The biggest problem during pump valve casting producing is the casting shrinkage, therefore we need to change in the process of machining on the casting the location of the internal sprue, the structure of the pump valve casting and hot section area to the formation of thick, implements the rapid solidification, the internal and external chiller, local big zircon sand, using heat storage chromite sand or special coatings.
The pump valve casting adopts its reasonable process design.The inner gate is located in the relatively thin wall of the casting, so that the metal liquid that enters the thick wall first solidifies and then solidifies after the thin wall, so that the equilibrium solidifies basically everywhere.For castings with uniform wall thickness, a plurality of inner sprays and vents are used.There are many sprays, scattered and evenly distributed, so as to balance the overall heat.The air hole is thin and much, that is, the exhaust ventilation and the cooling effect.
Quality requirements of pump valve casting
1. The chemical composition and mechanical properties of the main material of the pump valve meet the requirements of relevant material standards.
2. The deviation of the shape and size of the pump valve is in accordance with the requirements of the drawing.
3. The non-machined surface of the pump valve should be flat, smooth, without sand, no oxide, no porosity, no sand, no cracks and so on.The casting mark is clear, the gate and the riser should be flush with the casting surface.
4. All parts of the pump valve shall be connected firmly and without looseness.
5. The pressure test and sealing performance test of the pump valve meet the requirements of the test standards.
6. Have a large circulation capacity.
The role of chiller in pump valve casting.
The basic function of chiller is to chill the casting of the pump valve, to use the chilling effect of chiller, to adjust the casting part or the whole solidification process.Specific functions:
1. Improve the hardness and wear resistance of castings.
2. Control the casting's directional solidification or simultaneous solidification.
3. Eliminate the casting local hot section.
4. Prevent casting from cracking.
5. Reduce the number of outlets.
6. Reduce the size of the riser.http://www.dmgcastings.com/