Patent GB-1009740-A (GB)
Title: Stencil-printing machines
Inventor: WILFORD ERNEST
IPC: B41F15/46
Filed: 1963-07-19
Abstract: 1,009,740. Stencil-printing machines. BRADFORD DYERS' ASSOCIATED Ltd. July 15, 1964 [July 19, 1963], No. 28727/63. Heading B6C. In a multicolour screen printing machine of the type disclosed in Specification 895,706 at least one colour box comprises an applicator 4, Fig. 1, having a central pressure chamber 5, Fig. 3, for colouring liquid lying within a suction chamber 6 both chambers being mounted on a block 8 which carries inverted U-shaped rubber members 9 extending over the whole width of the machine The inner walls 10 of these members 9 constitutes squeegees lying on each side of a space 11 to which passages 12 in the base of the chamber 5 and block 8 lead. Passages 13 are formed through the members 9 and the block 8 to put the suction chamber 6 in communication with the spaces within the members 9. The applicator is closed at the top except for openings to which pipes 14 and 15 are connected. The pipes 14 branch from a pipe 16 which is connected to the pressure side of a pump 17 by which colouring liquid is drawn from a container 18 and supplied to the chamber 5 through tubes 7 which extend upwards through the top of the chamber 6. The pipes 15 branch from a suction pipe 19 which is connected to a suction pump 20, the pressure side of which delivers to the container 18. In operation both pumps 17 and 20 run continuously so that liquid is supplied to the chamber 5 and suction is applied through the chamber 6 to the interiors of the members 9. In consequence, colouring liquid leaking beneath the squeegees 10 is drawn away and returned to the container 18. In the printing of fine lines on deep pile carpet an applicator is used which effects printing in two stages. In the first the liquid is applied to the stencil under gravity while suction is-applied to the underside of the carpet, whilst in the second further liquid is applied to the stencil under position pressure. The applicator has end and side walls 21, 22, Figs. 4, 5, and an assembly 23 extends from one end wall to the other within the side walls and is composed of a top header section 24, a middle chamber section 25 and a bottom printing section 26. The section 24 is bounded by a horizontal partition 27 and is divided into three suction chambers 28 and two pressure chambers 29 to which appropriate suction and supply pipes 30, 31 are connected. The section 25 is divided into a further pressure chamber 54 and lateral suction chambers 32, 33, passages 34 communicating pressure chambers 29, 54, whilst passages 49 join the suction chambers 28, 32 and 33. A nozzle 35 which receives colouring liquid from the chamber 54 through openings 36 lies between two longitudinal members 38 suspending double-lipped squeegees 39. The assembly 23 is spaced from the walls 22 to form open-topped chambers 41, 42. Squeegees 44 form the lower boundaries of these chambers. In this application the suction is applied to the chambers 41, 42 with the result that colouring liquid can build up in them to the level of the bottoms of passages 43 when printing is not taking place, such liquid passing from the nozzle 35 and underneath the squeegees 39. St the beginning of each printing stroke there is a constant " head " of liquid in each chamber 41, 42. As the stroke proceeds, colouring liquid flows from the leading chamber 41 or 42 through the stencil into the carpet. Simultaneously, the amount of suction exerted on each opening of the stencil from below is reduced as explained in Specification 895,706 and initial printing takes place under a substantially constant pressure difference. Printing further takes place in a second stage as the space 37 locating the nozzle 35 comes over each stencil opening. If desired, stencil printing with this application may be effected without the use of suction beneath the carpet.