FR2601407A1 - Large enclosures under vacuum - Google Patents

Abstract

The invention relates to a method for constructing large enclosures under vacuum. It uses an external reinforced concrete structure 1 providing the overall stiffness, a thin metal structure 2 providing the leaktightness of the walls, the pressure forces on the wall 2 are transmitted to the reinforced concrete structure by means of hangers 3 welded to the skin 2 and sealed in the concrete 1. A space 9 allows the circulation of a hot air current. The method according to the invention is intended for the construction of enclosures under vacuum.

Description

 The present invention relates to a method of constructing large volume vacuum chambers.

 Vacuum chambers are generally used to carry out special metallurgical interventions of high technicality, mainly by electronic bombardment process (welding, fusion, evaporation, etc.).

 The elements to be treated are introduced at atmospheric pressure into the enclosure, put in place, then the opening is closed by a sealed door, and a vacuum is created inside the enclosure. The atmospheric pressure is then exerted over the entire surface of the enclosure, and reaches, for large enclosures, very high stress values.

 The enclosures are produced, in the traditional way, using metal structures comprising more or less reinforcements or ribs, ensuring both tightness and rigidity. These traditional structures are economical and easy to manufacture for small or medium dimensions (up to approximately 3 or 4 m. Of side or diameter), but become very complex and reach prohibitive costs for large dimensions.

 The method according to the invention makes it simple, and economically affordable, to manufacture large and very large vacuum chambers.

 In the method according to the invention, the structure ensuring the rigidity of the assembly is dissociated from the structure ensuring its tightness. Indeed, the structure ensuring the rigidity of the assembly is a reinforced concrete structure positioned in the external part of the enclosure. The structure ensuring the sealing of the walls is a thin metallic structure forming skin, to which are fixed by welding, or any other process, multiple external lines coming to be embedded in the reinforced concrete structure. When the enclosure is evacuated, these lines act as tie rods, which transmit the pressure forces on the skin to the reinforced concrete structure.

 The single plate represents, in section, a vacuum enclosure according to the invention.

 In one embodiment, the method according to the invention is used to construct a vacuum enclosure of circular section for a machine for welding by electronic bombardment.

The structure ensuring the rigidity of the assembly is a reinforced concrete structure (1) of circular section in its internal face. The sealing structure is a steel skin (2), also of circular section. Lines (3) are welded to the skin (2) and ensure the transmission of forces, due to the pressure on the skin, to the reinforced concrete structure (1); these lines are sealed when poured into the concrete of the structure. In this embodiment, a lost formwork (1O) is provided, of circular section, providing a space (9) between the concrete and the steel, in which can pass a hot air flow. The construction procedure will be established, in this embodiment, as follows:
-Manufacture and installation of the metallic skin kept in shape by a stiffening system -internal supply ("internal shoring").

 -Positioning of the lost formwork (10) allowing the lines (3) to pass.

 - Pouring, in successive beds, of concrete, - between an external formwork (11) and the internal formwork (10), after having put in place the reinforcements.

 - Formwork of the external formwork (ll).

 -Installation of external insulation (12).

 -Disassembly of the interior shoring.

 Pumping groups (4) reservations for additional groups (8), gun holder gantry (6) barrels with electric; sections (5), parts transfer carriage (7) are the classic components of the machine.

In one embodiment of the internal shoring, this will be carried out as follows:
Circular shoring sections are defined spaced so that the skin is self-supporting between these sections during the pouring of the concrete. Metal spokes (13) are welded to the internal face of the skin according to these shoring sections, these spokes maintain the circular shape of the section; when the concrete has set, we cut out the spokes (13), we deburr the interior surface of the
skin (2), and the rays are removed.

The method according to the invention is intended for construction
vacuum chambers.

Claims (3)

1) A method of constructing large volume vacuum chambers characterized in that the structure ensuring the rigidity of the assembly is an external structure of reinforced concrete and that the structure ensuring the sealing of the walls is a thin metallic skin with l 'outside of which are fixed multiple lines ensuring the transmission of pressure forces on the wall, to the reinforced concrete structure. 2) Method according to claim 1 characterized in that there is a space between the reinforced concrete structure and the metal skin, in which one can pass a flow of hot air. 3) Method according to claim 1 characterized in that maintaining the shape of the metal skin before pouring the concrete is carried out by means of metal spokes which are welded to the internal face of the skin in circular sections, and which are removed after setting concrete.