| 摘要 |
PURPOSE:To raise the production speed without lowering the yield of production by making the retreating speed of butt plate slower than its advancing speed. CONSTITUTION:The flared portion 2a and the bulb end edge 1a, or a sealing portion, are preheated by weakened flame of the burners 3. Then, the sealing portion including the portions 1a and 2a is softened by intensified flame of the burners 3 and the butt plate 4 is advanced so as to press the flared portion 2a onto the bulb end edge 1a for thermally bonding them. Then, the butt plate 4 is retreated and then the sealing portion including 1a and 2a is again heated for the completion of sealing. In this case, the retreating speed of the butt plate 4 is made considerably faster than its advancing speed. |
