Abstract:
A die press assembly for producing punched parts from a travelling web of material, the die press comprising: a lower die shoe securing a compound punch holder plate thereon, the compound punch holder biasedly gripping a compound punch tool therein, the lower die shoe also supporting a reciprocably movable stripper holder plate, wherein the compound punch extends slideably through a biasedly gripped stripper holder tool in the stripper holder plate; an upper punch holder movable with respect to the lower die shoe, the upper punch holder having a center punch holder plate which biasedly grips a center punch tool therewithin; and a die holder plate fixedly attached to the center punch holder plate with a biasedly gripped die tool slideably enclosing the center punch, wherein each of the biasedly gripped tools are in co-axial alignment in distortable bores in their respective plates.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention relates to punch press assemblies and more particularly to tool-holding grip arrangements for gripping tools to permit very accurate alignment arrangements to facilitate the alignment of opposing tools utilized to pierce a sheet of material such as for example in a punch press. 
     Discussion of the prior art 
     Compound tooling is currently utilized by hundreds of manufacturers to produce thousands of different types of washers made from aluminum, brass, copper, nylon, steel utilized in almost everything society touches. Washers are for example, utilized in any product with nuts and bolts or moving parts. The inside diameter and the outside diameter of these washers or other punched parts have become more critical and significant for use in the manufacture of high-quality precision devices. 
     Prior art tool and die sets have to be made slightly loose, and those tools use clamping screws which thus influences a die in a tool holder. That in turn establishes inaccuracies and a loss of concentricity of the alignment of those tools. 
     It is an object of the present invention to overcome the disadvantages of the prior art. 
     It is a further object of the present invention to provide a tool set in which the punch and die members are in exact accurate concentric alignment with one another. 
     It is a further object of the present invention to provide a unique and simple tool gripping and alignment plate which firmly grips a tool in a bias able irregular opening, which, when biased forms a perfect circle for gripping the tool, especially useful in die punching operations. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention comprises a die set assembly or arrangement for the manufacture of punched parts from a traveling web or sheet of material such as metal or plastic to produce washers or the like. 
     The die set assembly or arrangement of the present invention comprises a base portion which comprises a lowermost die shoe. The lowermost die shoe has a central bore extending therethrough. A compound punch holder plate is bolted to the upper side of the die shoe and has a central bore extending there through of a second diameter. A stripper holder plate is reciprocably supported on an arrangement of shoulder screws arranged between the lowermost die shoe and the stripper holder plate itself. Die springs compressibly support the stripper holder plate over the compound punch holder plate. 
     A compound punch is fixedly secured in the second diameter bore of the compound punch holder plate. The compound punch extends into the stripper holder plate. The compound punch has a bore in coaxial alignment with the bore in the lowermost die shoe. A stripper ring adjustably encloses the uppermost end of the compound punch within the stripper holder plate. 
     The die set arrangement of the present invention also comprises an upper portion which comprises the upper punch holder plate. The upper punch holder plate is disposed parallel to and reciprocably movable with respect to the stripper holderplate on the base portion of the die set arrangement. The punch holder plate is supported on guide pins which are received in guide bushings at their lowermost end. A center punch holder plate is bolted to the lower side of the punch holder plate. The center punch holder plate has a bore which adjustably arranged about a center punch there within. A die holder plate is supported by those same pins onto the lower side of the center punch holder plate. The die holder plate has a central opening of a third diameter. The opening in the die holder plate is arranged to adjustably enclose and align a die member therewithin. The die holder plate has a central opening which encloses an annular knockout member. The annular knockout member has a central bore through which the center punch, supported at its upper end by the center punch holder plate, is supported. 
     Reciprocating motion of the upper portion of the die set arrangement, with its die arranged downwardly therefrom, impacting the stripper holder plate supported on the lower portion of the die set arrangement, with a traveling web of material moving therebetween, effects the manufacture of a punched part by virtue of the center punch and the die mating with the compound punch and its associated stripper holder. 
     The concentric alignment each of these components is critical to the manufacture of a proper punched part. 
