JP2002018679A - Clamp mechanism in circular table device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly stop and hold a rotating shaft at a predetermined rotation angle even on a low working pressure in a circular table device such as an indexing device. SOLUTION: In this circular table device, a table surface 7 is disposed at one axial end of the rotating shaft 5, a driving mechanism rotates the rotating shaft 5, and a clamp mechanism fixes the rotating shaft at the predetermined rotation angle. The clamp mechanism comprises a brake disk 15 integrally provided for the rotating shaft 5, clamp members 20 and 21 for grabbing the brake disk 15, and a fluid pressure piston 25 for pressurizing the clamp members 20 and 21. A two stage type boosting mechanism comprising an axially and radially movable ball 26 and taper cam surfaces 28 and 29 formed on the piston 25 and a movable side clamp member 21, respectively, is provided between the fluid pressure piston 25 and the clamp member 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clamp mechanism for accurately stopping and holding a rotating shaft at a predetermined rotation angle in various rotary table devices such as an indexing device.

[0002]

2. Description of the Related Art Conventionally, a clamp mechanism of this type has a brake disk integrally provided on a rotating shaft, a clamp member for clamping the brake disk, and a hydraulic piston for pressurizing the clamp member. When the clamp member is directly pressurized by the hydraulic piston, the brake disk is pressed between the clamp members, and the rotation shaft is stopped and held at a predetermined rotation angle.

As is well known, the work held by the rotary table device is subjected to cutting or grinding by various machine tools such as a milling machine and a machining center. At the same time as being required to be fixed to the table surface, the clamping mechanism for stopping and holding the rotating shaft is also required to have a clamping force capable of reliably maintaining a predetermined rotation angle position against the pressure or vibration during the above operation. .

For this reason, as described above, a hydraulic piston is usually used as a piston for pressurizing the clamp member, and is operated at a high operating pressure (oil pressure).

[0005]

However, in the structure provided with the hydraulic piston having a high working pressure as described above, a high-pressure sealing mechanism and a sealing member are required to prevent oil leakage, and the cost of parts is increased. Maintenance is also troublesome.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a rotary table device,
It is an object of the present invention to provide a clamping mechanism that can sufficiently clamp a rotating shaft even with a fluid pressure piston used at a low pressure such as air pressure, and save parts and maintenance costs.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 of the present application is provided with a work mounting portion at one axial end of a rotating shaft, rotating the rotating shaft by a driving mechanism, and by a clamping mechanism. In a rotary table device for fixing a rotation shaft at a predetermined rotation angle, a brake disk integrally provided on the rotation shaft, a clamp member for clamping the brake disk, and an axial pressure on the clamp member are provided as a clamp mechanism. A fluid pressure piston is provided, and between the fluid pressure piston and the clamp member, a booster mechanism including a ball and a cam surface movable in the axial direction and the radial direction is interposed.

According to a second aspect of the present invention, in the clamp mechanism of the rotary table device according to the first aspect, the booster mechanism includes a first stage formed by abutment between a ball and a first tapered cam surface formed on a fluid pressure piston. It is characterized in that it has an intensifying section and a second-step intensifying section formed by abutment between a ball and a second tapered cam surface formed on the clamp member.

According to a third aspect of the present invention, in the clamp mechanism of the rotary table device according to the first or second aspect, the drive mechanism is constituted by a worm wheel provided on the rotating shaft and a worm shaft meshing with the worm wheel. It is characterized by:

According to a fourth aspect of the present invention, in the clamp mechanism of the rotary table device according to the third aspect, the worm shaft is formed of a hard material such as overhardened, and the worm wheel is formed of a hardened hard material. The worm shaft and the worm wheel are characterized by being meshed in the oil bath.

[0011]

FIG. 1 is a longitudinal sectional view of a rotary table device to which the present invention is applied. In a device main body 1, a rotary shaft 5 is rotatable via a cross roller bearing 2 and a needle bearing 4. One end of the rotating shaft 5 in the axial direction protrudes outward from the apparatus, and a table surface 7 is formed at the protruding end as a work mounting portion.

A worm wheel 11 is fixed to a portion between the bearings 2 and 4 of the rotating shaft 5 by bolts 10, and the worm wheel 11 meshes with a driving worm shaft 12, and the driving worm shaft 12 is not shown. Are connected to an electric rotary actuator or a manual handle type. The space for accommodating the worm shaft 12 and the worm wheel 11 is an oil bath, and the worm shaft 12 and the worm wheel 11 are driven in the oil bath. The worm shaft 12 is formed of a hard material such as overhardened, and the worm wheel 11 is formed of a hardened hard material.

