EP0727290A1 - An apparatus for feeding a web of wrapping material and for severing the material in lengths in a packaging machine and a method for controlling the same - Google Patents

Abstract

The advancing and cutting appts. uses a strip (12) which is unwound from a reel (11) and passed between motor-driven feed rollers (16,17) to the cutter (18) which comprises a fixed blade (19) and a moving blade (21) on a rotary shaft (20). The rotational speed and angular position of the shaft are maintained in direct proportion to those of the feed rollers by rigid coupling of the respective drives so that the lengths (A) cut from the end of the strip are equal. When the machine comes to a standstill, the blade and feed rollers are stopped simultaneously and restarted in synchronism.

Description

The invention relates to a device for feeding a wrapping material web and for separating individual wrapping material sections from the wrapping material web for a packaging machine, with a feed device with at least one feed roller driven by a feed drive motor and with a cutting device driven by a knife drive motor. The invention is further directed to a method for controlling the advance of a wrapping material web and for separating individual sections of wrapping material from the wrapping material web for a packaging machine.

Such a device and such a method are known from DE-OS 31 14 470. In this known device the wrapping material web runs off a continuously driven roll and forms a buffer loop before it is fed intermittently by a pair of feed rollers to a cutting device which separates the individual material sections from the material web by means of a reciprocating cutting knife. The buffer loop serves to enable the transition from the material web running continuously from the roll to the intermittent operation of the cutting device. It is also possible to stop the cutting device for one work cycle in the absence of an object to be wrapped in the packaging machine, but the material web continues to run from the supply roll and the length of the material web that has expired is stored in the buffer loop until an object to be packaged is again in the packaging machine is available.

The buffer loop in the known device is necessary in order to enable the high accelerations required each time the material web is fed again by the intermittently working feed rollers. The control for the buffer loop is very complex with several pairs of photo elements and is particularly prone to malfunctions if no object to be packed is present in the packaging machine in several successive work cycles. Another disadvantage of the known device is that the advanced sheet material tends to stick to the reciprocating knife after a cut. This also frequently leads to disruptions in the operating sequence of the known machine.

It is also already a method for providing wrapping sheets for individual articles such as candies or the like. known (DE 42 22 203 C2), in which one wrapping sheet after the other is cut off from a wrapping material web with a continuously operating knife. In the event of malfunctions in the supply of the pieces to be packed, wrapping sheets may no longer be fed to the packaging station. This is achieved in the known method in that, after the last wrapping sheet has been cut off, the feed rollers for the wrapping material web are braked within the next working cycle and turned back by an amount equal to that caused by the inertia the feed device corresponds to too much advanced web length. This is necessary because the knife continues to operate to cut the individual wrapping sheets and is not stopped. When pieces to be rewrapped are then delivered, the wrapping material web must be accelerated very strongly and passed through the cutting station so that the next time the knife is cut, a full length wrapping sheet is available for wrapping a product.

However, this known method has the disadvantage that when the material web is conveyed backwards, its tension drops sharply and a material web loop is formed which has to be caught and stabilized with an additional device. When the wrapping material web is restarted, this loop must first be removed again and the material web must be advanced at a speed far above the average web speed. Here, not only is the material web subjected to high stresses, but vibrations also occur slightly as a result of the material web being moved back and forth, which leads to excessive noise. In addition, the enormous dynamics in the return and advance of the material web result in fluctuations in the length of the individual wrapping material sections.

The object of the invention is to provide a generic device and to provide a method with which the disadvantages mentioned are avoided and with which it is possible to continuously advance the wrapping material web in a particularly simple manner and to separate uniformly large sections of wrapping material therefrom without causing disruptions in the operating sequence is coming.

This object is achieved with the device according to the invention in that the cutting device has at least one revolving knife, the drive of which is coupled to the drive for the feed roller and its rotational speed and the angle of rotation are directly proportional to the speed of rotation or the angle of rotation of the feed roller.