     The center punch holder plate and the die holder plate in the uppermost portion of the die set arrangement, and the stripper holder plate and the compound punch holder plate in the lower portion of the die set arrangement, each utilize a flexible grip arrangement to secure the tool components within their commonly aligned bores. 
     The center punch holder plate for example, has a central bore for squeezably pinching and holding a tool concentrically therewithin, with respect to adjacent tool holding plates. The central bore in the exemplary center punch holder plate is slightly out of round at one side location thereof. That side location also includes the beginning or distal end of a curvilinear cut through the center punch holder plate which curvilinear cut extends in a generally semi-circular or somewhat “J” shaped pattern around the central bore. That generally semicircular cut extends from the bore wall, and around the bore at least 180° therearound, looking somewhat liked a “curved finger”. In one embodiment of that semicircular cut, the second or proximal end of that cut curves slightly radially outwardly and away from the center of that central bore within the center punch holder plate. 
     A threaded bore is arranged through the side edge of the exemplary center punch holder plate and extends up to the radially outer surface of that generally semi circular cut, meeting the cut at a location of about one third the distance from the distal end of that cut. An adjustment bolt is disposed within that threaded bore so as to effect (or release) a bias on the radially outward side of the cut, when that adjustment bolt is rotated within that bore. That generally semicircular cut through the exemplary center punch holder plate in effect creates a “flexible grip” finger. A bias inwardly by the adjustment bolt against the finger presses a semi-circular curved wall portion of that finger slightly inwardly radially, so as to distort the irregular bore and hence create a perfect circular hole in that central bore. When for example, a tool such as a center punch is placed within the center punch holder plate, and the adjustment bolt is tightened with respect to that finger, the center punch is now squeezed tightly within a distorted bore now comprising a perfect circular hole therewithin. By aligning the respective center bores of the adjacent holder plates within the upper portion and the lower portion of the die set arrangement, the matable tool components therein may be held in perfect axial alignment. In one preferred embodiment of the present invention, the center punch holder plate, the die holder plate, the stripper holder plate and the compound punch holder plate may have an initial or pilot bore drilled therethrough to establish the initial alignment thereof. The slight irregularity of those respective bores may be machined when the generally semicircular cut is made in each respective holder plate. Thus when a tool is clamped within respective holder plate, that bore within that holder plate becomes a perfect circle. When no tool is clamped within the respective holder plates, the bore within those respective holder plates is irregular and “out of round” in its undistorted configuration. 
     The invention thus comprises a die press assembly for producing punched parts from a travelling web of material, the die press comprising: a lower die shoe securing a compound punch holder plate thereon, the compound punch holder biasedly gripping a compound punch tool therein, the lower die shoe also supporting a reciprocably movable stripper holder plate, wherein the compound punch extends slideably through a biasedly gripped stripper holder tool in the stripper holder plate; an upper punch holder movable with respect to the lower die shoe, the upper punch holder having a center punch holder plate which biasedly grips a center punch tool therewithin, and a die holder plate fixedly attached to the center punch holder plate with a biasedly gripped die tool slideably enclosing the center punch, wherein each of the biasedly gripped tools are in co-axial alignment in distortable bores in their respective plates. The distortable bores each biasedly grip their respective tools by a gripping finger comprising a curvilinear member defined by a cut through its plate, the gripping finger both comprising and extending around at least 180 degrees of the circumference of the bore. The gripping finger which defines at least part of the wall of the bore, is biasable inwardly about a pivot location of the side of the bore, from a non-circular configuration into a circular configuration. The gripping finger is defined by a generally “J” shaped cut in the plate in which it is arranged. The gripping finger is biased inwardly by the adjustable threaded member. The cut defining the gripping member has a first end which extends through a side wall portion of the bore in the plate. The cut defining the gripping member has a second end which extends radially outwardly from its circumferential path, and wherein the pivot location is generally diametrically opposite the first end of the cut in the wall of the bore, defining the gripping finger. The adjustable threaded member has a longitudinal axis which is in alignment with the first end of the cut defining the gripping finger. The bore in its undistorted orientation is comprised of a pair of semi-circular walls, each having its own center of curvature. The bore in its distorted orientation is comprised of a pair of semi-circular walls, each having a common center of curvature, and now forming a circle. 
