US2913798A - Manufacture of hollow rounded ele-ments of prestressed concrete - Google Patents

Description

Nov. 24,1959 I L. BREGUET 2,913,798

MANUFACTURE OF HOLLOW ROUNDED ELEMENTS 0F PRESTRESSED CONCRETE Filed Des 8 1953 4 Sheets-Sheet 1 Nov. 24, 1959 L'. BREGUET MANUFACTURE OF HOLLOW ROUNDED ELEMENTS OF PRESTRESSED CONCRETE Filed Dec. 8. 195a 4 Sheets-Sheet 2 Nov. 24, 1959 L. BREGUET 2,913,798

MANUFACTURE OF HOLLOW ROUNDED ELEMENTS OF PRESTRESSED CONCRETE 4 Sheets-Sheet 3 Filed Dec. 8, 1953 L. BREGUET $913,798

Nov. 24, 1959 MANUFACTURE OF HOLLOW ROUNDED ELEMENTS 0F PRESTRESSED CONCRETE Filed Dec. 8, 1953 4 Sheets-Sheet 4 r 1 v ltwllnu.lhlillmlllh1. h

United States Patent The present invention relates to an improvement in the manufacture of hollow rounded'clements of prestressed concrete, more particularly with a view to .the application of pre-stressed concrete to themanufacture of aircraft parts, such as hulls'and fuselages.

According to the invention, in order toenable the reinforcements tensioned beforethe casting 'ofthe concrete,

to follow the rounded profile of the elementto' be manufactured, two systems of reinforcements are provided, to one of which (called the main'system in the present specification) the pre-stressing'tension is directly applied, while the other (called the secondary system) is intended to provide for the first system points of support judiciously distributed in the element to be manufactured.

The reinforcements of the secondary system remain supported from the outside until theconcrete hasattained suflicient hardness. T hey'are aa'ttsilaiican placedunder tension when the main system receives the p're-stressing tension, the value of their tensionbeing greater in proportion as the rounding of' the'prdfile ofthe elements is more pronounced. v A

In an element of elongated"form,-fsuch as a hull or fuselage of an aircraft, the mainreinfo'rcements are disposed longitudinally and'the secondary reinforcements form transverse supportingframes for the reinforcements of the main system.

The invention further concerns an apparatus for the manufacture of elements of the aforesaid type, as also the said elements themselves.

The invention is illustrated by way of example in the accompanying drawings in which:

Figure 1 is a fragmentary longitudinal section through an aircraft hull;

Figure 2 is a section on the line 'II-II of Figure 1;

Figures 3 and 4 are diagrammatic views, taken in the plane V--V of Figure 1, showing the arrangement of the main and secondary reinforcements before and after the tensioning thereof;

FigureS is a section on the line VV of Figure 1;

Figure 6 is a fragmentary view of a detail similar to Figure 5, on a larger scale;

Figure 7 is a section on the line VII-VII of Figure 6;

Figure 8 is a section on the line VIlI--VIII of Figure 6;

Figure 9 is an elevational view, partly in section, of the core employed for the casting of the elements;

Figure 9a is a section on the line IXa-IXa of Figure 9;

Figure 10 is an elevational view, partly in section, of the mould corresponding to the core;

Figure 10a is a section on the line Xa-Xa of Figure 10;

Figure 11 is a sectional view of the core, showing a device for the removal of the supports of the secondary reinforcements, and

Figure 11a is a section on the line XIa-Xla of Figure 11.

In the embodiment illustrated in Figures 1 and 2, a

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hollow rounded element such as an aircraft element, for example a hull or fuselage of an aircraft compri'ses a wall 1 of concrete (or similar material) providedon the one hand with main longitudinal reinforcements-L'which in the present example are disposed regularlyalong the periphery of the hull; and on the-other hand with secondary reinforcements 3, which are here-disposed intransverse ribs 4 on the hull and form supporting frames for the main reinforcements.

In order to construct a hollow body of this-type, the main and secondary reinforcements of which areboth pre-stressed, the following proc'edure may' be followed (Figures 3 to 8):

A row of projections or pins'6 are radially distributed along the periphery of-the core 5 at-theposition to be occupied by each rib 4. The pins-Gare formedwith notches 7 (Figure 6) in their-ends to receive the secondary reinforcements 3, which are disposed around the core 5 and attached at theirends. At theintervals of the pins 6, the main reinforcements-2 (Figure 3) are disposed on the secondary reinforcements 3.

The main reinforcements 2*a're thereafter tensioned. Owing to the roundedform of thehollow-element to be produced, there are set up at the-points of contact of the main and secondary reinforcements, radially directed reactions which produce a deformation as well as a tensioning of the' secondaryreinforcements, the latter supporting at the same time the reinforcements of the main system. I

The core thus reinforced is covered'by an outer mould 5a (Figure 4) and the casting of the concrete is then effected. I I

At the time of the stripping of the mould, the pins 6 are extracted, whereby a series 'ofsmall holes 8 (Figure 5) is left in the rib 4.

Figures 6, 7 and 8 show on a larger scale a hull section manufactured in the manner hereinbefore described.

Figures 9, 9a, 10, 10a, 11 and 11a show how the core, the mould and the various accessories thereof may be designed in order to construct an aircraft fuselage section of circular cross-section.

