Stress-related process know-how and process optimasiton of plastic welding unsing the example of laser transmission welding

关于塑料焊接质量的评估，现在的重点是考虑通过准静态拉伸剪切试验确定的短期强度。然而，实际部件的不同工作条件会导致不同的应力和应变，例如在激光传输焊缝内。因此，实际中的连接响应与在实验室条件下观察到的不同。在使用中补充准静态加载动态，可能会出现多轴和可能的长时间作用的载荷。目前尚不清楚具有最大短期拉伸剪切强度的焊缝是否也能最好地承受其他载荷。同样未知的是，在不同载荷类型下确定的焊接系数是否彼此相关，因此可以从一种建议到另一种。对于激光透射式焊接，给出了短时焊接因素与长期焊接因素的关联式。结果表明，焊缝短时拉伸剪切强度与长期拉伸剪切强度之间存在线性关系。研究还表明，在焊接过程中，主导条件对焊缝组织形态和强度有较大影响。这种关系显然适用于各种塑料焊接过程，如已记录的类似挤压和热板焊接。因此，该项目的一部分是研究激光传输焊缝根据不同类型的应力和焊接过程的主要温度场的行为。此外，还应澄清是什么导致了可能的偏差。由于决定焊接过程的温度场决定了焊接过程中不同应力状态下的焊接过程、影响材料性能和焊缝强度之间的关系，因此激光透射式焊接有可能为其他塑料焊接工艺提供借鉴，获得可移植的知识。由于激光传输焊接所影响的温度场可以非常灵活地形成，因此激光传输焊接的示例性研究为获得可传递的结果提供了很好的要求。因此，应选择激光透射式焊接作为研究对象。预计对于不同的应力，导致最佳强度的温度场将是不同的。必须从根本上检查和理解造成这种情况的原因。此外，通过激光传输焊接产生的空间和时间变化的温度场应受到影响，以获得最佳的、而不是应力定制的焊缝强度。优化的方法将是使用具有两个离散激光波长的两个光束路径，两者都由高度动态的光束传输组件引导。

On the plastic weld quality evaluation, the focus is now on the consideration of the short term strength determined in a quasi static, tensile shear test. Different operating conditions of real components, however, lead to various stresses and strains, e. g. within laser transmission weld seams. Thus, the connection responses in reality differs from that observed in laboratory conditions. In use complementary to quasi static loading dynamic, multi axis and possibly loads acting for a long time may occur. It is unknown whether welds bearing maximum short term tensile shear strength withstand also other loads optimally. Also unknown is whether determined under different load types weld factors correlate with each other and thus can be possibly suggested from one to the other. Regarding laser transmission welding, a correlation of the short and long term weld factors are jet presented. It turned out that the short and long term tensile shear strength weld seam factors are linearly related. Further it was shown, that in the welding process prevailing conditions influence the morphology and the weld seam strength considerably. A correlation apparently valid for various plastic welding processes, as has been documented similar to the extrusion and hot plate welding.A part of the project is therefore to investigate how laser transmission weld seams behave depending on different types of stress and the welding process prevailing temperature fields. Moreover it should be clarified what causes possible deviations. Are findings on the relationship between the welding process, the effected material properties and the weld seam strength for different stresses attributed to the temperature field determining the welding process, it is possible to take the laser transmission welding as a precedent for other plastic welding process and to gain transferable knowledge. Since the temperature field effected by laser transmission welding can be formed extremely flexible, the exemplary study of laser transmission welding offers very well requirements to gain transferable findings. Therefore laser transmission welding should be chosen for the proposed investigation. It is expected that temperature fields leading to optimal strength for different stresses will be different. The reasons for this have to be examined and understood fundamentally. Furthermore, by laser transmission welding resulting spatially and temporally varying temperature fields shall be affected to achieve optimal rather stress customized weld seam strengths. The approach of optimization will be the use of two beam paths with two discrete laser wavelengths, both guided by a highly dynamic beam delivery component.