Abstract:
A loader plate attaches to a cliche used in transfer pad printing to provide an extension surface from which a sealed paint pod may be introduced to the cliche allowing the cliche to remain in registered position while transferring paint pods. A magnet system allows simple clamping of the loader plate to the cliche to simplify operation by a single user.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     BACKGROUND OF THE INVENTION 
     The present invention relates to transfer pad printing systems and, in particular, to a method and apparatus for loading sealed paint pods  32  or pods on such systems. 
     Referring to FIG. 1, a transfer pad printing system  10  provides a cliché  12  having a flat and polished upper surface  14 . Shallow paint channels  16  cut or etched into the upper surface of the cliché  12  define a pattern to be printed. The cliché  12  is ferromagnetic, meaning that it is attracted to magnets but not necessarily magnetic, and may be a stainless steel plate or similar material. 
     During printing, the shallow paint channels  16  are filled with paint. Any extra paint on the upper surface  14  of the cliché  12  is then scraped off or “doctored”. A transfer pad  20  composed of an elastomer such as silicone rubber is then positioned over the paint channels  16  as indicated by arrow  22  and pressed downward against the paint channels  16  where it deforms and accepts paint from the paint channels  16 . 
     The transfer pad  20  is then lifted away from the cliché  12 , as indicated by arrow  24 , and moved to another station (not shown), where it may be pressed against a registered part to be printed (not shown), transferring to that part, the image defined by the paint channels  16 . 
     Transfer pad printing can be extremely precise but normally requires that the cliché  12  and part be precisely registered with respect to movement of the transfer pad  20 . In this regard, the cliché  12  is tightly clamped by clamping structure  28  which provide vernier adjustments  30  allowing for precise registration of the cliché  12  with the remote part and transfer pad  20 . 
     Referring to FIGS. 1 and 2, filling the paint channels  16  in the cliché  12  may be done with a sealed paint cup or “paint pod”  32 . The paint pod  32  provides a cylindrical cup having a doctoring edge  34  surrounding an opening  36  of the cup. The doctoring edge is sharpened to terminate precisely at a plane. Centered within the paint pod  32  and attached thereto is a magnet  38  having one pole face offset slightly below the doctoring edge  34 . 
     In use, the paint pod  32  is filled with paint  40  then attached to the cliché  12 . For this purpose, the cliché  12  is inverted so that upper surface  14  of the cliché  12  faces downward to cover the opening  36  of the paint pod  32 . The magnet  38  pulls the upper surface  14  of the cliché  12  against the doctoring edge  34  of the paint pod  32  which together form a seal preventing leakage of the paint  40 . The connected paint pod  32  and cliché  12  are then inverted putting the upper surface  14  on the upper side. 
     The cliché  12  is then placed within the clamping structure  28  and registered with the rest of the transfer pad printing system  10 . 
     A pivot arm  42  is then attached to base  44  of the paint pod  32 . During operation of the transfer pad printing system  10 , the pivot arm  42  slides the paint pod  32  across the cliché  12  as indicated by arrow  46  in between pressings of the pad  20  against the paint channels  16 . When the paint pod  32  is over the paint channels  16 , it fills the paint channels  16  with paint  40 . As the paint pod  32  is withdrawn, the doctoring edge  34  removes the paint from the remainder of the upper surface  14 . 
     The sealing of the paint pod  32  against the upper surface  14  of the cliché  12  prevents evaporation of the solvent of the paint  40  during long press runs. For such long press runs, however, the amount of paint held within the paint pod  32  may be insufficient and it may be necessary to refill the paint pod  32  a number of times. This refilling process can be quite costly in terms of lost production. A particular problem is the removal of the cliché  12  and registering it again when the cliché  12  is replaced within the clamping structure  28 . Precise registration is time consuming and may require test impressions to assure that the registration is correct. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a method and apparatus for refilling paint pods without disturbing the cliché. By preserving the registration of the cliché, time-consuming re-registration of the cliché is eliminated. 
     The invention provides a loader plate that covers the pod during transfer operations. The surface of the loader plate is precisely ground and the loader plate is fitted with alignment arms so that it may attached to the cliché and the paint pod may be slid between the two without leakage of paint. Extra loader plates and paint pods allow the paint pods to be preloaded, eliminating refill time as well. 
