Combined wax pattern-based method of achieving precision investment casting for heat-resistant cast steel thin-wall turbine shell

Abstract

The invention discloses a combined wax pattern-based method of achieving precision investment casting for a heat-resistant cast steel thin-wall turbine shell, and belongs to the technical field of casting. In the method, the turbine shell is made of a heat-resistant cast steel material, a wax pattern of the turbine shell is three-dimensionally printed by adopting low-temperature wax, a riser wax pattern is poured by adopting medium-temperature wax through melt extrusion moulding, the combined wax pattern is formed by reliably bonding the wax pattern of the turbine shell with the riser wax pattern by bonding wax; an investment casting technical process based on the combined wax pattern comprises the following steps: preparing wax patterns, combining the wax patterns, producing a shell, carrying out investment wax removal, roasting a pattern shell, melting an alloy, pouring, compacting the shell, blasting shots, cleaning the shell, and the like. The method disclosed by the invention can be used for effectively increasing the wax pattern moulding efficiency of the turbine shell, reducing the cost, ensuring the casting accuracy of a runner of the turbine shell, improving the mould-filling capacity of heat-resistant cast steel, and achieving the thin-wall casting of the turbine shell; the wall thickness can be reduced to 3mm, and thus a light-weight purpose is achieved and the needs of an aircraft engine supercharger are met.

Description

technical field [0001] The invention relates to the technical field of turbocharging of aviation piston engines, in particular to a heat-resistant cast steel thin-walled turbine casing investment casting process based on a combined wax pattern for turbochargers, which is also applicable to automotive turbochargers. Especially in the field of car turbocharger technology. Background technique [0002] The turbocharger is installed on the exhaust pipe of the engine, and the turbine casing is directly connected to the exhaust pipe. It is under high temperature and high pressure working conditions, especially in aviation piston engines and passenger car gasoline engines, where the exhaust temperature is as high as 950 °C ~1050°C, which is much higher than the maximum exhaust temperature of a diesel engine at 850°C. The commonly used silicon-molybdenum ductile iron turbine casing can no longer meet its performance requirements, while austenitic heat-resistant cast steel has good h...

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Problems solved by technology

[0003] However, due to factors such as the poor fluidity of austenitic heat-resistant cast steel, high pouring temperature, easy gas absorption, oxidation and sand sticking, and the special and complex structure of the turbine shell, the application of austenitic heat-resistant cast steel in the turbine shell is relatively large. The difficulty of the process, the applicability of special casting methods such as metal mold casting, pressure casting and sand casting are poor, and the wall of the cast turbine volute is too thick, generally about 5mm, which is difficult to meet the requirements of light weight and low thermal inertia of aviation gasoline engines; At the same time, thin-walled complex structural parts are not easy to cast and form, and are prone to defects such as under-casting, cold shut, and under-casting

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