Abstract:
A clamping device &amp; method for down clamping against a workpiece by utilizing part features produced during a prior operation. The mechanics of this device allow it to open, close, raise and lower during its initialization and release. The device contains a built in block type jaw restraint to facilitate the customization of its clamping heads to suit the shape of the part feature it is to clamp down upon. This device is used within the part boundaries, thus facilitating higher quantity part batch sizes being presented to the limited travels of the machine tool used to process the parts. This invention is comprised of readily available hardware items along with two cost effective and simple to mass-produce components. The device can be actuated manually or with automatic actuation. The method described to prepare the project is unique to the function &amp; usage of this invention.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit of the filing of U.S. Provisional Patent Application Ser. No. 60/752,496 entitled “Workpiece Clamping Device”, filed on Dec. 22, 2005, and the specification thereof is incorporated herein by reference.  
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to adjustable workpiece clamps and other holding devices, actuated manually or actuated automatically and more specifically to metal devices for securing a workpiece to a tooling fixture and on the bed of a machine tool.  
       DESCRIPTION OF RELATED ART  
       [0003]     Numerous forms and types of clamps have long been known in the art, including those, which rely upon such mechanisms as screw threads, wedges, cams, inclines and orbital action. All of the miniature variants of these clamping devices apply their clamping force in a direction not parallel to the centerline of the means of actuation. Most closely resembling my invention is seen within U.S. Pat. No. 6,126,159, but upon close study of this art it will be seen that this device is a spreading device that functions by use of a wedge. This device utilizes an accessory item called a clamping brace by which the device jaws can be immobilized in order to prepare the jaws for a specific usage. Once the jaws have been customized for usage, this accessory item must be removed in order for this device to function. Another device appearing like my invention is seen within U.S. Pat. No. 4,804,171, but upon close study of this art it will be seen that this device is also a wedge actuated spreading device with no provision to facilitate customization of the device jaws. Another device is seen within U.S. Pat. No. 4,901,991, but upon close study of this art it will be seen that this device is also a wedge actuated spreading device. Yet another device is seen within U.S. Pat. No. 4,805,888, but upon close study of this art it will be seen that this device operates on an eccentric cam and applies forces not parallel to the means of actuation. Yet another device is seen within U.S. Pat. No. 4,049,253, but upon close study of this art it will be seen that this device is a toe clamp that uses wedging principals and applies forces not parallel to its means of actuation.  
         [0004]     The present invention relates to improvements in quick-action miniature clamping devices for securely holding work pieces to a tooling structure and/or to the machine tool to undergo further processing&#39;s and machining. This invention leaves a common convention of applying forces not parallel with the means of actuation and accomplishes its clamping action parallel to the centerline of the means of actuation. By using a clamping motion parallel to the means of actuation, this invention requires less space to function. Advantageously, by consuming less space by which to clamp a part, allows for the invention to be utilized within smaller areas that hereto before were considered not accessible by any other clamping devices. Advantageously, this device opens, closes, raises and lowers by rotation of its screw thus making it easy to use. This invention will allow lesser-experienced tooling designers to design toolings that hereto before could only be visualized and designed by senior skill level tool designers. This invention provides the tool designer more options to choose from when attempting to select areas of a part, which can be efficiently clamped upon. Prior to this invention many areas of a part were not considered suitable to clamp upon for the second processing step. This invention will provide a more standardized means by which parts can be clamped for the second processing step.  
