GB171121A - A photographic projection copying or contact printing apparatus for making photomechanical printing plates - Google Patents

Abstract

171,121. Boedicker, H. C. May 4, 1920. Printing-apparatus. - In apparatus for projection copying or contact printing such as described in Specification 155,340, and for making photomechanical printing plates, the printing plate is stretched from one side by a series of individually displaceable clamps, mounted on a bar which is displaceable by screw shafts to stretch the printing plate as a whole. The frame carrying the printing plate is vertically adjustable, and an independent pressure plate, also vertically adjustable, is mounted behind the printing plate frame, and is covered with a resilient covering which can be drawn taut across the face of the pressure plate. The printing plate framework 48 - - 51, Fig. 1, has a series of clamps 103 on the lower bar 51 and a series of individually displaceable clamps 104 on a bar 105 which is vertically adjustable in the framework. The clamps comprise clamping jaws 124, Fig. 15, mounted on a bar 121 hinged to the bar 105 and adapted to stretch any portion of the printing plate 71 by the screw 126. The bar 105 is vertically-movable to stretch the whole printing plate by means of screw shafts 110, 111, being supported by bevel wheels 112, 113, Fig. 11, which are rotated through bevel gearing from a central key and bevel wheel 118 mounted at the back of the bar 105. The frame 48 - - 51 is vertically adjustable in slide ways on the carrying frame 45 by means of screw shafts 55, 55<1>, which are turned by a hand wheel 52. To accurately step or re-locate the printing plate in any position, the frame 49 carries a scale 49<a>, Fig. 3, and the frame 45 an adjustable pointer 45<a>. The hand-wheel 52 also has a micrometer scale 90, Fig. 2. The carrying frame 45 is rigidly mounted in conjunction with a brace frame 44, and an independent pressure plate 59, Fig. 1, is also mounted to slide vertically on this frame, by grooves 61, Fig. 18, in the section 129 of the frame. The pressure plate is vertically adjustable by screw shafts 63 and operated from a handwheel 66, Figs. 1 and 2. The resilient covering comprises a padding 134, Fig. 2, over which is a rubberized blanket 135. The blanket is caught under the strap 136 screwed to the top of the plate 59, passes over the plate, and is attached to the roller 137, by which it may be stretched taut.