Ciencias Exactas y Ciencias de la Salud
Permanent URI for this collectionhttps://hdl.handle.net/11285/551039
Pertenecen a esta colección Tesis y Trabajos de grado de las Maestrías correspondientes a las Escuelas de Ingeniería y Ciencias así como a Medicina y Ciencias de la Salud.
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- Wavelets for spindle health diagnosis(2018-12-04) Villagómes Garzón, Silvia Cristina; Morales Menéndez, Rubén; Vallejo Guevara, Antonio; Hernández Alcántara, DianaIndustrial development and customer demands have increased the need to look for high-quality products at low cost and, at the same time, ensure safety during manufacturing. As a result, rotary machinery and its components have become increasingly complex, making their repairs more expensive. Therefore, many efforts must be focused in preventing breakdowns in machines, for which real-time fault diagnosis and prognosis are mandatory. Considering that the element most prone to failure in a machining center is the spindle, and with it its bearing system, the diagnosis of failures of these elements is of paramount importance. To ensure the safe operation of the bearing, some methods of fault detection have been developed based on different techniques. One of the most commonly used is vibration analysis. There are several difficulties when dealing with analyzing vibration signals, they are complex and non-stationary signals with a large amount of noise. Conventional analysis have not been able to solve this problem, thus, alternative methods such as Wavelet Transform have been gaining ground. The following research is focused in detecting bearing faults, as well as the main shaft faults, which eventually also lead to bearing damage, by using wavelets. Different signals, presenting distinct bearing fault conditions, of different data sets are evaluated for validating the proposed methodology. An exhaustive analysis has been developed for selecting the best parameters of this methodology. As results, an improvement around 20% in magnitude of bearing fault frequency peaks was found, compared to the traditional methodology. The proposal of giving more weight to high energy components allows increasing these fault frequencies, as well as reducing low frequency noise. This provides a great advantage in pursuit of an automatic fault detection. An industrial approach was also validated, by proving that the proposed methodology is more immune to noise. Even though, the magnitudes of the bearing fault peaks are diminished by noise, a comparison between the proposal and the traditional methodology reveal an increase of approximately 70% of those magnitudes. Demonstrating that the fault information is barely attenuated by noise. Also, an early diagnosis was proved, which could benefit future studies of fault prognosis. Finally, the filtering property of wavelet decomposition is exploited to limit the frequencies of the signal to few harmonics of the shaft speed. This with the aim of restricting the spectrum for detecting other faults, that mainly affect the spindle shaft, which are diagnosed by analyzing speed harmonics and subharmonics. Thus, a complete methodology is proposed to deal with the main spindle faults.
- Análisis de atributos de productos metalmecánicos y aspectos económicos para la selección de sistemas automatizados de manufactura(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2005-08-01) Galindo Sandoval, Gabriela; DORANTES GONZALEZ, DANTE JORGE; 67942; Dorantes González, Dante Jorge; Sandoval Palafox, Francisco; Manzano Herrera, MoisésEsta investigación da comienzo con la clasificación de los sistemas de manufactura en seis divisiones: líneas de transferencia, líneas de flujo por lotes, sistemas flexibles de manufactura, células de manufactura, máquinas herramientas de control numérico y taller de mecanizado. Posteriormente cuantifica los atributos más importantes de los productos (volumen de producción anual y variedad) y además establece la relación con los sistemas de fabricación por medio de la utilización de una herramienta gráfica, la cual delimita los rangos que abarca cada uno de los sistemas de manufactura para productos del sector metalmecánico representándolos a través de áreas. Esta herramienta gráfica es utilizada para la selección del sistema de manufactura más conveniente para el producto, basándose en el criterio de los atributos del mismo. Acto seguido presenta a los factores microeconómicos (costos de producción y tiempo de recuperación de la inversión) como aspectos cruciales en la selección de sistema de fabricación, realizando una comparativa de los sistemas de manufactura propuestos mediante el análisis del criterio de atributos del producto, basando esta comparación en los criterios del Punto de Equilibrio para los costos de producción y del Valor Presente Neto para encontrar el tiempo de recuperación de la inversión. Finalmente integra los aspectos técnico-económicos en un software que servirá como herramienta para el primer encuentro de consultoría con un posible inversionista con el fin de realizar un análisis de fiabilidad a nivel México.