TPT July 2021

T E CHNOLOG Y

T E CHNOLOG Y

Innovative design that improves the productivity of SHS and RHS tube mills

AS COUNTRIES around the world prioritise investment in infrastructure, the steel tube industry is witnessing a record amount of large size and heavy gauge structural SHS and RHS being utilised at metropolitan airports, high speed train stations, bridges and stadiums. As demand for a wide variety of high quality structural SHS and RHS grows, there have been calls for enhanced versatility and improved efficiency of the production process. Structural steel SHS and RHS manufacturers have been seeking innovative solutions to cut down tooling cost and machine downtime for tooling changeover or adjustment. After extensive market research and technical viability studies, Shijiazhuang Forever Machinery became the first company in China to successfully incorporate direct forming process in the ERW SHS and RHS production line in 2000. Adopting the multi-point pre- bend technology, this tube mill line was able to achieve changeover by solely adjusting the spacers without having to change the rolls. Insertion type spacers are designed in a way to facilitate changeover without the need to dismantle the shaft assembly or the gantry type machine stand.

Statistics at the tube manufacturers has shown a 70 per cent cost reduction in tooling compared to similar size traditional tube mill they have previously owned and operated. Changeover time was also significantly shortened due to the implementation of insertion type spacers and specially designed rolls. The application and rollout of the direct forming mill in China was a revolutionary change. With its advantages in product- ivity and cost effectiveness, the direct forming mill was especially competitive for manufacturers who produce a large range of SHS and RHS with varying dimensions and gauges. Due to the shortened changeover time, the manufacturers were able to boost the efficiency of their manufacturing process and save hundreds of thousands by investing in direct forming mill. Saving material and labour cost while maintaining a wide range of products has always been the ultimate goal for steel tube and pipe manufacturers. Based on data gathered from various tube manufacturers, the width of the raw materials (steel coil) received by direct forming mill is a proximately 4 to 8 per cent narrower than producing the same size tube on a traditional round- to-square tube mill. This is due to the

unique nature of the direct forming process, which involves much less deformation of raw materials than the round-to-square process. The standard configuration of a direct formingmill comprises 12 forming stands and 4 or 5 sizing stands depending on the specifications of the products. First 4 forming stands make up the preliminary stage of the forming section where each set of rolls performs incremental parts of the bend to allocate material for each side of the SHS or RHS. The next few stands perform further bend to form the preliminary profile of the SHS and RHS. Then the last three stands of the forming section prepare the profile for welding. As structural SHS and RHS gains popularity in modern infrastructure con- struction and the manufacturing industry, the demand for a less labour- intensive and user-friendly tube mill has been surging. To keep up with the growing demand for a more intelligent tube mill, Forever Machinery has never stopped optimising the direct forming process and has been innovating with refined engineering practice to revamp the design. Based upon performance analysis of existing direct forming mill and research into machinery automation, in 2015,

Saving material and labour costs while maintaining a wide range of products has always been the ultimate goal for steel tube and pipe manufacturers

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JULY 2021