METHOD AND APPARATUS FOR CONTINUOUSLY SUPPLYING A METERING DEVICE

In a method for continuously supplying a metering device with different batches of one and the same liquid medium, a progressive addition of the medium of a new batch takes place during a batch change.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of foreign priority under 35 U.S.C. § 119 of German patent application number 102022115177.8, filed on Jun. 17, 2022. The contents of this application are incorporated herein by reference in their entirety.

INTRODUCTION

The present invention relates to a method and an apparatus for continuously supplying a metering device with different batches of one and the same liquid medium.

In industrial production, there is often the problem that different batches of liquids, for example of adhesives or of casting materials, differ significantly with respect to their properties. However, a compensation can take place through changes of metering parameters, such as the opening time of a metering valve, media pressure, or also temperature, in order to achieve the same metering result even with changed media parameters, for example with a changing viscosity. If the result is controlled during the metering, minor and slowly occurring changes can be compensated by adapting metering parameters. However, the problem occurs here that the properties of the medium to be metered can change so much during a batch change that a readjustment of metering parameters is not sufficient to achieve consistent metering results.

To solve this problem, the possibility exists to either clean or replace all the components guiding the medium during a batch change. In this case, the metering system, however, has to be readjusted to the properties of the subsequent batch. If, on the other hand, a batch change takes place without cleaning, an abrupt change in the media properties nevertheless occurs, during which change an automatic readjustment of the metering parameters is not possible.

It is therefore the object of the present invention to provide a method and an apparatus for continuously supplying a metering device, by which method and apparatus a 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. This object is satisfied by the features of the independent claims.

SUMMARY

To satisfy the object, in accordance with a first aspect, a method for continuously supplying a metering device with different batches of one and the same liquid medium is provided, in which method a new batch is supplied to the metering device after the metering of a first batch. In this respect, the medium of the new batch is progressively added to the medium of the first batch with the aid of a control during such a batch change. Due to a progressive addition, i.e. a gradually increasing addition, of the medium of the new batch to the medium of the old batch, it can be achieved that the transition between the two batches is smoothed and a control of the metering device can perform a continuous adaptation to the properties of the two media by adapting metering parameters. The regulation of the metering device can hereby compensate the only minor changes in the parameters of the added medium, whereby an interruption-free production is possible. Since the addition of the new batch is controlled by a control, the transition between the two media can be controlled as desired and in particular such that no abrupt but only minor changes in the material parameters of the medium supplied to the metering device take place.

Advantageous embodiments of the invention are described in the description, in the drawing, and in the dependent claims.

In accordance with a first advantageous embodiment, the medium of the first and the new batch can be mixed in a line before it is supplied to the metering device. Due to such a common supply line, into which the medium of the old batch and the medium of the new batch are added in a specific mixing ratio, a mixing can take place within the line without additional mixing components, for example static mixers or the like, being necessary for this purpose.

In accordance with a further advantageous embodiment, the volume of the medium added per unit of time can be predefined by the control. Thus, it can be predefined in the control that, for example, the medium of the new batch is first added to the medium of the old batch only in small quantities and in increasing quantities as the time increases, whereby only minor changes in the medium added to the metering device result after the mixing of the two media.

In accordance with a further advantageous embodiment, the medium of the first batch can be supplied from a first container and the medium of the second batch can be supplied from a second container, wherein the medium in the second container is conditioned while the metering device is supplied with medium from the first container. The advantage hereby results that, when maintaining a continuous operation, a preconditioning of the new batch is possible, for example, a mixing, a temperature control, and/or a degassing.

In accordance with a further advantageous embodiment, a metering device can be used with which an automatic adaptation of metering parameters takes place in the event of a change in the viscosity of the medium to be metered. In this case, a constant metering result can also be achieved with then only minor changes in the material properties of the medium to be metered without having to interrupt the operation for this purpose.