       BRIEF SUMMARY OF THE INVENTION &amp; METHOD  
       [0005]     Invention  
         [0006]     The present invention departs from other clamping systems that spread, expand or push thru utilization of wedges, cams, inclines and orbital actuation. The present invention more closely approximates part clamping thru the use of a screw with a washer and nut strategy thus providing advantageous down clamping by utilizing the general principals of a cap screw with holding forces of the invention module equal to the tensile/break strength of the screw used to set in motion this invention. This clamping device lends itself to low-cost fabrication and to ready installation and rapid low profile clamping of work-pieces, which are to undergo a second machining or processing. This clamping device utilizes part features together with the methods claimed herein as is produced from a prior processing step. Implementing the usage of this invention upon a tooling structure and subsequently the usage of the invention as a clamping device does not entail high cost and user skill. In one preferred embodiment, each of the intended work pieces, prepared with the method claimed, are placed over locating pins or against raised abutments or over a combination of any of these mentioned part locators and simultaneously over several strategically placed, attached and customized clamping devices, all located on, within and attached to the tooling structure. All part features utilized to locate by or clamp upon should or can be processed to finish part dimensions. An actuator key is passed thru the part method passageway and then thru the centrally located passageway of the customized clamping device and down into the driving cavity of the screw. Then the actuator key is rotated, advancing the device onto the part and tooling structure, until moderately tightened. Then the actuator key is removed and this process is repeated for each part method passageway and each customized clamping device. Optionally, this clamping device may be actuated without a key if an automatic actuator is used. The screw assemblage within the clamping device may be used to attach to a coupling link that is upon the power shaft of an automatic actuator. The automatic actuator could be selected from a variety of different types to suit the user, e.g. hydraulic, pneumatic, electrical, rotary or even a combination of these actuation devices in a manner as described herein. Because the clamping device housing is attached to the tooling structure, this device may be actuated by forces originating from either above the tooling structure or from below the tooling structure. The parts are now ready for secondary machining or processing. As the customized heads clamp upon the finished part dimensions, simple and generally used part programming options are employed to direct the cutting tool movements around and clear of the clamping heads of the invention. Releasing the part, raising the clamping device above the part feature and retracting the clamping ledges can be accomplished by rotating an actuator key into the driving cavity of the screw and counter rotating the screw thus raising the center piece of the clamping device which is designed to raise the housing above the part and mechanically bring together the clamping ledges to allow for part removal OR by utilizing an automatic actuator to accomplish the same series of clamping and unclamping, raise and lower movements. To customize the ledges of the clamping device, tighten the clamping device down onto a plate and machine the desired shape upon the heads.  
         [0007]     Method  
         [0008]     Prerequisite to the ability to manually use the invention are several part characteristics either as they exist in the part design or as would be added to the part to provide a unique method to be used in conjunction with the present invention. First Method, for manual actuation of the clamping device with a key, the part specifications must allow a thru passageway to be machined or processed in the location of the part feature that is to be utilized for clamping onto and to be used for an actuator key to pass through. Second Method, at a location within this passageway of the desired part feature, a mill cut is to be performed whose sides are perpendicular to the means of actuation of the present invention and should/may equal a finished part dimension depth that will be performed during the second machining or processing operation. This milling cut is at two diametrically opposed places or can be up to 360 degrees round recess type shape. This recess cut for the second method can be performed utilizing a “key cutter” or “circular cutter” as will be illustrated herein at  FIG. 8 . Should an automatic actuator actuate this clamping device, only the Second Method stated herein would be required to facilitate usage of this invention.  
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0009]     Although the aspects and features of this invention and method which are considered to be novel are expressed in the appended claims, further details as to preferred practices and as to further objects and characteristics thereof may be most readily comprehended through reference to the following detailed description when taken in connection with the accompanying drawings and are not to be construed as limiting the invention wherein.  
         [0010]      FIG. 1  is a perspective view of a clamping device shown in the closed position; some hardware items are obscured as they are within the solid shape.  
         [0011]      FIG. 2  is a perspective view of a clamping device shown in the closed position; a cross-section line is shown on this illustration to provide for a clear understanding of exactly where the cross-section view on  FIG. 3  has been derived from.  
         [0012]      FIG. 3  is a perspective and cross-section view of a clamping device illustrating hardware items and other features.  
         [0013]      FIG. 4  is a perspective and blow out view of a clamping device. Certain angulated surfaces and an angulated passageway are illustrated.  
         [0014]      FIG. 5  is a perspective view illustrating several possible customizations of a clamping device. The clamping devices are shown customized and in both the open and closed positions.  
         [0015]      FIG. 6  is a perspective view illustrating a tooling structure, also illustrated are automatic actuators that may be used to actuate a clamping device.  
         [0016]      FIG. 7  is a perspective view of a project part; a cross-section line is shown on this illustration to provide for a clear understanding of exactly where the cross-section view on  FIG. 8  has been derived from.  
         [0017]      FIG. 8  is a perspective and cross-section view of a project part illustrating method features and also illustrating a means of providing a method.  
