JP2002239819A - Collet chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a collect chuck having holding precision and durability higher than the conventional ones. SOLUTION: The collet chuck 30 has a fitting base part 31, a holding part 32 and an elastic deforming part 33 provided between them. The elastic deforming part 33 is formed in a flat plate shape. Consequently, a state of elastic deformation hardly changes even when driving stress is slipped in the circumferential direction and local deformation of the elastic deforming part 33 is prevented, and accordingly, the holding precision and the durability are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collet chuck, and more particularly, to a collet chuck structure suitable for gripping a thin shaft.

[0002]

2. Description of the Related Art In general, a collet chuck is mounted on a spindle end of a machine tool and is used for gripping a work such as a tool or a workpiece. FIG. 4 shows an example of the collet chuck. The collet chuck 10 has a cylindrical fitting base 11 fitted and positioned at a spindle end of a machine tool, a gripping part 12 provided at a distal end for gripping a work, a fitting base 11 and a gripping part. And an elastic deformation portion 13 provided between the elastic deformation portion 13 and the elastic deformation portion 13. The gripping portion 12 and the elastic deformation portion 13 are formed by a plurality of slits 1 formed at a plurality of locations around the axis.
Oa causes a plurality of branches (three in the illustrated example), and the grip portion 12 moves inward and outward in the radial direction mainly due to the elasticity of the elastic deformation portion 13. The outer peripheral surface of the grip portion 12 is frusto-conical outer peripheral inclined surface 12a inclined in the axial direction is formed in the center of the grip portion 12 is gripped surface 12b for gripping the workpiece is formed.

The above-mentioned collet chuck 10 is used in a state where it is inserted into a cylindrical driving member 20 (indicated by a chain line in the drawing) provided in a machine tool. This drive member 20
Has an inner peripheral inclined surface 20a facing the outer peripheral inclined surface 12a. The gripping mechanism (not shown) provided in the machine tool moves the drive member 20 in the axial direction, so that the inner peripheral inclined surface 20a presses the outer peripheral inclined surface 12a of the collet chuck 10 inward, and the elastic deformation portion 13 Since the gripping portions 12 move radially inward due to elastic deformation, the gripping surface 12b can grip a workpiece (not shown).

[0004]

By the way, when the driving member 20 applies a stress radially inward to the grip portion 12 as described above, the distal end side of the elastic deformation portion 13 bends radially inward. However, the conventional collet chuck 10
In FIG. 5, as shown schematically in FIG.
Is obtained by dividing the cylindrical shape, so that the outer surface 13a
The inner surface 13b and the inner surface 13b both have a shape curved in the circumferential direction and formed of a cylindrical surface. When stress is applied to the elastically deforming portion 13 having such a curved shape in the radial direction via the grip portion 12, the elastically deforming portion 13 has a ridge line as shown by a dashed line in FIG. 5, and a stress is applied to the central portion in the axial direction. There concentrate.

[0005] When such a folded state occurs, FIG.
As shown in (a), when a stress is applied to the center in the width direction on the distal end side of the elastic deformation portion 13, the elastic deformation portion 13 is elastically deformed in a substantially straight middle bent shape in the axial direction, but the inner peripheral inclined surface of the drive member 20. As shown in FIG. 7B or FIG. 7C, due to the positional relationship between the gripper 20a and the outer peripheral inclined surface 12a of the gripper 12 and the processing accuracy of both, stress is applied to the left and right sides in the width direction on the distal end side of the elastically deformable portion 13. Is slightly displaced, the elastically deforming portion 13 is obliquely deformed, and as a result, the grip portion 12 is in a tilted posture.
There is a problem in that the gripping accuracy is reduced, leading to a misalignment of the work and a reduction in the gripping force.

In particular, when trying to grip a shaft having a small diameter of about 0.3 to several mm, if the gripping accuracy is slightly reduced, the shaft is greatly inclined. When small holes are drilled with a small diameter drill, the drill is likely to break. Therefore, increasing the gripping accuracy is extremely important in micromachining.

When the collet chuck 10 is used for a long period of time, the elastic deformation portion 13 repeatedly elastically deforms into the above-described bent state, thereby causing metal fatigue or the like in the bent portion where stress is concentrated. However, there arises a problem in durability, such as a change in elastic characteristics, resulting in deterioration of deformation accuracy (reproducibility of deformation).

Accordingly, the present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a collet chuck capable of obtaining a higher gripping accuracy than the conventional one by stabilizing the mode of the elastic deformation of the elastic deformation portion. To provide.
Another object of the present invention is to provide a collet chuck having higher durability than before.

[0009]

In order to solve the above-mentioned problems, a collet chuck according to the present invention is provided with a base portion to be positioned, a grip portion for gripping a work, and provided between the base portion and the grip portion. A collet chuck having an elastically deformable portion, wherein an outer edge or an inner edge in a cross section orthogonal to the axial direction of the elastically deformable portion is formed to be flat.

