A glazing unit for removing mold separation marks from press molded glassware includes a refractory oven, sized to snugly surround a vertical stack of ware to be treated. The oven is open at the bottom and at the top to permit movement of the ware therethrough. Tangentially arranged inclined nozzles at the upper end of the oven create a downwardly directed swirling blanket of hot gases around the periphery of the stack of ware and these gases exit through passageways at the bottom of the oven. An electric current may be conducted to the periphery of the ware through the hot gases to assist in the remelting of the rim of the ware and means are provided to advance the ware through the oven by adding one piece at a time to the bottom of the stack while removing one piece at a time from the top of the stack.
When blank-molded optical glass bodies are manufactured according to known methods based on blank-molding technology, the product exhibits rings in the glass and folds as well as an impression that precisely coincides with the contact surface of the parison inside the pressing die before the pressing operation. These defects are not permissible in blank-molded lenses, however, because they cause an undesirable optical effect such as changing the glare value in automobile headlights. Such defects are process-dependent and are caused by the fact that the transfer of the parison to the pressing die and the pressing itself are two separate operations that are performed with different tools. According to the invention, the formation of folds and rings in the glass as well as an impression of the contact surface of the parison are prevented by the fact that the removal and the transfer of the parison to the pressing die and the pressing cycle are performed without interruption with one and the same tool (multi-purpose tool). In a further development of the invention, the pressing operation is performed in two steps to take into account the given thermal inhomogeneities in the formed bodies.
A glass vessel edge chamfering method and apparatus wherein heat energy can be controlled readily and chamfering of a glass vessel having a deformed profile, local chamfering and simultaneous processing of the opposite inner and outer sides of a lip of a vessel can be performed readily and besides the efficiency in consumption of energy necessary for chamfering for one glass vessel is improved so that a glass vessel can be processed efficiently in a short time. A pair of positive and negative electrodes are opposed in a predetermined spaced relationship to an edge of a glass vessel, and flame is blown from a pair of burners into gaps between the edge of the glass vessel and the electrodes while a high voltage is applied between the electrodes. Thereupon, electric current flows between the electrodes and the glass vessel by way of the flame and heats the glass vessel by Joule heat when the electric current flows through the glass vessel.
