GB801556A - Improved screen printing apparatus - Google Patents

Abstract

801,556. Stencilling-apparatus. McCORMICK, W. P. Feb. 11, 1955 [Aug. 4, 1954], No. 22568/54. Class 100(2) A continuously operating stencil printing machine comprises pressure and guide rollers round which passes an endless flexible printing screen, an impression roller arranged so that an upwardly facing arcuate zone thereof supports the screen between the other rollers, a conduit for feeding ink to the screen above said zone and distributing ink across the screen, a device for squeezing ink through the screen at the end of said zone, mechanism for continuously rotating the pressure roller, and releasable means for forcing the impression and pressure rollers together to farm a linearly concentrated nip at the start of said zone, so that the screen will be forced to travel continuously round said zone from the nip to the squeezing device and thence back around the guide and pressure rollers to the nip, said guide roller being arranged to lead the screen tangentially from the impression roller immediately beyond the squeezing device. The pressure roller 25, Fig. 4, rotates in stationary bearings. The guide roller 26 rotates in bearings 50, 51 mounted in blocks 43, Fig. 7, adjustable to and from the pressure roller for altering the tension of the screen. The blocks 43 are adjusted by means of a hand wheel on a shaft 45, worm gearing 47, 48, and screws 49 threaded in the blocks. For correcting the alignment of the screen, one of the bearings 51 is adjustable transversely in its block 43 by means of a grub screw 52 turned by a hand tool inserted in a slot 53. The impression roller 24 has bearings carried on arms 36, and the roller is urged against the pressure roller 25 by pneumatic devices comprising cylinders 38 and piston rods 39 at each side of the machine. The pressure at each end is separately adjustable by adjusting leak valves in the supply lines to the respective cylinders 38. A squeegee 72 and a blade 75 to clean superfluous ink from the roller 25 are mounted on a bar 73, which through bell-cranks 75, 76 and pneumatic devices comprising cylinders 81 and piston rods 82 at each end of the machine, is mounted so as to force the squeegee and the blade against the rollers 24, 25, pressure being similarly adjustable at each end by leak valves. The arms 75 can be withdrawn to the left in order to facilitate removal of the squeegee assembly. The screen forms the subjectmatter of Specification 801,557. The Provision Specification refers to Specifications 350,541 and 483,590 [both in Group XXII].