METHOD FOR CONTROLLING THE AMOUNT OF AN ADHESIVE TO BE APPLIED TO A SUBSTRATE

Abstract

Controlling application of adhesive on a substrate includes using a gas sensor, obtaining a first sensor signal. The first sensor signal indicates a partial pressure of a gas that arises from a constituent of the adhesive. Based at least in part on this partial pressure, the controller either controls an applicator's delivery of the adhesive to a substrate or causes an error signal indicative of the adhesive's unsuitability for adhesion.

Claims

1-24. (canceled)

25. A method comprising receiving a first sensor signal from a gas sensor, said first sensor signal being indicative of a measurement of partial pressure of an adhesive gas, said adhesive gas being a gas that arises from a constituent of an adhesive that is being applied to a substrate and, based at least in part on said measurement of said partial pressure, carrying out an action selected from the group consisting of controlling an applicator's delivery of said adhesive to said substrate and causing storage or display of an error signal indicative of said adhesive's unsuitability for adhesion.

26. The method of claim 25, further comprising determining that said measurement of said partial pressure is outside of a permissible range and, in response, suppressing said applicator's ability to apply said adhesive.

27. The method of claim 25, wherein using said gas sensor comprises using an olfactometer.

28. The method of claim 25, wherein controlling said applicator's delivery of said adhesive comprises adjusting a spray of a sprayer in response to said measurement of said partial pressure.

29. The method of claim 25, wherein said adhesive is a melt adhesive.

30. The method of claim 25, further comprising causing said adhesive to be in circulation, said applicator being in communication with said circulating adhesive.

31. The method of claim 25, further comprising comparing a reference partial pressure with said measurement of said partial pressure and issuing a system error message after having determined that said measurement of partial pressure differs from said reference partial pressure.

32. The method of claim 25, further comprising receiving, from said gas sensor, measurements of partial pressures of additional adhesive gases and causing storage or display of said error signal in response to determining that said partial pressures indicate that said adhesive has a composition that deviates from a reference composition by having an incorrect constituent or by having a constituent at an incorrect concentration.

33. The method of claim 25, wherein obtaining said first sensor signal comprises obtaining a measurement of partial pressure that extends over time and wherein causing storage or display of said error signal comprises causing said storage or display of said error signal in response to detecting that, during said time, said measurement of partial pressure has exceeded a limit value.

34. The method of claim 25, further comprising, based at least in part on a measurement of a fill level of an adhesive reservoir, carrying out an action selected from the group consisting of controlling said applicator's delivery of said adhesive to said substrate and causing storage or display of said error signal.

35. The method of claim 25, further comprising introducing, into said adhesive, a binding agent and a solvent.

36. The method of claim 25, wherein obtaining a sensor signal indicative of a measurement of partial pressure of an adhesive gas comprises obtaining a signal indicative of partial pressure of a substance that imparts an aroma to said adhesive.

37. The method of claim 25, wherein obtaining a sensor signal indicative of a measurement of partial pressure of an adhesive gas comprises obtaining a signal indicative of partial pressure of a substance that has been added to said adhesive following manufacture of said adhesive in order to perfume said adhesive.

38. The method of claim 25, further comprising obtaining a second sensor signal, said second sensor signal being indicative of an additional measurement, said additional measurement being a measurement of a property selected from the group consisting of a temperature of said adhesive, an extent to which an adhesive reservoir is filled with said adhesive, a viscosity of said adhesive as it is being delivered, and a flow speed of said adhesive as it is being delivered, wherein, based at least on said measurement of partial pressure, carrying out an action selected from the group consisting of controlling an applicator's delivery of said adhesive to a substrate and causing an error signal indicative of said adhesive's unsuitability for adhesion to be stored or displayed comprises carrying out said action based on both said measurement of partial pressure and said additional measurement.

