Apparatus and method for applying foam adhesive
The device and method stabilize adhesive application by controlling pressure and foaming rate, addressing fluctuations to ensure consistent adhesive quantities and prevent delamination, enhancing container quality and reducing rejects in the beverage industry.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- KHS GMBH
- Filing Date
- 2025-10-06
- Publication Date
- 2026-06-04
AI Technical Summary
Existing adhesive application systems in the beverage industry face challenges in maintaining consistent adhesive quantities and preventing delamination, particularly with thinner PET bottles, due to fluctuations in adhesive application caused by pressure and foaming rate variations, leading to unsatisfactory container quality and high reject rates.
A device and method that includes a pressure control circuit with a control and regulating device, pressure sensor, and pumping mechanism to maintain constant hot melt adhesive pressure and foam adhesive pressure, ensuring precise adhesive application by compensating for pressure fluctuations, using a foaming device to produce foam adhesive from hot melt adhesive.
The solution significantly reduces adhesive quantity fluctuations, ensuring high-quality container production by maintaining precise adhesive application, even under varying machine conditions, thereby improving process stability and reducing rejects.
Smart Images
Figure EP2025078592_04062026_PF_FP_ABST
Abstract
Description
[0001] Device and method for applying foam adhesive
[0002] The invention relates to a device and a method for applying foam adhesive to containers.
[0003] Devices or systems for applying adhesives, in particular hot melt adhesives, are generally known. Such devices or systems typically have at least one application head, on which at least one nozzle, namely an adhesive nozzle, is provided, through which the adhesive or hot melt adhesive is dispensed.
[0004] Such devices or systems are also used in the beverage industry, for example, and particularly in packaging machines or systems for the production of container units. Here, for instance, the containers to be assembled into units are coated with spot hot melt adhesive using these devices, in order to bond the containers together to form a container unit. Such packaging machines or systems with a device for applying adhesive or hot melt adhesive are known, for example, from German patent applications DE 10 2012 100 810 A1 and EP 3 245 141 B1.
[0005] Particularly in the beverage industry, for example when producing containers from beverage containers, such as PET bottles, various aspects are crucial in order to manufacture containers of the required quality.
[0006] For example, when separating the container, delamination must be effectively prevented. This means ensuring that the adhesive causes PET layers to detach from the walls of the PET bottles, as such delamination can destabilize the bottles and ultimately lead to them bursting. Due to efforts in the beverage industry to reduce material and resource consumption,
[0007] 12274 WO With the increasing use of PET bottles with ever thinner walls to save costs, the delamination aspect is gaining in importance in the production of containers. Extensive test series conducted by the applicant have shown that delamination can be reduced or prevented if a foam adhesive is formed or produced from the hot melt adhesive and this foam adhesive is applied to the containers.
[0008] Another important aspect in the production of containers with high, consistent quality is adhering to precisely defined adhesive quantities during application. This ensures that the adhesive for spot bonding the containers is always applied in an optimal, as constant as possible, quantity. For example, precisely measured amounts of adhesive, particularly within a range of 50 mg to 250 mg, must be applied to the containers in very short application times, while maintaining tight tolerances. These tight tolerances are crucial because any deviation in the adhesive quantity (either too high or too low) will result in defective containers. For instance, if the amount of adhesive applied is too high, the containers within a single container assembly will no longer be able to be separated.Otherwise, the containers of a given container set may fall apart on their own if the amount of adhesive applied is too small.
[0009] To ensure that the adhesive quantity remains within the permissible tolerance range, certain precautions must be taken. A particularly important factor influencing compliance with the adhesive quantity is the pressure prevailing in the corresponding device for applying the hot melt adhesive, which can also be referred to as adhesive pressure, hot melt adhesive pressure, or system pressure.
[0010] Furthermore, particularly when applying foam adhesive, the amount of adhesive applied to the containers is also influenced by the so-called foaming rate, which indicates, for example, the volume ratio in which the gas used for foaming is added to the hot melt adhesive.
[0011] 12274 WO also provides an indication of the relative volume increase during the production of foam adhesive from hot melt adhesive. Therefore, in order to maintain the aforementioned tight tolerances for the amount of adhesive applied during the application of foam adhesive and to ensure reliable bonding, the foaming rate must always be taken into account during application.
[0012] With solutions known from the prior art, fluctuations in the amount of adhesive still occur disadvantageously when applying hot melt and / or foam adhesives, which often results in unsatisfactory quality of the manufactured containers or an excessive proportion of rejects.
[0013] The object of the invention is to provide an improved device and an improved method for applying foam adhesive, so that fluctuations in the amount of hot melt or foam adhesive applied to the containers are significantly reduced, in particular regardless of process conditions.
[0014] The problem is solved by a device or a method according to the features of the independent claims. Advantageous further developments and embodiments of the invention are specified in the dependent claims.
[0015] The present invention provides a device for applying foam adhesive to containers. The device comprises at least one hot melt adhesive tank for storing the hot melt adhesive and at least one foaming device fluidically connected to the hot melt adhesive tank via a hot melt adhesive line for applying a gas, in particular nitrogen, to the hot melt adhesive to produce a foam adhesive. Furthermore, the device has at least one application head connected to the foaming device via a feeder for applying the foam adhesive to the containers. The device also includes a controllable and / or adjustable pumping device for conveying the hot melt adhesive from the hot melt adhesive tank to the foaming device at a predetermined hot melt adhesive pressure.
