Monitoring and control system, and machine for facilities for applying foam adhesive

Abstract

A monitoring and control system for facilities for applying foam adhesive. The invention comprises selecting monitoring points for monitoring pressure, flow rate and speed values, and means for controlling said values. The pressure monitoring points are the adhesive inlet into the suction stage of the foam-generating pump and the intermediate chamber between the gear stages of the pump. The flow rate monitoring points are the flow rate of gas and the flow rate of melted adhesive entering the pump. The rotational speed monitoring points are in the pump. Optionally, a calibrated piston pump is provided in the inlet for the melted adhesive into the foam-generating pump. Pressure control means and flow rate control means are also provided, which receive the values from the monitoring points and generate control signals.

Description

[0001]

[0002] MONITORING AND CONTROL SYSTEM, AND MACHINE FOR FOAM-BASED ADHESIVE APPLICATION INSTALLATIONS

[0003] Technology sector

[0004] The present invention relates to the technical field of applying foamed adhesive by combining, under pressure, a hot-melt adhesive and a gas. More specifically, the invention relates to a monitoring and, optionally, control system applicable to foamed adhesive application installations (which may be in the form of systems, apparatus, devices, machinery, and the like) for the purpose of producing an optimal mixture of adhesive and gas.

[0005] State of the art

[0006] The application of foamed adhesive consists of providing, on the one hand, a flow of adhesive in a molten state and, on the other hand, a flow of gas, which combine to produce the foamy mass, suitable for application on the desired surfaces.

[0007] According to a foam adhesive application installation, firstly, a supply of molten adhesive is made, which can generally be of three types: by gravity, providing the adhesive directly from a tank containing the molten mass, by means of a closed tank with a piston that pushes the adhesive for its melting, and supply in a molten state, for cases of block adhesive such as PUR, with controlled supply of molten adhesive with a pre-melt equipment that, as its name indicates, melts the adhesive and supplies it by means of a feed pump.

[0008] Subsequently, the molten adhesive is supplied to a mixing pump where it is mixed with a gas. The pump used is a foam-generating pump, which includes a geared suction stage that draws in the adhesive from the supply, and a mixing and pumping stage. Between these two stages, the gas is introduced in the appropriate proportion to mix with the molten adhesive and achieve the characteristic consistency of the foam. In the mixing and pumping stage, the molten adhesive and gas are first mixed to create the foam mixture, which is then pumped to the application point. Once applied, the gas bubbles, which are compressed and transported throughout the system, expand, thus generating foamed adhesive.Some of the requirements for optimal adhesive quality include ensuring the most uniform expansion of the gas bubbles possible, that the bubbles are small and homogeneous, and that the adhesive-to-gas ratio of the mixture remains within appropriate values ​​for the intended application. Controlling the applied quantity is also quite complex because these are non-Newtonian, viscoelastic, and compressible fluids. This means that the adhesive's volume and density change depending on the pumping pressure.

[0009] On the other hand, a number of additional problems arise in order to provide the correct amount demanded.

[0010] During the mixing and pumping stage, a volume of adhesive and gas is absorbed, directly proportional to the volume each occupies in the intermediate zone between the suction and mixing stages. After application, the volume of the foamed adhesive will depend on the amount of adhesive and gas absorbed. While the adhesive volume doesn't change much, the gas volume depends on the absorbed mass, which in turn depends on the pressure at which the gas is absorbed, and therefore, on the pressure in the zone between the suction and mixing / pumping stages. If the adhesive introduced during the suction stage is under high pressure, it will expand, leaving less volume for the gas.The gas occupies the remaining volume with the pressure in that intermediate zone: this causes the amount of gas absorbed in the mixing and pumping stage to be less than that corresponding to the ratio of volumes of the gears of the suction and mixing and pumping stages, and therefore will have a lower percentage of gas in the applied foam.

