Arrangement for supplying a reactive, self-curing plastics mixture to a mold for a composite part, to which negative pressure can be applied

Abstract

An arrangement (1) for supplying a plastics mixture to a mold (40) to which negative pressure can be applied, comprises: a mixing device (20) for mixing a first and a second liquid synthetic resin component (2A, 2B), the outlet (24) of which is fluidically connected to at least one infusion point (42) of the mold (40) via a supply line (24); a first supply device (10A) for supplying a defined amount of the first synthetic resin component (2A) to the inlet (22) of the mixing device (20), the first supply device (10A) having a first and a second storage container (12A) and associated circulation circuits (13A, 13B) in which the respective synthetic resin components (2A, 2B) can be circulated from the respective storage container (12A, 12B) to a first or second branching point (14A, 14B) and recirculated back from there to the storage containers (12A, 12B); and is characterized in that a pressure-reducing valve (3A, 33A) and a first volume flow measuring unit (4A) are placed in series in the first branching line (16A), and a metering pump (6B) and a second volume flow measuring device (4B) are placed in series in the second branching line (16B). A metering pump (6B) speed is increased or reduced according to the magnitude of the synthetic resin component volume flows measured in the first and second branching lines (16A, 16B), in such a way that the volume flow ratio corresponds to a predetermined desired value.

Description

[0001] Arrangement for feeding a reactive, self-curing plastic mixture to a mold for a composite component that can be subjected to negative pressure

[0002] The invention relates to an arrangement for supplying a reactive, self-curing plastic mixture to a mold for a composite component that can be subjected to negative pressure, according to the preamble of claim 1.

[0003] The production of reinforced plastic components, such as wind turbine rotor blades, which are generally referred to as composite components, is usually carried out using molds that have a stable half-shell into which several layers of different reinforcement and / or support materials, such as glass or carbon fiber fabrics or other prelaminates such as balsa wood parts, are inserted. The top of the mold is then sealed with a flexible film, and the mold is connected to a feed and mixing device for the usually two components of a curable synthetic resin, such as epoxy resin, from which the plastic material is formed after curing, and then subjected to negative pressure.This process involves injecting the liquid, self-curing reactive resin mixture into the fiber material, eliminating the possibility of ambient air and the resulting formation of air bubbles. This results in high-quality and generally high-strength components after the resin has cured. The process is commonly referred to as Resin Transfer Molding (RTM) or Vacuum Assisted Resin Transfer Molding (VA-RTM).

[0004] DE 3522922 C2 discloses a previously described method in which, to avoid gas inclusions in the cured plastic material, the degassed liquid synthetic resin components are conveyed into a mixing unit using dosing devices. The self-curing synthetic resin mixture is drawn from the mixing device to the respective injection points by the negative pressure effect. For elongated components, such as rotor blades, several such injection points can be provided along the mold, which are preferably simultaneously injected with the liquid synthetic resin mixture to even out the wetting of the fiber material.

[0005] The entire system, from the degassing point to the casting point, is hermetically sealed from the environment and is under vacuum, so that the degassed material provided in the storage containers for the two liquid synthetic resin components cannot absorb any gas from the environment.

[0006] One problem with the previously described processes is that when filling the flexible molds using the dosing devices, deformation of the flexible part of the mold (cover film) can sometimes occur if too much of the liquid reactive synthetic resin mixture is temporarily fed into the mold, causing the pressure inside the mold to exceed atmospheric pressure. This leads to the flexible film resting on the upper side of the fiber material due to the negative pressure, lifting off the fiber material. As a result, the fiber material is no longer held in place by the film and can shift within the mold. Furthermore, the planned flow front path can be disrupted. This usually results in the finished cast product deviating from the originally desired shape or exhibiting other defects, thus rendering it unusable.

