EP0105191A2 - Cutter for flexible webs - Google Patents

Abstract

In apparatus for cutting a web of flexible material, upper and lower cutters are mounted on a swivel arm movable by a control means which determines the position of the cut. The control means includes a pneumatic cylinder and piston pivoted to a control arm linked to or integral with the swivel arm and of a much shorter effective length than the swivel arm. The cutting action is initiated by inter-engagement between the swivel arm and a stop edge of the web.

Description

The invention relates to a device for the precise introduction of a cut into a web of flexible material, with a lower knife and an upper knife rotatably articulated thereon, at least one of which is driven, and with a feed device for the material web.

The creation of individual articles, pieces of tape or packs from a wide variety of materials, all of which show the physical properties of a flexible material and a certain degree of rigidity, generally plays a major role in technology. Often, cuts have to be made at certain points on an intermittently conveyed web made of flexible material. Such sheets of flexible material with a certain inherent stiffness can, for example, be made of plastic, rubber, thin wood, paper or cardboard. Bulk goods can also be inexpensively produced from such webs in large quantities per unit of time if one only thinks of the packaging, for example.

A particular problem arises here in the field of liquid packs, in the preparation of which it is known to form a tube or a tube from the flat web pulled off a storage roll, which tube is filled and cut or first cut and then filled. When the material web along still no incision at any point having the conveying direction, ahnstückes for separating a _B from the other therefore introduce only a smooth average, the problem of the precise incision does not result in absolutely in such a critical manner as comparable, if the The piece of web to be processed already has creases, folds, cuts or perforations which must always be kept at a precise distance from the cut to be made. Sheets of flexible material have tolerances due to the physical property of the material Fluctuations, for example fluctuations in thickness, temperature, composition, etc. It is extremely complex to detect the specified cuts, creases, folds of the web or the like by means of electrical or optical measures in order to then cause a highly complicated control to precisely control the knife or knives to have the incision made at the desired location.

The object of the present invention is therefore to create a device for the precise introduction of a cut into such a web according to the type described at the outset, with which the accuracy of the interface can be achieved and maintained with simple means.

This object is achieved in that both the upper knife and lower knife are arranged on a swivel arm which can be moved by a control device, and that the control device cooperates with the material web to be cut in such a way that the interface is detected by the control device and in a movement of the Swivel arm is transmitted. The material web itself therefore has properties by means of which the control device immediately recognizes the location for making the desired cut. If the control device has detected the desired interface, the cutting device, which is arranged on a movable swivel arm, is brought by the latter to the desired interface.

It is particularly advantageous if the control device has a pneumatic cylinder with a movable piston which is articulated at one end of a control arm, that at the other end the articulated arm is articulated at its end, while at least one knife is attached to the other end of the articulated arm , and if the lever of the control arm is significantly smaller than that of the swivel arm. Instead of a pneumatic cylinder, a solenoid, an electrical control device or a hydraulic cylinder can of course also be used in practice, however, the use of a pneumatic cylinder has proven to be robust, simple and reliable. The swivel arm is therefore connected to this pneumatic cylinder via a control arm, with a lever ratio such that the swivel arm with the knives attached to it is considerably longer than the control arm. In this way, the force of the pneumatic cylinder, which ultimately acts on the knives, can be kept low without impairing the speed of movement of the swivel arm and its precise control. This small force ultimately acting in the cutting knives has the advantage that when the material web to be cut interacts on the one hand and the control device via the swivel arm on the other hand, the swivel arm to be controlled itself can be used as a sensing device, because a material web to be cut blows out of thin material in no way , Deformations, indentations or compressions. The pneumatic cylinder therefore only needs to receive a simple pilot control, which it puts on the swivel arm and at the same time receives control signals from it.

Particularly expediently, the invention is further embodied in that for the interaction of the material web and the control device on the material web, a stop is provided for a system of the swivel arm, which can be moved away from the control device and can be pivoted towards the stop before the cut into the stop. The stop on the material web can be created in a variety of ways. A wide variety of influences or treatments or changes in the material web take place in a continuous or intermittent machine. For example, in the case of an intermittently operating machine, an incision in the material web and an at least partial elevation of the material can take place before or after the incision in the conveying direction of the material web, so that this already gives a stop. The control device can then by the measures according to the invention on the swivel arm of such Mark the marked material web signals from the marking and then set up the measures to be taken. Preferably, according to the invention, the swivel arm is first moved away from the stop before the activity provided according to the invention, ie before the exact introduction of the cut, and then - preferably after reversing the direction of movement - is pivoted towards the stop. If, for example, the upper knife, the lower knife or both knives engage the stop on the material web, then the swivel arm is stopped, be it by the stop on the material web or by a control command in the control device, then the knife can immediately take action and Make the desired cut exactly where you want it.

