A theoretical and experimental study of single roll burnishing process as applied to yokes

Roller burnishing is a cold working process, that produces a finer surface finish by rotation of hardened rolls over a bored or turned metal surface. In burnishing process, the pressure generated by rolls exceeds the yield point of softer piece part surface at point of contact, resulting a small plastic deformation of the surface structure. The result is a mirror like finish with a strain hardened, wear and corrosion resistant surface.; The research presented in this dissertation is focused on the burnishing process as applied to yokes. The following stages were accomplished: (1) Background research on the burnishing process; (2) Experimental analysis of the process, while using four input parameters and covering multiple output parameters; (3) Based on the results of previous stage, adjustments and modifications of process were made; (4) Analysis and optimization of the fixturing device in order to improve the tolerances of the machined part; (5) A second experimental stage, narrowing the input variables and output parameters according to the findings at stage 1, with an extensive capability of the process analysis; (6) Modeling of the roll and yoke and creating a methodology to calibrate the model using geometrical comparison with experimental resulted surface; (7) Simulation of the process using specialized FEM software, and analysis of the results;; The simulation focused on stress and plastic strain evolution in the subsurface of yoke; while the process parameters are those used in experiments. The stages of simulation are: (1) Develop a viable burnishing model; (2) Calibrate the model; (3) Selection of the main simulation features and parameters; (4) Analysis of the simulation output data.; The major improvements resulting from the experimental work are: (1) The required surface roughness can be achieved in industrial environment; (2) The final diameter tolerance can be obtained by machining with low-costly machining processes;; The consistent output obtained recommends them for further use in the following directions: (1) Optimization of the process from subsurface damages point of view; (2) Use the methodology in future development of elastic-plastic contact specialized software; future use of methodology when certainly improved computing power will product a lot improved results and will permit to accurately predict the roughness; (3) Use the simulation for predict the surface strengthening; (4) Optimization of the process kinematics; (5) Use the methodology for different burnishing methods and optimize the process.