     More specifically, the present invention provides a loading platform for paint pods comprising a loader plate having an upper surface sized to receive and cover a dispensing opening in the paint pod. Alignment arms attached to the loader plate engage a cliché and align a transfer edge of the loader plate into gapless abutment with an edge of the cliché so that the upper surface of the loader plate is substantially coplanar with an upper surface of the cliché. The arms flank a transfer region along the transfer edge of the loader plate sufficient in width to allow continuous sliding passage of the paint pod along the upper surface of the loader plate across the transfer region to the upper surface of the cliché. 
     It is thus one object of the invention to provide a simplified means of loading paint pods without removal of the cliché. 
     The alignment arms may extend in cantilevered fashion over the transfer edge from the upper surface of the loader plate. 
     It is an object of the invention to provide an alignment system that is easily viewed by the operator and that works with a wide variety of clichés, all of which can be certain to have an upper planar surface. 
     The cantilevered portion of the transfer arms may have a lower planar surface coplanar with the upper surface of the loader plate, and the upper surface of the cliché when engaged with the cliché. 
     It is thus another object of the invention to provide a simple mechanism for ensuring alignment of the upper surface of the cliché and loader plates. 
     The transfer arms may have embedded magnets on their cantilevered portions at the lower planar surface so that the magnets attract the cliché when the alignment arms are engaged with the cliché. 
     It is another object of the invention to simplify the loading process by assisting the operator in holding the loader plate against the cliché. The cantilevered arms convert out of plane tipping of the loader plate into vertical disengagement of the magnets, a mode in which they have great strength. 
     The alignment arms may be non-ferromagnetic. 
     It is thus another object of the invention to eliminate distortions in the magnet fields such as may reduce their attractive power. 
     The loader plate may be ferromagnetic. 
     Another object of the invention is to provide a loader plate that attracts the magnet of the paint pod preventing slippage or premature release of paint. 
     The plate may include an upwardly extending fence structure preventing continuous sliding passage of the paint pod along the upper surface of the loader plate, off the loader plate, except across the transfer region. 
     Thus, it is another object of the invention to eliminate possible paint leakage caused by sliding of the paint pod in directions other than onto the cliché. 
     The transfer edge of the loader plate may further include magnets providing in-plane attraction of the loader plate to the cliché. 
     Thus, it is another object of the invention to provide a force holding the cliché and loader plate together that supplements the magnets in the attachment arms, which provide lesser sliding resistance. 
     The loader plate upper surface provides a surface finish and flatness so that the paint pod, when loaded with paint, may be slid along the upper surface without substantial loss of paint. 
     Thus, it is another object of the invention to generally match the surface flatness and finish of the cliché. 
     The transfer edge may include at least one pocket for accepting a projection of cliché retaining structure when the cliché is held in the retaining structure facilitating engagement of the loader plate and cliché. 
     Thus, it is another object of the invention to accommodate a clamping structure holding the cliché without removal of that clamping structure which might affect registration. 
     These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a prior art transfer press system described above showing the paint pod in position against the cliché; 
     FIG. 2 is an inverted, perspective view of the paint pod in partial cutaway showing the doctoring edge, interior magnet, and contained paint prior to attachment to a cliché; 
     FIG. 3 is a perspective view of the cliché attached to a loader plate of the present invention showing sliding disengagement of a paint pod from the loader plate onto the cliché; 
     FIG. 4 is a top plan view of the loader plate of FIG. 3 showing its attachment to the cliché as positioned and held by attachment arms with lower surface magnets and showing the position of a fence structure for reducing movement of the paint pod on the loader plate; and 
     FIG. 5 is a cross-sectional view along line  5 — 5  of FIG. 4 showing edge magnets, which supplement the magnets in the attachment arms for holding the loader plate against the cliché. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 3 and 4, the present invention provides a loader plate  48  providing a planar upper surface  50  having a surface finish and flatness commensurate with the upper surface  14  of the cliché  12 . 
     The loader plate  48  is preferably a ferromagnetic stainless steel and may be constructed, for example, of the same material as the cliché  12 . 
     The loader plate  48  provides a transfer edge  52  that may abut a corresponding edge  54  of the cliché  12 . Each of the edges  52  and  54  are generally perpendicular to the upper surfaces  14  and  50  and abut to eliminate gaps there between. Preferably, the transfer edge  52  is straight line such as to be readily adaptable to a variety of clichés  12 , which normally has a corresponding flat edge. 
