JP3713190B2 - Rotary 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

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to various rotary table devices such as an indexing device, and more particularly to a rotary table device having a clamp mechanism for accurately stopping and holding a rotation shaft at a predetermined rotation angle .
[0002]
[Prior art]
Conventionally, this type of clamping mechanism includes a brake disk integrally provided on a rotating shaft, a clamp member that clamps the brake disk, and a hydraulic piston for pressurizing the clamp member. By directly pressurizing the clamp member with the piston, the brake disc is clamped between the clamp members, and the rotation shaft is stopped and held at a predetermined rotation angle.
[0003]
Since the work held by the circular table device is used for cutting or grinding operations by various machine tools such as a milling machine and a machining center as is well known, the work is placed on the table surface so that it can withstand the pressurization or vibration from the tool. At the same time that it is required to be fixed, a clamping mechanism that stops and holds the rotating shaft is also required to have a clamping force that can reliably maintain a predetermined rotational angular position against the pressurization or vibration during the above-described operation.
[0004]
For this reason, as a piston for pressurizing the clamp member, a hydraulic piston is usually used as described above, and the piston is operated at a high operating pressure (hydraulic pressure).
[0005]
[Problems to be solved by the invention]
However, in the structure provided with the hydraulic piston having a high operating pressure as described above, a high-pressure seal mechanism and a seal member are required for oil leakage countermeasures, which incurs the cost of parts and labor for maintenance.
[0006]
OBJECT OF THE INVENTION
An object of the present invention is to provide a clamping mechanism capable of sufficiently clamping a rotating shaft even with a fluid pressure piston used at a low pressure such as air pressure in a circular table device, and saving part costs and maintenance costs.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 of the present application is provided with a work mounting portion at one end in the axial direction of the rotating shaft (5), the rotating shaft (5) is rotated by a driving mechanism, and a predetermined rotating angle is achieved by a clamping mechanism. In the rotary table device that fixes the rotating shaft at the rotating shaft (5), the drive mechanism includes a worm wheel (11) provided on the rotating shaft (5) and a worm shaft (12) meshing with the worm wheel (11), and a worm The shaft (12) and the worm wheel (11) are housed in an oil bath, and the clamp mechanism includes a brake disc (15) fixed to the worm wheel (11) and the brake disc (15) in the axial direction. and the fixed clamp member nipping releasably from opposite sides (20) and the movable clamp member (21), the fluid pressure piston for pressurizing the movable clamp member (21) axially stationary clamping member (20) side of ( 25), said fluid pressure piston (25) The axial and movable ball in the radial direction (26) and a boosting mechanism composed of the cam surfaces (28, 29) as well as interposed between the movable clamp member (21), wherein the movable clamping member (21) is urged toward the unclamping side in the axial direction by a return spring (30) , and the force- increasing mechanism includes a first stage tapered cam surface (28) formed on the fluid pressure piston (25) and a ball. The second-stage force-increasing portion by contact between the ball (26) and the first-stage force-increasing portion by contact with (26) and the second-stage tapered cam surface (29) formed on the movable-side clamp member (21). It has the part.
[0008]
According to a second aspect of the present invention , in the rotary table device according to the first aspect, the fluid pressure piston is formed in an annular shape surrounding the rotating shaft.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a longitudinal sectional view of a rotary table device to which the present invention is applied. A rotary shaft 5 is rotatably supported in a main body 1 via a cross roller bearing 2 and a needle bearing 4. One end in the axial direction of 5 protrudes outward from the apparatus, and a table surface 7 is formed at the protruding end as a work mounting portion.
[0012]
A worm wheel 11 is fixed to a portion between the bearings 2 and 4 of the rotary shaft 5 by a bolt 10. The worm wheel 11 meshes with a drive worm shaft 12, and the drive worm shaft 12 is electrically driven although not shown. It is connected to a rotary actuator or a manual handle type. A space for housing 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 made of a hard material such as hardened, and the worm wheel 11 is made of a hardened material.
[0013]
The clamping mechanism for stopping and holding the rotary shaft 5 at a predetermined rotational position includes a brake disc 15 that rotates integrally with the rotary shaft 5, a pair of clamp members 20 and 21 that clamp the brake disc 15 from both sides in the axial direction, The pneumatic piston 25 pressurizes (presses) the clamp member 21 in the axial direction, and a force-increasing mechanism using the balls 26 and the cam surfaces 28 and 29.
