Method for making multi-colored composite laminates
TECHNICAL FIELD 
     This invention relates to a method for making multi-layer laminates and specifically to a method of making color karat gold composite laminates. 
     BACKGROUND 
     In the prior art it is known to make patterned multi-colored sheet gold by the traditional diffusion bonding processes such as Japanese mokume-gane technique, but these techniques are inadequate for mass production. This process involves heating layers of different colored sheet metals under pressure until bonding occurs. The resulting billet is a multi-colored sandwich that can be manipulated into a variety of patterns. In order to expose the colors contained within, the billet must be further worked by forging, bending or twisting. Engraving, filing, grinding, chiseling, machining, and other material removal means have also been used to create colored patterns. 
     This process, however, has proven to be ineffective for large scale production. The difficulty in pouring consistently successful ingots of the zincless alloys necessary in a heat-soaking process such as mokume-gane has proven unduly expensive and time consuming. Also, the quantity of the material produced as such as limited to the size and pressure capacities of many available bonding furnaces. 
     Subsequent to the production of the billets, further inconvenience is encountered when manipulating the sheet material to form patterns. The amount of machining required is complicated, expensive and time consuming. In addition, the machining of the sheet metal causes burrs at grooved intersections which burrs must be removed before subsequent rolling. In final preparation, the grooves in the machined metal must be rolled out to expose the routed pattern to the outer surface. This rolling causes excessive elongation and distortion of the design. Finally, the machined grooves can create undesirable stresses within the sheet material when the metal is rolled. 
     SUMMARY OF THE INVENTION 
     The invention relates to a method for making multi-layered composites by stacking a plurality of sheets in a predetermined order or pattern and bonding these sheets under heat and pressure to form a single composite laminate. Rolling the laminate after the bonding process ensures complete cohesion. 
     Once the composite laminate has been bonded, one of the outer surfaces of the laminate is provided with a raised pattern. Skiving or cutting off these raised patterns exposes, in cross-section, the colors of the underlying sheets which would otherwise be hidden within the body of the laminate. This is usually accomplished by passing the laminate through a skiving table. The outline of the sheet material which was initially raised and then trimmed back now exposes color patterns on the surface of the laminate. The possible combination of patterns and desired designs is endless. Finally, the laminate is rolled to a finished dimension having a flat surface and a color design thereupon. The laminate may then be reeled up like any other roll of sheet material for convenient shipping and storage. 
     A variety of materials and material thicknesses may be used depending upon the desired pattern and the laminate&#39;s intended use. In order to obtain artistic patterns, colored materials are preferred. Such materials include plastics, metal or metal alloys and karat gold alloys. 
     The bonding of the sheet materials may be accomplished in any appropriate manner which assure good adhesion, such as continuous bonding. The raised pattern may also formed in a variety of ways such as pressing, stamping or by passing the laminate through a deep steel pattern roll. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The nature, advantages, and various other additional features of the invention will appear more fully upon consideration of the illustrative embodiments now to be described in detail in connection with the accompanying drawing figures, wherein: 
     FIG. 1 is a perspective view of a composite laminate according to the invention; 
     FIG. 2 is a side view of the composite laminate of FIG. 1 having a raised pattern on one surface; 
     FIG. 3 is a side view of the composite laminate of FIG. 2 with the raised pattern skived; and 
     FIG. 4 is a plan view of the composite laminate illustrated in FIG. 3. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention relates to a method of making a multi-colored composite laminate wherein a variety of different colored materials are used to create ornamental patterns. Each aspect of the invention represents a significant improvement over previous manufacturing techniques. These improvements include: 
     (1) a finished composite strip having a flush, not grooved, surface; 
     (2) undistorted or elongated ornamental patterns; 
     (3) cost effective means for large scale production; 
     (4) a composite strip that can be reeled up into a roll; and 
     (5) an infinite number of patterns. 
     The method includes selecting the materials, colors, the stacking sequence, sheet width and thickness according to the final pattern desired. Other factors are also considered, such as the final width, thickness and ultimate use of the material. 
     A wide variety of materials are available for use in this method. For example, plastic, glass, fiberglass, metal or metal alloys may be used, however, the preferred materials include metals or metal alloys, preferably color karat gold. Materials are selected based upon features such as vividness of color, similar annealing properties and similar hardnesses. 
     Once the materials have been selected and the color sequence decided, strips of the material are stacked accordingly. The stack is then bonded by any suitable bonding method to form a billet having layers of different colors and/or materials. The preferred bonding method is a continuous bonding as disclosed in U.S. Pat. No. 3,095,500 to Jost which is incorporated herein by reference. 
     After bonding, the thin laminate stock is passed through a pattern roller to deform the layers thereby forming an embossed or raised pattern. This pattern may take on an endless variety of possible configurations but is preferably a series of ridges which are aligned in rows. Other available shapes would include cubes, cylinders or cones. The state of the art as such also introduces the possibility of forming letters to spell person or company names, or the precision to create well known patterns, distinguishing marks or logos on a consistent large scale, mass production basis. 
     Subsequently, the embossing is cut away or skived to expose in cross-section the colored layers of the desired design. The final design formed in cross-section depends on the geometry (height, width and shape) of the raised pattern formed by the pattern roller. For example, the final pattern may be a series of concentric ellipses aligned in rows. Each ring of the concentric ellipses will have a different color according to the stacking sequence of the laminate. Finally, the laminate is flat rolled to a finished dimension. 
     In an alternate embodiment, the laminate is passed simultaneously through two pattern rollers to form an embossed pattern on both the upper and lower surfaces. Thereafter, when the embossing is skived off both surfaces, a colored pattern will be formed on both. 
     Referring now to FIG. 1, there is illustrated a stacking sequence of color karat gold alloys strips which may vary in width up to and above about 3 inches. The sequence contains a variety of gold alloy strips which vary in thickness and color. The color, order and thickness of the strips are determined beforehand to comprise a desired ornamental pattern. Subsequently, the stack up is subjected to a continuous bonding procedure to form a thin bonded laminate 10. Laminate 10 is then given a final roll to ensure complete bonding and to achieve a desired thickness. 
     After the final rolling, laminate 10 is passed through a deep steel pattern roll (approximately 0.30) which forms a raised pattern 12 into its surface as shown in FIG. 2. Laminate 10 is next passed through a skiving table which skives off the raised pattern as shown in FIG. 3. The skiving exposes flat bands of the underlying color karat gold 14. The resulting product is a thin, flat laminate having an ornamental and colorful pattern on one surface. Laminate 10 is then flat rolled to a finished dimension and may be reeled up into a cylindrical roll. 
     While it is apparent that the invention herein disclosed is well calculated to fulfill the objects above stated, it will be appreciated that numerous embodiments and modifications may be devised by those skilled in the art, and it is intended that the appended claims cover all such modifications and embodiments as fall within the true spirit and scope of the present invention.