Abstract:
A flexible counter for an embossing system provides resilient support under a sheet which opposes pressure from a contoured die forming an embossment in the sheet. The flexible counter includes a resilient mat and a fixed bolster which supports the mat. The bolster has peripheral walls which extend around sides of the mat so that an upper portion of the mat protrudes above the peripheral walls. In addition, the bolster includes a resilient bumper that bounds an upper portion of the mat. An upper edge of the bumper is about flush with an upper surface of the mat. The walls have a peripheral channel in which the bumper is disposed. The bumper is formed of a resilient material having higher rigidity than the mat, thereby controlling the flow and stretching behavior of the upper surface of the mat as compressed during an embossing operation.

Description:
FIELD OF THE INVENTION 
     The invention relates to a system for embossing paper, such as greeting cards, and more particularly relates to an embossing system having an improved flexible counter for supporting a sheet of paper for pressing by a contoured die. 
     BACKGROUND 
     Embossing systems are used to form an embossment or decoratively raised area on a sheet of paper or cardboard. Such an embossment may serve as a decorative feature on a greeting card, business card, or the like. Conventional embossing systems include matable male and female dies contoured in the shape of the desired embossment. With a sheet (e.g., paper) disposed between the two dies, the male and female dies are pressed together in complementary engagement with each other. The paper is thereby deformed to have an embossment matching the contour of the dies. 
     In an embossing system with mated dies, expenses are incurred for making both the male and female dies. Additionally, such a system requires regular attention to maintain precise die alignment for repeated mating engagement. 
     SUMMARY OF THE INVENTION 
     The present invention provides improved embossing performance in a system for embossing areas on greeting card material, paper or cardboard products or other items. A flexible counter is provided to support the material being embossed by opposing pressure against a contoured die. The flexible counter has a resilient mat which resides in a fixed bolster. According to an embodiment of the invention, a resilient seal or bumper is provided peripherally around upper sides of the flexible mat to contain the counter during compression between the dies. The bumper is made of a material that is more rigid than the mat, acting to “seal” flow behavior of the softer mat during compression. In other words, the bumper limits the lateral deformation and stretching of the mat, thereby preventing tearing of the embossed paper and optimizing embossing performance. 
     According to one aspect of the invention, the bolster has a sidewall secured to a table around a periphery of the mat, and the bumper surrounds an upper portion of the mat, fitting between the mat and the sidewall. For example, in an embodiment, the sidewall includes a channel to accommodate the bumper. The bumper resides, in a recessed fashion, in the channel, having an inner surface supported against the mat. The mat and bumper project a distance above the sidewall. 
     In an embodiment, the embossing system includes one or more plate-like shim that fits on the table under the mat. Advantageously, the shim permits use of a mat having a thickness dimension less than a depth from the upper edge of the bumper to the table. This enables the mat to be made of a variety of materials which may come in various stock thicknesses, thereby reducing cost. 
     Various embodiments of the invention provide multiple side-by-side bolsters for simultaneously embossing multiple panels of a sheet. For example, in an embodiment, the table can accommodate the installation of respective sidewalls, mats, and bumpers in one, two, three or more panel configurations as needed to suit a particular embossing job. 
     In an embodiment, the bumper is unitarily formed in a rectangular shape. In another embodiment, the bumper includes a plurality of strips, each of the strips fitting along a respective side of the rectangular mat. Together, the assembled strips extend around the periphery of the upper portion of the mat. 
     Embodiments of the invention include additional features found to enhance performance. For example, a friction-reducing film, such as a urethane or mylar film, may be positioned over the mat to separate the mat from the sheet. The friction-reducing film reduces damage to the sheet and aids in removing the sheet from the counter after embossing. The embossing system can include a frame sized to fit externally around a periphery of the sidewalls, and at least one of the edges of the sheet are secured to the frame. In an embodiment, two opposite sides of the sheet are clipped to respective sides of the frame using U-shaped clips. The frame is preferably constructed of steel or some other relatively heavy material so that the weight of the frame holds the film taut across the mat. In an automatic sheet-feeding environment, the sheet is clipped at ends along a feeding direction of the sheets. 
     An advantage of the present invention is that it provides reliable embossing performance while minimizing damage to the material being embossed. 
     Another advantage of the present invention is that it permits embossing with only a single contoured die, eliminating a need for a mated die, reducing material expenses. The invention permits the use of either a male or female contoured die. 
     A related advantage of the present invention is that it eliminates a need to maintain precise die alignment, reducing maintenance effort and associated down time of the system. 
     A further advantage of the invention is to provide a flexible counter with improved wear characteristics. 
     Additional features and advantages of the invention are described in, and will be apparent from, the disclosure herein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partially exploded perspective view of a flexible counter, including a flexible mat and a bolster constructed in accordance with teachings of the invention, the bolster having a unitary bumper. 
     FIG. 2 is a partially exploded perspective view of a flexible counter adapted for supporting multiple panels during embossing. 
     FIG. 3 is a sectional side view of a press assembly having a female die positioned above a flexible counter according to the invention. 
     FIG. 4 is a sectional side view of the press assembly of FIG. 3 in a compressed state. 
     FIG. 5 is a sectional side view of a press assembly having a male die compressing the flexible counter. 
    
