Abstract:
An engraved surface in a metallic workpiece and an engraving method therefor, for use in providing a decorative metallic surface. An engraved pattern is formed in a workpiece prior to the formation of an electroplated layer that continuously extends over the engraved pattern and adjacent surface areas of the workpiece. The engraved pattern includes wall-cut engravings inscribed in the workpiece that are used to define outer boundaries of the engraved pattern. The substantially vertical walls obtained by such wall-cut engravings permits a sharp, well-defined boundary between the engraved pattern and adjacent painted surfaces. A mask material is first applied to cover the engraved pattern, and then trimmed to create the sharp edge at the boundary of the engraved pattern. This permits a paint layer to be formed immediately adjacent to the engraved pattern, providing a decorative juxtaposition in an electroplated metallic surface after removal of the mask layer.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/388,594, filed Jun. 12, 2002. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an engraving technique and resulting engraved metal surface and, more particularly, to such engraved metal surfaces as may be decoratively employed. More specifically, the present invention relates to engraved metal surfaces, and the process to obtain same, that permit subsequent electroplating and colorization to obtain highly decorative surfaces. 
   2. Description of the Prior Art 
   It has been estimated that for the year 2001, the value of the U.S. Gross Domestic Motorcycle Product (GDMP) is approximately $25 billion. Approximately $5 billion is in new motorcycles, the remainder in the sale of used cycles, parts, and services relating to motorcycle sales and maintenance. 
   The Harley-Davidson V-twin cycles have been a large participant in the revival in motorcycle popularity beginning in the early 1990&#39;s. Such motorcycles cater to the individualistic rider, and while the outward appearance may seem unvarying to non-riders, it is important for most Harley owners to differentiate their motorcycle in some important visual manner. 
   Since many motorcycles share the same or similar aftermarket parts, oftentimes the visual differences arise from the paint and graphics applied to tanks and fenders. These parts are small and easily removed, making them far easier to paint than automobiles. As many riders discover, however, the paints that are most readily available and easily applied also tend to degrade the fastest in response to sunlight, weather, and general wear and tear. 
   Professional motorcycle painting traces its genesis to Kenneth “Von Dutch” Howard, a custom painter out of the 1950&#39;s and 1960&#39;s southern California school that also featured Ed “Big Daddy” Roth. Von Dutch had a talent for design and craftsmanship that essentially invented the motorcycle art of pinstriping. 
   Such exotic paint schemes have since evolved to ones that cost thousands of dollars and involve elaborate airbrush techniques and pigmentation. When clear-coated with protective layers, these elaborate works of art might last several years if reasonable attended to by the owner. Such owners often highlight their paint schemes by adding various chromed metal accent pieces. Most motorcycle owners, like the collectors of 1950&#39;s and 1960&#39;s automobiles, particularly value the deep metal shine of chromed parts. 
   Motorcycle fenders, gas tanks, and other small metal exterior parts are generally fabricated out of steel, aluminum, and brass or similar such metals. Finishing typically involves electroplating, using copper, nickel, chrome, brass, silver, gold or a combination, or painting, as previously described. It is normally not possible to electroplate over a painted surface, or paint over an electroplated surface—the latter being too smooth for the paint to reliably adhere. 
   Metal engraving is a well-known art, and provides designs of long last, since they represent cuts into the outer metal. If the part is to be electroplated, such coating must be applied after the engraving, since otherwise the engraver would remove the electroplated layer as the design is formed into the metal. Such breaks in the chrome layer would encourage further separation of the chrome from the underlying metal, resulting in the “peeling chrome” look that was common on aging chrome automobile bumpers in the snow and ice “road salt” areas of the United States. 
   Unfortunately, pre-electroplate engraving presented other technical problems. When using present laser, pantograph, rotary or other mechanical means, the engraved lines would be largely covered by the subsequently applied plated surface, considerably lessening, if not entirely eliminating, the impact of the engraved design. 
   Ideally, it would be desirable to provide a decorative metal surface that is able to utilize the long lasting benefits of engraving with the deep metal finishes provided by electroplating and the rich color obtained through paint pigments. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide an engraved surface that can be subsequently electroplated without definitional loss of the overall engraved design. In this regard a surface having a greater depth and wider engraved angle is provided. 
   It is a further object of the present invention to provide both a painted and engraved electroplated surface. By the utilization of both engraving and the application of a protective mask, both types of surfaces can be obtained. After electroplating the part, preferably first with copper and then a final electroplated coating of nickel, the engraved area is masked, and the area where paint will be applied is first roughed and then painted. 
   After removing the mask, the entire surface is covered with a protective coat, resulting in co-existing engraved and painted electroplated surfaces. Visually, the metal surface displays a deep, engraved cut design with the shine of a nickel electroplate, with immediately adjacent surfaces having a durable painted coating. 
   These objects, as well as other objects and advantages of the present invention will become readily apparent upon review of the description of a non-limiting illustrative embodiment and the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a motorcycle fender having an engraved design portion in accordance with the present invention. 
       FIG. 2  is a cross-sectional view taken along line  2 - 2  of  FIG. 1 , showing placement of an engraved design on a fender part in accordance with the present invention. 
       FIG. 3A  is an enlarged partial perspective view showing a shallow engraving cut in a metal workpiece, representative of prior art engravings. 
       FIG. 3B  is an enlarged partial perspective view showing a “V-” type engraving cut and an attempted masked application of a paint, again representative of prior art techniques. 
       FIG. 3C  is an enlarged partial perspective view showing an engraved cut and applied paint layer in accordance with the present invention. 
       FIG. 4A  is an enlarged partial elevation view showing an engraved cut beneath paint and mask layers in accordance with the present invention. 
       FIG. 4B  is an enlarged partial elevation view showing an engraved cut beneath a protective coating covering bare engraved metal immediately adjacent a paint coating in accordance with the present invention. 
       FIG. 5  is a schematic view of a method for fabricating the engraved and painted metal surface of  FIG. 4B . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference is now made to the drawings wherein like numerals refer to like parts throughout. In  FIG. 1 , a motorcycle fender  10  is shown, rounded in a conventional manner to protect the motorcycle (not shown in the Figures) from debris picked up from the road by the tire. The majority of motorcycle external parts are fabricated out of steel, in various forms, such as stainless, cold-rolled, carbon, or out of various forms of aluminum, such as milled, billeted, cast, and molded. Additionally, although a motorcycle fender piece is depicted, the present invention is not to be viewed as in any manner limited to the purpose or nature of the underlying metal piece. 
   An engraved surface  14  is formed in a portion of the fender  10 . In a presently preferred embodiment, prior to forming the engraved surface  14  the metal part is first highly polished using known techniques and procedures. For example, depending upon the metal and its original surface state, various polishing compounds ranging from 80 to 1500 grit may be required. Such polishing, as well as other remedial metal processing, is intended to remove the gouges, dents, scratches, waves, ripples, and other commonly encountered surface defects in manufactured metal parts. After the metal surface is highly polished and otherwise free of these various defects, the part is ready to be engraved. 
   As is depicted in  FIG. 2 , the engraved surface  14  normally occupies only a portion of outer surface of the metal part. Hand engraving has been in existence for thousands of years. Skilled artisans push or hammer a sharp and extremely hard small metal cutting tool termed a “graver,” through a metal that is softer than the graver, to obtain precisely positioned cuts. The artful combination of numerous cuts creates the engraved design. 
   Originally relying upon rocks and then “chasing hammers” to push or strike the graver, subsequent improvements have allowed the engraver to use pneumatic devices, such as those disclosed in U.S. Pat. Nos. 3,393,755 and 5,515,930 to strike against the graver. These tools primarily serve as a time saving device for the modern engravers. 
