GB327486A - Improvements in or relating to heat treating furnaces - Google Patents

Abstract

327,486. Robertson, H. M. Jan. 23, 1929. Tunnel furnaces. - A furnace for the heat treatment of metal articles, and for baking clay goods and enamelled ware comprises side combustion chambers 8 communicating with a common flue 8<a> abcve the roof 91 of the heating chamber. The furnace shown comprises entrance, heating and cooling chambers 3, 7 and 4 respectively, through which the goods are moved by an endless conveyer 6 having its return lap in a tunnel 5 beneath the furnace. The heating chamber is formed between side walls 9 spaced from the outer walls 10 to provide combustion spaces 8, into which gas or oil is delivered by end burners 19, combustion being effected with hot air from a conduit 19<1> extending beneath the space 8, and separated from it by a heat-conducting partition 20. The spaces 8 are covered by slabs 10<1>, and at the end remote from the burners these slabs are formed with ports leading to a flue chamber 8<a> extending above the heating-chamber 7 and both combustion spaces. The gases are exhausted from the chamber 8<a> at the burner end of the furnace. The roof of the cooling chamber consists of a box through which air is drawn by a fan. In a modification the cooling-chamber is omitted, and the goods fall from the conveyer into a shoot 53, Fig. 8, which has a hinged portion 54<a> so arranged that the goods can either be deposited in a box 53<a>, or can be passed direct into the air. Charges, conveying.-The conveyer comprises endless chains 6<a> running on water-cooled tracks 40 at the base of the furnace, and on angle tracks 39 in the chamber 5, upstanding arms 6<b>, and transverse charge supports 6<c>. The arms 6<b> are cranked, so that the chains can be located beneath projecting bricks 9<a> and so protected from the direct heat of the chamber 7. Doors.-The ends of the furnace are closed by vertically adjusted doors, which may have chains depending from their lower edges to prevent admission of air.