Grupos Investigadores

Líneas de Investigación

  • Optimización topológica de estructuras creadas por fabricación aditiva
  • Comportamiento mecánico y mecano-biológico de estructuras reticulares para aplicaciones biomédicas
  • Aplicaciones de impresión 3D a prefabricados de hormigón
  • Modelización, monitorizado y control de procesos de fabricación y construcción
  • Fabricación Híbrida de componentes metálicos combinando tecnologías de Fabricación Aditiva y post-procesado de acabado mediante operaciones de mecanizado

Palabras Clave

  • Permeabilidad
  • Monitorizado de procesos
  • Mecanizado
  • Imperfecciones de fabricación
  • Hormigón prefabricado
  • Gradación funcional
  • Fabricación aditiva
  • Elementos auxiliares de construcción
  • Biomecánica ortopédica
  • Biomateriales porosos
  • Fatiga

Publicaciones Científicas desde 2018

  • Autores: Bidare, P. (Autor de correspondencia); Jiménez Zabaleta, Amaia; Hassanin, H.; et al.
    Revista: ADVANCES IN MANUFACTURING
    ISSN 2095-3127 Vol.10 N° 2 2022 págs. 175 - 204
    Resumen
    Additive manufacturing (AM) technologies are currently employed for the manufacturing of completely functional parts and have gained the attention of high-technology industries such as the aerospace, automotive, and biomedical fields. This is mainly due to their advantages in terms of low material waste and high productivity, particularly owing to the flexibility in the geometries that can be generated. In the tooling industry, specifically the manufacturing of dies and molds, AM technologies enable the generation of complex shapes, internal cooling channels, the repair of damaged dies and molds, and an improved performance of dies and molds employing multiple AM materials. In the present paper, a review of AM processes and materials applied in the tooling industry for the generation of dies and molds is addressed. AM technologies used for tooling applications and the characteristics of the materials employed in this industry are first presented. In addition, the most relevant state-of-the-art approaches are analyzed with respect to the process parameters and microstructural and mechanical properties in the processing of high-performance tooling materials used in AM processes. Concretely, studies on the AM of ferrous (maraging steels and H13 steel alloy) and non-ferrous (stellite alloys and WC alloys) tooling alloys are also analyzed.
  • Autores: Ajami, S. (Autor de correspondencia); Rodríguez Florez, Naiara; Ong, J.; et al.
    Revista: JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
    ISSN 1751-6161 Vol.125 2022 págs. 104929
    Resumen
    Limited information is available on the effect of sagittal craniosynostosis (CS) on morphological and material properties of the parietal bone. Understanding these properties would not only provide an insight into bone response to surgical procedures but also improve the accuracy of computational models simulating these surgeries. The aim of the present study was to characterise the mechanical and microstructural properties of the cortical table and diploe in parietal bone of patients affected by sagittal CS. Twelve samples were collected from pediatric patients (11 males, and 1 female; age 5.2 +/- 1.3 months) surgically treated for sagittal CS. Samples were imaged using micro-computed tomography (micro-CT); and mechanical properties were extracted by means of micro-CT based finite element modelling (micro-FE) of three-point bending test, calibrated using sample-specific experimental data. Reference point indentation (RPI) was used to validate the micro-FE output. Bone samples were classified based on their macrostructure as unilaminar or trilaminar (sandwich) structure. The elastic moduli obtained using RPI and micro-FE approaches for cortical tables (E-RPI 3973.33 +/- 268.45 MPa and Emicro-FE 3438.11 +/- 387.38 MPa) in the sandwich structure and diploe (E(RPI)1958.17 +/- 563.79 MPa and Emicro-FE 1960.66 +/- 492.44 MPa) in unilaminar samples were in strong agreement (r = 0.86, p < .01). We found that the elastic modulus of cortical tables and diploe were correlated with bone mineral density. Changes in the microstructure and mechanical properties of bone specimens were found to be irrespective of patients' age. Although younger patients are reported to benefit more from surgical intervention as skull is more malleable, understanding the material properties is critical to better predict the surgical outcome in patients <1 year old since age-related changes were minimal.
  • Autores: Bidare, P. (Autor de correspondencia); Mehmeti, A.; Jiménez Zabaleta, Amaia; et al.
