US2873709A

US2873709A - Coated die structure and method

Info

Publication number: US2873709A
Application number: US363856A
Authority: US
Inventors: Michael J Celovsky
Original assignee: Lyon Inc
Current assignee: Lyon Inc
Priority date: 1953-06-24
Filing date: 1953-06-24
Publication date: 1959-02-17
Anticipated expiration: 1976-02-17

Description

Feb. 17, 1959 M. J. CELOV SKY 2,

COATED DIE STRUCTURE AND METHOD Filed June 24, 1953 2 Sheets-Sheet 1 .IZYZE YZZET MC'HA'EL cf CEL 01/55,

Feb. 17, 1959 M. J. CELOVSKY COATED DIE STRUCTURE AND METHOD Filed June 24. 1953 2 Sheets-Sheet 2 Maw/25L (I CELOl/SEV United States Patent '0 COATED DIE STRUCTURE AND METHOD Application June 24, 1953, Serial No. 363,856

2 Claims. (Cl. 113-49) The present invention relates to improvements in sheet metal drawing or forming die techniques, and more particularly relates to the provision of a die member against which highly polished sheet metal surfaces can be pressed without damage to the finish of the sheet metal article.

An important object of the present invention relates to the treatment of shaping or forming die surfaces for sheet metal work to enable highly polished sheet metal surfaces to be pressed under substantial pressure against the die surfaces without abrading or otherwise damaging the polished surfaces.

A further object of the invention is to provide an improved coated die structure.

Still another object of the invention is to provide a sheet metal die structure having the surface thereof treated to provide a thin cushioning layer thereon which will withstand high pressures in service without damage.

Yet another object of the invention is to provide a novel coating for the pressure surfaces of sheet metal dies.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings in which: I

Figure 1 is a more or less schematic vertical sectional detail view of a portion of a sheet metal working die of a kind particularly adapted for making wheel covers, and embodying features of the present invention;

Figure 2 is a fragmentary top plan View of a coated die member of the assembly shown in Figure 1;

Figure 3 is a fragmentary more or less schematic vertical sectional View through a modified form of sheet metal working die assembly embodying features of the invention;

Figure 4 is a fragmentary top plan view of a coated die member of the assembly of Figure 3; and

Figure 5 is a fragmentary side elevationalview of a wheel cover after it has been formed in the die assembly of Figure 3.

In the manufacture of sheet metal articles such as wheels covers, that is covers adapted to be applied to the outer sides of vehicle wheels such as automobiles, certain forming operations must be performed after at least certain external surface areas of the cover have been highly polished. As an incident to the forming operations, the highly polished surface areas are necessarily forced with substantial pressure against a die surface and are therefore liable to abrasion or pressure damage of the polished areas.

According to the present invention, the surfaces of the die elements which must engage under pressure with highly polished surface areas of sheet metal articles such as wheel covers in the process of formation of the articles are coated with a highly pressure resistant, .chipproof thin cushioning coating of an enamel, and more particularly a synthetic enamel. Excellent results have been obtained in practice with an enamel in which the 2,873,709 Patented Feb. 17, 1959 body ingredient is a phthalic alkyd resin. In a preferred formula, the enamel comprises pigment approximately 20.8%, synthetic resin 30.2%, solvents 49% and comprising aliphatic hydrocarbon 18.1% and aromatic hydrocarbon 30.9%. For ready identification of the surface the pigment is preferably a bright color such as chrome yellow.

In treating a die surface with the enamel, the die surface is first cleaned in hot caustic solution and is thereafter bonderized, that is, treating the surface with a solution of primary manganese di-hydrogen phosphate and a small percentage of a copper salt by dipping or spraying on the solution. Thereafter, the enamel is sprayed onto the die surface to be treated in a double wet coat. The coated surface is then baked at 280 to 290 F. for about one hour. No driers are used in the enamel. The alkyd resin is preferably in a pure, unmodified form. The resulting coating is highly resistant to pressures, is satisfactorily resilient and is chipproof. It is thus long wearing so that a die can be used a large number of times without requiring recoating.

As an example of a die structure in which the present invention has found-a high degree of utility, reference is made to Figures 1 and 2. A die base 10 has thereon circular ring dies comprising an inner die member 11 and an outer die member 12 which are provided with working surfaces properly profiled to match and thereby receive uniformly thereagainst the outer surfaces of a wheel cover plate 13 made from sheet metal and having the outer surfaces thereof highly polished as to a substantially mirror finish. In the present instance, the inner die ring 11 serves primarily as a centering die to receive a more or less frusto-conical intermediate portion 14 of the cover plate 13, while the outer die member 12 provides a. bearing surface to receive uniformly thereagainst an outer marginal portion 15 of the cover plate and to support such outer marginal portion against deformation while a hold down ring die member 17 presses an outer marginal portion of a second cover plate member 18 against the back face of the cover plate portion 15. As will be observed, the cover plate 18 has a portion 19 thereof directed convergently to the outer extremity portion of the cover margin 15 where a marginal extremity flange 20 of the cover portion 19,

ably by a die head 21, with springs 22 normally urging the hold down die ring 17 into substantial spaced relation to a backing plate member 23 carried by the die head 21.

