US3114299A

US3114299A - Machine for the continuous production of flat bags

Info

Publication number: US3114299A
Application number: US68269A
Authority: US
Inventors: Entzminger Auguste
Original assignee: Ateliers de Constructions Mecaniques C&A Holweg SA
Current assignee: Ateliers de Constructions Mecaniques C&A Holweg SA
Priority date: 1960-11-09
Filing date: 1960-11-09
Publication date: 1963-12-17
Anticipated expiration: 1980-12-17

Description

Dec. 17, 1963 A. ENTZMINGER MACHINE FOR THE CONTINUOUS PRODUCTION OF FLAT BAGS 3 Sheets-Sheet 1 Filed Nov. 9, 1960 Dec. 17, 1963 A. ENTZMINGER 3,114,299

MACHINE FOR THE CONTINUOUS PRODUCTION OF FLAT BAGS Filed Nov. 9, 1960 5 Sheets-Sheet 2 Dec. 17, 1963 A. ENTZMINGER MACHINE FOR THE CONTINUOUS PRODUCTION OF FLAT BAGS Filed NOV. 9, 1960 3 Sheets-Sheet 3 United States Patent 3,114,299 MACHINE FQR THE CONTINUOUS PRODUCTION OF FLAT BAGS Auguste Entzminger, Schiltigheim, France, a'ssignor to Les Ateliers de Constructions Meeaniques C. & A. Holweg,

S.a.r.l., Strasbourg, Bas-Rhin, France Filed Nov. 9, 1960, Ser. No. 68,269 7 Claims. (Cl. 93-18) The present invention relates to a machine for the continuous production of flat bags, wherein the web of material to be covered into bags is successively provided, at intervals corresponding to the bag length in each case, with lines of attenuation disposed transversely of the web, then shaped into a tube and finally divided into bag sections by tearing along the lines of attenuation, whereupon the bottom is then formed on these bag sections. Here the traction of the web is preferably taken over by two pairs of rollers driven in force-effected fashion, one of which is arranged at the entry of the web into the machine and the other behind the tube formation position, the latter being driven through a friction coupling.

As is known, such machines work with high speed and possess a great output capacity. In order to utilize this output capacity fully and to be able to increase it still further, if possible, it is necessary that the devices effecting the traction and the conversion of the web, and the Web itself, must be able to be set at any time during the operation of the machine, according to requirements from case to case of the working conditions, which are greatly variable mainly as a result of the nature of the material, which is not the same overall. This setting must be capable of taking place as rapidly as possible, since the slightest delay results in production of waste, together with a more or less long interruption of work. The losses thereby incurred can assume quite considerable proportions, due to the fact that they occur on a a high-output machine.

Apart from the necessity of being able to adjust the different working devices and the web of material during operation of the machine rapidly to the working conditions in each case, there is also the further necessity of being able to disengage these devices instantaneously and without altering their existing setting, on the occurrence of a disturbance, and of beingable to re-engage them again after removal of the disturbance.

In the production of bags, as for example of doubleaeam bags, letter envelopes, or the like, where waste is produced, it is also necessary that this waste should be removed from the working region of the production site according to the measure of its production, that is to say very rapidly.

It is, thus, one object of the present invention to provide a machine for the continuous production of fiat bags wherein each of the pairs of rollers consists of a presser roller and a counterresser roller, whereby one of the rollers effects the traction of the web of material and the other of the rollers the division thereof into bag sections by tearing oif. During the operation the presser roller can be adjusted in relation to the counter-presser roller according to the operational conditions in each case, and furthermore in the case of the traction roller pairs the presser roller can suddenly he disengaged and re-engaged without variation of this setting, and alsothat, similarly during operation, the rotating perforating tool which produces the line of attenuation can be shifted axially and the eccentrically mounted deflector roller which causes the longitudinal correction of the web can be shifted radially.

