Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Having separate expander means – Made up of plural expansible segments or sections
Patent
1981-07-20
1984-10-09
Holko, Thomas J.
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Having separate expander means
Made up of plural expansible segments or sections
411 44, 411 47, 411 61, 411 70, 411 78, 405259, F16B 1306
Patent
active
044758561
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an expansion screw of the adapted for being secured in a cavity and having a screw portion threaded at its outer end for co-action with a fastening element, e.g. in the form of a nut, and which is provided with an expandable sleeve having an outer cylindrical surface and an inner profile adapted to coact with the outer profile of the expansion screw for expanding the sleeve at withdrawal of the screw portion from the sleeve, the outer profile of the scew portion being formed by a plurality of co-axial cones with intermediate cylindrical junction portions, all the junction portions being made integral with the rest of the screw portion.
BACKGROUND ART
Expansion screws for insertion in holes in concrete or rock walls for retaining machine parts are well known, and are available in many different forms. Most often, an expansion screw has one, or only a few means for expanding an associated sleeve, but expansion screws with a plurality of expander cones are known, for example, from German Published Patent Application Nos. 2138246 and 1814485.
Such expansion screws with a plurality of expander cones are intended to distribute the pressure of the sleeve over a large portion of the hole wall so that the surface pressure will be kept to a low value. Among the known expansion screws, are those having a sleeve with a crennelated profile. However, such a sleeve has its profile flattened when the screw is loaded and the walls of the hole consist of a very hard material, whereby the screw can then be pulled out of the hole.
SUMMARY OF THE INVENTION
The expansion screw in accordance with the invention is characterized, inter alia, by the inner profile of the sleeve having thickened regions and attenuated regions. The sleeve thickness is adapted such that when it is expanded into contact with the wall of the hole, continued thightening of the screw portion expands a part of the sleeve's thickened portions into bulges going round the sleeve, these bulges penetrating into the wall of the hole and primarily contributing to retaining the expansion screw. With the expansion screw in accordance with the invention, the sleeve at its thickened regions can withstand very heavy pressure coming on the sleeve when the material in the hole walls is hard. Other forms of the expansion screw are also suitable when the walls of the hole consist of soft material with low strength.
BRIEF DESCRIPTION OF DRAWINGS
In the following, embodiments of expansion screws in accordance with the invention are described with reference to the appended drawing, wherein
FIG. 1 diagrammatically illustrates in section a complete expansion screw;
FIG. 2 illustrates development of a sleeve of the expansion screw;
FIG. 3 illustrates an expansion screw with different spacings between the thickened regions of the sleeve and the cones of the expansion screw;
FIG. 4 is an end view of the expansion screw as seen towards its innermost end;
FIG. 5 illustrates buckling in the attenuated portions of the sleeve;
FIG. 6 illustrates impressions in the thickened places of the sleeve;
FIG. 7 is a section taken along line B--B through the sleeve in FIG. 6; and
FIG. 8 illustrates an expansion bolt with an expanded sleeve.
BEST MODE FOR CARRYING OUT THE INVENTION
As is apparent from FIG. 1, the expansion screw includes a screw portion 1 having an outer end which is threaded in order to co-act with a fixing element. In the example shown, the screw portion is threaded externally for co-action with a nut 2, although it can be alternatively made with an axial hole threaded for co-action with a screw. The screw portion is provided with a plurality of cones, of which one cone 3, situated at the end opposite the threaded end, is directed with its minor end towards the threaded portion of the screw and is terminated at its outermost end by a short cylindrical portion. Three remaining cones 4, 5, 6, are double cones with the bases facing each other. Both cones in a double cone have approximately the same vertex angle, but can
REFERENCES:
patent: 1033447 (1912-07-01), Mower
patent: 1650958 (1927-11-01), Ogden et al.
patent: 2180030 (1939-11-01), Bugatti
Holko Thomas J.
Telefonaktiebolaget L M Ericsson
Wilson Neill
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