轿车变速器的粉末冶金齿轮

P/M gear for a passenger car gear box

粉末冶金齿轮由于材料中残留有孔隙,和用切削加工铸锻材料制造的零件相比,强度与耐磨性较差,不适用于重负载应用。通过横向辗压,利用选择性表面致密化,可显著改进粉末冶金齿轮的强度与耐磨性。这篇论文阐述了用压制、烧结、选择性表面致密化、表面硬化及根据要求的品质水平可能还有最后珩磨,制造轿车变速器的粉末冶金螺旋齿轮。研究了各种参数,诸如材料组成、横向辗压与热处理的工艺参数对致密化与硬度深度、孔隙形态、显微组织、齿轮齿廓、DIN品质以及表面粗糙度的影响。初步研究是在3轴的总成成对试验台架上进行的,其表明粉末冶金齿轮具有高负载承载能力。

Powder Metallurgy （P/M） gears with residual porosity have lower strength and wear resistance when compared to wrought and machined gears and hence have not been employed in heavy-duty applications. Substantial improvements in strength and wear resistance of P/M gears are achieved by selective surface densification through transverse rolling. This paper deals with the manufacturing of a helical P/M gear for a passenger car gear box by compaction, sintering, selective surface densification, case hardening and possibly final honing depending on the required quality level. The influence of various parameters such as material composition, transverse rolling and heat treatment process parameters on the densification and hardness depth, pore morphology, mierostructure, gear geometry, DIN-quality and surface roughness have been studied. Preliminary investigations have been carried out on a 3-shaft back to back testrig which indicate that the P/M gears have a high load bearing capacity.