JPH0212009Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention relates to an improvement plan for the top or soft jaw of a nail chuck.

[Conventional technology]

A well-known scroll chuck has a structure as shown in FIG. That is, a bevel pinion 5 and a scroll tooth 6 that rotates while meshing with the bevel pinion 5 are provided inside the chuck body 4, and the scroll tooth 6 is slidable in a radial dovetail groove 7 provided on the upper surface of the main body 4. Master Jiyo 2 inserted into
are interlocking. This Master Jiyo 2 is the third
As shown in the figure, the protrusions 2a on both sides engage guide grooves 7a in the dovetail groove 7 and are movably attached, and the racks 2b on the bottom mesh with the scroll teeth 6. To open and close the pawl 3, turn the bevel pinion 5 with a chuck wrench to rotate the scroll teeth 6.
This is done by moving the master yaw 2 meshing with the scroll in the radial direction.

There are two types of claws 3 that are standardly used: one for bolting the top jaw to the master jaw 2, and one for bolting the soft jaw 1 as shown in FIG. The top gripper is also called a hard gripper, in which a hardened workpiece gripping surface is preformed in multiple stages on the radial end face, and a large gripping force can be obtained. Used for gripping.

On the other hand, the Soft Jyo 1 is usually made of unhardened carbon steel, and the purchaser can optionally process the workpiece gripping surface according to the shape of the workpiece, so it can achieve uniform contact with the workpiece. , high gripping accuracy can be obtained. Therefore, it is often used for finishing machining and machining that requires high machining accuracy.

[Problem that the invention attempts to solve]

In a chuck having the above structure, when the chuck is used for a long period of time, the protrusion 2a of the master jaw 2 slides within the guide groove 7a many times, causing the sliding surface to wear out. However, as shown in FIG. 3, a large gap 8 is created between the protrusion 2a and the guide groove 7a. In such a state, even if the soft or top jaw is replaced with a new one, when a workpiece is actually clamped, the master jaw 2 will lift up by the gap 8, and the workpiece gripping surface will no longer come into accurate contact with the workpiece surface.

In this case, the lifting of the master jaw 2 is caused by the clamping force being applied to the workpiece gripping surface 11 in the structure shown in FIG. The end is pushed down so that it is tilted in the length direction. That is, the protrusion 2a at the end opposite to the workpiece gripping surface 11 contacts the bottom surface of the guide groove 7a, and the guide groove 7a on the workpiece gripping surface side uses the contact position as a fulcrum.
is pressed against the upper surface of the guide groove 7a.

This becomes a big problem especially in the case of the soft jaw 1 used for finishing. In other words, even if an attempt is made to form an accurate gripping surface that matches the workpiece, the workpiece gripping surface cannot be processed accurately due to the wobbling of the master yaw 2, and as a result, the workpiece gripping surface does not match the workpiece shape, resulting in the stability of the workpiece. It is not possible to obtain accurate gripping or high centering accuracy.

To deal with the above-mentioned problems, conventionally, in soft jaws, when machining the workpiece gripping surface, a ring for fixing the soft jaw 1 from the outside is attached to the chuck body 4 with bolts, etc., and each soft jaw 1 is pressed against the chuck body 4 and lifted up. There is a method that allows processing to be performed without the . With this method, it is certainly possible to form an accurate gripping diameter during machining, but when the ring is removed, there will be looseness between the master jaw 2 and the dovetail groove 7.
When clamping, the workpiece gripping surface does not contact the workpiece surface accurately.

In addition, Japanese Utility Model Application Publication No. 55-60904 proposes a fixing device in which a chuck pawl is provided with a screw rod and a rotor that is screwed into the screw rod, and the chuck pawl can be moved toward and away from the chuck body by the rotor. By using this fixing device, it is possible to eliminate play between the protrusion of the master jaw and the guide groove.

However, in the above structure, since the chuck pawl is pushed up parallel to the chuck body, the chuck pawl is held in a state different from the lifted state that occurs when a work is actually gripped by the chuck pawl. Therefore, even if the workpiece gripping surface is formed to match the shape of the workpiece with the chuck claw pushed up, when the rotor is loosened and the chuck claw grips the workpiece next time, the workpiece gripping surface will not follow the shape of the workpiece. First, it has the disadvantage that highly accurate gripping cannot be achieved.

Therefore, in order to perform accurate clamping with the above-mentioned fixing device, it is necessary to hold the chuck pawl pushed up by the fixing device, but the chuck pawl is held in a lifted state by a screw rod, etc. Therefore, the strength is weak against clamping force, cutting force, etc., and the durability is low.

This invention solves the above problems and allows the workpiece gripping surface to be formed with high accuracy regardless of the play between the master jaw and the chuck body, and also does not reduce mechanical strength or durability against clamping force or cutting force. The purpose is to provide a top or soft top that does not require a top or soft top.

[Means for solving problems]

In order to solve the above problem, this invention includes a cam on at least one of the side surfaces adjacent to the workpiece gripping surface, the distance from the rotation center to the top dead center being larger than the distance from the rotation center to the top surface of the chuck. ,
The cam is attached via a rotating support shaft perpendicular to the side surface, and the cam is mounted at a position biased toward the workpiece gripping surface with respect to the center of the upper surface of the master jaw.

