MATERIAL MIXTURE SYSTEM WITH BUFFER STORE

Abstract

A system for mixing two or a plurality of material components, for example for applying onto electronic circuit boards, having a pressure-regulated buffer store downstream of the mixing unit so that a mixing material is pressurized regardless of the quantity contained in the buffer store, even if the inflow and outflow in the buffer store change dynamically.

Claims

1. Material mixing system which is configured for use in a production line for electronic assemblies for providing a viscous material stream, comprising: a mixing unit adapted to mix two or more inlet material streams to produce a mixing material, and a mixing material buffer store unit having an inlet for receiving the mixing material from the mixing unit and an outlet for dispensing the mixing material and adapted to pressurize the mixing material in a controlled manner, and a control device which is adapted at least to control the pressurization of the mixing material in order to maintain at least the pressure in the buffer store which acts on the mixing material, on the basis of an adjustable target value, independently of the quantity of the mixing material in the buffer store, independently of a possible input volume flow and independently of an output volume flow.

2. Material mixing system according to claim 2, wherein an effective storage volume of the mixing material buffer store is dynamically adjustable.

3. Material mixing system according to claim 1, wherein the mixing material buffer store has a displaceable piston.

4. Material mixing system according to claim 3, wherein the displaceable piston communicates with a controllable fluid pressure source on a side facing away from the mixing material.

5. Material mixing system according to claim 3, wherein the displaceable piston is connected to a controllable electrical or electromagnetic drive device.

6. Material mixing system according to claim 1, wherein a fluid substantially inert for the mixing material can be controllably introduced into the mixing material buffer store for pressurizing the mixing material.

7. Material mixing system according to claim 1, further comprising volume determination means adapted to determine an actual volume of mixing material in the mixing material buffer store.

8. Material mixing system according to claim 3, which is further configured to determine a position of the displaceable piston in the mixing material buffer store.

9. Material mixing system according to claim 8, wherein the displaceable piston has an indicator element which enables a position of the displaceable piston to be determined contact-less.

10. Material mixing system according to claim 1, further comprising control means adapted at least to control the pressurization of the mixing material.

11. An electronic assembly production line material mixing system for providing a viscous material stream comprising: a source of starting materials used in electronic assembly production; a plurality of metering units coupled to said source of starting materials; a mixing unit having a mixing unit inlet coupled to said plurality of mixing units and a mixing unit outlet; a buffer store coupled to the mixing unit outlet, said buffer store having a buffer store outlet; a material output component coupled to the buffer store outlet, whereby said material output component is capable of providing the viscous material stream to a component of an electronic assembly; a pressure control device coupled to said buffer store configured to provide a controlled pressure to said buffer store; a control unit coupled to said plurality of metering units, said mixing unit, and said pressure control device, said control unit configured to provide a controlled pressurization to said buffer store so as to maintain a defined volume flow and output pressure of the viscous material stream from said material output component independent of a quantity of material in said buffer store, a material flow from the mixing unit outlet of said mixing unit into said buffer store, and a material flow from the buffer store outlet of said buffer store to said material output component, whereby a high dynamic range of the viscous material stream is capable of being maintained.

Description

[0032] Further advantageous embodiment are described in more detail with reference to the accompanying drawings, in which

[0033] FIG. 1 schematically shows a material mixing system, in which a controlled mixing material buffer store is provided,

[0034] FIG. 2 shows a schematic view of a material mixing system in which the pressure control in the buffer store is implemented by pneumatic control,

[0035] FIG. 3A shows a schematic sectional view of the buffer store according to an illustrative embodiment, in which a displaceable piston is provided for pressurizing the mixing material,

[0036] FIG. 3B shows a perspective view of a piston that can be used in embodiments with displaceable pistons, for example the embodiment shown in FIG. 3A,

[0037] FIGS. 4A and 4B schematically show sectional views of the buffer store, whereby a displaceable piston is provided, which is directly mechanically coupled to an electrical or electromagnetic drive device, and

[0038] FIGS. 5A and 5B show schematic sectional views of the buffer store, in which the pressurization of the mixing material in the buffer store is effected by the action of a pressurizing fluid, such as a gas, a suitable liquid, and the like.

[0039] With reference to the accompanying drawings, further embodiments are now described and/or the previously described embodiments are explained in more detail.

[0040] FIG. 1 schematically shows a system 190 for the production and application of a mixing material, which is produced from two or a plurality of components by mixing. The system 190 has a corresponding material source 191 for this purpose, in which corresponding starting materials are typically provided in the form of fluids, whereby the individual components have certain properties that enable reliable transport, storage and processing. Typically, the starting materials are fluids with a manageable viscosity. By mixing two or a plurality of components, the desired material properties are obtained and, as already mentioned at the beginning, a final product is obtained after a certain curing time, which meets the application-specific requirements.