[0016] The device is designed as a hot melt adhesive line (12274 WO). It features a pressure control circuit with at least one control and / or regulating device and a pressure sensor connected to the control and / or regulating device for detecting the inlet pressure of the hot melt adhesive at the foaming device. The control and / or regulating device is configured to act on the pumping device depending on the inlet pressure detected by the pressure sensor.
[0017] The device according to the invention can compensate for and thus significantly reduce fluctuations in the amount of hot melt or foam adhesive applied to the containers, thereby ensuring compliance with high quality requirements and significantly improving process stability in the production of containers through spot bonding. Constant adhesive quantities and foam rates can advantageously be maintained even during different dynamic machine states, for example, regardless of machine speeds and even during the start-up or ramp-up of the device or machine.
[0018] The "device" can also be understood, within the meaning of the present invention, as a system for applying foam adhesive and can be used, in particular, in a machine or plant for the production of containerized packaging, for example, so-called multipacks, or can also be a part or component of such a machine or plant. In particular, the device can be used in the beverage industry and be integrated into a treatment and / or packaging machine for treating and / or packaging beverage containers. The containers onto which the foam adhesive is applied by means of the present device are, for example, (beverage) cans or bottles, preferably PET bottles.
[0019] The hot melt adhesive line can, in the present sense, essentially be designed as an adhesive line, for example as a hose or pipe, in particular as a hot melt hose. The hot melt adhesive tank or reservoir connected to the hot melt adhesive line can, for example, be heated by means of a preferably provided heating device. The hot melt adhesive, which is also synonymously called glue, adhesive, or
[0020] 12274 WO, which is designated as hot melt adhesive, is heated to a predetermined temperature, in particular to a melting temperature and / or processing temperature, so that the hot melt adhesive is maintained in a viscous, flowable form. In this viscous, flowable state, the hot melt adhesive is also conveyed in the hot melt adhesive line and introduced into the foaming device.
[0021] It is also conceivable to implement designs in which the hot melt adhesive tank and the foaming device are arranged in close proximity to each other in order to form an essentially integrated or combined structural unit. For example, the foaming device connects directly to the hot melt adhesive tank, so that the hot melt adhesive line is limited to a minimal transition between an outlet of the hot melt adhesive tank and an inlet of the foaming device.
[0022] The at least one application head provided in the device, which in this case can also be referred to as an application head or applicator head, or as an adhesive application head or glue application head, is designed, for example, in a manner known to those skilled in the art. In the present system, several application heads can also be provided, connected in parallel or in series, each of the several application heads preferably being equipped with at least one adhesive nozzle.
[0023] The applicator head, or each applicator head, dispenses the specified, precise amount of hot melt adhesive via the adhesive nozzle(s) and applies it to the containers, thereby creating pinpoint adhesive bonds. Each of these dispensing and application events can be referred to as an application process or a "shot." The applicator head, or each applicator head of the device, operates, for example, at a frequency of up to 500 application processes per minute.
[0024] The pumping device of the present apparatus, which is designed to convey the hot melt adhesive from the hot melt adhesive tank to the foaming device.
[0025] 12274 WO is, can build up pressure, namely in particular pressure in the hot melt adhesive line through which the hot melt adhesive is supplied to the foaming device. Thus, the pumping device according to the present invention is designed to build up pressure upstream of the foaming device, under which the hot melt adhesive is conveyed in the hot melt adhesive line.
[0026] This pressure in the hot melt adhesive line is also referred to as hot melt adhesive pressure. Hot melt adhesive pressure can also be understood as the pressure prevailing during hot melt adhesive transport or as the system pressure of a section of the device upstream of the foaming unit. The hot melt adhesive pressure is preset and selectable or adjustable, at least within a certain range. The preset or adjustable hot melt adhesive pressure can be specified, for example, depending on the application process, particularly product- and / or process-specific factors, such as the type of containers being processed, the hot melt adhesive used, machine power or operating speed, and / or the like.For example, the hot melt adhesive pressure can be specified to a value in the range of 10 bar to 30 bar, preferably to a value in the range of 15 bar to 25 bar and particularly preferably to a value of around 20 bar.
[0027] The device according to the invention offers particular advantages because the pressure control circuit with the control and / or regulating device makes it possible to influence the pumping device in order to control the hot melt adhesive pressure in the hot melt adhesive line and, in particular, to maintain it at the predetermined value. Due to the pressure sensor, which is also part of the pressure control circuit and detects the inlet pressure at the foaming device, particularly directly at one of its inlets, in order to influence the pumping device depending on this detected inlet pressure, the device according to the invention advantageously controls the hot melt adhesive pressure in the hot melt adhesive line all the way to the foaming device, specifically directly to the inlet of the foaming device, which is also referred to as the hot melt adhesive inlet, and maintains it at the predetermined value.
