Browsing by Author "Gil Del Val, A."
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Item Monitoring of thread quality when tapping nodular cast iron with TiN-coated HSS cutting taps(2013-11) Gil Del Val, A.; Fernández, J.; Del Castillo, E.; Arizmendi, M.; Veiga, F.; Tecnalia Research & InnovationTapping is a widely employed but complex manufacturing process in which a multi-toothed tool, known as a tap, cuts a mating thread when driven into a hole. In this paper, the experiments, statistical analysis and the on-line implementation of a new thread quality monitoring system are presented for a tapping process in high-speed conditions. A multivariate statistical process control chart, for each tap, is presented based on the principal components of the torque directly measured from spindle motor drive. The on-line implementation of the multivariate chart provides tap wear warnings and alarms before the process starts producing unacceptable screw threads. The system is cost-effective since the tapping process can be run automatically without any operator intervention, does not require intrusive sensors, does not result in false negatives (defects) and provides an acceptable number of false positives.Item Threading holder based on axial metal cylinder pins to reduce tap risk during reversion instant(2023-03-01) Fernández-Lucio, P.; Gil Del Val, A.; Plaza, S.; Pereira, O.; Fernández-Valdivielso, A.; López de Lacalle, L. N.; FABRIC_INTELInternal thread profiles are used widely in manufacturing processes with the aim of assembling/disassembling different components during maintenance activities from the aeronautics sector until common industrial parts. The threading process is one of the last operations carried out to obtain those components, and consequently, it is an operation of high added value. Threading is a complex operation that must carefully synchronize the rotation with the feed movements to avoid tool breakage during the instant of tapping reversion stage. In order to avoid this risk, several toolholders were developed present in the literature but deficiencies in terms of stability and productivity. Therefore, in this work, a new toolholder is proposed in which the common springs used to mitigate the lack of perfect synchronization between rotation and feed movements are replaced by elastic metal pins achieving a torsional compliance toolholder. The results show that the use of the proposed toolholder implies not only a productivity increase but also a surface integrity improvement as well as a stress reduction that the cutting tap is subjected and thus, achieving a substantial improvement in the current tapping processes. In particular, the use of the proposed toolholder implied a 75% reduction of the maximum stress achieved in the reversal instant, improving 20% tool life with an increase of 30% cutting speed. Therefore, the use of the proposed toolholder implies a substantial improvement in the current tapping processes.Item Transient temperature distribution in a rotating cylinder subject to a surface heat source and convective cooling(2022) Arizmendi, M.; Veiga, F.; Jiménez, A.; Gil Del Val, A.; Tecnalia Research & Innovation; FABRIC_INTELIn this article, an analytical solution is developed to determine the transient temperature distribution in a rotating finite cylinder subject to a heat source acting on its flat surface with convective cooling. The resolution of the heat conduction problem for the cylinder temperature is carried out by means of the successive application of one-dimensional integral transforms: the finite Fourier transform and the finite Hankel transform. The solution can be applied in different engineering applications such as turning, pin-on-disk devices, bearings and braking systems. Taking this solution into account, a numerical analysis of the transient temperature distribution generated in a rotating cylinder subject to a heat source is performed. In this analysis the effect of the rotation speed and of the convective cooling on the transient temperature distribution of the cylinder and on the time required to reach the quasi-steady state is studied by means of two dimensionless parameters: the Peclet number and the Biot number, which depend on the rotation speed and on the convective heat transfer coefficient, respectively. Finally, different heat source geometries (circular, square and circular trapezoid) are considered.