Patent GB-675181-A (GB)
Title: Improvements in or relating to stencil screen printing machines
IPC: B41F15/42
Filed: 1948-06-11
Abstract: 675,181. Stencil printing-machines. MEYERCORD CO. June 11, 1948 [Dec. 16, 1947], No. 15791/48. Class 100 (ii). A stencil screen printing-machine includes a stencil screen having a supply of printing ink at one end thereof, a squeegee mechanism adapted to be reciprocated over the stencil screen for printing toward the supply of ink and for return movement in the reverse direction, the mechanism comprising a squeegee adapted to operably engage the screen during the return stroke and a scoop adapted to pick up ink at the supply end of the screen at the end of the printing stroke and to transport said ink to and deposit it ahead of the squeegee at the other end of the screen opposite the supply of ink for use during the printing stroke and for return to the ink supply by the squeegee. A stencil screen printing-machine, Fig. 1, comprises a vertically movable table 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 pivotally connected to links 52, Fig. 1, 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, first 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 during the printing stroke. On the return movement the blade 84 is raised above the screen 47. A crank 69, Fig. 1, is pivoted at one end to the rotatable disc 53 and at the other end to a link 70 pivoted to a crank 71 mounted on a rocker shaft 72 carrying levers 74 pivoted to links 76 on either side of the machine. The mechanism 68 comprises an angle plate 77 secured to a pair of end plates 78 each pivotally secured to a link 76. A transverse rocker shaft 80 is supported in the end plates 78. The blade 84 is supported between plates 82 and 86, the plate 82 being secured to the plate 77. A scoop 87, Fig. 3, extending transversely across the stencil screen 47 is secured by an angle plate 89 to a bar 90 journalled in a pair of plates 92 secured to the plate 77 by an angle plate 93. The bar 90 carries a gear segment 96, Fig. 2, which meshes with a gear segment 94 secured to the shaft 80. Rotation of the shaft 80 causes the scoop 87 to pivot in one direction or the other. The shaft 80 is rotated by a rocker arm 97 fixed thereto and provided with an arcuate slot 98 through which a stud 99 connecting each end plate 78 to each link 76 projects. The end 97a of the arm 97 engages spaced stops 100, Fig. 3, secured to the brackets 50. The stops 100 project into the path of the arm 97 adjacent each end of the squeegee stroke so that the arm 97 is rocked as the squeegee approaches either end of its stroke, thus causing the scoop 87 to be pivoted into a horizontal or depending position. During the printing stroke the scoop is held in a depending position so as to allow ink to drip on to the screen by a latch comprising an arm 101, Fig. 3, urged upwardly by a spring 104 into engagement with a roller 103 which engages the right hand end of an abutment 106 on the arm 101. During the return stroke the scoop is held in a horizontal position by the roller 103 which engages the left hand end of the abutment 106. The squeegee mechanism 68 including the blade 84 is raised at the end of each printing stroke by rollers 107, Fig. 3, on the inner sides of the plates 78 which engage tracks 108, Fig. 2, mounted on each side of the machine by studs 109 engaging slots 110. The tracks 108, Fig. 1, are raised at the end of each printing stroke through links 112, 113, 118, and 119 by a roller 121 in engagement with a cam 122 carried on the shaft 32. The tracks may also be raised manually by a treadle 123. In a modification the squeegee and scoop are actuated by an arm which engages stops 100 at the end of each stroke, the arm being connected to the squeegee and scoop by toggle links. The Specification as open to inspection under Sect. 91 also comprises' the subject-matter of Specification 675,257, 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