In re Jansson

609 F.2d 996

• Court: Court of Customs and Patent Appeals
• Decided: November 8, 1979
• Docket: Appeal No. 79-552
• Status: Published

Opinion

RICH, Judge.

This appeal is from the decision of the United States Patent and Trademark Office (PTO) Board of Appeals (board) affirming the rejection of claims 6-11 in appellant’s application serial No. 579-278, filed May 20, 1975, for “Method for the Production of Tools for Deep Drawing, Moulding, Extruding and the Like,” under 35 U.S.C. 103 as obvious from the teachings of the prior art references. We reverse.

The Invention

Appellant discloses a method for producing substantially rigid tools, i. e., dies, having hard wearing surfaces of sprayed metal. Dies are negative forms used for the production of many replicas. Therefore, it is critical that the die face closely conform to the face of the original article or the pattern or model thereof. The prior art recognized that molten metal sprayed onto a form warped upon cooling unless restricted to very thin coatings. Appellant’s specification states that sprayed steel rises from its foundation if sprayed thicker than 0.2 mm.

A hundred-fold increase in the thickness of a wearing layer of a die is said to be attainable by the present invention. The following drawings best illustrate the claimed method.

A die pattern is formed by spraying a readily-fusible, thin metal or alloy layer (12) over a die model (10) which has been coated with a release agent (11). Next, a heat-resistant plastic backing (13) is added to the fusible facing to finish the pattern.

Separation of the pattern from the model precedes formation of a die replica. As seen in Fig. 2B, a hard wearing layer (14) such as steel, carbide, or oxide is sprayed onto the fusible layer (12). Heat resistant plastic (15) is then also used to back the die replica.

Release of the pattern from the replica is achieved by applying heat. The two metallic layers are easily separated once the thin, readily-fusible pattern facing is fused.

The References

Nicholson 2,515,017 July 11, 1950

Gilliland et al. 3,228,650 Jan. 11, 1966

(Gilliland)

Fraser et al. 3,405,212 Oct. 8, 1968

(Fraser)

Folger et al. 3,565,978 Feb. 23, 1971

(Folger)

Gilliland also addresses the problem of die inaccuracy due to warpage. A frame forming part of the die structure is positioned about a die pattern of zinc-tin alloy. As seen below in Figs. 3 and 5, a facing layer of metal (20) having a fusion temperature between 1800° and 2000° F. is sprayed onto the pattern (10). Backing material (22) is then sprayed onto the facing layer. Finally a steel plate (26) which covers the backing layer is bolted to the frame (14). An important function of the frame is to reduce “the tendency of the sprayed metal facing from warping and moving away from the pattern during the spraying operations.”

The die replica is released from the pattern by melting the zinc-tin alloy of the pattern. The separated die assembly (Fig. 5) is then heated in order to fuse the facing layer to the backing layer.

Nicholson teaches a mold sequence for the “lost wax” process. A negative wax mold is formed upon a positive article. Then, a metal mold replica is created from the negative wax mold by encasing the wax in a flask, melting out the wax, and pouring in metal. The metal mold is then used to reproduce desired articles.

Fraser discloses the production of plastic-contour dies coated with sprayed metal. The plaster pattern of the die is impregnated with a water-soluble, thermoplastic material. By dissolving the thermoplastic material, the pattern is released from the die.

Folger also relates a molding sequence wherein a negative replica is employed to form a positive replica.

The Rejection

The examiner stated that Gilliland teaches a basic method of making a sprayed metal die from a metal pattern. The secondary references evidence that plastic backings for sprayed metal facings are also known. He admitted that while Gilliland teaches patterns formed from fusible alloys and thin layers of sprayed metal, it does not teach the use of them together.

The Board

The board affirmed the rejection of claims 6-11, saying that Gilliland discloses the use of an easily-fusible, zinc-tin alloy pattern which is melted to release a die. The board states that appellant’s invention differs from the primary reference only in that the easily-fusible pattern is not solid but is a thin fusible layer backed by a heat-resistant plastic and that the resolution of this case lies in the unobviousness of the pattern-forming steps.

Appellant’s Arguments

The crux of appellant’s arguments is found in his Reply Brief. He contends that the references disclose the use of sprayed metal layers only for the final die products corresponding to the wearing layer (14) of his die. The use of a layer of easily-fusible metal on a die pattern, from which the die is made, is not disclosed by any of the references.

OPINION

Claims 7-11 are not argued separately by appellant. Since these claims are method limitations dependent upon independent claim 6, all the claims will stand or fall together.

The issue is whether or not the combined references would have suggested the claimed method of die fabrication as a whole to one of ordinary skill in the art at the time the invention was made. Specifically, would the references have suggested the formation of a die pattern employing a thin layer of an easily-fusible metal or alloy backed by a heat-resistant plastic?

The examiner’s reasoning in reconstructing the claimed method from the references is in error. He admits that Gilliland does not teach using layered patterns having an easily-fusible facing. Yet, he concludes that it “would be obvious to use this for the surface ‘20’ in Gilliland” (his hard die facing) in making a first mold to make a pattern, since such hypothetical mold “need not be indestructible.”

The examiner has confused Gilliland’s die wearing surface “20” with appellant’s claimed fusible layer “12.” The attempted logical nexus whereby a sprayed wearing layer and a solid, easily-fusible pattern are supposed to suggest a thin, fusible layer for a pattern surface is not readily apparent to this court and is, in any event, impermissible hindsight reasoning.

In affirming the examiner, the board presents a modified rationale which in substance is based upon the following. Nicholson suggests the molding sequence of appellant’s claims. Gilliland relates the use of an easily-fusible zinc-tin alloy for a die pattern. Fraser discloses layered molds wherein metal is backed by plastic. Therefore, the layering of a pattern with a fusible metal facing would have been obvious.

None of the references suggests any layering of a pattern with a readily-fusible metal. Nicholson is remotely related to the present method only by disclosing a generalized molding sequence, but in a lost-wax method. Fraser directs the use of a metal facing in the formation of a die, not a pattern, and was cited only for the showing of plastic instead of metal backing. Admittedly, Gilliland does state that a die pattern made wholly from an easily-fusible alloy facilitates the release of the die, but his method for forming a pattern differs significantly from the appealed claims. The solid fusible pattern of Gilliland is either hand-worked or pressure cast from an existing master die. None of these pattern-forming steps suggests the layering of the pattern with a readily-fusible metal or alloy, we agree with appellant that the board’s reasoning is also hindsight reconstruction.

Appellant’s use of a fusible metal layer on a die pattern represents a solution to the warpage problem of sprayed metal dies withoüf'resórtfñg to bulky frames and backing plates. The result is an accurately formed die with a thicker wearing surface. In view of the foregoing, the rejection of claims 6-11 is reversed.

REVERSED.