Abstract:
A swing clamp ( 100 ) for selectively clamping a workpiece ( 58 ) having a surface to be worked upon to a support surface is provided. The swing clamp includes a housing ( 108 ) and an actuator ( 101 ) at least partially disposed within the housing. A clamp arm ( 102 ) is coupled to the actuator, wherein the actuator is adapted to actuate the clamp arm between a clamped position, an unclamped position, and a retracted position in which the clamp arm is adapted to be disposed below an elevation of the surface to be worked upon.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/407,844, filed Aug. 30, 2002, priority from the filing date of which is hereby claimed under 35 U.S.C. § 119 and the disclosure of which is hereby expressly incorporated by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to clamps and, more particularly, to swing clamps selectively actuatable between a clamped position and an unclamped position.  
         BACKGROUND OF THE INVENTION  
         [0003]    Machining operations often require clamps to hold a workpiece stationary during machining operations. Manually operated mechanical clamps have been used in the past for this purpose. More recently, manually controlled, electrical, pneumatic and hydraulically actuated clamps have been developed. While clamps can be electrical or mechanical, most modern clamps are pneumatically or hydraulically actuated. Still more recently, in order to accommodate modem machining operations, programmable clamps have been developed. Programmable clamps are designed for rapid movement between a clamped position and an unclamped position. The actuation of programmable clamps may be controlled by a computer or similar controller to permit the actuation of the clamp between a clamped and unclamped position without direct human intervention. Manual manipulations required by manually operated clamps are avoided, labor costs are reduced, and manufacturing times are decreased.  
           [0004]    Unfortunately, existing manually controlled and programmable clamps are not without their problems. For instance, as a machining device machines a workpiece into a desired shape, the machining device may have to be positioned in or pass through a location occupied by a clamp. In order to avoid conflict, the clamp must be disengaged and displaced from the workpiece to allow access to the area by the machining device, causing significant increases in manufacturing cost and time.  
           [0005]    One previously developed solution to the foregoing disengagement problem is the swing clamp. A swing clamp has a clamp arm that is rotated 90 degrees as the clamp arm is moved from a clamped position to an unclamped position, thereby partially displacing the clamp arm from the workpiece. Thus swing clamps permit some additional access to a work piece in the vicinity of such clamps. However, previously developed swing clamps are not without their problems. For instance, the clamp arms of previously developed swing clamps rise above the workpiece when moving to the unclamped position and rotating by 90 degrees. After rotation, the arms remain raised. This is often undesirable because a machining device having a part or component that extends horizontally outward from the cutting tool of the machining device may impact the raised clamp arm as the machining device works in the vicinity of the workpiece previously engaged by the clamp arm. Thus previously developed swing clamps can interfere with machining operations and potentially cause damage, if the machining device impacts a raised clamp arm.  
           [0006]    Thus there exists a need for a swing clamp having an unclamped position such that no part of the swing clamp will interfere with machining operations in the vicinity of the clamp. Further, a need exists not only for a swing clamp that allows increased access of a machining device to a workpiece in the vicinity of the clamp, but is also economical to manufacture and has a high degree of reliability.  
         SUMMARY OF THE INVENTION  
         [0007]    One embodiment of a swing clamp formed in accordance with the present invention is provided. The swing clamp is adapted to selectively clamp a workpiece having a surface to be worked upon to a support surface. The swing clamp includes a housing and an actuator at least partially disposed within the housing. A clamp arm is coupled to the actuator, wherein the actuator is adapted to actuate the clamp arm between a clamped position, an unclamped position, and a retracted position. In the retracted position, the clamp arm is adapted to be disposed below an elevation of the surface to be worked upon.  
           [0008]    Another embodiment of a swing clamp formed in accordance with the present invention is provided. The swing clamp is adapted to selectively clamp a workpiece having a surface to be worked upon to a support surface. The swing clamp includes a housing and an actuator at least partially disposed within the housing. A clamp arm is coupled to the actuator, the clamp arm having at least a first arm and a second arm. Each arm is adapted to alternately engage and clamp the workpiece. The actuator is adapted to configure the clamp arm between a first clamped position in which the first arm is adapted to clamp the workpiece to the support surface, a second clamped position in which the second arm is adapted to clamp the workpiece to the support surface, and an unclamped position.  