This configuration has the advantage that it is possible by means of the rotating knife to continuously advance the wrapping material without the feed of the material having to be slowed down or even stopped during the cut. Since the revolving knife only engages with the wrapping material at the time of the cut, it does not result in the knife sticking to the wrapping material. If the feed speed of the roller fluctuates, the rotational speed of the rotating knife changes proportionally with the rotational speed of the feed roller due to the coupling of the drives of the roller and knife with a certain proportionality factor, so that sections of the same length are always cut off regardless of the feed speed of the wrapping material web.

It is particularly advantageous if the drive motors for the feed roller and for the cutting device are coupled to one another via an electronic control device and can be controlled by the latter. The control device, which is expediently coupled to a rotary encoder arranged on a main shaft of the device, enables particularly simple coupling of the drive motors for the knife shaft and the feed roller without complex mechanical devices.

If the control device has an adjusting device for adjusting the proportionality factor between the speed of the feed roller and the rotating knife, the length of the wrapping material sections to be cut can be adjusted particularly easily and quickly, so that the entire device can be readjusted easily and in a very short time and so on it is possible to pack products of different sizes in the downstream packaging machine with practically no changeover time, for which wrapping material sections of different sizes have to be fed. If the Wrapping material web is provided with imprints or printing marks for each section of wrapping material, it is easily possible with the setting device to set the circumferential knife when setting up the device or threading a material web so that it always cuts the material web at the right place between two imprints or printing marks .

The device can expediently be provided with a tear thread cutting device with a driven, rotating tear thread knife. With the tear thread cutting device it is possible to separately cut a tear thread arranged on the wrapping material web, with the aid of which the packaged product can be easily removed from the wrapper by the consumer, the cut of the tear thread being able to lie a little next to the cut that is then carried out by the rotating knife to separate the individual sections. It is particularly advantageous if the tear thread knife is driven by the knife drive motor for the cutting device, since this saves a separate separate drive for the tear thread knife and it is always ensured that both knives are driven synchronously.

It is particularly advantageous if a print mark reader, which is coupled to the electronic control device, is arranged in the direction of travel of the wrapping material web in front of the cutting device. In this case, it is possible with a wrapping material web provided with printing marks to automatically control or regulate the feed roller or the rotating knife in such a way that the printing mark or the printing on the web is exactly in the correct position when the knife cuts off a material section. The arrangement is expediently such that the rotary encoder displays the current angle of rotation of the main shaft and transmits it as a setpoint to the control device, and that the print mark reader recognizes the print marks printed on the wrapping material web and as Actual value transmitted to the control device, and that the control device controls the speed of the feed drive motor for the feed roller depending on the result of a setpoint-actual value comparison.

The device is preferably provided with a detection device in order to determine whether a product to be wrapped is present in the packaging machine arranged downstream. The detection device delivers a signal to the control device when there is no product to be packed in the packaging machine. The control device can then immediately stop the drives for the feed and the rotating knife as a result of this signal, so that no wrapping material section is then fed to the packaging machine. This prevents paper jams or other malfunctions in the packaging machine and no material is wasted.

The feed device expediently consists essentially of a driven feed roller and a co-driven counter roller which rotate in opposite directions and thereby guide and advance the wrapping material web between them. The drive motors for the feed roller and the cutting device are preferably servomotors which are very reliable, robust and particularly easy to control.

According to the method according to the invention, the wrapping material web is advanced from the feed device with at least one feed roller driven by a feed drive motor, and in each work cycle of the packaging machine arranged subsequently, a wrapping material section is separated from the advanced wrapping material web by a cutting device which has at least one rotating knife driven by a knife drive motor. wherein the drive motors are controlled by an electronic control device so that the speed and angle of rotation of the rotating knife are directly proportional to the speed or angle of rotation of the feed roller.

A particularly advantageous embodiment of the method according to the invention results if, in the absence of an object to be wrapped in the packaging machine, the feed device advances the wrapping material web a piece forming a partial length of a wrapping material section and then stops it, while at the same time retracting the rotating knife by a certain angle of rotation the last cut made is further rotated and stopped in a certain STOP position, and when the drives for the feed roller and the knife in the STOP position are switched on again when an object to be wrapped is again found in the packaging machine in order to achieve the to advance the next length of wrapping material still missing length of wrapping material.