         [0018]      FIG. 9  is a perspective view of a project part nested into a tooling structure, optional automatic actuators are shown for actuation of a claming device; two cross-section lines are shown on this illustration to provide for a clear understanding of exactly where the cross-section view on  FIG. 10  and also  FIG. 11  have been derived from.  
         [0019]      FIG. 10  is a perspective &amp; cross-sectioned view of a project part illustrating method features; a tooling structure, two clamping devices, a manual actuator and a pair of optional automatic actuators.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]     Having reference to the drawings, wherein like reference characters designate identical or corresponding parts throughout the different views, there is shown a clamping device  90  comprised of a “U” shaped housing  1  made from rigid material having some resilient flexibility and a material whose shape may be mass produced by machining, molding, extruding, casting or stamping. The housing comprises a base  26  having a flat, horizontal undersurface  27  for mounting on a tooling structure  23  upon surface  72 ; housing surfaces  55  and undersurface  27  are co-planar. Projecting upwardly from opposite ends of base  26  and surface  55  are two substantially parallel shanks  28  &amp;  29  being thicker at their lower end and at the inner face being reduced in thickness at  30  &amp;  31  with the inner face surfaces continuing upwardly to transition with parallel profile surfaces  84  &amp;  85  continue to a pair of substantially parallel, mirror image clearance channels  34  &amp;  35 . Said clearance channel vertical side surfaces  36  &amp;  37  each continue upwardly until said vertical side surface of said clearance channel intersects the most upward and outwardly location of each angulated surface  17  &amp;  18 , each surface  17  &amp;  18  then tapers inward and away from it at an angle “A” of approximately 60 degrees from the vertical to join vertical side surfaces  38  &amp;  39  which now continue parallel and vertically to join a secondary pair of angulated surfaces  19  &amp;  20  at their most inward and upper location, now transition outward and away from it at an angle “A” of approximately 60 degrees from the vertical and then continuing outwardly until intersecting vertical surfaces  40  &amp;  41  and then continue parallel and vertically to parallel profile surfaces  82  &amp;  83  which continue outwardly and transition into the planar surface  73 . Parallel profile surfaces  82  &amp;  83  provide a functional lead in surface for block  2 . The outer surfaces of shanks  28  &amp;  29  project upwardly and parallel from opposite ends of base surface  26  and continue to parallel profile surfaces  80  &amp;  81  then continue outwardly and transition horizontally to the extents of side surfaces  42  &amp;  43  then transition vertically to the top surface  73 . The shanks  28  &amp;  29  support a pair of customizable heads  32  &amp;  33 . Profile surfaces  80 ,  81 ,  84  &amp;  85  provide structural support to customizable heads  32  &amp;  33 . Approximately mid-span distance of shanks  28  &amp;  29  and passing thru perpendicular to co-planar surfaces  55  &amp;  27  are passageways  47 ,  48  &amp;  14 . Passageway  14  is located approximately mid distance along the longitudinal length of surfaces  55  &amp;  27  and passageways  47  &amp;  48  are located approximately mid distance between passageways  14  and the furthest extents of surfaces  55  &amp;  27  respectively.  
