EP0259433B1

EP0259433B1 - Improvement in the apparatus for carrying out cross perforations on a paper band

Info

Publication number: EP0259433B1
Application number: EP87901609A
Authority: EP
Inventors: Mauro Lenzi
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-02-03
Filing date: 1987-02-02
Publication date: 1992-12-02
Also published as: EP0259433A1; DE3782891D1; WO1987004658A1; IT1190473B; DE3782891T2; AU7027687A; IT8647614A0

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

The present invention relates to an apparatus for carrying out cross perforations on a paper band, as defined in the pre-characterising portion of Claim 1.
Such an apparatus is known from US-A-3 552 251
Presently, apparatus carrying out cross perforations 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.
In this field Document US-A-3 552 251 teaches a "Rotary slit cutter that comprises a rotary cylinder carrying knives, and a stationary fixed knife, the cutting edge of which is ground away or relieved except at those parts along its length where the web is to be slit. All of the rotary knives cooperate with the resulting intermittent edge of the single fixed knife. The knives are preferably helically mounted on the cylinder, and the cylinder and fixed knife are skewed at an angle such that the resulting slits are perpendicular to the long axis of the web.
This structure is unduly complicate since mounting a number of knives helically arranged on a cylinder surface is quite a difficult and time wasting operation. Furthermore the cooperating stationary fixed knife will hardly perform its function properly, at any rate the continous surface of the striking cylinder of this invention offers a much better action besides the important action performed for mounting helically into place the single plane blade of the invention, as described below.
The present invention seeks to eliminate these troubles and to provide on apparatus in which a single perforation blade is arranged as a cylindrical 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 to 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 a preferred embodiment of 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.

blade carrier cylinder

striking cylinder

system

cylinders

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 β 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 α equal to angle α' 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, perforation 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 β.
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 is the arrangement 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 synchronized 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

Apparatus (30) for carrying out cross perforations intended to help the tearing or folding of a continuous paper band (N) and adapted to be arranged in an operation line comprising a band unrolling spool (31), a punching machine (32) perforating side holes on the paper band, a first band driving machine (33), a setting device (34) regulating the position of the cross perforations with the position of the side holes, a main driving machine (35) and a user machine (36), said apparatus consisting of a cylinder (10) which carries a plurality of perforating elements (25) arranged along a cylindrical spiral path and an elongate striking element (11) adapted for coaction with said perforating elements (25) in producing the perforation action on the paper band (N) passing therebetween, and wherein:
- the axis of said cylinder (10) is so arranged as to form with the perpendicular to the centre line of said paper band (N) an angle (α)identical with the constant angle (α') that each tangent to said spiral path point by point forms with the generatrix of the cylinder (10) passing by said point;

- the striking element (11) is disposed at the same acute angle as the cylinder (10) axis such that the resulting perforations are perpendicular to the centre line of said paper band (N);
characterised in that
- the cylinder (10) is equipped with just a single blade (16) on the periphery (24) of which are disposed the perforating elements (25), said blade (16) consisting of an unique flat steel band received in a continuous groove formed on the cylinder surface (15) and following said cylindrical spiral path that has a constant and very long pitch, which blade (16) is provided with a toothed edge (24) and a number of parallel notches (22) disposed perpendicular to the opposite edge (23) and extending therefrom almost until said toothed edge (24);

- the striking element is a cylinder (11) arranged with its axis parallel to the axis of said cylinder (10) carrying said unique perforating blade (16);

- both the cylinder (10) carrying the perforating elements (25) and the striking cylinder (11) are rotatable mounted in opposite directions and disposed almost in contact with each other so as to provide the cross perforations during rotation of said cylinders (10,11);

- the cylinders (10,11) are rotatable at a speed of rotation which is synchronised with the traversing speed of the paper band (N).
The apparatus of Claim 1, wherein said striking cylinder (11) cooperates to force firmly into place said unique steel blade (16) previously loosely entered into said groove, when the blade (16) is to be put in place for operation or substitution.