    Revista: INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
    ISSN 0268-3768 Vol.120 N° 11-12 2022 págs. 8063 - 8074
    Resumen
    Nickel-based alloys are known as non-weldable materials due to their complex characteristics. Consequently, additive manufacturing of these alloys is particularly challenging. In this paper, the influence of process parameters on the porosity, crack formation and microstructure of additively manufactured CM247LC nickel-based alloy is analysed. The feasibility of the direct laser deposition (DLD) process to manufacture crack-free and low-porosity CM247LC samples is studied. CM247LC samples were built on Inconel 718 that has similar chemical composition, to form hybrid superalloy parts. It was shown that crack-free and high-density CM247LC samples can be obtained through DLD without significant substrate preheating for certain parameter combinations: laser power in the range of 800-1000 W and powder feed rates between 6 and 8 g/min. High-cost and complex preheating was avoided that was commonly reported as necessary to achieve similar densities. For hybrid parts, a large beam diameter and slow scan speeds were employed to achieve optimal conditions as it was evident from the achieved bonding between the Inconel 718 substrate and the deposited layers. It was observed that good bonding between the two materials can be obtained with laser power values between 800 and 1000 W, scanning speed higher than 300 mm/min and powder flow rates of 6-8 g/min.
  • Autores: Aramburu Ibarlucea, Amaya (Autor de correspondencia); Calderón-Uriszar-Aldaca, I.; Puente Urruzmendi, Íñigo
    Revista: CONSTRUCTION AND BUILDING MATERIALS
    ISSN 0950-0618 Vol.340 2022 págs. 127827
    Resumen
    Passive rebars are inserted into interior hollow channels within a 3D-printed mortar geometry and then bonded with a wet joint of filling mortar, in order to test the bonding strength of the rebars within the mortar structure. Standardized test procedures are adapted for the test procedure. The test results revealed bonding strengths with shear stresses within an interval between 16.75 MPa and 18 MPa, dependent upon rebar diameter, and good early strength development of the bonding mortar of at least 14 MPa during the first week. No specimen failed because of debonding between the filling mortar and the 3D-printed cylinder, nor because of debonding of the cylinder and the concrete poured around its exterior.
  • Autores: Jiménez Zabaleta, Amaia; Bidare, P.; Hassanin, H.; et al.
    Revista: INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
    ISSN 0268-3768 Vol.114 N° 1 - 2 2021 págs. 63 - 96
    Resumen
    Recent advances in additive manufacturing (AM) have attracted significant industrial interest. Initially, AM was mainly associated with the fabrication of prototypes, but the AM advances together with the broadening range of available materials, especially for producing metallic parts, have broaden the application areas and now the technology can be used for manufacturing functional parts, too. Especially, the AM technologies enable the creation of complex and topologically optimised geometries with internal cavities that were impossible to produce with traditional manufacturing processes. However, the tight geometrical tolerances along with the strict surface integrity requirements in aerospace, biomedical and automotive industries are not achievable in most cases with standalone AM technologies. Therefore, AM parts need extensive post-processing to ensure that their surface and dimensional requirements together with their respective mechanical properties are met. In this context, it is not surprising that the integration of AM with post-processing technologies into single and multi set-up processing solutions, commonly referred to as hybrid AM, has emerged as a very attractive proposition for industry while attracting a significant R&D interest. This paper reviews the current research and technology advances associated with the hybrid AM solutions. The special focus is on hybrid AM solutions that combine the capabilities of laser-based AM for processing powders with the necessary post-process technologies for producing metal parts with required accuracy, surface integrity and material properties. Commercially available hybrid AM systems that integrate laser-based AM with post-processing technologies are also reviewed together with their key application areas. Finally, the main challenges and open issues in broadening the industrial use of hybrid AM solutions are discussed.
  • Autores: Asbai-Ghoudan, Reduan (Autor de correspondencia); Ruiz de Galarreta Moriones, Sergio; Rodríguez Florez, Naiara
    Revista: JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
    ISSN 1751-6161 Vol.124 2021 págs. 104804
  • Autores: Ruiz de Galarreta Moriones, Sergio (Autor de correspondencia); Doyle, Ruben J. ; Jeffers, Jonathan ; et al.
    Revista: JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
    ISSN 1751-6161 Vol.123 2021 págs. 104784
  • Autores: Del-Val, A. G.; Veiga, F.; Penalva, M.; et al.
