Power Operated Rotatable Clamping Assembly

1. Technical Field

The present invention broadly relates to clamping devices and deals more particularly with a power operated clamping device which may be rotated to allow clamping in any of a plurality of rotational positions.

2. Background Art

Various types of clamping devices are used in manufacturing operations to securely hold parts or the like during machine operations. There is an increasing need for clamping devices which are versatile and readily adaptable for use in clamping various types of parts in numerous positions. For example, in the past, where a change was made in the geometry of the part to be clamped, it was often necessary to physically relocate the clamping device; this often required unbolting the clamping device and securing it in a new position relative to the part. Such a procedure is obviously costly because of the labor required to relocate the clamping device as well as in terms of the down time of manufacturing operations.

In many applications, clamping devices of the type described above are operated by a fluid driven piston and cylinder assembly. For reasons of safety, mechanical means must be provided for locking the clamp in a clamping position in the event that fluid pressure is lost from the cylinder. This mechanical requirement obviously increases the mechanical complexity of the clamping device and may be feasible where the device must be sufficiently versatile to allow clamping of the part in a variety of positions.

Accordingly, it is a primary object of the present invention to provide a power operated clamping assembly which allows clamping a part in a variety of positions. As a corollary to the foregoing object, it is a further object to provide a clamping assembly having a clamping member which may be rotated to any of a plurality of clamping positions.

A still further object of the present invention is to provide a clamping assembly as described above which is particularly simple in construction and quite reliable.

Another object of the invention is to provide a clamping assembly as described above which includes a mechanical locking feature for locking a clamping member in a locked, clamping position in the event of a failure of a fluid operated motor which normally operates the clamping member.

These, and further objects of the invention, will be made clear or will become apparent during the course of the following description of a preferred embodiment of the present invention.

According to the present invention, a clamping assembly is operated by a piston and cylinder assembly rotatably mounted on a support. A mounting bracket rotatably mounted on the support is provided with a pair of pivotally mounted plates each having a clamping arm and a cam track. The mounting bracket includes an annular shoulder engaging the support; a flange draws the shoulder against the support, thereby selectively locking the bracket and piston/cylinder against rotation in any of a plurality of rotational positions. A drive rod connected to the piston extends through the support and into an elongate slot in the bracket. A pair of rollers secured to the outer end of the rod are disposed in the cam slots and drive the plates to pivot. The cam slots are specially configured to lock the clamp in a locking position in the event that fluid pressure is lost in the piston.

In the drawings, which form an integral part of the specification and are to be read in conjunction therewith, and in which like reference numerals are employed to designate identical components in the various views:

FIG. 1 is a perspective view of the power operated, rotatable clamping assembly of the present invention, the clamping position of the clamping arm being shown in the phantom;

FIG. 2 is a sectional view taken along the line 2--2 of FIG. 1;

FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2;

FIG. 4 is a perspective, exploded view of the clamping assembly shown in FIG. 1; and,

FIGS. 5a-5d are diagrammatic views of the camming mechanism showing its progressive operation from an unclamped position to a clamped position.

Referring first to FIGS. 1-4, the present invention is broadly concerned with a power operated, rotatable clamping assembly generally indicated by the numeral 10. Clamping assembly 10 broadly includes a fluid operated, piston and cylinder assembly 15 and a clamping mechanism 13 mounted on a support 12.

Support 12 includes a flat base 16 adapted to be mounted on any suitable structure adjacent the part to be clamped and an upstanding bracket 14 having a counterbored hole 18 therethrough.

The piston and cylinder assembly 15 includes a cylinder 60 closed at the opposite ends thereof by end caps 62 and 64 which are respectively provided with fluid ports 68 and 66. A piston 58 is reciprocably confined within the cylinder 60 and has secured thereto a piston rod 56 which extends forwardly through end cap 62 and seal 67 through the hole 18 in support 12. The piston and cylinder assembly 15 is mounted for rotation on bracket 14 by means which will later be discussed.

The clamping mechanism 13 broadly includes bracket 24, locking flange 20 and clamping plates 32. Bracket 24 is cylindrical in shape on one end 33 and is provided with an annular shoulder 28 which is rotatably received within the counterbore of hole 18. Flange 20 includes first and second interlocking portions 20a and 20b which are secured to one face of the bracket 14 by a cap screw 22. The inner face of flange portions 20a and 20b slideably engage shoulder 28. The cylindrical end 33 of bracket 24 is therefore rotatable within the counterbore of hole 18 until the flange 20 is tightened with screws 22, thereby locking the bracket 24 in any of a plurality of rotational positions.

