1. Steel Rolling Processes and Equipment

(1) Definition of the steel rolling process

Steel rolling refers to the iron and steel rolling process in which the shape of steel ingots or billets is altered between rotating rolls. Since steel ingots or billets coming directly from the steelmaking plant are still semi-finished products, they must undergo a steel rolling stage before they can be transformed into qualified steel products. According to the rolling temperature, the steel rolling process can be divided into hot rolling and cold rolling. Based on the relative motion between the workpiece and the rolls, it can also be categorized into longitudinal rolling, transverse rolling, and skew rolling. Moreover, given the wide variety of rolled products with diverse specifications, the rolling processes themselves differ accordingly. Taking bars and wires as examples, the steel rolling process is illustrated in the figure below:

　　(2) Development of Steel Rolling Processes

　　As a key stage in the steel industry for producing finished steel products, China’s rolling industry has, building on the introduction, digestion, and assimilation of foreign technologies, embarked on integrated innovation and independent innovation. As a result, it has achieved leapfrog development in advancing rolling process technologies, developing advanced equipment and automation systems, and leading the future development of steel materials, making outstanding contributions to the sustainable development of China’s steel industry. Since the reform and opening-up policy was introduced, China has continuously developed its rolling production lines, constructing a large number of such facilities that have reached internationally advanced standards. China now possesses a relatively comprehensive grasp of the world’s most advanced rolling technologies and has developed the capability to design, develop, and manufacture cutting-edge rolling equipment.

　　Although China’s steel rolling technology and equipment have developed rapidly, and its steel production has ranked first in the world for more than a decade, the overall quality of steel products and energy consumption remain cause for concern. This is mainly reflected in the following aspects: The overall physical quality of Chinese steel products is still relatively low, and product quality lacks stability; the upgrading and replacement of widely used hot-rolled ribbed bars and other similar products are slow; the proportion of high-strength, earthquake-resistant rebar produced remains low, and existing codes and standards fail to meet the demands of reducing steel usage; there is still considerable room for improvement in energy conservation and emission reduction within the steel industry—traditional processes still have relatively high energy consumption per ton of steel, and enterprises’ energy-saving and emission-reduction technologies need further optimization; moreover, there are few independent innovations in process technologies, equipment, and key product varieties, and automation technologies for steel rolling process control as well as some critical equipment still largely rely on imports.

　　Therefore, in recent years, research on China’s steel rolling technology and processes has primarily focused on improving the quality and performance of steel products and reducing energy consumption. For instance, since the year 2000, the introduction of segmented rolling technology has created favorable conditions for better integration between continuous casting and steel rolling production. The widespread adoption of segmented rolling technology in bar stock production lines can significantly boost the output of small- and medium-sized bars. Without increasing the number of rolling mills, this approach enables the production of different product specifications from billets of the same cross-section, reduces the variety of raw materials required, and effectively lowers energy consumption and production costs. Moreover, the controlled rolling and controlled cooling process—currently being vigorously promoted by the state—fully leverages the effects of deformation strengthening and phase transformation strengthening. Through optimized rolling processes, it is possible to fully exploit the strength and toughness potential of steel, thereby enhancing both the quality and grade of steel products while reducing the use of microalloying elements.

　　2. Equipment specifically designed for steel rolling

　　(1) Overview

　　In most steel rolling mills, the production process of rolled steel involves multiple rolling stages as well as a series of auxiliary operations, such as transporting raw materials from the warehouse, heating them, feeding the workpieces into the rolls, turning them over, shearing, straightening, marking, collecting the rolled products, and coiling them into rolls. Specialized equipment for steel rolling refers to the mechanical devices used throughout the entire steel-rolling process—from raw materials to finished products. Depending on their specific functions, this equipment can be divided into two main categories: primary equipment—namely, rolling mills—and auxiliary equipment—machinery used outside the rolling mill itself to carry out various supporting processes. The number and variety of auxiliary equipment are substantial, including heating furnaces, guide devices, water-quenching systems, shearing units, finishing equipment, inspection devices, and control systems. In modern steel rolling mills, specialized equipment serving different processing stages is often organized into continuous-operation units according to process requirements, thereby enhancing mechanization and automation levels and continuously improving product output and production efficiency. Although the primary equipment in the steel-rolling process is the rolling mill itself, the specialized, high-quality, and high-tech auxiliary equipment that ensures the smooth and continuous operation of the entire steel-rolling production line plays a crucial role in determining the overall production efficiency of the line, energy savings, material consumption reduction, product variety and quality, and the degree of automation.

