The aim of this report is to show step by step the internship experience done at FABtotum, a start-up company that produces consumer electronics, particularly a personal fabricator able to 3D print, 3D scan (laser and tactile) and CNC machining. The experience was targeted to the design of the PRISM module, that is a new module that allowed the machine to add to the 3D print function a new artifacts creation method, the stereolithography. The stereolithography is the first additive developed and patented manufacturing technology; it consists in the solidification of a specifical liquid resin thanks to a photopolymerization process, that is related to the light, especially ultraviolet light. This process, polymerizing layer by layer, allows to fabricate rapid complex geometric 3D objects with good surface finishing. Specifically for the PRISM project, the light beam, after passing through the dynamic mask (LCD), comes to the construction chamber, the tank of the resin, from the bottom, it involves some dimensional advantages and requires a system that doesn’t deflect or change the light beam, which must be as diaphanous as possible. This system is commonly called Mask Projection Stereolithography. First of all the design has involved the light beam motion system, but it was carried out in parallel with the designing of other systems (dissipative system, construction chamber system and building plate system) and with light source experimentations that have involved various design choices. In fact the motion and dissipative system design, besides the size and costs project constraints imposed by the company, was first implemented for a laser module or laser diode solution, than to move a 11 LED array, staggered on two rows, afterwards the light source experiments. Also the construction chamber design, typically called vat, has considered the PDMS (siliconic polymer) and FEP (fluoropolymer sheet) experimentations to implement the bottom of a resin tank that allow the solidification of the resin without modifying the light beam. The building plate support system was also dimensioned by respecting the project constraints, especially the need to mount it on the x-y carriage of the FABtotum personal fabricator, and it was also designed with slots in order to manually adjust the inclination and the height as regards the other components, so that it was parallel to the bottom of the vat. After having considered the virtual prototyping, you have proceeded to the realization of the physical prototyping, in order to ensure the effective working of the mechanical system and to go on with a new experimentation on the optical-polymer system (light source with optical lens, LCD, vat and resins). In order to operate the prototype within a suitably modified personal fabricator, you have decided to prototype a provisional electronic system and the IT department has generated a Processing script (based on Java language). The testing on the prototype is still going on as regards the optical component, while the mechanical and thermal design may be considered completed; subsequently it will be necessary to develop a computer code that fits the current one on FABtotum personal fabricator and to turn the attention to the development of a dedicated electronic that is necessary for the operation of the PRISM module.
Questo report ha lo scopo di esporre passo dopo passo l’esperienza di tirocinio formativo svolta nell’azienda FABtotum, start-up produttrice di elettronica di consumo, in particolare di un personal fabricator in grado di stampare in 3D, eseguire scansioni 3D (laser e tattili) ed asportare materiale come un CNC. L’esperienza è stata mirata alla progettazione del modulo PRISM, ovvero un add-on (modulo aggiuntivo) che consentisse alla macchina di aggiungere alla funzione di stampa 3D un nuovo metodo di creazione di artefatti, la stereolitografia. La stereolitografia è la prima tecnologia di manifattura additiva sviluppata e brevettata; consiste nella solidificazione di una specifica resina liquida grazie a un processo fotopolimerico, legato cioè alla luce, in particolare alla luce ultravioletta. Questo processo, polimerizzando uno strato di materiale per volta, consente di ottenere un oggetto di geometria complessa in tempi rapidi e con buona finitura superficiale. Nel caso del progetto PRISM, il fascio luminoso, dopo aver attraversato una maschera dinamica (LCD), arriva alla camera di costruzione, contenente la resina, dal basso, comportando diversi vantaggi, per lo più dimensionali, e necessitando di un sistema che non deflettesse o modificasse il fascio di luce, ovvero il più trasparente possibile. Questo sistema viene comunemente definito Mask Projection Stereolitography. La progettazione ha riguardato prima di tutto il sistema di movimentazione del fascio luminoso, ma è stata comunque svolta in parallelo con quella degli altri sistemi (dissipativo, della camera di costruzione e del piano di stampa) e con le sperimentazioni sulla sorgente luminosa, che hanno comportato diverse scelte progettuali. Infatti il progetto del sistema di movimentazione e dissipazione, oltre a dover tenere in considerazione i vincoli progettuali di ingombro e costi imposti dall’azienda, è stato pensato prima per una soluzione con modulo o diodo laser e poi modificato per sostenere un array di 11 LED, disposti su due file e sfalsati, in seguito alle sperimentazioni effettuate sulle