[0028] 12274 WO Surprisingly, experimental tests conducted at the applicant's premises have shown that the hot melt adhesive pressure in the hot melt adhesive line, and in particular the hot melt adhesive pressure upstream of the foaming device, decisively influences the foaming of the hot melt adhesive in the foaming device and significantly affects the foaming rate. Specifically, the hot melt adhesive pressure immediately before or directly at the hot melt adhesive inlet, i.e., immediately before or directly at the inlet of the foaming device, is crucial for the desired foaming rate.
[0029] The foaming rate, which can also be referred to as the foam formation rate or foaming rate, essentially indicates the volume ratio in which the gas is introduced into the hot melt adhesive when it is applied. The foaming rate thus also indirectly indicates the volume increase of the hot melt adhesive during foaming, i.e., the relative increase in volume experienced by the hot melt adhesive during foaming, particularly due to gas inclusions or the gas introduced into the hot melt adhesive by applying the gas. This increase is determined by the relative amount of gas in the hot melt adhesive-gas mixture and by the corresponding expansion of the introduced gas upon pressure release at the nozzle outlet of the applicator head.
[0030] Through the controlling and / or regulating effect of the pressure control loop on the pump device, the hot melt adhesive pressure at the inlet of the foaming device, in particular directly or immediately at its inlet, can be kept constant at the specified value or "adjusted" to this value, which in this case can also be understood as a control loop for regulating the inlet pressure.
[0031] For example, the inlet pressure is "regulated" to 20 bar via this control loop. In this loop, the inlet pressure at the foaming device is measured as an actual value by the pressure sensor, and the hot melt adhesive pressure is regulated to a predetermined setpoint of the inlet pressure by the pressure control loop. This allows the foaming rate to be advantageously controlled within a very narrow range.
[0032] 12274 WO tolerance range is kept constant. Fluctuations in the foam formation rate, especially fluctuations of a magnitude that affect the amount of foam adhesive applied to a given container, namely the melt or foam adhesive quantity or the application quantity, can therefore be almost completely or completely avoided with the device according to the invention.
[0033] The pressure control circuit provided according to the invention ensures that any pressure drop in the hot melt adhesive pressure in the hot melt adhesive line can be compensated for, or is compensated for. The present device thus features pressure fluctuation compensation, which in turn compensates for fluctuations in the foaming rate, ultimately resulting in the avoidance or compensation of fluctuations in the applied amount of foam adhesive. In other words, the pressure drop compensation, or pressure fluctuation compensation, ensures that the same required, defined amount of adhesive is applied to the containers in each application process, thus producing stable, high-quality container units. The required amount of adhesive can be precisely and accurately maintained within a narrow tolerance range.The tolerances of the adhesive spot weights can be advantageously reduced.
[0034] According to a preferred embodiment, an actuator connected to the control and / or regulating device and the pumping device is provided in the pressure control circuit to act on the pumping device. The actuator is in particular a pneumatic actuator and is preferably designed as a proportional valve.
[0035] The actuator is advantageously configured to control and / or regulate the pumping device. Preferably, due to its action on the pumping device, the actuator can control and / or regulate a drive of the pumping device, in particular, for example, control and / or regulate the supply of compressed air used to drive the pumping device, for example, to actuate a piston. In such embodiments, the actuator can also be understood as a drive controller for the pumping device.
[0036] 12274 WO In alternative embodiments, the actuator can also be implemented by a differently designed control valve and, for example, be designed as a pulsed multi-way valve or as a 3 / 2-way valve.
[0037] The pumping device is preferably a positive displacement pump, in particular a pneumatically driven positive displacement pump. A piston pump, in particular a pneumatically driven piston pump, is especially preferred, although alternatively a gear pump or a centrifugal pump can also be used.
[0038] According to a particularly preferred embodiment, the pressure sensor is designed to detect the inlet pressure of the hot melt adhesive directly at an inlet of the foaming device. This enables exceptionally high accuracy in pressure control, thereby further increasing both process and production reliability, as well as, in particular, quality assurance.
[0039] According to a particularly preferred embodiment, the foaming device comprises at least one controllable and / or adjustable pump unit, preferably a multi-stage, controllable and / or adjustable pump unit, as well as a gas supply for applying the gas to the hot melt adhesive. The pump unit is designed to convey the gas-impregnated hot melt adhesive, i.e., the hot melt adhesive-gas mixture, to at least one application head, specifically for conveying the hot melt adhesive-gas mixture under a predeterminable foam adhesive pressure.
[0040] In a similar manner to that described above for the pumping device for conveying the hot melt adhesive, the pumping unit for conveying the gas-charged hot melt adhesive can also build up pressure, specifically a pressure with which the hot melt adhesive-gas mixture is supplied to the at least one applicator head. This pressure is also referred to as foam adhesive pressure. Thus, the pumping unit is part of the foam-generating device in the sense of the laying
[0041] 12274 WO Invention designed to build up pressure in front of the application head, in particular in the feed to the application head.
[0042] The foam adhesive pressure can also be preset and selected or adjusted, at least within a certain range. The preset or adjustable foam adhesive pressure can be specified, for example, depending on the application process, particularly product- and / or process-specific factors, such as the type of containers being processed, the hot melt adhesive used, machine performance or working speed, and / or the like.
