Production process of HSS sections

The transformation of steel sheets into hollow structural sections(HSS) in the cold rolling method is done in several different ways, and this article mentions one of the most up-to-date and optimal production methods. In this method, the flat steel sheet is continuously formed along the longitudinal axis during a cold rolling process to become a tube with a round cross-section. It is done by moving the sheet through a set of rollers. The edges of the sheet are placed adjacent to each other and heated by high-frequency induction welding or contact welding and the edges sink into each other as a result of welding to form a continuous longitudinal weld without the need to add filler metal(electrode) to be formed. Then the weld seam is bent and finally it is converted into round, square or rectangular sized sections by passing through a series of sizing rollers during another cold rolling process.

Preparation

First, the steel coils are opened at the beginning of the production line, then the flattened sheets are directed to the forming part. To prevent the line from stopping and maintaining its continuity, before the previous coil is finished, in the middle of the storage line, a new coil is inserted into the line, then the end of the previous coil is welded to the beginning of the new coil

Forming

The flattened sheets are curved with a gentle slope in 12 stages and the two ends of the sheet are placed at a suitable distance before longitudinal welding, and after welding, a circular cross-section is created

Welding

The high frequency welding machine, manufactured by EFD Norway, is able to weld the prepared edges of the sheet longitudinally and continuously, without using an external object (electrode). This weld has the best quality and is a component of induction ERW electrical resistance. Due to the lack of noticeable change in the temperature gradient in the cross section of the sheet, the molecular structure will have the least possible change

CutOff

This stage is performed by an advanced rotary cutting machine with two blades, which dynamically performs the cutting line without stopping the production line, and the end cutting surface is fully machined without bending

Quality Control

Standard quality control tests are performed on samples of the produced sections. ASTM, EN DIN, JIS standards are checked during the quality control process and the product specifications are adapted to the standard specifications. If there is a discrepancy, it will be removed from the production path. In order to obtain the AWWA standard, all the required tests, including ON-LINE ultrasonic test, are performed and controlled on the products

Steel Manufacturing

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