It is expedient according to the invention if the stop on the material web is formed by at least one incision in the material web and folding it along at least one crease line running in the conveying direction of the material web. Especially when a tube is to be formed for the production of liquid packs, this overall tube, which corresponds to the length of the material web, must ultimately be divided or separated to form individual packs. It may be expedient to partially cut the tube when creating the superplasticizer and then to form the stop in the area of this incision by folding the material web in front of or behind the incision - as seen in the conveying direction of the material web. If exact folds or folds are desired at precisely predetermined locations in the material web, then crease lines are previously introduced in the material web in a manner known per se. Since a stop for the swivel arm according to the invention must have an edge transversely to the conveying direction of the material web, the folding should also take place transversely to the conveying direction of the material web, ie around a crease line in the conveying direction of the material web.

For the reasons mentioned above, the device according to the invention can be used particularly advantageously for separating partially cut, connected tube pieces which are formed from a coated paper web. A tube, hose or tube has the shape of a circle in cross section in the finished state. The stop in the material web can now be obtained particularly simply and advantageously when making partial incisions in such a tube in that the creasing lines which run along the tube surface lines are not arranged exactly on diametrically opposite sides. If you put a plane through the crease lines of such a tube or tube in your thoughts, then according to the teaching of the invention, this plane should not run exactly through the center line (or the center point of the circle), but should be somewhat eccentric to it. In this way it is possible that when the tube is partially compressed in the direction transverse to its longitudinal axis, one path comes closer to the shape of a plane than the other, because viewed in cross-section, it is not halves of equal length but sections of unequal length . Preferably this is a section, e.g. the longer section seen in cross section, cut, and the short section, already lying in one plane, uncut. Then these tube pieces hang together along the flat part and are cut along the partially curved, longer section. To separate the last cut must then be made exactly under the existing cuts. In order to achieve this, the device of the type described above offers, so to speak, a "searching knife" because the knife parts attached to the swivel arm search for the stop itself and thus for the point at which the finite average for separating or separating the tube pieces is to take place.

It can be seen from the above considerations by what simple means a device for making a cut very precisely and precisely on a desired one th place of a material web is created.

• Figur 1 schematisch im Schnitt eine Materialbahn und die Schneidvorrichtung mit ihrer abgebrochen gezeigten Halterung,
• Figur 2 perspektivisch einen abgebrochenen Teil der Mate- .rialbahn, wenn man von unten auf diese blickt,
• Figur 3 eine Seitenansicht dieser Materialbahn, wenn man z.B. von rechts vorn nach links oben in Figur 2 blickt,
• Figur 4 eine Draufsicht auf den Zuschnitt der Materialbahn vor der Faltung zum Tubus nach Figur 2,
• Figuren 5a und 5b schematische Querschnittsansichten einer schlauchförmigen Bahn im zusammengedrückten bzw. ungefalteten Zustand,
• Figuren 6a und 6b gleiche Darstellungen wie Fig. 5a und 5b, wobei jedoch die Rillinien an anderer Stelle in der Bahn angeordnet sind.
• Figur 7 eine Seitenansicht der Schneidvorrichtung nach einer bevorzugten Ausführungsform mit Pneumatikzylinder und
• Figur 8 eine Draufsicht auf die Messer mit Halterung und Materialbahn.

Further advantages, features and possible uses of the present invention result from the following description in connection with preferred exemplary embodiments. Show it:

• FIG. 1 shows schematically in section a material web and the cutting device with its holder shown broken off,
• FIG. 2 is a perspective view of a broken-off part of the material web when one looks at it from below,
• 3 shows a side view of this material web, for example if one looks from the front right to the top left in FIG. 2,
• FIG. 4 shows a plan view of the cut of the material web before folding into the tube according to FIG. 2,
• FIGS. 5a and 5b show schematic cross-sectional views of a tubular web in the compressed or unfolded state,
• FIGS. 6a and 6b are the same representations as FIGS. 5a and 5b, but with the creasing lines being arranged elsewhere in the path.
• Figure 7 is a side view of the cutting device according to a preferred embodiment with pneumatic cylinder and
• Figure 8 is a plan view of the knife with holder and web.

FIG. 1 shows schematically the lower knife 1 and the upper knife 3 pivotably articulated on the axis of rotation 2, which is attached to a swivel arm 4. In between you can see the schematic cross-section of a path formed into a tube or tube with thick lines.

