Basic technological investigation of a new high-performance process for the production of internal threads and microstructure-based characterization of their performance

传统的螺纹加工工艺，如攻丝或成形，占用了零件加工时间的很大一部分。由于定义的螺纹节距，主轴旋转必须与进给轴同步。此外，收缩运动发生在相同的进给量在相反的旋转方向。由于必要的加速和减速过程而导致的时间损失导致了高主时间。在本研究项目的范围内，将开发用于AlSi10Mg铝合金的创新螺纹成形工艺“轴向螺纹成形”的工艺安全概念，以产生高效的可拆卸接头。与传统的螺纹成形方法相比，这种创新的高性能工艺节省了大量的时间，因为螺纹不是连续成形的，而是由刀具的半圈旋转完全产生的。本研究项目的基本目的是掌握轴向螺纹成形的基本知识。然而，新的运动学和刀具设计要求研究加工本身与结果之间的相关性。轴向螺纹成形过程中机械刀具载荷和成形过程的分析与螺纹质量的研究同样重要。将使用黄铜合金CuZn40证明结果可转移到其他材料系统。为了表征内螺纹，需要进一步开发用于研究机械性能的有效测试序列，以确保基于应用优化的物理传感器技术和适当数量的试样的准静态和循环材料行为的详细知识。调查的目的是通过相对较少的样品获得有关螺纹质量和失效机制的尽可能高的信息。特别研究了轴向螺纹成形过程中产生的拉削通道及其在载荷作用下产生的应力增加和重叠减少对机械强度和疲劳寿命的影响。选定的工艺相关参数在加工过程中变化，并使用机械表征方法进行评估。将结果反馈到制造过程中，可以实现资源节约和高效加工。此外，为了对测试结果进行分类，将测试结果与常规螺纹成形生产的螺纹进行比较。内螺纹的工艺相关的几何和微观结构性能与力学性能相关，从而导致基于结构的损伤机理分析，从而产生基于基本工艺-结构-性能理解的最佳工艺条件设计知识库。

Conventional threading processes, such as tapping or forming, take up a large proportion of machining time of a component. Due to the defined thread pitch, the spindle rotation must be synchronized with the feed axis. In addition, the retraction movement takes place at the same feed rate in the reverse direction of rotation. The resulting loss of time due to the necessary acceleration and deceleration processes results in high main times.Within the scope of this research project, a process-safe concept for the innovative thread forming process "axial thread forming" for the aluminum cast alloy AlSi10Mg is to be developed in order to generate highly productive detachable joints. The innovative high-performance process offers enormous time saving potentials in contrast to conventional thread forming methods, since the thread is not formed continuously, but is completely produced by half a revolution of the tool.The basic aim of this research project is to acquire a basic knowledge of axial thread forming. The novel kinematics as well as the tool design, however, require the investigation of correlations between the machining itself and the result. The analysis of the mechanical tool loads as well as the forming processes during axial thread forming are just as important as the investigation of the thread quality. The transferability of the results to other material systems will be demonstrated using the brass alloy CuZn40.In order to characterize the internal threads, efficient test sequences for the investigation of the mechanical properties are to be further developed, which guarantee detailed knowledge of the quasi-static and cyclic material behavior based on application-optimized physical sensor technology with an appropriate number of specimens. The aim of the investigations is to obtain the highest possible information about the thread quality and the failure mechanisms with a relatively small number of specimens. In particular, the influence of the broaching channels generated during axial thread forming and the associated stress increase under load as well as the reduced overlap on the mechanical strength and fatigue life are investigated. Selected process-relevant parameters are varied during machining and evaluated using mechanical characterization methods. The feedback of the results into the manufacturing process enables resource-saving and efficient machining. In addition, the results are compared with threads produced conventionally by thread forming in order to classify the test results.The process-related geometric and microstructural properties of the internal threads are correlated with the mechanical properties, which results in a structure-based analysis of the damage mechanisms to generate a knowledgebase for the design of optimum process conditions based on a basic process-structure-property-understanding.