Person: Rubio Alvir, Eva María
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Rubio Alvir
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Eva María
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Publication Analysis of Force Signals for the Estimation of Surface Roughness during Robot-Assisted Polishing(MDPI, 2018-08-15) Teti, Roberto; Agustina Tejerizo, Beatriz De; Marín Martín, Marta María; Rubio Alvir, Eva MaríaIn this study feature extraction of force signals detected during robot-assisted polishing processes was carried out to estimate the surface roughness during the process. The purpose was to collect significant features from the signal that allow the determination of the end point of the polishing process based on surface roughness. For this objective, dry polishing turning tests were performed on a Robot-Assisted Polishing (RAP) machine (STRECON NanoRAP 200) during three polishing sessions, using the same polishing conditions. Along the tests, force signals were acquired and offline surface roughness measurements were taken at the end of each polishing session. As a main conclusion, it can be affirmed, regarding the force signal, that features extracted from both time and frequency domains are valuable data for the estimation of surface roughness.Publication A novel method for the determination of fatty acid esters in aqueous emulsion on Ti6Al4V surface with IRRAS and carbon quantification(Elsevier, 2018-12-01) Benedicto Bardolet, Elisabet; Carou Porto, Diego; Batlle, L.; Rubio Alvir, Eva MaríaA novel direct method based on infrared reflection absorption spectroscopy (IRRAS) and carbon elemental analysis has been developed for the quantitative determination of fatty acid ester on Ti6Al4V surface. The new approach involves the IR spectra and carbon analysis of a Ti6Al4V strip treated with a surfactant and ester emulsion adjusted to pH 9.2 with 2-aminoethanol. The results are dependent on the ester and surfactant concentration. The analytical signals are the integral value of the CH2 and CO signals of the IR spectra and the carbon content. The main advantage of the proposed method is that the analysis made directly on the metal surface allows knowing the film forming ability of the emulsion. The method may be useful for research and development of more environmentally friendly water-based metalworking fluids for the metal industry.Publication Parametric Analysis of the Mandrel Geometrical Data in a Cold Expansion Process of Small Holes Drilled in Thick Plates(MDPI, 2019-12-08) Calaf Chica, José; Teti, Roberto; Segreto, Tiziana; Marín Martín, Marta María; Rubio Alvir, Eva MaríaCold expansion technology is a cold-forming process widely used in aeronautics to extend the fatigue life of riveted and bolted holes. During this process, an oversized mandrel is pushed through the hole in order to yield it and generate compressive residual stresses contributing to the fatigue life extension of the hole. In this paper, a parametric analysis of the mandrel geometrical data (inlet angle straight zone length and diametric interference) and their influence on the residual stresses was carried out using a finite element method (FEM). The obtained results were compared with the conclusions presented in a previous parametric FEM analysis on the influence of the swage geometry in a swaging cold-forming process of gun barrels. This process could be considered, in a simplified way, as a scale-up of the cold expansion process of small holes, and this investigation demonstrated the influence of the diameter ratio (K) on the relation between the mandrel or swage geometry and the residual stresses obtained after the cold-forming process.Publication Experimental study of magnesium drilling based on the surface quality(Elsevier, 2019) Berzosa Lara, Fernando; Agustina Tejerizo, Beatriz De; Rubio Alvir, Eva María; Marín Martín, Marta MaríaNowadays, the use of magnesium and its alloys for transport applications is based on the combination of high mechanical properties and low density. In general, the machinability of these materials is considered to be good. Nevertheless, it has been reported that the machining of these alloys involves some critical problems regarding their tendency to be flammable at high temperatures and consequently, there is a risk of chip ignition in the working area during the process. This fact is especially critical when the size of chips is reduced. In this study, the influence of cutting conditions on surface roughness, in terms of Ra, obtained by drilling of magnesium alloy (AZ91D-F) was carried out. A factorial design 2 4 was employed for the planning of the drilling tests. The factors considered were the feed rate (0.05 and 0.2 mm/r), cutting speed, 40 and 60 m/min, the type of tool, in particular, the point angle of 118º and 135º, and the cooling system, Dry conditions and MQL (Minimum Quantity Lubrication) system. As main conclusions it can be affirmed that improved surface roughness is obtained with the cutting conditions selected in this study. Furthermore, at 0.05 mm/r and 40 m/min the use of tools with a point angle of 135º provides lower values of Ra than the tool of 118º point angle. Slightly lower values of Ra are obtained with tools