Patent Publication Number: US-6904837-B2

Title: Clamp pieces for lower frame assembly of blanking tool

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a divisional of application Ser. No. 10/078,864, filed Feb. 20, 2002 now U.S. Pat. No. 6,769,342. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to die cutting machines for making carton blanks, and more particularly to a frame assembly for a lower blanking tool that supports carton scrap during a blanking operation in a die cutting machine. 
   In the manufacture of cartons, small sheets of paper material having specific profiles are cut out of larger sheets of paper material. These smaller sheets are known as carton blanks which, in turn, are formed into cartons and/or boxes. The blanks are formed during a process known as a blanking operation in a die cutting machine. 
   In a die cutting machine, the blanks are cut, but not removed from a large sheet of paper material. After the blanks have been cut, the sheet is moved downstream in the die cutting machine to a blanking station where the sheet is positioned over a frame assembly for support. The frame assembly includes an outer frame and an inner grid having large openings which correspond in size, in shape and in position to the profile of the carton blank previously cut. Below the frame is a mechanism for stacking the carton blanks. 
   At the blanking station, an upper tool is used in combination with the lower tool or frame assembly to knock the carton blanks from the sheet of paper material while holding the scrap material that surrounds the blanks. The upper tool has a support board that moves vertically up and down in the die cutting machine, and the support board typically has a plurality of stand-offs depending therefrom that hold pushers spaced beneath the board which in turn are used to push the carton blanks from the sheet through the lower tool or frame assembly. A plurality of presser assemblies are also mounted in the support board and depend therefrom to hold the scrap material against the lower tool or frame assembly during the blanking operation so that the blanks may be pushed from the sheet. A presser assembly typically includes a presser rail which is biased downwardly away from the support board by a spring so that the rail is positioned slightly below the pushers. As the upper tool is lowered, the presser rail engages the sheet of paper material first such that a scrap portion of the large sheet of material is secured between the presser rail and the frame. The upper tool then continues to be lowered such that the sheet of material engages the inner grid within the frame while at substantially the same time the pushers engage the carton blanks and knock the blanks out of the sheet of material and through the inner grid. The carton blanks then fall into a stacking mechanism below the frame where the blanks are stacked for further processing. 
   The lower tool used in the blanking operation is typically comprised of a steel outer frame that supports an inner grid. The inner grid is typically comprised of a plurality of lengthwise and crosswise extending bars. In order to secure the inner grid in place on the outer frame, the end of each bar is typically screwed onto attachment pieces which in turn are mounted on the lengthwise and crosswise rails of the outer frame. Since the frame and grid support a sheet of paper material during the blanking operation, the grid must be configured to match or conform to the die cut in the sheet of paper material. In addition, the grid must be reconfigured whenever a different carton blank needs to be produced. Thus, unscrewing the inner grid from the outer frame oftentimes becomes very cumbersome and time consuming. Thus, it is desirable to provide a quicker manner of attaching and removing the inner grid from the outer frame. 
   Other types of attachment pieces include wedges which are used to clamp the ends of the bars in place. Although these wedges provide a type of quick-connect and quick-disconnect for the bars of the grid, they also have the disadvantage of oftentimes moving the bars slightly during assembly. Movement of the bars, even slight movements thereof, result in the grid being misaligned with the die cut in the sheet of paper material which in turn may result in an imprecise blanking operation. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide an improved frame assembly for a lower blanking tool of a carton die cutting machine. 
   It is another object of the present invention to provide a frame assembly for a lower blanking tool that includes an inner grid that may be easily attached and removed from its supporting outer frame, can be precisely positioned during assembly, and yet maintains its rigidity during normal blanking operations. 
   It is yet another object of the invention to provide a frame assembly for a lower blanking tool which is easy to assemble, compatible with standard blanking operation machinery, and relatively inexpensive. 
   In order to accomplish the above objects, the present invention provides a frame assembly for a lower blanking tool of a carton die cutting machine. The frame assembly includes a rigid outer frame, and an inner grid comprised of a plurality of lengthwise and crosswise extending bars for supporting a sheet of die cut paper material during a blanking operation. The frame assembly also includes a plurality of clamps attaching the ends of the bars of the inner grid to the outer frame. Each clamp comprises an upright plate member defining a substantially flat vertically extending inner face, a substantially flat opposite vertically extending outer face, and a horizontally extending upper face. A substantially U-shaped upper cavity is formed in the inner face of the plate member and opens at its upper end to the upper face. The upper cavity defines an upper abutment surface, an opposite downwardly sloped surface disposed at an acute angle with respect to the upper abutment surface, and an upper support surface. An upper wedge member is disposed within the upper cavity for sliding movement along the downwardly sloped surface between clamped and released positions. The upper wedge is also substantially U-shaped and defines a clamping surface disposed parallel to and spaced from the upper abutment surface, an opposite downwardly angled surface disposed to engage against and slide along the downwardly sloped surface of the U-shaped upper cavity, and a base surface disposed substantially parallel to and spaced from the upper support surface of the cavity when the wedge member is in its clamped position. A screw extends through the upper wedge member into the upper support surface and is used to move the upper wedge between its clamped and released positions so as to hold or clamp the end of a bar of the inner grid between the abutment surface of the upper cavity and the clamping surface of the wedge member. 
