P. Saravanakumar

Bio: P. Saravanakumar is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Honing. The author has an hindex of 1, co-authored 1 publications receiving 13 citations.

Modelling of fluid continuum considering 3D surface parameters in hydraulic assemblies

Abstract: Friction in servo hydraulic assemblies reduces the response characteristics of the system. The friction is influenced by various factors including the geometry (form and surface errors) of the sliding surfaces. In this work, functionally significant 3D surface parameters from the Birmingham parameters are investigated for reduced friction. A 3D surface modelling approach is presented using random process modelling as the basis. An exponential decay areal autocorrelation function is used to model the grinding and honing processes which are commonly employed for the manufacture of the hydraulic assemblies. Honed surface is modelled with the crosshatches of appropriate angle. Method of surface modelling is validated using the data obtained through measurements on a practical surface. Different surface maps with varying surface parameters of the ground and honed surfaces are generated. The fluid continuum gap geometries of the hydraulic assemblies are modelled using these surface maps as envelopes. Pressure distribution, velocity and viscous friction force are used as measurands of the frictional characteristics. Using computational fluid dynamics (CFD) approach, these measurands are evaluated for different functionally significant Birmingham parameters. Based on further analysis, negative skewness, lower kurtosis values, higher valley fluid retention index were found to have lower frictional characteristics.

Numerical generation of anisotropic 3D non-Gaussian engineering surfaces with specified 3D surface roughness parameters

Abstract: Three-dimensional surface roughness of mating parts of engineering assemblies has a significant influence on their functional behaviour. Studies on load bearing capacity in elastohydrodynamic contacts, gap flow analysis in precision hydraulic assemblies using modeled 3D fluid continuum micro gap geometry, etc., have made it possible to quantify the effect of certain 3D surface roughness parameters on frictional behaviour of the assemblies. This set forth the need for artificially generated three-dimensional engineering surfaces having prescribed roughness values for a better understanding and prediction of tribological problems. In this paper, an algorithm is developed for the numerical generation of three-dimensional anisotropic surfaces with prescribed 3D surface roughness parameters. The procedures employ either the Non-linear Conjugate Gradient Method (NCGM) or 2-D Digital Filter method. The results show that both the methods can adequately produce surfaces at small correlation distances, while at higher correlation distances the NCGM yields better results. Comparison between model-simulated output and measurement results of three-dimensional surface roughness of engineering surface show a good match, supporting the validity of the model.

Characterization of 3D surface topography in 5-axis milling

Abstract: Within the context of 5-axis free-form machining, CAM software offers various ways of tool-path generation, depending on the geometry of the surface to be machined. Therefore, as the manufactured surface quality results from the choice of the machining strategy and machining parameters, the prediction of surface roughness in function of the machining conditions is an important issue in 5-axis machining. The objective of this paper is to propose a simulation model of material removal in 5-axis based on the N-buffer method and integrating the Inverse Kinematics Transformation. The tooth track is linked with the velocity giving the surface topography resulting from actual machining conditions. The model is assessed thanks to a series of sweeping over planes according to various tool axis orientations and cutting conditions. 3D surface topography analyses are performed through the new areal surface roughness parameters proposed by recent standards.

Model for the prediction of 3D surface topography in 5-axis milling

Abstract: The paper deals with the prediction of the 3D surface topography obtained in 5-axis milling in function of the machining conditions. For this purpose, a simulation model for the prediction of machined surface patterns is developed based on the well-known N-buffer method. As in sculptured surface machining the feed rates locally vary, the proposed model can be coupled to a feed-rate prediction model. Thanks to the simulation model of 3D surface topography, the influence of the machining strategy on resulting 3D surface patterns is analyzed through an experimental design. Results enhance the major influence of the tool inclination on 3D topography. Surface parameters used in the study are strongly affected by the variation of the yaw angle. The effect of the feed rate is also significant on amplitude parameters. Finally, the analysis brings out the interest of using surface parameters to characterize 3D surface topography obtained in 5-axis milling.

Characterization of 3D surface topography in 5 axis milling

Abstract: Within the context of 5-axis free-form machining, CAM software offers various modes of tool-path generation, depending on the geometry of the surface to be machined. Therefore, as the manufactured surface quality results from the choice of the machining strategy and machining parameters, the prediction of surface roughness in function of the machining conditions is an important issue in 5-axis machining. The objective of this paper is to propose a simulation model of material removal in 5- axis based on the N-buffer method and integrating the Inverse Kinematics Transformation. The tooth track is linked to the velocity giving the surface topography resulting from actual machining conditions. The model is assessed thanks to a series of sweeping over planes according to various tool axis orientations and cutting conditions. 3D surface topography analyses are performed through the new 3D roughness parameters proposed by recent standards.

Simulation of textured surface topography during a low wear process

Abstract: Wear experiments were conducted on a block-on ring tester. The stationary block made from cast iron of 50 HRC hardness was ground. The rotated ground ring was made from 42CrMo4 steel of 32 HRC hardness. The rings were modified by a burnishing technique in order to obtain surfaces with oil pockets. Oil pockets of spherical and of drop shape were tested. The correlation and regression analysis of parameters of textured surface topography was carried out. Two sets of surfaces were analysed: after machining and after “zero-wear”. As the result of analysis, minimum number of parameters describing this surface kind was obtained. A simple truncation model of the ring surface change was used. Worn surface topographies, after a low wear, were also modeled in a different way. An idea of the proposed method of surface topography modeling is imposition of random surface of Gaussian ordinate distribution on the base surface (after burnishing). The modeled surfaces were correctly matched to the measured surfaces in 90% of all analysed cases. Basing on the simulation, the local wear values during a low wear process were calculated and compared with experimental ones.