Casting process for piston shell

Abstract

The invention discloses a casting process for a piston shell. The process is as follows: an upper inner core and a lower inner core of the piston shell are fabricated at first and then are combined together to form an integral core that is put into a piston shell mold later, which enables the success rate of product casting to be improved; raw materials added during melting comprise, by weight, 34% of pig iron, 26% of steel scrap, 33% of returns, 1.4% of ferromanganese, 0.8% of ferromolybdenum, 0.5% of copper, 0.6% of ferrovanadium, 1.5% of ferrochrome and 0.8% of ferronickel; a silicon calcium barium inoculant is added at the front of a furnace for multiple inoculation. A separately cast test bar obtained after pouring has a tensile strength under a cast condition of more than 380 MPa and a hardness of 255 to 270 HB, a graphite grade is grade 5 and pearlite reaches over 97%; thus, the test bar totally meets requirements by customers, has good processing performance, needs no heat treatment, enables production cost to be reduced and effectively prolongs the service life of the piston shell.

Description

technical field [0001] The invention relates to a casting process, in particular to a casting process of a piston housing. Background technique [0002] The existing piston housings used on trains have heavy weight and high product density, and the casting process also has the following disadvantages: [0003] 1) In the casting process, the castings must undergo stress relief annealing treatment after pouring. The production cycle is long and the cost is high. Moreover, the mechanical properties of the gray cast iron (HT350) after heat treatment are very unstable, and it is difficult to meet the technical requirements of HT350, and often need to be adjusted by heat treatment again It can only meet the requirements, which not only wastes resources and time, but also increases the casting cost of the piston housing; [0004] 2) Since the inner core cavity of the piston housing is integrally cast, the scrap rate is high in the existing casting process. Contents of the invent...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the problems of heavy weight, high product density, waste of resources and time, high cost, and high scrap rate in the existing piston housings used on trains in the prior art. Difficulty, improve the rate of finished products, use the cast production method without heat treatment, reduce production costs, and effectively increase the service life of the piston housing

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