Gearbox synchronizer ring with optimized friction characteristics, having flat-topped axial teeth and produced from iron-based powder mixture by cold compacting and sintering

摘要

Production of a synchronizer ring, from a powder mixture of (a) at least two of iron, alloying element and ferrous alloy powders, (b) iron alloy powder containing carburigenic alloying elements and (c) graphite powder, involves cold compacting the mixture in a mold to give an internal conical bore with axial teeth having tips with flat surfaces and consolidating the product by sintering at less than 1150[deg]C. Production of a synchronizer ring comprises: (a) forming a homogeneous mixture comprising (a) at least two of (i) iron powder, (ii) powdered alloying elements selected from copper, nickel and molybdenum and (iii) powdered alloys of iron with nickel and/or molybdenum, (b) particles of ferrous alloy powder containing carburigenic alloying elements at 1-10 wt. % and (c) graphite powder at an amount of less than 1 wt. %; (b) cold compacting the powder mixture in a mold to give an internal conical bore (14) with axial teeth (16) having tips with flat surfaces (17) of width less than 0.2 mm; and (c) consolidating the product by sintering at less than 1150[deg]C. An independent claim is included for a synchronizer ring, formed by sintering at less than 1150[deg]C, comprising an internal conical bore with axial teeth as above, comprising a steel matrix containing copper, nickel and/or molybdenum and carbon-enriched ferrous alloy zones, cohering with the matrix, in an amount of 1-10 vol. %.