[Effect]

In the soft jaw constructed as described above, when the cam is rotated, the soft jaw is pushed up from the upper surface of the chuck, and the surface of the protrusion of the master jaw fixed to the soft jaw is pressed against the upper surface of the guide groove. In this case, since the cam is biased toward the work gripping surface side, only the end of the master jaw on the work gripping surface side is lifted up, and the master jaw is tilted in the length direction. Therefore, if the workpiece gripping surface is machined in this state, the shape of the workpiece gripping surface will be the same as when the workpiece was clamped, and then the cam will be loosened and a When clamping is performed after returning to the state where there is wobbling, the gripping surface follows the shape of the workpiece and makes uniform contact, allowing accurate centering.

〔Example〕

Hereinafter, an embodiment of this invention will be described based on FIGS. 1 and 2.

This embodiment is applied to the conventional soft jaw shown in FIG.
Serrations 10 are provided on the joint surfaces to prevent slipping. Also, Master Jiyo 2 is
The protrusions 2a on both sides engage with the guide grooves 7a and are slidably inserted into the dovetail grooves 7, and the racks 2b at the bottom mesh with the scroll teeth 6.

Work gripping surface 11 in the above-mentioned soft jaw 1
A cam 14 whose outer peripheral surface serves as a cam surface is rotatably attached to the side surface 12 adjacent to the workpiece gripping surface 11 by a screw shaft 15 screwed into the side surface 12 at right angles. This cam 14
is a disk-shaped flat cam, and a circular hole 14a into which the head 15a of the screw shaft 15 is fitted is formed on one side, and the head 1 is inserted into the hole 14a as shown in FIG.
When the screw shaft 15 is rotated with the screw 5a fitted, the cam 14 is rotated by the frictional force generated at the contact portion between the head 15a and the hole 14a.

The distance from the rotation center 17 of the cam 14 to the top dead center 16 is set to be greater than the distance from the rotation center 17 to the upper surface 4a of the chuck body 4. Therefore, when the screw shaft 15 is operated and the cam 14 is rotated so as to press the top dead center 16 side against the chuck upper surface 4a, the soft jaw 1 moves along the outer peripheral surface of the cam 14 and presses the chuck upper surface 4a.
pushed up from

The soft jaw 1 of this embodiment is constructed as described above, and the workpiece gripping surface 11 is machined with the soft jaw 1 being pushed up from the top surface 4a of the chuck by the cam 14 as described above. In this state, the master jaw 2 is pushed up together with the soft jaw 1, and the upper surface of the protrusion 2a is pressed against the upper surface of the guide groove 7a, as shown in FIG. becomes the state of

Therefore, if the workpiece gripping surface 11 is machined to match the shape of the workpiece in this state, the gripping surface 11 will be formed to exactly fit the shape of the workpiece in the same state as the clamp. For this reason, next
When the cam 14 is returned to its original position and clamping is performed with the master jaw 2 and the dovetail groove 7 having some play, the gripping surface 11 follows the shape of the workpiece and comes into uniform contact with the surface, resulting in a stable gripping surface 11. Gripping and high concentric accuracy can be obtained.

In addition, in the case of hydraulic chucks, air chucks, etc., the master yaw 3 may not be raised sufficiently to the locking position simply by rotating the cam 14, so in such cases, first grasp the work or a jig to replace it, and then It is preferable to tighten the cam 14 after the master yaw has been lifted up.

The cam 14, which has been loosened from the restrained position and is now in a free state, remains stable and oriented in one direction due to centrifugal force even if the chuck body 4 is rotated after clamping the workpiece, so it cannot be tightened again. There is no need to repair or fix it in any way.

Further, the cam 14 may also be provided on both side surfaces 12 and 13 adjacent to the gripping surface 11.

〔effect〕

As described above, this invention provides a cam biased towards the workpiece gripping surface on the top or soft jaw,
This cam allows the master jaw to be tilted and pushed up in the same way as when clamping a workpiece.
The shape of the workpiece gripping surface can be precisely formed to match the shape of the workpiece in the same state as when clamping the workpiece, and even if the chuck body is old and has wobbles, it can grip the workpiece stably and with high accuracy. It is possible to obtain centering accuracy.

In addition, the workpiece is clamped by disengaging the cam, releasing the push-up of the jaw, and then engaging the master jaw with the guide groove of the chuck body in the same way as before, so there is no reduction in strength and the workpiece can be clamped just like a normal chuck. You can get the same durability.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an example of the soft jyo according to this invention attached to the upper surface of the master jyo, Fig. 2 is a cross-sectional view of the same, Fig. 3 is a transverse cross-sectional view of the conventional example, and Fig. 4 is 1 is a partially sectional view of a known scroll chuck; FIG. 1... Soft Jiyo, 2... Master Jiyo, 2
a...Protrusion, 3...Claw, 4...Chuck body, 7
...Dovetail groove, 7a...Guide groove, 14...Cam, 15
...Screw shaft.

Claims (1)

[Scope of utility model registration request] On at least one of the side surfaces adjacent to the workpiece gripping surface of the top of the chuck claw fixed to the master jaw or the soft jaw, the distance from the center of rotation to the top dead center is from the center of rotation to the top surface of the chuck. A cam larger than the distance of is installed via a rotating support shaft perpendicular to the side surface, and the cam's installation position is biased toward the workpiece gripping surface with respect to the center of the upper surface of the master jaw. A nail top or soft jaw for a nail chuck characterized by: