EP2485889B1 - Device and method for the manufacture of, especially application of glue to, semifinished bags - Google Patents

Description

The invention relates to a device for applying a size-appropriate glue line on packaging semifinished products, with an applicator head comprising a plurality of glue outlet openings, each Leimaustrittsöffnung is assigned a glue valve, with a Leimleitungssystem with which the glue on the respective glue valve to the respective glue outlet opening is feasible, and with a control device.

Such a device is off DE 102 42 732 A1 known. The setting of the format-appropriate glue trace is made in this document via an operator terminal. In addition, it is generally mentioned that the generic device can also be equipped with pressure sensors and pressure regulators.

In US 5,920,829 A a device for applying a fluid by means of a nozzle is described on a workpiece, which can be used for a variety of purposes. The flow characteristic of the fluid is determined based on the initial ratio of flow rate and nozzle pressure. In this way, during the application of the fluid, the nozzle pressure and the feed rate of the nozzle can be adjusted properly.

In US 2009/0038707 A1 Another device for applying a fluid by means of a nozzle is described on a workpiece, which can be used for a variety of purposes. Among other things, the feed rate of the nozzle and the nozzle pressure can be measured as operating parameters. Future operating parameters are calculated from existing operating parameters so that the application of a new track takes place at the right time and at the correct position of the workpiece.

Devices for gluing packaging semi-finished products are used inter alia in the production of various types of bags. Since bags are made in a variety of sizes, the glue tracks must be applied format-appropriate.

The order of a format-appropriate glue track is usually carried out by bringing a mounted on a rotating roller format part in a revolution of the format roller with a glue roller or other Leimspeicher- or transfer parts in contact and thereby applied with glue. In the further course of the roller rotation, the format plate transfers the glue stored on it to the respectively to be bonded areas of the later bag bottoms or the slip. For this purpose, the format part is provided with characteristic elevations, which are adapted to a specific sack format. For the production of bags of other formats on a bottom-laying device containing such a gluing station, the format parts are exchanged. This type of production of flat glue marks on semi-finished sacks has proven itself, as such large quantities of the difficult-to-handle starch glue - which is often used for gluing packaging paper packaging - are clean and format order applicable.

The term "size-appropriate glue line" is to be understood as an order form tailored to the type and format of the bag. The order within this order form is usually flat, often the edges of the mold is of particular importance for the durability and tightness of the bags.

The disadvantage here, however, that for these devices a variety of glue transfer components, such as format rollers and format parts, held and must be cleaned again after use.

Therefore, more recently Bodenlegevorrichtungen have become known, which manage without such format parts. That's how it shows EP 1 648 688 B1 a Bodenlegevorrichtung with a gluing station, in which several applicators extrude glue on semi-finished sacks. For this purpose, several glue valves are mounted on each of these guns. These glue valves are one or associated with several glue outlet openings from which the glue is applied to the bag components.

The production of a format-appropriate glue trace is now done by a control unit selectively activates these glue valves. In this way, a wide variety of glue profiles can be realized. The need to maintain a large number of format parts is eliminated.

However, a problem with these floor laying devices is that production processes - especially during the gluing of the semi-finished sacks with selectively controlled glue valves - must be precisely controlled and, if necessary, adjusted.

One way to control such a glue application is in the DE 10 2005 046 660 A1 presented. In this document, the shape of the glue trace applied to the package is examined by examining the electromagnetic radiation remitted by the packaging semi-finished products. Such a method is complicated and error-prone and it only recognizes errors that have already occurred on the examined semi-finished packaging. Even the documents mentioned in the introduction are unable to solve these problems.

Therefore, the object of the present invention is to provide a device in which errors can be detected with less effort and optionally shut down.

The solution according to the invention is that a pressure sensor is integrated in each glue valve, wherein the pressure in the glue line system in the glue flow direction behind the respective glue valve can be measured with each pressure sensor, and the control device is set up in such a way that the time profile of the measured values of the respective pressure sensor is compared with a desired course of the corresponding value and wherein based on the time difference from actual to desired course of the corresponding value, a change in the control of the valves is made.

The invention takes advantage of the fact that in the glue lines by the opening and closing of the valves, which should work smoothly to ensure a proper glue application, changes in the pressure result. The easiest way is to measure the static pressure in the glue lines. This goes back when the glue lines are opened and the glue sets in motion, so additionally hydrodynamic pressure pronounced. By the way, glue lines are also to be understood as meaning the lines within a valve.

