JPH07308840A - Workpiece holding device for lathe - Google Patents

Abstract

PURPOSE:To precisely hold a workpiece with opposite ends such as a cylindrical shape opened without deviation of its center, so as to precisely machine the workpiece even having a long length, and to always hold the workpiece in one and the same condition in order to enhance the workability for the installation and removal thereof. CONSTITUTION:A stationary head 3 which is partly inserted into an opening at one end of a workpiece W having opposite ends opened, is provided on a spindle 1 of a lathe. Meanwhile, a push head 8 having one end which is partly fitted in an opening at the other end of the workpiece W is attached to the tail stock shaft 2 of the lathe so as to be axially retractable. A thrust means such as air cylinder 7 or a spring for giving a thrust force to the push head is provided between the tail stock rod and the push head 7. Conical tapered parts 11b, 14 adapted to make press-contact with an opening edge of the workpiece are formed in the outer peripheral surfaces of the stationary head and the push head, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a workpiece holding device for a lathe for holding a workpiece between a spindle and a tailstock shaft, and more particularly,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work piece holding device suitable for a relatively long work piece having both ends opened, such as a cylindrical shape.

[0002]

2. Description of the Related Art When processing a cylindrical workpiece on a conventional lathe, as shown in FIG. 4, an inner grip type collet chuck 50 and a tailstock shaft (not shown) are provided on the main shaft (not shown) side. Heads 52 each having a conical taper surface 51 are provided on the (not) side, and the collet 53 of the collet chuck 50 is opened to the outside in the one end opening of the cylindrical work W to open one end of the work W. While gripping from the inner side, the tapered surface 51 of the head 52 is pressed against the other end opening of the workpiece W, and a constant thrust force is applied in the axial direction to fix the workpiece W,
The outer periphery was processed.

[0003]

However, according to this, the collet chuck 50 grips the workpiece W from the inside and completely restrains it. Therefore, if the accuracy of the collet chuck 50 is poor, the center of rotation O1 of the main shaft and the workpiece to be machined. There is a problem that the center O2 of the object deviates from the center O2 and the processing accuracy becomes lower as the length of the object becomes longer. Further, since the movable part of the opening / closing mechanism of the collet chuck always has friction, it is impossible to always hold the workpiece in the same state.

In view of the above-mentioned problems of the prior art, the object of the present invention is to enable a workpiece having a cylindrical shape, which is open at both ends, to be held with high precision without causing a center shift. It is to enable precision machining even when the length is long, to be able to always hold the workpiece in the same state, and to improve the workability of attachment and detachment.

[0005]

In the work piece holding apparatus according to the present invention, a fixed head, which is partially fitted into one end opening of a work piece whose both ends are open, is provided on the main shaft of the lathe, while the tailing of the lathe is provided. A push head, a part of which is fitted into the other end opening of the workpiece, is mounted on the shaft so as to be able to advance and retreat in the axial direction, and a propulsion means for applying thrust to the push head is provided between the tailstock shaft and the push head. Set up. Further, a tapered conical taper portion is formed on the outer peripheral surfaces of the fixed head and the push head so as to be pressed against the opening edge of the workpiece.

A spring or an air cylinder is used as a propelling means for applying thrust to the push head. When using an air cylinder, the push head is rotatably supported by the piston.

[0007]

In the present invention, both the fixed head on the main shaft side and the push head on the tailstock shaft side hold the work piece partially inserted into the openings at both ends of the work piece.
At this time, the push rod, which is given thrust by the propulsion means, pushes the work piece toward the fixed head side, and the tapered conical taper portions formed on the outer peripheral surfaces of both heads form the main shaft and the work piece. The function of aligning the center of the from both sides of the work piece. The work piece is held between a fixed head and a push head without being gripped by a collet chuck as in the conventional art. In addition to the fact that there is no problem in terms of stability for holding the work piece, the work piece can be easily attached and detached.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a first embodiment. In the figure,
The lathe main shaft 1 and the tailstock shaft 2 face each other on the same axis, and a fixed head 3 is fixed to the main shaft 1 via a mount 4.
An air cylinder 5 is attached to the tailstock shaft 2, and a push head 7 is rotatably supported by a bearing 8 on a piston 6 of the air cylinder 5.

