JPH1128631A - Pallet clamp device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the rigidity of a clamp by causing the tapered surfaces of a clamp member, a collet inside-diameter portion, a member to be clamped, and a collet outside-diameter portion to make contact with and press against one another in the form of a ring during clamping. SOLUTION: Pressure oil is supplied to a cylinder chamber 14a via an oil passage 15a to lower a piston 19 and a clamp member 21. The second tapered surface 20 of the clamp member 21 thereby presses the tapered surface 27 of the inside diameter portion of a collet 23, causing the split pieces 23a, 23b, 23c... of the collet to move against the energizing force of an energizing member 25 in the direction to leave an axis along a guiding part 18; i.e., the diameter of the collet 23 increases, and the tapered surface 24 of its outside diameter portion presses the first tapered surface 13 of a member 11 to be clamped, clamping a pallet 2 strongly against pallet support 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pallet clamping device capable of placing a workpiece replacement pallet of a machine tool on a table in a clamped / unclamped state.

[0002]

2. Description of the Related Art In a numerically controlled machine tool such as a machining center, in order to continuously process a large number of workpieces by automatic operation, the workpieces are loaded on a pallet, and a pallet loaded with the processed workpieces is mounted on a table. Unload,
Instead, an automatic pallet changer (hereinafter, referred to as “AP”) is used to carry a pallet loaded with unprocessed work in a pallet pool line or a preparation station onto the table.
C ". ) Is used.

In order to clamp a pallet carried on a table by the APC, a pallet guide that moves up and down on the table is provided, and the upper end of the pallet guide is set to T.
In general, the pallet is formed in a letter shape and engaged with a T-shaped groove formed on the lower surface of the pallet, and then the pallet guide is lowered to clamp the pallet. Also, recently, in order to shorten the pallet replacement time, an APC that directly replaces the pallet on the table has been devised. In this case, the pallet carried on the table is lowered to clamp the pallet on the table. Transfer to the engagement position of the member,
A method is employed in which a clamped member provided on the lower surface of a pallet is pressed and clamped. As a clamp device employing this clamp system, Japanese Utility Model Publication No. 2-6965,
An apparatus such as Japanese Utility Model Publication No. Hei 7-46433 is disclosed.

[0004]

However, actual fairness 2-6
In the method disclosed in Japanese Patent Publication No. 965, a cylindrical collet member provided with a slit is formed along a tapered tapered surface formed at the distal end of a fixed shaft, and the diameter of a flange formed at an end of the collet member is increased. However, a large pull-down stroke is required for clamping and unclamping, and a thin portion is required to expand and reduce the diameter by using a slit. It is low and is not suitable when a large clamping force is required. Further, there is a problem that stress is concentrated on the slit portion and the collet member is easily damaged.

Japanese Utility Model Publication No. Hei 7-46433 discloses that a clamp member is engaged with a plurality of engagement grooves provided at one end of a piston body, and interlocks with the operation of the piston body in a direction perpendicular to the axis of the table. A device for clamping a pallet by pressing a clamped member provided on the lower surface of a pallet so as to move a clamp member forward and backward has been disclosed. However, a plurality of clamp members are formed by dividing one end of a piston body in a circumferential direction. In this case, the components such as the connection member, the engagement member, and the engagement guide member have complicated shapes, and the number of clamp members cannot be increased. Further, in order to increase the clamping force, it is necessary to increase the inclination angle of the engaging member. Although it is conceivable to increase the thrust of the piston body, there is a limit depending on the specification of the hydraulic power source. Under such a configuration, the member to be clamped cannot be pressed in a ring shape, but is pressed at a point arranged on the circumference, and the rigidity of the clamp cannot be increased. Further, when trying to increase the inclination angle in order to increase the clamping force, it is necessary to increase the length of the inclined surface of the engaging member required to move the clamp member by a required amount, but there is a limit to the actual length. The clamping force could not be increased because of the fact that the pallet could not be moved up and down in order to shorten the pallet replacement time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a pallet capable of increasing the clamping rigidity, shortening the time required for clamping and unclamping operations, and obtaining a stable operation. A clamping device is provided.

