Patent Publication Number: US-10759079-B2

Title: Rotary cutting die apparatus for cutting corrugated board including retainers for maintaining trim strippers closely adjacent trim cutting blades

Description:
FIELD OF THE INVENTION 
     The present invention relates to rotary cutting dies for cutting and scoring corrugated board, and more particularly to a rotary cutting die having trim cutting blades and trim strippers for engaging cut pieces of trim and directing them away from the rotary cutting die. 
     BACKGROUND OF THE INVENTION 
     Rotary cutting dies are commonly used for producing a container or carton blank from corrugated board sheet material. Such rotary dies are typically comprised of a die cylinder, a die board mounted on the die cylinder and including cutting blades and scoring rules, and an anvil mounted adjacently the die cylinder and the die board. A nip is defined between the die board and the anvil and sheets of corrugated board are fed into the nip. As the corrugated board is fed through the nip, the cutting rules, scoring rules and other devices and elements mounted on the die board engage and operate on the corrugated board passing through the nip and between the die board and the anvil. 
     Most die boards are designed to trim the corrugated board along surrounding edges as the corrugated board passes through the nip. To accomplish this, the die board is provided with a series of trim cutting blades. Also mounted to the die board adjacent the outside of the respective trim cutting blades is elastomer trim transfer devices or trim strippers. The trim strippers are compressible and resilient. During the trim cutting process, the trim strippers engage the cut pieces of trim as they pass through the nip and hold the cut pieces of trim against the anvil for a short period of time. The trim strippers function to separate the cut pieces of trim from the resulting product board. 
     Over a period of time, the trim strippers or trim transfer devices tend to separate and move away from the adjacent trim cutting blades. That is, as the trim strippers are compressed and passed through the nip, it is common to find that they tend to bow and as they bow, a small gap occurs between the trip strippers and the adjacent trim cutting blades. Once this gap occurs, it is common for small pieces of cut trim to become lodged or packed in the gap. Over a period of time, this cut trim becomes more compact and is effectively driven down between the trim strippers and the trim cutting blades. The forces placed on the cut pieces of trim can be so great that they damage and even break the die board. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a rotary cutting die that is adapted to be mounted on a rotary die cylinder for cutting corrugated board fed between the cutting die and an anvil. The rotary cutting die includes a die board and a plurality of trim cutting blades mounted on the die board. Trim strippers or trim transfer devices are secured on the die board adjacent the trim cutting blades and functions to engage cut pieces of trim and urge the cut pieces of trim away from the trim cutting blades. A retainer is mounted on the die board closely adjacent the trim strippers such that the trim strippers are confined and disposed between the retainer and the trim cutting blades. By confining the trim strippers between the retainer and trim cutting blades, the trim strippers are maintained closely adjacent the trim cutting blades such that a gap does not occur between the trim strippers and the trim cutting blades. This generally prevents cut pieces of trim from becoming jammed or packed between the trim strippers and the trim cutting blades. 
     In another embodiment of the present invention, there is provided a preloading device mounted on the die board ahead of a leading trim cutting blade. The preloading device engages the anvil during the process of trimming and cutting corrugated board and preloads the rotary die cylinder that the die board is mounted on prior to the leading trim cutting blade loading the die cylinder. This preloading device tends to gradually load the die cylinder as opposed to abruptly loading the die cylinder which may occur when the leading trim cutting blades engage the corrugated board. By gradually loading or preloading the die cylinder as contrasted with abruptly loading, upstream printing operations are made more efficient and generally typical problems associated with ink smudging is avoided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a rotary cutting die apparatus showing trim cutting blades, trip strippers and retainers for maintaining the trim strippers in close proximity to the trim cutting blades. 
         FIG. 2  is a fragmentary perspective view showing a portion of a die board of the present invention. 
         FIG. 2A  is an exploded view showing portions of the trim cutting blades, trim stripper and retainer. 
         FIG. 3  is a fragmentary perspective view showing another portion of the die board of the present invention. 
         FIG. 4  is a fragmentary plan view showing a portion of the die board of the present invention. 
         FIG. 5  is a sectional view taken through the line V-V of  FIG. 4 . 
         FIG. 6  is a sectional view similar to  FIG. 5 , but showing a block of wood used as the retainer. 
         FIG. 7  is a fragmentary sectional view showing an alternative design for a trim stripper. 
         FIG. 8  is a fragmentary sectional view showing another alternative design for a trim stripper. 
         FIG. 9  is fragmentary sectional view showing still another alternative design for the trim stripper. 
         FIG. 10  is a schematic illustration of a portion of a die board including a preloading device. 
         FIG. 11  is a fragmentary sectional view taken through the line XI-XI of  FIG. 10 . 
         FIG. 12A  is a schematic illustration showing a trim stripper beginning to pass through the nip between a die board cylinder and an anvil cylinder. 
         FIG. 12B  is a schematic illustration showing the continued movement of the trim stripper through the nip and showing the trim stripper engaging a piece of cut trim. 
         FIG. 12C  is similar to  FIGS. 12A and 12B  and which shows the trim stripper exiting the nip, but still engaged with the cut piece of trim. 
         FIG. 13  is a schematic illustration of a machine that includes the rotary cuffing die assembly along with a series of printing stations. 
     
    
    
     DETAILED DESCRIPTION 
     With further reference to the drawings, a rotary cutting die apparatus is shown therein and indicated generally by the numeral  30 . As is appreciated by those skilled in the art, the rotary cutting die apparatus  30  is designed to receive sheets of corrugated board CB and to trim the sheets of corrugated board to yield a product board. Further, the rotary cutting die apparatus  30  is designed to cut, score, and in some cases remove scrap from areas of product board. In the end, the rotary cutting die apparatus  30  is designed to treat and condition the corrugated board such that when the corrugated board exits the rotary cutting die apparatus, the product board can be easily manipulated into a box configuration. 
     With reference to  FIG. 1 , the rotary cutting die apparatus  30  includes a die board cylinder  40  and an anvil cylinder  50 . As will be appreciated from subsequent portions of the disclosure, the die board cylinder  40  is designed to receive and hold a die board  42 . The die board cylinder  40  including the die board  42  is disposed with respect to the anvil cylinder  50  such that a nip is defined there between. As sheets of corrugated board are fed through the nip, corrugated board is engaged by the die board  42  which trims, cuts and scores the corrugated board. The anvil cylinder  50  is typically surrounded or sheathed with a surface layer or coating  52  of a relatively compliant material such as urethane, which provides a backing surface against which a cut can be made without damaging various components carried by the die board  42 . As such, anvil cylinder  50  rotates in a manner that is generally synchronous with the adjacent die board cylinder  40  during normal operations. 
     Die board  42  is typically constructed of laminated plywood. Die boards, such as that illustrated in  FIG. 1 , typically include a combination of cutting blades, creasing rules, resilient scrap strippers, resilient product ejectors and the like. 
     More particularly, the die board  42  includes a series of trim cutting blades  44  which are securely mounted in the die board such that the cutting tips of the blades  44  protrude and extend generally outwardly and away from the surface of the die board cylinder  40 . Trim cutting blades  44  extend generally around an area of the die board  42 . For example, the trim cutting blades  44  include one or more leading trim cutting blades such as shown in  FIGS. 2 and 12A , one or more side trim cutting blades such as appears in  FIG. 3  and one or more trailing trim cut blades that are shown extending transversely across the lower portion of the die board  42  in  FIG. 1 . Each trim cutting blade  44  includes an outboard side that is referred to by  44 A and an inboard side that is referred to by  44 B. 
     Rotary cutting die apparatus  30  is designed to receive the corrugated board CB. As the corrugated board CB passes through the nip, the die cutting board and the elements thereof is effective to trim the corrugated board. That is, the trim cutting blades  44  trim small trim pieces TP from the outside edge of the corrugated board. This leaves a product board or a product portion of the corrugated board. Die board  42  and the elements thereon operate on the product portion to cut and score and form the product board into a corrugated panel that can be shaped and formed into a corrugated box or container. 
     The term “trim cutting blade” or “trim blade” is specifically defined as a blade that trims the corrugated board CB and cuts a piece of trim from around edge portions of the corrugated board to leave the finished die cut product. The term “trim cutting blade” or “trim blade” specifically excludes any scrap cutting blades located within the area defined by the overall length and overall width of the finished die cut product. 
     Disposed adjacent trim cutting blades  44  is a series of trim strippers  46 . In some cases, the trim strippers  46  are referred to as elastomer trim transfer devices. The trim strippers  46  are positioned adjacent the outboard side  44 A of the trim cutting blades  44 . They function to engage the cut trim pieces TP cut from the corrugated board CB by the trim cutting blades  44  and direct the cut trim pieces away from the trim cutting blades and away from the product portion of the corrugated board CB. Trim strippers  46  can assume various shapes. In the embodiment illustrated herein, the trim strippers  46  are generally elongated and are generally rectangular or square in cross section. The trim strippers  46  are resilient and compressible and are typically manufactured from a resilient material such as a urethane having a durometer of 85 on a Shore 00 scale and having a density of approximately 45 g/cm 3 . 
     For purposes of explanation, each trim stripper  46  includes an outboard side  46 A and an inboard side  46 B. Inboard side  46 B is set directly adjacent the outboard side  44 A of a trim cutting blade  44 . This is true for all of the trim cutting blades  44  irrespective of their location on the die board  42 . That is, in the case of the leading trim cutting blade ( FIG. 2 ), the trim stripper or strippers  46  is disposed directly adjacent the outboard side  44 A of the trim cutting blade  44 . Likewise, for side and trailing trim cutting blades, the trim strippers  46  are disposed on the outside thereof such that the inboard side  46 B of the trim strippers engage and rest against the outboard side  44 A of the trim cutting blades. 
     As discussed above, in conventional rotary cutting dies there is a tendency for the trim strippers to bow. That is, as the die board rotates and the trim strippers engage cut trim as well as the anvil, the trim strippers tend to bow, leaving a gap between the trim strippers and the outboard side of the trim cutting blades. This results in the inboard side of the trim stripper moving away from the adjacent trim cutting blade. Often, this leaves the gap between the trim cutting blade and the trim stripper. Over a period of time, small cut pieces of trim tend to wedge themselves between the trim cutting blade and the adjacent trim stripper. This over time causes substantial forces to be applied against the blade and ultimately the die board, often resulting in damage to the die board. 
     In addition to the trim strippers  46  just discussed, also provided are secondary trim strippers  48 . As illustrated in  FIG. 4 , the secondary trim strippers  48  are disposed outside the trim cutting blades  44 . Secondary trim strippers  48  can be placed at various locations on the die board  42 . In general, as illustrated in  FIG. 4 , the secondary trim strippers  48  are disposed outside of the trim cutting blades  44  and as illustrated in  FIG. 4  in this one example the secondary trim strippers  48  include a series of generally U-shaped trim strippers disposed along the side of the die board and three secondary trim strippers disposed in the leading corners of the die board just outwardly of the trim cutting blades  44 . The secondary trim strippers  48  may be placed along the leading edge of the die board  42 , just outwardly of the leading trim cutting blades  44  and the primary trim strippers  46 . Generally, the secondary trim strippers  48  are optional. Secondary trim strippers  48  may be useful during the set up and initial runs of the rotary cutting die apparatus  30 . In some cases during set up and initial runs the leading trim pieces cut may be larger than would ordinarily occur during normal operations. In these cases, the secondary trim strippers  48  engage the relatively large pieces of cut trim and urge them downwardly in engagement with the anvil  50  and cause the cut trim pieces to be separated from the produced product board. For the secondary trim strippers  48 , conventional trim stripping material can be used. In one embodiment it is contemplated that the material used for the secondary trim strippers  48  would be less dense than the material used for trim strippers  46 . 
     The present invention provides a retainer  100  for engaging the trim strippers  46  and maintaining the trim strippers closely adjacent the trim cutting blades  44  so that the tendency for a gap to occur between the trim strippers and the trim cutting blades is reduced or eliminated. Therefore, as seen in the drawings, a series of retainers  100  is mounted in the die board outside of the trim cutting blades  44  and outside of the trim strippers  46 . As seen in the drawings, the retainers are spaced so as to closely confine the trim strippers  46  between the trim cutting blades  44  and the retainers  100 . The retainers  100  include an outboard side  100 A and an inboard side  100 B. The retainers  100  are positioned flush against the outboard side  46 A of the trim strippers  46 . The purpose of the retainers  100  is to hold the trim strippers  46  closely adjacent the outboard side of the trim cutting blades  44 . This confines the trim strippers  46  between the trim cutting blades  44  and the retainers  100 . This prevents the trim strippers  46  from bowing and leaving a gap between the trim strippers and the trim cutting blades  44 . 
     Retainers  100  can take various forms. In one embodiment, the retainers comprise a series of scoring or cutting rules mounted in the die board  42 . In another embodiment, the retainer  100  can assume the form of a block object secured on the die board  42 . For example, the block object could be surface mounted to the die board  42 . In one particular example, the retainer is a block of wood that is stapled, glued or otherwise fastened to the die board  42 . This is illustrated in  FIG. 6  and the block of wood is indicated at  100 C. Discussed subsequently herein are preloading devices  150 . The preloading device subsequently discussed herein could be utilized as a retainer for retaining the trim strippers  46  in a space defined generally between the trim cutting blades  44  and the preloading devices. Other forms and types of retainers may be used. The retainers  100  should be sufficiently strong enough and of a height to retain the trim strippers  46  and maintain the trim strippers closely adjacent the respective trim cutting blades  44 . 
     As pointed out above, the trim stripper  46  can assume various designs. A few exemplary designs for the trim stripper  46  are shown in  FIGS. 7, 8 and 9 . First, in  FIG. 7 , the trim stripper shown therein is still confined between the trim cutting blade  44  and the retainer  100 . In this case the trim stripper includes a member  46 C that can be an elastomer constructed of foam, rubber, or the like. Secured by glue or other suitable fastening means to member  46 C is a cap  46 D. The cap  46 D assumes an inverted U-shape and includes downwardly extending sides that are confined between the retainer  100  and the trim cutting blade  44 . As viewed in  FIG. 7 , the resilient member  46 C is compressible as it passes through the nip. Cap  46 D, which can be constructed of plastic or other suitable materials, moves with the compressible member  46 C. Consequently, both member  46 C and cap  46 D move back and forth between the retainer  100  and trim cutting blade  44  as the trim stripper passes through the nip. 
       FIG. 8  is another example of a trim stripper design. Here the trim stripper  46  includes a resilient member  46 E that is confined between retainer  100  and trim cutting blade  44 . Again, member  46 E can be an elastomer such as a resilient block constructed of rubber, foam or the like. Secured to the top of member  46 E is a cap  46 F. Cap  46 F includes a resilient wiper  46 G that extends from one side of the cap  46 F. The wiper  46 G is biased to generally engage the trim blade  44  as the trim stripper is moved back and forth within the confines of the retainer  100  and trim blade  44 . Wiper  46 G by engaging the outboard surface of the trim cutting blade  44  prevents cut trim from being lodged between the wiper  46 G and the outboard side of the trim cutting blade  44 . 
       FIG. 9  is another exemplary trim stripper. Here the trim stripper includes a resilient member  46 H in the form of a spring. The spring is seated on the die board  42  and extends therefrom. Secured over the spring  46 H is a cap  46 I. Cap  46 I assumes an inverted U-shape with the sides thereof extending, as viewed in  FIG. 9 , downwardly between the spring  46 H and the retainer  100  and trim cutting blade  44 . Again, as the trim stripper passes through the nip, the resilient member or spring  46 H is compressed causing the cap  46 I, as viewed in  FIG. 9 , to move downwardly. Again, the retainer  100  and trim cutting blade  44  confine the cap  46 I. The retainer  100  functions to retain the cap  46 I closely adjacent the outboard side of the cutting blade  44  such that cut trim is not packed or wedged between the cap  46 I and the outboard side of the trim cutting blade  44 . 
