| 摘要 |
PROBLEM TO BE SOLVED: To provide a clogging prevention structure for a powder transportation pipe capable of preventing the clogging of a pipe caused by the deposition of powder at an elbow of the pipe and performing the stable feeding of the powder. SOLUTION: A relay box 2 of stomach shape comprising an upstream part 21 having a passage cross section area enlarged as it advances from an entrance 21a to a downstream side; and a downstream part 22 having the passage cross section area narrowed as it advances from the upstream part side to an exit 22a is provided at the elbow 3b of the pipe for transporting the powder by gas. The upstream part and the downstream part are connected so as to form an angleθof 100-120°. Further, the connection of the entrance of the upstream part, the exit of the downstream part and the pipe 3 is performed such that no step is generated on the inner surface of the connection part. COPYRIGHT: (C)2007,JPO&INPIT
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