| 摘要 |
PURPOSE:To enable sure extrusion-drawing and grooving by expanding the diameter of a pipe by a floating plug and exerting thrust on the floating plug with a stock pipe. CONSTITUTION:A floating plug 1 of which the outside diameter in the intermediate cylindrical part is larger than the bore of a stock pipe 40, a grooved plug 50 which is provided successively with the plug 1 and has many grooves 60 on the surface and a compressing device 10 which houses these plugs oppositely to each other in the axial center thereof, are used. The pipe 40 is thereupon expanded in diameter by the plug 1 and in succession the pipe is reduced in diameter by the approach part 11 of the device 10; further the pipe 40 is grooved by the grooving part 101 of the device 10 while the pipe is compressed between said part and plug 50. The sure extrusion-drawing and grooving are thus made possible and productivity is improved.
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