           [0009]    Still another embodiment of a swing clamp formed in accordance with the present invention is provided. The swing clamp is adapted to selectively clamp a workpiece having a surface to be worked upon to a support surface. The swing clamp includes a housing and an actuator at least partially disposed within the housing. A clamp arm is coupled to the actuator. A cam assembly is disposed at least partially within the housing. The cam assembly includes a branched cam having a first portion which branches to at least a first branch and a second branch. The cam assembly also includes a cam follower adapted to interface with the branched cam to guide the actuation of the clamp arm between a first position and a second position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0011]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0012]    [0012]FIG. 1 is an elevation view of one embodiment of a swing clamp formed in accordance with the present invention, wherein a cam-rod and attached clamp arm of the swing clamp are shown in a clamped position holding a workpiece stationary upon a work table as the workpiece is machined by a machining device; FIG. 2 is an elevation view of a portion of FIG. 1 showing the cam-rod and attached clamp arm of the swing clamp in an unclamped position, the clamp arm being displaced above the workpiece;  
         [0013]    [0013]FIG. 3 is an elevation view of a portion of FIG. 1 showing the cam-rod and attached clamp arm of the swing clamp in a retracted position such that the clamp arm has been displaced away from and below the upper surface of the workpiece being machined, thereby eliminating the possibility of interference between the clamp arm and the machining device;  
         [0014]    [0014]FIG. 4 is a cross-sectional view of one embodiment of a swing clamp formed in accordance with the present invention, taken substantially along line  4 - 4  of FIG. 5, the cam-rod and attached clamp arm shown in an unclamped position;  
         [0015]    [0015]FIG. 5 is a top view of the swing clamp depicted in FIG. 4;  
         [0016]    [0016]FIG. 6 is a cross-sectional view of the swing clamp depicted in FIG. 4 taken substantially along line  6 - 6  of FIG. 7, the cam-rod and attached clamp shown in a retracted position;  
         [0017]    [0017]FIG. 7 is a top view of the swing clamp depicted in FIG. 6;  
         [0018]    [0018]FIG. 8 is an elevation view of one embodiment of a cam-rod formed in accordance with the present invention suitable for use in the swing clamp shown in FIGS.  1 - 7 ;  
         [0019]    [0019]FIG. 9 is a flat representation of the outer surface of a lower cylindrical portion of the cam-rod shown in FIG. 8, depicting a configuration of a cam groove network formed on the surface of the low cylindrical portion of the cam-rod; and  
         [0020]    [0020]FIG. 10 is a top view of the cam-rod shown in FIG. 8. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    Referring to FIGS.  1 - 7 , one embodiment of a swing clamp  100  formed in accordance with the present invention is shown. Although the illustrated embodiment of the present invention will be described as a swing clamp for use in holding down a workpiece during a manufacturing process, those skilled in the relevant art and others will appreciate that the disclosed swing clamp  100  is illustrative in nature and should not be construed as limited to application as a workpiece holdown clamp. As those skilled in the art and others will appreciate further, the swing clamp  100  has wide application and may be used in any situation where the application of a clamping pressure is desirable. It should be noted that for purposes of this disclosure, terms, such as “upper,” “lower,” “vertical,” and “horizontal,” should be construed as descriptive and not limiting.  
         [0022]    [0022]FIG. 1 is an environmental view showing the swing clamp  100  in relation to an exemplary machining device  50 . The exemplary machining device  50  is a router  60  having a cutting tool  52 . In FIG. 1, the cutting tool  52  is shown in cutting engagement with a workpiece  58 . The workpiece  58  includes a plurality of thin sheets of metal, oriented in a stacked relationship upon a sacrificial sheet  56 . The sacrificial sheet  56  is supported by a support surface or work table  54 . The machine device  50  is selectively programmable to control the movement of the router  60  over the workpiece  58  to cut the workpiece  58  into a desired shape. The alignment of the multiple sheets of the workpiece  58  is maintained by the swing clamp. More specifically, the swing clamp  100  includes a clamp arm  102  that applies a downward clamping force to the workpiece  58 , thereby compressing the workpiece  58  between the work table  54  and the clamp arm  102 . (In an actual machine, a plurality of swing clamps would be located around the periphery of the work piece  58 .)  