[0041] In some of the embodiments shown here, reference is made to a mixing material that is produced from two starting components by mixing, since such 2-component materials are frequently used in industry, for example as filling materials, protective coating materials, and the like. However, it should be noted that the concept according to the invention is also applicable to mixing materials that are mixed together from three or a plurality of components, if this is considered suitable for certain applications.

[0042] The material source 191 thus has corresponding containers or other material sources which can provide starting materials with the desired quantity and flow rate by suitable means, for example by pumps, for instance in the form of diaphragm pumps, and the like. The material source 191 typically also has one or a plurality of materials that can be used to flush the system 190, and includes suitable solvents, and the like. It also includes, for example, fluids in the form of gas, such as air, nitrogen, and the like, which can also be provided by suitable means, pressure vessels, and the like. The system 190 also includes a material mixing system 100, which is configured, in accordance with the invention, to achieve significant efficiency improvements over conventional material mixing systems, with the material mixing system 100, in particular, enabling an increased speed of response to dynamically varying acceptance requirements, as described in detail above and in the following.

[0043] The system 190 also has a material output component 192, which receives a mixing material 193 from material mixing system 100 and outputs mixing material 193 in a suitable manner. For example, the mixing material output component 192 has one or a plurality of types of nozzles for spraying the mixing material 193 onto an object, with corresponding nozzles typically controllable so that the flow rate depends on the current operating state of the corresponding nozzle. In an advantageous embodiment, the material mixing system 100 according to the invention is used within the framework of the system 190 to apply mixing materials to carrier plates of electronic components so that corresponding components are given additional functions after mounting on the carrier plate, such as protection against environmental influences, and the like.

[0044] In other variants, the material system 190 with the mixing material system 100 according to the invention can be used for the production and application of mixing materials in which the mixing material can be processed before a certain period of time of the chemical reaction has elapsed, although with typically increased viscosity compared to the starting materials, and corresponding volume flows of the mixing material 193 are in the range of a few cubic centimeters per minute up to several hundred cubic centimeters per minute. The mixing material system 100 is configured in such a way that a quick response to rapid changes in the decrease quantity in particular is possible. If, for example, the mixing material 193 in the output component 192 has to be provided in a correspondingly time-varying quantity due to flow rates that fluctuate rapidly over time, for example if the spray width of a curtain nozzle is changed dynamically during an application process, the system 100 can then react with a correspondingly high response speed and provide a variable volume flow. In this way, a continuous material quality of the applied mixing material 193 is guaranteed.

[0045] As already explained at the beginning, the dynamics of a system for mixing and applying a mixing material is typically given by the mechanical properties of corresponding metering units and the configuration of a mixer, since, for example, the metering units cannot change their throughput at any speed and the mixer also typically has a correspondingly low response speed due to its configuration. In the system 190, for example, well known metering units 194A, 194B, 194C, . . . are provided, which are configured as volumetric units, so that, for example, a corresponding metering screw is provided, which, due to its configuration, conveys a precisely defined quantity of starting material from its inlet to its outlet, provided that it is guaranteed that sufficient starting material from material source 191 is always available at the respective metering units. This means that in well-proven, established volumetric metering units, the quantity per unit of time and thus the volume flow can be precisely adjusted by the speed of the corresponding screw conveyor, for example by controlling the speed of the screw conveyor. In case of rapid changes of the required volume flow, however, due to the limitations of the drive means as well as the mechanical conditions, only a limited dynamic tracking of the required volume flow can be performed.

[0046] It should be noted that in the example shown, the metering units 194A, 194B each provide the starting materials for the mixing material 193 in the desired quantity ratio, while the metering unit 194C, for example, can be provided for the metered supply of cleaning material, and the like, if precise metering is required in this respect. In other examples, as explained above, three or a plurality of components may be required for the resulting mixing material 193.

[0047] The metered material quantities or volume flows provided by the metering units 194A, 194B, 194C, which are schematically designated here as 195A, 195B, 195C, are fed to a mixing unit 110 of the material mixing system 100, which is schematically represented here in such a way that it can homogeneously mix at least two of the volume flows 159A, 159B. It should be noted that the mixing unit 110 can also be a combination of a plurality of mixing units, if, for example, a plurality of starting materials are to be mixed in several stages, i.e. in several steps. The mixing unit 110 can be a well-known static/dynamic mixing unit in which a mixing helix is statically provided, if, for example, the material properties of the starting materials, such as viscosity, are relatively similar and the materials can be mixed well so that a homogeneous material mixture is produced when passing through the static mixing helix. This is usually limited to certain values of the mixing ratio. In other variants a dynamic, i.e. rotatable mixing helix can be provided in order to achieve a higher degree of flexibility in the homogeneous mixing of the starting material streams.

[0048] As explained earlier, when the two or plurality of starting materials come into contact, a corresponding chemical reaction occurs, which typically leads to an increase in viscosity, so that only a limited time is available for further processing of the mixing material 193 as explained earlier.

[0049] The material mixing system 100 also includes a mixing material buffer store 120, also known as buffer store, with an inlet 121, which is directly or indirectly connected to the mixing unit 110 to receive the mixing material 193 from the mixing unit 110. Furthermore, an outlet 122 is provided through which the mixing material 193 can be discharged, for example to an optional pre-pressure control 130, which in turn passes the mixing material 193 to the output component 192 at a desired pressure.

[0050] The buffer store 120 also has a storage volume 123, which is controllably variable in some embodiments, as already explained or as will be shown in more detail below. It should also be noted that the positions of the inlet 121 and outlet 122 do not necessarily correspond to the positions shown in FIG. 1 and should rather be regarded as functional components only, so that the actual position of the respective connections for inlet 121 and outlet 122 are selected according to the requirements, as explained in more detail below.

[0051] The buffer store 120 is a controlled buffer store which applies a controllable pressure to at least the mixing material in it. This means that the buffer store 120 comprises a pressure control 124 or is at least coupled to it, which is suitable for adjusting the pressure prevailing in the storage volume 123 in a suitable manner and for maintaining it within a certain range so that the pressurization of the mixing material in the storage volume 123 takes place at a relatively precisely set value. The pressure control 124 can, for example, be a unit in which a proportional valve, not shown, is controlled in such a way that a pressure from a pressure accumulator (not shown), i.e. a corresponding fluid, is fed into storage volume 123 and thus pressurizes the material in it with the desired pressure. If the pressure in the storage volume 123 changes, for example by further introduction of mixing material from the mixing unit 110, the pressure control 124 is further configured in such a way that a corresponding compensation of the pressure with a short response time, for example in the range of a few milliseconds up to several tens of milliseconds, can be achieved, for example by providing a corresponding bypass path or venting path, not shown. When a pressure source with a pressurizing fluid is used, the pressurizing fluid can act directly on the mixing material or interact with the mixing material via a displaceable piston, as explained in more detail below.

[0052] In even further embodiments, the pressure control 124 can take place in the form of a direct mechanical coupling, if, for example, the pressure control 124 includes suitable drive components, such as linear motors, rotary motors with spindle drive, rack and pinion drives, electromagnetic drives that produce a linear effect, and the like. The pressure control 124 may have a control device which, independently of the remaining components of the material mixing system 100, is configured to maintain the corresponding pressure in the storage volume 123, taking into account a corresponding externally specified target value. Mechanical pressure regulators may be provided for this purpose, whereby, for example, the corresponding target value is determined by manually setting an appropriate regulator, and the like. In other embodiments, an electronic control device is provided which acts on corresponding actuators, such as a proportional valve and the like, in order to perform the pressure control in the storage volume 123.

[0053] In further illustrative embodiments, an electronic control unit 140 is provided which is configured to take over the function of the pressure control 124, for example by generating corresponding control signals for actuators and/or receiving and evaluating sensor signals or other signals with parameter values of the pressure control 124 or other components of the material mixing system 100, and the like. In advantageous embodiments, the control unit 140 is also functionally connected to at least one other component of the material mixing system 100 and/or the system 190 in order to receive at least parameter values or sensor values and to evaluate them for controlling the buffer store 120. The control unit 140 can be provided in the form of a microcomputer, a microcontroller, and the like, whereby corresponding function modules are implemented, which take over various evaluation and control tasks. It should be noted that modern microcontrollers and programmable logic controllers (PLC) typically have cycle times, i.e. times for a complete run-through of a control algorithm, of one millisecond or less up to several milliseconds, so that a fast response speed is achieved, especially for the control of the buffer store 120.

[0054] Furthermore, it should be noted that often certain components, such as electric motors, valves and the like can be connected to corresponding parts of the control unit 140, which have a certain “intelligence” of their own, so that, for example, the execution of control tasks, such as keeping an electric motor position constant, opening or closing valves, and the like is possible in shorter time intervals compared to the cycle time of the control unit 140. For example, corresponding electric motors can be addressed via the control device 140 by merely specifying one or more target values, such as speed and the like, while the actual control loop is implemented in a subordinate unit, for example a stepper motor control, so that the response speed is given by the mechanics of the respective components to be driven and the corresponding subordinate controls.

[0055] For example, the control unit 140 can be coupled with corresponding drive motors for the screw conveyors of the metering units 194A, . . . , 194C, so that corresponding target values can be specified, compliance with which is then achieved by the subordinate control system in a very precise manner, without these control loops being influenced by the cycle time of the control unit 140. In the same way, the control device 140 can be connected to the mixing unit 110 in order to specify a corresponding target value for the rotational speed when an active mixing unit is considered, or in order to obtain corresponding operating parameters, for example, current consumption of a corresponding motor, to detect a state of a corresponding mixing helix, and the like. In this way, the operating mode of the buffer store 120 can also be adapted in an optimized way to the interaction of the other components of the system 100 and the system 190.

