GB631135A - Improvements in and relating to screen printing apparatus - Google Patents

Abstract

631,135. Stencilling-apparatus. WALKER, D., and EVANS & CO., Ltd., D. April 16, 1947, No. 10148. [Class 100 (ii)] A screen printing-apparatus comprises mechanical lifting means for raising a screensupporting frame diagonally from a support cornerwise and progressively to break the adhesion between the screen and the materials being printed after a printing impression has been made, without undesired disturbance of the material on the support. As shown, the screen and framework 2, 3, 4 are attached to a rear channelshaped member 80 forming a carriage having a pair of grooved rollers 85 which travel along a table rail 86 and form a hinge about which the whole carriage may be raised, the location of the carriage along the rails into each pivoting position being determined by a stop 109 and a pair of sockets 113. The stops and sockets are adjustably secured to the rails 86. The mechanical lifting of the carriage is effected by moving roller-carrying levers 81- 82, Fig. 5, about pivots 83, 84 by means of small links 105, 106a and 105, 106 respectively, which are operated by rods 104, Fig. 1, extending from the front of the machine where they are connected by a pair of parallel levers to an operating-handle 102. Downward pressure on the handle 102 will thereupon immediately cause the rear right-hand corner of the stencil to rise, but due to the lost motion of a slotted connection 107, the lifting of the left-hand corner is delayed. The carriage is locked in the raised position by a catch 119, Fig. 7, engaging a recess 115 in a block 89 forming a coupling between the two levers 81, 82. Block 89 has a pin 93 rising through the carriage to form part of a spring assembly which gives a cushioning to the carriage when a pin 90 depending from the block 89 drops into a locating slot 108 in the stop 109. After the initial raising and sideways travel of the carriage, the higher corner of the carriage is lowered to bring it level by the engagement of a lever 130 with an end part 133 of the stop 109. Lever 130 has a slot 128 through which projects a pin 127 mounted on an eccentric boss 125 forming the bearing 84 of the lever 82. An elongated bearing hole 124 for the boss 125 is provided in the lever 82 so that when the lever 130 is rotated by engagement with a stop 109 the anticlockwise movement imparted to the pin and boss permits the carriage to fall relative to the lever 82. When the next printing position is approached, a lever mechanism 134, 120 having been lowered by the action of lever 130, engages the next stop 109 releasing the block 89 and the pin 90 slides down a slope 135 until finally located in the slot 108. During the reverse travel of the carriage, lever 134 and lever 130 are ineffective since clockwise movement of the former will not actuate the catch 119 and similar movement of lever 130 will not rotate the eccentric disc since the pin 127 rides freely in a slot 128 in the lever. The construction and operation of the squeegee is described in Specification 625,108.