JP3446414B2 - Finger chuck - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finger chuck for holding a work in a machine tool.

[0002]

2. Description of the Related Art For example, a finger chuck used for turning an aluminum wheel usually has a mechanism for clamping a work and a mechanism for centering the work. In a conventional centering mechanism, like a finger chuck disclosed in Japanese Patent Laid-Open No. 7-68405, a centering body is provided at the center of the chuck body so as to project forward, and three claws slide on the body in the radial direction of the chuck. The work is provided so as to be movable, and the work is grasped from the inner peripheral side by these claws and centered.

[0003]

However, according to the conventional finger chuck, the work is gripped by the centering claw that is slidable in the chuck radial direction, so that the work can be held on the outer peripheral side by the centering claw. When gripping from, there is a problem that the gripping force decreases due to the centrifugal force that acts on the centering claw due to chuck rotation, and the work moves during rotation.In particular, the centering claw should be placed near the outer periphery of the chuck body. It was a big problem when it was installed. Also, since the centering claw is slid with the stroke of the wedge plunger, the stroke of the wedge plunger must be increased in order to increase the jaw stroke of the centering claw to accommodate workpieces of various sizes. However, it is necessary to increase the wedge angle, but an increase in stroke leads to an increase in the chuck overall length, and there is a limit to the increase in the wedge angle (generally 30 degrees or less), which causes a problem of increasing the size of the chuck.

Therefore, an object of the present invention is to provide a finger chuck in which the grasping force of the centering claw can be prevented from being lowered by centrifugal force and the jaw stroke of the centering claw can be easily increased. Especially.

[0005]

In order to solve the above problems, the finger chuck according to the invention of claim 1 is provided with a plurality of guide grooves radially extending from the center on the front surface of the chuck body, and each guide groove has a parent groove. The claw is slidably fitted, and the plunger that drives the parent claw along the guide groove is provided inside the chuck body.The support is placed on the chuck body at the position corresponding to the parent claw. and rotatably supported by a shaft of the crank lever at an intermediate portion to form a connection portion that is connected to Shintsume to one end of a crank lever, provided the pawl that engages the workpiece at the other end of the crank lever, the support Crank with body
A means for adjusting the position of the lever in the longitudinal direction of the guide groove is provided,
Guide the engaging part that engages the connecting part of the crank lever to the parent claw
A plurality of grooves are provided in the longitudinal direction of the groove .

In the finger chuck according to a second aspect of the present invention, the position adjusting means is a protrusion provided on the back surface of the support.
And engraved on the front plate of the chuck body
With the positioning groove and the protrusion fitted in the positioning groove,
This includes the bolts that attach the holder to the front plate.
And are characterized.

[0007]

[0008]

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a finger chuck will be described below with reference to the drawings. As shown in FIGS. 1 and 2, a chuck body 1 of a finger chuck is constructed by assembling a front plate 3 to a front end of a cup-shaped body 2 attached to a spindle (not shown) of a machine tool. A guide sleeve 4 is fixed to the central portion of the rear end of the cup-shaped body 2, and a draw screw 5 including an outer cylinder 5a and an inner cylinder 5b is inserted inside the guide sleeve 4. A draw bolt 6 is inserted inside the draw screw 5, and these draw members 5 and 6 are driven in the chuck axis direction by a rotary cylinder (not shown) installed on the spindle side.

A contact portion 7 is provided at the front end of the draw screw 5, and two spiders 8 and 9 on the rear side of the contact portion 7 are tilted forward and backward via spherical washers 10 and 11, respectively. It is supported freely. The rear spherical washer 11 is housed in the center hole 8a of the front spider 8, and the front surface thereof is provided with an engaging portion 11a that engages with the contact portion 7 through the hole 10a of the front spherical washer 10. There is. A coil spring 12 is interposed between the rear spherical washer 11 and the rear spider 9.

On the outer periphery of the front plate 3, six finger levers 17 are provided at the center of the V-shaped groove 17a for the pin 1.
A gripping claw 19 that is swingably supported by 8 and that engages with the outer peripheral surface of the work W such as an aluminum wheel is provided at the front end of each lever 17.
Has been attached. The rear ends of the three finger levers 17 are rotatably connected to the outer periphery of the front spider 9 and the remaining rear ends of the three finger levers 17 are connected to the outer periphery of the rear spider 12 by shafts 20, respectively. Each finger lever 17 is opened and closed via the spiders 8 and 9 as the draw screw 5 moves, and in the closed state, the grip claws 19 clamp the work W from the outer peripheral side. A work pedestal 21 is provided on the front surface of the front plate 3 at the same circumferential position as the finger lever 17. Coil springs 22 and 23 for urging the finger lever 17 in the opening direction are interposed between the cup-shaped body 2 and the spiders 8 and 9.

