METHOD OF PRODUCING MOLD FOR LENS AND METHOD OF PRODUCING EYEGLASS LENS

摘要

The present invention relates to a method of manufacturing a lens casting mold in which an upper surface of a glass material being formed is formed into a shape of a molding surface for forming a surface comprising a progressive surface or a progressive element by using a continuous heating furnace. As the forming mold, a forming mold having a curvature distribution on the forming surface is utilized. In one aspect, a temperature of the continuous heating furnace is controlled so that the continuous heating furnace comprises a temperature rising region having a temperature distribution such that the temperature rises in a conveyance direction of the forming mold, and a separation distance between the forming surface of the forming mold and a lower surface of the glass material being formed is specified in two or more spots before introduction to the continuous heating furnace. The forming mold is conveyed in the temperature rising region so that a portion with the greatest separation distance among the specified separation distances is comprised in a portion on a side of the conveyance direction as divided in two by a virtual line, the virtual line running orthogonally to the conveyance direction of the forming mold and passing through a geometric center of the forming surface. In another aspect, a forming mold position control region is provided in the continuous heating furnace, a temperature is directly or indirectly measured at multiple measurement points on the forming surface in the forming mold position control region, and the forming mold is conveyed so that a portion on the forming surface of greatest curvature is present in a high temperature portion that has been determined based on the measurement result. A virtual line A passing through a geometric center and a maximum temperature point among the multiple measurement points is specified, and then a portion containing the maximum temperature point as divided in two by a virtual line B running orthogonally to the virtual line A and passing through the geometric center is determined as the high temperature portion.