[0007] To prevent the flexible film that forms the top side of the finished component from lifting off due to a brief excess supply of liquid reaction resin, EP 2 656 991 A2 discloses storing the supplied liquid reaction resin in flexible plastic bags before introducing it into the injection points of the mold, so that from this point onwards the material is always at maximum atmospheric pressure. The fill level of the bag is monitored and controlled by a load cell. The geodetic arrangement of the load cell relative to the mold can rudimentarily compensate for the suboptimal pressure loss when the resin mixture flows to the mold. This is not optimal because the flow rate and thus the pressure loss decreases towards zero as the mold fill level increases.Here, the supply of liquid reactive resin to a bag is interrupted by closing a corresponding valve when the weight reaches a predetermined upper maximum value, and the supply is activated by opening the valve when the weight falls below a minimum value. Although the device reliably prevents the film from lifting, it has the disadvantage that the control is comparatively slow and the bags, each with its associated mixing unit, can only be filled sequentially and not simultaneously by a central dosing device. This disadvantageously increases the time required to completely fill the mold.A further difficulty is that the bags do not have a FIFO (First In First Out) design, so that reactive resin that has been in the reaction process for some time may influence the overall process, which can lead to a loss of quality / strength of the finished composite components.

[0008] Accordingly, it is an object of the present invention to provide an arrangement with which components made of fiber-reinforced plastic can be manufactured with high quality and in a shorter time.

[0009] This object is achieved according to the invention by an arrangement having the features of claim 1.

[0010] Further features of the invention are described in the subclaims.

[0011] The invention is described below with reference to preferred embodiments and the accompanying drawings. In the drawings:

[0012] Fig. 1 is a schematic representation of a first embodiment of the arrangement according to the invention, in which the pressure reducing valve for the first synthetic resin component is a manually adjustable, mechanically operated pressure reducing valve,

[0013] Fig. 2 is a schematic representation of a second embodiment of the arrangement according to the invention, in which the pressure reducing valve for the first synthetic resin component is an electronically proportionally controlled pressure reducing valve, and Fig. 3 is a schematic representation of a modularly constructed embodiment of the arrangement according to the invention, in which a central supply module supplies a total of three dosing and mixing modules for the two synthetic resin components via collecting lines.

[0014] As shown in Fig. 1, an arrangement 1 according to the invention for producing a composite component 50 comprises a mold 40 which can be subjected to negative pressure from a vacuum source 46 and which is intended to receive composite material, which can be covered and fixed in the mold by a flexible film 44, as is known from the previously described VA-RTM process. The arrangement 1 further comprises a mixing device 20 for mixing a first and second liquid synthetic resin component 2A, 2B, e.g. epoxy resin, to form a self-curing reactive synthetic resin mixture which, after curing, forms the workpiece or component 50 together with the composite material. The outlet 24 of the mixing device 20, which can be a known static or dynamic mixing device for such multi-component synthetic resins, is fluidly connected to at least one infusion point 42 of the mold 40 via a feed line 24.

[0015] To provide the first synthetic resin component 2A, the arrangement 1 comprises a first supply device 10A, which supplies a predetermined amount of the first liquid synthetic resin component 2A to the inlet 22 of the mixing device 20. For this purpose, the first supply device 10A has a first storage container 12A and a first circulation line HA for the first synthetic resin component 2A, in which the latter is pumped by a preferably speed-controlled feed pump 8A from the first storage container 12A to a first branch point 14A of a first circulation circuit 13A and from there back to the first storage container 26A.

[0016] As shown in Figs. 1 and 2, the arrangement 1 further comprises a second supply device 10B, which conveys a predetermined amount of the second liquid synthetic resin component 2B to the inlet 22 of the mixing device 20, depending on the required mixing ratio of the two synthetic resin components 2A, 2B. For this purpose, the second supply device 10B has a second storage container 12A and a second circulation line HB for the second synthetic resin component 2B, in which the latter is circulated by a preferably speed-controlled feed pump 8B from the second storage container 12B to a second branch point 14B of a second circulation circuit 13B and from there back to the second storage container 12B.

[0017] The two circulation circuits 13A and 13B serve to provide the first synthetic resin component 2A and the second synthetic resin component 2B with a substantially constant pre-pressure, which considerably simplifies the dosing of the respective component during supply to the mixing device 20 and thereby reduces the risk of dosing errors resulting from fluctuating supply pressures.

