WO2002016243A2

WO2002016243A2 - Continuous web input guillotine cutter

Info

Publication number: WO2002016243A2
Application number: PCT/US2001/023824
Authority: WO
Inventors: Roger A. Jacques
Original assignee: Moore North America, Inc.
Priority date: 2000-08-24
Filing date: 2001-07-27
Publication date: 2002-02-28
Also published as: WO2002016243A3; AU2001280877A1

Abstract

A buckle gap (G) is defined by first and second web guide assemblies (18, 20) upstream of the guillotine knife (38), so that a controlled buckle can form upstream of the knife (38) when the web is stopped as a part of the knife downstroke. The buckle gap (G) is defined at least in part by an adjustable guide (18, 20) so that a controlled area for web buckling can be defined to take up an appropriate amount of web material during the cutting portion of the cycle. After the cutting operation, once the knife (38) has cleared the anvil (60), the web is released to be fed past the knife (38). To ensure feed of the accumulated buckle of web material, pull rolls (40) are provided to pull the web forward to substantially remove the buckle before the next cut cycle.

Description

CONTINUOUS WEB INPUT GUILLOTINE CUTTER

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a guillotine cutter and, more specifically, to a web cutting system for cutting a continuously fed web by periodically stopping the web for cutting in the vicinity of the cutter without stopping the web input device.

Typical guillotine type cutters, particularly in the paper processing industry, index the web one sheet length then activate the knife stroke to sever the web into cut sheets of a prescribed size. Such stop-start action limits the manufacturing speed that may be achieved with the system and limits the choices of web input devices.

It has been proposed, in various web feeding and cutting systems, to cut a sheet from a continuously fed strip of web material by engaging the web with a suitable stop and cutting the web with a reciprocating cutter. The web thus remains stationary at the cutting station during the cutting operation while a slack hump or buckle forms upstream of the cutting station.

There have been problems, however, ensuring that the slack hump or buckle of web material will be created at a predetermined location and can be accommodated in a controlled manner, particularly in a system where the web feed speed may be changed from time to time to accommodate different sheet lengths. If the feed speed of the web material is high, then the buckle, if not properly accommodated, will get out of control so that after the cutting operation, the web may misfeed and jam the feed mechanism.

Thus, it was an object of the invention to provide a novel control mechanism for controlling at least one of the location and size of the slack hump or buckle thereby to ensure a desired intermittent buckle formation, to ensure that the buckle will not get out of control at any time during web processing, and to ensure that a sufficient length of web material will be fed to the cutting station between cutting intervals.

In an embodiment of the invention, a buckle gap is defined upstream of the guillotine knife so that a controlled buckle can form upstream of the knife when the web is stopped as a part of the knife downstroke. The buckle gap is defined at least in part by an adjustable guide so that a controlled area for web buckling can be defined to take up an appropriate amount of web material during the cutting portion of the cycle. After the cutting operation, once the knife has cleared the anvil, the web is released to be fed past the knife. To ensure feed of the accumulated buckle of web material, pull rolls are provided to pull the web forward to remove the buckle before the next cut cycle.

It is a further object of the invention to provide for a controlled buckle gap that the location of the buckle can be determined with respect to the web feed path. The foregoing object is realized in accordance with the preferred embodiment of the invention by defining the buckle gap with both upstream and downstream adjustable guides, so that the location of the buckle gap with respect to the cutter as well as its formation area can be determined.

BRIEF DESCRIPTION OF THE DRAWINGS

These, as well as other objects and advantages of this invention, will be more completely understood and appreciated by careful study of the following more detailed description of the presently preferred exemplary embodiments of the invention taken in conjunction with the accompanying drawings, in which: FIGURE 1 is a schematic elevational view of a continuous input web guillotine cutter embodying the invention;

FIGURE 2 schematically illustrates the buckle loop parameters according to the invention;

FIGURE 3A is a schematic elevational view of the knife and snubber bar in the knife up position; and

FIGURE 3B is a schematic elevational view of the knife and snubber at the knife down position.

DETAILED DESCRIPTION OF THE INVENTION

FIGURE 1 schematically illustrates a continuous web input guillotine cutter system in accordance with an embodiment of the invention. As illustrated, the web 10 is taken up in a conventional manner with the aid of feed tractors schematically illustrated at 12, from which the web is fed to margin slitters 14 for severing the perforated edges of the web. Web feed rolls schematically illustrated at 16 provide positive web feed and control at the entry to the infeed guide 18, described below, to ensure that the web is positively fed, ultimately to the cutting station 24, and to ensure that the buckle occurs in the controlled space G formed between the guides 18,20.