[0043] Particularly preferably, the device further comprises at least one foam adhesive pressure control loop with at least one additional control and / or regulating device and at least one application pressure sensor for detecting the application pressure of the foam adhesive prevailing at the application head. The control and / or regulating device of the foam adhesive pressure control loop is configured to act on the pump unit of the foam formation device depending on the application pressure measured by the application pressure sensor.
[0044] This offers particular advantages, as the integrated foam adhesive pressure control loop allows for intervention in the pump unit of the foaming device to control the foam adhesive pressure and, in particular, to maintain it at the specified value. The application pressure at the applicator head is measured by at least one application pressure sensor associated with the foam adhesive pressure control loop, specifically directly at the applicator head, for example, directly at the adhesive nozzle. Depending on this measured application pressure, the pump unit is then adjusted, thus advantageously controlling the foam adhesive pressure all the way to the applicator head and maintaining it at the specified value.
[0045] Since a defined volume of hot melt adhesive gas mixture is removed from the overall system with each application process or "shot",
[0046] 12274 WO This affects the foam adhesive pressure. In conventional, known state-of-the-art solutions, the pressure at the applicator head, and in particular the foam adhesive pressure or application pressure, therefore changes depending on the amount of foam adhesive dispensed per application process, i.e., per "shot". This results in pressure fluctuations in the feed leading from the foam generation unit to the applicator head, and thus also at the applicator head itself. These pressure fluctuations directly affect the amount of adhesive dispensed per container and have a negative impact on maintaining a consistent adhesive application, thus impairing process accuracy and quality assurance in these conventional systems.
[0047] These disadvantages are overcome by the foam adhesive pressure control loop advantageously provided in the present device. In particular, the foam adhesive pressure control loop acting on the pump unit compensates for, or even eliminates, any pressure drop in the foam adhesive pressure in the supply line. This provides an additional pressure fluctuation compensation mechanism, specifically for the foam adhesive pressure. Deviations in the amount of foam adhesive dispensed per application or "shot" can thus be further reduced, and the required amount of adhesive can be maintained even more precisely and accurately within an even narrower tolerance range.
[0048] In other words, the present device advantageously regulates the amount or weight of adhesive by placing an additional pressure sensor as close as possible to the application point and controlling the foam adhesive pressure via the pump unit of the foaming device based on its reading. This further distinguishes the device from the prior art, where fluctuations occur in both the applied amount of adhesive and the foam rate when, for example, machine conditions change, as different pressure drops occur depending on the amount of adhesive dispensed. In the present device, this pressure drop is compensated for by the control system, and the fluctuations are balanced.
[0049] 12274 WO The pressure control circuit and the foam adhesive pressure control circuit of the present device thus work together in a combinatorial and synergistic manner to achieve a very safe and stable compensation of fluctuations in the application quantity of the foam adhesive.
[0050] A multi-stage gear pump is particularly preferred as the controllable and / or adjustable pump unit of the foam formation device. The foam adhesive pressure control loop acts specifically on the multi-stage gear pump, for example, on its rotational speed. It is particularly advantageous for the foam adhesive pressure control loop to act on, for example, a motor-driven drive gear of the multi-stage gear pump by regulating the rotational speed of the drive gear. This can also be understood as drive control of the multi-stage gear pump.
[0051] The application pressure sensor is advantageously designed to detect the application pressure of the foam adhesive directly at the application head. This ensures that the application pressure, which serves as the actual value, is measured as close as possible to the application point, further increasing accuracy.
[0052] According to a preferred embodiment of the device, two or more application heads are provided, and the supply system has two or more supply lines. Each application head is connected to the foaming unit via its own dedicated supply line. Furthermore, each application head is equipped with its own application pressure sensor and its own pump unit for conveying the gas-energized hot melt adhesive to the respective application head. In this preferred embodiment, the control and / or regulating device of the foam adhesive pressure control circuit is configured to act on the respective pump unit for each application head, depending on the application pressure measured by the corresponding application pressure sensor.
[0053] Preferably, the device is designed as an open application system or as an open hot melt adhesive application system with a non-returnable hot melt adhesive flow. This particularly means that the device is linear and
[0054] 12274 WO is configured openly and therefore no closed adhesive circuit is provided, via which adhesive is returned from the application head or from the multiple application heads back to the hot melt adhesive tank and / or to the inlet of the foaming device.
[0055] The present invention also relates to a machine for producing containers from containers joined together by adhesive, comprising a device as described above and preferably a device for applying carrying handles to the containers.
[0056] The present invention further relates to a method for applying foam adhesive to containers. In this method, a hot melt adhesive is stored in a hot melt adhesive tank and fed via at least one hot melt adhesive line to a foaming device for the purpose of applying a gas, in particular nitrogen, to the hot melt adhesive to produce a foam adhesive. The gas-treated hot melt adhesive is fed via a feeder to at least one application head for applying the foam adhesive to the containers. The hot melt adhesive is pumped from the hot melt adhesive tank to the foaming device by means of a pumping device under a predetermined hot melt adhesive pressure in the hot melt adhesive line.A pressure control loop is provided, comprising at least one control and / or regulating device and a pressure sensor connected to the control and / or regulating device for detecting the inlet pressure of the hot melt adhesive at the foaming device. The pressure sensor detects the inlet pressure of the hot melt adhesive at the foaming device. Depending on the detected inlet pressure, the control and / or regulating device acts on the pumping device.