With the provision of a pressure sensor, this change in pressure can now be measured. The measured values can be prepared or used in different ways. It is advantageous if, for this purpose, at least one means for passing on the pressure measurement value is provided, with which the pressure measurement value can be displayed to a machine operator and / or forwarded to a control device. Pressure readings that do not meet expectations can provide an indication of pre-existing or even imminent disruptions. Both the operator and the controller can take countermeasures.

Of course, a suitable display device must be provided in order to display the measured values to the machine operator. Instead of the measured values, the operator can also derive information derived from the measured values. are displayed. This can be, for example, a warning if a pressure reading or a difference of pressure readings exceeds or falls below a predetermined value.

The pressure sensor is in this invention - arranged in the glue flow direction - seen behind the valve. If the sensor (not according to the invention) is arranged in front of the valve, then it can be assumed that the static pressure to be measured is higher with the valve closed than with the valve open. In the arrangement behind the valve, the pressure conditions are rather reversed. The valve is often a component provided with a plug or socket through which the energy is supplied for opening and closing. The pressure sensor is integrated in this valve, i. Valve and sensor represent a component. Thus, the assembly of the device for further processing of semi-finished sacks can be greatly simplified. In addition, the measured value for the pressure can then also be read out via the plug and / or the socket. So it is only an electrical cable necessary.

In general, the glue will flow after opening the valves in the direction of glue application openings, which are in a gluing position to the packaging semi-finished products. As a rule, the semifinished packaging products to be glued are guided past the gluing openings.

If at least one further sensor is provided, measures the characteristics of the working current, which is supplied to the valves for opening and closing measures, this is advantageous. Characteristics of the working current can be physical quantities such as current or voltage or the like.

The control device is set up in such a way that it compares the values of the respective pressure sensor and optionally the measured values of the at least one further sensor with nominal values. These setpoints are available as temporal course of the respective physical value.

A comparison of the values of pressure sensors with the values of the other sensors can also be helpful. In particular, the comparison of the time course of these values can lead to findings on the opening behavior of the valves and thus also the glue application behavior. Also, a comparison of the same physical values to different valves brings advantages. A comparison of such values provides insights into differences between the valves and thus to possible faults.

In this context too, the assignment of sensors to valves has to be considered. An exact assignment of the measured values from sensors to valves is possible since one pressure sensor and optionally one additional sensor are assigned to one valve.

If, not according to the invention, one sensor is assigned to a plurality of valves-that is, for example, measures the pressure in a glue line, in the course of which a plurality of glue valves are located-then at least one deviation in the pressure curve can be detected at the opening of a plurality of valves. If the valves are opened and closed at different times, it is possible to assign a corresponding "pressure response" to the opening of each valve. The same applies if several valves - here at least two - only one sensor is assigned. The corresponding Ventilansteuersequenzen can be implemented as program instructions in a control unit. They can be carried out in a test operation, when performing a washing program for cleaning the glue application components or the like. In such a washing program, the glue application device can be cleaned consciously. This can be done by the passage of a suitable - preferably leachable and low viscosity liquid. Particularly suitable for this purpose are so-called Newtonian fluids whose viscosity depends only on the temperature, but not for example on the pressure itself. Such liquids include water. The glue commonly used in the devices for gluing sack semi-finished products is usually not Newtonian liquid. Newtonian fluids always lead to the same pressure response.

However, it is also advantageous if the control device is set such that it utilizes working cycles in which different valves, which are assigned to a sensor, are activated during operation at different times.

The pressure sensor can advantageously be arranged at a bottleneck of the glue line system. At such bottlenecks, the glue has to flow faster than in the other glue line areas when the glue valve (s) are open. As a result, the dynamic pressure in the narrows increases and the static pressure decreases more as a result of valve opening. Stronger variations in static pressure are better to measure than smaller ones.

Constrictions are advantageous, which are narrowed compared to the normal line system by a factor between 1 and 2. Since, according to the law of Hagen-Poiseuille, the pressure depends on the fourth power of the radius, a narrowing by one of the stated factors already leads to a very strong pressure change in comparison with the non-narrowed line system.

It is advantageous to provide at least one viscosity measuring system in the glue line system. Alternatively, a measurement of the viscosity of the supplied glue can be made again and again. For example, the aforesaid viscosity measuring system can measure the volume flow through a pipe (it may also be known to the system from the beginning) and also measure the pressure drop in the line. Then the viscosity can be determined by the law of Hagen-Poisseuille.

