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How to set up the riser of the valve casting and how to test the hardness

Jun 06, 2018

During the process of manufacturing the pump valve castings, the riser should be effectively set on the top or side of the hot section of the casting, and should not be set on the part where the casting is subjected to force, so that it can effectively prevent its coarse structure and reduce its Mechanical properties.

 The riser of the casting of the pump valve shall be set at the highest and the thickest part of the casting as much as possible. When using it, it is necessary to use a single VI to feed several hot spots at the same time. For the hot spot in the lower part or the hot spot farther from the riser on the same level, cold iron can be subsidized or chilled so as to guarantee the orderly solidification and the smoothness of the feeding channel. Under the premise of meeting the feeding effect, the feeder should be set on the processing surface as much as possible to reduce the workload of cleaning the root of the feeder and reduce energy consumption.

The position of the riser of the pump valve to a certain extent should be effectively matched with the position where the alloy fluid is introduced. It is better to place it on the inner runner during operation so that the molten metal can enter the cavity through the riser. It not only has a preheating effect on the riser, but also plays a role in blocking the slag during the filling process.

Hardness test method for pump valve castings

1. Brinell hardness: It is mainly used to determine the hardness of castings, forgings, non-ferrous metal parts, hot-rolled billets and annealed parts. The measurement range is HB450.

2. Rockwell hardness: HRA is mainly used for high-hardness test specimens, the hardness of which is higher than that of HRC67 and surface hardness, such as hard alloy, nitrided steel, etc., and the measurement range is HRA>70. HRC is mainly used for hardness measurement of steel parts (such as carbon steel, tool steel, alloy steel, etc.) after quenching or tempering. The measurement range is HRC20~67.

3. Vickers hardness: used to determine the hardness of thin and steel parts, can also be used to determine the hardness of carburizing, cyanidation, nitriding and other surface hardening parts.

To a certain extent, the pump valve casting refers to a fusible model made of a fusible material, on which a plurality of layer-specific fire-retardant paints are applied, and can effectively be dried and hardened to form a unitary type during operation. After the shell, steam or hot water is used to melt the model out of the shell. The shell is then placed in the sand box and filled with dry sand. The cast is placed in a roaster and baked at a high temperature. After the shell is fired, the molten metal is poured thereinto to obtain a casting.