Analysis of the interactions between the morphology and the properties of weld seams during laser transmission welding of plastics by a three-dimensional, spatially re-solved determination of the crystallinity of the weld seam by means of Raman microscopy

通过拉曼显微镜对焊缝结晶度进行三维空间分辨率测定，分析塑料激光透射焊接过程中焊缝形态和性能之间的相互作用

基本信息

批准号：
399619237
负责人：
Professor Dr.-Ing. Michael Schmidt
金额：
--
依托单位：
Lehrstuhl für Photonische Technologien (LPT)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2018
资助国家：
德国
起止时间：
2017-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/399619237?language=en
关键词：
Analysis interactions between morphology properties

项目摘要

In this project, the cause-and-effect relationships between the temperature field present in the weld seam, the weld seam morphology and the mechanical properties of laser-welded plastic components are to be determined. For this purpose, a new spatially resolved measuring method based on Raman spectroscopy for the determination of the local degree of crystallization in semicrystalline materials is to be scientifically developed and qualified, and the influence of the degree of crystallization in the weld seam on the short-term and long-term properties of laser-welded components is investigated. The measurement method to be developed is suitable, on the one hand, for the predictive material analysis in order to determine material properties for the subsequent joining process. Local different degrees of crystallization can be identified in the component and compensated by a suitable process parameter adjustment during laser beam welding. On the other hand, process-structure-property relationships in laser transmission welding are to be analyzed, understood and optimized.Based on preliminary work, the Raman microscopy is to be further developed and validated for the determination of locally spatially resolved crystallization degrees. Various semi-crystalline materials (PA6, PP and PE-HD) are to be used for this purpose. Here, the development of an approach for the depth-resolved determination of polymer properties is an important step. Subsequently, the degree of crystallization in the weld seam of laser welded test specimens is to be analyzed as a function of different process parameters. Furthermore, relationships between the degree of crystallization and the short-term and long-term properties of the weld connection are investigated. A thermal FEM model of the laser transmission welding process is intended to represent the temperature field during the welding process and thus to determine the cause-and-effect relationships between the parameters of the temperature field (maximum temperature, heating and cooling rate) and degree of crystallization. The degree of crystallization in the weld seam is to be adjusted by adapted irradiation strategies (controlled cooling by multiple crossings, generation of quasi-stationary temperature fields by oscillating movement of the laser beam).

在该项目中，需要确定焊缝中存在的温度场、焊缝形态和激光焊接塑料部件的机械性能之间的因果关系。为此，需要科学开发并鉴定一种基于拉曼光谱的空间分辨测量方法，用于测定半晶材料的局部结晶度，以及焊缝结晶度对短路的影响。研究了激光焊接部件的长期性能。一方面，待开发的测量方法适用于预测材料分析，以确定后续连接过程的材料特性。可以识别部件中的局部不同程度的结晶，并在激光束焊接期间通过适当的工艺参数调整进行补偿。另一方面，需要分析、理解和优化激光透射焊接中的工艺-结构-性能关系。在前期工作的基础上，将进一步开发和验证拉曼显微镜，用于确定局部空间分辨结晶度。为此目的将使用各种半结晶材料（PA6、PP 和 PE-HD）。在这里，开发一种深度分辨测定聚合物性能的方法是重要的一步。随后，将分析激光焊接试样焊缝的结晶程度作为不同工艺参数的函数。此外，还研究了结晶度与焊接连接的短期和长期性能之间的关系。激光透射焊接过程的热有限元模型旨在表示焊接过程中的温度场，从而确定温度场参数（最高温度、加热和冷却速率）与程度之间的因果关系的结晶。焊缝的结晶程度可通过适当的照射策略进行调整（通过多个交叉点控制冷却，通过激光束的振荡运动产生准稳态温度场）。