In recent years, extensive research has been carried out on the influence of tool and process design on tool wear for bevel gear cutting. However, due to the complex interactions between tool, gear and process design, an analytical analysis of the cutting process has proven difficult. In this paper, the influence of the tool design on tool wear in continuous bevel gear manufacturing is analyzed using both simulations and cutting trials. Initially, a theoretical analysis is performed using a manufacturing simulation and a method is derived to calculate the effective tool angles. Subsequently, the results of cutting trials using the same tool designs are presented and compared to the simulation results.

In gear hobbing, as in other soft machining processes, it is essential to maintain the required workpiece quality to avoid rejects or increased rework. To track the workpiece quality, the manufactured gears usually have to be measured on a measuring machine. In order to ensure workpiece quality even with long measuring intervals, process monitoring offers an approach to check the gear quality already during the manufacturing process. In this report, the potential of acceleration data with regard to the assessment of workpiece quality is investigated. In this investigation, both analytical and artificial intelligence based methods are considered. (c) 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)

Gear skiving is a flexible and productive process for the manufacturing of internal and external gears. Due to the variable cutting conditions and the complex process kinematics, a simulative investigation of the skiving process is necessary for an efficient and economic process design. The plane-based penetration calculation is an established method for simulating the machining of gears. In this paper, this simulation approach is validated based on experimental results for the gear skiving process of internal gears. For almost all simulation results, the results of the gear skiving simulation for internal gears agreed with the experimental results. (c) 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)

Specifically designed modifications of the involute of gears can positively influence the excitation behavior and the load carrying capacity of the gear. The standard modifications are mathematically described by linear and quadratic functions. Modifications that can be described by functions of higher order are called topological modifications. Gears featuring topological modifications not only exhibit improved excitation behavior compared to gears with standard modifications, but also an improved load carrying capacity. Modifications are usually applied in the final manufacturing step, e.g. by generating grinding, profile grinding or hard skiving. A method for applying topological modifications to gear flanks using a kinematic adaptation of the gear skiving process is presented in this paper. For this purpose a converter was developed that enables a transfer of any kinematics to machine control in order to manufacture modifications using the gear skiving process. The skiving process involves the removal of material from the gear flanks using a cutting tool. By controlling the kinematic variables of the process, it is possible to selectively shape the gear flanks in a precise and controlled manner. This approach allows the design and manufacture of customized gear shapes that can improve the performance of the gear system. The effectiveness of the method developed in this work is demonstrated through the experimental application of topological modifications. (c) 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)

The aim of this study is to use a Shapley value-based machine learning algorithm to investigate the cross-process chain impacts of the processes involved in a pinion shafts manufacturing chain on final gear quality with sustainability considerations. Process data is collected during gear hobbing and profile grinding and analyzed using a neural network model to calculate Shapley values. The results quantify the influence of process parameters and trace data of each process on the gear quality, thereby improving understanding and leading to better control and sustainability of processes within the manufacturing chain. By achieving better process control and evaluating sustainability, this study not only helps to save time, energy, and material resources but also promotes sustainable manufacturing practices that minimize waste and the environmental impact of gear production. Overall, this study provides valuable insights into the importance of processes in the gear manufacturing chain, aiding in its optimization.

Due to near netshape production, powder metallurgically manufactured (PM) gears have a high potential to increase cost and resource efficiency. Compared to conventionally machined gears, the advantages of PM gears are the different local density distribution in the component and the potential integration of secondary design elements. These advantages are accompanied by the reduction of weight and the possibility of optimizing the NVH-behavior of a gear. PM gears may be manufactured by both, die pressing and additive manufacturing (AM). The powder bed-based additive manufacturing processes for metals can be classified into binder-based (e.g. Binder Jetting, BJT) and beam-based thermal processes (e.g. Laser Powder Bed Fusion, LPBF). Due to the specific process technology, the manufacturing of PM gears by die pressing is only economical for large batch sizes in series production. For small batches, AM offers an approach to manufacture gears that meet the requirements in terms of quality, strength, acoustics and economic efficiency of the manufacturing process.This report describes the potential of BJT gears made of stainless steel 17-4PH (X5CrN-CuNb16-4) with a relative density of rho(0,rel) approximate to 99% regarding the tooth bending strength. The reliability of the process and thus the tooth bending strength can be increased further by a specific adjustment of process parameters. Subsequently, the gears are tested with regard to the tooth bending strength on the pulsator test rig. The results are summarized in a SN-curve.