     Which further reference to the drawings, the die board  42  includes other elements that are associated with the trim cutting blades  44 . For example, extending perpendicularly outwardly from the outboard side  44 A of the trim cutting blades  44  is a series of trim breakers  120 . Many of the trim breakers disclosed herein assume a generally L-shape on the die board  42 . They may also be generally straight. The trim breakers  100  include an upper cutting edge that is effective to cut the outside trim pieces into smaller portions. Note that the trim breakers  120  generally extend from or even abut the trim cutting blades  44 . 
     The trim cutting blades are also reinforced by a series of rule supports  130 . Note in  FIGS. 2 and 4  where the rule supports lie adjacent the inboard side  44 B of the cutting blades  44 . These rule supports  130  extend into or abut against the inboard side of the cutting blades  44  so as to support and reinforce the trim cutting blades. 
     Turning to  FIG. 10  of the drawings, there is shown therein a machine for printing and die cutting corrugated board. The machine is referred to generally by the numeral  200 . The machine  200 , in this embodiment, includes three basic operating stations. Station  210  is a first print station and  212  refers to a second print station. Located downstream from the second print station  212  is a die cutting station indicated generally by the numeral  214 . Die cutting station  214  includes the rotary die cutting apparatus  30  discussed above. That is, die cutting station  214  includes the rotary die cylinder  40 , anvil cylinder  50  and die board  42 . Upstream from the first print station  214  is a pair of rollers  202 ,  204 . Roller  204  is driven by a motor that is controlled through a controller. Roller  204  has a gear associated therewith that is effective to drive the components of the first print station. The first print station  210  includes a gear network that is operative to drive the second print station which likewise has a gear network that is operative to drive the die cutting station  214 . Details of the machine  10  will not be dealt with herein because such is not per se material to the present invention and further such machines are known. Suffice to say that corrugated board CB is fed into the machine from right to left, as viewed in  FIG. 10 . The corrugated board is fed into the nip between rollers  202  and  204  and continues generally horizontally through the first and second print stations  210  and  212  and then through the die cutting station  214 . In the process, printing plates carried by the print rollers of the first and second print stations  210  and  212  are operative to print indicia, designs, etc. on the passing corrugated board. Once the corrugated board clears the second print station  212 , it enters the die cutting station  214  and the die board  42  and the elements thereon trim the corrugated board and further cut and act on the remaining product board. 
     In the example shown in  FIG. 10 , each station  210 ,  212  and  214  includes a dedicated motor for assisting and powering the respective stations. However, in many of the machines similar to that shown in  FIG. 10 , the multiple stations are powered by a single motor that drives an initial roller such as roller  204  at the inlet end of the machine. In this case particularly, the printing process is sometimes encumbered by abrupt loads that are repeatedly placed on the components of the die cutting station  214 . In particular, when the leading trim cutting blade comes into contact with the corrugated board, there is an abrupt load placed on the rotary die cylinder  40 . This for just a moment causes a hesitation in the upstream drive system. This hesitation is just enough to cause a small ink smudge at a particular point or area on the corrugated board. 
     The present invention entails a die board that is designed to avoid the abrupt loads caused by the leading trim blades on each revolution of the rotary die cylinder  40 . 
     The present invention entails one or more preloading devices, indicated generally by the numeral  150  mounted on the die board  42  just ahead of the leading trim cutting blades  44 . Essentially the preloading devices  150  provide a gradual load to the rotary die cutting apparatus  30  prior to the leading trim cutting blades  44  engaging the corrugated board and cutting the trim against the anvil  50 . 
     The preloading devices can be designed and arranged in various ways. In the present application, each preloading device includes one or more ramps that are aligned with the leading trim cutting blades  44  and spaced ahead of the trim cutting blades. That is, as seen in  FIGS. 2, 4, 6 and 7 , the preloading devices  150  include a ramp-like structure that is inclined such that the upper surfaces of the ramps are inclined outwardly from the die board  42  in the general direction of the leading trim cutting blades  44 . 
