GB2248828A - Bursting two webs of material - Google Patents

Abstract

A method for conveying two webs 14, 16 of material having equally spaced, successive transverse lines 15 of weakening and for separating the webs along the lines of weakening includes: first, positively feeding the two webs simultaneously through a pair of feed rollers 10, 12 with the two webs offset from each other by one half the distance between the lines of weakening, one of the feed rollers having a flat 22 extending across the portion of the length of the roller in contact with the web; second, feeding the two webs over a bursting element 24 oriented transverse to the longitudinal path; and third, feeding the two webs through a pair of burster rollers, 26, 28 rollers rotating at a speed greater than the speed of the feed rollers, whereby the webs are alternately and continuously burst. <IMAGE>

Description

METHOD AND APPARATUS FOR BURSTING TWO WEBS OF MATERIAL This invention relates to bursting apparatus-and more particularly to the separation (tearing) of two continuous webs of material along transverse lines of weakening.

Business forms are often preprinted on a continuous web of perforated material. Such forms are conventionally used in billing and other typical business transactions. The continuous series of forms require processing for end use, such as mailing, which may require bursting or separating the forms, as well as the performance of the end functions of stacking, stamping, sealing, inserting, collating (for additional enclosures) and folding. The aforesaid end functions are all provided for with existing equipment in one continuous process.

The bursting of the web is typically achieved with the use of two sets or pairs of rollers. The downstream rollers are made and arranged to be driven at a slightly higher speed than the upstream rollers, so that the web, when properly perforated, will separate. There is an additional element called a burst ball located between the two pairs of rollers which assists the separation process, especially if the two rollers are running at the same speed and the upstream rollers are momentarily stopped to permit the downstream rollers to continue feeding the desired, separated sheet.

In the interest of greater efficiency and throughput, attempts have been made to feed two webs through a single pair of upstream (feeding) rollers so that two webs could be handled and burst alternately. The webs were offset by half a pitch or length of sheet being burst. The mechanical arrangement was as described hereinabove regarding rollers and the bursting element. The result was that the web lying in contact with the upper feed (upstream) roller, i.e. the upper web, would creep out of position due to the geometric relationship of the web in bending about the feed roller at the entry area. This creep results in the perforation on the upper web not being in the correct position when that web arrived at the bursting roller, which prevents the upper web from bursting properly at the correct time.

Several attempts were made to eliminate the creep problem, including the use of an additional pair of feed rollers, and the use of flat areas on the feed rollers. It is critical that the perforations in the webs be positioned correctly over the bursting element or the desired separation will not be effected. None of the attempts to eliminate the creep proved successful, and none were able to properly position the perforations over the bursting element. The instant invention, however, has proven successful in overcoming the creep problems, and does not involve many of the complexities of the prior attempts and consistently positions the perforation over the bursting element.

Accordingly, the invention provides a method for conveying two webs of material having equally spaced, successive, transverse lines of weakening along a longitudinal path and for separating said webs along said transverse lines of weakening. The method comprises: first, feeding said two webs through a pair of upper and lower, vertically spaced feed rollers with said two webs offset from each other by one half the distance between the lines of weakening, one of said feed rollers having a flat extending across the portion of the length of said roller in contact with said web; second, feeding said two webs over a bursting element oriented transverse to said longitudinal path; and third, feeding said two webs through a pair of vertically spaced burster rollers, said burster rollers rotating at a speed greater than the speed of the feed rollers, whereby said webs are alternately and continuously burst by said burster rollers.

The invention will be better understood from the following non-limiting description of examples (an example) thereof given with reference to the accompanying drawings in which: Fig. 1 is a perspective view of an example of bursting apparatus employed in the invention, and shows the upper web being burst; Fig. 2 is similar to Fig. 1 but shows the lower web being burst; Fig. 3 is a side elevation view of the apparatus seen in Figs. 1 and 2 and shows creep in the upper web immediately prior to bursting; Fig. 4 is similar to Fig. 3 but shows the creep removed from the upper web as it is being burst; Fig. 5 is similar to Figs. 3 and 4 but shows the lower web being burst; Fig. 6 is an enlarged, side elevational view of the feeding rollers and webs seen in Fig. 3; Fig. 7 is an enlarged, side elevational view of the feeding rollers and webs seen in Fig. 4;; Fig. 8 is a front, elevational view of the feed rollers and webs seen in Figs. 1 and 2.

In describing the preferred embodiment of the instant invention, reference is made to the drawings wherein there is seen in Fig. 1 a pair of feed rollers 10 and 12 for feeding an upper web 14 and a lower web 16 of computer printout paper having transverse lines of weakening 15 defining separate sheets 17. The webs 14 and 16 initially include sprocket strips 18 on either side (see Figs. 1 and 2) which are engaged by a pair of six pin needle bearing tractors 20 which feed the webs 14 and 16 to the feed rollers 10 and 12. The upper feed roller 10 includes a flat 22 milled across the portion of the upper feed roller 10 which engages the webs 14 and 16, that is, the flat 22 extends across the roller 10 except for about 1/2 inch on each end of the roller 10. The functioning of the flat 22 will be explained in detail hereinbelow.Downstream of the tractors 20 are a pair of sprocket strip trimmers (not shown) for removing the sprocket strips 18 from the webs 14 and 16.

