多通道加样臂动态性能分析及优化设计

发布时间：2019-02-21 07:39

【摘要】：基因提取、蛋白质结晶以及新药研制等工程中需要对种类繁多的生物试剂进行高通量、高精度定量分配，传统的手工作业劳动强度大、精度低、重复性差。应运而生的单通道自动加样系统在一定程度上克服了手工加样的缺点，但仍满足不了越来越繁重的试样操作要求。多通道自动加样系统因具有4个、8个或者16个通道，针间距变化可与96孔微孔板一致，一次操作可实现多个试样的分配，不但减少了实验操作人员的分配操作次数，而且可提高分配的精密度，是微量试样高通量处理的发展趋势。本文研究的四通道加样机构其处理速度为16孔/秒、加样针的位置精度为±0.2mm、针距之间可实现9mm与18mm间距变换。悬臂是加样机构极其重要的组成部分，负担着多个通道组成的质量较大的移动体，移动体在悬臂上做1m/s的高速运动，产生的激励会导致悬臂振动，进而影响处理速度与位置精度，因此要求悬臂的刚度与机械阻抗越大越好，其振动越小越好。本文在研究国内外现有多通道加样机构与阅读大量相关文献基础上，，首先，通过构型综合确定了采用单输入螺旋式等距分度机构作为加样针间距调整机构，并通过工程应用分析确定了悬臂式的支撑方式，在此基础上完成了关节结构方案的设计。然后，应用模态分析理论将悬臂简化为欧拉伯努利梁，从机械刚度、机械振动、机械阻抗三个方面对悬臂的机械性能进行分析，通过建立系统的数学模型，得到影响悬臂刚度的若干因素、计算出了组合梁的固有频率、框架的固有频率；推导出了移动质量激励下悬臂梁的位移、速度、加速度响应与悬臂的机械阻抗表达式。着重分析了对悬臂动态特性影响最大的框架结构，应用惩罚函数法以框架刚度惯量比最大为优化目标函数对框架截面尺寸进行了优化。优化后计算结果表明，在刚度惯量比增大的情况下，框架的固有频率提高了24%，静刚度提高了89%。最后，搭建了实验平台，采用模态实验分析方法，应用压电陶瓷传感器等，通过对压电陶瓷变形输出变化的电压信号进行图像与数据采集并运用周期法完成框架与组合梁的固有频率与静刚度测定后，分析了测量值与理论值产生误差的原因。
[Abstract]:Gene extraction, protein crystallization and the development of new drugs need to carry out high-throughput and high-precision quantitative distribution of a wide variety of biological reagents. The traditional manual work is characterized by high labor intensity, low precision and poor repeatability. The single channel automatic sampling system has overcome the shortcoming of manual sampling to some extent, but it still can not meet the more and more heavy sample operation requirements. Because the multi-channel automatic sampling system has 4, 8 or 16 channels, the change of needle spacing can be consistent with that of 96 hole microporous plates, and the distribution of multiple samples can be realized in one operation, which not only reduces the number of assignment operations of the laboratory operators, Moreover, the precision of distribution can be improved, which is the development trend of high throughput treatment of trace samples. The four-channel sampling mechanism studied in this paper has the processing speed of 16 holes per second, the accuracy of 卤0.2 mm in the position of the needle, and the distance between 9mm and 18mm can be transformed between the needle pitch. The cantilever is an extremely important part of the sample adding mechanism. It bears a large mass moving body composed of multiple channels. The high speed motion of the 1m/s on the cantilever will result in the vibration of the cantilever. Therefore, the greater the stiffness and mechanical impedance of the cantilever is, the better the vibration is. Based on the study of the existing multi-channel sampling mechanism at home and abroad and the reading of a large number of related documents, firstly, the single-input spiral isometric indexing mechanism is adopted as the adjusting mechanism of the needle spacing through the configuration synthesis. The cantilever support mode is determined through engineering application analysis, and the design of joint structure scheme is completed on this basis. Then, using modal analysis theory, the cantilever is simplified to Euler Bernoulli beam. The mechanical properties of the cantilever are analyzed from three aspects of mechanical stiffness, mechanical vibration and mechanical impedance, and the mathematical model of the system is established. Some factors affecting cantilever stiffness are obtained, and the natural frequency of composite beam and frame are calculated. The expressions of displacement, velocity, acceleration response and mechanical impedance of cantilever under moving mass excitation are derived. The frame structure which has the greatest influence on the cantilever dynamic characteristics is emphatically analyzed. The frame cross-section size is optimized by using the penalty function method with the maximum stiffness / inertia ratio of the frame as the optimization objective function. The results show that the natural frequency of the frame is increased by 24 and the static stiffness of the frame is increased by 89 when the ratio of stiffness and inertia is increased. Finally, the experiment platform is built, the modal experiment analysis method is adopted, the piezoelectric ceramic sensor and so on are used. By collecting the image and data of the voltage signal of the piezoelectric ceramic deformation output and using the periodic method to measure the natural frequency and static stiffness of the frame and composite beam, the causes of the errors between the measured and theoretical values are analyzed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH112

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