Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Headed fastener element – Having plastically flowable or deflectable end – e.g. – rivet,...
Patent
1991-01-22
1992-01-21
Wilson, Neill R.
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Headed fastener element
Having plastically flowable or deflectable end, e.g., rivet,...
411507, 295241, 295252, F16B 1906, B21D 3900
Patent
active
050824112
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a fastening means, in particular a rivet, for the assembly of materials, more specifically sheet metal in the aeronautic field It extends to the process for installing the fastening means and to the assemblies obtained. The invention seeks to improve the distribution of compression forces between the securing means and the assembled materials.
BACKGROUND AND OBJECTS OF THE INVENTION
In the aeronautical field, assemblies are required to undergo great stress and it is known that their stress-bearing capacity is directly linked to the distribution of compressive forces which are introduced at the time of installation, between the fastener means and the materials being assembled. The most critical zones are found at the level of the preformed head of the securing means and at the junction between the shank and the head The poorly-solved problem at the present time is that of obtaining, simultaneously, on the one hand a sufficient radial enlargement of the head to guarantee a good tightness between the head and the assembled materials, and on the other hand, a deformation and adequate expansion of the head toward the head/shank junction zone as well as in the shank in order to attain in these zones a higher level of compression restraints, thus assuring a satisfactory stress-bearing capacity.
In attempting to resolve this problem the head of the rivet has been provided with particular shapes, this head being flattened at the time of setting, for producing a flow of the material toward the sheets to be assembled; the adopted solutions heretofore have consisted of adding in projection on the frontal face of the head of the rivet protuberances or bulged parts which are then flattened at the time of placement and produce a greater flow than a flat head. Nevertheless, the shapes provided have a tendency to favor either the radial enlargement of the head to the detriment of the expansion at the level of the head/shank junction and of the shank, or in the reverse, the flow toward the shank to the detriment of the expansion of the head.
Thus certain fastener means are provided with a head having a bulged frontal surface (series of Dassault Standards 3.507.2 and 3.507.3 of 1968; 3.502.1 of 1966; FIAT Standards Norms 12830 of Feb. 5, 1971 intended for the MRCA aircraft; U.S. Pat. Nos. 4,000,680, 3,927,458, 3,747,467, 3,748,948) and the flattening of this bulged head increases the flow toward the shank, improving the compression forces therein; however, with the normal flattening forces, this surplus of material in the central portion of the head tends to reduce the radial enlargement of said head and to bring about a poor tightness between the head and the sheets. Other securing members include a head on which the surplus of material is provided on the periphery of the frontal surface of the head, in particular in the form of an annular projecting dome on this frontal surface (U.S. Pat. No. 4,051,592). During setting, this peripheral projection favors the radial enlargement of the head, bringing about a good tightness of the head in the sheets, however it is to the detriment of the flow toward the shank where the compression constraints remain weak, with the risk of rupture in the case of alternated constraints.
DESCRIPTION OF THE INVENTION
The present invention seeks to provide a satisfactory solution to the problem posed, by providing an improved fastening means adapted to improve the distribution of compressive forces between the fastening means and the assembled materials.
For this purpose, the fastening member provided by this invention is of the type including an axial shank intended to be placed in a hole in the materials to be assembled, and a head situated at one extremity of said shank and intended to be deformed by crushing during setting; according to the present invention, this member is characterized by the fact that its head has a frontal surface on which is provided a ring-shaped groove extending about the axis, said annular groove being essentially positioned on said front
REFERENCES:
patent: 4051592 (1977-10-01), Briles
patent: 4086839 (1978-05-01), Briles
patent: 4159666 (1979-07-01), Briles
patent: 4695213 (1987-09-01), Sparling et al.
Auriol Jean-Marc
Bornes Philippe
Dutton, Jr. Harold H.
Ste. Ateliers de la Haute Garronne Ets Auriol Cie
Wilson Neill R.
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