Abstract:
A clamping device utilizing the mechanism of conventional vise-grip locking pliers comprises an extendable fixed arm and an extendable movable arm, both fitted with threaded holes at one end to attach a wide variety of clamping jaws and accessories. The device is capable of clamping workpieces of various shapes such as rectangular, cylindrical, triangular, and spherical, etc. with adjustable clamping force. It is also capable of clamping workpieces of a broad range of sizes, and capable of clamping a plurality of workpieces at the desired spatial relationship between each other.

Description:
REFERENCE CITED 
   U.S. Patent Documents 
   
     
       
             
             
             
             
           
         
             
                 
                 
             
           
           
             
                 
               2,641,149 
               June 1953 
               Christian Petersen 
             
             
                 
               4,305,575 
               December 1981 
               Dale L. Bardes 
             
             
                 
               4,344,215 
               August 1982 
               Timothy C. Dearman 
             
             
                 
               4,477,937 
               October 1984 
               James Costello 
             
             
                 
               4,542,669 
               September 1985 
               Philippe Roux 
             
             
                 
               4,850,254 
               July 1989 
               Burrell T. Burney 
             
             
                 
               5,022,290 
               June 1991 
               Thomas F. Duffy 
             
             
                 
               5,469,766 
               November 1995 
               Joseph M. Hodges 
             
             
                 
               5,499,800 
               March 1996 
               Stephen D. Albin 
             
             
                 
               6,012,362 
               January 2000 
               Chao-Chi Wang 
             
             
                 
               6,389,937 
               May 2002 
               Hsin-Fa Kang 
             
             
                 
                 
             
           
        
       
     
