| 摘要 |
1298095 Applying predetermined tension to bolts MAC LEAN-FOGG LOCK NUT CO 15 Sept 1970 [15 Sept 1969] 44055/70 Heading F2H A method of controlling the clamping force exerted against workpieces 24, 25 by a threaded fastener which initially embodies a pair of nuts 20, 22 acting against one workpiece surface and each co-acting with a bolt 23 acting in opposition against another workpiece surface comprising the steps of (a) tightening the nuts 20, 22 on the bolt 23 and against the workpiece 25 until a predetermined clamping force between the nut 20 and workpiece 25 is sensed (b) releasing the force beteween nut 20 and workpiece 25 without moving the nut 22, to transfer the load thereto with some reduction of its magnitude and (c) tightening the nut 22 against the workpiece 25 by turning it through a predetermined angular increment relative to the bolt 23. A relievable torque driving connection is obtained between nuts 22, 20 by punching opposed depressions 38 into the outer nut 20 to produce protuberances 39 frictionally engaging the inner nut 22 whereby the nut 22 can be tightened initially by a tool applied to a polygonal collar portion 27 extending from a threaded ring portion 29 of the nut 20. The predetermined clamping force is sensed and transferred when a section 32 between the collar 27 and ring 29 ruptures axially. In one embodiment, Fig. 6 the collar 27 may be removed after rupture of the section 32 but in another, Fig. 8, it is held captive by a flange portion 42 of the ring 29 with flats aligned initially with those of the collar 27. In either case the ring 49 may be ultimately tightened against the nut 22 to serve as a lock nut. The final angular increment to be turned by the nut 22 relative to the bolt 23 is so determined that the clamping force sensed is reestablished, the increment being proportional to the clamping force and inversely proportiona to the compression characteristic of the nut 22. The clamping force may be controlled to restrict the bolt tension within the safe load limit of the bolt by suitably selecting the predetermined clamping force to be sensed. |
