Abstract:
A sealed pin locator clamp includes an actuator having a linearly drivable member, a clamp body, a locating pin coupled to and protruding from the clamp body and a clamping member slidably positioned within an arcuate slot formed in the pin. The clamping member is drivingly coupled to the actuator and selectively moveable between a first position inside the pin and a second position at least partially protruding from the pin.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION  
       [0001]     The present invention relates generally to a clamp and, more particularly, to a fluid powered, sealed pin locator clamp.  
         [0002]     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 station, 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. 5,190,330 entitled “Powered Clamp with Parallel Jaws” which issued on Mar. 2, 1993; all of which are incorporated by reference herein.  
         [0003]     It is desirable to prevent a clamping arm from opening and releasing the workpiece if there is a loss of fluid pressure. 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.  
         [0004]     In accordance with the present invention, a sealed pin locator clamp includes an actuator operably moveable in a linear direction, a clamp body, a pin coupled to the clamp body and an arcuate clamping member. The pin includes an external surface and an internal arcuate slot in communication with the external surface. The arcuate clamping member is positioned within the arcuate slot and drivingly coupled to the actuator. The clamping member is selectively moveable between a first position inside the pin and a second position at least partially protruding from the pin. The clamping member is operable to exert a force toward an anvil to temporarily secure a workpiece to the sealed pin locator clamp.  
         [0005]     The sealed pin locator clamp of the present invention is highly advantageous over traditional clamps in that the clamp includes an arcuate clamping member contained within a precise slot of a locating pin. The clamping member is moveable in response to the application of pressurized fluid to a sealed chamber. This design eliminates exposing the inner mechanism to contamination such as weld flash, metal shavings or coatings on the metal which may rub off when parts are loaded over the pin locator clamp. Additionally, the arcuate clamping member is rotatable from a position inside the pin to a position outside the pin such that the workpiece may be freely positioned over the pin when the clamping member is retracted and firmly held in place when the clamping member is extended.  
         [0006]     In addition, the present invention optionally includes a self-locking mechanism which does not allow the clamping mechanism to retract if fluid actuation pressure is lost. A first embodiment includes a spring to supply load to the clamping member in the event of pressure loss. An alternate embodiment includes a lock pin which engages a piston to resist retraction of the clamping member. The lock pin may be released via fluid pressure once pressure returns to the system or manually by pulling an external portion of the pin.  
         [0007]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0009]      FIG. 1  is a side elevational view showing a first embodiment sealed pin locator clamp constructed in accordance with the teachings of the present invention;  
         [0010]      FIG. 2  is a perspective view of the first embodiment sealed pin locator clamp;  
         [0011]      FIG. 3  is a exploded perspective view of the first embodiment sealed pin locator clamp;  
         [0012]      FIG. 4  is a side view cross-sectional view of the first embodiment sealed pin locator clamp having a clamping member in an extended position;  
         [0013]      FIG. 5  is a cross-sectional side view of the first embodiment sealed pin locator clamp having the clamping member in a retracted position;  
         [0014]      FIG. 6  is a partial side view depicting the interconnection between the clamping member and a link of the sealed pin locator clamp;  
         [0015]      FIG. 7  is a partial fragmentary top view depicting the clamping member and link interconnection;  
         [0016]      FIG. 8  is a partial cross-sectional side view of a second embodiment sealed pin locator clamp;  
         [0017]      FIG. 9  is a partial cross-sectional side view depicting another alternate embodiment sealed pin locator clamp having an enlarged locator pin with an optional second clamping member;  
         [0018]      FIG. 10  is a cross-sectional side view depicting an alternate embodiment sealed pin locator clamp having a manually releasable locking pin;  
         [0019]      FIG. 11  is a partial top view depicting the clamping member and link interconnection of the alternate embodiment sealed pin locator clamp shown in  FIG. 10 ; and  
         [0020]      FIG. 12  is a partial top view of an alternate embodiment sealed pin locator clamp having a quick change pin mount.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     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.  
         [0022]     Referring to  FIGS. 1-7 , a first embodiment of a locking pin clamp  20  of the present invention is used to locate or gauge and then clamp a workpiece  22  in a work station such as a moving assembly line, in a start-stop manufacturing station or in an off-line work cell. A clamp body  24  is coupled to a base  26  which in turn may be mounted to a table or attached to an end effector secured to a robotic arm. A seal  27  is positioned between body  24  and base  26 . Clamp body  24  may be alternatively shaped to include a cylindrical outer surface. Also, base  26  may be extended to include a flange  25  shown in phantom line representation. Flange  25  includes at least one aperture to assist in mounting pin clamp  20 . Body  24  is preferably machined with a NAAMS hole pattern on one or more sides. Base  26  also includes a NAAMS hold pattern to aid in mounting pin clamp  20 . Accordingly, workpiece  22  may be moved relative to a stationarily mounted clamp  20  or clamp  20  may be moved relative to a stationarily mounted workpiece.  