[0057] In a preferred embodiment of the method, the foaming device includes a pump unit for conveying the gas-impregnated hot melt adhesive to the at least one application head under a predefinable foam adhesive pressure, and furthermore a foam adhesive pressure control circuit.
[0058] 12274 WO is provided with at least one further control and / or regulating device and at least one application pressure sensor for detecting the application pressure of the foam adhesive prevailing at the application head, wherein the application pressure is detected via the application pressure sensor. Depending on the detected application pressure, the pump unit is acted upon by means of the further control and / or regulating device.
[0059] According to a particularly preferred variant of the method, an actual value of the inlet pressure of the hot melt adhesive prevailing at the foaming device is measured by means of the pressure sensor and the hot melt adhesive pressure is regulated to a predetermined setpoint of the inlet pressure by means of the pressure control loop.
[0060] Furthermore, the target value of the inlet pressure is preferably set depending on a machine speed and / or a machine throughput.
[0061] The invention will be explained in more detail below with reference to exemplary embodiments shown in the figures. The figures show:
[0062] Fig. 1, in an exemplary and highly simplified manner, sketches an embodiment of a device for applying foam adhesive using a rough schematic block diagram and
[0063] Fig. 2 also illustrates, by way of a rough schematic block diagram and in a highly simplified manner, another embodiment of the device for applying foam adhesive.
[0064] Figures 1 and 2 each show exemplary embodiments of a device 1 for applying foam adhesive in a highly simplified and roughly schematic, diagram-like representation.
[0065] The exemplary device 1 is preferably used in a container treatment machine or system, in particular in a packaging machine for the production of container packages, for example in the beverage industry.
[0066] 12274 WO Device 1 can also be part of such a packaging machine and as such may also be structurally integrated into the packaging machine.
[0067] The device 1 generally includes an adhesive supply for providing a hot melt adhesive, specifically an adhesive supply with a hot melt adhesive tank 2 for storing the hot melt adhesive. In the illustrated examples, the hot melt adhesive tank 2 is associated with a pre-melter in which the hot melt adhesive can be heated, for example, to a suitable temperature corresponding to a melting or processing temperature, so that the hot melt adhesive is in a viscous, flowable form and is available for use in this state. For this purpose, a heating device (not shown and not further described in the figures) is provided, by which, in particular, the hot melt adhesive tank 2 can be heated.
[0068] A hot melt adhesive line 3 leads from and is connected to the hot melt adhesive tank 2 and to a foaming device 7 belonging to the device 1, which is also connected to the hot melt adhesive line 3. The hot melt adhesive tank 2 is thus fluidically sealed to the foaming device 7 via the hot melt adhesive line 3, so that the hot melt adhesive, which is present in viscous, flowable form in the hot melt adhesive tank 2, can be supplied to the foaming device 7 via the hot melt adhesive line 3. The hot melt adhesive is supplied to the foaming device 7 at an inlet 11 of the foaming device 7.
[0069] The foaming device 7, which can also be referred to synonymously as a foaming unit, is designed to pressurize the hot melt adhesive supplied by a pumping device 6 belonging to the apparatus 1 with a gas, in particular nitrogen, and in this way to produce a hot melt adhesive-gas mixture from the supplied hot melt adhesive in order to generate a foam adhesive. The structural and functional design of the foaming device 7 is described in more detail below in connection with the example of Figure 2.
[0070] 12274 WO In order to supply the hot melt adhesive gas mixture or the foam adhesive produced in the foaming device 7 to the at least one application head 5, 5' provided for applying the foam adhesive to the containers, the device 1 has a feed 4 connected on the outlet side to the foaming device 7, namely to or via an outlet 12, 12' of the foaming device 7 in a fluidically tight manner, through which the hot melt adhesive gas mixture produced in the foaming device 7 is conveyed from the foaming device 7 and transported in the direction of the application head or the application heads 5, 5'.
[0071] In the example of Figure 1, the device 1 has one applicator head 5, and in the example of Figure 2, it has two applicator heads 5, 5'. The applicator head 5 or the applicator heads 5, 5' are fluidically connected to the foaming device 7 via the feed 4, with each applicator head 5 being equipped with a respective adhesive nozzle 5.1, through which the foam adhesive is dispensed or applied to the containers during operation of the device 1.
[0072] Application processes are thus carried out at each application head 5, 5', in particular at a predetermined frequency, whereby a specific, precisely metered quantity of foam adhesive is dispensed and applied to the respective containers in each application process. Optionally, the feeder 4 and / or the application head 5 or the application heads 5, 5' can also be heated to prevent cooling and premature, undesirable solidification of the hot melt adhesive-gas mixture during conveying.
[0073] Both embodiments shown in the figures illustrate that, according to an important aspect of the present invention, the device 1 is designed to be able to control the supply of the hot melt adhesive to the foaming device 7.
