Abstract A bell furnace for annealing treatment of metal sheets in superimposed rolls has a first outer hood, a second inner hood for protection of the sheet rolls, a cylindrical annular space between the first outer hood and the second inner hood and an upper collecting chamber and a lower collecting chamber within the inner hood. There is disposed a plurality of vertical tubes circumferentially arranged about the sheet rolls externally of the second hood for the passage in ascending stage of the entire protective gas capacity from the lower collecting chamber to the upper collecting chamber; a diffuser is located within the lower collecting chamber and beneath the central bore of the sheet rolls for establishing a fluid circulation within the inner hood and the tubes arranged in the space between the inner and outer hoods.
A furnace according to claim 1, wherein said lower collecting chamber comprises a lower plate on which said inner hood and diffuser bear, and an upper annular disc, the peripheral wall of the annular collecting chamber downward extending to penetrate into a cohesive layer, such as sand, ensuring a tight sealing.
Claim 2
Dependent Claim
17 words
A furnace according to claim 1, wherein each tube comprises an expansion joint disposed within said space.
Claim 3
Dependent Claim
33 words
A furnace according to claim 1, wherein an expansion joint is disposed within said space and mounted for communication between one end of each tube and the wall of said second inner hood.
Claim 4
Dependent Claim
42 words
A furnace according to claim 1, wherein said outer hood is removably mounted for cooling and is made of sheet as said inner hood and at the top thereof a fan is carried for generating an air circulation externally of said tubes.
Claim 5
Dependent Claim
18 words
A furnace according to claim 1, wherein said outer hood is removably mounted and constitutes a heating hood.