Steel pipes are generally divided into two categories, one is welded steel pipe and the other is seamless steel pipe. Welded steel pipe, also called welded pipe, is a steel pipe made by welding steel plates or strips after roll forming. The production process of welded steel pipe is simple, the production efficiency is high, there are many varieties and specifications, and the equipment cost is small, but the general strength is lower than that of seamless steel pipe. Since the 1930s, with the rapid development of continuous production of high-quality strip steel and the advancement of welding and inspection technology, the quality of welds has been continuously improved, and the variety of welded steel pipes has increased, and has replaced seamless steel pipes in more and more fields.
Welded steel pipe is divided into straight seam welded pipe and spiral welded pipe according to the form of weld. The blanks used for welding steel pipes are steel plates or strip steels, which are divided into furnace welded pipes, electric welded (resistance welded) pipes, and automatic arc welded pipes due to their different welding processes. There are two types of welded pipe: straight seam welded pipe and spiral welded pipe.
The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is fast. The strength of spiral welded pipes is generally higher than that of straight seam welded pipes. Welded pipes with larger diameters can be produced from narrower billets. Welded pipes with different diameters can also be produced with billets of the same width. However, compared with the straight seam pipe of the same length, the weld seam length of the spiral welded pipe is increased by 30 to 100%, and the production speed is lower.
The smaller-diameter welded pipes are mostly straight seam welded, and the large-diameter welded pipes are mostly spiral welded.
The pipe welding unit is the core equipment of the welded pipe production line. The normal operation of the unit plays a vital role in improving the unit's production efficiency, increasing economic benefits, and ensuring product quality. What are the main equipments of a high-frequency welded pipe production line?
Uncoiler: There are two uncoiling methods: upper uncoiling and lower uncoiling.
Steel belt leveling machine: generally consists of upper frame, lower frame, transmission device, etc., there are five rollers, seven rollers and so on. Used to level the strip before forming.
Cutting head butt welding machine: The irregular head and tail ends of the strips are cut neatly by the cutting butt welding machine to ensure continuous production of the production line.
Looper for storage: Looper storage device must be set before the strip head and tail shearing butt welding station. To ensure continuous production of welded pipe units.
Horizontal Looper: Horizontal spiral looper is suitable for strip thickness range 0.4-16mm. The advantage of the horizontal looper is that it can be charged at any time, the strip deformation is small.
High frequency pipe welding machine: Straight seam welding pipe forming machine is divided into straight seam resistance roller type and straight seam submerged arc welding compression molding.
High-frequency welding device: The skin effect and proximity effect of high-frequency current are used to quickly heat the weld to a molten state, and welding is achieved by extrusion.
Sizing section: used to improve the stress concentration and residual stress of forming and welding production.
Roll forming: The roller is the main consumable part of the high-frequency welded pipe production machine. The quality of the roll mold directly affects the yield, production efficiency and quality of the high-frequency welded pipe.
Cut-to-length cutting machine: realizes high-precision cut-to-length cutting in the online state.