The hub (Figures 9 and 9a) comprises a central core of body 10 (consisting, for example, of cast iron or of assembled tubes or metal sections), on which are mounted rings 11, formed in one or more parts, which guide the pins 6. The latter also extend through the body 10 in which they are maintained by a suitable securing device, for example that hereinafter described with reference to Figure 11.

Rubber air chambers 12 provided with valves 12a are disposed between the rings 11, and sectors 13 (produced, for example, on a lathe and then divided into sections) are placed on the chambers 12.

The core 10 also has, on its lower part, a cover 14 which can he slid with the aid of jacks 15 bearing on the one hand on the end 14a of this cover and on the other hand on a flange 10a on the core.

The cover 14 is provided with a flange 16 permitting of attaching the main reinforcements 2, a corresponding ring 17 on the core serving as a guide for the said reinforcements. The latter are attached at their other end to another ring 18 intended to form an integral part of the hull and supported by a ring 19 on the core 10. i

The core 10 comprises in addition an eye 20 to permit transport thereof.

When the reinforcements 2 and 3 have been positioned of the reinforcements take place on the corefindependently of the mould, which permits of production in series and simultaneous preparation of any desired number of cores.

When prepared, the core can be transported, for example by means of a crane, towards the mould (Figures and 10a).

This last mentioned mould consists of two half- shells 21 and 22 articulated together at 23 and 24 and adapted to fit on to rings 17 and 18 on the core by means of appropriate bearing surfaces 25 and 26.

" In the present example the shells 21 and 22 are internally lined with contiguous longitudinal bars 27 bearing on peripheral ribs 28.

The mould and the core together are resiliently suspended at 29.. When the core has been positioned, the filling is effected, for example through the top as indicated by the arrows f, and the concrete is vibrated with the aid of an apparatus (not shown) attached at 14b to the cover 14 of the core. After filling, air under pressure is passed into the chambers 12 through pipes connected at 12a (Figure 9a).

When the concrete has set, the mould is opened and the core bearing the hull or other manufactured element is removed.

Figures 11 and 11a illustrate an example of a device for maintaining the pins 6 in position and extracting them from the hull in order to enable the core to be removed therefrom.

The body 10 of the core contains a tube 30 of large diameter which serves as a support for bell crank levers 31, of which one end 31a, which is fork-shaped, engages in a groove 6a in the corresponding pin, while the other end 31b is disposed in a groove 32a in a central push rod 32, which is adapted to be longitudinally locked by means not shown. The said push rod is guided at one end in an upper web 10b of the body 10 and in a hole 140 in the cover 14, while it terminates at its lower end in a head 32b.

In order to extract the pins 6 when the main reinforcements 2 have been severed between the flange 16 and the ring 17, and the push member released, it is suflicient to, actuate the jacks in order to force the cover 14 in the direction of the arrow. This cover then carries the push rod 32 with it, whereby the pins 6 are extracted.

From this instant, it is possible to remove the core from the hull. The central body 10, the air chambers 12, and the rings 11 are first removed, some of the said rings having been formed in a number of parts for this purpose, whereafter the sectors 13 are removed.

The manufactured hull comprises a number of circular ribs carrying the secondary reinforcements, and longitudinal ribs, due to the spaces existing between the sectors 13. Consequently, an internal reinforcing system having 4 rectangular projections is produced, which stifiens the wall of the hull.

What I claim is:

1. Apparatus for manufacturing hollow tubular elements of pre-stressed concrete having an arcuate shape both longitudinally and transversely and containing longitudinal reinforcements and transverse reinforcements, comprising in combination a mould, a core in said mould, the said core being provided with a plurality of series of circumferentially spaced radial holes in different transverse sections of said core, radial members slidably mounted in the said holes and adapted to support the said transverse reinforcements, a push-rod slidably mounted longitudinally in the said core and bell-crank levers pivoted on said core and engaging said push-rod and said radial members respectively, for displacing said radial members, means for supporting said longitudinal reinforcements between said core and mould in regular distribution along the periphery of said core, and means for tensioning the said transverse reinforcements by a tensioning of the longitudinal reinforcements.

2. The combination of claim 1 wherein the said means for tensioning the longitudinal reinforcements comprise a cover slidably mounted at one end of said core and adapted to support the corresponding ends of the said longitudinal reinforcements, and jacks mounted between said cover and core whereby said cover may be displaced axially relatively to said core. 1

3. The combination of claim 2 wherein said push-rod is extended through said cover and provided with a head outside of said cover, said cover being adapted to act on the said head for displacing the said push-rod.

References Cited in the file of this patent UNITED STATES PATENTS 1,103,270 Cronholm July 14, 1914 1,431,565 Buente Oct. 10, 1922 1,485,142 Mitchell Feb. 26, 1924 1,499,762 Conradi July 1, 1924 1,624,191 Venzie Apr. 12, 1927 1,843,853 -Underwood Feb. 2, 1932 2,001,237 Bille May 14, 1935 2,048,253 Freyssinet July 21, 1936 2,165,671 Ward July 11, 1939 2,170,188 Cobi Aug. 22, 1939 2,196,874 Ruegg Apr. 9, 1940 2,353,492 OConnor July 11, 1940 2,378,584 Schorer June 19, 1945 FOREIGN PATENTS 468,550 Germany Nov. 15, 1928 955,533 France June 27, 1949 71,548 Netherlands Jan. 15, 1953

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