METHOD FOR ELECTRIC-CONTACT HEAT TREATMENT OF PART SURFACES Russian patent published in 2000 - IPC

FIELD: machine engineering industry branches, namely, heat treatment, possibly case hardening of working faces of parts. SUBSTANCE: method for electric-contact heat treatment of surfaces of parts from ferrum-carbon alloys comprises steps of passing electric current through contact members forced by pressure to treated surface; at treating curvilinear portions of wheels of cars of rolling stock successively placing contact members in such a way that they are shifted one from to another by angle 70-110 degrees relative to line being tangent to generatrix of hardened surface for heat treating portions in the form of stripes; providing ratio of radius values of curvilinear surface and profile of contact member in range 1: (0.8-0.98) when curvilinear surface is concave and in range 1:(1.08-1.17) when curvilinear surface is convex. Mutually shifted contact members may be placed with overlapping for providing annealing zone of hardened strip provided by first contact member. Stripes may be intermittent and they may be arranged in staggered fashion. EFFECT: reduced inner stresses of part, increased wear resistance of heat treated surface. 4 cl, 1 dwg, 3 ex