Method and Apparatus for Severing a Paper Web, Particularly Perforated Paper

The present invention relates to a method for severing a paper web by clamping and aligning the web and placing the web in tension.

The invention also concerns an apparatus for the implementation of the method.

The increase in the number of computer applications has an impact on the growing use of perforated paper. The paper is conventionally packed into bunches of fan-folded continuous forms with the paper being perforated at the folds. The paper is fed into a printing machine or printer, after which operation the web is cut into sheets of desired length appropriate with the application.

Up to now, the perforated paper has been ripped, for example, by manual methods without auxiliary tools. Cutting has also been effected using a serrated blade, having a width extending at least over the entire width of the paper web, against which the web is pressed manually or with a mechanical accessory. Alternatively, shearing devices are conventionally used, thereby achieving a neat cutting edge on an unperforated web.

A disadvantage of conventional technology is that the nonshearing severing devices do not always manage to cut the paper at a desired point, thus resulting in an unsatisfactory quality of the separated edge. Shearing devices are hampered by their complicated construction, which results in higher manufacturing and service costs.

The aim of the present invention is to overcome the disadvantages associated with the prior art technology and achieve a totally new kind of method and apparatus for severing a paper web.

The invention is based on severing the paper web, which is held by clamping means, with the help of tensioning exerted on the web by a severing means placed between the clamping means.

More specifically, the method in accordance with the invention is characterized by clamping the web with two clamping members to align it therebetween and tensioning the web by a tensioning member between the clamping members to separate the web at a perforation with the help of tensile stress.

Furthermore, the apparatus in accordance with the invention is characterized by two clamping members aligned transversely to the web movement direction, an anvil on the opposite side of the web from the clamping member, a tension means for severing the web and a backing bight.

The invention provides outstanding benefits.

The severing process in accordance with the invention results in an accurate separation of the web at the perforation, provided that the perforation line falls between the bounds of the clamping means. However, the distance between the clamping means is large allowing a wide latitude in the alignment of the web. The implementation of the invention requires no cutting blades nor mechanically wearing parts. Further, paper litter produced in a shearing operation is avoided. Moreover, the method is relatively quiet.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

The invention is next examined in detail with help of the following exemplifying embodiments illustrated in the attached drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a perspective view of a paper web severing apparatus in accordance with the invention;

FIG. 2 is a perspective view of a second paper web severing apparatus in accordance with the invention; and

FIG. 3 is a perspective view of third paper web severing apparatus in accordance with the invention.

Illustrated in FIG. 1 is a possible implementation of the severing apparatus. The apparatus comprises a plate-formed anvil 1, whose width extends at least over the width of a paper web 4. The upper surface of the anvil is essentially parallel with the web 4. The upper surface of the anvil 1 is designed to incorporate a channel aligned cross-wise to the direction of the paper web to accept a tensiong hose 2. Above the anvil 1 a pressing shoe 3 is positioned. The distance between the pressing shoe 3 and the web 4 is adjustable by actuator means (not shown). The width of the pressing shoe 3 is at least as wide as that of the web 4. The lower surface of the pressing shoe 3 has two clamping members 6, extending cross-wise over the web so that a backing bight 20 is formed between them. The clamping members 6 are placed to be appropriately spaced from the tensioning hose 2 and mate over their full length with the upper surface of the anvil 1 when the shoe 3 is pressed against the anvil. A proper distance between the tensioning hose 2 and the clamping member 6 is the diameter of the hose, for example. The distance may be varied from 0.5 to 1.5 times the hose diameter.

Severing operation of the web is effected in the apparatus by guiding the paper web 4 between the anvil 1 and the pressing shoe 3. The web 4 moves cyclically stepeed or in a continuous movement in the direction indicated by the arrow. When a desired perforation line 5 is aligned between the clamping members 6, the pressing shoe 3 is pushed down to mate with the anvil 1 so as to clamp the web to the anvil on either side of the tensioning hose 2 by means of the clamping members 6. Then, compressed air is, released by compressed air source 100 into the hose making the hose expand and exert tension on the web 4 causing the web to be severed at the perforation 5. The pressing shoe 3 is retracted upwardly, pressure is released from the hose, and the severed paper sheet is withdrawn with the help of a pulling device (not shown) while the feed of the paper web 4 is continued from the printer. Removal of the severed sheet may also be implemented with the help of an air jet or gravity.

In the embodiment illustrated in FIG. 2., an upper part 8 is permanently mounted above the anvil 1 carrying clamping hoses 7 on its lower surface with a comparable function as the clamping members 6 shown in FIG. 1. The placement of these clamping members is comparable to that of the clamping members 6 shown in FIG. 1. Correspondingly, this embodiment also provides a backing bight 21 formed between the clamping hoses 7. Severing is achieved by applying pressure to the clamping hoses 7 when the desired separation line 5 falls between the hoses, thereby clamping the paper web to the anvil 1 at both sides of the severing hose 2. An instantaneous pressurization of the severing hose 2 tensions the paper web causing its separation at the perforation 5. Then, pressure is released from the clamping hoses 7 to allow further feeding of the web.

In the embodiment illustrated in FIG. 3., the severing apparatus comprises a stationary upper part 9 having a wide compressed air hose 10 mounted in a channel extending over the web 4. The hose has two functional parts, namely clamping sections 11 at the rims of the hose 10 and a severing section 12 in the middle of the hose. A lower part 13 of the apparatus comprises backing bight 14, aligned to coincide with the severing section 12 with a width exceeding that of the severing section. When the hose 10 is pressurized, the clamping sections 11 press the web 4 against the lower part 13 while the severing section 12 performs a severing operation of the web while expanding down into the backing bight 14.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.