    Revista: METALS
    ISSN 2075-4701 Vol.11 N° 4 2021 págs. 537
    Resumen
    Automotive, railway and aerospace sectors require a high level of quality on the thread profiles in their manufacturing systems knowing that the tapping process is a complex manufacturing process and the last operation in a manufacturing cell. Therefore, a multivariate statistical process control chart, for each tap, is presented based on the principal components of the torque signal directly measured from spindle motor drive to diagnosis the thread profile quality. This on-line multivariate control chart has implemented an alarm to avoid defected screw threads (oversized). Therefore, it could work automatically without any operator intervention assessing the thread quality and the safety is guaranteed during the tapping process.
  • Autores: Markel Alaña (Autor de correspondencia); Antonio Cutolo; Ruiz de Galarreta Moriones, Sergio; et al.
    Revista: SCIENTIFIC REPORTS
    ISSN 2045-2322 Vol.11 N° 19314 2021
  • Autores: Jiménez Zabaleta, Amaia (Autor de correspondencia); Arizmendi Jaca, Miguel; Sánchez Moreno, José Manuel
    Revista: INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
    ISSN 0268-3768 Vol.114 N° 9 - 10 2021 págs. 2711 - 2720
    Resumen
    This paper presents an experimental method for predicting tool wear in drilling Inconel 718 superalloy. The method combines analysis of drilling force signals and tool wear progress. Force characteristics were studied both in time and frequency domains (power spectrum and wavelet decomposition) in order to find best correlation with tool wear progress. These analyses show that the mean value of the thrust force component, the high frequency component of the force, the frequencies that arise during drilling, and the evolution of the wavelet decomposition details are all sensitive to tool wear progress. Therefore, these characteristics can be employed as indicators for drill failure prediction. Among all those indicators, the mean value of the thrust force and the standard deviation of high frequency components of that force have shown the greatest sensitivity to drill wear.
  • Autores: Heutinck, P.; Knoops, P.; Rodríguez Florez, Naiara; et al.
    Revista: JOURNAL OF CRANIO-MAXILLOFACIAL SURGERY
    ISSN 1010-5182 Vol.49 N° 6 2021 págs. 449 - 455
    Resumen
    The aim of this study is, firstly, to create a population-based 3D head shape model for the 0 to 2-year-old subjects to describe head shape variability within a normal population and, secondly, to test a combined normal and sagittal craniosynostosis (SAG) population model, able to provide surgical outcome assessment. 3D head shapes of patients affected by non-cranial related pathologies and of SAG patients (pre- and post-op) were extracted either from head CTs or 3D stereophotography scans, and processed. Statistical shape modelling (SSM) was used to describe shape variability using two models - a normal population model (MODEL1) and a combined normal and SAG population model (MODEL2). Head shape variability was described via principal components analysis (PCA) which calculates shape modes describing specific shape features. MODEL1 (n - 65) mode 1 showed statistical correlation (p < 0.001) with width (125.8 +/- 13.6 mm), length (151.3 +/- 17.4 mm) and height (112.5 +/- 11.1 mm) whilst mode 2 showed correlation with cranial index ( 83.5 mm +/- 6.3 mm, p < 0.001). The remaining 9 modes showed more subtle head shape variability. MODEL2 (n = 159) revealed that post-operative head shape still did not achieve full shape normalization with either spring cranioplasty or total calvarial remodelling. This study proves that SSM has the potential to describe detailed anatomical variations in a paediatric population. (C) 2021 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
  • Autores: Cumbicus Jiménez, Wilmer Euclides (Autor de correspondencia); Estrems, M.; Arizmendi Jaca, Miguel; et al.
    Revista: INTERNATIONAL JOURNAL OF MATERIAL FORMING
    ISSN 1960-6206 Vol.14 N° 4 2021 págs. 777 - 798
  • Autores: Pradera Mallabiabarrena, Ainara (Autor de correspondencia); López de Arancibia, Aitziber; Ruiz de Galarreta Moriones, Sergio; et al.
    Revista: THIN-WALLED STRUCTURES
    ISSN 0263-8231 Vol.159 2021
    Resumen
    Steel cylindrical shell structures such as silos and tanks are very sensitive to geometric imperfections and prone to a plastic instability failure known as elephant's foot (EF) buckling. This type of buckling arises under axial compression. The aim of this paper is to explore the plastic collapse response in conical shells with low semi-vertex angle values under compression. In a first step, the initial geometric imperfection shapes that dictate which plastic mechanisms arise were identified using finite element (FE) models. In a second step, a parametric study reported two plastic collapse mechanisms and showed that the elephant's foot plastic collapse mechanism is the most likely to appear in compressed conical shells with low d/t values, followed by the Yoshimura collapse mechanism, more common with larger d/t values. Finally, a practical model in which the parameters have been adjusted from numerical models has been derived for the elephant's foot plastic mechanism. This model provides the load-deformation behaviour of compressed conical shells at the post-collapse region. The load vs. end-shortening curves provided by the model have been validated through comparison with curves given by the FE models. The good agreement between the results proves the efficiency of the practical model to predict the collapse response of conical shells.
