There are many problems to be solved in the valve casting process, and relevant personnel should focus on the following design.
One is the shrinkage of valve castings. Valve castings may shrink in application. Relevant personnel shall control the shrinkage within a certain range so that it will not affect the function of valve castings. Based on this, the shrinkage of valve castings shall be determined. When determining this parameter, we should also consider the material, valve casting structure and other factors. The final internal and external cavity scale parameters are 2% and 1.50% respectively.
Second, parting surface. Effectively select the parting surface to solve the problem of simultaneous feeding and shrinkage of annular pipeline. Take the parting surface as the collection position of all pipeline centerline. In the design, relevant personnel need to find the pipeline center, and the collection position of central extension line is the parting surface. Under the action of parting surface, the integral valve casting will be divided into two parts evenly. This plane has the largest cross-sectional area. Relevant personnel should also check the collection position of the axial centerline to see if there is only one plane. In valve casting, relevant personnel should control the use of sand core, which can avoid the occurrence of drape joint.
The third is the gating system. The pouring method is bottom pouring type, and the relevant system design shall also meet the requirements of bottom pouring type. It mainly designs the sprue and gate. In terms of sprue, it is necessary to ensure its corrosion resistance and stability, so that it can safely bear the impact of liquid metal and avoid various defects. The runner also plays the role of blocking metal slag. In the design, it should be avoided to block the gas discharge of the cavity. In order to ensure the filling effect of the gating system, it is also necessary to solve the influence of metal chromium, mainly to improve the cold shut and wrinkle phenomenon. Also deal with the oxide film produced by chromium. In addition, the pouring time, the mass flow rate of liquid steel and the diameter of wrapped hole should be designed and controlled to meet the quality requirements of steel castings. Among these parameters, the diameter of cladding hole and the mass flow rate of molten steel will affect each other. Relevant personnel will analyze the relationship between them through data and summarizing the law in several experiments. Finally, the cross-sectional area of components should be accurately calculated to make the size of valve casting gating system meet the requirements.