US3620874A

US3620874A - Method for producing tear-strips

Info

Publication number: US3620874A
Application number: US833951A
Authority: US
Inventors: Derek Henry Youngman; Robert William Davies
Original assignee: Molins Machine Co Ltd
Current assignee: Molins Machine Co Ltd
Priority date: 1969-06-17
Filing date: 1969-06-17
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16

Abstract

A method for producing tear-strips from a continuous web having a width equal to the desired length of tear-strip comprises intermittently advancing the longitudinal web, transversely cutting the web progressively from one edge to the opposite edge between each advancement of the web to sever portions of the web equal in length to the desired width of the tear-strip and continuously urging each strip as it is being severed from the web in a direction transverse to the direction of advance of the web and conveying each cut strip in a direction opposite to the direction the web is progressively cut.

Description

United States Patent Derek Henry Youngman;

Robert William Davies, both of Deptford, London, England June 17, 1969 Nov. 16, 1971 The Molins Organization Limited London, England Original application Nov. 8, 1965, Ser. No. 506,789, now Patent No. 3,502,536. Divided and this application June 17, 1969, Ser. No. 833,951

Inventors Appl. No. Filed Patented Assignee METHOD FOR PRODUCING TEAR-STRIPS 5 Claims, 7 Drawing Figs.

[1.8. 156/270 Int. (1 1332!) 31/18 Field of Search 156/265,

[56] References Cited UNITED STATES PATENTS 2,759,618 8/1956 Vogt 156/270 X 2,865,261 12/1958 Seragnoli 156/520 X Primary Examiner-Verlin R. Pendegrass Attorney-Craig, Antonelii, Stewart & l-lill ABSTRACT: A method for producing tear-strips from a continuous web having a width equal to the desired length of tearstrip comprises intermittently advancing the longitudinal web,

. transversely cutting the web progressively from one edge to the opposite edge between each advancement of the web to sever portions of the web equal in length to the desired width of the tear-strip and continuously urging each strip as it is being severed from the web in a direction transverse to the direction of advance of the web and conveying each cut strip in a direction opposite to the direction the web is progressively cut.

PATENTEDNnv 16 um 3,620,874

SHEEI 2 [IF 5 PATENTEBuuv 15 \en METHOD FOR PRODUCING FEAR-STRIPS This application is a divisional application of our copending application Ser. No. 506,789, filed Nov. 8, 1965, and now US. Pat. No. 3,502,536.

This invention relates to a method of producing tear-strips and applying the tear-strips to a web of wrapping material, as is required for example in cigarette-packing machines.

A tear-strip is narrow relative to its length, and earlier mechanisms for producing and applying tear-strips have, at least until recently, in general been supplied with tear-strip material already of the required width; said material has been fed from a reel or drum to cutting mechanism arranged to operate intermittently so as to sever strips of desired length,

the actual length of each strip being determined by the length fed forward between successive cutting operations.

Recently, it has been found advantageous in various respects to employ a web of tear-strip material whose width is equal to the length of the desired tear-strips. This however introduces the necessity for a comparatively long cut, and it is an object of the present invention to provide an improved method for producing tear-strips from a relatively wide strip or web.

According to the invention a method is provided for producing tear-strips from an elongated web of material of width to the desired length of the tear strips to be produced. This is accomplished by longitudinally advancing the web intermittently and between successive advancements transversely cutting the web progressively from one edge to the opposite edge whereby successive portions of the web equal in length to the desired width of the tear-strip are severed from the web. As each strip is being cut, it is continuously urged in a direction transverse to the direction of advance of the web, and upon completion of the cutting, the cut strip is conveyed in a direction opposite to the direction the web is progressively cut.

It will be understood that the terms upstream" and downstream" are used with their common meanings, i.e., the upstream edge of the web is that edge past which the motion of the conveyor means is directed towards the far edge of the web.

The knives may take various forms; we may mount the movable knife for pivotal movement relative to the fixed knife, i.e., so that the two knives operate in the manner of scissors, the pivotal axis being slightly farther downstream than the downstream edge of the web to be cut. Preferably, however, we provide a movable knife which is reciprocable at right-angles to the plane of the web; the progressive cutting is then achieved by providing one of the knives with a cutting edge inclined to the plane of the web, so that the spacing between the cutting edges of the two knives decreases in the direction of movement of the conveyor means.

In another form of apparatus employing a reciprocable knife, the conveyor means may take the form of a suction drum and the feed means is then arranged to advance the web to the knives with a substantially cylindrical curvature; one of the knives has a cutting edge curved to confonn to the curvature of the web while the other knife has a cutting edge with a larger-radius curvature, so that cutting is progressive.

The movable knife may if desired be provided with pneumatic means arranged to produce an airblast so directed as to urge tear-strips cut by said knives towards the conveyor means. Such pneumatic means conveniently includes a plurality of air passages in the movable knife itself and means for connecting said air passages to a source of compressed air.

Most conveniently the conveyor means comprises a suction conveyor in the form of an endless air-pervious belt to one face of which suction is applied so that atmospheric pressure serves to hold each tear-strip severed by the knives against the other face of the belt. In an alternative arrangement the conveyor means may comprise an endless impervious belt of electrically insulating material, e.g., nylon, arranged to become electrostatically charged so that tear-strips are held thereto by electrostatic attraction.

In general, the method according to the invention will be used as part of a process for applying a succession of tearstrips to a continuous web of wrapper material, which after application of the tear-strips may either be stored on reels until required or, as is preferred, fed directly to consuming apparatus such as a cigarette packer.

As a further feature of the invention, therefore, a method is provided for applying a succession of tear-strips to a continuous web of wrapper material, including the method for producing tear-strips as defined above together with the feeding of a continuous web of wrapper material and applying the tear-strips to said wrapper material in succession.

Preferably, such a method includes the application of a band of adhesive to the wrapper web before reaching the position where the tear-strips are applied. After the wrapper web has received the tear-strips, heat may be applied to cure the adhesive previously applied to the wrapper web to secure the tear-strips securely thereto. If the tear-strips and/or the wrapper web are of thermoplastic material, then the adhesive application step may not be needed, as heating alone may suffice to bond the tear-strip to the wrapper web.

In order that the invention may be well understood, preferred embodiments of apparatus for carrying out the novel method will now be described in detail, reference being made to the accompanying drawings in which:

FIG. I is an end view of a device embodying the invention employing a reciprocable knife;

FIG. 2 is a front view of the device of FIG. I, with certain parts omitted;

FIG. 3 is a front view of another device embodying the invention, employing a pivoted knife;

FIG. 4 is a front view of a modified form of device;

FIGS. 5 and 6 are end views of the device of FIG. 4; and

FIG. 7 shows somewhat diagrammatically yet another form of device.

First referring to FIG. 1, a web I of tear-strip material, of width (normal to the plane of the drawing) equal to the length of tear-strips to be made is drawn from a supply reel 2 by feed rollers 3. Rollers 3 are actuated intermittently by any convenient drive means (not shown) such as a ratchet drive, so as to advance at each actuation a length of the web 1 equal to the desired width of tear-strip. After passing through the rollers 3. the web I travels between guides 4 and below a fixed knife 5 having a lower face 6 slightly inclined to the horizontal; the edge of face 6 remote from rollers 3 serves as the cutting edge of knife 5 and cooperates with a movable knife 7 carried on a support member 8 which is in turn carried by arms 9 secured to a shaft 10. The shaft 10 is connected to a further drive means (not shown) arranged to rotate the shaft 10 through a small angle clockwise and then return it, so that knife 7 moves up past (and in contact with) the cutting edge of knife 5 and then returns; in FIG. I the movable knife 7 is shown at an intermediate point in its upward motion.

The rollers 3 and shaft 10 are operated alternately by their respective driving means, so that the knife 7 moves up and down between successive operations of the rollers 3. When the said rollers operate, and hence the web 1 advances, knife 7 is in its lowest position and the leading end of the web 1 is fed above it; then the next subsequent operation of shaft 10 causes the knife 7 to rise and the web 1 is severed by the action of the cooperating edges of knife 5 and knife 7. As at each operation of the rollers 3 the web 1 is advanced by the desired width of a tear-strip, each operation of knife 7 cuts from the leading end of the web I a strip of such width.

Such cutting produces a detached strip above the knife 7, and such strip is blown upwards by an airblast emerging from apertures in the upper surface of knife 7. Said apertures are connected by internal passages (indicated at 11) through knife 7 and support member 8 to an external flexible pipe 12 connected to a source of compressed air (not shown).

Above the movable knife 7, at a level a little higher than that of the cutting edge of the fixed knife 5, lies the lower run 13 of a conveyor belt 14 carried by two rollers 15 in conventional manner. The belt 14 is however an air-pervious belt, and above said lower run 13 is mounted a suction box 16 connected to a suction pump (not shown); the box 16 has an open lower face closed by the lower run 13 of the belt 14 so that atmospheric pressure causes air to flow through said lower run into the box.

