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Nikšić, Montenegro

Vukelic D.,University of Novi Sad | Tadic B.,University of Kragujevac | Miljanic D.,Metalik DOO | Budak I.,University of Novi Sad | And 3 more authors.
Tehnicki Vjesnik | Year: 2012

Fixtures which balance cutting forces and torques by the friction forces generated on contact surfaces of locating, clamping elements and workpiece surfaces are widespread in industrial practice. Among other things, these friction contacts are characterized by a certain amount of interface compliance which is a complex function of macro- and microgeometry of contact pairs in the workpiece-fixture system, as well as the clamping and cutting forces. Workpiece machining errors are mostly the consequence of that interface compliance. This paper investigates workpiece-fixture interface compliance in cases where clamping is performed using a standard, and specially designed clamping element. Theoretical considerations are presented, followed by results of experimental investigation. Considerable advantages of the specially designed clamping element compared to its standard counterpart are demonstrated by experiments. The results are a good starting point for a research into optimization of special fixture clamping elements and their wider industrial application. Source

Tadic B.,University of Kragujevac | Todorovic P.M.,University of Kragujevac | Luzanin O.,University of Novi Sad | Miljanic D.,Metalik DOO | And 3 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2013

This paper is focused on the process of ball burnishing. The influence of tool stiffness on surface roughness parameters was considered theoretically, while experimental investigation was conducted to establish the influence of initial surface roughness (previous machining) on the effects of ball burnishing as the finishing process. Experimental investigations were conducted over a wide interval of most influential process parameters (burnishing forces, burnishing feed, and number of burnishing passes). The material used in the experiments was aluminum alloy EN AW-6082 (AlMgSi1) T651. Burnishing was performed using a specially designed tool of high stiffness. Statistical analysis of experimental data revealed strong correlation between roughness, R a, and burnishing force, burnishing feed, and number of passes for the three surfaces, each with different roughness parameters. Particular combinations of process parameters yielded very low surface roughness, R a, equivalent to polishing. It is worth noting that high surface quality can be achieved with relatively small burnishing forces, which differs from the investigations published so far. Contrary to conventional approaches, which are based on elastic tool systems, the authors propose the burnishing process to be conducted with high-stiffness tools. Further investigation shall be focused on optimization of burnishing process parameters in order to achieve surface finish equivalent to high polish. © 2012 Springer-Verlag London Limited. Source

Tadic B.,University of Kragujevac | Vukelic D.,University of Novi Sad | Miljanic D.,Metalik DOO | Bogdanovic B.,University of Kragujevac | And 3 more authors.
Journal of Manufacturing Systems | Year: 2014

This paper is focused on the problem of compliance of interface between clamping/locating fixture elements and workpiece, under dynamic loads during machining. In contrast to previous investigations, the authors have developed a special device dedicated to testing of physical models which represent clamping/locating elements and workpiece. This device allows optimization of a large number of input parameters which are critical to interface compliance. It was used in experimental investigations to establish the impact that the radius of the spherical tip of a clamping/locating element has on the interface compliance and load capacity. The results of experimental investigation show that, under certain conditions, the clamping/locating elements with larger-radius spherical tips provide significantly lower interface compliance. Future investigations should be aimed at finding optimum macro- and micro-geometries of contact interface, as well as the selection of materials for clamping/locating elements. © 2013 The Society of Manufacturing Engineers. Source

Jeremic M.,University of Kragujevac | Matejic M.,University of Kragujevac | Bogdanovic B.,University of Kragujevac | Tadic B.,University of Kragujevac | And 2 more authors.
Tribology in Industry | Year: 2014

This paper is analyzing the impact of the construction element position of ship winch drum on the effects of torque transmission by friction in the mechanization welding process. The driving and driven wheels (construction elements) were examined for the general case of the load distribution. Based on this examination, the construction of the device that should provide the reliable torque transmission and the movement of the drum in the process of its welding are proposed. This construction is characterized by a high level of flexibility and ability to change the friction torque based on changing drum position in regard to the driving and driven wheels (construction elements). With this new construction, problems related to the movement synchronization are avoided, unlike the all previously known constructions of this type, which lead to the positive impact on the wear intensity of friction gears. © 2014 Published by Faculty of Engineering. Source

Vukelic D.,University of Novi Sad | Miljanic D.,Metalik DOO | Randjelovic S.,University of Kragujevac | Budak I.,University of Novi Sad | And 3 more authors.
Materiali in Tehnologije | Year: 2013

This paper deals with the problem of defining the trajectory of a stiff burnishing tool that would be optimal from the point of view of surface quality. The basic goal of this work is to gain an insight into the very process from the microscopic aspect, with the primary focus on material flow and roughness variations. Based on theoretical considerations, we planned an experiment with the aim to verify the initial hypotheses about the analysis of roughness change and a determination of the optimal depth of the workpiece penetration. Through matching and the superposition of surface profiles formed at various contact pressures, i.e., various burnishing forces and various penetration depths of the burnishing ball into the profile roughness, the phenomenon of roughness change was explained. Theoretical assumptions related to a determination of the optimum tool trajectory have largely been confirmed from the point of view of surface quality. The balls within the stiff tool system, which follow a predetermined depth of penetration into the roughness profile, very likely provide optimum surface quality, regardless of the initial machining. Based on experimental results, it is highly possible that the depth of the penetration of tool (burnishing ball) should equal the roughness profile height of the previously machined surface. The analysis of results obtained by the measurement of the surface roughness and the super-positioning of the profiles obtained by burnishing with various burnishing forces, significantly contributed to the explanation of the roughness peaks' deformation phenomenon. The proposed burnishing method could be of special importance in the burnishing of roughly machined surfaces, where Rp reaches high values. Investigations presented in this paper open a number of new directions, such as the testing of a stiff tool system with various workpiece materials and burnishing regimes, with different surface roughnesses as the result of the initial machining. We believe that the proposed model can significantly improve our present knowledge of the burnishing process. Source

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