With this and other objects in view which will become apparent in the following detailed description, the present invention will be clear understood in connection with the accompanying drawings, in which:

3,114,299 Patented Dec. 17., 1963 FIG. 1 is an overall lateral elevation of the first embodiment of the present machine;

FIG. 2 is a fragmentary perspective View, amplify ing FIG. 1, of the progressive conversion of the web of material into a finished flat bag;

FIG. 3 is a partial lateral elevation of another embodiment of the present machine;

FIG. 4 is a plan view of the web section which is worked, amplifying FIG. 3;

FIG. 5 is a plan view of the roller arrangement present between the tube formation position and the bottomfolding mechanism;

FIG. 6 is a partially sectional plan view of the rotating perforating device;

FIG. 7 is a cross-section through the second pair of traction rollers, driven through a friction coupling;

FIG. 8 is a partially sectional lateral elevation of an additional tearing-off and waste-discharge device;

FIG. 9 is an elevation, on a somewhat larger scale, of the tearing-off device according to the first embodiment of the present invention, in the position at the first separating step;

FIG. 10 is a plan view of the tube at the same separating cut;

FIGS. 11 and 12 are views similar to those in FIGS. 9 and 10, let in a position after the second and last separating steps.

Referring now to the drawings, and in particular to FIGS. 1, 2 and 5 to 12, showing the first embodiment of the present invention, the present machine is set up for the production of flat bags from a web folded into a tube, wherein the bottom and closure flaps are folded over on to the same side of the bag.

The machine comprises a series of traction and working devices, which are described as follows: a first pair of traction rollers A is disposed opposite a glueing device B, to be followed by a perforating device C, and then by a device D for the correction of the strip length. A tube formation device E is followed by a second pair of traction rollers F, then by a pair of rollers G for the periodic stopping of the web movement to provide then a special pair of rollers H for additional tearing off and waste-removal, to provide then a pair of tearer rollers J, a bottom-folding mechanism K, and a further glueing device L.

The web of material 1, wound on a hollow spindle, is mounted on a shaft 2, which is supported by bearing arms 4 secured on the frame 3 of the machine. It is unwound from the shaft 2 by the traction roller pair A over deflecting rollers 5 and 6, and passed on to the perforating device C.

The traction roller pair A is formed by a stationarily arranged, directly driven roller 7 and a roller 8 pressed thereon. and expediently divided into two rings. The roller 8 is rotatably secured on the free end of the short arm of a toggle lever 9, and can be pressed more or less strongly on to the counter-presser roller 7, by a traction exerted upon the longer arm of the toggle lever 9. As

means for the exertion of this traction there serves a threaded spindle 10, which can be screwed in a nut 11 fixedly arranged on the frame 3 and the smooth part of which freely extends through the longer arm of the tog gle lever 9, and terminates in a small collar 10', against which there bears one end of a compression spring 12, the other end of which abuts on the long arm of the toggle lever. By screwing out the spindle 10 by means of the hand wheel 10" the spring 12 is more strongly tensioned and consequently the bearing pressure of the roller 8 upon the roller 7 is correspondingly increased. In this manner it is possible to regulate this pressure simply and rapidly during operation of the machine, according to the requirements in each case. Furthermore this arrangement permits of suddenly disengaging and re-engaging the presser roller 8, also during operation, and in fact this is effected by rotation of the stationarily mounted eccentric 13, against the profile of which the free, angled end of the long arm of the toggle lever 9 rests.

At approximately the same height as the traction roller pair A there is arranged a glueing device B. This serves for the application of the glue trace for glueing together the two longitudinal edges of the web, and consists as usual of a glue container 14 and the glue transfer disc 15 dipping into the latter and constantly resiliently pressed against the counter-presser roller 7. The latter is at the same time the counter-presser roller of the traction roller pair 7 and S and it must be regarded as a simplification that the roller 7, by virtue of the arrangement of the traction roller pair 7 and 8 and of the glueing device 14 and 15, in accordance with the present invention, can fulfill two functions at the same time. Incidentally the glueing device 14 and 15 is mounted for pivoting about a horizontal spindle 14, and can be pivoted out at any time by shifting of an eccentric 14", so far that its disc 15 no longer comes into contact with the web 1.