  • Autores: Veiga Suárez, Fernando; Arizmendi Jaca, Miguel; Jiménez Zabaleta, Amaia; et al.
    Revista: INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
    ISSN 0020-7403 Vol.204 2021 págs. 106524
    Resumen
    High temperatures generated in cutting processes significantly affect the surface integrity of machined parts and tool wear, leading to workpiece thermal damage, tensile residual stresses in the workpiece and a reduction in tool life. In recent years, different analytical thermal models to predict cutting temperatures have been developed in literature based on 2D modeling of the cutting process and the assumption that thermal conductivities of work piece and chip are not dependent on temperature. However, this dependence of conductivity on temperature may have a significant influence on predicted temperatures and must be taken into account. In this paper, a thermal model of the orthogonal cutting process that considers thermal conductivity of materials (chip and tool) to be dependent on temperature is developed. A linear variation of thermal conductivity with temperature is assumed for chip (workpiece) and tool materials. The model is based on application of: (1) the Kirchhoff transformation in order to convert the nonlinear heat conduction problem into a linear one, (2) the theory of moving and stationary heat sources in semi-infinite and infinite mediums in order to model primary and secondary deformation zones and (3) imaginary heat sources to meet adiabatic boundary conditions in the chip and tool. Imaginary heat sources were defined in the thermal model proposed in this paper in such a way that the effect of the tool-chip interface dimensions and of cutting tool width on
  • Autores: Ibrahim, A. (Autor de correspondencia); Rodríguez Florez, Naiara; Gardner, O. F. W.; et al.
    Revista: STEM CELLS TRANSLATIONAL MEDICINE
    ISSN 2157-6564 Vol.9 2020 págs. 1551 - 1666
    Resumen
    While human adipose-derived stem cells (hADSCs) are known to possess osteogenic differentiation potential, the bone tissues formed are generally considered rudimentary and immature compared with those made by bone-derived precursor cells such as human bone marrow-derived mesenchymal stem cells (hBMSCs) and less commonly studied human calvarium osteoprogenitor cells (hOPs). Traditional differentiation protocols have tended to focus on osteoinduction of hADSCs through the addition of osteogenic differentiation media or use of stimulatory bioactive scaffolds which have not resulted in mature bone formation. Here, we tested the hypothesis that by reproducing the physical as well as biochemical bone microenvironment through the use of three-dimensional (3D) culture and vascularization we could enhance osteogenic maturation in hADSCs. In addition to biomolecular characterization, we performed structural analysis through extracellular collagen alignment and mineral density in our bone tissue engineered samples to evaluate osteogenic maturation. We further compared bone formed by hADSCs, hBMSCs, and hOPs against mature human pediatric calvarial bone, yet not extensively investigated. Although bone generated by all three cell types was still less mature than native pediatric bone, a fibrin-based 3D microenvironment together with vascularization boosted osteogenic maturation of hADSC making it similar to that of bone-derived osteoprogenitors. This demonstrates the important role of vascularization and 3D culture in driving osteogenic maturation of cells easily available but constitutively less committed to this lineage and suggests a crucial avenue for recreating the bone microenvironment for tissue engineering of mature craniofacial bone tissues from pediatric hADSCs, as well as hBMSCs and hOPs.
  • Autores: Alana, M. (Autor de correspondencia); Cutolo, A. (Autor de correspondencia); Probst, G. ; et al.
