Large seamless pipe forming techniques mainly include: hot spinning method, heat extrusion method, hot piercing rolling method, including preparation of expanding method. The details are as follows:
Hot spinning method,It is the flat blank or pre molded blank is fixed to the rotating core rod, the pressure with the rotary wheel blank, rotation and axial feeding, after one or more processing, get the process of thin-walled hollow rotary body products. Its advantages are high precision products, good mechanical properties, size range. Tool and die is simple, easy to replace, production cost is lower than other methods. The main drawback is the production of long hours, low yield, pipe processing equipment limited by length, short size.
Hot extrusion method,The need for billet machining pretreatment before extrusion, the extruded tube diameter below 100mm, low equipment investment, less waste of materials, technology is more mature. But once the pipe diameter size, by using the method of hot pressing need of large tonnage and large power equipment, the corresponding control system to upgrade.
Hot piercing rolling method,Hot piercing rolling in longitudinal rolling extension and cross rolling elongation. Longitudinal rolling rolling main Co. mandrel pipe mill rolling, MPM Tube Rolling Mill, three roll retained mandrel pipe rolling and floating mandrel pipe mill. The method has high production efficiency, low metal consumption, good product quality, advanced control system, widely used. Cross rolling elongation rolling method with less investment, short process, suitable for small batch, multi varieties, multi specifications and high precision in the thick wall seamless steel tube production and also obtained the widespread application.
Push the process of expanding method,Pushing expanding diameter has the advantages of simple equipment, low cost, convenient repair, economic and durable, the product specifications flexible transformation, such as the need for preparation of large diameter elbow and other similar products, only need to add some accessories. Suitable for production of large diameter, wall thickness of seamless steel tube material, also can produce thick wall pipe does not exceed the capacity of equipment.