Method and apparatus for continuously feeding a metering device - Patents.com

Abstract

To provide a method and an apparatus for continuously supplying a metering device, by which the metering device can be continuously supplied with different batches without a cleaning or a replacement of components being required or a complete readjustment of the metering parameters having to take place.SOLUTION: A method for continuously supplying a metering device 10 with different batches A and B of one and the same liquid medium is provided, in which method a new one of the batch B is supplied to the metering device 10 after metering of the first batch A, during such a batch change, the medium of the new batch B is progressively added to the medium of the first batch A with the aid of a control 50.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for continuously supplying different batches of the same liquid medium to a metering device. [Background technology]

[0002] In industrial production, the problem often arises that different batches of liquids, e.g. adhesives or casting materials, differ significantly with regard to their properties. However, by compensating by changing metering parameters such as the opening time of the metering valve, the medium pressure or the temperature, the same metering result can be obtained even when a medium parameter, e.g. the viscosity, changes. If the metering result is controlled during metering, minor, slowly occurring changes can be compensated for by adapting the metering parameters. However, the properties of the metered medium may also change so much during a batch change that a consistent metering result cannot be obtained by simply readjusting the metering parameters.

[0003] To solve this problem, it has been proposed to clean or replace all components that guide the medium during the batch change. However, this requires a readjustment of the metering system to the properties of the subsequent batch. On the other hand, if the batch change is carried out without cleaning, the properties of the medium change so rapidly that an automatic readjustment of the metering parameters during the change is not possible. Summary of the Invention [Problem to be solved by the invention]

[0004] It is therefore an object of the present invention to provide a method and apparatus for continuously feeding a metering device, which allows different batches to be continuously fed to the metering device without the need for cleaning or replacement of components or a complete readjustment of the metering parameters. [Means for solving the problem]

[0005] This object is achieved by means of the features of the independent claims.

[0006] To this end, according to a first aspect, a method is provided for the continuous feeding of different batches of the same liquid medium to a metering device, in which a new batch is fed to the metering device after the metering of the first batch. In this regard, during such a batch exchange, with the aid of a control unit, the new batch of medium is added progressively to the first batch of medium. The progressive, i.e. gradually increasing, addition of the new batch of medium to the old batch of medium results in a smooth transition between the two batches, and the control unit of the metering device can carry out a continuous adaptation to the properties of the two media by adapting the metering parameters. By controlling the metering device, slight changes in the parameters of the added medium can be compensated for, allowing uninterrupted production. Since the addition of the new batch is controlled by the control unit, the transition between the two media can be controlled as desired, in particular in such a way that only slight changes occur without abrupt changes in the material parameters of the medium fed to the metering device.

[0007] Advantageous embodiments of the invention are described in the specification, the accompanying drawings and the dependent claims.

[0008] According to a first advantageous embodiment, the first batch and the new batch of medium can be mixed in line before being fed to the metering device. Such a common feed line, in which the old batch of medium and the new batch of medium are added in a specific mixing ratio, allows the mixing to take place in line without the need for additional mixing components for this purpose, such as for example static mixers.

[0009] According to a further advantageous embodiment, the amount of medium added per unit of time can be preset by the control unit. Thus, for example, it can be preset in the control unit so that a new batch of medium is first added in small amounts to an old batch of medium, with the amount increasing over time. This results in only small changes in the medium added to the metering device after mixing of the two media.

[0010] According to a further advantageous embodiment, a first batch of medium can be fed from a first container and a second batch of medium can be fed from a second container, whereby the medium in the second container is conditioned while the metering device is being fed with medium from the first container, which has the advantage that preconditioning, e.g. mixing, temperature control and / or degassing of the new batch is possible while maintaining a continuous operation.

[0011] According to a further advantageous embodiment, the metering device can be used in such a way that an automatic adaptation of the metering parameters takes place when the viscosity of the metered medium changes, whereby only small changes in the material properties of the metered medium are necessary to achieve a constant metering result, without having to interrupt operation for this purpose.

[0012] According to a further advantageous embodiment, an apparatus for carrying out a method of the above-mentioned kind may be provided, which comprises a first and a second container and a first and a second pump, by means of which the medium may be supplied to the metering device via a common line. Furthermore, a control may be provided, which is configured and adapted to control the two pumps such that the medium from the second container is added progressively to the medium from the first container. The amount supplied by each pump to the common line may be predefined and set by appropriately controlling the two pumps. Here, in particular, the ratio of the amounts supplied by the two pumps to the supply line per unit time may also be predefined.

[0013] For example, if a piston pump is used, the number of piston strokes per unit time and / or the length of each piston stroke can be preset with the help of a control unit. If the new batch of medium is to be mixed progressively into the old batch of medium, for example one pump first performs 9 pump strokes and the other pump performs 1 pump stroke per unit time. This ratio is then gradually changed over a predefined period of time so that at the end of the transition phase only the pump of the new batch is in operation and the pump of the old batch is switched off. In this regard, the mixing of the two media, old and new batches, can advantageously be performed in a common line, the input of which is connected to the two pumps and the output of which is connected to a metering device.

[0014] According to a further advantageous embodiment, both containers can be provided with a filling level sensor. Here, the control unit controls the two pumps depending on the signal of the filling level sensor. In this embodiment, the continuous operation can be performed automatically, since with the help of the filling level sensor it can be determined whether or not to perform the continuous operation when the batch of medium in the container is low. The pump supplying the new batch of medium can then be activated to ensure a smooth transition between the two batches by gradual mixing. [Brief description of the drawings]

[0015] The invention will now be described, purely by way of example, with reference to advantageous embodiments thereof and the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram of an apparatus for continuously supplying media. [Diagram 2] FIG. [Diagram 3] FIG. 13 is a diagram showing the feed amount during batch exchange. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] FIG. 1 shows an apparatus for continuously feeding different batches A and B of the same liquid medium to a metering device 10. The metering device 10 is only shown diagrammatically and comprises at least one metering valve, for example a jet valve, by means of which the medium can be fed in small portions. Furthermore, the metering device has a known control, by means of which slight changes in the material properties of the medium to be metered can be compensated for by adapting metering parameters such as the opening time of the metering valve, the medium pressure or the temperature. This allows consistent metering results to be obtained.