[0011] This overpressure of the adhesive introduced by the suction stage can occur because the adhesive feed to the foam generation pump creates high pressure at the pump inlet, for example, when the flow rate demand is high and the supply pressure is increased in a poorly controlled manner to meet it. Another significant problem arises, for example, in certain applications that require intermittent adhesive application or variable flow rates. In these cases, the adhesive demand may be low or drop to zero at certain times. If the demand is low, the foam generation pump will rotate slowly, and therefore the suction effect of the mixing and pumping stage will be lost. This facilitates internal leaks, due to possible internal mechanical misalignments in the pump, allowing adhesive and / or gas to enter from the outlet area of ​​the mixing and pumping stage, causing the pressure between stages to rise.

[0012] Furthermore, if the pressure in the area between chambers is less than the adhesive feed pressure at the suction stage inlet, as the pump slows down the effect of the adhesive overpressure at the inlet becomes more noticeable, and when the pump stops, the effect of internal leakage from the adhesive inlet through the suction stage becomes more pronounced.

[0013] This excess pressure between stages of the foam generating pump can prevent the entry of the necessary amount of gas for the desired proportion in the mixture, since it can slow the inlet flow if the pressure inside the pump is not less than the gas pressure in the feed channel, even cutting off the entire supply if the pressure difference between the inside and the feed is greater than the minimum necessary for the non-return valve of the gas inlet to open.

[0014] One of the regulation systems used to apply foam adhesive with the correct amount of gas and adhesive involves recirculation systems. These systems utilize complex closed-loop configurations with recirculation, where the foamed adhesive is recirculated back to the foam generation pump to compensate for the flow rate variations required during application. These systems solve the problem of foam generation at very low or zero pump speeds if the application is interrupted. However, they suffer from significant imbalance issues because they introduce foamed adhesive into the adhesive and gas mixing zone of the foam generation pump, making it very difficult to control the mixture ratio. Furthermore, the quality of the applied foam decreases with recirculation.

[0015] Another installation alternative is the direct application system, which does not recirculate the foamed adhesive back to the foam generation pump. In these systems, the adhesive quality is maintained because the foamed adhesive is not recirculated. However, there is no way to accommodate changes in foam flow rate demand, forcing the pump to slow down or even stop. This presents the problems of controlling and maintaining the adhesive-to-gas flow rate ratio, as previously mentioned.

[0016] That is why a solution is needed for the perfect control of foam generation with a set quality, which adapts to the demand for variable foam quantity depending on changes in production speed (or according to products), controlling with the greatest precision the mass flows of air and adhesive that enter between the suction and mixing stages, changing their quantity according to changes in the total quantity, but maintaining the same relative proportion between them.

[0017] Object of the invention

[0018] According to the objectives set forth in the preceding section, the object of the present invention is a monitoring and control system for direct-application foamed adhesive systems. These systems typically comprise, essentially, a molten adhesive supply system (in the form of an adhesive tank and / or a pre-melting unit), a gas supply system, and a foaming system with a foam generation pump that includes a suction stage into which the molten adhesive is introduced and a mixing and pumping stage, with the mixing gas being introduced into the space between these stages. It is envisaged that the foam generation pump may have multiple stages, but there will always be an intermediate chamber or space between a suction stage and a mixing and / or pumping stage into which the gas is introduced.

[0019] In the invention, several monitoring points for pressure, flow rate, and rotational speed values ​​are selected, and, optionally, various means of controlling these values ​​are provided. Pressure monitoring points are, for example, in the adhesive supply system of a pre-fusion unit, at the adhesive inlet to the suction stage of the foam-generating pump, and in the intermediate chamber where gas is injected between the suction and mixing stages of said foam-generating pump; corresponding pressure gauges are connected to these points. Flow rate monitoring points are the gas flow rate and the molten adhesive flow rate entering the foam-generating pump; corresponding flow meters are connected to these points at suitable points along the adhesive and gas inlet lines, either at the inlets to the foam-generating pump itself or at other points along the line that provide representative values.The points for monitoring rotation speeds are, for example, the rotation speed of the last stage of the foam generating pump, where this speed varies according to the demand for foamed adhesive supplied.

