重型机床装配精度可靠性评价及其工艺设计方法

发布时间：2018-02-28 22:32

本文关键词： 重型机床装配精度可靠性工艺设计　出处：《哈尔滨理工大学》2015年博士论文　论文类型：学位论文

【摘要】：作为核电压力容器的关键零件,水室封头长期在高温、高压与腐蚀条件下工作,其设计、选材与加工制造等都有着极为严格的要求。该类零件重达数十吨至上百吨,其工件材料一般为低碳合金钢,此类材料虽然硬度不高,但韧性和强度较高,切削加工性能差,其加工时切削力大、切削温度高、振动剧烈,切削载荷变化情况复杂,对于机床的承载能力、抗振性提出了极高要求,已有的重型机床无法满足水室封头的加工要求。因此,开发高水平重型数控机床设计、制造技术,研制水室封头专用数控龙门移动式车铣加工中心,满足大尺寸、大吨位、高精度核电零件精确加工与批量化生产的需求,对推动核电装备制造技术进步,促进国产重型数控机床技术的发展具有重要现实意义。重型数控机床整机结构庞大,初次装配检验合格后,需要将部分零部件拆卸,运至生产现场进行二次装配,对机床装配精度可靠性要求高。该机床装配变形和累积误差大,在装配中经常采用修研、试凑方法,导致床身、立柱、导轨、横梁等零部件全行程配合精度低,装配精度可靠性差,无法满足机床运动部件平稳、可靠传递精度和动力的需求。本文针对水室封头数控龙门移动式车铣加工中心研制中存在的上述问题,进行重型机床装配精度可靠性与装配工艺设计方法研究,主要内容包括：为满足水室封头专机的车削、铣削、镗削的功能需求,研究机床功能与机床结构、装配工艺的映射关系,建立机床装配精度可靠性评价指标,揭示机床装配精度可靠性与结构的映射关系,构建机床装配工艺层次结构,通过装配载荷与装配变量分析,提出机床装配精度可靠性工艺设计方案,并进行实例验证。采用多体系统模型,分析机床装配初始误差的形成过程,揭示初始误差的影响因素及其累积过程,提出机床部件形位误差源、接触误差源和整机装配初始误差解算方法,并进行机床初次装配工艺评判和误差检测。针对机床装配精度随装配工序变化特性,表征初次装配精度迁移、重复装配精度迁移和机床运行中的装配精度迁移过程,研究机床装配精度与变形场的映射关系,提出机床变形场影响因素与关键工序变量识别方法,建立机床装配精度迁移判据,构建机床装配精度迁移模型,揭示装配精度迁移的形成、增长和转变机制,提出机床装配工艺设计方法,并进行实例验证。针对水室封头车铣加工中心B轴组件装配精度设计要求,分析B轴重要组件滑枕的变形特性,建立滑枕组件前端面装配误差的解算模型,通过机床B轴结构设计方案评判,获得满足设计要求的B轴组件结构修正设计方案,并对该方案效果进行验证。
[Abstract]:As a key part of nuclear power pressure vessel, the head of water chamber works under the conditions of high temperature, high pressure and corrosion for a long time. Its design, material selection, processing and manufacture have very strict requirements. The weight of this kind of parts is tens to hundreds of tons. The workpiece material is generally low carbon alloy steel. Although the hardness of this kind of material is not high, its toughness and strength are high, and its cutting performance is poor. The cutting force is large, the cutting temperature is high, the vibration is intense, and the cutting load changes are complicated. The bearing capacity and vibration resistance of machine tools are very high, and the existing heavy-duty machine tools can not meet the processing requirements of the head of water chamber. Therefore, the design and manufacturing technology of high level heavy numerical control machine tools is developed. To develop a special CNC gantry turn-milling machining center for water chamber head, to meet the needs of large size, large tonnage and high precision nuclear power parts precision machining and mass production, and to promote the progress of nuclear power equipment manufacturing technology. It is of great practical significance to promote the development of domestic heavy-duty NC machine tool technology. The heavy NC machine tool has a large structure and needs to disassemble some parts and components to the production site for secondary assembly after the first assembly and inspection. The accuracy and reliability of the machine tool assembly is high. The assembly deformation and accumulated error of the machine tool are large, and the method of revision and research is often used in the assembly, which leads to the low precision of the whole stroke matching of the parts such as the bed, the column, the guide rail, the beam, and so on. Because of the poor reliability of assembly precision, it can not meet the requirements of stable, reliable transmission of precision and power of the moving parts of the machine tool. This paper aims at the above problems in the development of the CNC gantry movable turn-milling machining center with water chamber seal head. In order to meet the needs of turning, milling and boring of water chamber head special machine, the function and structure of machine tool are studied. The mapping relation of assembly process, the evaluation index of machine tool assembly precision reliability, the mapping relation between machine tool assembly precision reliability and structure, the construction of machine tool assembly process hierarchy structure, and the analysis of assembly load and assembly variables are established. The reliability process planning scheme of machine tool assembly accuracy is put forward and verified by an example. The forming process of machine tool assembly initial error is analyzed by using multi-body system model, and the influencing factors of initial error and its accumulation process are revealed. In this paper, the error source of machine tool parts, contact error source and initial error calculation method of whole machine assembly are put forward, and the primary assembly process evaluation and error detection of machine tool are carried out. According to the characteristics of machine tool assembly accuracy varying with assembly process, This paper describes the migration of primary assembly precision, repeated assembly precision and assembly precision migration in machine tool operation. The mapping relationship between machine tool assembly precision and deformation field is studied, and the identification method of influencing factors and key process variables of machine tool deformation field is put forward. The criterion of machine tool assembly precision migration is established, the model of machine tool assembly precision migration is constructed, the forming, increasing and transforming mechanism of assembly precision migration is revealed, and the method of machine tool assembly process design is put forward. According to the design requirements of assembly accuracy of B-axis components in the water chamber head turn-milling machining center, the deformation characteristics of the sliding pillow of the important components of B-axis are analyzed, and the calculation model of the assembly error of the front surface of the head-end of the sliding pillow is established. By judging the design scheme of machine tool's B-axis structure, the modified design scheme of B-axis component structure is obtained, and the effect of the scheme is verified.
【学位授予单位】：哈尔滨理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG659

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