JP2001219310A - Collet and tightening nut of collet chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a collet and a tightening nut of a collet chuck capable of efficiently transmitting a force produced by tightening the tightening nut to the collet so that the collet can be contracted effectively so as sufficiently develop a tool holding force. SOLUTION: This collet chuck comprises a chuck main body 11 having a converged taper hole 15, a collet 12 having a first taper surface 16 fitted into the converged taper hole 15, and a tightening nut 13 connected detachably to the collet 12 and screwed to the chuck main body 11. An annular groove 18 is formed in the front end outer peripheral surface of the collet 12, a second taper surface 20 is formed in the peripheral side walls of the annular groove 18 adjacently to the first taper surface 16, and an annular projected part 26 having a taper surface 27 engaged with the annular groove 18 of the collet 12 and capable of being overlapped with the second taper surface 20 is formed in the front end inner peripheral surface of the tightening nut 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collet chuck for attaching a tool such as a drill and an end mill to a rotating spindle of various machine tools.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 4, a collet chuck has a chuck body 2 having a deep tapered hole 1 at a distal end thereof and a tapered surface 3 fitted into the deep tapered hole 1. An annular groove 6 having a U-shaped cross section is provided on the outer peripheral surface of the front end portion of the collet 4 and includes a collet 4 having a diameter and a fastening nut 5 detachably connected to the collet 4 and screwed to the chuck body 2. Is formed on the inner peripheral surface of the front end portion of the tightening nut 5. An annular convex portion 7 that engages with the annular groove 6 of the collet 4 is formed. By tightening the tightening nut 5, the annular convex portion 7 is formed. The collet 4 is pressed into contact with the peripheral side wall 6a of the annular groove 6 of the collet 4 so that the collet 4 is pressed into the deep tapered hole 1 of the chuck body and the diameter thereof is reduced at the same time, and the tool T inserted in the collet 4 is gripped. It is designed to be fixed.

The conventional collet chuck shown in FIG. 5 is the same as the chuck shown in FIG. 4 except that a tapered surface 8 adjacent to an annular groove 6 is formed at the front end of the collet 4 and the tightening nut 5 is formed. An annular projection 9 different from the annular projection 7 is formed at a front end portion, and a tapered surface 9 a overlapping with the front end side tapered surface 8 of the collet 4 is formed on an inner peripheral surface of the annular projection 9, By tightening the tightening nut 5, the tapered surface 9 a of the front-side annular convex portion 9 of the tightening nut 5 presses against the front-side tapered surface 8 of the collet 4.

[0004]

In the conventional collet chuck shown in FIG. 4, the annular groove 6 of the collet 4 has a taper 3
And a peripheral wall 6a adjacent to the collet 4 is formed in a plane shape orthogonal to the axial direction of the collet 4.
The rear end face of the annular projection 7 is in contact with the collet 4, so that the tightening of the tightening nut 5 causes an axial pressing force to act on the collet 4.
Is pressed into the deep tapered hole 1 of the chuck body 2, and the collet 4 is radially pressed by the wedge action to reduce the diameter.

That is, when the nut 5 is tightened and screwed in the axial direction, the collet 4 receives only the axial pressing force directly from the nut 5 but not the radial force. The axial pressing force 4 is divided into an axially opposite reaction force and a radial force at the tapered hole 1 of the chuck body 2 into which the tapered surface 3 is fitted, and the radial component force causes the collet 4 to contract. As a result, since a large frictional force acts between the tapered hole 1 and the tapered surface 3, in the above-mentioned conventional collet chuck, the force generated by tightening the tightening nut 5 eventually causes the collet. 4 cannot be transmitted efficiently, and the tool gripping force cannot be sufficiently exerted. For this reason, it is necessary to apply a large force to tighten the tightening nut 5, and the tightening work becomes more difficult.

