Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Torque responsive nut or bolt driving connection – Resilient connection
Patent
1997-03-10
1998-08-18
Saether, Flemming
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Torque responsive nut or bolt driving connection
Resilient connection
411 1, 411403, 411396, F16B 3100, F16B 2300
Patent
active
057951160
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a rotatable device with a dynamometric arrangement, primarily against overtightening of threaded appliances like bolts, screws, etc.
Screw and bolt connections very often have to be tightened with a predetermined torque, so that they can fulfil predetermined practical requirements. Expensive and sensitive special tools have hitherto been necessary to apply a specific torque. If no such tools are used, there is a considerable risk of over-tightening the bolt or screw, and even to cause a rupture.
In relation with different types of adjustment screws, bolts and dials, a continued turning of the treaded part can be very detrimental, e.g., when an end value has already been reached, or when, the threaded part, or a part directly conected thereto, has been fastened in some way and this fact is overlooked by the operator, who tries to turn it around despite of its being fastened. A specific example of this is the radial fine adjustment of tool bit holders at the precision finishing of bores with rotary tools. On these tools, the tool bit holder is eccentrically displaced from the rotation axis by a radially sliding member which is adjusted by a scale or micrometer screw with a threaded shaft. When the preset radius has been attained, the sliding member is fixed with a fastening screw. After a finished boring operation, the, operator may overlook to loosen the fastening screw before turning the scale or micrometer screw, thus damaging the latter.
Thus, a first object of the present invention is to rotate rotatable appliances without exceeding a predetermined torque.
A further object of the present invention is to protect rotatable appliances against attempts to rotate when said appliance has been fixedly locked.
BRIEF DESCRIPTION OF THE DRAWINGS
For illustrative but non-limiting purposes, the invention will now be further described in relation with the appended drawings, wherein:
FIG. 1 shows a perspective view of a bolt comprising a protective arrangement according to the present invention;
FIG. 2 is the same bolt as in FIG. 1, with the protective arrangement taken apart.
FIG. 3 shows in perspective a sleeve clip according to the present invention;
FIG. 4 shows another embodiment of a clip according to the present invention;
FIG. 5 is still another embodiment of a clip according to the present invention;
FIG. 6 is still another embodiment of a clip according to the present invention; and
FIG. 7 shows a radial cross-section of a balanced boring head illustrating an application of the arrangement according to the present invention.,
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1 and 2 show a bolt 1 with a lead 2. A cylindrical bore 3 is provided on the top surface of head 2. Bore 3 is concentric with the axial extension of bolt 1. A clip 4 of basic cylindrical shape is fitted into bore 3. Clip 4 according to FIG. 1 and 2 has a socket 5 of hexagonal cross-section. Socket 5 and the outer envelope surface of the clip are connected via a slot 6. The slot can be made either along one of the corners of the hexagon (FIG. 2) or in the middle of one of the sides of the hexagon, thus splitting the side into two parts (FIG. 3). A suitable key of hexagonal cross-section can be inserted into the socket 5 in order to rotate the bolt.
When clip 4 is in bore 3, it must press firmly against the cylindrical wall of the bore. In order to achieve this, the clip music be pressed together by approaching the two flat, congruent surfaces facing slot 6. Suitably, the clip is pressed together by pliers and then it is inserted into bore 3, whereafter it is let free to expand and press against the bore wall. The clip is made of a suitable spring steel so that the friction joint in the bore becomes sufficiently strong by the inherent spring effect of the steel. By this friction, a predetermined maximum torque or torque range is transferred from the clip to the bore wall. A suitable steel for the clip should preferrably have a spring steel hardness of 43 to 50 Rockw
REFERENCES:
patent: 2931265 (1960-04-01), De Lacy
patent: 3073206 (1963-01-01), Rudolph
patent: 3405595 (1968-10-01), Peterson
patent: 4658558 (1987-04-01), Verble
patent: 4687392 (1987-08-01), Bidwell
patent: 5154557 (1992-10-01), Houck
patent: 5584626 (1996-12-01), Assmundson
Aspeby Magnus
Frank Peter
Kraft Klaus
Nitz Erwin
Saether Flemming
Sandvik AB
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