真空加热观测实验平台设计开发

发布时间：2018-03-11 08:21

  本文选题：真空加热　切入点：观测　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：真空技术以其无污染、无氧化等特点在加热领域得到了越来越广泛的应用。目前常见的真空加热设备大多应用于工业生产。工业用设备往往体积庞大,难以搭配高倍显微镜对真空加热过程进行精密监测,对工件或材料在某一温度下的变形以及表面形貌变化只能凭借经验做出定性的估计,难以做出精确的定量判定。为解决此问题,本文研究开发了真空加热观测实验平台,主要研究内容包括以下几个方面。(1)根据真空加热观测实验平台技术指标制定整体方案,并对组成该平台的五个部分进行逐一设计。真空室部分,设计了真空腔体结构,计算了真空腔体壁厚,选取了观察窗水冷方案并布置了水冷通道。真空泵组部分,设计了泵组组合方案,选取了机械泵与分子泵。真空管路部分,设计了连接真空室和泵组的管路。加热部分采用外热式加热,对加热丝的结构和排布进行了设计,同时设计制作了保温层和温控回路。其它部分则选取了隔振平台,设计定做了高倍显微镜。(2)运用有限元分析软件ANSYS Workbench对真空腔体进行有限元分析,仿真结果表明:在额定载荷下,真空腔体底部变形最大,侧壁抽气口开孔处应力最大,真空腔体底部变形量超过技术指标要求。为了减小变形量,本文采用对真空腔体底部进行加厚和布置加强筋的方案对真空腔体底部进行结构优化,并对两种优化方案从加工工艺到优化效果进行对比,最终选取真空腔底部加厚的方案。对真空腔体侧壁结构进行尺寸的参数化管理,并以真空腔体应力值最小、真空腔体质量最小为目标进行多目标驱动优化,根据优化结果选取抽气口管路轴线到真空腔体顶部距离29mm和抽气口内径尺寸8mm的最佳尺寸组合。(3)对加工完成的真空加热观测实验平台各部分进行搭接、安装,并对组装完成后的设备进行抽真空试验和显微观测试验。结果表明:真空加热观测实验平台能够在额定时间内达到要求真空度,且放大倍数、视野范围均符合技术指标要求。对真空加热观测实验平台的工作区域进行了最高工作温度下的温度均匀性测量。结果表明:随着加热时间的延长升温速度减慢,加热30min后工作区域温度可以稳定在最高设定温度700℃附近,温度场进入平衡状态。对30min、32min、34min、36min、38min、40min六个时刻的测温点温度数据进行温度均匀性计算。结果表明:这六个时刻温度均匀性分别为5℃、4℃、8℃、5℃、6℃和4℃,符合设备的温度技术指标要求。
[Abstract]:Vacuum technology is more and more widely used in the field of heating because of its characteristics of non-pollution and non-oxidation. At present, most of the common vacuum heating equipments are used in industrial production. It is difficult to precisely monitor the vacuum heating process with a high-power microscope. The deformation of the workpiece or material at a certain temperature and the change of the surface morphology can only be qualitatively estimated by experience. It is difficult to make accurate quantitative judgment. In order to solve this problem, a vacuum heating observation experimental platform is developed in this paper. The main research contents include the following aspects. Five parts of the platform are designed one by one. In the vacuum chamber part, the structure of the vacuum chamber is designed, the wall thickness of the vacuum chamber is calculated, the water cooling scheme of the observation window is selected and the water cooling channel is arranged. The combination scheme of pump group is designed, the mechanical pump and molecular pump are selected, and the pipe connecting vacuum chamber and pump group is designed. The heating part is heated by external heat, and the structure and arrangement of heating wire are designed. At the same time, the insulation layer and the temperature control loop are designed and manufactured. In other parts, the vibration isolation platform is selected, and the high-power microscope is designed and customized. The finite element analysis software ANSYS Workbench is used for the finite element analysis of the vacuum cavity. The simulation results show that under rated load, the bottom deformation of vacuum cavity is the largest, and the stress at the opening of sidewall air outlet is the largest. The deformation of vacuum cavity bottom exceeds the requirement of technical index. In this paper, the structure of vacuum cavity bottom is optimized by thickening and reinforcement arrangement at the bottom of vacuum cavity, and the two optimization schemes are compared from processing technology to optimization effect. Finally, the scheme of thickening the bottom of vacuum cavity is selected. The dimension of the side wall of vacuum cavity is parameterized, and the minimum stress of vacuum cavity and the minimum mass of vacuum cavity are taken as the goal of multi-objective driving optimization. According to the optimization results, the optimum dimension combination of 29mm distance between the axis of the exhaust pipe line and the top of the vacuum cavity and 8mm of the inner diameter of the air outlet is selected to lap and install the parts of the vacuum heating observation experimental platform completed by machining. The vacuum test and microscopic observation test of the assembled equipment are carried out. The results show that the vacuum degree required and the magnification of the vacuum heating observation platform can be achieved within the rated time. The range of visual field meets the requirements of technical specifications. The temperature uniformity of the working area of the vacuum heating experimental platform is measured at the highest working temperature. The results show that the heating rate slows down with the prolongation of heating time. After heating for 30 min, the temperature of the working area can be stabilized at the maximum set temperature of 700 鈩，

本文编号：1597350