| 摘要 |
A method for pretensioning a joint to a predetermined clamping load level, which joint is apt to settlement during pretensioning and comprises two or more threaded fasteners (15 a-d) to be tightened by a simultaneous engagement of individually rotated and controlled torque delivering tools (19 a-d), comprising the steps of: I) applying simultaneously a tightening torque on each one of the fasteners (15 a-d), II) measuring during the torque application the instantaneous axial load (F) in each one of the fasteners (15 a-d), III) interrupting the torque application on each one of the fasteners as the axial load (F) on the respective fastener (15 a-d) has reached a predetermined axial load (FT) which corresponds to the intended clamping load level in the joint (10), IV) reapplying a tightening torque one or more times on that fastener or those fasteners (15 a-d) on which the axial load (F) has decreased due to settlement of the joint (10) during one or more relaxation time intervals so as to regain the predetermined axial load level (FT), and V) terminating the pretensioning process of the joint (10) as the axial load (F) has remained substantially unchanged at the predetermined axial load level (FT) for a final time interval in all of the fasteners (15 a-d), thereby providing the intended clamping load level in the joint (10). |