    Revista: MATERIALS & DESIGN
    ISSN 0264-1275 Vol.195 2020 págs. 108971
    Resumen
    Laser powder bed fusion (L-PBF) allows the production of metal lattice cellular structures with tailored mechanical properties. In order to generate the specific structural behavior it is of utmost importance to understand the response of the unit cells when different load conditions are considered. In this article the mechanical response of diamond based cellular structures has been investigated focusing on the impact of geometrical inaccuracy generated by the manufacturing process on the elastic anisotropy of the mentioned unit cell. The ii-CT analysis of the structures shows that the manufacturing deviations occur in certain orientations that depend highly on the building direction and proximity to nodes. The measured imperfection types were implemented in a finite element model in order to predict their single and combined effects in the elastic directional response. The results indicate that the L-PBF process can induce a significant change of elastic anisotropy in the diamond unit cells, including a substantial variation of the optimal orientation for minimal compliance. Methods are presented to calculate this anisotropy such that it can be taken into account when designing and using such lattice structures in real-life applications with multi-axial load conditions. (c) 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).
  • Autores: Rodríguez Florez, Naiara; Borghi, A. ; Yauwan, D. D. ; et al.
    Revista: JOURNAL OF CRANIOFACIAL SURGERY
    ISSN 1049-2275 Vol.31 N° 7 2020 págs. 2084 - 2087
    Resumen
    Spring-assisted cranioplasty (SAC) is a minimally invasive technique for treating sagittal synostosis in young infants. Yet, follow-up data on cranial growth in patients who have undergone SAC are lacking. This project aimed to understand how the cranial shape develops during the postoperative period, from spring insertion to removal. 3D head scans of 30 consecutive infants undergoing SAC for sagittal synostosis were acquired using a handheld scanner pre-operatively, immediately postoperatively, at follow-up and at spring removal; 3D scans of 41 age-matched control subjects were also acquired. Measurements of head length, width, height, circumference, and volume were taken for all subjects; cephalic index (CI) was calculated. Statistical shape modeling was used to compute 3D average head models of sagittal patients at the different time points. SAC was performed at a mean age of 5.2 months (range 3.3-8.0) and springs were removed 4.3 months later. CI increased significantly (P < 0.001) from pre-op (69.5% +/- 2.8%) to spring removal (74.4% +/- 3.9%), mainly due to the widening of head width, which became as wide as for age-matched controls; however, the CI of controls was not reached (82.3% +/- 6.8%). The springs did not constrain volume changes and allowed for natural growth. Population mean shapes showed that the bony prominences seen at the sites of spring engagement settle over time, and that springs affect the overall 3D head shape of the skull. In conclusion, results reaffirmed the effectiveness of SAC as a treatment method for nonsyndromic single suture sagittal synostosis.
  • Autores: Del Val, AG. (Autor de correspondencia); Veiga Suárez, Fernando; Suarez, A.; et al.
    Revista: JOURNAL OF MANUFACTURING AND MATERIALS PROCESSING
    ISSN 2504-4494 Vol.4 N° 1 2020 págs. 9
    Resumen
    Thread quality control is becoming a widespread necessity in manufacturing to guarantee the geometry of the resulting screws on the workpiece due to the high industrial costs. Besides, the industrial inspection is manual provoking high rates of manufacturing delays. Therefore, the aim of this paper consists of developing a statistical quality control approach acquiring the data (torque signal) coming from the spindle drive for assessing thread quality using different coatings. The system shows a red light when the tap wear is critical before machining in unacceptable screw threads. Therefore, the application could reduce these high industrial costs because it can work self-governance.
  • Autores: Calderon-Uriszar-Aldaca, I. (Autor de correspondencia); Briz, E. ; Biezma, M. V. ; et al.
    Revista: INTERNATIONAL JOURNAL OF FATIGUE
    ISSN 0142-1123 Vol.122 2019 págs. 141 - 151
    Resumen
    Fatigue under variable amplitude loading is currently assessed by applying the Palmgren-Miner linear rule in structural standards. However, this linear rule is inadequate in natural scenarios with coupled fatigue and corrosion effects, because the coupled corrosion-fatigue process synergistically accelerates deterioration. In view of the absence of specifications for the coupled fatigue-corrosion effect in structural standards, the objective here is to develop a simple and practical correction factor that will ensure a conservative linear summation of damage, taking the corrosion-fatigue effect into account. The theoretical consistency and the feasibility of the new adapted rule are tested in a case study.
  • Autores: Arizmendi Jaca, Miguel (Autor de correspondencia); Jiménez Zabaleta, Amaia; Cumbicus Jiménez, Wilmer Euclides; et al.