[0020] The system that is the subject of the invention is understood to be suitable for foamed adhesives, but it will also be valid for other types of fluids to be foamed, such as a butyl used subsequently as a sealant, without altering the object of the invention.

[0021] The information obtained will allow us to adapt the installation parameters to solve the problems raised in the state of the art section.

[0022] According to another feature of the invention, pressure control means are provided such that they receive, as inputs, the values ​​of one or more of the pressure gauges mentioned above and provide, as output, a control signal; this control signal is carried to a pressure regulator connected and arranged to regulate the pressure of the molten adhesive coming from the pre-fusing equipment, preferably, although not exclusively, at the inlet of the foaming pump or at a point in the supply means, including the outlet of said pre-fusing equipment.These pressure control means can also provide a control signal to regulate the pressure of the gas entering the intermediate chamber between the suction and mixing stages of the foam generating pump, by means of a gas pressure regulator supplied in the line connecting the gas supply means to the foaming station or by means of a control output of a gas flow regulating pump.

[0023] According to another feature of the invention, the system comprises monitoring points for the flow of gas and molten adhesive entering the foam-generating pump. For this purpose, corresponding flow meters are connected at suitable points along the adhesive and gas inlet lines, either at the inlets to the foam-generating pump itself or at other points along the line that provide representative values. In this way, flow readings from the flow meters can be taken and fed into flow control means to obtain regulating signals.These control signals can take the form of a signal that, in the case of a liquid adhesive feed pre-fusion unit, controls the rotational speed of the liquid adhesive feed pump; a signal that regulates the adhesive supply pressure at a point in the supply system, including the outlet of the pre-fusion unit, by means of a pressure regulator of the type mentioned in the previous paragraph; and a signal that controls the pressure at which the gas is supplied to the foam generating pump, also by means of, for example, a gas pressure regulator or a gas flow regulating pump control output, as mentioned in the previous paragraph.

[0024] According to another feature of the invention, the system comprises points for monitoring the rotational speed of the foam pump. For this purpose, the rotational speed of the foam-generating pump is measured at appropriate points along the pump, either in the suction, mixing, and pumping stages, or in subsequent stages, or at other points that provide representative values. In this way, the rotational speed readings of the foam-generating pump can be taken and fed into flow control means to obtain regulating signals.These regulating signals can take the form of a signal that, in the case of having a liquid adhesive feeding pre-melt unit, controls the rotation speed of the liquid adhesive feeding pump, a signal that regulates the adhesive supply pressure at a point in the supply means, including the outlet of the pre-melt unit by means of a pressure regulator of the type mentioned in the previous paragraph, and a signal that controls the pressure at which the gas is supplied to the foam generating pump, also by means, for example, of an adhesive flow regulating pump control output arranged in the molten adhesive supply line or a gas flow regulating pump control output in the line connecting the gas supply means to the foaming station.

[0025] In an alternative embodiment of the invention, the pressure control means and the flow control means are embodied in a single pressure and / or flow control means, i.e., a single functional and physical entity that serves to perform controls of the supplied gas and / or adhesive pressure based on both flow and pressure values ​​and, taking as input(s), any combination of these measured reference values ​​mentioned above.

[0026] The system of the invention may also include a bypass valve arranged to divert at least part of the molten adhesive inlet flow to the foam-generating pump, recirculating it to the melting tank or the pre-melting equipment that supplies the molten adhesive. This valve is arranged so that a molten adhesive inlet pressure threshold can be set, and it diverts the flow when it detects that threshold is exceeded. The diversion, as mentioned, may involve only part of the inlet flow or all of it, and simultaneously with this diversion, the valve may partially or completely close the inlet path to the foam-generating pump, or simply leave it open.

[0027] Both the pressure regulator for the supplied molten adhesive and the pressure regulator for the supplied gas can be, or may include, proportional type valves.

[0028] Optionally, and alternatively or in combination with any of the above options, a piston pump calibrated to a defined pressure is provided, which can be modified by manual operation or by control means at the inlet of the molten adhesive to the foam generating pump.

