基于混合分布的数控刀架载荷谱编制方法及应用研究
发布时间：2019-01-21 19:54
【摘要】：由于缺少数控机床使用阶段的载荷数据,造成产品在设计阶段时无法准确的评估出其真实的使用寿命;同时在可靠性试验阶段,由于缺少程序加载谱,造成无法确定与实际工况相符的加载系数。针对上述问题,本文以数控机床的关键功能部件数控刀架为研究对象,开展数控刀架载荷谱的编制方法及应用研究。为了能够获取数控机床真实的载荷工况,需要深入机床用户现场采集机床工艺数据,并根据现场的工艺数据,开展切削试验获取切削载荷。由于数控机床加工工况复杂,外界干扰源较多等因素,造成切削载荷数据统计分析处理困难。针对上述问题,本文主要开展典型工艺参数的确定、载荷信号的降噪处理、载荷的参数外推、载荷谱的编制及应用等关键技术的研究,具体研究内容如下:1)根据现场采集的机床工艺数据,确定了36组典型工艺参数及对应的使用比例;搭建了数控车床切削力采集装置,确定了切削采样频率和切削试验步骤;最后开展切削试验,获取了典型工艺参数下的数控刀架载荷信号。2)根据数控车床的加工特点和实测的数控刀架载荷信号,分析出实验室采集的载荷信号中存在着大量的噪声和奇异点,同时存在着噪声识别困难的问题;针对上述问题,本文提出改进的小波相邻系数法,实现了数控刀架载荷信号的降噪处理。3)根据数控刀架的载荷特性,提出基于混合分布的载荷参数外推模型。利用蒙特卡洛马尔可夫链法将36组载荷信号扩展到指定长度,并通过雨流计数法合并了36组载荷均幅值频次矩阵。根据合并后载荷均幅值的拟合特性,提出采用混合威布尔分布模型拟合载荷均值,威布尔分布模型拟合载荷幅值;针对混合威布尔分布模型中基函数个数选择困难的问题,提出相邻似然比法选择最优基函数的个数;在分析载荷均幅值相关性的基础上,应用Copula函数建立了载荷均幅值的联合分布模型。最后根据载荷外推累计频次和联合分布模型,编制了切削力矩恒定工况下的数控刀架载荷谱。4)在分析可靠性试验基本流程的基础上,制定了基于载荷谱的数控刀架可靠性试验方案;主要包括:可靠性试验时间的确定、试验最小样本数的求解以及试验加载方案的确定。最后,结合研究内容,本文还应用MATLAB设计了载荷谱生成器软件。
[Abstract]:Due to the lack of load data in the use phase of NC machine tools, it is impossible to accurately evaluate the true service life of the products in the design phase. At the same time, in the reliability test stage, due to the lack of program loading spectrum, it is impossible to determine the loading coefficient which is consistent with the actual working conditions. Aiming at the above problems, this paper takes the CNC tool holder as the research object, and develops the method and application of the load spectrum of the NC tool holder. In order to obtain the real load condition of the NC machine tool, it is necessary to collect the machine tool process data from the machine tool users and carry out cutting tests to obtain the cutting load according to the field process data. Because of complex working conditions and many external interference sources, it is difficult to analyze and process the cutting load data. In order to solve the above problems, this paper mainly studies the key technologies, such as the determination of typical process parameters, the noise reduction of load signals, the extrapolation of load parameters, the compilation and application of load spectrum, etc. The specific research contents are as follows: 1) according to the machine tool process data collected on the spot, 36 groups of typical process parameters and corresponding usage ratio are determined; The cutting force acquisition device of NC lathe is built, and the cutting sampling frequency and cutting test steps are determined. Finally, the cutting test is carried out, and the load signal of NC tool holder under typical technological parameters is obtained. 2) according to the machining characteristics of NC lathe and the measured load signal of NC tool holder, It is found that there are a lot of noises and singularities in the load signals collected in the laboratory, and at the same time, the problem of noise identification is also found. In order to solve the above problems, an improved wavelet adjacent coefficient method is proposed to reduce the noise of the NC tool holder load signal. 3) according to the load characteristics of the NC tool holder, a load parameter extrapolation model based on mixed distribution is proposed. By using Monte Carlo Markov chain method, 36 sets of load signals are extended to a specified length, and 36 sets of load average amplitude frequency matrices are combined by rain flow counting method. According to the fitting characteristic of the average amplitude of combined load, a hybrid Weibull distribution model is proposed to fit the load mean value and Weibull distribution model to fit the load amplitude value. In view of the difficulty of selecting the number of basis functions in the mixed Weibull distribution model, the adjacent likelihood ratio method is proposed to select the number of optimal basis functions. Based on the analysis of the correlation between the average amplitude of the load and the Copula function, the joint distribution model of the average amplitude of the load is established. Finally, according to the cumulative frequency and joint distribution model of load extrapolation, the load spectrum of NC tool holder under constant cutting moment is compiled. 4) based on the analysis of the basic flow of reliability test, The reliability test scheme of NC tool holder based on load spectrum is established. It mainly includes the determination of the reliability test time, the solution of the minimum sample number and the determination of the test loading scheme. Finally, combined with the research content, the software of load spectrum generator is designed by using MATLAB.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG659
本文编号：2412983