Situated downstream of the feed rollers 10 and 12 is a bursting cone 24. Downstream of the bursting cone 24 are a pair of bursting rollers 26 and 28, and located beneath the webs 14 and 16 between the feed rollers 10 and 12 and the bursting rollers 26 and 28 is a guide 30 for supporting the webs 14 and 16 when they are not gripped by both the feed rollers 10 and 12 and the bursting rollers 26 and 28.

The tractors 20, the sprocket strip trimmers and the feed rollers 10 and 12 are driven at the same linear speed by means of a stepper motor through a timing belt and pulleys (not shown). The bursting rollers 26 and 28 are driven by a d.c. motor preferably at twice the linear speed as the feed rollers 10 and 12.

To understand the operation of the foregoing apparatus, reference is initially made to Fig. 3, wherein it can be seen that creep or bulge 32 has appeared in the upper web 14 between the feed rollers 10 and 12 and the bursting cone 24. The lower web 16 has been burst and the upper web 14 is about to be burst, and the flat 22 is situated at the top of the feed roller 10. As the feed roller 10 continues its counterclockwise rotation, the flat 22 becomes situated at the bottom, as seen in Figs. 4 and 7, and the creep 32 seen in Figs. 3 and 6 is eliminated before the top web 14 is burst.

After the top web 14 is burst, the bottom web 16 is burst, as seen in Fig. 5, and the two webs 14 and 16 continue to be burst alternatively. The flat 22 allows each of the webs 14 and 16 to adjust each revolution of the feed roller 10 so that the creep 32, or any other bulges, regardless of their direction or orientation, can be removed.

In order to effect the desired alternate bursting of the two webs 14 and 16, the bottom web 16 is loaded into the tractors 20, after which the top web 14 is loaded into the tractors 20 a distance back from the bottom web 16 of one half the distance between the lines of weakening 15, i.e. the distance of a single sheet 17. By way of example, if the sheet 17 is 11 inches long, the lead edge of the top web 14 will be back 5.5 inches from the lead edge of the bottom web 16. When both webs' sprocket strips 18 are locked into the tractors 20, both webs 14 and 16 are jogged forward by the tractors 20 through the trimmers (not shown) which trim off the sprocket strips 18 which exit beneath the path of travel of the webs 14 and 16.The continued jogging forward of the webs 14 and 16 causes them to enter the nip of the feed rollers 10 and 12 and finally to a position between the feed rollers 10 and 12 and the bursting rollers 26 and 28.

Once the webs 14 and 16 are properly positioned, the feed rollers 10 and 12 are driven at a constant feed speed until the bottom web 16 enters the bursting rollers 26 and 28, which are moving at about twice the speed of the feed rollers 10 and 12, causing the web 16 to burst at the burst cone 24 into a single document 17 and the remaining web 16.

The top web 14, being half a pitch behind, will not burst until it is fed into the burst rollers 26 and 28. By this means, the top and bottom webs 14 and 16 will alternately burst as long as the system is energized. Neither of the webs 14 and 16 will creep ahead of the other because the tractors 20 keep them locked into position. Moreover, because the feed roller 10 is relieved (by means of the flat 22) each revolution, accumulation of one web relative to the other due to slight speed variation or slippage does not occur.

It will be understood by those skilled in the art that various modifications may be made without departing from the present invention.

Claims (10)

1. A method for conveying two webs of material having equally spaced, successive, transverse lines of weakening along a longitudinal path and for separating said webs along said transverse lines of weakening, comprising: first, positively feeding said two webs simultaneously through a pair of upper and lower, vertically spaced feed rollers with said two webs offset from each other by substantially one half the distance between the lines of weakening, one of said feed rollers having a flat extending across the portion of the length of said roller in contact with said web; second, feeding said two webs over a bursting element oriented transverse to said longitudinal path; and third, feeding said two webs through a pair of vertically spaced burster rollers, said burster rollers rotating at a speed greater than the speed of the feed rollers, whereby said webs are alternately and continuously burst by said burster rollers.

2. The method of claim 1, wherein said webs include sprocket strips and said feeding of said two webs through said feed rollers is effected by a tractor drive engaging said sprocket strips.

3. The method of claim 1 or 2, wherein said bursting element comprises a bursting cone.

4. The method of claim 1, 2 or 3, wherin the burster rollers are rotated at a speed substantially twice the speed of the feed rollers.

5. Apparatus for conveying two webs of material having equally spaced, successive, transverse lines of weakening along a longitudinal path and for separating said webs along said transverse lines of weakening, comprising: a pair of upper and lower, vertically spaced feed rollers through which are fed two webs simultaneously with said two webs offset from each other by substantially one half the distance between the lines of weakening, one of said feed rollers having a flat extending across the portion of the length of said roller in contact with said web; a bursting element oriented transverse to said longitudinal path over which said two webs are fed; and a pair of vertically spaced burster rollers through which said two webs are fed, said burster rollers being rotatable at a speed greater than the speed of the feed rollers, whereby in operation said webs are alternately and continuously burst by said burster rollers.

6. Apparatus according to claim 5, wherein said webs include sprocket strips and said feeding of said two webs through said feed rollers is effected by a tractor drive engaging said sprocket strips.

7. Apparatus according to claim 6, wherein said bursting element comprises a bursting cone.

8. Apparatus according to claim 7, including means to rotate the burster rollers at a speed substantially twice the speed of the feed rollers.

9. A method for bursting two webs substantially as herein described with reference to and as illustrated in the accompanying drawings.

10. Any novel combination or sub-combination of features disclosed and/or illustrated herein.