Dynamic Analysis Of Impact Vibration Forming Machine With Dynamic Friction

In many developing countries,producing one-time forming production is a traditional and important industry,ranging from indispensable noodles,coal fuel,cartons and other supplies in our daily life to engineering supplies such as cutting and forming machines and heat sink forming machines.However,in the process of finished product forming,there are many factors that affect the quality of the product,such as the size of the external excitation,the excitation frequency,the temperature of the cavity,the melting degree of the material and the smoothness of the cavity,etc,which reduce the quality of the product.Therefore,the dynamic analysis of the working state of the forming machine can not only provide a theoretical basis for the design and optimization of the system mechanism,but also give the parameter interval of the stable operation of the system.In this paper,two kinds of dynamic models of impact vibration molding machine are simplified from a kind of automatic heat sink molding machine with material detection device.The influence of the change of external excitation frequency on the topological structure of system motion under the action of improved LuGre dynamic friction modle and Dankowicz dynamic friction is considered respectively.The collision,flutter and viscosity of system motion in the process of changing excitation frequency are further analyzed,and the parameter interval of system stable operation is analyzed.The main contents are as follows:(1)According to the dynamic model of shock vibration shaper with restoring force linearization,under the effect of improved LuGre dynamic friction model,the topological structure of the system motion mainly occurs periodic doubling bifurcation,periodic inverse doubling bifurcation,edging bifurcation and saddle junction bifurcation in the process of excitation frequency change between single period and multi-period,period and chaos.In the whole process of change,the system will have one or more collisions for each external exciting force and each collision will be accompanied by chatter phenomenon.Under the action of Dankowicz dynamic friction model,the main topological structures of the system motion are the sharp-edge bifurcation,saddle junction bifurcation and Hopf bifurcation,which transition between single period and multi-period,period and chaos.In the whole process of change,the system will have one or more collisions for each external exciting force,and each collision will be accompanied by quiver phenomenon,and viscous phenomena will also occur during the chaotic motion.Under the action of two kinds of friction models,when the system excitation frequency is at low frequency(ω∈[1,3]),the system motion topology changes frequently and the cycle window is small;when the system excitation frequency is at medium frequency(ω∈[3.64,4.596]),the system motion is in stable cycle one motion;when the system excitation frequency is at high frequency(ω>4.596),the system motion is mainly chaotic.(2)Aiming at the dynamic model of shock vibration shaper with restoring force nonlinearization,under the action of improved LuGre dynamic friction model,the topology structure of the system motion mainly occurs periodic doubling bifurcation,periodic inverse doubling bifurcation,edge-crossing bifurcation,saddle-junction bifurcation and Hopf bifurcation in the process of excitation frequency change between single period and multi-period,period and chaos.In the whole process of change,one or more collisions will occur for each time the system is affected by an external exciting force,and each collision is accompanied by quiver phenomenon,and the system has a viscous phenomenon when the system excitation frequency is at 1-1.1.Under the Dankowicz dynamic friction model,the topological structure of the system motion is mainly cyclic inverse doubling bifurcations,edge-crossing bifurcations and saddle-knot bifurcations,which transition between single period and multi-period,period and chaos.In the whole process of change,the system will have one or more collisions for each external exciting force and each collision will be accompanied by chatter phenomenon.Under the action of two kinds of friction models,when the system excitation frequency is at low frequency(ω∈[1,3]),the system motion topology changes frequently and the cycle window is small;when the system excitation frequency is at medium frequency(ω∈[3.725,4.476]),the system motion is in stable cycle one motion;when the system excitation frequency is at high frequency(ω>4.476),the system motion is mainly chaotic.