   
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a class of locking pliers, or vise grips in general, and more particularly to multi-purpose locking pliers with extendable clamping arms and threaded holes on clamping arms to attach a wide variety of clamping jaws and accessories. The invention is capable of clamping workpieces of various shapes such as rectangular, cylindrical, triangular, and spherical, etc. with adjustable clamping force. It is also capable of clamping workpieces within a broad range of sizes. 
   2. Description of the Related Art 
   A conventional locking plier or vise grip generally comprises a fixed arm with clamping jaw, a movable arm attached with clamping jaw and a toggling linkage mechanism attached between the movable arm and the fixed arm. To serve various applications, there are many different designs of the clamping jaws for locking pliers in the field, such as: C-shape clamping arm with round tips used in the Gripping Tool, U.S. Pat. No. 2,641,149; L-shape jaws used in Toe-nailing Clamping Tool, U.S. Pat. No. 4,305,575; V-shape jaws for cylindrical pipe clamping, U.S. Pat. No. 4,344,215; combination of wrench and chain clamping jaws, U.S. Pat. No. 4,477,937; long nose jaws for external and internal clamping, U.S. Pat. No. 4,542,669; combination of vise grip and bar clamp, U.S. Pat. No. 4,850,254; adjustable locking jaws, U.S. Pat. No. 5,022,290; C-shape arm with hole and clip, U.S. Pat. No. 5,469,766; adjustable locking bar clamp, U.S. Pat. No. 5,499,800; V-shape toothed jaws, U.S. Pat. No. 6,012,362; and cylindrical jaws for clamping various sizes pipes, U.S. Pat. No. 6,389,937; etc. However, almost all of these prior arts are single-purpose oriented, some of them may serve more than one purposes, but still very limited in application and flexibility. A number of locking pliers, each with different design features will be required to serve a number of different work holding jobs. Furthermore, the size of a workpiece that can be manipulated on is limited by the physical size of most of these prior arts. In other words, to clamp a workpiece of significantly different dimension will require a similar tool of the appropriate size. It is the intention of the present invention to provide a handy tool to work on workpieces within a broad range of physical sizes. Another intention is to enable the adjustment of the clamping force on a workpiece by turning an adjustment screw. Further intention of the present invention is to provide a convenient means to increase the clamping force on a workpiece by inserting a metal rod or any suitable screwdriver into the hole equipped on the adjustment screw to act as a handle to increase the turning torque. Yet another intention of the invention is to provide a simple means to adjust the workable gap between the clamping jaws of the invention. An additional intention of the present invention is to increase the functionality by attaching a wide variety of clamping jaws and accessories to work on workpieces of different shapes in various ways. 
   SUMMARY OF THE INVENTION 
   The present invention comprises a fixed handle to which a L-shape extendable fixed arm with screw-in jaw is attached, a movable handle to which a L-shape extendable movable arm with screw-in jaw is pivotally mounted, a toggling linkage mechanism pivotally connected between the fixed handle and the movable handle, an adjustment screw inserted into the free end of the fixed handle, a plurality of clamping jaws and a plurality of attachable accessories. The fixed handle, the movable handle, the adjustment screw and the toggling linkage mechanism are similar in design as the conventional locking pliers. The principle of operations of these parts will not be discussed here again. 
   The L-shape extendable fixed arm comprises an upper L-shape metal shank, a first upper straight shank with inverted U-shape cross section riveted to one end of the upper L-shape metal shank, and a second upper straight shank made of solid metal inserted into the first upper straight shank. The second upper straight shank, similar in length as and slidable inside the first upper straight shank, can be fixed at a plurality of positions with screws and nuts through a plurality of holes on the bodies of both the first upper straight shank and the second upper straight shank. The L-shape extendable movable arm comprises a lower L-shape metal shank, a first lower straight shank with U-shape cross section riveted to one end of the lower L-shape metal shank, and a second lower straight shank made of solid metal inserted into the first lower straight shank. The second lower straight shank, similar in length as and slidable inside the first lower straight shank can be fixed at a plurality of positions with screws and nuts through a plurality of holes on the bodies of both the first lower straight shank and the second lower straight shank. Such construction enables the user to extend the effective length of both the fixed arm and the movable arm to the required length matching the size of the workpiece to be clamped. Since the fixed arm and the movable arm are individually extendable, each arm can be extended to a plurality of length combinations to suit special needs of various applications. 
   The free end of the second upper straight shank is shaped as a vertical cylinder with a threaded hole cutting through its centerline. The threaded hole is made to accept various types of clamping jaws or accessories designed for various applications. The free end of the second lower straight shank is shaped as a vertical cylinder with a threaded hole cutting through its centerline. The threaded hole is made to accept various types of clamping jaws or accessories designed for various applications. The L-shape design of both the fixed arm and the movable arm increases the effective clamping gap between the jaws so that the present invention can be used to clamp thicker workpieces. 
