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Summary of bearing technical transformation of aluminum casting and rolling mill

　　Due to market demand and competition, the requirements for finished aluminum foil are becoming higher and higher, especially in the extremely thin state of double zero foil, aluminum foil should have good formability, less metallurgical defects, small anisotropy, high strength, good ductility, uniform thickness, good flatness and other requirements. The quality of cast rolled aluminum sheet will directly affect the important indicators of aluminum foil.

　　At present, four row tapered or double row tapered roller bearings are used as radial support and axial positioning by domestic casting and rolling mill manufacturers. Although this type of bearing can bear axial force and radial load in two directions at the same time, it also has good bearing performance. It can be said that the design requirements fully meet the type selection requirements, but there are some disadvantages in the actual use process, as follows.

　　1. There are many components with poor interchangeability and cumbersome assembly requirements. In particular, the four row tapered roller bearing comprises a middle outer ring, two side outer rings, a middle spacer, two side spacers, four row rolling elements, two inner rings and a cage. And each part has a special number, and the installation sequence shall not be reversed.

　　2. It cannot be separated after the roll diameter is installed. Although the bearing is separable, due to assembly and coordination restrictions, the bearing cannot realize the separation function of inner and outer rings after installation. In fact, it is a set of non separable bearings, which makes it impossible to directly maintain and clean the box and check the wear condition of the internal raceway. It may even occur that the bearing will not be removed for inspection until there is abnormal noise during operation or the plate type tolerance is seriously out of tolerance, However, at this time, the bearing has suffered from serious peeling defects or edge fracture, and the bearing parts are not interchangeable or spare parts, so they can only be scrapped as a whole.

　　3. The clearance between the inner diameter and the shaft diameter is matched. Even for the cast rolling mill with a very slow speed, the wear of its roll diameter (the roll diameter at the bearing installation) has exceeded the normal matching size when the roll surface diameter is less than 30%. The larger matching clearance caused by the roll diameter wear and the irregularity of the roll diameter surface directly affect the plate shape tolerance.

　　As a typical rolling mill roll diameter bearing, the four row cylindrical roller bearing or the double row cylindrical roller bearing can be separated from each other, with high precision and position exchange. It is very convenient for installation, disassembly and cleaning. In a given installation space, it can provide the maximum radial bearing capacity and has a low friction coefficient. In order to accommodate the maximum number of rolling elements to provide the best radial bearing capacity, the cage of four row cylindrical bearings with an internal diameter of more than 400mm is generally designed as a pin through cage. This cage is composed of two washers of the lateral limit rolling element and a pillar connecting the two washers and passing through the center of the roller. The two ends of the final pillar and the gasket are riveted and fixed by argon arc welding, and the cage has high strength. It can completely avoid the above disadvantages.

　　1. It has few components, high interchangeability and convenient installation.

　　2. It can be separated after being loaded into the roll diameter, and can be maintained and cleaned directly in the box.

　　3. It can be separated after being installed into the roll diameter, and the service conditions of various parts of the bearing can be directly and intuitively inspected.

　　4. The interference fit between the inner diameter and the shaft diameter eliminates the wear of the roll diameter.

　　In addition, the bearing can also be set with inner ring or outer component separately. The bearing can be used continuously only by replacing the inner ring or outer component, avoiding unnecessary replacement of undamaged parts. Because its raceway contact is linear contact, it has the highest bearing performance in the same size series of bearings. And this is what the tapered bearing does not have.

　　In this regard, DMD has carried out the technical transformation of several cast rolling mills, which are in good operation condition, and the maintenance is simplified and in place. The most obvious comparison is that the plate shape tolerance after the technical transformation is reduced by 56% compared with that of the conical bearing, so it is recommended to promote it.