Influence of swabbing compounds on loading, heat transfer and release performance in hot glass forming
Résumé
In the glass container manufacturing industry, hot moulds are regularly swabbed with a lubricant during production. The swabbing lubricant facilitates the loading of glass into a mould, reduces heat exchange when the glass comes into contact with the mould and expedites the release of the glass after forming. Swabbing lubricants generally contain ap- proximately 70% petroleum oils and volatile products, 20% thickeners, soaps and binders, and 10% solids. The main compounds of the solid portion are graphite and sulphur. Adjusting the proportion of the solids affects heat transfer, thereby influencing the mechanical performance of the swabbing lubricant. The TEMPO Laboratory has an experimental Glass/Tool Interaction (GTI) rig, which is a reduced-scale production unit that reproduces industrial glass forming conditions. Each forming cycle of the GTI rig combines a pressing phase, during which the hot glass is pressed by the punch, and a subsequent punch rotation phase. The presence of thermocouples and force sensors makes it possible to study thermal and mechanical behaviours at the glass/punch interface. The aim of this study is to use the GTI rig to evaluate the influence of graphite and sulfur on heat transfer and mechanical performance. This influence is determined by analysing the temperature changes in the punch and the critical and maximum forces during the rotation of the punch in contact with the hot glass.