Measuring and testing – Dynamometers – Responsive to torque
Patent
1994-06-13
1996-08-20
Chilcot, Richard
Measuring and testing
Dynamometers
Responsive to torque
73847, 81478, B25B 23142
Patent
active
055468160
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Tools for the controlled tightening of bolts and other threaded objects are often provided with an indication of when the turning moment has reached a predetermined value and include a spring whose force can be adjusted to a value corresponding to the intended indication moment, for instance by displacement of one of the ends of the spring when rotating the grip of the tool. Thereafter, the tool can be used to tighten several bolts with the same turning moment.
For applications with particularly rigid safety regulations, for instance in aircraft industry, chemical or nuclear industry, there is a necessity to be able to adjust the spring force and the indication moment with a higher precision than what is normally possible with usual tools and to lock the tightening device of the spring so that the preset moment cannot change during work. The present invention relates to a tightening device for this purpose.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the tightening according to the present invention will now be described with reference to FIGS. 1 to 3.
FIG. 1 is an exterior view of a grip with a tightening device and the scales which are used when adjusting the indication moment.
FIG. 2 is a cross-section taken through the grip and the tightening device.
FIG. 3 is an exploded view of the four unities separately.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The lower part of the tool is not shown in the figures and comprises an indication arrangement of known type, for instance as described in U.S. Pat. No. 5,123,289 the subject matter of which is incorporated herein by reference. According to this patent, an indication arrangement gives an optical, acoustic, tactile or electrical indication when the turning moment reaches a certain predetermined indication moment. Further, at its fore end said lower part of said tool comprises a moment transferring part of known type, for instance an axle for coupling different sleeves which can hold different bolts and other threaded objects.
The spring 21 is situated in the shaft 24 of the tool. The force in the spring 21 actuates the indication arrangement not shown in the figures, and thus it determines the indication moment. The force in the spring 21 can be varied by rotation of a grip 11 which also serves the purpose of taking up the forces from the hand when using the tool. The dimensions of the spring 21 have been chosen so that the total rotation angle of the grip 11 becomes a measure of the indication moment. In order to attain sufficient precision at the adjustment, the total rotation angle has to amount to several revolutions, wherefore the reading of the rotation angle is made on two scales, a total scale 31 on the shaft 24 of the tool, and a fine scale 32 around the grip 11. In order to achieve the best precision and a safe reading of the total scale 31, it is read off relative to a movable index 33 whose displacement along the shaft 24 at rotation of the grip 11 is considerably larger than the compression of the spring 21.
In order to avoid any undesired changes of the predetermined indication moment, the rotation of the grip 11 in relation to the shaft 24 can be locked with a detachable handle 10 at the rear of the grip 11.
The compression of the spring 21 which is intended to create the predetermined force, is brought about by a screw 13 connected to the grip 11, which screw is threaded into a threaded bushing 23 connected to the shaft 24. The front end of this screw presses against a slidable abutment piece 22 within the shaft 24. The spring 21 rests against said abutment piece 22. The thread of the screw 13 and the bushing 23 has a small pitch, so that for every revolution of the grip 11 the displacement of the abutment piece 22 and the force increase in the spring become small. This makes it possible to adjust the force with high precision. The rear end of the screw 13 is connected with the grip 11 by a threaded tube 14. The longitudinal position of the screw 13 can be adjusted by turning it in relation to
REFERENCES:
patent: 2607219 (1952-08-01), Millard et al.
patent: 2732747 (1956-01-01), Livermont
patent: 2887921 (1959-05-01), Livermont
patent: 3140623 (1964-07-01), Van Hoose
patent: 3165014 (1965-01-01), Grabovac
patent: 3270594 (1966-09-01), Grabovac
patent: 3276296 (1966-10-01), Woods
patent: 3577815 (1971-05-01), Bergquist
patent: 3666021 (1972-05-01), Whitehouse
patent: 3772942 (1973-11-01), Grabovac
patent: 3893354 (1975-07-01), Knoll
patent: 4248107 (1981-02-01), Blattner
patent: 4467678 (1984-08-01), Lindholm
patent: 4485703 (1984-12-01), Grabovac et al.
patent: 4655104 (1987-04-01), Blattner
patent: 4709602 (1987-12-01), Grabovac et al.
patent: 4870879 (1989-10-01), Shieh
patent: 5048381 (1991-09-01), Allen et al.
patent: 5123289 (1992-06-01), Potesta
patent: 5129293 (1992-07-01), Larson et al.
patent: 5239875 (1993-08-01), Stasiek et al.
patent: 5435190 (1995-07-01), Jansson et al.
Bergqvist Hakan
Himbert Hans
Jansson Conny
Chilcot Richard
McCall Eric S.
Sandvick AB
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