[0014]
The brake disk 15 is sandwiched between a pair of attachment rings 16 and is fixed to the worm wheel 11 by bolts 27. Of the pair of clamp members 20, 21, one clamp member 20 is formed integrally with the apparatus main body 1 and cannot move in the axial direction, and the other clamp member 21 is an inner peripheral surface of the apparatus main body 1. And a movable side clamp member. A return spring 30 is provided between the clamp members 20 and 21 to urge the movable clamp member 21 toward the unclamp side (arrow A2 side).
[0015]
An annular piston chamber (cylinder) having an L-shaped cross section is formed by the cylinder forming member 31 on the arrow A2 side from the movable side clamp member 21, and a plurality of O-rings 38a, 38b, and 38c are formed in the piston chamber. The pneumatic piston 25 having an L-shaped cross section is fitted so as to be movable in the axial direction. In the piston chamber, there are a clamping air chamber 32 for moving the piston 25 to the clamping side (arrow A1 side) and an unclamping air chamber 33 for moving the piston 25 to the unclamping side (arrow A2 side). The two air chambers 32 and 33 are communicated with an air supply source and an air discharge portion through air passages 35 and 36, an air switching valve (not shown) and the like, respectively, so as to be switchable.
[0016]
The force-increasing mechanism includes a first-stage taper cam surface 28 formed at the tip of the piston and a first-stage force-increasing portion composed of a ball 26, a second-stage taper cam surface 29 formed on the movable clamp member 21, and a ball. The second-stage power-increasing portion is 26, and the power is increased in a two-stage manner.
[0017]
FIG. 2 is an enlarged view of the above-described two-stage force-increasing mechanism. A tapered surface 40 is formed on the end surface on the arrow A1 side of the cylinder forming member 31 so as to come to the arrow A1 side as it goes outward in the radial direction. The plurality of balls 26 are arranged over the entire circumference of the tapered surface 40. The tapered cam surface 28 of the piston 25 is in contact with the portion P1 of the ball 26 on the rotational axis side, and the tapered cam surface 29 of the movable clamp member 21 is in contact with the portion P2 of the ball 26 on the arrow A1 side.
[0018]
The taper surface 40 of the cylinder forming member 31 and the taper cam surface 29 of the movable clamp member 21 have gentle inclination angles α2 and α3 of 30 ° or less with respect to a surface perpendicular to the rotation axis. The taper angle α1 of the taper cam surface 28 of the piston 25 is also a gentle inclination angle of 30 ° or less.
[0019]
[Action]
(1) FIG. 1 is an unclamped state, and the clamping pressure of the clamp members 20 and 21 with respect to the brake disc 15 is released. By rotating the driving worm shaft 12 in this state, the rotating shaft 5 rotates via the worm wheel 11, thereby changing the rotation angle of the workpiece on the table surface 7.
[0020]
(2) When the rotary shaft 5 is clamped after rotation by a predetermined angle, air is pressed into the clamping air chamber 32 and at the same time, the air is discharged from the unclamping air chamber 33, so that the piston 25 is clamped (arrow). A1 direction).
[0021]
In FIG. 2, the movement of the piston 25 in the direction of arrow A1 causes the ball 26 to be pushed by the first stage taper cam surface 28, along the taper surface 40 of the cylinder forming member 31, and outward in the radial direction and arrow A1. Move in the direction. Along with this, the movable side clamp member 21 moves in the direction of the arrow A <b> 1 and clamps the brake disk 15 between the fixed side clamp member 20.
[0022]
Assuming that the pressing force of the piston 25 in the direction of arrow A1 is F1 in the process of transmitting power from the piston 25 to the movable clamp member 21 as described above, first, the contact between the first stage tapered cam surface 28 and the ball 26 is assumed. At the contact portion P 1, the pressing force F 1 is increased to a radially outward force F 2 by the cam action of the first stage tapered cam surface 28 and transmitted to the ball 26. That is, the first stage booster is boosted from F1 to F2.