The web 1, provided with the longitudinal glue trace, then passes to the perforating device C, where in known manner it is provided with lines of attenuation extending transversely thereof, which in this embodiment have such a form that they define at the same time the bottom flap of one bag and the closure flap of the other of two succeeding bags. The production of these lines of attenuation takes place by means of the perforating device C, which consists of a roller 16 with the perforating blade 16' and a counter-presser roller 17. In this device it is novel that the roller 16 with the perforating blade 16 can be adjusted axially and secured again while the machine is working. For this purpose its shaft 16 extends with one end through a mounting sleeve 18 (FIG. 6) firmly connected with the frame 3 of the machine, which sleeve 18 is provided at its free end with an external threading 18, upon which a cap nut 19 and a locking nut 20 are screwed. The shaft 16" terminates in a short, threaded journal 16", which projects somewhat out of the cap nut 19 and carries on the part projecting out a hexagonal nut 21' and a washer 22. By slackening the locking nut 20 and rotation of the cap nut 19 in one direction or the other, the shaft 16" or the roller 16 with the perforating blade 16 is accordingly moved to the right or left and then locked firmly by re-tightening of the locking nut 20, when the desired position is reached. By virtue of this device it is possible always to set the perforating roller 16 during the work of the machine in such a manner that the bottom and closure flaps defined by the perforated lines are always distributed in the direction of the width exactly symmetrically of the longitudinal center line of the tube formed from the web. If this is not so, the machine produces useless bags or waste, and must frequently be stopped and readjusted for the removal of this defect, as is frequently the case in the known machines.

The strip is then provided with a transverse fold by a rotating folding strip 21, at the point where the closure flap adjoins the bag, and thereupon passes over a deflecting roller 22 to the tube formation position E, where the strip is formed into a tube in known manner and with known means.

The deflecting roller 22 is rotatably mounted, as also known, on the free end of two pivot arms 23, and in accordance with a novel design is constructed as eccentric roller, which can be rotated by a handle 24. According to the rotation of this eccentric roller 22, the strip end is drawn more or less far oppositely to the direction of running or upwards, which has the result that the distance of the bottom fold, about which the bottom fiap is turned over on to the bag, from the end of the strip is reduced or increased. Thus in this manner the length of overlap of the bottom flap can be regulated during the operation of the machine, according to desire and need, which is the more necessary because this length constantly varies during the operation of the machine, as a result of the unavoidable side phenomena, and it could occur that the length no longer suffices for the production of a sealed bottom.

After the strip is formed into a tube, it is pressed flat between two

presser rollers

25 and 26, and then comes between the second traction roller pair P, which is driven through a friction coupling and the task of which is to keep the web section situated between itself and the first traction roller pair A always under traction in such a way that the conversion of the web into a tube can take place correctly. The arrangement of such a second traction roller pair F behind the tube formation position of a machine for the continuous production of fiat bags is known, and, therefore, not included in the present invention. It has, however, appeared in practice that it can only fulfill its purpose correctly if both the friction resistance of its coupling and the bearing pressure of its presser roller can be varied according to needs in each case during the operation of the machine. In accordance with the present invention this is rendered possible as follows: The second traction roller pair F is composed as hitherto of the presser roller 27 divided into two traction rings, and the counter presser roller 28 co-operating therewith. The latter is also, as hitherto, driven through a spur gear wheel 3% (FIG. 7) mounted loosely on its shaft 2n. On both sides of the gear wheel 30 there are similarly loosely mounted on the shaft 28 a friction disc 29 and a flanged sleeve 31, and this entire loose arrangement is pressed by a compression spring 32 against a stationary thrust bearing 33, namely the more strongly is the spring 32 tensioned. The spring 32 bears on the one hand against the outer flanged sleeve 31 and on the other hand against a bearing support 34, in which one end of the shaft 28 rotates, and which is produced in one piece with a relatively long guide sleeve 34'. The guide sleeve 34 is pushed on a pin 35 firmly anchored in the frame of the

roller pair

27, 28, the free end of which pin is threaded, and on to which a nut and locknut 36 and 36', respectively, are screwed, by means of which the guide sleeve 34' and the bearing support 34 can be shifted axially and locked again after every movement. Due to this axial displacement of the support 34 in one direction or the other, the tension of the spring 32 is either increased or decreased, and to the same extent then the friction resistance of the friction coupling consisting of the above-enumerated parts is increased or reduced also.

On the other hand the shaft 27' of the presser roller 27 is mounted in a sliding piece 37 at each end, each of which is subject to the influence of a spring 38, one end of which presses against a fixed part of the frame of the

traction roller pair

27 and 28 and the other end of which presses against a nut 39, which is screwed on to a pin 40 firmly anchored in the corresponding sliding piece 37. By means of the nuts 39 the tension of the springs 38 can be regulated according to need in each case, namely independently on each side, which is of importance in as much as an oblique running of the web is thereby prevented.

