Classification of forming technology for large-size seamless pipe fittings

The forming technologies of large-size seamless pipe fittings mainly include: hot spinning, hot extrusion, hot piercing and rolling, and hot pushing and expanding. Details as follows:

1.Hot spinning method

It fixes the flat blank or pre-formed blank to the rotating mandrel, applies pressure to the blank with a rotating wheel, and the rotating wheel simultaneously feeds in the axial direction. After one or more processing, various thin-walled hollow rotating systems are obtained. The process method of the product. Its advantages are high product precision, good mechanical properties and wide size range. The tool mold is simple, easy to replace, and the production cost is lower than other methods. The main disadvantages are long production hours and low output. The processed pipe fittings are limited by the length of the equipment and the size is short.

ASTM A106 API 5L seamless steel pipes

2.Hot extrusion method

The billet needs to be pre-processed before extrusion. When extruding pipes with a diameter of less than 100mm, the equipment investment is small, the material waste is small, and the technology is relatively mature. However, once the pipe diameter size increases, the hot extrusion method requires large tonnage and high power equipment, and the corresponding control system must be upgraded.

3.Hot piercing and rolling method

Hot piercing rolling is mainly based on longitudinal rolling and cross rolling. Longitudinal rolling and extension rolling are mainly limited-moving mandrel continuous tube rolling, few-stand-restricted mandrel continuous rolling tube rolling, three-roll restricted mandrel continuous rolling tube rolling, and floating mandrel continuous tube rolling. These methods have high production efficiency, low metal consumption, good product quality, advanced control systems, and increasingly widespread applications. The skew extension rolling method has also been widely used because of its low investment, short process, suitable for small batches, multiple varieties, multiple specifications and high-precision production of medium-thick wall seamless pipes.

4.Hot push system expansion method

The diameter expansion equipment is simple, low cost, convenient maintenance, economical and durable, and the product specification is flexible. If you need to prepare large diameter elbows and other similar products, you only need to add some accessories. Suitable for the production of medium and thin-walled large-diameter seamless steel pipes, as well as thick-walled pipes that do not exceed the equipment capacity.