[0029] In an alternative embodiment of the invention, the flow control means provide control of an adhesive flow regulating pump and control of a gas flow regulating pump, where said outlet flows of the adhesive and gas flow regulating pumps are kept regulated and adapted to the demand for foamed adhesive at any given time.

[0030] Alternatively, the control of adhesive and gas is carried out by means of the pressure regulator located at a point of the molten adhesive supply means, including the outlet of the pre-fusion equipment and alternatively or in combination with this, by means of a pressure regulator connected in the gas supply line coming from the gas supply means, both regulators adapting to the pressure and adhesive needs according to the demand for foamed adhesive at any given time.

[0031] In the various control systems mentioned above, whether pressure-based, flow-based, or combining both, parameters or variables (their actual values) can be entered for the defined function of those control systems. These values ​​can be entered manually, for example, via a touchscreen, keyboard, or similar device, or via wired or wireless communication. The entered values ​​include, for example, setpoint values ​​for the feedback loops defined by the different control systems.

[0032] The different control means, explained for example in the previous paragraph, may include software storage means (in the form, for example, of one or more memories) to store the different algorithms that manage the aforementioned controls and corresponding processing means; among the latter, PID controllers may be included.

[0033] The system can also include alarms to warn of anomalous readings from various pressure gauges and flow meters. These alarms will trigger when anomalous values ​​(for example, values ​​outside predefined ranges) persist for a minimum period deemed to pose a risk to the proper functioning of the installation. Any of the aforementioned control methods can be used for this purpose, leveraging their corresponding software storage and processing capabilities.

[0034] Preferably, the different flow meters mentioned throughout this section can be volumetric or mass flow meters, preferably mass flow meters, which are advantageous in situations where density variations may occur.

[0035] Finally, according to another aspect of the invention, a foam adhesive application machine is contemplated comprising a system according to the characteristics described above.

[0036] Therefore, the invention consists of a direct system that, with the information obtained from monitoring, performs precise control of the amount of gas and adhesive present in the chamber between the suction and mixing stages, in order to obtain an optimal quality of the application foam, that is, adjusting and maintaining the desired proportion of gas and foamed adhesive according to the variable flow rate demanded by the application.

[0037] Description of the figures

[0038] The drawings attached to this document are listed and briefly described below, by way of non-limiting example, to illustrate and facilitate the interpretation of the monitoring and control system disclosed in this invention.

[0039] Figures 1 and 2 are two schematic views of a direct application installation of foamed adhesive according to the existing technique and in its two modes of adhesive supply by gravity and by use of a pre-fusion equipment.

[0040] Figures 3a, 3b, 4 and 5 are three examples of the implementation of the monitoring system of the present invention applied in a foamed adhesive installation and in its pressure monitoring mode.

[0041] Figure 6 is an embodiment of the system of the present invention in which a calibrated piston pump is applied.

[0042] Figures 7 and 8 are two examples of the implementation of the monitoring system of the present invention applied in a foamed adhesive installation and in its flow monitoring mode.

[0043] Figure 9 is an embodiment of the present invention illustrating the use of a bypass valve at the inlet of the molten adhesive to the foaming station of the foam adhesive application system. Figure 10 is an embodiment of the monitoring system of the present invention applied to a foam adhesive system, specifically in the form of regulating the flow rate adapted to the rotational speed of the foam pump.

[0044] Detailed description of the invention

[0045] A detailed description of the invention will then be carried out with reference to the figures outlined in the previous section.

[0046] Figures 1 and 2 show two examples of open-loop installations for applying foamed adhesive. The first installation uses a tank (10) to supply the molten adhesive, while the second uses a pre-melt unit (20) shaped like a pump to deliver the molten adhesive. A third option would be an installation using a closed tank with a piston that pushes the adhesive to melt it, and supplying it in a molten state, for block-shaped adhesives such as PUR (not shown in the figures).

