GB1049362A - Improvements in or relating to the continuous heat treatment of sheet or strip material - Google Patents

Abstract

<PICT:1049362/C6-C7/1> A method and apparatus for continuously heat treating strip material comprise passing the strip in succession through two fluidized beds at different temperatures, and maintaining the strip with its faces in substantially vertical planes during its passage through the beds. In the form shown the strip 25 is passed consecutively through first and second fluidized beds 2, 3 respectively and hence through a chamber 20. The first bed 2, contains heaters 11, arranged in such manner as to direct the fluidized material against the said strip, and maintaining the first bed at a temperature higher than that of the second, which is provided with a cooling pipe 13 and baffles 12 to direct the fluidizable material therein against the strip. The strip enters and leaves successive chambers through slits 14, 5, 18, 14a in the respective walls thereof, the slits being defined by a resilient material, (Figs. 3-5, not shown). Passage of fluidized particles through the slit 18 is minimized by maintaining the chamber 20 at a pressure above that of the chamber 3; any particles passing therethrough being returned to the chamber 3 via the pipe 21 and cyclone separator 22. The baths are fluidized by means of air supplied under pressure through pipes 9, 10 to plenum chambers 7, 8 and hence through the wire mesh 6 to chambers 2, 3 respectively. In a further embodiment (Fig. 6, 7, not shown) the first and second chambers containing fluidizing material are formed with a slot in the floor of each, which slots are connected by an intermediate chamber defined by two spaced curvilinear walls. The strip material passes vertically downwards through the first chamber, through the curvilinear intermediate chamber, protected from contact therewith by an air cushion, and vertically upwards through the second chamber. Examples are given of the effect of such heat treatment on aluminium alloy strip.