Self-lubricating plunger, bushing for self-lubricating plunger and method for manufacturing same

A method for manufacturing a bushing of a self-lubricating plunger, comprising:

• S1. uniformly mixing a base metal powder of 100-1000 meshes with a reinforcing metal powder of 100-1000 meshes to obtain a mixture, putting the mixture into a mold for pressing by a hydraulic press machine to form a blank, then putting the blank into a high-temperature furnace for high-temperature sintering to form a tubular metal foundation, wherein, the tubular metal foundation has a plurality of micropores;
• S2. melting a metal matrix lubricant by heating up, wherein the metal matrix lubricant comprises a metal substance of low melting point and a basic lubricating powder dispersed in the metal substance of low melting point, and the metal substance of low melting point has a melting point higher than a storage temperature of the bushing and lower than a working temperature of the plunger, the working temperature of the plunger ranges 185° C.-210° C., the melting point of the metal substance of low melting point is 80° C.-170° C.;
• wherein the metal substance of low melting point is one substance or a mixture of more than one substance selected from a group consisting of cesium, indium, bismuth, lead, cadmium, tin, dysprosium, gallium alloy, bismuth-based alloy, lead-based alloy, lead-tin-antimony copper;
• the metal substance of low melting point accounts for 80-97 wt % of a total weight of the metal matrix lubricant;
• and
• S3. immersing the tubular metal foundation in the molten metal matrix lubricant to fill the micropores of the tubular metal foundation with the metal matrix lubricant, then cooling down the temperature.