[0018] In order to supply the first and second synthetic resin components 2A, 2B, which have been degassed in a known manner at a constant pre-pressure and by applying a corresponding negative pressure to the storage containers 10A, 10B, to the mixing device 20, a first branching point 14A is arranged in the first circulation circuit 13A, which is fluidly connected to one inlet 22 of the mixing device 20 via a first branch line 16A for the first synthetic resin component 2A. Likewise, a second branching point 14B is arranged in the second circulation line 11B, e.g. a T-piece, through which the second circulation circuit 13B can also be connected to the inlet 22 of the mixing device 20 for this component via a corresponding second branch line 16B for the second synthetic resin component 2B.

[0019] The arrangement 1 according to the invention is characterized in that in the first branch line 16A a pressure reducing valve 3A, 33A and a first volume or mass flow measuring device 4A are arranged one after the other in series, and in the second branch line 16B a metering pump 6B and a second volume or mass flow measuring device 4B are arranged one after the other in series, which are connected to an electronic control and regulation device 30, which increases or decreases the speed of the metering pump 7 depending on the size of the volume or mass flow of the first synthetic resin component 2A in the first branch line 16A detected by the first volume or mass flow measuring device 4A and the size of the volume or mass flow of the second synthetic resin component 2B in the second branch line 16B detected by the second volume flow measuring device 4B in such a way that the ratio of the volume flows of the two synthetic resin components 2A,2B corresponds to a given target value.,

[0020] The main advantage of the solution according to the invention is that the dosing of the A component is not controlled by preset dosing programs or sensors, such as volume or mass flow measuring devices. Likewise, no actuators such as volumetric pumps, e.g., gear or eccentric screw pumps, are required. A further advantage of the arrangement according to the invention is that it opens up the possibility of storing empirical values ​​for the settings of the valves and pumps in conjunction with the associated pressure measurements and measured values ​​for the volume or mass flows in an electronic memory, so that the electronic control and regulation device can read the stored values ​​from the memory for subsequent infusions and use them to achieve the specified target values ​​in a shorter time.In simple terms, this improves the ability to learn and adapt in a beneficial way.

[0021] Based on the set infusion pressure at the mold, which is provided, for example, by a corresponding vacuum source 46, the first resin component 2A automatically adjusts its flow rate. This is highest at the beginning of an infusion process and decreases more and more towards the end of the process, the more resin is in the mold 40. The pressure reducing valve, which according to a first embodiment is a purely mechanically operated valve 3A that is manually set to a fixed pressure value in the first branch line 16A, adapted to the requirements of the overall system, automatically changes and adjusts the pressure and flow conditions in the first branch line 16A such that the pressure reducing valve opens wider the lower the pressure. This results in the flow rate of the first resin component 2A increasing accordingly and the mold 40 being filled more quickly.

[0022] If, however, the flow rate is too high at the end of an infusion process when the mold 40 is almost completely filled, the pressure at the inlet 42 of the mold 40 also increases, and the pressure reducing valve 3A closes more and more, thereby automatically reducing the flow rate in the first branch line 16A for the first resin component 2A. The automatic adjustment of the pressure to the manually set fixed value in the first branch line 16A downstream of the valve 3A, which is set to this or a slightly higher level depending on the ambient pressure in order to compensate for the pressure loss between the mixing device 20 and the infusion site 42, takes place in the manner known for such valves, independently of the volume flow of the first synthetic resin component in the first branch line 16A, e.g. via a spring-loaded membrane installed in the valve.

[0023] When, towards the end of the infusion process, the mold 40, or the composite material contained therein, in simple terms, can no longer absorb any resin and the flow in the first branch line 16 detected by the first volume flow measuring device 4A approaches zero, the dosing process is stopped by the electronic control and regulation device 30, so that a lifting of the film 44 is prevented.

