| 摘要 |
The rod included in each drill string component for transmission of striker energy to the drill crown at the string lower end is surrounded by a tubular unit for transmission of rotation to the drill crown. The tubular unit produces a space for drilling fluid between it and the bar, and has two internal dia. reductions which are displaced towards its ends. - The bar has radial projections which are displaced towards its ends, whereby the internal dia. reductions and the radial projections are dimensioned to prevent the bar falling out of the tubular unit. The tubular unit is formed in one piece, and at least one of the dia. reductions is arranged on a separate element, and components are provided for axially fix the separate element in relation to the tubular component. The internal dia. reductions are in the form of a seat. |
