Abstract:
A force multiplying apparatus employs a pivoting clamping arm motion and then a subsequent linear clamping arm motion. A slotted swing arm and a slotted drive link are pivotably and slidably mounted to a relatively fixed body. A toggling action and coincidental sliding of pivots cause the multiplied closing forces.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates generally to clamps and specifically to a powered, force multiplying apparatus. 
     In the clamping and sheet metal joining industries, it is commonly known to provide a clamping mechanism for temporarily or permanently securing sheets of material. Typically, these traditional clamps are limited to a pivoting movement, a linear movement, or a linear then pivoting movement, when a clamping arm is moved between an open/retracted position to a closed/material engaging position. 
     Examples of traditional clamping arm movement in the rotational manner is disclosed within the following U.S. patents: U.S. Pat. No. 5,171,001 entitled &#34;Sealed Power Clamp&#34;; U.S. Pat. No. 5,165,670 entitled &#34;Retracting Power Clamp&#34;; and U.S. Pat. No. 5,118,088 entitled &#34;Power Clamp&#34;; all of which were invented by the inventor of the present invention. A variety of linear motion clamping arms are disclosed within the following U.S. patents: U.S. Pat. No. 4,574,473 entitled &#34;Self-Attaching Fastener and Apparatus for Securing Same to Sheet Material&#34;; and U.S. Pat. No. 3,730,044 entitled &#34;Fluid Operated Apparatus&#34;; both of which were invented by the inventor of the present invention and are incorporated by reference herewithin. Other clamping devices have been employed such as those disclosed within the following U.S. patents: U.S. Pat. No. 5,193,789 entitled &#34;Automatic Clamping Apparatus&#34; which issued to Tucker; U.S. Pat. No. 4,723,767 entitled &#34;Rotary Powered Linear Actuated Clamp&#34; which issued to McPherson et al.; U.S. Pat. No. 3,599,957 entitled &#34;Cam Wedge Power Swing Away With Guided Arm&#34; which issued to Blaft; and U.S. Pat. No. 3,482,830 entitled &#34;Clamp&#34; which issued to Sendoykas; all of which are incorporated by reference herewithin. While many of these constructions have proven satisfactory, it would be desirable to achieve greater clamping force with less driving force. 
     In accordance with the present invention, the preferred embodiment of a force multiplying apparatus employs a pivoting clamping arm motion and then a subsequent linear clamping arm motion. In another aspect of the present invention, a slotted swing arm and a slotted drive link are pivotably and slidably mounted to a relatively fixed body. In yet another aspect of the present invention, a punch is mounted upon a distal section of the clamping arm for acting in conjunction with a die thereby clinching or otherwise joining sheets of material disposed therebetween. 
     The apparatus of the present invention is advantageous over traditional constructions since the present invention provides the ability to significantly multiply or increase the clamping forces without requiring a corresponding increase in the actuator or driving forces. The present invention force multiplying apparatus additionally achieves a more accurate and secure joint between material sheets due to the final linear motion of the clamping arm. As another advantage, the present invention is extremely durable and reliable by employing more robust and less delicate component parts as compared to many conventional constructions. 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 
     FIG. 1 is a side elevational view showing the preferred embodiment of a force multiplying apparatus of the present invention, disposed in a fully closed or material engaging position; 
     FIG. 1a is a diagrammatic side elevation view showing an alternate embodiment stop employed in the force multiplying apparatus of the present invention; 
     FIG. 2 is a bottom elevational view showing the preferred embodiment apparatus of the present invention, disposed in the fully closed position; 
     FIG. 3 is a side elevational view showing a swing arm employed in the preferred embodiment apparatus of the present invention; 
     FIG. 4 is a side elevational view showing a cam drive link employed in the preferred embodiment apparatus of the present invention; 
     FIG. 5 is a side elevational view showing a pivot slide block employed in the preferred embodiment apparatus of the present invention; 
     FIG. 6 is a side elevational view showing a cam slide block employed in the preferred embodiment apparatus of the present invention; 
     FIG. 7 is a side elevational view showing a rod eye employed in the preferred embodiment apparatus of the present invention; 
     3 
     FIG. 8 is a side elevational view showing a sealed roller bearing employed in the preferred embodiment apparatus of the present invention; 
     FIGS. 9-12 are a series of side elevational views showing the preferred embodiment apparatus of the present invention in differing operational positions. 
     FIG. 13 is a true elevational view showing a die employed in the preferred embodiment apparatus of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, the preferred embodiment of a force multiplying apparatus 21 of the present invention is shown in a fully closed or material engaging position. Apparatus 21 is preferably a five ton clinch-type clamp. Apparatus 21 includes a body 23, a pair of swing arms 25, a punch 27, a pair of cam drive links 29, a piston 31, a piston cylinder 33, a die support 35 and a die 37. Body 23 is a stationary member consisting of a casing 51 and a cover 53. 
     As can best be observed in FIGS. 1-3, swing arms 25 have substantially L-shaped, symmetrical configurations such that only one will be described in detail hereinafter. Swing arm 25 has an elongated linear arm slot 61 and a pivot hole 63. A cylindrical center portion of a pivot pin 65 projects through pivot hole 63. Referring to FIGS. 1, 2 and 5, D-shaped ends of pivot pin 65 are secured within substantially rectangular pivot slide blocks 67. Pivot slide blocks 67 are capable of longitudinal linear movement within a longitudinally oversized receptacle 69 of body 23. 