[0024] The use of the pressure reducing valve 3A in the first branch line 16A ensures that the pressure on the outlet side of the valve 3A is maintained at a specific level, resulting in a flow rate adapted to consumption. Since the pressure reducing valve 3A is fixed in the case of the first embodiment, the valve is adjusted to achieve a compromise between a) rapid infusion (inlet pressure at the mold = ambient pressure, e.g., 1.2 bar absolute pressure at the valve), but early intermittent on / off dosing due to the increasing pressure at the mold inlet; and b) less on / off dosing at the end of the process, but with a lower set pressure (e.g., 1 bar) on the outlet side of the valve 3A in the first branch line 16A, and a correspondingly somewhat longer infusion time.

[0025] The volume or mass flow of the second synthetic resin component 2B in the second branch line 16B, which must be mixed with the first synthetic resin component 2A in a ratio to be precisely maintained in the mixing device 20, for example in the case of epoxy resin in a ratio of 1:1 to 1:30, is, however, regulated by the metering pump 6B arranged in the second branch line 2B, depending on the respective actual volume or mass flow in the first branch line 16A, which is detected by the first volume flow measuring device 4A.

[0026] The metering pump 6B can be any type of continuous metering pump that ensures a material flow controllable by the electronic control and regulation device. In order to precisely regulate the volumetric or mass flow of the second synthetic resin component 2B in the second branch line 16B through the metering pump 6B to the desired mixing ratio, this flow is continuously measured by the second volumetric flow measuring device 4B, and the metering pump 6B is controlled by the control and regulation device 30 connected to it so that the desired ratio of the volumetric flows of the first and second synthetic resin components 2A, 2B is established at the two inputs at the inlet 22 of the mixing device 20.For this purpose, the measured values ​​recorded by the control and regulation device 30 during previous infusions, which are preferably stored in a memory, are read out and compared with the currently recorded measured values, so that a program routine running in the electronic control and regulation device 30 can determine the optimal setting values ​​for the dosing pump 6B based on the comparison in the shortest possible time, which lead to the set mixing ratio.

[0027] In order to ensure that the pressure in the mold 40 does not rise above the ambient pressure and lead to a lifting of the film 44, in the preferred embodiment of the invention, at least one infusion point 42, but preferably all infusion points 42, which, as shown in Figs. 1 and 2, are arranged at respective intervals along the length of the component 50, a pressure sensor PMI to PM Xassigned to it, with which the pressure of the reactive liquid synthetic resin mixture introduced into the mold 40 is detected relative to the ambient pressure at the infusion site 42. If the electronic control and regulation device 30, which monitors the pressure values ​​of the pressure sensors PMI to PMX during an infusion process, detects an increase in pressure above a predetermined maximum infusion pressure of the mold 40, which is slightly, e.g. 0.05 bar, below the ambient pressure, it closes an on / off valve 17A, 17B arranged in the first branch line 16A and the second branch line 16B, which is shown in Figs. 1 and 2. This leads to the pressure in the mold 40 immediately dropping again due to the negative pressure present at the outlet side of the mold 40, which is provided by the negative pressure source 46, so that lifting of the film 44 is reliably prevented.

[0028] As already mentioned above, in the case of elongated components, such as rotor blades for wind turbines, which can have a length of up to 80 m or even more, two or more infusion points 42 are preferably arranged on the mold 40. These infusion points are connected to the outlet 24 of the mixing device 20 via supply lines, via which the ready-mixed reactive synthetic resin mixture is introduced into the mold 40. According to the invention, it can be provided that each infusion point 42 is assigned an individual pressure sensor PMI to PMX, and the electronic control and regulating device 30 is configured to actuate the on / off valve 17A, 17B on the basis of the pressure sensor PMI to PMX which transmits the largest current pressure measurement value.

[0029] According to a further embodiment of the invention shown in Fig. 2, the pressure reducing valve is an electric proportional pressure reducing valve 33A actuated by the electronic control device 30, which controls the pressure in the first branch line 16A downstream of the valve 33A to a constant value, in particular to a value of 0 to 1.2 bar relative to the ambient pressure and / or the internal mold pressure, regardless of the volume or mass flow in the first branch line 16A. The use of an automatically controlled pressure reducing valve offers the advantage, compared to the previously described embodiment with a fixed pressure reducing valve 3A, that the infusion time and the mold occupancy time can be minimized.