This has the advantage that, when restarting after an empty cycle in which no material section has been fed to the packaging machine, the wrapping material web has to be advanced a shorter distance to the next cut, since after the cut before the empty cycle it has continued a little further. While the feed and knife are idle, the knife is out of engagement with the wrapping material web, so that it cannot adhere to the wrapping material.

The coupling of the feed roller and the rotating knife always ensures that the packaging machine - material sections of the same length are always fed at the correct cycle time if there are objects to be packaged in the packaging machine.

The STOP position of the rotating knife is suitably between an angle of rotation of the knife shaft 20 ° and 150 ° after the previous cut. In this area, it is particularly possible to stop the knife after an empty cut cycle and to accelerate it again to its normal rotational speed when starting again until the next cut.

The angle of rotation for the STOP position is expediently adjustable and can thus be optimally set for different lengths of the material sections.

Fig.1

eine Vorrichtung zum Vorschub einer Einwickelmaterialbahn und zum Abtrennen einzelner Materialabschnitte nach der Erfindung, in einer schematischen Darstellung; und

Fig.2

einen die Vorschubwalzen und die Schneideinrichtung darstellenden Ausschnitt der Fig.1 in einer vergrößerten Darstellung.

Further features and advantages of the invention result from the following description and the drawing, in which a preferred embodiment of the invention is explained in more detail using an example. It shows:

Fig. 1

a device for feeding a wrapping material web and for separating individual material sections according to the invention, in a schematic representation; and

Fig. 2

a detail of the feed rollers and the cutting device of Figure 1 in an enlarged view.

In the drawing, 10 denotes a device for feeding a wrapping material web and for separating individual material sections from the web for a packaging machine (not shown in more detail).

A roller 11 is arranged on the device 10, from which the wrapping material web 12 runs and is guided via deflection rollers 13 to a feed device 14. The feed device 14 essentially consists of a feed roller 16 driven by a feed drive motor 15 and a counter-roller 17 which is also driven, between which the material web 12 runs in the direction of the arrow F. In Passage direction F behind the feed device 14 is a cutting device 18 which essentially consists of a fixed counter knife 19 and a rotating knife 21 arranged on a knife shaft 20. The knife shaft 20 with the knife 21 arranged thereon is driven by a knife drive motor 22 and rotates in the same direction of rotation as the counter-roller 17, as is indicated by the arrows G and G '. After each complete rotation of the knife shaft 20, that is to say every time the rotating knife 21 passes the fixed counter knife 19, a wrapping material section A is separated from the material web 12.

Arranged in the direction of travel F in front of the feed device 14 is a print mark reader 23 scanning the wrapping material web 12, and between this and the feed device 14 a tear thread cutting device 24, which is also driven by the knife drive motor 22.

The print mark reader 23 is connected to an electronic control and regulating device 26 via a first signal line 25. The control device 26 is also connected via a second control line 27 to a rotary encoder 28 (only shown schematically) which is arranged on a main shaft and which transmits the respective current angle of rotation of the main shaft to the control device via the second signal line 27. Furthermore, the control device is connected via a third control signal line 29 to a detector device 30 arranged on the packaging machine, which detects whether there is an object to be packed, for example a candy, in the packaging machine and which transmits signals corresponding to the control device.