The correctly set presser roller 27 can then be disengaged and re-engaged suddenly without varying its setting, at any time. This is rendered possible due to the fact that each of the two pins 49 extends with its free end, constructed as mounting eye, upwards somewhat out of the roller carrier 45, and is movably secured to a pin 41' serving as fixed pivot axis of an eccentric lever 41. The two eccentric levers 41 are connected articulatedly with one another through a small rod 42 in such fashion that when the one eccentric lever is rotated, the other moves therewith to the same extent, and that due to this movement the two sliding pieces 37 are lifted with the presser roller 27 mounted in the latter away from the counterpresser roller 28, against the action of the springs 38.

The roller pairs G, following the thus described second traction roller arrangement F, with the

rollers

43 and 44 for the intermittent retainin of the tube, the two

tearer rollers

46 and 47 of the unit I for the tearing off of the forward tube piece, and the bottom folding mechanism 48, 48' following this

last roller pair

46 and 47, with the glueing device 49, are known as regards both their construction and their arrangement and manner of operation, and therefore require no further explanation.

In the production of ordinary flat bags, that is to say of those wherein the bottom flap is folded on to one side of the bag and the closer flap on to the other side, the separation of the foremost tube piece from the next following takes place in one step, in that the latter tube piece is retained a short distance behind the line of separation, by the

roller pair

43 and 44, and the foremost tube piece is separated away from the next succeeding tube piece, by the somewhat more rapidly running tearing

rollers

46, 47, along the line of separation. In the case of relatively long bags the tearing

rollers

46 and 47 can be replaced by the

bottom folding mechanism

48, 43.

In the production of flat bags wherein both the bottom flap and the closer flap are folded down on the same side of the bag, the separation of the foremost tube piece from the next succeeding piece takes place in two steps, and in fact in the first step the foremost tube piece, together with the waste occurring in this style of production, is separated from the next succeeding tube piece, and in the second step the waste is separated from the latter, as may be seen clearly from FIGS. 9 to 12, of which FIGURES 9 and 10 show the position of the individual rollers and the position of the individual tube pieces in relation to one another in the first separation step, and FIGS. 11 and 12 the same in the second separation step. Here the first separation is effected by a

special roller pair

50, 51 in combination with the

roller pair

43, 44 and the second separation is eifected by the same special roller pair in combination with the tearing

roller pair

46, 47, which may also be replaced by the bottom-folding mechanism 48, 48'.

These statements regarding the separation of the tube in one or two separation steps were made merely for the sake of completeness, for in reality both the one and the other of the two styles of separation have already become known and the same also applies to the means for the execution thereof, except however for those which serve for the removal of the waste. These means consisted hitherto of a series of points fixedly provided on the periphery of the counter-presser roller 51 of the special roller pair, which impaled the waste and took it out of the working region of the machine. At the speed at that time, increased to extreme, with which these machines work, such a waste removal, which in fact suffers from the fact that the impaling of the waste does not take place suddenly enough, is no longer possible. In accordance with the present invention, therefore, the fixed points were replaced by movable points, which are so actuated by a cam control that at the correct moment they spring with great suddenness out of the periphery of the roller 51, impale the waste, and on further rotation of the roller 51 then withdraw again into its interior, and in doing so release the waste. FIG. 8 shows how this has been rendered possible. According to this figure, the roller 51 is constructed as hollow roller, the wall of which has, at at least one position 51', a row of holes for the points 52 secured on a common strip 52. The strip 52 is articulated onthe side opposite to the points to the short arm of a two-armed level 53, which has its pivot point at 53 in the wall of the roller 51 and the long arm of which is drawn by a traction spring 54 constantly against a stationary cam 55. Here the contact of the lever 53 with the cam 55 is expediently constituted by a small round disc 53" rotatably secured on the lever 53. The profile of the cam 55 is so selected, that the sudden springing of the points out of the roller 51 takes place at the same moment when they have reached the perpendicular line of connection of the center points of the two rollers 50 and 51 (FIG. 11). On further rotation of the roller 51 the points 52 always draw back further into the interior of the roller 51, until they just still retain the waste, so that the latter can reliably be stripped off from them by a rotating rake 56 (FIG. 8).