[0030] In this embodiment, the mold inlet pressure (and thus the dosing pressure) is actively adjusted to a level just below ambient pressure by appropriately controlling the electric proportional pressure reducing valve 33A by the electronic control and regulation device 30, depending on the signals from the pressure sensors PMI to PMX at the mold inlet, in order to prevent the film 44 from lifting off and thus a defective workpiece 50. The described proportional electrically controlled pressure reducing valves are known from the prior art and are used to adjust the infusion pressure during the infusion process, thereby increasing the infusion rate throughout the entire process and optimizing the infusion time accordingly.The self-regulating basic function of the valve 33 A, with a value for the infusion pressure specified by the electronic control and regulation device 30, leads to a flow rate adapted to the tool consumption at any time during the process.

[0031] According to a further idea underlying the invention, it can further be provided that the electronic control and regulation device 30 alternately opens and closes the electrically actuated on / off valve 17A, 17B in the first and second branch line 16A, 16B for a short period of time, for example a few seconds, towards the end of an infusion process in order to provide a minimum volume flow in the first branch line 16A and / or the second branch line 16B, which can still be detected by the first and / or second volume flow measuring devices 4aA, 4B.This provides the advantage that the entire infusion process can still be controlled towards the end, even at very low flow rates for the first and / or second synthetic resin components 2A, 2B, since the flow rate can be measured by the volume measuring devices 4A, 4B for a certain period of time even if the average volume or mass flow, regardless of the switching state of the on / off valve 17A, 17B, is below the minimum value that can just be measured by the volume flow measuring devices 4A, 4B. In other words, the infusion process can still be controlled towards the end by this measure if the flow is lower than the minimum detectable volume or mass flow.

[0032] In order to provide a constant pre-pressure at the branch points 14A, 14B and to improve the dosing accuracy at different volume flows in the branch lines 16A and 16B, a speed-controlled feed pump 8A, 8B and an overpressure or pressure-maintaining valve 9A, 9B arranged downstream of this in the flow direction of the first and / or second synthetic resin component 2A, 2B are preferably arranged in the first circulation circuit 13A and / or in the second circulation circuit 13B, which can be controlled by the electronic control and regulation device 30 in such a way that the speed of the feed pump 8A, 8B in the first and / or second circulation circuit 13A, 13B can be adjusted to different speed values ​​depending on the current volume flow for the amount of reactive synthetic resin mixture supplied to the mold 40.Thus, the speed control of the second feed pump 14B can be considerably simplified if its speed is reduced in several stages, e.g., in 10% increments, as the volume or mass flow decreases toward the end of an infusion process. This also ensures a constant pressure at the inlet of the dosing pump 6B, reliably preventing a sudden overpressure above the maximum permissible infusion pressure at the inlet 42 of the mold 44.

[0033] As further discovered by the applicant, by using an overpressure or pressure-maintaining valve 9 A in the first circulation circuit 13 A, a constant pressure can also be maintained at the inlet of the pressure reducing valve 3 A or 33 A, which leads to a reduction in the fluctuations in the volume flow of the first component 2 A in the branch line 16 A, since the outlet pressure at the first pressure reducing valve 3 A, 33 A also depends on the inlet pressure.

[0034] In order to maintain the target mixing ratio of the first and second synthetic resin components 2A, 2B required for optimal strength of the cured synthetic resin mixture as closely as possible throughout the entire infusion process, a further idea underlying the invention can provide that the electronic control and regulation device 30 is designed to integrate the volume or mass flow measured values ​​recorded by the first and second volume flow measuring devices 4A, 4B during a predetermined time interval of, for example, 1 minute, in each case to a first volume value required in the first branch line 16A for the first synthetic resin component 2A and a second volume value conveyed in the second branch line 16B for the second synthetic resin component 2B.After the time interval has elapsed, the electronic control and regulation device 30 determines the ratio of the two synthetic resin components and calculates a new target delivery rate for the dosing pump 6B, for example by forming the difference between the determined ratio of the volume values ​​and the ideal target mixing ratio. The volume or mass flow of this new target flow rate is then increased or decreased accordingly by the electronic control and regulation device 30. This can be done, for example, by increasing or decreasing the pump speed of the dosing pump 6B. In practice, the integration of the volume flow measured values ​​recorded by the first and second volume flow measuring devices 4A, 4B during the time interval is carried out, for example, by digitally summing incremental measured values ​​from the first and second volume flow measuring devices 4A, 4B in the same time interval.

