柱塞泵反包柱塞收口的设计与制造

Design and Manufacture of Reverse Piston Necking of Piston Pumps

反包柱塞比正包柱塞具有结构简单、体积小和寿命长等优点,对反包柱塞进行了结构设计和材料选择。为解决反包柱塞在收口处出现裂纹的问题,对柱塞颈部进行了金相、电子能谱分析和硬度分析。结果表明颈部防渗剂防渗效果不好,热处理造成颈部硬度增加明显,塑性下降,是裂纹产生的主要原因。针对问题产生的原因,采取了气体渗氮前颈部预留机加工余量和先收口再进行热处理的工艺措施,使颈部硬度符合设计要求,解决了柱塞颈部裂纹的问题,保证了压合后的质量,为实际生产提供了准确的工艺方法。

Reverse piston was simpler in structure, smaller volume and longer life than original＇s, which structure was designed and material was selected. To solve the problem of the cracks appeared in the necking, the metallographic, EDX and hardness of necking were analyzed. The results showed that the mainly reasons to cracks were anti-seepage agents ineffective, causing neck＇s hardness significantly increased, plasticity decreased. The process measures of reservation machining allowance before gas nitriding and the piston necking-in before heat treatment were taken. The hardness of neck met the design requirements and solved the problem of the piston neck cracks. The quality of the pressing was ensured, and the accurate process method was provided for the practical production.