         [0023]     Clamp  20  includes a piston  28  slidably positioned within a stepped bore  30 . Stepped bore  30  includes a first bore  31  and a second bore  32 . First bore  31  is coaxially aligned with second bore  32 . Stepped bore  30  includes a longitudinal axis  34  offset from a longitudinal axis  35  of body  24 . Locking pin clamp  20  also includes a link  36 , a clamping member  38 , a pin  40  and an anvil  42 .  
         [0024]     Piston  28 , link  36  and clamping member  38  are drivingly coupled to one another to move clamping member  38  between an extended or clamping position shown in  FIG. 4  to a retracted position shown in  FIG. 5 . In the extended position, a distal end  44  of clamping member  38  exerts force on workpiece  22  which is reacted by an upper surface  46  of anvil  42 . First end  44  may be rounded as depicted in the Figures, or may alternately include a flat. The flat would be oriented at an angle to upper surface  46  to maintain a line contact with workpiece  22 . A pair of seals  48  are coupled to piston  28  to sealingly engage first bore  31 . Seals  48  define a first chamber  50  and a second chamber  52 . Pressurized fluid is supplied to first chamber  50  to translate piston  28  and move clamping member  38  toward the extended position. Second chamber  52  is selectively supplied with pressurized fluid to move piston  28  in an opposite direction toward base  26  thereby moving clamping member toward the retracted position of  FIG. 5 .  
         [0025]     Piston  28  includes a substantially cylindrical first section  54 , a substantially cylindrical second section  56  axially extending from first section  54 , and a third section  58  axially extending from second section  56 . First section  54  includes a spring bore  60  for receipt of a spring  62 . Spring  62  is a compression spring and is shown in a pre-loaded position in  FIG. 4 . Accordingly, if pressurized fluid is not supplied to first chamber  50  or second chamber  52 , a force is exerted from clamping member  38  to anvil  42 . Spring  62  assures that at least a minimum force is exerted on workpiece  22  should the pressurized fluid source be compromised during a manufacturing operation.  
         [0026]     Second section  56  is slidably positioned within second bore  32 . A seal  64  is positioned within a pocket  66  formed within second bore  32 . As is clearly shown in the Figures, third section  58  defines a smaller effective diameter than second section  56  while second section  56  defines a smaller effective diameter when compared to first section  54 . The transition from first section  54  to second section  56  of piston  28  is axially positioned to allow clamping member  38  to engage workpieces  22  having a wide variety of thicknesses. In particular, the axial location of the transition from first section  54  to second section  56  of piston  28  allows extended linear travel of piston  28  to ensure a sufficient clamp force is generated on the different thickness materials.  
         [0027]     As most clearly shown in  FIGS. 6 and 7 , third section  58  is substantially cylindrical including a notch  68  having a flat  70 . A post  72  laterally extends from flat  70  transverse to longitudinal axis  34 . Link  36  includes a first end  74  and a bifurcated second end  76 . First end  74  includes an aperture  78  in receipt of post  72 . Post  72  and aperture  78  are sized such that link  36  is free to rotate about the longitudinal axis of post  72 . Bifurcated second end  76  includes first leg  80  and a second leg  82 . Each of the first and second legs includes an aperture  84  positioned along a common axis.  
         [0028]     Clamping member  38  is a generally flat arcuately shaped member. Distal end  44  includes a substantially planar first face  86  and a substantially planar second face  88  offset and parallel to first face  86 . A proximal end  90  of clamping member  38  has a reduced thickness from distal end  44  to define a web  92 . An aperture  94  extends transversely through web  92  to accommodate a pin  96  which rotatably interconnects clamping member  38  and link  36 . Specifically, pin  96  extends through first leg  80 , web  92  and second leg  82 . Clamping member  38 , pin  96  and bifurcated second end  76  of link  36  are slidably positioned within an arcuate slot  98  formed in pin  40 . Arcuate slot  98  includes a generally rectangular cross-section and communicates with an external surface  100  of pin  40  at both an upper aperture  102  and a lower aperture  104 . Clamping member  38  is sized to closely conform to the dimensions of arcuate slot  98 . Therefore, locking pin clamp  20  operates as a self-sealing and self-cleaning apparatus. Additionally, upper aperture  102  is exposed to the work cell environment. To further reduce the possibility of contamination, aperture  102  is substantially vertically oriented in most applications. The vertical orientation substantially reduces the likelihood of contaminant entry.  
