GB2217308A

GB2217308A - Continuous paper bursting

Info

Publication number: GB2217308A
Application number: GB8905940A
Authority: GB
Inventors: Tsuneo Shimizu
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-04-11
Filing date: 1989-03-15
Publication date: 1989-10-25
Also published as: GB8905940D0; IT1231351B; FR2629807A1; IT8947789A0; JPH01264800A; DE3911377A1

Abstract

Perforated continuous paper (10) is burst along a perforation (11) by means of the tension applied by the differential speeds of narrow infeed and outfeed rollers (7, 8) which are narrower than the width of the paper to create a pilot crack (12) at the portion of the perforation affected by the tension. A breaker blade (9) may be provided having its lower edge (9a) below the line joining the roller lips. <IMAGE>

Description

Continuous Paper Bursting This invention relates to a bursting mechanism for separating a continuous sheet of paper into smaller sheets. The long continuous sheet of paper has bursting cross-perforations, such as found in zig-zag fanfold paper for computers.

In general, existing bursting mechanisms use a pair of rollers which are at least as wide as the paper width. The speed of the outfeed roller is faster than the speed of the infeed roller which consequently creates tension on the full width of the paper.

Between the two rollers, a breaker mechanism such as a blade with a point is provided which inclines rearwardly from the point thereof. The point of the blade is so located as to strike the transverse perforation in the paper when tension is applied to the paper. At that moment, a pilot crack occurs on the perforation at the place where the point strikes the perforation. The full width tension, which is parallel to the paper path and the bottom of the bursting mechanism, widens the pilot crack in the direction of the paper width along the perforation and finally the paper is burst along the perforation.

Existing machines essentially need full paper width tension to finish the bursting. However, when certain materials, such as an elastic material or very thin paper, are to be burst, at the very beginning of the process tension by full width rollers is applied both at the marginal and central regions. However, the marginal tension portions receive maximum tension whereas the centre tension portion of the paper receives minimum tension. In the case of computer continuous paper which has sprocket holes or longitudinal glue lines at the marginal edges, these materials will bubble and tend to push the rollers against the pressure. Consequently, the tension which must be activated at the centre of the paper is reduced considerably so that it is difficult for a pilot crack to appear at that point.

At the same time, the rollers receive a bending moment at the centre and since they tend to bend there, further reduction of tension at that point occurs. To avoid this, current technology has resorted to large diameter rollers which inhibits against possible reduction in machine size. Furthermore, since current mechanisms pull the paper with a uniform tension across its full width at the time that the pilot crack is formed, the rollers require high power an thus need a large power source. This means that the parts of these existing mechanisms must have durability for the large power sources. As a result, existing mechanisms are expensive.

Moreover, the high power now required for the full roller width permits almost no slip to the paper between the rollers. Hence, the perforation and the outfeed roller position must be adjusted very precisely together since, when the paper is under tension by the infeed and outfeed rollers, the perforation must be just under the breaker blade. If the parts are not in these precise positions with the tension at a very high level, the paper is either torn irregularly rather than at the perforation, or, because of slippage between the paper and the rollers, deformation such as wrinkles occur on the paper. In either case, correct bursting cannot be accomplished.

According to one aspect of the present invention, a method of bursting perforated continuous paper along a perforation comprises applying tension to the paper in width less that the width of the paper, creating a pilot crack at the portion of the perforation affected by the tension and applying the tension continuously in an outside direction of the paper width to burst the remaining perforation successively.

According to another aspect of the present invention, a bursting mechanism to burst a perforation on a sheet comprises an infeed roller and an outfeed roller, the outfeed roller being arranged to rotate at a higher peripheral speed than the infeed roller in order to give a tension to the paper at the perforation, the rollers being narrower in width than the width of the sheet whereby tension is applied to an area narrower than the width of the sheet.

Thus in accordance with the invention, there is used a narrow width tension on the paper rather than a full width tension. The narrow width tension is applied at the cross-perforation to permit bursting of the perforation. In addition, a convex bursting means may be used to touch the tensed part of the paper to concentrate the tension at the touching point in order to burst the perforation.