   In more recent historical times there are mechanical and laser engravers that can be considerably automated. Turning to  FIG. 3A , a first workpiece  22  is shown having a u-cut engraving  24  formed therein. This relatively wide and shallow cut is exemplary of the types of cuts made by mechanical or laser engravers. Such cuts are appropriate for name engravings on trophies and the like, where there is to be no further processing of the metal part. It can readily be understood how overlaying an electroplated coating (not shown in  FIG. 3A ) might easily partially or completely fill the u-cut engraving  24 . 
   In  FIG. 3B  a second workpiece  26  is shown with a v-cut engraving  28  formed therein. A slumped paint layer  32  has been formed over a portion of the second workpiece  26 . The failure of the painted layer to properly form is as a result of the sloped sides of the v-cut engraving  28 . Where the slope is insufficiently steep, it becomes difficult to accurately mask off the non-painted area, and it likewise is difficult to accurately remove only the mask and not the paint layer after the painting is complete. In some ways, the best that can be done is to cut along the extended slope, resulting in a feathered paint layer (not shown in the drawings). 
     FIG. 3C  depicts a presently preferred manner of engraving, with a third workpiece  36  having a wall-cut engraving  38  formed therein. Having a substantially vertical outer wall, the wall-cut engraving  38  provides a template for fabricating a fine-edge paint layer  42  having an edge that extends vertically from the wall-cut engraving  38  in the manner of a paint wall  44 . Such an accurate placement of the paint edge is essential towards the creation of an esthetically pleasing design. 
   In  FIG. 4A  the resultant structure is illustrated in the context of the wall-cut engraving  38  made in the fender  10 . To assure their visibility after one or more electroplated layers have been deposited, in accordance with the presently preferred embodiment, the engravings are inscribed to a depth in the metal workpiece of between 0.010 inches to 0.017 inches, with width of the engravings varying between 0.010 inches and 0.050 inches. Subsequent to such engraving an electroplate layer  52  is deposited over the entire surface of the fender  10 . Such layers are typically very thin, ordinarily in the range of 0.005 inches to 0.008 inches in depth. A mask material  56  is then deposited over a selected surface of the fender  10 , including within the wall-cut engraving  38 . The substantially vertical wall of such engraving permits the formation of a substantially vertical mask edge. A paint layer  62  is formed over the un-masked surface of the fender  10 , forming the paint wall  44  at its interface with the mask material  56 . 
   As is depicted in  FIG. 4B , upon removal of the mask material  56 , a sealant or clear coat layer  66  is formed over the entire outer surface of the fender  10 . An indentation  72  is formed in the clear coat layer  66  in substantial registration with the wall-cut engraving  38 . This surface expression of the distinctive engraving further enhances the visual impression of both its depth and the visual metallic purity of the electroplated layer  52 . 
     FIG. 5  depicts, in schematic form, a simplified method for creating the component layers of the engraved surface  14  of  FIG. 1 . After selection, a metallic part, such as the fender  10 , is initially secured  82 . 
   The surface of metallic parts are subjected to all types of contaminants, both as a result of fabrication and caused by conditions encountered during transport and storage. Prior to initiation of further processing, all such surface contaminants must be stripped  84  from the metallic part. Various solvents are known to the art and are appropriate for specific types of contaminants and types of metal. 
   Such preliminary surface treatment continues with a robust surface polishing  86  to remove as many surface defects as possible. As mentioned previously, this will typically involve the use of a variety of polishing compounds selected as required by the surface blemishes and the type of metal to be polished. 
   A design is then applied  88  to the appropriate surface area or areas on the metal part. In a preferred embodiment such application is by conventional means, such as being directly drawn on the part or by a design transfer from a paper rendition to the metal part. 
