Large-scale seamless tube forming technology are: hot spinning method, hot extrusion method, hot piercing rolling method, hot push expansion method. details as follows:
1, Hot spinning method
It is the flat blank or pre-shaped blank fixed to the rotating mandrel, with the wheel pressure on the rough, while the wheel for axial feed, after one or more processing, to obtain a variety of thin-walled hollow rotary system product of the process. The advantage is the product of high precision, good mechanical properties, a wide range of sizes. Tool mold is simple, easy to replace, production costs lower than other methods. The main disadvantage is the long production hours, low output, the processing of the pipe by the device length restrictions, short size.
2, Hot extrusion method
Before extrusion, it is necessary to pretreat the billet by machining. When the pipe with a diameter of less than 100mm is squeezed, the equipment will be put into small parts with less material waste and the technology is more mature. However, once the pipe diameter size increases, the use of hot extrusion method requires large tonnage and high-power equipment, the corresponding control system should be upgraded.
3, Hot piercing rolling method
Hot perforation rolling to the longitudinal extension of the rolling and oblique-based extension. Longitudinal rolling extension of the main limited rolling mandrel rolling mill, mandrel less limited mandrel rolling, three mandrel rolling and floating mandrel rolling. These methods have the advantages of high production efficiency, low metal consumption, good product quality, advanced control system and wide application. Slant rolling extension rolling method with a small investment, the process is short, suitable for small quantities, more varieties, specifications and high precision medium-thickness seamless pipe production has also been widely used.
4, Hot push expansion method
Push to expand the diameter of the device is simple, low cost, easy maintenance, economical and durable, flexible product specifications change, such as the need to prepare large-diameter elbow and similar products, just add some accessories. Suitable for the production of thin-walled large-diameter seamless steel pipe, can produce no more than the capacity of thick-walled tubes.
