Industry Heavy Metal
Current views on the detailed design of heavily loaded components for rolling mills by Vladlen Mazur, Viktor Artyukh, Gennady Artyukh and Maryna Takadzhi.
Ukraine is a developing European country and part of the CIS (Commonwealth of Independent States). Its iron and steel, and heavy engineering industries provide equipment and spare parts for steel working around the world. They are key industries for its domestic and external markets, producing finished products for export with a total value of about £9.1 billion, approximately 45.3% of total Ukrainian exports.
The most promising area for increasing the production of steel making equipment appears to be rolling mills. They carry heavy loading, which would have to be raised to improve productivity. It is important that parts are modified to avoid overloads, accidental breakdowns and downtime of expensive equipment.
In the design, modernisation and repair of different types of mechanical equipment, it is often wrongly stated that ‘The larger the part is, the stronger it should be’. Using the results of theoretical and experimental research, stress analysis, technical and scientific developments of different pieces of metallurgical equipment, industrial commissioning and so on, we suggest using new approaches to better understand the relationships between strength, durability and the dimensions of such parts. Any heavy loaded machine, its assemblies and subassemblies must be considered as a whole set of elastic systems if there is to be no permanent deformation. These systems
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interact with other systems generating new load patterns. New technical procedures are provided to take account of higher loads and forces where strength and stiffness of equipment are crucial. These loads may be classified according to their function:
1. Necessary loadings arising from operations, eg material rolling (see figure 1), transport (see figure 3), and flattening rolled products. Engineers can calculate these loads using the well- known proven formulas.
2. Unnecessary additional loads arise where the equipment is not optimised for the loading. Such loads act in addition to the functional loads and their elimination would improve the efficiency of all types of equipment. Their accurate determination must be performed individually for every load case or by experimental testing. For example, the main types can be illustrated using the hot thick strip four high working stand shown in figure 1:
• Additional impact loads (forces). Examples are direct blows of rolled metal 1 against rolling rolls (RR) 2 during metal biting, impacts of chocks 3 and 4 of RR 2 and backup rolls (BR) 5 against frames 6;
• Additional loads from incorrect positioning of contact surfaces on rolling stand parts. The main reasons are: gaps, misalignments and poor
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