High-strength gears produced by powder metallurgical processes

对于齿轮的制造，可以应用几种工艺链。粉末冶金生产是一个资源效率高的工艺链，由模压、烧结、致密化轧制和表面硬化组成。通过节能制造和低材料使用，最大限度地减少了制造资源的使用。与完全致密的齿轮相比，具有相当强度的表面致密粉末冶金齿轮的重量减少了10%。这也有助于提高资源效率。拟议的研究项目旨在提高材料使用率和负载合适的边界层，以优化零件设计。因此，该项目直接解决了优先计划资源高效机器元件（SPP 1551）的目标。该项目的目标是通过全面优化粉末冶金齿轮生产来提高齿轮的资源效率。为此，将通过预测齿根强度来优化齿根几何形状和表面密度分布。因此，不同的密度分布被认为是确定最佳的齿根几何形状和预测其强度。对于后者，使用第一阶段制定的方法。通过实验值与理论值的比较，验证了齿根疲劳强度预测方法的正确性。此外，粉末冶金制造，表面致密化齿轮的可变齿几何形状的潜力进行了评估。它将被调查，齿的几何形状是适合的表面致密化通过轧制。此外，喷丸作为一种替代致密化工艺的潜力进行了评估。喷丸强化提供了致密化几何形状的可能性，这些几何形状是不可滚动的。此外，预测齿根疲劳强度的方法被扩展到预测滚动强度以及。载荷和强度的局部比较将扩展到具有密度和碳含量轮廓的材料的赫兹接触。优先计划资源高效机器元件（SPP 1551）内的合作将用于应用其他项目的选定方法，以在过程链上产生边界层，从而生产PM齿轮。将确定和研究产生附面层的适当工艺。这将进一步提高齿轮使用期间的资源效率。强度和工艺链的比较将导致资源效率的验证。

For manufacturing of gears several process chains can be applied. A process chain with high resource efficiency is a powder metallurgical production, which is composed by die pressing, sintering, densification rolling and case hardening. Manufacturing resource employment is minimized by energy efficient manufacturing and low material usage. Surface densified PM gears with a comparable strength have a 10% reduced weight compared to fully dense gears. This also contributes to resource efficiency.The proposed research project targets an improved material usage and a load suitable boundary layer for optimization of part design. Hence the project directly addresses the objectives of the Priority Program Resource efficient machine elements (SPP 1551)The objective of this project is the increase of resource efficiency of gears by a holistic optimization of the powder metallurgical gear production. For that an optimization of tooth root geometry and surface density profile by prediction of tooth root strength will be performed. Therefore, different density profiles are considered for the determination of the optimal tooth root geometry and the prediction of its strength. For the latter, the methodology developed in phase 1 is used. By comparison of experiment and theoretically determined values the methodology to predict tooth root endurance strength is verified. Furthermore, the potential of variable tooth geometries for powder metallurgical manufactured, surface densified gears is evaluated. It will be investigated, which tooth geometries are suitable for surface densification by rolling. Furthermore, the potential of shot peening as an alternative densification process is evaluated. Shot peening offers the possibility to densify geometries, which are not rollable. Additionally, the methodology to predict tooth root endurance strength is extended to predict the rolling strength as well. The local comparison of load and strength will be extended to Hertzian contact for a material with profile of density and carbon content.The cooperation within Priority Program Resource efficient machine elements (SPP 1551) will be used to apply chosen methods of other projects to generate boundary layers onto the process chain to produce PM gears. Suitable processes for generating boundary layers are to be identified and investigated. This shall result in a further increase of resource efficiency during the gears usage. Comparison of strength and process chains will result in a verification of resource efficiency.