Abstract:
A clamping apparatus has a body and an elongated member that is extendable from the body. In another aspect of the present invention, a clamp has a workpiece engaging arm mounted adjacent an end of the elongated member. A further aspect of the present invention causes the elongated member to linearly extend and rotate when advanced.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION  
         [0001]    The present invention relates generally to clamps and more specifically to an industrial clamp employing a swinging and linear motion.  
           [0002]    Various industrial clamps have an arm which uses a linear and rotary motion. Examples of such conventional devices are disclosed within U.S. Pat. No. 6,059,277 entitled “Retracting Power Clamp” which issued to Sawdon et al. on May 9, 2000, and U.S. Pat. No. 5,165,670 entitled “Retracting Power Clamp” which issued to Sawdon on Nov. 24, 1992. Both of these patents are incorporated by reference herein. Other industrial clamps are known which have a piston rod and an externally mounted arm. The arm is linearly extendable along the piston rod axis and is rotatable only along a transverse plane perpendicular to the piston rod axis. These clamps, known as the 1500 Series and 2500 Series clamps from BTM Corp., are also pneumatically driven with a sealed body. While such traditional devices have significantly improved the art, additional and enhanced movement is often desirable in order to clear workpiece flanges or other obstructions during clamping or unclamping.  
           [0003]    In accordance with the present invention, a clamping apparatus is provided that has a body and an elongated member that is extendable from the body. In another aspect of the present invention, a clamp has a workpiece engaging arm mounted adjacent an end of the elongated member. A further aspect of the present invention causes the elongated member to linearly extend and rotate when advanced. In yet another aspect of the present invention, a camming surface is provided in the body of the apparatus. An additional aspect of the present invention provides for improved fastening of the arm to the elongated member. A method of operating the clamp is also disclosed.  
           [0004]    The clamp of the present invention is advantageous over conventional devices in that the present invention has an increased and enhanced range of motion during clamping and unclamping in order to clear workpiece flanges and other adjacent obstructions. The present invention is further advantageous by use of an automatically movable opening cover to minimize undesired contamination of the clamp body; this reduces dirt, dust, weld splatter and other external debris from otherwise entering the shaft opening, which could increase friction between moving parts and reduce durability of the clamp. The unique constructions and movement of the present invention cover allow the clamp to remain fully sealed when the workpiece arm is retracted, thereby retaining internal grease and excluding external contaminants. Furthermore, the camming surface design allows for simplified and reduced cost manufacturing and assembly while minimizing body openings that would otherwise need to be sealed. Moreover, the arm-to-shaft mounting arrangement of the present invention provides superior adjustability and fastening. Additional advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIGS. 1 and 2 are perspective views showing the preferred embodiment clamp of the present invention in different movement positions;  
         [0006]    FIGS.  3 - 5  are side elevational views showing the preferred embodiment clamp in various positions;  
         [0007]    [0007]FIG. 6 is a side elevational view, taken 90 degrees to that of FIG. 3, showing the preferred embodiment clamp in a retracted position with a switch plate removed;  
         [0008]    [0008]FIG. 7 is an exploded perspective view showing the preferred embodiment clamp, but with an alternately configured arm;  
         [0009]    FIGS.  8 - 10  are enlarged and fragmentary side elevational views, taken within circle  8  of FIG. 3, showing the preferred embodiment clamp in different positions with a side plate removed;  
         [0010]    [0010]FIG. 11 is a diagrammatic side view showing a first alternate embodiment clamp of the present invention;  
         [0011]    [0011]FIG. 12 is a diagrammatic side view showing a second alternate embodiment clamp of the present invention; and  
         [0012]    [0012]FIG. 13 is a fragmentary and diagrammatic side view showing a third alternate embodiment clamp of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    Referring to FIGS.  1 - 3 , the preferred embodiment of a clamp apparatus  21  of the present invention is used to clamp or otherwise engage a workpiece  23 , such as an automotive vehicle panel, against a work surface  25  or fixture in an industrial manufacturing plant. Workpiece  23  typically has one or more sheets of steel with upturned flanges  27 , downturned flanges  29  or alternately shaped surfaces which need to be secured together for welding, assembly or machining operations. A bracket  31  is mounted to any side surface of a body or housing  33  of clamp  21  by way of screws  35  or other removable fasteners. An arm of an articulated robot  37  or stationary, factory-floor mounted structure is secured to bracket  31  for respectively moving or maintaining the position of clamp  21  relative to one or more of workpieces  23 .  
