Mold filling differential pressure determining method based on vacuum differential pressure casting classified pressurizing mold filling

Abstract

The invention discloses a mold filling differential pressure determining method based on vacuum differential pressure casting classified pressurizing mold filling. Under the condition that it is guaranteed that the inner mold filling flow state of a liquid ascending pipe is laminar flow, the mold filling pressure and the mold filling speed of liquid metal in the liquid ascending pipe are determined, and the classified pressurizing mold filling differential pressure needed at the position of a classified mold filling section is calculated in combination with the shape, the height, the wall thickness and the complex degree at the position of a casting mold filling section according to the principles of energy conservation, mass conservation and continuity. The mold filling differential pressure determining method has the advantages that a good mold filling flow state in the liquid ascending pipe can be guaranteed, the classified pressurizing mold filling differential pressure is determined according to the mold filling section feature, and accordingly, the stability of the mold filling flow state at the position of the mold filling section can be obviously improved. The vacuum differential pressure casting classified pressurizing mold filling differential pressure can be scientifically determined, and important significance is achieved for achieving stability and the sequence ofthe flow state in the mold filling process and reducing oxidization slag inclusions, gas wrapping and other casting defects happening to castings.

Description

technical field [0001] The invention relates to the technical field of special casting, in particular to a method for determining the filling pressure difference based on vacuum differential pressure casting with staged pressure filling. Background technique [0002] Vacuum differential pressure casting has been widely used in the production of thin-walled castings, and researchers at home and abroad have conducted extensive research on its filling process. As early as the 1980s, foreign Campbell J and Weng-sing Hwang et al. The filling flow state of thin-walled castings was studied, and the theory of unsteady vertical immersion restricted jet was proposed. Determined by the ratio of the width of the slab. Since 1989, under the leadership of academician Zhou Yaohe, Northwestern Polytechnical University has conducted a lot of research on vacuum differential pressure casting. The mold filling flow form of casting has been studied, and it is considered that the mold filling o...

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Problems solved by technology

However, this research is based on the case that the filling pressure difference is fixed. At this time, it is of good scientific guiding significance to use the gas flow rate to determine the filling pressure difference, but the filling pressure difference of the staged pressurization filling is According to the change of the casting structure, when the filling pressure difference changes, due to the compressible characteristics of the gas, the volume will change significantly under different pressure conditions, and the step-by-step pressurization filling is to control the filling by controlling the gas pressure Pressure difference, the pressure change will obviously affect the volume of the gas, therefore, under the condition of staged pressurization filling, using the gas flow rate to determine the filling pressure difference will produce a certain error, and the filling of the staged pressurization filling There is no relevant report on the research on the method of determining the pressure difference

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