     The invention also comprised a method of gripping a tool for use in a punch press assembly, comprising: machining a non-circular walled bore in a tool supporting plate; machining a curvilinear cut in the tool supporting plate to form an elongated, biasable, curvilinear gripping finger, which gripping finger has a wall portion that comprises at least one half of the circumference of the non-circular walled bore; inserting a tool into the non-circular walled bore in the tool supporting plate; and biasing the elongated, curvilinear gripping finger into a distorted circular configuration so as to form a snug tool gripping circular wall about the tool inserted therein. The elongated curvilinear gripping finger is biased by an adjustable bolt member. The curvilinear cut has a first end which extends into the wall of the bore in the tool supporting plate. The adjustable bolt has a longitudinal axis which is in alignment with the first end of the curvilinear cut in the tool supporting plate. 
     The invention also comprises a solid tool gripping and alignment plate, for accurately gripping and holding in perfect alignment, a tool placed therein, comprising: a flat unitary tool gripping plate; an irregular opening formed in the tool gripping plate, for gripping a tool therein; a biasing member for biasing a portion of the irregular opening in the tool gripping plate from a non-circular shape into a circular shaped opening for circumferentially gripping a tool therein. The irregular opening is preferably comprised of a pair of generally semi-circular curves each having its own center of curvature. One of the semi-circular curves comprising the irregular opening is preferably comprised of a pivotable, generally “J” shaped finger member for about one-half of its inner periphery of the opening. The shaped finger member is defined by a generally “J” shaped cut through the plate from a first point on its inner periphery, semi-circumferentially about the inner periphery, to an end point radially outwardly of the pivot point of the “J” shaped finger member. The generally “J” shaped finger member, when biased, pivots about a location on the inner periphery of the opening opposite the location of the first point of the cut on the inner point of the opening. The biasing member comprises an adjustable threaded member extending through a side wall of the plate, in biasing abutment with a side portion of the “J” shaped finger member, and is in axial alignment with the first point of the side wall of the irregular shaped bore in the plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and advantages of the present invention will become more apparent when viewed in conjunction with the following drawings, in which: 
         FIG. 1  is a side elevation view in section of a compound die assembly and a sheet of material passing therewithin to be punched by a punch and die arrangement including an arrangement of flexible gripping members for readily aligning and securing those punch and die components therein; 
         FIG. 2  is a side elevation view of the compound die assembly shown in  FIG. 1 , with the gripped punch and die components mating and piercing the sheet of material passing therebetween; 
         FIG. 3  is an exemplary plan view of a center punch holder plate; 
         FIG. 4  is a view taken along the lines  4 - 4  of  FIG. 3  showing the center punch holder played in a side view; and 
         FIG. 5  is an enlarged exemplary plan view of the compound die holder plate. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings in detail and particularly to  FIGS. 1 and 2 , there is shown the present invention which comprises a die set assembly or arrangement  10  for the manufacture of punched parts from a traveling web or sheet of material  12  such as metal or plastic to produce washers  14  or the like. 
     The die set assembly or arrangement  10  of the present invention comprises a base portion  16  which comprises a lowermost die shoe  18 . The lowermost die shoe  18  has a central bore  20  of a first diameter D 1 , extending therethrough. A compound punch holder plate  22  is attached, by an arrangement of bolts  24 , to the upper side  26  of the die shoe  18  and has a second diameter central bore  28  extending therethrough, of a second diameter D 2 . A stripper holder plate  32  is reciprocably supported on an arrangement of shoulder screws  34  arranged between the lowermost die shoe  18  and the stripper holder plate  32  itself. Die springs  36  compressibly support the stripper holder plate  32  over the compound punch holder plate  22 . 