     Alignment arms  56  and  58  are attached at one end to the upper surface  50  of the loader plate  48  by machine screws  60  and extend in cantilever fashion from the loader plate  48 . 
     Referring momentarily also to FIG. 5, each of the attachment arms  56  and  58  provide a planar lower surface  62  that, at one end, may rest against the planar upper surface  14  of the cliché  12  and, at the other end, is retained against the planar upper surface  50  of the loader plate  48 . Thus, when bridging the two upper surfaces  14  and  50 , the alignment arms  56  and  58  bring upper surfaces  14  and  50  into alignment in a single plane. 
     Retention of lower surface  62  of attachment arms  56  and  58  in abutment with the upper surface  14  and cliché  12  is provided by a series of eight magnets  64  flush with the lower surface  62  of arms  58  and  56 . In the preferred embodiment, each of the magnets will have a 3.5 lb. rating and will be ground flush to the lower surface  62  so as to provide very little gap between the magnets and the cliché  12  increasing their pull. Further, the arms  58  and  56  are constructed of a non-ferromagnetic material, preferably aluminum, so as not to interfere with the magnetic fields of the magnets or mar the upper surface  14  of the cliché  12 . 
     Downward forces  66  on the loader plate  48  caused for example, by the weight of a paint pod  32  or operator manipulation, will translate into an upward force  68  on the cantilevered portion of the arms  58  and  60  causing a pulling of the magnets  64  away from the ferromagnetic cliché  12 , a direction in which the magnetic resisting force is strongest. Nevertheless, the magnets  64  may be disengaged easily by sliding them along the polished upper surface  14  of the cliché  12  under the influence of an in-plane force  71 . 
     Added resistance to this in-plane force  71  may be provided by a second set of magnets  70  positioned at the transfer edge  52  below the upper surface  50  of the loader plate  48  to attract the edge  54  of the cliché  12 . Magnets  70  may be held by a retention clamp  72  providing one side of a pocket beneath the upper surface  50  of the loader plate  48 . The retention clamp  72  grips the magnets  70  as pulled against the remainder of the loader plate  48  by a machine screw  74 . Magnet  70  may be ground substantially flush with the edge  52  to minimize the gap therebetween. 
     Referring again to FIG. 4, the head of machine screw  74  holding the retention clamp is accessible at the upper surface  50  of the loader plate  48  and may be counter sunk, and then covered with an epoxy material flush with the remainder of the upper surface  50 . 
     Referring again to both FIGS. 4 and 5, the upper surface  50  of the loader plate  48  provides an area  78  sufficient to hold a paint pod  32 . Arms  56  and  58  are separated to provide a transfer region between them sufficient for the paint pod  32  to slide from the area  78  onto the cliché  12  without obstruction. 
     Dowel posts  80  may extend upward from the upper surface  50  of the loader plate  48  so as to provide a fence structure preventing sliding of the paint pod  32  except onto the cliché  12  as indicated by arrow  82 . 
     Referring to FIG. 4, a pocket  90  may be cut into the transfer edge  52  of the loader plate  48  beneath the upper surface  50  to accommodate clamping structures  28  (for example, as shown in FIG. 1) according to the particular application. 
     Referring to FIG. 2, in operation, the loader plate  48  may be used instead of the cliché  12  for covering the opening  36  of a paint filled paint pod  32 . The joined loader plate  48  and cliché  12 , held by operation of the magnet  38 , may then be inverted and the transfer edge  52  of the loader plate  48  engaged against the edge  54  of the cliché  12  as shown in FIG.  3 . Magnets  64  in alignment arms  56  and  58  hold the upper surface  50  of the loader plate  48  co-planar with the upper surface  14  of the cliché  12 , while magnets  70  pull the transfer edge  52  of the loader plate  48  against edge  54  of the cliché  12  eliminating any gap between the two. As held, a single operator may slide the paint pod  32  as shown by arrow  82  onto the cliché  12  and attached to the pivot arm  42  as shown in FIG.  1 . 
     By using additional paint pods  32  and loader plates  48 , the time required to fill paint pods  32  may be eliminated from the changeover time. A second loader plate  48  (not shown) may be used to remove the empty paint pod  32  through the reverse of the above process eliminating paint drips from the empty paint pod  32  as it is removed from the cliché  12 . 
     It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.