article posted 21 March 2016
Gesine Bergmann works at the HVG/DGG in Offenbach She specialises in hot forming of glass: temperature measurement; temperature distribution of the glass from feeder channel to blow mould; interactions between mould materials, glass, and swabbing materials.
The strength and fracture of glass.
Emission measurements in the flue gas of glass furnaces; quality control based on DIN EN ISO/IEC 17015.
Influences on the temperature distribution of gobs as a precondition for the production of lightweight hollow ware
G. Bergmann, N.-H. Löber, J. Simon, H. Müller-Simon
Research Association of the German Glass Industry (HVG-DGG), Siemensstraße 45, 63071 Offenbach, Germany
The decrease in the weight of glass bottles and jars is on top of the wish list of customers all over the world. Especially for the blow-blow-process a more uniformly distribute wall thickness distribution is a key for lightweight bottles. Due to the fact that viscosity is inseparably linked to the temperature, a basic requirement therefore is a known and adapted temperature distribution of the gobs before loading. The resulting temperature distribution of the gob just before the blank is affected by the flow conditions in the spout and by the flow out conditions before the shear cut. Another very important part is the delivery. Due to the fact of different length of the trough and the deflectors, the blanks have to run with different gobs.
The paper deals with industrial data on one hand and model based calculations on the other hand. As an introduction the influence of the pull rate and the direction of tube rotation on the temperature distribution of the pristine gobs will be discussed. The main part focuses on the delivery system. The influences of different delivery properties like the material of the trough, possible effects of different coatings of the trough and the results of changing environmental conditions will be discussed. The paper will not only focus on the temperature of the gob but will also treat the effects on gob speed or gob length and will also raise the topic of the gobs movement pattern inside the delivery. Last but not least the calculated heat transfer coefficients will be discussed. As a result of the research we are able to calculate and characterize the inside temperature distribution of the gobs after cutting and we are also able to predict the resulting temperature distribution of the gobs after leaving the delivery system.