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Abstract(s)
RESUMO
A indústria automóvel tem uma grande importância na economia global por todos os postos de
trabalho que gera, materiais que explora, ou desenvolvimento técnico e tecnológico que
impulsiona. Associada à indústria automóvel, destaca-se a indústria de componentes automóveis,
responsável por diversos componentes posteriormente utilizados na construção de automóveis,
tais como cabos de controlo. Estes asseguram funções indispensáveis a qualquer automóvel, como
a abertura de portas e janelas, ou o acionamento do travão de mão e do acelerador. O processo de
montagem destes cabos envolve inúmeras etapas, bem como o fabrico dos vários componentes
constituintes, sendo os mais importantes a espiral, revestimento interior e exterior, terminal de
espiral e os terminais. Os terminais de cabo de controlo são pequenas peças obtidas por fundição
injetada, fabricadas em ligas leves e de baixo ponto de fusão, principalmente o zamak, que consiste
numa liga de zinco. Durante este processo de injeção é normal a ocorrência de problemas
associados ao aquecimento do bico de injeção, o que dificulta o processo de extração do terminal
do cabo de controlo do molde de injeção e, em casos mais graves, a paragem do equipamento. A
presente dissertação apresenta três objetivos, pelo que o primeiro consiste no desenvolvimento de
uma nova solução para o aquecimento de bicos de injeção de liga zamak por indução
eletromagnética, para o fabrico de terminais de cabos de controlo. Este aquecimento é realizado
por resistências elétricas, que não permitem um controlo preciso na temperatura dos componentes
ou uma rápida resposta a variações da temperatura do bico de injeção. Foi concluído que, com
recurso a um sistema de indução eletromagnética é possível a solução destes problemas, bem como
a implementação de um sistema mais eficiente, de fácil automação e menos poluente. Em
contrapartida, são esperadas dificuldades, designadamente a determinação de parâmetros como a
frequência e intensidade da corrente elétrica, ou a potência necessária, de modo a maximizar a
eficiência do processo. Destaca-se ainda o elevado custo associado a estes sistemas. O segundo
objetivo encontra-se associado ao conjunto de injeção resultante do processo de injeção. Existe a
necessidade de separar o conjunto de injeção nos seus constituintes, nomeadamente os terminais
e o sistema de alimentação, comummente designado gito, processo que é realizado manualmente.
Isto implica a ocupação do operador responsável pela máquina com uma tarefa repetitiva, não
gratificante e potenciadora de problemas de saúde, principalmente tendinites. O objetivo é o
desenvolvimento de um sistema automatizado pneumático para realizar esta tarefa, o qual
ultrapassou dificuldades como o reduzido espaço disponível e o processamento dos sete tipos
diferentes de peças injetados pela máquina de injeção. O objetivo foi cumprido através da
implementação do sistema automatizado projetado, e resultou numa redução de tempo necessário
para completar a mesma ordem de produção de, aproximadamente, 36 %. O terceiro objetivo deste
trabalho está associado ao terminal de espiral, sobre injetado no revestimento exterior, numa linha
de produção automática. Uma alteração anterior no projeto conduziu à alteração dos moldes de
injeção, o que resultou no aparecimento do gito, anteriormente inexistente neste processo de
injeção plástica. Foi projetado um sistema automatizado para retirar o gito plástico da zona de
injeção, de modo a garantir a continuidade do processo de montagem na linha de produção. O
projeto desenvolvido foi apresentado à empresa, e encontra-se atualmente em construção.
