As the requirements for the engine’s power, economy, environmental protection and reliability become more and more strict, the piston has developed into a collection of lightweight high-strength new materials, shaped outer cylindrical composite profiles, shaped pin holes, etc. The high-tech products of the new technology ensure the heat resistance, wear resistance, smooth guiding and good sealing function of the piston, reduce the friction energy loss of the engine and 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 profiled outer circle (medium convex ellipse), that is, the cross section perpendicular to the axis of the piston is an ellipse or a modified ellipse, and the ellipticity changes according to a certain law along the axis direction. (As shown in Figure 1), the ellipticity accuracy is 0.005mm; the outer contour of the longitudinal section of the piston is a fitting curve of the high-order function, and the contour accuracy is 0.005~0.01mm; in order to improve the load carrying capacity of the piston, the engine is raised. Power, usually the pin hole of the high-load piston is designed as a micro-inner cone or a positive-stress curved surface (shaped pin hole), the pin hole size accuracy is up to IT4, and the contour accuracy is 0.003mm.
As a typical key component of a car, the piston has strong process characteristics in terms of machining. The domestic piston manufacturing industry usually consists of a general-purpose machine tool and a special equipment that combines the characteristics of the piston process. Therefore, the special equipment becomes the key equipment for piston cutting. Its function and precision will directly affect the quality index of the key characteristics of the final product.