As an important equipment of steel rolling process, roll is related to the high-efficiency continuous production and product quality of rolled products in an iron and steel enterprise. At present, the material selection, manufacturing technology and quality control of roller production in China have reached the level of advanced countries in the 1990s. However, according to the analysis of the usage of roller, the consumption level of steel per ton of roller still stops at the level of 1960s abroad. According to the statistics, the average consumption of roller per ton of steel in China was 2.46kg/t in 2000. Through detailed analysis, it can be seen that 35% to 50% of the roller consumption of most users are non productive consumption. In other words, nearly half of the rollers consumed in China each year are not productive consumption of normal steel rolling. In particular, some data from the cold rolling mill reflect that less than 20% of the rolls are normally scrapped. The high proportion of non productive consumption of rolls also causes the problems of low operation rate of rolling mill, difficult rolling of high-grade rolled products, and high cost of roll replacement, which affects the development of steel rolling industry.
Title：An Elementary Introduction to the Operation Technology of Rolls
Keywords：Roll . Steel Rolling . Operation Technology.
- Formation of roll application technology
In recent years, foreign steel rolling industry has appeared high efficiency, large-scale continuous, automation and other low energy consumption and environmental protection new steel rolling enterprises, also pay more attention to the research of low energy consumption technology and precision control rolling technology. The proportion of steel varieties with thinner and harder quality, higher surface and gauge quality is increasing. In order to adapt to the development of rolling technology and rolling equipment, new materials and new products of roll are developed and applied in actual production. This puts forward higher requirements for roll management mode and roll use technology. Therefore, it is very important to carry out systematic and in-depth research on roll use technology to improve the operation rate and quality of rolling mill and prolong the service life of roll. The domestic roll material and manufacturing technology are also developing towards high purity purification, high alloying, compounding and high hardness. The development and rapid large-scale application of composite high speed steel hot strip roll in Japan is a successful example of paying attention to the application technology research. Since the 1980s, some newly-built iron and steel enterprises in our country have come into contact with some of these technologies and realized the importance of mastering the technology of roller use by introducing the management mode of complete sets of rolling equipment and the latest developed new roller varieties. Both steel mills and roll manufacturers realize that the rapid development of rolling technology and the continuous improvement of product quality can not be met only by purchasing high-quality rolls with high price without the support of roll application technology.
The backwardness of roll application technology is also the key to the backwardness of the development level of roll and other related fields in China. Therefore, it has become the consensus of rolling and roll manufacturing industry to improve the technical level of roll use in China. In the early 1990s, Baosteel was the first to study the roll application technology. Now this research has become a very important work in the daily rolling production management of Baosteel, and has gained a lot of experience. For example, Baosteel’s high chromium series ultra deep quenched layer forged steel cold rolling work roll has been successfully developed from research and development to large-scale application in a short time on the basis of paying attention to the research of application technology. Now, the unit consumption coefficient of Baosteel’s rolls is one third of the average value in China. This is not only due to the advanced rolling equipment and the high proportion of imported high-quality rolls, but also a very important reason, Baosteel has always attached importance to and absorbed the latest research results of roll use technology in the world, and has initially formed a relatively complete roll use technology system suitable for Baosteel’s management mechanism.
- definition and characteristics of roller application technology
Roll use technology includes the scientific management methods and skills used by the relevant departments of roll to ensure the operation rate of rolling mill, improve the quality of rolled products and reduce the use cost. This technology is the extension and supplement of steel rolling technology and roll manufacturing technology, and it is the practical application of roll measurement and detection technology, roll machining technology, roll surface treatment technology, production operation management science and many other related cross field technologies. The characteristics of roller application technology are: the cooperation and complementarity of manufacturing, application and maintenance. It is a platform to promote the development of roller technology. The effective cooperation of roller related departments in rolling mill and the quality of roller management engineers and technicians are the basis of roller application technology.
- The main role of roll application technology
The application technology of roller can be divided into four parts. The first is supportability, including ensuring the operation rate of rolling mill, improving and stabilizing the quality of rolled products; The second part is to reduce the use cost; The third part is continuous improvement. The main content is to adapt to and improve the environment of roller use and improve the efficiency of use and maintenance; The fourth part is the use technology of roller in abnormal period. The old roll using technology and the present roll using technology
4.1 guarantee and continuously improve the efficiency of the rolling mill and ensure the quality of rolled products. On the premise of ensuring the complete rolling process of the rolling mill, extend the roll change cycle in a scientific way, and monitor the physical quality of the rolls in use and standby circulation in a scientific way, so as to reduce the accident rate and unplanned roll change rate of the rolls, It makes it possible to implement new rolling technologies such as free rolling. At the same time, under the condition of high efficiency, high precision and low energy consumption, by improving the roll surface quality and controlling uniform wear, the auxiliary rolling control system can produce the gauge, surface quality and performance
4.2 promote the development and use of new roll varieties, and cultivate users to expand the demand for new roll varieties. On the premise of ensuring the operation rate of rolling mill, replace the original roll varieties with rolls with higher price performance and more suitable for rolling mill. At the same time, in order to adapt to the development of new rolling technology and promote the roll manufacturing industry to develop long-life and low-cost rolls, better carry out “roll life-long service” for users, cultivate users, help users reduce the risk of using new varieties of rolls in the trial process, and reduce the cost of roll trial production, so as to expand users’ demand for new varieties of rolls.
