Patent Application
20070075472
The present invention relates generally to a clamp and, more particularly, to a fluid powered, sealed pin locating and clamping apparatus.
Powered clamps have been commonly used to secure workpieces, such as sheet metal automotive body panels, polymeric parts and the like in checking fixtures, gauging stations, welding stations, punching stations and other locations within a manufacturing environment. Many existing clamps are powered by hydraulic or pneumatic fluid pressure. For example, reference should be made to the following U.S. patents, which have been invented by Sawdon: U.S. Pat. No. 6,502,880 entitled “Pin Part Locator” which issued on Jan. 7, 2003; U.S. Pat. No. 6,378,855 entitled “Locking Pin Clamp” which issued on Apr. 30, 2002; U.S. Pat. No. 5,190,330entitled “Powered Clamp with Parallel Jaws” which issued on Mar. 2, 1993 and U.S. Pat. No. 6,902,159 entitled “Sealed Pin Locating and Clamping Apparatus” which issued on Jun. 7, 2005; all of which are incorporated by reference herein.
Many of the previously known locating pin clamps include a mechanism which drives a finger or arm which extends outwardly from the pin and pulls down against the workpiece to hold the workpiece in place while operations such as welding and/or clinching take place. Additionally, some locating pin clamps include an aperture in the locating pin to allow the finger to extend and retract from the pin during operation. This aperture provides a path for contamination to enter into the mechanism. Because locating pin clamps are often used in harsh environments, locating pin clamp reliability may be a concern.
Furthermore, some of the known locating pin clamps release the workpiece if there is a loss of fluid pressure during clamp operation. It is desirable to prevent the clamping arm from opening and releasing the workpiece if a loss of fluid pressure were to occur. Prior constructions employing such a feature are disclosed in U.S. Pat. No. 5,871,250 entitled “Sealed Straight Line Gripper” which issued to Sawdon on Feb. 16, 1999 and U.S. Pat. No. 5,853,211 entitled “Universal Gripper” which issued to Sawdon et al. on Dec. 29, 1998. These patents are also incorporated by reference herein.
In accordance with the present invention, a clamp includes a body, a lead pin moveable relative to the body and an actuator supported by the body. The actuator is axially moveable between an extended position and a retracted position. The actuator includes a camshaft drivingly coupled to the lead pin. Axial movement of the camshaft causes the lead pin to rotate between a first positioned aligned with a first longitudinal axis and a second position aligned with a second longitudinal axis laterally offset from the first longitudinal axis.
As another feature of the present invention, the clamp includes a body, an actuator moveably supported by the body, and a clamping member drivingly coupled to the actuator. The actuator includes a pair of rollers, each roller being positioned within one of two grooves formed on an axially and rotatably moveable camshaft. Each groove includes a plurality of detents. The clamping member axially translates and rotates between an extended position and retracted position in response to movement of the actuator. The rollers are positionable in engagement with the detents to restrict movement of the clamping member in the absence of force being provided by the actuator.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Referring to
Clamp body 16 is substantially rectangularly-shaped having a machined NAAMS hole pattern on one or more sides. Body 16 includes a piston cavity 22 formed at the end nearest front end cap 18. Cavity 22 has a longitudinal axis 24. A camshaft bore 26 is in communication with piston cavity 22 and extends through the opposite end of body 16. Camshaft bore 26 extends along axis 14. Axis 14 is substantially parallel to and laterally offset from axis 24. Front end cap 18 is coupled to body 16 via a plurality of threaded fasteners 30.
Body 16 includes a port 32 in fluid communication with piston cavity 22. Front end cap 18 includes a port 34 also in fluid communication with piston cavity 22. A piston 36 is slidably positioned within piston cavity 22. A pair of seals 38 sealingly engage the sidewalls of piston cavity 22 so that piston 36 translates in reaction to pressurized fluid entering and/or exiting ports 32 and 34. A pin 40 is coupled to piston 36 and longitudinally extends from a rear face 42 of piston 36. Pin 40 is slidably positioned within a blind aperture 44 longitudinally extending through a portion of body 16. Pin 40 and aperture 44 function to restrict piston 36 from rotating during operation.