    
     DESCRIPTION OF EMBODIMENTS 
     Now referring to the Figures, wherein like numerals designate like components, FIGS. 1-4 show a flexible counter  10  according to the invention. The flexible counter  10  includes a resilient mat  12 , a resilient bumper  14 , a rigid table  16 , and a plurality of walls  18 ,  20 ,  22 ,  24  mounted to the table  16 . The table, walls and bumper comprise a structure known as a “bolsterz” for supporting, containing and “sealing” the mat  12  during an embossing process during which the mat is compressed. 
     In general, the flexible counter  10  is configured to resiliently support a sheet  26  pressed against a contoured die  28  during an embossing operation, as shown in FIGS. 3 and 4. The flexible counter  10  is particularly useful in an automated embossing operation wherein embossments are formed on paper sheets during the manufacturing of greeting cards, business cards or the like. 
     FIG. 1 shows, in exploded view, the flexible counter  10  as configured for a single-panel embossment. It is noted, however, that the table  10  is preferably configured to accommodate the installation of additional walls to form additional counters. Such additional counters would enable the simultaneous embossing of multiple panels. For example, an embodiment with two adjacent counters could accommodate the embossing of both panels of a dual-panel, single-fold greeting card, and an embodiment with three adjacent counters could accommodate the simultaneous embossing of all panels of a three-panel, dual-fold greeting card. 
     In the illustrated embodiment, the table  16  has a plurality of grooves  30 , and each of the side walls  18 ,  20  and end walls  22 ,  24  includes a lower projection  32 ,  34  (FIGS. 3 and 4) adapted to be closely received within the groove. The fit of the projections  32 ,  34  within the grooves  30  provides secure mounting of the walls  18 ,  20 ,  22 ,  24 , even under high forces experienced against the mat  12  and bumper  14  during embossing. Additionally, each of the walls  18 ,  20 ,  22 ,  24  is provided with a plurality of bolt holes which receive respective bolts for snugly securing the respective walls to the table. In an embodiment, two or more of the plurality of walls  18 ,  20 ,  22 ,  24  can be an integral or unitary. 
     Referring to FIGS. 1 and 2, to accommodate the installation of walls to provide the counter  10  with additional panels, the table includes grooves  30  positioned to mountably receive such additional walls  120 ,  122 ,  124 . Within the walls  120 ,  122 ,  124  a second mat  112  is positioned to be supported by the table  16 . Furthermore a second bumper  114 - 117  is fitted around a periphery of the mat  112 . 
     For improving the compression behavior of the mat  12  during embossing, the bumper  14  extends around a periphery of the exposed portion of the mat  12 . More specifically, the bumper  14  fits around the sides of the mat  12 , between the mat  12  and the walls  18 ,  20 ,  22 ,  24 . In the illustrated embodiment, each of the walls  18 ,  20 ,  22 ,  24  is shaped to have a channel  36 ,  38  (FIGS. 3 and 4) against which the bumper is seated. The bumper  14  is constructed of a resilient material that is more rigid than the mat  12 , but not as rigid as the walls  18 ,  20 ,  22 ,  24 , which are preferably made of steel. The bumper  14  operates to laterally contain the portion of the mat  12  which projects vertically above the walls  18 ,  20 ,  22 ,  24 . 
     The bumper  14  may have one or more components. For example, the bumper  14  may be unitary, as in the rectangular embodiment illustrated in FIG. 1, or a bumper  14  may be provided of a plurality of elongate strips  114 ,  115 ,  116  and  117 , as illustrated in FIG.  2 . 
     The mat  12  fits closely within the four walls  18 ,  20 ,  22 ,  24  and is supported by the table  16 . Depending on the thickness of the mat  12 , the mat can rest directly on the table  16 , or alternatively, one or more plate-like shim  40  is provided between the table  16  and the mat  12  to result in the desired positioning of the upper mat surface generally flush with the top of the bumper  14 . 
     As shown in FIG. 3, the bumper  14  and mat  12  project above the walls  18 ,  20 ,  22 ,  24 . Additionally, the mat  12  and bumper  14  are dimensioned so that the upper surface of the mat  12  is flush with an upper edge of the bumper  14 . For example, the mat  12  protrudes above the walls  18 ,  20 ,  22 ,  24  by about 0.090 to 0.125 inch. 
     As mentioned, the desired mat level can be achieved by selecting a mat with a thickness to rest directly on the table or by selecting a mat  12  of some lesser thickness and placing one or more shim  40  (FIGS. 1,  3  and  4  ),  140  (FIG. 2) under the mat  12  to elevate the mat to the desired level. It should be noted that the mat material may be commercially available sheet form in certain stock thicknesses. The shim  40  advantageously permits the use of a mat  12  in a readily-available thickness. For example, mat material is commercially available in thicknesses of 0.25, 0.375, and 0.5 inches. It has been found that suitable behavior is achievable from a mat  12  having such thicknesses, used in conjunction with an appropriate shim  40 . It is believed that other mat thicknesses would also provide suitable behavior. 
     The mat  12  may be made of various natural or synthetic elastomers which have appropriate resilience. For example, natural gum rubber has been found to exhibit favorable properties. Other suitable materials may include buna-n rubber, neoprene, silicon, sorbothane, EPDM rubber, urethane, cotton, reinforced neoprene and hypalon. In one embodiment, the mat would have the following characteristics: 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 First Range 
                 Second Range 
                 Preferred 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Hardness 
                   
