| 摘要 |
PURPOSE:To make a long-sized double tube by inserting an inner tube into an outer tube by bringing an outside diameter of the inner tube to be smaller than an inside diameter of the outer tube by a prescribed dimension and then press fitting the outer and inner tubes by plastically deforming the outer tube. CONSTITUTION:An inner tube 2 whose outside face has slits 4 and whose inside surface has grooves 3 in the axial direction is formed to have the same length as that of an outer tube 1 and the outside diameter of the tube 2 is worked to be smaller than an inside diameter of the outer tube 1 by a prescribed dimension. After inserting the tube 2 into the tube 1, a pressure F is applied to a groove 5b formed on the peripheral surface of the tube 1 to plastically deform the tube 1 in the peripheral direction and to tightly adhered to the tube 2. Thus, the stoppage on the way of the inner tube due to galling, etc., are eliminated, so that the long-sized double tube is easily formed.
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