| 摘要 |
PROBLEM TO BE SOLVED: To prevent the front core from being bent by thermal stress due to shrinkage at the time of glass solidification by imbedding in the track groove a dummy core for relaxing thermal stress during the solidification of molten glass. SOLUTION: When a dummy core 3 is inserted in the track groove 2 of a core member 1, in the care molten glass 5 is filled in the track groove 2, it facilitates the insertion since the upper part of the dummy core 3 is connected with a connecting rod 6. Also, the dummy core 3 is connected with a specific pitch and, therefore, inserted into the track groove with high precision. After that, by grenadine the connecting rod 6 of the dummy core connector 4 which is on the side of the face abutting on the back core, the front core 7 is completed. The absolute quantity of the molten glass 5 inside the track groove decreases by the volume of the dummy core; hence, it can relax the shrinkage due to the thermal stress caused at the time of solidification of the molten glass 5.
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