Study On Contact Dynamics And Damage Mechanism Of Mining Round Link Chains Transmission

Round link chain transmission mechanism have extensive application in mine, metallurgy,lifting, hoisting, shipping, aerospace, food processing and other industries, especially applied inmine machinery, which are easily taken place accidents in the harsh conditions, not only affectsthe production efficiency of the resulting economic losses, and may endanger life safety. Atpresent, domestic and foreign scholars on the round link chains transmission mechanism of thestructure were made relatively thorough research, but for round link chain transmissing contactdynamics research further. Based on contact nonlinear dynamics, collision theory, vibrationtheory and fatigue damage theory, through laboratory experiments, numerical simulation methodis adopted, the round link chains, round link chain and sprocket meshing dynamics in the processof the chain and the sprocket meshing, due to the collision and damage problem is studied.The main research results are as follows:1) Through the establishment of round link chain structural equations, and based on themechanical analysis of chains, using the Hertz contact theory, deduced from the two link chainsarm of the contact to the surface contact, the contact surface is elliptical, and can be calculatedthe contact area and pressure stress, establish chain nest space structure mathematical equations,combined sprocket structure equation, deduced from the chain and the sprocket space contactmodel, and the establishment of a chain sprocket contact structure equation; according to thechain and the sprocket meshing force analysis, and considering the friction factors to constructcomplex chains winding sprocket dynamics finite element model, and the establishment of thechain and the sprocket wheel in meshing angle range with deflection angle dynamics equation.2) Through the use of finite element method, to solve the nonlinear contact problem, the useof finite element dynamic analysis software ANSYS/LS-DYNA, simulation is carried in theprocess of round link chains collision, round link chain and sprocket meshing, the results showthat the link in the state of instantaneous starting or chain getting stuck, stress mainly focus onthe chains between contact positions (circular) and the transitional position between the straightarm and curved arm, instantaneous stress concentration is also great,repeated collision mustproduce fatigue and fracture. In the process of round link chain and sprocket meshing, the modelthat a sprocket pitch larger than the pitch of the chain is established, stress distribution on thechains driven by the teeth are shown, but on a chain stress is much greater than the sprockettooth stress, link chain stress fluctuations also displays stage characteristics. 3) Through analyzing the chain transmission mechanism environment, the damage factorsare: wear and corrosion, fatigue and fracture, vibration and shock. Usually the broken chainaccident reason is the result of the action of these factors simutaneously. Chain and sprockettransmissing process, mainly for the impact and fatigue, by means of ANSYS software, theround link chain and sprocket for instant impact simulation analysis, the results show that, in amoment of impact caused by stress concentration, the life of round link chain and link chain ofconnector can be used to predict by the fatigue cumulative damage theory. According to theworking process of round link chain injury presents empirical protective measures and means.4) The use of laboratory large style integrated equipment, using strain sensor and dataacquisition electronics, established a chain transmission dynamic test system, through the roundlink chain and sprocket meshing transmission process monitoring and strain data acquisitionresults of the analysis can be drawn: in the transmission system of the chain sprockettransmissing end, winding process by sprocket polygon effect, stress curve demonstratedsignificant growth phases, when engagement ended, stress remain unchanged; the sprocket andchain in the process of engagement, within the wrap angle of meshing sprocket teeth of differentstress increase, and chain detachment, stress values remain unchanged, and phasic stress canproduce once contacting, so go round and begin again. Which is matched with the simulatedresults, the instant meshing of the chain and the sprocket is an important reason to chains toproduce injury.5) Test result reveals that the link chain meshes into the sprocket moment, will producegreat stress, mainly due to the instantaneous impact, and the chains are subjected to stress andwear; chains and the polygon effect of the sprocket within the meshing angles, will producefatigue wear, chains and sprocket teeth part are usually the stress that is not particularly large,but in the long-term working conditions, will evolve into fatigue wear, eventually lead to chainsbroken.In this paper, the system of round link chain transmission is analyzed, for the chaintransmission mechanism in a variety of equipment and the working conditions of the applicationto provide a reliable theoretical analysis, numerical simulation and experimental methods, toreduce the damage of chain transmissing has the actual significance.