Precoated sand casting process of cast steel valve

Abstract

The invention relates to a precoated sand casting process of a cast steel valve. The process specifically comprises the following steps of firstly preparing a sand shell by using precoated sand as a raw material, baking the sand shell, pouring molten steel into the sand shell, taking down a to-be-cast valve after the to-be-cast valve is naturally cooled, solidified and formed, and obtaining a valve casting; and finally carrying out shot blasting, riser cutting, heat treatment, secondary shot blasting and finishing on the valve casting to obtain a valve blank, specifically, the method for manufacturing the sand shell by using the precoated sand as the raw material comprises the following specific steps of preparing a half shell or a half core by using the precoated sand as the raw material;and repairing and spraying the half shell and the half core of a valve body / valve cover while hot, and assembling to obtain the sand shell, specifically, the time consumption of the repairing processof the half core of the valve body / valve cover and the repairing process of the half shell needs to controlled to be less than or equal to 120 seconds; and in the spraying process, the temperature ofthe half shell and the temperature of the half core of the valve body / valve cover are kept 60 DEG C or above. The cast steel valve produced by the process is high in pressure test qualified rate.

Description

technical field [0001] The invention belongs to the field of valve component manufacturing, and in particular relates to a coated sand casting process for cast steel valves. Background technique [0002] The coated sand process is initially to mechanically mix the powdery thermosetting phenolic resin with the original sand, and solidify when heated. A certain coating process is formulated into coated sand. When the coated sand is heated, the resin coated on the surface of the sand grains melts. Under the action of methylene decomposed from urotropine, the molten resin rapidly changes from a linear structure to The non-melting body structure allows the coated sand to solidify and form. [0003] At present, the production of cast steel valves mainly adopts the water glass shell process or the silica sol composite process and the investment casting method. However, various methods have the disadvantages of low efficiency, complex production process, long delivery cycle, large...

AI Technical Summary

Problems solved by technology

The shell produced by the production process of coated sand casting valve can be directly cast, which has the advantages of short delivery period, high production efficiency, less labor, simple process, single material use, and low noise on the production site, so it has little pollution to the environment, but Due to technical reasons, cast steel valves made of coated sand have not been widely used due to the high scrap rate

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