GB656896A - Improvements in or relating to heat treating furnace and method of use - Google Patents

Abstract

656,896. Heat-treatment furnaces. DOW, J. A. April 7, 1948, No. 9733. Convention date, May 6, 1947. [Class 51(ii)] A heat-treatment furnace of the forced convection type is heated by radiant tubes 28 disposed down two side of the heating chamber 16, heavy heat-storing slabs 31 of a material of high specific heat and good conductivity, e.g. carborundum being set in the walls adjacent the tubes in order to assist in the rapid heating of the 'circulated atmosphere gases when the cold work is first charged. In a modification, Figs. 3 and 4 (not shown), the radiant tubes are enclosed by squarestacks of the heatabsorbing material open at the top and bottom so that atmosphere gases may circulate therein. A further modification, Fig. 5, comprises a cylindrical chamber 41 having a removable cover 42 and enclosing a cylindrical work container 46, a cylindrical heat-absorbing element 48 and electric heating elements 49 disposed therein. In a final modification, Fig. 6 (not shown), a further inner concentric heatabsorbing element encloses the heating elements 49 in an annular stack through and around which the atmosphere gases are circulated. With a heat-absorbing element roughly equal in weight to the work treated the temperature gradient in the work, after an initial rise, falls to a minimum about half-way through the heating period and remains substantially constant, the heating elements can be operated at an appreciably lower temperature than in the normal furnace, and the heat equalizing or soaking period is considerably reduced giving a more even processing of the work.