US1805443A - Clamping device - Google Patents

Description

May 12, 1931. v. E. WALTERS ET AL CLAMPING DEVICE Filed May 12. 1928 2 Sheets-Sheet 1 y 1931- v. E; WALTERS ET AL ,443

CLAMPING DEVICE Filed May 12. 1928 2 Sheets-Sheet 2 Patented May 12, 1931' UNITED STATES PATENT OFFICE "VERNON E. WALTERS, OF DETROIT, AND IRVING GRANT, OF GROSSE POINTE PARK, MICHIGAN, ASSIGNORS TO GENERAL MOTORS CORPORATION, OF DETROIT, IICHIGAN,

A CORPORATION OF DELAWARE CLAMI'ING DEVICE Application filed Kay 12, 1928. Serial No. 277,285.

This invention relates to a clamping device used for holding an article while some machining operation such as drilling, grinding, milling, etc. is being performed.

In factories where machine work is done on a large production basis, it is desirable to have a simple clamping device into which the work to be held may be quickly inserted or withdrawn from. The clamping or unclamping action must be obtained by a single movement of. the operating lever, and t e work must be positively held so that it is not permitted to move while the machining operation is being performed. v

There are a number of clamping fixtures available in which the clamping action is produced by a compression spring. These, however, are not satisfactory due to the fact that the article being worked on is not positively held as the resiliency of the spring sometimes permits a certain amount of movement of the article while it is being-machined, thus resulting in inaccuracies.

An object of this invention is to prov de such a device in which the clamping actlon is obtained by means of cam-shaped surfaces which engage each other to produce a wedging action. This wedging action also serves to hold the fixture in clamping position. To

further insure that the fixture will be positively held in clamping position a compression spring is provided which cooperates with the cam-shaped surfaces to assist in producing the locking action.

Other objects and advantages will be apparent upon referring to the specification and accompanying drawings in which Figure 1 is a vertical section through our improved clamping device.

Figure 2 is a section taken on the line 22 of Figure 1.

Figure 3 is a plan view of the device with parts broken away. a

Figure 4 is a detailed perspective view of one of the parts.

Figure 5 is a detailed perspective view of another of the parts.

Figure 6 is a section taken onthe line 6-6 of Figure 2. p

Figure 7 is a section taken on the line7-7 of Figure 1.

Figure 8 is a developed view of a spiral groove'in one of the parts.

Figure 9 is a section taken on the line 9-9 of Figure 1.

The reference number 10 indicates a base or fixed member having a vertical passage 12, in which is mounted a sleeve 14. On the outsideof this sleeve, teeth 16 are milled across one side as shown in Figure 7. Supported on a shaft 18, which is journaled in the base, is a pinion 20, which is held to the shaft by a key 22. The pinion 20 has teeth 24 formed on it, which mesh with the teeth 16, and prevent the sleeve 14 from rotating within the passage 12. A handle 26 is secured in the shaft 18, and the latter is held in place in the base by means of a pin 28.

Mounted in the sleeve 14 is a vertical shaft 30, which is eccentrically located in the sleeve in order that the teeth 16 may be cut in the latter without weakening it.- The shaft 30 has formed in it a spiral groove 32, which is provided with an offset or shoulder portion 34 at its upper end as shown in Figure 8. A set screw or pin 36, which is secured in' the sleeve 14, has a reduced end portion which fits into the groove 32, and when the device is in imclamped position, this end portion is held at the upper end of the groove by being held behind the shoulder 34, so that the sleeve 14 and the shaft 30 will move up or down as a unit and in order that the shaft 30 may not rotate within the sleeve 14.

Secured against a shoulder 37 at the -upper end of the shaft 30 is a collar 38. A thrust bearing 40 isheld in the collar by means of a cap 42, which is retained by the nuts 44. The shaft 30 is free to turn within the collar 38, and the function of the bearing 40 is to take the thrust loaddeveloped by the clamping action to be described later. A support 46 is mounted upon the outside of the collar 38, and has secured to it by means of guides 47 and nuts 49, an upper clamping member or movable member 48. The guides 47 extend down into passages 51 in the base 10, and

. serve to hold the movable member 48 in proper relation to the base, as well as to prevent rotation of the movable member 48.