[0047] Figures 1 and 2 schematically represent two foam adhesive application systems, corresponding to gravity-fed adhesive application and controlled adhesive application with a pre-fusion unit, respectively. The gas supply means (50) are represented schematically, for illustrative purposes only, by a compressed gas cylinder. These gas supply means (50) can be pressure-based, flow-based, mass-based, etc.

[0048] Reference (90) designates a hose (90) of molten adhesive to carry the latter to the foam generating pump (30) of the foaming station; although, in this and the rest of the figures, in order to schematize them, said hose (90) is represented occupying only a section of the line that joins the pre-fusor equipment (20) with the pump (30), it is evident, as experts in the field know, that said hose (90) can occupy the entirety or practically the entirety of that route.

[0049] Figures 3a and 3b show a first example of the implementation of the monitoring and control system of the present invention. It is worth recalling at this point that the purpose of this system is to provide, at the outlet of the foaming station, more specifically at the outlet of the application applicator (40) (Figures 1 and 2), a homogeneous and uniform application of foam, with the least possible variability in its physical properties, regardless of the varying foam demand at the specific application point and factors such as the adhesive temperature, the length and diameter of the different hoses involved in its delivery, the rheology and density of the adhesive used, possible failures, malfunctions, and tolerances of components and parts of the installation, etc.

[0050] To this end, in a first embodiment (Figures 3a, 3b, 4, and 5), two pressure gauges (62, 64), T1 and T2, are provided in the foam-generating pump (30), specifically in the part of the pump (30) where the molten adhesive enters and in the intermediate part or chamber between the suction stage (32) and the mixing and pumping stage (34), where the gas from the gas supply means (50) is injected. In these and subsequent figures, system and installation components that do not influence the technical elements relating to the claimed characteristics have been omitted, such as, for example, the application applicator (40) or the gas supply line in Figures 3a, 3b, and 4.

[0051] When working with a foaming system, the molten adhesive can be supplied from a pre-fusion unit (20) via a heated hose (90). The adhesive pressure at the inlet of the foam-generating pump (30), T1, varies depending on the pressure set in the pre-fusion unit (20), P1, and the pressure drop along the hose (90) connecting the two points. This pressure drop depends primarily on three factors: the type of hose (90) (inner tube diameter and length), and the rheology and flow rate of the adhesive. For this reason, the flow meter (62) can be placed at any point along the molten adhesive supply line up to the pump's (30) suction stage (32), but the preferred embodiment of the invention is to place it at the point closest to this suction stage (32), as shown in Figures 3a and 3b.

[0052] During laboratory tests, it was found that pressure variations at the adhesive inlet to the foam-generating pump (30), caused mainly by changes in the applied adhesive flow rate due to application requirements, influence the gas percentage in the mixture produced in the pump (30). On the other hand, if the adhesive pressure in the pre-fusion unit (20) is kept constant, two things can happen:

[0053] • By increasing the flow rate, the inlet pressure, T1, decreases, and a higher percentage of gas is obtained.

[0054] • By decreasing the flow rate, the inlet pressure, T1, increases, and a lower percentage of gas is obtained.

[0055] In turn, it has been verified that, by maintaining a controlled relationship between the pressure, T1, at the pump inlet (30), and the gas pressure at the pump inlet (30), Pg, a constant percentage of gas is achieved regardless of the adhesive flow rate.

[0056] To maintain the same percentage of gas in the mixture for any flow demand, it is necessary that the adhesive and gas pressure, before the formation of the foam, at the pump inlet (30), T1, or between the two gear stages (32, 34) of said pump (30), T2, be constant.

[0057] To this end, on the one hand, the aforementioned pressure gauge (62) is provided at the pump inlet (30), which monitors the adhesive pressure, T1, and sends a signal to the pressure regulator (82) of the pre-fusion unit (20) in order to modify the adhesive pressure, P1, of the pre-fusion unit (20) and maintain a constant pressure, T1, at the pump inlet (30).