     Returning to FIGS. 1-3, a cylindrical central portion of a cam slide pin 81 has four, heavy load, sealed roller bearing races 83 located therearound. The inner two of these bearing races 83 are slidably engagable within slot 61 of arm 25. As can be observed in FIGS. 1, 2 and 6, D-shaped ends of cam slide pin 81 are secured within cam slide blocks 85. These cam slide blocks 85 are linearly slidable along an elongated longitudinally oriented channel 87 within body 23. 
     Referring to FIGS. 1, 2 and 4, each symmetrical cam drive link 29 includes a pivot aperture 91 for engagement about pivot pin 65. Cam drive link 29 further includes a camming slot 93 having a longitudinally oriented linear portion 95 joined to an angled portion 97. The outer two bearing races 83 movably engage within camming slot 93 of cam drive link 29. A secondary aperture 99 is provided within a corner of cam drive link 29 for engagement with a cam drive pin 101. A pair of heavy load, sealed roller bearing races 103 are shown engaged upon ends of cam drive pin 101 within FIGS. 1, 2 and 8. Bearing races 103 are linearly movable along a transverse direction (perpendicular to movement of a piston rod 113) within a track defined by a pair of parallel, hardened cam plate fingers 105 disposed along each interior surface of body 23. A vertical stop block 107 transversely projects from body 23 and acts to vertically limit cam drive link 29. An alternate embodiment of a vertical stop block 109 and threaded set screw 110 are shown in FIG. 1a. Screw 110 is adjustable. A lower end of screw 110 abuts against bearing races 103. 
     Referring now to FIGS. 1, 2 and 7, a rod eye 111 has a passageway surrounding the center of cam slide pin 81. Rod eye 111 is threadably engaged upon a distal end of piston rod 113 projecting from piston 31. Piston 31, piston rod 113 and rod eye 111 act as driving members for actuating the swing arm 25. Piston cylinder 33 is of a pneumatically driven variety having an 82.5 millimeter diameter bore and a 180 millimeter stroke. An end cap 121 is also provided. End cap 121 has internal, weld field immune, AC/DC switches and one rear mounted five pin micro connector. Body 23 additionally has a thrust key 123. 
     As is best illustrated in FIG. 1, punch 27 has a threaded mandrel or adjustment screw 131 projecting in alignment therewith. Bore sections 133 of arms 25 securely capture adjustment screw 131 of die 37 therebetween when a pair of locking screws 135, enmeshably spanning between the pair of arms 25, are tightened. Die 37 is coaxially aligned with punch 27 when punch 27 is disposed in the fully closed position. Die 37 is retained to die support 35 by a head of a screw 141 engaging an angled undercut in a side thereof. Punch 27 and die 37 are of the type disclosed within U.S. Patents 5,267,383 entitled &#34;Apparatus for Joining Sheet Material&#34; and 4,459,735 entitled &#34;Joining Sheet Metal&#34;, both of which were invented by the inventor of the present invention and are incorporated by reference herewithin. Die 37 further has a movable set of die blades 211 surrounding a central anvil 213, as is shown in FIG. 13. Accordingly, the sheets of material are joined in the lanced or mushroom-shaped and leakproof manners shown therein. Of course, other material forming members may be attached to the swing arms or support. Furthermore, it is envisioned that the die may be affixed to a separate stationary or movable structure. In an alternate embodiment of the present invention, a material gripping jaw may be fastened to the swing arm and support instead of the aforementioned punch and anvil. 
     The operation of the present invention apparatus 21 can be observed by reference to FIGS. 1 and 9-12. FIG. 9 shows swing arm 25 in a fully open and retracted position. As swing arm 25 moves from the positions of FIG. 9 to that of FIG. 10, cylinder 33 and the piston act to push rod eye 111, cam slide pin 81 and bearing races 83 upward along angled portion 97 of camming slot 93 of cam drive link 29 concurrently with sliding along arm slot 61 of swing arm 25. This acts to move bearing race 103 and cam drive pin 101 in a linear manner along the transverse direction thereby pivoting cam drive link 29. This slight linear piston movement further causes swing arm 25 to significantly pivot away from the open position. 
     As rod eye 111, cam slide pin 81 and bearing races 83 are subsequently moved between the positions of FIGS. 10-11, bearing races 83 further slide along angled portion 97 of camming slot 93 while also riding along arm slot 61. Thus, swing arm 25 has been rotated 80° between the fully opened position of FIG. 9 and an extended, end of rotation position as shown in FIG. 11. Next, referring to the movement between FIGS. 11, 12 and 1, continued movement of rod eye 111, cam slide pin 81 and bearing races 83 cause swing arm 25, and punch 27 mounted upon a distal section thereof, to linearly move approximately ten millimeters in a linear manner opposite that of piston 31 and rod eye 111. As part of this motion, pivot pin 65 and pivot slide block 67 are linearly moved in conjunction with swing arm 25. Bearing race 103, and the adjacent portion of cam drive link 29, concurrently move transversely along track fingers 105. The interaction of track fingers 105 and bearing race 103 limits and forces cam drive link 29 and arm 25 to move linearly, while cam drive link 29 is also pivoting, in response to movement of piston 31 and rod eye 111. Thus, swing arm 25 is first moved in a pivoting manner and subsequently moved in strictly a linear manner thereby multiplying the driving force to create a significantly enhanced clinching and clamping force. The pneumatic cylinder and piston generate approximately 80 psi while the resultant clamping force is approximately 249,000 pounds. 
     While the preferred embodiment of this apparatus has been disclosed, it will be appreciated that various modifications may be made without departing from the present invention. For example, the rod eye may be driven by hydraulic or electric means. Furthermore, a variety of arcuate shaped slots may alternately be provided. The slots may alternately take the form of channels or separate linkages and pins as long as the disclosed motion is achieved. 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.