JP2001047337A - Inside surface machining jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate generation of a chucking distortion and perform accurate machining for the inner surface of a work in a thin ring shape using a lathe, etc. SOLUTION: A fitting recess 2d to admit fitting of the outer surface of a work W in a tight contact condition is formed at the forefront face of a jig body 2 to be grasped by pawls 4 of a chuck in a lathe, etc., and from its outside, a cap 3 is fitted in screw engagement in such a way as put on, and the work W is pressed in the axial direction and held. Through a hole 3k penetrating the cap 3, the inner surface of the work W is machined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner surface processing jig suitable for inner surface processing of a thin ring-shaped work, for example, in lathe processing.

[0002]

2. Description of the Related Art Conventionally, as a holding jig for holding a workpiece when the inner surface of a ring-shaped workpiece is subjected to lathe processing, for example, a jig as disclosed in JP-A-7-1209 is known.
As shown in FIG. 3, this jig divides a disk-shaped plate 52 attached to an end face of a chuck 51 into three parts, and a fan-shaped claw similarly divided into three parts with a work W interposed therebetween on the front surface of the disk-shaped plate 52. With the body 53 attached, the fan-shaped claw body 53 expands and contracts in the radial direction by the chucking operation, and the work W can be clamped and fixed in the radial direction by the fan-shaped claw body 53.

[0003]

However, for example, when the work has a thin ring shape, the method of fixing the work by tightening it in the radial direction requires the work to have precise inner diameter accuracy and roundness. In such a case, there is a problem that chuck distortion occurs and processing cannot be performed with desired accuracy.

Accordingly, an object of the present invention is to provide a processing jig capable of performing accurate inner surface processing without causing chuck distortion even in a work having a thin ring shape.

[0005]

According to the present invention, a work holding portion is provided at a distal end portion of a jig body whose base end is gripped by a chuck portion such as a lathe. An inner surface processing jig configured to machine an inner surface of a workpiece to be held by a processing tool, wherein a work holding portion is formed at a front end portion of the jig main body and is fitted to an outer surface of the work in a closely fitting state with a fitting recess. In this case, an end face pressing means for pressing an end face of the work to be fitted in the axial direction is used.

If the work is fitted in the fitting recess of the jig body in a close contact state, and the work is pressed and held in the axial direction by the end face pressing means, the work is clamped in the radial direction so that chuck distortion occurs. Troubles can be prevented. For this reason, the fitting recess is formed in accordance with the outer diameter of the work so as to fit closely to the outer surface of the work.

The end face pressing means may be any means as long as it does not apply a force in the radial direction of the work and exerts a pressing force only in the axial direction. A chuck claw or the like utilizing a spring force or the like may be provided on the periphery of the member, or a cap member or the like may be screwed and fixed.

According to a second aspect of the present invention, the end surface pressing means is a cap member which can be screwed to the outer peripheral thread portion on the distal end side of the jig main body and has a through hole larger than the inner diameter of the work at the center.

If such a cap member is screwed into the outer peripheral thread portion of the jig main body to press and hold the work in the axial direction, the pressing force against the work becomes uniform and processing can be performed with higher precision.

[0010]

Embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a sectional view of a work holding mechanism of a processing jig according to the present invention, and FIG. 2 is an exploded perspective view of the same.

The inner surface processing jig according to the present invention is configured as, for example, an inner surface finishing processing jig of a valve body ring which is a part of a vehicle component, and the valve body ring is a thin ring-shaped work. For this reason, the problem that chucking distortion occurs when machining with conventional lathe finishing and machining with desired roundness cannot be achieved is improved.

That is, the inner surface processing jig holds the work W by a work holding mechanism 1 such as a lathe shown in FIGS. 1 and 2, and when working the inner surface of the work W with a processing tool (not shown). The workpiece holding mechanism 1 includes a jig body 2 that is capable of machining without causing chuck distortion.
And a cap member 3, and a fitting recess 2 d is formed in the tip end surface of the jig main body 2, and the fitting recess 2 d and the cap member 3 constitute a work holding portion.