[0058] Therefore, a closed-loop control is established in which the pressure, T1, of the adhesive inlet to the foaming station is kept constant, more specifically to the suction stage (32) of the pump (30), acting on a pressure regulator (82) (preferably a proportional valve) that controls the pressure, P1, of the pre-fusion equipment (20) (figures 3a and 3b).

[0059] Likewise, it can also establish a closed loop control in which the pressure, T1, of the adhesive inlet to the foaming station is kept constant, more specifically to the suction stage (32) of the pump (30), acting on a pressure and / or flow control system located at the inlet of the suction stage (32) of the pump (30).

[0060] On the other hand, the pressure gauge (64) can be provided, thus establishing another closed-loop control system in which the pressure, T2, is kept constant in the chamber where the gas is mixed with the molten adhesive. This closed loop acts on the aforementioned regulator (82) in a similar manner to that described for the gauge (62) (Figure 4).

[0061] Figures 3a, 3b, and 4 show two examples of independent implementations of the loop monitored by the meter (62) and the loop monitored by the meter (64). However, as stated in the claims, both loops could be combined into a single loop, sharing the control means (80) and the output line of the latter. The signal sent to control the regulator (82) would then be the result of processing the readings from the two meters (62, 64) appropriately, in conjunction with the processing means, algorithms, and storage or memory included in the control means (80), where applicable. This same principle applies to the various examples illustrated in the remaining figures, which show only some specific applications and not all the possible combinations defined in the appended claims.

[0062] Setpoint values ​​can be entered manually via a user interface or can be reached to the control means (80) via a wired or wireless communication line.

[0063] Figure 5 shows another example of a control application for the supply of foamed adhesive using the aforementioned pressure gauges (62, 64). In this specific case, a control loop is implemented from pressure gauge (64) to a pressure regulator (84) to adjust the pressure, Pg, of the gas supplied from the gas supply means (50). It would also be possible to use only gauge (64), only gauge (62), or both gauges (62, 64) combined in the same control means (80). Similarly, the loop in Figure 5 could be combined in all possible configurations with the loops in Figures 3a, 3b, and 4.

[0064] Another control option contemplated by the present invention is shown in Figure 6, where a piston pump (70) calibrated to the desired pressure is connected to the molten adhesive inlet (30). In this way, a piston is connected to the hose outlet (90) and pumps at a desired constant pressure. Figures 7 and 8 will then explain how the quality of the foam application is regulated by measuring the flow rates of molten adhesive and gas, and consequently modifying the pressures Pg and P1, when necessary. For illustrative purposes, the case of supplying molten adhesive via a tank (10) and under the action of gravity is also considered (Figure 7).

[0065] As just mentioned, in a foam installation with a tank (10) there is no possibility of controlling the inlet pressure, T1, of adhesive to the pump (30), since the product enters by gravity and by the suction made by the pump itself (30) when rotating at a certain speed.

[0066] During laboratory tests, it was found that pressure variations, T1, at the adhesive inlet to the foam-generating pump (30) (caused mainly by changes in the adhesive flow rate due to the application requirements of the foamed adhesive) influence the gas percentage of the mixture. When the flow rate increases, the inlet pressure, T1, decreases, resulting in a higher gas percentage. When the flow rate decreases, the inlet pressure, T1, increases, resulting in a lower gas percentage.

[0067] To maintain a constant percentage of gas in the mixture for any flow rate, it is necessary to control the gas input to the pump (30) and thus a closed-loop control is proposed in which the ratio between the adhesive flow rate and the gas flow rate remains substantially constant.

[0068] In relation to that, in a foam adhesive application installation, an electronic circuit generates a signal for the motor variator that rotates the pump (30) so that it has certain revolutions.

[0069] On the other hand, a flow meter (66) is provided to notify control devices (86) of the gas flow rate, Q1, entering the pump (30). The percentage of gas in the mixture is a value that can be entered via a screen (or other type of interface) or through communications, as explained previously. To maintain this relationship in the application, the system must adjust the gas inlet pressure, Pg, to achieve a gas quantity that corresponds to the pump speed (30) (i.e., the molten adhesive flow rate). With a mass flow meter (66) at the gas inlet to the pump (30), the inlet pressure, Pg, can be corrected in real time using a proportional valve (pressure regulator (84)).

