JPH08192306A - Gripping jaw for chuck - Google Patents

Abstract

PURPOSE: To sufficiently secure a gripping area and strength in a gripping jaw for a chuck in which a mounting bolt head part for the gripping jaw and a gripping face overlap each other in the radius direction of the chuck. CONSTITUTION: In a gripping jaw 21, an outline is formed into an L-shape, and a gripping face 24 is positioned in the opposed position to a button bolt 23 on the outside in the radius direction of the chuck 1, while a U-shaped bolt insertion part 28 is arranged on a draw bar 18 side beyond a gripping face formation part 25. A bolt operating hole 29 provided with a diameter smaller than that of a bolt head part 23c is bored in the opposed position to the bolt head part 23c inserted into the bolt insertion part 28 in the chuck rotational axis line L direction, and the chuck rotational axial line L direction width in a bolt head part insertion part 27 is set to be narrow so as to correspond to the head part height of the button bolt 23 whose head part height is low.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape of a gripping claw for a chuck in which the head of a mounting bolt and a gripping surface overlap each other in the radial direction of the chuck.

[0002]

2. Description of the Related Art A conventional gripping claw for a chuck is disclosed in Japanese Patent Application Laid-Open No. 47-36277.
As shown in FIG. 7, the gripping claw 121 has three gripping surfaces 124a, 124b, and 124c facing outward in the radial direction in a staircase pattern with different phases in the axial direction of the chuck 1, and has a gripping surface at the radially inner end. The gripping surface 124d has a larger gripping area than that of the gripping surface 124a. The gripping surface 124d protrudes from the front end surface of the chuck body 2 and is attached to the gripping claw mounting member 18 such as a master jaw or a drawbar which is movable in the radial direction.
The movement of 8 moves in the radial direction. Grasping claw mounting member 1
In order to attach the grasping claw 121 to the 8, the grasping claw 121 is provided with a bolt attachment portion 135 in which three counterbore holes 130 bored in the chuck rotation axis direction into which the attachment bolt 123 is inserted are continuous. The counterbore part (bolt head insertion part) 132 of the counterbore hole 130 has gripping surfaces 124b, 124.
It depends on c. In the case of FIG. 7, the grasping pawl 121 is attached to the grasping pawl attaching member 18 by using the two counterbore holes 130 on the outer side in the radial direction. In this state,
The mounting bolt head 123c inserted into the spot facing hole 130 and the gripping surface 124b overlap each other in the chuck radial direction.

[0003]

In the conventional grasping claw, the counterbore portion 132 of the counterbore hole 130 has the grasping surface 124.
b, 124c, and since the grasping surface is notched by the spot facing portion 132, the grasping surface 124b of the grasping claw,
There is a problem that the work gripping area of 124c becomes small, the surface pressure at the time of gripping the work becomes high, the work is easily damaged, and the strength of the gripping surface forming portion is lowered.

An object of the present application is to increase the gripping area of the gripping surface of the gripping jaw and increase the strength of the gripping nail itself in the chuck gripping nail in which the bolt head and the gripping surface overlap in the radial direction. It is to provide a grasping claw for a chuck that can be performed. Another object of the present invention is to provide a chuck grasping pawl that can be tightened and loosened by tightening a mounting bolt from the front side in the axial direction of the chuck by using a tightening tool similar to the conventional one. Still another object is to provide a grasping claw for a chuck, which can be used when the space in the front in the chuck axial direction is limited, and has a small thickness in the chuck axial direction. Still another problem is to solve all of the above problems, and to secure a gripping surface forming part of the gripping claw and a gripping surface sufficient to grip the workpiece, and even if the chuck has the same diameter, it is close to that diameter. It is to provide a grasping claw for a chuck capable of grasping a large work.

[0005]

