伺服转塔刀架可靠性评估及结构优化

发布时间：2018-04-26 15:10

  本文选题：伺服转塔刀架 + 故障模式与影响分析　； 参考：《东南大学》2016年博士论文

【摘要】：加速提升中高档数控系统和功能部件配套能力,是顺应当今数控机床高速、高效、高精、柔性和复合加工发展趋势的重要任务。对数控刀架这一功能部件而言,伺服转塔刀架(本节以下简称“伺服刀架”)是由中档产品跨入高档产品的桥梁,因此对该产品的自主研制具有承前启后的意义。在这一新产品研发过程所应对的关键技术指标中,其可靠性水平将直接牵制所匹配机床的整体性能,特别是运行稳定性和工作效率,因此,基于可靠性系统工程的研发阶段工作以研究并提升伺服刀架的可靠性水平,将具有重大的工程应用价值。本文在“高档数控机床与基础制造装备”科技重大专项资金项目的资助下,针对伺服刀架在研发阶段的可靠性定性分析、定量评估、优化设计、研制试验进行了系统研究。研究过程中,通过综合运用可靠性技术体系,并根据伺服刀架自身特点创新性地提出了多状态动态故障树分析方法、多失效模式下多状态频率可靠性分析方法、刀架可靠性切削研制试验方法,以及基于综合运行信息的PCM-PHM综合模型,探索出了一整套完整实用的解决方案,从而能有效评估并提升新研制伺服刀架的可靠性水平。概括起来,本文的研究内容及取得的主要成果如下：(1)伺服刀架故障模式与影响分析(FMEA)。在系统规划和原型设计阶段,通过分析FMEA的目标及实施步骤,特别指出收集相似产品的可靠性信息能有效提高FMEA结论的有效性；基于该思路统计分析了相似成熟产品液压转塔刀架的故障部位、故障模式；采用分布拟合检验方法建立了系统及各子系统含截尾数据的首次故障时间模型。基于独立功能流串联/并联/转换规则将伺服刀架规范划分为10个子系统模块,并在此基础上估计了与液压转塔刀架各个相似模块元以及系统整体的相似度。以各个子系统为单位列举了可能的故障模式及故障原因,结合故障影响分析,提出了预防及补偿措施。(2)伺服刀架多状态系统可靠性指标分析。根据伺服刀架的多状态特性,提出了多状态动态故障树(MDFT)建模分析方法：首先提出了状态空间以及状态变换的线性代数描述方法(LAR),并基于状态变换的思路将各类静、动态逻辑门运算规则的建立转化为两个变量的求解。在此基础上,针对模块化的MDFT模型,提出了可变步长时序模拟时钟的生成方法,以支持蒙特卡洛仿真定量分析多状态特性下的系统可靠度及子系统重要度。将该方法应用到伺服刀架中,评估出系统可靠寿命以及后续以待优化的关键子系统。(3)伺服刀架关键结构的可靠性优化设计。在改进设计阶段,基于应力-强度干涉模型建立了多失效模式下刀盘子系统状态函数,综合运用矩方法、蒙特卡洛仿真搭建了静强度可靠性模型；采用可靠性灵敏度分析识别敏感结构参数,并优选出满足可靠度要求的改进方案。提出了多失效模式下多状态频率可靠性分析方法,并设计了嵌套式蒙特卡洛仿真以评估系统频率可靠度；采用相关性分析方法识别了随机结构参数的敏感程度和敏感方向；将该方法应用到基于多体系统传递矩阵法(MS-TMM)所建立的伺服刀架系统动力学模型上,提出了轻量化设计方案使得系统频率可靠度得到了显著提高。(4)伺服刀架可靠性切削研制试验设计及试验平台搭建。在样机试制阶段,综合考虑伺服刀架的实际工况提出了刀架可靠性切削研制试验方法,以合理评估在真实切削载荷环境下的可靠性水平,所考察可靠性包含着刀架的性能保持能力：系统陈述了试验总体设计思路,并以功能需求为指导搭建了刀架综合性能及可靠性研究平台；提出了基于多种材料典型试件加工的任务剖面编制方法,使得借助切削力测试系统最终确定的试验内容既具有代表性,又能流畅执行以缩短试验周期；制定了综合性能测试规程(包括静刚度、重复定位精度、转位噪声、加速度频响函数),以及数据采集分析方法。(5)基于综合运行信息的受试伺服刀架可靠性评估。针对具有突发类与退化类共存且相互独立的竞争故障模式,以经典协变量模型为基础提出了PCM-PHM综合模型：既考虑了载荷条件对不同类故障模式下可靠性的影响,又充分利用多种性能特征以建立退化类故障模式下的可靠性模型。将该方法应用到参与可靠性切削研制试验的受试样机可靠性评估中：采用恒值载荷步叠加计数及分布拟合检验方法建立了试验载荷分布模型,并基于此确定了环境协变量；采用相关分析及指数模型建立起综合响应协变量特征值；利用多元线性回归方法获得了伺服刀架故障率函数,并进一步建立了可靠度函数及可靠寿命估计。上述研究成果最终应用于伺服刀架的设计制造中,取得了良好的实际效果。这款具有自主知识产权的中高档数控刀架功能部件产品目前已经批量生产并实现与数控车床配套使用,其可靠性水平在用户处得到了普遍认可。
[Abstract]:It is an important task to accelerate the upgrading of middle and high grade CNC system and functional components. It is an important task to conform to the development trend of high speed, high efficiency, high precision, flexible and compound machining of CNC machine tools. For this function part, servo turret (hereinafter referred to as "servicing tool holder") is a bridge from middle grade to high-end products. In this new product R & D process, the reliability level will directly affect the overall performance of the matched machine tool, especially the operation stability and efficiency. Therefore, the research and development stage based on the reliability system engineering will be studied and The improvement of the reliability level of the servo tool holder will be of great engineering application value. In this paper, the reliability qualitative analysis, quantitative evaluation, optimization design and development test of the servo tool holder in the R & D stage are systematically studied under the support of the major project of "high-grade CNC machine tools and basic manufacturing equipment". In the process, the multi state dynamic fault tree analysis method, multi state frequency reliability analysis method under multi failure mode, tool reliability cutting development test method, and PCM-PHM integrated model based on comprehensive operation information are explored and explored, based on the comprehensive application of reliability technology system and according to the characteristics of servo tool frame. A complete set of practical solutions can be used to effectively evaluate and improve the reliability level of the newly developed servo tool holder. In summary, the research content and main achievements of this paper are as follows: (1) the failure mode and influence analysis (FMEA) of the servo tool holder. In the stage of system planning and prototype design, the objectives and implementation steps of the FMEA are analyzed. In particular, it is pointed out that the reliability information of collecting similar products can effectively improve the validity of the FMEA conclusion. Based on this idea, the fault location and fault mode of the hydraulic turret tool holder of similar mature products are analyzed and the fault time model based on the distribution fitting test method is used to establish the first fault time model of the system and each subsystem with truncated data. The independent functional flow series / parallel / conversion rules divide the servo tool frame into 10 subsystem modules, and on this basis, the similarity between the various modules and the whole system of the hydraulic turret tool is estimated. The possible failure modes and failure reasons are enumerated