[0056] In one embodiment, the control device 140 is configured to serve as a volume determination device which determines the storage volume on the basis of sensor signals and/or other signals supplied to it, such as from drive components and the like, as described above.

[0057] When operating the system 190 with the material mixing system 100, provided that a suitable mixing ratio for the starting materials is already known and the system 190 is in a functional state, the corresponding volume flows 195A, 195B, 195C are fed from the metering units 194A, . . . , 194C to the mixing unit 110, where a homogeneous mixing of the two or plurality of material components then takes place. The produced mixing material 193 is then first fed to the buffer store 120, in which a quantity of mixing material 193 adapted to the application is stored before the mixing material 193 is discharged at the outlet 122. Especially when using the control unit 140, which has stored corresponding application-specific information or otherwise determines or receives this information, the control of the buffer store 120 can then be made application-specific in such a way that a defined volume flow under a desired pressure is output to the output component 192, which applies the mixing material 193 in the desired form to an object, such as a printed circuit board.

[0058] For example, the control unit 140 can retrieve or determine parameters for a corresponding application, which concern the pot life of the material 193, the current flow in the output component 192, the current state of the buffer store 120, and the like. In this way it is determined, for example, what quantity of mixing material 193 must first be stored in the buffer store 120 before the application process can begin. If, for example, it is known that a relatively high volume flow is required for the dispensing component 192, for example, to wet relatively large-area components, and the control unit 140 knows the corresponding operating conditions of the metering units 194A, . . . , 194C and the mixing unit 110, then a corresponding quantity to be stored and a corresponding dispensing time can be calculated, taking into account the material properties, i.e., the pot life, before a “recharging” of the buffer store 120 is required.

[0059] If, for example, the pot life of the currently used mixing material 193 is relatively long, then for a known required volume flow in the output component 192 it can be determined how much material can be added to the buffer store 120 before the actual application begins. In this way, the output of the mixing material 193 can be adjusted to the special conditions, so that, for example, exactly enough mixing material is stored in the storage 120 so that a certain number of application processes can be reliably carried out without being affected by the increasing viscosity of the mixing material 193. This can also be achieved for a volume flow at the output component 192 that exceeds the maximum possible volume flow of the metering units or the mixing unit 194A, 194C, 110. In this case, the continuous supply of material in the buffer store 120 can also be taken into account in advance to determine the corresponding number of possible application processes and the corresponding quantity of material in buffer store 120.

[0060] If, on the other hand, a relatively low volume flow is required at the output component 192, the control device 140 determines a suitable dwell time for the mixing material in the buffer store 120, taking into account the pot life, so that a corresponding smaller quantity may be sufficient. Nevertheless, fluctuations occurring in the process can be compensated due to the high dynamics of the material mixing system 100.

[0061] It should be noted that the pre-pressure control 130 is provided in conventional systems in order to maintain a certain “constancy” of the pressurization of the mixing material at the output component, but in the present invention this pre-pressure control 130 may be omitted if necessary, provided that the high response speed of the buffer store 120 to pressure fluctuations is considered sufficient for certain requirements.

[0062] FIG. 2 schematically shows a system for generating and applying a mixing material 290, in which a material system 291 has a material source 291A for a first component and a material source 291B for a second material component. The material sources 291A, 291B can be cartridges or other sources providing the two starting materials. In addition, as explained earlier in connection with FIG. 1, a component 291C may be provided, such as a solvent, and the like. The material sources 291A, 2918 are connected to corresponding metering units 294A, 294B, which are provided, for example, in the form of a volumetrically operating system in which a corresponding drive unit of the units 294A or 294B sets a corresponding screw conveyor in motion so that, independent of the pressure and temperature of the input materials, a precisely defined amount of material per unit of time is conveyed, depending on the speed and structure.

[0063] The two metering units 294A, 294B are connected to a mixing unit 210, which is configured, for example, as a static-dynamic mixing unit, which is equipped with a drive component 211, for example an electric motor, and a mixing helix 212. In the case of dynamic mixing, as explained above, the mixing helix 212 is set in rotation by the motor 211 in order to achieve the most homogeneous possible mixing of a mixing material 293 even with very different material properties and/or a large mixing ratio. The mixing unit 210 is connected to a mixing material buffer store or buffer store 220, to whose inlet 221 the mixing material 293 is fed. An outlet 222 is located near the inlet 221 and is connected to an inlet pressure control 230, which in turn is connected to an output component 292, such as a Jetter nozzle and/or a curtain nozzle, and the like.

[0064] The mixing unit 210 in combination with the buffer store 220 and the optional pre-pressure control 230 correspond to a material mixing system according to the invention, as it is explained above in connection with the system 100. In this variant, the buffer store 220 is, for example, configured as a cylindrical hollow body, which is made of inexpensive materials, such as PTFE, although other materials are also available, such as aluminum, and the like.

