| 摘要 |
PURPOSE:To obtain a sufficiently strong U-shaped glass tube having no glass gob at the root of the leg parts by joining two glass tubes so that they communicate with each other and by forming the joined part with a die split into two along a plane passing through the centers of the two glass tubes and provided with central projections with a gap in-between. CONSTITUTION:Two glass tubes 1, 1 are arranged parallel to each other and flames from burners 6 are jetted on prescribed parts of the tubes 1,1 to make a hole 12 and to directly join the tubes 1, 1 to each other with the glass of the tubes 1, 1 pressed against the edge of the hole 12. The periphery of the joined part is then softened by heating, the joined part is put in a die 9 having a U-shaped recess and a U-shaped glass tube is formed. The die 9 used is a die split into two along a plane passing through the centers of the tubes 1, 1 and provided with opposite central projections 92 with a gap in-between.
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