Analysis Of Vibrating Screen About Its Key Technology In Asphalt Mixing Plant

Asphalt mixture mixing equipment is the core equipment of construction machineryfor the asphalt pavement, which is widely used in highway construction in our country. Thevibrating screen is the core equipment in the intermittent asphalt mixing equipment, itsscreening efficiency and production have extremely important influence in the quality offollow-up highway pavement. But by the test of production site, we can find: The efficiencyof the multi-layer linear vibrating screen is far lower than the efficiency of the nationalstandard, the production also can not reach the design value, the problem has been thebottleneck to restrict the quality of pavement construction in our country. The deep reason isthat we lack the in-depth study for the multi-layer linear vibrating screen which is used inasphalt mixture mixing equipment. As the development of the construction technology ofthe asphalt pavement, the gradation demand in the construction of asphalt pavement hasmore and more finer for the control points of aggregate. Multilayer screen has been usedmore and more widely in the asphalt mixing equipment, the kinds of which has beendeveloped from circle vibrating screen with two layers of four stages to linear vibratingscreen with six, seven or even nine layers. At the same time, as the production increasing, thevibrating screen constantly extends length outside, in addition, still continuing extension thewidth and heightening the height.The existing screening theory and design method can’tapply to multi-layer vibrating screen. The design and manufacturer of multi-layer vibratingscreen in our country mainly depends on analog design or introducing the foreign vibratingscreen technology. The system theory and design method of multi-layer vibrating screen hasnot formed practically, which restricted seriously the screening efficiency and workreliability of vibrating screen. The topic selection of this thesis was put forward from thisbackground.In this thesis, we put the multi-layer vibrating screen which is used in the asphalt mixingequipment as research object. Firstly, have the basic of kinematics and static and dynamicssimulation analysis for vibrating screen, which we have tests to validate, and also have thecontrast tests with different vibrating screen used in asphalt mixing equipment in the samescale.The mainly content and progresses are: Carry out the kinematics simulation analysis for vibrating screen in ADAMS, we got thepoints such as: the influence of amplitude applied by the location of exciting force, the law ofvibration characteristics of vibrating screen, the law of lateral wobble and the influence ofamplitude applied by material loading.Set up the finite element model of vibrating screen in ANSYS,and have the staticanalysis and dynamics analysis on it.From the dynamics simulation analysis namely modalanalysis and harmonious response analysis of vibrating screen, we got the idea that the workfrequency of vibrating screen in experiment is far away from resonance frequency, it will notproduce the resonance phenomenon when the vibrating screen is working, the work conditionis stable and the deformation of vibrating screen is not big. From the static analysis forvibrating screen body, we got the cloud picture of stress distribution, and found the largerpoint of vibrating screen stress. And have the stress analysis to screen, we have gotten the ideathat the support points of screen are more,the stress of screen is more smoothie;Adopting thestress of circular arc support is more uniform than other kinds.Use the experiment to validate the law of vibration characteristics of vibrating screen,the law of lateral wobble and the influence of amplitude applied by material loading ofvibrating screen and also validate the change trend of stress of vibrating screen and itsnumerical size. The simulation results are basic agreement with experiment results, provingthat the models set up by ADAMS and ANSYS were correct, which could be for furtheranalysis research.In the contrast tests, we carried out vibration parameters experiments and parking andstarting experiments to compare to vibrating screen prototype. The comparative data results inaccordance with vibration characteristics of vibrating screen; When the exciting way isVibration motor, the time for parking is longer,so it needs the direction braking device. At themoment, the designed value of amplitude which is used in the vibrating screen is low, leadingthe low screening efficiency and production, so the measures to improve the screeningefficiency should be adopted.Aiming at the work materials of vibrating screen are hot material, we have the thermalanalysis by using the ANSYS model, proving that the temperature has much influence in thestrength of vibrating screen.So we must consider the influence of temperature when the strength analysis is carried out for the vibrating screen used in asphalt mixing equipment.Andthen, we optimized the structure of vibrating screen in the ANSYS model, leading to decreasethe mass of screen body and thermal stress, proving the optimization was feasible.Through the integrated research for the vibrating screen of asphalt mixing equipment,we put forward two measures to improve the screening efficiency: increase the vibratingstrength and adopt dual-frequency vibrating technology. We can know from the simulationanalysis and test, when the exciting force increases1.6times, and amplitude is4.02mm, thescreening efficiency reaches the national standard, proving that this measure is feasible.Designed and manufactured a dual-frequency vibrating screen for small scale, carry out thecentroid trajectory simulation and orthogonal test of screening efficiency. The test proved thatadopting dual-frequency vibration screening method can improve the screening efficiencyeffectively.The thesis adopts the method of combining the theoretical analysis simulation analysisand the experimental research, using the commonly used vibrating screen as research object,to have a thoroughly and comprehensive research for a variety of factors which affect thescreening efficiency, production capacity, reliability and service life. The research results ofthis thesis gives a foundation for designing and using vibrating screen which is used inasphalt mixture mixing equipment.The reaearch of the thesis was funded by the item naned “the industrialization researchof efficient asphalt mixing equipment”（2008ZH01-16）which is the special funds planproject for major science and technology innovation in Shaanxi.