This path is shown even more clearly in perspective in FIG. 2 and in a side view in FIG. 3. To simplify the explanation of the invention, the web is in the illustration tion of Figures 2 and 3 turned upside down, ie the flat side lying in cross section in Figure 1 is in Figures 2 and 3 above. The material web is generally designated 5 and should move in the direction of arrow 6. It consists of flexible material, in the embodiment shown in the drawings a relatively thick paper coated on both sides with plastic, as is used, for example, for the production of liquid packs. A cut 7 is to be made in this coated paper, which extends from one longitudinal edge of the flat web side to the other. On the opposite side shown in the cross-sectional view of FIG. 2, one can see the overlap point 8, at which the material web was shaped and welded to form the tube before being laid flat to form the flat part. From the side edges just described, which lie along creasing lines 25 (FIG. 4), in FIG. 2 reaching down to the overlap point 8, one can see the cut edges or incisions 9, 9 '. At the right end of the first left tube piece of FIG. 2, these incisions 9 and 9 'can again be seen as dashed lines, because these cuts lie below the flat surface of the web 5 facing the viewer. In FIGS. 2 and 3, two dash-dotted lines 10 10 ′ run transversely to the conveying direction 6 of the material web 5. The distance between these two lines represents the tolerance range for making the cut in the web 5. Normal milk or fruit juice packs are involved here by a length of, for example, 3 mm. In this area between the two lines 10 and 10 ', the incision 7 must ultimately be made. It should connect exactly to the two incisions 9, 9 ', so that the individual tube pieces of the total track 5 are separated at one and the same interface.

FIG. 4 shows the top view of a flat web made of paper coated with plastic, ie flexible material, the conveying direction of which is again shown by arrow 6. The path shown in Figure 4 is in three Parts divided, from which three tube pieces and ultimately three packages are later formed according to the last average. From the right-hand first third of the web one can see the embossing which runs across the entire width and is generally designated 11, with the aid of which a bottom or lid of the pack can later be formed. Two parallel creasing lines 25 can be seen transversely to the embossing strip 11, that is to say in the conveying direction 6 of the web 5.

Left at a distance a from the pre efeld ^g 11 extend two transverse to the conveying direction 6 notches 9, 9 'which extend from the outer edge to the respective score line 25th Parallel to the embossing field 11, the area to the right of the incisions 12 with the width a later results in a transverse sealing seam for closing the package.

If the middle third of the web shown in FIG. 4 is moved to the left by a further feed in direction 6, the material web 5 is folded up along the creasing lines 25 upwards towards the viewer, the lower field shown in FIG. 4 first and then the upper one Field can be folded in or folded up. The left third is then shown in FIG. 4, again showing the overlap point 8. As a result of the incisions 9 and 9 ', the width of the material web 5 around these side panels has decreased.

If the material web 5 then advances further to the left in the conveying direction 6, then the above-mentioned average 7 should take place on the line shown by the arrow 7 in FIG. 4, which is exactly in line with the incisions 9 and 9 '.

So that the control device can cooperate with its swivel arm 4 with the material web 5, so that the cut 7 lies exactly in line with the incisions 9, 9 ', a stop 12 is formed by the material web 5 itself, this stop 12 being the most obvious Figure 7 ago going on. It is created by holding down the left tube part shown in FIG. 7 and keeping the tube part lying to the right of the upper knife 3 free or popping open.

The inventive idea of how the cross-section of the tube shown in FIGS. 1 and 2 can be achieved is to be explained beforehand with reference to FIGS. 5 and 6. The cross section of the tube is shown as a circle in FIGS. 5b and 6b. At the points shown by the arrows 13, the creasing lines 25 are to be located, which run transversely to the plane of the paper and are therefore practically not visible in FIGS. 5 and 6. If an imaginary plane is laid through the creasing lines, the plane 14 shown in FIGS. 5b and 6b and shown by a dashed line is obtained. It can be seen that the person skilled in the art will arrange the creasing lines 25 in such a way on diametrically opposite sides to lay an initially round tube would that the imaginary plane 14 runs through the central longitudinal axis 15. However, this would have the disadvantage that when the hose or hose piece was laid flat in the state of FIG. 5a, two sides of the same length would result, which after laying flat have no different paper tension or spring force.

However, if the creasing lines 25 are arranged according to the arrows 13 at the point shown in FIG. 6b so eccentrically to the center of the tube so that the imaginary plane 14 does not run through the central longitudinal axis 15 of the tube, then the state of FIG. 6a results when laying flat with a lower shorter and an upper longer one, ie arched part. If one squeezes such a hose, which is shown schematically in cross section in FIG. 6a, the upper larger surface always strives to bulge into the position shown in FIG. 6a.

