Automated system for selecting material and strengthening thermochemical treatment of gear wheels

Abstract

.The present article suggests an automated data bank for designing gear wheels." a system of correlated data on materials and their properties after strengthening under certain technological conditions. The data bank contains the marques and standard chemical compositions of steels, a description of the technology of strengthening treatment, characteristics of the material after strengthening (properties of the surface layer and of the core), operational properties after contact fatigue tests and bending fatigue tests of gear wheels or various specimens. On the basis of this data base the authors worked out a system of selecting the material and strengthening treatment for gear wheels realized on a personal computer IBM PC~AT. Operational reliability and the life of machines depend on the properties of the parts, assemblies, and detachable and permanent joints, which in their turn are connected with the structural strength of the materials. Structural strength is the totality of mechanical characteristics being in the closest correlation with the service properties of the given product and characterizing the serviceability of the material under the operational conditions. Static and dynamic strength, resistance to brittle failure, fracture toughness, fatigue limit, seizing and wear resistance, and also many other properties of materials are decisive for the reliability and life of machines. A characteristic trait of modern engineering is the stringent demands on the structural strength of steel, which is the basic material of machine parts. It is rare that materials without strengthening satisfy such stringent demands; the technology of strengthening treatment belongs to the most important stages in the production of machine parts. Correct choice of material and strengthening technology for a certain machine part is an important problem that the designer has to solve jointly with the metal scientist and the technologist. In the present work, we attempt to devise an automated system for selecting the material and strengthening technology for medium-sized gear wheels of which more than 80 million are produced annually in Russia. The selection of the steel and of the methods of strengthening it is determined by the level of the required structural strength, the technological suitability, machining, heat treatment and thermochemical treatment, the output, and the cost of" material and of processing it.