         [0023]    The clamped and unclamped positioning of the clamp arm  102  is controlled by a well known controller (not shown) coupled to an actuation system  101  (shown in one form in FIGS.  4 - 9  and described below) housed within a housing or cylinder  108  that forms part of the swing clamp  100 . The controller (not shown) selectively energizes the actuation system, such as by applying a pressurized fluid, a current, etc. to the actuation system. The controller may include a computer or similar device, or may include a manually operable device, such as a valve, for selectively energizing the actuation system. A cam-rod  104  couples the clamp arm  102  to the actuation system  101  (See FIG. 4) housed within the cylinder portion  108  of the swing clamp  100 .  
         [0024]    The swing clamp  100  is programmable to actuate the cam-rod  104  and attached clamp arm  102  between three positions: a clamped position shown in FIG. 1, an unclamped position shown in FIG. 2, and a retracted position shown in FIG. 3. With the cam-rod  104  and attached clamp arm  102  in the unclamped position shown in FIG. 2, the clamp force is removed from the workpiece  58 , allowing the workpiece to be repositioned or removed from the work table  54 . The unclamped position is a precursor to positioning the cam-rod  104  and attached clamp arm  102  in the retracted position.  
         [0025]    Referring to FIG. 3, in the retracted position, the cam-rod and attached clamp arm  102  are displaced below a top surface of the workpiece  58 , and more specifically, preferably below the workpiece  58 , below the sacrificial sheet  56 , and flush or below the upper surface of the work table  54 . This positioning removes the clamp arm  102  from potential interference with the machining device  50 , allowing the machining device  50  to work in the vicinity of the swing clamp  100  without interference or damage. Although in the illustrated embodiment depicted in FIGS.  1 - 3 , only a single swing clamp  100  is shown, as briefly noted above, those skilled in the art and others will readily understand that a plurality of swing clamps would typically be used to hold down a workpiece  58 . In such machines, when the machining device  50  approaches a particular swing clamp  100 , the swing clamp would be actuated such that the clamp arm is moved into the retracted position. Once the machining device  50  has vacated the vicinity of the swing clamp  100 , the swing clamp  100  may be actuated to move the clamp arm into the clamped position.  
         [0026]    Keeping in mind the above general overview of the swing clamp  100 , the following description will focus on the structural components of the swing clamp  100 . FIGS. 4 and 5 illustrate the cam-rod  104  and attached clamp arm  102  of the swing clamp  100  in an unclamped position. The cam-rod  104  is movable between clamped, unclamped, and retracted positions by an actuation system  101  housed within the cylinder  108  of the swing clamp  100 . As best shown in FIG. 8, the cam-rod  104  comprises an upper shaft  162  axially aligned and coupled to a lower cam groove cylinder  164 . Two mounting flats  168  are machined on opposite sides of an upper distal end  166  of the upper shaft  162  in a parallel arrangement. Referring to FIGS. 4, 5, and  8 , bored perpendicularly through the mounting flats  168  is a bore  106  for accepting a well-known fastener  158  (FIG. 4). The mounting flats  168 , in combination with the fastener  158 , facilitate the attachment of the clamp arm  102  to the cam-rod  104 . Disposed between the upper distal end  166  of the upper shaft  162  and the lower cam groove cylinder  164  is an annular groove  160 . The annular groove  160  is radially disposed around the upper shaft  162  and is configured to receive a retaining ring  136  (FIG. 4), such as an E-clip. The retaining ring  136  serves to impede the upward movement of a piston  170  slidingly mounted on the upper shaft  162 , thereby retaining the piston  170  between the retaining ring  136  and a shoulder  174  of the cam groove cylinder  164 .  
