Patent GB-675257-A (GB)
Title: Improvements in or relating to stencil screen printing machines
IPC: B41F15/08
Filed: 1948-06-11
Abstract: 675,257. Stencil printing-machines. MEYERCORD CO. June 11, 1948 [Dec. 16, 1947], No. 30328/50. Divided out of 675,181. Class 100 (ii). [Also in Group XXIV] A stencil screen printing machine comprises a stencil screen, a table adapted to be raised and lowered to and from printing position under the screen, a squeegee mechanism adapted to be reciprocated over said screen, means for moving said squeegee to and from screen engaging position, means for lowering and raising said table, a rotatable member in driving connection with said means, a source of power for driving said machine, a driving connection between said power source and said member including a manually controlled clutch mechanism for completing or breaking the driving connection to said member for starting or stopping operation of said squeegee mechanism, table, and squeegee moving means at a constant point in the cycle of machine operation, said clutch being adapted to stop the table in lowered position and the squeegee mechanism at the end of its printing stroke. The machine, Fig. 1, comprises a vertically movable bed 36 carried by supports 37 reciprocated by a link 39 secured to a shaft 40 which is oscillated by a cam 44 through a lever 42 carrying a roller 43. A stencil 47, Fig. 2, is carried in a frame 48 within a cradle 49 which is rocked by brackets 50 secured to plates 51, Fig. 1, pivotally connected to links 52 eccentrically secured to a rotatable disc 53 secured to a shaft 32. When the frame 48 is rocked the screen 47 is peeled cleanly from a printed sheet on the table 36. Sheets are fed from a table 54 by gripper bars 56 carried by chains 57 to the table 36 and then to the delivery end of the machine where they are dried. The squeegee mechanism 68, Figs. 1 and 2, extends transversely of the machine and is adapted to be reciprocated longitudinally of the machine so that the squeegee blade 84 only engages the screen 47 as it moves to the right as seen in Fig. 1, on the printing stroke. On the return movement the blade 84 is raised above the screen 47. Clutch mechanism.-A clutch 34 disposed on the shaft 32 is arranged to break the driving connection between a driving shaft and the shaft 32 at a certain point in the cycle of operation of the machine so that the table 36 is stopped in its lowest position and the squeegee 84 is stopped at the end of its printing stroke. The clutch 34, Fig. 11, comprises a sleeve 140 mounted on bushes 143 and 145 free to rotate on the shaft 32. A cam lock plate 147 is secured to the sleeve 140 and a gear 31 by bolts, the gear 31 being constantly driven by a gear on the driving shaft. The sleeve 140 extends through a stationary cam plate 148 secured to a plate 150. An arm 151 fixed on the shaft 32 carries a rocker lever 156 supporting rollers 157 and 158. The roller 157 is adapted to engage a recess 159 in the lock plate 147 and the roller 158 is adapted to engage a recess 160 in the cam plate 148. The lever 156 is urged in a clockwise direction about its pivot 154 by a spring 161 secured to a bracket 162 so that the roller 157 is held in driving connection with the recess 159 in order that the shaft 32 may be driven. A dog 166 secured to a rotatable shaft 167 is adapted to engage a lug 164 on the lever 156 thus preventing further rotation of the arm 151 and shaft 32 and withdrawing the roller 157 from the recess 159. The roller 158 moves into engagement with the recess 160 and a leaf spring 168 engages a locking- plate 169 to prevent movement of the arm 151 and shaft 32 in a counterclockwise direction. The Specification as open to inspection under Sect. 91, also comprises the subject-matter of Specification 675,181 and states that the scoop may be replaced by an ink spreading member which engages the screen during the non-printing stroke of the squeegee mechanism. This subject-matter does not appear in the Specification as accepted.