US2359689A - Locking fixture - Google Patents

Description

Patented Oct. 3, 1944 UNITED STATES PATENT oEFicE LOCKING FDTURE Guy, E. Swartz, Detroit, Mich. Application October 6, 1941, Serial No. 413,857

4 Claims.

The present invention relates to locking fixtures for use in production of machine parts, for example, in xing parts to be subjected to multiple drilling or other operations.

In the use of such fixtures for so-called heavy duty operations, where the part being worked is large and requires large clamping means, it has been found that the quite heavy movable member of the clamp is difficult to move up and down and consequently subjects the operator and the operating parts to undue strains.

It is among the objects of the present invention to provide means for overcoming such diiiiculties by the use of weight compensation means acting on the heavy clamp element.

Another object is a weight compensation means which may be adjusted both for tension and for considerable variation in the dimension of the part to be clamped.

Other objects and advantages will readily occur to those skilled in the art upon reference to the following description and the accompanying drawing in which Figure 1 is a perspective View of a locking iixture embodying the invention.

Figure 2 is a longitudinal central vertical sectiona1 view of the base portion.

Figure 3 is a section on line 3 3 of Figure 2.

As indicated in the drawing, a xture embodying the present invention may consist of a base Il) having at each end guide sleeves II through which and into the base extend vertically slidable rack members I2 fixed at their upper ends to a clamping plate I3.

Extending longitudinally through the base l is a shaft I4, mounted in suitable bearings in the end walls, and provided with teeth at the portions adjacent racks I2 for engaging the teeth of the latter, so that rotation of shaft I4 provides up and down motion of plate I3.

Rotation of the shaft I4 is accomplished by means of a lever I5 acting through self-locking means indicated as a whole at I6, the detailed construction of which is not being shown, but which provides for turning the shaft and locking it automatically against reverse motion.

Since as stated above, the members I2 and I3 in heavy duty fixtures are quite heavy, a weight compensation means is shown as included in the structure. This compensator is shown as a heavy helical spring 20, xed at one end 2I to shaft I4, and at its other end secured to a sleeve 22 rotatably mounted on shaft I4.

This sleeve 22 is provided on its outer surface with worm teeth 23 adapted to coact with a Worin 24 formed on a shaft 25 mounted in suitable bearings in the back and front walls of the base I Il, and extending through the latter to the outside, the projecting end being squared or otherwise shaped as at 26 to permit application of a suitable handle (not shown) In mounting the shaft 25, it is preferred to provide its forward bearing in a bushing 21 fixed in the front wall of the base as by a screw 28.

In operation, the fixture is adjusted so that the plate I3 is at approximately the proper height for the work part to be operated, the tension of spring 20 is then adjusted to counterpoise the Weight of the vertically movable parts. Under such an adjustment, operation of the hand lever I5 provides a smooth easy action even in the largest and heaviest iixtures. The locking means I6 may be of any suitable form, but is preferably such as is shown in my previous U. Si. Patent No. 2,171,458, issued August 29, 1939or No. 2,066,167, issued December 29, 1936.

Now having described the invention and the preferred embodiment thereof, it is to be understood that said invention is to be limited, not to the specific details herein set forth, but only by the scope of the claims which follow.

I claim:

1. A locking fixture including a base, a clamping plate located above said base, rack members fixed to said plate and extending into said base, a shaft rotatably mounted in said base and provided with pinions coacting with said rack members to move ysaid plate, means for rotating and for locking said shaft in position, and means for counterbalancing the weight of said plate and racks.

2. A locking iixture including a base, a clamping plate located above said base, rack members fixed to said plate and extending into said base, a shaft rotatably mounted in said base and Tprovided with pinions coacting with said rack members to move said plate, means for rotating and for locking said shaft in position, and spring means adapted to act upon said shaft to provide a resilient resistance to its rotation toward clamping position.

3. A locking fixture including a base, a clamping plate located above said base, rack members Xed to said plate and extending into said base, a shaft rotatably mounted in said base and provided with pinions coacting withr said rack members to move said plate, means for rotating and for locking said shaft in position, and means for counterbalancing the weight of said plate and racks, said latter means consisting of a spring xed to said coacting with said shaft for counterbalancing the 10 Weight of said plate and racks, means for xing one end of said spring to said shaft, and means for fixing the other end of said spring to said base and adjusting the tension thereof, said latter means consisting of a sleeve rotatable upon said shaft and provided with worm gear teeth and a Worm shaft mounted in said base and coacting With said Worm gear on said sleeve.

GUY E. SWARTZ.

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