    Revista: INTERNATIONAL JOURNAL OF MACHINE TOOLS AND MANUFACTURE
    ISSN 0890-6955 Vol.137 2019 págs. 79 - 95
  • Autores: Jiménez Zabaleta, Amaia (Autor de correspondencia); Arizmendi Jaca, Miguel; Cumbicus Jiménez, Wilmer Euclides
    Revista: INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
    ISSN 0268-3768 Vol.100 N° 9-12 2019 págs. 2831 - 2855
    Resumen
    In this work, a model for the prediction of drilling stability against low-frequency lateral vibrations, named as whirling in the literature, is proposed. These vibrations are lateral displacements of the tool that arise at frequencies near multiples of the rotation frequency of the drill. The appearance of whirling vibrations leads to the generation of lobe-shaped holes. In order to predict whirling vibrations, the motion equation of the drill is deduced taking into account the modal characteristics of the drill and the cutting and process damping forces that act on it. In this paper, forces that arise in two different regions of the drill are considered: (1) forces on the main cutting edges and (2) forces on the chisel edge. Different force models are presented for each region that include both the regenerative effect of the vibration on the cutting area and the process damping. An oblique cutting model and an orthogonal model are employed for the calculation of cutting forces acting on the main cutting edges and on the chisel edge, respectively. The cutting force model for the main cutting edges takes into account the cutting angle (inclination angle, rake angle, and chip flow angle) variation along the main cutting edges. For the chisel edge region, where the feed speed is no longer negligible with respect to the cutting speed, the dynamic cutting angles are employed for the force model development. Concerning the process damping force model, previous works in the literature consider a constant value of the clearance angle for the calculation of the process damping coefficient. However, in this work, the variation of the normal clearance angle along the main cutting edges is considered. It is shown that, depending on the clearance face grinding parameters employed, the clearance angle can double its value along the main cutting edges. Considering the force models and through the semi-discretization of the motion equation of the drill, the appearance of low-frequency lateral vibrations is predicted regarding the drill geometry and cutting conditions such as drill rotation speed and feed. In addition, given cutting conditions at which whirling vibrations are expected to occur, the model is able to predict the vibration frequencies that are excited. The drilling model and the stability predictions are experimentally validated by means of drilling tests with different drill diameters and cutting conditions. In comparing the experimentally obtained results and the predictions obtained by the model, it is concluded that the model can reasonably predict the appearance of whirling vibrations as a function of drill geometry and cutting conditions. Generated hole shape is also analyzed through the measurement of hole roundness and bottom surface geometry. It is observed that, when drilling in the presence of whirling vibrations, holes with lobed shape and polygonal bottom surface are generated. It is also noticed that both the number of lobes and the number of sides of the polygonal bottom surface are directly related to the vibration frequencies that arise.
  • Autores: Arizmendi Jaca, Miguel (Autor de correspondencia); Jiménez Zabaleta, Amaia
    Revista: INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
    ISSN 0020-7403 Vol.163 2019
    Resumen
    This paper presents a model for predicting the surface topography generated in face milling operations. In these operations, when the face mill inserts remove the workpiece material, they leave marks on the machined surfaces. The marks depend on the face mill geometry, the geometry and runout of the face mill inserts, and cutting conditions, e.g. feed and step over. In order to predict the surface topography, the geometry of the face mill cutting edges must first be modelled. The modelling of the cutting edge geometry is for round insert face mills and for square shoulder face mills. Due to the influence of insert runout on the final surface topography, axial and radial runouts of the face mill inserts are also taken into account in the modelling of the cutting edge geometry. Next, the equations expressing the trajectory of any cutting edge point are derived as a function of the feed value, the rotation angle of the face mill, its axial position, and its radial position with respect to the face mill axis. Finally, given the cutting edge geometry and the trajectory of cutting edge points, a methodology based on the discretization of the milled surface in a grid with a finite number of points is developed in this paper for the simulation of the surface topography. The methodology is based on the fact that at each grid point, the final height of the topography will be the height of the workpiece material remaining at this point after many face mill revolutions. For this reason, the procedure initially estimates the rotation angles of the face mill for which the face mill cutting edges in their front-cutting and back-cutting motion pass by the grid point being considered. In order to achieve this, a transcendental equation that is only dependent on the rotation angle is derived from the cutting edge trajectory equations. This equation is transformed into an equivalent polynomial equation by means of Chebyshev expansions. The transformed equation is solved for the rotation angle using a standard root finder that does not require a starting value. Then, by means of the estimated rotation angles and the cutting edge trajectory equations, the radial positions of the cutting edge points passing by the grid point are obtained. Finally, based on these radial positions and the cutting edge geometry, the heights of cutting edge points, which can generate the surface topography at this grid point, are estimated. The final height of the surface topography will correspond to the lowest value among the estimated height values. The methodology can be easily extended and applied to face mills with other insert geometries or to face mills with central and peripheral inserts. In addition, the simulation of the surface topography generated by lateral passes in face milling operations is simplified. The procedure allows the influence of the face mill geometry, the feed value and the step over between passes to be analysed and the roughness values to be predicted. In order to validate the model predictions, a series of face milling tests are carried out. Predicted surface topographies are compared with measured topographies and a good agreement between them is observed.