Whenever a tear-strip is formed by the action of the knives 5, 7 as described above, as soon as the cutting is complete the airblast through the apertures in knife 7 causes the severed strip to move up until it encounters the lower run 13 of belt 14; the strip tlien blocks the airflow through the belt, the pressure in suction box 16 falls, and the strip is held against the belt by virtue of the pressure difference across it, i.e. because the lower face of the strip is subject to atmospheric pressure and its lower face to a lower pressure.

The fixed knife 5 has its bottom face 6, and hence its cutting edge, inclined to the horizontal, so that the spacing between the knives 5, 7 (with knife 7 in its lowest position, as in FIG. 2) decreases in the direction of travel of the lower run 13 of belt 14. It will be apparent that, as knife 7 rises, the strip severed from web 1 will first be cut free at its downstream, i.e. lefthand end (FIG. 2) and as cutting proceeds this end will be increasingly free to move up to the belt, under the influence of the airblast through the apertures in knife 7. Although part of the strip thus comes into contact with the belt before cutting is complete, insufficient frictional grip develops between the strip and the beltto break the strip, as until cutting is complete and the whole strip lies on the belt there is a substantial area of the lower run 13 of belt 14 which remains uncovered and hence the pressure difference between atmosphere and the interior of suction box 16 is less than when the whole strip lies against the belt. A slight pull is however exerted on the strip which in fact tends to assist in holding the uncut part of web 1 against the fixed knife 5 as is desirable for a clean cut.

The inclination of the cutting edge of knife 5 is important, being directed as shown to avoid buckling of the strip during cutting-if the upstream, i.e. right-hand end of the strip were to be freed first, its engagement with the belt would tend to carry it towards the uncut portion which is undesirable.

The web 1 of tear-strip material is so directed by the guides 4 that it lies in a plane parallel to the inclined lower face of the fixed knife 5 in the vicinity of said knife. Preferably the axis of feed reel 2 in inclined to the horizontal at the same angle as the lower face of knife 5, although as the required angle of inclination is relatively small it is permissible to mount reel 2 with its axis horizontal and introduce the required inclination of the web 1 as it passes through the rollers 3 and guides 4.

Once each strip is completely severed from the web 1, it travels with the belt 14 round the left-hand (FIG. 2) roller to a horizontal upper run of said belt. A wrapper web 17 is continuously fed from a supply reel 18 round a guide roller 19 so placed that the web 17 reaches the belt 14 tangentially just as the latter has started going round the downstream (lefthand) roller 15. At this point, the belt 14 has just moved clear of the suction box 16 and a tear-strip held therein as previously explained would tend to fall off in the absence of web 17. However, the web 17 prevents the fall of strips and the latter are, as they travel round said left-hand roller 15, pressed between web 17 and belt 14.

As web 17 passes round guide roller 19, it is also engaged by a gumming wheel 20 which transfer to the web 17 a line of ad hesive derived by said wheel from a gum pot 21 via a wick feed 22. Said line of adhesive is so positioned across the width of the web 17 that it is engaged by the tear-strips as they come into engagement with the web 17. As the strips travel with the web, and pressed against it, around the left-hand roller 15, along the upper run of belt 14, and then part-way round the right-hand roller 15 before leaving the belt, the said tear-strips are effectively caused to adhere to the web 17 so long as the speed of belt 14 is low enough to allow time for the adhesive to set. Should higher speeds be desired, then a heater may be placed above the upper run of belt 14, as indicated in dashed lines at 23, to accelerate setting of the adhesive.

Turning now to FIG. 3, we show an alternative form of device embodying the invention. In this form, a fixed knife is mounted adjacent to the upper run 113 of a conveyor belt 114 which, like belt 14 of FIGS. 1 and 2, is an air-pervious belt carried by rollers 115 and below said upper run 113 is mounted a suction box 116 connected to a suction pump (not shown). The suction box 116 has an open upper face closed by the upper run 113 of the belt so that atmospheric pressure causes air to flow through said lower run into the box.

