Study On Numerical Simulation Of Pulsed Laser Cleaning On Tire Die

Generally speaking,the mold surface used in the tire curing process for a long time will be attached with a layer of solid organic inorganic pollutants,the main components are silica black oxide and sulfide.These pollutants deposited in the tire pattern dead area have an important impact on the quality of vulcanized tires.Therefore,the tire mold cleaning becomes an indispensable process in the tire manufacturing industry,which will directly affect the quality grade of the tire after molding.The laser cleaning technology on tire mold has the advantages of high efficiency,low cost,low thermal and mechanical load,so it will not damage the mold and no environmental pollution.If the pulsed laser cleaning technology on tire mold can be put into use in practice,it will realize the breakthrough reform of tire mold cleaning technology in China,which will have a far-reaching influence on the tire mold cleaning industry.Using Abaqus,Visual Studio,IVF XE2013 softwares and finite element ideas,the numerical simulation of pulsed laser cleaning on tire mold was carried out.The mold heat transfer model in the process of laser cleaning and three models of finite difference method,namely the explicit computing model,the implicit computing model and the hybrid computing model,were established.The explicit computing model requires the choice of material performance parameters,time step and space step,the implicit computing model and the hybrid computing model are stable under any conditions,but the solving steps are more complex and the calculation amount is larger,however,the approximate solution obtained by the hybrid computing model has the best convergence and the result is more accurate,therefore,the corresponding finite difference method solution model can be selected according to the actual process requirements.The finite element model of pulsed laser cleaning on tire mold was established and the distribution and variation of temperature rise generated by the absorption of laser energy in the tire mold and the energy density of laser light source were obtained.The temperature distribution gradient and the energy density of laser light source distribution gradient exist on the surface and inside the die,heat flux accumulation occurs in the center of die surface,resulting in lower temperature rise in the beginningand end parts than in the middle part,with the advance of time,the node temperature presents a rapid multi-step rising trend,followed by a slow decline,the temperature of the path goes up and then down,the overall temperature,maximum temperature and heating rate of nodes and paths increase with the increase of energy density but decrease with the incerase of scanning speed,the time of node temperature rise and step temperature rise decrease with the increase of scanning speed,the variation of the displacement distribution caused by the absorption of laser energy in the tire mold was obtained,as the cleaning process goes on,the maximum surface displacement gradually increases and there is a distribution gradient,when the displacement reaches the maximum allowable displacement under the laser cleaning parameter,it will remain unchanged,but the range of generation will continue to increase,when the cleaning process is completed,the mold surface enters the stage of thermoelastic strain recovery,as time progresses,the node displacement first remains unchanged,then presents a multi-step increase trend,and finally drops slowly,with the increase of energy density,the overall displacement,maximum displacement and acceleration of the node increase,as the scanning speed increases,the overall and maximum displacement of the node decrease,when the node begins to generate displacement,it gradually moves forward with the increase of scanning speed and the time used in the stepwise increase of displacement also decreases with the increase of scanning velocity,the action time in the thermoelastic strain recovery stage increases gradually.The linear distribution of the maximum surface temperature with the change of energy density and its fitting equation were obtained,the linear distribution of the maximum surface displacement of the tire with the change of energy density and its fitting equation were obtained,when the scanning speed is in the range of 3m/s to 10m/s,the approximate inversely proportional distribution of the maximum temperature on the surface of the tire with the change of the scanning velocity and its fitting equation were obtained.Under the condition of scanning velocity v=5m/s,the cleaning threshold of the energy density for the numerical simulation of pulsed laser cleaning on tire molds is4.58J/cm2 and the damage threshold is 22.72J/cm2,under the condition of energy density φ=20.70J/cm2,the damage threshold of scanning velocity for the numerical simulation of pulsed laser cleaning on tire molds is 4.5657m/s.The energy densityφ=20.70J/cm2 and scanning speed v=5m/s are the reasonable technological parametersof pulsed laser cleaning.The main mechanisms of pulsed laser cleaning on tire mold,namely the thermal vibration effect mechanism of matrix and the ablative effect mechanism,were revealed and the quality evaluation system of pulsed laser cleaning technology on tire mold was proposed.