Paper embossing system with a flexible counter and method of embossing

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 a peripheral wall which extends around sides of the mat so that an upper portion of the mat protrudes above the peripheral wall. In addition, the bolster includes support surfaces bounded by recesses. The support surfaces support a bottom surface of the mat, and the recesses receive bulging portions of the mat when compressed under pressure from the die.

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 female 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.
 Attempts have been made to eliminate the male die component by instead
 providing a flexible "counter" to support a paper being pressed by the
 female die. Unfortunately, known flexible counter systems have not
 provided suitable embossing results. Basically, known counters include a
 flexible mat which supports the paper during pressing by female die. Some
 known counters include a structure that contains all but one side of the
 mat. These known flexible counters often tear the paper during embossing
 or result in an unsuitable embossment. Such performance shortcomings may
 be due to poor deformation behavior or "flow" characteristics of the mat
 as supported by these known counters.
 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 from a female die. The flexible
 counter has a resilient mat which resides in a fixed bolster. According to
 the invention, the bolster is constructed to form recesses which receive
 bulging deformation of the mat material as the mat is compressed by the
 opposing die forces. By accommodating bulging of lower portions of the
 mat, deformation of upper portions of the mat are controlled to reduce
 stretching behavior of the upper mat surface which supports the sheet, and
 thereby optimize embossing performance.
 According one aspect of the invention, the bolster has a sidewall which
 extends generally around a periphery of the mat so that an upper portion
 of the thickness of the mat extends above the sidewall. Another aspect of
 the invention provides that the bolster has at least one support surface
 which is adjacent to a recess. The support surface supports a bottom
 surface of the mat, and the recess receives a bulging portion of the mat
 as the mat deforms under compression of the embossing die.
 In an embodiment, the bolster has a plurality of support surfaces. These
 support surfaces may be formed by buttons of various shapes, loop-shaped
 elements or other appropriately-shaped support members. The bolster may
 also have a fixed floor to which such support members and sidewalls are
 mounted. The buttons or other support members are preferably spaced apart
 from each other to form the recesses.
 Embodiments of the invention may include additional features found to
 enhance performance. For example, a friction-reducing film, such as a
 mylar or urethane 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.
 A recess may be provided around a lower periphery of the mat. In an
 embodiment, such a peripheral recess may be defined by a chamfered
 interior edge of the sidewall.
 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 a female die, eliminating a need for a mated male die, reducing
 material expenses.
 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.
 Additional features and advantages of the invention are described in, and
 will be apparent from, the disclosure herein.