                   
                   
               
               
                 (Durometer) Shore A 
                 30-60 
                 35-45 
                 40 
               
               
                 Tensile Strength (psi) 
                 2000-6000 
                 3000-4500 
                 4000 
               
               
                 Heat Stability 
               
               
                 Fahrenheit 
                 −20°-300° 
                 −20°-140° 
                 175° 
               
               
                   
               
             
          
         
       
     
     The bumper  14  is constructed of a material that is resilient, yet firmer and more rigid than the mat  12  material. For example, various plastic or hard rubber materials are suitable, such as urethane. It has been found that a bumper works suitably well having sides with a width within a range of about {fraction (1/10 )}to {fraction (3/16)}in. and a height of about 0.25 in. Other sizes also work. 
     Turning to FIGS. 3 and 4, the contoured die  28  is mounted to oppose the counter  10 . The die  28  may have a female contour, having a recessed embossment image, as illustrated in FIGS. 3 and 4, or a die  228  may be used having a male contour as illustrated in FIG.  5 . For example, a typical emboss die  28  has a contour depth of about 0.06 to 0.08 inches or protrusion of 0.03 to 0.06 inches. The sheet  26  of material to be embossed is positioned between the flexible counter  10  and the opposing die  28 . Although the sheet  26  may be provided in various thickness, a standard thickness is about 0.010 inch. 
     For creating an embossment, the counter  10  and die  44  are movable toward each other. For example, the table is moveable upwardly (as illustrated), the die  28  is moveable downwardly, or both. A hydraulic press is typically used to drive the die  28  and counter  10  together. The counter  10  and contoured die  28  deformably press the sheet  26  to form an embossment thereon. For typical card embossing, the die compression stroke may continue beyond an initial contact between about 0.030 to 0.125 inch. 
     The sheet  26  may be paper, cardboard or some other deformable material suitable for embossing. The sheet  26  may be provided in precut sections or in the form of a continuous web, and may be positioned between the die  26  and flexible counter  10  by suitable automatic sheet-feeding equipment. 
     According to the invention, the flexible counter  10  supports the mat  12  in a controlled manner. Specifically, the mat deformation caused by pressure from the contoured die is directionally controlled, resulting in a “flow” behavior of the mat material which optimizes the embossing performance. In particular, the bumper  14  helps avoid undesirable lateral translation and stretching of the upper mat surface which reduces the risk of tearing the sheet  26 . 
     For example, as illustrated in FIGS. 3 and 4, the flexible counter  10  is effective to support one side of the sheet  26  during an embossing operation wherein the contoured embossing die  28  presses against an opposite side of the sheet  26  toward the flexible counter  10 . FIG. 3 illustrates the embossing system  8  when the die  28  and counter  10  are retracted apart from each other, and FIG. 4 illustrates the embossing system  8  when the die  28  and counter  10  are pressed together to emboss the sheet  26 . FIG. 5 illustrates a system  208  including the counter  10  and the male die  228  in a compressed state. 
     As the sheet  26  is embossed, the die  28  contacts against the sheet  26 , pressing against the bumper  14  and mat  12 . The resilient bumper  14  and mat  12  deform so that the mat  12  fills against contour of the die  28  and supports the sheet  26  under the embossed area. As mentioned, in an embodiment, the embossing stroke vertically compresses the mat and bumper between about 0.03 to 0.125 inch, and typically about 0.0625 inch beyond the initial contact. 
     An undesirable “witness mark” or “ghosting” effect can sometimes be formed on the sheet  26  where contacted by the bumper  14 . The embossed sheet may sized to not contact any portion of the bumper. However, some sheets may be too large to fit on only the mat area. For example, a sheet that forms a two-panel greeting card or three-panel greeting card typically lies across an edge  50  of the bumper. In such a case, the sheet  26  is preferably positioned so that the fold line of the card is aligned over the edge  50  of the bumper  14 . Also, that particular edge  50  (FIG. 1) of the bumper  14  which meets the fold line is thinner, having a narrow width (e.g., about 0.10 inch) in order to minimize the size and appearance of any resulting witness mark. 
     In an automated system wherein the sheets are repeatedly fed in a feed direction, it is desirable to reduce the risk of snagging. Accordingly, the end walls  22 ,  24  are shaped with a chamfered edge and positioned along the feeding direction. 
     As also illustrated in FIGS. 3 and 4, a friction-reducing film  44  is positioned between the mat  12  and the sheet  26 . The film  44  reduces friction between the mat  12  and the sheet  26 , thereby aiding to release the sheet  26  from the mat  12  after embossing and reducing a risk of damaging the sheet  26 . The film  44  may be made of mylar, urethane, or some other suitable material. A urethane film product marketed by Astor Universal, a Markem Company, 3841 Greenway Circle, Lawrence, Kans., USA, called “CC010 Countercast Tuff Film” has been found to serve as a suitable material for the film  44 . In one embodiment, the film may have a thickness of: 
     
