| 摘要 |
The present invention refers to a threaded coupling for percussion drill rods having a diameter of 30 - 40 mm, comprising an external rod thread and an internal sleeve thread, the longitudinal section of said threads having continuously curved tops and bottoms. In threads of the type mentioned above it is desirable to be able to tighten them to a relatively high degree because otherwise the thread coupling loosenes when used in hydraulic percussive drilling machines of a high frequency. Significant for the thread coupling of the present invention is that the pitch (S) is 7 - 11 mm, the radii of curvature (R1 - R4), at least for the portions of the tops and bottoms located immediately adjacent the contact shoulder, are 3 - 5 mmm, and that the threads have a height (H1,H2) of 1.2 - 1.6 mm. |
