GB647097A - Improvements in screen printing machines - Google Patents

Abstract

647,097. Stencilling-machines. MARTIN, L. April 2, 1948, No. 9382. [Class 100 (ii)] A screen printing-machine comprises an endless blanket arranged to travel over a flat supporting surface and to hold the material to be printed thereon, a continuously - driven reciprocating mechanism including an adjustable throw crank operating through a oneway clutch upon the belt drive intermittently transporting the material to be printed across the machine through a pre-determined distance at each step, and a printing screen supported over the bed and arranged to be moved automatically into and out of contact with the surface of the material to be printed during the intervals when the bed is stationary. The machine comprises a flat table 24 supported by a tubular framework 20, Fig. 2, and having spacers 22 therebetween for adjusting the level of the table 24 which has slots 25, Fig. 10, through which extend the upper runs of three chains 26, the chains having lugs 28 to which are attached the endless blanket 29. The chains 26 are driven from an electric motor through the reciprocating mechanism which comprises a crank arm 72 to which is pivotally attached, at an adjustable radius, a rack 78 engaging a pinion forming the driving member of the one-way clutch axially attached to a shaft 36 carrying sprockets 31 over which the chains 26 run. The blanket 29 has an outer solid cover 30 and an undercovering of cellulosic material to prevent wear during its movement over the table 24. The belt is made adhesive so that the web to be printed, which is fed from a supply roll 56, can be fixed thereto. The belt, after carrying the web past the stencilling positions, passes through to a cleansing device comprising a spray nozzle 45, Fig. 2, and thence over a towelling belt 49, after which the belt is dried by a hot air source 51, 52, 54. Driven also in synchronism with the belt are two cams 106 which raise the printing screens carried in frames 100, about hinges 101 at the moment when the endless belt is stationary. Colour distributing mechanism.-Colour is distributed over the screens for printing by a rocking squeegee comprising two blades 124 and 125, Fig. 10, spring-urged downwardly on to the screen 113. The blades are mounted on a shaft 138, carried between rollers 139, Fig. 1, which travel on tracks 140 and is moved by a shaft 142 from an air motor 141, the connection from the shaft 142 to the shafts 138 being a forked member 149. At the end of each stroke the fork 149 pivots the shaft 138 by an amount determined by the engagement of one base corner of segments 151 engaging rails 152 adjustable relative to the segments. At the end of the rearward stroke the shaft 138 engages a lever 179, which is thereby pivoted clockwise, Fig. 10, and opens a gate 178, normally closing an opening in a container 171, to allow colouring matter to fall on to a shelf 132 fixed on to the squeegee blade 125, which has a slot 131 for the colour to pass through on to the screen. The fabric is dried between the various stencilling positions by means of lamps 190, 191 and 192.