Since the outer edge or inner edge of the elastically deformable portion in a cross section orthogonal to the axial direction is formed flat, unlike the conventional elastically deformable portion in which both the outer surface and the inner surface are curved, a portion which receives a driving stress. Is slightly changed, the deformation direction hardly changes, and high gripping accuracy can be obtained. In addition, since stress is not easily concentrated on a specific portion of the elastically deformable portion and local deformation is hardly generated, fatigue of the material is hardly generated, and durability is improved.

In the present invention, it is preferable that both the outer edge and the inner edge of the cross section are formed flat.
As a result, both the outer surface and the inner surface of the elastically deformable portion are formed to be flat in the circumferential direction, so that the deformation direction is more difficult to shift from the radial direction, and stress concentration and local deformation are further suppressed. Therefore, the gripping accuracy can be further improved, and the durability is further improved.

In the present invention, it is preferable that the outer edge and the inner edge of the cross section are formed in parallel. As a result, since the elastically deformable portion has substantially the same thickness around the axis, the stress distribution and the deformation distribution seen in the circumferential direction around the axis become more uniform, so that the gripping accuracy and durability are further improved. be able to.

Here, the section in which the outer edge and the inner edge are parallel is defined as:
It refers to various shapes, such as a square, a rectangle, a parallelogram, and a trapezoid, in which an outer edge corresponding to the contour of the outer surface of the elastically deformable portion is parallel to an inner edge corresponding to the contour of the inner surface of the elastically deformable portion. According to this, since the elastically deformable portion is not curved around the axis, the deformation direction is unlikely to change even if the portion that receives the driving stress is displaced when the elastically deformable portion is deformed inward or outward in the radial direction. It is possible to obtain gripping accuracy. In addition, since stress is not easily concentrated on a specific portion of the elastically deformable portion and local deformation is hardly generated, fatigue of the material is hardly generated, and durability is improved.

In the present invention, it is preferable that the elastically deforming portions have substantially the same cross-sectional shape along the axial direction. Since the elastic deformation portion has substantially the same cross-sectional shape along the axial direction, the driving stress can be received more uniformly over the entire axial direction of the elastic deformation portion. Since it is uniformly elastically deformed, gripping accuracy and durability can be further improved.

In the present invention, it is preferable that the elastic deformation portion is formed in a parallel plate shape. Since the elastically deforming portion is formed in a parallel plate shape, extremely high gripping accuracy and high durability can be obtained.

In each of the above-mentioned inventions, as a more specific configuration, there may be a case where the plurality of gripping portions and the elastically deforming portions are branched off from the fitting base. Also,
The distal end side of the elastic deformation portion or the grip portion may have an inclined surface inclined with respect to the axial direction.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a collet chuck according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing the collet chuck 30 of the present embodiment, FIG. 2 is a longitudinal sectional view of the collet chuck 30 of the present embodiment, and FIG. 3 is a front view of the collet chuck 30 of the present embodiment as viewed from the gripping portion side ( FIG. 4B is a cross-sectional view illustrating a state of FIG. 4A and a section taken along a plane orthogonal to the axis at the elastic deformation portion.

The collet chuck 30 has a cylindrical fitting base 31, a plurality of gripping portions 32 and an elastically deforming portion 33 branched by a slit 30a, as in the above-mentioned conventional example. Here, the fitting base portion 31 and the grip portion 32 are completely the same as the conventional structure, and the grip portion 32 has an outer peripheral inclined surface 32a.
And a gripping surface 32b.

In the present embodiment, the elastic deformation portion 33
It is formed in a parallel plate shape having an outer surface 33a and an inner surface 33b which are parallel to each other and flat, and a cross-sectional shape orthogonal to the axial direction shown in FIG. 3B is substantially rectangular, and has a constant cross-sectional shape in the axial direction. It has become.

FIG. 6 schematically shows the elastic deformation portion 33 of the present embodiment. Since the elastically deformable portion 33 is formed in a parallel plate shape extending in the axial direction, as shown by a dashed line in the drawing, the outer peripheral inclined surface 32a of the grip portion 32 is the same as that shown in FIG. When a stress is applied radially inward of the elastic deformation portion 33, the entire portion of the elastically deformable portion 33 is curved such that the portion near the distal end is directed radially inward. In this case, the stress is not distributed and bears over the entire elastic deformation portion 33 in the axial direction (that is, the length direction), unlike the conventional elastic deformation portion 13 shown in FIG. The degree of curvature is substantially uniform throughout.

In this embodiment, FIG.
As shown in FIG.
When a stress is applied from the gripping portion 32, the elastically deforming portion 33 is bent according to a contact state between a driving member (not shown) and the grip portion 32, as shown in FIG. 8B and 8C, even if the stress balance that is applied is deviated in the circumferential direction around the axis, it is straight inward in the radial direction almost similarly to the case shown in FIG. 8A. Bend. This is the elastic deformation part 3
This is because, unlike the conventional elastically deformable portion 13, the portion 3 is formed in a parallel plate shape and can be deformed as it is in the stressed direction (ie, radially inward) even if the stressed position is slightly shifted.