   In another aspect, the invention includes the clamping device itself for attaching the bars of an inner grid to the outer frame of the lower blanking tool of a carton die cutting machine. The clamping device includes the upright plate member, U-shaped upper cavity and upper wedge member described above. However, in an alternate embodiment, the clamping device may also include a lower U-shaped cavity and a lower wedge member disposed within the lower cavity for sliding movement along an upwardly sloped surface between clamped and released positions. The lower cavity is preferably a mirror image of the upper cavity, and is used to clamp a bar of the inner grid at two points rather than only a single point if only the upper cavity and upper wedge is utilized. This is particularly useful to attach the lengthwise or machine direction bars of the inner grid as these bars may be taller than the crosswise bars. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate the best mode presently contemplated of carrying out the invention. 
     In the drawings: 
       FIG. 1  is a perspective view of a lower frame assembly for a blanking tool of a carton die cutting machine constructed in accordance with the principles of the present invention; 
       FIG. 2  is an enlarged perspective view illustrating a clamp device for attaching a bar of the inner grid to the outer frame of the lower frame assembly; 
       FIG. 3  is a front elevational exploded view of the clamping device of  FIG. 2 ; 
       FIG. 4  is a sectional view taken along the plane of the line  4 — 4  in  FIG. 3  of the clamp device; 
       FIG. 5  is a perspective view illustrating a second embodiment of the clamp device of the present invention; 
       FIG. 6  is a front elevational exploded view of the clamp device of  FIG. 5 ; 
       FIG. 7  is a sectional view taken along the plane of the line  7 — 7  in  FIG. 6  of the clamp device illustrated therein; 
       FIG. 8  is a perspective view illustrating a third embodiment of the clamp device of the present invention; 
       FIG. 9  is a front elevational view of the clamp device illustrated in  FIG. 8  with the two clamping wedges removed; 
       FIG. 10  is a sectional view taken along the plane in line  10 — 10  in  FIG. 9  of the clamp device illustrated therein; 
       FIG. 11  is a perspective view, partially in section, illustrating a stiffening assembly for a side rail of the outer frame; 
       FIG. 12  is a perspective exploded view illustrating a prior art clamp device for attaching a bar of the inner grid to the outer frame of the lower frame assembly for a blanking tool; and 
       FIG. 13  is a front elevational exploded view of the prior art clamp device of FIG.  12 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings,  FIG. 1  illustrates a lower frame assembly generally designated by the numeral  1  which is used in a blanking tool of a die cutting machine for converting or processing a sheet of paper material into a carton blank. These machines are well known in the art and are used to cut one or several blanks into each sheet of paper material which, after folding and gluing, may be formed into cartons or boxes. As is conventional, the sheets of paper material move in a substantially horizontal plane within the machine and are carried through various sequences of printing, cutting, embossing, creasing, waste stripping and/or blanking stations. 
   The die cutting machine usually is formed by a series of stations with the first station being a starting position or input station in which the sheets, which may be preprinted if desired, are taken one by one from the top of a stack to a feed table where they are placed in position against frontal and side guides. The sheet can then be grasped by a gripper bar and lead downstream or in the machine direction into subsequent processing stations. Typically, the sheet is first conveyed into a cutting station where the carton or box blanks of a desired size and profile are die cut into the sheet. These blanks are held to the sheet by knicks which are arranged along the cut edges of the blanks. This cutting station is usually comprised of upper and lower tools, one of which is provided with a plurality of line-shaped straight and curved die cutting blades. If desired, the cutting station may be proceeded by a printing station, or as noted above, the sheets may be preprinted. After cutting, the sheet is then lead to a stripping station where the waste, i.e. the unused scrap between the various blanks, are grasped by upper and lower pins in order to be lead downward into a waste container. The sheet is then fed to a blanking station where the sheet is positioned horizontally over a lower frame for support. The lower frame includes an inner grid having large openings which correspond in size, in shape and in position to the profile of the blank previously cut. An upper blanking tool having one or more presser assemblies mounted thereto then moves vertically downwardly in the die cutting machine to secure the scrap portions against the grid and frame and then as the tool continues to move downwardly, the fasten points or knicks between the blanks and the sheet are broken by pushers so that each of the blanks are released, pushed through the grid and falls below the frame where the blanks are stacked for further processing. Finally, the residual or remaining portion of the sheet is carried into a delivery or exit station where it is released by the gripper bar as waste material. 
