Thesis defense of Javier Vicente Teixidó

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Thesis defense of Javier Vicente Teixidó

THESIS

Thesis defense of Javier Vicente Teixidó

Title of the thesis: “Embedded nanocomposite based preload force sensor for ball screws”. Obtained the SOBRESALIENTE qualification and the CUM LAUDE and DOCTOR INTERNACIONAL mentions.

2020·01·16

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  • Title of the thesis: “Embedded nanocomposite based preload force sensor for ball screws”.
  • PhD programme: DOCTORATE PROGRAMME IN MECHANICAL ENGINEERING AND ELECTRICAL ENERGY
  • Thesis directors: José Manuel Abete Huici, Aitzol Iturrospe Iregui.
  • Court:
    • President: Carlos Miguel da Silva Costa (University of Minho)
    • Vocal: Franck Andres Girot Mata (EHU-UPV)
    • Vocal: Maria del Carmen Rial Tubio (BCMaterials, Basque Center of Materials)
    • Vocal: Pedro José Arrazola Arriola (Mondragon Unibertsitatea) 
    • Secretary: Jaione Iriondo Gabilondo (Mondragon Unibertsitatea)

Abstract

In this dissertation, the development of a preload sensing system for ball screws is presented. Being a critical component in machine tools, ball screw preload has a direct impact on the quality of machined parts. The development of a novel preload monitorization system based on direct preload measurement through functional force sensing materials was identified as a critical added value to ball screws.

Among the different sensing technologies found in the literature, nanocarbonaceous polymeric piezoresistive nanocomposites were identified as a valid option for preload force measurement. The main advantages of these functional materials are their sensitivity to load, their lower cost and their embeddability. Particularly, PVDF-based nanocarbonaceus piezoresistive materials were selected for the application, as the thermal, mechanical and weathering properties of PVDF suited the target application. Different PVDF based piezoresistive nanocomposites were evaluated. Their morphological, thermal, electrical, mechanical and electromechanical properties were studied under laboratory tests.

A sensed ball screw design was developed under the W-model strategy. Different sensor configurations were tested, both dynamically and statically. The final design employs the piezoresistive material in thin film format between the nut and the ball screw spacer. The developed design met the industrial requirements for the application in terms of cost, complexity and design. The developed preload sensing system was tested, calibrated and validated under laboratory conditions.

Finally, the sensed prototype was tested and validated based on the industrial standard DIN 69051/3. A preload variation mechanism was designed for the validation of the ball screw both at different preload levels and under dynamic preload. The developed design met the requirements established in terms of industrial requirements.