A bore 46 longitudinally extends through front end cap 18 along axis 24. Piston 36 includes a body portion 48 having an enlarged diameter slidably positioned within piston cavity 22 and a necked portion 50 having a reduced diameter at least partially extending through bore 46 of front end cap 18. The distal end of necked portion 50 includes a recess 52. Lower pin 13 extends through an aperture 58 in part rest 15. Lower pin 13 is operable to translate along axis 24. A dog 54 is formed on lower pin 13 and engages recess 52. The interconnection of dog 54 and recess 52 assures that lower pin 13 does not rotate relative to piston 36. An offset bore 60 longitudinally extends through lower pin 13 along axis 14. A seal 62 is positioned within a groove 64 formed within part rest 15 to sealingly engage an outer diameter of lower pin 13. Another seal 66 is positioned within a groove 67 formed in front end cap 18.
Lead pin or head 12 is positioned adjacent to lower pin 13. Lead pin 12 includes an outer surface having a tapered portion 68 and a cylindrical portion 69. Lead pin 12 includes a planar end face or clamping surface 70. Lead pin 12 is operable to rotate about axis 14 such that clamping surface 70 translates relative to an end surface 72 formed on lower pin 13. Lead pin 12 is rotatable through approximately 135 degrees about eccentric axis 14. In this manner, lead pin 12 may be positioned such that outer cylindrical portion 69 is aligned with the outer cylindrical surface of lower pin 13. Because lead pin 12 rotates about eccentric axis 14, the outer cylindrical portion 69 of lead pin 12 may be laterally offset from being in alignment with axis 24 and/or the outer surface of lower pin 13 such that clamping surface 70 overhangs lower pin 13 to engage a portion of workpiece 10.
A tie rod 74 is affixed to lead pin 12 via a roll pin 76. Tie rod 74 extends through lower pin 13 and piston 36 to mount to a camshaft 78. Tie rod 74 is coupled to camshaft 78 via a roll pin 80. A seal 83 engages tie rod 74 and camshaft 78.
Camshaft 78 is a substantially elongated cylindrical member rotatably positioned within bore 26. A seal 79 sealingly engages bore 26. Camshaft 78 includes a reduced diameter nose portion 81 moveably positioned within a pocket 82 formed in body portion 48 of piston 36. A spring 84 is positioned within pocket 82 to provide a separating force between piston 36 and camshaft 78. A seal 85 is positioned between nose portion 81 and piston 36.
A cam housing 86 is coupled to body 16 to rotatably support camshaft 78. A pair of cam slots 88 are formed on an external surface of camshaft 78. Cam rollers 90 are rotatably supported on pins 92 extending from cam housing 86. Because cam housing 86, pins 92 and rollers 90 are longitudinally fixed, axial movement of camshaft 78 causes it to rotate along axis 14 due to the shape of cam slots 88. Lead pin 12 axially translates and rotates between an extended position and retracted position in response to movement of camshaft 78. Furthermore, a plurality of detents 93 are formed near the end each cam slot 88. Cam rollers 90 are positionable in engagement with detents 93 to restrict movement of lead pin 12 in the absence of force being provided by piston 36. A loss of force may occur during an interruption of pressurized fluid supply. Cam rollers 90 are positioned within detents 93 when the lead pin 12 is in the retracted position. Accordingly, workpiece 10 will remain clamped against part rest 15 during a loss of pressurized fluid supply.
Cam housing 86 also includes provisions for mounting and aligning a proximity switch package 94. To assure that the features or provisions incorporated in cam housing 86 are properly aligned relative to body 16, a roll pin 96 interconnects cam housing 86 and body 16 at a specific angular orientation. Cam housing 86 includes a first sensor aperture 98 and a second sensor aperture 100 laterally extending therethrough. Sensor package 94 includes a first sensor head 102 positioned within first sensor aperture 98 and a second sensor head 104 positioned within second sensor aperture 100. First sensor head 102 and second sensor head 104 are mounted to a switch plate 106.