   Referring now to  FIG. 1 , there is illustrated frame assembly  1  for a lower blanking tool of a carton die cutting machine. The lower frame assembly  1  includes an outer frame comprised of a pair of opposite, spaced apart longitudinally extending side frame members or side rails  2  and  3 , and a pair of opposite, spaced apart cross frame members or cross rails  4  and  5  extending crosswise between side rails  2  and  3 . Arrow  6  illustrates the machine direction, i.e. the direction of movement of a sheet of paper material (not shown) within the die cutting machine. Thus, as illustrated in  FIG. 1 , side rail  2  would be considered the left side rail while side rail  3  would be considered the right side rail. Likewise, cross rail  4  would be considered the front or leading cross rail while cross rail  5  would be considered the rear or trailing cross rail. As illustrated, cross rails  4  and  5  each have a length such that their opposite ends overlap the opposite ends of side rails  2  and  3 . Also, cross rails  4  and  5  are disposed on top of side rails  2  and  3  so that the lower surface of cross rails  4  and  5  abut against the upper surfaces of side rails  2  and  3 , as will hereinafter be described. 
   Side rails  2  and  3  are rigidly interconnected to cross rails  4  and  5  by means of a plurality of corner pieces  7 - 10 . Corner pieces  7  and  9  are referred to herein as right corner pieces while corner pieces  8  and  10  are referred to herein as left corner pieces. The terms “right” and “left” refer to the location of a tenon on the underside of each corner piece (see  FIG. 7  versus FIG.  11 ), but it should be noted that left corner pieces  8  and  10  are essentially mirror images of right corner pieces  7  and  9 . Corner pieces  7 - 10  are used to rigidly interconnect rails  2 - 5  to one another, and function like clamps to tightly hold rails  2 - 5  together in a “square” or 90° relationship, as will hereinafter be described. 
   The inner grid is composed of a plurality of parallel lengthwise bars  11  extending in the machine direction between front rail  4  and rear rail  5 , and a plurality of substantially parallel crosswise bars  12  extending transversely to the machine direction  6  between left rail  2  and right rail  3 . Bars  11  and  12  of the inner grid can be point welded or glued with adhesive at the points where they intersect to insure rigidity of the inner grid. Bars  11  are attached to cross rails  4  and  5  by means of a plurality of attachment pieces or clamp devices  13 . Likewise, bars  12  are attached to side rails  2  and  3  by a plurality of attachment pieces or clamp devices  14 . It should be noted that the present invention is not limited to the design for the inner grid illustrated in  FIG. 1  as the design illustrated is but one example of an inner grid design. In fact, the profile of the inner grid is typically changed depending upon the type, size and shape of the carton blank to be produced. Thus, the inner grid illustrated in  FIG. 1  is for illustration purposes only. 
   Referring now to  FIG. 11 , there is illustrated in more detail the interconnection of left side rail  2  to front cross rail  4  by corner piece  7 . More specifically, cross rail  4  includes an upper surface  15 , an opposite lower surface  16 , an outer surface  17 , and an opposite inner surface  18 . Each surface  15 - 18  is substantially planar, and surface  18  is referred to as the “inner” surface since it faces the interior of frame assembly  1 , i.e. towards the inner grid. As shown best in  FIG. 11 , rail  4  includes a bolt receiving T-shaped slot  19  formed therein. Slot  19  is formed throughout the entire elongate length of rail  4  and opens to both of the opposite ends of rail  4 . Slot  19  has a blind end located within the interior of rail  4  and has an open end which opens to inner surface  18 . Slot  19  defines a downwardly extending axis  20  disposed at an acute angle  21  with respect to the plane of inner surface  18 . As shown in  FIG. 11 , acute angle  21  is defined as the angle between axis  20  and the plane of inner surface  18 . Acute angle  21  may be an angle between 1° and 89°, but is preferably an angle of about 30° to about 80°, and most preferably an angle of about 65°. 
   As shown in  FIG. 11 , rail  4  also includes an inwardly projecting ledge  22  formed in inner surface  18 . Ledge  22  is planar in shape and is disposed at an angle of 90° with respect to inner surface  18 . However, ledge  22  could also be modified to be at an acute angle with respect to inner surface  18  if desired. As shown, ledge  22  is located at the intersection of the upper surface  15  and inner surface  18  of rail  4  such that ledge  22  is located between upper surface  15  and T-shaped slot  19 . Ledge  22  extends along the entire length of rail  4  and opens to both of the opposite ends of rail  4  in a manner similar to slot  19 . 
