Method of manufacturing plastic injection mold tooling

Abstract

Provided is a steel alloy and process for manufacture thereof. The steel alloy has improved ductility, weldability and dimensional stability. Also provided is a manufacturing mold having a manifold that may be formed of the steel alloy. The manifold may include sprues or runners such that the manifold may be used in plastic injection mold. The steel alloy has the chemical composition comprised of (by weight percent) about 0.16-0.2 carbon, about 0.6-0.9 manganese, up to about 0.02 phosphorous, up to about 0.02 sulfur, about 0.25-0.45 silicon, about 2.3-2.7 chromium, up to about 0.2 nickel, up to about 0.15 copper, up to about 0.15 molybdenum, about 0.15-0.03 aluminum and the balance being iron with trace amounts of ordinarily present elements. The steel alloy is electric furnace melted, ladle refined, vacuum degassed and argon shield poured in order to ensure cleanliness and quality.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority to U.S. Provisional Application Ser. No. 60 / 509,953 entitled P1 ALLOY filed Oct. 9, 2003.STATEMENT RE: FEDERALLY SPONSORED RESEARCH / DEVELOPMENT[0002](Not Applicable)BACKGROUND[0003]This invention relates to a steel alloy and, more particularly, to a tool steel alloy having good machinability and dimensional stability and being specifically designed and optimized for use in plastic mold tooling.[0004]Tooling for plastic injection molds has evolved with increasing sophistication as the uses of and demands upon plastics have grown. Such tooling may include hot runner manifolds that may be fabricated of steel alloy. However, known alloy steels that are currently used for such tooling applications suffer from several deficiencies that detract from their overall utility. For example, alloy steels currently used for plastic injection mold tooling may have unfavorable ductility characteristics such that the...

AI Technical Summary

Benefits of technology

The patent describes a special steel alloy that can be used in plastic injection molding tools. The alloy has a specific chemical composition that makes it strong, ductile, weldable, and dimensionally stable. The process for making the alloy involves melting it in an electric furnace, refining it in a ladle, and removing impurities through vacuum degassing and argon shielding. The resulting product is flat and free of bending stresses and heavy scale. This special steel alloy can improve the performance and durability of plastic injection molding tools.

Problems solved by technology

However, known alloy steels that are currently used for such tooling applications suffer from several deficiencies that detract from their overall utility.

For example, alloy steels currently used for plastic injection mold tooling may have unfavorable ductility characteristics such that the tooling may fracture under relatively low deformation loads.

In addition, such alloy steel may possess poor weldability characteristics making fabrication and repair of the tooling difficult.

Furthermore, currently known alloy steels used in plastic injection mold tooling may suffer from poor dimensional stability manifested by high levels of waviness and wrinkling in the material in addition to warping of the material at elevated temperatures.

Other deficiencies of currently known alloy steel used for injection mold tooling are low strength and low hardness properties.

In addition, ESR and VAR practices may result in a high level of cleanliness and a generally homogenous microstructure of the alloy steel.

Unfortunately, ESR and VAR refining is associated with an excessively high overall cost in the production of the alloy steel.

Furthermore, the production of alloy steel using ESR and VAR refining may entail even further costs when the chemical composition by percent weight of the alloy steel is restricted to within a relatively narrow range.

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