In this embodiment, as described above, the elastically deformable portion 33 is provided even if the portion of the grip portion 32 that receives the stress is slightly displaced in the circumferential direction due to the abutting condition of the inclined surfaces of the drive member and the grip portion 32. Is deformed almost straight inward in the radial direction, so that the grip portion 32 moves almost straight inward in the radial direction, and as a result, the gripping surface 32b can grip the work in the originally intended posture. Therefore, the gripping accuracy of the collet chuck 30 is much higher than that of the conventional collet chuck.

Further, as described above, the flat elastic deformation portion 3
3 can be uniformly curved over the whole, so that the stress caused by the driving member does not concentrate on a specific portion, and as a result, the elastic deformation portion 33 does not locally deform significantly. In addition, since metal fatigue is less likely to occur, and the elastic characteristics of the elastically deformable portion 33 are less likely to be deteriorated, the gripping accuracy is less likely to deteriorate, so that the durability of the collet chuck can be increased.

It should be noted that the collet chuck of the present invention is not limited to the illustrated example described above, and it is a matter of course that various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the elastic deformation portion 33 has a parallel plate shape, that is, the outer surface 33a and the inner surface 33b of the elastic deformation portion 33 are both flat when viewed in the circumferential direction around the axis, and are parallel to each other. The outer surface 33a and the inner surface 33b are formed to have the same thickness in the circumferential direction, have a constant cross-sectional shape when viewed in the axial direction, and to be flat when viewed in the axial direction. However, the present invention solves the problem caused by the conventional elastically deformable portion having the outer surface and the inner surface both having a curved shape in the circumferential direction around the axis. If at least one of the inner surfaces 33b has a flat shape when viewed in the circumferential direction around the axis, advantageous effects can be obtained from the viewpoint of gripping accuracy and durability. Of course, both the outer surface 33a and the inner surface 33b are preferably flat when viewed in the circumferential direction. In this case, the outer edge 33b and the inner surface 33b
It is preferable that the inner edge indicating the outline of the cross section has a cross-sectional shape parallel to each other. In these cases, the elastically deforming portion 3
The overall shape of 3 may be curved in the axial direction. However, since the elastically deformable portion 33 has substantially the same cross-sectional shape in the axial direction, the entire elastically deformable portion 33 is deformed, so that stress concentration hardly occurs, and local deformation hardly occurs. It becomes more preferable from the viewpoint of durability.

The above-mentioned collet chuck has three slits and three grip portions.
The number of grips is not limited to three.

Furthermore, the above-mentioned collet chuck is configured to grip the work from the outside, but the collet chuck can be similarly applied to a chuck of a lining type in which the work is gripped by the gripping portion whose diameter is increased from the inside. It is possible.

[0027]

As described above, according to the present invention, it is possible to improve the gripping accuracy of a workpiece such as a tool or a workpiece, and also to improve the durability.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a collet chuck according to the present invention.

FIG. 2 is a longitudinal sectional view of the embodiment.

FIG. 3 is a front view (a) of the same embodiment and a cross-sectional view (b) showing a state cut along a plane orthogonal to the axial direction.

FIG. 4 is a perspective view showing an example of a conventional collet chuck.

FIG. 5 is an explanatory view schematically showing an elastically deformable portion of a conventional collet chuck and its deformation mode.

FIG. 6 is an explanatory diagram schematically showing an elastic deformation portion and a deformation mode of the embodiment.

FIG. 7 is an explanatory view schematically showing a state of a deformation mode of an elastic deformation section of a conventional collet chuck viewed from an outer peripheral side;
(C).

FIGS. 8A to 8C are explanatory diagrams schematically illustrating a state in which the elastic deformation portion of the embodiment is viewed from the outer peripheral side.

[Explanation of symbols]

 REFERENCE SIGNS LIST 30 collet chuck 31 fitting base 32 gripping portion 32a outer peripheral inclined surface 32b gripping surface 33 elastic deformation portion 33a outer surface 33b inner surface

Claims (5)

[Claims] 1. A collet chuck having a base to be positioned, a gripper for gripping a work, and an elastically deformable part provided between the base and the gripper, wherein the elastically deformable part is provided. An outer edge or an inner edge in a cross section orthogonal to the axial direction of the collet chuck is formed to be flat. 2. The collet chuck according to claim 1, wherein both the outer edge and the inner edge of the cross section are formed flat. 3. The cross section according to claim 1, wherein the outer edge and the inner edge of the cross section are formed in parallel.
Collet chuck described in 1. 4. The collet chuck according to claim 1, wherein said elastically deformable portions have substantially the same cross-sectional shape along the axial direction. 5. The collet chuck according to claim 1, wherein said elastically deforming portion is formed in a parallel plate shape.