US2147552A - Metallic construction - Google Patents

Description

Feb. 14, 1939. L. SAIVES 27,147,552

METALLIC CONSTRUCTION Filed Aug. 30, 1937 a more substantial manner to the.

IMETALLIG CONSTRUCTION Leon Solves, Blllancourt, France, asslgnor to Louis Renault,

Billancourt, France Application August 30, 1937, Serial No. 161,692 In France October 7, 1936 l llllu ".lhe present invention relates to improvements in metallic constructions, which are charactericed hy the use of very thin which are preliminarily subjected to tension and thus provide for the construction oi assembled devices which are perfectly rigid, while at the time very light.

The said improvements have chiefly for their object the construction of metallic hollow oodles, in the form of prisms, cones, or tylinders, and the assembling of the same, these heme adapted tor use as iimelages or wines for aircraft, car riage-worlr for vehicles, etc, and theconstruction thus obtained will give the muniinum vo1- uine available inthe interior of the hodyand will permit the. operation of the whole of the outer metallic covering.

in conformity with the invention, the hollow structure consists essentially of transverse members termed frames, to which the sheet metal covering is secured by welding or riveting. The said frames and covering are constructed in a manner resembling a "hull" construction in which the covering acts as a resistant element and is subjected to tension. l'he diflerence consists in the nature and the function oi the loneitudinal members or hare. In the lrnown hull construction, the bars are secured to the frames and to the coverings, and they provide for the rigidity of the latter, but in my present construction, the said bars oass loosely through all or the intermediate frames, and are secured to the end frames, but they are not secured to the covering.

its the rigidity thecovcrlnu is no longer insured by the stihenine grating termed hy the frames and the bars, this rigidity is obtained in the following manner.

The covering is secured to the trainee, and in end frames, end the whole set or bars is out in place through all of the intermediate frames, being then secured at one end'to one of the frames situated at the end. Then, by means of the end frames, the covering is subjectedto a longitudinal tension which is distributed upon the periphery. This longitudinal tension, which is produced by means of a suitable outfit, may be uniformly distributed on the periphery of the.covering or may be distributed in a variable Hpanner. The rate of variation of this longitudinal tension will depend upon the subsequent stresses to which the covering is subjected. The tension is observed by measuring the difierences in the distances of the checking holes which are properly drilled in the sheet metal pieces,

. taking due account oi the (@l. Mil-3d) sheet metal oi the coveiiny heroic the ussernhlinu operation.

When the entire covering lids heen eluted insder tension, and when the measurements oi the tensions have heen made, the have are secured at their ends which were lett this may be effected either permanently by welding or riveting, or removahly, by the use oi mechanical assemhling means. en this latter method oi us semhlinc, the apparatus can be when court at a later date, tor repairs, or lot eeain placing the covering under tension.

When the seem-inc operation isilnuhed. the tension exercised by the tool outfit is removed, and owing to the compression oi the rods and to their consequent shortening, the tension of the covering is reduced, this depending upon the ratios between the cross sections of the bars and the corresponding sections of the covering. During the preliminary study, it is possible to calculate the tensions which should be exercised by the tool outfit in order to obtaiuafter the assembling, the definite tensions desired.

The thickness oi the covering will depend upon the stresses to which it is subjected in service, coemclentoi safety. The tension. during the construction should be such that it will not be annulled by the compression in any cuse. For the parts suh ected to traction, the suns oi the two traction eiiects should he less then the stress allowed.

litter the description oi the method, it will easy to understood application cl this method.

The covering oi the hollow should con slot of a metal having most approved llltldhhlllcal features, such as restless niclrehchrorne steel, cold rolled, and the metal may have u very reduced thictzness, which however must he coon loatible with the strength. it study oi thchull construction has shown that this thickness may be very small, owing. to the distribution ol the material at the periphery.

For the better understanding of the invention, it is particularly described with reference to the accompanying drawing.

--Fig. 1 is a lengthwise view of this construction.

Fig. 2 is a corresponding end view.

Figs. 3 and 4 are explanatory views.

As shown in Fig. 1, the hollow structure which is obtained, consists essentially of transverse members I, in suitable number, to which the covering 2 is secured by welding or riveting.

The transverse members I are maintained by or a hollow body iii Eli

longitudinal members or bars 3, which are so cured to the end pieces i and i", Figs. 3 and 4.

As the rigidity of the covering is no longer insured by the stiffening grating consisting of the crow-frames i and the bars 3. -I proceed in the following manner. The covering 2 being fixed to the frames I, and more securely to the end frames l and I, the bars 3 are inserted through the frames 1, and are secured at one end to one of the end frames, for instance to the lrame P. Then, through the medium of the frame at the other end I, and by the use of a suitable outfit, the covering 2 is subjected to a longitudinal tension t (Fig. 4) which is distributed uniformly or variably upon the whole periphery.

Checking holes 4 which are drilled before the assembling, in the sheet metal or the covering 2, provided for the observation of the tension which is applied, by measuring the distance between them.

After measuring the tensions thus produced, the free ends of the bars 3 are secured to the end frame I (Fig. 3), eitherdefinitely, by welding or riveting, or removably, by mechanical means for assembling.

This construction is more simple than the "hull" construction which is now in use, owing to the fact that the bars are not secured to the covering, and that this latter does not require to be stiflened.

On the other hand, the designing and the utilization of this construction are facilitated by the fact that it is always possible to verify the tensions by means oi suitable checidng holes pro vided in the covering.

The alternate stresses due to vibrations or to other causes, do not produce changes oi sign of the action in the units which make up the constmction, as the stresses have always the same direction. Hence this property provides for a better preservation of the metal.

On the other hand, this construction permits the used steel of great strength, and by its possibility of welding, it affords, in the aeronautic industry, better cost prices than the known constructions.

Obviously, the longitudinal tension may be completed by transverse tensions which are obtained either by a forced fitting of the frames, or by producing the tension-oi the sheet metal icy suitaisle tools.

"L claim:

A hollow metal hody comprising a very thin sheet metal plate which is subjected to tension in the longitudinal direction, substantially annular transverse units secured to said thin plate and. having openings therein, longitudinal bars passing freely through said openings in the intermediate transverse members and placed in compression and secured only to the transverse members situated at the ends of the plate and said bars being arenged at the periphery of the transverse members so as to leave a free space at the center of the hollow body.

LEON SW.

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