Three molding methods for valve spheres
Comparison of valve ball forming methods:
(1) Valve ball casting method
This is a traditional processing method that requires a complete set of melting, pouring and other equipment, as well as large factories and a large number of workers. Large investment, multiple processes, complex production techniques, and environmental pollution. The technical level of each process worker directly affects the quality of the product, and the problem of leakage from the internal pores of the sphere cannot be completely solved. However, the blank machining allowance is large, resulting in significant waste. Casting defects are often found during the machining process, leading to scrap and increased product costs.
(2) Valve ball forging method
This is another method currently adopted by many valve ball enterprises in China. There are two processing methods: one is to cut off round steel, heat forge it into a spherical solid billet, and then machine it. Secondly, the circular stainless steel plate is formed on a large press to obtain a hollow hemispherical billet, which is then processed and welded into the hemispherical billet. This method has a high material utilization rate, but requires high-power presses, heating furnaces, and argon arc welding equipment. It is estimated that an investment of 3 million yuan is needed to form production capacity, and everyone needs to act within their means.
(3) Valve ball spinning method
Metal spinning is a new branch of pressure processing that involves minimal and no chips. It integrates the process characteristics of forging, extrusion, rolling, and rolling, with high material utilization rate (up to 80-90%), saving a lot of processing time (1-5 minutes for forming), and doubling the material strength after spinning. During spinning, the contact area between the rotating wheel and the workpiece is small, and the metal material is under bi-directional or triaxial compressive stress, which makes it easy to deform. With less power, higher unit contact stress (up to 25-35Mpa) can be achieved. Therefore, the device is lightweight and requires less total power (less than 1/5-1/4 of the press), and has been recognized as an energy-saving ball processing technology by the foreign valve ball industry.
