Printing – Printing members – Plate mountings
Reexamination Certificate
2000-02-09
2002-01-29
Gulakowski, Randy (Department: 1746)
Printing
Printing members
Plate mountings
C072S482900, C156S272400, C216S036000, C216S041000, C216S105000
Reexamination Certificate
active
06341557
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the field of graphic arts and especially to graphic arts impression dies such as copper, magnesium, bronze or other non-ferrous metal/ferromagnetic laminated dies. It also relates to graphic arts impression die assemblies for use on various types of stamping or embossing apparatus, including sheet or web-fed graphic arts presses such as clamshell, vertical or horizontal presses, and to improved processes for preparing the graphic arts impression dies and to preparation of impression graphic arts die assemblies. As used herein, the term graphic arts “impression die(s)” means at least the categories of graphic arts dies including hot foil stamping/blocking dies, embossing dies, debossing dies, embossing/debossing dies, combination/fluted/one-shot/foil embossing dies, and any other graphic arts dies which combine any one or more of these general types of die functions on a single plate for smooth, lenticular, textured or grained surfaces, or any other similar graphic arts metal, polymeric or composite impression dies.
More particularly, the invention concerns a cladded metal graphic arts impression die plate having a non-magnetic layer of metal integrally joined with a ferromagnetic layer of metal. A relieved, design-defining surface is provided in the outer face of the non-magnetic layer of metal. The graphic arts impression die plate is mounted on a magnetic support member and held in position thereon at least in part by a series of permanent magnets embedded in the magnetic support member in disposition to magnetically attract and hold the ferromagnetic layer of the graphic arts impression die plate supported by the magnetic support member.
The magnetic support member with the cladded metal graphic arts impression die plate thereon is adapted to be affixed to the chase of a stamping or embossing machine such as a sheet or web-fed graphic arts press, in disposition with the design-defining surface of the graphic arts impression die plate in alignment with a predetermined design location.
The utilization of a cladded metal sheet having a non-magnetic layer integral with a ferromagnetic layer for the graphic arts impression die plate facilitates formation of a relieved design in the outer surface of the non-magnetic layer, either by way of a chemical etching process, mechanically using a pantograph milling machine, a computer numerically-controlled (CNC) laser or mechanical milling machine or an operator-controlled milling machine, or by hand-engraving. The cladded metal sheet having a photo-resist coating on the outer surface of the non-magnetic layer of the sheet may be affixed to a magnetic support member through the medium of a series of permanent magnets on the magnetic support member which attract the ferromagnetic layer of the sheet. The magnetic support member and the cladded metal sheet thereon may then be positioned in an etching machine for etching of the exposed areas of the non-magnetic layer of the cladded metal sheet which are not protected by the photo-resist coating. The magnetic support member having embedded permanent magnets therein may also be used to support the cladded metal sheet blank in a chemical etching machine, CNC, pantograph, or operator-controlled milling machines, or during hand engraving, resulting in a design-defining surface. The magnets embedded in the magnetic support member are especially important in stabilizing the central area of the relatively thin cladded metal sheet blank while it is being machined.
2. Description of Related Arts
Stamping dies have long been used in the graphic arts field to apply thin metal foil or thin layers of other transferable material to a substrate such as paper, cardboard, thin metal films or plastic in accordance with a design formed in the stamping surface of the die. Similarly, embossing dies have been provided to emboss or deboss a desired design in a suitable substrate, and to produce lenticular lines, texturing or graining impressions in the paper, plastic, thin metal film or cardboard. Combination dies which combine hot foil stamping or blocking, embossing or debossing, or formation of other surface feature designs are also well known in the art.
Graphic arts impression dies as described have long been prepared by etching or engraving a desired design in the outer surface of a metal plate, usually magnesium, copper or brass. These metal plates generally were of sufficient thickness, as for example about ¼ in., to cause the plate to be essentially self-sustaining. In the case of relatively long embossing or stamping runs involving as many as hundreds of thousands of impressions, it has been past practice to employ relatively long lived graphic arts impression die plates made of a metal such as copper or brass. For intermediate length runs, the plates were usually made out of magnesium which was less expensive and easier to engrave or etch a relieved design area than with copper or brass.
In those instances where the runs are shorter and any inherent wear of the die surface is acceptable from a final product quality standpoint, non-metal graphic arts impression dies have largely supplanted copper and brass, and even magnesium plates in more recent times by less costly and simpler non-metal dies. For example, steel-backed photo polymer graphic arts impression die plates have been developed in which a hardened photo polymeric composition representing the desired design is supported on a steel backing plate. These steel-backed photo polymer plates can be used with conventional foil stamping and embossing equipment.
Photo polymer graphic arts impression die plates are generally thinner than conventional magnesium, copper or brass graphic arts impression dies, and therefore a spacer plate has been required between the photo polymer graphic arts impression die plate and the chase of the stamping or embossing machine to avoid the necessity of modifying the embossing or stamping equipment.
Pat. No. 5,904,096 (“'096”) of May 18, 1999, shows and illustrates one type of spacer plate that can be used to support a photo polymer graphic arts impression die plate on the chase of an embossing or stamping machine. The spacer plate of the '096 patent is provided with a series of permanent magnets which are described as being capable of magnetically attracting and holding the steel plate portion of the graphic arts impression die plate and thereby the photo polymer die assembly on the spacer plate. Use of a spacer plate of an appropriate thickness serves to support the photo polymer die in the required spaced relationship from the surface of the chase.
There is a need though for a graphic arts impression die which substantially has the longevity of conventional copper or brass dies, yet is less costly and easier to manufacture than conventional metal dies made of copper or brass. There has also been a need for decreasing the make-ready time involved in mounting of a hot foil stamping or blocking, embossing or debossing die on stamping or embossing equipment, particularly from the standpoint of proper alignment of the die with respect to the image onto which the foil is to be applied, or the image to be embossed or debossed. A further important need in the graphic arts impression die field is to provide a die which may be changed out and replaced in the stamping or embossing equipment or apparatus in a significantly shorter period of time than is presently the case.
SUMMARY OF THE INVENTION
An improved metal graphic arts impression die is provided which is made up of a cladded metal die plate having a design-defining non-magnetic metal layer such as copper, magnesium, bronze, or other non-ferrous metal which may be cladded to a ferromagnetic support layer that for example may be a steel sheet. A relieved area in the non-ferrous layer defines the design to be foil stamped, embossed, debossed or impressed. In a preferred form, the laminated metal graphic arts die plate has a layer of copper clad to a sheet of carbon stee
Hutchison Glenn E.
Scholtz Todd E.
Gulakowski Randy
Hovey Williams Timmons & Collins
Olsen Allan
Universal Engraving, Inc.
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