Motor-driven screwing and transporting tool for reactor pressure vessel head retaining fastenings
AssigneeKraftwerk Union Aktiengesellschaft
InventorManfred Scholz
Life of this patent
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Abstract
The invention concerns a motor-driven screwing and transporting tool for tightening or loosening the threaded studs and associated tightening nuts of the head bolting of pressure vessels. After the tightening nuts are loosened or before they are tightened, the weight of the studs is taken over by rotating bearings that can be lifted, so that the studs with their tightening nuts can be screwed in or out, the screw threads of the studs being thus weight-relieved. The invention is intended primarily for nuclear reactor pressure vessels.
Claims21
A device for unscrewing and screwing nuclear reactor pressure vessel head-retaining nuts and screw studs, the studs extending upwardly through stud holes in a head flange of a removable head of a reactor pressure vessel, the studs having threaded lower ends screwed into threaded holes in the pressure vessel's top and threaded portions on which the nuts are screwed above the head flange to hold down the head on the pressure vessel with the studs under pretension between the vessel's top and the nuts, the nuts having external gear teeth for their rotation and the studs having upper ends spaced above the nuts;
- said tool comprising a support body and means for supporting said body at controllable heights on said head flange;
- and unscrewing and screwing units for said nuts and studs, mounted on said body and having axial passages for releasable insertion of the studs and nuts;
- each of said units for a stud and nut when inserted in the unit's passage, having a pinion releasably meshing with the nut's said gear teeth and means for reversingly driving said pinion for unscrewing and screwing movements of the nut on the stud, gripping means for releasably gripping the upper end of the stud above the nut, and means for applying upward force to said gripping means for stretching the stud upwardly from the pressure vessel's top to free the nut from said pretension during said movements;
- each of said units further having means for releasably engaging said reversibly rotating the stud so its said lower end can be unscrewed and screwed in the threaded hole in the pressure vessel's top while the nut remains screwed on the stud, and means for applying a lifting force to both the nut and stud to relieve the stud's said lower end from the weight of the nut and stud while being unscrewed and screwed in the pressure vessel's threaded hole.
A device for securing or releasing a connector capable of connecting a first member to a second member, the connector comprising a stud having a threaded end region and a threaded intermediate region, and an adjusting nut on the threaded intermediate region, the arrangement being such that, during connection, the stud extends through an aperture in the second member and is located at its threaded end region in a threaded hole in the first member, with the adjusting nut on that side of the second member remote from the first member and urging the second member towards the first member;
- the device comprising:
- a support which is intended to be adjustable parallel to the axis of the stud, and, carried by the support:
- 1. means for gripping an end region of the stud remote from the said threaded end region;
- 2. means for axially extending the stud;
- 3. first drive means for rotating the adjusting nut relative to the stud;
- 4. second drive means for screwing and unscrewing the stud (and the adjusting nut carried thereon) relative to the first member;
- and
- 5. lifting means for taking up the weight of the stud and adjusting nut while they are being acted upon by the second drive means.
Dependencies are inferred from the claim text.