JPH0696217B2 - Clamp device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a clamping device for positioning a fixed object such as a pallet or a work in an automatic machine tool such as a machining center.

2. Description of the Related Art As a conventional clamping device of this type, there is a clamping device configured to press a pallet, which is positioned by two pins with respect to a base, to a base side with a clamping piece to fix the pallet. To be Further, as another clamp device, the tip of the pull stud is inserted into the inside of the tubular body, and the pull stud is held in a locked state by a locking body such as a ball that is movable in the radial direction inside the tubular body. There is a clamp mechanism for tool shank for machining center.

The former clamp device has the drawback that the clamp device itself becomes complicated and large, and the pallet changing device also becomes complicated. Also, the production cost of the pallet itself will be high. Therefore, when considering a pallet for small items, the pallet and the clamp device as described above are unsuitable.

Further, in the latter clamp device, since the allowable range of the shaft diameter of the tapered portion of the tool is large, the outer diameter cannot be made constant among a plurality of tools. For this reason,
Even if this clamp mechanism is incorporated into a pallet clamp device, the bottom surface of the pallet cannot be brought into close contact with the base surface, which is disadvantageous in terms of rigidity and causes problems such as vibration during cutting.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to position an object to be fixed such as a pallet with high accuracy in the axial direction, the radial direction, and the circumferential direction, and to make the device compact and to reduce the manufacturing cost of the object to be fixed such as a pallet. Another object of the present invention is to provide a clamp device that can be manufactured at low cost and that has a strong rigidity.

SUMMARY OF THE INVENTION Therefore, the present invention is based on a pull stud type clamp mechanism, and the position of a pallet or the like is axially restricted by a reference plane by the clamp mechanism, and then a taper sleeve is pressed against a tapered surface on the pallet side. Thus, the pallet is accurately indexed in the radial direction of the shaft on the reference plane and fixed under the wedge action. Here, the holding operation of the pull stud and the driving operation of the taper sleeve are achieved by differentially moving the two pistons due to the pressure receiving area difference.

Configuration of the Invention FIGS. 1 to 3 show a clamping device 1 of the present invention. The clamp device 1 is incorporated in the index table 2, for example. The base 3 of the clamp device 1 has a hollow cylindrical shape, and the index table 2
Is rotatably supported inside the bearing via a bearing 4.
A pallet 5, which is an object to be fixed, is arranged on the base 3. The pallet 5 is formed in the following shape so that its position with respect to the base 3 is determined. That is, the outer peripheral portion of the bottom surface of the pallet 5 is provided with a flat surface portion 5a for determining the position in the axial direction, and a substantially cylindrical protruding portion 5b protruding downward from the central portion of the bottom surface of the pallet 5.
The outer peripheral surface of the taper part 5c for centering in the radial direction
Is provided. Further, in this protruding portion 5b, a straight cylindrical portion 5d for rough positioning is formed so as to further project in the radial direction on the side of the tapered portion 5c from the position of the tapered portion 5c. Further, for example, one taper hole 5e is formed on the bottom surface of the pallet 5 on the side closer to the center than the plane portion 5a in order to position the pallet 5 relative to the base 3. A taper pin 6 inserted and arranged in a pin hole 3a formed in the base 3 is fitted into the taper hole 5e. The taper pin 6 is movable in the vertical direction with respect to the base 3, and is pressed against the taper hole 5e side via a disc-shaped spring 7.

Further, the pull stud 8 is provided on the protruding portion 5b of the pallet 5.
Are fixed by screwing the screw portion 8a into the protruding portion 5b. The tip end side of the pull stud 8 can be releasably connected to the clamp rod 10 via a ball 9. The ball 9 is fitted into the small hole 10a in the radial direction so as to be able to be taken in and out by the holding hole 10e at the tip of the clamp rod 10, and moves by hitting the cam surface 3d.

The clamp rod 10 is arranged in the base 3 so as to be vertically slidable. The vertical movable range of the clamp rod 10 is determined by the contact between the end surface of the cylinder chamber 3c of the base 3 and the piston portion 10b. Further, another piston 11 is fitted on the upper part of the clamp rod 10 so as to be vertically slidable in the cylinder chamber 3e. The piston 11 and the piston portion 10b are opposed to each other and face the hydraulic chamber 12 side, and the pressure receiving area of the piston 11 is formed to be smaller than the pressure receiving area of the piston portion 10b of the clamp rod 10.