Bracket 24 includes an aperture 30 in the end thereof through which the outer end of piston rod 56 extends. A longitudinally extending slot 26 in bracket 24 is aligned with aperture 30 and defines slot like openings on opposite sides of bracket 24. A mounting block 50 is slideably confined within slot 26 and is adjustably threadably secured to the end of rod 56 by means of a threaded coupling 57. Adjustment of the threaded coupling 57 varies the longitudinal position of block 50 relative to rod 56. A shaft 52 extends transversely through block 50 and has mounted on opposite ends thereof rollers 54. Rollers 54 are therefore respectively positioned outboard of the slot 26, on opposite lateral sides of bracket 24.

Clamping plates 32 each comprise an enlarged base 38 and an elongate clamping arm 36, the outer extremities of clamping arms 36 being secured together as by welding through a connecting block 34. Apertures 42 and a bolt 44 pivotally mount plates 32 on opposite sides of bracket 24. Plates 32 further include cam slot openings 70 in the respective bases 38, within which there is received the corresponding rollers 54.

Cam slot openings 70 are of unique configuration and are respectively defined by first and second, opposing cam surfaces. One of the cam surfaces 72 is substantially continuously arcuate, the opposing cam surface being defined by a pair of arcuately shaped cam surface portions 74 and 76 connected by a shoulder-like cusp 78.

From the foregoing it may be appreciated that the clamping mechanism 13 is mounted for rotation on the support 12 by means of the flange 20 which captures the cylindrical end of bracket 24 within the counterbore of hole 18. End cap 62 of the piston and cylinder assembly 15 is drawn against one face of support 14 by pressure applied through adjustment of coupling 57. Thus, piston and cylinder assembly 15 rotate along with the clamping mechanism 13 when flange 20 is loosened such that the cylindrical end 33 of bracket 24 is allowed to rotate within the support 12.

Referring now also to FIGS. 5a-5c, in operation, with the piston 58 retracted as shown in FIGS. 1, 2 and 5a, rollers 54 are disposed within the upper portion of the cam slots 70 and clamping plates 32 are in an unclamped position. It will be understood that any suitable clamping pad, device etc. may be secured to the outer ends of clamping arms 36 to actually contact and thereby clamp the part. In order to shift the clamping plates 32 to a clamping position, fluid is introduced under pressure through inlet port 66 into the cylinder 60 thereby extending piston rod 56. Upon extension of rod 56, rollers 54 bear against cam surface portion 74 causing the clamping plates 32 to pivot about bolt 44. As the rod 56 continues to be displaced outwardly, rollers 54 ride over the cusp 78 down into the cam surface portion 76 at which time the rollers 54 commence exerting force against surface portion 76 and cusp 78. Continued outward displacement of rod 56 causes rollers 54 to return back over the cusp 78 and into surface portion 74 where the clamping arms 36 are fully displaced to their clamping position. At this point, in the event that fluid pressure is lost within the cylinder 60 the clamping plates 32 remain in their locked, clamped position by virtue of the fact that the cusps 78 engage rollers 54 and thus prevent return pivotal movement of clamping plates 32 until such time as rod 56 is retracted sufficiently to allow rollers 54 to clear cusps 78.

Clamping plates 32 are returned to their starting position by allowing fluid to exit through ports 66 and introducing fluid under pressure through ports 68 into the cylinder 60. This causes the rod 56 to retract. Upon retraction of rod 56, rollers 54 bear against cam surface 72 and roll clear of cusp 78, thus causing plates 32 to rotate counterclockwise as viewed in FIGS. 5a-5d.

The rotational position of the clamping arms 36 may be conveniently altered simply by loosening screws 22 and turning the entire clamping mechanism 13 until the desired rotational position is reached whereupon screws 22 are retightened thereby locking the clamping mechanism in place.

From the foregoing, it is apparent that the clamping assembly described above not only provides for the reliable accomplishment of the objects of the invention but does so in a particularly economical and efficient manner. It is recognized, of course, that those skilled in the art may make various modifications or additions to the preferred embodiment choosen to illustrate the invention without departing from the spirit and scope of the present contribution to the art. Accordingly, it is to be understood that the protection sought and to be afforded hereby should be deemed to extend to the subject matter claimed and all equivalents thereof fairly within the scope of the invention.