     In the case of the embodiment shown in  FIG. 2 , the preloading devices are in the form of a compressible ramp structure that is made of urethane or hard or semi-hard rubber. Various materials can be used for the ramps. In one embodiment the preloading ramp, such as shown in  FIG. 2 , comprises a urethane generally described as Shore A, durometer 85-87. These ramps include side edges and an upper inclined surface. Note that as viewed in  FIG. 2 , the upper inclined surface of each preloading device is inclined upwardly in the direction of the leading trim cutting blades  44 . Thus, on each revolution of the rotary die cylinder  40 , these ramps or preloading devices  150  will engage the anvil  50  ahead of the leading trim cutting blades  44  so as to gradually load the rotary die board cylinder  40 . This gradual loading of the cylinder  40  will prevent abrupt loading and will reduce the tendency of the printing stations to cause ink smudges instantaneously at the time of abrupt loading. 
     The preloading ramps can assume various forms. In an alternative design shown in  FIG. 7 , the preloading device  150  includes a series of upstanding elements  154 . This is referred to as a segmented ramp because it is not continuous or does not include a continuous upper surface. Various types of elements can be employed. In one embodiment, the various elements comprising the preloading device in  FIGS. 6 and 7  is a series of scoring rules with their heights varying. As viewed in  FIGS. 6 and 7 , the height of the respective elements of the segmented ramp, generally become taller or higher towards the retainer  100  and trim stripper  46 . Again, the elements that make up the segmented ramp shown in  FIGS. 6 and 7  will effectively gradually preload the die board cylinder  40 . In some cases, the various elements of the segmented ramp can be turned 90° or at other angles from that shown in  FIGS. 6 and 7 . The length of the respective segments can vary. 
       FIGS. 9A, 9B and 9C  are a sequence of views showing how the retainer  100  confines the trim stripper  46  and prevents a gap from occurring between this trim stripper and a trim cutting blade  44 . Further, the sequence of drawings illustrates how the preloading device  150  preloads the die board cylinder  40  to prevent abrupt loading. 
     In  FIG. 9A , the corrugated board is fed into the nip and at the point shown therein, the trim cutting blade is disposed at a point where it is about to engage the corrugated board CB and cut a piece of trim from the leading edge of the corrugated board. At this point, a portion of the trim stripper  46  has engaged the trim piece and has been partially compressed. 
     In  FIG. 9B  the trim cutting blade  44  has severed the trim piece and the trim piece is held against the surface of the anvil  50  by the trim stripper  46 . Note that the retainer  100  has confined the trim stripper  46  between the retainer and the trim cutting blade  44  such that a gap does not appear between the trim stripper and the trim cutting blade. Thus, the piece of cut trim cannot be wedged between the trim stripper  46  and the trim cutting blade  44 . 
       FIG. 9C  shows a continuation of the process where the trim stripper  46  remains engaged with the cut piece of trim TP and is holding the cut piece of trim against the surface of the anvil  50  so as to separate the trim from the following product board. As the process continues, the trim stripper  46  will continue to hold the cut piece of trim against the surface of the anvil until it is released. At the point of the release, the cut trim TP is at a position where the anvil will tend to direct the cut piece of trim downwardly and to the left as viewed in  FIG. 9C . This separates the cut trim from the product board. This same process occurs around the die board  42  and around the various cutting blades  44  utilized. The trim strippers  44  are maintained closely adjacent trim cutting blades  44  such that pieces of trim cannot be wedged or jammed into an opening or gap that occurs between the trim stripper  46  and the trim cutting blades  44 . 
     There are many advantages to the die board  42  of the present invention. The use of the retainers  100  to confine the trim strippers  46  between the trim cuffing blades  44  and the retainers generally preclude cut trim pieces from being wedged and packed between the trim cutting blades and the trim strippers. In addition, with the retainers  100 , taller and firmer stripping material can be employed along the leading edge of the die board. This provides better separation of cut trim pieces from the product board, and as a result less trim pieces end up with the product. 
     The present invention may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the invention. The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.