Study On The Stability Of Friction Performance Of Wet Multi-Disc Brakes

Mine explosion-proof trackless rubber-tyred vehicle has been widely recognized and applied in coal mine enterprises due to its stable performance,large load and strong climbing ability.The wet multi-disk brake is also the most widely used brake in trackless rubber tire vehicles because of its good anti-fouling,dustproof ability and greater braking torque.The friction performance of friction disc of wet brake is an important factor affecting the safety of vehicle braking.In the braking process of wet brake,the factors determining the stability of the braking system are mainly determined by the change of braking conditions and the change of fluid inside the brake.In order to study the stability of the friction performance of the wet multi-disc brake,the wet multi-disc brake used in the mine 50 ring 600 P is taken as the research object.The braking torque is determined according to its braking process.Combined with the basic theory of fluid mechanics and fluid-solid coupling,the flow field boundary conditions in the braking process of the wet brake are analyzed theoretically.According to the brake condition,the mechanical analysis of the friction pair of the wet brake is carried out,and the boundary conditions of the structural field are established,and the solution method of the fluid-solid coupling is analyzed and selected.According to the structural parameters of the wet brake,the simplified three-dimensional model of its key components is established by Soliworks and imported into AnsysWorkbench.Based on the boundary conditions established by theoretical analysis,the flow field model and transient structural field model of the wet brake are established respectively.Firstly,the flow field model of the wet brake is obtained by Boolean subtraction operation in the fluid simulation module through the three-dimensional model,and the mesh is divided and the boundary conditions,such as flow velocity,fluid material and viscosity,are applied.Then,the command flow is added to the transient structure module to set the structural material parameters and mesh them,and the boundary conditions,such as rotation torque,pressure and constraint,are imposed.Finally,the fluid module simulation results are imported into the structural field to establish the fluid-solid coupling model.Based on the fluid-solid coupling,the finite element simulation of the temperature field and stress field of the friction pair of the wet brake under different braking pressure,initial braking speed and fluid viscosity is carried out.Also,the change of the safety factor is analyzed.Then,the stability of the friction performance is determined by the position change of the high temperature hot spot and high stress point in the friction pair.Finally,through the bench test,the temperature variation curve of the same point in the braking process under different braking conditions is compared.The maximum error value is calculated,and the effectiveness of the finite element analysis results is determined.Moreover,the deviation between the finite element simulation boundary condition setting and the actual situation is analyzed to provide theoretical basis for subsequent research.Considering that the friction coefficient is an important indicator of friction performance but can not be added to the boundary conditions of the simulation model as a variable by the actual situation,an experiment was designed to study and analyze the variation of the friction coefficient under the continuous braking conditions of long time and high speed.