Y larger than that shown, the support 46, to-

gether with the movable member 48 may be moved upward relative to the collar 38, by loosening the hollow-headed screw 58,- which releases a sleeve 60 which is normally drawn a ainst the collar 38 as shown in Figure 6. Vllhen the sleeve 60 is in released position, the support 46 may be freely moved up or down with respect to the collar 38, to correspond with the size of the work which it is desired to clamp.

Secured in the bottom of the base 10 is a ring member 62 which is held in place by screws 64 which are threaded into the base and which fit into grooves 66 in the ring member to prevent rotation of the latter. This ring member has formed on it cam or inclined surfaces 68, as shown in Figure 5. The lower end of the shaft has formed on it extensions 70 and, 72, the upper sides of which are shaped to form cam or inclined surfaces 74, as shown in Figure 4. When the fixture is in unclamped position, the extensions 70 and 72 are held in such position by the pin 36 fitting into the shoulder 34 in the spiral roove, that these extensions may pass throng slots 76 in the ring member 62. Secured in the bottom of the base 10, as best shown in Figure 9, is a pin or set-screw 78, which has a portion of its inner end cut away to provide an angular face 80. Surrounding the shaft 30, and held by the sleeve 14 and the collar 38, is a compression spring 82.

The operation of the device isas follows: The operator places the work which is to be machined, such as the connecting-rod 50, in the work-supporting member 52, and turns the handle 26 in a counter-clockwise direction as viewed in Figure 1, thereby rotating the pinion 20, causing the sleeve 14 and the shaft 0 to be moved downwardly.

- The extensions 70 and 72 at the lower end of the shaft 30 pass-through the slots 76, and continue in their downward movement until a chamfered portion 71 on the extension 70 strikes the angular face of the set-screw 78. This, of course, tends to cause the shaft 30 to rotate in a clockwise direction as viewed in Figure 9. This rotation of the shaft 30 causes the pin 36 to be disengaged from the shoulder 34 in the spiral groove 32. The shaft 30 is-novyfree to rotate and move axially-with respect to'the sleeve 14. The compression spring 82 tends to force the sleeve 14 downwardly, and due to the action on the pin 36 working in the spiral groove 32, the shaft 30 is caused to rotate 1n such direction as will cause the inclined surfaces 74 to become wedged against the inclined surfaces 68. At this time, of course, the movable member 48 has been brought down to a position whereby the connecting-rod is clamped tightly between the work- sup orting members 52 and 54. The angle of the inclined surfaces 68 and 74 is so chosen that the proper clamping action is obtained without any possibility of the parts becoming so wedged together that they may not be readily released by taming the shaft 30 in the opposite direction, and so that a comparatively large range of clamping movement is provided. It is not necessary that the surfaces 74 be moved to any particular position with respect to the surfaces 68. The clamping action will be obtained any time that the inclined surfaces 74 engage any part of the inclined surfaces 68. Therefore, the range of clamping action for any setting of the movable member with respect to the collar 38 will be substantially equal to the height of the inclined surfaces 68. This permits the device to be used for clamping work which is apt to vary considerably in size, without changing the setting of the clamping device, and at the same time securing .the same clamping pressure with each piece of work.

When it is desired to unclamp the device, the handle 26 is moved in the opposite direction, thereby pulling up the sleeve 14. Due to the action of the pin 36 in the spiral groove 32, the shaft30 is rapidly rotated in a direction which will disengage the inclined surfaces 74 from the surfaces 68. Just as the shaft 32 reaches its normal position, chamfered portions 84 on the inclined surfaces 74 come into contact with similar chamfered portions 86 formed on the inclined surfaces 68, for the purpose of forcing the pin 36 into position behind the shoulder 34 in the spiral groove 32, so that the shaft 30 will a ain be locked in position in the sleeve 14.

ontinued movement of the handle 26 then causes the sleeve 14, shaft 30 and movable member 48 to be moved to their uppermost ositionso that the work may be removed.

e arts are held inthis position by the weig t of the handle 26, which is so designed that due to the ratio of the gears, it more than offsets the weight of the movable member 48 and associated parts.

