基于加压变幅的汽车起重机落幅操控性与起幅抗冲击性能研究

发布时间：2017-12-27 23:02

本文关键词：基于加压变幅的汽车起重机落幅操控性与起幅抗冲击性能研究　出处：《长安大学》2017年博士论文　论文类型：学位论文

【摘要】：汽车起重机是工程建设施工中应用最广泛的工程机械之一,主要包括卷扬、伸缩、变幅和回转四个动作。国内汽车起重机在吊装作业时不允许进行伸缩动作,因此变幅成为了唯一可以改变作业半径的动作,变幅系统的性能直接影响汽车起重机的作业效率和安全,因此对变幅系统进行研究具有重要的现实意义和工程价值。变幅系统根据落幅方式可分为重力变幅系统和动力变幅系统。重力变幅系统在变幅大角度或轻载时,落幅角速度过慢,作业效率低;而在变幅小角度或重载时,落幅角速度过快,易引发安全事故。动力变幅系统受到负载波动的影响较大,落幅平稳性差,降低了作业效率和安全。另外,采用LUDV系统的汽车起重机在进行起幅落钩组合动作时,易出现起幅冲击的现象,降低了作业效率和安全。为了提高汽车起重机的落幅操控性和组合动作的抗冲击性能,提高作业效率和安全,论文的主要研究工作如下:(1)针对传统变幅系统落幅操控性存在的不足,提出了一种加压变幅方法。建立了加压变幅系统的数学模型,获得变幅液压系统的负载特性以及落幅角速度的变化规律。提出了落幅操控性的评价方法,分析了变幅液压系统主要元件和参数对落幅操控性的影响。利用MATLAB软件进行数值分析,结果表明加压变幅系统在各工况的落幅均匀性均明显提高。利用AMESim软件进行变幅液压系统仿真,结果表明加压变幅系统在没有明显降低落幅平稳性的前提下,提高了落幅均匀性。(2)针对变幅小角度或重载工况下落幅角速度较大的问题,研究了变幅平衡阀的流量饱和特性,得到了变幅平衡阀对落幅角速度的影响规律。数值仿真和台架试验结果表明,控制压力越大,流量饱和点越大,达到流量饱和的压差先减小,然后逐渐增大;过流面积越小,流量饱和点越小,达到饱和流量的压差越大;在阀芯行程相同的前提下,流量饱和点随着弹簧刚度的降低而降低,达到流量饱和的压差也随之降低。通过改进变幅平衡阀的结构,限制了落幅角速度,提高了汽车起重机的落幅均匀性。(3)提出了一种变幅平衡阀特性参数的数值算法。利用变幅平衡阀的三维模型,按照一定的规律选择不同的阀芯位移间隔,计算各位移的离散阀口参数,然后采用三次样条差值法得到整个阀芯位移所对应的连续阀口参数。将参数用于变幅平衡阀流量饱和特性研究,仿真和实验结果基本一致,验证了数值算法的可行性。(4)研究了组合动作下汽车起重机的起幅抗冲击性能。提出了抗冲击性能的评价方法,分析了LUDV系统在组合动作下的响应特性和起幅冲击产生的原因,提出了改善起幅流量突变的技术措施,AMESim仿真结果表明,技术措施可以有效地减弱起幅流量突变,抑制起幅冲击,提高汽车起重机在组合动作下的起幅抗冲击性能。(5)对加压变幅系统的落幅操控性和组合动作下的起幅抗冲击性能进行了试验研究。落幅均匀性试验结果显示,加压变幅系统存在流量峰值,落幅角速度存在明显的减小趋势,表明加压变幅系统可以对变幅小角度或重载工况的落幅角速度进行限制,提高汽车起重机的落幅均匀性。落幅平稳性试验结果显示,各工况下系统压力和流量平稳,变幅角度的波动范围很小,表明加压变幅系统具有良好的落幅平稳性。对改进前后的汽车起重机进行了起幅落钩组合动作试验。试验结果显示,改进后汽车起重机的起幅流量突变显著改善,垂直方向的振动加速度明显减小,起幅抗冲击性能得到提高。
[Abstract]:The automobile crane is one of the most widely used engineering machinery in the construction of engineering, which mainly includes four movements such as rolling, expansion, amplitude variation and rotation. The domestic automobile crane does not allow telescopic action in the lifting operation, so the amplitude becomes the only can change the operating radius of action, operation efficiency and safety directly affects the vehicle crane luffing system, so the research has important practical significance and engineering value of luffing system. The variable amplitude system can be divided into the gravity variable amplitude system and the dynamic amplitude system according to the way of the falling amplitude. The gravity luffing system in luffing angle or light load, the argument falls too slow, low working efficiency; and in the range of small angle or overload, phase fall too fast, easy to cause safety accidents. The power variable amplitude system is greatly influenced by the load fluctuation, and the stability of the falling amplitude is poor, and the operation efficiency and safety are reduced. In addition, when the truck crane using the LUDV system carries out the combination action of the hooked hook, it is easy to appear the phenomenon of the amplitude impact, which reduces the efficiency and safety of the operation. In order to improve the impact control performance of the truck crane and the impact performance of the combined action and improve the efficiency and safety, the main research work is as follows: (1) aiming at the shortcomings of the traditional amplitude control system, a pressure amplitude adjustment method is proposed. The establishment of the mathematical model of pressurized luffing system, obtain the load characteristics of luffing hydraulic system as well as the variation of the speed of falling angle. The evaluation method of the maneuverability of the falling amplitude is put forward, and the influence of the main components and parameters of the variable amplitude hydraulic system on the control of the falling amplitude is analyzed. The numerical analysis is carried out by MATLAB software, and the results show that the uniformity of the falling amplitude of the pressure variable amplitude system is obviously improved. The simulation of luffing hydraulic system is carried out by using AMESim software. The results show that the pressure swing system improves the uniformity of falling amplitude without reducing the stability of falling amplitude significantly. (2) according to the amplitude of small angle or heavy load drop velocity argument, flow saturation on the amplitude of the balance valve, the influence of amplitude on falling velocity amplitude balance valve. Numerical simulation and bench test results show that the control pressure is, the greater flow reached saturation point, flow saturation pressure decreases first, then increases gradually; the flow area is smaller, the smaller flow saturation point, saturated flow pressure is large; in the same spool stroke on the premise of flow the saturation point decreased with spring stiffness decreases, reaching saturated flow pressure is reduced. Through the improvement of the structure variation of the balance valve, limit the fall speed improves the argument, amplitude uniformity fall of truck crane. (3) a numerical algorithm for the characteristic parameters of the variable amplitude balancing valve is proposed. Based on the three-dimensional model of the luffing balance valve, the different valve spool displacement intervals are selected according to certain rules, the discrete valve port parameters of each displacement are calculated, and then the continuous valve port parameters corresponding to the displacement of the spool are obtained by the three spline difference method. The parameters are used to study the flow saturation characteristic of the variable amplitude balance valve. The simulation and experimental results are basically consistent, and the feasibility of the numerical algorithm is verified. (4) the anti impact performance of the crane is studied under the combined action. Put forward the evaluation method of anti shock performance, analysis of the causes of the response of the LUDV system in the combination of action and shock generated, put forward to improve the picture flow technique, AMESim simulation results show that the method can effectively decrease the picture flow mutation, inhibit shock, improve the automobile crane in the picture under the combined action of anti shock performance. (5) the amplitude control of the pressurized variable amplitude system and the performance of the shock resistance under the combined action were tested. Drop amplitude uniformity test results show that the existence of peak flow pressure drop angle velocity of the luffing system, significantly decreasing trend, that pressure can speed argument falls to the luffing system of small amplitude angle or heavy load conditions are restricted, improve the uniformity of amplitude fall of truck crane. The results of falling stability test show that under different working conditions, the system pressure and flow rate are stable, and the fluctuation range of amplitude angle is very small, which indicates that the pressure swing system has good stability of falling amplitude. The combined action test of the hooked hook was carried out before and after the improvement of the truck crane. The test results show that the amplitude change of the crane crane's flow is significantly improved, the vertical acceleration is obviously reduced, and the amplitude impact resistance is improved.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TH213.6

【参考文献】