39. An apparatus for applying an adhesive to a substrate, said apparatus comprising a controller, a gas sensor, an applicator, and an adhesive reservoir, wherein said applicator applies said adhesive from said adhesive reservoir onto said substrate wherein said gas sensor is configured to detect a partial pressure of an adhesive gas, said adhesive gas arising from a constituent of said adhesive, wherein said controller is configured to receive a sensor signal from said gas sensor and to carry out an action selected from the group consisting of controlling said applicator based at least in part on said sensor signal and causing storage or display of an error signal.

40. The apparatus of claim 39, further comprising a suction device disposed at an application region.

41. The apparatus of claim 39, further comprising an adhesive delivery device that delivers adhesive from said adhesive reservoir, wherein said gas sensor is disposed in said adhesive reservoir or in said adhesive delivery device.

42. The apparatus of claim 39, wherein said gas sensor is configured provide measurements of concentrations of different adhesive gases and wherein said controller takes action based at least in part on said concentrations of different adhesive gases.

43. The apparatus of claim 39, further comprising a delivery circuit that comprises an adhesive delivery device that draws adhesive from said adhesive reservoir, wherein said gas sensor is disposed along said delivery circuit.

44. The apparatus of claim 39, further comprising additional sensors, wherein said additional sensors measure a temperature of said adhesive, an extent to which said adhesive reservoir is filled with said adhesive, a viscosity of said adhesive as said adhesive is being delivered, and a flow speed of said adhesive as it is being delivered.

45. The apparatus of claim 39, further comprising a suction device that draws adhesive gas away from said adhesive reservoir or from an adhesive delivery device thereby reducing emission of said adhesive gas into the environment.

46. The apparatus of claim 39, further comprising a machine selected from the group consisting of a labeling machine and a machine for adhesively connecting containers so as to form container bundles.

47. The apparatus of claim 39, further comprising a heater for controlling viscosity of said adhesive and a delivery pump for pumping said adhesive from said adhesive reservoir, and a valve for regulating flow of said adhesive.

48. The apparatus of claim 39, wherein said gas sensor is disposed at or above a glue roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The invention is described hereinafter by way of example, on the basis of the schematic drawings in which:

[0039] FIG. 1 is a view from above onto a labeling machine,

[0040] FIG. 2 shows measured solvent content of an adhesive over time,

[0041] FIG. 3 shows measured solvent content of an adhesive over time in connection with a re-filling an adhesive container with adhesive.

DETAILED DESCRIPTION

[0042] FIG. 1 shows a labeling machine 10 having a vacuum drum 12 that rotates about an axis-of-rotation. The labeling machine 10 also includes a label-delivery device 16 that includes a cutting roller 18 and a transfer drum 20.

[0043] The vacuum drum 12 has six receptors 14. The receptors 14 are equally spaced from each other around the drum's circumference. During the course of the vacuum drum's rotation, each receptor 14 passes through a first sector A and a second sector B, each of which corresponds to a range of angles. In some embodiments, a receptor 14 is able to move radially inward or outward.

[0044] As the vacuum drum 12 rotates, it brings receptors 14 to a reception region 22. In operation, while a receptor 14 is in the reception region 22, a label 24 is taken over from a label receiver 21 of the transfer drum 20 onto that receptor 14.

[0045] As the vacuum drum 12 continues to rotate, it brings the receptors 14 to a handover region 26. In operation, when the receptor 14 is in the handover region 26, a label 24 is moved from a receptor 14 onto a circumferential surface of a container 34 that is located at a transport point 30 of a transporter 23. of a container-handling device.

[0046] Each receptor 14 on the vacuum drum 12 has a suction surface 28 that faces radially outward to engage a label 24. The suction surface 28 connects to an associated vacuum chamber 36. The vacuum chamber 36 ends in a perforation 38 through a base plate. The base plates of the various receptors 14 extend along a circle that is concentric with the vacuum drum's axis-of-rotation. Each perforation 38 establishes communication between its corresponding vacuum chamber 36 and a vacuum source.