The automotive industry is of great importance to the global economy for all the jobs it generates, the materials it exploits, or the technical and technological development it drives. Associated with the automotive industry is the automotive components industry, which is responsible for various components that are later used in the construction of cars, such as control cables. The control cables provide essential functions for any car, such as the opening of doors and windows, or activating the handbrake and accelerator. The process of assembling these cables involves numerous steps, as well as the manufacture of the various constituent components, of which the most important are the spiral, inner and outer coating, spiral terminal, and terminals. Control cable terminals are small die-cast parts made from light and low-melting point alloys, mainly zamak, which is a zinc alloy. During this injection process it is normal for problems associated with the heating of the injection nozzle to occur, which makes the process of extracting the control cable terminal from the injection mold difficult and, in more serious cases, equipment stoppage. This dissertation has three objectives, the first of which is to develop a new solution for heating zamak alloy injection nozzles by electromagnetic induction for the manufacture of control cable terminals. Heating is normally carried out by electric resistors, which do not assure precise control of the components’ temperature or a rapid response to variations in the injection nozzle temperature. It was concluded that using an electromagnetic induction system could solve these problems, as well as implementing a more efficient, easier to automate, and less polluting system. On the other hand, difficulties are to be expected, namely determining parameters such as the frequency and intensity of the electric current, or the power required to maximize the efficiency of the process. Also noteworthy is the high cost associated with these systems. The second objective is associated with the injection set resulting from the injection process. There is a need to separate the injection set into its constituent parts, namely the terminals and the feeding system, commonly known as the gate, a process that is carried out manually. This means that the operator in charge of the machine is occupied with a repetitive, unrewarding task that can lead to health problems, especially tendonitis. The objective is to develop an automated pneumatic system to carry out this task, which can overcome difficulties such as the limited space available and processing of seven different types of parts injected by the injection machine. The objective was met through the implementation of the designed automated system, which resulted in a reduction in the time needed to complete the same production order of approximately 36 %. The third objective of this work is associated with the spiral terminal, which is over-injected into the outer coating in an automatic production line. A previous change in the project led to a change in the injection dies, which resulted in the appearance of the gate, previously non-existent in this plastic injection process. An automated system was designed to remove the plastic gate from the injection zone to guarantee the continuity of the assembly process on the production line. The project was presented to the company and is currently under construction.
The automotive industry is of great importance to the global economy for all the jobs it generates, the materials it exploits, or the technical and technological development it drives. Associated with the automotive industry is the automotive components industry, which is responsible for various components that are later used in the construction of cars, such as control cables. The control cables provide essential functions for any car, such as the opening of doors and windows, or activating the handbrake and accelerator. The process of assembling these cables involves numerous steps, as well as the manufacture of the various constituent components, of which the most important are the spiral, inner and outer coating, spiral terminal, and terminals. Control cable terminals are small die-cast parts made from light and low-melting point alloys, mainly zamak, which is a zinc alloy. During this injection process it is normal for problems associated with the heating of the injection nozzle to occur, which makes the process of extracting the control cable terminal from the injection mold difficult and, in more serious cases, equipment stoppage. This dissertation has three objectives, the first of which is to develop a new solution for heating zamak alloy injection nozzles by electromagnetic induction for the manufacture of control cable terminals. Heating is normally carried out by electric resistors, which do not assure precise control of the components’ temperature or a rapid response to variations in the injection nozzle temperature. It was concluded that using an electromagnetic induction system could solve these problems, as well as implementing a more efficient, easier to automate, and less polluting system. On the other hand, difficulties are to be expected, namely determining parameters such as the frequency and intensity of the electric current, or the power required to maximize the efficiency of the process. Also noteworthy is the high cost associated with these systems. The second objective is associated with the injection set resulting from the injection process. There is a need to separate the injection set into its constituent parts, namely the terminals and the feeding system, commonly known as the gate, a process that is carried out manually. This means that the operator in charge of the machine is occupied with a repetitive, unrewarding task that can lead to health problems, especially tendonitis. The objective is to develop an automated pneumatic system to carry out this task, which can overcome difficulties such as the limited space available and processing of seven different types of parts injected by the injection machine. The objective was met through the implementation of the designed automated system, which resulted in a reduction in the time needed to complete the same production order of approximately 36 %. The third objective of this work is associated with the spiral terminal, which is over-injected into the outer coating in an automatic production line. A previous change in the project led to a change in the injection dies, which resulted in the appearance of the gate, previously non-existent in this plastic injection process. An automated system was designed to remove the plastic gate from the injection zone to guarantee the continuity of the assembly process on the production line. The project was presented to the company and is currently under construction.
Description
Keywords
Automotive industry Control cable assembly Die casting Process automation Electromagnetic induction