GB793216A - Improvements in or relating to a method of and machine or apparatus for drying coated sheet stock - Google Patents

Abstract

793,216. Drying coated sheets of paper &c. BLACK, J. A. Feb. 18, 1956, No. 5109/56. Class 34(2) [Also in Group XXX] A method of drying coated sheets of paper &c. consists in subjecting the sheets to a current of heated air and then allowing them to absorb moisture corresponding to room humidity prior to stacking. As shown, the sheets 138. Fig. 3, are dried by conveyance by racks 74 in a rightward direction over a table 33 formed by the top of a chamber 31 heated by hot air supplied through ducts 29, 30 disposed at the opposite sides of one end of the chamber and connected to an upper chamber 22 spaced a little above the table and containing vertically-adjustable, electric heating plates 35 over which air is circulated by a fan 27, Fig. 1, driven by an electric motor 28 and connected to a duct 25 communicating with the drying room. The racks are supported by end rollers 76, 77, Fig. 11, running on side tracks 66, 67 and are traversed through the narrow space between the chambers by endless-travelling chains 49,50 carrying projections 92, 93 for engagement with the racks. After passage over the table, the racks are transferred to a lower pair of tracks over which they are slowly traversed in a leftward direction by projections on a lower pair of endless-travelling chains with the sheets in a depending position to a point at which the sheets are automatically released from the racks and fall into a collecting tray 148. The slow movement of the racks over the lower tracks enables the sheets to absorb moisture corresponding to the humidity of the air in the drying room which prevents subsequent buckling of the sheets. The air is exhausted from the chamber 31 by a fan 139 into a shallow transverse chamber 142 having an outlet slot 32 from which the air issues in a jet which raises the sheets 138 into a vertical position as the racks are transferred from the upper to the lower tracks, the air then passing to an. outlet duct 26 having a damper 143 by adjustment of which a portion of the air is recirculated. The upper and lower tracks are connected at their ends by arcuate tracks 71, 72 to facilitate the transfer of the racks. Each sheet is attached to its rack by a gripper bar 81, Figs. 11, 12, secured at its ends to a guide arm 78 carrying a roller 79 running on a closed track at one side of the apparatus, and a block 80 freely mounted on the rack, and spring clips 89 also mounted on the rack and formed with slots engaged by pins 91 secured to the rack. Rigidly secured to each rack is a trip arm 86 which abuts against a stop 146, Fig. 3, to effect partial rotation of the rack to open the clips and release the sheet so that it falls into the tray 148. The trip arm is also actuated by cam mechanism to open the clips when the rack is transferred from the lower to the upper tracks at the left end of the apparatus, to permit the feed, either manually or automatically, of a fresh sheet to the rack.