The clamp mechanism for stopping and holding the rotary shaft 5 at a predetermined rotation position includes a brake disk 15 that rotates integrally with the rotary shaft 5 and a pair of clamp members 20 and 21 that press the brake disk 15 from both sides in the axial direction. And a pneumatic piston 25 that presses (presses) one of the clamp members 21 in the axial direction, and a booster mechanism using a ball 26 and cam surfaces 28 and 29.

The brake disk 15 is sandwiched between a pair of mounting rings 16 and is fixed to the worm wheel 11 by bolts 27. The pair of clamp members 20,
21, one of the clamp members 20 is formed integrally with the apparatus main body 1 and cannot be moved in the axial direction, and the other clamp member 21 is fitted to the inner peripheral surface of the apparatus main body 1 so as to be movable in the axial direction. And it is a movable side clamp member. A return spring 30 is contracted between the clamp members 20 and 21 to move the movable clamp member 21 to the unclamping side (arrow A).
2).

An annular piston chamber (cylinder) having an L-shaped cross section is formed by the cylinder forming member 31 on the arrow A2 side of the movable side clamp member 21, and a plurality of O-rings 38a, 38b, 38c are formed in the piston chamber. The pneumatic piston 25 having an L-shaped cross section is fitted through the through hole so as to be movable in the axial direction. In the piston chamber, a clamping air chamber 32 for moving the piston 25 to the clamp side (arrow A1 side) and the piston 25 to the unclamping side (arrow A
2), an air chamber 33 for unclamping is formed to move the air supply source and the air discharge through air passages 35 and 36 and an air switching valve (not shown). It is connected to the part so as to be switchable.

The booster mechanism comprises a first stepped taper cam surface 28 formed at the tip of the piston and a ball 26 formed of a ball 26.
A step intensifier and a second clamp formed on the movable clamp member 21
It has a tapered cam surface 29 for the step and a second step intensifying portion composed of 26 balls, so that the step is increased in a two-step manner.

FIG. 2 is an enlarged view of the above-described two-stage booster mechanism. A taper surface 40 that comes to the arrow A1 side as going outward in the radial direction is provided on the end surface of the cylinder forming member 31 on the arrow A1 side. Are formed, and a plurality of the balls 26 are formed.
Are arranged over the entire circumference of the tapered surface 40.
The tapered cam surface 28 of the piston 25 contacts the portion P1 of the ball 26 on the rotation axis side, and the tapered cam surface 29 of the movable clamp member 21 contacts the portion P2 of the ball 26 on the arrow A1 side.

The tapered surface 40 of the cylinder forming member 31 and the tapered cam surface 29 of the movable clamp member 21 have gentle inclination angles α2 and α3 of 30 ° or less with respect to a plane perpendicular to the rotation axis. Further, the taper angle α1 of the tapered cam surface 28 of the piston 25 is also a gentle inclination angle of 30 ° or less.

[0019]

(1) FIG. 1 shows the unclamped state, in which the clamping pressure of the clamp members 20 and 21 on the brake disk 15 is released. In this state, the drive worm shaft 12
, The rotation shaft 5 rotates via the worm wheel 11, thereby changing the rotation angle of the work on the table surface 7.

(2) When the rotating shaft 5 is to be clamped after the rotation by a predetermined angle, the piston 25 is clamped by pressing air into the clamping air chamber 32 and discharging air from the unclamping air chamber 33 at the same time. To the side (in the direction of arrow A1).

In FIG. 2, the ball 26 is pushed by the first-stage tapered cam surface 28 by the movement of the piston 25 in the direction of the arrow A1, and the tapered surface 4 of the cylinder forming member 31 is pressed.
It moves radially outward and in the direction of arrow A1 along 0. Accordingly, the movable-side clamp member 21 moves in the direction of the arrow A1, and presses the brake disc 15 between the movable-side clamp member 21 and the fixed-side clamp member 20.

In the process of transmitting power from the piston 25 to the movable clamp member 21 as described above, the piston 2
Assuming that the pressing force in the direction of arrow A1 of F5 is F1, first,
Contact portion P between first-stage tapered cam surface 28 and ball 26
1, the pressing force F1 is increased to a radially outward force F2 by the cam action of the first-stage tapered cam surface 28 and transmitted to the ball 26. That is, in the first-stage booster, the power is increased from F1 to F2.

Next, the ball 26 and the movable clamp member 2
In the contact portion P2 with the first portion 1, the force F2 is increased to a pressing force F3 in the direction of the arrow A1 by the cam action of the second-stage tapered cam surface 29 and transmitted to the movable clamp member 21.