         [0014]    As can best be observed in FIGS. 2, 3 and  6 - 8 , clamp  21  has a single piece or unitary housing  33  cast and then machined from a single block of aluminum. A longitudinal bore  51  is machined within the center of body  33  and is accessible through an external opening  53  in a first end of body  33 . A first camming surface  57 , having a longitudinally extending leg  59  and a diagonally offset leg  61 , is machined through an outside wall  63  of body  33  and openly communicates with bore  51 . During manufacturing, a milling head is inserted through a first camming slot defined by first camming surface  57  and through the corresponding portion of bore  51  in order to machine a recessed, matching second camming surface  65  within an opposite second side wall  67  of body  33 . A second camming slot defined by second camming surface  65 , however, is recessed in and does not protrude all the way through the outside surface of side wall  67  such that a separately attached plate and seal are not required on the second side wall  67 . Second camming surface  65  identically mirrors the shape of first camming surface  57 . This preferred construction and manufacturing procedure allows for a unitary or one piece body to have a pair of opposed and integral camming surfaces as compared to prior devices which had bifurcated housings with somewhat less durable sealing and were prone to tolerance variations between halves leading to potential cam follower binding when assembled. A steel cover plate  69  is removable secured by screws  71  to an external side of body  33  to cover the first camming slot.  
         [0015]    A piston cylinder  81  is machined into an end of body  33  opposite the end containing external opening  53 . Piston cylinder  81  preferably has a generally oval cross sectional shape although a circular cross sectional shape can alternately be employed. Piston cylinder  81  is in communication with and coaxial with bore  51 . An aluminum end cap  83  and elastomeric O-ring seal  85  are fastened by way of screws  87  to the end of body  33  adjacent piston cylinder  81 . Pneumatic ports  89  and  91  are machined in the external surface of body  33  for attaching hoses and fittings to allow the entry and exit of pneumatic pressure into piston cylinder  81 .  
         [0016]    An oval shaped piston  93  and an elongated piston rod  95  coupled thereto longitudinally advance and retract in response to the selective use of pneumatic pressure through ports  89  and  91 . Sets of elastomeric seals  97  and  99  are secured within grooves of piston  93  in order to seal piston against the internal surface of piston cylinder  81 . An O-ring seal  101  is inserted within a cavity of body  33  adjacent bore  51  in order to seal piston rod  95  to body  33 . Piston rod  95  at least partially slides in a linear longitudinal direction within bore  51 .  
         [0017]    A partially circular-cylindrical and elongated shaft  121  has a first bifurcated end  123  with a first hole  125  and a second hole  127 . A reduced thickness end  129  of piston rod  95  rotatably fits within a channel formed within bifurcated end  123  of shaft  121 . A pin  131  is located within holes  125  and  133  so as to drivably couple piston rod  95  to shaft  121 . Another pin  141  fits within second hole  127  of shaft  121  to retain steel rollers  143  and  145  which serve as cam followers along camming surfaces  63  and  65 , respectively.  
         [0018]    An external end  151  of shaft  121  has a reduced diameter and a pair of opposed flats  153 . A steel cover  155  is essentially a flat rectangle with an enclosed hole defined by a pair of lateral flat surfaces joined by rounded surfaces. The flat surfaces of the hole align with flats  153  of shaft  121  in order to locate cover relative to shaft  121  in a key-hole like manner throughout all shaft movement positions. End  151  of shaft  121  has at least a partially threaded section for receiving a jam nut  157 . A compression spring  159  is disposed between nut  157  and cover  155  and serves to bias cover  155  against lower shoulders of flats  153  which coincide with the adjacent end of body  33  when shaft  121  is in its retracted position.  
         [0019]    A workpiece engaging arm  171  has a proximal end segment within which is located a main aperture  173  with an opening axis concentric to the elongated axis of shaft  121  when assembled. A through-slot  175  connects main aperture  173  to an external surface of arm  171 . Furthermore, a fastening hole  177  is transversely oriented within arm  171  to intersect slot  175 . This arrangement allows arm  171  to be adjustably attached to shaft  121  by manually orienting arm  171  in any  3600  position along a plane transverse to the elongated axis of shaft  121 . End  151  of shaft  121  is preferably patterned with a continuous thread to match an internal thread in main aperture  173  of arm  171 , however, a knurl pattern, spine pattern or even a smooth circular-cylindrical configuration can be employed on either or both mating surfaces. After arm  171  has been manually oriented relative to shaft  121  and end  151  has been inserted through main aperture  173 , a screw  179  is inserted into hole  177 . Screw  179  has threads that match corresponding threads within the far section of fastening hole  177 , but has clearance to the oversized adjacent section of fastening hole  177 . Screw  179  spans or bridges across slot  175  whereby manual rotation of screw  179  serves to compressibly tighten the main aperture of arm  171  around the circumference of shaft  121  in order to firmly secure one to the other. Arm  171  is preferably machined from steel and has an L-side view shape, but alternately, may have a straight configuration such as that shown in FIG. 7 which optionally allows for gripper pads (not shown) or other attachments to be secured to a distal end thereof.  