[0007]

In order to solve the above problems, the present invention has the following arrangement. That is, in a pallet clamping device that detachably clamps a pallet to a table of a machine tool, a pallet support attached to the table along the axis of the table, and a pallet that can be inserted from the outside on the lower surface of the pallet. A clamped member having a first tapered surface having an inner diameter portion that gradually decreases in diameter toward the lower side of the axis, and the pallet support is inserted and provided so that the pallet support can be moved forward and backward by fluid pressure. An operating piston body, a clamp member provided at one end of the piston body and having a second tapered surface on an outer diameter portion that gradually decreases in diameter toward the lower side of the axial center; a cylindrical portion on the outer diameter portion; Having a tapered surface that engages with the tapered surface of
The inner diameter portion has a tapered surface that engages with the second tapered surface, and is composed of a plurality of wide and narrow divided pieces that are divided in the circumferential direction. A biasing member wound around the cylindrical portion of the diameter portion to bias the collet in the center direction; and a guide portion provided on an upper surface of a cylinder cover fixed to an upper portion of the pallet support, for guiding the collet freely and widely. When the piston body descends due to the fluid pressure, the second tapered surface of the clamp member presses and engages with the tapered surface of the inner diameter portion of the collet, and the collet expands in diameter along the guide portion. The tapered surface of the outer diameter portion presses and engages with the first tapered surface of the clamped member to clamp the pallet on the pallet support. The engagement between the first tapered surface and the tapered surface of the outer diameter of the collet member is released, thereby unclamping the pallet from the pallet support, the collet is configured to diameter by the biasing member.

In the above means, the pallet is lifted by a biasing force of a spring provided between the lower surface of the piston body and the pallet support without using fluid pressure to raise the piston body. The collet was unclamped from the support and the collet was reduced in diameter by the urging member.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When clamping a pallet carried on a table by APC, the diameter of a collet annularly arranged on the outer periphery of a clamp member is reduced so that the pallet can be inserted in advance, and the outer diameter of the upper part of the collet is reduced. It should be smaller than the inner diameter of the clamped member provided on the lower surface of the pallet. That is, the piston body inserted and retracted into the pallet support attached to the table along the axis of the table is raised by fluid pressure and formed on the outer diameter portion of the clamp member provided at one end of the piston body. The engagement between the second tapered surface and the tapered surface of the inner diameter of the collet is released, and the divided pieces of the collet are provided on the upper surface of the cylinder cover fixed to the upper portion of the pallet support by the urging force of the urging member. The outer diameter of the upper portion of the collet is smaller than the inner diameter of the member to be clamped.

In this state, the pallet is lowered from above the table to a position where the positioning pin provided on the pallet and the bush provided on the pallet support engage with each other by the APC, and is mounted on the pallet support.

Next, when the piston body is lowered by fluid pressure,
The second tapered surface of the clamp member presses the tapered surface of the inner diameter portion of the collet, and each of the divided pieces of the collet moves outward along the guide portion against the urging member, whereby the collet is moved. The diameter is increased, and the tapered surface of the outer diameter portion of the collet presses the first tapered surface of the clamped member to clamp the pallet.

To unclamp the pallet, as described above, the piston body is raised to reduce the diameter of the collet, the pressing state between the collet and the first tapered surface is released, and the outer diameter of the upper part of the collet is clamped. Make it smaller than the inside diameter of the member.

In another aspect of the invention, attention is paid to the fact that a large force is not required to raise the piston body, and the piston is actuated by the urging force of a spring provided between the lower surface of the piston body and the pallet support without using fluid pressure. I'm raising my body.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the first embodiment, showing a part of a table 1 and an entire clamp device.
FIG. 2 is a cross-sectional view of a main part of the clamp device showing a state where the pallet 2 is unclamped in the first embodiment. FIG. 3 is a cross-sectional view of a main part of the clamping device showing a state where the pallet 2 is clamped in the first embodiment. FIG. 4 is a plan view of the collet split pieces 23a, 23b, 23c,..., And FIG. In this embodiment, a pair of couplings is provided below the pallet support 3 so that the pallet support 3 on which the pallet 2 is clamped can rotate and index around the axis of the table 1 as shown in FIG. 4 and the gear 5 are fixed, and the cylinder 6, the piston 7 and the like are incorporated between the table 1 and the table 1. However, the description is omitted because it is not directly related to the present invention.

1 to 3, a positioning pin 8 is fixed to the pallet support 3, and a bush 9 is fixed to the lower surface of the pallet 2 at a position corresponding to the positioning pin 8. Further, a member to be clamped 11 is fixed to the lower surface of the pallet 2 with bolts 12, and a concave portion 10 which is a circular space is formed inside the member 11. A first tapered surface 13 is formed at a lower portion of the inner diameter of the clamped member 11 so as to gradually reduce its diameter toward the lower side of the axial center.