[0035] According to a further idea underlying the invention, the speed-controlled feed pumps 8A, 8B arranged in the first circulation circuit 11A and in the second circulation circuit 13B and the storage containers 12A, 12B of the first and / or second synthetic resin components 2A, 2B, which are in flow connection with these, together with the associated circulation lines 11A, 11B form a supply module 100.

[0036] At the same time, the first overpressure or pressure holding valve 9A and the first pressure reducing valve 3A, 33A connected to it via the first branch point 14A and the first branch line 16A and the first volume flow measuring device 4A for the first component 2A arranged downstream of it in series in terms of flow, together with the second overpressure or pressure holding valve 9B and the second branch point 14B connected to it via the second branch line 16B as well as the metering pump 6B and second volume flow measuring device 4B for the second component 2B connected one after the other in series to the second branch line 16B, including the mixing device 20, form a mixing and metering module 200 which, as indicated in Fig. 3, can be controlled by the electronic control and regulating device 30.

[0037] In Figures 1-3, the associated electrical control lines between the respective components and the electronic control and regulation device, which is advantageously implemented by a known and appropriately programmed microprocessor circuit, are not shown or only partially shown for the sake of clarity.

[0038] As can also be seen from the illustration in Figure 3, for large and elongated components 50 with a plurality of infusion points 42, two or more dosing and mixing modules 200 are preferably used. These are connected to the supply module 100 via a first collective supply line 210A and a first collective return line 211A for the first component 2A, as well as via a second collective supply line 210B and a second collective return line 211B for the second component 2B. This modular design, in which the mixing and dosing modules 200 are preferably connected to the collective supply and return lines 210A, 211A, 210B, and 211B via quick-release couplings (not shown in detail), opens up the possibility of reducing the overall CAPEX and OPEX and reducing the space required in the workshop.A further advantage of the modular structure of the arrangement 1 is that it allows the overall electrical energy requirement of the arrangement to be reduced, since only as many dosing and mixing modules 200 are used as are required to fill the mold 50. Finally, a particular advantage of this embodiment is that the supply modules 100 can be designed so that they not only work sequentially, as is known from current bag solutions, but when multiple dosing and mixing modules 200 are used, there is the possibility of supplying one or even multiple molds 50 simultaneously, which significantly simplifies logistics and further reduces the filling times of the respective mold or molds 50.

[0039] In addition, the energy supply for providing and metering the first synthetic resin component 2A – which, given the usual mixing ratios of, for example, 2:60 and the generally higher viscosity of the second component, requires disproportionately more energy – is not provided at the metering and mixing module 200 itself, but rather in a single material feed system that supplies all metering and mixing modules. This reduces both the electrical wiring effort and the space required for the metering and mixing modules 200.

[0040] Although a total of three dosing and mixing modules 200 are shown in Fig. 3, which are supplied by a supply module 100 via the collecting lines 210A, 210B as well as 211A and 211B, it is also possible to supply only one such dosing and mixing module 200 by a supply module 100, or to provide two or more supply modules 100, each with two or more dosing and mixing modules 200, on a mold 40 in order to be able to supply a correspondingly large number of infusion points 42 with the reactive synthetic resin mixture in the case of very large and long molds 50. Furthermore, it is possible for a supply module 100 according to an embodiment not shown in the drawings to supply not only one mold 40 with the respective first and second synthetic resin components 2A, 2B, but rather several such molds 40 simultaneously, which in this case each have their own dosing and mixing module 200 for the two resin components 2A, 2B.