In the conventional collet chuck shown in FIG. 5, when the tightening nut 5 is tightened, the tapered surface 9a of the front end side annular convex portion 9 of the tightening nut 5 presses against the front end side tapered surface 8 of the collet 4. Therefore, when the tightening nut 5 is tightened, the collet 4 receives the axial pressing force and the radial pressure directly from the tightening nut 5, and the axial pressing force is changed by the diameter in the tapered hole 1 where the tapered surface 3 is fitted. Since a directional pressure is generated, the diameter of the collet 4 is reduced by both the radial pressure at the front end side tapered surface 8 and the radial pressure at the tapered surface 3 fitted with the tapered hole 1. However, this tip side tapered surface 8
Is located at the front end of the collet which is separated from the rear end side tapered surface 3 by the annular groove 6 and is further away from the tip of the chuck body 2.
Buckling or deformation occurs in the annular groove 6 portion of the collet 4 due to the tightening force from
The radial force applied to the collet 4 escapes, and eventually the force generated by the tightening of the tightening nut 5 is efficiently transmitted to the collet 4 so that the collet 4 can be effectively reduced in diameter and the tool gripping force can be sufficiently exhibited. It will not be possible.

[0007] The present invention has been made in view of the above,
An object of the present invention is to provide a collet chuck capable of efficiently transmitting a force generated by tightening a tightening nut to the collet 4 so as to effectively reduce the diameter of the collet 4 and sufficiently exert a tool gripping force. I do.

[0008]

The collet in the collet chuck according to the first aspect of the present invention comprises a chuck body 11 having a deep tapered hole 15 at a tip end thereof, and a first taper fitted into the deep tapered hole 15. A collet of a collet chuck comprising a collapsible collet 12 having a surface 16 and a tightening nut 13 connected to the collet 12 and screwed to the chuck body 11.
An annular groove 18 is formed on the outer peripheral surface of the front end portion, and a second taper surface 20 having a slope opposite to the first taper surface 16 is formed on a peripheral side wall of the annular groove 18 adjacent to the first taper surface 16. It is characterized by being.

According to a second aspect of the present invention, a tightening nut for a collet chuck has a chuck main body 11 having a deep tapered hole 15 at a tip end thereof, and a first fitting member fitted into the deep tapered hole 15.
In the collet chuck tightening nut comprising a collapsible collet 12 having a tapered surface 16 and a tightening nut 13 connected to the collet 12 and screwed to the chuck body 11, On the inner peripheral surface of the front end portion, there is formed an annular convex portion 26 having a tapered surface 27 which is engaged with the annular groove 18 of the collet 12 and has a tapered surface 27 which can be superimposed on the second tapered surface 20 of the collet 12 on the rear end side. It is characterized by the following.

In the collet chuck according to the third aspect of the present invention, the collet has an annular projection 19 formed at the front end of the collet 12 adjacent to the annular groove 18 of the collet 12.
The rear end side peripheral side wall 21 is configured to have the configuration according to claim 1 which is tapered rearward.

The tightening nut in the collet chuck of the invention according to claim 4 is the same as that of the annular convex portion 2 of the tightening nut 13.
The rear end side peripheral side wall 30 of the annular groove 28 formed at the front end of the tightening nut 13 adjacent to the rear end 6 has a tapered shape. I have.

The collet in the collet chuck according to the fifth aspect of the present invention has an annular projection 19 formed at the front end of the collet 12 adjacent to the annular groove 18 of the collet 12.
The front end side peripheral side wall 22 is formed to have a tapered shape with a narrowed front side.

The tightening nut in the collet chuck of the invention according to claim 6 is the same as that of the annular convex portion 2 of the tightening nut 13.
The front end side peripheral side wall (29) of the annular groove (28) formed at the front end of the tightening nut (13) adjacent to the nut (6) has a tapered front end. .