[0074] 12274 WO In the present device 1, the hot melt adhesive is actively conveyed from the hot melt adhesive tank 2 to the foaming device 7, namely, in particular, pumped, wherein the device 1 has the controllable and / or adjustable pumping device 6 for this purpose. During operation, the controllable and / or adjustable pumping device 6 builds up a pressure in the hot melt adhesive line 3, which is understood here as the hot melt adhesive pressure p of the hot melt adhesive in the hot melt adhesive line 3. The pumping device 6, which in the illustrated examples of the figures is a pneumatically driven piston pump, can thus convey the hot melt adhesive in the hot melt adhesive line 3 at the hot melt adhesive pressure p.
[0075] The hot melt adhesive pressure p in the hot melt adhesive line 3 is predefined and can be specified or set, for example, according to the application and / or production requirements. For instance, the hot melt adhesive pressure p can be specified or set as a process parameter or operating parameter, particularly depending on the type of hot melt adhesive and / or container being processed, the quantity of hot melt adhesive to be applied per container, the frequency of application, and / or the production speed or power output of the device 1. In the examples shown, the value for the predefined hot melt adhesive pressure p is approximately 20 bar.
[0076] In order to prevent or compensate for a pressure drop in the hot melt adhesive line 3 when the hot melt adhesive is supplied to the foaming device 7, the device 1 has a pressure control circuit RC1, via which the hot melt adhesive pressure p can be kept at the specified value over the entire hot melt adhesive line 3, namely up to the hot melt adhesive inlet 11 of the foaming device 7.
[0077] The pressure control circuit RC1 comprises a control and / or regulating device 100 and a pressure sensor 8 connected to the control and / or regulating device 100, which is designed to detect the inlet pressure of the hot melt adhesive prevailing at the hot melt adhesive inlet 11 of the foaming device 7.
[0078] 12274 WO the pressure control circuit RC1 the control and / or regulating device 100 acts on the pumping device 6 depending on the input pressure detected by means of the pressure sensor 8.
[0079] In the examples shown in the figures, a proportional valve connected to the control and / or regulating device 100 and the pump unit 6 is provided as a pneumatic actuator 9 in the pressure control loop RC1. The proportional valve 9 acts on the pump unit 6, which is designed as a piston pump, by varying or regulating the supply of compressed air, which serves as the piston drive of the piston pump 6. Specifically, it throttles or increases the supply depending on the detected inlet pressure – which in this case represents the actual value – thereby allowing the piston pump 6 to be regulated to the predetermined hot melt adhesive pressure p, which in this case represents a setpoint.
[0080] The inlet pressure at the hot melt adhesive inlet 11 of the foaming device 7, that is, the pressure with which the hot melt adhesive is introduced into the foaming device 7, significantly influences the production of the foam adhesive and is reflected, for example, directly in the foam rate, which in turn directly affects the amount of foam adhesive dispensed or applied per application process per container.
[0081] Therefore, maintaining a constant hot melt adhesive pressure p – especially at the hot melt adhesive inlet 11 – is crucial to ensure that the foam rate remains stable and that the defined, precisely specified amount of foam adhesive is applied to the containers in each application process, so that deviations in the respective application processes are within a permissible, very narrow tolerance range.
[0082] The pressure control circuit RC1 ensures that the specified hot melt adhesive pressure p remains constant up to the hot melt adhesive inlet 11, meaning that the inlet pressure corresponds to the specified hot melt adhesive pressure p and thus any potential pressure drop across the hot melt adhesive line 3 is compensated. The pressure control circuit RC1 provided in the device 1 enables precise
[0083] 12274 WO Setting, tracking and maintaining constant hot melt adhesive pressure p is possible, whereby pressure fluctuations can be effectively compensated, regardless of operating or machine condition.
[0084] In the example shown in Figure 2, in addition to the pressure control circuit RC1 for maintaining the constant hot melt adhesive pressure p, a foam adhesive pressure control circuit RC2 is also provided, via which a foam adhesive pressure pf, pf' of the hot melt adhesive gas mixture or of the foam adhesive produced by means of the foaming device 7 in the feed 4 can be controlled and a pressure drop in the feed 4 can be compensated.
[0085] To illustrate this, the structure and function of the foaming device 7 will first be described in more detail below.
[0086] The hot melt adhesive, which is fed into the foaming device 7 via the hot melt adhesive inlet 11, is pressurized with gas, in particular nitrogen, by means of a gas supply 13, which in the example shown in Figure 2 is connected to a gas reservoir 13a (which may optionally be part of the device 1 or external). The gas or nitrogen is supplied at a constant gas or nitrogen pressure of, for example, 4 bar. To produce a uniform hot melt adhesive-gas mixture and to convey the gas-pressurized hot melt adhesive to the at least one application head 5, 5', a controllable and / or adjustable pump unit 14 is also provided in the foaming device 7.
[0087] Since the device 1 in the example of Figure 2 comprises two application heads 5, 5', the foaming device 7 also has two controllable and / or adjustable pump units 14, 14', each of which is assigned to a respective application head 5, 5' and is configured to pump the gas-charged hot melt adhesive to the respective application head 5, 5'. The pump units 14, 14' are designed to pump the gas-charged hot melt adhesive, namely the hot melt adhesive-gas-
[0088] 12274 WO mixture, to be conveyed under a predetermined foam adhesive pressure pf, pf' to the respective application heads 5, 5', in corresponding, respective supply lines 4a, 4a' of the supply 4.
