With the increasingly strict requirements for the power, economy, environmental protection and reliability of the engine for the whole automobile, the piston has developed into a high-tech product integrating a number of new technologies, such as light and high-strength new materials, special-shaped cylindrical composite surfaces, special-shaped pin holes, etc., to ensure the heat resistance, wear resistance, stable guidance and good sealing function of the piston, reduce the loss of friction work of the engine, reduce fuel consumption Noise and emissions. In order to meet the above functional requirements, the outer circle of the piston is usually designed as a special-shaped outer circle (convex to elliptical), that is, the cross section perpendicular to the piston axis is an ellipse or a modified ellipse, and the ovality changes along the axis direction according to a certain rule (as shown in Figure 1), and the ovality accuracy reaches 0.005mm; The outer contour of the piston longitudinal profile is the fitting curve of a higher order function, and the contour accuracy is 0.005-0.01mm; In order to improve the bearing capacity of the piston and increase the power of the engine, the pin hole of the high load piston is usually designed as a micro inner cone or a normal stress curved surface (special-shaped pin hole). The dimensional accuracy of the pin hole reaches IT4, and the contour accuracy is 0.003mm

Piston, as a typical key component of automobile, has strong technological characteristics in machining. In the domestic piston manufacturing industry, the machining production line is usually composed of general machine tools and special equipment combined with piston process characteristics. Therefore, special equipment has become the key equipment for piston cutting, and its function and accuracy will directly affect the quality index of the key characteristics of the final product.