【作者】 黄明辉；

【导师】 钟掘；

【作者基本信息】 中南大学 ， 机械设计及理论， 2006， 博士

【摘要】 三万吨模锻水压机和一万吨多向模锻水压机是我国国防和基础产业的关键设备,为我国的军工及民用产品生产发挥了巨大的作用。3万吨和一万吨水压机均为上世纪70年代初建造,其能力和制造精度均难以满足现代国防工业、能源工业等迅速发展对高精度超大规格锻件的需求。因此,国防科工委、国家计委和原中国有色金属工业总公司等下有关部门分别下达专项,决定对其进行现代化功能升级与高技术改造。极端巨大的机械结构的载荷传递与三维空间变形控制是巨型精密模锻水压机设计的核心问题,是水压机精确操作与运行控制的基础。本文以三万吨模锻水压机为研究对象,结合巨型框架结构、垫板结构与螺纹连接组件的力学分析和结构特点,系统建立了具有多维多元超静定、强应力下的非线性接触特征的结构强度与刚度分析的多体弹性接触混合有限元方法:运用现代强度理论、检测技术与计算机技术,研究查明了模锻水压机本体主结构的载荷真实传递和变形规律及各种工况条件下各核心构件的强度储备水平及动态峰值部位,揭示了水压机运行过程中的奇异力学行为规律,如:超静定结构导致的载荷演变特点、附加载荷的产生机制与原因、多体接触/运动副间隙/连接安装方式等因素对局部应力畸变的影响;在上述理论研究的基础上,研制开发了水压机工况监测系统与保护系统,为实现三万吨模锻水压机的技术改造和功能升级提供了理论依据与技术实现的途径。本文的主要研究工作如下:1、大型结构的三维弹性接触问题有限元分析方法:结合巨型框架结构、垫板结构与螺纹连接组件的结构与力学特点,系统建立了具有多维多元超静定、强应力下的非线性接触特征的结构强度与刚度分析的多体非线性接触问题的计算方法和计算软件,解决了多层垫板组结、螺纹连接组件的强度与变形分析计算问题,为巨型结构的设计分析提供了新的方法与手段。2、水压机垫板组的强度和刚度行为研究:根据三万吨水压机垫板组的特点,建立了其三维非线性弹性接触分析有限元模型,提出了一种有限元混合求解算法,获得了垫板组各接触层接触应力的分布和参数影响规律,查明了载荷分布与锻件形状及支承组件结构方式的关联机制。3、立柱及其螺纹组合件的强度与变形分析:为解决重载螺纹连接的计算问题,提出了一种分析弹塑性接触问题的双重非线性有限元方法,建立了水压机立柱与螺纹组合件的接触力学模型,查明了水压机立柱在各种承载状态下的应力分布规律、立柱螺纹组件连接强度的储备水平与增压可能性。4、机架刚度的有限元分析与评估:建立了水压机主体框架(上梁—立柱—固定横梁—下横梁)有限元分析计算模型。系统查明了3万吨水压机主体框架结构在各种可能工况下的真实应力状态、动态应力峰值与分布,分别分析了中载、纵偏、横偏、斜偏等状态下水压机整体的应力状态与空间三维变形规律,为巨型水压机本体结构设计和增压改造强度分析提供了基础依据,并为水压机运行精度提升指出了技术途径。5、主工作缸力学行为分析与强度评估:通过多种模型仿真,并结合有限元计算,克服了实际测压时测点布置的局限性所带来的影响,全面获取了不同结构主工作缸的应力应变状态,并对缸底过渡区的过渡形线等结构参数进行了优化设计,为准确可靠地分析主工作缸的强度、寿命预测及其新缸体的设计提供依据。6、立柱应力在线检测及保护系统研制:基于水压机立柱的应力与变形分析,研制了三万吨水压机的集成式工况监测和非接触式立柱应力保护检测及保护系统,完全满足实际生产过程对检测系统的高精度与实时性要求,采用动态零点采集技术,消除了环境温度变化、零点漂移等因素对应力检测精度的影响,填补了在大型模锻水压机上实现立柱应力高精度检测的空白。基于以上各方面的系统研究结果,本文提出了三万吨水压机功能升级的可行技术途径:在不改变主体结构和不更换主要承力构件的条件下,通过对水压机运动和载荷的有效控制,实现运动的高度同步和偏载抑制,减少附加载荷的产生,同时通过锻造工艺的优化和模具结构的合理设计,减少变形抗力和提高其均匀性,从而使水压机原隐式的过载潜力转化为主锻造过程的实际承载能力提高。该技术途径已经成功实施,实现了我国三万吨水压机的现代化改造与功能升级。更多还原

