Quality defects and prevention of electric heating bands

With the development and improvement of technology, most of the current production of heating rings uses round tube billets. The production cost of round tube billets is lower than that of rolled round tube billets, and because of their good surface quality, the surface defects of the heating rings used to produce them are fewer. Round tube billets are generally produced by vertical machines, arc machines and horizontal machines. The round tube billets produced by vertical machines and arc machines have larger specifications, while the round tube billets produced by horizontal machines have smaller specifications.

Tube billets are different from die casting. It is a continuous casting process with the following obvious characteristics and advantages.

(1) High yield. The method used to produce round tube billets eliminates the loss of residual steel in the middle pouring pipe and the hot water channel when producing tube billets by die casting, and improves the yield of molten steel. At the same time, because the steel ingot does not need an insulation cap, it is no longer necessary to cut off the head of the steel ingot, and its yield rate can be increased by 10% to 15%.

(2) Improved production conditions. The degree of mechanization and automation of round tube billet production is much higher than that of die casting, which greatly improves labor intensity.

(3) Simplified process. The method is used to produce round tube billets, eliminating the intermediate processes such as demoulding and ingot formation in the die casting process. In particular, when the steel ingot cannot be directly used for tube rolling, the die-cast steel ingot needs to be heated and rough-rolled (forged) to open the billet, which increases the production process. Obviously, the production process of round tube billets is simpler and the production cost is lower.

(4) Energy saving. Once the hot delivery and hot loading process is realized in the production of round tube billets, part of the fuel required for heating the tube billets can be saved, thereby greatly reducing energy consumption. It can be seen that the direct use of round tube billets in the production of heating coils has brought a profound revolution to the heating coil manufacturing industry due to its low cost and good quality.

Currently, the production of extra-large and smaller cross-section tubes using this process presents certain difficulties, forcing large pipe jacking mills and small pipe rolling mills to continue using steel ingots and rolled (forged) billets as billets. For high-alloy steels not suitable for this process or for small batches of billets that are uneconomical to produce, rolled (forged) round billets, electroslag ingots, or centrifugally cast hollow round billets are the only options. Furthermore, round billets have gradually replaced steel ingots and rolled (forged) round billets for the production of heater coils. Even cyclic pipe rolling mills, once considered best suited for direct steel ingot production, are now using round billets extensively.

Whether using steel ingots, rolled (forged) round billets, centrifugally cast hollow round billets, or even round billets to produce heater coils, defects in the billet can lead to quality defects in the heater coil. Therefore, ensuring the quality of the billet is paramount to improving the quality of the heater coil.