         [0029]     An alternate clamping member  38 ′ is shown in  FIG. 5  in phantom line representation. Alternate clamping member  38 ′ spans an extended arc length. The extended arc length provides greater support for clamping member  38 ′ during operation. A recess  105  is formed in anvil  42  to accept proximal end  90  and account for the increased length of clamping member  38 ′.  
         [0030]     Pin  40  is a substantially cylindrical member having a spherically-shaped first end  106  and a second end  108 . Second end  108  includes a flange  110  having a bottom surface  112  supported by a land  114  of a recess  116  formed at one end of body  24 . Anvil  42  is a substantially disc-shaped member having a counterbore  118  extending therethrough. Counterbore  118  is sized for receipt of flange  110  and the cylindrical portion of pin  40 . One skilled in the art will appreciate that pin  40  may be constructed having any number of geometrical cross-sectional shapes and the cylindrical shape described is merely exemplary. Anvil  42  further includes an internal relief  120  sized to accommodate the articulated positions of link  36  and piston  28 . A roll pin  122  couples and aligns anvil  42  with body  24 . Furthermore, a fastener counterbore  123  is aligned with an internally threaded passageway  124  of body  24 . A threaded fastener  125  couples pin  40  and anvil  42  to body  24 .  
         [0031]     As best shown in  FIGS. 4 and 5 , a proximity switch assembly  126  is configured to signal an electronic controller (not shown) or a user when piston  28  is located near the top or bottom of first bore  31 . More particularly proximity switch assembly  126  includes a housing  128 , an access plate  130 , a first sensor head  132 , a second sensor head  134  and wire  136  interconnecting the sensor heads and housing  128 . First sensor head  132  is positioned within a first transverse bore  138 . Transverse bore  138  extends from first bore  31  to a switch pocket  140  formed in body  24 . Second sensor head  134  is positioned within a second transverse bore  142 . Second transverse bore is in communication with first bore  31  and pocket  140 . First sensor head  132  and second sensor head  134  are positioned to detect the presence or absence of piston  28 . Each sensor head outputs a signal when the piston is within a predetermined proximity of an end face of the sensor head. In this manner, a controller or an operator is notified that clamping member  38  is in the extended position, retracted position or somewhere therebetween depending on the signals output from proximity switch assembly  126 .  
         [0032]      FIG. 8  depicts an alternate embodiment locking pin clamp  200 . Locking pin clamp  200  is substantially similar to locking pin clamp  20 . Accordingly, like numerals will be used to identify previously introduced elements. Locking pin clamp  200  utilizes clamping member  38 , link  36 , piston  28  and body  24  common to clamp  20 . An enlarged pin  202  is coupled to body  24  via an anvil  204 . Pin  202  includes a locating lug  205  to prevent loss of orientation of pin  202  and anvil  204  thus preventing possible binding. Anvil  204  includes a correspondingly enlarged bore  206  extending therethrough. Link  36  and third section  58  of piston  28  are positioned within the boundary defined by counterbore  206 . Therefore, anvil  204  of second pin clamp  200  does not require the special machining of a relief such as previously described in relation to anvil  42 .  
         [0033]      FIG. 9  depicts another alternate embodiment locking pin clamp  300 . Locking pin clamp  300  is substantially similar to the previously described locking pin clamps. Accordingly, like elements will maintain their previously introduced reference numerals. Locking pin clamp  300  is also designed to utilize common clamping member  38 , link  36 , piston  28  and body  24 . Locking pin clamp  300  includes a relatively large pin  302  extending through an appropriately sized anvil  304 . Piston  28  and link  36  articulate through apertures formed in pin  302 . Accordingly, special machining is not required of anvil  304 . Additionally, an arcuate slot  306  formed in pin  302  is positioned to one side of a pin longitudinal axis  308 . Based on this positioning of componentry, an optional second clamping member  310  may be selectively driven from a retracted position to an extended position as previously described in relation to clamping member  38 . Preferably, second clamping member is drivingly coupled to a new single piston (not shown) having a pair of links coupled thereto.  
