GB808244A - Apparatus for forming perforations in sheet material - Google Patents

Abstract

808,244. Perforating-apparatus. CRAMBON Ltd. Jan. 30, 1957 [Jan. 30, 1956], No. 3310/57. Class 31 (2). Apparatus for forming perforations in sheet material comprises a blade having a rectilinear edge and mounted for rotation about an axis lying in a plane parallel to the said edge, and a non-rotatable blade having a rectilinear edge and mounted with the said edge skew with respect to the other axis but lying in a plane parallel to the said axis, one of the blades having an interrupted edge and the other blade being a counter-blade having a continuous edge, and the blades being mounted so that upon rotation of the rotatable blade, they co-operate to exert a progressive shearing action along their length upon sheet material fed between the blades. As shown, a blade 11 having an interrupted edge is secured to a rotatably-mounted cylinder 10 and co-operates with a counter-blade 20 which has a continuous edge and is carried by a pivotallymounted lever 21 the free end of which is held against an adjustable stop 23 by means of a spring 22. The blade 11 is mounted so that its edge is skew with respect to the axis of the cylinder 10, and the blade 20 is mounted so that the edges of the blades 11, 20 are two distinct generatrices of the surface generated by the edge of the blade 11 during its rotation. An adjusting device 14 mounted in advance of the cylinder 10 enables the rows of perforations formed by the apparatus to be correctly located with respect to tensioning rollers 15, 16. Circular knives 17, 18 may be mounted after the cylinder 10 to divide the perforated web lengthwise. The means for feeding the web of material are coupled to the means for rotating the blade 11 in such a way that the rows of perforations extend perpendicularly to the direction of feed of the web. To vary the distance between adjacent rows of perforations, the means for rotating the blade 11 may incorporate transmission means comprising a system of elliptical gears.