Deformation Analysis And Optimization Of Wide Ironing Plate

As the key working device of asphalt concrete paver,the ironing plate has an important influence on the pavement quality.Due to the large transverse size of the wide ironing plate,it will produce large static deformation under the action of its own gravity,asphalt mixture resistance and thermal load.In addition,under the action of exciting force,the ironing plate will even produce large dynamic deformation,resulting in uneven vibration of the ironing plate.The working form of the ironing plate reflects on the pavement,and then affects the pavement quality.Therefore,it is of great significance to study the deformation characteristics of wide ironing plate for improving the flatness,precompaction and uniformity of pavement.In this paper,the static deformation and dynamic characteristics of the 12 m mechanical broadening ironing plate are studied deeply,and corresponding measures are taken to optimize the structure of the wide ironing plate.The main research contents are as follows:1.The simulation model of 12 m wide ironing plate was established to analyze the longitudinal deformation of the ironing plate in different bracing rod states.The results show that the longitudinal deformation of ironing plate is reduced by only 2.5% under the action of struts,and the inhibition effect is not obvious.The lengthened section of 1.5m is the weakest point of longitudinal stiffness.2.The response surface method was adopted to analyze the influence relationship between the structural size of the box in the weak section and its mass and maximum longitudinal deformation,and to complete the size optimization design based on the binocular standard.The results show that the longitudinal stiffness of the box can be effectively improved by increasing the diaphragm in an appropriate range.After optimization,the maximum longitudinal deformation of the ironing plate is reduced by 28.71% and the quality is reduced by 2.12%.3.Vertical static deformation and thermal-static coupling deformation of wide ironing plate were analyzed and technical improvements were made,and the correctness of the simulation was verified through thermal deformation tests.The influence of different strut states on the vertical static deformation and thermal-static coupling deformation of the ironing plate is analyzed.The simulation results show that the three strut states can effectively restrain the vertical static deformation,but the effect on the thermal deformation is limited.And the hot deformation of the ironing plate presents an upper arch shape along the length distribution.The experimental results show that the actual thermal deformation value is close to the simulation value,and the distribution law is consistent with the simulation value.4.Analyzing the thermal deformation of each section of the box of the ironing plate,it is concluded that the box presents the characteristics of trapezoidal upwarping after deformation.The thermal deformation was compensated by improving the structure shape,and the corresponding reserved thermal expansion Angle was calculated.Then the relative thermal deformation of the ironing plate under different spreading temperatures is analyzed and the linear correlation between the relative thermal deformation and temperature is obtained.In order to compensate the relative thermal deformation,the pretension force was applied to the telescopic straddle rod device,and the linear relationship between the pretension force and the relative thermal deformation was obtained.Finally,the equivalent linear relationship between the preloading force and the heating temperature is calculated,and the method of setting the preloading force as 7 levels and adjusting the different spreading temperatures(130℃～165℃)to compensate the relative thermal deformation is given.5.The modal comparison analysis of the wide ironing plate before and after the deformation optimization shows that there are six orders of longitudinal and vertical vibration modes of the ironing plate without brace rod before the internal optimization of the working frequency,while the stiffness of the ironing plate box under the condition of three brace rod after the deformation optimization is significantly improved,but the brace rod has more local vibration modes,and the stiffness of the brace rod is the worst at 11.5m.Then,the response surface method was used to optimize the first-order natural frequency and mass of the tie bar.After optimization,the mass of the tie bar was reduced by 7.94%,and the lowest natural frequency was increased to 44.925 Hz.6.The modal verification analysis was carried out on the ironing plate optimized by the support rod,and the analysis showed that the first-order natural frequency of the ironing plate was increased to 25.993 Hz and the second-order natural frequency was increased to 29.37 Hz after modal optimization.Most of the natural frequencies of the ironing plate were out of the working range.