Characteristics of valve manufacturing process
Each industry has its unique characteristics. Compared with the manufacturing process of other institutions, the manufacturing process of the valve industry mainly has the following three characteristics:
1. Mechanical processing is difficult
Due to the wide variety of valve materials, except for various cast iron and carbon steel, most of the high-strength, corrosion-resistant and high-hard materials have poor cutting performance, and it is difficult to make the parts reach the specified machining accuracy and surface roughness. The geometric shape accuracy and surface roughness of the valve sealing surface are very demanding, which increases the difficulty of valve machining. At the same time, the poor cutting performance of the valve material has brought many new problems to the valve processing method, tool material, cutting amount, process equipment and so on.
2. The manufacturing process and inspection process of the valve blank are more complicated
The casting blank of the valve is a thin-walled shell with a complex structure. The castings require smooth surface, clear casting, especially dense defects. In order to meet the above requirements, a series of technological measures should be taken during casting, such as selecting high refractory molding materials and controlling the water content of the molding sand, layering and compacting during molding to ensure the hardness of the sand mold, using a reasonable gate system and strict control. Pouring speed and temperature, etc. Due to the high technical requirements, the casting process of valve blanks is far more complicated than that of general castings.
In addition, in addition to checking the size, position accuracy and appearance of the valve blank, some are also used for metallographic structure, mechanical properties, corrosion resistance and non-destructive testing, etc., so the valve inspection process is also more complicated.
3. It is difficult to install valve parts on the machine tool
The structure and shape of the main parts of the valve are relatively complex, and some parts are thin-walled, slender, and have poor rigidity. When machining on a machine tool, positioning and clamping are difficult, so complex special fixtures are often required.
For some valve parts, the accuracy of the positioning base surface is low, the surface roughness is high, and sometimes even non-machined surfaces are used for positioning. However, the precision and surface roughness of the parts such as the processed sealing surface are very high, so it is difficult to ensure the processing quality. Therefore, in order to meet the needs of the process, it is often necessary to improve the accuracy of the positioning base surface and reduce the surface roughness, or process the positioning base surface on the non-machined surface, which increases the complexity of the valve manufacturing process.
The above three points are the characteristics of the valve manufacturing process. Due to the particularity of the valve, these three characteristics are particularly prominent compared to other manufacturing processes.