Patent Publication Number: US-3877181-A

Title: Clamping assembly

Description:
i United States Patent [191 Dunn [ CLAMPING ASSEMBLY [75] Inventor: Elman R. Dunn, Roscoe, Ill.  
 [73] Assignee: Litton Industries, Inc., Beverly Hills,  
 Calif.  
 [22] Filed: Feb. 6, 1974 [21] Appl. No.: 440,169  
 Primary Examiner-Roy Lake Assistant ExaminerNeil Abrams Attorney, Agent, or FirmSpencer T. Smith [57] ABSTRACT A clamping assembly for clamping a workpiece stack having at least three rectanguloid workpieces in a V- block or the like comprising a clamp arm, a clamp head pivotally secured to the clamp arm, means for displacing the clamp arm from an unclamped position [451 Apr. 15, 1975 to a clamped position, the clamp head including a body portion, side plates adapted to be secured to opposing sides of the body portion, a first body opening, a rear clamp pin adapted to be located within the first body opening, means for mounting the rear clamp pin on the side plates for eccentric rotation and limited lengthwise tilting, the rear clamp pin including a bearing for engaging the rear surface of the workpiece stack and being selectively configured to permit lengthwise tilting and limited eccentric rotation, a second body opening, at least three lower clamp pins, means for mounting each of the three lower clamp pins on the side plates for eccentric rotation and limited lengthwise tilting, each of the lower clamp pins including cylindrical end portions having a bearing surface for engaging the top surface of a corresponding workpiece and the workpiece stack, a pair of center pins including cylindrical end portions having a bearing surface of selected width to permit engagement with the cylindrical end portions of an adjacent pair of lower clamp pins, an upper pin including cylindrical end portions having a bearing surface of selected width to permit engagement with the cylindrical end portions of the pair of center pins and being selectively configured to permit limited lengthwise tilting, the second opening being selectively configured to receive the lower, center and upper pins, whereby when the clamp assembly is closed upon a workpiece stack equal pressure will be applied to the engaged surfaces of the workpiece stack.  
 1 Claim, 4 Drawing Figures PATENTEB I 5i975 3,877? l 81 mmmfz CLAMPING ASSEMBLY This invention relates to clamping fixtures for effectively clamping and aligning a stack of nearly alike workpieces, to enable precision grinding of the end surfaces thereof.  
  Previous practice in grinding such workpiece ends has been to clamp and grind one piece at a time, or to clamp several workpieces together wherein a soft cushioning element is utilized to encourage equal clamping effect upon the edges of all workpieces in the stack. Obviously single workpiece grinding is a slower and hence not desirable method. On the other hand, stack precision grinding as with a soft cushioning element in the clamping system has never been satisfactory because such a system does not assure that equal clamping pressure will be applied to all workpieces of the stack. Unless all workpieces in a given stack are clamped assuredly alike, it follows that there will be non-uniform geometric accuracies present in the ground surfaces. when comparing one workpiece with others from the same stack.  
  It is accordingly an object of the present invention to provide a clamping assembly which will assuredly subject each workpiece of a workpiece stack to equal clamping pressure along its edges and sides so that all workpieces from the stack will have uniform geometric accuracies in the ground surfaces thereof.  
  Other objects and advantages of the present invention will become apparent from the following portion of this specification and from the accompanying drawings which illustrate in accordance with the mandate of the patent statutes, a presently preferred embodiment incorporating the principles of the invention.  
 Referring to the drawings:  
  FIG. 1 is a front oblique view of a horizontal double disc grinder having a clamping assembly constructed in accordance with the teachings ofthe present invention;  
  FIG. 2 is an enlarged elevational view partially broken away of the clamping assembly illustrated in FIG. 1;  
  FIG. 3 is an enlarged view of the clamp head of the clamping assembly illustrated in FIG. 2; and  
  FIG. 4 is an oblique view of the triangular array of clamp pins of the clamp assembly illustrated in FIG. 3.  
  A horizontal double disc grinding machine is illustrated in FIGS. 1 and 2 and includes left-hand and right-hand abrasive discs l2, 14 each having a central axially extending bore (not shown). The abrasive discs are rotatably mounted on a pair of slides 16 which are longitudinally displaceable for incremental infeed along a machine bed 18 to compensate for normal wheel wear.  
  The base 19 ofthe clamping assembly 20 is rigidly secured via a suitable fixture 21 to a gun type slide bar 22, which is journaled in spaced bearings (not shown) of the spindle housing 28. The spindle housing is mounted on a rigid base member which provides a vibration free support for the gun type slide bar 22. Axial displacement of the gun type slide bar 22 is controlled by a hydraulic motor or cylinder (not shown) in a conventional manner.  
  The clamp assembly additionally includes a two piece clamp handle 32, a clamp arm 34 and a clamp head 36. The clamp base 19 includes an axially extending slot 38 at the top thereof which is selectively configured to permit rotative displacement of the clamp arm 34,  
 which is pivotally secured at a pivot connection 40 to a pair of spaced, opposing upwardly extending posts 42, which define the forward portion of the slot, from a clamped position to an unclamped position illustrated in broken lines in FIG. 2. A leaf spring 44 biases the clamp arm in a counterclockwise direction towards the unclamped position.  