As already mentioned, it is advantageous that the time profile of the various measured values is compared with setpoint values. The desired values can be obtained empirically and / or mathematically. A comparison of the actual values of different valves is also an advantage here. This is especially true when it comes to pressure readings from different valves at a time or better during a period and Viscosity fluctuations in the pipe system are to be feared or have taken place. In this case, set values, which were often measured under completely different operating states or viscosities, lose their significance. It is also possible to compare the actual values of a valve with the average values of other valves.

As a result of all these comparisons, actual values are measured on valves with limited function, which deviate from setpoints or from the actual values of the other valves. Here, the deviation may be in a lower maximum value, for example, the drop in the static pressure. In such a case, it can be assumed that the relevant valve no longer completely opens and / or closes or that a glue line is clogged. As a result of the occurrence of these measurement values, the control device may interrupt the operation of the gluing station and initiate remedial measures, such as the execution of a washing program. Also appropriate are warnings to the operating personnel.

In particular, if deviations from actual values to desired values or to the actual values of other valves occur in the case of a valve, which are mainly reflected in the time course of the actual values, other remedial measures can also be taken during operation, as an alternative or in addition:
Valves which - judging by the course of the actual values - can be actuated earlier, too slowly or too late, in order to compensate for the resulting "dead time" (longer activation time). The method steps for determining the dead time can also be implemented in the control device. The same applies to the change of the activation times of the affected valves.

In general, the dead time will be defined as the time between a triggering trigger signal intended to trigger the valve opening, such as the working current, and the actual valve opening, which is measurable via the measured pressure change.

Further embodiments of the invention will become apparent from the description and the claims.

Fig. 1

eine Vorrichtung zur Beleimung von Verpackungshalbzeugen

Fig. 2

Den Verlauf des statischen Druckes des Leims in einem ersten weiten Leimleitungsabschnitt

Fig. 3

Den Verlauf des statischen Druckes des Leims in einem zweiten engen Leimleitungsabschnitt

Fig. 4

Die Leimleitung mit dem ersten und zweiten Leimleitungsabschnitt

Fig. 5

Einen Schnitt durch einen Leimauftragskopf

Fig. 6

Den Verlauf des statischen Druckes des Leims in einem weiteren Leimleitungsabschnitt in dem sich ein Ventil öffnet

Fig. 7

Den Verlauf des Arbeitsstromes des Ventils bei seiner Öffnung

The individual figures show:

Fig. 1

a device for gluing packaging semi-finished products

Fig. 2

The course of the static pressure of the glue in a first wide glue line section

Fig. 3

The course of the static pressure of the glue in a second narrow glue line section

Fig. 4

The glue line with the first and second glue line sections

Fig. 5

A cut through a glue application head

Fig. 6

The course of the static pressure of the glue in another Leimleitungsabschnitt in which opens a valve

Fig. 7

The course of the operating current of the valve at its opening

Fig. 1 shows an application head 1, as it is used in a Beleimungsstation in a Bodenlegevorrichtung. This application head 1 is composed of a job plate 2, to which valves 3 are attached. The glue is supplied to the application head 1 via the glue supply line 4. The gluing station are fed in the direction x unprimed labels 5. Such labels are used, for example, to add cross bottoms of cement sacks. Especially on cement sacks but also valve leaflets are used.

Each valve 3 is assigned in the non-glued sheets 5 side facing the application plate 2 one or a group of glue outlet openings. The glue flow to the glue outlet opening can be made or interrupted by the associated valve 3. In this way, it is possible to apply 5 different glue tracks on the unprimed label, which run parallel to the conveying direction x of the unprimed label 5. By regularly opening and closing the valve 3, a regularly interrupted glue trace 6 can be applied. Also can be produced short traces of glue 7, broken glue marks 8 and continuous glue traces 9.

If there is no unsealed label 5 under the application head 1, the glue flow through all valves 3 is interrupted in order not to pollute the gluing station unnecessarily. In order to be able to glue all areas of the unprimed label in the direction y transversely to the conveying direction, the application head 1 can likewise be displaced in this direction. However, the applicator head 1 just described can not only be used for gluing sheets 5, but is also suitable for applying glue to the areas of the subsequent bottom of the sack to be bonded due to the variability of the glue tracks that can be produced.