         [0027]    Still referring to FIGS. 4, 5, and  8 , the cam groove cylinder  164  is concentrically aligned with the upper shaft  162 . The cam groove cylinder  164  has a cam groove network  172  disposed on its outer surface. The purpose and operation of the cam groove network  172  will be discussed in further detail below. The diameter of the cam groove cylinder  164  is greater than the diameter of the upper shaft  162 , thereby creating the shoulder  174  at the interface of the upper shaft  162  with the cam groove cylinder  164 .  
         [0028]    Referring to FIG. 4, the shoulder  174  provides a support surface for a thrust bearing  128 . The thrust bearing  128  is comprised of an upper annular race  130  spaced from a lower annular lower race  132 . Disposed between the annular races is a plurality of ball bearings  134 . The ball bearings  134  allow a compression force (thrust) to be absorbed by the annular races  130  and  132  while still permitting the rotation of the upper annular race  130  relative to the lower annular race  132 . The lower race  132  engages the shoulder  174  of the cam groove cylinder  164 . The upper race  130  engages the piston  170 . This arrangement allows the thrust bearing  128  to enhance the rotational freedom of the piston  170  relative to the upper shaft  162  during loading of the piston in a downward direction.  
         [0029]    The piston  170  will now be described in further detail. The piston  170  is a disc-shaped member having an inner aperture  176  having a diameter sized to rotatingly receive the upper shaft  162 . The outer diameter  178  of the piston is selected to be reciprocatingly received by an upper cylinder bore  126  of the cylinder  108 . Disposed on the outer cylindrical surface of the piston  170  is an annular groove for receiving an O-ring  144 . The O-ring  144  substantially seals the outer cylindrical surface of the piston  170  with the inner cylindrical wall of the upper cylinder bore  126 . The piston  170  is coupled to the upper shaft  162  by the interaction of the retaining ring  136  upon a washer  138  disposed in an annular recess in the upper portion of the piston  170  and the thrust bearing  128  in combination with the shoulder  174  of the cam groove cylinder  164 . Thus the piston  170  is impeded from longitudinal movement along the axis of the cam-rod  104  by sandwiching the piston  170  between the retaining ring  136  and washer  138  on the upper side, and on the lower side, between the shoulder  174  of the cam groove cylinder  164  and the thrust bearing  128 .  
         [0030]    The cylinder  108  will now be described in further detail. The cylinder  108  is cylindrical in shape, preferably having a constant outer diameter. The cylinder  108  houses a lower cylinder bore  116  of a first diameter and an upper cylinder bore  126  of a greater second diameter. The lower cylinder bore  116  is sized to reciprocatingly receive the cam groove cylinder  164 . The upper cylinder bore  126  is sized to reciprocatingly receive the piston  170 . In fluid communication with the lower cylinder bore  116  is an extender port  118 . The extender port  118  couples a pressurizable fluid line (not shown) with the lower cylinder bore  116 , to permit the selective pressurization of the lower cylinder bore  116 . A retractor port  120  located in the upper portion of the cylinder  108  couples a pressurizable fluid line (also not shown) to the upper cylinder bore  126  to permit the selective pressurization of the upper cylinder bore  126 . The extender port  118  and retractor port  120  are located such that pressurized fluid in their respective bores can be discharged as the other bore is pressurized. The cam-rod  104  is moved in an upward direction by injecting a pressurized fluid through the extender port  118 . The pressurized fluid applies a force to the bottom surface of the piston  170  which causes upward movement of the cam-rod  104 . Downward movement of the cam-rod  104  is created by applying a pressurized fluid to the retractor port  120 . The pressured fluid applies a force to the top surface of the piston  170  which causes downward movement of the cam-rod  104 . While the preferred pressurized fluid is air, it will be apparent to those skilled in the art and others that other actuating fluids, such as hydraulic oil, can be used. Further, other actuating devices, such as electrical solenoid actuating devices, can be used and fall within the scope of the present invention.  
         [0031]    The cylinder  108  further includes a cam follower passageway  112  radially bored through a wall of the cylinder  108 . Disposed within the cam follower passageway  112  is a cam follower  110 . The cam follower  110  is comprised of a rod sized to slidably fit within the cam follower passageway  112 . Preferably, the cam follower  110  is constructed from a hardened, high-strength material. Abutting the outer distal end of the cam follower  110  is a cam follower retainer  114 . The cam follower retainer  114  acts as a plug to prevent the backing out of the cam follower  110  from the cam follower passageway  112 .  
