Molten metal bath, particularly a molten tin bath, of a production line for producing flat glass, and method for limiting the differential expansion between the crown and the vat

A metal bath, in particular a tin bath, of a production line for producing float glass comprising a chamber formed of three main constituents, a bath tank (5), wherein liquid metal, in particular liquid tin (10), is found, a roof (6) overhanging it, and side-sealing casings (7), creating the join between the two preceding components, the bath tank (5) comprising a metal casing (8) packed with refractory material (9) , that may be moved on a frame (21) along the axis of the process, with the exception of fixed supports (23) referred to as “fixed points”, formed by a zone for rigidly connecting the casing to the frame (21), wherein the roof (6) rests on sliding or rolling supports (24) that guide and direct the thermal expansions of the whole of the roof along the axis of the process, and comprises a “fixed point” (26) in the vicinity of the perpendicular to the “fixed point” (23) of the tank (5).

A process that makes it possible to limit the differential expansions between a tank (5) and a roof (6) of a metal bath, in particular tin bath, of a production line for producing float glass, side-sealing casings (7) creating the join between the two preceding components, the bath tank (5) consisting of a metal casing (8) packed with refractory material (9), that may be moved on a frame (21) along the axis of the process, with the exception of fixed supports (23) referred to as “fixed points”, formed by a zone for rigidly connecting the casing (8) to the frame (21), the roof (6) resting on sliding or rolling supports (24) that guide and direct the thermal expansions of the whole of the crown along the axis of the process, and comprising a “fixed point” (26) in the vicinity of the perpendicular to the “fixed point” (23) of the tank (5), wherein the process comprises monitoring the longitudinal differential expansion between the roof (6) and the tank (5) by a continuous measurement thereof, and adjusting the cooling of the tank so as to keep the longitudinal differential expansion within defined limits, so as to prevent the degradation of sealing joints (19) between the tank (5) and the roof (6) that may give rise to gas leaks between the atmosphere of the bath and the outside of the tank.