面向增材制造的模型重建方法与成型工艺研究

发布时间：2018-08-24 08:00

【摘要】：随着现代制造业全球化与市场化的发展,能在更短的时间内开发出新产品并推向市场是企业保持竞争力的关键所在。增材制造技术的应用加速了产品的设计开发过程,降低了产品设计验证成本。与传统去除材料的加工方式不同,增材制造是一个分层累积材料的过程,将三维零件降维到二维平面或者一维的点线,消除了复杂形状对加工制造的限制。从上世纪的八十年代增材制造技术出现开始,目前已经有多种增材制造加工工艺,也有光敏树脂、金属与陶瓷粉末等多种材料可供应用。但其加工精度、表面质量与所得零件的性能与传统的切削加工、铸造锻压成型、注塑成型等工艺还有较大的差距,这些都限制了增材制造的大范围应用。相对于传统的加工技术,增材制造加工零件的单个成本相对较高,不适合大批量零件的制造。针对上述问题,本文从集成数控增材制造工艺与基于掩膜图像投影的增材制造工艺两方面进行了研究,以期提高增材制造的加工质量、扩展其应用范围。主要研究内容与成果如下： (1)基于双轴旋转微镜的可集成模型数字化技术研究。以实现集成模型三维测量系统的增材制造工艺为目标,以德州仪器的TALPIOOOB双轴旋转微镜镜和摄像机为核心部件,设计了三维激光测量系统。该系统通过控制双轴旋转微镜来控制激光点的移动,实现一次固定,区域测量,可作为集成部件方便的安装到增材制造系统当中,实现对待加工表面的在线测量。测量系统中采用分层离散的定标算法对摄像机和激光位置进行标定,基于双线性插补算法计算图像像素点位置和激光点位置。由双轴旋转微镜与摄像机分别获取经过被测点的两条空间直线,然后通过空间直线的三角化求交来计算测量点位置。通过测量实例,分析了测量误差产生的原因及提高措施。 (2)基于代数点集曲面APSS与多层深度法矢图像LDNIs的模型重建算法研究。采用代数点集曲面APSS拟合测量点集,进行去噪平滑,然后通过投影运算将APSS曲面转化为LDNIs表达的实体模型,进而采用轮廓线算法生成三角网格曲面,实现模型的重建。 (3)研究了集成数控增材制造系统。针对传统分层增材制造工艺所得零件在不同方向上物理性能不一致的问题,开发基于数控技术的无分层增材制造工艺CNCA。将所开发的三维测量系统与模型重建算法集成到该工艺当中,实现对待加工表面的在线测量与模型重建。结合基于多层深度法矢图像的布尔运算与偏置运算,实现激光头的路径规划,输入数字控制系统,实现在给定曲面上的固化加工 (4)基于MIP-SLA的大面积微细加工制造工艺研究。对基于DLP投影机的MIP-SLA(?)曾材制造工艺的加工原理、工艺流程及系统组成进行了研究,重点研究了基于约束液面的MIP-SLA增材制造工艺。设计开发了基于MIP-SLA的大面积微细制造工艺系统,研究了制造系统的图像生成与工艺规划。基于商业投影机,重构光学系统实现掩膜图像在微小区域内的聚焦,通过对光路与加工基座在平面内的扩展,实现大面积微细零件的制造。 (5)基于LDNIs的掩膜图像切片生成算法研究。提出了基于LDNIs模型的掩膜图像生成算法,该算法首先对实体模型进行采样离散生LDNIs模型,然后采用离散的一维布尔运算代替传统的轮廓求交运算得出二维的掩膜图像。该算法在处理复杂模型与小层厚图像生成时与基于轮廓的算法有更高的运算效率。研究DLP投影机的标定算法,提出采用分层离散的方式对其进行空间定标。并根据定标数据实现了投影图像的反算。在基于MIP-SLA工艺的光滑表面制造系统中，，应用空间投影图像反算算法生成该工艺中的二次投影图像。 (6) MIP-SLA原型机系统设计。设计搭建了大面积微细制造工艺的硬件系统,对微细加工的曝光时间、加工分辨率等因素进行了研究。基于EtherMAC运动控制系统及WindowsCE (?)沃入式操作系统开发了约束液面式MIP-SLA原型机系统。开发了了基于PC的掩膜图像切片软件与基于WindowsCE嵌入式系统的控制软件,并设计了分离拉力的在线测量系统。通过实验验证了掩膜图像切片算法的正确性,测定了系统的加工精度、加工效率以及加工过程中分离拉力随加工面积的变化趋势。论文对面向增材制造的模型数字化技术与模型重建方法的研究,实现了集成的数控增材制造系统。该系统创新性地提出了无分层的制造方式,解决了分层制造工艺所加工零件在各个方向物理性能不一致的问题。基于多层深度法矢图像的掩膜图像生成算法与传统的基于轮廓的算法相比,在处理复杂模型方面具有更高的计算效率。所设计的大面积微细制造工艺系统克服了MIP-SLA工艺加工分辨率与加工面积之间的矛盾,可实现高分辨大面积零件的制造,对扩展MIP-SLA工艺的应用范围,提高零件的加工精度有重要的意义。
[Abstract]:With the development of globalization and marketization of modern manufacturing industry, it is the key for enterprises to develop new products and push them to the market in a shorter time. The application of augmented material manufacturing technology accelerates the process of product design and development and reduces the cost of product design verification. Manufacturing is a process of layered accumulation of materials, which reduces the dimension of three-dimensional parts to two-dimensional plane or one-dimensional point and line, eliminating the restriction of complex shape on machining.
Since the appearance of augmented materials manufacturing technology in the 1980s, there have been many kinds of augmented materials manufacturing processes, as well as photosensitive resins, metal and ceramic powders and other materials for application. Compared with the traditional machining technology, the single cost of manufacturing parts by adding materials is relatively high, which is not suitable for manufacturing large quantities of parts. The main research contents and achievements are as follows:1.
(1) Research on the digitization technology of integrated model based on Two-axis rotating micromirror. Aiming at the manufacturing process of the integrated model three-dimensional measuring system, a three-dimensional laser measuring system was designed with TALPIOOOB dual-axis rotating micromirror and camera as the core components. The moving of the light point can be fixed once and the area measurement can be carried out. It can be easily installed into the augmented material manufacturing system as an integrated part to realize the on-line measurement of the machined surface. The position of laser point is calculated by triangulating the intersection of the two space lines which pass through the measured point. The cause of measurement error and the improvement measures are analyzed through a measurement example.
