Comparison of Formation Methods of Spheres


1. Casting method: This is a traditional processing method that requires a complete set of melting, pouring and other equipment, as well as a large factory building and a large number of workers. It requires a large investment, multiple processes, complex production processes, and pollutes the environment. The technical level of workers in each process directly affects the quality of the product. The problem of leakage from the pores of the ball cannot be completely solved, and the blank processing has a large margin and waste, It is often found during the processing that due to casting defects, the product is scrapped, resulting in increased cost and quality assurance. This method is not suitable for our factory to use.

2. Forging method: This is another method currently used by many valve enterprises in China. There are two processing methods: one is to use round steel to cut, heat, and forge into a spherical solid blank, and then perform mechanical processing. The second method is to mold the stainless steel plates that are cut into a circular shape on a large press to obtain a hollow hemispherical blank, which is then welded into a spherical blank for mechanical processing. This method has a high material utilization rate, but requires a high-power press, heating furnace, and argon arc welding equipment. It is expected to require an investment of 3 million yuan to form productivity, which is not suitable for our factory.

3. Spinning method: Metal spinning method is an advanced and chip free processing method, belonging to a new branch of pressure processing. It combines the characteristics of forging, extrusion, rolling, and rolling processes, has a high material utilization rate (up to 80-90%), saves a lot of processing time (1-5 minutes of forming), and can double the material strength after spinning. Due to the small area of contact between the spinning wheel and the workpiece during spinning, the metal material is subjected to two or three directions of compressive stress, making it easy to deform. Under small power, it can achieve a higher unit contact stress (up to 2535Mpa). Therefore, the equipment is light in weight and requires less total power (less than 1/5-1/4 of the press). It is now recognized by the foreign valve industry as an energy-saving ball processing process plan, It is also suitable for processing other hollow rotating parts. Spinning technology has been widely applied and rapidly developed abroad, with mature and stable processes and equipment, and achieving automatic control of mechanical, electrical, and hydraulic integration. At present, spinning technology has also been greatly developed in China and has entered a stage of promotion and practicality.