Then, the brake disc 15 is pressed and held between the fixed-side clamp member 20 by the pressing force F3 of the movable-side clamp member 21.

In the case of unclamping, the piston 25 is moved in the direction of arrow A2 by pressing air into the unclamping air chamber 33 and discharging air from the clamping air chamber 32 in FIG. The clamps 21 and 20 are released. At that time, the movable side clamp member 21
Is pushed in the direction of the arrow A2 by the spring 30, and the ball 25 returns to the rotation axis side, and keeps a state in which it comes into contact with the first-stage tapered cam surface 28.

[0026]

[Other Embodiments] (1) As a fluid pressure piston,
It is possible to use a hydraulic piston, but even in that case, it can be used without increasing the operating oil pressure.

[0027]

As described above, according to the present invention, (1) In the rotary table device, as the clamp mechanism,
A brake disc provided integrally with the rotating shaft, a clamp member for clamping the brake disc, and a fluid pressure piston for pressurizing the clamp member are provided, and an axial direction and a diameter are provided between the fluid pressure piston and the clamp member. Because a force-intensifying mechanism consisting of a ball and a cam surface that can move in the direction is interposed, the rotating shaft can be firmly and reliably fixed at a predetermined rotation angle even at a low operating pressure, and the holding function of the workpiece etc. In addition to the improvement, the need for a high-pressure sealing mechanism and a sealing member is eliminated, so that a reduction in component costs and simplification of maintenance can be achieved.

(2) It becomes possible to use a pneumatic piston having a low operating pressure, thereby reducing the cost of parts and facilitating maintenance.

(3) As in the second aspect of the present invention, as a boosting mechanism, a first-step booster formed by abutment between a ball and a first tapered cam surface formed on a piston, and a second booster formed on a clamp member. When the second-stage intensifier is provided by abutment between the second tapered cam surface and the ball, the holding force of the rotating shaft is further improved while maintaining the compactness of the intensifier.

(3) When the drive mechanism is constituted by a worm wheel provided on the rotating shaft and a worm shaft meshing with the worm wheel, as in the invention described in claim 3,
The rotational positioning accuracy can be improved while maintaining the compactness of the drive mechanism.

According to a fourth aspect of the present invention, the worm shaft is formed of a hard material such as overhardened, the worm wheel is formed of a hardened hard material, and the worm shaft and the worm wheel are engaged in an oil bath. When aligned, the rotational positioning accuracy and durability are improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a rotary table device to which the present invention is applied.

FIG. 2 is an enlarged vertical sectional view of the booster mechanism of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Apparatus main body 5 Rotation axis 7 Table surface (work mounting part) 15 Brake disk 20 Clamp member on fixed side 21 Clamp member on movable side 25 Pneumatic piston 26 Ball 28 First stage taper cam surface 29 Second stage taper cam Plane 32,33 air chamber

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B23Q 1/28 (72) Inventor Shingo Oda 1-6-153 Motomachi, Higashiosaka-shi, Osaka Nikken Kogyo Co., Ltd. F Terms (reference) 3C028 EE17 3C048 AA01 BC02 CC04 DD12 3J058 AA43 AA47 AA53 AA68 AA77 AA79 AA83 BA07 CC32 CC52 FA32

Claims (4)

[Claims] 1. A rotary table device comprising a work mounting portion at one axial end of a rotary shaft, the rotary shaft being rotated by a drive mechanism, and the rotary shaft being fixed at a predetermined rotation angle by a clamp mechanism. A brake disc provided integrally with the brake disc, a clamp member for pressing the brake disc, and a fluid pressure piston for pressurizing the clamp member in the axial direction. A clamp mechanism in a rotary table device, wherein a booster mechanism comprising a ball and a cam surface movable in a radial direction is interposed. 2. The power boosting mechanism according to claim 1, wherein the first pressure cam surface formed on the fluid pressure piston is in contact with a ball.
2. The clamping mechanism according to claim 1, further comprising a step-intensifying section, and a second step-intensifying section formed by abutment between a ball and a second tapered cam surface formed on the clamp member. 3. The clamp mechanism according to claim 1, wherein the drive mechanism comprises a worm wheel provided on the rotating shaft and a worm shaft meshing with the worm wheel. 4. The worm shaft is formed of a hard material such as overhardened steel, the worm wheel is formed of a hardened hard material, and the worm shaft and the worm wheel are engaged in an oil bath. A clamp mechanism in the rotary table device according to claim 3.