Glass conditioning by viscosity control

During the forming process of a glass melt the viscosity is the dominant process parameter. Up to now in the industrial container glass production only temperature-controlled systems have been used. With these control elements only thermally induced variations of the viscosity are visible. Variations in the composition, the redox state, the water and the SO3 content in the melting process cause a shift in the viscosity. Up to now these changes have not been detectable and therefore, it has not been possible to compensate them. A measuring device for the continuous determination of the viscosity in the glass was developed and tested for several months in a container glass plant. All measured variations of the viscosity can now be corrected by the existing control elements for the thermally controlled glass conditioning. Dependent on the position of the viscosimeter in the feeder channel, a feedforward or feedback controlling concept is practicable.