         [0032]    Inserted within the upper end of lower cylindrical bore  116  of the cylinder  108  is a lower bushing  122 . The lower bushing is sized to reciprocatingly receive the cam groove cylinder  164 . The lower bushing  122  serves to maintain the axial alignment of the cam-rod  104  during operation. More specifically, as an upward force is exerted upon one side of the double-sided clamp arm  102  during clamping operations, a large moment is exerted upon the cam-rod  104 , tending to misalign the cam-rod  104 . The lower bushing  122 , in coordination with an upper bushing  124  (described in detail below), counteract the large moment forces exerted upon the cam-rod  104 , thereby maintaining the axial alignment of the cam-rod  104 .  
         [0033]    The swing clamp  100  also includes a cylinder head  148 . The cylinder head  148  is constructed to mate with the cylinder  108  and seal the open end of the cylinder  108 , thereby creating a pressure vessel defined by the upper cylinder bore  126  and the lower cylinder bore  116 . To aid in the maintaining of pressure within the upper cylinder bore  126  and the lower cylinder bore  116 , an O-ring  142  is located between the cylinder  108  and the cylinder head  148 . The upper shaft  162  of the cam-rod  104  passes through a bore  179  concentrically machined in the cylinder head  148 .  
         [0034]    Mounted within the bore  179  is the upper bushing  124 . The upper bushing  124  is configured to reciprocatingly receive the upper shaft  162  of the cam-rod  104 . Disposed within an annual groove radially formed on the upper bushing  124  is an O-ring  140 . The O-ring  140  aids in the prevention of blow-by, thereby preventing pressurized air injected through the retractor port  120  from escaping from the upper cylinder bore  126  while simultaneously impeding the entrance of contaminates into the cylinder  108 . The upper bushing  124 , as described above, aids in maintaining the axial alignment of the cam-rod  104 .  
         [0035]    Referring to FIGS. 6 and 7, machined in the upper portion of the cylinder head  148  is a clamp arm recess  152  and a clamp arm base recess  150 . The clamp arm recess  152  is sized with sufficient width, length, and depth to receive the clamp arm  102 . The clamp arm base recess  150 , which is circular in shape, is sized with a sufficient diameter and depth to receive the clamp arm base  154  therein. Thus when the cam-rod  104  is positioned in the retracted position, the clamp arm  102  is fully retracted within the cylinder head  148  thereby providing maximum clearance for machining devices operating on the work piece  58 .  
         [0036]    Referring to FIGS. 6 and 7, the cylinder head  148  is mounted to the cylinder  108  by well known fasteners  214 . Likewise, the cylinder head  148  is mounted to the work table  54  by well know fasteners  216 . Although the swing clamp  100  of the illustrated embodiment of the present invention is depicted with a specific mounting system, it should be apparent to one skilled in the art that any number of methods of mounting the swing clamp to a work table  54  may be employed. For instance, the cylinder head  148  or the cylinder  108  may include a threaded portion for removably mounting the swing clamp  100  to a mounting aperture in the work table  54  having reciprocal threads machined therein. Further still, although the illustrated embodiment is depicted as mounted to the work table  54 , it should be apparent to one skilled in the art that the swing clamp  100  may be mounted to any structure to best accommodate the desired machining operations. For example, the swing clamp  100  may be mounted to a holding structure, examples of such structures often referred to as “tombstones” or “pallets” in the trade, which is then set and rigidly held upon the work table  54 .  