of 118º point angle at 0.2 mm/r and 60 m/min.Publication Tool Selection in Drilling of Magnesium UNSM11917 Pieces under Dry and MQL Conditions based on Surface Roughness(Elsevier, 2017) Berzosa Lara, Fernando; Agustina Tejerizo, Beatriz De; Rubio Alvir, Eva MaríaNowadays, the use of lighter materials for transportation purposes is still a challenge; especially in the aeronautical and aerospace sectors. The use of certain materials, such as magnesium alloys which have exceptional mechanical properties relative to density as structural materials, allows a remarkable reduction of weight. These alloys have significant challenges in machining. On the one hand, their use with water-based lubricants can produce flammable hydrogen atmospheres and, on the other hand, the operational parameters can produce tiny chips which, at high temperature, could burn. Regarding the tools, drills are the most used ones in drilling operations; manufacturers do not always take in consideration magnesium alloys. This is why, sometimes, the data from other types of similar alloys need to be extrapolated. This work shows an experimental study about the drilling of magnesium pieces based on surface roughness. The main goal is to determine the tools that best suit the requirement of surface roughness for this type of operations, which, for the aeronautical sector, is from 0.8 to 1.6 μm. The tests have been conducted under different cutting conditions, using several types of tools and two sustainable lubrication systems. In particular, dry machining and minimum quantity of lubrication (MQL) system have been used. A design of experiments (DOE) has been used to optimize the resources. The average roughness, Ra, has been selected as a response variable. The roughness values obtained are lower than 0.9 μm (namely, from 0.13 μm to 0.87 μm); so, it is possible to increase some of the parameter values, in order to improve the productivity, without they go outside the established limits. The results have been analyzed using the analysis of variance (ANOVA) method. A model for estimating the expected surface roughness in terms of the Rae, has been developed.Publication Cutting Parameter Selection for Efficient and Sustainable Repair of Holes Made in Hybrid Mg–Ti–Mg Component Stacks by Dry Drilling Operations(MDPI, 2018-08-07) Rubio Alvir, Eva María; Villeta, María; Valencia, José Luis; Sáenz de Pipaón, José Manuel; MDPIDrilling is one of the most common machining operations in the aeronautic and aerospace industries. For assembling parts, a large number of holes are usually drilled into the parts so that they can be joined later by rivets. As these holes are subjected to fatigue cycles, they have to be checked regularly for maintenance or repair, since small cracks or damage in its contour can quickly cause breakage of the part, which can have dangerous consequences. This paper focuses on finding the best combinations of cutting parameters to perform repair and maintenance operations of holes in stacked hybrid magnesium–titanium–magnesium components in an efficient, timely, and sustainable (without lubricants or coolants) manner, under dry drilling conditions. For the machining trials, experiments were designed and completed. A product of a full factorial 23 and a block of two factors (3 2) was used with surface roughness as the response variable measured as the mean roughness average. Analysis of variance (ANOVA) was used to examine the results. A set of optimized tool and cutting conditions is presented for performing dry drilling repair operations.Publication Feasibility Study of Hole Repair and Maintenance Operations by Dry Drilling of Magnesium Alloy UNS M11917 for Aeronautical Components(MDPI, 2019-06-30) Berzosa, Fernando; Agustina Tejerizo, Beatriz De; Rubio Alvir, Eva María; Davim, J. Paulo; MDPIMagnesium alloys are increasingly used due to the reduction of weight and pollutants that can be obtained, especially in the aeronautical, aerospace, and automotive sectors. In maintenance and repair tasks, it is common to carry out re-drilling processes, which must comply with the established quality requirements and be performed following the required safety and environmental standards. Currently, there is still a lack of knowledge of the machining of these alloys, especially with regards to drilling operations. The present article studies the influence of di erent cutting parameters on the surface quality obtained by drilling during repair and/or maintaining operations. For this propose, an experimental design was established that allows for the optimization of resources, using the average roughness (Ra) as the response variable, and it was analyzed through the analysis of variance (ANOVA). The results were within the margins of variation of the factors considered: the combination of factor levels that keep the Ra within the established margin, those that allow for the minimization of roughness, and those that allow for the reduction of machining time. In this sense, these operations were carried out in the most e cient way.Publication Parametric Analysis of the Mandrel Geometrical Data in a Cold Expansion Process of Small Holes Drilled in Thick Plates(MDPI, 2019-12-08) Calaf-Chica, José; Marín