Also, on the upper end side of the piston 11, a plurality of pins are arranged in the circumferential direction.
13 are arranged. This pin 13 is a small hole 3f in the base 3
It is provided so as to be slidable therein, and configured to transmit the force of the piston 11 to the taper sleeve 14. The taper sleeve 14 can slide in the axial direction with the circular hole 3g of the base 3 as a guide, and a disc spring provided between the lower end flange portion 14a of the taper sleeve 14 and the base 3. The taper sleeve 14 is constantly urged downward by 15. The taper sleeve 14 is configured such that the taper surface 14b on the inner peripheral surface side is hard to be wedged into the taper portion 5c of the pallet 5 under a wedge action within a movable range.

A worm wheel 16 is provided on the outer peripheral portion of the base 3.
Is fixed, and the worm wheel 16 meshes with the worm 17 on the index table 2 side. A rotary joint 18 is rotatably attached to the lower end side of the clamp rod 10. The hydraulic ports 18a and 18b of the rotary joint 18 are annular groove portions, and the hydraulic chamber 12 and the cylinder chamber are formed by the passages 10c and 10d of the clamp rod 10.
It leads to one room of 3c. In addition, the air pressure port 18c is a portion of the annular groove that communicates with the holding hole 10e by the passage 10f of the clamp rod 10 and is further branched into the passage 3 of the base 3.
It also communicates with the center hole 6a of the taper pin 6 by b.

Action of the Invention As shown in FIG. 1, when there is no pallet 5 on the base 3,
The clamp rod 10 receives the hydraulic pressure from the hydraulic port 18b and is in the forward limit, and the taper sleeve 14 is pressed by the disc spring 15 so as to be located in the backward limit. As a result, the ball 9 faces the large diameter portion of the cam surface 3d of the base 3.

In this state, when the pallet 5 is carried in above the base 3 and placed on the base 3, the pull stud 8
Hold the hole of the clamp rod 10 by expanding the ball 9
Get inside 10e. At this time, the pallet 5 is relatively positioned in the circumferential direction at the fitting portion due to the fitting of the tapered hole 5e and the tapered pin 6. At this point, the pallet 5 is still in the unclamped state, so that the pallet 5 rotates about the taper pin 6 and moves to the base 3
It slides on the upper surface of the and can be accurately positioned during the subsequent clamping operation.

When shifting from the unclamped state to the clamped state, pressure is first applied to the hydraulic chamber 12 from the hydraulic port 18a of the rotary joint 18 through the passage 10c. At this time, first, the piston portion 10b moves downward in the drawing, that is, in the backward (clamping) direction, and the clamp rod 10b
The ball 9 moves along the cam surface 3d of the base 3 with the movement of. Then, the ball 9 moves toward the center by the small diameter portion of the cam surface 3d, and the neck portion of the pull stud 8 is sandwiched, so that the pull stud 8 is in a retaining state with respect to the clamp rod 10. Following the downward movement of 10, it moves downward integrally. Until the flat portion 5a of the pallet 5 contacts the base as shown in FIG. 2, the pressure in the hydraulic chamber 12 becomes a pressure value that overcomes the sum of the seal resistance of the clamp rod 10 and the elastic resistance of the spring 7. ing. At this time, the pressure causes the piston 11 to
Attempts to push the taper sleeve 14 upward, that is, in the forward direction via the pin 13, but since the elastic force of the disc spring 15 is stronger than the pressure value of the hydraulic chamber 12, the taper sleeve 14 is still in the backward limit. It is still pressed to the position. In this way, the pallet 5 serves as a reference plane,
It contacts the mounting surface of the base 3 and is positioned in the axial direction of the clamp rod 10.

After the flat portion 5a of the pallet 5 contacts the base 3, the pressure in the hydraulic chamber 12 rises to the supply pressure. The force by which the piston 11 pushes the tapered sleeve 14 against the disc spring 15 forward by this supply pressure is set to be sufficiently larger than the elastic force of the disc spring 15. Therefore, in the process of being pushed upward, the taper sleeve 14 comes into close contact with the taper surface 14b so that the taper portion 5c of the pallet 5 is pushed into the taper surface 14b as shown in FIG. At this time, the taper sleeve 14
Acts as a wedge between the circular hole 3g and the tapered portion 5c. As a result, the pallet 5 has a tapered portion.
Accurate centering by 5c, and surely clamped at the same time. During this time, the piston portion 10b has a larger pressure receiving area than the piston 11, and therefore the pallet 5 is pressed against the base 3 by the difference force.

