GB833436A - Improvements in or relating to web supply mechanism - Google Patents

Abstract

833,436. Feeding webs. CRABTREE & SONS Ltd., R. W. July 12, 1956 [July 14, 1955], No. 20477/55. Class 100(1) [Also in Group XXXV] A web supply mechanism comprises a support which is movable to carry a running roll from a normal running position to a web transfer position, a first electrically operated web tension control means operating by peripheral engagement with the running roll in the normal running position, a second electrically operated web tension control means operating through the roll centre, a device producing electrical signals in response to change of web tension and means to transfer the latter signals from controlling the first tension control means to controlling the second tension control means as the running roll moves to the web transfer position. In Fig. 1, a supporting spider comprises three arms 1, 2, 3 rotatable about a shaft 4 by a motor M1. Rolls are loaded at position 7, the spider rotated to move the roll to the normal running position 6 in which position drive and tension control are imparted to the roll by a continuous belt 8 driven over rollers 9, 10, 11, the expiring roll moved to position 5 and the web W transferred from the expiring toll to the new running roll by operating a brush 13 to press the web on to an adhesive covered section of the periphery of the new running roll whereupon a knife 14 is operated to sever the web. The web passes to a consuming machine via a tension responsive device 16 which operates a switch 18, Fig. 2, controlling a reversible motor M2 to raise or lower an arm 12 carrying roller 11 so that the angle of wrap of belt 8 is adjusted to maintain web tension constant while it is being supplied from a roll in the normal running position. When the diameter of the running roll decreases to a predetermined value, movement of an arm 83 carrying a roller 82 running on the periphery of the roll causes electrical actuation of means to engage a roller 92 with roller 9 causing an arm 93 to move clockwise at a rate corresponding to the rate of feed of the web so that after a predetermined length of web has been fed a switch 94 is operated to initiate web transfer. This involves raising arm 12 so that belt 8 is clear of the running roll whereupon web tension control is effected by a switch 19, Fig. 2, controlling reversible motor M3 to adjust a potentiometer R in the circuit of an electromagnet 22 operating a disc brake 46 on the running roll. Motor M1 is then operated to move the rolls in an anticlockwise direction until stopped by the operation of a switch (not shown) on engagement of a fresh roll with an arm 70 carrying a roller 69, a further motor (not shown) having operated to bring arm 70 into an operating position. Arm 12 is then lowered to speed up the new roll and web transfer gear 13, 14 moved to a position of readiness as shown. Arm 93 continues to rotate until it closes a switch 95 so that, when the new roll rotates to a position in which it cam-operates a further switch (not shown) through a member 56, brush 13 operates to press the web against the adhesive-covered section of the periphery of the new roll and knife 14 operates to sever the connection with the used roll. The used roll is then stopped by full application of its electromagnetically operated disc brake. A similar brake for the roll in the loading position may be manually controlled. Specification 823,207 is referred to.