     An elongated compound punch  38  is secured in component-controlled coaxial alignment by a gripping finger means “G”, described hereinbelow, within the second diameter central bore  28  of the compound punch holder plate  22 , and has a lower end which rests upon the upper side of the die shoe  18 , as may be seen in  FIGS. 1 and 2 . The compound punch  38  extends into the reciprocably displaceable stripper holder plate  32 . The compound punch  38  has a bore  40  in coaxial alignment with the bore  20  in the lowermost die shoe  18 . A stripper ring  42 , is securably seated in component-controlled co-alignment within an annular shoulder  33  of the holder plate  32 , and which stripper ring  42  also slidably surrounds the uppermost end of the compound punch  38  within the reciprocably displaceable stripper holder plate  32 . 
     The die set arrangement of the present invention also comprises an upper portion  50  which comprises the upper center punch holder plate  52 . The upper center punch holder plate  52  is disposed parallel to and reciprocably movable toward and away from the stripper holder plate  32  on the base portion  16  of the die set arrangement  10 , as may be seen from the representation in  FIGS. 1 and 2 . The punch holder plate  52  is supported on guide pins  54  which are received in guide bushings  56  at their lowermost end, as represented in  FIG. 1 . The center punch holder plate  52  is bolted to the lower side  58  of the punch holder  60  by an arrangement of bolts  62 . The center punch holder plate  52  has an commonly co-axially aligned adjustable bore  64  which grips, by a gripping finger means “G”, described hereinbelow, a commonly co-axially aligned center punch  66  therewithin, which gripping finger means “G” as noted, is described hereinbelow. A die holder plate  68  is also supported by those same pins or bolts  62  onto the lower side of the punch holder  60  as may be seen in  FIGS. 1 and 2 . The die holder plate  68  has an adjustable central bore or opening  70  of a third diameter D 3 . The opening  70  in the die holder plate  68  is arranged to adjustably enclose and align a die member  72  therewithin, by another commonly aligned gripping finger means “G”, described hereinbelow. The die holder plate  68  also encloses an annular, compressible, reciprocably movable knockout member  74  within the bore  76  of the die member  72 . The compressible annular knockout member  74  has a central bore  78  through which the center punch  66 , supported at its upper end against the lower side  58  of the punch holder  60 , by the center punch holder plate  52 , as shown in  FIGS. 1 and 2 . The knockout member  74  temporarily compresses as the punch  66  strikes the material  12  to be pierced. 
     Reciprocating motion of the upper portion  50  of the die set arrangement  10 , with its die  72  arranged downwardly therefrom, impacts the sheet of material  12  moving across the stripper holder plate  32  supported on the lower portion  16  of the die set arrangement  10 , during the traveling of that web of material  12  moving therebetween, to effect the manufacture of a punched part  14  by virtue of the center punch  66  and the die  72  mating with the compound punch  38  and its associated stripper ring  42  and the stripper holder plate  32 . 
     The concentric co-axial alignment each of the center punch  66  and compound punch  38  and associated die components is critical to the proper manufacture of a proper punched part  14 . 
     The center punch holder plate  52  and the die holder plate  68  in the uppermost portion  50  of the die set arrangement  10 , and the stripper holder plate  32  and the compound punch holder plate  22  in the lower portion  16  of the die set arrangement  10 , each utilize their own gripper means “G”, comprising a flexible generally “J” shaped gripping member or grip arrangement  84  to secure the center punch  66 , the die  72 , stripper holder  42  and the compound punch  38  respectively, as tool components efficiently securely in co-axial alignment within their commonly aligned bores in their respective holders (plates)  52 ,  68 ,  32  and  22 . 
     Such gripper means “G” comprises the generally “J” shaped, flexible gripping finger  84 , with its inner peripheral, (semicircular) tool engaging surface, and is shown in an exemplary manner in  FIGS. 3, 4 and 5 . 