Rear end cap 17 includes a cylindrical bore 110 extending therethrough. A first portion 112 of the cylindrical bore is in receipt of cam housing 86. A reduced diameter portion 114 is in receipt of a portion of camshaft 78. A threaded portion of a bore 116 is in receipt of a plug 118. A plurality of fasteners 119 extend through rear end cap 17 and cam housing 86 to threadingly engage body 16. Rear end cap 17 includes a laterally extending aperture 120 substantially aligned with the sensor apertures 98 and 100 extending through cam housing 86. First sensor head 102 and second sensor head 104 extend through aperture 120 as well as apertures 98 and 100, respectively. Switch plate 106 is mounted to rear end cap 17 via a fastener 121. Switch plate 106 sealingly closes aperture 120 and supports sensor heads 102 and 104. Sensor heads 102 and 104 are longitudinally spaced apart from one another and are operable to detect if a portion of camshaft 78 is within close proximity to one of the sensor heads.
To assist a user in determining the axial and rotational position of lead pin or head 12, camshaft 78 includes a first lobe 122 and a second lobe 124. First lobe 122 is shaped and longitudinally positioned to cause sensor head 102 to output a signal indicative of the presence of lobe 122 when piston 36 is in the fully retracted position and lead pin 12 is in its retracted and eccentrically offset position as shown in
Camshaft 78 includes an internally threaded blind aperture 126 substantially aligned with internally threaded portion 116 of bore 110. By removing plug 118 from rear end cap 17, access to internally threaded blind aperture 126 is provided. A hand tool (not shown) may be inserted through bore 116 and threadingly engaged with camshaft 78 through threaded aperture 126. Manual rotation of camshaft 78 allows a user to manually operate the actuator mechanism. During manual or powered operation it may be desirable to fine tune the position of lead pin 12 relative to axis 24 at the fully extended position of piston 36. In this manner, an end user may assure that cylindrical portion 69 of lead pin 12 is aligned with the outer surface or lower pin 13 at a particular point in operation. An adjustable stop 130 is threadingly engaged with cam housing 86 as shown in
As best shown in
It should be appreciated that lead pin 12, lower pin 13 and part rest 15 define a pin assembly of a certain size. Specifically, outer cylindrical portion 69 of lead pin 12 is sized to protrude through a like sized aperture in a workpiece. However, different workpieces may have differently sized apertures. Accordingly, a family of pin assemblies may exist to allow a user to easily modify pin clamp 8 for use in clamping workpieces having differently sized apertures. It is contemplated that lead pin 12 has an outer diameter of 12 mm while the members of the family of pin assemblies may have pin sizes ranging from 6 mm to 40 plus mm in diameter. The ranges previously described are merely exemplary and it should be appreciated that the pin clamp may be constructed to have lead pins of various sizes.
Clamp 400 includes a one-piece body 402 slidably housing camshaft 78 and piston 36. Housing 402 performs the functions previously performed by rear end cap 17, cam housing 86 and body 16 of clamp 8. A front end cap 404 encloses a bore 406 formed in body 402. Front end cap 404 is substantially similar to front end cap 18 except that front end cap 404 is sealed to body 402 using a face seal 408. Front end cap 404 is coupled to body 402 via fasteners 30. Pin clamp 400 utilizes piston 36 having a slight modification from its use within pin clamp 8. Specifically, a pair of roll pins 410 interconnect necked portion 50 with lower pin 13 to assure that piston 36 does not rotate relative to lower pin 13. Alternatively, the recess and dog interconnection previously described may be used with pin clamp 400.
Roller assemblies 412 extend through counterbores 414 formed in body 402 to engage cam slots 88 on camshaft 78. Each roller assembly 412 includes a stanchion 416, a seal 418, a roller 420 and a retaining screw 422. Stanchion 416 includes a head portion 424, a guide portion 426 and a spindle portion 428.
As best shown in
Body 402 includes a first sensor bore 444 in receipt of first sensor head 102 and a second sensor bore 446 in receipt of second sensor head 104. A pocket 448 accepts switch plate 106. Sensor package 94 functions as previously described in relation to pin clamp 8.
One skilled in the art should appreciate that pin clamp 400 may also be configured to utilize the alternate embodiment pin assemblies 200 and/or 300 if so desired by a user.
Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without department from the spirit and scope of the invention as defined in the following claims.