sorgenti luminose. Anche il progetto della camera di costruzione, in gergo vat, ha tenuto conto delle sperimentazioni svolte sul PDMS (polimero siliconico) e sul FEP (foglio di fluoropolimero) per implementare il fondo di un apparato in grado di contenere la resina e permetterne la solidificazione senza modificare il fascio luminoso. Il sistema di sostegno del building plate è stato anch’esso dimensionato rispettando dei vincoli di progetto, ossia la necessità di essere montato sul carrello x-y del personal fabricator FABtotum, ed è stato anche progettato con delle asole al fine di poterne regolare manualmente l’inclinazione e l’altezza rispetto agli altri componenti della macchina, in particolar modo per far sì che fosse parallelo al fondo del vat. Una volta ritenuta conclusa la prototipazione virtuale, si è proceduto alla realizzazione del prototipo fisico, al fine di assicurare l’effettivo funzionamento del sistema meccanico e procedere con una nuova sperimentazione su quello ottico-polimerico (sorgente luminosa con rispettive lenti, LCD, vat e resine). Per poter far funzionare il prototipo all’interno di un personal fabricator opportunamente modificato, si è provveduto a prototipare un sistema elettronico provvisorio e il reparto informatico ha generato uno script Processing (basato sul linguaggio Java). La sperimentazione sul prototipo è tutt’ora in corso per quel che riguarda la componente ottica, mentre la parte meccanica e termica può considerarsi completa; successivamente sarà necessario sviluppare un codice informatico che si adatti a quello già presente per il personal fabricator FABtotum e rivolgere l’attenzione allo sviluppo di un’elettronica dedicata necessaria al funzionamento del modulo PRISM.
Sviluppo del sistema PRISM FABtotum per stampa 3D stereolitografica
PUGLIELLI, BERARDINO
2014/2015
Abstract
The aim of this report is to show step by step the internship experience done at FABtotum, a start-up company that produces consumer electronics, particularly a personal fabricator able to 3D print, 3D scan (laser and tactile) and CNC machining. The experience was targeted to the design of the PRISM module, that is a new module that allowed the machine to add to the 3D print function a new artifacts creation method, the stereolithography. The stereolithography is the first additive developed and patented manufacturing technology; it consists in the solidification of a specifical liquid resin thanks to a photopolymerization process, that is related to the light, especially ultraviolet light. This process, polymerizing layer by layer, allows to fabricate rapid complex geometric 3D objects with good surface finishing. Specifically for the PRISM project, the light beam, after passing through the dynamic mask (LCD), comes to the construction chamber, the tank of the resin, from the bottom, it involves some dimensional advantages and requires a system that doesn’t deflect or change the light beam, which must be as diaphanous as possible. This system is commonly called Mask Projection Stereolithography. First of all the design has involved the light beam motion system, but it was carried out in parallel with the designing of other systems (dissipative system, construction chamber system and building plate system) and with light source experimentations that have involved various design choices. In fact the motion and dissipative system design, besides the size and costs project constraints imposed by the company, was first implemented for a laser module or laser diode solution, than to move a 11 LED array, staggered on two rows, afterwards the light source experiments. Also the construction chamber design, typically called vat, has considered the PDMS (siliconic polymer) and FEP (fluoropolymer sheet) experimentations to implement the bottom of a resin tank that allow the solidification of the resin without modifying the light beam. The building plate support system was also dimensioned by respecting the project constraints, especially the need to mount it on the x-y carriage of the FABtotum personal fabricator, and it was also designed with slots in order to manually adjust the inclination and the height as regards the other components, so that it was parallel to the bottom of the vat. After having considered the virtual prototyping, you have proceeded to the realization of the physical prototyping, in order to ensure the effective working of the mechanical system and to go on with a new experimentation on the optical-polymer system (light source with optical lens, LCD, vat and resins). In order to operate the prototype within a suitably modified personal fabricator, you have decided to prototype a provisional electronic system and the IT department has generated a Processing script (based on Java language). The testing on the prototype is still going on as regards the optical component, while the mechanical and thermal design may be considered completed; subsequently it will be necessary to develop a computer code that fits the current one on FABtotum personal fabricator and to turn the attention to the development of a dedicated electronic that is necessary for the operation of the PRISM module.| File | Dimensione | Formato | |
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2016_04_Puglielli.pdf
Open Access dal 10/04/2019
Descrizione: Testo della tesi
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https://hdl.handle.net/10589/118286