GB756315A - Improvements in or relating to stencil printing cylinders - Google Patents

Abstract

756,315. Stencils. BARROS, A. J. C. DE O. Dec. 16, 1954 [Sept. 24, 1954], No. 36438/54. Class 100 (2). A cylindrical stencil screen is formed by coating a flat, metallic mesh screen on one side only with an impervious material, removing the coating according to the desired design, bending the screen into a cylinder and plating the exposed parts of the cylinder in an electrolytic bath so that the mesh is made rigid by the metallic deposit. A very thin metallic deposit is also formed over the impervious coating. The coating 12, Fig. 7, is photo-sensitive so that the design can be formed by exposure to light, developing and washing out. The screen is bent round with the coating inside and welded along the seam 16, Fig. 3. The ends of the screen are soldered to rings 18. For the plating process metal end discs 24, Fig. 5, are inserted in the rings 18 and a shaft 44, e.g. of stainless steel, is passed through the discs 24 insulated therefrom by bushes 40. The ends of the shaft 44 are supported on bearings 48, 50 in the bath and a gear drive on one end enables the cylinder to be rotated slowly during the plating process. Spring brushes 32 bearing on cylindrical bosses 26 of the discs 24 connect the cylinder with one pole of an electric supply and anodes 54, 55 suspended from cross pieces 52, 53 are connected to the other pole. The anodes, e.g. of copper, are of plate form and curved so as to be spaced about the surface of the cylinder. The bath may be a copper sulphate and sulphuric acid solution. After the plating process the wires of the screen 10 are locked together where they cross and thickened as shown at 64 in Fig. 7. The cylinder is thereby rendered rigid and the impervious coating is also strengthened by a thin metallic deposit thereon. Alternatively, the screen may be bent so that the impervious coating is outside, the anode then being arranged inside the cylinder, for instance it may be formed by the shaft 44.