[0023]
Next, in the contact portion P2 between the ball 26 and the movable side clamp member 21, the force F2 is increased to the pressing force F3 in the direction of the arrow A1 by the cam action of the second stage taper cam surface 29, so that the movable side It is transmitted to the clamp member 21.
[0024]
Then, the brake disc 15 is clamped and held with the fixed clamp member 20 by the pressing force F3 of the movable clamp member 21.
[0025]
In the case of unclamping, the piston 25 is moved in the direction of the arrow A2 by press-fitting air into the unclamping air chamber 33 of FIG. Release the clamp by. 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 contacting the first stage taper cam surface 28.
[0026]
[Other embodiments]
(1) Although a hydraulic piston can be used as the fluid pressure piston, it can be used without increasing the operating hydraulic pressure.
[0027]
【The invention's effect】
As explained above, according to the present invention,
(1) In the rotary table device, as a clamp mechanism, a brake disk provided integrally with a rotating shaft, a clamp member that clamps the brake disk, a fluid pressure piston that pressurizes the clamp member, and a fluid pressure A force-increasing mechanism consisting of a ball and a cam surface that are movable in the axial direction and the radial direction is interposed between the piston and the clamp member, so that the rotating shaft can be firmly and reliably maintained at a predetermined rotational angle even at low operating pressures. It can be fixed, the holding function of the workpiece and the like is improved, and the high-pressure seal mechanism and the seal member are not necessary, so that it is possible to reduce the parts cost and facilitate the maintenance.
[0028]
(2) It is possible to use a pneumatic piston with a low operating pressure, thereby reducing component costs and facilitating maintenance.
[0029]
(3) As a force-increasing mechanism, a first-stage force-increasing portion formed by contact between the first taper cam surface formed on the piston and the ball, and a second step-power-increasing portion formed on the clamp member and contacted by the ball. When the two-stage booster is provided, the holding force of the rotating shaft is further improved while maintaining the compactness of the booster mechanism.
[0030]
(4) When the drive mechanism is composed of a worm wheel provided on the rotating shaft and a worm shaft meshing with the worm wheel, and the worm shaft and the worm wheel are housed in an oil bath, the drive mechanism can be made compact. While maintaining, rotational positioning accuracy and durability are improved.
[0031]
If the worm shaft is made of a hard material such as carbide and the worm wheel is made of a hardened material, the durability is further improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a circular table device to which the present invention is applied.
FIG. 2 is an enlarged vertical sectional view of the power increasing mechanism of FIG.
[Explanation of symbols]
1 Device body 5 Rotating shaft 7 Table surface (work mounting part)
15 Brake disc 20 Clamp member 21 on the fixed side Clamp member 25 on the movable side Pneumatic piston 26 Ball 28 First stage taper cam surface 29 Second stage taper cam surface 32, 33 Air chamber

Claims (2)

In the rotary table device provided with a work mounting part at one axial end of the rotating shaft (5), rotating the rotating shaft (5) by a drive mechanism, and fixing the rotating shaft at a predetermined rotation angle by a clamp mechanism,
The drive mechanism is composed of a worm wheel (11) provided on the rotating shaft (5) and a worm shaft (12) meshing with the worm wheel (11), and the worm shaft (12) and the worm wheel (11) are Stored in the oil bath,
The clamp mechanism includes a brake disc (15) fixed to the worm wheel (11) , a fixed-side clamp member ( 20) and a movable-side clamp that clamp the brake disc (15) so as to be releasable from both sides in the axial direction. a member (21), the movable clamp member (21) in the axial direction of the fixed clamping member (20) fluid pressure pressurized to side piston (25), said fluid pressure piston (25) and said movable clamp member ( 21) and a force-increasing mechanism composed of a ball (26) and a cam surface (28, 29) that are movable in the axial direction and the radial direction .
The movable clamp member (21) is urged toward the unclamping side in the axial direction by a return spring (30) ,
The force-increasing mechanism includes a first-stage force-increasing portion formed by contact between the first- stage tapered cam surface (28) formed on the fluid pressure piston (25) and the ball (26), and a movable-side clamp member (21). A circular table device having a second-stage intensifying part formed by contact between the formed second-stage tapered cam surface (29) and the ball (26).   The rotary table device according to claim 1, wherein the fluid pressure piston is formed in an annular shape surrounding a rotating shaft.

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