  Both arms of the two piece clamp handle 32 are pivotally, externally secured, at a suitable pivot connec tion 46, to the clamp base 19 and are fixedly joined together at the other or free end by connecting pins 48. A roller is rotatably secured at a horizontal orientation to the interior surfaces of the clamp handle arms so that the roller will engage the bottom surface 52 of the clamp arm. A portion 54 of each of the opposing side walls of the slot are cut away to permit free rotative displacement of the clamp handle from the clamped position to the unclamped position. Counterclockwise displacement of the clamp handle 32 is limited by the stop portion 56 of the clamp arm 34, which extends downwardly from the left-hand end of the clamp and which engages the roller 50 when the clamp handle is displaced to the clamped position and clockwise rotation of the clamp handle is limited by the selectively located side walls of the upstanding base posts 42, which engage the clamp handle when it is advanced to the unclamped position. As can be clearly appreciated, both the clamped and unclamped positions are neutral and a positive force must be applied to displace the clamp handle from either position.  
  In operation, the clamp handle is manually displaced from the unclamped to the clamped position and is automatically returned to the unclamped position by physical engagement of the trip member 58 with the clamp handle 32 as the clamp assembly is axially dis placed to the retracted position. The trip member 58 may be rotated away from the path of the clamp handle to permit the displacement of the clamp handle from the unclamped to the clamped position.  
  The clamp head 36 is secured to the clamp arm 34 at a pivot connection 59 and is capable of limited pivotal displacement thereabout. When the clamp handle is displaced from the unclamped to the clamped position, the clamp head forcefully engages the top 60 surface of each rectanguloid workpiece and the rear surface 62 of the rear workpiece of the workpiece stack which is supported in a V-block defined by bottom 64 and side 68 inserts suitably secured to the clamp base 19.  
  The rear surface of the workpiece stack is forcefully engaged by a substantially clyindrical rear clamp pin 70 which is located within a suitable bore 72 in the clamp head body 74. The rear clamp pin 70 includes a pair of coaxial pivot pins 76 which are fixedly, eccentrically secured to the ends of the clamp pin and which are loosely received by bores (not shown) in the clamp head side plates 78. The engaging face of the rear clamp pin 70 may include two longitudinally extending flutes or bearing surfaces 80 separated by a recess 82 in order to maximize the effect of the clamping forces.  
  To enable the rear clamp pin 70 to tilt from end to end about a central pivot location, the surface of the rear clamp pin remote from the bearing surfaces is beveled 84 from either end towards the center as illustrated in FIG. 4 with reference to the upper clamp pin 94.  
  A lower clamp pin 90 is associated with the top surface 64 of each workpiece of the workpiece stack, a center clamp pin 92 is associated with each pair of lower clamp pins and an upper clamp pin 94 is associated with the pair of center clamp pins 92. This triangular array of lower, center and upper clamp pins is received in a second selectively configured clamp head body opening 96.  
  Each lower clamp pin includes a pair of coaxial pivot pins 98 which are fixedly, eccentrically secured to the ends of the lower clamp pin and which are loosely re ceived by suitable side plate bores 100. Additionally, each lower clamp pin includes cylindrical end portions 102 which have a planar workpiece engaging surface in the form of two longitudinally extending flutes or bearing surfaces 104 separated by a recess 106.  
  The center clamp pins include axially staggered cylindrical portions 108, which have a planar longitudinally extending portion 110 for engaging the cylindrical portion of the lower clamp pins. The width of the planar portion 110 is selectively chosen so as to extend beyond centers of a pair of adjacent lower clamp pins.  
  The upper clamp pin 94 is substantially cylindrical, but includes beveled portions 112 extending toward a pivot location 114 and a planar portion 116 for engaging with the cylindrical portions 108 of the center clamp pins 92. The width of the planar portion 116 is chosen so as to extend beyond centers of the adjacent center clamp cylindrical portions.  
  All voids of the assembled clamp head are filled with a suitable grease to lubricate the clamp pins and to prevent rust and sludge formation.  
  A coolant guard 120 may be secured to the clamp base to confine the flow of coolant directed towards the workpieces in the grinding zone.  
  It can be appreciated that when the clamp assembly is closed upon a stack of workpieces, the various clamp pins will rotate about their axes of rotation and tilt lengthwise to assuredly apply an equal clamping pressure to all the workpieces.  
 What is claimed is:  
  1. A clamping assembly for clamping a workpiece stack having at least three rectanguloid workpieces in a V-block or the like comprising a clamp arm a clamp head pivotally secured to said clamp arm,  
 means for displacing said clamp arm from an unclamped position to a clamped position.  
 said clamp head including a body portion side plates adapted to be secured to opposing sides of said body portion,  
 a first body opening a rear clamp pin adapted to be located within said first body opening,  
 means for mounting said rear clamp pin on said side plates for eccentric rotation and limited lengthwise tilting, I  
 said rear clamp pin including bearing surface means for engaging the rear surface of the workpiece stack and being selectively configured to permit lengthwise tilting and limited eccentric rotation,  
 21 second body opening.  
 three lower clamp pins,  
 means for mounting each of said three lower clamp pins on said side plates for eccentric rotation and limited lengthwise tilting,  
 each of said lower clamp pins including cylindrical end portions having bearing surface means for engaging the top surface of a corresponding workpiece of the workpiece stack,  
 a pair of center pins including cylindrical end portions having bearing surface means of selected width to permit engagement with the cylindrical end portions of an adjacent pair of lower clamp pins,  
 an upper pin including cylindrical end portions hav ing bearing surface means of selected width to permit engagement with the cylindrical end portions of said pair of center pins and being selectively configured to permit limited lengthwise tilting.  
 said second opening being selectively configured to receive said lower, center and upper pins.  
 whereby when the clamp assembly is closed upon a workpiece stack equal pressure will be applied to the engaged surfaces of the workpiece stack.  
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