The production of ZHY casting steel castings adopts the chilled furan resin quartz sand process, and the chilled furan resin quartz sand is also used as the molding material for cf8c stainless steel valves. The sand mold coating is made of zircon powder alcohol based coating for two times, and then brushed with magnesia powder alcohol based coating for two times. The stripping property of pure zircon powder coating or magnesia powder coating is not good. The double-layer composite coating of two kinds of coatings makes it difficult for liquid steel to erode the sand mold, and the coating layer is easy to peel, which can effectively prevent sand sticking and casting defects.
A riser is set at the nozzle of the valve casting, and a feeding channel is set along the nozzle under the riser, which is conducive to feeding at the nozzle and improve the feeding efficiency of the riser; A riser is set at the intersection of each pipe above the valve casting, so that the main body of the valve casting can be fully fed to form a dense structure, and the slag collection effect is remarkable; Indirect external cooling iron is applied at the thick part at the intersection of each pipe of the valve casting and below the pipe body. The sand separation layer adopts 30 ~ 50mm thick chromite sand to form the feeding end, increase the effective feeding distance of the riser, realize the sequential solidification of the valve casting, and reduce the shrinkage cavity, shrinkage porosity and crack casting defects of the valve casting during solidification and cooling.
Indirect external cooling iron is not in direct contact with the casting surface. Reasonable application can improve the casting surface quality. Concession materials shall be reasonably placed inside the sand core, and the sand consumption shall be controlled at 80 ~ 100 mm, which can effectively prevent crack defects of valve castings.