[0014]

FIG. 1 is a longitudinal sectional view of a collet chuck according to an embodiment of the present invention. The collet chuck has a chuck body 11 having a tapered shank portion 14 at a rear end portion and a deep tapered hole 15 at a front end portion side,
A collapsible collet 12 having a first tapered surface 16 whose outer peripheral surface forms a deep taper and fits into a deep tapered hole 15 of the chuck body 11, and is detachably connected to the collet 12. A fastening nut 13 screwed to the chuck body 11.

The collet 12 has a substantially cylindrical shape having a tool insertion hole 17 concentric with the axis thereof, and can be reduced in diameter by split grooves (not shown) alternately cut from the front end side and the rear end side. Has become. An annular groove 18 is formed on the outer peripheral surface of the front end portion of the collet 12 and the annular groove 18 is formed.
An annular convex portion 19 is formed at the front end of the collet 12 adjacent to the first groove. A second tapered surface 20 of the annular groove 18 having a slope opposite to the first tapered surface 16 is formed on a peripheral side wall adjacent to the first tapered surface 16. Are formed.

A rear end side peripheral side wall 21 (also a front end side peripheral side wall of the annular groove 18) formed at the front end of the collet 12 has a tapered rear end (the second taper of the annular groove 18). The front end side peripheral side wall 22 of the annular convex portion 19 is formed in a tapered shape (a tapered shape having the same inclination as the second tapered surface 20 of the annular groove 18). Have been.

The tightening nut 13 includes a nut body 13a having a female screw 24 formed on an inner peripheral surface of a rear end portion thereof, which is screwed into a male screw portion 23 on an outer peripheral surface of a front end portion of the chuck main body 11, and an inner peripheral surface of the front end portion of the nut main body 13a. A ring 13b rotatably mounted on the surface of the ring 13b. An annular groove having a semicircular cross section is provided on the outer peripheral surface of the ring 13b and the corresponding inner peripheral surface of the nut body 13a. By tightly incorporating the ball 25 between the nut body 13a and the ring 13b
Are rotatably connected to each other so as to be integrated in the axial direction.

The collet 1 is provided on the inner peripheral surface at the front end of the tightening nut 13, that is, on the inner peripheral surface of the ring 13b.
An annular convex portion 26 is formed to be engaged with the second annular groove 18, and a tapered surface 27 that can be overlapped with the second tapered surface 20 of the collet 12 is formed at the rear end of the annular convex portion 26. By tightening the nut 13, the tapered surface 27 on the rear end side of the annular convex portion 26 becomes the second tapered surface 20 of the collet 12.
Is to be pressed against.

The front end side peripheral side wall 29 of the annular groove 28 formed at the front end of the ring 13b adjacent to the annular protrusion 26 on the inner peripheral surface of the ring 13b is provided with an annular convex portion of the collet 12 opposed thereto. As in the case of the front end side peripheral side wall 22 of FIG. Ring 1 of tightening nut 13
An annular clearance S between the inner peripheral surface of the inner surface 3b and the outer peripheral surface of the front end of the collet 12 forms an annular passage through which coolant (cutting oil) passes.
In this case, the front peripheral wall 29 of the front end side of the annular groove 28 on the side of the tightening nut 13 and the peripheral wall 22 of the front end side of the annular convex part 19 on the side of the collet 12 are respectively constricted. Since it has a tapered shape, the coolant C can be sprayed in a tapered shape from the tip of the annular passage as shown by the arrow, and can be effectively applied to the blade portion of the tool T.

Also, as described above, the rear peripheral wall 21 (also the front peripheral wall of the annular groove 18) of the annular convex portion 19 of the collet 12 is tapered rearward. And the rear end side peripheral side wall 3 of the annular groove 28 on the tightening nut 13 side.
Since the collet 12 is formed in the same tapered shape as the rearward constriction, the work of removing the collet 12 from the tightening nut 13 becomes easy. That is, when removing the collet 12,
The tightening nut 13 is attached to the chuck body 11 together with the collet 12.
When the front end of the collet 12 is pressed with the
The tapered peripheral side wall 21 on the side of the collet 12 and the tapered peripheral side wall 30 on the side of the nut 13 are in contact with each other,
The collet 12 is reduced in diameter centering on the front end portion by the guiding action caused by the sliding between the first and third 30 and the annular convex portion 19 exceeds the annular convex portion 26 of the tightening nut 13. Break away from

