GB620241A - Improvements in web cutting mechanism - Google Patents

Abstract

620,241. Cutting webs. WOOD NEWSPAPER MACHINERY CORPORATION. Jan. 10, 1947, No. 950. Convention date, March 9, 1946. [Class 31 (i)] In cutting paper webs in a printing press, the check pieces which are situated on either side of the knife and are movable parallel to the knife blade, are provided with means which cushion the final portion of their outward travel. The check pieces may themselves be constituted by a resilient material, e.g. rubber, in which case they need not be movably mounted. The cushioning device may comprise resilient pads, e.g. of rubber, or a hydraulic dashpot device. As shown in Fig. 1, the cutting cylinder 11 has a knife-box 12 containing a relatively fixed serrated knife 15 which co-operates with the cutting rubber 14 in the rotating cylinder 10 to sever the web 13. On either side of the knife are check woods 16 slidably mounted on guide rods and urged outwardly by springs 17; outward movement is limited by resilient pads 21 attached to the check woods and which abut against a shoulder 18 in the knife-box. In the example shown in Fig. 5, the check wood 16 is slidably mounted on guide pins and urged outwardly by springs 17 as in Fig. 1, but in this case the check wood is pivotally connected at 24 to a connected rod 23 for a piston 25 having hydraulic fluid on either side thereof. Initial outward movement of the piston and check wood is permitted freely, fluid flowing from 26 through comparatively large passages 28, 29, 30. Towards the end of its outward movement, the piston obscures passages 28 and the fluid passes through the restricted passage 31 to passages 29, 30, whereby the final outward movement is cushioned. Rapid inward movement is permitted by providing a spring-loaded ball-valve 34 which opens to permit fluid to flow through passages 33, 32 when the check wood 16 is moved in. In the form shown in Fig. 6, the movable check woods are replaced by fixed checks 35 of resilient material.