   Rail  4  further includes a channel-shaped recess  23  formed in upper surface  15 . Recess  23  is formed and extends along the entire length of rail  4  and opens to both of the opposite ends of rail  4 . Recess  23  is typically utilized to receive a ruler or other measuring device which aids in the proper placement of attachment members or clamp devices  13  and  14  when building the inner grid. 
   Rail  4  also includes a V-shaped cavity  24  formed in its outer surface  17 . Again, as with slot  19 , ledge  22  and recess  23 , cavity  24  is formed along the entire length of rail  4  and opens to both of the opposite ends of rail  4 . Typically, each face of cavity  24  is formed at a 60° angle to a horizontal line running through the center thereof. The function of cavity  24  is to locate a linear scale for measuring placement of the bars  11 ,  12  for the inner grid. 
   Front cross rail  4  also includes a reinforcement or stiffening member  25  which minimizes the flexing of rail  4  during a blanking operation. Reinforcement member  25  projects outwardly from outer surface  17  and is formed along the entire length of rail  4 . Although illustrated as being integral with rail  4 , reinforcement member  25  could also be a separate piece which could be removably attached with fasteners if desired. Also, although illustrated as having a lower surface  26  contiguous with lower surface  16  of rail  4  and a chamfered surface  27  contiguous with outer surface  17 , reinforcement member  25  could take other shapes and be positioned in a slightly different location than illustrated so long as it functions to stiffen front cross rail  4 . 
   The cross sectional profile of rear cross rail  5  is identical to front cross rail  4  with the exception that rail  5  does not include the reinforcement or stiffening member  25 . Since rail  5  is identical to rail  4  with the exception of reinforcement member  25 , like numbers, except utilizing the designation “A” therewith, are utilized to refer to like parts or elements. 
   As illustrated, cross rails  4  and  5  are elongated members having opposite ends and a length greater than either its height or its width. Rail  5  and rail  4  (without reinforcement member  25 ) have a height greater than their width, and are formed of aluminum, preferably extruded aluminum. Extrusion techniques provide the most efficient and cost effect method of producing an aluminum rail having the profile illustrated in FIG.  11 . 
   Referring now to  FIGS. 1 and 11 , there is illustrated the cross sectional profile of side rails  2  and  3 . The profiles of rails  2  and  3  are identical, and therefore only one will be described, i.e. side rail  2 . As illustrated, side rail  2  is an elongate member having a length greater than either its height or its width. However, rail  2  has a width which is slightly greater than its height which enables it to accommodate the additional slot to hereinafter be described. Again, as with rails  4  and  5 , rails  2  and  3  are composed of aluminum, preferably extruded aluminum. As illustrated, rail  2  has an upper surface  28 , an opposite lower surface  29 , an outer surface  30  and an opposite inner surface  31 . Surfaces  28 - 31  are substantially planar in shape and are formed along the entire length of rail  2  and extend completely between opposite ends of rail  2 . As shown best in  FIG. 11 , rail  2  includes a bolt receiving T-shaped slot  32  formed therein throughout the entire length thereof. Slot  32  defines a downwardly extending axis  33  disposed at an acute angle  34  with respect to the plane defined by inner surface  31 . Acute angle  34  may be any angle between 1° and 89°, but is preferably between about 30° to about 80° and is most preferably about 65°. Slot  32  has a blind end located within rail  2  and has an open end which opens to inner surface  31 . Slot  32  is formed along the entire length of rail  2  and is open to both of the opposite ends of rail  2 . 
   As shown in  FIG. 11 , rail  2  further includes a second bolt receiving T-shaped slot  35  formed therein. Slot  35  is identical to slot  32  in shape and also defines a downwardly extending axis  36  disposed at an acute angle  37  with respect to upper surface  28 . As with angle  34 , acute angle  37  may be any angle between about 1° to about 89°, but is preferably between about 30° to about 80° and most preferably about 65°. Slot  35  is formed along the entire length of rail  2  and opens to both of the opposite ends of rail  2 . As illustrated, slot  35  has a blind end located within rail  2  and an open end which opens to upper surface  28 . The blind end of slot  35  (as well as the blind end of slots  19  and  32 ) is configured to conform to the shape of a nut (not shown) captured therein. The nut is utilized to threadedly receive and hold the shank of a bolt extending into slot  35  (as well as slots  19  and  32 ), as will hereinafter be described. 
   As illustrated, rail  2  also includes a channel-shaped recess  38  formed in upper surface  28 . Recess  38  is formed in upper surface  28  between slot  35  and inner surface  31 , and functions to receive a ruler or other measuring device to aid in building the inner grid in a manner similar to recess  23  in rails  4  and  5 . Recess  38  is formed throughout the entire length of rail  2  and opens to both of the opposite ends thereof. 
