GB2089270A - Cutting device for transverse cutting of a paper web - Google Patents

Abstract

A cutting device for transverse cutting of a moving paper web (4), especially in front of a folding apparatus in a rotary printing machine, comprises a longitudinally slotted shaft somewhat longer than the width of the web (4) and rotatably mounted between walls of the printing machine, the shaft being capable of being traversed approximately in its rotational axis by the web approximately centrally of the slot (3). The shaft can be biassed by means of a torsion spring disposed at either or each of shaft end and can be blocked or disengaged, at a detent (11) fixed on one of the shaft journals, by a linkage (12) coupled with an electromagnet (13). On one side of the web (4) a cutting knife (2) is disposed with its cutting edge at a short distance from the shaft cylindrical surface and from the plane of the longitudinal side of the slot (3) which is towards the cutting knife (2). Opposite the cutting knife (2) and on the other side of the web (4), a deflector bar (15) is fixed parallel to the shaft.

Description

SPECIFICATION Cutting device for transverse cutting of a paper web The present invention relates to a cutting device for transverse cutting of a paper web, especially for paper folding apparatus in a rotary printing machine, in which due to restricted space availability, the installation of a paper cutting device is associated with considerable difficulties.

In folding apparatus, blockages, which particularly in a high-speed machine can lead to considerable damage, can occur for a wide variety of causes well-known to the specialist. A number of devices have therefore been devised for shutting down the machine and cutting the paper web immediately a fault is recognised, so as to prevent further running of paper into the folding apparatus. The cutting device should be disposed as close as possible to the folding apparatus in order that the paper end which continues to run in until the machine stops shall be short, in order not to unnecessarily aggravate the blockage which occurs.

Furthermore, trouble-free operation must be provided by the cutting device, as this really constitutes a safety device, in order that cutting of the paper web takes place with absolute reliability whenever a stoppage occurs.

For carrying out the further processing of the printed paper web, there are situated in close succession between a folding hopper and the folding apparatus a series of transporting, perforating and cutting rolls, so that it is not possible, without constructional compromises, to incorporate known cutting devices between these rolls. Afurthertech nical problem consists in reliably conducting away, without undue cost and complication, the paper web cut off by the cutting device, so that it cannot enter the folding apparatus.

A device for cutting a paper web ahead of folding apparatus has been disclosed in US-PS 4000888.

This device has the disadvantage that it requires a relatively large amount of space, so that if it were installed the distance between the folding hopper and the folding apparatus would have to be increased. A further disadvantage of the device is that it is of complicated and expensive construction. In particular, it has numerous moving parts which result in considerable wear and therefore adversely affect its operational life. The cutting knife striking the paper web requires a special guide in order to preventjamming and thus failure of the device at the time a blockage occurs.

In DE-PS 1 230 81 1, there is disclosed a cutting device having a striking knife. In this device, the aforementioned drawbacks, such as space demand, numerous moving parts and striking knife, are also present. In this case, the knife even strikes the running web without provision of any protection for the sharp cutting edge, which increases the risk of accident. Moreover, additional measures are necessary in order to conduct away from the folding apparatus the paper web, which is cut off but nevertheless still conveyed until the machine stops.

There is according/ya needfora sim,z7/e, uncom plicated and inexpensively manufactured cutting device for the transverse cutting of a moving paper web, the device being capable of installation in front of the majority of folding apparatus having good operational reliability. Such a device should prefer ably possess space-saving features, so that it can be installed even where space is limited. The risk of accident from a cutting knife and the possibility of jamming of the knife should be eliminated and the number of the components subjected to wear should be reduced. At the same time, it should be ensured that, without undue complication, the paper web continuing to run on until the machine stops should be prevented from entering associated folding apparatus.