in each subsystem. Prevention and compensation measures. (2) reliability index analysis of multi state system of servo tool frame. Based on the multi state characteristics of servo tool frame, a multi state dynamic fault tree (MDFT) modeling and analysis method is proposed. First, the linear algebraic description method of state space and state transformation (LAR) is proposed, and all kinds of static and dynamic state transformation are based on the state transformation. The establishment of logic gate operation rules is transformed into two variables. On this basis, a method of generating variable step size time series analog clock is proposed for modularized MDFT model, in order to support the Monte Carlo simulation for quantitative analysis of system reliability and subsystem importance in multi state characteristics. The method is applied to the servo tool frame and the evaluation of the method is applied. The reliable life of the system and the key subsystem of the subsequent optimization are estimated. (3) the reliability optimization design of the key structure of the servo tool. In the improved design stage, the state function of the knife and plate system under the multi failure mode is established based on the stress intensity interference model. The static strength reliability model is built by the Monte Carlo simulation and the Monte Carlo simulation. The reliability sensitivity analysis is used to identify the sensitive structural parameters and optimize the scheme to meet the requirements of reliability. A multi state frequency reliability analysis method under multiple failure modes is proposed, and a nested Monte Carlo simulation is designed to evaluate the reliability of the system frequency, and the random structural parameter is identified by the method of correlation analysis. The sensitivity and sensitive direction of the number are applied to the dynamic model of the servo tool frame system based on the multibody system transfer matrix method (MS-TMM). A lightweight design scheme has been proposed to improve the system frequency reliability significantly. (4) the experimental design and test platform of the servo tool holder can be developed and the test platform is set up. In the trial stage of the prototype, the reliability cutting test method of the tool holder is put forward in consideration of the actual working conditions of the servo tool holder, so as to reasonably evaluate the reliability level in the real cutting load environment, and the reliability is included in the performance retention capability of the tool holder. The system states the overall design idea of the test and takes the function requirement as the guidance. The research platform for comprehensive performance and reliability of the tool holder is built, and a task section compilation method based on the typical specimen processing is put forward, which makes the final test content of the cutting force testing system not only representative, but also can be carried out smoothly to shorten the test period. Complex positioning accuracy, transposition noise, acceleration frequency response function, and data acquisition and analysis methods. (5) the reliability evaluation of the servo tool holder based on the integrated operation information. The PCM-PHM synthesis model is proposed based on the classical covariate model, which is based on the classical covariate model. The effect of load conditions on the reliability of different type of fault modes and the full use of various performance characteristics to establish the reliability model of the degenerate type fault model. The method is applied to the reliability evaluation of the sample machine involved in the reliability cutting development test: the method of constant load step superposition counting and distribution fitting test is established. The experimental load distribution model is established, and the environmental covariate is determined based on this. The correlation analysis and the exponential model are used to establish the eigenvalue of the integrated response covariate, and the fault rate function of the servo tool holder is obtained by using the multiple linear regression method, and the reliability function and the life estimation are further established. The results are finally applied. In the design and manufacture of the servo tool, a good practical effect has been achieved. The product of the middle and high grade CNC tool rack with independent intellectual property right now has been produced and used with the CNC lathe. The reliability level has been universally recognized at the user's place.

【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG659
，

本文编号：1806543