1. The principle of sphere spinning
1.1. Valve ball technical parameters
Table 1: Sphere technical parameters
1.2 Comparison of sphere forming methods
(1) Casting method
This is a traditional processing method. It requires a complete set of equipment for smelting and pouring. It also requires a larger plant and more workers. It requires a large investment, many processes, complex production processes, and pollutes the environment. Every process The technical level of the workers directly affects the quality of the product. The problem of the pore leakage of the sphere can not be completely solved, and the blank processing allowance is large, and the waste is large. It is often found that the casting defect makes it scrapped during the processing, which will increase the cost of the product. , The quality cannot be guaranteed, this method is not suitable for our factory. To
(2) Forging method
This is another method currently used by many domestic valve companies. It has two processing methods: one is to use round steel to cut and heat forge into a spherical solid blank, and then perform mechanical processing. The second is to mold the stainless steel plate into a round 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 higher material utilization rate, but a high-powered one is required. The press, heating furnace and argon welding equipment are expected to require an investment of 3 million yuan to form productivity. To
(3) Spinning method
The metal spinning method is an advanced processing method with less and no chips. It belongs to a new branch of pressure processing. It combines the characteristics of forging, extrusion, rolling and rolling, and has high material utilization (up to 80-90%). ), saving a lot of processing time (1-5 minutes forming), the strength of the material can be doubled after spinning. Due to the small area contact between the rotating wheel and the workpiece during spinning, the metal material is in a two-way or three-way compressive stress state, which is easy to deform. Under a small power, a higher unit contact stress (up to 25- 35Mpa), therefore, the equipment is light in weight, and the total power required is small (less than 1/5 to 1/4 of the press). It has been recognized by the foreign valve industry as an energy-saving spherical processing technology program, and it is also applicable For processing other hollow rotating parts. To
Spinning technology has been widely used and developed rapidly abroad. The technology and equipment are very mature and stable, and the automatic control of mechanical, electrical, and hydraulic integration is realized. At present, spinning technology has also been greatly developed in my country and has entered the stage of popularization and practicality. To
2. Technical conditions for spinning sphere blanks
According to the production needs of our factory and combined with the characteristics of spinning deformation, the following technical conditions are drawn up:
(1) Material and type of spinning blank: 1Gr18Nr9Tr, 2Gr13 steel pipe or steel plate;
(2) The shape and structure of the spinning sphere blank:
3. Spinning scheme
Sphere spinning has different effects due to the different types of blanks selected. After analysis, two solutions are available:
3.1. Steel pipe necking and spinning method
This scheme is divided into three steps: the first step is to cut the steel pipe according to the size and clamp it in the spindle chuck of the spinning machine tool to rotate with the spindle. The diameter is gradually reduced to form a semicircular sphere; in the second step, the formed sphere is cut off and the welding groove is processed; in the third step, the two hemispheres are butt-welded with argon solitary welding to form the required hollow sphere blank . To
The advantages of the steel pipe necking and spinning method: no mold is required, and the forming process is simpler; the disadvantage is: a specific steel pipe is required, with welds, and the cost of the steel pipe is higher. To
3.2. Steel plate general rotation method
There are two ways in this scheme: the first way is to press the flat circular material on the outer end surface of the spherical mandrel by the hydraulic jacking force of the tailstock, and rotate with the main shaft. The hydraulic profiling device is used to rotate several times. Press to make the flat plate gradually shrink and deform and attach it to the core mold to obtain a hollow hemisphere, then cut off the excess burrs and process the welding groove, and then weld the two hemispheres with argon solitary welding to form the required hollow sphere blank .
The second method also uses general spinning of flat blanks. The difference is that after spinning into a hemispherical shape, a section of semi-finished products in cylindrical shape needs to be screwed out, and then the semi-finished blanks are installed in the inner hemispherical core mold. The same tailstock ejector rod is compressed, and the same spinning method as the necking of the steel pipe is performed. The cylindrical section is gradually reduced (closed) to form the other hemisphere, and the excess metal material of the closed end is attached to the ejector rod, and finally cut off Excess part to obtain a required overall hollow ball blank. To
The advantages of this method of the steel plate general rotation method: the source of the steel plate is convenient, the price is lower than that of the steel pipe, and a complete hollow structure sphere can be realized. Compared with the previous scheme of the steel pipe necking spinning method, the disadvantage is that two core molds are required, the spinning process is complicated, the structure and control of the spinning equipment required are more complicated, and the equipment cost is higher, but from the aspects of economic benefits and product quality Analysis, this program is still the best program. To
4. Selection of spinning machine tools
The spinning machine tool is composed of three parts: mechanical, electrical, and hydraulic. It is a relatively advanced medium-sized machine tool with advanced mechatronics-hydraulic integration. The schematic principle of the machine tool. It is composed of main shaft gearbox and hydraulic ejector, tailstock, rotary frame, bed and other parts. To
In terms of hydraulic transmission, there is a hydraulic station and its hydraulic system, which provide all power for the machine tool except for the rotation of the spindle. The lateral direction of the rotary wheel is a spinning profiling control device, including profiling valves, profiling plates, adjustment mechanisms and brackets. To
In the aspect of electronic control, advanced computer automatic control is adopted to realize the automation of the spinning process. To
5. Conclusion
The comparison of the above-mentioned various processing schemes shows that the sphere blank spinning with a flat plate is the best scheme, and the expected effect is achieved in both the process and the product quality. But everything has its two sides. The flat spinning sphere process is complicated, and the spinning equipment structure and automatic control required have higher requirements, which limits its promotion.