         [0037]    Referring to FIGS. 4 and 8- 10 , the cam groove network  172  disposed on the cam groove cylinder  164  will now be described in further detail. The cam groove network  172  is comprised of a plurality of interconnected grooves machined into the outer surface of the cam groove cylinder  164 . Generally stated, the shape of the grooves forming the cam groove network  172  controls the orientation of the clamp arm  102  in relation to the workpiece. The width of the grooves of the cam groove network  172  is selected to slidingly receive the inner distal end  180  of the cam follower  110 . The depth of the grooves of the cam groove network  172  is selected to provide sufficient strength to prevent the deformation of the grooves of the cam groove network  172  when engaged with the cam follower  110 . The cam groove network  172  includes four branched cam grooves  181 A,  181 B,  182 C, and  181 D. Each branched cam groove  181  includes a longitudinal segment  182 A,  182 B,  182 C, or  182 D oriented vertically and at 90 degree intervals about the circumference of the cam groove cylinder  164 . Each longitudinal segment  182 A,  182 B,  182 C, and  182 D is substantially linear in shape and terminates in a branched segment  184 A,  184 B,  184 C, and  184 D. The four longitudinal segments  182 A,  182 B,  182 C, and  182 D guide the cam-rod  104  during vertical, linear movement, while the branched segments  184 A,  184 B,  184 C, and  184 D guide the cam-rod  104  during a vertical and rotational phase of cam-rod  104  movement. The branched segments  184  are accordingly substantially arcuate in shape.  
         [0038]    Each branched segment  184 A,  184 B,  184 C, and  184 D has two branch portions. Each branch may be classified by its degree of rotation and direction of intended travel. More specifically, each branch is oriented to initiate either a 30-degree or a 60-degree rotation of the cam-rod  104 . Further, each branch is tracked by the cam follower  110  during the upward movement of the cam-rod  104  or the downward movement of the cam-rod  104  exclusively. Using the above designations, the classification of each branch will be noted as one travels from left to right of FIG. 9. The right branch  192 A of branched segment  184 A is a downward movement, 60-degree rotation branch. The left branch  192 B of branched segment  184 B is an upward movement, 30 degree rotation branch while the right branch  192 C is a downward movement, 30 degree rotation branch. The left branch  192 D of branched segment  184 C is an upward movement, 60-degree rotation branch, while the right branch  192 E is a downward movement, 60-degree rotation branch. The left branch  192 F of branched segment  184 D is an upward movement, 30-degree rotation branch, while the right branch  192 G is a downward movement, 30-degree rotation branch. The left branch of branched segment  184 A is an upward movement, 60-degree rotation branch.  
         [0039]    The movement of the cam-rod  104  during operation will now be discussed in further detail. For purposes of this detailed description, the discussion of the movement of the cam-rod  104  will begin with the cam follower  110  located within the grooves of the cam groove network  172  at a starting position indicated by reference numeral  194 . Of note, reference numeral  194  represents the position of the cam follower  110  at a point in time when the cam-rod  104  is located at an unclamped position, i.e. a Top Dead Center (TDC) position, with the clamp arm rotated 30 degrees counterclockwise (when viewed from above) from alignment with an imaginary line extending normal from an edge of the work table. As the cam-rod  104  is actuated vertically downward from this position, the cam follower  110  slides within branch  192 B. Of note, the cam follower  110  does not reenter branch  192 A since the vertically oriented momentum of the cam-rod  104  carries the cam-rod  104  past branch  192 A. In addition, the rotational friction induced by bushings  122  and  124 , O-rings  140  and  146 , piston  170 , and thrust bearing  128 , albeit minimal, upon the cam-rod  104  impede the cam-rod  104  from rotating, thus preventing the cam follower  110  from reentering branch  192 A.  
         [0040]    Once the cam follower  110  enters branch  192 B, due to the arcuate shape of branch  192 B, the cam-rod  104  and attached clamp arm  102  are rotated 30 degrees clockwise so as to align the clamp arm  102  with the imaginary line extending normal from the work table. As the cam follower  110  enters and rides within the longitudinal segment  182 B, the clamp arm  102  reciprocates vertically downward upon the workpiece, engaging the workpiece and applying a clamping force upon the workpiece. With the cam-rod  104  in the fully clamped position, the location of the cam follower  110  is indicated by reference numeral  196 . As should be apparent to one skilled in the art, the vertical position of reference numeral  196  along the longitudinal segment  182 B is determined by the thickness of the workpiece.  