[0041] List of reference symbols

[0042] 1 Arrangement according to the invention

[0043] 2A first liquid resin component

[0044] 2B second resin component

[0045] 3A Pressure reducing valve in the first branch line

[0046] 4A first dosing pump

[0047] 4B second dosing pump

[0048] Dosing pump in second branch line

[0049] 8A speed-controlled feed pump in the first circulation circuit

[0050] 8B speed-controlled feed pump in second circulation circuit

[0051] 9A Adjustable pressure reducing valve in the first circulation circuit

[0052] 9B Adjustable pressure reducing valve in second circulation circuit

[0053] 10A first feed device

[0054] HA first circulation line

[0055] 12A first reservoir

[0056] 13A first circulation circuit

[0057] 14A first junction

[0058] 16A first branch line

[0059] 10B second feed device

[0060] 1 IB second circulation line

[0061] 12B second storage container

[0062] 13B second circulation circuit

[0063] 14B second junction

[0064] 16B second branch line

[0065] 20 Mixing device

[0066] 22 Inlet of the mixing device

[0067] 24 Outlet of the mixing device

[0068] 30 electronic control and regulation device

[0069] 33A electronically operated proportional pressure reducing valve

[0070] 40 Shape

[0071] 42 Infusion site of form 44 flexible film

[0072] 46 Vacuum source

[0073] 50 components

[0074] 100 supply module

[0075] 200 Dosing and mixing module

[0076] 210A first collective supply line for first component

[0077] 211 A first sainmel return line for first component

[0078] 21 OB first collective inlet line for second component

[0079] 211 B second sainmel return line for second component

[0080] PMI - PMX pressure sensors at infusion sites of the form

Claims

Claims 1. An arrangement (1) for supplying a reactive, self-curing plastic mixture to a mold (40) for a composite component that can be subjected to negative pressure and can be covered and fixed in the mold (40) by a flexible film (44), comprising a mixing device (20) for mixing a first and second liquid synthetic resin component (2A, 2B) to form the self-curing, reactive synthetic resin mixture, the outlet (24) of which is fluidly connected to at least one infusion point (42) of the mold (40) via a feed line (24), a first supply device (10A) for providing and supplying a predetermined amount of the first liquid synthetic resin component (2A) to the inlet (22) of the mixing device (20), the first supply device (10A) comprising a first storage container (12A) and a first circulation circuit (13A) for the first synthetic resin component (2A),in which it can be circulated from the first storage container (12A) to a first branching point (14A) and from there back to the first storage container (12A) by generating a predetermined pre-pressure, a second supply device (10B) for providing and supplying a predetermined amount of the second liquid synthetic resin component (2B) to the inlet (22) of the mixing device (20), wherein the second supply device (10B) comprises a second storage container (12A) and a second circulation circuit (13B) for the second synthetic resin component (2B), in which it can be circulated from the first storage container (12A) to a second branching point (14B) and from there back to the first storage container (12B) by generating a predetermined pre-pressure,wherein the first branching point (14A) is fluidly connectable to the inlet (22) of the mixing device (20) via a first branch line (16A) for the first synthetic resin component (2A) and the second branching point (14B) is fluidly connectable to the inlet (22) of the mixing device (20) via a second branch line (16B) for the second synthetic resin component (2B), characterized in that in the first branch line (16A) a pressure reducing valve (3A, 33A) and a first volume flow measuring device (4A) are arranged one after the other in series in terms of flow, in that in the second branch line (16B) a metering pump (6B) and a second volume flow measuring device (4B) are arranged one after the other in series in terms of flow, and in that the arrangement (1) comprises an electronic control and regulating device (30) which increases or decreases the speed of the metering pump (6B) as a function of the size of the volume or mass flow of the first synthetic resin component (2A) in the first branch line (16A) detected by the first volume flow measuring device (4A) and the size of the volume or mass flow of the second synthetic resin component (2B) in the second branch line (16B) detected by the second volume flow measuring device (4B) in such a way that the ratio of the volume flows corresponds to a predetermined target value.