[0070] The other parameter measured is the flow rate of the molten adhesive entering the pump (30), which is achieved by means of the flow meter (68). The closed gas control loop is therefore associated with a closed molten adhesive control loop (with its corresponding flow meters (66, 68)), and the adhesive flow meter (68) measures the amount of adhesive entering the pump to maintain the proportion (gas percentage) corresponding to the established quality.

[0071] Figure 7 shows the case where adhesive is supplied using a tank (10), and Figure 8 shows the case where a pre-fusion unit (20) is used. In the first case, the control means (86) act on the pump speed (rpm) (30) to draw in a smaller or larger quantity of adhesive and on the gas pressure regulator (84). In the case shown in Figure 8, the control means (86) act on the pressure regulator (82) of the pre-fusion unit (20) and, as in the previous case, also on the regulator (84).

[0072] In another embodiment of the monitoring and control system, Figure 9 shows a control implementation using a bypass valve (88) connected to the pump inlet (30) to regulate the adhesive pressure entering the pump (30). In this case, the input parameter for control can be considered to be the adhesive pressure at the pump inlet (30), and the reference is a threshold or limit value that determines when to open the valve (88) and, therefore, divert the flow of molten adhesive back to the pre-melting unit (20).

[0073] Figure 10 shows the monitoring and control of adhesive and gas by means of an adhesive flow regulating pump (71) in the molten adhesive supply means at the pump inlet (30) and a gas flow regulating pump (72) connected in the gas supply line coming from the gas supply means (50), where, by means of the flow control means (86), said adhesive and gas flows are kept regulated and adapted to the rotation speed of the pump (30) which varies according to the demand for foamed adhesive at the outlet of the applicator (40).This regulation can be done analogously by means of the control of the pressure regulator (82) located at a point of the molten adhesive supply means, including the outlet of the pre-melt equipment (30) for molten adhesive regulation and by means of the pressure regulator (84) connected in the gas supply line coming from the gas supply means (50) on which the control means (80) act.

[0074] Finally, in another embodiment of the monitoring and control system, the correct supply of molten adhesive and gas to the pump (30) is achieved by controlling an adhesive flow regulating pump (71) and a gas flow regulating pump (72). The outlet flow rates of these adhesive (71) and gas (72) flow regulating pumps are kept regulated and adapted to the demand for foamed adhesive at any given time by means of flow control means (86). Alternatively, this is achieved by controlling the pressure regulator (82) in the adhesive supply means and, alternatively or in combination with this, by means of a pressure regulator (84) connected to the gas supply line from the gas supply means. Both regulators are adapted to the gas and adhesive pressure requirements by means of control means (80).

Claims

CLAIMS 1. Monitoring and control system for foamed adhesive application installations of the type comprising a suction stage (32) and a mixing and pumping stage (34), of a foam generating pump (30), comprising: - at least a first gauge (62) of the inlet pressure, T1, of the molten adhesive at the inlet of the suction stage (32) and / or - at least a second pressure gauge (64), T2, in the intermediate chamber into which gas is injected between the suction stage (32) and the mixing and pumping stage (34), of the foam generating pump (30) and / or - at least one first flow meter (66) connected to measure the flow rate, Q1, of gas entering the foam generating pump (30) and / or - at least a second flow meter (68) connected to measure the flow rate, Q2, of molten adhesive entering the foam generating pump (30) and / or - at least one pump rotation meter (30) for foam generating; for monitoring the correct application of foamed adhesive.

2. Monitoring and control system according to claim 1, comprising pressure control means (80) arranged to receive information from the first pressure gauge (62) and / or the second pressure gauge (64) to provide, based on these measurements, a control signal from a pressure regulator (82) located at a point in the molten adhesive supply means of the application installation, and / or a control output from a pressure regulator (84) connected in the gas supply line from a gas supply means (50) and / or a control output from a gas flow regulating pump.

