| 摘要 |
Burrs which develop on the incomplete thread at the start of cutting of male threads (1) of a threaded joint and which are a cause of galling when connecting oil country tubular goods are eliminated. In the incomplete thread, the upper portion (11a) of a thread (11) having a pointed crest with a generally triangular cross-section (typically a beveled portion) is cut off to form a thread having a trapezoidal cross section and a crest face (11c). Cutting off of the upper portion (11) is carried out such that the angle ¸ formed between the crest face (11c) and the flank on the side opposing a thread (12) of a complete thread is an obtuse angle, and the thread height h from the root of the flank is at least 0.2 mm. Cutting is preferably carried out under the same feed conditions as in machining of the male threads. |
