IMPROVEMENT IN THE APPARATUS FOR CARRYING OUT CROSS PERFORATIONS ON A PAPER BAND

Abstract: A novel apparatus for carrying out cross perforations consisting of a pair of parallel cylinders (11, 18) rotating almost in contact with each other, one cylinder (18) carrying the perforation blade (16) arranged as a cylindrical spiral having a very long pitch and pressing during the rotation against the surface of the second cylinder (11) normally referred to as ''striking cylinder''.

Description: IMPROVEMENT IN THEAPPARATUS FOR CARRYING OUT CROSS PERFORATIONS ON A PAPER BAND■ The present invention relates to an improved apparatus for carrying out cross perforations on a paper band. Presently, apparatus carrying out cross perfo- rations necessary for the separation of the continuous paper bands in several sheets used in the paper machines consist of two parallel cylinders arranged with their axes perpendicular to the paper band. Both cylinders rotate almost in contact with each other in opposite directions so that their peripheries "accompany" the band passing therebetween. The surface of one cylinder, referred to as "blade carrier", is provided with at least a groove parallel to the axis of the cylinder, in which the perforation blade is locked by pressure, said blade striking the second cylinder, referred to as "striking cylinder" during the rotation of both cylinders so that the perforation of the paper band is carried out at a single blow and the form and the length thereof is equal to the edge of the blade. This operation, in the way it is carried out, provides troubles and causes very strong stresses in the components of the machine which, in turn, are causes of noise as well as considerable vibrations so that redundant constructions, very accurate processing and particular expedients are needed to achieve a good precision. The present invention seeks to eliminate these troubles and to provide an apparatus in which the perforation blade is not arranged along a generatrix of the blade carrier cylinder but it is placed as a cylin¬ drical spiral having a constant and very long pitch so that the contact between perforation blade and "striking cylinder" is continuous point by point from one end to the other end of the blade and is kept the time needed for the blade carrier cylinder to be rotated by an acute angle which is formed on the axis of the cylinder by both generatrices passing by the ends of the blade. In the same time the paper band traverses a length equal to the plane extension of the cylinder portion between the generatrices carrying the blade. The axes of the blade carrier cylinder and the striking cylinder are parallel to each other and can not obviously oriented perpendicular to the traversing direction of the band, but the direction of said axes forms with the direction of the perforations to be carried out, i.e. with such a direction perpendicular to the traversing direction of the band, an angle equal to the angle that the tangent to the cylindrical spiral along which the perforation blade is placed forms point by point with the corresponding generatrix. The arrangement along a cylindrical spiral of the perforation blade consisting of a plane steel band, one edge of which is provided with spaced perforation teeth, is made possible as a set of parallel notches which are perpendicular to the edges of the band and extend from the opposite edge of the toothed edge are formed in the band. For its assembling the blade is entered into the groove without first thrusting it, but then forcing it in its position with the striking cylinder, thus causing both cylinders to make a complete rotation. The apparatus according to the invention will be now described in detail with reference to the accompanying drawing, in which: Fig. 1 is a perspective, fragmentary view showing the apparatus of the invention; Fig. 2 is an elevation showing fragmentarily the perforation blade; Fig. 3 is a top view showing in reduced scale the arrangement of the device with respect to the band; and Fig. 4 is a general view of the apparatus between the paper unrolling and feeding devices. With reference to Figs. 1 to 4 the apparatus according to the invention consists essentially of a blade carrier cylinder 10, a striking cylinder 11, a support 12 of the cylinders, and motors or driving means 13 and a system 14 which synchronizes the speed of rotation of cylinders 10 and 12 with the traversing speed of band N. Blade carrier cylinder 10 carries at its cylindrical surface 15 a perforation blade 16 extending from the circular surface 18 to the opposite circular surface along a track shaped as a spiral with very long pitch having one end 19 on generatrix G1 and the other end 20 on generatrix G2. As shown, generatrixes G1 and G2 form an angle J having its apex on the axis of the cylinder, thus defining a surface portion b. As better seen in Fig. 3, a pair of cylinders 10, 11 are arranged so that their axes form with the direction perpendicular to the feed direction an angle o( equal to angle o( formed point by point by the tangent to the spiral and the generatrix of the cylinder passing by that point. With such an arrangement of cylinders, perfo- ration blade 16 comes in contact with band N "point by point" so that a straight perforation just perpendicular to the feed direction of the band can be achieved by a synchronization of the traversing speed of the band with . the speed of rotation of cylinders 10, 11. In other words it is needed to this end that band N moves along length A equal to the plane extension of the cylindrical surface b between generatrices G1 and G2 containing blade 16 in the time needed for cylinder 10 to rotate by angle j . Shown in Fig. 2 is the construction of blade 16 having parallel spaced notches 22 from edge 23 to the opposite edge 24 carrying perforation teeth 25. Such notches allow blade 16 to follow the path to take on its position. Schematically shown in Fig. 4 id the arrange¬ ment of the device according to the invention, generally designated by 30, with respect to paper band N and the several machines and apparatus operating therewith. Such machines and apparatus consist of an unrolling spool of the continuous paper band, designated by 31, a punching machine 32 to perforate side holes designed to allow the band to be fed by means of wheels or toothed members, first driving device of band N, designated by 33, a device 34 coupling the position of the cross perforations made by the apparatus according to the invention with the position of side holes made by punching machine 32, a main driving device for band N, designated by 35, and an user machine 36 which can be a winding frame or a laser printer and the like. As above mentioned the apparatus according to the invention has to carry out cross perforations correlated to the side perforations made by punching machine 32. Furthermore the speed of rotation of the rollers has to be such that in the time band N moves along a length A cylinder 10 rotates by an acute angle between generatrices G1 and G2, such length A being equal to the plane extension of cylindrical surface b between generatrices itself (Fig. 1). For this reason apparatus 30 according to the invention is provided with a known assembly, preferably of the electronic type, designated by 14, in order to be sinchronized both with punching machine 32 and driving devices 33 and 35. From what above it is self evident that the invention provides a device readily and effectively solving the problem of perforating continuous paper bands by avoiding undue stresses, vibrations and strikings.

Claims: CLAIMS 1. Improved apparatus for carrying out cross perforations for tearing or folding a continuous paper band and adapted to be arranged in an operation line comprising a band unrolling spool, a punching machine 5 perforating side holes on the paper band, a first band driving machine, a setting device regulating the position of the cross perforations with the position of the side holes, a main driving machine and an user machine, said apparatus '" consisting of a cylinder carrying the blade and a * 10 striking cylinder, both cylinders being placed almost in contact with each other and rotating in opposite directions with the paper band passing therebetween, characterized in that the blade carrying out the cross perforations is placed on the cylinder carrying the blade along a cylindrical 5 spiral path having a constant and very long pitch, and the axes of both cylinders form with the direction perpendicular to the traversing direction of the band an angle equal to the angle formed by the tangent to said cylindrical spiral point by point with the generatrix 0 of the cylinder carrying the blade passing by said point. 2. Improved apparatus according to claim 1, wherein said perforation blade has parallel spaced notches perpendicular to its edges and extending from the edge opposite that provided with teeth to an extent almost 5 equal to the width of the blade.

Inventors: LENZI MAURO, LENZI, MAURO
Applicants: LENZI MAURO, LENZI, MAURO
Application year: 1987
Main classification: B26F1
IPC codes: B26F1