Monitoring and control of metal-based additive manufacturing technologies

This work shows the development of monitoring and control strategies for additive manufacturing (AM) processes. An arc-length control system and a PID temperature control system were developed for Wire-arc AM processes. An Oxygen monitoring/control system with a shielding gas crossflow was developed for Powder based fusion (PBF) processes. The arc-length control system delivered a constant transfer mode and allowed for consistent temperature measurements whilst drastically improving process stability and part appearance. Small improvements where observed with the use of the PID temperature control system. Maximum temperatures were reduced by approximately 200°C. The results indicate a successful temperature control system requires the use of an independent arc-length control system. For PBF, a controlled environment capable of maintaining oxygen levels of 1ppm during the entire build process was designed. A simple monitoring/control system was developed to ensure the machine did not operate over a user selected oxygen concentration threshold. A laminar cross-flow device was developed to remove unwanted by-products generated by the PBF process. High speed imaging experiments were used to test the validity of the crossflow. The results show, that the use of a laminar crossflow device leads to a drastic improvement in process stability

Desenvolvimento de laboratório de experimentação remota didático para aprendizagem na área da conformação mecânica

Esta tese trata do desenvolvimento de um laboratório remoto didático para estudos na área da Conformação Mecânica, chamado de Laboratório Online de Conformação Mecânica (LABCONM), o qual visa proporcionar a aprendizagem da Conformação Mecânica usando experimentos reais operados remotamente. Este laboratório é formado por duas partes principais: A primeira parte é um Sistema de Gerenciamento de Aprendizagem (SGA) contendo todos os menus, atividades e tarefas, agenda e painel de acesso e controle aos experimentos. A segunda parte é a parte física, ou seja, o experimento remoto, que nesta primeira versão do LABCONM é a “Máquina Didática Teleoperada de Ensaio de Compressão” (MDTEC). No painel de controle da MDTEC o estudante controla e visualiza remotamente um ensaio de compressão real e exporta os dados. Uma atividade de aprendizagem experimental foi desenvolvida para guiar os estudantes na busca da solução do problema, gerando assim a aprendizagem da curva de escoamento. Para validar o laboratório, foram feitos dois tipos de testes: O primeiro é funcional e técnico, que analisa os resultados do experimento remoto, avaliando a similaridade e a repetibilidade para fins didáticos. E o segundo teste é uma validação acadêmica, que foi dividida em duas partes. A primeira, foi direta, e feita por um grupo de estudantes da disciplina de Conformação Mecânica, onde responderam questionários após uso do laboratório. A segunda etapa foi indireta, feita pela comparação das notas da prova entre os estudantes que "usaram" com aqueles que "não usaram" o laboratório, visando obter a influência do uso do laboratório na aprendizagem. Os resultados dos testes técnicos e funcionais mostram que a MDTEC é um experimento que tem condições de realizar ensaios de compressão reais, fornecendo dados com boa repetibilidade para levantamento de curvas de escoamento. Na avaliação dos estudantes o LABCONM demonstrou ter cumprido com o objetivo de ensino aprendizagem. Em relação à avaliação da prova aplicada com ambos os grupos de estudantes com e sem acesso ao LABCONM, observou-se que houve uma influencia positiva nos resultados da turma que acessou o laboratório, visto que nenhum destes estudantes do grupo teve nota insatisfatória no exercício de cálculo.This thesis deals with the development of a remote didactic laboratory for studies in the area of Metal Forming, called the Online Laboratory of Metal Forming (LABCONM), which aims to provide the learning of the Metal Forming using real remotely operated experiments. This lab consists of two main parts: The first part is a Learning Management System (SGA) containing all the menus, activities and tasks, agenda and access panel and control to the experiments. The second part is the physical part, that is, the remote experiment, which in this first version of LABCONM is the "Teleoperated Testing Machine for Compression Testing" (MDTEC). In the MDTEC control panel the student remotely controls and visualizes a real compression test and exports the data. An experimental learning activity was developed to guide the students in the search of the solution of the problem, thus generating learning the flow curve. To validate the laboratory, two types of tests were performed: The first one is functional and technical, which analyzes the results of the remote experiment, evaluating similarity and repeatability for didactic purposes. And the second test is an academic validation, which was divided into two parts. The first one was direct, and made by a group of students of the discipline of Mechanical Conformation, where they answered questionnaires after using the laboratory. The second stage was indirect, made by comparing test scores among students who "used" those who "did not use" the laboratory, in order to obtain the influence of the use of the laboratory in learning. The results of the technical and functional tests show that the MDTEC is an experiment that is able to perform real compression tests, providing data with good repeatability for survey of flow curves. In the evaluation of the students the LABCONM has demonstrated to have fulfilled with the objective of teaching-learning. Regarding the evaluation of the test applied with both groups of students with and without access to LABCONM, it was observed that there was a positive influence on the results of the group that visited the laboratory, since none of these students of the group had an unsatisfactory grade in the calculation

Online Temperature Control System

In this paper, a remote temperature control system has been proposed. The physical system is controlled in real time through the Internet network. For educational purpose, the students use only a web browser to tune and test a PID controller via shared user interface. The PID parameters are calculated using the basic experimental Ziegler—Nichols tuning rules. After hardware and software experiment description, the remote online experiment is tested and the results are given