2. Arrangement according to claim 1, characterized in that a pressure sensor (PMI to PMX) is assigned to the at least one infusion point (42) of the mold (40), with which pressure sensor the pressure of the reactive liquid synthetic resin mixture introduced into the mold (40) relative to the ambient pressure at the infusion point (42) can be detected, that an on / off valve (17A, 17B) actuatable by the electronic control and regulating device (30) is arranged in the first branch line (16A) and the second branch line (16B), and that the electronic control and regulating device (30) is designed to close the on / off valve (17A, 17B) when the pressure detected by the pressure sensor (PMI to PMX) exceeds a predetermined maximum infusion pressure of the mold (40).

3. Arrangement according to claim 2, characterized in that the mold (40) has two or more infusion points (42) connected to the outlet (24) of the mixing device (20) via supply lines, each of which has a pressure sensor (PMI to PMX), and that the electronic control and regulating device (30) is designed to actuate the on / off valve (17A, 17B) on the basis of the pressure sensor (PMI to PMX) which transmits the largest pressure measurement value.

4. Arrangement according to claim 2, characterized in that the pressure reducing valve is a mechanically operated pressure reducing valve (3A) which can be manually adjusted to a desired output pressure and which regulates the pressure in the first branch line (16A) downstream of the valve (3A) to a manually set fixed value independently of the volume or mass flow in the first branch line (16A).

5. Arrangement according to one of claims 1 to 3, characterized in that the pressure reducing valve is an electric proportional pressure reducing valve (33A) which can be actuated by the electronic control unit (30) and which sets the pressure in the first branch line (16A) downstream of the valve (33A) to a constant value, in particular to a value of 0 to 1.2 bar, independently of the volume or mass flow in the first branch line (16A).

6. Arrangement according to claim 2, characterized in that the electronic control and regulation device (30) is designed to open and close the on / off valve (17A, 17B) in the first and second branch line (16A, 16B) intermittently for a short period of time of preferably less than 1 second towards the end of an infusion process in order to provide a minimum volume or mass flow in the first branch line (16A) and / or the second branch line (16B) that can be detected by the first and / or second volume measuring devices (4A, 4B).

7. Arrangement according to one of the preceding claims, characterized in that the electronic control and regulation device (30) is designed to integrate the volume flow measured values ​​recorded by the first and second volume flow measuring devices (4A, 4B) during a predetermined time interval of, for example, 1 minute, in each case to a first volume value required in the first branch line (16A) for the first synthetic resin component (2A) and a second volume value delivered in the second branch line (16B) for the second synthetic resin component (2B), and to increase or decrease the delivery rate of the metering pump (6B) accordingly if the ratio of the first volume value and the second volume value deviates from the predetermined mixing ratio for the first and second synthetic resin components (2A, 2B).

8. Arrangement according to one of the preceding claims, characterized in that in the first circulation circuit (13A) and / or in the second circulation circuit (13B) a speed-controlled feed pump (8A, 8B) and a pressure relief or pressure-maintaining valve (9A, 9B) arranged downstream of the latter in the flow direction of the first and / or second synthetic resin component (2A, 2B) are arranged, which reduces the pre-pressure upstream of the pressure-reducing valve (3A, 33A) and the metering pump (6B) to a substantially constant value.

9. Arrangement according to claim 8, characterized in that the storage containers (12A, 12B) arranged in the first circulation circuit (13A) and / or in the second circulation circuit (13B) together with the speed-controlled feed pumps (8A, 8B) and the circulation lines (11A, 11B) form a supply module (100), and that the overpressure or pressure-maintaining valves (9A, 9B) arranged downstream of these in the flow direction of the first and / or second synthetic resin component (2A, 2B) together with the pressure reducing valve (3A, 33A) and the first volume flow measuring device (4A) for the first component (2A) arranged downstream of it in terms of flow, as well as the metering pump (6B) and second Volume flow measuring device (4B) for the second component (2B) including the mixing device (20) to which the first and second synthetic resin components (2A, 2B) are fed, form a dosing and mixing module (200) which can be controlled by the electronic control and regulation device (30).

10. Arrangement according to claim 9, characterized in that two or more mixing and dosing modules (200) are provided, which are each connected in parallel to a supply module (100) via an associated first collective feed line (210A) and collective return line (211A) for the first synthetic resin component (2A) and an associated second collective feed line (211B) and collective return line (211B) for the second synthetic resin component (2B).

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