Using the method and mechanism stated above, and described more fully hereinafter, the mechanism of the present invention is available to form a pilot crack at a lower power compared with existing mechanism. After the pilot crack is formed, it is transferred successively from both ends of the pilot crack to both edges of the paper along the perforation. The bursting power is not concentrated in a moment but gradually to the full width of the paper. With this mechanism, if, for some reason, the paper is given a strong enough tension to tear the paper at a point other than at the perforation, the small tension rollers allow slippage between the paper and the rollers to prevent tearing the paper along a path other than the perforation.

Moreover, when a breaker blade or small roller touches the tensed portion of the paper, the stress makes a tension concentration at the touching point so that as soon as the perforation comes to the breaker blade the pilot crack occurs.

The invention may be carried into practice in various ways but one burster mechanism embodying the invention will now be described and explained by contrast with a current mechanism which will also be described. The mechanisms are shown in the accompanying drawings, in which: Figs. 1, 2 and 3 are diagrammatic views showing the mechanism embodying the invention in perspective, top and side views, respectively; Figs. 4 and 5 are schematic views showing contrasting stress diagrams on the paper by, respectively, the current mechanisms shown in Figs. 6, 7 and 8 and the mechanism embodying the invention and shown in Figs. 1, 2 and 3; and Figs. 6, 7 and 8 are diagrammatic views similar to Figs. 1, 2 and 3 but showing the current mechanism.

Referring first to Figs. 6, 7 and 8, there show an existing bursting mechanism. This unit has a set of rollers comprising two pairs 1 and 2, all of the rollers being as wide as the paper width. The feed or peripheral speed of the outfeed rollers 2 is faster than the peripheral speed of the infeed rollers 1 and, consequently, a tension is created on the paper across its full width.

Between the rollers 1 and 2, there is a breaker blade 3 the lower edges 3b of which incline downwardly to a point 3a and which also inclines rearwardly away from the point 3a. The point 3a of the blade 3 is so located as to strike the perforation 5 of the paper 4 at that point only when the tension is applied to the paper and, at the moment, a pilot crack occurs in the perforation 5. Full width tension parallel to the paper path etnd the reaction from the bottom edge 3b widens the pilot crack to the paper width along the perforation and finally the paper is burst full width.

By contrast, in the mechanism constructed in accordance with the present invention and illustrated in Figs. 1, 2 and 3, the infeed rollers 7 and outfeed rollers 8 which generate the paper tension are made of narrow width (about 1 cm width is preferable) compared to the paper 10. The rollers 7 and 8 apply different pressures to each other, the outfeed rollers 8 applying more pressure than the infeed rollers 7. These different pressures and roller friction coefficient are enough to hold the paper in place.

The paper 10 has bursting cross perforations 11 located in a certain longitudinal distance from each other. It is fed manually or by some other method (unshown) to the rollers 7 and 8 which are in alignment with each other. A breaker blade 9 which is of approximately the same width as the rollers 7, 8 is located between the rollers with its bottom edge 9a located under the line joining the nips of the infeed rollers 7 and the outfeed rollers 8, i.e., under the tensed paper 10 line. The lower edge of the blade 9 is convex and tapers to a rounded point. The blade 9 could be replaced by a small roller. The front side 9b of the blade 9 inclines leftwards and downwards as seen in Figure 3, i.e. downwards and in the paper feeding direction. The rollers 7 and 8 are in alignment with each other but need not necessarily be located at the centre of the paper 10.The distance between the outfeed roller 8 and the blade 9 should preferably be adjusted to be almost the same as the length from the paper top (leading edge) to the perforation 11 but could be set a shorter distance. A guide 19 located below the paper path and between the infeed and outfeed rollers 7, 8 is proved to guide the paper 10 whose top, or leading edge, is fed by the infeed roller set 7 and under the blade 9 and to lead it into the outfeed roller 8. The blade 9 can be eliminated if thin enough paper is selected.

