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Eibar, Spain

Tzanakis I.,Bournemouth University | Conte M.,IK4 Tekniker | Hadfield M.,Bournemouth University | Stolarski T.A.,Brunel University
Wear | Year: 2013

This study investigates the contact temperatures caused by frictional heating of sliding parallel pairs. In this case the materials studied are a PTFE composite in contact with a high carbon steel plate. These materials are commonly used for industrial applications, in particular as the main contacting components within a scroll expander system. The expected contact temperature values are important to be quantified in order to predict failure mechanisms associated with excessive thermal effects caused by sliding friction. A rational and coherent interpretation of the thermal effects on the actual tribological contact is presented.Contact temperatures are monitored continuously using a high-precision infrared thermal imaging technique with a systematic variation in surface roughness of the high carbon steel material. These surface temperatures are investigated as a function of the friction coefficient, the sliding velocity and the applied load while the most influential parameter for the temperature rise is determined. Analytical results using conventional mathematical methodology are also produced. The analytical and experimental findings are then compared indicating interesting correlations within the macro- and micro-surface temperature regimes and the experimental conditions. Microscopic observations show that thermal effects can seriously affect fibers durability while transfer films formed across the steel counterpart can be beneficial for the operation of scroll systems under specific roughness and test conditions. © 2013.


Nevshupa R.,IETCC CSIC | Conte M.,IK4 Tekniker | Van Rijn C.,Noon Energy S.L.
Measurement Science and Technology | Year: 2013

The measurement uncertainty and linearity of a bundle fibre-optic displacement sensor were studied on a wide range of displacements using experimental and simulation approaches. The theoretical He-Cuomo distribution functions of light intensity yielded the simulated modulation characteristic that best fitted the experimental data in the range of dimensionless distances to the target surface from 0 to 50 but diverged beyond. The coefficient of variation of the output signal of the sensor varied non-monotonically with the distance to the target surface. This variation is suggested to stem from small randomly distributed imperfections on the mirror surface. © 2013 IOP Publishing Ltd.


Munoa J.,IK4 IDEKO | Mancisidor I.,IK4 IDEKO | Loix N.,Micromega | Uriarte L.G.,IK4 Tekniker | And 2 more authors.
CIRP Annals - Manufacturing Technology | Year: 2013

Productivity of heavy duty milling processes is limited by chatter vibrations related to the flexibility of the machine tool structure. One of the solutions is to add damping to the structure using vibration absorbers. However, the dynamic behaviour of these machines changes depending on their position in the workspace. Moreover, the critical modes have different displacement directions. Hence, in order to suppress chatter vibrations, a biaxial active actuator has been developed. In this work, the possible control strategies are analysed and the results of experimental tests of the biaxial actuator are shown. Important stability increase was obtained in real milling operations. © 2013 CIRP.


Ibarguren A.,IK4 Tekniker
Sensors (Basel, Switzerland) | Year: 2013

Maintenance tasks are crucial for all kind of industries, especially in extensive industrial plants, like solar thermal power plants. The incorporation of robots is a key issue for automating inspection activities, as it will allow a constant and regular control over the whole plant. This paper presents an autonomous robotic system to perform pipeline inspection for early detection and prevention of leakages in thermal power plants, based on the work developed within the MAINBOT (http://www.mainbot.eu) European project. Based on the information provided by a thermographic camera, the system is able to detect leakages in the collectors and pipelines. Beside the leakage detection algorithms, the system includes a particle filter-based tracking algorithm to keep the target in the field of view of the camera and to avoid the irregularities of the terrain while the robot patrols the plant. The information provided by the particle filter is further used to command a robot arm, which handles the camera and ensures that the target is always within the image. The obtained results show the suitability of the proposed approach, adding a tracking algorithm to improve the performance of the leakage detection system.


Uriarte L.,IK4 Tekniker | Zatarain M.,IK4 IDEKO | Axinte D.,University of Nottingham | Yague-Fabra J.,University of Zaragoza | And 3 more authors.
CIRP Annals - Manufacturing Technology | Year: 2013

This paper reviews the design, engineering principles and applications of machine tools specially developed for large parts. Large workshop machines are commonly used for manufacturing, where the impact of the general engineering principles differs substantially from those applied to conventional size machines. Portable machines are used during assembly and operation due to mobility, agility and energy constraints. Such large dimensions produce an amplification factor of any error source, so verification and calibration of such large or portable machines becomes even more critical than in conventional machines. The paper also includes future trends and unsolved challenges. © 2013 CIRP.

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