Abstract:
A C-clamp with an expeditious adjustment feature. The C-clamp comprises a C-frame having a seat pad and a hole at its either ends. A cylinder is to be received within the hole; the cylinder in turn carrying a clamp rod, which is used for pressing a work piece against the seat pad. The cylinder and the hole permit the clamp rod both to be rotated and to be freely pushed through the cylinder against the seat pad.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    None 
       FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable 
       SEQUENCE LISTING OR PROGRAM 
       [0003]    Not Applicable 
       STATEMENT REGARDING COPYRIGHTED MATERIAL 
       [0004]    Portions of the disclosure of this patent document contain material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office file or records, but otherwise reserves all copyright rights whatsoever. 
       BACKGROUND 
       [0005]    The present invention relates to work piece-holding devices and more particularly to C-clamps and even more particularly to a C-clamp with an expeditious adjustment feature. 
         [0006]    A C-clamp typically includes a C-frame and a threaded rod to be used in conjunction with the C-frame. The C-frame comprises a pair of oppositely faced arms, namely first and second arms, both connected by an intermediate arm. The ends of the first and the second arms include a seat pad and a threaded hole respectively; the seat pad for providing a gripping surface. The threaded rod is to be received within the threaded hole. One end of the threaded rod includes a shoe member that faces the seat pad of the first arm. The other end of the threaded rod includes a handle. The handle can be rotated in either direction so that the threaded rod can be moved thread-by-thread in a forward or backward direction. Generally, to make use of the C-clamp, a work piece/work pieces are placed between the shoe member and the seat pad. The handle of the threaded rod is rotated until the work piece/work pieces are firmly secured between the seat pad and the shoe member. 
         [0007]    C-clamps are generally made of different sizes, ranging from small to large. The operation of the C-clamps, especially the larger ones, is inefficient because the threaded rod has to be rotated so that its entire length has to advance thread-by-thread until the work piece is firmly clamped. This process becomes all the more difficult and strenuous when smaller and/or thinner work pieces are to be clamped. This is because the thinner/smaller the work piece, the more thread-by-thread displacement of the threaded rod required. Thus, more time and efforts is required. To overcome this problem, it is desirable to move or slide the threaded rod rapidly, without having to rotate it, over a considerable distance until the work piece is gripped, and then secure the work piece firmly by rotating the threaded rod. Several C-clamps which facilitate this expeditious movement of the threaded rod are known in the art. 
         [0008]    For example, U.S. Pat No. 4,627,604 to Choi discloses a multi-element C-clamp having a work piece-gripping surface at a gripping arm on one end piece, and a gripping element supported from a cooperating gripping arm of a second end piece; the gripping element being advanced as rotated. A spring biased locking lever locks the end pieces in predetermined juxtaposition with respect to one another, with one non-gripping arm of one end piece inserted into a corresponding non-gripping hollow arm of the other end piece. Security latches are provided in the locking levers to ensure against accidental disengagement of end pieces during use. Although the C-clamp and the present invention serve the same purpose, the present invention is structurally distinguishable as it needs to be manipulated at the point where the clamp rod and the C-frame are coupled to achieve the purpose. 
         [0009]    U.S. Pat. No. 6,296,241 to Harrison discloses an adjustable C-clamp, which includes a C-shaped frame fitted with parallel bottom and top clamp seats and a clamp cylinder at the top clamp seat. A slotted cylinder is secured in the clamp cylinder by an Allen screw. A clamp rod disposed in the slotted cylinder is fitted with a clamp rod pin. A clamp nut typically attached to one end of the clamp rod faces the bottom clamp seat across the expanse of the clamp frame. The clamp rod pin is designed to slide through a pair of parallel, diametrically-opposed longitudinal cylinder slots in the slotted cylinder to facilitate adjusting the clamp rod in the slotted cylinder and quickly positioning the clamp nut at a selected spacing from the bottom clamp seat. By rotation of the clamp rod in the slotted cylinder, the clamp rod pin is seated in a selected pair of multiple spaced-apart pin slots extending from the respective longitudinal cylinder slots in diametrically opposed relationship with respect to each other. Continued rotation of the clamp rod facilitates threaded extension of the clamp cylinder through the top clamp seat and advancement of the clamp nut against the bottom clamp seat. In another embodiment, the slotted cylinder is omitted and the longitudinal cylinder slots and respective sets of pin slots are provided in the clamp cylinder. 
