The thermoforming process is only one of the many manufacturing methods that converts plastic material into numerous products. As with many thermoforming companies the process is not used to its full potential. The major goal of this work was to develop a non-isothermal simulation of the plug assisted thermoforming process which has direct practical relevance with the thermoforming industry. The simulation would be used as design tool to help improve the process, enabling investigations into changes in product/tooling design and processing conditions, prior to production. Development of robust and accurate simulations has been difficult due to the interactions that exist between the key process elements, such as; highly non-linear material response, heat transfer and friction. For these reasons a fUlly coupled non-isothermal simulation of the plug assisted thermoforming process does not exist. To reduce the scope of this work a previously developed constitutive material model capable of predicting the deformation response of the material used in this work was adopted therefore allowing for more simulation and experimental investigations. . . A detailed experimental programme was carried out on a single shot experimental thermoforming machine to investigate the effect of the major thermoforming processing variables such as plug speed, sheet temperature etc. In addition a series of friction and heat transfer experiments were conducted using specially adapted test equipment in an attempt to isolate and understand each contact phenomena better. The information obtained from the experiments was used in the construction and validation of the developed simulation which was carried out using the finite element package ABAQUS®/Standard. Initial isothermal simulations were used to investigate the effects of friction only on the simulated output. The simulation capabilities were improved by incorporating heat transfer effects and a fully coupled temperature dependant simulation is presented. The peiiormance of the simulation was validated against the experimental data obtained from the thermoforming trials and the trends observed were highly comparable. The overall project goals were met with the development of a working nonisothermal simulation incorporating all aspects of the plug assisted thermoforming process such as heat transfer and friction, however further work is required on the constitutive material modelling aspects of the work to improve the simulation capabilities.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:486260 |
| Date | January 2007 |
| Creators | McCool, RauriÌ |
| Publisher | Queen's University Belfast |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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