| The combined-type flying shear is one of the heavy machinery equipments in metallurgy, which is used to shear the moving rolled pieces. The combined-type flying shear is usually installed in rolling line, such as billet rolling mill, steel rolling mill, structural steel and wire rod rolling mill, used to shear the head or tail of rolled pieces or shear them into the specified lengths, its performance has a direct influence on the productivity, rate of acceptability, pass percent of the specified lengths of steel rolling workshop. In recent years, with the development of rolling technology and the diversification of rolling varieties, ranging from low speed, large cross section rolling to high speed, small cross section rolling, the requirements for the flying shear are higher and higher, flying shears of the traditional structure can’t match the rolling line well any longer, which has a big influence on the productivity of steel.In the process of actual production, flying shears are often required to shear both rolled pieces of low speed, large cross section and high speed, small cross section, which is also the characteristics of the combined-type flying shear. The combined-type flying shear combine the properties of the two kinds of flying shears and it has got both the advantages of them. The characteristics of the combined-type flying shear lies in that it can work not only in the crank style but also in the circle style and it has advantages of reliable work, high shearing accuracy and simple structure.The combined-type flying shear installed after finishing mill in a steel plant is set as the researching object in this paper, the structure is researched in detail, its working principles and mechanical design points are analyzed, and the influence of parameters on the equipment performance is analyzed. The flying shear is3D modeled with CATIA, and the motor working style and the motion trail of the shear blade is determined, and mathematical model of the shear zone is established. The kinematics simulation of the shear mechanism is done by ADAMS, then the startup time is got. According to the length adjustment formula L=voto±L1, the largest specified length range of the the flying shear is determined. The feasibility that whether it can shear the specified lengths of400-600mm is analyzed according to the technological requirements and the specified lengths of the flying shear is determined.The crankshaft, the main part of the combined-type flying shear, which influences the dynamic characteristics of a combined-type flying shear most, is selected to take the security feature test. According to statistics, seventy percent of the failure was due to fatigue caused by the crankshaft.The modal analysis is taken on the basis of its statics analysis, and its influence frequency range is determined. The structure of the crankshaft is improved by the structure parameters optimization method, and its dynamic property parameters are modified to meet the working requirements and avoid the resonance, key components for the structure have been improved.Research results show that the structural parameters can meet the actual production requirements, the modeling method and the simulation results are of some value for reference to the deep analysis of shearing process, parameters optimization and design of the same kind of flying shears, which provide a basis for the structure design of the crankshaft from the view of dynamic analysis. |
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