Upon downward movement of the die head 21 to drive the hold down ring 17 against the marginal portion 20, a crimping die ring 24 carried by the outer perimeter of the backing plate 23 operates to turn an extremity flange 25 of the marginal portion 15 over into crimped retaining relation to the plate margin 20 for thereby uniting the

cover plates

14 and 18. Pressure of the hold down member 17 is reflected in substantial pressure of the cover marginal portion 15 against the opposing bearing surface of the die member 12. Accordingly, the bearing surface of the die member 12 is provided with a cushioning coating 27 of the protective coating enamel as described hereinabove. This affords protection against damage of the highly polished external surface of the cover marginal portion 15.

Inasmuch as direct pressure from the hold down member 17 is exerted on a narrow annular marginal extremity portion of the cover portion 15, it has been found desirable to omit the cushion coating 27 from the annular outer extremity marginal area of the hearing surface of the die ring 12, as indicated at 28. The

concentration of pressure in this narrow area is so great that the life of the enamel coating would be too short to be practicable in this narrow area as compared to the remainder of the bearing area. Moreover, the narrow area 28 is preferably highly polished complementary to the highly polished surface of the opposing cover surface so that danger of damage of the highly polished surface is substantially eliminated.

In the modified die assembly of Figures 3 and 4, a cover of different type is shaped. In this die assembly, a base plate 30 supports a ring die member 31 carrying a clamping ring die member 32 which is normally elevated relative to the die member 31 through the medium of springs 33.

Opposing the clamping ring 32 is a hold down ring die member 34 attached to a forming die ring 35 carried by a backing plate 37 supported by a die head 38. The die ring 35 has forming surfaces 39 cooperative with recesses 40 in the underlying die ring member 31 inside of the clamping die ring 32 for producing embossments 41 in a cover member 42 which has a marginal annular portion 43 of dished cross-section clamped between the clamping ring 32 and the hold down die member 34 during the forming or drawing action of the cooperative die members.

Since the outer dished surface of the cover portion 43 is highly polished and bufied to a mirror finish, it must be protected against pressure damage between the die members 32 and 34. To this end, the cover surface opposing bearing surface of the clamping die member 32 is provided with a protective enamel coating 44. This provides a cushion and protective resilient surface between the bearing face of the die member 32 and the highly polished surface of the cover portion 43. It will be observed that inasmuch as the pressure against the cover portion 43 is substantially uniformly applied over the entire surface engaging the clamping die member 32, the entire bearing surface is coated with the coating 44.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a die structure, a circular die member having an annular surface receptive of a highly polished complementary surface of a sheet metal member and against which annular die surface the sheet metal member must be pressed with substantial pressure for holding the sheet metal member immovable while forming operation is effected upon the sheet metal member by yet other die means, said annular surface having thereon, except for a narrow annular marginal portion thereof, and thoroughly bonded thereto a highly pressure resistant but satisfactorily resilient and chip-proof layer of a sub- 5 stantrally pure unmodified alkyd resin enamel free from driers and fused by baking, and effective as a cushion to prevent abrasion or pressure damage of the polished sheet metal article surface pressed thereagainst, said narrow marginal portion being highly polished for receiving thereagainst a corresponding narrow annular portion of the surface of the sheet metal member against which forming pressure is applied in excess of the pressure applied against that portion of the sheet metal surface opposed by the baked enamel'cushion.

2. In a process for die shaping sheet metal articles having polished surfaces susceptible of marring when subjected to forming pressure between opposing dies and which polished surfaces must be protected against marring while being subjected to the forming pressures between the dies, the method of preparing a die member for supporting against a substantial surface area thereof an opposing highly polished surface of a sheet metal member under substantial pressure of the opposing die directed toward said die member surface area, cleaning said surface area of the die member, treating said cleaned surface area to enhance the adhesion thereto of an enamel coating, applying to said die surface area in fluid form an enamel composition free from driers and consisting essentially of a substantially pure unmodified phthalic alkyd resin as the major solids component, and solvents, and baking the coating for a time interval and at a temperature sufficient completely to fuse the enamel coating and provide a highly compression pressure resistant and chip-proof resilient cushion upon said die surface area, serving as a protection against marring of the polished sheet metal surface pressed thereagainst and then pressing the polished surface of said metal member against the resilient cushion protected surface area of said die member.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Publication: Alkyd Resins as Film-Forming Materials, General Electric Co. (-1929).

Publication: Heat Treating and Forging magazine, June 1943, pages 290-291.