  • Autores: Jiménez Zabaleta, Amaia (Autor de correspondencia); Arizmendi Jaca, Miguel; Cumbicus Jiménez, Wilmer Euclides
    Revista: INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
    ISSN 0268-3768 Vol.96 2018 págs. 1971 - 1990
    Resumen
    A model that predicts the appearance of low-frequency lateral vibrations in drilling with pilot hole is proposed in this work. These vibrations, called whirling in the literature, are responsible for the generation of lobe-shaped holes during drilling. The present model considers both the influence of the regenerative effect of vibrations on the cutting forces and the influence of the process damping phenomenon that appears along the main cutting edges. In order to model cutting forces, cutting edges are divided into discrete elements and for each of them oblique cutting model is employed. Specific cutting forces at each cutting edge element are calculated as function of cutting speed and normal rake angle value. A new methodology is developed to analyze the motion equation of the drill in the frequency domain in order to predict the appearance of whirling vibrations during drilling with pilot hole. Regarding the depth of cut and the spindle rotational speed, drilling stability limits against low-frequency lateral vibrations are obtained. Moreover, in the presence of vibrations, the model can predict the whirling frequencies that are excited depending on the established cutting conditions. In addition, the stability model is experimentally validated via drilling tests over pilot holes of different diameters for a wide range of cutting conditions. In order to study the appearance of low-frequency vibrations and to avoid the appearance of other vibrations such as regenerative chatter, the analysis is focused on low spindle speed values. A comparison between predicted vibration frequencies and actual frequencies in measured cutting forces during drilling tests is carried out and a good correlation between them is observed.
  • Autores: Alvarez, A. ; Calleja, A. (Autor de correspondencia); Arizmendi Jaca, Miguel; et al.
    Revista: MATERIALS
    ISSN 1996-1944 Vol.11 N° 8 2018 págs. 1301
    Resumen
    The emergence of multitasking machines in the machine tool sector presents new opportunities for the machining of large size gears and short production series in these machines. However, the possibility of using standard tools in conventional machines for gears machining represents a technological challenge from the point of view of workpiece quality. Machining conditions in order to achieve both dimensional and surface quality requirements need to be determined. With these considerations in mind, computer numerical control (CNC) methods to provide useful tools for gear processing are studied. Thus, a model for the prediction of surface roughness obtained on the teeth surface of a machined spiral bevel gear in a multiprocess machine is presented. Machining strategies and optimal machining parameters were studied, and the roughness model is validated for 3 + 2 axes and 5 continuous axes machining strategies.

Proyectos desde 2018

  • Título: Optimización del proceso de corte y de la vida útil de la herramienta en operaciones de mecanizado de aceros inoxidables super dúplex
    Código de expediente: PUE_2022_1_0008
    Investigador principal: MIGUEL ARIZMENDI JACA.
    Financiador: GOBIERNO VASCO
    Convocatoria: PROYECTOS DE INVESTIGACIÓN BÁSICA Y APLICADA 2022-2024
    Fecha de inicio: 01-09-2022
    Fecha fin: 31-08-2024
    Importe concedido: 50.000,00 €
    Fondos FEDER: NO
  • Título: Estrategias de diseño e impresión 3D para el desarrollo de garras robóticas con sensórica integrada. Postprocesados para mejorar tolerancias y funcionalidad: mecanizados y recubrimientos
    Código de expediente: 2021-CIEN-000065-01
    Investigador principal: AITOR CAZON MARTIN.
    Financiador: DIPUTACIÓN FORAL DE GIPUZKOA
    Convocatoria: Programa Red guipuzcoana de Ciencia, Tecnología e Innovación_DFG 2021
    Fecha de inicio: 01-07-2021
    Fecha fin: 30-11-2022
    Importe concedido: 44.412,00 €
    Fondos FEDER: NO