   As shown best in  FIG. 11 , rail  2  also includes an angled groove  39  formed in inner surface  31  above slot  32 . Again, groove  39  is formed through the entire length of rail  2  and opens to both of the opposite ends thereof. As illustrated, groove  39  includes an inwardly projecting ledge  40 , and an angled surface  41 . Ledge  40  has a planar surface and is disposed at an angle of about 90° with respect to inner surface  31 . Other acute angles for ledge  40  may be used, but 90° is preferred. Angled surface  41  forms an acute angle with ledge  40  which angle is generally between about 30° to about 80°, but is preferably about 70°. Groove  39  functions to receive a tenon of corner piece  7  as will hereinafter be described. 
   Corner piece  7  is also illustrated in FIG.  11 . As noted earlier, corner piece  7  is identical to corner piece  9  while corner pieces  8  and  10  are mirror images thereof. More specifically, corner piece  7  interconnects side rail  2  and front cross rail  4  of the lower blanking tool frame assembly, and includes an L-shaped body having a horizontal plate member  43  and an upright or vertical plate member  44 . Horizontal plate member  43  defines a substantially flat upper face, a substantially flat opposite lower face, an inside face, an opposite outside face and an end face. As illustrated, each of these faces are substantially planar in shape. Upright or vertical plate member  44  also defines a substantially flat inner face contiguous with the upper face of plate member  43 , a substantially flat outer face contiguous with the lower face of plate member  43 , an inside face contiguous with the inside face of horizontal plate member  43 , an opposite outside face contiguous with the outside face of horizontal plate member  43 , and a top face. Horizontal plate member  43  has a pair of adjacent, aligned outwardly and downwardly extending bolt receiving bores formed therethrough extending between its upper face and lower face. Each bore defines an axis disposed at an acute angle with respect to the upper face of plate member  43 . The acute angle may be between about 1° and 89°, but preferably between about 30° and about 80°, and most preferably about 65° to match angle  37  of slot  35 . 
   Upright or vertical plate member  44  also includes a pair of adjacent, aligned outwardly and downwardly extending bolt receiving bores formed therethrough from its inner face to its outer face through which bolts  47  and  48  extend into T-shaped slot  32 . Each bore defines an axis disposed at an acute angle with respect to the inner face of plate member  44 . Again, this acute angle may be anywhere between 1° and 89°, but is preferably between about 30° and about 80°, and is most preferably about 65° to match angle  34  of slot  32 . 
   Upright plate member  44  has a lip  49  projecting outwardly therefrom. Lip  49  has an upper surface and a lower surface. The upper surface of lip  49  is contiguous with the top face of plate member  44  while its lower surface is contiguous with the outer face of plate member  44 . Lip  49  is disposed substantially 90° with respect to the outer face of plate member  44 , and lip  49  extends completely across the outer face of plate member  44 . Although illustrated as being contiguous with the top face of plate member  44 , lip  49  could also be spaced slightly downwardly therefrom if desired. Also, lip  49  need not necessarily extend completely across the outer face of plate member  44 , but preferably does so to provide the maximum amount of clamp force against ledge  22 , as will hereinafter be described. 
   Corner piece  7  also includes a tenon  50  projecting downwardly from horizontal plate member  43 . Tenon  50  has an angled surface disposed at an acute angle with respect to the lower face of plate member  43 . This acute angle may be any angle between 1° and 89°, but preferably matches the angle formed by surface  41  of groove  39  in side rail  2 . Again, by matching the angle of surface  41  the maximum amount of friction is provided between tenon  50  and surface  41  to provide the maximum clamping force, as will hereinafter be described. Finally, corner piece  7  includes a pair of reinforcement members or blocks  52  and  53  located at the intersection of upright plate member  44  and horizontal plate member  43 . As shown best in  FIG. 11 , each block  52 ,  53  preferably comprises a wedge-shaped or triangular-shaped member. 
   Left corner pieces  8  and  10  are mirror images of right corner pieces  7  and  9 , and therefore need not be described herein in detail, but identical parts utilize like numerals with the designation “A” therewith. Corner pieces  8  and  10  are referred to as “left” corner pieces since tenon  50 A is located on the left side thereof. In like manner, corner pieces  7  and  9  are referred to as “right” corner pieces since tenon  50  is located along the right side thereof. In all other respects, corner pieces  8  and  10  are identical to corner pieces  7  and  9 . 