[0047] The labeling machine 10 further includes a glue roller 13 arranged along the first sector A between the reception region 22 and the handover region 26. The glue roller 13 rotates in a direction opposite that of the vacuum drum 12. As a result, rolling the glue roller 13 results in application of an even layer of glue to the rear side of a label 24 that is held on a receptor 14 as it rolls. This glue secures the label 24 to a container's circumference.

[0048] To promote contact between with the container 34, it is useful for the receptor 14 to move radially outward while in the handover region 36. However, in those embodiments that lack radially movable receptors 14, the vacuum drum 12 is arranged such that secure contact can be made even in the absence of such radial movement by the receptors 14.

[0049] The labeling machine 10 features an adhesive delivery system 36 that includes an adhesive reservoir 48, a controller 52, and a variety of sensors. These sensors include a gas sensor 50 to detect the presence of one or more adhesive gases, a temperature sensor 54 to measure the adhesive's temperature, a viscosity sensor 56 to measure the adhesive's viscosity, a filling-level sensor to measure the amount of adhesive remaining in the reservoir 48. The adhesive itself is, of course, not a gas. The term adhesive gas is used as a convenient way to refer to the gaseous form of various constituents of the adhesive, some of which may be volatile and hence have a tendency to evaporate, thus causing a measurable partial pressure.

[0050] The adhesive delivery system 36 also includes an applicator 40 in the region of a glue roller 13. The applicator 40 includes a sprayer 42 from which adhesive is launched from the adhesive delivery system 36 towards the substrate. A valve 44 upstream of the sprayer 42 regulates how much adhesive from the reservoir 48 to reach the sprayer 42.

[0051] In operation, the controller 52 controls the valve 44 to regulate the quantity of adhesive delivered to the applicator 40 to cause the sprayer 42 to spray an even distribution of adhesive onto the glue roller 13. The controller 52 controls the valve 44 based on one or more inputs from the sensors.

[0052] Some embodiments include devices for maintaining the condition of the adhesive. These include a solvent-agent delivery device 60, a binding-agent delivery device 62, and a stirrer, all of which are connected to the adhesive reservoir 48. A heater 64 in the adhesive reservoir 68 heats the adhesive as needed to maintain a target viscosity. In such embodiments, the controller 52 controls the solvent-agent delivery device 60, the binding-agent delivery device 62, and the heater 64 based on outputs from one or more of the aforementioned sensors.

[0053] In some embodiments, the gas sensor 50 measures a partial pressure of an adhesive gas. An example of such an adhesive gas is that associated with adhesive's solvent. The gas sensor 50 provides a signal indicative of this gas pressure to the controller 52, which then controls the valve 44. As a result, the controller 52 is able to control supply a particular quantity of adhesive based on a sensor signal from the gas sensor 50.

[0054] In some cases, the controller 52 will simply switch off the applicator 40 upon occurrence of a condition. Examples of such conditions include a signal from the gas sensor 50 that indicates a particularly low partial pressure of an adhesive gas. Such a low value may indicate that the adhesive is no longer capable of carrying out its function. In some cases, the adhesive gas is that which arises from evaporation of the adhesive's solvent. However, other gases can also be sensed.

[0055] In some embodiments, a signal from the viscosity sensor 56 or the temperature sensor 54 provides a basis for adjusting the quantity of adhesive to be delivered. In addition, the temperature sensor 54 provides a basis for controlling the heater 64 so as to maintain a suitable temperature for the adhesive. Since viscosity is often a function of temperature, the output of the viscosity sensor 56 also provides a basis for controlling the heater 64.

[0056] In some embodiments, the gas sensor 50 detects partial pressures of several species of adhesive gas. This permits an inference to be made concerning the nature or condition of the adhesive. From this, such inferences, it is possible to tell whether the adhesive is appropriate for the desired purpose.