         [0021]     There is shown a “T” shaped block  2  made from a material that is rigid and whose shape may be mass produced by machining, molding, extruding, casting or stamping and is comprised of parallel profile surfaces and dimensioned to nest between shanks  28  &amp;  29  and to intimately nest angulated surfaces  15  &amp;  16  against surfaces  17  &amp;  18  at an angle “B” of approximately 60 degrees from the vertical. Angulated surfaces  21  &amp;  22  are dimensioned to intimately nest with surfaces  19  &amp;  20  at an angle “B” of approximately 60 degrees from the vertical. Surfaces  15  &amp;  16  transition to vertical surfaces  44  &amp;  45  which transition along profile surfaces  86  &amp;  87  projecting upward and each outwardly to surfaces  21  &amp;  22 . Vertical surfaces  44 ,  45  are vertically dimensioned so as to allow either; a first pair of surfaces which is comprised of surfaces  15  &amp;  16  to intimately nest with surfaces  17  &amp;  18 ; OR a second pair of surfaces which is comprised of surfaces  21  &amp;  22  to intimately nest with surfaces  19  &amp;  20 ; but not dimensioned to allow the first and the second pair  2  surfaces to nest simultaneously. Vertical surfaces  44 ,  45  are dimensioned to place the entire vertical portion of surfaces  21  &amp;  22  above surface  73  when surfaces  15  &amp;  16  are intimately nested with surfaces  17  &amp;  18 . Surfaces  88  &amp;  89  are dimensioned so as not to touch profile surfaces  84  &amp;  85  when surfaces  21  &amp;  22  intimately nest with surfaces  19  &amp;  20 . Surfaces  88  &amp;  89  provide structural support to surfaces  15  &amp;  16 . The horizontal distance as measured perpendicular to surface  27  across the intersection of surfaces  15  &amp;  88  horizontally across to the intersection of surfaces  16  &amp;  89  is dimensioned to be greater than the horizontal distance as measured perpendicular to surface  27  across the intersection of surfaces  17  &amp;  38  horizontally across to the intersection of surfaces  16  &amp;  39  and same moment as surfaces  21  &amp;  22  are intimately nesting with surfaces,  19  &amp;  20  with column  62  in place. The differential between these two dimensions allows material engagement to initiate intimate nesting of surfaces  15  against  17  and surfaces  16  against  18  when screw  3  is counter rotated away from tooling structure  23 , also provided is a material engagement to make happen the interlocking of block  2  into housing  1 , also provided during material engagement is an increase to the dimension between tooling structure surface  72  as measured from undersurface  27  as allowed by a comparative distance calculation between bolt  4  &amp;  5  shoulder lengths  58  &amp;  59  as compared to the passageway lengths of  53  &amp;  54  to let rise clamping device  90 . Relevant to clearances required between housing  1  and block  2  in the general area of the clearance channel surfaces  34  &amp;  35  and more specifically the distance relationship between the intersecting surfaces  15  &amp;  88  and horizontally across to the intersection of surfaces  16  &amp;  89  are dimensioned less than the, horizontal distance as measured perpendicular to surface  27  across the intersection of surfaces  34  &amp;  17  and horizontally across to the intersection of surfaces  35  &amp;  18  as required to facilitate an adequate area for block  2  to move as distance between surfaces  27  &amp;  72  increases also as the distances reduce between surfaces  38  &amp;  44  also between surfaces  39  &amp;  45 . Within block  2  is passageway  13  that is a profile surface traversing in a direction perpendicular to the longitudinal direction of the parallel profile surfaces comprising block  2 . Surface  70  and surface  69  are coplanar. Passageway  13  provides residence for screw  3 . Passageway  11  intersects passageway  13  in a perpendicular direction and provides access to screw  3  for an actuator key  91 . Passageway  46  allows screw  3  to pass through to passageway  14 . The center axis of passageway  127  intersects the centerline axis of passageway  46  at angle “C” of approximately 30 degrees from the vertical and both passageways  127  &amp;  46  are of diameters that will accommodate screw  3 . Passageways  11  &amp;  46  are inline. Passageways  10  &amp;  12  provide access to bolts  4  &amp;  5  for an actuator key  91 . Passageways  10 ,  12  &amp;  46  are inline with locations of passageways  47 ,  48 ,  14  and tapped holes  60 ,  61  &amp;  24 .  
         [0022]     There is shown a screw assemblage comprising of a screw  3  made from a material like alloy steel is passed thru an upper washer  9  that is made from a metallic material, then passed into passageway  127  at angle “C” then passed into passageway  46  then seated within passageway  13 , onto surface  70  then passed thru lower washer  8  that is made from a metallic material. Upper nut  7  which is made from a metallic material is then rotated onto screw  3  until contact is made with lower washer  8  against surface  69 , lower nut  6  which is made from a metallic material is then rotated onto screw  3  until contact is made with upper nut  7  at which time lower nut  6  is held stationary and upper nut  7  is counter-tightened against lower nut  6  to effectuate a wedge lock upon screw  3  which, establishes a linear distance between washers  8  &amp;  9  that is more than the linear distance between coplanar surfaces  69  &amp;  70  to allow screw  3  to freely rotate in passageway  46 .  
