The Effects of Roller Burnishing Parameters Upon Surface Properties of AISI 52100 Bearing Steel (60HRC). A Finite Element Analysis -Edición Única
Jasso Lucio, Francisco
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This thesis is based on the technical report HPM/ERC/NSM-05-R39 which was written in collaboration with the Engineering Research Center for Net Shape Manufacturing (ERC/NSM) [Jasso et. al, 2005a]. The author of this thesis spent some time on a research stance working at The Ohio State University in a roller burnishing project. Most part of the work presented in this document was conducted during that time. Hard roller burnishing is a cost effective surface finishing/enhancement process where a hard ball rolls on the machined surface under a high pressure and flattens the roughness peaks. Particularly when combined with hard turning, this process is able to provide a good alternative to abrasion-based finishing methods such as grinding operations. In this study, two main tasks were conducted, including 1) modifications of FEM modeling of roller burnishing from Yen’s model [Yen, 2004] and 2) FEM simulations to analyze the effect of roller burnishing parameters by using real process conditions selected from experiments previously conducted by the ERC/NSM) [Sartkulvanich, 2004b]. Specifically, the contents of each chapter of this thesis can be summarized as follows. Chapter 1 provides an introduction, which includes the description of roller burnishing process, advantages and challenges encountered in the use of roller burnishing to replace grinding. Overall and specific objectives are discussed in Chapter 2. Chapter 3 provides a literature review on roller burnishing research. It is mainly divided into three major topics, i.e. experimental study on the surface improvement by roller burnishing process, experimental study on the effect of burnishing process parameters, and modeling of roller burnishing. iii SUMMARY Chapter 4 summarizes the details of hard turning and roller burnishing experiments, conducted by the ERC/NSM. Information of experimental procedure and experimental data are given in this chapter. In addition to the data presented in [Sartkulvanich, 2004b], data from experimental measurements of residual stresses on hard turned and burnished AISI 52100 surfaces (obtained by X-ray diffraction technique) are also provided in this chapter. Chapter 5 presents the modifications made for the previously developed FEM model of roller burnishing in [Yen, 2004]. These include consideration of flow stress models from ball indentation tests, consideration of pressure loss during roller burnishing operation, selection of a workpiece size for the FEM model, determination of maximum ball penetration depth during roller burnishing, and evaluation of tool movement control in the 2D FEM model proposed by [Yen, 2004]. Chapter 6 discusses the FEM predicted results on the effects of the burnishing feeds and burnishing pressures upon surface properties. The predictions of surface finish and residual stresses are the focus of this analysis. FEM results were also compared with experimental data for validation. In summary, hard roller burnishing shows two main improvements on burnished workpieces: surface roughness reduction, and increase in compressive residual stresses beneath the surface. The effect of burnishing pressure is the most significant. Higher burnishing pressure produced smoother surface and more compressive residuals stress. Smaller burnishing feed provides similar surface improvements but to a less degree. Quantitatively, FEM results match well with the experiments for the residual stresses but not with the surface roughness parameters. Chapter 7 presents the author’s personal contributions, the findings of this study, some suggestions for further research on hard turning and roller burnishing as well as the application perspectives for this processes’ combination by the Mexican Industry.