Heizzeitverkürzung im Kautschukspritzguss unter Ausnutzung der Scher-, Dehn und Kompressionserwärmung

Translated title of the contribution: Cure-time reduction in rubber injection moulding by means of shear- elongation- and compression heating

Leonhard Perko

    Research output: ThesisDoctoral Thesis

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    Cure time represents the largest part of the cycle time in rubber injection moulding. The superposed shear- and elongational heating in conical dies can be used to raise the bulk temperature during the injection of the compound into the mould. To discribe this phenomenon an analytical model for the calculation of bulk temperature with consideration of elongational heating was developed. The material data used are the thermodynamic properties and the shear and elongational viscosity at high deformation rates measured on the High Pressure Capillary Rheometer (HPCR). To get a correct characterisation of the rheological properties of rubber compounds, a new method for temperature correction of shear viscosity and for the evaluation of elongational viscosity was developed. The validation of the calculation model was made in industrial scale experiments on a rubber injection moulding machine using a self-designed test mould for bulk temperature measurements. A series of conical dies with different die angles was characterised. The experiments showed a good correlation to the model predictions with an average error lower than 5%. Conical dies were also used for cure time reduction at the rubber injection moulding machine and the material properties of the produced parts were tested. The injection work was identified as the major influencing parameter on the bulk temperature as well as the cure time reduction. Compression heating for cure time reduction was also investigated in this work. To achieve this, measurements of compression heating at the High Pressure Capillary Rheometer (HPCR) and a rubber injection moulding machine were carried out. The measured temperature increase was around 10°C per 1800 bar pressure for the compounds used. This value could be predicted with good accuracy by an analytic formula as well. Integrating a compression phase into the injection moulding cycle did not lead to a cure time reduction or an improvement of part quality. This work gives a comprehensive insight into the different mechanisms of heating rubber compounds and therefore shows the possibilities and limitation of cure time reductions in rubber injection moulding.
    Translated title of the contributionCure-time reduction in rubber injection moulding by means of shear- elongation- and compression heating
    Original languageGerman
    • Kern, Wolfgang, Assessor B (internal)
    • Friesenbichler, Walter, Assessor A (internal)
    Publication statusPublished - 2014

    Bibliographical note

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    • rubber injection moulding
    • shear heating
    • elongation heating
    • compression heating
    • cure time reduction

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