Investigation of Mechanical Loads Distribution for the Process of Generating Gear Grinding

In grinding, interaction between the workpiece material and rotating abrasive tool generates high thermo-mechanical loads in the contact zone. If these loads reach critically high values, workpiece material properties deteriorate. To prevent the material deterioration, several models for thermomechanical analysis of grinding processes have been developed. In these models, the source of heat flux is usually considered as uniform in the temperature distribution calculation. However, it is known that heat flux in grinding is generated from frictional heating as well as plastic deformation during the interaction between workpiece material and each grain from the tool. To consider these factors in a future coupled thermomechanical model specifically for the process of gear generating grinding, an investigation of the mechanical load distribution during interaction between grain and workpiece material considering the process kinematics is first required. This work aims to investigate the influence of process parameters as well as grain shape on the distribution of the mechanical loads along a single-grain in gear generating grinding. For this investigation, an adaptation of a single-grain energy model considering the chip formation mechanisms is proposed. The grinding energy as well as normal force can be determined either supported by measurements or solely based on prediction models.

Dry Generating Gear Grinding: Hierarchical Two-Step Finite Element Model for Process Optimization

Recent developments in the automotive industry have led to more stringent requirements for transmission gear quality. This aspect, combined with a massive increase in the number of gears produced per year, has seen generating grinding become the finishing method of choice for mass production of gears. Due to the intrinsic nature of grinding, this process remains the only manufacturing phase that still requires the widespread use of lubricant. With the aim of improving the environmental sustainability of this process chain, recent attempts at performing dry grinding without lubricant have highlighted the critical aspect of thermal damage produced under these conditions. In the present work, a two-step finite element modeling approach is presented for predicting thermal damage during dry generating gear grinding. Grinding forces and thermal energy generated by the interaction of a single grain with the workpiece are first calculated based on real grain geometry acquired via computed tomography. Results of this single-grain model are then applied at a gear tooth level together with process kinematics to determine the temperature distribution during dry generating grinding. Single-grain and generating grinding tests are performed to verify the predicted onset of thermal damage and the ability to optimize process parameters using the proposed hierarchical modeling approach.