GB1112978A - Apparatus for stencil-printing thick fabrics - Google Patents

Abstract

1,112,978. Stencilling apparatus. BRADFORD DYERS ASSOCIATION Ltd. 18 July, 1966 [21 July, 1965], No. 31064/65. Heading B6C. [Also in Division F2] In apparatus for printing on a thick fabric by the application of free-flowing colouring matter through a stencil to the fabric whilst the fabric is on a perforated support forming the top of a suction box, a valve such as 14, Fig. 4, is provided in the side of the suction box so as to be subject to the suction in the box on one face, i.e. to the left, Fig. 4, and to atmospheric pressure on the other face, i.e. to the right, Fig. 4, and yielding means hold the valve on its seat so that the valve opens when the suction reaches a predetermined value to maintain the suction in the box constant. The yielding means may be a spring, or a piston-and-cylinder subjected to air pressure, and the valve may be a flatplate coacting with an annular seating. As shown, however, the valve 14 is frusto-conical and is connected by a rod 15 and ball joints to a lever member 44. The member 44 has one pivot 52 engaging a forked end of a bracket 51 and connected to a piston 49 of a cylinder 48. A second pivot at the lower end of the member 44 is movable in slots 46 in a bracket 45 and is connected to the piston 42 of a smaller cylinder 41. When a low suction is required in the suction box, high-pressure air is supplied to the right-hand side of the piston 49 so as to maintain the pivot 52 on a leftward position. Air at a predetermined low pressure is supplied to the right-hand side of piston 42. When so set, the valve 14 opens when the suction on the valve 14 plus atmospheric pressure exceeds the closing force exerted by the piston 42. For a higher suction, high-pressure air is supplied to the left-hand side of the piston 42 so that the lower end of the member 44 is moved to its rightward position and the member pivots about that end. Compressed air at a low pressure is supplied to the left-hand side of piston 49 so that opening of the valve 14 takes place against the air pressure exerted on that piston. In another arrangement, Fig. 2 (not shown), a lever corresponding to member 44 is movable about a fixed pivot, and at a part extending below the pivot is connected to two piston rods. Compressed air at a predetermined pressure is supplied to a cylinder associated with one of the piston rods for low vacuum working, and is supplied to both cylinders for a higher vacuum working.