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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).

在本项目中，需要确定焊缝温度场、焊缝形貌与激光焊接塑料构件力学性能之间的因果关系。为此，科学开发并验证了基于拉曼光谱的半结晶材料局部结晶度的空间分辨测量新方法，研究了焊缝结晶度对激光焊接构件短期和长期性能的影响。所要开发的测量方法一方面适用于预测材料分析，以便为随后的连接过程确定材料性能。在激光焊接过程中，可以识别零件局部不同程度的结晶，并通过适当的工艺参数调整进行补偿。另一方面，对激光传输焊接的工艺-结构-性能关系进行分析、认识和优化。在前期工作的基础上，拉曼显微镜还有待进一步发展和验证，以确定局部空间分辨的结晶度。各种半结晶材料（PA6， PP和PE-HD）可用于此目的。在这里，开发一种深度分辨测定聚合物性质的方法是重要的一步。随后，分析了激光焊接试样焊缝结晶程度随不同工艺参数的变化规律。此外，还研究了结晶程度与焊接接头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征焊接过程中的温度场，从而确定温度场参数（最高温度、加热和冷却速度）与结晶程度之间的因果关系。通过适当的辐照策略（通过多次交叉控制冷却，通过激光束的振荡运动产生准静止温度场）来调节焊缝的结晶程度。