         [0023]     There is shown shoulder bolts  4  &amp;  5  that are made from a metallic material like alloy steel or stainless steel is passed through cooperating passageways  47  &amp;  48 . Counter bore type recesses  49  &amp;  50  are dimensioned to allow shoulder bolts head surfaces  78  &amp;  79  to be below surface  55  to a distance of (shoulder length  59  minus passageway wall length  54 ) and (shoulder length  58  minus passageway wall length  53 ) when bolt head undersurfaces  74  &amp;  75  contact bottom of c-bore surfaces  51  &amp;  52 . Passageway diameters  47  &amp;  48  are dimensioned larger than bolt shoulder diameter  56  &amp;  57  by an amount approximating 3% of diameter  56  &amp;  57  and linear length  53  &amp;  54  are dimensioned shorter than bolt shoulder length  58  &amp;  59  by an amount approximating 15% of diameter  56  &amp;  57 . These clearance calculations translate to a desirable free play fit characteristic between clamping device  90  to tooling structure  23  and part  65 .  
         [0024]     Housing  1  is positioned above tooling structure surface  72  with passageways  47  &amp;  48  inline with tapped holes  60  &amp;  61 , shoulder bolts  4  &amp;  5  are placed within passageways  47  &amp;  48 , an actuator key  91  is positioned into driving cavities  67  &amp;  68  and shoulder bolts  4  &amp;  5  are rotated into tapped holes  60  &amp;  61  until tight against surface  72 . Block  2  may be placed between shanks  28  &amp;  29  and brought in place with screw  3  by placing an actuator key  91  thru passageway  11  into driving cavity  66  and rotating screw  3  into tapped hole  24 . Vertical down clamping parallel with and guided by bolt shoulders  58  &amp;  59  allow the clamping device and the customizable heads  32  &amp;  33  to move toward tooling structure  23  by forces exerted by screw  3  when rotated into the tapped hole  24  and when the following events occur; surface  71  intimately contacts upper washer  9  onto surface  70  and surfaces  21  &amp;  22  intimately nest with surfaces  18  &amp;  19  establishing a inflexible column controlled dimension  62  as surface  69  intimately contacts surface  55 . The clamping device  90  advances toward tooling structure  23  for a distance of (shoulder length  59  minus wall length  54 ) and (shoulder length  58  minus wall length  53 ) as undersurface  27  intimately contacts surface  72 . The clamping device is now static. Dimension  25  is rigid and maximized and the clamping device is now attached to tooling structure  23 . Vertical up release and clamp head  32  &amp;  33  retraction of the clamping device  90  is accomplished as follows; insert actuator key  91  thru passageway  11  into cavity  66  of screw  3 . Counter-rotating screw  3  away from tapped hole  24 , exerts adequate force to cause the following events to occur; upper nut  7  intimately, contacts lower washer  8  against surface  69  to vertically elevate block  2  until simultaneous intimate contact is made with surfaces  15  &amp;  17  also  16  &amp;  18 . Continued rotation of actuator screw  3  away from tapped hole  24  lifts housing  1  away from surface  72  for a distance of (shoulder length  59  minus wall length  54 ) and (shoulder length  58  minus wall length  53 ) until c-bore bottom surfaces  51  &amp;  52  intimately contact bolt undersurfaces  74  &amp;  75  at which time housing  1  ceases to increase distance between surface  72  and undersurface  27 . Continued counter rotation of screw  3  away from tapped hole  24  with housing  1  causes angulated surfaces  15  &amp;  16  to move in a vertical direction away from surface  72  forcing angulated surfaces  17  &amp;  18  to move in an inwardly direction along the inclines of surfaces  15  &amp;  16  until surfaces  38  &amp;  39  are forced to make contact with surfaces  44  &amp;  45 . At the conclusion of this event dimension  25  has been minimized, the clamping device is static in the vertical up position and the clamp retraction is complete.  
         [0025]     There is also illustrated an optional method for clamping device actuation comprising of an underside mounted automatic actuator  128  attached to tooling structure  23  with cooperating brackets  93 . Coupling link  133  passes through a cooperating passageway  92  and links to screw  3 . Automatic actuation occurs as an energy source enters automatic actuator  128  thru power input  131 . The automatic actuator  128  may be of hydraulic type or of pneumatic type or of an electric type or of a rotary screw type or of other types or a combination of those mentioned.  