[0065] The buffer store 220 has a displaceable piston 225, which thus serves to pressurize the mixing material 293 inside the buffer store and at the same time determines the effective storage volume of the buffer store 220. This means that on a side of the piston 225 facing away from the mixing material 293, a fluid storage volume 224A is defined, which is filled with a pressurizing fluid, such as air, nitrogen, and the like, or also a liquid, so that on the one hand the desired pressure is exerted on the piston 225 and on the other hand a corresponding variable adjustment of the effective storage volume for the mixing material 293 is achieved by appropriate supply and discharge of fluid from the fluid storage volume 224A.

[0066] In the embodiment shown, for example, a pressure control 224 for the mixing material 293 is achieved by coupling a suitable fluid source (not shown) to the fluid storage volume 224A above the piston 225 and by providing a corresponding actuator 224B which is capable of controlling and maintaining the pressure in the fluid storage volume 224A at a desired value. For example, the component 224B may include a proportional by-pass valve so that an appropriate amount of fluid can be supplied from the pressure reservoir, not shown, so that a desired pressure is maintained even with a variable amount of mixing material 293, whereas an increase in volume of the mixing material 293 and a resulting force exerted by mixing material 293 on piston 225 allows fluid to escape from fluid storage volume 224A in a controlled manner. As explained above, the pressure control 224 can be achieved by means of an electronic control device or manual controls can be used to maintain the desired pressure conditions in the fluid storage volume 224A.

[0067] Furthermore, in the embodiment shown, a sensor 226 is provided which detects the position of the displaceable piston 225. The sensor 226 can, for example, be configured as an analog path sensor that responds to a corresponding indicator material in the displaceable piston 225. For example, the corresponding indicator material can be provided as a magnet in the piston 225. By detecting the position of the displaceable piston 225, a control device, not shown, such as the control device 140 of FIG. 1, can determine the current value of the effective storage volume so that the quantity of the mixing material 293 present in the buffer store 220 is known at any time. Although the actual quantity of the mixing material 293 can also be obtained on the basis of “indirect” values, as explained above in connection with FIG. 1, the sensor 226 provides a very precise and well temporally well resolved positional information for the displaceable piston 225. In other variants, other sensors can be used, such as a series of discretely arranged reed switches, etc. An electromagnetic coupling between the displaceable piston 225 and a corresponding sensor, which is mounted on the outside of the buffer store 220, can also be used to detect the position of the displaceable piston 225 in a contact-free manner.

[0068] Furthermore, it also applies to the system 290 and the material mixing system with components 210, 220 and 230 that in general the control of the buffer store 220 and at least one other component can be carried out via a corresponding electronic control device, as explained in connection with FIG. 1. For example, the drive components of the metering units 294A, 294B, the motor 211 of the mixing unit 210 can also be controlled by or under the instruction of a corresponding electronic control device, or at least corresponding operating parameters are provided for a corresponding control device so that the status of the system 290 can be evaluated, in particular to control the operation of the buffer store 220 taking into account the status of the system 290.

[0069] During the operation of the system 290, the materials 291A, 291B are discharged according to a previously determined mixing ratio from the metering units 294A, 294B to the mixing unit 210, in which the two components are mixed as homogeneously as possible, for example statically or dynamically, depending on the starting materials, their mixing ratio, and the like. The mixing material 293 is fed to the inlet 221 at a lower area of the buffer store 220, so that against the pressure of the piston 225 the mixing unit 210 conveys the material 293 into the buffer store 220. This means that by moving the piston 225, the introduced mixing material 293 is pressurized by the piston 225 with the pressure which is present in the fluid storage volume 224A and is kept essentially constant by the pressure control 224. If mixing unit 210 continues to operate, further mixing material 293 is introduced into the buffer store 220 against the pressure of the piston 225, while maintaining a relatively constant pressure in the volume 224A. As explained above, the pressure control 224 is configured in such a way that when the fluid storage volume 224A is reduced, fluid can escape, for example to the outside or into a fluid reservoir, not shown, so that the desired pressure is maintained.

[0070] If, on the other hand, mixing material 293 is discharged from outlet 222 by activating the output component 292, the position of the piston 225 may change downwards depending on the feeding volume flow generated by mixing unit 210, so that control component 224B then ensures that the desired constant pressure is maintained in fluid storage volume 224A. If a change in volume flow occurs, for example, due to a change in the jet width of a curtain nozzle, the corresponding resulting pressure fluctuation can be absorbed by pressure control 224 without causing a noticeable change in the pressurization of the mixing material 293. For example, if there is a rapid increase in volume flow to the output component 292, the corresponding decrease in storage volume is compensated by a corresponding movement of the piston 225 and a further introduction of pressurizing fluid into volume 224A, so that very constant pressure conditions continue to exist at the output component 292. The same applies to a reduction of the volume flow if, at about the same time, there is still an inflow of material from the mixing unit 210, so that an increase in material in the buffer store 220 is compensated accordingly.