4.3 use technology of abnormal period. The application technology of abnormal period refers to the application technology of roller in abnormal period, such as the period of updating new and old roller, the running in period of new supplier, the change period of rolling products and the inventory turnover in the initial stage of new or reconstructed rolling line.
- Main research contents of roller application technology
The relationship between how to improve rolling efficiency (rolling mill operation rate) and roll change cycle is studied. The relationship between the gauge accuracy and the physical and mechanical properties of the roll material is studied. The relationship between surface quality, gauge accuracy and roll profile and surface roughness was studied. The relationship between prolonging roll changing period and ensuring roll safety and economy is studied. This paper studies the relationship between the direct and indirect costs of roller use and the use environment and rolling varieties, and the relationship between improving the utilization rate of turning grinder and ensuring the safety of the next use cycle. The influencing factors of reducing the accident rate, preventing the abnormal failure of rolls and the related and indirect loss of rolls are studied. The relationship between reducing the proportion of non productive failure and the quality of rolls and the environment of rolling mill operation and maintenance is studied. The relationship among repair methods, repair cost and reuse cost of various rolls was studied. The relationship between the surface quality of rolled products and the performance of rolls and the way of surface roughening, surface chrome plating and other strengthening roll surface treatment as well as the use cost were studied. The relationship between on-line cleaning, on-line inspection and on-line grinding and surface quality of rolled products, roll performance and cost was studied. This paper studies how to predict the service life of the roller in different environments according to the mechanical properties of the roller. The relationship between the change of cooling conditions and the performance of roll was studied. This paper studies the relationship between how to purchase personalized and stable high-performance rolls suitable for each rolling mill and how to reduce the purchase cost of rolls. Study how to control the appropriate turnover, inventory, abnormal accident volume and the relationship between timely and appropriate procurement This paper studies the application effect and different influencing factors of the same material and same process roller in different use environment and different use period.
This paper studies the influence of roll replacement on the original rolling environment, rolling operation and maintenance mode, cost change, new and old material mixing period management and adaptation period process.
- Problems existing in roller application in China
(1) In each stage of roller R & D, manufacturing, operation and maintenance, manufacturers and users have not really established an effective channel for joint research.
(2) Some users only pay attention to reducing the direct cost and consumption coefficient of rolls when using rolls.
(3) In the process of research and development of new roll products, there is less research on the use of technology, that is to say, there is less research on how to use new roll products to improve and guarantee the operation rate of rolling mill and improve the quality of rolled products. At the same time, it lacks detailed analysis of non productive consumption and comparison of price performance ratio of new products. In addition, there is a lack of the concept of R & D roller serialization or quality personalization.
(4) The research on failure analysis and accident failure analysis of roller is far from enough, and it has not achieved the goal of controlling the dynamic quality of the manufacturer and developing personalized varieties through these research results.
- development trend of roll application technology
(1) Due to the obvious lag between the domestic research on roll application technology and the development speed of rolling technology and new roll R & D, it is expected that many relevant units will focus on the research in the near future.
(2) The research on roll application technology will extend to the upstream and downstream, and integrate with roll manufacturing technology and rolling control technology, adapt to each other and develop synchronously. The research on the relationship between the roller service environment and the roller quality control will be more in-depth.
(3) The roller using technology will be the main content of after-sales service for roller manufacturing enterprises in the future. The lifelong service level of roller suppliers will become the main factor of industry competition.
(4) When the supplier and the demander jointly develop new products, technical transformation of equipment in grinding roll room and formulate new roll management mode and system, roll use technology is an important consideration.
(5) The improvement of the use and maintenance environment of rolls will continue. For example, hot rolling and cold rolling endless rolling technology, steel plate edge induction heating, rolling oil, continuous detection, on-line grinding, central enhanced controllable cooling system, finishing stand set-up roll, work roll backup roll bearing grinding, automatic rapid roll change system The technology of measuring grinding, non-destructive testing, special purpose vehicle grinding machine and so on will be gradually mature and continue to be developed.