Fig. 4 shows tensile stress pattern for the paper by existing mechanism and Fig. 5 shows tensile stress pattern produced by the mechanism shown in Figures 1, 2 and 3. The arrows show by their lengths and direction the amount and direction of the stress. Existing mechanisms cause small amounts of tensile stress at the centre of the paper. Consequently if the centre needs a greater tension, greater force must be applied over the whole length of the rollers. However, with the present invention, the stress occurs only at the centre of the paper where the rollers 7 and 9 are located and almost no stress occurs at the other parts of the paper. Dash arrows in Fig. 5 show the power direction after the pilot crack has been created, as will be explained more fully hereinafter.

Referring to Figs. 1 to 3, which shows a bursting process according to this invention, the top or leading edge of the paper 10 is pinched by the infeed roller 7 and goes through under the blade 9 guided by the front side 9b of the blade. It reaches the outfeed roller 8 along the guide 19. As the peripheral or paper feed speed of the out feed roller 8 is greater than that of the aligned infeed roller 7, when the paper is pinched by roller 8 a tension is created on the paper immediately. As the width of the rollers 7 and 8 is narrower than the paper width and they are in alignment with each other, tension is created along the longitudinal roller line between rollers 7 and 8. The perforation 11 on the paper 10 to which the tension has been applied forms a pilot crack 12 where it touches the blade 9 at the point where stress is concentrated.

The tension by the rollers 7 and 8 apply more stress to the pilot crack 12 to tear and enlarge the crack successively along the perforation 11. This tearing force permits full width bursting of the perforation 11 and completes the separation before the perforation 11 reaches the outfeed roller 8. Both rollers 7 and 8 are stated to be of the same narrow width but one pair of rollers may be narrower than the other pair, if desired, without departing from the invention.

As stated above, this invention permits the power used to rotate the rollers to be relatively small, which gives mechanical advantages and, since the blade timing for striking the perforation is not necessarily critical, even if the paper thickness is different, easy operation is accomplished. Hence, the machine size can be small.

Claims

Claims:

1. A method of bursting perforated continuous paper along a perforation comprising applying tension to the paper in a width less than the width of the paper, creating a pilot crack at the portion of the perforation affected by the tension and applying the tension continuously in an outside direction of the paper width to burst the remaining perforation successively.

2. A method as claimed in claim 1 in which the tension is applied along an area longitudinal of the paper feed.

3. A method as claimed in claim 1 or claim 2 in which the tension is applied along a narrow width relative to the paper width.

4. A method as claimed in claim 1 or claim 2 or claim 3 in which the tension is applied centrally of the width of the paper.

5. A bursting mechanism to burst a perforation on a sheet which comprises an in feed roller and an out feed roller, the outfeed roller being arranged to rotate at a higher peripheral speed than the in feed roller in order to give a tension to the paper at the perforation, the rollers being narrower in width than the width of the sheet whereby tension is applied to an area narrower that the width of the sheet.

6. A mechanism as claimed in claim 5 which includes crack-forming means to concentrate the tension at the point it touches the perforation to create a pilot crack on the sheet at the perforation.

7. A mechanism as claimed in claim 6 in which the crack-forming means comprises a breaker blade.

8. A mechanism as claimed in claim 7 in which the breaker blade is inclined in the paper feed direction.

9. A mechanism as claimed in claim 7 or claim 8 which includes a guide on the face opposite the face where the blade is located.

10. A mechanism as claimed in any of claims 6 to 9 in which the two rollers are substantially the same width.

11. A mechanism as claimed in any of claims 6 to 10 in which the two rollers are centrally located with respect to the width of the paper.

12. A mechanism as claimed in any of claims 6 to 11 in which the rollers are of approximately the same diametric size.

13. A method of bursting perforated continuous paper substantially as described herein with reference to Figures 1, 2, 3 and 5 of the accompanying drawings.

14. A bursting mechanism substantially as described herein with reference to Figures 1, 2, 3 and 5 of the accompanying drawings.