A movable knife 107 is mounted on a pivot placed a little above and to the right of the right-hand end of the fixed knife 105, so that the two

knives

105, 107 function in a scissorslike manner whenever the movable knife 107 is oscillated on its pivot. A web of tear-strip material is fed between the two

knives

105, 107 by means (not shown) which may comprise rollers and guides as shown in FIG. 2. In the device now being considered the web of tear-strip material will also be advanced intermittently, each advancing movement being made at a time when the movable knife 107 is clear of the fixed knife 105 (i.e., is in a more clockwise position than shown in FIG. 3). Various forms of drive may be provided for the knife 107; a simple and convenient arrangement as shown includes a rotatable drive shaft 126 carrying a crank 127 which in turn is linked by a connecting rod 128 to an operating arm 129 forming an extension of the knife 107 to the right of its pivot 125.

In FIG. 3, movable knife 107 is shown approximately halfway through a cutting stroke and a tear-strip 130 can be seen in a half-severed condition. Rollers 115 rotate clockwise and hence the upper run 113 of belt 114 moves from left to right. Cutting of each' tear-strip starts at the right (i.e., downstream) end and the airstream through said upper run 113, previously mentioned, causes the severed part of each tear-strip to be urged towards and held against the belt while cutting proceeds; as soon as cutting of the strip is complete, the already existing contact between the strip and the belt will cause the strip to move with the upper run 113 to the right.

As in the device of FIGS. 1 and 2, a wrapper web, here identified as 117, is fed from a supply reel 118 so as to reach the belt 114 tangentially as the latter has just started going round the downstream (right-hand) roller 115. Before reaching the belt 114, however, web 117 passes round two guide rollers 119 between which it is engaged by a gumming wick 120 fed by a gum pot I21. Wick 120 serves the same purpose as gumming wheel 20 (FIG. 2), i.e., it puts on wrapper web 117 a line of adhesive so positioned'across the width of web 117 that it is engaged by the tear-strips as they come into engagement with said web. It will be seen from FIG. 3 that the leading (right-hand) end of each tear-strip will be gripped between the web 117 and the belt 114, backed by the righthand roller 115, before the trailing end of the same tear-strip has passed out of register with suction box 116; thus the tearstrips, once severed, are held in position on belt 114 until their location against the line of adhesive on web 117 is established.

Web 1 17 feeds off belt 1 14 and right-hand roller 115 at 131. If the speed of the device and characteristics of the adhesive applied to web 117 so require, a heater may be placed adjacent to the web 117 in this area, e.g., as indicated in dashed lines at 123.

In FIGS. 4 to 6 is illustrated a further form of device embodying the invention.

Much of -the device shown in these figures corresponds closely to one or other of the embodiments previously described. It may therefore briefly be said that here a reciprocating knife 207 cooperates with a fixed knife 205 to cut tear-strips from a continuous web 201; said web reaches the knives via feed rollers 203 and guides 204.

The movable knife 207 is carried by support members 208 on arms 209 which are rockable on a shaft 210. As each tearstrip is cut. it falls on to the upper run 213 of a suction belt conveyor 214 carried by rollers 215 and provided with a suction box 216.

A wrapper web 217 is fed to the belt conveyor 214 via guide roller 219, gumming wheel 220 (with which a gumming device 222 isassociated) and a further guide roller; wheel 220 applies a line of gum to web 217 and when the latter reaches belt 214, said gum is pressed against tear-strips severed by the knives and by the time the web 217 leaves the belt 214, passing around a guide roller 224, the tear-strips are firmly secured to the web 217.

The knife 207 is driven from a drive shaft 226 by means of eccentrics 227 on said shaft which operate connecting rods 228 pivotally secured to operating arms 229 in the form of extensions of the arms 209. The lower one of feed rollers 203 is driven intermittently, to advance web 201 by a distance equal to the desired width of a tear-strip; this drive also comes from shaft 226, via an eccentric 232 which through a connecting arm 233 operates a sector plate 234 loosely carried on a shaft 238. The plate 234 carries a drive pawl 235 engaged with a ratchet wheel 237 secured to shafl 238 carrying the lower feed roller 203. A holding pawl 276 (pivotally mounted on a fixed part of the device) also engages ratchet wheel 237.

It will be apparent that reciprocation of arm 233, produced by eccentric 232 as shaft 226 turns, will cause rocking of sector plate 234. As the latter moves anticlockwise (FIG. 5) the pawl 235 turns the ratchet wheel with the plate 234, pawl 276 slipping, but as plate 234 moves clockwise, pawl 276 holds wheel 237 stationary while pawl 235 slips. As the lower feed roller 203 is carried by and secured to the shaft 238, said roller is intermittently rotated to feed the web 201 by suitable constant increments.

in operation of such a device, e.g., for initial setting, it may be desired to relax the grip of feed rollers 203 on web 201. For this purpose, the upper roller 203 may be lifted, against the pressure of springs 243 which urge it downwardly; such lifting is accomplished by manual operation of a handle 239 which causes cams 240 to turn; said cams 240 each bear against one end of a bellcrank support 241 for the upper roller 203, said supports 24] being carried by a pivot shaft 242.