As may be seen from FIGS. 1 and 5, the roller pairs 25 and 26, 27 and 23 and 43 and 44, the peripheral speed of which is the same as the conveying speed of the web of material or of the tube produced therefrom, are all mounted in a. common carriage and in this manner from a structural unit, while each of the two further roller pairs 5i? and 51 and 46 and 47 is independently mounted in a car iage. These three carriages can be shifted in relation to one another on the machine bed in such a way as is necessitated by the bag forms to be produced from case to case.

Referring now again to the drawing, and in particular to FIGS. 3 and 4, a second embodiment, is disclosed which is arranged for the production of fiat bags with lateral stuck seams. It differs from the first embodiment due to the fact that between the glueing device B and the perforating device C there is interposed a folding device M for the production of the two longitudinal folds, and in that further the tube-formation device E is replaced by a longitudinal cutting device N and a device 0 arranged thereafter for the turning over of the lateral stuck seams remaining after the cutting out of the edges on both sides of the material web, 1.

The folding device M consists of two folding discs 69 mounted on a common shaft, and a counter-presser roller 61 co-operating therewith, while the longitudinal cutting device N consists of two longitudinal cutting blades 63 and a counter-presser roller 64 co-operating therewith. The waste occurring on this cutting device can be removed for example through air nozzles 63 connected to the suction side of an air compressor.

From the cutting device the web is fed over a deflecting roller 66 to the device 0 for the folding over of the lateral stuck seams, and thence to a glueing device P, which is provided at the point where the web reaches the plane which separates the rollers of the further roller pairs. Since in this case no tube is formed, the glueing device B is omitted. Otherwise the work takes its course in the case of this embodiment exactly as in the case of the first embodiment.

While I have disclosed several embodiments of the present invention, it is to be understood that these are given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claims.

I claim:

1. In a machine for the continuous production of fiat bags, a series of pairs of rollers, each of said pairs of rollers comprising a presser roller and a counter-presser roller, and said series of pairs of rollers including a first pair of traction rollers adapted to feed a web of material between said first pair of traction rollers, a gluing roller releasably engaging one of the rollers of said first pair of traction rollers and adapted to apply adhesive to said web of material along a longitudinal line thereof during the movement of said web material, means for perforating crosswise said web of material at a predetermined spacing taken in longitudinal direction of said web, means for correcting the strip length of said web material following said perforating means, means for forming a tube from said web of material, a second pair of traction rollers adapted to continue the feeding of said web of material in tube form, a pair of rollers for retarding periodically the movement of said web, a pair of rollers for tearing off and waste-removal of predetermined portions of said web, a pair of rollers for additional tearing of portions of said web, means for folding the bottom portion of the bag to be made, means for adjusting one of the rollers of said first pair of traction rollers relative to the corresponding other of said rollers of said first pair of traction rollers in accordance with the operating conditions, means for sudden disengagement of said presser roller without disturbance of said adjustment of said first traction rollers, means for shifting in lateral direction of said web said perforation means, and means for shifting radially said strip length correcting means causing a longitudinal correction of said web.

2. The machine, as set forth in claim 1, which includes means for driving said first and second pairs of traction rollers, said first pair of traction rollers being disposed at the starting end of said machine and said second pair of traction rollers being disposed immediately following said tube forming means, said driving means for said second pair of traction rollers including friction coupling means, said first pair of traction rollers including a double toggle lever having a long arm and a short arm, the presser roller of said first pair of traction rollers being rotatably secured to said short arm and a spring engaging said long arm to urge said last mentioned presser roller toward the corresponding counter presser roller, a threaded spindle projecting through said long arm and carrying said spring and adapted to adjust the pressure of said spring during operation of said machine, and the presser roller of said second pair of traction rollers is spring-biased toward the corresponding of the counter-rollers, and means for varying the tension of said last mentioned spring during operation of said machine.

3. The machine, as set forth in claim 2, wherein said friction coupling means of said second pair of traction rollers includes friction elements interposed in said driving means, a spring acting on said friction elements, and means for adjusting the pressure of said spring.

4. The machine, as set forth in claim 1, which includes eccentric means constituting said means for sudden disengagement of said presser roller.

5. The machine, as set forth in claim 1, wherein said perforating means comprises a pair of rollers and said means for shifting in lateral direction of said web said perforation means comprises means for axially adjusting said pair of rollers during operation of said machine, said adjusting means comprising a shaft for one roller of said pair of rollers, a cap nut mounted on said shaft and a stationary mounting sleeve threadedly receiving said cap nut.