[0089] Similar to the hot melt adhesive pressure p in the hot melt adhesive line 3, the foam adhesive pressure pf, pf' can also be specified or set, for example, application-related and / or production-specific, for example, as a process parameter or operating parameter, which may depend in particular on the type of hot melt adhesive and / or the containers, on the amount of hot melt adhesive to be applied per container, and / or on the production speed or output of the device 1. In the example shown, the value for the specified foam adhesive pressure pf, pf' is approximately 55 bar.
[0090] Each of the controllable and / or adjustable pump units 14, 14', which conveys the gas-pressurized hot melt adhesive under the foam adhesive pressure pf, pf', is a multi-stage gear pump with several successive stages, from a first stage to a final stage 14.n. The foam adhesive pressure control loop RC2 acts as a controllable or regulating mechanism on the multi-stage gear pump 14, 14', in particular on the rotational speed of the multi-stage gear pump 14, 14'.
[0091] The foam adhesive pressure control loop RC2 comprises a further control and / or regulating device 110 and corresponding application pressure sensors 10, 10', each provided directly at each application head 5, 5', which detect or measure the application pressure of the foam adhesive directly at the respective application head 5, 5'. Depending on the detected or measured application pressure, the control and / or regulating device 110 acts on the multi-stage gear pumps 14, 14', for example by varying the rotational speed of the motor-driven drive gear of the gear pump 14, 14'.
[0092] The foam adhesive pressure control loop RC2 thus allows advantageous control of the gear pump 14, 14' of the foam formation device 7 by varying or regulating the rotational speed of the drive gear, namely by increasing or decreasing it.
[0093] 12274 WO depending on the detected application pressure - which in this case represents the actual value - is throttled or increased, whereby the gear pump 14, 14' can be regulated to the specified foam adhesive pressure pf, pf' - which in this case forms a target value.
[0094] The application pressure at the applicator heads 5, 5' significantly influences the dispensing of the foam adhesive and is directly reflected, for example, in the amount of foam adhesive dispensed or applied to each container per application process. Therefore, maintaining a constant foam adhesive pressure pf, pf' directly at the applicator heads 5, 5' is crucial to ensuring that the defined, precisely specified amount of foam adhesive is applied to the containers in each application process.
[0095] The RC2 pressure control circuit ensures that pressure fluctuations, which occur during the application process when dispensing foam adhesive, for example due to volume discharge, are effectively compensated.
[0096] By combining the two control loops, namely the pressure control loop RC1 and the foam adhesive pressure control loop RC2, the present device 1 can synergistically ensure that the amount of hot melt adhesive can be kept constant within a very narrow tolerance range for optimal quality results in the production of container packages.
[0097] The invention has been described above using exemplary embodiments. It is understood that numerous modifications or adaptations are possible without departing from the underlying inventive concept.
[0098] 12274 WO Reference List
[0099] 1 Device for applying foam adhesive
[0100] 2 hot melt adhesive tanks
[0101] 3 Hot melt adhesive line
[0102] 4 Feed
[0103] 4a, 4a' Supply lines
[0104] 5.5' Applicator head
[0105] 5.1 Adhesive nozzle
[0106] 6 Pumping equipment
[0107] 7 Foam forming device
[0108] 8 pressure sensors
[0109] 9 Actuator
[0110] 10, 10' Application pressure sensors
[0111] 11 Hot melt adhesive inlet
[0112] 12, 12' Exit
[0113] 13 Gas supply
[0114] 13a Gas storage tank
[0115] 14, 14' Pump unit
[0116] 14. Last stage of the pump unit
[0117] 100 Control and / or regulating device
[0118] 110 Control and / or regulating device
[0119] P Hot melt adhesive printing pf, pf' Foam adhesive printing
[0120] RC1 pressure control circuit
[0121] RC2 foam adhesive pressure control loop
[0122] 12274 WO
Claims
Patent claims 1. Device (1) for applying foam adhesive to containers, comprising at least a hot melt adhesive tank (2) for storing a hot melt adhesive, at least one foaming device (7) fluidically connected to the hot melt adhesive tank (2) via a hot melt adhesive line (3) for applying a gas, in particular nitrogen, to the hot melt adhesive to produce a foam adhesive, and at least one application head (5, 5') connected to the foaming device (7) via a feed (4) for applying the foam adhesive to the containers, wherein the device (1) further comprises a controllable and / or adjustable pumping device (6) designed to convey the hot melt adhesive from the hot melt adhesive tank (2) to the foaming device (7) under a predeterminable hot melt adhesive pressure (p) of the hot melt adhesive in the hot melt adhesive line (3),wherein the device (1 ) has a pressure control circuit (RC1 ) with at least one control and / or regulating device (100) and a pressure sensor (8) connected to the control and / or regulating device (100) for detecting an inlet pressure of the hot melt adhesive prevailing at the foaming device (7) and wherein the control and / or regulating device (100) is configured to act on the pumping device (6) depending on the inlet pressure detected by means of the pressure sensor (8).
