GB860295A - Improvements in or relating to sheet coating apparatus - Google Patents

Abstract

860,295. Coating webs. BRITISH CELLOPHANE Ltd. June 25, 1959 [Aug. 8, 1958], No. 25593/58. Class 140. An apparatus for coating travelling sheet materials, e.g. regenerated cellulose, comprises a pair of spaced parallel rotatable hubbed rollers having longitudinal axes in the same horizontal plane between which rollers sheet materials may be passed and coated with a liquid coating composition, e.g. an aqueous dispersion of a copolymer, maintained in the nip formed by the materials, driving means for rotating the rollers at the same speed but in opposite directions, an adjustable separator placed in each of the spaces between corresponding hubs formed on the rollers for determining the degree of spacing of the rollers, urging means applied to the rollers for pressing the hubs into contact with the separators and a spacing control mechanism for continuously adjusting the separators in such a manner that the hubs may be oscillated to and from each other with a period of oscillation equal to the period of one revolution of the rollers and at such an amplitude and phase with respect to the rotational position of the rollers that any cyclic variation in the spacing of the roller barrels during rotation of the rollers due to eccentricity between the barrels and the corresponding hubs is substantially countered. As shown in Figs. 1 and 2 a pair of steel-hubbed rollers 1, 2 having barrels 3, 4 and hubs 6, 7, are mounted in bearings 5, 5<SP>1</SP>. Between the hubs 6, 7 is an adjustable separator 10 comprising a pair of wedges 11, 12 connected by screw rod 13. Rollers 1, 2 are urged towards each other by backing rollers 14, 15 so that hubs 6, 7 ride in contact with the inclined edges 16, 17 of wedges 11, 12 and maintain the barrels 3, 11 spaced apart. The threads on screw rod 13 and in wedges 11 and 12 are such that when rod 13 is turned the wedges are either drawn together or moved apart in a vertical direction. Hubs 6, 7 and consequently rollers 3, 4 are thereby either forced apart or allowed to move together. Control mechanism 18 for continuously adjusting separator 10 comprises a rotatable member 19 driven from roller shaft 9 through sprockets 20 and 22, chain 21, shaft 24 and spur differential gear 25 in which the cage 26 can be locked against rotation at any 5 degree interval, by means of pivoted plate 29, carrying tooth 30 adapted to enter any one of holes 27 drilled at 5 degree intervals around one half of the edge of the lower face of cage 26. The end of the member 19 remote from gear 25 is fitted with a crank of pre-adjustable throw consisting of a disc 31 having a T-shaped groove 32 cut across one diameter in which is fitted a T-shaped bolt 33 capable of being secured in any position in groove 32 by means of screw 34. Crank-arm 35 attached to bolt 33 is pivoted to arm 36 which is fixed to rod 13. On rotation of member 19, arms 35, 36 are reciprocated by bolt 33 through a distance determined by the position of bolt 33 in groove 32, the period of the oscillation being equal to one revolution of rollers 1, 2. This oscillatory movement is transmitted to rollers 1, 2 by rod 13 and wedges 11, 12. The amplitude of oscillation of rollers 1, 2 may be adjusted by adjustment of the position of bolt 33 in groove 32, and the phase of oscillation with respect to the rotational position of the rollers may be determined by the position in which cage 26 has been locked by tooth 30. Instead of the wedges 11, 12 a pair of shoes arranged back to back may be employed. Specifications 663,645 and 802,682 are referred to.