Below the guides 18,20, a lower web support plate 22 is formed to define with the guides, the feed path for the web 10 from the feed rolls 16 to the knife of the cutting station 24. A snubber bar 36 is provided for stopping the web 10 before the knife 38 reaches the cut point during its downstroke and for releasing the web after the knife opens on the upstroke, as described in greater detail below. In the illustrated embodiment, the snubber bar 36 is operatively mounted to the upstream side of the reciprocating guillotine knife. While the snubber bar engages the web, a buckle forms in the web upstream thereof. In the illustrated embodiment, the buckle naturally forms in the gap G defined by guides 18,20.

To allow the buckle gap to be adjusted to determine the size thereof, at least one of the buckle guides 18,20 is adjustable to determine a buckle gap size to accommodate the buckle upstream of the cutting station 24. In accordance with the presently preferred embodiment of the invention, both the size and location of the buckle relative to the cutting station are desirably adjustable and determinable to minimize the risk of collapse of the buckle and potential jamming of the web feed and/or damage to the web.

One or both buckle guides can be made adjustable in any one of a number of ways. For example, one or both buckle guides could be supported by an adjustable support structure disposed to the side of the web path or adjustably coupled to the lower web support plate. With such an adjustable guide, a part of or the entire guide may be displaced toward or away from the cutting station 24 to control the size of the buckle gap G. In a preferred embodiment of the invention, an adjustable guide assembly is provided that includes a fixed guide 26,28 which is disposed in a predetermined location relative to the feed rolls 16, the lower web support plate 22, and cutting station 24 and an adjustable guide 30,32 adjustably mounted to the fixed guide 26,28. Providing the adjustable guide assembly 18,20 as a two or more part assembly, as illustrated, has the advantage that the location of the fixed guide is determined with respect to infeed rolls, the lower web support plate, and the cutting station, to ensure proper feed of the web to the vicinity of the buckle gap and ultimately to the cutting station.

Thus, in the preferred embodiment, provided in opposed facing relation to the lower web support plate 22 is a first, fixed guide 26 defining an inlet for the continuously fed web 10. Mounted to the fixed guide 26 is a first, upstream adjustable guide 30. Guide 30 is adjustably mounted to the fixed guide 26 so that it can be displaced towards or away from the knife thereby to define an upstream limit of the controlled buckle to be formed. In the illustrated embodiment, the adjustable guide 30 has, e.g., a slot and is provided with a suitable locking knob 34 so that when the locking knob is loosened, the adjustable guide 30 can be slid in an upstream or downstream direction and then the lock knob rotated to lock the adjustable guide 30 with respect to the fixed guide 26. In the alternative to a continuous slide adjustment, a series of apertures can be defined in the adjustable guide and/or the fixed guide through which the lock knob is selectively disposed to lock the adjustable guide in a prescribed position with respect to the fixed guide. Other adjustment mechanisms for adjusting the disposition of the adjustable guide relative to the fixed guide are known and could be used without departing from the invention.

According to my original concept, I provided only an upstream adjustable guide, as described above, to vary the buckle gap, so that a controlled buckle area, sized to the cut length was possible. With e.g., roll fed media, this provided desirable web control for consistent operation without web jams. As a result of further testing and analysis, however, I recognized that additional control is appropriate for handling certain media, such as folded and cross perforated media as opposed to roll fed media.

More particularly, as originally proposed, the continuous web input guillotine cutter of the invention was developed for offline applications, running boxed forms with prefolded cross-perforations. I realized that control of the buckle gap location in such an application is important. If a fold perforation is allowed to be disposed in the buckle area when the web is stopped to be cut, the buckle may fold at the perforation and collapse. Depending upon where this occurs, the folded portion can jam in the throat of the buckle guide just ahead of the snubber 36 or at the entry to the snubber. To minimize the risk of folding of the buckle in the buckle gap and/or the potential for jamming the system, in accordance with the preferred embodiment, the downstream guide 20 which I originally proposed to provide as a fixed guide has been made adjustable. This allows both the upper guides 30,32 to be adjusted to determine the location of the buckle area relative to the web and to the cutter, to be certain that in any selected cutting operation, no perforation or other less stable portion of the web 10 is disposed in the buckle gap. By providing both upstream and downstream adjustable guides 18,20, not only the gap for formation of the buckle can be controlled, but its location relative to the fed web can be controlled so as to minimize the potential for web jams and to minimize the potential for collapse and/or damage of the web material.

On the downstream end of the buckle gap, a second fixed guide 28 and second adjustable guide 32 are provided as explained above. The second adjustable guide 32 is mounted so as to be selectively displaceable relative to the second fixed guide 28 to determine the downstream limit of the buckle gap, whereupon the adjustable guide is locked to the fixed guide to determine the buckle gap with the first adjustable guide 30. The adjustable guide 32 may be adjustable relative to the fixed guide 30 in any suitable manner, as was described above with respect to the upstream guide 18.

