Novel casting method of steam turbine combined steam valve shell steel casting

Abstract

The invention provides a novel casting method of a steam turbine combined steam valve shell steel casting. The outer contour of the steam turbine combined steam valve shell steel casting is formed bya lower casting mold, a first middle casting mold, a second middle casting mold and an upper casting mold, and three parting surfaces are designed from the bottom to the top of the casting molds, namely, the large-diameter end surface of a conical main body serves as a first parting surface, the horizontal plane passing through the diameter of an opening of a bent pipe serves as a second parting surface, and the horizontal plane passing through the diameter of an opening of a straight pipe serves as a third parting surface; and a bottom pouring system is adopted for mold filling of the castingmolds to form the steam turbine combined steam valve shell steel casting, and pouring from the large opening end to the small opening end of the steam turbine combined steam valve shell steel castingis achieved. The large opening end of the steam turbine combined steam valve shell steel casting faces downwards, and the small opening end of the steam turbine combined steam valve shell steel casting faces upwards, so that a sand core is accurate in positioning, low in gravity center without skew and accurate in size, hot spots are prevented from being generated at the small opening end, the bent pipe is continuously and stably filled with molten steel along with rising of the molten steel in the casting process, the molten steel falling phenomenon is avoided, the slag inclusion rate of thesteam turbine combined steam valve shell steel casting is reduced, and the quality of the finished steam turbine combined steam valve shell steel casting is ensured.

Description

technical field [0001] The invention relates to the technical field of casting, in particular to a novel casting method for a steel casting of a combined steam valve housing of a steam turbine. Background technique [0002] The steam turbine steel casting combined with the steam valve housing is an important part of the steam turbine. It is responsible for the entry and exit of high-pressure and high-temperature steam. It has been in a high-temperature and high-pressure working environment for a long time. Therefore, the internal quality requirements of each part of the product are extremely high, and it needs to pass the ray RT flaw detection requirements. The valve casing of the combined steam valve is in the shape of a large top and a small tapered bottom, and is connected with the straight pipe at a certain angle. The product structure is complex. For specific product structure, see figure 1 . The traditional casting method is that the small mouth end faces down, the bi...

AI Technical Summary

Problems solved by technology

[0008] In order to solve the technical problems existing in the prior art, the present invention provides a new casting method for steam turbine combined steam valve casing steel castings, which changes the casting modeling method in the traditional casting method, and puts the large mouth end of the casting downwards and the small mouth end upwards. Placement, the pouring system is set at the bottom of the large mouth end, and the molten steel is poured steadily upward from the large mouth end of the casting during pouring, which effectively solves the difficulty in dimension positioning of valve casing castings, poor feeding efficiency, easy sintering of inner cavity sand and difficulty in sintering, and hidden leakage of inner cavity In addition, according to the new casting method, the present invention also provides a new casting method for steam turbine combined steam valve casing steel castings.

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