The base end of the jig body 2 is a small-diameter portion 2s which is gripped by a raw claw 4 of a chuck portion such as a lathe, and an outer peripheral thread 2n is formed on the outer peripheral portion on the distal end side.

The fitting recess 2d has a large diameter on the inlet side substantially matching the outside diameter of the work W, and a stepped recess on the inside of the fitting recess 2d. The outside diameter of the work W is closely attached to the large diameter part. The large-diameter portion has a depth t that is shorter than the length s of the workpiece W, while allowing the fitting to be performed.

The cap member 3 has an inner peripheral thread 3n which can be screwed to the outer peripheral thread 2n of the jig main body 2, and a through hole 3k having a diameter larger than the inner diameter of the work W and smaller than the outer diameter. When screwed into the outer thread 2n of the jig body 2, the end face of the work W can be pressed and held in the axial direction.

In the work holding mechanism 1 as described above,
The small-diameter portion 2s on the base end side of the jig main body 2 is gripped by the raw claws 4 of the chuck portion, and the work W is fitted into the fitting concave portion 2d on the distal end side. Then, the cap member 3 is tightened to fix the work W. Then, the outer surface of the work W comes into close contact with the inner surface of the fitting concave portion 2d, and is pressed in the axial direction by the cap member 3 to be sandwiched.

Next, a processing tool (not shown) is advanced through the through hole 3k of the cap member 3 to process the inner surface of the work W. Since the held work W does not receive a pressing force in the radial direction, It is processed without chuck distortion and high-precision processing is possible.

By the way, when the inner surface is machined by the above-mentioned method, the conventional lathe machining, which could not be machined with an accuracy of roundness of 20 to 30 μ or more, can be machined with an accuracy of about 5 μ, For example, it has become possible to sufficiently satisfy the processing accuracy required for a roundness of 10 μ or more.

The present invention is not limited to the above embodiment. Those having substantially the same configuration as those described in the claims of the present invention and exhibiting the same operation and effect belong to the technical scope of the present invention. For example, means other than the cap member 3 may be used as the end face pressing means for pressing the end face of the work W in the axial direction.

[0020]

As described above, the inner surface processing jig according to the present invention is used as a work holding portion when processing the inner surface of a work.
The fitting recess formed in the jig main body and the end face pressing means for pressing the end face of the workpiece to be fitted in the axial direction, and the outer surface of the workpiece is fitted into the fitting recess in a close contact state and is processed. In addition, it is possible to prevent a problem that chuck distortion occurs due to tightening in the radial direction, and it is possible to enhance processing accuracy such as roundness. Further, when the end face pressing means is a cap member which can be screwed to the outer peripheral thread portion on the tip end side of the jig body, the pressing force against the work becomes uniform, and the processing can be performed with higher precision.

[Brief description of the drawings]

FIG. 1 is a sectional view of a work holding mechanism of a processing jig according to the present invention.

FIG. 2 is an exploded perspective view of the same.

FIG. 3 is an explanatory view of a conventional work holding mechanism.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Work holding mechanism, 2 ... Jig main body, 2d ... Fitting concave part,
2n: outer peripheral thread portion, 3: cap member, 3k: through hole.

Claims (2)

[Claims] 1. A work holding portion is provided at a distal end portion of a jig body whose base end is gripped by a chuck portion such as a lathe, and the inner surface of a work held by the work holding portion is processed by a processing tool. An inner surface processing jig, wherein the work holding portion is formed at a front end portion of the jig body and is fitted into an outer surface of the work in a close contact state; An inner surface processing jig comprising an end surface pressing means for pressing. 2. The inner surface processing jig according to claim 1, wherein said end surface pressing means is capable of being screwed to an outer peripheral thread portion on a distal end side of said jig main body, and penetrates at a central portion thereof to be larger than the inner diameter of the work. An inner surface processing jig, which is a cap member having a hole formed therein.