Typical parameters for the buckle gap and loop are based on the approximation that the loop is a circular segment with a height less than the radius (for better control). The buckle loop parameters are shown in FIGURE 2. The buckle gap parameters in FIGURE 2 are

h = loop height; (For θ = 75°, h = .74r) y = web C/L height above loop circle center θ = angle of circle arc from vertical to web C/L r = loop radius

G = loop area gap (width of opening for buckle length at web C/L)

LT = total loop segment length

Knife cycle parameters in FIGURES 3A and 3B are:

KT = total length of knife stroke, up to down

Kc = length of knife stroke from cut C/L to down

Ks = distance from blade edge to bottom of snubber bar

During the cut downstroke the snubber bar 36 hits the web 10 first and then the blade of the knife 38 cuts the web. On the upstroke the knife blade clears the web C/L, first, followed by the snubber bar, thereby releasing the web. The web 10 will be stopped during the portion of the cycle that the snubber is in contact with the web:

STOP CYCLE = ^{Ks + Kc} = .2, forK_T = 1, K_c = .1, K_s = .1

The length of the buckle loop, L_τ, is the length of web in the gap, G, plus the amount of web travel while stopped to cut, LB, the buckle length:

L_τ = L_B + G, or G = L_τ - L_B

A complete knife cycle is one cut length L. The buckle length is the portion of the cycle that the web is stopped.

L_B = .2 L For θ = 75°: L_τ = 1.37 G Substitution yields:

G = .54 L

L_τ = .74L

The gap required and related parameters for a typical range of cut sheet lengths are:

In the illustrated embodiment, pull rolls 40 are disposed in the vicinity of the downstream fixed guide 28 to positively feed the web buckle after the web has been severed and the snubber bar 36 raised. In the presently preferred embodiment, the pull rolls 40 are rotated so as to rotate at an overspeed relative to the web feed speed. Moreover, the pull roll assembly is preferably operatively coupled, for example, to the reciprocating knife assembly so that the rolls are lifted out of contact with the web during the cutting down stroke and are lowered to positively feed the buckled web after the cut has been achieved. As noted above, the pull rolls 40 are disengaged from the web 10 while the web is stopped for the cutting operation and reengaged to ensure proper web feed to the cutting station 24 for a subsequent cutting operation by sufficiently reducing or eliminating the buckle for smooth operation. To provide for appropriate timing of engagement of the pull rolls relative to the knife cutting operation, the pull rolls are advantageously linked to the knife cycle. By way of example, the pull rolls are pivotally mounted to a suitable lateral support structure (not shown in detail) and spring biased into engagement with the web. A suitable cam or engagement projection 42 is provided on the knife assembly so that as the knife strokes downwardly, a free end of the pull roll support assembly is engaged to pivot the pull rolls relative to pivot pin 44 to thus lift the pull rolls out of contact with the web. Upon lifting of the knife assembly, engagement with the distal end of the pull roll arm 46 is released or reduced and due to the spring biased action, the pull rolls are again engaged with the web to effect the positive feed noted above.

With reference to FIGURES 3A and 3B, the snubber bar 36 for stopping web feed during the cutting operation and the knife 38 for severing the web are schematically illustrated. As noted above, the snubber bar is mounted so as to move generally with the knife up and down strokes but is displaced relative to the knife upon contact with the web 10 so as to hold the web 10 but not damage the web during the knife cutting operation.

When the knife and snubber bar are disposed in the knife up position, as illustrated in FIGURE 3A, the snubber bar 36 bottom or lower end 48 extends downwardly beyond the cutting edge 50 of the knife 38 by a distance Ks. As the knife assembly is lowered towards the web, the snubber bar 36 will engage the web in advance of the knife to stop its forward feed through the cutting station. As the downward displacement of the knife continues, the knife moves downwardly while the snubber bar remains vertically stationary, pressed against the web as illustrated in FIGURE 3B. Once the cutting operation has been completed and the knife is retracted upwardly, past the cut edge of the web, the snubber bar is also lifted upwardly out of contact with the web to the position shown in FIGURE 3A.

As described above, the snubber bar 36 is supported relative to the knife so as to initially project by a predetermined amount Ks beyond the cutting edge of the knife. Preferably the amount that the snubber bar projects can be adjusted. In the illustrated embodiment, an adjustment screw or bolt 52 is inserted through a suitable aperture therefor defined in a support 54 projecting from the knife component 38 and threaded into the top end of the snubber bar 36. Engagement of the enlarged head 56 of the adjustment bolt 52 with the support 54 limits the amount by which the snubber bar can project beyond the knife. By rotating the adjustment bolt clockwise or counter clockwise, the projection of the snubber bar can be decreased or increased, respectively. A spring 58 is disposed between the support 54 and the top of the snubber bar 36, to urge the snubber bar downwardly, so that during the knife downstroke, the snubber bar will resiliently engage the web, to stop its advance without damaging it. Other mechanisms for mounting the snubber bar to the knife component, so as to allow a limited amount of relative displacement, are known and may be provided as an alternative to the mechanism described above. For example, rather than providing an adjustable bolt to vary the projection amount Ks, the support provided on the knife component can itself be vertically adjustable to achieve substantially the same result.