   In order to assemble frame assembly  1 , cross rails  4  and  5  are placed on top of side rails  2  and  3  so that the ends of rails  2 - 5  overlap one another, as illustrated in FIG.  1 . Thereafter, right corner piece  7  is placed as illustrated in  FIG. 11  with lip  49  engaging ledge  22  in cross rail  4 , and tenon  50  engaging groove  39  formed in side rail  2 . Bolts  45  and  46  are then inserted through the bores in plate member  43  into corresponding nuts contained in slot  35  of side rail  2 . As bolts  45  and  46  are tightened, they engage the nuts to pull or clamp cross rail  4  tightly against side rail  2 . At the same time, bolts  47  and  48  extend through the bores of upright plate member  44  into nuts captured within slot  19  of cross rail  4 . As bolts  47  and  48  are tightened, they pull or clamp the upper surface  29  of side rail  2  tightly against the lower surface  16  of cross rail  4 . In this manner, rails  2  and  4  are rigidly interconnected. Thereafter, in a like manner, corner pieces  8 - 10  are utilized to rigidly interconnect the other three corners of frame assembly  1 . As a result, rails  2 - 5  are rigidly interconnected to one another to form frame assembly  1 . 
   As illustrated best in  FIG. 1 , the second T-shaped slot  32  formed in inner surface  41  of side rails  2  and  3 , is utilized to connect a plurality of attachment pieces or clamp pieces  14  for crosswise bars  12  of the inner grid. In like manner, the T-shaped slots  19  and  19 A formed in cross rails  4  and  5 , are also utilized to connect attachment pieces or clamp devices  13  for mounting lengthwise bars  11  of the inner grid. 
   Clamp devices  13  of the present invention are illustrated in  FIGS. 2-4 . For comparison, a prior art clamp device  108  is illustrated in  FIGS. 12 and 13 . As illustrated, the prior art clamp device  108  includes an upright plate member  109 , a U-shaped cavity  110  formed completely therethrough at its upper end, a wedge member  111  disposed within cavity  110  for sliding movement between a lower clamped position and an upper released position, and a screw member  112  extending vertically through wedge member  111  into plate member  109  for moving wedge member  111  between its clamped and released positions. Openings  113  and  114  extend transversely through the lower end of plate member  109  at a 90° angle to the faces of plate member  109  to receive bolts (not shown) for attaching the clamp device  108  to the rails of the lower frame assembly. 
   As illustrated in  FIGS. 2-4 , clamp device  13  of the present invention includes an upright plate member defining a substantially flat vertically extending inner face  54 , a substantially flat opposite vertically extending outer face  55 , a horizontally extending upper face  56 , an opposite horizontally extending lower face  57 , and a pair of opposite end faces  58  and  59 . Together, faces  54 - 59  define a rectangular shape solid plate-like body composed of steel or aluminum. Although illustrated as having a height greater than either its length or width, clamp piece  13  may have other geometric shapes depending upon its end use. 
   A lip  60  is formed on the outer face  55  of clamp piece  13 . Lip  60  projects substantially 90° with respect to outer face  55 , and extends completely across face  55  to extend between end faces  58  and  59 . Although illustrated as being located approximately two-thirds of the distance between upper face  56  and lower face  57 , lip  60  could also be positioned slightly upwardly or downwardly from the location illustrated in FIG.  2 . Also, lip  60  need not necessarily extend completely across face  55 , but preferably does so to provide the maximum amount of clamp force against ledge  22  formed in cross rails  4  and  5 . 
   A substantially U-shaped upper cavity or recess  61  is formed in inner face  54 , and opens at its inner end to the inner face  54  and at its upper end to upper face  56 . Cavity  61  defines an upper abutment surface  62  which extends vertically in a plane parallel to end faces  58  and  59 , and is disposed at a 90° angle with respect to inner face  54 . Abutment surface  62  as well as cavity  61  has a depth, i.e. extends into clamp device  13 , approximately two-thirds of the distance between inner face  54  and outer face  55 , and surface  62  includes a plurality of parallel vertically extending score lines  63  formed therein. Score lines  63  aid in providing friction to hold the outer ends of bars  11  of the inner grid, as will hereinafter be described. Cavity  61  also defines a downwardly sloped concave surface  64  disposed opposite of abutment surface  62  and at an acute angle  65  with respect to abutment surface  62 . As illustrated best in  FIG. 3 , sloped surface  64  extends downwardly and away from end face  59  so that the lower end of cavity  61  is narrower than the upper end of cavity  61 . Acute angle  65  is preferably between about 5° and about 45°, and most preferably about 15°. Finally, cavity  61  also defines a horizontally extending upper support surface  66 . Surface  66  is substantially parallel to upper face  56  and extends 90° with respect to inner face  54 . Cavity  61  is also defined by a rear wall  67 . Rear wall  67  includes a rear surface  68  extending vertically in a plane parallel to inner face  54  and outer face  55 . 