[0071] As explained above, an electronic control device, not shown, such as the control device 140 described in connection with FIG. 1, can determine a suitable operating mode for a particular application in advance or dynamically for the buffer store 220. For example, a minimum effective storage volume can be determined which is necessary to reliably enable the operation of output component 292 so that, when this minimum storage volume is reached, corresponding material from mixing unit 210 must be delivered in to buffer store 220. For this purpose, for a known profile of the output of mixing material 293, a corresponding quantity of mixing material 293 can be determined, which is necessary for the reliable supply at the given profile in order to ensure the operation of the output component 292 for a corresponding period of time. On the other hand, a maximum effective storage size can also be determined for this purpose, which is determined as a function of the pot life, so that when filling the buffer store 220, no excessive quantities of the mixing material 293 are loaded, which could otherwise contribute to premature curing of the material and thus to the inoperability of the entire system 290.

[0072] In a simple case, such values for the minimum and maximum storage size can be specified as a function of the position of the displaceable piston 225, so that when the minimum piston position is reached, a corresponding signal is sent to the mixing unit 210, and thus also to the metering units 294A, 294B, so that material is mixed again and the buffer store 220 is loaded, if the operation of these units was previously interrupted. Similarly, when the maximum piston position is reached, the further supply of material is interrupted, so that the dwell time of the mixing material 293 in the buffer store 220 is in an uncritical range with respect to the pot life. For example, a position determined as the maximum piston position for this particular application can be defined in such a way that the mixing unit 210 can be reliably emptied in any case without exceeding the critical storage volume in terms of pot life, while at the same time preventing curing of mixing material in mixing unit 210 as far as possible.

[0073] Due to the dynamically controllable storage function of the buffer store 220, especially the mixing unit 210 and the metering units 291A, 291B can be operated in a reliable, possibly relatively limited working range, while still allowing a high dynamics with regard to the volume flow to be provided. In other words, in applications where a high average volume flow in the output component 292 is required, the component 292 can be operated intermittently if the inflow from mixing unit 210 is smaller than the average outflow from the buffer store 220. In this case, suitable minimum and maximum storage volumes are determined so that the output component 292 can be operated reliably and under precisely defined operating conditions for appropriate periods of time, while the buffer store 220 can be filled appropriately during respective operating stops. The metering units 294A, 294B and the mixing unit 210 can be operated continuously without affecting the output pressure during the active phases of the output component 292.

[0074] In addition, pressure transducers may be provided at suitable points to monitor the condition of the system 290, for example after the metering units 294A, 2948 and after the buffer store 220. By determining the pressure conditions, various conditions of the system 290 can be detected, for example a reduction in the “permeability” of a section of pipe, and the like. The values of the pressure transducers can also be used to control the operation of the buffer store 220, whereby it is advantageous to use an electronic control device, such as the control device 140 in FIG. 1,

[0075] FIG. 3A shows a schematic sectional view of a mixing material buffer store 320, briefly referred to as buffer store, which can be used, for example, in the embodiments shown above with reference to FIGS. 1 and 2. The buffer store 320 is part of a material mixing system, e.g. the system 110, which is shown in FIG. 1. The buffer store 320 is therefore connected to a mixing unit 310, which, for example, has a dynamically driven mixing helix 312, in which two or a plurality of material components are mixed as homogeneously as possible, so that a mixing material 393 is formed, which is introduced into the buffer store 320 via an inlet 321, i.e. a passage between the mixing unit 310 and a storage volume 323. The mixing material 393 leaves the storage volume 323 via an outlet 322, which is configured, for example, as a fluid passage to a corresponding supply line for an output component.

[0076] In the embodiment shown, the outlet 322 is connected to a pre-pressure control 330, which, for example, has a further pressure inlet not shown, in order to apply further pressure to the mixing material 393. In other illustrative configurations, pressure can be applied exclusively via the store 320, so that a further volume is not required to pressurize the mixing material 393 before it is fed to a corresponding output component.

[0077] In the embodiment shown, a mechanically simple structure results from the fact that the inlet 321 is directly coupled with the mixing unit 310 as a fluid passage and the outlet is also directly coupled as a fluid passage with the inlet pressure control 330 or a corresponding outlet line.

