JPH09225714A - Four-jaw chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely catch a work not round by providing jaws in such a manner that the work is held by one set of jaws after it is held by the other set of jaws. SOLUTION: By the movement to the right of a piston rod, a first crank lever 18 is rotated clockwise, and a second crank lever is rotated counterclockwise. Thus, sliders 12, 13 approach the axial center of a chuck body, and when chuck jaws 14, 14 of the first set of sliders 12, 12 come in contact with a work, the sliders 12, 12 are not moved even when the piston rod is further moved to the right, an engaging element 8 is thus not moved, a forked lever 27 is rotated clockwise by the movement of a shaft pin 26, and the chuck jaw 16 of the slider 13 is approached to the axial center of the chuck body and brought into contact with the work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chuck for a robot hand or a lathe, and more particularly to a four-jaw chuck which is convenient for gripping a work whose outer or inner circumference is not a perfect circle.

[0002]

In the conventional four-jaw chuck, four chuck claws arranged in a cross shape simultaneously approach the center of the chuck or move away from the center of the chuck in the same step, and grip the work. Therefore, even if the diameters of the work are slightly uneven, the work cannot be reliably gripped. Therefore, in the present invention, 4 in the 4-jaw chuck is used.
An object of the present invention is to provide a four-claw chuck that allows two claws facing each other to move in the same step so that even a work having a non-circular diameter can be reliably gripped at four points. To do.

[0003]

According to the present invention, an engaging member having a circumferential groove is slidably fitted in a piston rod of a piston which moves forward and backward by a pressure fluid, and a foot is fitted in the circumferential groove. The center of the bifurcated lever that engages with each other is pivotally supported, and one of the four claws of the four cranks arranged in a cross makes the two claws facing each other move in the same manner. One arm is engaged, the other arm of the first crank lever is engaged with the engaging element, the other arm of the second crank lever is engaged with the other set of claws, and the other arm of the second crank lever is bifurcated. Engage with the bifurcation of the lever, engage the leg of the bifurcated lever with the engaging element, pivotally support the first crank lever and the second crank lever on the chuck body with the shaft pin, and pivot the center of the bifurcated lever with the shaft pin. It is a structure pivotally supported by a bracket integrated with the rod.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described based on examples with reference to the drawings. A head shaft 6 projects from the front end of a piston rod 5 which projects forward from a cylinder 4 composed of a peripheral body part 1 and front and rear end parts 2 and 3, and a circumferential groove for engaging the head shaft 6 with the end of a lever described later. Engagement element 8 having 7 is fitted slidably in the axial direction. A pair of bifurcated brackets 9 and 9 project from the front end surface of the piston rod 5 at symmetrical positions with respect to the engaging element 8, and a claw support frame 10 is provided in front of the front end portion 2 of the cylinder 4. The claw support frame 10 is provided with four T-shaped grooves 11 radially at intervals of 90 degrees around the axis of the piston rod 5, and the T-shaped grooves 1
Two sliders 12 and 13 facing each other are slidably fitted in the unit 1. That is, the set of the sliders 13 facing each other with respect to the set of the sliders 12 facing each other is designed to move in the right-angled direction. The chuck claw 14 is fixed to the surface of the slider 12, the engaging groove 15 is provided on the back surface, the chuck claw 16 is fixed to the surface of the slider 13, and the engaging groove 17 is provided on the back surface. In the engagement groove 15 of the slider 12 of the first set, the first crank lever 1
8, the tip 19 of one arm engages, and the second set of sliders 13
The one end 21 of one arm of the second crank lever 20 is engaged with the engaging groove 17 of. The first crank lever 18 is rotatably supported at its center by a shaft pin 22, and has a tip 23 of the other arm.
Engages with the circumferential groove 7 of the engaging element 8. The second crank lever 20 is rotatably supported at its center by a shaft pin 24,
The tip 25 of the other arm is engaged with a fork 28 of a fork lever 27 rotatably supported by a shaft pin 26 at the center of the fork bracket 9, and a foot 29 of the fork lever 27 is attached to the circumferential groove 7 of the engaging element 8. Is engaged with.

