Orendarchuk Y. Scientific methods of computer-integrated design of technologies for the manufacture of internal combustion piston castings

The dissertation solved the scientific and practical problem of substantiation and creation of technology of computer-integrated design (CID) of pistons of diesel engines with complex application of modeling of thermal, hydrodynamic parameters of casting and taking into account influence of technological parameters of casting on sizes of gas-shrinkage defects. Solving this problem makes it possible to raise the technical level, and reduce design time, as well as reduce costs for engine production. The result of the study was the creation of a three-dimensional model of the casting with elements of the foundry-feeding system applied to it. According to the results of creating a 3D model of the piston casting D 240-1004021 was found that the three-dimensional image of a complex designed part, greatly facilitated the perception and simplified the process of developing foundry technology. This is due to the fact that you can clearly see the design features, thermal units, etc., with the reduction of the dimensional coefficient of castings became more technological; the correct choice of the position of the casting in the form and connector of the mold allowed to improve the quality of castings and reduce the complexity of their manufacture. A also increase the stability of the molds; in the process of casting pistons, it is advisable to use side systems with slot feeders. Also, bring from below through ring feeders that provides smooth filling of a cavity of the form; Pre-existing casting systems work inefficiently because the constructive location of the traditional casting system relative to the casting prevents the creation of directional crystallization in the casting. The improved gutter system ensured smooth flow and filling sequence due to smoother transitions from one element to another and the absence of a structural element "collector". It is proved that the upper systems provide the highest stability of the molds. In addition, such systems are very economical. However, such systems are not inferior to the lower (siphon) in terms of reduction in castings of non-metallic inclusions. It is emphasized that the three-dimensional model of the casting with the elements of the foundry-feeding system applied to it will be used in the future to model the processes that take place in the foundry form during its pouring and cooling of the metal. It is established that an integral part of the system approach to computer-integrated design technology is the method of determining the location and size of defects in the cast piston of the engine with fuel ignition from compression. To develop this method was determined that the most effective method direct modeling of the process of pore formation during curing based on the use of Darcy's equation, however, the necessary mathematical models are not accurate enough and need to be improved. It was found that the formation of gas-shrinkage defects corresponds to the model based on the theory of percolation; initial and boundary conditions for modeling are defined. The Niyama criterion, which shows the direction of crystallization, was used to determine the location of gas-shrinkage defects. Analysis of the results of modeling the location of defects showed that the most prone to shrinkage are arrays of bosses under the finger hole; the bottom of the piston under the combustion chamber, the transition area from the piston body to the bottom. For the purpose of specification of the sizes and places of formation of gas-shrinkage defects in the conditions of production for experimental batch of pistons D 240-1004021 allowed establishing the location and size of gas-shrinkage defects (Ø 0.3-1.3 mm) experimental studies of the functionality and resource determination of pistons D 240-1004021 were also performed. To assess the impact of technological factors of casting on the size of gas-shrinkage defects in their locations, a numerical experiment was developed and implemented using the results of modeling in LVMFlow. Studies have shown that the most interesting when studying the process of directional curing are the thickness of the layer of refractory coating, the thermal conductivity of the coating, the wall thickness of the mold and the initial temperature of the mold.