Abstract:
Removable handles are disclosed for attaching to die boards for installation and removal from die cutter machines in a printing machine.

Description:
FIELD  
         [0001]    This invention relates to printing machines including at least one die cutter section for diecutting or scoring individual sheets of material as they pass through the printing machine, and more particularly, to substantially improved handles for attaching and detaching the “die boards” to and from the rotary die cylinder.  
         BACKGROUND  
         [0002]    In the field of rotary printing machines, for printing on sheets of corrugated cardboard, for example, it is well known that the printed sheets must be cut and/or scored so as to fold and form end displays or cartons. It is also well known, such as disclosed in U.S. Pat. No. 4,878,407, to mount the cutter blades on a shell or “die board” which is removably connected to the die cutter cylinder; said patent being hereby incorporated by reference. The elongated die boards are generally composed of wood, and are both heavy and awkward to attach and detach from the die cylinder such that it is known to provide handles at the opposite longitudinal ends of the die board. Handles in the form of cut-outs are disclosed in the above stated patent, and it is also known to provide removable handles which are temporarily attached to the die board when it is desired to mount or demount a die board on or from the die cylinder. However, such removable handles have been heavy and awkward in themselves, difficult to attach and detach, and composed of stainless steel which makes them very expensive.  
         SUMMARY  
         [0003]    The present invention provides handles and a handle locking system for die boards which are easy and quick to attach or remove, and which are both light weight and inexpensive. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0004]    [0004]FIG. 1 illustrates a die cylinder and die board of the prior art;  
         [0005]    [0005]FIG. 2 is a perspective view of the handle and locking system of the present invention;  
         [0006]    [0006]FIG. 3 is a side elevational view, partly in cross-section, illustrating the locking elements of the handle and die board; and  
         [0007]    [0007]FIG. 4 is a schematic perspective view showing one removable handle of the invention secured to a die board, and the mounting insert for securing a second handle. 
     
    
     DETAILED DESCRIPTION  
       [0008]    Referring first to the prior art, FIG. 1 illustrates a die board  10  carrying cutters  12  mounted on a die cylinder  14 . In the illustrated prior art, the die board is maintained on the cylinder by virtue of a negative pressure within the hollow cylinder which draws the die board against the cylinder through a plurality of valves  16 . However, it will be understood that other forms of vacuum and/or mechanical attachment may be used with the present invention such as bolts, locking rings, etc. FIG. 1 also illustrates one cut-out handle  18 , and it will be understood that a second handle is provided in the cut-off right-hand end of the die board. However, such cut-out handles are difficult to use and may cause pinched fingers as the die board engages the cylinder.  
         [0009]    Referring to FIGS. 2 and 3, one handle  20  of the present invention is illustrated in detail. The handle comprises a curved gripping portion  22 , a bridge portion  24  which extends from one end of the curved gripping portion to the other, and a pair of stand-off legs  26 . Legs  26  include curved surfaces  28  which match the curvature of the die board when the legs engage the die board, and legs  26  are one-piece integral portions of the handle.  
         [0010]    Bridge portion  24  includes a passage  30  through which a threaded bolt or pin  32  extends. Threaded pin  32  includes an enlarged head portion  34  which preferably includes a high friction surface  35  such as a knurled surface or a coating of high friction material. Head  34  may be integral with the pin, or the head may comprise a plastic knob securely connected to the pin such as by adhesives, locking pins or other connectors. As further shown in FIGS.  2 - 3 , the second element of the locking system comprises an insert  36  having internal threads  37  which is inserted into the die board in a permanent manner. For example, a hole of proper size may be drilled into the die board, and the exterior threads  39  of insert  36  may be screwed into the hole such that it is securely retained in the hole by friction. Preferably, insert  36  has self-tapping threads and a slot  38  so that the insert cuts the threads in the die board as it is screwed into the hole, and the leading portions of the insert on opposite sides of the slot are compressed so that the leading portions exert a strong frictional force against the hole in the die board. In addition, or alternatively, external threads  39  of the insert may be coated with locking materials such as glue, epoxy, etc. so as to permanently secure the insert in place in the die board with or without the provision of slot  38 .  
         [0011]    In use, a first handle  20  is placed on the die board with curved surfaces  28  engaging the die board, and threaded pin  32  is screwed into an insert  36  by rotating knob  34 . Preferably, the external threads on the pin and internal threads  37  of the insert have a course pitch such that only a few turns of the knob are required to lock the handle to the die board. Thereafter, the same simple procedure is used to quickly attach a second handle to the opposite end of the die board, and both handles may be quickly removed by simply turning the knobs a few times in the opposite direction.  
         [0012]    With respect to the compositions of the various parts, it is a feature of the invention that the handles are substantially lighter and of substantially lower cost than previously known. For example, it has been discovered that sturdy, rugged and long-term reusable handles may be cast from aluminum, or water or plasma jet-cut from standard stock aluminum sheets; such sheets having a preferred thickness in the order of ¾ to 1 inch. It has also been discovered that, for even lighter handles at lower cost, the handles may be molded of or cut from plastic such as reinforced polypropylene or Nylon® or other plastic materials. At the same time, however, it is preferred that inserts  36  and pins  32  be composed of metal.  
         [0013]    From the foregoing description of one preferred embodiment of the invention, it will be apparent that numerous variations may be made in the invention by a person skilled in the art. Accordingly, it is to be understood that the foregoing description is intended to be illustrative of the principles of the invention, and not exhaustive thereof, and that the invention is intended to be limited only as set forth in the following claims interpreted under the doctrine of equivalents.