JPH0440804Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a chuck that grips a workpiece at two places, front and back.

[Conventional technology]

Generally, when cutting a long bar material using a lathe or the like, a chuck is attached to a headstock provided near the cutting edge so that the chuck firmly grips the workpiece.

Generally, when gripping a workpiece, the machining accuracy will be improved if the workpiece is gripped as strongly as possible. A collect chuck is sometimes used for this purpose.

[Problem that the invention attempts to solve]

However, in order to support a long material such as a bar, it is conceivable to support the bar at two points in order to prevent vibration. In such a case, if two chucks are operated strongly at the same time, one of them will become hard and tighten first, and the other chuck will become loose. To solve this problem, it is necessary to use one chuck to strongly tighten the long material, and the other chuck to tighten the long material in a cushioning manner. Conventionally, such a collection chuck did not exist.

The present invention aims to provide such a chuck.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention includes a holder held on a fixed frame, an actuation cylinder rotatably held within the holder, a piston formed in the actuation cylinder, and a piston formed in the actuation cylinder. A first collet that is provided in a collet holding cylinder and is expandable and retractable and connected to one end of the piston and moves integrally with the piston; a first collet that is expandable and retractable at the same time as the first collet that is connected to the other end of the piston and moves integrally; and a shock absorber provided in the collet holding cylinder that operates to buffer the workpiece in the first collet as the piston is actuated. The configuration is adopted.

The shock absorber may be a buffer chamber supplied with pressure oil, or may be a coil spring.
Furthermore, if the body of the collet is made of a soft material, the lead groove provided therein may also be used.

[Effect]

Actuation of the cylinder causes the first and second collects to simultaneously grip the workpiece.

Since the second collect is not equipped with a shock absorber,
Although the material is strongly gripped, the first collet grips the material in a cushioning manner by means of a damping device.

Therefore, the material is properly gripped by both collects without play in one of the collects, vibration is prevented, and machining accuracy is improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

This chuck has a chuck portion that grips the bar, which is a long material, in a cushioning manner, and a chuck portion that grips the bar material, which is a long material, in a non-cushioning manner.

In Fig. 1, the first
The chuck portion 1 is attached to the left end of a spindle 43 rotatably held by a headstock 40 in the drawing.

The spindle 43 is rotatably held on the headstock 40 by bearings 41 and 42, and a pulley 45 is connected to the left end of the spindle by belts b ₀ , 42 .
It is designed to be rotated by b ₀ ,...b ₀ .

At the right end of the spindle 43 held by the headstock 40, there is provided a second chuck portion 46 that holds the bar material in a non-buffering manner.

The non-cushioned holding chuck 46 has a casing 48. This casing 48 is fixed to the spindle 43 by bolts 49. A second collet 51 for non-buffering holding is provided within the casing 48.

This second chuck portion 46 is for holding a long material such as a rod in a non-cushioned or rigid manner.

The first chuck part 1 has an actuation cylinder 12, which has a large diameter part 1.
2a and a collet holding cylindrical portion 12b connected to the large diameter portion 12a. The large diameter portion 12a
A piston 13 is provided inside, and this piston 1
A threaded portion 13a is formed at the left end in the drawing of 3, and this threaded portion 13a engages with the right end in the drawing of the expandable and contractible first collet 14 provided in the collet holding cylindrical portion 12b. .

The collet holding cylindrical portion 12b is rotatably held by a holder 15 held by a fixed frame, and this holder 15 is formed with ports 16 and 17 for supplying pressure oil. An operating sleeve 18 is provided between the outer circumferential surface of the first collet and the inner circumferential surface of the collet holding cylindrical portion 12b, and an inclined surface 18a is provided on the inner circumferential surface of the front end of the operating sleeve 18.
is formed, and a stepped portion 18b is formed at the rear end portion of the outer periphery. The inclined surface 18a cooperates with the outer peripheral inclined surface 14a of the first collet 14 to expand and contract the first collet 14.

Inclined surface 48 in the second chuck portion 46
a, 51a are formed in the same direction as the inclined surfaces 14a, 18a in the first chuck portion 1.

The first collet 14 is inserted into the collet holding cylinder part 12b as the piston 13 operates.
A buffer device is provided which operates to buffer the workpiece material.

That is, a step 12c is formed on the inner circumferential surface of the collet holding cylindrical portion 12b opposite to the step 18b of the operating sleeve, and both steps 18b, 1
A buffer chamber _r1 is formed between 2c. This buffer chamber
One end of an oil passage P ₂ formed within the wall thickness of the working cylinder 12 is connected to r ₁ . This oil road
_P2 is connected to the working chamber _d2 on the left side in the figure of the large diameter portion. An oil passage P ₁ is connected to the working chamber d ₁ on the right side of the piston 13, and the tip of this oil passage P ₁ is connected to the port 16. Oil from this port 16 flows into the oil passage _P1 via a groove _a1 formed in an annular shape on the inner circumferential surface of the holder 15, while oil from the port 17 flows through the holder 15. The oil flows into the oil passage P 2 through a groove a ₂ formed on the inner circumferential surface of the oil passage P ₂ . This holder 15 is adapted to rotatably hold the collet holding cylindrical portion 12b via bearings b, b, and the annular grooves a ₁ and a ₂ are formed on the inner peripheral surface of the holder. In addition, annular grooves a ₃ and a ₄ are provided, and oil flows into the drain casing 20 through the annular grooves a ₃ and a ₄ and is discharged to the outside through the drain pipe 21 connected to the drain casing 20. Ru.