In order to fix the tool T to the collet chuck constructed as described above, as shown in FIG. 1, the tool T is inserted into the collet 12 to which the tightening nut 13 is connected, and the first The tapered surface 16 is fitted into the deep tapered hole 15 of the chuck body 11, and the female screw 2 of the tightening nut 13 is fitted.
4 into the male screw portion 23 at the tip of the chuck body 11,
What is necessary is just to rotate the nut main body 13a of this tightening nut 13 in the tightening direction.

By this tightening, the taper 27 formed on the ring 13b of the tightening nut 13 presses against the second tapered surface 20 of the collet 12, and the collet 12 is moved from the tightening nut 13 as indicated by an arrow. At the same time when the axial pressing force F1 acts, the pressure F2 acts in the inward radial direction.
Then, the axial pressing force F1 on the second tapered surface 20 generates a radial pressure in the deep tapered hole 15 of the chuck body 11 to which the first tapered surface 16 of the collet 12 fits. The diameter can be reduced very effectively by the radial pressure F2 on the second tapered surface 20 and the radial pressure on the first tapered surface 16 side. Since it is adjacent and located near the tip of the chuck body 11, buckling and deformation may occur on the front end side of the collet 12 due to the axial pressing force from the tightening nut 13 generated on the second tapered surface 20. There is no. Therefore, the force generated by the tightening of the tightening nut 13 is efficiently transmitted to the collet 12, so that the diameter of the collet 12 can be effectively reduced and the tool gripping force can be sufficiently exhibited.

The collet chuck shown in FIG. 2 has almost the same structure as the collet chuck of FIG. 1, and has an annular gap S between the inner peripheral surface of the ring 13b of the tightening nut 13 and the outer peripheral surface of the front end of the collet 12. Is different from the collet chuck shown in FIG. 1 in that the front end is formed in a straight shape instead of a tapered shape. The collet chuck shown in FIG. 3 has almost the same configuration as the collet chuck shown in FIG. 2, but has a rear end side peripheral side wall 21 (also a front end side peripheral side wall of the annular groove 18) of the annular convex portion 19 of the collet 12. The rear end side peripheral side wall 30 of the annular groove 28 of the tightening nut 13 (which is also the front end side peripheral side wall of the annular convex portion 26) is formed in a non-tapered shape, that is, the collet chuck. 2 and 1 is different from the collet chuck shown in FIGS.

[0024]

According to the first or second aspect of the present invention,
By tightening the tightening nut 13, the tightening nut 1
3 presses against the second tapered surface 20 of the collet 12 to apply an axial pressing force to the collet 12 from the tightening nut 13, and at the same time, a pressure acts in an inward radial direction, and the axial The pressing force further generates an inward radial pressure at the deep tapered hole 15 of the chuck body 11 to which the first tapered surface 16 of the collet 12 fits.
The diameter is reduced very effectively by the radial pressure acting directly on the second tapered surface 20 and the radial pressure on the first tapered surface 16.
Is located adjacent to the first tapered surface 16 and near the tip of the chuck body 11, so that the second tapered surface 20
No buckling or deformation occurs on the front end side of the collet 12 due to the axial pressing force from the tightening nut 13 generated in the above.
Therefore, the force generated by the tightening of the tightening nut 13 is efficiently transmitted to the collet 12, and the diameter of the collet can be effectively reduced, so that the tool gripping force can be sufficiently exhibited.

According to the third or fourth aspect of the present invention, the rear side wall 21 on the rear end side of the annular projection 19 formed at the front end of the collet 12 adjacent to the annular groove 18 of the collet 12, and the tightening nut The rear end side peripheral side walls 30 of the annular groove 28 formed at the front end of the tightening nut 13 adjacent to the annular projection 26 of the thirteen are respectively tapered rearward.
The work of removing the collet 12 from the fastening nut 13 is facilitated.

