The tube billets used in the production of electric heating coils can be round tube billets, rolled (forged) round tube billets (made of square billets or steel ingots through rolling of forging mills or forging machines), and centrifugally cast round hollow tube billets. You can also use steel ingots directly.
With the development and perfection of technology, the current production of heating coils mostly uses round tube blanks. The production cost of the round tube billet is lower than that of the rolled round tube billet, and because of its good surface quality, there are fewer surface defects on the heating coil used for production.
Round tube blanks are generally produced using vertical machines, arc machines and horizontal machines. Round tube blanks produced by vertical and arc machines have larger specifications, while round tube blanks produced by horizontal machines have smaller specifications.
The pipe blank is different from die casting, it is a continuous casting process, and has the following obvious characteristics and advantages.
(1) High yield. The method is used to produce round pipe blanks, which eliminates the residual steel loss of the injection pipe and the soup channel when producing the pipe blanks by die casting, improves the yield of the molten steel, and because the ingot does not require a thermal insulation cap, it does not need to be cut off. For the ingot head, the material yield can be increased by 10% to 15%.
(2) Changes in production conditions. The degree of mechanization and automation for the production of round tube billets is much higher than that of die casting production, which greatly changes the labor intensity.
(3) The process is simplified. The method uses the method to produce round tube blanks, eliminating the intermediate steps such as demolding and ingot in the die casting process. In particular, when steel ingots cannot be used for tube rolling directly, heating and rough rolling (forging) of the cast steel ingots are also required, which increases the production process. Obviously, the production process of round tube blanks is simpler and the production costs are lower.
(4) Save energy. For the production of round tube billets, once the hot-sending and hot-filling process is realized, a part of the fuel required for the tube billet heating can be omitted, thereby greatly reducing energy consumption. It can be seen that the round tube blank is directly used in the production of heating coils. Because of its low cost and good quality, it has brought a profound revolution to the manufacturing of heating coils.
At present, there are still difficulties in producing tube blanks with extra-large cross sections and smaller cross-sections using technology, which makes large pipe jacking units and small tube rolling units still have to still use steel ingots and rolled (forged) billets as tube rolling blanks; and some are not suitable for use. The high-alloy steel produced by the process or the low-volume tube billets that are not economical to produce can only use rolled (forged) round tube billets, electroslag ingots, or centrifugally cast hollow tube billets as tube billets. In addition, round billets have gradually replaced steel ingots and rolled (forged) round billets for the production of heating coils. Even the original cycle rolling mill, which was originally thought to be suitable for the direct use of steel ingots to produce heating coils, has been using a large number of round billets for rolling.
No matter it is the use of steel ingots, rolled (forged) round tube blanks, or centrifugal casting of round hollow tube blanks, or even the use of round tube blanks to produce heating coils, heating coils may be caused by defects in the quality of the tube billets. Quality defects. Therefore, in order to improve the quality of the heating coil, the first step is to ensure the quality of the tube blank.