Next, the table 1 is provided with a pallet support 3 which is rotatable and indexable about its axis. The pallet support 3 has cylinder chambers 14a and 14b formed along its axis. , Cylinder chambers 14a, 14b
The oil passages 15a and 15b communicating with are formed. A cylinder cover 16 is fixed to the upper portion of the pallet support 3 with bolts 17 to form a part of the cylinder chambers 14a and 14b, and a collet 23 to be described later is reduced in diameter or enlarged on the upper surface of the cylinder cover 16. An annular guide portion 18 is formed to guide the collet split pieces 23a, 23b, 23c. A seal member 31 is attached to the cylinder cover 16 so that chips and cutting agents during work processing do not enter the inside of the clamp device.

Further, a piston body 19 is inserted into the cylinder chambers 14a and 14b so as to be able to advance and retreat.
It can move up and down by pressure oil supplied via oil passages 15a and 15b communicating with 4a and 14b. A clamp member 21 having an outer diameter portion having a second tapered surface 20 whose diameter gradually decreases toward the lower side of the axial center is fixed to an upper portion of the piston body 19 by a bolt 22.

On the outer periphery of the clamp member, a plurality of wide and narrow collet divided pieces 23a, 23 divided in the circumferential direction are provided.
A collet 23 composed of b, 23c,... is arranged in an annular shape, and a tapered surface 24 engaging with the first tapered surface 13 and a cylindrical portion 26 are formed on an outer diameter portion of the collet 23. Is formed with a tapered surface 27 that engages with the second tapered surface 20. The cylindrical portion 2 of the collet 23
6 includes collet divided pieces 23a, 23b, 23c,.
Urging member 25 for urging the actuator to move in the axial direction
Is wound. As shown in FIG. 2, in the state where the tapered surface 27 of the inner diameter portion of the collet 23 is not pressed by the second tapered surface 20, that is, in the unclamped state, the outer diameter of the upper part of the collet 23 whose diameter has been reduced is covered. Clamp member 1
1 is smaller than the minimum inner diameter.

The operation of the first embodiment described above will be described. First, pallet 2 is placed on pallet support 3
Before mounting on the device, the clamp device is in an unclamped state as shown in FIG. That is, in FIGS. 1 and 2, when pressure oil is supplied to the cylinder chamber 14 b through the oil passage 15 b to raise the piston body 19, the second tapered surface 20 and the tapered surface 27 of the inner diameter portion of the collet 23 are in contact with each other. The engagement is released, and the divided pieces 23a, 23b, 23c of the collet are released.
Move in the axial direction along the guide portion 18 by the urging force of the urging member 25, and the outer diameter of the collet 23 is reduced. When the outer diameter of the collet 23 is reduced, the collet 2
The engagement between the tapered surface 24 of the outer diameter portion and the first tapered surface 13 is released, the unclamped state is reached, and the outer diameter of the upper portion of the reduced collet 23 is reduced in the next step. Is smaller than the minimum inner diameter of the clamped member 11 fixed to the lower surface of the pallet 2 to be placed on the pallet 2.

In this state, the pallet 2 is carried into the table side by APC (not shown) and is lowered from above. As shown in FIG. 1, the pallet 2 is fixed to the lower surface of the pallet 2 and to the pallet support 3 as shown in FIG. The pallet 2 is placed at a predetermined position. At this time, the upper portions of the clamp member 21 and the collet 23 enter into the concave portion 10 formed on the lower surface of the pallet 2 at the same time.

Next, in FIGS. 1 and 3, pressure oil is supplied to the cylinder chamber 14a through the oil passage 15a, and
9 and the clamp member 21 are lowered, the second tapered surface 20 of the clamp member 21 presses the tapered surface 27 of the inner diameter portion of the collet 23, and each of the divided pieces 23a, 23 of the collet 23
.. move in a direction away from the axis along the guide portion 18 against the urging force of the urging member 25. That is, the collet 23 expands in diameter, and the tapered surface 24 presses the first tapered surface 13, thereby firmly clamping the pallet 2 to the pallet support 3. In this embodiment, the outer diameter portion of the clamp member 21 and the inner diameter portion of the collet 23 are each provided with two tapered surfaces in order to obtain a stable operation, but the same applies to one.

When the pallet 2 is to be replaced, as described above, pressure oil is supplied to the cylinder chamber 14b through the oil passage 15b to raise the piston body 19 to be in an unclamped state, and then the pallet 2 is subjected to APC. Raise and replace.

Next, a second embodiment of the present invention will be described.