   An upper wedge member  69  is disposed within upper cavity  61  for sliding movement along the downwardly sloped surface  64  between a clamped position (i.e. at or toward the lower or narrower end of cavity  61 ) wherein the end of bar  11  is fixed in place, and a released position (i.e. at or toward the upper or wider end of cavity  61 ) wherein the bar  11  may be removed from cavity  61 . As illustrated, wedge member  69  is substantially U-shaped in profile to substantially match the U-shaped profile of upper cavity  61 . Wedge member  69  includes a vertically extending clamping surface  70  disposed in a plane parallel to and spaced from abutment surface  62 . Clamping surface  70  also includes a plurality of parallel spaced score lines (not shown) formed therein for aiding in providing friction to hold bar  11  between surfaces  70  and  62 . Wedge member  69  also includes a downwardly angled convex surface  72  disposed opposite clamping surface  70 . Angled surface  72  functions to engage against and slide along downwardly sloped concave surface  64  of cavity  61  so as to move surface  70  of wedge member  69  into a position more closely adjacent to abutment surface  62  as wedge member  69  moves downwardly along surface  64 . This action provides the clamping force necessary for clamping an end of a bar  11  between abutment surface  62  and clamping surface  70  as wedge member  69  moves downwardly into cavity  61 . Concave surface  64  and convex surface  72  also function to capture or contain wedge member  69  and essentially lock it in position within cavity  61  so it does not laterally move therein as wedge member  69  moves downwardly to its clamping position. Wedge member  69  also includes a base surface  73  at its lower end disposed substantially parallel to support surface  63 . Base surface  73  typically remains spaced from support surface  66  when the wedge member  69  is in its clamped position. Wedge member  69  also includes an inner substantially flat surface  74  disposed substantially flush with inner face  54 , and an outer substantially flat surface  75  which bears against and slides along surface  68  of rear wall  67  as wedge member  69  moves between its clamped and released positions. As illustrated, rear wall  67  contains wedge member  69  within cavity  61 , and it aids in properly locating wedge member  69  during assembly. Wall  67  also reinforces or stiffens the sides of clamp device  13  and prevents the upper end of cavity  61  from spreading apart as wedge member  69  moves downwardly to its clamping position. 
   As a means for moving upper wedge member  69  between its clamped and released positions,  FIG. 2  illustrates a screw member  76  which extends vertically through wedge member  69  into support surface  66 . Wedge  69  includes a bore  77  formed therethrough and opening to base surface  73  together with a counterbore  78  opening to top surface  79  so as to enable the head of screw  76  to be flush with surface  79  when wedge member  69  is in its clamped position. An internally threaded bore  80  is formed through a cross member  81  for receiving the externally threaded shank of screw  76 . In this manner, as screw  76  is turned into threaded bore  80 , wedge member  69  moves downwardly along surface  64  until clamping surface  70  engages one side of bar  11  and forces it against abutment surface  62 . As screw  76  is tightened, additional clamping force is applied against bar  11  so as to rigidly clamp bar  11  between abutment surface  62  and clamping surface  70 . To release bar  11 , screw  76  is merely turned in a counterclockwise direction until wedge  69  moves away from bar  11  to release the clamping pressure applied thereto so that bar  11  can be removed from cavity  61 . 
   In order to attach clamp device  13  to cross rails  4  and  5 , a rectangular recess  82  is formed in inner face  54  to define a lower wall  83  separated by cross member  81  from upper cavity  61 . A downwardly and outwardly extending bolt receiving bore  84  is formed through lower wall  83 . Bore  84  defines an axis  85  disposed at an acute angle  86  with respect to outer face  55 . The acute angle  86  may be anywhere between 1° and 89°, but is preferably between about 30° and about 80°, and is most preferably about 65° to match the angle  21  defined by slot  19  in cross rail  4 . A bolt  87  extends through bore  84  into a nut (not shown) captured within slot  19 . As bolt  87  is tightened, lip  60  is pulled tightly against ledge  22  of rail  4  while at the same time outer face  55  is forced to bear tightly against inner face  18  of cross rail  4  to rigidly hold clamp piece  13  in position on cross rail  4 . 
   Referring now to  FIGS. 5-7 , there is illustrated clamp devices  14  for attaching the ends of crosswise bars  12  to side rails  2  and  3 . Clamp pieces  14  are identical to clamp pieces  13  with the exception that clamp pieces  14  are slightly taller than clamp pieces  12 . Since clamp pieces  14  are substantially identical to clamp pieces  13 , like numbers, except utilizing the designation “A” therewith, are utilized to refer to like parts or elements. It should be noted that lip  60 A formed on outer face  55 A of clamp piece  14  is located approximately one-third to one-half the distance between upper face  56 A and lower face  57 A thus enabling crosswise bars  12  to be spaced upwardly from side rails  2  and  3  at substantially the same height as lengthwise bars  11 , as seen best in FIG.  1 . Also, it should be noted that recess  82 A is also substantially taller in clamp piece  14  than recess  82  is in clamp piece  13 . In all other respects, clamp pieces  14  are substantially identical to clamp pieces  13 , and need not be further described herein. 
