GB470003A - Improvements relating to the heat treatment of metal articles - Google Patents

Abstract

470,003. Heat treating. DENNEEN, F. S., and DUNN, W. C. Feb. 3, 1936, No. 3140. Convention date, Feb. 4, 1935. [Class 72] [Also in Group XII] In the heat-treatment of metal articles, the article or a portion of it is surrounded by an enclosure in which the surface of the article is heated by a flame which is moved over the surface relatively to the enclosure, and the heating period is terminated by automatically cutting off the supply of fuel to the flame through the medium of a heat- or light-sensitive device controlled by the temperature of the heated surface, the article then being quenched. When a plurality of flames are used, the intensity of the individual flames, and also their interruption, are automatically controlled. The article 11, Fig. 1, is mounted in an enclosure 12 provided with a cooling jacket 14 and opening 20, closed by a spring-controlled valve 18, for the escape of gases produced in the enclosure. Burners 16, 17 are mounted on carriers 28, 29 which are reciprocated horizontally by a lever 30 hinged at 31 and moved by a rod 32 in openings in the enclosure 12. Fitting in an opening in the top of the enclosure 12 is a chamber 48 which is shaped at its lower end to the contour of the article 11 and is provided at its upper end with a transparent cover 51 outside of which a photo-electric cell 47 is arranged, the supply of fuel to the burners being cut off by a solenoid 55 or a motor connected to the device 47. To prevent the flow of hot gases into the interior 52 of the chamber 48, a fluid, preferably a heated inert gas, may be introduced therein by the pipe 53. To ensure a sufficient heating over the entire width of the article, a group of cells such as 47 may be arranged in line and all connected in series so that control device 55 is not operated until the minimum desired temperature has been reached at all points. Simultaneously, with the interruption of the heating by the device 55, a suitable valve or valves in the pipes 56, 57 will be opened and quenching fluid will be projected through those pipes on to the heated surface of the article. A reducing atmosphere in the enclosure 12 may be provided by the introduction of a gas such as hydrogen, carbon monoxide or a hydrocarbon. To prevent oxidation by the quenching liquid, air or other gases is expelled from the same by heating under pressure, and the liquid may be aerated with hydrogen. In a modification, in which the article to be treated is rotated, the burners are mounted in the upper part of the enclosure so that they can be oscillated and the control of the fuel supply to the burners is produced by a thermo-couple mounted in a chamber similar to the chamber 48. When a hollow article is being treated, cooling liquid may be passed through its interior. A bimetallic strip may be used for the temperature control instead of the photo-electric cell or the thermo-couple. Specification 445,425 is referred to.