| 摘要 |
A centraliser (13) has two spaced annular end collars (18, 19) interconnected by a plurality of longitudinally extending spring bows (16). Each end of each spring bow (16) is profiled, and is received within a cut out in the respective end collar (18, 19) such that circumferentially extending projections (22) of the end collar (18, 19) are received within corresponding recesses (24) in the ends of the spring bows (16). These mechanical interconnections are also welded. The resulting joint between each end of each spring bow and the respective end collar has a high degree of rigidity, and this produces high radially acting restoring forces. Furthermore, the position and configuration of the welds enables loads on the centraliser to be received and transmitted by the material of the spring bows (16) and of the end collars (18, 19). As a result, the overall diameter of the centraliser (13) can be reduced to be a sliding fit within a borehole. The centraliser (13) is thereby able to provide low starting and running forces yet high restoring forces. |
