The thicker wall thickness of the product, it is more economical and practical, the thinner the wall thickness, it will be significantly increased processing costs; the product of the process can determine its limitations, low accuracy generally seamless : uneven thickness, the tube looks low brightness, high cut-costs, as well as the appearance of pitting, and is difficult to remove black spots inside; detection and shaping it to be prepainted galvanized steel coil off-line processing.
So it reflects its superiority in high-pressure, high-intensity, mechanical structural material aspects. Piercing and rolling a billet using a square PPM (pressure roll piercing mill) has been modified by replacing the round billet using inclined roll piercing machine. The advantage of a conical punch having a rotary forging machine effect and inhibition effect of shear deformation in the circumferential direction, the defect can be suppressed in the inner surface of the steel pipe can be used for the perforation of the material difficult to process, and particularly can be used for thin-walled perforated reaming. When using an ordinary punch, the limit wall thickness ratio of the outer diameter is about 6%, and the body wall when the piercer can be performed using a conical tube perforation. Stretching rolling mandrel mill is already large and compact direction. Rack chassis number from 7 to 9 minus 4 to 5 racks, punching machine and a mandrel mill required in order to reduce total energy consumption by about 20%. In the mandrel mill control technology in order to reduce crop losses later in tension reducing the wall thickness of the pipe end machine, developed pre-thinning tube end forming technology, which uses a mandrel Mill previously thinned pipe end forming technology, and in the steel mill for the first time using a hydraulic pressure device.
Reducing rolling and sizing rolling, though not worth a special presentation of technological development in the final adjustment reducing the outer diameter sizing rolling and rolling areas, but large-diameter sizing mill also uses many of the shortcomings of three rollers is unable to change the roll away, so much the number of rack units, but recently emerged from a variable roll mill, also proposed a four-roll reducing mill idea. Future mandrel mill and a direct connection technology sizing machines and stretch reducing mill will serve also as cause for concern. Pipe above the area of the perforations in the high-alloy developed by the mandrel and the tube mandrel and the air guide groove has a great development lubricant correlation between theological technique is therefore desirable to have a long life and further development of the technology.
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