   Referring now to  FIGS. 8-10 , there is illustrated a third embodiment of the clamp pieces of the present invention. This third embodiment is generally designated by the numeral  88 , and as best shown in  FIG. 8 , provides a double clamping arrangement whereby the end of a rail or other component utilized with a lower blanking tool may be clamped securely in place on cross rails  4  or  5 . Clamp piece  88  includes an upper wedge member  69 B disposed within a U-shaped upper cavity  61 B together with a lower wedge member  69 C disposed within a lower U-shaped cavity  61 C. Wedge members  69 B and  69 C as well as cavities  61 B and  61 C are identical to wedge member  69  and cavity  61  previously described herein with respect to  FIGS. 2-4 . Since the components of clamp piece  88  are substantially identical to the components of clamp pieces  13  and  14  previously described herein, like numbers, except utilizing the designation “B” for the upper components and “C” for the lower components, are utilized in  FIGS. 8-10  to refer to like parts or elements. The only significant differences between clamp piece  88  and clamp pieces  13  and  14  previously described herein is that abutment surface  89  forms a continuous uninterrupted abutment surface extending between upper face  56 B and lower face  57 B. In addition, cross member  81 B does not extend completely to abutment surface  89 , but instead has an end face  90  which is spaced from abutment surface  89 . Additionally, lip  60 B is formed at upper face  56 B and is contiguous therewith rather than being located between upper face  56 B and lower  57 B as for clamp pieces  13  and  14 . Lastly, this third embodiment includes a single screw  91  which simultaneously moves upper wedge  69 B and lower wedge  69 C to their clamped positions as it is turned down in a clockwise direction. In order to accomplish this, screw  91  extends vertically into upper wedge  69 B, through cross member  81 B and vertically through lower wedge member  69 C. Thus, as screw  91  is turned in a clockwise direction, lower wedge  69 C is pulled upwardly along the upwardly sloped surface  64 C while upper wedge  69 B is pushed downwardly along downwardly sloped surface  64 B until their respective clamping surface  70 C and  70 B engage and hold a component against abutment surface  89 . To release the component, screw  91  is merely turned in a counterclockwise direction so that upper wedge  69 B moves upwardly and lower wedge  69 C moves downwardly away from abutment surface  89 . 
   Clamp piece  88  also includes a pair of aligned outwardly and downwardly extending bolt-receiving bores  92  and  93  formed therethrough through which bolts  94  and  95  extend into the T-shaped slots of rails  4  or  5 . Each bore  92 ,  93  defines an axis  96  disposed at an acute angle  97  with respect to the outer face  55 B of clamp piece  88 , as shown best in FIG.  10 . Acute angle  97  may be anywhere between 1° and 89°, but is preferably about 30° to about 80°, and is most preferably about 65° to match the angles of the T-shaped slots. Thus, as bolts  94  and  95  are turned clockwise, they engage nuts (not shown) contained in the T-shaped slot of rails  4  or  5 . As bolts  94  and  95  are tightened, they engage the nuts to pull clamp piece  88  so that its outer face  55 B tightly engages the inner face of the rail. In this manner, clamp piece  88  is rigidly connected to a rail  4  or  5  so that lip  60 B engages the ledge  22  formed in cross rail  4  or cross rail  5 . 
   Referring now to  FIG. 11 , there is illustrated a stiffening assembly for one or both of side rails  2  and  3 . As illustrated, the stiffening assembly comprises a longitudinally extending angle member  98  having a length substantially the same as the length of side rail  2  or side rail  3 . Angle member  98  includes a horizontal leg  99  and a vertical leg  100  disposed at 90° to one another. Angle member  98  may be composed of any suitable material, but is preferably steel having sufficient strength to stiffen the aluminum side rails  2  or  3 . As illustrated, vertical leg  100  has a longitudinally extending V-shaped groove  101  formed therein. The opposite side of leg  100  defines a planar face which bears or abuts against the outer face  55 A of clamp pieces  13 , as illustrated. Clamp pieces  13  each include a V-shaped cut  102  formed horizontally across its outer face  55 A. The stiffening assembly also includes a C-shaped jaw  103  having a pair of opposite parallel legs  104 ,  105  with leg  105  being slightly longer than leg  104  and the terminal ends of which are rounded for engagement within V-shaped groove  101  and V-shaped cut  102 . To complete the assembly, a screw  106  extends through wall  107  of C-shaped jaw  103  into clamp piece  13 . Thus, as screw  106  is turned down in a clockwise direction, jaw  103  is moved toward clamp piece  13  so that leg  104  engages V-shaped groove  101  and leg  105  engages V-shaped cut  102  until angle member  98  is rigidly in place. As a result, angle member  98  stiffens side rail  2  or  3  to prevent any significant flexing thereof during a blanking operation.