[Abstract]:Due to the lack of load data in the use phase of NC machine tools, it is impossible to accurately evaluate the true service life of the products in the design phase. At the same time, in the reliability test stage, due to the lack of program loading spectrum, it is impossible to determine the loading coefficient which is consistent with the actual working conditions. Aiming at the above problems, this paper takes the CNC tool holder as the research object, and develops the method and application of the load spectrum of the NC tool holder. In order to obtain the real load condition of the NC machine tool, it is necessary to collect the machine tool process data from the machine tool users and carry out cutting tests to obtain the cutting load according to the field process data. Because of complex working conditions and many external interference sources, it is difficult to analyze and process the cutting load data. In order to solve the above problems, this paper mainly studies the key technologies, such as the determination of typical process parameters, the noise reduction of load signals, the extrapolation of load parameters, the compilation and application of load spectrum, etc. The specific research contents are as follows: 1) according to the machine tool process data collected on the spot, 36 groups of typical process parameters and corresponding usage ratio are determined; The cutting force acquisition device of NC lathe is built, and the cutting sampling frequency and cutting test steps are determined. Finally, the cutting test is carried out, and the load signal of NC tool holder under typical technological parameters is obtained. 2) according to the machining characteristics of NC lathe and the measured load signal of NC tool holder, It is found that there are a lot of noises and singularities in the load signals collected in the laboratory, and at the same time, the problem of noise identification is also found. In order to solve the above problems, an improved wavelet adjacent coefficient method is proposed to reduce the noise of the NC tool holder load signal. 3) according to the load characteristics of the NC tool holder, a load parameter extrapolation model based on mixed distribution is proposed. By using Monte Carlo Markov chain method, 36 sets of load signals are extended to a specified length, and 36 sets of load average amplitude frequency matrices are combined by rain flow counting method. According to the fitting characteristic of the average amplitude of combined load, a hybrid Weibull distribution model is proposed to fit the load mean value and Weibull distribution model to fit the load amplitude value. In view of the difficulty of selecting the number of basis functions in the mixed Weibull distribution model, the adjacent likelihood ratio method is proposed to select the number of optimal basis functions. Based on the analysis of the correlation between the average amplitude of the load and the Copula function, the joint distribution model of the average amplitude of the load is established. Finally, according to the cumulative frequency and joint distribution model of load extrapolation, the load spectrum of NC tool holder under constant cutting moment is compiled. 4) based on the analysis of the basic flow of reliability test, The reliability test scheme of NC tool holder based on load spectrum is established. It mainly includes the determination of the reliability test time, the solution of the minimum sample number and the determination of the test loading scheme. Finally, combined with the research content, the software of load spectrum generator is designed by using MATLAB.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG659
【相似文献】
相关期刊论文 前10条
1 甘成君;;可调式数控刀架钻夹的设计与使用[J];制造技术与机床;2011年02期
2 蔡子远;;探讨数控刀架类故障诊断与维修的方法[J];硅谷;2011年08期
3 张立敏;申桂香;张英芝;王晓峰;郑珊;孟书;;小样本数控刀架的可靠性模型[J];吉林大学学报(工学版);2012年S1期
4 侯朱伟;;数控刀架维修初探[J];新课程(下);2012年04期
5 王丽杰;孙慧;丁喜波;白亚梅;;多工位数控刀架误差测量系统的研究[J];传感器世界;2007年08期
6 沈会;丁蕾;李之洋;;立式伺服数控刀架有限元分析[J];机械工程师;2013年09期
7 王海巧;孙蓓蓓;;基于实例推理的数控刀架快速设计方法[J];东南大学学报(自然科学版);2013年06期
8 谭伟,张济生,张根保;手动经济型数控刀架的原理与设计[J];机械;2001年01期
9 马洪波;朱显明;;四工位数控刀架常见故障诊断与维修[J];黑龙江科技信息;2012年24期
10 张希芳;魏传良;;手动经济型数控刀架的原理与设计[J];中小企业管理与科技(上旬刊);2011年06期
相关重要报纸文章 前2条
1 李培森;好马还须配好鞍[N];中国机电日报;2002年
2 魏旭东;专业化生产是我国数控附件发展方向[N];中国工业报;2006年
相关硕士学位论文 前10条
1 付翔;数控刀架数字化优化设计快速开发平台[D];东南大学;2015年
2 龚书林;数控刀架可靠性分析与信息管理系统设计[D];东南大学;2015年
3 崔政;基于试验的国产数控刀架性能研究[D];东南大学;2016年
4 李昊;基于虚拟制造技术的数控刀架的关键技术研究[D];东北大学;2013年
5 李圳;基于混合分布的数控刀架载荷谱编制方法及应用研究[D];吉林大学;2017年
6 宗立华;数控刀架的可靠性试验方法研究[D];吉林大学;2011年
7 璩国伟;直驱伺服数控刀架关键技术研究[D];东北大学;2012年
8 白亚梅;数控刀架误差测量系统的研究[D];哈尔滨理工大学;2009年
9 李登强;电主轴数控刀架的关键技术研究[D];东北大学;2011年
10 陈志恒;AK31数控刀架可靠性分析与控制技术研究[D];重庆大学;2014年
，本文编号：2412983
本文链接：https://www.wllwen.com/kejilunwen/jiagonggongyi/2412983.html
