Work fixing device

A work fixing device capable of stably fixing the work, without any biasing, in the longitudinal direction of the work, of the fastening force for fixing the work. The moving mechanism of clamps is constructed by comprising a scroll disc as working disc forming a circular hole in which to insert the work at the center and scroll guides in spiral shape the winding direction of which is opposite to each other from the center toward the outer circumference on the both side faces, a rotary drive mechanism for rotatably driving this scroll disc, and scroll pieces having a fitting portion to be engaged with the scroll guides of the scroll disc and disposed on both sides of the scroll disc in a way to correspond to a plurality of clamps respectively.

BACKGROUND OF THE INVENTION

The present invention relates to a work fixing device, more specifically a work fixing device for gripping a work with circular section inserted in a hole formed in the main body of the work fixing device, comprising a plurality of clamps disposed movably along a guide groove formed in the radial direction in the main body of the work fixing device; and a clamp moving mechanism for synchronously moving the plurality of clamps in the radial direction.

Conventionally, when executing processing such as spinning, cutting, etc. on works with circular section (also including hollow works in tubular shape, in this specification), a variety of work fixing devices are used (JP 07-227733 A, for example), because of the necessity of fixing the work.

By the way, this type of work fixing device usually comprises, as shown inFIG. 11, a clamp moving mechanism3for moving a plurality of clamps2. However, with this arrangement, in which the clamp is supported and moved by the moving mechanism3disposed on either the back face or a side face of the clamp2, the fixing of work was liable to be limited only to the central part of the work or biased to one side.

For that reason, in the case of a long work or a work of soft metal such as aluminum, etc. or a hollow work in tubular shape with little rigidity, or in the case where the dimensional accuracy is rather low and variable, there was a problem that the work cannot be fixed accurately, eventually having negative influences on the working accuracy and operating efficiency.

SUMMARY OF THE INVENTION

The objective of the present invention, realized in view of such problems of the above-described conventional work fixing device, is to provide a work fixing device (i.e. a workpiece holding device) capable of stably fixing the work, without any biasing, in the longitudinal direction of the work, of the fastening force for fixing the work.

To achieve the above-mentioned objective, the work fixing device of this first invention is a work fixing device for gripping a work with circular section inserted in a hole formed in the main body of the work fixing device, comprising:

a plurality of clamps disposed movably along a guide groove formed in the radial direction in the main body of the work fixing device; and

a clamp moving mechanism for synchronously moving the plurality of clamps in the radial direction,

wherein

said clamp moving mechanism is composed of a working disc forming a hole, in which to insert the work at the center, and a scroll guide in spiral shape on both sides from the center toward the outer circumference respectively;

a rotary drive mechanism for rotatably driving the working disc; and

scroll pieces having a fitting portion to be engaged with the scroll guide of the working disc and disposed on both sides of the working disc in a way to correspond to a plurality of clamps respectively.

Moreover, to achieve the same objective, the work fixing device of this second invention is a work fixing device for gripping a work with circular section inserted in a hole formed in the main body of the work fixing device, comprising:

a plurality of clamps disposed movably along a guide groove formed in the radial direction in the main body of the work fixing device; and

a clamp moving mechanism for synchronously moving the plurality of clamps in the radial direction,

wherein

said clamp moving mechanism is composed of a working disc forming a hole in which to insert the work at the center, and a cam groove in spiral shape on both sides from the center toward the outer circumference respectively;

a rotary drive mechanism for rotatably driving the working disc; and

slide pieces having a fitting portion to be fit in the cam groove of the working disc and disposed on both sides of the working disc in a way to correspond to a plurality of clamps respectively.

In this case, it can be so arranged that the interval of the clamps disposed on both sides of the working disc may be a dimension larger than the diameter of the work.

Furthermore, it can be so arranged that the scroll pieces disposed on both sides of the working disc may be driven in linkage with one another.

Still more, it can be so arranged that the scroll pieces disposed on both sides of the working disc may be driven independently of one another.

According to the work fixing device of this first invention, by constructing the clamp moving mechanism with a working disc forming a hole, in which to insert the work at the center, and a scroll guide in spiral shape on both sides from the center toward the outer circumference respectively, a rotary drive mechanism for rotatably driving the working disc, and scroll pieces having a fitting portion to be engaged with the scroll guide of the working disc and disposed on both sides of the working disc in a way to correspond to a plurality of clamps respectively, the clamps come to be disposed on both sides of the working disc, and the fastening force for fixing the work is applied symmetrically across the working disc, thus enabling stable fixing the work without any biasing, in the longitudinal direction of the work, of the fastening force for fixing the work.

Moreover, according to the work fixing device of this second invention, by constructing the clamp moving mechanism with a working disc forming a hole in which to insert the work at the center, and a cam groove in spiral shape on both sides from the center toward the outer circumference respectively, a rotary drive mechanism for rotatably driving the working disc, and slide pieces having a fitting portion to be fit in the cam groove of the working disc and disposed on both sides of the working disc in a way to correspond to a plurality of clamps respectively, the clamps come to be disposed on both sides of the working disc, and the fastening force for fixing the work is applied symmetrically across the working disc, thus enabling stable fixing of the work without any biasing, in the longitudinal direction of the work, of the fastening force for fixing the work.

Furthermore, by setting the interval of the clamps disposed on both sides of the working disc for a dimension larger than the diameter of the work, it becomes possible to stably fix a long work or a work to be worked at both ends.

Moreover, by driving the scroll pieces disposed on both sides of the working disc in linkage with one another, it becomes possible to simplify the working disc and its rotary drive mechanism.

Additionally, by driving the scroll pieces disposed on both sides of the working disc independently of one another, it becomes possible to set the amount of movement of the clamps on both sides disposed on the scroll pieces independently for each side, and stably fix the work without any biasing, in the longitudinal direction of the work, of the fastening force for fixing the work, even in the case where the diameter is variable in the longitudinal direction or in the case of uneven works.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the work fixing device according to the present invention will be described below, with reference to drawings.

FIG. 1toFIG. 7show the first embodiment in which the work fixing device according to the present invention is applied to a device for spinning a work.

This work fixing device M is disposed in a way to face a spinning system S for executing drawing by spinning at both ends of the work W, which is, in this embodiment, a hollow work in tubular shape with a circular section forming a constriction in the intermediate part.

The work fixing device M, designed for gripping the work W with circular section inserted in a circular hole12formed on the main body1of work fixing device, comprises a plurality of clamps2disposed movably along a guide groove11formed in the radial direction in the main body1of the work fixing device, and a clamp moving mechanism3for synchronously moving the plurality of clamps2in the radial direction.

In this embodiment, a side disc10is fixed with a bolt B to the both side faces of the main body1of work fixing device, as shown inFIG. 3andFIG. 4, forming a circular hole12at the center of this side disc10, and forming a guide groove11so that the inner end side in radial direction may be continuous to this hole12.

The clamp moving mechanism3is constructed by comprising a scroll disc4as working disc forming a circular hole41in which to insert the work W at the center and scroll guides42a,42bin spiral shape the winding direction of which is opposite to each other from the center toward the outer circumference on the both side faces, a rotary drive mechanism5for rotatably driving this scroll disc4, and scroll pieces6having a fitting portion61to be engaged with the scroll guides42a,42bof the scroll disc4and disposed on both sides of the scroll disc4in a way to correspond to a plurality of clamps2(inFIG. 1, the clamp on the left side of the scroll disc4is named clamp2a, and the clamp on the right side is named clamp2b) respectively.

Here, the mounting of the clamp2to the scroll piece6is made by using an optional fastening means such as bolt, etc. At that time, it is desirable to accurately position the clamp2with a circular key62attached to the scroll piece6.

In this case, the construction of the scroll guides42a,42bin spiral shape of the scroll disc4is made with up-down groove in spiral shape of left hand wind from the center toward the outer circumference, as shown inFIG. 5A, for one scroll guide42a, and with up-down groove in spiral shape of right hand wind from the center toward the outer circumference, as shown inFIG. 5C, for the other scroll guide42b.

The fitting portion61, to be engaged with the scroll guides42a,42bof this scroll disc4, made of the up-down groove of the scroll piece6on which to attach the clamp2, is formed by changing the phase one after another, so that the tip of the clamp2attached to the scroll piece6may be positioned about on the concentric circle sharing the center with the circular hole41of the scroll disc4.

Moreover, in this construction, on the outer circumferential face of the scroll disc4is formed a gear43to be engaged with the rack gear51of the rotary drive mechanism5for rotatably driving the scroll disc4, as shown inFIG. 2, so as to turn the scroll disc4by operating the rack gear51of the rotary drive mechanism5with a push-pull drive of the hydraulic cylinder52(sliding of piston rod PR) (or by rotatably driving the worm gear (not illustrated) with an optional rotary drive mechanism such as motor, etc. or by hand).

The rack gear51is formed on a piston rod PR provided in the piston P of the hydraulic cylinder52, and the piston rod PR is made to slide in the hydraulic cylinder52without turning, by inserting a key K, disposed on the main body1of work fixing device, in the key groove KM formed in the piston rod PR. And, the sliding of the piston rod PR is made by selectively feeding an operating fluid to the cylinder chambers CY1, CY2of the hydraulic cylinder52. Furthermore, by blocking the hydraulic circuit leading to the cylinder chambers CY1, CY2of the hydraulic cylinder52, it becomes possible to fix the rotary drive mechanism5for rotatably driving the scroll disc4, and maintain the gripping force of the clamp2in a steady state.

As a result, by rotatably driving the scroll disc4with the rotary drive mechanism5, it becomes possible to move a plurality of clamps2, movably disposed along the guide groove11formed in the radial direction on the main body1of work fixing device, in the radial direction synchronously through the scroll pieces6, on both sides of the scroll disc4, because the scroll guides42a,42bin spiral shape formed on both side faces of the scroll disc4are spiraled in directions opposite to each other, thus enabling either fixing the work W with the clamp2or releasing the work W by the clamp2.

By the way, in this embodiment, the interval D1of the clamps2disposed on both sides of the scroll disc4through scroll pieces6is set for a dimension no less than the diameter D2of the work W. This enables to stable fixing of a long work or a work to be worked at both ends, by forming a constriction in the intermediate part, as shown in this embodiment.

Furthermore, when fixing a work (stepped pipe) W having a difference of diameter at gripping positions, as shown inFIG. 6, in the state in which the fitting portion61of the scroll piece6is engaged with the scroll guides42a,42bof the scroll disc4, remove the bolt B of the side disc10on one side, the side disc10on the right side inFIG. 3, for example, and turn the side disc10by a desired amount, and only the clamp2bon the right side inFIG. 3will be displaced in the radial direction (at that time, the clamp2aon the left side inFIG. 3is not displaced). If the side disc10is fixed at this position after displacement, the clamp2aand the clamp2bare displaced away from each other in the radial direction, enabling accurate gripping of a work (stepped pipe) W having a difference of diameter at gripping positions as inFIG. 6.

In addition, as a method for disposing the clamp2aand the clamp2bdeviated from each other, there is a method which consists in changing the mounting position of the clamps2against the scroll pieces6. To be concrete, the mounting position of the clamps2against the scroll pieces6can be changed, by either rotatably displacing the clamp2b-1against the scroll pieces6, as shown inFIG. 7A, thereby shifting the mounting position of the clamp2against the scroll pieces6by an amount equal to the difference between the dimension L1and the dimension L2, or by slidably displacing the clamp2b-2against the scroll pieces6, as shown inFIG. 7B, thereby shifting the mounting position of the clamp2against the scroll pieces6by an amount equal to the dimension L3. InFIG. 7B, DB is a bolt on which is formed a stepped part D, LS is a long slit, and H is a concave part in which is engaged the stepped part D.

At the base7of the work fixing device M are disposed, as shown inFIG. 1andFIG. 2, a horizontal moving mechanism71for moving the upper structure of the work fixing device M in the horizontal direction orthogonal to the working axis (center axis of the work W) of the spinning system S, and the drive system72for it, as well as a rotating mechanism73for turning the upper structure around a vertical axis, and the drive system74for it respectively.

The horizontal moving mechanism71and the drive system72have a nut72afor ball screw fixed to the bottom part of the table75in which are placed the upper structure of the work fixing device M and a ball screw72bto be engaged therewith disposed in parallel to the guide rail71aof the horizontal moving mechanism71, and is rotatably supported by a servo motor (not illustrated). This makes it possible to move the table75in the horizontal direction orthogonal to the working axis (center axis of the work W) of the spinning system S, by rotatably turning the ball screw72bwith the servo motor of the drive system72.

Moreover, the rotating mechanism73and the drive system74, disposed on the table75, are constructed in a way to turn the upper structure of the work fixing device M around a vertical axis.

This makes it possible to rotatably drive the upper structure of the work fixing device M around a vertical axis with the drive system74, and turn the direction of the upper structure by 180, for example, thus enabling drawing by spinning at both ends of the work W with a single unit of spinning system S, while fixing the work W with the work fixing device M, without making any change of gripping.

This work fixing device M, wherein the clamp moving mechanism3is constructed by comprising a scroll disc4as working disc forming a circular hole41in which to insert the work W at the center and scroll guides42a,42bin spiral shape the winding direction of which is opposite to each other from the center toward the outer circumference on the both side faces, a rotary drive mechanism5for rotatably driving this scroll disc4, and scroll pieces6having a fitting portion61to be engaged with the scroll guides42a,42bof the scroll disc4and disposed on both sides of the scroll disc4in a way to correspond to a plurality of clamps2respectively, can stably fix the work W, without any biasing, in the longitudinal direction of the work W, of the fastening force for fixing the work W, because the clamp2is disposed on both sides of the scroll disc4and the fastening force for fixing the work W is applied symmetrically across the working disc4.

By the way, while in the above-described first embodiment, the working disc is composed of a scroll disc4, this working disc may be composed of a cam groove disc4A forming cam grooves44a,44bin spiral shape on both side faces spiraled in opposite directions from the center toward the outer circumference, as in the second embodiment shown inFIG. 8, in place of this scroll disc4.

In this embodiment, the projection (cam follower)63to be fit in the cam grooves44a,44bis provided in protrusion on the slide piece6A, to rotatably drive, through the gear43A, the cam groove disc4A with a proper drive mechanism (not illustrated), so as to synchronously move, through the slide piece6A, a plurality of clamps2disposed movably along the guide groove11formed in the radial direction in the main body1of the work fixing device, in the same way as in the first embodiment, thus enabling either fix the work W with the clamps2or release the fixing of the work W by the clamps2.

Other constructions and actions of this embodiment are identical to those of the first embodiment explained above.

Moreover, in the above-described first embodiment, the scroll disc (working disc)4as moving mechanism3of the clamps2is composed of a single-piece member, and this scroll disc4is rotatably driven by a single rotary drive mechanism5, to drive the scroll pieces6,6disposed on both sides of the scroll disc4in linkage with each other, so as to align at both ends the amount of movements of the clamps2a,2bon both sides disposed on the scroll pieces6,6. However, it is also all right to drive the scroll pieces6,6disposed on both sides of the scroll disc4independently on each side, in place of above, as in the third embodiment shown inFIG. 9andFIG. 10, thus enabling setting of the amount of movement of the clamps2a,2bon both sides disposed on the scroll pieces6,6independently on each side.

More specifically, in this first embodiment, the scroll disc4as moving mechanism3(3a,3b) of the clamps2is split into 2 parts i.e. scroll disc4aon the left side and scroll disc4bon the right side jointed to each other at one side face, as shown inFIG. 9, and these scroll discs4a,4bare rotatably driven by separate rotary drive mechanisms5a,5brespectively, to enable to drive the scroll pieces6,6disposed on both sides of the scroll discs4a,4bindependently on each side.

And, as shown inFIG. 9andFIG. 10, it is so arranged that the scroll discs4a,4bare rotatably driven by the rotary drive mechanisms5a,5bat two points in the direction of diameter. To be concrete, the scroll disc4ais pushed and turned upward (PA-1→PA-2) by the rotary drive mechanism5a, and the scroll disc4bis pushed and turned downward (PB-1→PB-2) by the rotary drive mechanism5b, to drive the scroll pieces6,6disposed on both sides of the scroll discs4a,4bindependently on each side. This presents an advantage of reducing the influences of the load due to rotary drive mechanisms5a,5bon the side disc10providing a bearing function to the scroll discs4a,4band on the bearing on the inner circumferential side constituting the hole41, compared with the case in which the scroll discs4a,4bare rotatably driven downward together (or upward together) by the rotary drive mechanisms5a,5bat two points in the direction of diameter.

Furthermore, the pistons Pa, Pb of the rotary drive mechanisms5a,5bof the scroll discs4a,4bare offset by a distance L on both sides from the center line SL constituting the jointing face of the scroll discs4a,4b, and the rack teeth Ra, Rb are cut off on both sides to avoid interference.

The rotary drive mechanisms5a,5bof the scroll discs4a,4bmay take an optional construction of disposition other than that disposing face to face at two points in the direction of diameter of the scroll discs4a,4b, such as disposing rotary drive mechanism5aand the rotary drive mechanism5bin the perpendicular direction, for example, as shown in this embodiment.

Still more, for the rotary drive mechanisms5a,5bof the scroll discs4a,4b, it is also all right to use any optional drive source other than the rodless cylinder as shown in this embodiment, such as ordinary cylinder having piston rod, for example, to drive the rack teeth Ra, Rb, through a drive force transfer mechanism.

And, by enabling the amount of movement of the clamps2a,2bon both sides to be set independently for each side, it becomes possible to stably fix the work W without any biasing, in the longitudinal direction of the work W, of the fastening force for fixing the work W, even in the case where the diameter is variable in the longitudinal direction or in the case of an uneven work W.

Other constructions and actions of this embodiment are identical to those of the first embodiment described above.

Explanation has so far been made on the work fixing device of the present invention, based on embodiments in which the work fixing device is applied to a system for executing spinning on the work. However, the present invention is not restricted to the constructions described in the above-mentioned embodiments, but may allow changes to its construction as necessary in the range not deviating from its purpose, such as combining the constructions described in the respective embodiments as desired or using fixing device in processing other than spinning and cutting, etc.

The work fixing device of the present invention, capable of stably fixing the work, without any biasing in the longitudinal direction of the work, can be suitably used for applications of fixing the work, in the case executing processing such as spinning, cutting, etc. on the works of a variety of shapes and properties.