| 摘要 |
<p>Provided is a manufacturing method for a seamless steel pipe in which a small diameter thin-walled pipe is drawn by means of a tapered die (1), which is used as a processing die and is provided with an approaching part (1a) that has a tapered shape, and a bearing part (1b) that delimits the outer diameter in the drawing process, and a plug (2), which is inserted into the inner surface of a pipe (3) that is being drawn while the diameter of the pipe is being reduced by the tapered die (1). As a result of using the tapered die (1) wherein the approaching part (1a) forms an angle (a) of 15 - 20°, it is possible to reduce the striations on the inner surface of the pipe which occur during a hot pipe-manufacturing process without increasing the thickness of the base pipe, and thereby obtain a small diameter thin-walled pipe with a high quality inner surface. In the disclosed manufacturing method for a small diameter thin-walled pipe, it is preferable for the plug (2) to be a semi-floating plug provided with a finishing part (2b), which regulates the finished inner diameter of the pipe and a tapered part (2a), which is contiguous with the finishing part.</p> |
