GB924071A - Improvements in heat treatment or baking ovens - Google Patents

Abstract

924,071. Bakers' ovens. BAKER PERKINS HOLDINGS Ltd., F. R. DIXON, and R. G. CLEMENTS. July 20, 1960 [July 23, 1959], No. 25287/59. Class 28 (1). [Also in Groups XI, XII and XXX] An oven includes a conveyer (Group XXX) upon which articles, e.g. flour confectionery or foundry cores, are moved through the oven beneath pairs of high-frequency electrodes located in sections of a tunnel through which the conveyer passes, which tunnel is spaced from the top and bottom walls of the oven and is formed of high conductivity and non-magnetic metal to screen the remainder of the oven, further heaters, electric or gas, being mounted within the oven but outside the tunnel. Conveyer 14 carries articles 15 through the oven casing 11, 12, 13, Fig. 1, and through the tunnel sections 24 which enclose pairs of slotted or gridlike electrodes 23 supported by aluminium tubes 57, Fig. 6, traversed by pipes 59 for air cooling. The tunnel is formed by a corrugated stainless steel base 28, upon which the conveyer is supported by skids, and aluminium, brass, or bronze sides 35, secured and earthed to the oven walls, and roof sections 24, the base and the roof sections being perforated to allow simultaneous heating of the articles 15 by convection or radiation from gas or electric heaters 22, and to prevent overheating of the edges of the conveyer. The electrodes 23 are fed from an oscillator 61 via a tuner consisting of a pair of parallel members 63 and an adjustable shorting bar 65. A degree of turbulence in the oven atmosphere is maintained by pumping air from the oven casing through duct 47 and introducing it, via duct 49, into outlet pipes 51 distributed along the top of the oven (Fig. 8, not shown). The air flows horizontally along a pipe 53, Fig. 7, within pipe 51, and expands into the latter through side vents 54, and thence downwards into the oven through vents 52.