Patent GB-502442-A (GB)
Title: Stencil printing machine
IPC: B41F15/18
Filed: 1938-04-19
Abstract: 502,442. Stencil printing machines. KESSEL, J. April 19, 1938, No. 11714. [Class 100 (ii)] A stencil printing machine is provided with an intermittently-travelling printing- support which is heated, pasted for retaining a web or sheet thereon for printing operations, and then washed to remove the paste therefrom, one or more stencils adapted to be raised and lowered either by hand or automatically, and means for moving the printing-support in a fully or semi-automatic manner, provision being made for moving the support first at a rapid speed, and then at a creeping speed, to enable fine adjustment for printing, and means being incorporated for giving a visible or audible warning when the support is in the printing position. The machine includes an automatically-operated doctor device for distributing ink over the stencils, and means for raising the doctor or doctors near the end of each reciprocation. As shown, the machine comprises a felt-covered table 1 around which is an endless band 2 of rubber or rubbered fabric supported on rolls 3, 4 which are connected together by an extensible driving chain. The roll 3 is keyed on the driving shaft 5 of the machine adapted to bo rotated intermittently by a motor A through a gearing arrangement B. Narrow stripes of adhesive are applied to the band 2 by a ribbed roll 12 to which adhesive is supplied from a container 13 by a roll 14, and the web 7 or; if desired, separate pieces such as table cloths, to be printed is, or are, applied to the band by a heated roll 10 co-operating with the roll 4. The printed web 7, on leaving the band 2, is drawn through a drying device IV by a reel 38 on which the web is rewound, the reel being driven by belt means from the shaft 5. If, desired, the printed web may be forwarded to a folding and collecting device. The band 2 2 returns through a washing device III comprising a vessel of heated water, rotary brushes, and laterally movable stricklers 43, the rotary parts of the device being driven from the gearing B through a chain drive, and the stricklers being actuated by a lever system 43a, Fig. 3, actuated from a cam 43b on the shaft 5. The band 2 is dried by passing beneath the table 1 which is of hollow construction and provided with heating means. As shown, there are two stencils 6 mounted for accurate adjustment on a pair of rigidly interconnected vertically movable bars 24. The bars 24 are adapted to be raised and lowered when the band 2 is at rest either manually by means of a lever 27, connecting- rod 28, and lever system 29, or automatically by means of a toothed crank disc 31 and switch disc 74 connected thereto, a connecting- rod 30, the lever 27, rod 28, and levers 29. The crank disc 31 is driven by gearing from an auxiliary motor C. Ink is spread on the stencils 6 automatically by means of spreaders or doctors 37 which are operated from an auxiliary motor D which is switched in automatically when the motor C is switched off. The motor D drives two endless chains 77 or the like which carry a cam 78 and a bolt 79, the cam being adapted to actuate a control disc 81 which controls through an electrical circuit the motor D, and the bolt being adapted to move a carriage 80 to-and-fro. The carriage 80 has secured to each end the ends of a long rope 84 which is arranged by a system of pulleys to cross the table 1 several times, and is adapted to move the doctors to-and-fro transversely of the table 1 and stencils 6. The two doctors 37 rest in a slot in a long longitudinal holder 85 carried by the bars 24 and consequently ascends and descends with the stencils, and which is adapted to be moved transversely of the table by means of the rope 84. Cam bars over which the doctor holder rolls, and abutments, effect the lifting of the doctors near the end of each stroke to enable them to pass behind the heap of ink for the return stroke. The cam 78 and control disc 81 can both be adjusted to control the number of to-and-fro movements of the doctor, and more than one cam could be secured to the chains 77. The drive from the motor A to the printing support or band 2 is controlled either by a hand clutch G. or electricallyoperated clutches E and F, the clutch G serving only for a quick movement of the band 2 which could be controlled by a brake, and the clutches E, F for quick and slow movements respectively. If desired, the band 2 could be moved by hand by turning a handwheel J mounted on a countershaft 47 of the gearing B ; this arrangement also allows fine adjustments of the band 2. The motor A drives by means of a belt a pulley 48 which is then clutched to the countershaft 47 by the clutch G by turning a hand-lever 51 and the shaft 5 is driven at high speed through gearwheels. For electrical operation, the countershaft 47 has rotatably mounted thereon a pulley 70 with the clutch E, and a pulley 71 with .the clutch F, the pulley 70 being driven directly from the motor A by a belt, and the pulley 71 being driven indirectly through a reduction gear 66 of the motor A. A device K is provided for accurate adjustment of the band 2 during printing comprising a lever 59 geared to an indicator lever 60, and a catch L clamped in a predetermined position on the band 2 is adapted to strike the lever 69 to move the indicator lever 60 into engagement with an adjustable electrical contact 61 to stop tho drive of the band and to start the stencil motor C in the case of an automatic electric drive, or, where the band is manually driven or governed by the hand-clutch G, to serve as an audible or visible warning. Prior to engaging the lever 59, the catch L engages an abutment 97 which, when the machine is fully automatically operated, acts to disengage the quick acting clutch E and to clutch the slow-acting clutch F to the shaft 5. The catch L can be manually or electromagnetically clamped on the band 2, and can be returned to initial position against a stop 64, either by hand, or automatically. through the agency of a screw spindle 65 rotated from the reduction gear 66. In the electrical circuit of the motors A, C, D, in addition to a current supply from the mains, there is a secondary current supply, shown as a battery. The band 2 is accurately guided laterally as it passes around and leaves the roller 4, and is supported above and below between the roller 4 and the table 1. The heating arrangement of the machine may be hot air, steam, or electrical, and is automatically controlled. More than two stencils 6 may be employed depending upon the number of colours to be printed.