Due to near netshape production, powder metallurgically manufactured (PM) gears have a high potential to increase cost and resource efficiency. Compared to conventionally machined gears, the advantages of PM gears are the different local density distribution in the component and the potential integration of secondary design elements. These advantages are accompanied by the reduction of weight and the possibility of optimizing the NVH-behavior of a gear. PM gears may be manufactured by both, die pressing and additive manufacturing (AM). The powder bed-based additive manufacturing processes for metals can be classified into binder-based (e.g. Binder Jetting, BJT) and beam-based thermal processes (e.g. Laser Powder Bed Fusion, LPBF). Due to the specific process technology, the manufacturing of PM gears by die pressing is only economical for large batch sizes in series production. For small batches, AM offers an approach to manufacture gears that meet the requirements in terms of quality, strength, acoustics and economic efficiency of the manufacturing process. This report describes the potential of BJT gears made of stainless steel 17-4PH (X5CrN-CuNb16-4) with a relative density of ρ 0,rel ≈ 99% regarding the tooth bending strength. The reliability of the process and thus the tooth bending strength can be increased further by a specific adjustment of process parameters. Subsequently, the gears are tested with regard to the tooth bending strength on the pulsator test rig. The results are summarized in a SN-curve.

During generating gear grinding, a large portion of the energy generated is converted into heat that can flow into the gear. To better control the heat flowing to the gear, an energy distribution model was developed, which considers chip formation mechanisms of each grain of the grinding worm. The energy distribution calculation requires knowledge of micro-interaction characteristics of grains engaging with the gear. In this paper, a simulation model of generating gear grinding is developed, considering grains micro-interaction characteristics during the process. Ultimately, the calculation of energy distribution is performed, contributing to better knowledge of heat flow into the gear.

Zur Steigerung der Zahnflankentragfähigkeit werden Zahnräder vermehrt fein- oder poliergeschliffen. Allerdings existieren bislang keine Erkenntnisse darüber, welchen Einfluss die Prozesse bei gleicher Zahnflankenrauheit auf das Einlaufverhalten von Verzahnungen haben. To increase the load carrying capacity of tooth flanks, gears are increasingly fine- or polish-ground. However, there is hardly any knowledge about how these processes influence the running-in behavior of gears with the same tooth flank roughness.

Grinding is an established process for gear manufacturing, as good geometric and surface quality can be achieved. For bevel gears, grinding is used in case of high demands on accuracy and reproducibility. In industry, design of bevel gear grinding processes is usually based on experience. An efficient design of grinding processes can be performed based on the cutting force. Knowledge of the cutting force is necessary to predict the process influence on the workpiece and the wear of the grinding tools. For bevel gear grinding, no cutting force models exist. To model the cutting force in grinding processes, the contact conditions must be known. In this report, a model of the geometric contact conditions in bevel gear grinding is presented. The model is validated by comparing the simulated bevel gear flank with the ideal flank. Finally, the relation between simulation and measured process loads is analyzed.

