FR2577239A1 - Improvements to annealing ovens - Google Patents

Abstract

Annealing oven, especially for the heat treatment of metal sheets, designed so as to produce either heating or maintaining or cooling in the same vessel, characterised in that the oven chamber is employed alternately for producing the heating and the cooling, separate means for heating and cooling being provided for this purpose in the said chamber.

Description

 The present invention relates to improvements made to annealing ovens. In certain embodiments of annealing ovens, in particular for the treatment of sheets, it may be necessary to produce, in the same enclosure, either heating, or holding, or cooling. If the transition from heating to holding, or from cooling to holding, poses no problem, on the other hand, the use of the same enclosure for heating or cooling is not easy.

In the currently known embodiments, heating elements consisting of radiant tubes are used, which, to ensure the cooling function, are transformed into cooling tubes by rayonnexnentX
For such a system to be effective, it is necessary to solve many technological problems to ensure, in particular, moderate hot gas flow rates, for heating, and very high flow rates with regard to the cold gas circulating in the tubes to ensure the recooling. These requirements translate into excessive constraints, when the change of allocation of the room for, to go from heating to cooling, must be done quickly. Furthermore, the necessary equipment is overabundant.

 The problems posed by known installations are all the more acute as the temperatures reached during the thermal cycle are high, as is the case, in particular, in the processing lines for strips of stainless steel or silicon steel.

 The present invention proposes to make improvements to annealing ovens, making it possible to carry out the heating and cooling actions in the same chamber, but without using common elements to ensure these two functions.

 Consequently, this invention relates to an annealing furnace, in particular} lt for the thermal treatment of sheets, making it possible to carry out in the same chamber either heating, or holding, or cooling, characterized in that the furnace chamber is used alternately for heating and cooling, separate heating and cooling means being provided for this purpose in said chamber.

 According to the invention, the heating is obtained using electric elements, preferably placed on the walls and on the hood of the oven chamber "and the ref-oldsssernent is provided by tubes located in the lower part of These tubes, depending on the performance required for the tsraitemXerAt, can act either as simple radiation tubes or as blowing tubes, and, for this purpose, they are then pierced with orifices directed towards the strip to be treated.

 According to the invention, the furnace chamber is cut e FentiOnS of the same lengths, assigned respectively to the heating action> s cooling action, the transition from heating to cooling, and vice versa, then effected by simple action on the electrical supply to the heating element resistors and on the cooling tube supply valves See the corresponding section.

 In the case of radiation cooling, the tubes are traversed by a stream of blown or aspirated air, and, in the case of direct blowing cooling on the strip, the gas blown through the strip can be recirculated through an external exchanger to keep the desired CompositLon from the interior atmosphere of the oven.

 The invention applies more particularly to ovens for heat treatment lines for stainless steels, silicon steels, and annealing of mild steel.

 It remains to be understood that this invention is not limited to the exemplary embodiments described here, but that it encompasses all variants thereof.

Claims (5)

 1 - Annealing furnace, in particular for the heat treatment of sheets, designed so as to produce in the same enclosure either a heating, a holding or a cooling, characterized in that the furnace chamber is used alternately to produce heating and cooling, separate heating and cooling means being provided for this purpose in said chamber.  2 - Annealing furnace according to claim 1, characterized in that the heating means consist of electrical elements preferably placed on the walls and on the ceiling of the room.  3 - Annealing furnace according to one of claims 1 or 2, characterized in that the cooling means are constituted by radiation tubes located in the lower part of the chamber.  4 - Annealing furnace according to one of claims 1 or 2, characterized in that the cooling means are constituted by direct blow tubes.  5 - Annealing furnace according to any one of the preceding claims, characterized in that the furnace chamber is divided into sections of the same length assigned respectively to the heating action and to the cooling action.