Martín, Marta María; Rubio Alvir, Eva María; Teti, Roberto; Secreto, Tiziana; MDPICold expansion technology is a cold-forming process widely used in aeronautics to extend the fatigue life of riveted and bolted holes. During this process, an oversized mandrel is pushed through the hole in order to yield it and generate compressive residual stresses contributing to the fatigue life extension of the hole. In this paper, a parametric analysis of the mandrel geometrical data (inlet angle straight zone length and diametric interference) and their influence on the residual stresses was carried out using a finite element method (FEM). The obtained results were compared with the conclusions presented in a previous parametric FEM analysis on the influence of the swage geometry in a swaging cold-forming process of gun barrels. This process could be considered, in a simplified way, as a scale-up of the cold expansion process of small holes, and this investigation demonstrated the influence of the diameter ratio (K) on the relation between the mandrel or swage geometry and the residual stresses obtained after the cold-forming process.Publication Guidelines for Selecting Plugs Used in Thin-Walled Tube Drawing Processes of Metallic Alloys(MDPI, 2017-12-18) Rubio Alvir, Eva María; Camacho López, Ana María; Pérez, Rául; Marín Martín, Marta María; MDPIIn this paper, some practical guidelines to select the plug or set of plugs more adequate to carry out drawing processes of thin-walled tubes carried out with fixed conical inner plug are presented. For this purpose, the most relevant input parameters have been considered in this study: the tube material, the most important geometrical parameters of the process (die semiangle, a, and cross-sectional area reduction, r) and the friction conditions (Coulomb friction coefficients, m1, between the die and the tube outer surface, and m2, between the plug and the tube inner surface). Three work-hardening materials are analyzed: the annealed copper UNS C11000, the aluminum UNS A91100, and the stainless steel UNS S34000. The analysis is realized by means of the upper bound method (UBM), modelling the plastic deformation zone by triangular rigid zones (TRZ), under the validated assumption that the process occurs under plane strain conditions. The obtained results allow establishing, for each material, a group of geometrical parameters, friction conditions, a set of plugs that make possible to carry out the process under good conditions, and the optimum plug to carry out the process using the minimum amount of energy. The proposed model is validated by means of an own finite element analysis (FEA) carried out under different conditions and, in addition, by other finite element method (FEM) simulations and real experiments taken from other researchers found in the literature (called literature simulations and literature experimental results, respectively). As a main conclusion, it is possible to affirm that the plug that allows carrying out the process with minimum quantity of energy is cylindrical in most cases.Publication Experimental Study for Improving the Repair of Magnesium–Aluminium Hybrid Parts by Turning Processes(MDPI, 2018-01-16) Rubio Alvir, Eva María; Villeta, María; Valencia, José Luis; Sáenz de Pipaón, José Manuel; MDPIOne of the lightest metallic materials used in the aeronautics, aerospace, and automotive industries, among others, is magnesium, due to its excellent weight/strength ratio. Most parts used in these industries need to be made of materials that are rigid, strong, and lightweight, but sometimes the materials do not simultaneously satisfy all of the properties required. An alternative is to combine two or more materials, giving rise to a hybrid component that can satisfy a wider range of properties. The pieces machined in these industrial fields must satisfy stringent surface roughness requirements that conform to the design specifications. This work shows an experimental study to analyse the surface roughness reached in hybrid components made up of a base of magnesium alloy (UNS M11917) and two inserts of aluminium alloy (UNS A92024) obtained by turning. Its purpose is to determine the influence of the factors and their possible interactions on the response variable, the surface roughness Ra. The study is carried out using a design of experiments (DOE). A product of a full factorial 23 and a block of two factors 3 2 was selected. The factors identified as possible sources of variation of the surface roughness are: depth of cut, feed rate, spindle speed, type of tool, location with respect to the specimen (LRS), and location with respect to the insert (LRI). Data were analysed by means of the analysis of variance (ANOVA) method. The main conclusion is the possibility to carry out the repair and maintenance of parts of magnesium–aluminum hybrid components by dry turning; that is, without cutting fluids and, therefore, in the most sustainable way that the process can be carried out. In addition, different combinations of cutting parameters have been identified that allow these operations to be carried out in an efficient manner, reducing mechanization times and, therefore, also the direct and indirect costs associated with them.