In this way, the pallet 5 is accurately positioned with respect to the base 3 and is clamped with a strong force.
In this state, the workpiece fixed to the pallet 5 is subjected to necessary machining. If a predetermined amount of rotation of the worm 17 is applied during this processing, the base 3 rotates the pallet 5 with respect to the index table 2 while keeping the pallet 5 in a clamped state to index the pallet 5 to a desired angle. go. During this rotational indexing, the rotary joint 18 remains stationary, allowing the clamp rod 10 to rotate, thereby maintaining the required pressure from the piping system.

After processing, when moving from this clamped state to the unclamped state, the hydraulic port 18b of the rotary joint 18 is
Pressure is applied to the rear end side chamber from the cylinder chamber 3c. Then,
The clamp rod 10 moves upward, and at the same time, the ball 9 faces the large diameter portion of the cam surface 3d, so that the pull stud 8
Is released from the locked state with respect to the clamp rod 10, so that the pallet 5 is in an unclamped state. In addition,
The air pressure port 18c is connected to the pin hole 3a of the base 3 and the holding hole 10e at the upper end of the clamp rod 10. By sending air pressure from the air pressure port 18c, the cutting powder inside the taper hole 5e and the holding hole 10e is cut. Blow away etc.

Other Embodiments In the embodiments described above, the pull stud 8 is releasably engaged with the clamp rod 10 via the ball 9, but the present invention is not limited to this. For example, the pull stud 8 is clamped. It may be configured to be releasably engageable with a locking body such as a collet provided on the upper end side of the rod 10. Further, in the above-described embodiment, the example of the pallet on which the work is placed as the fixed object is described, but the fixed object may be the work itself. Further, the clamp rod 10 may be installed horizontally instead of vertically or at an appropriate tilt angle.

Effects of the Invention According to the present invention, the following effects are obtained. Since the fixed object such as a pallet has a flat part for determining the axial direction, a taper part for centering in the radial direction, and a tapered hole for determining the circumferential direction, the fixed object is fixed in the axial direction and the radius. Positioning can be performed with high accuracy in the direction and the circumferential direction. Further, even though the clamp mechanism is based on the taper portion, the bottom surface of the fixed object can be firmly fixed to the base by the taper sleeve, so that the clamped state has high rigidity. Further, since the piston mechanism is such that the retainer and the centering operation are sequentially performed, there is no loss in operating time, and since there is only one operating circuit, the circuit configuration can be simplified. In addition, since the mechanism is simple, the device itself can be made compact and the manufacturing cost can be reduced. Further, since the shape of the fixed object can be simplified, the manufacturing cost can be reduced.

[Brief description of drawings]

1 to 3 are cross-sectional views showing respective operating states of the clamp device according to the present invention. 1 ... Clamping device, 3 ... Base, 3c ... Cylinder chamber, 5 ... Pallet, 5a ... Flat part, 5c, ... Taper part, 5e ... Taper hole, 6 ... Taper pin, 8 ... Pull Stud, 10 ... Clamp rod, 10b ... Piston part, 1
1 ... Piston, 14 ... Tapered sleeve, 14b ... Tapered surface, 15 ... Disc spring.

Claims (4)

[Claims] 1. A base in which a circumferential positioning pin is provided upright, a positioning hole is provided at a position corresponding to the positioning pin of the base, and a bottom surface portion is axially provided at a predetermined position. A fixed object having a flat portion for positioning and a taper portion for centering in the radial direction is formed on the outer peripheral surface of the protruding portion protruding from the central portion of the bottom surface. Forming a piston part in the cylinder chamber of the base, with a pull stud fixed to the part,
A clamp rod slidably arranged by the piston portion and engageable with the tip of the pull stud, a piston having a pressure receiving area smaller than that of the piston portion slidably fitted in the clamp rod, and a piston above the piston. And a taper sleeve having a taper surface for holding the taper portion of the fixed object in close contact with the forward movement of the piston. . 2. The clamp device according to claim 1, wherein the fixed object is a pallet. 3. The clamp device according to claim 1, wherein the object to be fixed is a work. 4. The clamp device according to claim 1, wherein the base is supported so as to be indexable around the clamp rod as a center of rotation.