| 摘要 |
<p>An activating device is mounted in a drill string to control the activation and deactivation of an enlargement tool used for enlarging a bore hole. In order to assemble the activating device, pistons are mounted in passages and spline bars, in which plates are screwed, are then slid along T-slots of the body, through apertures of the pistons. In order to deploy the pistons and cutters, pressurized drilling fluid is applied to the inner faces of the pistons. When a pre-determined pressure level is reached, screws break and the pistons move from the inward position to the outwardly deployed position.</p> |
