JPH0222166Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a holder for processing hard and brittle materials such as ceramics.

Technical Background of the Invention Figures 1 and 2 show conventional holders 1 and 1 of a grinding device, and since these holders 1 and 1 are completely the same, only the holder 1 on one side will be explained. The holder 1 is formed in a cylindrical shape, and has a recess 2 having a square cross section formed on one end surface, and a center hole 3 bored in the other end surface. The holder 1 is provided with screw holes 4, 4 that penetrate from the outer peripheral surface of each recess 2 in a direction perpendicular to the mutually orthogonal inner wall surfaces of the recess 2. Set screws 5, 5 are screwed together. In actual grinding, both ends of the workpiece 6 are fitted into the recesses 2, 2 of the holders 1, 1, and are pressed and fixed by set screws 5, 5. However, the holders 1 and 1 are attached to both ends.
The workpiece 6 with a crown attached thereto is held in the center holes 3, 3 by the main spindle 7 and the tailstock spindle 8, and is ground by the grinding wheel 9.

Problems with the Background Art Since the workpiece 6 is pressed and fixed by the set screws 5, 5, a concentrated load is applied only to the contact point of the set screws 5, 5, and the workpiece 6 is made of a hard and brittle material such as ceramics. In this case, when the setscrews 5, 5 are loosened in order to remove the workpiece 6, micro-fractures occur at the contact points of the upper female screws 5, 5. Further, during grinding, the set screws 5, 5 become loose due to the influence of rotational vibration of the grinding wheel 9 and main shaft 7, vibration at the grinding point during grinding, and high precision processing cannot be performed. Furthermore, a set screw 5,
Due to the looseness of the grinding wheel 5, the sharpness of the grinding wheel and the shape of the grinding wheel are deteriorated, resulting in a shortened life of the grinding wheel.Especially in the case of support on both centers, the rigidity is low, so the amount of uncut material becomes large.

The purpose of the invention is to provide a holder that can grind hard and brittle materials with high precision without causing destruction.

Summary of the invention A workpiece is held by a plurality of split claws, and the tapered part provided on the outer circumferential surface of the split claws is fitted into a holder having a thread on the outer periphery. The workpiece is fastened by pressing the split claw with a tightening screw that is engaged with the split mold claw.

Embodiment of the invention FIGS. 3 and 4 show an embodiment of the holder of the invention, and these figures show the holder holding a workpiece. The holder 10 is formed into a cylindrical body, and a truncated cone-shaped recess 1 is provided on one end surface of the holder 10, which is coaxial with the axis of the cylindrical body and whose diameter increases toward the one end surface.
1 is formed. Further, on the other end surface side of this holding body 10, a center hole 12 coaxial with the recessed portion 11 is provided.
is provided. The bottom of this center hole 12 is a female threaded portion 12a that passes through the recessed portion 11.
Furthermore, a male thread 13 is threaded on the outer circumferential surface of the holding body 10. Then, the recessed portion 11 of the holding body 10
Holds a fastening body consisting of a pair of mutually independent split claws 14, 14 which together form a truncated cone. That is, the split claws 14, 14 are equally spaced around the axis of the recessed portion of the holder 10, and the split claws 1 constitute part of the side surface of the truncated cone.
The outer peripheral surfaces of 4 and 14 are in sliding contact with the inner peripheral surface of the recessed portion 11. In the state where the split claws 14, 14 are recessed into the recessed portion 11, the two split claws 14, 14
There is a slight gap between them, and the split claw 1
4 and 14 partially protrude from the recessed portion 11.
Cutouts 15, 15 whose cross section perpendicular to the axis of the recessed portion 11 forms an isosceles triangle are provided on the end surfaces of the split claws 14, 14 having larger outer diameters. When the cross sections of each notch 15, 15 perpendicular to the axis of the recess 11 are aligned, it becomes a square, and the axis of the prism formed by the notch 15, 15 is coaxial with the recess 11 (see Fig. 4). ). Also, at the bottom of each recess 11 are stoppers 16 and 1.
6 is provided protrudingly. On the other hand, from the recessed portion 11 side of the holding body 10, a tightening screw 17 formed in a cup shape and having a female thread carved on the inner peripheral surface is screwed into the external thread 13 of the holding body 10. A through hole 9 coaxial with the holder 10 is bored in the bottom 18 of the tightening screw 17. The inner diameter of this through hole 19 is the recessed portion 11
It is smaller than the innermost diameter of , and larger than the diagonal line L formed by the notches 15, 15 (see FIG. 4).