In order to solve the above-mentioned problems, according to a first aspect of the present invention, the gripping claw mounting member that is movable in the radial direction of the chuck is mounted by a mounting bolt, and in the mounted state, the mounting bolt is mounted in the radial direction of the chuck. In the gripping jaws for chucks, where the gripping surface of the head and the gripping surface of the gripping nail overlap, a U-shaped bolt insertion part and a U shape for the mounting bolt that opens to the outside of the gripping nail on the gripping nail mounting member side of the gripping surface forming part And a U-shaped bolt insertion portion including a bolt head insertion portion. According to the present invention, a bolt operating hole smaller than the bolt head diameter is bored at a position opposite to the bolt head inserted into the bolt insertion portion in the chuck rotation axis direction in a state where the bolt is attached to the grasping claw mounting member with the mounting bolt. Is characterized by. According to a third aspect of the present invention, the width of the bolt head insertion portion in the chuck rotation axis direction is set to a width corresponding to a low head bolt having a low head height. According to a fourth aspect of the present invention, it is a pawl attached to the grasping pawl mounting member with two mounting bolts, and the mounting bolt is a low head bolt, and the outer shape of the grasping pawl is in the direction opposite to the rear surface facing the grasping pawl mounting member. It has a protruding L shape, a U-shaped bolt insertion part is provided on the gripping claw mounting member side of the gripping surface forming part, and the low head on the outer side in the radial direction of the chuck when attached to the gripping claw mounting member with a low head bolt. The gripping surface is located at a position facing the bolt head, and a bolt operating hole smaller than the bolt head diameter is bored at a position facing the chuck head of the bolt inserted in the bolt insertion portion in the direction of the chuck rotation axis. It is characterized in that the width of the insertion portion in the chuck rotation axis direction corresponds to the low head bolt.

[0006]

According to the grasping claw for a chuck of claim 1, U which is opened to the outside of the grasping claw is closer to the grasping claw mounting member than the grasping surface forming portion.
Since the bolt-shaped insertion portion is provided, the bolt head insertion portion is not applied to the grasping surface, and the grasping area is larger than before and the strength is increased. According to the second aspect of the present invention, since the bolt head inserted into the bolt insertion portion in the mounted state is provided with a bolt operation hole smaller than the bolt head diameter that overlaps the gripping surface in the chuck radial direction at a position facing each other in the chuck rotation axis direction. The notch on the grip surface is smaller than that of the conventional structure in which the bolt head insertion portion is provided on the grip surface, the gripping area is larger than before, and the mounting bolt can be tightened as usual from the front of the chuck. According to the third aspect, the width of the bolt head insertion portion in the chuck rotation axis direction is set to a width corresponding to the low head bolt having a low head height, whereby the size in the rotation axis direction can be reduced. In addition, in the fourth aspect, in addition to the configurations of the first to third aspects, since the gripping surface is located at a position facing the outer mounting bolt, the gripping area is large, and the mounting bolt is tightened from the chuck axial direction, A chuck claw that can be loosened and has a small thickness in the chuck axis direction.
A large workpiece can be grasped with a small diameter chuck.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the gripping claw for a chuck of the present invention will be described with reference to the drawings. As shown in FIG. 1, the drawdown chuck 1 is provided with a back plate 4 at the rear portion of the chuck body 2 and is attached to a rotary spindle A of a lathe with bolts 3. A draw sleeve 6 penetrates through the back plate 4 and is fitted in a through hole 5 in the central portion of the chuck body 2 so as to be slidable in the rotation axis L direction. A draw screw 8 connected to a piston rod of a rotary cylinder (not shown) at the rear end of the rotary spindle A is inserted into the center hole 7 of the draw sleeve 6, and a round nut 9 is screwed into the threaded portion of the draw screw 6 to connect to the draw sleeve 6. It is firmly fixed. Chuck body 2
The through hole 5 is closed by a pilot plate 11 attached by a plurality of bolts 10. The through hole 5 of the chuck body 2 is formed in the large diameter hole 12 at the rear portion, and the hook portion 13 of the draw sleeve 6 is located in the large diameter hole 12. A part of the hooking portion 13 is cut out in a U shape, and the notch groove 14 is provided so as to project rearward from the surface of the large diameter hole 12 of the chuck body 2 into the large diameter hole 12 and is attached to the chuck body 2 by a bolt 15. A fixed detent 16 is fitted to prevent the draw sleeve 6 from rotating. Further, as shown in FIG. 2, the chuck body 2 is provided with insertion holes 17 inclined with respect to the rotation axis L at positions that divide the circumferential direction into three equal parts. A draw bar 18 is slidably inserted in a direction inclined with respect to the chuck rotation axis L. A hook groove 19 that engages with the hook portion 13 of the draw sleeve 6 is provided at the rear portion of the draw bar 18,
The rear end of the draw bar 18 is housed in the recess 4 a of the back plate 4. As shown in FIG. 2, a stopper base 33 for the work W is fixed to the front surface of the chuck body 2 between the insertion holes 17 at positions that divide the chuck circumferential direction into three equal parts, like the insertion holes 17.