As shown in FIGS. 1 and 3, a large diameter cylindrical hole 25 is provided at the center of the front plate 3, and a wedge plunger 26 is housed in this cylindrical hole 25 so as to be slidable in the chuck axial direction. Has been done. The wedge plunger 26 is connected to the front end of the draw bolt 6 by a clasp 27, and the draw bolt 6 is linearly guided by the draw screw 5. Also, on the front surface of the front plate 3,
The three guide grooves 29 having a T-shaped cross section (see FIG. 4) are cylindrical holes 2.
5 is formed so as to extend radially from the center of 5 through the middle of a pair of adjacent finger levers 17, and each guide groove 2
A centering claw 30 for centering the work W is slidably fitted to 9 (the guide groove 29 may have a dovetail groove shape or a round cross section). A dust cover 28 is attached to the front plate 3 to prevent chips from entering the cylindrical hole 25 and the wedge plunger 26.

As shown in FIGS. 3 to 5, the centering pawl 30 includes a master pawl (master jaw) 31 having a T-shaped cross section, which is fitted in the guide groove 29, and a crank lever 32 which holds the work W from the outer peripheral side. It consists of At the inner end of the parent claw 31, the wedge portion 3 that meshes with the wedge groove 26a of the wedge plunger 26.
1a is provided, and the parent claw 31 is driven along the guide groove 29 as the wedge plunger 26 moves back and forth. Also,
Three engaging grooves 31b are formed on the front surface of the outer end portion of the parent claw 32 at equal pitches in the longitudinal direction of the guide groove 29.

At a position corresponding to the parent claw 31, a support body 33 is attached to the front plate 3 with four bolts 34 so as to straddle the guide groove 29, and a crank lever 32 is attached to the support body 33 at an intermediate shaft. It is rotatably supported by 35. Screw hole 36 for tightening the bolt 34
Are formed at four positions on the front plate 3 at equal pitches in the longitudinal direction of the guide groove 29. Further, three positioning grooves 37 are engraved on the front plate 3, one of these grooves 37 is fitted with a protrusion 33a on the back surface of the support body 33, and a bolt 34 is inserted into a screw hole 36 at a position sandwiching the groove 37. The crank lever 32 is adjustably attached to the guide groove 29 at three positions in the longitudinal direction by tightening.

Since the crank lever 32 is sandwiched by the pair of side wall portions 33b of the support body 33, there is no possibility of rattling in the circumferential direction. In addition, the positioning means of the crank lever 32 is provided by the projection of the front plate 3 and the support body 3.
It may be configured by a groove of No. 3, a cylindrical hole and a cylindrical protrusion, or by providing serrations on the facing surfaces of the front plate 3 and the support body 33.

At the rear end of the crank lever 32, there is integrally formed a connecting portion 32a which selectively fits in the engaging groove 31b of the parent claw 31, and at the other end of the crank lever 32 , the work W is engaged. The claw 38 is attached by a screw 39 so as to be replaceable according to the work diameter. In the crank lever 32 , a centrifugal moment generated by a centrifugal force generated according to the mass of the claw 38 side of the shaft 35 with the chuck rotation is generated according to the mass of the coupling part 32 a side of the shaft 35 and the mass of the parent claw 31. The rotational moment due to the centrifugal force generated in accordance with the mass of the claw 38 side of the shaft 35 is slightly smaller than the rotational moment due to the force, and the rotational moment due to the centrifugal force is generated from the shaft 35 to the connecting portion 32.
It is formed in a shape that substantially balances the rotational moment due to the centrifugal force generated according to the mass on the side a and the mass of the parent claw 31. Then, at each adjustment position of the support body 33, the crank lever 32 is connected to the master claw 31 through the fitting of the coupling portion 32a and the engagement groove 31b, and opens and closes in the chuck radial direction as the master claw 31 slides. In the rotated and closed state, the claw 38 clamps the work W from the outer peripheral side to center it.

On the other hand, as shown in FIGS. 1 and 3, three work receiving seats 41 are provided on the front surface of the outer peripheral portion of the front plate 3 at a position 180 ° away from the centering claw 30. Each seat 41 is supported by a base 42 via a spring 43 so as to be retractable. One seat 41 is configured to detect the seating of the work W based on the pressure fluctuation of the air supplied from the air passage 44 of the front plate 3. The base 42 is adjustably attached to three positions in the chuck radial direction at the same pitch as the crank lever 32 by selectively tightening the mounting bolts 45 into the screw holes 46 of the front plate 3. Therefore, by adjusting the positions of the crank lever 32 and the receiving seat 41, it is possible to easily deal with the difference in the gripping diameter of the work W.

