Innovative drive concept for machining robots

In this paper an innovative drive concept for robots to improve their machining capability is presented. As a test bed a two-axis robot is designed and equipped with torque motors with load-sided high resolution encoders in addition to conventional gear motors with harmonic drive gearboxes. The gear motors are used for positioning tasks while the torque motors in particular compensate static and dynamic load-sided angle errors. The model-based control algorithm is decoupled and separately actuates both the servo gear and torque motors. It is shown that a considerable increase of performance is possible when adding the torque motors especially regarding the compensation of dynamic angle errors. The paper will present the design and details of the new drive concept, the modeling basics and first simulation results

Close-to-process compensation of geometric deviations on implants based on optical measurement data

The production of implants is challenging due to their complex shapes, the filigree structures and the great regulatory effort. Therefore, a manufacturing cell with an integrated optical measurement was realized. The measurement system is used to determine the geometric deviations and to fulfill the documentation obligation. The measurement data are used to create a matrix containing the nominal coordinates and the error vector for compensation points at the relevant shapes. Based on this, the corresponding tool-path segments are isolated in the G-Code and compensated in order to reduce the geometric deviations. With this method, the deviation could be reduced by 85 %. However, it is pointed out, that the result of the compensation strongly depends on the quality of the optical measurement data

CAPACITACIÓN DE UTILLAJES FLEXIBLES PARA SU USO EN PROCESOS DE MECANIZADO DE ALTA CALIDAD: UN CASO DE APLICACIÓN DEL PARADIGMA INDUSTRIA 4.0

The incipient implementation of the Industry 4.0 paradigm has led to an increase in the machines sensoring level, in the processes optimization and, thus, in the product manufacturing with a higher added value. In this article a new aspect is described where, through the machine monitoring, the utilization of innovative elements as fixture is enabled for high quality machining processes. These innovative elements are characterized by the great flexibility offered by them as holding component and by their low costs. However, these elements lack the enough geometrical accuracy for applications where a high shape and surface quality product are needed. First of all, in order to have a clear vision of the singularities of each fixture type present on the state of the art, a nomenclature and a classification has been proposed based on their geometry characteristics. Hence, based on this classification, an analysis of the different fixturing solutions provided by the market has been made, enhancing the advantages of this solution against the existing ones. With the aim of demonstrating its suitability for certain machining applications, the behavior of these sort of flexible materials has been characterized. Besides, the sensors implementation has been analyzed in order to capacitate this solution for processes where tough tolerances on parts are demanded. Therefore, this survey demonstrates that, through the massive information gathering, not only an optimization of the existing technologies is obtained, but it is possible to develop innovative solutions that provide improved capacities to the already existing ones in the Industry.Financial support from the Basque Government under the ELKARTEK Program (AERO3NAK project, grant number KK-2017/00033) is gratefully acknowledged by the authors

Tool path adaption based on optical measurement data for milling with industrial robots

Industrial robots are used in a great variety of applications for handling, welding and milling operations. They represent a cost-saving and flexible alternative for machining applications. A reduced pose and path accuracy, especially under process force load due to the high mechanical compliance, restrict the use of industrial robots for further machining applications. Test results showed that these deviations range up to 0.6 mm. In this paper, a method is presented to determine the resulting path deviation of the robot under process force by using a structured light scanner. The obtained data is compared with the CAD (Computer Aided Design) data of the machined part within a developed software module. Additionally, the developed module provides functions for manipulation, registration of STL (Surface Tessellation Language) surface point clouds and a postprocessor for program translation. The comparison is performed using a dexel discretization of each data set. Based on this comparison the robot path is adapted to improve the machining quality. This method can be applied to 3- and 5-axis machining operations. The results show that the deviation can be reduced to 0.1 mm

Desarrollo de sistema flexible de fabricación de pieles aeronáuticas por mecanizado mecánico.

215 p.Esta tesis doctoral presenta el desarrollo y caracterización de una solución flexible y de bajo coste que permita la fabricación de pieles aeronáuticas de aluminio mediante mecanizado convencional. Este concepto se basa, por un lado, en la adaptación e integración de láminas de goma de nitrilo butadieno (NBR) como utillajes flexibles de vacío. Por otro lado, de cara a compensar la diferencia de tolerancia de espesor de este tipo de elementos flexibles con los requisitos de espesor demandados en la industria, se plantea la integración de diferentes elementos de monitorización que permitan la adaptación de la trayectoria de la herramienta. Así, se pretende que este sistema sea capaz de fabricar este tipo de piezas aeronáuticas esbeltas sin tener que recurrir a tecnologías de bajo rendimiento, como el fresado químico, o incurrir en grandes inversiones, como las soluciones de fresado mecánico mediante máquina de doble cabezal