         [0041]    As the cam-rod  104  is actuated upward to release the workpiece from the clamping force, the cam-follower  110  slides within the longitudinal segment  182 B, therein entering branch  192 C. Due to the arcuate shape of branch  192 C, the cam-rod  104  and attached clamp arm  102  are rotated 30 degrees clockwise so as to rotate the clamp arm  102  30 degrees clockwise from the imaginary line extending normal from the work table. The cam-rod  104  and attached clamp arm  102  are now positioned in the unclamped TDC position. The position of the cam follower at TDC is indicated by reference numeral  198 . As the cam-rod  104  is actuated downward from TDC, the cam follower  110  enters branch  192 D. Due to the arcuate shape of branch  192 D, the cam-rod  104  and attached clamp arm  102  are rotated 60 degrees clockwise, orienting the clamp arm  102  perpendicularly to the imaginary line extending normal from the work table. As the cam follower enters and rides within the longitudinal segment  182 C, the clamp arm  102  reciprocates vertically downward until recessed within the cylinder head  148 . In this position, the cam-rod  104  and attached clamp arm  102  are displaced below the top surface of the workpiece, thus eliminating the possibility of the cam-rod  104  and attached clamp arm  102  from interfering with the movement of the machining device. Reference numeral  200  indicates the position of the cam follower  110  when the cam-rod  104  reaches the fully retracted position, i.e. Bottom Dead Center (BDC) position.  
         [0042]    As the cam-rod  104  is actuated upward from the BDC position, the cam-follower  110  slides within the longitudinal segment  182 C from the position of the cam-follower  110  indicated by reference numeral  200 , and enters branch  192 E. Due to the arcuate shape of branch  192 E, the cam-rod  104  and attached clamp arm  102  are rotated 60 degrees clockwise so as to rotate the clamp arm  102  30 degrees clockwise from the imaginary line extending normal to the work table. The position of the cam follower at TDC is indicated by reference numeral  202 . As the cam-rod  104  is actuated downward from TDC, the cam follower  110  enters branch  192 F. The motion of the cam-rod  104  and attached clamp arm  102  as the cam follower  110  travels through branch  192 F and the remaining portion of the cam groove network  172  is identical to the motion described above for the first half of the cam groove network  172 . Therefore, the motion of the cam follower through the second half of the cam groove network  172  will be omitted for brevity.  
         [0043]    Although specific degrees of angular displacement are described relative to each branch  192 , it should be apparent to one skilled in the art that other angular displacements may be associated with each branch  192 . For instance, each branch may initiate a 45-degree rotation of the cam-rod  104 . Or each branch may initiate a 90 degree rotation or other selected angular displacement such that the clamp arm rotates 360 degrees in one direction when the clamp arm is actuated from the clamped position to the unclamped position, to the retracted position, to the unclamped position, and back to the unclamped position. Thus, as should be apparent to those skilled in the art, in this configuration, only two branched cam grooves  181  are required. Further, although the orientation of the cam groove network  172  of the illustrated embodiment causes the cam-rod  104  to rotate in a clockwise direction when viewed from above, it should be apparent to one skilled in the art that by forming a cam groove cylinder  164  having a mirror image of the cam groove network  172  of the illustrated embodiment formed thereon, the cam-rod  104  may be directed in a counterclockwise direction. Further still, although the illustrated embodiment depicts a cam groove network  172  having four branched cam grooves  181 , it should be apparent to one skilled in the art that a cam groove network  172  having any number of branched cam grooves  181 , such as two, is suitable for use, and thus falls within the scope of the present invention.  
         [0044]    Further still, although the above described embodiment depicts a cam assembly using a cam groove network  172  disposed upon the cam groove cylinder  164 , with a cam follower  110  coupled to the cylinder  108 , it should be apparent to those skilled in the art that this arrangement may be reversed. Moreover, it should be apparent to those skilled in the art that the cam follower  110  may be disposed upon the cam groove cylinder  164  and the cam groove network  172  disposed upon the cylinder  108 . Further, although the illustrated embodiment depicts a cam follower engaging a groove, it should be apparent that any type of cams and cam followers are suitable for use with and are within the spirit and scope of the present invention. For instance, the cam may be a rib which extends outward from the cam groove cylinder  164 , engaging a u-shaped cam follower coupled to the cylinder  108 .  
         [0045]    While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.