Research On Surface Fit Of Piston Former And Processing Methods

Based on the actual needs of engineering application, the paper conducts analysis, summarization and study upon the key technical points relating to profile characters of piston and piston former, fitting methods, profile machining methods and the designing of special machining tool sets etc. The paper demonstrates a simplified implementation plan concerning the fitting and machining of piston former profiles.According to the profile characters of piston former, the paper confirms the workflow of the profile fitting of piston former.It establishes a mathematical model as for the fitting of piston former, the numerical value calculation and analysis indicate that as for the cross section of piston former with smaller ellipse degree and ultimately approximate to rotundity, if properly choose eccentricity and eccentric circular arc, and then the cross ellipse profile of piston former could adopt four eccentric circular arcs to fit. As for the piston former whose longitudinal section is curve profiles of discrete points, if properly choose fit curve and use tangents of fit curve on all discrete points to replace the fit curve. Through technical process of the two modes, without special-type machining equipment, it could solve the difficulty to machine convex ellipse profiles of piston formers, and provide the feasibility for fully utilizing existing machining equipments to machine the convex profiles of piston formers on general precision plane grinding machines, under the conditions that there is no need for us to introduce expensive special-type machining equipment; in this way it not only reduces production costs, but also ensures production quality of piston formers. It conducts analysis and summarization on the designing and manufacturing plan of special eccentric shafts and special sine tool sets during the machining of convex ellipse profiles of piston formers.It designs and makes piston formers for testing, and the testing results indicate that the simplified plan on the designing and making of piston former profiles in the paper is feasible.