The web feed and knife mechanisms are precisely positioned and speed controlled by a suitable stepper or servo motors and drives with high resolution encoders to achieve the desired cut accuracy. The knife stroke is synchronized to web position, making one cycle, down and up, for each cut sheet length. For a single cut, the upper knife is in the form of a cutting edge moving past a fixed lower blade anvil 60 (FIGURE 1 ). For a double-cut or chip cut, the upper knife is provided as a double edged knife opposed to two fixed lower blades.

Following the severance of the web by the knife stroke, the cut sheet is taken up by overspeed transport belts 62 to deliver the cut sheets 64 with a gap therebetween for collection and subsequent transport or further processing.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. Apparatus for cutting a continuously fed web comprising: a support structure defining a web feed path; a first web feed station disposed along said web feed path for positively feeding a continuous web along said web path; at least one cutting station disposed downstream of said first feed station along said web feed path and including a knife component for selectively cutting said web to define cut sheets, said cutting station including at least one web stopping mechanism for periodically stopping the web substantially immediately upstream of said knife component during said cutting operation with said knife component, a cut sheet take-up station disposed downstream of said cutting station for receiving cut sheets from said cutting station; and a buckle forming and accommodating portion disposed upstream of said cutting station and downstream of said first feed station for accommodating a buckle in said web formed during said cutting operation, said buckle accommodating portion including an upstream web guide assembly and a downstream web guide assembly for defining therebetween a buckle gap to allow and accommodate the formation of a buckle while the web is stopped for said cutting operation, wherein at least one of said web guide assemblies is adjustable along said web path so as to selectively alter a size of said buckle gap.

2. An apparatus for cutting as in claim 1 , wherein at least said one adjustable guide assembly includes a fixed guide component and an adjustable guide component for being selectively displaced relative to said fixed guide so as to adjust said buckle gap.

3. An apparatus for cutting as in claim 1 , wherein each of said upstream and said downstream buckle guides is adjustable so that a size of said buckle and a location of said buckle with respect to said cutting station can be selectively adjusted.

4. An apparatus for cutting as in claim 1 , further comprising a pull roll assembly disposed downstream of said buckle accommodating portion and upstream of said cutting station for selectively positively feeding web material from said buckle accommodating portion to said cutting station.

5. An apparatus for cutting as in claim 4, wherein said pull roll assembly comprises rolls rotated at overspeed so as to take up slack in said web following a cutting operation to thereby eliminate said buckle.

6. An apparatus for cutting as in claim 4, wherein said pull roll assembly is disengaged from said web at least when said snubber bar engages said web to stop the web upstream of said cutting knife.

7. An apparatus for cutting as in claim 4, wherein said pull rolls are pivotally mounted with respect to said support structure so as to be pivotable into and out of engagement with said web.

8. An apparatus for cutting as in claim 7, wherein said knife selectively engages a free end of said pull roll assembly so as to pivot said pull rolls out of engagement with said web during said knife downstroke and to release said pull rolls into engagement with said web during said knife upstroke.

9. An apparatus for cutting as in claim 7, wherein said pull rolls are spring biased into engagement with said web.

10. A method of cutting sheets from a continuously fed web, comprising: feeding a web along a web feed path; providing a buckle forming and accommodating portion for forming a buckle portion upstream of said knife component, said buckle accommodating portion including an upstream web guide assembly and a downstream web guide assembly for defining therebetween a buckle gap to allow and accommodate the formation of a buckle while the web is stopped during said cutting step, adjusting at least one of said web guide assemblies along said web path so as to selectively alter one of a size and a location of said buckle gap with respect to the knife component; periodically stopping the web substantially immediately upstream of a knife component; selectively cutting said web with said knife component while the web is stopped immediately upstream of the knife component, to define cut sheets; and taking up cut sheets downstream of said knife component.

11. A method as in claim 10, wherein said adjusting step comprises adjusting both said web guide assemblies.

12. A method as in claim 10, further including a pull roll assembly and wherein the method includes the step of, after the cutting step, feeding the web at an outlet of the buckle forming and accommodating portion at a speed greater than an web input speed so as to substantially eliminate the buckle formed therein.

13. A method as in claim 10, wherein said taking up step comprises providing take off belts and rotating said take off belts at a speed higher than said web feed speed, so as to provide a gap between cut sheets.