Showing papers on "Roller burnishing published in 2007"

Finite Element Modeling of Hard Roller Burnishing: An Analysis on the Effects of Process Parameters Upon Surface Finish and Residual Stresses

Abstract: Hard roller burnishing is a cost-effective finishing and surface enhancement process where a ceramic ball rolls on the machined surface to flatten the roughness peaks The ball is supported and lubricated by hydrostatic fluid in a special tool holder The process not only improves surface finish but also imposes favorable compressive residual stresses in functional surfaces, which can lead to long fatigue life Most research in the past focused on experimental studies There is still a special need for a reliable finite element method (FEM) model that provides a fundamental understanding of the process mechanics In this study, two-dimensional (2D) and three-dimensional FEM models for hard roller burnishing were established The developed 2D FEM model was used to study the effects of process parameters (ie, burnishing pressure, feed rate) on surface finish and residual stresses The simulation results were evaluated and compared to the experimental data Results show that the established FEM model could predict the residual stresses and provided useful information for the effect of process parameters Both FEM and experiments show that burnishing pressure is the most influence, where high burnishing pressure produces less roughness and more compressive residual stress at the surface

The influence of roller burnishing on the fatigue crack propagation in notched round bars—Experimental observations under three-point bending

Abstract: Roller burnishing involves a local plastic deformation on the surface that permits the fatigue strength of structures to be increased. Crack propagation is delayed by the introduction of compressive residual stresses. In this way, the process is particularly useful in the presence of stress concentrators, for example in the fillets of crankshafts or in notched shafts. Crack propagation in round bars has been widely investigated, experimentally and numerically. However, the aim of the present work is to study roller burnished notched shafts (whose groove approaches the fillets of crankshafts) loaded in three-point bending. Experimentally, a sequence of destructive interrupted tests has been performed to obtain the crack kinetics and shapes during fatigue life. Thus, the beneficial influence of roller burnishing has been confirmed on both crack initiation and propagation. Some cracks were even stopped by compressive residual stresses. Otherwise, the crack shape observed was very original : cracks propagated first at the edge of the coupon and then, into the depth of the shaft. Multicracking and crack closure have been pointed out and appear to be of great importance.

Determination of material properties for use in FEM simulations of machining and roller burnishing

Abstract: In machining, Finite Element Method (FEM) simulation is used widely to analyze the effect of process conditions and tool edge design upon cutting variables. Thus, it is possible to investigate material machinability, process economics, and surface quality. One of the most crucial inputs in performing a reliable FEM simulation is the availability of material plastic properties. Special material testing methods are required to consider the high ranges of plastic strain, strain rate and temperature that occur in practical machining conditions (for strain rates up to 106 s-1 and temperatures up to 103 °C). Conventional material testing methods are not suitable. Roller burnishing is a surface finishing process where a ceramic ball (3-12 mm in diameter) freely rolls on the machined surface under a high pressure and flattens the roughness peaks. The ball is hydrostatically supported and lubricated by the pressure fluid. The process improves surface finish, increases microhardness and induces compressive residual stresses on the surface. To implement FEM simulation of roller burnishing process, the flow stress properties of the machined surface layer must be known. Such surface layer properties could be significantly different from the substrate (bulk) material due to severe plastic deformation and possible phase transformation caused by prior machining operations. In this study, two approaches to determine the flow stress data are proposed.

Numerical simulation of fatigue crack propagation in compressive residual stress fields of notched round bars

Abstract: In this paper, the influence of the residual compressive stresses induced by roller burnishing on fatigue crack propagation in the fillet of notched round bar is investigated. A 3D finite element simulation model of rolling has allowed to introduce a residual stress profile as an initial condition. After the rolling process, fatigue loading has been applied to three-point bending specimens in which an initial crack has been introduced. A numerical predictive method of crack propagation in roller burnished specimens has also been implemented. It is based on a step-by-step process of stress intensity factor calculations by elastic finite element analyses. These stress intensity factor results are combined with the Paris law to estimate the fatigue crack growth rate. In the case of roller burnished specimens, a numerical modification concerning experimental crack closure has to be considered. This method is applied to three specimens: without roller burnishing, and with two levels of roller burnishing (type A and type B). In all these cases, the computational finite element predictions of fatigue crack growth rate agree well with the experimental measurements. The developed model can be easily extended to crankshafts in real operating conditions.

The effect of diamond pressing and roller burnishing of unheat treated carbon steel surfaces

Abstract: Diamond pressing (DP) and roller burnishing (RB) processes are surface plastic deformation methods used to improve surface quality (microhardness and surface roughness) In the present work DP and RB tools with a special holder were used to study the effect of DP and RB on the surface texture of three different carbon steels (low, medium, and high) and to compare the both methods The results show that the RB in the case of low carbon steel is better than the DP in terms of its effect on the microhardness and surface roughness, but in the case of the medium and high carbon steel the results depicts that the DP is better than RB in terms of its effect on the microhardness, but the RB is better than DP in terms of its effect on the surface roughness As a result of this study it was found that DP and RB have a great effect on surface texture and RB was found to be better in surface roughness, but DP has better results in surface microhardness relative to ground surfaces Also in this paper micrographs of th

Improvement of Roundness of Cylindrical Parts Using Hybrid Electrochemical Smoothing and Roller Burnishing Process

Abstract: A novel finishing process, which integrates the merits of electrochemical smoothing (ECS) and roller burnishing (RB) is proposed in this research for improving the roundness error of cylindrical parts. This process can be used after various turning operations. Through simple equipment attachments, electrochemical smoothing-roller burnishing (ECS-RB) can follow the machining process on the same turning machine. To explore the optimum combinations of the ECS-RB process parameters in an efficient and quantitative manner, the experiments were designed on the basis of the response surface methodology (RSM) technique. The effect of ECS-RB parameters namely, burnishing force, applied voltage, interelectrode gap and workpiece rotational speed on the roundness error was studied. Experimental results indicate that the combined process effectively improves the roundness error. Therefore, the combination of ECS and RB is a feasible process by which it is possible to minimize geometrical errors.

