EP0489400B1 - Wiper mecanism for a packaging machine forming tubular sleeves - Google Patents

Abstract

The invention relates to a stripper mechanism for a tubular bag packaging machine, in which a foil strip (1) is formed into a tube (3) by means of a longitudinal sealing jaw (2) and is formed into bags by means of cross-sealing jaws (4). A stripper mechanism (5) is arranged in the area of the cross-sealing jaws (4), which stripper mechanism (5) includes two stripper rods (6) supported on the end areas of support arms (7). In order to provide a drive for the stripper mechanism (5), which drive is independent of the drive of the cross-sealing jaws (4), the stripper rods (6) are connected to a common closing mechanism (8), and that furthermore the stripper rods are connected to a moving mechanism (9) for effecting a relative movement along the foil tube (3).

Description

The invention relates to a stripper device for a tubular bag packaging machine, with two stripper tools arranged on both sides of the movement path of the tubular bag, which are movable by means of a drive device.

In the case of a tubular bag packaging machine, a film strip is passed over a shaped shoulder and, by means of a longitudinal sealing device, is formed into a hose which encloses a filling tube or format tube through which the product to be packaged can be introduced into the film tube. The individual bags containing the product are each closed by means of a bottom or top seam, the top seam of the preceding bag and the bottom seam of the following bag being formed at the same time. A device of this type is previously known, for example, from US-A-4,663,917.

US-A-4,391,081 shows a stripper device for a tubular bag packaging machine in which the movement of the stripper tools and the cross-sealing jaws is coupled to one another. The cross welding jaws can be moved via a four-bar mechanism or scissor mechanism, the up and down movement of the stripper tools being caused by the opening and closing movement of the cross welding jaws. Due to the rigid coupling of the up and down movement of the stripper tools, this embodiment of the invention does not allow any adaptation and optimization of the stripping process with regard to the sealing process.

When forming the top seam and the bottom seam by means of a pair of cross sealing jaws, it is necessary to keep the sealing area of the film tube free of remnants of the goods to be packaged. Especially with bulky goods, such as potato chips, there is a risk that after filling the bag, which is closed by the bottom seam and is still open at the top, the product will not fall evenly into the bag. For this reason, stripper tools are used, which, usually in the form of a pair of bars, are stripped down along the bag in order to transport the product completely into the bag and out of the area of the bottom and top seam.

Due to the technical process of such a tubular bag packaging machine, in which the film tube runs essentially continuously through the machine, it is necessary that the stripper device is designed in its movement sequence so that the stripper tools can perform a stripping movement in addition to the movement speed of the film tube. It is also necessary for the system to carry out the stripping process in the closing area of the cross sealing jaws. The stripper device must therefore be introduced with the cross sealing jaws open in the space formed between them and the film tube. The stripper tools are then closed and thus placed against the film tube and then moved downwards. This means that the cross sealing jaws must remain open while the stripper device is in use. The cycle time available thus limits the cross sealing time and the time in which the stripper device is in use.

The invention has for its object to provide a stripper device of the type mentioned, which with a simple structure and reliable usability allows adjustment of the speed of movement of the stripper device so that the time for the stripping process and the sealing process can be maximized.

According to the invention the object is achieved by the features of the main claim, the subclaims show further advantageous embodiments of the invention.

The stripper device according to the invention is distinguished by a number of considerable advantages. Since, according to the invention, the stripper tools are mounted on a carriage which can be moved by means of the crank drive, it is possible to move the stripper tools directly into or remove them from the gap between the open cross weld jaws in relation to the movement of the cross welding jaws. This avoids, on the one hand, that the stripper tools collide with the cross-welding jaws, and, on the other hand, no additional control and / or drive means need to be provided in order to actuate the stripper device itself.

According to the invention, the drive of the cross welding jaws and the drive device of the stripper tools are coupled out of phase with one another to form a common drive. This makes it possible to actuate both groups of components by means of a common drive. This leads to a considerable simplification of the tubular bag packaging machine. The phase-shifted coupling results in a precisely adapted and set movement sequence. It is thus ensured that the linear stripper movement is out of phase with the circular movement of the cross sealing jaws. The cross sealing jaws are each mounted on bearing levers which carry out an essentially circular arc-shaped rotary movement, so that the sealing jaws are moved on a circular path, preferably on a D-shaped circular path, which is flattened in the direction of the film bag. The stripper tools are opened and closed during a cycle, ie separated from the film tube or placed against it for stripping. A further movement of the stripper tools takes place in the longitudinal direction of the film tube, this movement of the stripper tools taking place at a high speed in order to strip off the bag. For this purpose the carriage on which the stripper tools are mounted is moved back and forth in the longitudinal direction of the longitudinal axis of the bag, this movement being generated, for example, by a crank operation which is coupled in terms of drive with the rotary movement of the levers for mounting the cross-sealing jaws. A crank mechanism is also connected to the crank mechanism, which causes the stripper tools to open and close. The stripper device is discussed in detail below.

