Shandong Laiduan Machinery Co.,ltd
Add：ZHAILI, LAIWU CITY-SHANDONG PROVINCE – CHINA
The production process of ductile iron pipe can be divided into two kinds: cold drawing and hot rolling. The production process of cold rolling ductile iron pipe is generally more complicated than hot rolling, the first three rollers are to be rolled, and after extrusion, the diameter test should be carried out if the surface does not respond to the crack after cutting machine to cut into the length of about a meters of blank. Then enter the annealing process, annealing to use acidic liquid for pickling, pickling should pay attention to the surface whether there is a large number of blistering, if there is a large number of bubbles to show that the quality of the steel pipe does not reach the standard of response. The appearance of cold rolled ductile iron pipe is shorter than that of hot-rolled ductile iron pipe, the wall thickness of cold rolling ductile iron pipe is generally smaller than that of hot-rolled ductile iron pipe, but the surface looks brighter than that of thick-walled ductile iron pipe, and there is not too much roughness on the surface. The delivery status of hot-rolled ductile iron pipes is generally hot-rolled and delivered after heat treatment. Hot-rolled ductile iron pipe after quality inspection to pass through the strict manual selection of staff, after the quality of the surface coating oil, followed by a number of cold drawing experiments, hot-rolled after treatment to carry out a perforation of the experiment, if the perforation expansion is too large will be straightening rectification. After straightening, the transmission device is transmitted to the flaw detection machine to carry out the flaw detection experiment, finally pastes the label, carries on the specification arrangement after placing to the warehouse.
Round tube billet → heating → perforation → three-roll skew rolling, continuous rolling or extrusion → off Tube → sizing (or reducing diameter) → cooling → straightening → hydrostatic test (or flaw detection) → mark → storage ductile iron pipe is made of steel ingot or solid billet through perforated capillary, then by hot rolling, cold rolling or cold dial. The specification of ductile iron pipes is indicated by the diameter of the wall thickness mm. Nodular cast iron pipe hot-rolled and cold-rolled (dial) Ductile iron pipe two types. Hot-rolled ductile iron pipe is a general steel pipe, low, medium pressure boiler steel pipe, high-pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, geological steel pipe and other steel pipe. Cold rolling (dial) ductile iron pipe In addition to the general steel pipe, low medium pressure boiler steel pipe, high-pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, other steel pipes, but also include carbon thin-walled steel pipe, alloy thin-walled steel pipe, stainless steel thin-walled pipe, profiled steel Hot-rolled seamless pipe diameter is generally greater than 32mm, wall thickness 2.5-200mm, Cold rolled ductile iron pipe diameter can be 6mm, wall thickness can be up to 0.25mm, thin-walled tube diameter can be to 5mm wall thickness is less than 0.25mm, cold rolling than hot rolling size precision.