[0057] It is also possible to infer from such measurements of multiple species, particularly when combined with measurements from the viscosity sensor 56, to determine whether certain constituents, such as solvents or binding agents, are missing or in otherwise short supply. In such embodiments, the controller 52 causes the solvent-delivery device 60 or the binding-agent delivery device 62 to top up the missing constituents as required to restore the adhesive to a reference state thereof.

[0058] Some embodiments include a filling-level sensor 58 that measures extent to which adhesive fills the adhesive container 48. Information from the filling-level sensor 58 is particularly useful for topping up the components of the adhesive. In particular, the information from the filling-level sensor 58 permits optimizing the quantity of solvents and binding agents that are delivered during the topping-up process.

[0059] FIG. 2 shows a sensor signal provided by the gas sensor 50 during the course of operation. In the illustrated example, the gas sensor 50 measures partial pressure of solvent that evaporates over time. The vertical axis I, which represents intensity, indicates that partial pressure is decreasing in an approximately linear fashion with a slope approximated by dI/dt. It is thus possible for the controller 52 to extrapolate and predict when the partial pressure of solvent will drop below a minimum permissible value, I.sub.min, and to take steps accordingly.

[0060] In some embodiments, the controller 52 stops the applicator 40 before the partial pressure reaches this minimum value. In other embodiments, the controller 52 instructs either or both the solvent delivery device 60 or the binding agent delivery device 62 to take steps to correct the loss of solvent partial pressure by delivering respective amounts of binding agent or solvent. This permits the controller 52 to maintain a consistent quality of adhesive.

[0061] It is also possible to use the time evolution of partial pressure of gas from an adhesive to assess the condition of the adhesive during filling of the reservoir 48.

[0062] FIG. 3 shows the expected evolution of partial pressure over time for a gas when filling the reservoir 48 with adhesive. The filling interval t1 is the time needed to fill the reservoir 48, the peak interval t2 is the duration of an anticipated peak in partial pressure, and intensity k1 represents a range of anticipated partial pressures that one might expect shortly after having filled the reservoir 48 with the adhesive.

[0063] The measured partial pressure can be that of the adhesive's solvent or of a secondary substance that has been introduced only for identification.

[0064] During the filling interval t1, the partial pressure is anticipated to rise sharply until it reaches the intensity range k1. If, on the basis of the sensor signal from the gas sensor 50, this peak is indeed measured in this range, the system is then disconnected. If, after filling, this peak has not been reached within the following peak interval t2 in the intensity range k1, then one can infer that the adhesive is unsuitable, either because it has aged or because it is an incorrect adhesive. Under these circumstances, a warning signal to be issued and/or the system is stopped or, if the system is not running, it is prevented from starting.

[0065] Some embodiments take account of temperature dependency. For example, with a higher temperature, a steeper decline in intensity over time would be expected in FIG. 2 and the anticipated peak interval t2 would differ in both in both temporal extent and location along the temporal axis and the anticipated intensity range k1 would differ in its location along the temporal axis and in its extent in along the intensity axis.

[0066] The adhesive-application system described herein has been described in connection with a labeling machine 10 that labels containers. However, it can also be used for labeling cartons or for applying adhesive used to bond container together into container packs. The adhesive-application system as described herein is also usable for applying adhesive in connection with folding and aligning cartons during carton packaging.

[0067] In the illustrated example, adhesive ultimately passes through a sprayer 42 before reaching the substrate. However, the principles described herein are independent of the choice of what actually applies the adhesive. Thus, the system described herein is usable with a device that applies adhesive points or other devices for surface application of adhesive.

[0068] In some embodiments, the adhesive delivery device 46 is a delivery pump that adjusts the delivery pressure of the adhesive and hence the pressure with which the sprayer 42 sprays the adhesive. The control device 52 then preferably controls the valve 44 and/or the delivery pump. However, it is also possible to use an adjustable delivery pump instead of a valve 44.

[0069] The invention is not restricted to the exemplary embodiment described heretofore, but can also be varied at will within the scope of protection of the following claims.

[0070] Having described the invention and a preferred embodiment thereof, what is new and secured by letters patent is: