JPH0474153B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gripping device that can serve as both an internal grip and an external grip.

[Conventional technology and its problems]

Conventionally, there is a gripping device shown in FIG. 5 that can be used for both internal and external gripping. In this gripping device, a pair of gripping plates 20 as shown in the figure are overlapped with their center grooves 21 aligned, a support pin 23 connected to a drive shaft 22 is engaged with the groove 21, and each gripping plate is 20 is rotatably connected to a fixed base or the like via a pin 24, and when the drive shaft 22 is moved straight in the direction of the arrow, the support pin 23 and pin 2
4 as a fulcrum, the tips of each gripping plate 20 rotate in the approaching and separating directions, and the workpiece is gripped therebetween.

However, in the above gripping device, the pin 2 is inserted into the hole.
4 are fitted and rotated, there is a problem in that there is fitting play between the two, resulting in poor gripping accuracy. In addition, the engaging part can be lubricated-free, and the support pin 2
3 and the groove 21 are opened and closed by swinging, rust and wear are likely to occur in the engaging portion due to the swinging action, and as a result, the play in the engaging portion increases and the movement of the gripping plate 20 is reduced. The disadvantage is that it causes wobbling.

Furthermore, since the force is transmitted using a lever via the support pins 23 and pins 24, it is difficult to set the input to the drive shaft 22 to obtain a predetermined gripping force, making it difficult to obtain an accurate gripping force. There is also the problem that it is difficult.

The present invention has been made in view of the above problems, and aims to provide a gripping device that can maintain good gripping accuracy over a long period of time and can accurately set gripping force.

[Means for solving problems]

In order to solve the above problems, the present invention provides a split collet which is equipped with a work support arm at its tip, has a slit that opens from the rear end toward the tip, and has tapered surfaces on the inside and outside of the rear end. a wedge member that engages the inner tapered surface of the split collet; a tightening member that engages the split collet with the outer tapered surface; and the tightening member and the wedge member are fixed in the axial direction of the split collet. and a drive means for driving in the axial direction while maintaining the positional relationship, and the inner and outer tapered surfaces are each formed into a cylindrical tapered surface whose diameter decreases from the rear end to the tip of the split collet. be.

[Effect]

In the gripping device configured as described above, when the wedge member is driven by the driving means and engages with the tapered surface on the inside of the split collet, the split collet is opened outward and the support arm grips the workpiece from the inside. On the other hand, when the tightening member engages with the tapered surface on the outside of the split collet, the split collet contracts inward, and the support arm grips the workpiece from the outside.

The above deformation of the split collet is carried out by deforming the collet through the engagement of the cylindrical tapered surfaces, and by expanding and closing the tip using the rear end as a fulcrum due to the deflection of the collet material. There is no play or wobbling that occurs with rotating or sliding members, and high repeatable gripping accuracy can be achieved.

〔Example〕

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

As shown in FIG. 1, a hydraulic cylinder 1 has a piston 3 provided with a tapered surface 2a and a wedge pin 2 with a tapered tip on the inside so as to be movable in the front-rear direction. is provided with an oil supply port 4 and an oil discharge port 5.

A split collet 7 is attached to the side surface of the hydraulic cylinder 1 with screws 6, and a sleeve 9, which is a tightening member, is attached to the outside of the split collet 7 via a sleeve guide 8 so as to be movable in the front-rear direction. There is. The sleeve 9 and the sleeve guide 8 are attached with their central axes positioned on the center line of the split collet 7.

The split collet 7 is provided with a slit 10 whose distal end side is open in the front-rear direction, and is designed to elastically deform in the direction in which the distal ends approach and separate from each other using the rear end as a fulcrum. ,
A pair of workpiece support arms 12 are attached with screws 11.

A through hole 13 through which the wedge pin 2 is inserted is formed at the rear end of the split collet 7, and a tapered surface 10a whose diameter decreases toward the tip is provided on the front side of the inside of the slit 10. As shown in FIG. 2, when the wedge pin 2 moves forward, the tapered surface 2a at its tip comes into sliding contact, pushing the collet 7 outward and opening the tip of the support arm 12.

As shown in FIGS. 1 and 3, the sleeve 9 includes:
A tapered surface 9a whose diameter decreases toward the tip is formed on the inside of the tip end, and is connected to the wedge pin 2 via a connecting pin 14. In addition, Wari collection 7
The slit 10 is formed in a size that allows the connecting pin 14 to move freely. In the case of the above structure, the connecting pin 14 and the hydraulic cylinder 1 constitute the driving means referred to in the claims, and the wedge pin 2 and the sleeve 9 are divided to maintain a fixed positional relationship in the axial direction of the collet 7. and drive it in its axial direction.

On the other hand, the outer surface of the split collet 7 is formed with a tapered surface 7a that becomes smaller in diameter toward the tip and engages with the tapered surface 9a of the sleeve 9.

A mounting arbor 15 is attached to the rear surface of the hydraulic cylinder 1, and the shape of the arbor 15 can be arbitrarily set depending on the machine and position to be used.

The gripping device of this embodiment has the above-mentioned configuration, and as shown in FIG.
The collet 7 is deformed so as to open outward by slidingly contacting the collet 7. As a result, the support arm 12 at the tip of the collet 7 opens outward and grips the workpiece from the outside.

At this time, the tapered surface 9a of the sleeve 9 and the tapered surface 7a of the collet 7 come into contact with each other, thereby preventing fatigue failure in the opening direction of the portion A of the collet 7.

On the other hand, when the wedge pin 2 is moved backward by the drive of the hydraulic cylinder 1, the connecting pin 14 moves to the rear end of the slit 10 provided in the collet 7, as shown in FIG. move it backwards. By this movement, the tapered surface 9a at the tip of the sleeve 9 comes into sliding contact with the outer tapered surface 7a of the collet 7, deforming the collet 7 so as to close it inward. This action allows the support arm 12 to grip the workpiece from the outside.
At this time, the tapered surface 7a of the collet 7 shown in FIG.
The outer diameter of the cracked surface of the sleeve 9 is the tapered surface 9a of the sleeve 9.
This prevents fatigue failure in the closing direction at the A part of the collet 7.

In the gripping device having the above configuration, the wedge pin 2
By moving the collet 7 back and forth, the direction of deformation of the collet 7 is changed, so the gripping direction of the inner grip and the outer grip can be easily changed.

In addition, the deformation of the split collet 7 is caused by the wedge pin 2.
This is done by moving the sleeve 9 on the same center line with respect to the collet 7 and bringing the tapered surfaces into contact with each other, so there is no play or backlash in the contact area, and high gripping accuracy and repeatability can be obtained. In addition, even after repeated use over a long period of time, the abrasion of the contact portion is extremely small, and gripping accuracy can be maintained for a long time.

The gripping force P in the gripping device with the above configuration is, in the case of inside gripping, as shown in FIG.
Let θ be the angle formed by the tapered surface 2a of the cylinder 1.
When the driving force is F, it is given by the following formula: P=F/tan(θ/2+λ). Here, λ is the friction angle.
That is, by setting the angle θ of the tapered surface 2a to a predetermined value, an accurate gripping force relative to the driving force F can be obtained. The outer grip is also exactly the same as above.

Moreover, repeated fatigue failure of the part A shown in FIGS. 2 and 3 occurs when opening and closing is performed by the tapered surface 9a of the sleeve 9 interlocking with the wedge pin 2. Therefore, if the range of this gap is regulated within the limit of the repeated bending fatigue of part A, regardless of the strength of the gripping force, that is, the strength of the external force, A No fatigue failure will occur.

In this embodiment, a hydraulic cylinder is used as the drive means, but this can be replaced with a drive mechanism that performs reciprocating operation, such as an electromagnetic solenoid.

〔Effect of the invention〕

The gripping device of the present invention is configured as described above,
Since the wedge member and the tightening member are moved relative to the split collet, and the taper surface and the inclined surface are engaged to deform the collet, there is no play or rattling in the engaging part, and high gripping accuracy can be maintained over a long period of time. You can get it by passing.

Further, by appropriately selecting the taper angle of the tapered surface, there is an advantage that a predetermined gripping force can be accurately set in response to the drive input, and reliable gripping can be performed.

Furthermore, since we want the inner and outer tapered surfaces of the split collet to be tapered surfaces with inclinations in the same direction, and to drive the wedge member and tightening member in conjunction with each other, we set the engagement position for each tapered surface appropriately. This makes it possible to set the change from internal grip to external grip in an extremely short time.

In addition, by making the inner and outer tapered surfaces slope in the same direction, the amount of opening and closing of the split collet is determined within the gap between the inner and outer tapered surfaces and the wedge member or tightening member. By regulating the range within the fatigue limit of the weakest part of the splitting collet, fatigue failure of the splitting collet can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a partially vertical front view of an embodiment according to the present invention, FIGS. 2 and 3 are sectional views of essential parts showing the same action, respectively, FIG. 4 is a perspective view of the split collet shown above, and FIG. The figure shows a conventional gripping device, and FIG. 6 is a schematic diagram showing the main part of FIG. 3. 1...Hydraulic cylinder, 2...Wedge pin, 7...
...Split collet, 9...Sleeve, 10...Slit, 12...Work support arm, 14...Connecting pin.

Claims (1)

[Claims] 1. A split collet equipped with a work support arm at the tip, a slit that opens on the tip side from the rear end toward the tip, and tapered surfaces on the inside and outside of the rear end, and the inside taper surface of the split collet. a wedge member that engages with the split collet; a tightening member that engages with the outer tapered surface of the split collet; the inner and outer tapered surfaces are each formed into a cylindrical tapered surface whose diameter decreases from the rear end to the tip of the collet.