Aufgrund steigender Anforderungen an den Wirkungsgrad und die Geräuschanregung von Zahnradgetrieben ist die Hartbearbeitung von Zahnrädern für viele Anwendungen zu einem notwendigen Prozessschritt geworden. Die Hartfeinbearbeitung durch Schleifen ist ein etabliertes Herstellungsverfahren für verschiedene Arten von Zahnrädern, da eine gute Qualität der Geometrie und der Oberfläche erreicht werden kann. Das Schleifen wird bei Kegelrädern insbesondere bei hohen Qualitätsanforderungen eingesetzt. Die Kenntnis der Schleifkraft ist von wesentlicher Bedeutung für die Vorhersage der Randzoneneigenschaften und der Belastung des Schleifwerkzeugs. Daher spielt die Kenntnis der Schleifkraft eine wichtige Rolle bei der wissensbasierten Prozessauslegung. Für das Kegelradschleifen existieren jedoch keine Modelle zur Vorhersage der Schleifkraft. Frühere Untersuchungen haben gezeigt, dass die Berechnung der Schleifkraft auf der Grundlage theoretischer Kontaktbedingungen und des Modells nach Werner nicht der gemessenen Prozesskraft entspricht. Diese Diskrepanz kann mit der elastischen Verformung des Systems zusammenhängen. In der vorliegenden Arbeit werden elastische Effekte beim tauchenden Kegelradschleifen untersucht. Zunächst wird der charakteristische Verlauf der Werkzeugspindelleistung und der Schleifkraft in Abhängigkeit von der Zustellung bestimmt. Anschließend wird der Zusammenhang zwischen der Kraft und der elastischen Verformung analysiert. Die vorgestellte Arbeit soll dazu beitragen, den Einfluss elastischer Effekte beim tauchenden Kegelradschleifen zu verstehen.

On universal milling machines, bevel gears can be produced with standard end mills. Due to the flexible process kinematics, there are fewer restrictions with regard to implementable component geometries compared to conventional gear-cutting processes. The quality requirements for bevel gears allow deviations of only a few micrometers. For this reason, small production-related deviations can lead to the exceedance of the permissible tolerances. Furthermore, surface integrity is decisive for the load-carrying capacity of gears. In this report, the influence of the process on the bevel gear quality and the properties of the near surface zone is analyzed.

Due to rising requirements concerning efficiency and noise excitation of gear drives, the hard finishing of gears has become a necessary process step for many applications. The hard finishing by grinding is an established manufacturing process for various types of gears, as good geometric and surface quality can be achieved. For bevel gears, grinding is used especially to machine gears with high quality requirements such as for automotive axle drives. The knowledge of the grinding force is essential for the prediction of the properties of the near surface zone as well as the load on the grinding tool. Therefore, the prediction of the grinding force is fundamental for a knowledge-based process design. For the process of bevel gear grinding, no models for the calculation of the force exist. The objective of the project DFG KL 500/187-1 is consequently the development of a force model for bevel gear grinding. In this paper, a method to determine and evaluate the grinding force in plunging bevel gear grinding as a basis for future force modelling is presented.

Tools and workpieces in bulk metal forming processes such as electro-assisted upsetting or hybridized solid forward extrusion are subjected to electrical and thermo-mechanical loads. Existing electric contact models like the one of Holm do not regard the complex electro-thermo-mechanical interactions in the contact area between tool components and workpiece. Based on experimental as well as numerical analyses, this work introduces a new electro-thermo-mechanical contact model that accounts for electro-thermo-mechanical load profiles. The load profiles consist of mechanical loads that are typical for bulk metal forming processes. Therefore, it allows accounting for the influence of surface smoothing and lubrication expulsion on electric and thermal contact parameters. Upsetting experiments were performed in order to analyze the influence of lubrication on surface smoothing. All experiments were executed using cylindrical Cf53 workpieces, which were shot peened and lubricated with BERUFORGE 190. Pressure-dependent surface characterization profiles were derived and implemented in the model. The elaborated model of the electro-thermo-mechanical contact is coupled with Abaqus Software by means of user-defined thermal and electrical contact behavior. The resistance heating experiments were performed on the same workpieces to experimentally define the heating time and reached temperature. The numerical simulations of the performed resistance heating tests are used to verify the thermo-electrical part of the model. The mechanical part of the model is validated by means of electro-assisted upsetting tests data reported in the literature.