[0078] Furthermore, a displaceable piston 325 is provided, which leads to a division of the total volume of the fluid reservoir 320 into the effective reservoir volume 323 and into a fluid reservoir volume 324A, which in the embodiment shown is charged with a suitable fluid in order to apply a desired pressure to the mixing material 393 via the displaceable piston 325, as explained above. In advantageous embodiments, the fluid reservoir volume 324A is filled with air or nitrogen and thus represents a pneumatic pressure control for the buffer store 320. The fluid piston 325 has a suitable indicator material 325A, which enables the position of the fluid piston 325 to be detected by a position sensor shown schematically as 326. For example, the indicator material 325A is provided in the form of a magnet and the sensor 326 is an analogously working sensor, so that an almost continuous detection of the current position of the piston 325 is possible. Due to this arrangement, the configuration of the housing of the fluid reservoir 320 can be kept simple, since no corresponding through holes and the like are required for internal sensors.

[0079] In general, the configuration of the fluid reservoir 320 of the embodiment shown is such that the number of dead spaces is kept as low as possible, which is also helped by the contact-free coupling of the indicator material 225A with the sensor 326. It should be noted that the illustrations in FIG. 3A are very schematic and the corresponding feed-throughs and lines, for example in the form of the inlet 321 of the outlet 323 and the line run in the pre-pressure control 330, are actually configured in such a way that the flow of the mixing material 393 is as low-resistant as possible without corresponding areas with flow standstill. For example, the 90° corners shown in the drawing are rounded accordingly in practice.

[0080] The function of the buffer store 320 is similar to the function described above in connection with FIGS. 1 and 2. This means that the mixing unit 310 feeds the interior of the buffer store 320 with the mixing material 393, which thus displaces the displaceable piston 325 against the pressure exerted on the piston 325 in the fluid storage volume 324A, so that the mixing material 393 is thus subjected to the pressure that is set in a controlled manner in the fluid storage volume 324A. As material continues to be fed through the mixing unit 310, the quantity 393 in the effective storage volume 323 increases when the outflow is less than the inflow. On the other hand, the storage volume decreases if the outflow is higher than the inflow. As explained above, by detecting the current position of the piston 325, the corresponding actual storage volume and thus the material quantity 393 can be determined, so that suitable operating conditions are always maintained, which are determined depending on the pot life, the application process, the capabilities of the mixing unit 310 and the upstream metering units, and the like. Also in this case, the operating mode of the buffer store 320 and one or a plurality of further components can be controlled by an electronic control device, such as the control device 140 shown in FIG. 1.

[0081] FIG. 3B shows a schematic perspective view of a possible embodiment of the displaceable piston 325. In the embodiment shown, a suitable outer material 325C is provided which is compatible with the properties of the mixing material. For example, a material can be selected in the same way as it is used for conventional material cartridges. In this way a very tight seal can be achieved between the effective storage volume 323 and the fluid storage volume 324A (see FIG. 3A). Furthermore, an underside 3258 of piston 325 can be configured so that when a mechanically lowest position is reached in the buffer store, complete closure of inlet 321 and/or outlet 322 (see FIG. 3A) is prevented, so that the buffer store can still be charged with material in this position. A corresponding arrangement is therefore favorable for operating conditions in which it is advantageous to empty the buffer store almost completely. For example, when calibrating the buffer store and/or the metering units and when determining suitable metering ratios, emptying the buffer store can facilitate a more precise determination of calibration values and parameters. Furthermore, as explained above, the piston 325 may have a suitable indicator material, such as the material 325A from FIG. 3A, which is encased by the outer material 325C.

[0082] FIG. 4A shows a schematic sectional view of a buffer store 420, which can also be used in the material mixing systems explained above. In the variant shown, the buffer store 420 has a displaceable piston 425, which thus dynamically adjusts an effective storage volume 423 and therefore directly applies pressure to a corresponding mixing material (not shown), as described above in connection with the embodiments of FIGS. 2 and 3A, 3B. However, in the case of pressure control by means of a fluid, an electric or electromagnetic pressure control 424 is provided, which has a drive unit 424C, for example in the form of a rotating electric motor, and a corresponding unit for converting the rotary motion into a linear motion 424D. For example, corresponding linear drives are well known as spindle drives. By controlling the 424C drive unit, the piston 425 can thus be moved and, in case of contact with the mixing material, a desired pressure can be exerted, which can be precisely adjusted by operating parameters of the 424C drive unit. For example, the drive unit 424C can be coupled with a suitable control device, such as the control device 140 shown in FIG. 1, with the interposition of appropriate control components, such as a converter, and the like, so that an exact position and/or pressure for the piston 425 can be set.

[0083] For example, by monitoring the corresponding motor speed, the current position of the piston 425 can be evaluated directly and, for example, when mixing material is fed into the buffer store 420, the correspondingly caused displacement of the piston 425 can be read out via a corresponding step counter, position sensor, and the like for the drive unit 424C. At the same time, the force on the piston 425 can also be precisely determined by a corresponding target value for the torque of the drive unit 424C, so that a desired constant pressurization of the mixing material results. The reaction time of the system consisting of piston 425 and pressure control 424 is in the range of typical pneumatic pressure control systems or even below, whereby the use of electrical or electromagnetic components in particular contributes to the higher energy efficiency of an overall system. The piston 425 can also be provided without additional indicator materials and the like, since precise position determination is guaranteed by the drive unit 424C and the associated electronic control unit.

