Backing Bearings For Rolling Machines

The backing bearings used in rolling mills are key components for multi-roller cold rolling machines, and they can also be applied to straightening machines, bending machines, and other equipment. Here is a product description of them: Structural features: The main structural forms are double-row or triple-row cylindrical roller bearings, with options including those with or without integral flanges or retaining rings, full rollers (without cage) or with cages, etc. The outer rings are particularly thick. Backing bearings without flanges or movable edge retaining rings and installed without flanges require the use of thrust washers; backing bearings with flanges (or retaining rings) can simultaneously withstand radial and axial forces. Working principle: The backing bearings are installed in groups on stationary shafts as support rollers. The pressure on the working rollers is transmitted through the intermediate rollers to the support rollers, which are then transmitted to the frame through the saddle system, thereby supporting and transmitting the rolling force, ensuring the stable operation of the rolling mill. Lubrication method: The main lubrication methods are air-oil lubrication and rolling oil lubrication. Air-oil lubrication uses compressed air to form a positive pressure seal to prevent contaminants from entering, and supplies lubricating oil at regular intervals for lubrication and cooling; rolling oil lubrication uses clean rolling oil for lubrication and cooling, and the pressure and cleanliness of the rolling oil are crucial to the bearing life. Assembly points: When installing, precise grouping matching is required. Grouping is based on the H value height. The larger-sized bearings are placed in the middle, and the smaller ones are placed on both sides. The H value error of adjacent backing bearings should be controlled within 0.002mm, and the entire group should be within 0.006mm. At the same time, the arrangement of backing bearings on each column of support rollers should be regularly changed, and the inner ring force area of the bearings should be adjusted regularly during assembly to ensure uniform wear of the inner rings. Performance parameters: Taking SKF's 315268 B backing bearing as an example, its bore diameter is 70mm, the outer diameter is 160mm, the basic rated dynamic load is 358kN, the basic rated static load is 585kN, the tolerance grade is P4, it has ultra-precision quality, can achieve runout tolerance, and the cross-sectional height tolerance is strict, and can withstand high loads.

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Product Introduction

I. Product Core Positioning
The backing bearings for rolling mills are the core load-bearing components of multi-roller cold rolling machines (12-roller, 20-roller, etc.) and high-precision straightening machines, bending machines, etc. They are specially designed for cluster-type roller systems. Through grouped arrangement, they form a supporting roller system, evenly transferring the rolling force from the working rollers to the frame, directly determining the rigidity of the rolling mill and the rolling accuracy of the strip (such as thickness tolerance, surface quality). Their manufacturing accuracy needs to reach P4 level or above. For some specifications, the radial runout can be controlled within 0.002mm, and they are the key basic components for achieving high-precision strip rolling of stainless steel, silicon steel, and non-ferrous metals.
II. Structural Design and Core Characteristics
(1) Structural Form
Based on double-row or triple-row cylindrical roller bearings, they are classified into three mainstream types according to design differences:
No outer ring flange type: Relying on the movement of the inner ring flange to guide the rolling elements, using a comb-shaped cage, without sealing design, suitable for free circulation lubrication of the rolling mill emulsion;
Outer ring three flange type: Double-row structure combined with brass cages, can be configured with sealed or non-sealed versions according to the lubrication method, compatible with various lubrication systems;
Full-load double-row type: Both the inner and outer rings have middle flanges, without sealing design, suitable for lubrication with emulsion under high load scenarios.
All types adopt a thickened outer ring design, with a grinding allowance of more than 3mm, the hardness of the outer ring reaches 59-61HRC, and a gradient hardness curve forms from outside to inside, combining impact resistance and wear resistance.
(2) Key Design Optimization
Material Upgrade: The rings use TIMKEN 3311 and other high-purity bearing steels, with harmful elements (oxygen, phosphorus, etc.) content far lower than domestic standards, reducing thermal treatment defects and performance fluctuations; The cages use manganese brass instead of lead brass, improving hardness and wear resistance, solving the problems of slagging and hole deformation;
Stress Optimization: The outer ring adopts large arc surface transition chamfering, the rolling element design has contact convexity, reducing stress concentration and friction abrasion; The movable spacer is optimized in angle design, balancing lubrication guidance and collision prevention functions;
Precision Control: Strictly control parameters such as radial clearance, wall thickness difference, and rolling element diameter difference, the difference in the height (H value) of the same group of bearings is ≤ 0.005mm, and the size error of the inner and outer rings is < 5μm.
III. Performance Advantages
High Bearing Capacity: The full-roller structure and thickened outer ring design can withstand extremely large radial loads. Some models (such as SKF BCZ-0525 B) have a basic rated dynamic load of up to 270kN and static load of 345kN, suitable for high-speed rolling scenarios (up to 1000m/min);
Super Precision Operation: Through group tolerance control (3-7 groups, each group tolerance 3-5μm) and 100% factory inspection, ensuring uniform force on the roller system, reducing roller deflection and deformation;
Long-Lasting Durability: The outer ring can be re-ground multiple times while maintaining hardness, combined with scientific maintenance, it can significantly extend the service life; The new combined sealing structure improves dust resistance, reducing pollutant erosion;
Flexibility in Adaptability: Compatible with air-oil lubrication, circulating lubricating oil lubrication, and rolling emulsion lubrication, and can be customized according to the type of rolling mill (mining oil for small and medium-sized ones, emulsion for large and high-speed ones).

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