Vacuum expendable pattern casting (V-EPC) molding method of large complex castings

Abstract

The invention discloses a vacuum expendable pattern casting (V-EPC) molding method of large complex castings. A flask for molding comprises three parts including flask bottom, a flask body and an up draught pneumatic hoist press bar; each part is provided with an independent vacuum air duct. The molding procedures comprise the following steps: filling sand and carrying out vibrating molding on the bottom of the expendable pattern, turning over the flask, removing a supporting plate and a tire plate rack and placing the up draught pneumatic hoist press bar, filling the sand, exerting pressure for vibrating molding, sealing the flask and carrying out pouring after vacuumizing. The parts with blind holes and grooves are filled with resin sand and core irons and a floating crane is employed to fix the core irons; local compaction is carried out on loose parts. Being adopted, the method of the invention ensures compact and uniform molding sand, solves the difficult problems frequently appearing in the process of V-EPC of large castings, including sand crushing, sand drop, sand inclusion and deformation, can ensure the accuracy of the blind holes, deep grooves and entire castings, can enable the pattern to be almost free from floating and deformation in the process of vibration and can produce high quality large complex castings.

Description

technical field [0001] The invention relates to a casting method, in particular to a molding method for casting large and complex castings by using vacuum lost foam. Background technique [0002] Vacuum lost foam casting technology is a new type of casting technology developed in recent decades. The process of vacuum lost foam casting includes foam forming-assembly model bundle-painting-drying-embedding box, vibration molding-vacuumizing-casting under negative pressure (foam type vaporization)-casting solidification cooling-sand cleaning. Vacuum lost foam casting belongs to solid casting. Its model is generally formed by foam, and the shape of the model is the same as that of the casting. After the pretreatment of the model assembly is completed, place it on the sand in the sand box, and then fill the box with dry molding sand. After the sand fills the sand box, use a vibrating machine to vibrate the sand and fill the sand to the top of the model. Every corner, and then co...

AI Technical Summary

Problems solved by technology

However, the casting sand box with this structure is only suitable for small castings. For large castings, such as molds for stamping automobile bodies, their shapes are complex, with many blind holes and grooves, and their weight often reaches several tons, ten tons or even twenty tons, so it is far from enough to take this kind of measure

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