GB888215A - Creasing apparatus, method and product - Google Patents

Abstract

888,215. Creasing box-blanks. INTERNATIONAL PAPER BOX MACHINE CO. March 6. 1959 [June 12, 1958], No. 7822/59. Class 100(2) A method of creasing paperboard to form adjoining, hingedly connected panels e.g. of a box-blank, comprises the steps of impressing a single, shallow furrow in one face of the paperboard along the centre line of the crease while simultaneously impressing a pair of shallow furrows in the opposite face of the paperboard, each laterally spaced from and parallel to the single furrow, and then continuing the pressure and deepening the furrows until the single furrow overlaps the pair of furrows and until the material of the paperboard located between the pair of furrows has been permanently stretched nearly to the point of fracture, thereby forming a compound crease consisting a double hinge. Opposed creaser bars 20, 21 are mounted so as to rotate in parallelism towards and away from the material to be creased; mechanism for effecting such rotation may be as described in Specification 876,331. The creaser bar 21 carries a single creaser blade 36 rigidly secured therein by set screws 39. The creaser bar 20 carries a pair of creaser blades 46, 47 which are mounted in lateral recesses on either side of a tapered central portion 53 of the bar. Pivot pins such as 62 carried by the portion 53 pass through holes in the blades 46, 47. The blades can pivot laterally between the tapered portion 53 and vertical cover plates 56, 57 which are fixed by bolts 58 to opposite sides of the bar 20. The blades are urged apart by coil springs such as 64 mounted in holes in the tapered portion 53 and their maximum divergence can be adjusted by means of a series of set screws such as 67, 68 which are threaded in the cover plates 56, 57. The effective height of the blade 36 above the upper face 42 of the bar 21 is substantially greater than the effective height of the blades 46, 47. As the bars 20, 21 are brought together to crease a blank 24 of corrugated paperboard the edges of the blades 36, 46, 47 frictionally engage the blank and form shallow furrows therein. As the creaser bars are brought to the position in which they are closest to each other, Fig. 5, the blades 46, 47 are caused to converge by reason of their frictional engagement with the blank and deep, overlapping furrows are formed in the blank. When the blank is formed into a box it may be folded about the crease through either 90 degrees, Fig. 9, or 180 degrees. The process is also applicable to laminated or pressed paperboard. In a modification of the apparatus the blades 46, 47 are replaced by blades of flexible resilient material such as spring metal.