des Winkels δ. In Fig.2 sei angenommen, daß die Vorschubwalze 16 bei jeder vollständigen Umdrehung der Messerwelle 20 um einen Winkel δ von 180° weiterdreht, die Länge eines Materialabschnitts A also die Hälfte des Umfangs der Vorschubwalze beträgt. Wenn die Messerwelle 20 um einen Winkel Θ von 60° weitergedreht wird, dreht die Vorschubwalze im selben Zeitraum um einen Winkel δ

von 30°. Der Proportionalitätsfaktor zwischen Drehwinkel Θ der Messerwelle und Vorschubwinkel δ der Vorschubwalze beträgt in diesem Falle also 2:1 und ist zu jedem Zeitpunkt der einzelnen Arbeitstakte der Maschine konstant.The control device 26 controls the drive motors 15 and 22 for the feed roller 16 and the rotating knives 21, 24 as a function of the current angle of rotation of the main shaft, via a fourth or a fifth control line 31 or 32 Signals from the print mark reader 23 and the detector device 30, the rotational speed and the rotational angle of the rotating knife 21 being directly proportional to the rotational speed or the rotational angle of the feed roller 16. This means that the feed rollers 16 and 17 always rotate by the same angle δ with every complete 360 ° rotation of the knife shaft 20. When the knife shaft is rotated by a partial amount Θ of a complete revolution, the feed roller rotates by a corresponding partial amount δ

of the angle δ. In FIG. 2 it is assumed that the feed roller 16 rotates by an angle δ of 180 ° with each complete revolution of the knife shaft 20, that is to say the length of a material section A is half the circumference of the feed roller. If the knife shaft 20 is rotated further by an angle Θ of 60 °, the feed roller rotates by an angle δ in the same period

of 30 °. The proportionality factor between the rotation angle Θ of the knife shaft and the feed angle δ of the feed roller is 2: 1 in this case and is constant at all times of the individual work cycles of the machine.

If the detector device 30 detects that no candy or the like is in the packaging machine. is present, it transmits a corresponding signal to the control device 26 via the third control line 29. The control device then brakes the drives 15, 22 for the feed roller 16 and the knife shaft 20 and at the same time stops them, so that the knife shaft 20 is in a STOP Position Θ after the last cut and the

stehenbleiben. Die Materialbahn ist hierbei bereits um eine Teillänge l eines Materialabschnittes A vorgeschoben worden, die dem dem Winkelbetrag δ

entsprechenden Umfangsteil ñ der Vorschubwalze 16 entspricht.Feed roller after turning further by the proportional angle amount δ

stop. The material web has already been advanced by a partial length l of a material section A that corresponds to the angular amount δ

corresponding circumferential part ñ corresponds to the feed roller 16.

When the detector device 30 again detects a candy in the packaging machine, it transmits a corresponding signal to the control device 26. This then switches on the servomotors 15, 22 for the rotating knife and the feed roller 16 again at the same time, the rotational speeds or angles of rotation of which rotate Components also when restarting, ie Accelerating the motors are always proportional to each other.

If the material web 12 is provided with imprints or print marks, the print mark reader 23 can recognize these print marks and transmits signals to the control device 26 as actual values. The control device 26 compares these actual value signals with the signals from the rotary encoder 28 which form the setpoint for the position of the print marks and controls the feed drive motor 15 for the feed roller 16 so that the print marks are in the correct position on the material web 12 when the rotating knife has a material section A. separates from the web 12. This means that the strict coupling with a fixed proportionality factor between knife drive and feed drive can be removed until the print marks scanned by the print mark reader 23 are in correct position when the knife cuts. In this way, it is easily possible to set up the machine again, for example when the roll 11 is replaced with the wrapping material 12.

If the material web 12 is provided with a tear thread, this can be severed with the tear thread cutting device 24 in a manner known per se for the individual material sections before the web 12 is advanced by the feed rollers 16, 17 to the cutting device 18. Since the length of a tear thread on a material section A is usually the same length as the section itself, the tear thread cutting device is driven by the knife drive motor 22 at the same rotational speed as the knife shaft 20 for the revolving knife 21 and, exactly like this, is stopped when none during a work cycle Candy is found in the packaging machine.

The invention is not limited to the exemplary embodiment shown and described, but several changes and additions are possible without leaving the scope of the invention. For example, it is possible to equip the knife shaft with several knives, so that several material sections are cut off with one complete rotation of the knife shaft. Furthermore, the device can also be provided with a plurality of rollers 11, so that it is possible to quickly change one material web for another. The roller 11 can be driven with its own roller drive, which is also controlled by the control device and which, depending on the tension of the material web, accelerates, brakes or turns back the roller. The device can be used for both continuous and intermittent packaging machines.