   Clamping jaws include a wide variety of designs. For example, a threaded rod with a fixed clamping pad, a threaded rod with a swivel clamping pad to clamp workpiece with inclined or curved surface so that the clamping pad will sit properly on the surface; a threaded rod with rubber clamping pad for workpieces of smooth and slippery surfaces; a clamping jaw with longer threaded rod for step-over clamping and easy adjustment of the clamping gap to suit various thicknesses of workpieces; and a yoke assembly to clamp two workpieces together and to fix them at the desired spatial relationship; etc. 
   Different types of accessories can be attached with screws to the present invention for particular applications. For example, a V-pad for clamping cylindrical workpieces; a 90 degree V-angle bracket for joining two cylindrical workpieces at 90 degree relationship; a 90 degree L-angle bracket for joining two rectangular workpieces at 90 degree relationship; a 180 degree V-angle bracket to join two cylindrical workpieces in-line; a 180 degree L-angle bracket for holding two rectangular workpieces in-line; a L-shape link to join two pieces of the present invention together to clamp more workpieces at the same time; and a L-shape clamping arm with round tip for regular grip; etc. 
   A cylindrical hole is made perpendicular to the axis of the adjustment screw for inserting a metal rod or a screwdriver to increase the turning torque of the adjustment screw. For some application, when a workpiece is clamped with the present invention, a greater clamping force may be required. Under clamping condition, turning the adjustment screw further by fingers will increase the clamping force to a certain degree. However, the turning torque may not be strong enough to achieve the desired clamping force, then the inserted screwdriver will help in this situation. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the present invention with the fixed arm and the movable arm extended, attaching a threaded rod with swivel clamping pad and a threaded rod with fixed clamping pad respectively; 
       FIG. 2  is a perspective view of the present invention clamping two workpieces, and a screwdriver inserted into the hole of the adjustment screw; 
       FIG. 3  is a perspective view of part of the fixed arm attaching a threaded rod with swivel clamping pad; 
       FIG. 4  is a perspective view of the yoke assembly; 
       FIG. 5  is a perspective view of the support bar; 
       FIG. 6  is a perspective view of the present invention with both the fixed arm and the movable arm retracted and mounted with the yoke assembly and support bar respectively; 
       FIG. 7  is a perspective view of part of the present invention clamping two workpieces between the yoke assembly and the support bar at a particular spatial relationship; 
       FIG. 8  is a perspective view of part of the present invention clamping two workpieces between the yoke assembly and the 90 degree L-angle bracket at 90 degree relationship; 
       FIG. 9  shows a number of the possible designs of clamping jaws and accessories, for example, the V-pad, the L-shape links, the 180 degree V-angle bracket, the 90 degree V-angle bracket, the 180 degree L-angle bracket, and the 90 degree L-angle bracket; 
       FIG. 10  is a perspective view of the present invention clamping two cylindrical pipes in-line between the V-pad and the 180 degree V-angle bracket; 
       FIG. 11  is a perspective view of the L-shape clamping arm with round tip; 
       FIG. 12  is a side elevation of the L-shape clamping arm with round tip; 
       FIG. 13  is a cross-sectional view of the area cut along  13 — 13  of  FIG. 12 ; 
       FIG. 14  is a perspective view of the slip-on jaw; 
       FIG. 15  is a perspective view of the slip-on jaw slipped on the round tip of the L-shape clamping arm; and 
       FIG. 16  is a perspective view of the L-shape clamping arms attached to the fixed arm and the movable arm by screws. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With the help of the drawings and the detail description below, the features of the present invention will be apparent and fully understandable. 
   Referring to  FIG. 1 , the present invention comprises a fixed handle  1  to which a L-shape extendable fixed arm  2  is attached and a movable handle  3  to which a L-shape extendable movable arm  4  is pivotally mounted. The fixed handle  1  is connected to the movable handle  3  with the toggling linkage mechanism  5  and the L-shape extendable movable arm  4  through pivots and spring the same way as a conventional locking plier. The free end of the fixed handle  1  is cylindrical in shape and threaded internally to accept the adjustment screw  6  for the adjustment of the clamping gap and clamping force of the present invention. Cylindrical hole  7  is made perpendicular to the axis of the adjustment screw  6  so that a screwdriver  24  or any metal rod of the proper size can be inserted, as shown in  FIG. 2  to increase the turning torque when a greater clamping force is required. The L-shape extendable fixed arm  2  comprises an upper L-shape metal shank  8 , a first upper straight shank  9  with inverted U-shape cross section riveted to the free end of the upper L-shape metal shank  8 , and a second upper straight shank  10  made of solid metal inserted into the first upper straight shank  9 . The second upper straight shank  10 , similar in length as and slidable inside the first upper straight shank  9 , is fixed at a plurality of positions with screws and nuts  15  through a plurality of holes on the bodies of both the first upper straight shank  9  and the second upper straight shank  10 . The L-shape extendable movable arm  4  comprises a lower L-shape metal shank  11 , a first lower straight shank  12  with U-shape cross section riveted to the free end of the lower L-shape metal shank  11 , and a second lower straight shank  14  made