comprises a cam groove 27 provided in the draw bar 16 and a cam pin 28 assembled in the spider 9. Cam groove 2
A cam surface 27 a is formed on the shaft 7 in a shape twisted around the axis of the draw bar 16. The cam pin 28 has a fitting hole 9
Support hole 9 formed in the spider 9 so as to cross the edge portion of a.
The cam surface 27a is line-contacted with the overlapping portion of the support hole 9b and the fitting hole 9a, and is supported by the spider 9 on both sides of the contact portion.

In the finger chuck constructed as described above, when the spider 9 is retracted by the draw screw 8, first, the contact portion 16b of the draw bar 16 is brought into contact with the sleeve 17 by the spring 24, and the cam pin 28 is contacted. Causes the drawbar 16 to rotate about its own axis through the cam groove 27, and then the spider 9 is moved to the washer 2
The draw bar 16 is retracted in the chuck axial direction by coming into contact with the nut member 20 via 2 and the work W is face clamped to the front surface of the front plate 5 by the finger jaws 18. On the contrary, when the spider 9 is moved forward, the draw bar 16 first moves forward together with the spider 9 in the chuck axis direction, and thereafter, the contact portion 16 of the draw bar 16 is moved.
When b comes into contact with the sleeve 17, the draw bar 16 is rotated in the opposite direction by the subsequent advance of the spider 9, the finger jaws 18 are separated from the work W, and the springs 24 hold the finger jaws 18 in the separated position.

Focusing on the cam mechanism 26, since the power is transmitted in the state where the cam pin 28 is in line contact with the cam surface 27a, wear at both engaging portions is suppressed and the life of the cam mechanism 26 is reduced. Can be improved. Further, since the cam pin 28 is supported by the spider 9 in a two-sided holding state, the cam pin 28 can be prevented from being broken, and the pin supporting base as in the prior art is not required, and the axial dimension of the chuck can be shortened. Is also possible. Moreover, since the cam pin 28 is in line contact with the cam surface 7a at the overlapping portion of the support hole 9b and the fitting hole 9a, there is no risk of rattling at this portion, and the draw bar 16 can be rotated and slid reliably and smoothly. be able to.

The present invention is not limited to the above-described embodiment, and the configurations and shapes of the respective parts can be arbitrarily modified and embodied without departing from the spirit of the present invention.

[0016]

As described in detail above, according to the first aspect of the present invention, the cam mechanism is composed of the cam surface having the twist shape and the cam pin which is in line contact with the cam surface. This has the excellent effect of suppressing the life of the cam mechanism.

According to the second aspect of the invention, since the cam pin is assembled to the spider in a double-supported state, it is possible to prevent breakage of the cam pin and to shorten the axial dimension of the chuck.

According to the invention of claim 3, since the cam pin is brought into line contact with the cam surface at the overlapping portion of the support hole and the fitting hole,
There is an effect that the drawbar can be driven reliably and smoothly.

[Brief description of drawings]

FIG. 1 is a sectional view of a finger chuck showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view showing a conventional finger chuck.

[Explanation of symbols]

1 ... Chuck body, 8 ... Draw screw, 9 ...
Spider, 9a ... Fitting hole, 9b ... Support hole, 16 ...
Drawbar, 18-finger jaw, 26-cam mechanism, 27-cam groove, 27a-cam surface, 28-cam pin, W-work.

Claims (3)

[Claims] 1. The drawbar is slid in the axial direction as the spider moves in the chuck axial direction, and the drawbar is rotated about its own axis through a cam mechanism to disengage the finger jaws from the work. A finger chuck in which a cam mechanism includes a twisted cam surface provided on the drawbar side and a cam pin provided on the spider side so as to make linear contact with the cam surface. 2. The finger chuck according to claim 1, wherein the cam pin is assembled by being supported by a spider on both sides of a contact portion with the cam surface. 3. The spider is provided with a fitting hole into which the drawbar is rotatably fitted, and a supporting hole for supporting the cam pin is provided so as to cross an edge of the fitting hole. The finger chuck according to claim 1 or 2, wherein the cam pin is brought into line contact with the cam surface at the overlapping portion.