Next, the operation of the chuck having the above structure will be explained.

The long material to be processed is collected from the left side in the diagram.
4. It is inserted through the spindle 43 and the collet 51, and its tip reaches the tool rest. Figure 1 shows collection 1
4 and 51 show the state in which the elongated material is released.

Next, pressure oil is injected from the port 17 into the left working chamber d ₂ via the oil passage P ₂ and flows into the buffer chamber r ₁ . At this time, the piston 13
moves to the right in the figure, thereby causing the first collet 14 of the first chuck portion 1 to move to the right and clamp the elongated material. At the same time, the movement of the piston 13 causes the second collet 51 of the second chuck portion 46 to move to the right in the figure via the connecting cylinder 44 slidably provided within the spindle 43.
As a result, the second collector 51 of the second chuck portion 46 is also connected to the first collector of the first chuck portion 1.
Together with the collet 14, the outer peripheral surface of the elongated material is tightened.

The second collect 5 of the second chuck portion 46
1 holds the leading end portion of the elongated material firmly and in a non-cushioning manner, while the first collet 14 of the first chuck portion 1 grips the middle portion of the elongated material in a cushioning manner.

That is, when tightening the first collet 14, pressure oil is also supplied to the buffer chamber _r1 , so that the first collet 14 is tightened by both the inclined surfaces 14a, 18a and the buffer chamber _r1. The middle part of the long material is gripped while being affected by the pressure oil. As shown in FIG. 1, the area of the buffer chamber r ₁ is smaller than the area of said piston, so that the actuating sleeve 18 is moved with less force than the force exerted on the second collet and thus dampingly You will have to press collect.

When releasing the long material, pressure oil is supplied to the right working chamber _d1 through the port 16 and the oil passage _P1 .
The first collet 14, the connecting cylinder 44, and the second collet 51 may be moved to the left in the figure.

In this way, the second chuck part 46 firmly holds the long material, and the first chuck part 1, which is provided at a constant distance from this chuck part 46, grips the long material in a cushioning manner. Even if the material is rotated at high speed, vibrations can be sufficiently prevented, and one of the first and second chuck parts 1, 46 will not play.

In addition, in FIG. ₁ , pressure oil is supplied to the buffer chamber _r1 , but as shown in FIG. good. In this case, the oil path P ₂
An oil passage P ₃ is provided instead, and this oil passage P ₃ is not connected to the buffer chamber S.

Further, as shown in FIG. 3, the operating cylinder 1
8 and buffer chambers r ₁ and r ₂ are not provided, the first collet 14 is directly inserted into the collet holding tube 12b, and the tip of the holding tube 12b has an inclined inner circumferential surface and an inclined outer circumferential tip of the collet 14. Alternatively, a lead groove 30 or the like may be provided directly in the body of the first collet 14 instead of the buffer chamber. In this case, the body of the first collect needs to be made of a relatively soft metal, and the lead groove 30 allows the body of the first collect 14 to expand and contract as the piston 13 moves. It performs a similar function.

In this way, the buffer chamber _r1 is provided and the first collector is operated as a buffer by pressure oil, or the spring S is provided in the buffer chamber _r2 as shown in FIG. If the body of the collet 14 is configured to be expandable and retractable, the first collet 14 can grip the workpiece in a cushioning manner.

[Effect of idea]

Since the present invention is configured as described above, the material can be gripped more strongly by the second collect, and can be gripped by the first collect in a cushioning manner. Therefore, the material can be properly gripped by both collets without play in one of the collets, vibration can be prevented, and machining accuracy can be improved.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the chuck of the present invention applied to processing a long material, Fig. 2 is a longitudinal cross-sectional view of another embodiment of the present invention, and Fig. 3 is a longitudinal cross-sectional view of another embodiment of the present invention. FIG. 3 is a longitudinal cross-sectional view showing an example. DESCRIPTION OF SYMBOLS 1...First chuck part, 12...Working cylinder, 13...Piston, 14...First collector, 15...Holding body, 18...Working cylinder, r ₁
...Buffer chamber, S...Spring, 30...Lead groove, 46...Second chuck portion, 51...Second collector.

Claims (1)

[Claims for Utility Model Registration] 1. A holding body held in a fixed frame, an actuation cylinder rotatably held within this holding body, a piston formed in this actuation cylinder, and a collet holding cylinder of said actuation cylinder. a first collet which is provided within the piston and is expandable and retractable and connected to one end of the piston and moves together; and a first collet which is expandable and retractable at the same time as the first collet which is connected to the other end of the piston and moves together. Second
a collet, and a buffer device provided in the collet holding cylindrical portion that operates to cause the first collet to buffer the workpiece as the piston operates. Check. 2. The shock absorber includes an actuation sleeve that is slidably provided between the first collet and the collet holding cylinder and has an inner peripheral inclined surface that cooperates with an outer peripheral inclined surface of the first collet. and a buffer chamber for receiving pressurized oil having an area smaller than that of the piston, which is formed between the operating sleeve and the collet holding cylinder part. The check described in paragraph 1. 3. The shock absorbing device includes an actuation sleeve that is slidably provided between the first collet and the collet holding cylindrical portion and has an inner peripheral inclined surface that cooperates with an outer peripheral inclined surface of the first collet. 2. The chuck according to claim 1, further comprising a buffer spring interposed between the operating sleeve and the collet holding cylinder. 4. Utility model registration claim 1, characterized in that the shock absorbing device is constituted by an extensible part formed in the body of the first collet and can be slightly expanded and contracted in the axial direction of the body. Check the section.