Main Large Size Seamless Pipe Forming Technology
Large size seamless pipe forming technology mainly include: hot spinning pipe, hot extrusion pipe, hot piercing rolling pipe and heat pushing expansion pipe. As follows:
1. Hot spinning pipe:
The flat blank or advanced rough fixed on the rotating mandrel, with wheel to pressure on the blank, wheel for axial sent at the same time, through one or more processing, products have all kinds of hollow thin-wall revolving body process method . Its advantage is the product of high precision, good mechanical performance, size range. Tool mould is simple and easy replacement, the production cost is lower than other methods. Meanwhile the main drawback is the production of long hours, low yield, fitting the equipment manufactured by length limit and short size.
2. Hot extrusion pipe:
Before squeeze it needs pretreatment for billet machining, when extrusion diameter under 100 mm for pipe fittings, low investment of equipment, less waste of materials, and the technology is relatively mature. But once the pipe diameter size increases, adopt the method of hot extrusion requires large capacity and high power devices, the corresponding control system will upgrade also.
3. Hot rolling perforation
Hot rolling perforation is given priority to the longitudinal rolling extension and skew rolling extension. Extension longitudinal rolling mill main limited mandrel MPM rolling, less stand mandrel MPM rolling, three roll limit mandrel MPM rolling and floating mandrel MPM rolling. The method is of high production efficiency, low metal consumption, good product quality, advanced control system and increasingly widely used. Extend skew rolling method with low cost, short process, suitable for small batch and many varieties, many specifications, and high precision thick-walled seamless tube production and has been widely used at the same time.
Heat pushing expanding law-making equipment is simple, low cost, easy maintenance, and durable, flexible product specifications, such as preparation of large-diameter elbow and other similar products and only need to add some accessories. Suitable for the production of medium and large-diameter seamless steel pipe wall thickness material or produce thick-walled tube have not exceed the capacity.