Furthermore, a very important advantage of the invention results from the fact that the crank drive comprises means for changing the crank stroke. It follows that the crank stroke during one revolution, i.e. does not remain constant in the usual way during a work cycle. This opens up the possibility of carrying out the longitudinal movement of the slide at different speeds. The stripper device can thus be inserted at a slow speed upwards into the space between the open cross sealing jaws, while the stripping or stripping stroke directed downwards can take place at a relatively high speed. The time portions of a cycle that can neither be used for the transverse sealing process nor for the stripping process can thus be minimized.

The stripper tools can preferably be actuated with a cam drive device, wherein a cam track or cam disc can be used. This eliminates the need for an additional drive, so that this also results in a significant simplification of the overall design. This means that only one drive is used to drive the sealing jaws and to synchronize the stripper tools.

Furthermore, it can be advantageous if safety catches are provided, which can be curved in order to close the stripper rods in good time if the closing pulse is not triggered in good time or is completely absent. This is particularly important if the air supply for the locking cylinder is not working properly.

Furthermore, it can be advantageous if a safety circuit is used which controls the drive device of the stripper tools and the drive of the cross welding jaws. This safety circuit preferably comprises a sensor which checks the opening or closing process of the stripper tools. If the synchronization between the dosing device and the packaging machine fails, it can happen that a bag is filled with product due to a triggered double fill in the sealing area. In this case, the stripper tools hit a bulging bag and are unable to push the product down. The stripper tools thus inevitably remain in the open position. The cross-welding jaws subsequently put into operation would now hit the stripper tools and destroy the entire mechanism. To prevent this, a sensor is used, for example in the form of an inductive sensor, which is mounted on the pneumatic cylinder for actuating the stripper tools. The piston of the pneumatic cylinder can, for example, be provided with a magnetic material which generates a signal in the inductive sensor. In the case described, the safety circuit leads to the jaw and stripper drive being switched off if the piston of the pneumatic cylinder has not passed the sensor. The position of the sensor can be chosen arbitrarily. Optical monitoring means can also be used.

In a further, particularly advantageous embodiment of the invention it is provided that the crank drive comprises a drive rod which is pivotally mounted on the slide with its free end and which is pivotally mounted on a rotatable crank by means of a guide pin by means of a guide pin, and that the guide pin is mounted along the Slidable crank is appropriate. By shifting the guide pin of the drive rod relative to the crank, the effective length of the crank can be varied in a particularly simple manner, so that there is a change in the working stroke or crank stroke and thus a change in the speed of the carriage with a constant rotational speed of the crank.

In order to facilitate the displacement of the guide pin along the crank, it is provided that the guide pin is guided in an elongated hole in the crank. This construction is particularly favorable at high movement speeds and very short cycle times.

In order to ensure the displacement of the guide pin along the crank in a suitable manner, it is particularly advantageous if a cam track element on which the guide pin is guided is mounted in the region of the crank. The cam track element can be configured, for example, in the form of a cam disk or a guide cam. The guide pin is thus guided on the cam track of the cam disc with each revolution of the crank. It is particularly advantageous if the guide pin is prestressed against the guideway of the cam disc by means of a prestressing element. This results in a particularly simple configuration of the cam. Alternatively, it is also possible to receive and guide the guide pin on all sides in a circumferential groove or a similar curved path.

The cam is preferably mounted in the region of the axis of rotation of the crank, the mounting being designed such that the cam cannot be rotated together with the crank. It is also particularly advantageous if the cam plate is designed to be interchangeable, which opens up the possibility of adapting the movement of the stripper tools to different production conditions, for example bag sizes or stripping specifications.

The ellipsoid-like area has a longer crank length in order to move the slide upwards with slow movement between the open cross-welding jaws, while the arc-like area serves to move the slide down very quickly during the stripping process.

In order to be able to open or close the stripper tools in the usual way, it is provided according to the invention that the drive device for actuating the stripper tools is designed in the form of a pneumatic cylinder mounted on the slide. On the one hand, this drive is designed with a relatively low weight, on the other hand, the air can be supplied in a very simple manner via flexible hoses.

Fig. 1

eine schematische Seitenansicht der erfindungsgemäßen Strippereinrichtung,

Fig. 2

eine vergrößerte Seitenansicht der Stripperwerkzeuge in einer geöffneten und einer geschlossenen Stellung,

Fig. 3

eine weitere Seitenansicht, auf die in Fig. 1 linke Seite der in Fig. 1 gezeigten Strippereinrichtung,

Fig. 4

eine schematische Seitenansicht eines weiteren Ausführungsbeispiels der erfindungsgemäßen Strippereinrichtung, bei welchem der Antrieb für die lineare Stripperbewegung phasenverschoben mit der Bewegung der Quersiegelbacken gekoppelt ist,

Fig. 5 bis 8

Darstellungen unterschiedlicher Betriebszustände beim Durchlauf eines Stripperzyklus bei einer Vorrichtung gemäß Fig. 4.

The invention is described below using an exemplary embodiment in conjunction with the drawing. It shows:

Fig. 1

2 shows a schematic side view of the stripper device according to the invention,

Fig. 2

an enlarged side view of the stripper tools in an open and a closed position,

Fig. 3

2 shows a further side view, on the left side in FIG. 1 of the stripper device shown in FIG. 1,

Fig. 4

2 shows a schematic side view of a further exemplary embodiment of the stripper device according to the invention, in which the drive for the linear stripper movement is coupled out of phase with the movement of the transverse sealing jaws,

5 to 8

Representations of different operating states when running through a stripper cycle in a device according to FIG. 4.

The stripper device shown in the figures shows a film tube 25 fed via a filling tube or format tube 16 to be stripped off by a pair of cross-welding jaws 24 before a bottom or top seam is formed. For this purpose, the stripper device comprises two stripper tools 14 which are essentially in the form of parallel rod-like elements. The stripper tools 14 are each mounted on a lever 18, the two levers 18 being connected to one another in a scissor-like manner at a common hinge point, as is shown in FIG. 1. At the free ends of the levers 18 further levers 19 are articulated, so that opening and closing of the stripper tools 14 results from a change in the distance between the pivot axes of the levers 18 and the levers 19. FIG. 2 shows the stripper tools in solid lines in the open state, while the dashed lines represent the stripper tools in a closed state.

The stripper tools are opened and closed by a drive device 15, which is designed in the form of a pneumatic cylinder. This is actuated via an air supply 20, which is only shown schematically in FIG. 3.

The pneumatic cylinder and the stripper tools 15 and the levers 18, 19 are mounted on a slide 13 which can be displaced along a guide rail 10 in the longitudinal direction of the film tube 25. A bearing 12 is formed on the lower region of the slide 13, to which a drive rod 9 is pivotably articulated. The end of the drive rod 9 comprises, as can be seen in particular from FIG. 3, a guide pin 8 which is guided in a slot 7 of a crank 6. As shown in FIG. 3, the guide pin 8 is in the elongated hole 7 guided by means of a guide bush 22. The crank 6 is pivotally mounted on a machine frame, not shown in detail, and is fixedly connected to a toothed belt pulley 5, via which a toothed belt 2 is guided. This in turn runs over a toothed belt pulley 1, which is part of the drive of the transverse sealing tools. A synchronization of the movement of the slide 13 and thus of the stripper tools 14 as a function of the movement of the cross-welding jaws 24 is thus ensured.

At the free end of the guide pin 8, as shown in FIG. 3, a cam roller 21 is mounted, which rolls on a cam element 4 to be described in detail. In order to press the guide pin 8 and thus the cam roller 21 against the outer circumference of the cam track element 4, a prestressing element (spring) is provided, which is fastened at one end to the guide pin 8 and at the other end to the axis of rotation 26 of the crank 6.

The cam track element 4, which is disc-shaped, is not rotatable, but is interchangeably attached to a housing 17 of the cheek block of the transverse sealing jaws, the cam track element 4 being fastened in the region of the axis of rotation 26, as can be seen in FIG. 3.

1 shows the cam track element 4 in a side view. From this representation it follows that the left half of the curved path element 4 is essentially circular, while the right half is ellipsoidal. The arcuate side of the cam track element 4 leads to a relatively rapid downward movement of the slide 13 during the stripping process, while the ellipsoidal side increases the effective crank length 6 and thus leads to a slower upward movement of the slide 13.

FIG. 4 shows a further exemplary embodiment of the invention, in which the drive for the linear movement of the stripper tools takes place out of phase with the movement of the transverse welding jaws 24. 4 is highly schematic, so that only the most essential components are shown. The cross-welding jaws are each mounted on a lever 100, two levers 100 being arranged one above the other, so that, together with the axes of rotation of the two levers 100 and a coupling rod 101 each articulated on these levers 100, a four-bar mechanism results. The coupling rod 101 is connected to the cross welding jaw 24. As is known from the prior art, the latter additionally has heating devices. Furthermore, it is possible to assign a separating device in the form of a perforator or knife to the transverse welding jaws, which are preferably double.

As represented by the movement circle 102, the drive shaft, not shown in detail, on which the lever 100 is placed rotates in a predetermined direction. Coupled with this movement, a drive lever 103 is rotated, which is rotatably supported at 104. The rotational movement of the lever 100 also results in a rotational movement of the drive lever 103.

The drive lever 103 is connected to a stripper tool mechanism, which is designed as shown in FIGS. 1 to 3, via a link 104 which is designed to be variable in length.

In addition, a pull rod 105 is provided, which is articulated on the stripper tool mechanism, for example the slide 13. The lower end of the pull rod 105 runs in a curved path 106. The pull rod 105 serves to close or open the stripper tools 14. The curved path 106 has, for example, an area 106A which effects the closing operation, while in an area 106B the Stripper tools 14 are open. The inner area 106C of the cam track 106 is an area in which the stripper tools 14 are closed.

A cam disk can also be used instead of the cam track 106.

An additional drive can be saved by using a cam track 106 or a cam disk.

The rotary movement of the lever 100 and the drive lever 103 are out of phase according to the invention, for example by 37 degrees.

5 to 8 each show different operational sequences of the arrangement shown in FIG. 4. 5 shows a process in which the stripper tools 14 are displaced upward when the cross sealing jaws 24 are open and are in a state in which the closing process of the stripper tools 14 is initiated, as is shown by the arrows. 6 shows a closed state of the stripper tools 14, in which the downward stripping movement begins. FIG. 7 shows an operating state in which the stripping process has continued, while FIG. 8 shows the end of the operating cycle in which the two transverse sealing jaws 24 are pressed against one another while the stripper tools 14 move apart to release the film bag. 5 to 8 result in the rotary movement of the drive lever 103 and the lever 100. Furthermore, the position of the pull rod 105 shows in which area of the curved path 106 (not shown in FIGS. 5 to 8) the end region of the pull rod 105 is performed.

Claims (15)

1. A stripper device for a packaging machine for forming tubular sleeves, with two stripper tools (14), arranged on either side of the path of movement of the tubular bag, which are movable by means of a drive device (15), a displacement device for the longitudinal displacement of the stripper tools (14), characterised by a carriage which is displaceable along the foil tube (25), on which the stripper tools (14) are mounted, and which is connected, via a crank drive, to the drive of the transverse welding terminal (24), wherein the drive of the transverse welding terminal (24) and the drive device (15) of the stripper tools (14) are coupled to one another, out of phase, to form a common drive.
2. A stripper device according to claim 1, characterised in that the crank drive comprises means of modifying the travel of the crank.
3. A stripper device according to claim 2, characterised in that the stripper tools (14) are actuatable by means of a curved drive device.
4. A stripper device according to claim 2 or 3, characterised in that the drive device (15) of the stripper tools (14) comprises safety dogs.
5. A stripper device according to one of claims 2 to 4, characterised by a safety circuit for controlling the drive device (15) of the stripper tools (14) and the drive of the transverse welding terminal (24), which comprises a sensor for checking the opening and closing operation (14).
6. A stripper device according to claim 5, characterised in that the sensor is designed in the form of an inductive sensor, which is allocated to an actuating element of the stripper tools (14).
7. A stripper device according to one of claims 1 to 6, characterised in that the time of the opening and closing movement of the stripper tools (14) is modifiable in order to set the stripping distance.
8. A stripper device according to claims 1 to 7, characterised in that the crank drive comprises a driving linkage (9), which is pivotably mounted at its free end on the carriage (13), said driving linkage (9) being pivotably mounted at its other end on a rotatable crank (6) by means of a guide bolt (8), and that the guide bolt (8) is mounted displaceably along the crank (6).
9. A stripper device according to claim 8, characterised in that the guide bolt (8) is guided in a longitudinal hole (7) in the crank (6).
10. A stripper device according to claim 8 or 9, characterised in that a curved path element (4) is mounted in the region of the crank (6), in which the guide bolt (8) is guided.
11. A stripper device according to claim 10, characterised in that the curved path element (4) is a curved disc and that the guide bolt (8) is prestressed against the guideway of the curved disc (4) by means of a prestressing element (3).
12. A stripper device according to claim 11, characterised in that the curved disc (4) is not rotatably mounted in the region of the axis of rotation of the crank (6).
13. A stripper device according to claim 5 or 6, characterised in that the curved disc (4) comprises an arc-shaped region and an ellipsoidal region.
14. A stripper device according to one of claims 11 to 13, characterised in that the curved disc (4) is replaceable.
15. A stripper device according to one of claims 1 to 14, characterised in that the drive device (15) for the stripper tools (14) takes the form of a pneumatic cylinder mounted on the carriage (13).

Images