         [0010]    U.S. Pat. No. 5,423,525 to Spainhower discloses a C-clamp comprising a C-shaped body. The body comprises a first end and a second end, the first and the second ends terminating in an anvil and a base respectively. The base includes an opening. Further, the base includes a first member and a second member, both pivotally connected thereon. The first and second members are operative between open and second positions. In the closed position, the first and the second members are joined together to form an aperture that is aligned with the opening in the base; the aperture being internally threaded. In the open position, the first and the second members are tilted sideward in opposite directions whereby the aperture is divided longitudinally. The first and second members are operated between the open and closed position by means of a latch. The C-clamp further comprises a screw which includes a foot and a rod at either end, the rod acting as a handle. The screw is disposed within the opening and the aperture such that the foot and the anvil are oppositely located. The screw can be slid within the opening when the first and the second members are in the open position. However, when the first and the second members are in closed position, the screw needs to be rotated so as to advance it in forward or backward direction. Therefore, to make use of the C-clamp, a work piece is to be placed across the expanse of the C-shaped body and the screw is to be freely pushed until the work piece is gripped in between the foot and the anvil. Then the latch is to be released, so that the first and second members engage in closed position. Subsequently, the screw is rotated until the work piece is tightly clamped. 
         [0011]    Although the above references facilitate an expeditious adjustment of the C-clamps, the present invention differs from the above inventions in that the present invention employs a groove and locking device mechanism to secure a clamp rod and facilitate efficient clamping and unclamping of a work piece. 
         [0012]    Therefore, it is an objective of the present invention to provide a C-clamp with an expeditious movement/adjustment feature so as to avoid thread-by-thread advancement of the clamp rod for clamping a work piece. 
         [0013]    A further object is to provide a means for facilitating expeditious adjustment at the point where the C-frame and the clamp rod are coupled. 
         [0014]    Finally, it is an object of the present invention to provide the expeditious adjustment feature by employing a cylinder with a bore, at least one groove, a locking device, and a clamp rod thereby differentiating the present invention from the above references and other related art. These and other objects of the present invention will become better understood with reference to the appended Summary, Description, and Claims. 
       SUMMARY 
       [0015]    The present invention is an adjustable C-clamp comprising a clamp rod and a C-frame, which in turn comprises first and second arms. The ends of the first and the second arms comprise a seat pad and hole respectively. The clamp rod is engaged with the C-frame. The clamp rod includes a shoe member at one of its end. 
         [0016]    The C-clamp further comprises a cylinder that is to be received within the hole. The cylinder contains a bore and thus, comprises an exterior and interior side. The interior includes at least one groove. At least one end of the groove terminates in a shallow end or another groove that is shallower than the first groove. The interior further comprises a locking device initially located within the groove. The clamp rod is to be disposed within the interior such that the seat pad and the shoe member are oppositely faced. The clamp rod can slide within the interior. 
         [0017]    To make use of the C-clamp, the clamp rod is pushed until a work piece is gripped between the shoe member and the seat pad. The clamp rod is then rotated in a first direction so that the locking device moves towards the shallow end of the groove. At this point the clamp rod gets substantially locked within the interior of the cylinder. Further rotation of the clamp rod in the same direction enables a tighter gripping on the work piece due to extension of the cylinder along with the clamp rod thereby producing the desired clamping effect. Rotating the clamp rod in a second direction followed by sliding it backwards disengages the work piece from the C-clamp. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0018]      FIG. 1  is a perspective view of the C-clamp in accordance with the present invention. 
           [0019]      FIG. 2  is a plan view of the dissembled C-clamp in accordance with the present invention. 
           [0020]      FIG. 3  is a side perspective view of the cylinder in accordance with the present invention. 
           [0021]      FIG. 4  is a front perspective view of the cylinder in accordance with the present invention. 
           [0022]      FIG. 5  is a perspective view of the cylinder with the clamp rod disposed within it in accordance with the present invention. 
           [0023]      FIGS. 6 through 8  are the illustrations of the sequential operations involved in locking the clamp rod within the cylinder in accordance with the present invention. 
           [0024]      FIG. 9  is a perspective view of the C-clamp holding a work piece in accordance with the present invention. 
           [0025]      FIG. 10  is a front perspective view of the cylinder employed with locking devices of ball bearings in accordance with the present invention. 
           [0026]      FIG. 11  is a front sectional view of the cylinder with two primary grooves it in accordance with the present invention. 
           [0027]      FIG. 12  is a perspective view of the c-clamp without the cylinder in accordance with the present invention. 