DESCRIPTION OF EMBODIMENTS
 Now referring to the Figures, wherein like numerals designate like
 components, FIG. 1 shows a flexible counter 10 according to the invention.
 The flexible counter 10 generally includes a bolster 20 and a generally
 rectilinear resilient mat 22 supported by the bolster 20. The flexible
 counter 10 is constructed to resiliently support a sheet 24 (FIGS. 2-4 )
 during an embossing operation and 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.
 As illustrated in FIGS. 1 and 3, the bolster 20 generally includes a
 plate-like floor 26, four side walls 28 mounted relative to the floor 26
 defining a periphery of the bolster 20, and a plurality support members or
 circular buttons 30 mounted to the floor 26. Each of these buttons 30
 forms a support surface 32 for supporting the mat 22. In the embodiment
 illustrated in FIG. 1, each button 30 has a center hole through which a
 screw 34 secures the button 30 to the floor 26. The buttons 30 may be
 provided in other suitable shapes, as explained below.
 The mat 22 has an upper surface 36, a lower surface 38, and four side
 surfaces 40. The mat 22 fits closely within the four walls 28 of the
 bolster 20 and rests atop the buttons 30 so that the lower surface 38 of
 the mat 22 contacts the support surfaces 32. As shown in FIG. 3, the mat
 22 and bolster 20 are dimensioned so that a portion of the thickness of
 the mat 22 protrudes above the peripheral walls 28 of the bolster 20. For
 example, about one-half to one-third of the thickness of the mat 22 may
 protrude above the walls 28 of the bolster 20. The mat 22 may have a
 thickness in the range of 0.125 inches to 2.0 inches and a preferred
 thickness of about 0.5 inches.
 The mat 22 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 30-60 35-45 40
 (Durometer) Shore A
 Tensile Strength (psi) 2000-6000 3000-4500 4000
 Heat Stability -20.degree.-300.degree. -20.degree.-140.degree.
 175.degree.
 Fahrenheit
 Turning to FIGS. 2-4, the flexible counter 10 is mounted to a fixed table
 or base 42, and a contoured female die 44 is mounted to a movable press 46
 opposing the counter 10. As shown in FIGS. 3 and 4, the walls 28 of the
 flexible counter 10 are mounted directly to the base 42 by threaded screws
 48. In another embodiment, the floor 26 may be deleted and the base 42 may
 also serve as the floor of the bolster 20. As shown in FIGS. 2-4, the
 sheet 24 of material to be embossed is positioned between the flexible
 counter 10 and the opposing female die 44. The counter 10 and female die
 44 deformably press the sheet 24 to form an embossment thereon.
 The sheet 24 may be paper, cardboard or some other deformable material
 suitable for embossing. The sheet 24 may be provided in precut sections or
 in the form of a continuous web, and may be positioned between the die 44
 and flexible counter 10 by suitable sheet-moving equipment.
 The embodiment of FIG. 2 shows an embossing system 50 including the
 flexible counter 10 and an additional flexible counter 110, both of which
 are mounted to the base 42 and respectively aligned under female dies 44,
 144 which are mounted to an upper portion 46 of the press. The additional
 flexible counter 110 is similar to the flexible counter 10 described
 herein, having similar components including a bolster 112 and mat 122. The
 additional flexible counter 110 is shown having smaller width and length
 dimensions than the flexible counter 10. With the additional flexible
 counter 110, the embossing system 50 is capable of forming multiple
 embossments with a single pressing operation. Of course, more than two
 counter-die combinations could be provided at the embossing system 50. The
 dies 44, 144 and opposing counters 10, 110 are positioned to form
 embossments in desired locations of the sheet 24 depending on the
 particular application, patterns and products being produced. The
 embossing system 50 may be used as a station in a production line for
 manufacturing greeting cards or other products.
 According to the invention, the flexible counter 10 supports the mat in a
 controlled manner. Specifically, the mat deformation caused by pressure
 from the contoured female die is directionally controlled, resulting in a
 "flow" behavior of the mat material which optimizes the embossing
 performance. In particular, at lower regions of the mat, the bolster has
 shaped recesses which accommodate "bulging" of the compressed rubber. This
 helps avoid undesirable lateral translation and stretching of the upper
 mat surface which reduces the risk of tearing the sheet.
 For example, as illustrated in FIGS. 3 and 4, the flexible counter 10 is
 effective to support one side 24A of the sheet 24 during an embossing
 operation while the contoured female embossing die 44 presses against an
 opposite side 24B of the sheet 24 toward the flexible counter 10. FIG. 3
 illustrates the embossing system 50 when the press 46 and die 44 are
 retracted, and FIG. 4 illustrates the embossing system 50 when the press
 46 is forcing the die 44 toward the counter 10 to emboss the sheet 24. As
 the sheet 24 is embossed, the mat 22 deforms to match the contour of the
 die 44 and supports the sheet 24 under the embossed area.
 According to an aspect of the invention, to accommodate the bulging
 portions of the mat 22 during compression, the bolster 20 is constructed
 to have one or more recesses adjacent the support surfaces 32, including,
 for example, a peripheral recess 52 and multiple bottom recesses 54.
 Forming the peripheral recess 52, each of the walls 28 of the bolster 20
 has a chamfered interior edge 56 facing the mat 22. The peripheral recess
 52 extends peripherally around a lower portion of the mat 22, surrounding
 a lower thickness of the mat 22. The bottom recesses 54 may be formed by
 gaps between the support surfaces 32 which support the mat 22. As shown in
 FIGS. 1-4, buttons 30 are mounted to the floor 26 in an array or pattern
 wherein the buttons 30 are spaced apart from each other to form the
 recesses 54.
 As also illustrated in FIGS. 3 and 4, a friction-reducing film 58 is
 positioned between the mat 22 and the sheet 24. The film 58 reduces
 friction between the mat 22 and the sheet 24, thereby aiding to release
 the sheet 24 from the mat 22 after embossing and reducing a risk of
 damaging the sheet 24. The film 58 may be made of urethane, mylar, 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 58. In one embodiment, the urethane film may have a
 thickness of:

Range Preferred
 Thickness (inches) .003-.09 0.015
 As illustrated in the embodiment of FIGS. 3-4, the film 58 is secured in
 position relative to the flexible counter 10 by clamping edges of the film
 58 under braces 60 which are fastened to the base 42 by threaded screws
 61.
 In FIG. 3, the die 44 and press 46 are illustrated in a retracted or lifted
 position. While the die 44 is retracted, the sheet 24 is placed between
 the film 58 and the die 44, and the sheet 24 is positioned so that the
 desired area of the sheet. 24 to be embossed is aligned under the die 44.
 Turning to FIG. 4, the press 46 is then actuated downwardly, thereby
 pressing the die 44 downwardly against the sheet 24. Pressure applied to
 the die 44 may vary from application to application depending on the type
 and thickness of the sheet material, the shape 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.degree.-300.degree. 130.degree.-210.degree.
 165.degree.
 (Fahrenheit)
 Still referring to FIG. 4, when the die 44 is pressed against the sheet 24,
 the sheet 24 contacts the film 58, which in turn is pressed against the
 mat 22, which in turn is supported by the bolster 20. The upper surface 36
 of the mat 22 presses upwardly against the sheet 24 (through the film 58),
 opposing the die force and complementarily deforming to the contour of the
 die 44. The sheet 24 is embossed between the die 44 and the mat 22 to
 affect the desired embossment of the sheet 24. The die 44 is subsequently
 retracted, and the embossed sheet 24 is removed.
 According to the invention, the mat 22 is supported by the support areas 32
 and the walls 28 of the bolster 20 adjacent to the recesses 52, 54. As
 shown in FIG. 4, the mat 22 deforms against the buttons 30 and against the
 walls 28, causing peripheral lower portions 62 of the mat 22 to bulge into
 the peripheral recess 52. Additionally, bulging portions 64 at the lower
 surface 38 of the mat 22 bulge into the recesses 64 between the buttons
 30. The ability of the mat 22 to bulge or "flow" in this manner away from
 the upper surface 36 of the mat 22 results in reliable embossing
 performance. The performance exhibited by the counter 10 may be partly due
 toga minimization of lateral stretching and translation at the upper
 surface 36 of the mat 22 from the stress-relieving deformation and "flow"
 permitted at lower regions of the mat 22 into the recesses 52, 54.
 As illustrated in FIGS. 3 and 4, in order to avoid cutting or damaging the
 mat 22, each of the buttons 30 may be shaped so that the support surface
 32 has no sharp angles or edges. In the illustrated embodiment, each of
 the buttons 30 is rounded in shape at the side which faces the mat 22. In
 an embodiment, a button may be rounded so that the support surface 32 has
 a cross-sectional radius of about one-quarter inch. In one embodiment, a
 button has a diameter of about 1.25 inches and a height of about 0.3
 inches. Also, the buttons are spaced about 1.5 inches from the center of
 one button to the center of another button.
 The buttons may have the following characteristics:

First Range Second Range Preferred
 Diameter (inches) 0.25-2.50 1-1.375 1.25
 Height (inches) 0.0625-1.0 0.25-0.375 0.31
 Spacing (inches) 0.5-5.0 1-1.75 1.5
 Because the flexible counter 10 is resilient, the flexible counter 10
 provides effective counter-support against a variety of female die
 contours. The flexible counter 10 eliminates a need for an expensive
 cooperatively-shaped male die. Moreover, the flexible counter 10 provides
 effective counter-support at any position where the mat 22 is adequately
 supported by the support members 30, preferably at locations spaced
 inwardly from the sides 40 of the mat 22. Accordingly, maintaining precise
 alignment of the flexible counter relative to the female die 44 is
 unnecessary.
 The bolster 20 of the flexible counter 10 may be constructed in any
 appropriate shape which results in the desirable deformation
 characteristics of the mat 22. Particularly, the bolster 20 may be
 provided in any of a variety of shapes having suitable recesses to
 controllably accommodate bulging lower portions of the mat 22 in order to
 result in the desired behavior of the upper surface 36 of the mat 22.
 For example, alternatively shaped bolsters 220 and 320 are illustrated in
 FIGS. 5 and 6, respectively. The bolster 220 illustrated in FIG. 5 has a
 plurality of generally loop-shaped support members 230, 232 arranged in a
 concentric and spaced manner. The loop-shaped support members 230, 232 are
 mounted to a common floor 226 within a rectangular wall 228 for
 peripherally surrounding sides of the mat. FIG. 6 illustrates bolster 320
 having an array of spaced square or rectangular buttons 330 arranged in a
 waffle pattern. The buttons 330 are mounted to a common floor 326 within a
 rectangular loop-shaped support member 331 and a rectangular wall 328 for
 peripherally extending around sides of the mat.
 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. Accordingly, the appended claims are intended to
 cover all alternatives, modifications, and equivalents included within the
 spirit and scope of the invention.