GB776369A - Improved press knife and method of making the same - Google Patents

Abstract

776,369. Moulding cutting tools. ART PATTERN & KNIFE CO., Ltd. and HAINES, G. W. Aug. 9, 1955 [Sept. 27, 1954], No. 27838/54. Class 87(2). [Also in Group VIII] A cutting die comprises a metallic knife of endless form having a single cutting edge and a comparatively wide back edge with spaced protrusions thereon or spaced formations therein and a homogeneous carrier body surmounting the knife and united thereto, the carrier body consisting of a hollow deep back having the same inner and outer contour as the knife and moulded in a reinforced plastic material in which the spaced protrusions are embedded, or which keys with the formations in the back edge of the knife. As shown in Figs. 1 and 2, the knife 1 is surmounted by a hollow carrier body 2 the upper face of which is preferably protected by means of a metal strip 3. The carrier body has at least one safety band 4 which may be moulded integrally therewith or attached thereto. The back edge of the knife is knurled at 5 and has screws 6 for bonding to the carrier body. The latter is preferably moulded in a reinforced plastic e.g. polyester resin reinforced by glass fibre. To make the cutting die shown, a wooden or other mould comprising an outer part 7, Fig. 6, and a core 9 spaced therefrom to form a cavity 10 has the core fastened to the base 18 of a jig J and the outer part 7 clamped upon the base 18 by means of bars 19 and associated bolts 20 and nuts 21. If a metal strip 3 is to be provided this is first located in the cavity 10 and the latter is then filled with resin-impregnated pieces 23 of glass fibre. The knife is then placed in position on top of the plastic with its cutting edge 1a upwards, Fig. 8, and a plate 24, Fig. 9, placed thereon, the plate being forced downwardly by means of apertured bars 25 which are engaged over the upper ends of the bolts 20 and tightened down by further nuts 26, depth blocks 27 being interposed between the plate 24 and the base 18 of the jig. The complete mould incorporating the cutting die is removed from the jig and placed upon supports in a machine, Fig. 10 (not shown), provided with a rammer which forces the mould core downwardly out of the cutting die. Finally, the outer mould part is split away from the cutting die. When the mould is of wood, the parts 7, 9 thereof are made from a solid block by first marking the upper face thereof with suitably contoured spaced lines produced with the aid of a hollow templet, and then causing a band saw, after making an initial cut 11, to follow these lines and thereby cut out the core 9 and form in the block a larger but correspondingly-shaped opening. The separated portions at opposite sides of the cut 11 are connected by elements 12.