Abstract: An apparatus for mixing or homogenizing viscous material is disclosed. Stirrers, comprising multiple vane mixing blades are mounted on a pair of parallel shafts in corresponding spaced apart parallel tiers. Each vane has a working surface inclined relative to the shaft and offset relative to the vanes of an immediately adjacent blade. One shaft is advanced relative to the other so that the vanes intermesh. The inclination of the vanes in one blade is mirrored in sense to the other blade on the adjacent shaft, and the shafts are rotated in opposite sense so that the stirrers in each tier pump the material in the same relative direction when the shafts are so rotated.

Abstract: A furnace for melting thermoplastic material, such as glass, includes a vertical furnace with electrodes at different levels immersed to different depths in the molten material. The convection currents and size, shape and stability of the fusion zone are controlled by changing the amount of power and the depth of immersion of the electrodes at different levels. For example, the electrodes in one of the lower tiers extend closer to the center of the furnace to produce a central upward convection current, to prevent an unstable fusion zone due to temperature gradients from wall to center, and to decrease the temperature near the furnace wall. For glasses with steep temperature-resistivity relationships and/or high infra-red absorption characteristics, the advantages of using differently immersed electrodes are even more significant.

Abstract: An apparatus for heating glass-forming materials within a delivery conduit extending from an electric glass melting furnace to a connector channel is disclosed. The conduit is made from an electrically conductive refractory metal such as molybdenum and is used to conduct current from inside the furnace to its exit end in the channel. Joule effect heating between the exit end of the conduit and an electrode in the connector channel indirectly causes the glass materials within the conduit to partially melt, to the extent that the materials within the conduit may be exhausted from the conduit. A flange assembly for use with a molybdenum conduit is also disclosed.

Abstract: An apparatus and method for determining the elevation of the fusion interface between batch and molten glass in an electric glass-melting furnace is disclosed. A probe is driven vertically downwardly through the batch by a combination of a motorized drive assembly and a pneumatic hammer device. When the bottom tip of the probe penetrates the fusion interface, a current path is established from a furnace electrode through the molten glass to the probe tip, with such current flow thereby giving indication that the probe tip has descended to the elevation of the fusion interface.