Deutsche Spezialglas Ag

Thomas Schonfeld, Executor

Gunter Schonfeld, Deceased

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.

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Berlin, Germany

Thomas Schonfeld, Executor