Pilkington Brothers P.l.c.

Donald C Wright

Brian Marsh

Gordon T Simpkin

Willem Wiechers

Rodney L Young

The invention provides a method and apparatus for treating articles with particulate material, for example for thermally toughening glass sheets. The particulate material consists of or contains permanently magnetized particles and is subjected to an electromagnetic field which travels linearly through the treatment space and is effective to sustain a dispersion of the particulate material in the treatment space. The article is contacted with that dispersion.

Thermally treating articles with particulate material and apparatus

A glass sheet is thermally treated, for example thermally toughened, by heating the glass sheet, and lowering the sheet into a gas-fluidized bed of particulate material which is at a glass-treatment temperature, for example quenching temperature. Extraction of gas from a localized upper region of the bed is commenced prior to the lowering of the hot glass sheet into the bed in order to produce gradually an unfluidized static packed condition of the material in that upper region of the bed. The glass sheet is lowered into the bed at a time after commencement of gas extraction which is such that the lower edge of the sheet passes through that upper region prior to full attainment of the static packed condition.

Thermal treatment of glass sheets

A gas-fluidized bed of particulate material is operated by extracting gas from a localized region of the bed to produce an unfluidized static condition of the material in that region. The region may be in the upper part of the fluidized bed, or may be a region adjacent a side opening into the bed where the unfluidized static material obturates the opening. There may be a plurality of unfluidized static regions in the bed. The invention is applicable to the thermal toughening of glass quenched in the fluidized bed.

Method and apparatus for controlling a fluidized bed

An article, for example a glass sheet, is treated in a gas-fluidized particulate material by advancing the article along a path leading into the gas-fluidized particulate material and extracting gas from a region of the path at a rate sufficient to pack the particulate material in that region and thereby obturate the path. An opening leading into a container for a gas-fluidized bed of particulate material may be obturated in this way. The packed state of the material obturating the opening is such that an article can pass through the opening.

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Parbold, United Kingdom

Donald C Wright