It will be readily seen that the clamping action is obtained through the wedging tendency of the inclined surfaces 68 and 74 upon each other, and that the only function of the spring 82 is to aid in holding the incline surfaces in clamping position, so that they may not work loose due to vibration.

Thus there is no possibility of the clamping device accidentally loosening while the work is being machined, thereby resulting in indrill press or other machine on which it is being used, that the clamping action will be automatically obtained w brought into operating position, and the unclamping action will be obtained by turning the controlling mechanism to the shuttingoif position.

It is thought from the foregoing, taken in connection with the accompanying drawings, that the construction and operation of the device will be apparent to those skilled in the art, and that various changes in size, shape and pro ortion, and details of construction may e made without departing from the spirit and scope. of the appended claims.

We claim:

1. A clamping device comprising, in combination, a fixed member, a movable member, an axially movable sleeve carried in said fixed member, a shaft connected to said movable member and rotatably and axially movable in said sleeve, inclined surfaces on said fixedmember, inclined surfaces on .said shaft, means to move said sleeve, shaft and movable member toward said fixed member, and connecting means between said shaft and sleeve so constructed that axial movement of the sleeve causes rotary and axial movement of said shaft in said sleeve to cause said inclined surfaces to become engaged for the purpose of producing a clampin action between said fixed and movable mem ers.

2. A clamping device comprising, in com-.

bination, a fixed member, a movable member, an axially movable and non-rotatable sleeve carried in said fixed member, a shaft connected to said movable member and rotatably and axially movable in said sleeve, means to lock said shaft in said sleeve when the device is in lmclamping position, inclined surfaces on said fixed member, inclined surfaces on said shaft, means to move said sleeve shaft and movable member toward said fixed member, means to unlock said shaft from said sleeve when said shaft is in substantiallyits lowermost position, and means to rotate said shaft in said sleeve to cause said inclined surfaces to become engaged for the purpose of roducing a clampin action between said ed and movable mem rs.

Isleeve at the beginning en the machine is -to produce a clamping action 3. The combination as defined in claim 2, and means to again lock said shaft in said of the movement which will return the device to unclamping position.

4. A clamping device comprising, in combination, a fixed member, a movable member, a shaft connected to said movable member, a sleeve axially movable but non-rotatable in said fixed member, said shaft being axially and rotatably movable in said sleeve, means to move said sleeve and shaft toward said fixed member, inclined surfaces on both said shaft and said fixed member, means to rotate a said shaft in said sleeve at substantially the lowermost point of travel of said shaft so that said inclined surfaces enga e each other between said fixed and movable members, and spring means operative only when the parts are in clamping position to tend to rotate said shaft for the purpose of causing said inclined surfaces to become more tightly engaged.

5. A clam ing device comprising, in combination, a fixed member, a movable member, an axially movable sleeve carried in said fixed member, teeth formed in said sleeve, a pinion meshing with said teeth and serving to prevent rotation of said sleeve, a shaft connected to saidmovable member and r0- tatably and axially movable in said sleeve, a spiral groove havinga shoulder at its upper end formed in said shaft, a pin secured in said sleeve, the end of said pin fitting into said groove and being normally held by said shoulder, a compression spring between said movable member and said sleeve, inclined surfaces on said fixed member, inclined surfaces on said shaft, and a deflecting member held in said fixed member and adapted to release said pin from said shoulder and to rotate said shaft when said sleeve is moved to substantially its lowermost position by said pinion so that said inclined surfaces will engage each other to produce a clamping action between saidfixed and movable member, said spring serving to assist in holding said inclined surfaces in clamping position through the action of said pin and said spiral groove.

In testimony whereof we afiix our signatures- VERNON E. WALTERS. IRVING GRANT.

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