| 摘要 |
A coupling thread structure for percussion drill elements including a rod (10) having an external thread (14), and a sleeve (24) having an internal thread (26) with the threads, when the sleeve and rod are coupled, having abutting (16) and non-abutting (18) flanks and with the flanks being joined by bottom (22) and crest (20) portions, wherein the threads have at least two starts; the abutting flanks (16) are substantially straight along their whole abutting contact portions (CL) and form an angle of between 10 DEG and 25 DEG , preferably 15 DEG to 20 DEG , with the drill axis; the pitch angle of the threads is in the range 9 DEG to 20 DEG , preferably 11 DEG to 16 DEG ; the crest portions (20) are substantially straight and intersect the abutting flank (16) portions at a well defined edge (30); the non-abutting flanks (18) have a flank angle which is considerably greater than that of the abutting flanks (16); the flank angle of the non-abutting flanks (18) is in the range 50 DEG to 80 DEG , preferably 65 DEG to 75 DEG , with respect to the drill axis; and the bottom portions (22) of the threads (14,26) are curved. |
