PURPOSE: To enable accurate positioning of an optical glass raw material to the forming point.
CONSTITUTION: A cylinder 29 is attached to a transfer arm 21 for an optical glass raw material 5. A stopper rod 32 is placed above the transfer arm 21 and held in a state freely movable in the direction same as the extending direction of the transfer arm by the cylinder 29 attached to the upper face of the transfer arm 21. The stopper rod 32 is constantly pressed toward a forming chamber 8 by a spring placed in the cylinder 29. A stopper plate 35 contacting with the tip end of the stopper rod 32 is placed in the main heating furnace 7. The transfer arm 21 and the stopper rod 32 are made of the same material. The optical glass raw material 5 supported by the transfer arm 21 is made to be positioned at the forming point 9 when the stopper rod 32 is brought into contact with the stopper plate 35. Since the thermal expansion of the stopper rod 32 is equal to that of the transfer arm 21, the optical glass raw material can be transferred to the forming point 9 even by changing the heating temperature of the optical glass raw material 5.
MITSUSAKA MOTOSUKE
IWASAKI NOBUYOSHI