       
    
    
     FIGURES-REFERENCE NUMERALS 
       [0000]    
       
           100  . . . Adjustable C-clamp 
           110  . . . Handle 
           120  . . . C-frame 
           130  . . . First Arm 
           140  . . . Second Arm 
           150  . . . Intermediate Arm 
           160  . . . Cylinder 
           170  . . . Clamp Rod 
           180  . . . Shoe Member 
           190  . . . Seat Pad 
           200  . . . Ridge 
           210  . . . Locking device 
           220  . . . Hole 
           300  . . . Bore 
           400  . . . Interior 
           410  . . . Groove 
           900  . . . Work Piece 
           1000  . . . Bearings 
       
     
       DETAILED DESCRIPTION 
       [0046]    Referring to the drawings, a preferred embodiment of an adjustable C-clamp  100  is illustrated in  FIGS. 1 through 12 . Referring to  FIG. 1 , the C-clamp  100  comprises a handle  110 , C-frame  120 , a first arm  130 , a second arm  140 , an intermediate arm  150 , a cylinder  160 , a clamp rod  170 , a shoe  180 , and a seat pad  190 . The C-frame  120  is defined by first arm  130  and second arm  140  which are oppositely faced. The first and second arms,  130  and  140 , are connected by an intermediate arm  150 . The ends of the second arm  140  comprising a seat pad  190 . The seat pad  190  may include a gripping surface such as grooves, ridges, additional gripping materials or the like attached to the seat pad  190 , to further improve the gripping ability of the seat pad  190 . The shoe  180 , like the seat pad  190 , may also have a gripping surface such as grooves, ridges, additional gripping materials or the like to further improve the gripping ability of the shoe  180 . The connection of shoe  180  to clamp rod  170  may be a ball and joint assembly to allow for flexibility of the shoe  180 . Shoe  180  and handle  110  are detachable from clamp rod  170 . The C-frame  120  can be made of any materials such as metal, iron, bronze, steel, aluminum, wood or plastic depending on its use. 
         [0047]    Referring to  FIG. 2 , which shows the C-clamp  100  of the present invention disassembled, further shows ridge  200 , locking device  210 , and hole  220 . Ridge  200  which may be a part of cylinder  160  keeps the cylinder  160  from sliding through hole  220 . Hole  220  may include threads or other means of retaining cylinder  160 . Locking device  210  while shown as a rod may be a rod, cylinder, sphere, or any other shape and may be magnetized to better adhere to clamp rod  170 . 
         [0048]    Referring to  FIG. 3 , which shows cylinder  160 , may be made of metal, iron, bronze, steel, aluminum, wood, or the like. Cylinder  160  contains bore  300  and may also include threads on the exterior of the cylinder  160  such that when inserted into hole  220 , the threads of cylinder  160  would engage the threads of hole  220 . 
         [0049]    Referring to  FIG. 4 , cylinder  160  is shown with a bore. On the bore side or interior  400  of cylinder  160  is groove  410 . Groove  410  includes at least one shallow end or a secondary groove that is shallower than groove  410 . Inside groove  410  is locking device  210 . 
         [0050]    Referring to  FIG. 5 through 8 , clamp rod  170  is shown in the interior of cylinder  160  with locking device  210  in the deep part of groove  410 . As clamp rod  170  is rotated in a first direction, locking device  210 , moves towards the shallow side of groove  410  and substantially locks clamp rod  170  to the interior  400  of cylinder  160 . This locked position prevents the clamp rod  170  from sliding within the interior  400 . If cylinder  160  and hole  220  are threaded, further rotation of the clamp rod  170  in the same direction advances the clamp rod  170  forward due to the threaded extension of the cylinder  160 . Rotation of clamp rod  170  in a second direction releases the clamp rod  170  and moves the locking device  210  from the shallow end of groove  410 , thereby bringing the clamp rod  160  back to its initial position, where clamp rod  170  can slide within the cylinder  160 . 
         [0051]    Alternatively, if there are two shallow ends of groove  410 , the rotation of clamp rod  170  in the second direction produces the same locking effect within cylinder  160 . Further rotation of clamp rod  170  in the same second direction moves the cylinder  160  in the second direction thread-by-thread. Rotating clamp rod  170  in the first direction brings back the clamp rod  170  to the initial position. 
         [0052]    Therefore, to clamp a work piece  900  or a plurality of work pieces as seen in  FIG. 9 , the clamp rod  170 , when in its initial position, is moved until the work piece  900  is gripped between the seat pad  190  and the shoe member  180 . Once the work piece  900  is gripped, the handle  110  is rotated in the first direction, which causes the movement of the locking device  210  to the shallow end of groove  410 . This locks clamp rod  170  within cylinder  160 . Further rotation of handle  110  tightens the grip of the C-clamp  100  over the work piece  900 , owing to the forward advancement of the cylinder  160  carrying the clamp rod  170 . The handle  110  is to be rotated in the second direction to free the work piece  900 . 
         [0053]    Referring to  FIGS. 10 through 12 , alternative embodiments of the present invention using a plurality of locking devices  210  in the form of bearings within the grooves  410  instead of the locking device  210  as a rod. In another embodiment, two grooves  410  are provided, each with shallow ends; the grooves  410  being diametrically opposite to each other as seen in  FIG. 11 . In yet another embodiment of the present invention, the cylinder  160  and the hole  220  is one unit and the locking device  210  and the groove  410  are employed within the hole  220  of the C-frame  120  as seen in  FIG. 12 . 
         [0054]    All features disclosed in this specification, including any accompanying claims, abstract, and drawings, may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
         [0055]    Any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. §112, paragraph 6. In particular, the use of “step of” in the claims herein is not intended to invoke the provisions of 35 U.S.C. §112, paragraph 6. 
         [0056]    Although preferred embodiments of the present invention have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.