     The center punch holder plate  52 , shown in  FIGS. 3 and 4  as an example of the gripper means “G” cited hereinabove, has its adjustable central bore  64  for squeezably pinching and holding a tool (i.e. here, center punch  66  in phantom) concentrically therewithin, with respect to adjacent tool holding plates  68 ,  32  and  22 , as represented in  FIGS. 1 and 2 . The central bore  64  in the exemplary center punch holder plate  52  is slightly “out of round”. A generally “J” shaped cut  86  is made through the holder plate  52 , as shown in the example in  FIG. 3 . That “J” shaped cut  86  begins as a gap at one location “A”, as a first point on the inner periphery of the bore  64  and extends circumferentially around and beyond 180° from that one location “A”, as represented in  FIG. 3 , and extends to a radially extended location “E”, in a curved point circumferentially and radially beyond point “B”. The bore  64  has a first semicircular configuration “C1” extending from location “A” to point “B”, and has a second semicircular configuration “C2” extending from point “B” as presented in  FIG. 3 . The bore  64 , is thus irregular (i.e. non-circular) when it is originally machined. Each semicircular configuration “C1” and C2” has its own center of curvature “Y” and “Z” respectively. 
     A finger biasing adjustment bolt  90  is threadedly received into a bore  92  in the side  94  of the plate  52  as represented in  FIGS. 3 and 4 . The biasing adjustment bolt  90 , such as a bolt or the like, has a longitudinal axis “L” which is in alignment with the location “A”, and a midpoint in the gap thereat. Advancement of the adjustment bolt  90  against the finger  84  effects a tightening of that elongated, curvilinear finger  84 , to pivot the finger  84  slightly around the location “B”, (which is generally diametrically opposite the first point “A”, the location of the cut through the side wall of the bore  64 ), thus forming that bore  64  into a perfect circle, and thus tightening that gripping finger  84  about the center punch  66 . Retraction of that biasing member  90  from its threaded bore  92  removes the bias from the gripping finger  84 , so as to loosen its grip on the member received therewithin, which in this exemplary case is the punch  66 , thus returning the bore  64  to its undistorted, non-circular state. 
     The adjustment bolt  90  is thus adjustably disposed within that threaded bore  92  so as to effect (or release) a bias on the radially outward side of the cut  86 , when that adjustment bolt  90  is rotated within that bore  92 . That generally “J” shaped, yet generally semicircular cut  86  through the exemplary center punch holder plate  52  in effect creates the “flexible grip” finger  84 . A bias inwardly by the adjustment bolt  90  against the finger  84  presses that finger slightly (about for example, one half of a degree) inwardly radially, as indicated by arrow “R” in  FIG. 5 , so as to distort the pre-biased “irregular” distorted non-circular bore  64  into a biased “now circular” bore and hence create a accurate tool-gripping perfect circular hole within that central bore  64 . When for example, a tool such as for example, a center punch  66  is placed within for example, the center punch holder plate  52 , and its respective adjustment bolt  90  is adjusted and tightened with respect to that gripping finger  84 , the center punch  66  is squeezed tightly within a now biased-induced perfect, tool receiving circular hole  64  therewithin. By aligning the respective center bores  64 ,  70 ,  33  and  28  of the adjacent holder plates  52 ,  68 ,  32  and  22  respectively within the upper portion  50  and the lower portion  16  of the die set arrangement  10  by virtue of their commonly machined and aligned bolt holes shown in the figures, the respective matable tool components secured respectively therein may be efficiently held and easily removably changed and re-inserted in perfect axial alignment. In one preferred embodiment of the present invention, the center punch holder plate  52 , the die holder plate  68 , the stripper holder plate  32 , and the compound punch holder plate  22  all may have an initial pilot bore drilled therethrough to establish the initial alignment thereof. The slight irregularity of those respective bores may be machined when the generally semicircular cut  86  is made in each respective holder plate  52 ,  68 ,  32  and  22 . Thus when a tool such as for example, the center punch  66  is clamped within its respective holder plate  52 , that irregular bore  64  within that holder plate  52  becomes a perfect circle by the biasing of the finger  84  by the adjustment bolt  96 . When no tool is clamped within the respective holder plates, the bore within those respective holder plates returns to its irregular and “out of round”, awaiting receipt of a tool therein.