(1) Field of the Invention
The present invention relates to a roller assembly for a roller furnace for heat treating slabs of steel, etc. The roller assembly has a number of spaced carrier rings for carrying the slabs and thermal insulation between the carrier rings. The slabs are transported through the roller furnace by the roller assemblies on the carrier rings for heat treatment thereof. The hollow cavity of the roller assembly is usually water cooled. The thermal insulation is for protecting the roller assembly from the hot slab, as well as preventing the hot slab from cooling due to the presence of the roller assembly.
(2) State of the Prior Art
DE 32 31 736 C2 discloses a sheathing for insulating a cooled slide, skid or transverse pipe in a furnace. Moldings for the bottom side of the pipe made of a ceramic fiber material and moldings for the upper side of the pipe made of a refractory ceramic are provided for adapting the bottom and upper sides for the different stresses the sides will undergo. This type of an arrangement is unsuitable for a rotating roller assembly. Preformed insulating moldings result in joints in the thermal insulation of the roller assembly. Such joints have a negative impact on the insulating effect of the thermal insulation.
Moldings for insulating pipes are also described in DE 31 25 440 A1 and in DE 36 09 047 A1. The types of moldings described in these disclosures are unsuitable for roller assemblies, since the moldings have very little ability to withstand the dynamic stresses of a rotating roller assembly, and since the joints in the moldings negatively impact on the effect of the thermal insulation.