Development of 3D joining surface geometries for shaft hub connections manufactured by lateral extrusion

工程应用中的装配式或形状锁定轴毂连接通常由成品部件形成。然而，简单的组装过程需要间隙，这通常会对连接造成有害影响。例如，冷接合连接件受到操作间隙的影响，并且在交变载荷下遭受微动腐蚀和过早失效。另一方面，热接合连接涉及对已经硬化的部件进行再回火的风险。最近的发展揭示了通过塑性变形产生轴毂连接而没有上述缺点的可能性。例如，内部高压装配已经在汽车制造中用于不同的部件，但该过程仅适用于相对薄且均匀的中空轴。然而，IFU和项目合作伙伴IKTD的初步研究表明，通过横向挤压连接多个阶梯轴是可行的。在以下研究中，也取得了有希望的结果，这种连接的传输能力。因此，在同时产生保持接合压力的情况下进行冷接合的可能性是特别有利的。此外，不再需要连接几何形状的精密公差，因为轴在初始状态下保持未加工。然而，不利的是，在接触表面几何形状的设计中不考虑由于侧向挤压工艺而导致的凸形轴几何形状。因此，不均匀的模具填充和接头压力分布中产生的连接，这导致在循环载荷下增加的微动磨损。在拟议的项目中，将考虑在接触面几何形状的精细设计中使用全新的方法来忽略连接过程的影响。通过引入内毂几何形状的三维设计，实现了连接的完全成型和受控的接头压力修改。因此，微动磨损可以被最小化，并且可以利用现有的潜力进一步增加静态和动态传输能力。通过充分考虑材料性能的耦合模拟方法，包括塑性变形模拟和结构模拟，一个通用的几何设计模型，它考虑到几何形状，材料，工艺和应用要求，因此是有效的，在广泛的应用领域。

Frictional or form locking shaft-hub-connections for engineering applications are usually created by finished components. However, a straightforward assembly process requires clearance, which often causes harmful effects on the connection. For instance, cold joined connections are subject to operating clearance and suffer from fretting corrosion and premature failure under alternating loads. Warm joined connections on the other hand involve the risk of retempering already hardened components. Recent developments reveal possibilities of creating shaft-hub-connections by plastic deformation without the mentioned disadvantages. As an example, internal high pressure assembly is already implemented for different components in car manufacturing, but this process is only practicable for relatively thin and uniform hollow shafts. However, preliminary studies by IFU and project partner IKTD showed the feasibility of joining multiply stepped shafts by lateral extrusion. Promising results for the transmission capability of such connections were also achieved during following studies. Hereby, the possibility of cold joining with the simultaneous creation of a maintaining joint pressure is especially advantageous. In addition, close tolerances for the connection geometry are no longer needed, as the shaft remains unmachined in the initial state. However, it is disadvantageous that the convex shaft geometry, as a result of the lateral extrusion process, is not considered in the design of the contact surface geometry. Hence, inhomogeneous mold filling and joint pressure distribution are generated in the connection, which lead to increased fretting under cycling loads. In the proposed project the disregarded effects of the joining process will be considered in the fine design of the contact surface geometry with a fundamentally new approach. By introducing a three-dimensional design of the inner hub geometry, complete form-filling and controlled joint pressure modification are pursued for the connection. Hence, fretting can be minimized and the existing potentials for further increase of static and dynamical transmission capabilities can be exploited. Via thorough consideration of material properties in a coupled simulation methodology, including plastic deformation simulation and structural simulation, a universal model for geometry design is to be developed, which takes into account geometry, material, process and application requirements and is thus valid in an extensive field of application.