The draw bar 18 protruding from the front surface of the chuck body 2 is formed with a radial projection 20a and a concave groove 20 orthogonal to the projection 20a.
1 The concave groove 21a provided on the back surface is fitted, and the concave groove 20
The grasping claws 21 are attached to the respective drawbars 18 by engaging the projections 22 of the grasping claws 21 and button bolts (low head bolts) 23, which are two mounting bolts, which will be described later, arranged in the radial direction. As shown in FIG. 4, the grasping pawl 21 attached to the drawbar 18 has an L-shaped outer shape when viewed from the side, and the grasping surface forming portion 25 protrudes in the opposite direction to the back surface facing the drawbar 18. The grip surface 21 is formed on the grip claw 21.
A U-shaped bolt insertion portion 26 for a mounting bolt and a U-shaped bolt head insertion portion 27 as shown in FIG. 5, which is open to the outside in the radial direction of the grasping claw 21 while maintaining a certain thickness on the drawbar 18 side. A U-shaped bolt insertion portion 28 is formed. The width D of the U-shaped bolt head insertion portion 27 in the chuck rotation axis L direction is formed to be a narrow width corresponding to the button bolt 23 which is a low head bolt having a low head height. The button bolt 23 is a well-known one, and the bolt head has a shape with an R, and is a low-head bolt whose head height is lower than that of a normal hexagon socket head cap bolt. There is a hexagonal hole. The gripping surface forming portion 25 grips the gripping claw 21 at a position that radially overlaps the bolt head 23c of the button bolt 23 that is radially outward in the chuck radial direction when the gripping claw 21 is attached to the drawbar 18. Surface 2
4 are provided.

Also, with the drawbar 18 attached,
A bolt operating hole 29 having a diameter smaller than the diameter of the bolt head 23c is formed at a position opposite to the bolt head 23c of the button bolt 23 radially outside inserted in the bolt insertion portion 28 in the chuck rotation axis L direction. The grip surface 24 of 21 is slightly cut out so as to overlap with the bolt operation hole 29. The bolt operation hole 29 is a hole through which a tool for fastening the button bolt 23 when the grasping claw 21 is attached to the drawbar 18 with the button bolt 23, and is slightly smaller than the maximum diameter of the hexagonal hole of the button bolt 23. It has a large diameter. A counterbore hole 32 including a bolt insertion hole 30 and a bolt head insertion hole 31 is bored in the chuck rotation axis L direction inside the chuck radial direction when the grasping claw 21 is attached.

Next, the operation of this embodiment configured as described above will be described. The draw screw 8 is connected to a rotary cylinder attached to the rear end of the main shaft A. By operating the piston rod of the rotary cylinder back and forth, the draw screw 8 moves back and forth, and the draw sleeve 6 connected to the draw screw 8 moves back and forth. When the draw sleeve 6 retracts, the hook groove 19 of the draw bar 18 engaged with the hook portion 13 of the draw sleeve 6 is pulled by the hook portion 13, and the draw bar 18 slides diagonally rearward in the insertion hole 17 of the chuck body 2, As a result, the grasping claw 21 attached to the tip of the draw bar 18 protruding from the chuck body 2 moves inward in the chuck radial direction, is pressed against the stopper base 33, and grasps the work W positioned by the phase determining pin (not shown) on the grasping surface 24. To chuck. When the draw screw 8 is pushed forward by the piston rod, the draw sleeve 6 moves forward along the chuck rotation axis L,
The hook portion 13 of the draw sleeve 6 pushes the hook groove 19 of the draw bar 18 forward, slides the draw bar 18 in the insertion hole 17 of the chuck body 2 forward, and moves the grasping claw 21 to the outside of the chuck 1 in the radial direction. The work W is released. Since only the button bolt operating hole 29 is bored in the grasping surface forming portion 25 of the grasping claw 21, a counterbore larger than the bolt head 23c is not bored as in the conventional case, and compared with the conventional one. A wide grasping surface can be secured by the difference between the spot facing diameter and the inner diameter of the bolt operating hole 29, and it is possible to prevent an increase in surface pressure at the time of grasping, and moreover, since the notch of the grasping surface forming portion 25 is small, the strength is high. Also increases. Further, since the grasping surface forming portion 25 is formed at the position opposite to the button bolt 23 on the outer side of the two button bolts 23 in the chuck radial direction, it is possible to grasp a large workpiece with a chuck having a small diameter.
Further, since the width of the bolt head insertion portion 27 is set to be a narrow width required to accommodate the head portion of the button bolt 23, the thickness of the entire grasping claw 21 in the chuck rotation axis direction can be reduced, and the chuck axis direction can be reduced. Can be used even when there are restrictions on dimensions.