3. Monitoring and control system according to claim 1, comprising - at least one first flow meter (66) connected to measure the flow rate, Q1, of gas entering the foam generating pump (30) and / or - at least a second flow meter (68) connected to measure the flow rate, Q2, of molten adhesive entering the foam-generating pump (30), and flow control means (86) arranged to receive information from the first flow meter (66) and / or the second flow meter (68) to provide, based on at least these received inputs, a control output of an adhesive feed pump and / or a control output of a pressure regulator (82) located at a point in the molten adhesive supply means and / or an output control of a pressure regulator (84) connected in the gas supply line from the gas supply means (50) and / or a control outlet of a gas flow regulating pump.

4. Monitoring and control system according to claim 1, comprising at least one speed gauge of the foam-generating pump (30) and flow control means (86) arranged to receive information from the speed gauge of the foam pump (30) to provide, based on this received input, a control output of an adhesive feed pump (71) and a control output of a gas feed pump (72) 5. Monitoring and control system according to claim 1, comprising at least one foam-generating pump rotation meter (30) and control means (80) arranged to receive information from the foam pump rotation meter (30) to provide, based on this received input, a control output of a pressure regulator (82) located at a point of the molten adhesive supply means and a control output of a pressure regulator (84) connected in the gas supply line from the gas supply means (50).

6. Monitoring and control system according to claims 2 to 5, wherein the pressure control means (80) and the flow control means (86) are a single pressure and / or flow control means.

7. Monitoring and control system according to any of the preceding claims, comprising a bypass valve (88) connected at the molten adhesive inlet to the suction stage (32) and actuated by a pressure threshold set such that, when said pressure threshold is exceeded at said molten adhesive inlet, the bypass valve (88) is arranged to at least partially open a recirculation path to the pre-fusing equipment (20) and, optionally, at least partially close the inlet path to the suction stage (32).

8. Monitoring and control system according to any of claims 2 to 7, wherein the molten adhesive supply pressure regulator (82) and the gas supply pressure regulator (84) comprise a proportional valve.

9. Monitoring and control system according to claim 1, comprising at least one piston pump (70) calibrated to a predetermined pressure and connected to the inlet of the molten adhesive to the suction stage (32), so that at the outlet of the hose (90) it will be pumped at a desired pressure.

10. Monitoring and control system for foamed adhesive application installations of the type comprising a suction stage (32) and a mixing and pumping stage (34), of a foam generating pump (30), comprising: - a control output for an adhesive flow regulating pump (71) and a control output for a gas flow regulating pump (72) and / or - a control outlet of a pressure regulator (82) located at a point of the molten adhesive supply means and / or a control outlet of a pressure regulator (84) connected in the gas supply line from the gas supply means (50); wherein the control means (80, 86) keep said outlets regulated and adapted to the demand for foamed adhesive.

11. Monitoring and control system according to any of claims 2 to 10, wherein either the pressure control means (80) and / or the flow control means (86), or the unique pressure and / or flow control means, comprise means for introducing parameters and / or variables, such as setpoint values, in the form of a face-to-face user interface and / or a communications receiver.

12. Monitoring and control system according to any of claims 2 to 11, wherein either the pressure control means (80) and / or the flow control means (86) or the unique pressure and / or flow control means comprise software storage means, processing means and / or one or more PID-type controllers.

13. A monitoring and control system according to any of the preceding claims, comprising one or more alarms arranged and connected to warn of values ​​read by at least one of the first inlet pressure gauge(s) (62), the second mixing chamber pressure gauge(s) (64), the first flow meter(s) (66), and the second flow meter(s) (68), when said values ​​are outside of specified ranges. security established for a set security period.

14. Monitoring and control system according to any of the preceding claims, wherein at least one of the first flowmeter(s) (66) and the second flowmeter(s) (68) is a mass flowmeter.

15. Foam adhesive application machine comprising a system according to any one of the preceding claims.

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