To explain how to use the holder having the above configuration, a screw 17 is attached to one end of a workpiece 20 such as ceramics, which is a rectangular bar with a square cross section perpendicular to the axis at both ends. After passing through the through hole 19 so as to face the end side, the pair of split claws 14, 14 are crowned until the stoppers 16, 16 come into contact with the end surface of the workpiece 20. 1 split nail on the side of
The inner surfaces of the notches 15, 15 of No. 4, 14 are brought into sliding contact. Thus, the split claws 14, 14 attached to the workpiece 20 are fitted into the recessed portion 11 of the holder 10. Next, when the tightening screw 17 is rotated with respect to the holder 10, the split claws 14, 14 that are in contact with the bottom 18 of the tightening screw 17 are pressed in the direction of the arrow 21 parallel to the axis of the holder 10, and slightly to slide. When the fastening of the tightening screw 17 to the holder 10 is completed, the workpiece 20 is tightened by the wedge action of the split claws 14, 14 on the holder 10.
receives an evenly distributed load in a direction perpendicular to the contact surfaces of the split claws 14, 14 with the inner surfaces of the notches 15, 15. As a result, the holding body 10
is integrally connected to the workpiece 20, and the holding body 1
Recessed part 11 of 0, notch part 1 of split claws 14, 14
5, 15 and the center hole 12
are provided coaxially, so the axis of the workpiece 20 and the axis of the center hole 12 coincide. A holder is also attached to the other end of the workpiece 20 using the same procedure. Thus, the workpiece 20, which has holders attached to both ends, is clamped and held by the main shaft and tailstock shaft of the grinding device at the center hole 12 of the holder. When removing the holder from the workpiece 20 after machining, first loosen the tightening screw 17,
It is separated from the holding body 10. In this state, the split claws 14, 14 remain in close contact with the holding body 10, so a rod is inserted from the outside of the through hole 19 of the holding body 10, or a bolt is inserted into the through hole to be screwed into the through hole. The split mold claws 14, 14 are pressed in the opposite direction to separate the split mold claws 14, 14 from the holder 10.

In the above embodiment, the number of split claws is two, but the number may be increased as appropriate. For example, if the gripped parts provided at both ends of the workpiece 20 are in the shape of an equilateral triangular prism, three split claws are provided corresponding to each corner, and each split claw is provided with three split claws. What is necessary is to provide a notch portion into which the gripped portion forming the equilateral triangular prism fits tightly.

Effects of the invention The holder of the invention has the remarkable effects listed below.

(b) Since the corner of the gripped part of the workpiece is tightly fitted into the notch, the contact area between the holder and the workpiece increases, which alleviates stress concentration and grips the workpiece. For example, even in hard and brittle materials such as ceramics, there is less risk of breaking. In particular, by fitting and fixing the corners of the gripped part with the notch, it is possible to prevent damage around the axis of the workpiece without having to grip it with excessive force, which also helps in preventing destruction.

(b) The workpiece is inserted into the tapered recess of the holder and is fastened by a plurality of split claws fixed by a wedge action. This prevents rattling even if the tightening screws loosen, making it possible to perform high-precision grinding. Moreover, as a result of being able to prevent the occurrence of backlash, the sharpness of the whetstone is improved and the life of the whetstone can be extended.

(c) Since the stopper supports the workpiece in contact with the end surface, the stopper not only acts as a support due to the pressing force of both centers, but also supports the stopper even when the roughness of both ends of the workpiece is poor. The workpiece is elastically slightly deformed in accordance with the undulations of the end surface of the workpiece, so that the workpiece can be held reliably. In particular, when the workpiece is made of hard and brittle materials such as ceramics, the elastic deformation is extremely small compared to metals, and the roughness of the end surface tends to vary, making it difficult to perform chucking stably. Applying the invented retainer will eliminate such problems.

(d) Since the holding body has a center hole, it not only becomes possible to perform work on both centers, but also contributes to improving centering accuracy during grinding.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main parts of a conventional holder;
The figure is a sectional view taken along the line X-X' in Fig. 1, Fig. 3 is a sectional view of main parts showing the structure of the holder of the present invention, and Fig. 4 is a sectional view taken along the line X-X' of Fig. 1.
It is a sectional view taken along the line Y-Y' in the figure. 10... Holding body, 11... Recessed portion, 12... Center hole, 13... Male thread, 14, 14... Split claw, 15, 15... Notch, 16... Stopper,
17...Tightening screw.

Claims (1)

[Claims for Utility Model Registration] A holder having the following configuration, characterized in that both ends in the axial direction hold a cylindrical workpiece formed in a prismatic gripped part. (a) A cylindrical body is formed, a thread is threaded on the outer peripheral surface of the cylindrical body, and a conical recessed portion whose diameter increases toward the one end face is provided on one end face of the cylindrical body. A holder provided coaxially with the axis and having a center hole provided coaxially with the recessed portion on the other end surface side of the cylindrical body. (b) A notch that has a tapered surface that slides into the recessed portion of the holder, is independently arranged around the axis of the recessed portion of the holder, and is in close contact with a corner of the gripped portion of the workpiece. a plurality of split-type claws, each of which is provided with a stopper protruding from the cutout portion and comes into contact with an end surface of the workpiece; (c) Formed in a cup shape, the bottom of the cup shape is provided with a through hole through which the workpiece is inserted, and the inner peripheral surface of the cup shape is provided with a male thread threaded on the outer peripheral surface of the holder. A female thread is threaded to be engaged with the holding body, and the threaded engagement of the male thread of the holding body and the female thread presses the plurality of split claws against the recessed portion of the holding body through the bottom of the cup shape. A tightening screw that holds and fixes the workpiece to the split claw.