　　(2) Industry Development

　　 In recent years, China’s rolling mill equipment has made significant progress. The newly built and put-into-operation modern rolling production lines integrate today’s most advanced rolling technologies worldwide. Key and core rolling technologies—such as energy conservation and consumption reduction, the application of multi-splitting technology, efficient production, reduced-material production, cross-sectional shape control, surface quality control, and the production of high-performance steels through controlled rolling and controlled cooling—have been successfully implemented, thereby raising the overall level of rolling technology and laying a solid equipment foundation for the production of high-quality steel products. Along with the continuous improvement in technological equipment levels, China’s specialized rolling equipment industry has gone through a stage of transitioning from introduction, digestion, and assimilation to independent integration and innovation. It has now developed the capability to independently integrate and develop large-scale, modern rolling production lines and equipment. Moreover, it has established distinctive and advanced integrated technologies in both software and hardware integration and development. As a result, the major process equipment for all key stages of the rolling production process has largely been localized, and China now possesses the capacity to independently build world-class steel mills with annual capacities of tens of millions of tons.

　　Compared with well-known foreign manufacturers of specialized rolling equipment, China’s domestic industry for such equipment still generally faces a technological gap. It has yet to fully shake off its role as a follower in key and core technologies, with relatively few instances of original innovation. In particular, there remains a certain gap compared to international advanced levels in the critical technologies underlying some large-scale, high-precision complete sets of equipment. With the advancement of power electronics, information technology, and modern control theory, the level of electromechanical integration in rolling machinery worldwide has significantly improved. Major breakthroughs have been achieved in the technology of large-scale integrated hot and cold continuous rolling mills: microprocessors are now used for digital control of the main drive systems; rolling production lines have adopted hierarchical, fully computer-based control and comprehensive automation; and practical applications of modern control theories—such as vector control, adaptive control, and self-tuning optimization—have greatly enhanced the overall equipment level of modern large-scale integrated hot and cold continuous rolling mills. However, domestically produced large-scale integrated hot and cold continuous rolling mills still lag behind their internationally renowned counterparts in areas such as multi-level computer control across the entire line and the development of mathematical models for various production processes. Moreover, there are also gaps in the manufacturing precision and service life of certain key spare parts.

　　(3) Competitive Landscape

　　The major domestic manufacturers of specialized equipment for steel rolling include large enterprise groups such as China First Heavy Machinery Co., Ltd., Second Heavy Machinery Group (Deyang) Heavy Equipment Co., Ltd., and Taiyuan Heavy Industry Co., Ltd. All of these companies are heavy machinery manufacturers with strong R&D, design, and core manufacturing capabilities. Their flagship products in the field of specialized steel-rolling equipment primarily consist of complete sets of equipment, including various types of rolling mills. In addition, internationally renowned metallurgical equipment companies such as Germany’s SMS Group, Siemens VAI, and Italy’s Danieli Group continue to hold a significant share in China’s specialized steel-rolling equipment market, particularly in the high-end complete-set equipment segment.

　　In the field of auxiliary equipment for steel rolling, most domestic suppliers are small- and medium-sized enterprises. Each company has only a certain advantage in one or several niche segments. Compared with internationally renowned metallurgical equipment companies, some high-end equipment still lags behind in areas such as new product development, product manufacturing accuracy, and service life. Certain wire rod reducing and sizing mills and three-roll reducing and sizing guides still need to be imported.

　　(4) Market Size and Development Prospects of Specialized Equipment for Steel Rolling

　　According to data from the National Bureau of Statistics, China's steel production increased from 131.46 million tons in 2000 to 1,067.62 million tons in 2013. At the same time, the quality of steel has significantly improved, providing crucial raw material support for the rapid development of industries such as construction, machinery, automotive, home appliances, shipbuilding, and the national economy as a whole.

　　In the coming years, as China’s industrialization and urbanization continue to deepen, the construction of affordable housing projects, water conservancy facilities, and transportation infrastructure will drive steel consumption. At the same time, China will accelerate its shift toward a more sustainable development model, promote industrial transformation and upgrading, and foster the development of strategic emerging industries. Factors such as “steel reduction” will significantly impact both the volume and structure of steel consumption. As a result, the growth rate of steel production will slow down, which will have a certain impact on the expansion of demand for specialized rolling equipment. However, this trend will also boost the adoption of advanced rolling technologies and specialized rolling equipment that align with the goals of the steel industry’s development.