of solid metal inserted into the first lower straight shank  12 . The second lower straight shank  14 , similar in length as and slidable inside the first lower straight shank  12 , is fixed at a plurality of positions with screws and nuts  16  through a plurality of holes on the bodies of both the first lower straight shank  12  and the second lower straight shank  14 . The free end of the second upper straight shank  10  is a vertical cylinder and made with a first threaded hole  17  cutting through its centerline to accept various types of clamping jaws, a round swivel clamping pad  19  attaching to a threaded rod  18  as an example shown in  FIG. 1 . The free end of the second lower straight shank  14  is a vertical cylinder and made with a second threaded hole (not shown) cutting through its centerline to accept various types of clamping jaws, a fixed clamping pad  21  attaching to a threaded rod  20  as an example shown in  FIG. 1 . Swivel clamping pad  19 , as shown in  FIG. 1  and  FIG. 3 , is used to clamp workpiece with inclined or curved surface so that the swivel clamping pad  19  will sit properly on the surface. Fixed clamping pad  21  provides a stable platform to support the workpiece. Threaded rods  18  and  20  provide an additional means to adjust the clamping gaps to suit different workpieces.  FIG. 2  shows two workpieces  22  and  23  being clamped between swivel clamping pad  19  and fixed clamping pad  21  (not shown). 
     FIG. 4  shows a yoke assembly  30  and  FIG. 5  shows the support bar  31 . The yoke assembly  30  consists of a horizontal straight metal bar  32  with a vertical threaded hole at each end (not shown). Each threaded hole is inserted a threaded rod  33  and  34  with clamping pads  35  and  36  respectively. The position of each clamping pads,  35  and  36  relative to the metal bar  32  is adjustable by turning the threaded rods  33  and  34  accordingly and can be locked in position by nuts  37 . In the middle of the metal bar  32 , a short threaded rod  38  is hinged. This short threaded rod  38  can be inserted into the first threaded hole  17  of the second upper straight shank  10 . Hence the yoke assembly  30  acts as clamping jaws to clamp workpiece of uneven surface or to clamp two workpieces at the same time. Support bar  31  is a straight metal bar with a recess hole  39  in the middle so that it can be fixed to the second lower straight shank  14  with a screw.  FIG. 6  shows how the yoke assembly  30  is attached to the second upper straight shank  10  and the support bar  31  is attached to the second lower straight shank  14  of the present invention.  FIG. 6  also shows that both the second upper straight shank  10  and the second lower straight shank  14  are set to the retracted position.  FIG. 7  shows how one set of the present invention can be used with the yoke assembly  30  and support bar  31  to clamp two workpieces  41  and  42  at a particular spatial relationship. 
   A wide variety of clamping jaws and accessories can be attached to the present invention to suit various clamping applications. Some examples of the clamping jaws and accessories are shown in  FIG. 9 : a V-pad  51  for clamping cylindrical workpieces; a long L-shape link  52  and a short L-shape link  53  for joining two sets of the present invention to clamp more workpieces together; a 180 degree V-angle bracket  54  for clamping two cylindrical workpieces in-line, as demonstrated by  FIG. 10 , workpieces  71  and  72  are clamped under the V-pad  51 ; a 90 degree V-angle bracket  55  for holding two cylindrical workpieces at 90 degree relationship; a 180 degree L-angle bracket  56  for joining two rectangular workpieces in-line; and a 90 degree L-angle bracket  57  for clamping two rectangular workpieces at 90 degree relationship, as illustrated in  FIG. 8 , workpieces  61  and  62  are clamped under the yoke assembly  30 . 
     FIG. 11  shows the perspective view of another attachment, a L-shape clamping arm  80  with round tip  81  while  FIG. 12  is the side elevation of it. The L-shape clamping arm  80  is a L-shape metal shank with an upper mounting plate  84  and a lower mounting plate  85  located at the middle portion and a locating ear  83  at one end. The other end is a round tip  81  for clamping a workpiece. An elongated hole  86  is equipped at the center of the upper mounting plate  84  and an elongated hole  87  is made at the center of the lower mounting plate  85 . As shown in  FIG. 16 , one L-shape clamping arm  80  is mounted to the second upper straight shank  10  inserted between the upper mounting plate  84 , lower mounting plate  85  and locating ear  83  with screw  93 ; similarly, another L-shape clamping arm  80  is mounted to the second lower straight shank  14  with screw  94 . With such an arrangement, the present invention is converted to a locking plier with round clamping tips and the effective length of both the fixed arm  2  and the movable arm  4  are further extended. To further enhance the flexibility of the present invention, the round tip  81  of the L-shape clamping arm  80  is equipped with two steel balls  82 , one on each side of the round tip  81 , as shown on  FIG. 11  and  FIG. 12 . The steel balls  82  are spring loaded internally by helical spring  88  as shown on the cross-sectional view  FIG. 13 . Circular flanges  89  are formed on each side of the round tip  81  to retain the steel balls  82  in position.  FIG. 14  is a slip-on jaw  91  which can easily be slipped onto the steel balls  82  and kept in position with two elongated holes  92 , as shown in  FIG. 15 .  FIG. 16  shows two sets of the L-shape clamping arms  80 , one attached to the extended fixed arm  2  and the other one attached to the extended movable arm  4 , both L-shape clamping arms  80  are added with the slip-on jaws  91  to form a locking plier with extra long clamping arms and with swivel flat clamping surfaces.