In the fixed head 3, the outer diameter of the portion ahead of the collar portion 9 for fixing to the mounting base 4 is different in three steps, and a rear portion 10a having a large outer diameter, an intermediate portion 10b thinner than that, and a front portion thinner. 10c, and between them, a large and small frustoconical tapered portion, that is, a large tapered portion 11a is formed between the rear portion 10a and the intermediate portion 10b, and the intermediate portion 10b and the front portion 10c are formed. A small taper portion 11b is formed therebetween.

On the other hand, in the push head 7, the outer diameter of the portion ahead of the collar portion 12 differs in two steps, and the rear portion 1 having a large outer diameter.
3a and a small front portion 13b are provided, and one truncated cone-shaped tapered portion 14 is formed between them.
Further, the push head 7 has a shaft portion 15 on the rear side of the shaft portion 12.
The shaft portion 15 is supported by the bearing 8. The bearing 8 is a bearing hole 1 provided in the piston 6.
It is located within 6.

A spring 18 is attached to the piston rod 17 of the air cylinder 5 outside the air cylinder 5, and the piston 6 is biased rearward (on the side opposite to the main shaft side) by the spring 18. . When compressed air is pressed into the air cylinder 5 from the air port 19, the piston 6 is advanced against the spring 18.

In the configuration shown in FIG. 1, in order to hold, for example, a cylindrical workpiece W, one end of the workpiece W is fitted into the front portion 10c of the fixed head 3 so that one end of the workpiece W can be held. After being supported by the fixed head 3, the piston 6 is moved forward by air pressure to move the front portion 13b of the push head 7.
Is inserted into the opening at the other end of the workpiece W. This allows
As shown in an enlarged manner in FIG. 2, one end opening edge of the workpiece W is in pressure contact with the tapered portion 11b of the fixed head 3 and the other end opening edge is in contact with the tapered portion 14 of the push head 7, respectively. The center of W is made to coincide with the axes of the main shaft 1 and the tailstock shaft 2 by both heads 3.7.
Held in between.

In this case, since the push head 7 is given a thrust by the air pressure via the piston 6, the above-mentioned holding state can be stably maintained even when the tailstock shaft 2 moves back and forth. Further, the axial load on the workpiece W by the push head 7 can be adjusted by air pressure. Since the push head 7 is rotatably supported by the piston 6, the push head 7 is driven and rotated by the rotation of the main spindle 1 while the workpiece W is held as described above. When the air pressure in the air cylinder 5 is released, the push head 7 automatically retracts along with the piston 6 by the force of the spring 18, so that the workpiece W can be easily released. Since the fixed head 3 has the large and small tapered portions 11a and 11b, the fixed head 3 has a large corresponding range with respect to the difference in the inner diameter of the workpiece W.

Next, the second embodiment of FIG. 3 will be described. In this example, a tapered portion 2 having a truncated cone shape is provided only at the tip.
The head 3 having 0 is used, and this is fixed to the convex portion 21a of the seat plate 21 fixed to the front surface of the mounting base 4 with the screw 22. As the push head 7, a short one having a truncated cone 23 having a truncated cone shape only at the tip is used, and this is fixed to the tip of the thrust shaft 24 with a screw 25. The thrust shaft 24 is provided with a collar portion 24b at the rear end of the shaft portion 24a, and the collar portion 24b is slidably fitted in a guide hole 27 of a mounting base 26 fixed to the tailstock shaft 2. In addition, the shaft portion 24a is slidably fitted to the thrust bearing 28 fixed to the front surface of the mounting base 26. The thrust shaft 24 is biased forward (on the side of the main shaft 1) by the coil spring 29 in the guide hole 27. The coil spring 29 is guided to expand and contract by a spring guide pin 30 which is planted on the rear surface of the thrust shaft 24. Further, on the inner surface of the guide hole 27, the flange portion 24 of the thrust shaft 24 is provided.
A rotation stop pin 32 is fitted in a hole 31 provided in b to restrict rotation of the thrust shaft 24.

In the case of the second embodiment, the tapered portion 20 of the fixed head 3 and the tapered portion 23 of the push head 7 are pressed against the opening edges of both ends of the cylindrical workpiece W to hold the workpiece W. . Since the push head 7 is thrust by the spring 29, it can hold the workpiece W even if the tailstock shaft 2 moves back and forth. In addition, the fixed head 3
Also, by preparing and exchanging push heads having different outer diameters, it is possible to cope with the difference in size (inner diameter) of the workpiece W.

The workpiece W that can be held by the holding device of the present invention is not limited to the one having a cylindrical shape in its entire length, but the one having at least both ends opened (some have only holes at both ends). Including).

[0018]

The present invention has the following effects.

With a push rod in which a part of the fixed head on the spindle side and a part of the push head on the tailstock shaft side are fitted into the openings of both ends of the workpiece, and thrust is given by the propulsion means. Since the work piece is pushed toward the fixed head and the tapered parts of both heads are pressed against and held by the opening edge of the work piece, the center of the spindle and work piece is automatically aligned at the same time as holding. You can Therefore, a workpiece such as a cylindrical shape whose both ends are open can be accurately held without causing a center shift, and precision processing can be performed even if the workpiece is long. The work piece is held by being sandwiched between a fixed head and a push head without being gripped by a collet chuck as in the conventional case. Moreover, since thrust is applied to the push head, the work piece can be always held in a stable state, and the work piece can be easily attached and detached.

By applying a thrust force to the push head by the spring, the above holding state can be stably maintained even when the tailstock shaft moves back and forth.

By applying a thrust force to the push head by the air cylinder, the above holding state can be stably maintained even when the tailstock shaft moves back and forth, and the axial load applied to the workpiece by the push head. Can be adjusted by air pressure.

By rotatably bearing the push head to the piston of the air cylinder, it is possible to rotate the work piece while the work piece is held as described above as the main shaft rotates.

[Brief description of drawings]

FIG. 1 is a sectional view of a work holding device according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a state where a workpiece is held by a fixed head and a push head of the same device.

FIG. 3 is a sectional view of a workpiece holding device according to a second embodiment.

FIG. 4 is a cross-sectional view showing a held state of a work piece according to a conventional example.

[Explanation of symbols]

 W Workpiece 1 Main shaft 2 Tail shaft 3 Fixed head 5 Air cylinder 6 Piston 7 Push head 11a ・ 11b ・ 20 Tapered part of fixed head 14 ・ 23 Tapered part of push head 18 ・ 29 Spring

Claims (4)

[Claims] 1. A workpiece holding device for a lathe, which holds a workpiece between a spindle and a tailstock shaft, wherein a part of the workpiece is inserted into one end opening of the workpiece having both ends open to the spindle. While providing a head, a push head, part of which is fitted into the other end opening of the workpiece, is attached to the tailing shaft so as to be able to advance and retreat in the axial direction, and between the tailing shaft and the push head,
Propulsion means for applying thrust to the push head is provided, and a tapered conical taper portion that presses against the opening edge of the workpiece is formed on the outer peripheral surfaces of the fixed head and the push head. Object holding device. 2. The workpiece holding device for a lathe according to claim 1, wherein the propulsion means is a spring. 3. The propelling means is an air cylinder.
Workpiece holding device for the lathe described. 4. A workpiece holding device for a lathe according to claim 3, wherein the push head is rotatably supported by a piston of an air cylinder.