According to the present invention there is pro vided a cutting device for transverse cutting of a paper web, the device comprising a shaft mountable for rotation relative to support means and provided with a longitudinal slot for passage of such web transversely through the shaft along a given path, resilient means for rotationally biassing the shaft relative to such support means, releasable holding means for holding the shaft against and releasing the shaft for rotation relative to the support means, a web cutting element arranged on one side of said path and provided with a cutting edge extending substantially parallel to the shaft and disposed adjacent to the shaft circumference and to the plane of the longitudinal slot wall closest to the cutting element, and a deflecting element arranged on the other side of said path to deflect a web portion cut by the cutting element.

In a preferred embodiment, the shaft is somewhat longer than the width of the paper web and is so positionable between the walls of a printing machine that the plane of the web lies approximately in the rotational axis of the shaft and centrally of the slot all around. The shaft can be biassed by means of a torsion spring disposed on either or each of the shaft journals and, in the biassed state, can be blocked or disengaged at a detent, which is fixed on one of the shaft journals, by means of a linkage coupled to an electromagnet.At one side of the web, the cutting element is a knife which is fixed parallel to the shaft between the machine walls and the cutting edge, depending on arrangement of the knife above or below the shaft, is at a short distance from the cylindrical surface of the shaft and from the plane of the longitudinal side of the slot situated on the side towards the knife.

A device embodying the invention as described above has the advantage that it essentially consists of two main components subjected to minimum wear, namely the slotted shaft traversed by the paper web and a fixedly mounted knife. Both of these components can, for example, by contrast to known cutting devices, be housed in the space encompassed by two roll pairs situated close together, without the necessity of adopting a spread out arrangement of these roll pairs. In operation, the knife remains stationary during the cutting operation and the web is impacted against the cutting edge and thereby severed, so that a special guide of the cutting knife h not neededanda isk of jammííog is removed.Also, the risk of accident is eliminated by the cutting edge resting almost on the cylindrical surface of the shaft and set back from the path of the web.

Opposite to the cutting knife and on the other side of the paper web, a deflecting bar is fixed parallel to the shaft and approximately in the same plane as the cutting edge of the cutting knife. Thus, without further means, the path to the lower rolls is blocked, when the device is triggered, by the surface of the cutting knife, by a portion of the cylindrical surface of the rotated shaft and by the surface of the deflector bar, so that the web continuing to run until the machine stops is deflected into a region where it cannot lead to damage.

Preferably, the or each torsion spring situated on a shaft journal is held at its one end by means, such as a ring or shoulder, fixed on the shaft and the other end is seated in means not rotatable with the shaft, for example in a bore in the machine wall.

Expediently, one of the shaft journals projects beyond its bearing position and is provided with a profile or engagement with a turning tool.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which Figure 1 is a sectional elevation, on theiine B-B of Figure 2, of a cutting device according to the said embodiment, Figure 2 is a sectional end view of the cutting device on the line A-A of Figure 1,with diagrammatic representation oftwo roll pairs, and Figure 3 is a diagrammatic view of further possible installation of the cutting device.

Referring now to the drawings, there is shown a cutting device which comprises two main components, a shaft 1 and a cutting knife 2. The shaft 1 is provided with a longitudinal slot 3 which is somewhat longer than the width of the paper sheet. The shaft 1 is rotatably mounted with its rotational axis capable of being traversed by a running paper web 4, between walls 5 of a printing machine in a seating mounting (not shown) or directly in the walls 5. In this arrangement, the planes of the two longitudinal sides of the slot 3 must, in the operating position of the shaft 1, lie parallel with and centrally about the plane of the web 4.Mounted on one shaft journal 6 or on each of the shaft journals 6 and 7 is a torsion spring 8, which is seated at one end in a ring 9 fixed on the shaft 1 and at its other end in a component (not shown), for example, the seating mounting, or in a bore lOin one of the machine walls 5. Fixed on the shaft journal 7 is a detent 11, which can be blocked and released by a linkage 12. The linkage 12 is coupled with an electromagnet 13 secured to the associated wall 5 or the seating mounting.