FIG. 6 is a sectional view of a main part of a clamping device according to a second embodiment, and shows a state where the pallet 2 is clamped. In FIG. 6, a plurality of springs 28 are attached to a plurality of spring storage portions 30 provided on the circumference at positions corresponding to the lower surface of the piston body 19 and the step portion 29 of the pallet support 3, respectively, to raise the piston body 19. Is being biased. Except that the spring 28 is provided, that the oil passage 15b is not provided in the first embodiment, and that no pressure oil is supplied to the cylinder chamber 14b, it is not necessary to use a sealing structure using a sealing member. The rest is the same as the configuration of the first embodiment.

The operation of the second embodiment will be described focusing on differences from the first embodiment. First, pallet 2
1 and 6, the supply of pressure oil to the oil passage 15a is stopped and the oil passage 15
The pressure in a is set to atmospheric pressure. Then, piston body 1
9 is raised by the urging force of the spring 28, and the clamp device is in the unclamped state as described in the first embodiment.
The collet 23 is reduced in diameter.

In this state, the operation of clamping the pallet 2 placed on the pallet support 3 by APC is the same as that of the first embodiment.

[0028]

As described above, according to the pallet clamping apparatus of the present invention, the second tapered surface of the clamp member and the tapered surface of the inner diameter portion of the collet, and the first tapered surface of the member to be clamped and the outer diameter of the collet. Since the tapered surfaces of the portions contact and press in a ring shape during clamping, the rigidity of the clamp can be increased. Further, the collet divided piece pressed by the second taper surface by pressing down the piston body presses the first taper surface to clamp the pallet, and the force is transmitted through the inclined surface. Therefore, the thrust of the piston body largely acts as a clamping force for pressing the member to be clamped by the wedge action of the inclined surface, and the clamping force can be increased. Furthermore, with a simple configuration, a reliable unclamping state and a clamping state can be obtained only by slightly moving the piston body having the clamping member up and down a little, so that the clamping / unclamping operation can be performed in a short time and the failure can be prevented. A small and stable clamp / unclamp operation can be obtained.

By arranging a spring between the lower surface of the piston body and the pallet support, the structure can be further simplified and the same effects as described above can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the entirety of a first embodiment.

FIG. 2 is a sectional view of a main part showing a state where the pallet is unclamped in the first embodiment.

FIG. 3 is a sectional view of a main part showing a state where the pallet is clamped in the first embodiment.

FIG. 4 is a plan view of a collet.

FIG. 5 is a sectional view of a collet.

FIG. 6 is a sectional view showing a state where a pallet is clamped in the second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 table 2 pallet 3 pallet support 11 clamped member 13 first tapered surface 18 guide 19 piston body 20 second tapered surface 21 clamp member 23 collet 25 urging member

Claims (2)

[Claims] 1. A pallet clamping device for detachably clamping a pallet carried into a table of a machine tool, wherein a pallet support attached to the table along an axis of the table and a pallet can be inserted from outside. A member to be clamped, which is provided on the lower surface of the pallet and has a first tapered surface having an inner diameter portion that gradually decreases in diameter toward the lower side of the axial center, and provided by inserting the pallet support into the pallet support. A piston member operable to advance and retreat by a fluid pressure; a clamp member provided at one end of the piston member and having a second tapered surface on an outer diameter portion that gradually decreases in diameter toward a lower portion of the axial center; It has a cylindrical portion and a taper surface that engages with the first taper surface, has an inner diameter portion that has a taper surface that engages with the second taper surface, and has a plurality of circumferentially divided wide and narrow divisions. From it, it is wound around the cylindrical portion of the outer diameter portion of the outer peripheral collet and the collet arranged annularly of said clamp member,
A biasing member for biasing the collet in the center direction; and a guide portion provided on an upper surface of a cylinder cover fixed to an upper portion of the pallet support and guiding the collet in a wide and narrow manner. As a result, the second tapered surface of the clamp member presses and engages the tapered surface of the inner diameter portion of the collet, and the collet expands in diameter along the guide portion. The pallet is clamped to the pallet support by being pressed and engaged with the first tapered surface of the clamp member. When the piston body rises due to the fluid pressure, the first tapered surface of the clamped member and the outer diameter of the collet are formed. The engagement with the tapered surface is released, the pallet is unclamped from the pallet support, and the diameter of the collet is reduced by the urging member. That the pallet clamping device. 2. The pallet clamping device according to claim 1, wherein said piston body is raised by a spring provided between said piston body and said pallet support.