Next, the attachment of the grasping pawl 21 to the drawbar 18 will be described. The button bolt 23 is inserted into the U-shaped bolt insertion portion 28 from the outside in the radial direction. At this time, the bolt head 23c is housed in the bolt head insertion portion 27, and the threaded portion of the button bolt 23 projects rearward from the rear surface of the grasping claw 21. In this state, the button bolt 23 is opposed to the screw hole on the outer side in the radial direction of the draw bar 18, and is screwed from the front side in the chuck axis L direction through the bolt operating hole 29 with a normal hexagon wrench. Then, another button bolt 23 is tightened through the counterbore 32. Even the one having the U-shaped bolt insertion portion 28 can be attached without using a special tool.

If it is desired to further increase the grasping area of the grasping surface of the grasping claw, the head portion of the button bolt is not provided with a bolt operating hole smaller than the diameter of the head portion of the bolt formed at a position facing the mounting screw. A plurality of engaging / disengaging holes for bolt tightening perpendicular to the axial direction of the bolt are provided in the circumferential direction, and a rod-shaped bolt tightening tool is inserted into the engaging / disengaging hole from the opening of the U-shaped bolt insertion part to attach the button bolt. Just tighten it.

[0013]

In the grasping claw for a chuck of the present invention, since the U-shaped bolt insertion portion opening to the outside of the grasping claw is provided on the grasping claw mounting member side with respect to the grasping surface forming part, the grasping area is larger than the conventional one. The strength is secured. In addition, a bolt operation hole smaller than the bolt head diameter that overlaps the gripping surface in the chuck radial direction is drilled at a position where the bolt head inserted in the bolt insertion part in the mounted state faces the chuck rotation axis. The notch of the grasping surface is smaller than that of the conventional case in which the part insertion portion is attached to the grasping surface, the gripping area is larger than before, and the mounting bolt can be tightened from the front of the chuck as usual. Further, the chuck head has a small width in the rotational axis direction because the width of the bolt head insertion portion in the chuck rotational axis direction is made narrow to correspond to the low head bolt having a low head height. Further, since the gripping surface is located at a position facing the outer mounting bolt, it is possible to grip a large work having a diameter close to that of the chuck.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a chuck.

FIG. 2 is a front view of a chuck.

FIG. 3 is a front view of a grasping claw for a chuck.

FIG. 4 is a side view of a grasping claw for a chuck.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

6 is a VI view of FIG. 4. FIG.

FIG. 7 is a front view showing a conventional gripping claw for a chuck.

[Explanation of symbols]

1 chuck, 2 chuck body, 18 drawbar, 21 grasping claw, 23 button bolt, 23c
Bolt head, 24 gripping surface, 25 gripping surface forming part,
28 U type bolt insertion part, 29 bolt operation hole,
L chuck rotation axis, W work

Claims (4)

[Claims] 1. A gripping jaw for a chuck, which is attached to a gripping jaw mounting member that is movable in the radial direction of the chuck by a mounting bolt, and the head of the mounting bolt and the gripping surface of the gripping nail overlap each other in the radial direction of the chuck in the mounted state. In the above, a U-shaped bolt insertion portion including a U-shaped bolt insertion portion for a mounting bolt that opens to the outside of the grasping claw on the grasping claw mounting member side of the grasping surface forming portion and a U-shaped bolt head insertion portion is provided. A gripping jaw for a chuck, which is characterized by being provided. 2. A bolt operation hole having a diameter smaller than the bolt head diameter is formed at a position opposite to the bolt head inserted in the bolt insertion portion in the chuck rotation axis direction in a state where the bolt head is attached to the grasping claw attachment member with the attachment bolt. The grasping claw for a chuck according to claim 1, wherein: 3. The mounting bolt is a low head bolt having a low head height, and the width of the bolt head insertion portion in the chuck rotation axis line direction is set to a width corresponding to the low head bolt. Grasping claw for chuck. 4. A claw attached to a grasping claw mounting member with two mounting bolts, wherein the mounting bolt is a low head bolt,
The outer shape of the gripping claw is L-shaped and protrudes in the direction opposite to the back surface facing the gripping surface forming part toward the gripping claw mounting member, and the U-shaped bolt insertion part is located closer to the gripping claw mounting member than the gripping surface forming part. The grip surface is located at a position facing the low head bolt head on the outer side in the radial direction of the chuck when it is attached to the grip claw mounting member by the low head bolt, and the bolt head inserted in the bolt insertion part is in the chuck rotation axis direction. A gripping jaw for a chuck, characterized in that a bolt operation hole having a diameter smaller than the bolt head diameter is bored at a facing position, and a width of the bolt head insertion portion in the chuck rotation axis direction is set to a width corresponding to a low head bolt.