In the finger chuck constructed as described above, the workpieces W have different outer peripheral positions at three outer peripheral positions.
It is centered by one centering claw 30 and is gripped by six finger levers 17. In this case, since the parent claw 31 is fitted in the guide groove 29, the work W can be centered and gripped at a position close to the front surface of the chuck body 1. Therefore, the amount of overhang on the front side of the chuck can be reduced and the rigidity of each part of the chuck can be improved.
It is also possible to shorten the finger lever 17 and improve the grip accuracy of the work W. Further, the centering claw 30 and the wedge plunger 26 are respectively attached to the front plate 3
Since it is incorporated in the centering mechanism, a body dedicated to the centering mechanism can be eliminated, the number of parts can be reduced, and the centering mechanism can be easily and compactly constructed.

Particularly, in the centering claw 30, when the parent claw 31 is urged outward by the centrifugal force during processing, the crank lever 32 is rotated in the closing direction via the engaging groove 31b and the connecting portion 32a. Be energized. Therefore, unlike the linearly sliding claw, the gripping force of the centering claw 30 is not likely to decrease due to the centrifugal force, and rather the crank lever 32 is caused by the centrifugal force generated according to the mass on the front side of the shaft 35. Since the rotational moment is formed to have a shape that is slightly smaller than the rotational moment due to the centrifugal force generated according to the mass on the rear side and the mass of the parent claw 31, a tightening action can be expected and the workpiece W can be expected. High-speed turning can be performed safely. Further, the rotational moment due to the centrifugal force generated according to the mass on the front side of the shaft 35 of the crank lever 32 is substantially balanced with the rotational moment due to the centrifugal force generated according to the mass on the rear side and the mass of the parent claw 31. Therefore, the centrifugal force acting on the crank lever relaxes the force of the parent claw 31 in the closing direction, the work W can be clamped without being deformed, and the fluctuation of the gripping force due to the change of the rotation speed of the chuck is suppressed. Thus, there is an advantage that the work W can always be clamped with an appropriate gripping force, and the gripping force can be easily adjusted to a value that is almost directly proportional to the driving force of the rotary cylinder that acts on the parent claw 31.

In the above embodiment, the wedge plunger 26 is used to engage the parent pawl 31 with the wedge groove 26a. However, a normal plunger is used, and the parent pawl 31 is attached to this through the crank mechanism. May be engaged. In addition, the present invention is not limited to the above-described embodiment, and is implemented by arbitrarily changing the configuration of each part without departing from the spirit of the present invention, such as changing the number and shape of the centering claw and the finger lever. It is also possible to do so. Further, the guide groove provided on the chuck body may be provided on the body of the centering chuck provided on the front plate, or may be provided on the guide member provided on the chuck body.

[0021]

As described in detail above, according to the present invention,
Since the master claw is fitted in the guide groove on the front of the chuck body and the crank lever is connected to the master claw, the workpiece can be gripped at a position close to the chuck body, and the rigidity and gripping accuracy of each part of the chuck can be improved. It has an excellent effect that the reduction of the gripping force due to the centrifugal force can be prevented.

Further, since the crank lever is provided along with the support so that the position of the crank lever can be adjusted in the longitudinal direction of the guide groove, it is possible to easily deal with the difference in the gripping diameter of the work.

[0023]

[0024]

[Brief description of drawings]

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

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

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a view on arrow C of FIG.

5 is a cross-sectional view taken along the line DD of FIG.

[Explanation of symbols]

1 ... Chuck body, 17 ... Finger lever, 2
6 ... Wedge plunger, 29 ... Guide groove, 30.
.Centering claws, 31 ... Parent claws, 31b ... Engaging grooves, 32 ...
Crank lever, 32a ··· connection part, 33 · · support,
33a ... Protrusion, 34 ... Bolt, 35 ... Shaft, 36 ...
・ Screw hole, 37 ・ ・ Positioning groove, 38 ・ ・ Claw, W ・ ・ Workpiece.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B23B 31/18 B23B 31/12

Claims (2)

(57) [Claims] 1. A plurality of guide grooves extending radially from the center are provided on the front surface of the chuck body, and parent pawls are slidably fitted in the respective guide grooves, and the parent pawls are provided along the guide grooves in the chuck body. A plunger is provided for driving, a support body is provided on the chuck body at a position corresponding to the parent claw, and the crank lever is rotatably supported by the shaft at the intermediate portion on the support body, and the parent claw is attached to one end of the crank lever. a connecting portion connected to form the provided nails engaging the workpiece at the other end of the crank lever, the support
Position adjustment of the crank lever along with the body in the longitudinal direction of the guide groove
Means for engaging the main claw with the connecting part of the crank lever
A finger chuck having a plurality of engaging portions provided in the longitudinal direction of the guide groove . 2. The position adjusting means is provided on the back surface of the support.
And the front plate of the chuck body
The engraved positioning groove and the protrusion were fitted into the positioning groove.
Bolts to attach the support to the front plate
The finger chuck according to claim 1 , further comprising :