2. Device (1) according to claim 1, characterized in that an actuator (9), in particular a pneumatic actuator, is provided in the pressure control circuit (RC1) to act on the pumping device (6), which is preferably designed as a proportional valve and is connected to the control and / or regulating device (100) and the pumping device (6).
3. Device (1 ) according to claim 1 or 2, characterized in that the pumping device (6) is a positive displacement pump, in particular a pneumatically driven positive displacement pump, preferably a piston pump.
4. Device (1) according to one of the preceding claims, characterized in that the pressure sensor (8) is configured to measure the inlet pressure of the 12274 WO to capture hot melt adhesive directly at a hot melt adhesive inlet (11) of the foaming device (7).
5. Device (1) according to one of the preceding claims, characterized in that the foaming device (7) comprises at least one controllable and / or adjustable pump unit (14, 14'), preferably a multi-stage, controllable and / or adjustable pump unit (14, 14'), and a gas supply (13) for applying the gas to the hot melt adhesive, wherein the pump unit (14, 14') is designed to convey the hot melt adhesive applied with the gas to the at least one application head (5, 5') under a predeterminable foam adhesive pressure (pf, pf').
6. Device (1) according to claim 5, characterized in that the device (1) further comprises at least one foam adhesive pressure control circuit (RC2) with at least one further control and / or regulating device (110) and at least one application pressure sensor (10, 10') for detecting an application pressure of the foam adhesive prevailing at the application head (5, 5'), wherein the control and / or regulating device (110) of the foam adhesive pressure control circuit (RC2) is configured to act on the pump unit (14, 14') of the foam formation device (7) depending on the application pressure measured by means of the application pressure sensor (10, 10').
7. Device (1 ) according to claim 5 or 6, characterized in that the controllable and / or adjustable pump unit (14, 14') of the foaming device (7) is a multi-stage gear pump.
8. Device (1 ) according to one of claims 5 to 7, characterized in that the application pressure sensor (10, 10') is designed to detect the application pressure of the foam adhesive directly at the application head (5, 5').
9. Device (1) according to any one of the preceding claims 5 to 8, characterized in that two or more application heads (5, 5') are provided and the feed (4) has two or more feed lines (4a, 4a'), wherein 12274 WO Each applicator head (5, 5') is connected to the foaming device (7) via a respective, assigned supply line (4a, 4a'), wherein each applicator head (5, 5') is furthermore assigned its own application pressure sensor (10, 10') and its own pump unit (14, 14') for conveying the gas-impregnated hot melt adhesive to the respective applicator head (5, 5') and the control and / or regulating device (110) of the foam adhesive pressure control circuit (RC2) is configured to act on the respective assigned pump unit (14, 14') for each applicator head (5, 5') depending on the application pressure measured by means of the corresponding application pressure sensor (10, 10').
10. Device (1 ) according to one of the preceding claims, characterized in that the device (1 ) is designed as an open application system with a non-returnable hot melt adhesive flow.
11. Machine for producing containers from containers joined together by hot melt adhesive, comprising a device (1) according to one of the preceding claims and preferably a device for applying carrying handles to the containers.
12. Method for applying foam adhesive to containers, in which a hot melt adhesive is stored in a hot melt adhesive tank (2) and supplied via at least one hot melt adhesive line (3) to a foaming device (7) for applying a gas, in particular nitrogen, to the hot melt adhesive to produce a foam adhesive, wherein the hot melt adhesive supplied with the gas is fed via a feed (4) to at least one application head (5, 5') for applying the foam adhesive to the containers, wherein the hot melt adhesive is conveyed by means of a pumping device (6) from the hot melt adhesive tank (2) to the foaming device (7) under a predeterminable hot melt adhesive pressure (p) in the hot melt adhesive line (3),wherein a pressure control circuit (RC1) is provided with at least one control and / or regulating device (100) and a pressure sensor (8) connected to the control and / or regulating device (100) for detecting an inlet pressure of the hot melt adhesive prevailing at the foaming device (7) and via which, 12274 WO The pressure sensor (8) detects the prevailing inlet pressure of the hot melt adhesive at the foaming device (7), and the control and / or regulating device (100) acts on the pumping device (6) depending on the detected inlet pressure.
13. Method according to claim 12, characterized in that the foaming device (7) has at least one pump unit (14, 14') for conveying the hot melt adhesive supplied with the gas to the at least one application head (5, 5') under a predefinable foam adhesive pressure (pf, pf'), wherein furthermore a foam adhesive pressure control circuit (RC2) with at least one further control and / or regulating device (110) and at least one application pressure sensor (10, 10') is provided for detecting an application pressure of the foam adhesive prevailing at the application head (5, 5') and the application pressure is detected via the application pressure sensor (10), and wherein, depending on the detected application pressure, the pump unit (14, 14') is acted upon by means of the further control and / or regulating device (110).
14. Method according to claim 12 or 13, characterized in that an actual value of the inlet pressure of the hot melt adhesive prevailing at the foaming device (7) is measured by means of the pressure sensor (8) and the hot melt adhesive pressure (p) is regulated to a predetermined setpoint of the inlet pressure by means of the pressure control loop (RC2).
15. Method according to one of claims 12 to 14, characterized in that the setpoint of the inlet pressure is adjusted as a function of a machine speed and / or a machine throughput. 12274 WO