非线性液压激振机理及其在成型机上的实验研究

发布时间：2018-02-15 15:13

本文关键词： 砌块成型机液压激振非线性振动支持向量机密实成型　出处：《太原理工大学》2013年博士论文　论文类型：学位论文

【摘要】：砌块成型机是生产砌块的关键设备,其振动密实成型技术决定了砌块质量的高低。我国生产的砌块存在密实度低的问题,导致抗压强度普遍较低,耐久性差。欧美等国的砌块成型技术先进,振动频率可达60Hz-85Hz,台振机加速度达到10g以上,模振机加速度可达20g左右,我国以台振机为主,频率在50Hz-65Hz,加速度一般不超过10g。与欧美等国相比,我国成型机振动系统频率低,加速度小,是导致密实度不高的主要原因。研究和开发具有自主知识产权的能够生产高强砌块的成型机,对打破国外高端成型机的技术垄断,提高我国砌块成型机技术力量具有重要意义。现有的振动密实大多采用偏心式惯性振动,受自身结构的制约,其振动频率很难再提高。本文提出利用液压激振作为振动输出源,结合分段非线性弹性力的振动系统来解决低频、小加速度问题。主要研究内容与结论如下： (1)分析混凝土密实成型影响因素,确定合理的振动参数,以此为设计依据,在分析了几种振动形式的基础上,提出了以两段不对称弹簧组成非线性力的双质体液压高频垂直定向振动系统。研究开发了转轴式高频激振器,并构建了整个液压调频激振系统。 (2)分析激振器-液压缸组成的振动系统激振机理,针对系统参数时变性强的特点,建立基于瞬变流原理的带旋转流体液压振动系统的动力学模型,用有限差分法求得系统的动态特性。由仿真结果得,该液压激振系统的频率和振幅可控可调,在相同的系统压力下,输出激振力比直流液压振动系统大；外负载一定时,对物料加压工况下,振动系统输出激振力随之增大,有利于振动密实。 (3)通过实验测定了弹性元件的载荷-变形曲线,得到了弹性力变化的滞回曲线,拟合了分段多项式的函数表达式。对成型机振动系统受力分析与运动过程分析,建立了具有五段非线性力的带双向间隙的双质体非线性振动模型,并用等价线性化法求得系统一次近似解,可得本文设计的振动系统从结构上保证了振动能量集中作用于模箱而不耗散于系统其他元件；用龙格-库塔法得到系统的数值模拟结果表明,频率70Hz-90Hz系统加速度可达15g以上,且产生混沌振动,实现以确定频率输入获得宽频响应,以低频激励获得高频谐响,大大提高混凝土颗粒的均匀性与密实度。 (4)研制实验样机,搭建模箱工作模态测试系统,通过定阶得到系统模态参数。搭建振动参数采集系统并测取相关参数,分析频率、压力对系统振幅与加速度的影响规律。结合模态参数,实验结果表明砌块成型机在双频(70Hz,80Hz)激励下能产生多种共振同时存在的混沌振动,实现节能宽频振动密实,当在外激频率60Hz-90Hz范围内,系统振动加速度最大峰值达到甚至超过20g,指标超过国标的规定,与仿真结果一致,表明了本文所提出的非线性液压振动系统的正确性与合理性。 (5)以实验所得输入输出数据为依据,采用支持向量机建立成型机实际振动系统整体实验模型。采用中值滤波和卷积滤波处理实验中的异常数据并进行数据光滑。利用5折交叉验证法确定支持向量机核函数最优参数,获得基于离散数据的实验模型；提出改进网格寻优方法并结合交叉验证法搜索核函数最优参数,获得基于时间序列的振动系统实验模型,以实验数据验证了两种模型响应预测的准确性,该实验模型是对理论模型的补充和完善。综上所述,本文的研究工作为开发能够生产高密实度砌块的成型机提供了理论支撑,对振动利用工程的发展以及建筑砌块行业的节能减排具有重要意义。
[Abstract]:The building block forming machine is the key equipment for producing building blocks . The vibration compacting technology determines the quality of the building blocks . The vibration frequency of the building blocks produced in China is low and the durability is poor . The vibration frequency of the building blocks is low and the durability is poor . ( 1 ) Based on the analysis of several vibration modes , a double - mass hydraulic high - frequency vertical directional vibration system consisting of two asymmetric springs is put forward , which is based on the analysis of several vibration modes . The rotating shaft type high frequency vibration exciter is developed and the whole hydraulic frequency modulation excitation system is constructed . ( 2 ) analyzing the exciting mechanism of the vibration system composed of the exciter - hydraulic cylinder , and establishing a dynamic model of the hydraulic vibration system with the rotating fluid based on the principle of the transient flow aiming at the characteristics of strong variability in the system parameters , and obtaining the dynamic characteristics of the system by a finite difference method . ( 3 ) The load - deformation curve of the elastic element is measured by experiments , the hysteretic curve of the elastic force change is obtained , and the function expression of the piecewise polynomial is fitted . By using the equivalent linearization method , a double - mass nonlinear vibration model with two - way gap is established . ( 4 ) The experimental prototype is developed to set up the working modal test system of the mould box , and the system modal parameters are obtained through the orders . The influence of the frequency and the pressure on the amplitude and acceleration of the system is analyzed . According to the modal parameters , the experimental results show that the maximum peak value of the vibration acceleration of the building block reaches even more than 20g when the external excitation frequency is 60 Hz - 90 Hz . The results agree with the simulation results , which indicates the correctness and rationality of the nonlinear hydraulic vibration system proposed in this paper . ( 5 ) Based on the input and output data of the experiment , the support vector machine is used to establish the integral experimental model of the actual vibration system of the forming machine . Using median filtering and convolution filtering to process the abnormal data in the experiment , the experimental model based on the discrete data is obtained . The experimental model of the vibration system based on the time series is obtained by using the 5 - fold cross verification method . The experimental data is used to validate the accuracy of the two models . The experimental model is the complement and perfection of the theoretical model . In conclusion , the research work of this paper provides theoretical support for the development of forming machines which can produce high density blocks , which is of great significance to the development of vibration utilization engineering and the energy saving and emission reduction of building block industry .

【学位授予单位】：太原理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU522.3

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