       
         
               
               
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Range 
                 Preferred 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Thickness (inches) 
                 .003-.090 
                 0.010 
               
               
                   
                   
               
             
          
         
       
     
     For maintaining the film  44  in a taut position across the upper surface of the mat  12 , the embossing system includes a rectangular frame  46 . In a preferred embodiment, the frame  46  is shaped to extend exteriorly around the walls  18 ,  20 ,  22 ,  24 , and at least two ends of the film  44  are secured to the frame  46  by U-shaped clips  48  adjacent to the chamfered walls  22 ,  24 . The frame  46  is preferably made of a relatively heavy material, such as steel, so that the weight of the frame  46  holds the film  44  in place. The film  44  can be easily removed and replaced by lifting the frame  46  and removing the U-shaped clips  48 . A fresh film  44  can then be mounted to the frame  46  with the clips  48  and placed over the mat  12 . To further help reduce snagging, the film  44  is clipped at the two ends corresponding to the chamfered end walls  22 ,  24 , along the sheet feeding direction. 
     In FIG. 3, the die  28  and press counter  10  are illustrated in a retracted or lifted position. While the die  28  is retracted, the sheet  26  is placed between the film  44  and the die  28 , and the sheet  26  is positioned so that the desired area of the sheet  26  to be embossed is aligned under the die  28 . 
     Turning to FIG. 4, the press is actuated, thereby moving the table  16  upwardly to press the sheet  26  against the die  28 . The actuation pressure may vary from application to application depending on the type and thickness of the sheet material, the shape and depth of the embossment, and other factors. In general, for typical greeting card embossments, a die pressure of about 2000 psi may be suitable. In one embodiment, the pressure, dwell time and temperature for a Gietz Press or Bobst Press would be as follows: 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 First Range 
                 Second Range 
                 Preferred 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Pressure (psi) 
                 1000-10,000 
                 1000-5000 
                 2500 
               
               
                 Dwell Time (seconds) 
                 0-3.0 
                 0-0.8 
                 0.4 
               
               
                 Temperature 
                 80°-300° 
                 130°-210° 
                 165° 
               
               
                 (Fahrenheit) 
               
               
                   
               
             
          
         
       
     
     Still referring to FIG. 4, when the sheet  26  is pressed by the die, the sheet  26  contacts the film  44 , which in turn is pressed against the mat  12  and bumper  14 , which are supported by the walls  18 ,  20 ,  22 ,  24  and table  16 . The upper surface of the mat  12  presses upwardly against the sheet  26  (through the film  44  ), opposing the die force and complementarily deforming to the contour of the die  28 . The sheet  26  is embossed between the die  28  and the mat  12  to affect the desired embossment of the sheet  26 . The die  28  is subsequently retracted, and the embossed sheet  26  is removed. 
     Because the flexible counter  10  is resilient, the flexible counter  10  provides effective counter-support against a variety of die contours. The flexible counter  10  eliminates a need for an expensive cooperatively-shaped mating die. Accordingly, maintaining precise alignment of the flexible counter  10  relative to the die  28  is unnecessary. 
     While the invention is described herein in connection with certain embodiments, the invention is not limited to those embodiments. On the contrary, various changes and modifications to the described embodiments will be apparent to those skilled in the art, and such changes and modifications may be made without departing from the spirit and scope of the present invention.