[0017] Furthermore, the device shown in Fig. 1 has two substantially identical containers 12 and 14, where a first batch A of medium is filled in the container 12 and a second batch B of medium is filled in the container 14. Both media are the same liquid medium, e.g. adhesive or casting material, but being different batches, may have different material parameters. To supply the media, the container 12 communicates with a pump 16 and the container 14 communicates with a pump 18. By means of the two pumps 16 and 18, the media in the containers can be transferred from the containers 12 and 14 via supply lines 22 and 24, respectively, to a common line 20 connected to the two pumps 16 and 18. In this way, the contents in the two containers 12 and 14 can be supplied to the metering device 10 via the common line 20.

[0018] In the embodiment shown in the figure, the two pumps 16 and 18 are designed as piston pumps and have magnetically marked pistons 26 and 28, respectively. The position of the pistons can be read off via a magnetic measuring system, for example via Hall elements 30 and 32. Two check valves 34 and 36 in the region of the pump 16 and two check valves 38 and 40 in the region of the pump 18 serve to alternately supply the medium from the container 12 or 14 to the common line 20.

[0019] In the embodiment shown, the control of the two piston pumps 16 and 18 is effected by two pneumatic valves, respectively, connected to a pressure supply P and a pressure return R in a known manner.

[0020] Furthermore, in the embodiment shown, a control unit 50 is provided which serves to control the two pumps 16 and 18 such that medium from one container is added incrementally to medium from the other container.

[0021] In order to automatically recognize such a batch exchange, both vessels 12 and 14 are provided with filling level sensors 52 and 54, respectively, which detect the respective filling levels in vessels 12 and 14 by means of floats 56 and 58. If, for example, the medium of batch A in vessel 12 reaches a remaining amount as shown in FIG. 1, a small stroke of pump 18 can be triggered after a full stroke of pump 16, so that only a small amount of the new batch B is added into the common line 20 via supply line 24. In this regard, the control unit 50 is programmed such that the amount conveyed from vessel 12 is continuously decreased and the amount conveyed from vessel 14 is continuously increased. This results in a gradual transition between the media of the two batches A and B. In this regard, a homogeneous mixing of the two media is advantageously performed in the common line 20, which supplies the two batches of media to the metering device 10. Due to the laminar flow in the line 20, the mixing of the two batches is performed as shown in FIG. 2. FIG. 2 shows how, in the line 20, two successive media are distributed and mixed by a flow front.

[0022] 3 illustrates a decrease in the amount of batch A medium being dispensed from vessel 12, and a simultaneous increase in the amount of medium B being dispensed from vessel 14. As shown, the amount of batch A being dispensed per unit of time to metering device 10 or line 20 decreases, while the amount of batch B being dispensed per unit of time similarly increases, until only batch B medium is being dispensed.

[0023] 1 shows that the vessels 12 and 14 can be provided with stirring units 60 and 62, respectively, which condition the medium in one vessel while the medium from the other vessel is being fed to the metering device 10. The vessels can also be provided with temperature control devices and / or degassing devices.

[0024] It should be noted that the above-described embodiments are purely exemplary. For example, pumps 16 and 18 can be replaced by other pumps. Control of the amount of medium delivered can be achieved by presetting the pump volume delivered by the pump per unit time.

Claims

1. A method for continuously feeding different first and new batches (A) and (B) of the same liquid medium to a metering device (10), comprising the steps of: feeding the medium of the new batch (B) to the metering device (10) after the metering of the first batch (A); and during such batch exchange, with the aid of a control unit (50), gradually increasing amounts of medium of the new batch (B) are added to the medium of the first batch (A), the first batch (A) of medium and the new batch (B) of medium are mixed in a line (20) through which the first batch (A) of medium and the new batch (B) of medium are supplied to the metering device (10); A method comprising:

2. 2. The method according to claim 1, characterized in that the amount of medium added per unit time is preset by the control unit (50).

3. 3. The method according to claim 1 or 2, characterized in that the first batch (A) of medium is supplied from a first container (12) and the new batch (B) of medium is supplied from a second container (14), and the medium in the second container (14) is conditioned while the metering device (10) is supplied with medium from the first container (12).

4. 4. The method of claim 3, characterized in that the medium in the second container (14) is degassed.

5. Method according to any one of the preceding claims, characterized in that the metering device (10) is adapted such that an adaptation of the metering parameters takes place when the viscosity of the medium to be metered changes.

6. 6. An apparatus for carrying out the method according to any one of claims 1 to 5, comprising a first container (12) and a second container (14), a first pump (16) and a second pump (18), said first pump (16) and said second pump (18) being capable of supplying a medium to a metering device (10) via a common line (20), and a control unit (50) configured and adapted to control the two first pumps (16) and the second pumps (18) such that medium from the second container (14) is added progressively to the medium in the first container (12).

7. 7. The device according to claim 6, characterized in that both the first container (12) and the second container (14) are provided with filling level sensors (52, 54), and the control unit (50) controls the two first pumps (16) and the second pump (18) in response to signals from the filling level sensors (52, 54).

8. 8. Apparatus according to claim 6 or 7, characterized in that both the first vessel (12) and the second vessel (14) are provided with stirring units (60, 62) and / or temperature control devices.

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