Implements or apparatus for applying pushing or pulling force – Pipe or rod jack – Tie rod tensioner
Patent
1996-08-02
1998-09-08
Watson, Robert C.
Implements or apparatus for applying pushing or pulling force
Pipe or rod jack
Tie rod tensioner
E21B 1900
Patent
active
058034366
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a tensioning device for threaded bolts with a cylinder resting on a machine part to be clamped by a threaded bolt and a nut, with a piston sealingly guided therein and supported with a threaded bushing, threaded onto a threaded end of the threaded bolt, and with a safety catch.
Known hydraulic tensioning devices for threaded bolts are comprised of a cylinder resting on the machine part to be clamped with a threaded bolt and a nut, in which a piston is sealingly guided. This piston rests on a threaded bushing that is threaded onto the threaded end of the bolt. In order to stretch the bolt, hydraulic oil is introduced under high pressure into the space between the piston and the cylinder so that the piston is displaced and entrains the threaded bushing threaded onto the threaded end of the threaded bolt. As a function of the pressure and the piston surface area as well as the diameter of the threaded bolt, a tensioning of the threaded bolt takes place and a nut threaded between the machine part and the threaded bushing can be tightened from the exterior without torsional moment until it abuts the machine part. This can be achieved either by turning a bushing, having a hexagon socket and being placed onto the nut from the exterior via a gear wheel engaging via an opening in the cylinder or by turning the nut with a pin inserted through an opening in the cylinder.
These known hydraulic tensioning devices for threaded bolts have been proven successful in practice and can be designed for one-step or multi-step operation for applying forces required for achieving a predetermined stretching of the threaded bolts of any conventional size.
Such known hydraulic tensioning devices for threaded bolts, as known from German Gebrauchsmusterschrift 76 00 965.9, have a safety means against overloading of the threaded bolt which is comprised of a limiter ring for limiting the stroke of the piston such that the threaded bolt upon contacting of the piston at the limiter ring is not subjected to further pulling force increase so that breakage of the bolt due to overextension can be avoided.
However, in hydraulic tensioning devices for threaded bolts of this kind the threaded bushing is a greatly loaded part which after a certain number of elongations of the threaded bolt may break within the area of the threaded end of the bolt. Since in such a case the entire system is suddenly released, the broken-off part of the threaded bushing, together with the piston and the cylinder, can be thrown with considerable energy and can cause considerable damage to neighboring machine parts as well as injuries to the operator.
In the aforementioned known hydraulic tensioning device for threaded bolts a safety means against throwing of parts of the hydraulic tensioning devices for threaded bolts upon breaking of the threaded bushing is not provided.
In contrast, a hydraulic tensioning device for threaded bolts according to the German Patent 1 297 557 provides a means for protecting the surroundings of a hydraulic device which means is placed over one end of the screw, for example, the screw for a steam turbine housing or coupling, for stretching the screw in the axial direction. The means is comprised of a protective device in the form of a protective plate supported by securing supports and is positioned on the hydraulic device in the vicinity of the tensioning device for the threaded bolts and fastened thereto.
This protective device is a catch basket that engages over the hydraulic tensioning device for threaded bolts and is fastened to a threaded bolt adjacent to the threaded bolt to be stretched. This known protective device is thus very cumbersome in its manipulation and requires a considerable amount of space.
It is an object of the invention to improve a hydraulic tensioning device for threaded bolts of the aforementioned kind such that upon breaking of the threaded bushing a safe catching of the broken-off part as well as of entrained parts of the tensioning device of the threaded b
REFERENCES:
patent: 3722332 (1973-03-01), Jones
patent: 4020720 (1977-05-01), Fujii
patent: 4175453 (1979-11-01), Exner et al.
patent: 4438901 (1984-03-01), Reneau et al.
patent: 4708036 (1987-11-01), Vossbrinck
Hohmann Frank
Hohmann Jorg
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