| Two-component polyurethane crack-seal machine is a new type of cement pavement grouting equipment.Polyurethane without heating is selected as the crack-seal material,which has fast construction and good grouting effect.In this paper,some key technologies of the new crack-seal machine are studied in detail,which has great application value for popularizing the two-component polyurethane crack-seal machine.Firstly,the structural characteristics of cement pavement joints are introduced,the performances of various kinds of joint materials are compared and analyzed,the unique advantages of two-component polyurethane materials are introduced,and the filling process and construction points are explained in detail.Then the overall structure of the crack-seal machine is designed,and the advantages and disadvantages of various mixing mixers are compared and analyzed.SK static mixer is selected as the polyurethane mixing element.Flat sector nozzle was selected and the relationship between nozzle structure parameters was deduced.By comparing and analyzing the metering,proportioning and cleaning schemes of polyurethane,the hydraulic schematic diagram of the crack-seal machine is established,and the calculation and selection of other core components are carried out.After that,FLUENT simulation analysis is carried out on SK static mixer and flat fan nozzle,which are the core components of the crack-seal system.The velocity,pressure and volume fraction of polyurethane in the mixer were studied.The mixing effect of the mixer was evaluated by value of volume fraction nonuniformity coefficient of cross-section polyurethane.The effects of inlet velocity,blade length-diameter ratio and blade thickness on mixing effect were investigated.The optimum length-diameter ratio and blade thickness were1.5-2.0 and 1.0-1.5 mm respectively.The variation of velocity,pressure and volume fraction of the flow field inside and outside the nozzle was analyzed.The influence of inlet velocity and grooving angle on the injection effect was explored.The smaller the inlet velocity was,the better the grouting effect was.When the inlet velocity was too small,polyurethane gathered at the nozzle outlet,resulting in dropping phenomenon.The inlet velocity should be controlled above 0.3m/s.Thebigger the grooving angle is,the better the grouting is.Aggregation also occurs when the angle is too large.The optimum grooving angle is 75 ~90,at which time the nozzle injection length can be increased to 25 mm.Finally,the AMESim simulation of the hydraulic system of the crack-seal machine is carried out to study the flow,pressure and motor torque ripple of the system,and the output flow determines the system fluctuation frequency.The larger the accumulator volume,the smaller the fluctuation amplitude of pressure and flow,but the longer the system reaches stability. |
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