Turning now to FIG. 7, there is shown in diagrammatic form yet another form of device embodying the invention. This device embodies a suction drum in place of the belt conveyors previously described, to carry the severed tear-strips and unite them with the wrapper web.

As can be seen in FIG. 7, the wrapper web, here marked as 317, travels past an adhesive or solvent applicator 320 and a guide roller 319 to the surface of a suction drum 314, round approximately one-half the circumference of said drum and then leaves past guide roller 324, and driven feed rollers 325. The suction drum 314 is perforated and hollow, and during operation a subatmospheric pressure is maintained within said drum so that the latter grips the web 317 in known manner.

Tear-strips 330 are placed on the surface of the drum 314 shortly before the arrival of the web 317 thereon. The tearstrips are produced by apparatus in essentials similar to that of FIG. 1; however, in this instance the knives are curved to allow for the curvature of the drum 314, and tear-strip web 301 is fed to said knives in a suitably curved configuration. In FIG. 7, it will be seen that there is shown a fixed knife 305 and a movable knife 307, the latter being reciprocable radially of the drum.

The cutting edge of the movable knife 307 conforms to the curvature of the drum being in the form of a circular arc, centered on the axis of drum 314, while the fixed knife 305 has a cutting edge which, while also of arcuate form, has a center of curvature displaced from the axis of the drum 314 so that cutting occurs progressively, starting at the downstream edge of the tear-strip web 301 as in the devices previously described.

It will be seen that an efficient and relatively simple method of producing tear-strips is provided by the invention. While the devices described in detail with reference to the accompanying drawings are presently preferred means for practising the method of the invention which may with advantage be employed with cigarette-packing machines, it will be understood that various changes and modifications may be made in such a device while still employing the method of the invention; moreover such devices may be employed to practise the method in association with machines other than cigarette packers.

As one example of a possible modification, we may dispense with the application of suction through the belt 14, and employ electrostatic means to hold the tear-strip to said belt. In such an arrangement, the belt 14 need not be air-pervious, for example an imperforate nylon belt may be used, and means are provided to impart to the outer surface of the belt 14 an electrostatic charge suflicient to retain the tear-strips thereon. While in some circumstances it may be found desirable to charge the belt and/or the strip directly i.e., by connection through brushes or the like to an electric supply, in many cases sufficient charge is developed on a moving nylon belt without such connection.

We claim:

1. A method for producing tear-strips from an elongated web of material of width equal to the desired length of the tear-strips to be produced comprising longitudinally advancing said web intennittently, transversely cutting said web with cutting means progressively from one edge to the opposite edge between successive advancements of said web whereby successive portions of said web equal in length to the desired width of the tear-strips are severed from said web, continuously and progressively urging each strip away from said cutting means as it is being cut from said web in a direction transverse to the direction of advance of said web, and conveying each cut strip in a direction opposite to the direction said web is progressively cut.

2. A method of applying a succession of tear-strips to a continuous web of wrapping material comprising the method for producing tear-strips as claimed in claim 6 and feeding a continuous web of wrapper material to a position to receive said conveyed tear-strips in succession.

3. a method as claimed in claim 2 wherein a band of adhe sive is applied to the wrapper web before receiving said tearstrips.

4. A method as claimed in claim 6 wherein each strip is continuously urged as it is being cut from said web in a direction transverse to the direction of advance of said web by directing an airstream against the surface of each strip.

5. A method as claimed in claim 2 wherein said wrapper web is heated afier receiving the tear-strips.

t I I i It

Claims

2. A method of applying a succession of tear-strips to a continuous web of wrapping material comprising the method for producing tear-strips as claimed in claim 6 and feeding a continuous web of wrapper material to a position to receive said conveyed tear-strips in succession.
3. A method as claimed in claim 2 wherein a band of adhesive is applied to the wrapper web before receiving said tear-strips.
4. A method as claimed in claim 6 wherein each strip is continuously urged as it is being cut from said web in a direction transverse to the direction of advance of said web by directing an airstream against the surface of each strip.
5. A method as claimed in claim 2 wherein said wrapper web is heated after receiving the tear-strips.