(2) Research on model reconstruction algorithm based on algebraic point set surface APSS and multi-layer depth normal image LDNIs. Using algebraic point set surface APSS to fit measurement point set, denoising and smoothing are carried out, then APSS surface is transformed into solid model expressed by LDNIs through projection operation, and then triangular mesh surface is generated by contour algorithm to realize the model. Reconstruction.
(3) The integrated NC augmentation manufacturing system is studied. Aiming at the problem of inconsistent physical properties in different directions of parts produced by traditional layered augmentation manufacturing process, a NC-based non-layered augmentation manufacturing process CNCA is developed. On-line surface measurement and model reconstruction. Combining Boolean operation and offset operation based on multi-layer depth normal vector image, path planning of laser head is realized, digital control system is inputted, and curing machining on a given surface is realized.
(4) Research on large area micro-fabrication process based on MIP-SLA. The principle, process flow and system composition of MIP-SLA based on DLP projector are studied. The MIP-SLA based on constrained liquid level is emphatically studied. A large area micro-fabrication process system based on MIP-SLA is designed and developed. The image generation and process planning of manufacturing system are studied. Based on commercial projector, the optical system is reconstructed to focus the mask image in a small area. By expanding the light path and the machining base in the plane, large area micro parts are manufactured.
(5) Research on Algorithm of mask image Slicing Based on LDNIs. A mask image generating algorithm based on LDNIs model is proposed. Firstly, the solid model is sampled and the discrete LDNIs model is generated. Then the discrete one-dimensional Boolean operation is used instead of the traditional contour intersection operation to get the two-dimensional mask image. This paper studies the calibration algorithm of DLP projector and proposes a method of spatial calibration by layered discrete method. The projection image is inversely computed according to the calibration data. In the smooth surface manufacturing system based on MIP-SLA technology, the spatial projection map is applied. The inverse algorithm is used to generate the two projection image in the process.
(6) The design of MIP-SLA prototype system. The hardware system of large area micro-fabrication process is designed and built. The exposure time and processing resolution of micro-fabrication are studied. The constrained liquid-level MIP-SLA prototype system is developed based on EtherMAC motion control system and Windows CE (?) Wordin operating system. The mask image slicing software and the control software based on the embedded system of Windows CE are designed, and the on-line measurement system of the separating tension is designed.
The integrated NC augmented material manufacturing system is realized by the research of model digitization technology and model reconstruction method for incremental material manufacturing. The system innovatively proposes a layered-free manufacturing method, which solves the problem of inconsistent physical properties of parts processed by layered manufacturing process in different directions. Compared with the traditional contour-based algorithm, the proposed mask image generation algorithm has higher computational efficiency in dealing with complex models. The large-area micro-manufacturing process system overcomes the contradiction between the processing resolution and the processing area of MIP-SLA, and can realize the manufacturing of high-resolution large-area parts. The application scope of art is of great significance to improve the machining accuracy of parts.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH166;TP391.72

【参考文献】