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Measures to Prevent Pinching in Valve Body Casting and Produce Stoma during Casting Process
- Jun 15, 2018 -

In order to further improve the quality of cut-off valve body castings and reduce the occurrence of undesirable phenomena such as blowholes, it is generally required to take corresponding measures in the smelting and pouring processes. In the smelting process of the cut-off valve body casting, in order to effectively reduce the occurrence of blowholes, we need to control the quality of raw materials and smelting process in this stage.

 

For the cut-off valve body castings, the selected raw materials should be kept dry, not wet, scrap steel, pig iron without rust, can not be mixed with other inclusions. At the same time, in the control of the smelting process, the smelting temperature should be controlled within an appropriate range, and iron should be allowed to stand for at least 15 minutes after being completely melted so that slag in the molten iron can be precipitated and floated.

 

At the same time, strict control is required in the pouring step. In general, during the pouring process, the pouring temperature needs to be strictly controlled. When casting the closing valve body casting, the pouring temperature should be controlled between 1330 and 1390°C. It is understood that when a package of molten iron is poured into the back, the molten iron has poor fluidity when the temperature is lower than 1320°C, and the molten iron cannot even flow out of the riser when pouring. In this case, the porosity of the casting increases significantly.

 

In order to solve this problem, the pouring temperature can be appropriately increased during the pouring process. In other words, the casting of the shutoff valve body can be poured first according to the temperature in the casting, which can also reduce the generation of the blowhole of the casting. At the same time, the degree of dryness of the ladle is also very important, and iron ladle that is not dried is not used. For example, some qualified manufacturers require that the use of molten iron must be over-wrapped before using the ladle, which would be better.

 

In short, in the casting process, regardless of whether the sand core has a large amount of gas, bad drying, or unsatisfactory exhaust capacity, unreasonable process design, poor quality of hot metal, low pouring temperature, etc. The main factor of stomata. Therefore, in the process of casting valve body castings, these factors should be improved, focusing on the process, paying attention to details, and effectively reducing porosity.

 

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