【Abstract】 300MN Die Forging Hydrostatic Press and 100MN multi-direction Die Forging Hydrostatic Press are the main equipments of national defense and basic industry. They have played a very important role in the manufacturing of military and civil productions. As a matter of fact, both of them were designed and made in the seventies of last century. With the rapid development of modern technology of national defense and energy industry, their production abilities and precision can not meet the requirement of modern technology. Therefore, some departments concerned, such as Commission of Science Technology and Industry for National Defense, State Planning Commission, Chinese nonferrous metal limited company, have set series new projects respectively so as to upgrade the function and reform the technology of Hydraulic Forging Press.In the extremely huge mechanical structure of the huge Die Forging Hydrostatic Press, load transfer and the control of 3D-spatial deformation are the core issues of its design, and they are also the foundation of accurate manipulation and operation control. In this paper, we take the 300mn Die Forging Hydrostatic Press as subject investigation, combine with the mechanics and structure of mega-frame, backing plate frame and conjunction technique, then built a mixed finite element method of multi-body elastic contact problem. In addition, Strength Theory, Determination Technology and Computer Technology were used in the study. As a result, we found the laws of the load transfer and deformation of the Press, such as the characteristics of load evolvement of statically indeterminate structure, generative mechanism and reason of the appended load, and several influential factors of local stress deformation. Base on these theories, Working Condition Monitoring System of the Press and Protecting System were developed. All of this have provide theory basis and technology guidance for the Press’s technology innovate and function upgrade.The main studies are as follows:1、The method of finite element of 3D elastic contacting problem of large-scale structure:Combining with structural and mechanical characters of large frame structure, backing plate and screw contacting subassembly, we have set up calculating method and software of multi-body nonlinear contacting problem, nonlinear contacting characteristic frame strength and stiffness analysis. And these were under multi-dimensions multivariate statically indeterminate and strong stress. This thesis have solved the strong and deformation analysis problems of multilayer backing plates subassembly, screw contacting subassembly, which have offered new methods and paths for large-scale designing analysis.2、Strength and stiffness analysis of Hydrostatic Press backing plate group:Base on 300mn Die Forging Hydrostatic Press’s characteristics, this thesis have set up the finite element model of 3D nonlinear elastic contacting analysis, developed a kind of mixed solving algorithm of finite element, and got backing plate group contact layers contact stress’ distribution and parameter rules, found out load distributing, forging piece shape and supporting components frame mode relevant machine-made.3. Strength and deformation analysis about upright column and screw assembled parts:A double nonlinear finite element method about elastic-plastic contact problem is brought up, in order to solve the screwed connection heavy load problem. This thesis built the contact mechanical model of upright column and screw assembled parts. In addition, stress distribution regulation of the upright column under variable load condition was found out. There are also some other regulations, such as joining strength of upright column screw, the possibility of pressurization and so on.4. Finite element method analysis and evaluation of framework stiffness:This thesis also built finite element method analysis model of hydrostatic press’s main framework (up beam-upright column-fixed beam-down beam). And found out true stress、dynamic stress peak and stress distribution of 300MN Die Forging Hydrostatic Press under variable load condition. In addition, stress station and 3D deformation regulation of the main framework which under different load condition were analyzed respectively. It lays great base on framework of the huge hydrostatic press’s design and re-modification. A new way for the accuracy promotion was pointed out as well.5. Mechanical behavior analysis and strength evaluation of the main working cylinder:After many simulation and finite element calculation, overcome the effects of actual measurement positioning errors, This thesis have got plenty of information about the stress-strain state of the working cylinder. In addition, the cylinder’s structure parameter was optimized design. These studies really means a lot to the intensity analysis of the working cylinder, so as to its life prediction and design.6、Stress online detecting of upright column and research of protection system:According to the analysis of stress and distortion of the upright column in Hydrostatic Press, we have developed the integrated working conditions detecting system and non-contact upright column stress protecting system for the 300MN Hydrostatic Press. It can fully meet the high-precision and real-time demands . Using the dynamic acquisition technology, the system can eliminate the errors of stress’s detecting precision which were caused by the environment temperature, zero shift and other factors. This technology supplied a gap of high-precision detecting of upright column on the large-scale die forging hydrostatic press.Based on the results all above, This thesis put forward a feasible technical way for functions upgrading of 300MN Hydrostatic Press: Maintaining the main body structure , keeping the core components the same, and then by controlling the motion and load of the hydrostatic press, we can carry out the high synchronization of motion and restrain from deflect loads, and decrease appended loads. At the mean time, we can also decrease the distortion resistance and improve the equality of work-piece by optimizing forging technology. Thereby, the Hydrostatic Press’s latent overloading can be translated into practical forging load ability on the main forging process. This technology has been carried out successfully, made the modernization rebuilding and function upgrading of the 300MN Hydrostatic Press a reality.更多还原