         [0026]     There is also illustrated several customizations of the clamping device  90  heads  42  &amp;  43  with head shapes  116 . Head shapes  116  are shown for reference only and many other shapes may be conceived and built, as a project may require. Customization of heads  42  &amp; 43  may be accomplished by firmly attaching clamping device  90  onto, a tooling structure  23  or equivalent, using actuator key  91  thru passageways  10 ,  11  &amp;  12  into driving cavities  66 ,  67  &amp;  68  of screws  3 ,  4  &amp;  5  to immobilize clamping device  90 . Heads  42  &amp;  43  may now be machined and customized to fit a part feature  120  &amp;  121  as may be determined by a tooling person. Customization of additional clamping devices  90 , for more and different feature shapes may be accomplished as per previous description. A trained machinist of ordinary skill can perform the customization of this clamping device.  
         [0027]     There is also illustrated a part  65  together with preparation and method steps required prior to usage of clamping device  90 . Part  65  is shown with all specified cuts  120 ,  121 ,  122 ,  123 ,  124  &amp;  125 , also holes  106 ,  126  &amp;  132 , all other surfaces including top surface  115  are cut to finish dimensions. Quite often this first process step utilizes a vise, other conventional clamping or fixturing, which leaves a remnant piece of material attached to the part called a carrier  104 . In this example, part features  120  &amp;  121  are selected to receive the method preparation to enable usage of clamping device  90 . Method step 1, provide passageways  63  &amp;  64  thru part of a cooperating diameter to accept actuator key  91 . Method step 2, using a standard or customized cutter  100 , with relief diameter  102 , machine undercut surface  110  a minimum of two places 180 degrees apart to accommodate clamping device customized head shape  116 . Surface  109  should be cut to a depth that will allow clamping device to function. The wall thickness between top surface  115  and undercut surface  111  may be to a finish dimension. Method is now complete.  
         [0028]     There is also illustrated the general preparation steps for a tooling structure  23 . A trained tooling person of ordinary skill may select the tooling structure material and sizes that meet requirements of part size and part density to be processed. Select part features from which to locate part  65  in the “X” &amp; “Y” directions on tooling structure  23 . Illustrated are pins  112  &amp;  113  and/or a part accommodating nest shape  114 . Part hole  106  may locate over pin  112  and phantomlike illustrated hole  107  may locate over pin  113 , OR a combination of part accommodating nest shapes  114  and pins  112  &amp;  113  may be used to locate part in tooling structure  23 . Implement the selected part locating options above tooling structure surface  72 . Part surface  115  is to intimately contact tooling structure surface  130  and at all areas where part features  120  &amp;  121  intersect with part surface  115 . Support by tooling structure surface  130  is required in these locations to effectuate direct toe clamping of part undersurfaces  111  against surface  130 . Prepare a cooperating pocket cavity  108  to accept clamping device  90 , drill and tap holes  24 ,  60  &amp;  61 . If an optional automatic actuator  128  is to be utilized, provide an accommodating passageway  92  in place of tapped holes  24  within tooling structure  23 .  
         [0029]     CNC programming may be required to develop a tool path layout and program to avoid cutter contact with the customized clamping head shapes  116  as these shapes will become visible as the second part processing is being performed. The clamping head shapes  116  may be viewed as “raised islands” to a CNC programming system and most CNC programming systems will program code to path cutters up, over, down and around the head shapes  116  of the clamping device  90 . Head shape undersurface  117  should be contacting a finish part surface  111  as established by the Method cut. Surface  111  should be the same surface programmed to before the up, over, down and or around moves of the cutting tool.  
         [0030]     While the preferred embodiment of the invention is directed toward clamping challenges within CNC tooling and machining, this device should also be viewed as a unique generic clamping module that is adaptable to many applications and its usage should not be considered limited to the examples presented herein. Variations and modifications of the present invention will be obvious to those skilled in the art and other embodiments may be devised without departing from the spirit of the invention and in the appended claims all such modifications and equivalents. The entire disclosures and all references, applications, patents and publications cited above are hereby incorporated by reference.