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How should roller bearings be maintained?
Aluminum rolling mill rolls and roll bearings are important parts of the rolling mill. In rolling production, the roll is in direct contact with the rolling metal, resulting in plastic deformation of the metal. Therefore, the roll is the main deformation tool of the rolling mill, and the roll is supported by various bearings. The quality and service life of rolls and roll bearings are directly related to the product quality, production efficiency and production cost of the rolling mill. Therefore, the maintenance of the roller bearing is particularly important. Working characteristics of 1. roll bearings Roll bearings are used to support rolls. Compared with general bearings, roll bearings have the following characteristics: 1. Strong pressure bearing capacity. Due to the limitation of the overall size of the bearing seat, it cannot be larger than the smaller diameter of the roller body, and the length of the roll neck is shorter, and the unit load on the bearing is larger. The unit pressure of the general roller bearing is as high as 2000 ~ 4800Mpa, which is 2~5 times that of the ordinary bearing, and the PV value (the product of the unit pressure and the linear velocity) is 3~20 times that of the ordinary bearing. 2. The speed difference is large. The operating speed of different rolling mills varies greatly. For example, the export speed of modern six-stand cold rolling mill has reached 42 m/s, the export speed of high-speed wire rod mill has reached 100 m/s, and some low-speed rolling
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Take you to understand the material of the roll and common problems
The roll is a tool for plastic deformation of (rolling) metal, and it is an important vulnerable part that determines the efficiency of the mill and the quality of the rolled material. Roll is an important part of the rolling mill in the rolling mill. It uses the pressure generated by a pair or a group of rolls to roll steel. It is mainly affected by the rolling process of dynamic and static load, wear and temperature changes. So, what are the characteristics and common problems of the roll? Let's look at it together.
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The following is a brief talk about roll maintenance and production standards
The following is a brief talk about roll maintenance and production standards: correctly judge the number of uses. The grinding interval of high-speed steel rolls depends on the oxide film on the roll surface and the maintenance of roughness after each shutdown. Under normal circumstances, the front frame can be used 3~7 times, the rear frame can be used 2~4 times, and the high-speed steel roll can even be used more than 10 times.
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What if the roll breaks?
What if the roll breaks? In the actual application process, the roll break is a common thing. So, do you know the specific reason why the roller breaks? Today, I will give you a detailed introduction.
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A Brief History of the Development of Rolls
The variety and manufacturing process of rolls are constantly developing with the progress of metallurgical technology and the evolution of rolling equipment. Low strength gray cast iron rolls were used in medieval rolling of soft non-ferrous metals. In the middle of the 18th century, Britain mastered the production technology of chilled cast iron rolls for rolling steel plates. In the second half of the 19th century, the progress of European steelmaking technology required the rolling of larger tonnage ingots, and the strength of gray cast iron or chilled cast iron rolls could not meet the requirements. Carbon content of 0.4%~ 0.6% ordinary cast steel roll was born accordingly. The emergence of heavy-duty forging equipment has further improved the strength and toughness of forging rolls with this composition. The use of alloying elements and the introduction of heat treatment in the early 20th century significantly improved the wear resistance and toughness of cast and forged steel hot and cold rolls. The addition of molybdenum to cast iron rolls for hot-rolled strip improves the surface quality of the rolled material. The core strength of the casting roll is obviously improved by the compound pouring with flushing method.
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Performance requirements
Generally, the main requirements for rough rolls are strength and thermal crack resistance. The working roll weight of the small 20-roll mill is only about 100 grams, while the support roll weight of the wide and heavy plate mill has exceeded 200 tons. When selecting the roll, first of all, according to the basic strength requirements of the rolling mill to the roll, select the main material for safe bearing (various levels of cast iron, cast steel or forged steel, etc.).
Roll selection
The commonly used roll materials and uses are shown in the table. The performance and quality of a roll generally depend on its chemical composition and manufacturing method, and can be evaluated by its structure, physical and mechanical properties, and the type of residual stress existing in the roll (see roll inspection). The effect of the roll in the mill depends not only on the material of the roll and its metallurgical quality, but also on the conditions of use, roll design, operation and maintenance. The conditions of use of rolls of different types of mills are very different, and the factors that cause the difference are:(1) the conditions of the mill. Such as mill type, mill and roll design, pass design, water cooling conditions and bearing types, etc.;(2) rolling conditions such as rolling material varieties, specifications and their deformation resistance, pressure system and temperature system, output requirements and operation, etc.;(3) product quality and surface quality requirements.