A cutting knife 2 is so arranged on one side of the web 4 and parallel to the shaft 1 that a cutting edge 14 thereof is situated either above or below the shaft 1 at a short distance from the shaft cylindrical surface (approximately 0.1 -1 mm) and from the plane of the longitudinal side of the slot 3 which is situated at the side towards the knife 2. An arrangement of the cutting edge 14 at larger distances from the aforementioned surfaces and planes is, of course, also possible, but with possible disadvantages to the operating speed of the cutting device.

Arranged opposite to the cutting knife 2 and on the other side of the web 4 and the shaft lisa deflector bar 15, which is fixed between the machine walls 5 in a manner analogous to the cutting knife 2 and is disposed approximately in the same plane as the cutting knife 2.

The cutting device can, without additional space being required, be incorporated in the space which in any case is free between the two roll pairs 16 and 17. It is, of course, also possible to incorporate the cutting device in front of other units of a rotary printing machine. In Figure 3, for example, use of the device in an offset printing machine in front of the printing cylinder is shown. In this application the cutting device could fulfil a further and indeed protective function, since it would replace the finger protection in front of the two pulling-in printing cylinders.

The shaft journal 6 projects beyonds its bearing 18 and is equipped with a profile 19 for coupling with a turning tool 20.

The cutting device is electrically connected with a monitoring device (not shown). For stressing, the shaft 1 is rotated by means of the tool 20 coupled with the profile 19 of the shaft journal 6, in opposition to the spring force of the torsion spring 8 until the linkage 12 lies in front of the detent 11, blocking the latter.

If the monitoring device detects a blockage, the electromagnet 13 is signalled and the linkage 12 is pulled up by the electromagnet. The shaft 1 rotates abruptly in the direction of the cutting knife 2. The paper web 4 passing through the longitudinal slot 3 is thereby struck against the cutting edge 14, which lies almost against the cylindrical surface, and is sheared through. Simultaneously, by the rotation of the shaft 1 through approximately 90" the access to the folding apparatusforthe paperweb,which runs until the machine stops, is blocked. The web is then conducted either to the right or to the left of the shaft by the cutting knife 2 or the deflector 15 and thus outside the folding apparatus.

Claims (8)

1. Acutting devicefortransverse cutting of a paper web, the device comprising a shaft mountable for rotation relative to support means and provided with a longitudinal slot for passage of such web transversely through the shaft along a given path, resilient means for rotationally biassing the shaft relative to such support means, releasable holding means for holding the shaft against and releasing the shaft for rotation relative to the support means, a web cutting element arranged on one side of said path and provided with a cutting edge extending substantially parallel to the shaft and disposed adjacent to the shaft circumference and to the plane of the longitudinal slot wall closest to the cutting element, and a deflecting element arranged on the other side of said path to deflect a web portion out by the cutting eiement.

2. A cutting device as claimed in claim 1, wherein said path extends substantially centrally between the slot walls and approximately across the shaft rotational axis.

3. A cutting device as claimed in either claim 1 or claim 2, the holding means comprising electromagnetically displaceable stop means engageable with abutment means provided at an axial end portion of the shaft.

4. A cutting device as claimed in any one of the preceding claims, the resilient means comprising torsion spring means arranged at at least one axial end portion of the shaft.

5. A cutting device as claimed in claim 4, the torsion spring means comprising a torsion spring connected at one end to means fixedly associated with the shaft and connectible at its other end to such support means.

6. A cutting device as claimed in any one of the preceding claims, wherein the shaft is provided at one axial end thereof with an extension adapted for engagement with means for rotating the shaft relative to such support means.

7. A cutting device for transverse cutting of paper web, the device being substantially as hereinbefore described with reference to the accompanying drawings.

8. A rotary printing machine comprising paper folding means and a cutting device as claimed in any one of the preceding claims arranged upstream of the folding means with respect to a direction of movement of a paper web into the folding means.