         [0034]      FIGS. 10 and 11  depict another alternate embodiment locking pin clamp  400 . Locking pin clamp  400  is constructed substantially similarly to the locking pin clamps previously described. Accordingly, like elements will retain their previously introduced reference numerals. Locking pin clamp  400  includes a quick change pin mount  402  including an anvil  404 , a locating pin  406  and a pair of threaded fasteners  408 . Pin mount  402  facilitates rapid changing of pin  40  should the need arise during use. Anvil  404  is a substantially rectangular component including parallel sides  412  and  413 . Locking pin clamp  400  includes a body  410  having a slot  414  sized to receive anvil  404 . Locating pin  406  is threadingly engaged with a threaded passage  416  transversely extending through body  410 . Locating pin  406  includes an unthreaded section  418  selectively positionable within key way  420 .  
         [0035]     To disassemble pin mount  402  from clamp  400 , threaded fasteners  408  and locating pin  406  are removed from the assembly. At this time, anvil  404 , pin  40 , clamping member  38  and link  36  may be linearly displaced in the direction of arrow  421  to disengage first end  74  of link  36  from post  72  of piston  28 . At this time, a differently or similarly sized pin replacement pin and anvil may be assembled to clamp  400  by simply reversing the procedure of connecting link  36  to piston  28 , inserting locating pin  406  within key way  420  and installing threaded fasteners  408  to fix anvil  404  to body  410 .  
         [0036]     Clamp  400  also includes a locking assembly  422 . Locking assembly  422  includes a housing  424 , a pull pin  426 , a piston  427  and a return spring  428 . Piston  427  is mounted on pull pin  426  and slidably positioned within a bore  430  of housing  424 . Housing  424  is threadingly coupled to body  410  to define a cavity  432  in communication with a port  434 . Pull pin  426  includes a first end  438  selectively positionable within first bore  31  or adjacent to first bore  31 .  
         [0037]     During actuation, pressure is normally supplied to port  434  to cause piston  427  to position first end  438  of pull pin  426  clear of piston  28 . If the supply of pressurized fluid to clamp  400  is interrupted, return spring  428  causes first end  438  of pull pin  426  to enter first bore  31  and engage an end surface  440  of piston  28  thereby limiting the amount of return travel clamping member  38  may incur.  
         [0038]     If pressure is returned to the system, piston  427  compresses spring  428  to clear pull pin  426  from piston  28 . If, however, it is desirable to move clamping member  38  to the retracted position without a pressurized fluid source, a tang  442  of pull pin  426  may be grasped to overcome the force supplied by return spring  428  to allow piston  28  to pass end  438 .  
         [0039]      FIG. 12  depicts an alternate pin mount  500  including a substantially cylindrical anvil  502  coupled to clamp body  504 . Clamp body  504  includes a substantially cylindrical outer surface  506 . Body  504  includes a recess  507  defined by an upstanding wall  508 .  
         [0040]     Anvil  502  includes a semi-cylindrical downstanding boss  510 , a pocket  512  and a slot  514 . Downstanding boss  510  forms a stepped profile engageable with upstanding wall  508  of body  504 . Boss  510  includes an inner semi-cylindrical portion  516  and an outer semi-cylindrical portion  518 . When assembled, outer semi-cylindrical portion  518  engages wall  508 . End surfaces  520  are formed at the transition of outer semi-cylindrical portion  518  and inner semi-cylindrical portion  516 . Recess  507  includes first, second and third notches  522 ,  524  and  526 , respectively. The notches are positioned to allow relative movement of anvil  502  relative to body  504  in a first transverse direction along line  521 . The translational movement of anvil  502  relative to body  504  is limited when end surfaces  520  of boss  510  engage first notch  522  and second notch  524 . At substantially the same time, inner semi-cylindrical portion  516  engages third notch  526 . Slot  514  provides clearance to a portion of a piston  528  to allow anvil  50  to move relative to body  504  as previously described. A pair of fasteners  530  couple anvil  502  to body  504 . Pin mount  500  may be disassembled from the clamp by simply removing fasteners  524  and sliding anvil  502  transversely relative to body  504  and then lifting anvil  502  off of body  504 .  
         [0041]     It should be appreciated that the embodiments shown are merely exemplary in nature and that a number of variations may be made to the embodiments without departing from the scope of the present invention. Specifically, the link to piston interconnection may be accomplished using a removable roll pin in lieu of the integrally formed post previously described. Additionally, functioning embodiments of the clamp need not include a mechanism for maintaining the position of the clamping member during a loss of pressure. Therefore, the assemblies could be further simplified by removing the return spring and/or the locking assembly.