Claims (15)

Device for feeding a wrapping material web and for separating individual wrapping material sections from the wrapping material web for a packaging machine, with a feed device with at least one feed roller driven by a feed drive motor and with a cutting device driven by a knife drive motor, characterized in that the cutting device (18) has at least one rotating knife (20, 21), the drive (22) of which is coupled to the feed drive motor (15) for the feed roller (16) and whose rotational speed and angle (Θ) are directly proportional to the rotational speed or angle (δ) of the feed roller (16) are. Apparatus according to claim 1, characterized in that the drive motors (15 and 22) for the feed roller (16) and for the cutting device (18) are coupled to one another via an electronic control device (26) and can be controlled by the latter. Device according to claim 1 or 2 , characterized in that the control device (26) is coupled to a rotary encoder (28) arranged on a main shaft of the device (10). Device according to one of claims 1 to 3, characterized in that the control device (26) has an adjusting device for adjusting the proportionality factor between the speed of the feed roller (16) and the speed of the rotating knife (20, 21). Device according to one of claims 1 to 4, characterized by a tear thread cutting device (24) with a driven, rotating tear thread knife. Device according to one of claims 1 to 5, characterized in that the tear thread cutting device (24) is driven by the knife drive motor (22) for the cutting device (18). Device according to one of claims 1 to 6, characterized in that a print mark reader (23) is arranged in the direction of travel (F) of the wrapping material web (12) in front of the cutting device (14). Device according to one of claims 1 to 7, characterized in that the rotary encoder (28) displays the current angle of rotation of the main shaft and transmits it as a setpoint to the control device (26), and in that the print mark reader (23) prints print marks printed on the wrapping material web (12) recognizes and transmits it as an actual value to the control device (26) and that the control device (26) regulates the speed of the feed drive motor (15) for the feed roller (16) as a function of the result of a setpoint / actual value comparison. Device according to one of claims 1 to 8, characterized by a detection device (30) for determining whether a product to be wrapped is present in the subsequent packaging machine. Device according to one of claims 1 to 9, characterized in that the feed device (14) consists essentially of the driven feed roller (16) and a counter-roller (17) driven with it. Device according to one of claims 1 to 11, characterized in that the drive motors (15, 22) for the feed roller (16) and for the cutting device (18) are servomotors. Method for controlling the feed of a wrapping material web and for separating individual sections of wrapping material from the wrapping material web for a packaging machine, characterized in that the wrapping material web (12) is fed by a feed device (14) with at least one feed roller (16) driven by a feed drive motor (15) and in each work cycle of the packaging machine, a wrapping material section (A) is separated from the advanced wrapping material web (12) by a cutting device (18) which has at least one rotating knife (20, 21) driven by a knife drive motor (22), the drive motors (15, 22) can be controlled by an electronic control device (26) so that the rotational speed and the rotational angle (() of the rotating knife (21) are directly proportional to the rotational speed or the rotational angle (δ) of the feed roller (16). A method according to claim 12, characterized in that in the event of the absence of an object to be wrapped in the packaging machine, the feed device (14) advances the wrapping material web (12) a little further, forming a part length ( l ) of a wrapping material section (A), and then stops it, while at the same time the rotating knife (20, 21) is rotated further by a certain angle of rotation after the last cut, and stopped in a certain STOP position (Θ), and that the drives (15, 22) for the feed roller (16) and the knife (21) located in the STOP position (Θ) can be switched on again when an object to be wrapped in the Packaging machine is determined to advance the remaining length of wrapping material web (12) still missing for the next wrapping material section (A). A method according to claim 12 or 13, characterized in that the STOP position (Θ) of the rotating knife (21) at an angle of rotation of the knife shaft (20) is between 20 ° and 150 ° after the previous cut. Method according to one of claims 12 to 14, characterized in that the angle of rotation for the STOP position (Θ) is adjustable.

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