Patent GB-729105-A (GB)
Title: Silk-screen multi-colour printing machine
IPC: B41F15/08
Filed: 1953-06-16
Abstract: 729,105. Stencilling machines. DUBUIT, L. G. June 16, 1953 [June 17, 1952], No. 16643/53. Class 100 (2). Machines for stencilling in more than one colour on articles having conical, spherical or cylindrical surfaces comprise a carrier adapted to receive at least two silk screens following one another, means under the screen carrier for mounting and rotating the article at such a speed that its surface and the screen have the same velocity, squeegees in a - number equal to the number of screens, each squeegee being mounted on a bar displaceable into or out of contact with the corresponding screen, the bars being received in a notch in a fixed member to hold the squeegee stationary during stencilling and means for lifting the squeegee bar out of the notch and carrying it away while the succeeding squeegee bar is received in the notch to make the stencilling operation with the next screen. In the form of Figs. 1 and 2 the machine frame 1 carries a vertical fixed shaft 3 on which is rotatably mounted a carrier plate 5 having cut-away parts to receive the stencils 13, 14. A bracket 28 is fixedly mounted on the shaft 3 and presents an upwardly open notch at the free end. Collars 7, 8 also rotatably mounted on the shaft 3 carry the bars 16, 17 on which are adjustably mounted the carriers 20, 21 for the squeegees 22, 23. A pulley portion 11 on the plate 5 receives a few turns of a cable 12 which passes over pulleys 38, 39, 40, 41 and round a driving pulley 35 of a chuck 34 rotatable about an axle 53 in a frame 52 and adapted to support the article 33 to be printed. The frame 52 is pivoted about an axis 50 and adapted to swing clockwise to present the curved surface of the article 33 against the under surface of the screens. The frame is moved into and out of this operative position by a link 57 connected to a crank arm 58 mounted for rotation on a shaft 59 and controlled by a handle 61. The precise position of the frame during the stencilling operation is governed by an adjustable stop limiting rotation of the crank arm 58. The chuck is opened by a lever 55 and rotated by a handle 54. Cam members 29, 30, 31 mounted on the plate 5 at points corresponding to the ends of the screens are adapted to lift and control movements of the bars 16, 17 carrying the squeegees as illustrated in Fig. 5. The sides of the notch 28e in the bracket 28, Fig. 4, are provided with cut-away parts 28b, 28d corresponding in shape to cut-aways (e.g. 16a) in the coacting parts of the levers 16, 17 so that one lever, 16, may pass out of the notch over the side having cut-away 28b when lifted by cam surface 30a and the other lever 17 may pass into the notch over the side having cut-away parts 28d when supported on cam surface 30d. In operation the lever 16 is placed initially on cam surface 29b, Fig. 5, and over the notch 28e of bracket 28 and lever 17 is placed on cam surface 30d. An article 33 to be printed is positioned in the chuck 34 and swung into engagement with the underside of stencil 13. Rotation of handle 54 then causes the plate 5 to turn so that cam 29 moves away from under lever 16 allowing it to fall into the notch 28e and bringing the squeegee into engagement with the screen 13 for the printing stroke. At the end of the printing stroke the lever is lifted by cam surface 30a, passes. out of the notch 28e and is carried away on cam surface 30b. Meanwhile lever 17 having passed over the side parts 28d of the notch abuts side parts 28b which it is not shaped to pass and is thereby swept off the surface 30d and lowered into the notch. The squeegee carried by lever 17 consequently comes into engagement with the screen 14 and effects the second printing operation. - At the end of the printing stroke the lever is lifted by cam surface 31a and engaged by cam part 31c which prevents further rotation of the machine. The printed article is then replaced by a fresh one and the machine rotated in the reverse direction for the next printing operation. Where printing is with a heated molten substance which sets on the article it is necessary to print in one direction only. A swinging cam member 66, Fig. 8, is therefore mounted on the bracket 28 and adapted in one position to prevent the squeegees from engaging the screens. The member 66 is displaced by stops 67, 68 on the plate 5 at each end of the movement so that movement in the reverse direction is ineffective to cause printing and merely returns the levers 16, 17 to their initial positions on cams 29 and 30. In the form of Fig. 9 a machine for printing on cylindrical articles comprises parallel guides 102 on which run sliders 103 supporting carriage 104 mounting the screens 105, 106 which are separated by a low wall 107. Extensions 109 from each end of the carriage are connected to a chain 108 passed round a pulley adapted to drive a rotatable supporting device for the article 126 which is thereby driven at the same peripheral speed as the screen. A member 110 fixed on each guide 102 has a centrally disposed notch 110a the sides of which are specially shaped to co-operate with cut-aways on cross bars 114 carrying the squeegees 112 (in a manner similar to the notch 28e and cut-aways on levers 16, 17 in the first form). A bracket 111 fixed to each side of the carriage has a pair of spaced notches to receive the cross-bars 114 when not in the operative position in notch 110a. Chains 116 connected to the sliders 103 pass round end pulleys 171 and engage sprocket 119 connected to a cross shaft 120. Cams 121 mounted on the shaft 120 have rise parts 121a, 121b, 121b adapted to lift follower rollers 122 mounted on vertically slidable plates 123 having inturned lips 125 for engagement under rollers 115 at each end of the cross bars 114. The operation is similar to that described for the first form, the squeegee carrying bars being lifted out of the central operative position by the action of the cam 121 and carried away on the brackets 111. Specification 712,131 is referred to.