   The transferred design is then engraved  92  into the metal part. In a presently preferred embodiment, the engraving is done by hand using traditional hand engraving methods and tools. The invention is not to be viewed as in any way limited to hand engraving. The factors presently viewed to be important are that the engraving be of sufficient depth to remain distinctive after an electroplated layer is applied and that the engraving create a wall-cut feature, meaning that the outer engraved walls must be substantially vertical, with a range of between 80 to 90 degrees presently viewed to be acceptable for the purposes of the present invention. 
   After engraving the metal part is again polished, to smooth any stray markings and normal engraving nicks and burrs. Once the surface is again satisfactorily smooth, the part is electroplated  94 . As presently preferred, the initial electroplate layer is of copper, which enhances the ability to obtain a more uniform and adhering second layer of nickel. The secondary layer can be of other metals, such as gold, silver, brass, and others; however, nickel is presently preferred due to the deepness of its metallic shine—assuming a chromed-type surface reflectivity. 
   Optionally, an adhesion promoter is applied  96  to the metal part prior to the application of a clear coating material  98 . This coating is then allowed to dry or cure for a period of preferably 24 hours. Such a coating, when used, further enhances the adhesion properties of the subsequently applied paints. 
   Depending upon the desired optical effects of a particular design, a liquid mask material is applied  102  to selected portions of the metal piece. Appropriate mask materials might include Metal Flake Spray MaskT™ manufactured by the Metal Flake Corporation of Amesbury, Mass. An appropriate time is accorded to permit the complete curing of the mask material—such as 24 hours when Metal Flake Spray MaskT™ is used. 
   Whether airbrushed or physically painted on, the mask material is purposefully applied approximately ¼ inch beyond the engraved area borders. This excess material must be removed, and typically the mask material lying outside of the engraved area is removed utilizing a small cutting tool such as a razor blade or an EXACTO® knife  104 . Such a tool creates a clear and distinct line of masking material separating the engraved area from the non-engraved area. Essentially an extremely thin, substantially vertical “wall” of masking material is formed between the outside line of the engraving and the non-engraved portion by this trimming procedure. 
   The exposed, un-masked surface regions that are to receive a coating of paint are first subjected to a surface roughening  106  to enhance the adhesion of the paint to the electroplated surface. Such surface roughening can appropriately be obtained utilizing either a fine grit sandpaper or known liquid grit compounds. 
   One or more coats of paint are then applied and allowed to dry  108 . Various types of paint are appropriate, and the application process will depend upon the type of paint selected. Paints manufactured by House of Paints of Picayune, Miss. are appropriate for this procedure. Depending upon such factors as color and type of paint selected, it may be necessary to apply several coats of paint, sometimes in various colors, to achieve the effect desired. These considerations are primarily artistic in nature and are not the result of any requirements or limitations of the present engraved surface or method. 
   The masking material is then carefully removed  110 , revealing a sharp distinction between the electroplated, engraved surface and the painted area outside of the design. The “wall” of masking material has resulted in the creation of a “wall of paint” when the masking material is removed. This “wall” clearly and sharply delineates and physically separates the painted area from the nickel-plated, engraved design. 
   Where desired, color may be applied to the bottom portion of the engraved lines. A presently preferred manner of affecting such color utilizes the application of a small amount of paint within the engraved cuts. Such paint is then allowed to dry  112 . An example of an appropriate line of paints might be located from among those supplied by House of Kolor, Picayune, Miss. 
   Regardless of whether color is applied to the engraved lines, completion of the decorative surface requires the application of commercially available clear coat paint to seal both the engraved and painted areas  114 . Several separately applied clear coat layers may be required to enhance the project. The coatings are allowed to dry/cure and then one final polishing is performed on the entire surface  116 . 
   Our invention has been disclosed in terms of a preferred embodiment thereof, which provides an engraved, decorative surface of great originality and ornamentality that is of great novelty and utility. Various changes, modifications, and alterations in the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. It is intended that the present invention encompass such changes and modifications.