Structural and seamless steel pipe are both extruded. That means a billet of material is forced through a hole in a die shaped to form the two-dimensional cross-section.
Extrusion of seamless tubes
Extrusion method refers to the metal blank into the extruder barrel, extrusion molding and extrusion rod composed of "closed" container by applying pressure to force the metal extruded rod extrusion die orifice outflow from, and access to metal plastic molding the method, which is a historic seamless manufacturing methods.
According to the direction of extrusion and metal lever urging the relative relationship between the direction of flow, extrusion method can be divided into two kinds of forward extrusion and backward extrusion. Forward extrusion direction of force and metal flowing in the same direction, backward extrusion opposite.
Anti- extrusion with extrusion pressure is small, extrusion ratio, extrusion speed, extrusion temperature can be reduced to improve the extrusion conditions, easy to implement isothermal / isobaric / constant extrusion, improve product performance and dimensional accuracy organizations, can reduce the margin squeeze at the end of the metal pressure, improve metal yield, etc.; but its operation is relatively inconvenient, and the product section size by extrusion rod size restrictions.
Seamless tube extrusion process
Perforated tube round → heating → three-roll rolling, rolling or extrusion → detached → sizing ( or reducing ) → cooling → straightening → hydrostatic test ( or testing ) → mark → storage rolling without the raw material is slit tube round tube, pipe cutting machine embryos to go through cutting the growth of about 1 m blank, and by conveyor belt to the furnace heating. Heating the billet is fed into the furnace, the temperature is about 1200 degrees Celsius. Fuel is hydrogen or acetylene.
Furnace temperature control is the key issue. Circle tube came out through the pressure punching machine wear air. Generally more common punch is tapered roller punching machine, punching machine such high production efficiency, product quality, perforated expanding volume, you can wear a variety of steels.
After perforation, round tube has been three roll rolling, rolling or extrusion. Squeeze off the tube after sizing. Sizing mill rotating at high speed through a cone drill holes into the billet to form pipe. Pipe diameter from the sizing mill to determine the length of the drill diameter. The pipe sizing after entering the cooling tower through water cooling pipe after cooling, will be straightening. Steel belt sent by straightening the metal detection machine ( or water pressure test ) for internal testing.
If the pipe internal cracks, bubbles and other problems will be detected. Steel quality even after rigorous hand-selected. Steel quality, the use of spray paint number, size, production batch number. Hanging by a crane into the warehouse.