Influence of Mechanical Surface Treatments on the Fatigue Performance of the Gamma TiAl Alloy Ti-45Al-9Nb-0.2C

Abstract: The effect of shot peening and roller burnishing on the fatigue performance of the γ(TiAl) alloy Ti-45Al-9Nb-0.2C was investigated over a wide range of processing intensities. At optimized conditions shot peening and roller burnishing can markedly improve the fatigue strength at ambient temperatures. For temperatures above 650 °C, the residual compressive stresses induced by shot peening and roller burnishing quickly relax. This indicates that, at elevated temperatures, surface roughness and dislocation strengthening become more important for the fatigue performance of mechanically surface-treated components. Roller burnishing leads to much lower surface roughness than shot peening, resulting in more effective improvement of high temperature fatigue performance. However, surface strengthening by shot peening can also be beneficial for the fatigue performance at elevated temperatures, when the surface roughness is reduced by subsequent polishing.

Bruñido con rodillo en acero AISI 1045

Abstract: Roller burnishing consists in a surface deformation which improves surface hardness, surface finishing, wear resistance, fatigue strength and corrosion strength. A conventional lathe with a single roller burnishing tool was used with1045 AISI carbon steel specimens. The effect of three roller burnishing parameters, force, feed and number of passes on surface finishing, surface hardness, diameter variation and depth of the deformed layer is established. The experimentation was carried out properly lubricated. A complete factorial experimental design was applied, N = 23 The obtained information was processed with the STATGRAPHICS Plus Version 4.1 for Windows statistical software. Mathematical equations relating hardness and roughness increments and diameter diminution as a function of the used variables are presented. It is concluded that roller burnishing lowers roughness, increases surface hardness and diminishes work piece diameter, in decreasing order of influence. The highest surface hardness increase is obtained with the force and feed interaction. In roughness, the greatest effect is feed. The greatest influence on the diameter is the interaction between force and feed.

Crankshaft machine tool test device

Abstract: The invention relates to a device for testing roller burnishing tools for a roller burnishing machine comprising at least one burnishing roller, characterized in that it comprises at least: means (51, 52, 53, 54, 5) for holding and for driving in the roller burnishing machine, which causes the test device (1) to rotate; a roller bearing raceway (22) pressing against said roller, the roller bearing raceway (22) exhibiting symmetry of revolution about the axis of rotation of the device (1), with a profile including a rounded portion; a cylindrical rolling bearing raceway (42) bearing against support wheels of the roller burnishing machine.

Method for evaluating condition of burnishing element

Abstract: PROBLEM TO BE SOLVED: To provide a method for manufacturing component elements having resistance against fatigue and damage, more particularly a method for evaluating a tool to be used for manufacturing the component elements. SOLUTION: This method for evaluating the condition of the roller burnishing element 14 includes abutting of the burnishing element 14 having an unknown condition against a surface and moving of the element 14 according to a test pattern T1 selected in advance; recording of at least a test force profile 30 showing force acting on the burnishing element 14 in at least a dimension, while moving the burnishing element 14; comparing of at least a test force profile 30 to at least a reference force profile 28 to determine a deviation from a baseline condition in the condition of the burnishing element 14. COPYRIGHT: (C)2008,JPO&INPIT

An investigation of multi-roller burnishing process on mild steel and copper metal

Abstract: Burnishing is a chipless machining process. It produces smooth finishing both on round and flat surfaces. It easily produces work hardened surface by plastic deformation of surface irregularities. The burnishing is carried out by pressing a freely rotating hardened ball or roller against a rotating or flat or stationery work piece. The surface roughness is produced by the planetary rotation of ball / roller. The resulting cold working process produce smooth surface roughness, induces compressive strength, resist wear, corrosion resistance and improves fatigue life of the work part. The ball burnishing improves circularity of the work pieces. The burnishing process also improves surface hardness on the work piece surface considerably. Various spindle speeds, feed and depth of penetration are used to perform the experiments. High spindle speed and feed for the same depth of penetration produced lower value in surface roughness. The surface hardness on the surface was also increased by increasing depth of penetration for given spindle rotation and feed. The surface hardness can be increased to certain value, however, there is a limitation.

A metrological study on hardened steel surface finishing using a diamond burnishing tool

Abstract: INTRODUCTION In recent years, manufacturing process that provides with low cost and high speed as well as accuracy and precision has been increasingly required. The processing techniques, which reduce the environmental load such as grinding sludge and lubricant are also desired in the industry. Today, surface burnishing by a diamond tool is the focus of attention from the industrial field. The burnishing process is one of micro plastic working methods, i.e. a special diamond point tool compresses the metal surface to obtain a mirror-like surface finish as well as to improve its surface hardness like shotpeening. Although, the roller burnishing techniques are applied to surface finishing process of aluminum alloy or stainless steel parts in the industrial field, that is not applicable to hard work materials such as quenched hardened steel. Therefore, a Diamond Burnishing process is proposed as a solution for this instance. However the adequate machining conditions to achieve proper surface finish have not been clarified. In order to evaluate the relationship between burnishing conditions and surface texture, practical burnishing tests were carried out under several machining conditions considering burnishing load and feed rate using an NC lathe.