According to the fifth or sixth aspect of the invention, the front end side peripheral side wall 22 of the annular projection 19 formed at the front end of the collet 12 adjacent to the annular groove 18 of the collet 12 and the tightening nut 13 The front end side peripheral side wall 29 of the annular groove portion 28 formed at the front end portion of the tightening nut 13 adjacent to the annular convex portion 26 is formed so as to be tapered forward.
Coolant is supplied to the annular gap S between the inner peripheral surface of the tightening nut 13 and the outer peripheral surface of the front end of the collet 12 as an annular passage for coolant, and the coolant is ejected from the tip of the annular passage S to the blade of the tool. In this case, the leading end of the annular passage S becomes pre-constricted, so that the coolant can be effectively injected to the blade of the tool.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a collet chuck of the present invention.

FIG. 2 is a longitudinal sectional view of a collet chuck showing another embodiment.

FIG. 3 is a longitudinal sectional view of a collet chuck showing still another embodiment.

FIG. 4 is a sectional view of a main part showing a conventional collet chuck.

FIG. 5 is a sectional view of a principal part showing a conventional collet chuck.

[Explanation of symbols]

Reference Signs List 11 chuck body 12 collet 13 tightening nut 15 deep tapered hole of chuck body 16 first tapered surface of collet 18 annular groove of collet 19 annular convex portion of collet 20 second tapered surface of collet 21 after annular convex portion of collet End side peripheral side wall (front end side peripheral side wall of annular groove) 22 Front end side peripheral side wall of annular convex portion of collet 29 Front end side peripheral side wall of annular groove portion of tightening nut 30 Rear end side peripheral side wall of annular groove portion of tightening nut ( Front end side peripheral side wall of annular convex part)

Claims (6)

[Claims] A chuck body having a deep tapered hole at a distal end thereof;
An outer peripheral surface of a front end portion of the collet 12 in a collet of a collet chuck including a collet 12 having a tapered surface 16 and capable of being reduced in diameter and a tightening nut 13 connected to the collet 12 and screwed to the chuck body 11. An annular groove 18 is formed in the annular groove 18.
A collet in a collet chuck, wherein a second tapered surface (20) that is opposite to the first tapered surface (16) is formed on a peripheral side wall adjacent to the tapered surface (16). 2. A chuck body 11 having a deep tapered hole 15 at a distal end thereof, and a first chuck body fitted into said deep tapered hole 15.
In the collet chuck tightening nut comprising a collapsible collet 12 having a tapered surface 16 and a tightening nut 13 connected to the collet 12 and screwed to the chuck body 11, On the inner peripheral surface of the front end portion, there is formed an annular convex portion 26 having a tapered surface 27 which is engaged with the annular groove 18 of the collet 12 and has a tapered surface 27 which can be superimposed on the second tapered surface 20 of the collet 12 on the rear end side. A tightening nut for a collet chuck, characterized in that: 3. A rear end side peripheral side wall 21 of an annular protrusion 19 formed at a front end of the collet 12 adjacent to the annular groove 18 of the collet 12 is tapered rearward. The collet of the collet chuck described in 1. 4. An annular groove 2 formed at the front end of the tightening nut 13 adjacent to the annular convex portion 26 of the tightening nut 13.
3. The tightening nut for a collet chuck according to claim 2, wherein the rear end side peripheral side wall 8 is tapered rearward. 5. A front end side peripheral side wall 22 of an annular projection 19 formed at a front end of the collet 12 adjacent to the annular groove 18 of the collet 12 is tapered. The collet of the collet chuck described. 6. An annular groove 2 formed at the front end of the tightening nut 13 adjacent to the annular protrusion 26 of the tightening nut 13.
5. The tightening nut for a collet chuck according to claim 4, wherein the front end side peripheral side wall of the front end of the collet chuck has a tapered shape.