6. The machine, as set forth in claim 1, wherein said strip length correcting means is disposed between said perforating means and said tube forming means, and an eccentric mounting means for said deflecting roller.

7. The machine, as set forth in claim 1, wherein the presser roller of said pair of rollers for tearing off portions of said web is a hollow roller having a circumferential wall, said wall having a plurality of holes disposed along a predetermined line, a strip disposed parallel to the axis of said roller and having a plurality of pins extending through said holes, a two-armed lever pivotally supporting said strip, a stationary cam controlling said twoarmed lever in order to move forward said pins suddenly during rotation of said roller, to impale the waste and to withdraw said pins into said roller, and a rake rotatably mounted adjacent said roller and removing said waste taken from said pins.

References Cited in the file of this patent UNITED STATES PATENTS 1,268,674 Brown June 4, 1918 1,941,272 Potdevin Dec. 26, 1933 2,016,047 Pope Oct. 1, 1935 2,030,118 Poppe Feb. 11, 1936 2,090,308 Potdevin Aug. 17, 1937 2,124,209 Poppe July 19, 1938 2,330,446 Piazze et a1 Sept. 28, 1943 2,382,930 Williams Aug. 14, 1945 2,652,879 Keller et al Sept. 22, 1953 FOREIGN PATENTS 1,159,929 France Feb. 17, 1958

Claims

1. IN A MACHINE FOR THE CONTINUOUS PRODUCTION OF FLAT BAGS, A SERIES OF PAIRS OF ROLLERS, EACH OF SAID PAIRS OF ROLLERS COMPRISING A PRESSER ROLLER AND A COUNTER-PRESSER ROLLER, AND SAID SERIES OF PAIRS OF ROLLERS INCLUDING A FIRST PAIR OF TRACTION ROLLERS ADAPTED TO FEED A WEB OF MATERIAL BETWEEN SAID FIRST OF TRACTION ROLLERS, A GLUING ROLLER RELEASABLY ENGAGING ONE OF THE ROLLERS OF SAID FIRST PAIR OF TRACTION ROLLERS AND ADAPTED TO APPLY ADHESIVE TO SAID WEB OF MATERIAL ALONG A LONGITUDINAL LINE THEREOF DURING THE MOVEMENT OF SAID WEB MATERIAL, MEANS FOR PERFORATING CROSSWISE SAID WEB OF MATERIAL AT A PREDETERMINED SPACING TAKEN IN LONGITUDINAL DIRECTION OF SAID WEB, MEANS FOR CORRECTING THE STRIP LENGTH OF SAID WEB MATERIAL FOLLOWING SAID PERFORATING MEANS, MEANS FOR FORMING A TUBE FROM SAID WEB OF MATERIAL, A SECOND PAIR OF TRACTION ROLLERS ADAPTED TO CONTINUE THE FEEDING OF SAID WEB OF MATERIAL IN TUBE FORM, A PAIR OF ROLLERS FOR RETARDING PERIODICALLY THE MOVEMENT OF SAID WEB, A PAIR OF ROLLERS FOR TEARING OFF AND WASTE-REMOVAL OF PREDETERMINED PORTIONS OF SAID WEB, A PAIR OF ROLLERS FOR ADDITIONAL TEARING OF PORTIONS OF SAID WEB, MEANS FOR FOLDING THE BOTTOM PORTION OF THE BAG TO BE MADE, MEANS FOR ADJUSTING ONE OF THE ROLLERS OF SAID FIRST PAIR OF TRACTION ROLLERS RELATIVE TO THE CORRESPONDING OTHER OF SAID ROLLERS OF SAID FIRST PAIR OF TRACTION ROLLERS IN ACCORDANCE WITH THE OPERATING CONDITIONS, MEANS FOR SUDDEN DISENGAGEMENT OF SAID PRESSER ROLLER WITHOUT DISTURBANCE OF SAID ADJUSTMENT OF SAID FIRST TRACTION ROLLERS, MEANS FOR SHIFTING IN LATERAL DIRECTION OF SAID WEB SAID PERFORATION MEANS, AND MEANS FOR SHIFTING RADIALLY SAID STRIP LENGTH CORRECTING MEANS CAUSING A LONGITUDINAL CORRECTION OF SAID WEB.