Roller repair technology The squeezing roller on the roller press is a key component in the production line. The wear layer on the surface of the squeezing roller is usually only 10mm thick. The exposed metal after the wear layer is worn away will be worn away in a very short time. The roll is deeply worn (see Figure 1). Therefore, after the roller press has been working for a period of time, it is necessary to repair the surface wear-resistant layer. According to the working conditions, it is divided into the repair without removing the squeeze roller (referred to as online repair) and the repair of the crush roller (referred to as offline repair). ). Among them, the online repair has the advantages of short cycle and small impact on production, so most of the squeezing rollers are repaired in this way, and the following difficulties exist in on-site construction: (1) It is required that the construction period is short and the online surfacing repair requirement period is as short as possible to meet the requirements of starting the cement production line as soon as possible after maintenance. figure 1 (2) The large diameter of the roller causes the risk of quality problems after surfacing. The diameter of the squeezing roller is usually 1000~1800mm, and the width of the roller surface is also 450~1400mm. Such a large-diameter, large-thickness solid roll is subjected to a large welding stress and a large welding residual stress. The welding stress can easily cause the high hardness and wear-resistant material of the roll surface to be peeled off, or the welding residual stress overlaps with the working load during work, causing the wear-resisting layer to peel off and damage the crushing roller (see Fig. 2). (3) The welding work is large and the welding process is formulated. The surfacing welding of the squeezing roller is required. Except for the beginning part of the work is the planing, the rest is the welding work. The rollers of a roller press for surfacing need different welding wires of 2000~4500kg depending on the model, and a single roller is used to weld 400~600kg welding wire every day. The speciality of wear-resistant surfacing determines the need to use different welding materials and welding processes such as transition layer, repair layer and wear layer during welding, which puts higher requirements on the formulation and implementation of welding technology. 2. Roller surfacing implementation In view of several major difficulties and points of online repair of the above roller press, it is necessary to formulate reasonable construction plans, welding process guidance and other measures before the construction of the maintenance. During the construction process, various construction techniques must be strictly monitored to ensure the quality. (1) Organize and implement clearly the person in charge of the project, the safety and quality supervision personnel, the person in charge of the night shift of the day shift, and the specific number of construction workers. Reasonable formulation of specific construction nodes must be completed on time according to preparation, preheating, planing, rounding, surfacing, repair layer, wear layer, pattern layer and trimming to meet short construction period. . (2) Tools and welding materials required for construction Before construction, prepare sufficient welding equipment, lifting tools, grinding tools, cutting tools and cables, etc. according to the project site, and supply the necessary consumables. The welding consumables used in the surfacing process are prepared according to the welding process and are budgeted for ordering. (3) Formulation of welding process The welding process is developed after understanding the material of the extrusion roller after communication with the manufacturer before construction. Different types of transition layer welding materials are required for different roller materials, for different welding positions. Specific parameters such as welding current, arc voltage, and welding speed are given. The automatic planing and welding process is used as much as possible to ensure the quality of the large workpiece such as the squeeze roller and to reduce the labor intensity of the worker. After clarifying the welding materials and welding parameters, select the appropriate preheating and welding interlayer temperature. Preheating and heat preservation are to avoid large welding stress and residual stress caused by excessive temperature difference between the welding area and other areas. The field is usually preheated and insulated by flame heating. Make a welding procedure instruction for each welding personnel on site to avoid quality problems during the welding process. (4) Construction implementation rules Develop detailed construction implementation rules, so that everyone can guide the work content in each node to improve efficiency. For example, the following construction steps: handle the construction procedure → remove the slanting plate → remove the side baffle → remove the roller surface fatigue layer → roll surface full weld repair → install the slanting plate → install the side baffle → clean the site → test machine. The implementation of the above schemes guarantees the progress and quality of our company in the repair site of multiple roller presses. Through the practice test, the construction plan and welding process formulated by our company are reasonable. I hope to continue to optimize in the future work, to get higher efficiency and better quality. 3. Conclusion The welding process of the roller surfacing repair technology is complex and demanding. It requires close coordination and cross-infiltration of basic science and engineering science, and continuous innovation and development according to the actual project. With the continuous development of technology, the online surfacing welding repair technology of the roller press will be continuously upgraded, and the various technologies of the online surfacing repair of the roller press will be fully grasped, and the cement industry in China will be vigorously prosperous. 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figure 2