In FIG. 2 is the time course 12 of the static pressure in a first Leimleitungsabschnitt 10 (in FIG. 4 ). The amplitudes 14 of the fluctuations of the static pressure Pst, which result in this first glue line section 10, are less than the amplitudes 15 of the fluctuations of the time course 13 of the pressure Pst in FIG. 3 , which result in the opening of the same valve in a second narrower track section 11. These different amplitudes 14 and 15 recorded by the pressure sensors DS1 (first, further line section) and DS2 (second, narrower line section) can be explained as follows:
In the further line section 10, the glue speed v1 is sufficient to convey the glue volume required per unit of time through the line section 10. After the constriction 16 a significantly higher glue speed v2 is required with open valve to promote enough glue. The force for accelerating the glue is provided from the static glue pressure Pst. Since the sum of static pressure Pst and dynamic pressure is always the same, the static pressure in the narrower line section 11 decreases more than in the other 10. The signals of the corresponding pressure sensor DS2 are therefore better to evaluate than the signals of the pressure sensor DS1, the pressure controlled in the other Leimleitungsbereich (among other things, because of the signal to noise ratio).

FIG. 5 shows a section through a device for gluing packaging semi-finished products. This device is different in their construction from the in FIG. 1 among other things, characterized in that the glue reservoir 21 is mounted in the z-direction over the glue valves Va-f.

In the FIG. 5 the glue reservoir 21 is supplied with glue through the glue line 20. The glue is supplied via further glue lines 23 af valves V af, which control the glue flow in the lines 23 af by opening or closing. The glue lines 23 af and the glue distribution lines mentioned later extend in a plate 26, which also carries the valves V af and the pressure sensors DS af. When the valve is open, the glue flows past the valves V af into the distribution lines 25 which supply the glue to the glue outlet openings 24. Through these openings, the glue is extruded on the packaging semi-finished products, not shown here packaging semi-finished products - which may be, inter alia, slips or cross bottoms - extruded.

If the gluing station (not according to the invention) is equipped only with a pressure sensor DS, which, like the DS3 sensor, measures the static pressure in a glue reservoir or glue line associated with several valves V af, then it is difficult to make any deviations or changes in the behavior of the pressure to the individual valves Va-f assign. As already mentioned, in such a case, it is most advantageous to evaluate pressure readings taken when the different valves are time differentiated, that is, opened at different times. This can be done as part of a rinsing process or during any other break. However, it is also possible to obtain these measured values in normal operation if the glue profile to be produced permits or requires the opening of the different valves at different times.

Even fewer problems with the assignment of the measuring signals to the valves occur when the signals are available from Leimdrucksensoren associated with Leimleitungen, which lead only to a valve, as is the case for example with the sensor DSa. Due to the (not according to the invention) position of the sensor and the high viscosity and rheology of the glue, the pressure curve in the line 23a almost exclusively from the opening and Closing behavior of the valve Va dependent and is only slightly influenced by the other processes in and around the glue reservoir 21. This also contributes to the large glue reservoir 21, from which the lines 23 branch off af directly. Such a large glue reservoir has a pressure-compensating effect, so that almost the same pressure prevails everywhere with the valves closed.

An inventive arrangement of the pressure sensors illustrates the sensor DSc, which is downstream of the valve. At this point, its measured values are even less dependent on the switching behavior of the other valves than the measured values of the DSa sensor. However, it is not completely self-evident to be able to measure usable values of the static pressure that rise here when the valve is open at such a point. In this context, it could be helpful if the total cross section of the lines downstream from the sensor DSc to the outlet openings again decreases. An alternative to measuring the static pressure could be the measurement of the flow velocity at this point (this also applies elsewhere).

The valves Va-f can be supplied via the power lines 27a-f with the working current required for switching the valves. At each power line 27 a-f or at each valve Va-f, a sensor SI a-f is arranged in each case, with the characteristic values of the working current can be measured. This sensor SI a-f may be a current measuring sensor. Also voltage, resistance or other measuring sensor are conceivable.

The FIGS. 6 and 7 deal with the time sequence of the caused by the opening of a valve pressure curve 30 and the course 32 of the working current I of a valve. To the pressure curve 30 is only on the statements to the FIGS. 2 and 3 to refer.

FIG. 7 shows the current that results during an opening and closing cycle of a valve. The rise and fall of the working current, which is measurable with the sensor SI, shows a slightly exponential course, since the glue valve concerned by the force of a coil to be energized is opened. The spool moves a needle whose movement opens the valve. When the power is switched off again, it also drops back in the form of a decay function due to the inductance of the coil. The needle is pushed back into its original position by a spring so that the valve is closed again.

