Pistons designing and production

Designing

Since 2000 “AVTRAMAT” Joint stock Company has created the end-to-end designing system, the essence of which is that the process of manufacturing the product is directly connected with the construction. The designing of construction is brought about simultaneously with designing of technology. This approach has sufficiently reduced the number of iterations in the process of manufacturing. Since piston is basic product of the enterprise, the system is arranged to ensure maximum efficiency in designing and producing pistons. The main objective is to reduce the losses of friction in the piston-cylinder-unit; it can be achieved at the cost of reduction of inertia masses and optimization of technology. Meanwhile, the loss of functionality and resource is inadmissible. Another important objective is the reduction of production costs; this issues the challenge of technology optimization. Thereby the designing system is divided into the following stages:

- analysis of prototypes;

- geometric 3D modeling;

- numerical modeling of the system of thermal and force action on the basis of boundary conditions of a prototype’s operation and models of this action;

- minimizing the mass under the criterion “not worse than the prototype”;

- calculation of the external shape of a piston;

- 3D modeling of a workpiece (cast) and gear for its production;

- 3D modeling of critical operations that can emerge in the course of production;

- optimizing the technology of bases and processing.

The crucial part of the developed technology of piston designing is protected by the patents of Ukraine (UA 66120) and Russian Federation (RU 2 256 897 C1).

Production

The process of piston production includes receiving a workpiece, thermal treatment, mechanical treatment, coating.

The enterprise applies the method of chill casting – gravitational or under low pressure. The type of chill casting is determined by such factors as output program, piston size, material, requirements to mechanical properties of the product. Most of automobile and light industrial pistons are produced by using the gravitational method. It gives possibility to produce more mouldings in one casting gear. 

The inner surface of the piston is shaped by the pivot, which can be whole (mono-wedge) or consist of 3-7 parts (wedges). The external surface of the piston is shaped by the matrix formed by several parts (usually two). Sometimes a pivot forming the bottom and the camera may be used. The agglomerate components form the casting form – the chill. 

The flexibility of the form enables the manufacturer to make changes in the construction of the parts being casted, and introduce the casting of other parts such as Ni-resistible blocks and breakable pivots. Finished pistons possess good mechanical properties and constant dimensions. The pistons produced by the method of low pressure casting are more solid than that produced by the method of gravitational casting. This method is used for production of little thin-walled pistons, for instance, compressors or for other use. The metal is supplied to the casting form with the help of vacuum or pressure of melted metal column; this ensures good spillability of little constructional elements.   

Casting machines, chills and gear are designed and produced in “AVTRAMAR” Joint-stock company. This gives possibility to master the manufacturing of a new product in minimal terms. Complex shape-generating surfaces of the casting gear are processed at PNC-equipped tools (PNC – programmed numerical control). 

After the casting and crystallization, the material of a workpiece does not possess enough toughness, firmness and stability at high temperatures. For improving the structure of the material and imparting necessary mechanical properties, the workpiece undergoes thermal treatment. After thermal treatment pistons undergo mechanical treatment to achieve specified parameters and various additional properties.