According to the above statements, one now has in the upper curved region of the hose in the state of FIG. 6a the incisions 9 and 9 '(see FIG. 2) are provided and the tube piece intended for the observer when viewing FIG. 6a is held flat above the paper plane and thus above the incisions 9 and 9', while the other is held backwards from the paper plane 6 is left in its unloaded state, then the viewer must find the state of FIG. 6a, ie the incisions 9, 9 'lie in the upper, longer, curved part, which thus represents the stop 12 shown in FIG.

According to FIG. 7, the material web 5, driven by drive rollers 16, runs from left to right into the cutting device in the conveying direction of arrow 6. The left tube part already provided with the incisions 9 and 9 'is held down by the feed rollers 16, i.e. in the flattened state, as can be seen at the point of engagement of the two feed rollers 16. Not only the holder 18 for the feed rollers 16 but also the holder 19 for a pneumatic cylinder 20 with a piston 21 are attached to the carrier 17. At the articulation point 22, the piston 21 is articulated on the left end 23 of a control arm 24, while the latter can be pivoted about an axis of rotation 26 provided on its right end 25. The swivel arm 4 is also pivotably articulated about this axis of rotation 26, which in the illustration in FIG. 7 is suspended downward and is connected at its lower end 27 to the upper knife 3 and via the articulation point 2 (FIG. 1) to the lower knife 1. Swivel arm 4 and control arm 24 consist of a rigid piece. From FIG. 7 it can be seen how the right edge of the upper knife 3 is brought into abutment against the stop 12 of the right part of the material web 5. In this state, the cut 7 can be made in the flat surface of the material web 5, the cut 7 then certainly being precisely aligned with the cuts 9, 9 '.

FIG. 8 shows the top view of the part of the cutting device shown in FIG. 7, the upper part here Feed roller 16 and the material web 5 with the overlap point 8 and the incisions 9, 9 'can be seen. To simplify the illustration, the upper knife 3 and swivel arm 4 are omitted, so that only the lower knife 1 and its articulation point 2 for the upper knife can be recognized. The tube piece is bulged to the right of the stop designated by 12, so that it has the cross-sectional state according to FIG. 2 on the left or 6a, while to the left the tube piece is still relatively compressed under the feed rollers 16.

In operation, the cutting device works in such a way that the swivel arm 4 is pivoted to the left about the axis of rotation 26 in the direction shown in FIG. to immediately turn right again, ie in Figure 7 counterclockwise, at a speed that is greater than the conveying speed of the material web 5. In this way, the swivel arm 4 can then move with its upper knife 3 against the material web having incisions 9, 9 ', which is stopped in the state of FIG. 7 by control means (not shown). The force of the pneumatic cylinder is so weak about the ratio of the short lever of the control arm 24 above and the long lever of the swivel arm 4 below that when the upper knife 3 approaches the stop 12, the latter is not damaged. Due to the small force acting in the upper knife 3, the swivel arm 4 is stopped in the position shown in FIG. 7, and then the control signal for making the incision 7 takes place.

Claims (6)

1. Device for the precise introduction of a cut (7) into a web (5) made of flexible material, with a lower knife (1) and an upper knife (3) rotatably articulated thereon, at least one of which is driven, and with a feed device ( 16) for the material web (5), characterized in that both knives (1, 3) are arranged on a swivel arm (4) which can be moved by a control device (3, 4, 20), and in that the control device (3, 4, 20) cooperates with the material web (5) to be cut in such a way that the interface (7) is detected by the control device (3, 4, 20) and transmitted into a movement of the swivel arm (4). 2. Device according to claim 1, characterized in that the control device (3, 4, 20) has a pneumatic cylinder (20) with a movable piston (21) which is articulated at one end (23) of a control arm (24) that at the other end (25) of the swivel arm (4) is articulated at one end, while at least one knife (3) is attached to the other end of the swivel arm (4), and that the lever (22 - 26) of the control arm (24 ) is significantly smaller than that (26 - 3) of the swivel arm (4). 3. Apparatus according to claim 1 or 2, characterized in that for the interaction of the material web (5) and control device (3, 4 20) on the material web (5) a stop (12) is provided for a system of the swivel arm (4) , which can be moved by the control device (3, 4, 20) before cutting into the stop (12) and swiveled towards the stop. 4. Device according to one of claims 1-3, characterized ^g e-indicates that the stop (12) on the material web (5) through at least one incision (9, 9 ') in the material web (5) and folding the same lengthwise at least a crease line (25) extending in the conveying direction (6) of the material web (5) is formed. 5. Use of the device according to one of claims 1 to 4 for separating partially incised, attached tube pieces, which are formed from a coated paper web (5). 6. The device according to claim 1 to 5, characterized in that the control arm (24) is designed in one piece with the swivel arm (4).

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