In the present example, the clamp T o denotes the opening dead time, which is measured here between the time at which the working current reaches a threshold value S and the time at which the pressure Pst in the glue line reaches its minimum.

In the example according to the FIGS. 6 and 7 For example, the closing dead time Ts sketched by the clamp Ts is measured between the beginning of the current drop and the reaching of the maximum pressure. If the valves are supplied by a control device triggers a power controller, which then provides the working flow for the valve, it may be advantageous to the Öffnungsstotzeit between the known at the time of the trigger signal and the step response of the static pressure (reaching the Minimums). In this way, the opening dead time of the entire system would be detected. Similarly, the dead time for the closing process could also be determined.

As part of an effective dead time compensation then the Ansteuerzeitpunkte can be changed after the determination of the dead time so that the pressure response in the glue line - and accordingly the slightly later beginning glue application on the packaging semi-finished - takes place again at the desired time or in a tolerance range around the target time.

In this context, a high read speed of the pressure sensor is advantageous. For example, to bring the accuracy of the glue application to 1 mm, the tolerance range should be set around the setpoint to 0.3 ms. To ensure this, a read rate of at least 3 kHz (ie 3000 individual measurements per second) is advantageous. It is preferred However, a reading rate of 15 kHz, to draw conclusions from the measured values not only on the opening or closing dead time, but also on the opening or closing behavior of the valve. The comparison of an actual opening or closing behavior with a desired behavior or the original behavior can provide indications of defects which have already occurred or are imminent. Thus, by early detection of errors, sudden or unplanned machine downtime can be avoided. LIST OF REFERENCE NUMBERS 1 gun 2 application plate 3 Valve 4 Leimzuleitung 5 unsealed piece of paper 6 regularly interrupted glue trace 7 short glue trace 8th interrupted glue trace 9 continuous glue trace 10 First, further Leimleitungsabschnitt 11 second, narrower Leimleitungsabschnitt 12 time course 12 of the static pressure in Leimleitungsabschnitt 10th 13 time course 12 of the static pressure in Leimleitungsabschnitt 11th 14 Amplitude of the fluctuations of the static pressure 15 Amplitude of the fluctuations of the static pressure 16 constriction 20 glue line 21 glue reservoir 22 23 af Further glue lines 24 glue outlet 25 distribution lines 26 plate 27 af Power lines 30 pressure curve 31 Course of the working current of a valve 32 Dashed line to illustrate the same time points in the FIGS. 6 and 7 33 S Threshold of the working current of the valve DS1-3 pressure sensors DS af pressure sensors v1 Leimgeschwindigkeit v2 Leimgeschwindigkeit shush Static glue printing V af glue valves I Working current of a valve SI af Sensor on the valve V af or on the power line 27 af Tö Dead time at valve opening ts Dead time when closing the valve X Transport direction of the sacks y Direction of space (transversely to the transport direction x) z Further spatial direction (transverse to the transport direction x and the direction y) A Application area of a normal glue valve 42 B Application area of the additional glue valve 43

Claims (3)

1. A device for applying a properly formatted trace of glue to semi-finished packaging products,
   having a discharge head (1), which comprises a plurality of glue outlet openings (24), wherein
   one glue valve (3, Va-f) is assigned to each glue outlet opening (24),
   having a glue guiding system (20, 21, 23a-f, 24, 25), with which the glue can be guided via the respective glue valve (3, Va-f) to the respective glue outlet opening (24), and having a control device,
   characterized in
   that a pressure sensor (DSc) is integrated in each glue valve, wherein with each pressure sensor the pressure in the glue guiding system (20, 21, 23a-f, 24, 25) can be measured in the glue flow direction behind the respective glue valve (3, Va-f), and
   that the control device is configured in such a manner that the time course of the measured values of the respective pressure sensor (DS) is compared with a target course of the corresponding value and wherein a change in the control of the valves is carried out by means of the time difference from the actual to the target course of the corresponding value.
2. A device according to Claim 1, characterized by a further sensor (SI),
   with which characteristic values (I) of the working stream, which can be fed to the respective glue valve (3, Va-f), can be measured.
3. A device according to Claim 2, characterized in that the control device is configured in such a manner that the time course of the measured values (Pst, I) of the respective pressure sensor (DS) can be compared with the time course of the measured values of the respective further sensor (DI).

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