3 and 4, when the piston moves to the right by a pressure fluid such as pressure oil or pressure air, the shaft pin 26, the forked lever 27, and the engaging element 8 are integrated with the piston rod 5 to the right. To go. By the rightward movement of the piston rod 5, the first crank lever 18 rotates in the hour hand direction and the second crank lever 20 rotates in the counter hour hand direction. Therefore, slider 1
2 and 13 are closer to the axis of the chuck body, and chuck claws 14 and 14 fixed to the sliders 12 and 12 of the first set.
Alternatively, the chuck jaws 16 and 16 fixed to the second set of sliders 13 and 13 come to grip the work. Now, for example, assuming that the chuck claws 14, 14 first come into contact with the work, the sliders 12, 12 do not move even when the piston rod 5 moves further to the right, and accordingly the engaging element 8 also stops moving, and the bifurcated lever 27 is moved. Is moved by the movement of the shaft pin 26 in the hour hand direction, and the slider 13, that is, the chag claw 16 is brought closer to the shaft center of the chuck main body through the second crank lever 20 and comes into contact with the work.

If the chuck jaws 16 and 16 hit the work first, the second crank lever 20 and the forked lever 2
7, the rotation of the piston rod 5 is stopped, but the shaft pin 26 of the forked lever 27 moves to the right when the piston rod 5 continues to the right, so that the forked lever 27 rotates in the counterclockwise hand direction and the engaging element 8
, The first crank lever 18 is rotated in the direction of the hour hand, and the chuck claws 14, 14 move closer to the work and hit and grip the work.

Although the above description has been made on the case where the outer circumference of the work is gripped, the inner circumference of the work can be securely gripped similarly.

In the above description, the forked lever is interposed between the second crank lever and the engaging element. However, as shown in FIG. 6, a forked 30 is formed at the other arm tip of the second crank lever to replace the forked lever. Alternatively, the lever 31 having no crotch may be engaged with the fork 30.

[0009]

According to the present invention, the two facing claws of the four claws always make the same movement, and after one of the sets holds the work, the other set of the claws holds the work. Therefore, even a work that is not a perfect circle can be reliably chucked with four claws.

[Brief description of drawings]

FIG. 1 is a front view.

FIG. 2 is a plan view.

3 is a cross-sectional view taken along the line A-O-B in FIG.

FIG. 4 is a cross-sectional view showing a state in which a chuck claw is far away.

FIG. 5 is a sectional view taken along line CC in FIG. 3;

FIG. 6 is an explanatory diagram showing an example of an engaging element.

[Explanation of symbols]

 5 Piston Rod 6 Headed Shaft 7 Circumferential Groove 8 Engager 9 Bifurcated Bracket 12, 13 Slider 14, 16 Chuck Groove 15, 17 Engagement Groove 18 First Crank Lever 20 Second Crank Lever 19, 21 Tip of One Arm 23, 25 Tip of other arm 22, 24, 26 Axis pin 27 Bifurcated lever 28 Bifurcated 29 feet

Claims (1)

[Claims] 1. A four-jaw chuck in which four claws are arranged in a cross shape around the axis of the chuck body, and two sets of claws that face each other are used to grip a workpiece. A piston rod that is moved forward and backward by pressure fluid is provided, and an engagement element is slidably inserted in the piston rod in the axial direction, and one end of the first crank lever is engaged with a pair of claws that move forward and backward. The other end is engaged with the engaging element, the other pair of the claws is engaged with one end of the second crank lever, the other end is engaged with the bifurcation of the bifurcated lever, and the foot of the bifurcated lever is engaged with the engaging element. It is characterized in that the center of the bifurcated lever is supported by a bracket integral with the piston rod so as to be vertically rotatable by a shaft pin, and the first crank lever and the second crank lever are pivotally supported by the chuck body by the shaft pins. 4 claw chuck.