[0084] Furthermore, it is also possible to detect an impermissible or cured state of a mixing material by evaluating the corresponding change in position of the piston 425 and the current to be memorized by the drive unit 424C.

[0085] FIG. 4B schematically shows another variant in which a linear displacement of the piston 425 is made possible by an electric or electromagnetic drive device. For this purpose, for example, a rotary motor 424F is provided in conjunction with a rack 424E, which is directly coupled to the piston 425. In this way too, the position of piston 425 and the pressure exerted on the mixing material in storage volume 423 can be reliably determined. With regard to the control of the drive unit 424F, essentially the same criteria apply as explained above.

[0086] Furthermore, this embodiment shows a pre-pressure control 430, which can also be used in the embodiment shown in FIG. 4A, if the pressure control by means of the buffer store 420 is to be further improved in dynamics.

[0087] It should be noted that the electrical or electromagnetic drive systems shown in FIGS. 4A and 4B are also intended to be representative of other electromagnetic drive systems, such as linear motors, which allow direct linear motion without the detour of rotary motion, or electromagnetic systems in which a plunger in an electromagnet is directly coupled to piston 425. Also included are electromagnetic systems in which the piston 425 itself serves as a drive component, for example by representing a part of a magnetic circuit, whereby, according to the reluctance principle, a displacement of the piston 425 is caused by suitable generation of a magnetic field.

[0088] FIG. 5A shows a variant of a buffer store 520, which can be used in the material mixing system 100 of FIG. 1, for example. In the buffer store 520, for example, a pressurizing fluid, which is schematically provided as 524A as part of a pressure control 524, is in direct contact with a mixing material 593. For this purpose, the pressurizing fluid 524A is preferably provided as an essentially inert material with respect to the mixing material 593. This means that suitable liquids and/or gases can be used which do not essentially affect the chemical reaction taking place in the mixing material 593. The pressure control 524 is configured so that the fluid 524A is introduced into the buffer store 520 in such a way that a desired pressure is always maintained in the storage 520. This can be done, for example, by means of appropriate pneumatic or hydraulic components, as explained above. If necessary, an appropriate shut-off device can be provided at an inlet 521 and/or an outlet 522 of the storage to prevent fluid from flowing out when the storage is completely empty. In other embodiments, the corresponding fluid 524A is sucked off accordingly when the buffer store is completely empty.

[0089] Here, too, the compression caused by the decrease in volume of the fluid 524A when gaseous fluids are considered, or the force exerted on the fluid 524A when incompressible fluids are considered, is compensated in the pressure control 524 by discharging fluid into a corresponding storage, so that the material 593 is still pressurized with the same pressure. On the other hand, more fluid is supplied if the effective volume in the buffer store 520 is reduced by draining the mixing material 593.

[0090] In the embodiment shown, the inlet 521, which is coupled to a corresponding mixing unit, is also provided remotely from outlet 522, so that incoming new mixing material is applied to already existing mixing material, so that the material that has been in the storage for the longest time is always discharged via the outlet 522, so that the problem of pot life can be defused even further, since the material with the longest dwell time is always discharged. Again, the inlet 521 and the outlet 522 are configured to achieve the lowest possible flow resistance and almost no dead spaces.

[0091] FIG. 5B shows another variant of the buffer store 520, where the mixing material 593 is in direct contact with the pressurizing fluid 524A, but this is also pressurized by a displaceable piston 525 in order to compensate for the volume changes at the desired pressure. The displaceable piston 525 can be driven pneumatically, mechanically, etc., as explained above.

[0092] The direct contact of the pressurizing fluid 524A with the mixing material 593 can lead to a more trouble-free operation, in particular, since, for example, mechanical deficiencies in connection with a displaceable piston that is directly in contact with the mixing material can be largely avoided. For example, cured residues of mixing material in the area of the inner surface of the buffer store, which is also the sliding surface with the piston, can lead to disturbances of the piston movement. In addition, the fluid 524A can be replaced in a suitable manner or even used as a flushing agent if the interior of the buffer store 520 must be cleaned after a successful run.

[0093] The present invention thus provides a material mixing system which offers a mode of operation with significantly higher dynamics compared to conventional mixing systems, since the pressure-regulated buffer store allows a higher degree of flexibility to react to different requirements when applying a mixing material. The mode of operation of the buffer store can be efficiently integrated into the general control cycle of a corresponding material mixing system and a higher-level mixing material production and application system. For example, when calibrating, setting mixing ratios, and the like, the buffer store can be controlled to a precisely defined operating state so that correspondingly obtained results can be obtained with the same precision as with conventional systems.