| 摘要 |
PROBLEM TO BE SOLVED: To provide a metal cut chip conveying path having high durability by connecting a plurality of steel pipes by steel-made pipe joints. SOLUTION: A steel pipe-made conveying path 10 is constituted by threadedly connecting steel pipes 12, 14 together with a steel elbow 16 and screwing nipples 18, 20 to the steel pipes 12, 14. An internal peripheral surface 44 of the elbow 16 is quenched to increase hardness higher than internal peripheral surfaces 46, 48 of the steel pipes 12, 14. When metal cut chips are conveyed by generating air flow in the steel pipe-made conveying path, the cut chips collide against particularly the elbow 16, but as it is made of steel to provide high hardness by quenching, wearing is only little. A steel pipe and a steel-made pipe joint are connected in the conveying direction of the cut chip to fit an end part of the upstream to the inside of the downstream, a flow of the metal cut chips may be prevented from being obstructed by eliminating a stepped part in the upstream direction.
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