         [0020]    A steel switch plate  191  is fastened to an external side of body  33  over a channel  193  machined into the body. An electrical proximity-type switch  195 , preferably obtained from Turk Corp., is carried on switch plate  191  for indicating the fully retracted and advanced positions of the rollers, piston rod, shaft or any of the other associated movement mechanisms. Proximity sensors  197  and  199  are part of the switch and plate assembly.  
         [0021]    Moreover, a compression spring  201  and detent ball  203  are compressed within a cavity in body  33 . This provides a mechanical detenting action against the adjacent roller  143  when the roller is in its retracted position, which corresponds with the workpiece clamping position in the preferred embodiment; this encourages arm  171  to remain in its workpiece clamping position even when fluid pressure is undesirably lost or absent. Alternately, a compression spring contained within piston cylinder  81  can be employed instead of spring  201  in order to bias piston  93  toward its retracted position.  
         [0022]    The operation of the present invention clamp apparatus  21  will now be described in greater detail. FIGS. 1, 3 and  8  show piston  93 , piston rod  95 , shaft  121  and arm  171  in a retracted position wherein arm  171  clamps against workpiece  23  and cover  155  is biased against the adjacent end of body  33 . In this position, cover  155  is essentially sealed against body  33  to deter external contaminants from entering the shaft opening. Referring now to FIGS. 4 and 9, piston  93  automatically drives piston rod  95 , shaft  121 , cover  155  and arm  171  to a linearly extended and coaxial position. Rollers  143  and  145  are still within longitudinally extending leg  59  of each camming surface  57  and  65 , respectively. Additionally, cover  155  is linearly moved away from the adjacent end of body  33 . Subsequently, FIGS. 2, 5 and  10  illustrate the fully advanced position wherein piston  93  has automatically driven piston rod  95 , shaft  121 , cover  155  and arm  171  to a rotated position along the same longitudinal plane as the initial linear movement. Rollers  143  and  145  act with the corresponding offset camming surfaces of body  33  in order to cause this rotation in response to the further linear piston driving motion. This allows arm  171  to fully clear flanges  27  of workpiece  23  and to allow simplified vertical movement of workpiece  23  without undesirably contacting the disengaged and advanced clamp arm.  
         [0023]    [0023]FIG. 13 shows an alternate embodiment clamp  221  of the present invention. This clamp is the same as the preferred embodiment clamp except that cover  255  has a generally flat first surface adjacent and generally perpendicular to an elongated direction of a shaft  321 , and the cover further has a second surface generally perpendicular to the flat surface such that the cover essentially conceals an intersection between offset adjacent and external surfaces of a housing  133 . This configuration allows for a longer external opening circumscribing the side and end intersection of body  133  to allow for even greater swinging rotation of shaft  321  and an attached arm  371 . This embodiment also compresses a compression spring  259  directly between arm  371  and cover  255  without the use of an intervening nut  157 .  
         [0024]    A second alternate embodiment clamp  401  can be observed in FIG. 11. The construction of clamp  401  in this embodiment is essentially the same as that for the preferred embodiment, but inverted. Clamp  401  also includes a cover (not shown). An arm  471 , however, is differently configured with a scoop-like tapered, distal end  473  which rotates from an advanced position to an intermediate position in order to scoop beneath a workpiece  475 . Subsequently, arm  471  is retracted toward a body  433  in a linear direction in order to lift workpiece  475 . Clamp  401  can lower and then gently release workpiece  475  by reverse linear and then rotary movement.  
         [0025]    Referring now to FIG. 12, a third alternate embodiment clamp  501  of the present invention is shown. This embodiment employs a pair of inverted clamps  503  and  505  which are the same as that with the second alternate embodiment except that their respective bodies  533  and  535  are joined together by a frame  537  which also serves to space apart the clamps by a predetermined distance. Frame  537  can be movably carried by a robotic arm or stationarily fixed to a factory floor mounted structure. In operation, the opposed rotary and linear movement of the facing arms  571  and  573  allows for rotated engagement of a workpiece and then linear lifting of the workpiece  575  when the arms are moved from their advanced positions to their retracted positions in a simultaneous and automatic manner.  
         [0026]    While various embodiments of the swinging and linear motion clamp have been disclosed, it should be appreciated that additional alternate constructions may fall within the scope of the present invention. For example, linkages and/or differently configured cam and cam follower mechanisms can be employed to achieve the presently disclosed clamp motion although many of the advantages of the present invention may not be realized. Furthermore, many other cover shapes and shaft openings can be used. It is envisioned that the camming and body construction and method of manufacturing same can be employed in other types of clamps having different arm motions and even without the preferred automatically moving cover. A separately attached piston cylinder can be provided in place of the preferred integral one discussed herein. It should also be appreciated that hydraulic fluid pressure or even electromagnetic actuation can be used although many of the advantages of the present invention may not be realized. While various materials, shapes and manufacturing processes have been disclosed, it will be appreciated that others can be also employed. It is intended by the following claims to cover these and any other departures from the disclosed embodiments which fall within the true spirit of this invention.