In accordance with a further advantageous embodiment, an apparatus for carrying out a method of the kind described above can be provided that has a first and a second container and a first and a second pump, wherein, with the pumps, medium can be supplied to a metering device via a common line. Furthermore, a control can be provided that is configured and adapted to control the two pumps such that medium from the second container is progressively added to the medium from the first container. The quantity supplied by each pump into the common line can be predefined and set by suitably controlling the two pumps, wherein the ratio of the volumes supplied by the two pumps into the common line per unit of time can in particular also be predefined.

If, for example, piston pumps are used, the number of piston strokes per unit of time and/or the length of the respective piston stroke can be predefined with the aid of the control. For a progressive admixing of the medium of the new batch to the medium of the old batch, one pump can, for example, first perform nine pump strokes, while the other pump performs one pump stroke per unit of time. This ratio can then be progressively changed over a predetermined period of time so that at the end of the transition phase only the pump of the new batch is in operation, while the pump of the old batch is switched off. The mixing of the two media of the old and the new batch can in this respect take place in an advantageous manner in a common line whose input is connected to the two pumps and whose output is connected to the metering device.

In accordance with a further advantageous embodiment, both containers can be provided with a filling level sensor, wherein the control performs a control of the two pumps in dependence on signals of the filling level sensors. In this embodiment, a continuous operation can be performed in an automated manner since it can be determined with the aid of the filling level sensors when the medium of a batch in a container is running low. The pump supplying the medium of the new batch can then be activated to ensure the smooth transition between the two batches by a progressive admixing.

DETAILED DESCRIPTION

FIG.1shows an apparatus for continuously supplying a metering device10with different batches A and B of one and the same liquid medium. The metering device10is only shown schematically and comprises at least one metering valve, for example a jet valve, with which the medium can be applied in very small quantities. Furthermore, the metering device has a regulation known per se with which small changes in material properties of the medium to be metered can be compensated by adapting metering parameters, such as the opening time of the metering valve, media pressure, or temperature, in order to achieve consistent metering results.

The apparatus shown inFIG.1furthermore has two substantially identical containers12and14, wherein the medium of a first batch A is filled into the container12and the medium of a second batch B is filled into the container14. However, both media are the same liquid medium, for example an adhesive or a casting material, that can, however, have different material parameters due to the different batches. To supply the medium, the container12is in communication with a pump16and the container14is in communication with a pump18. By means of the two pumps16and18, the medium present in the container can in each case be pumped from the containers12and14into a common line20that is connected to the two pumps16and18via supply lines22and24. The contents of the two containers12and14can thus be supplied to the metering device10via the common line20.

In the embodiment shown, the two pumps16and18are designed as piston pumps and have a magnetically marked piston26and28, respectively, whose position can be read out via a magnetic measurement system, for example, Hall elements30,32. Two check valves34and36in the region of the pump16and two check valves38and40in the region of the pump18serve to alternately supply medium from the container12or the container14into the common line20.

In the embodiment shown, a control of the two piston pumps16and18takes place by a respective two pneumatic valves that are connected to a pressure supply P and a pressure return means R in a known manner.

Furthermore, in the embodiment shown, a control50is provided that serves to control the two pumps16and18such that medium from the one container can be progressively added to the medium from the other container.

To automatically recognize such a batch change, both containers12and14are each provided with a filling level sensor52and54that detects the respective filling level in the containers12and14by means of a float56and58. If, for example in the container12, the medium of the batch A located therein has reached a residual quantity, as shown inFIG.1, a small stroke of the pump18can be triggered after a full stroke of the pump16so that only a small quantity of the new batch B is added through the supply line24into the common line20. The control50is in this respect programmed such that the volume that is conveyed from the container12is continuously reduced, while the volume that is conveyed from the tank14is continuously increased. A gradual progressive transition between the media of the two batches A and B hereby takes place. A uniform mixing of the two media in this respect takes place in an advantageous manner within the common line20through which the medium of the two batches is supplied to the metering device10. Due to the laminar flow within the line20, a mixing of the two batches takes place, which is illustrated inFIG.2. It shows how, in the line20, two consecutive media are distributed by the flow front and are mixed.

FIG.3illustrates the volume reduction of the medium of the batch A supplied from the container12and the simultaneous volume increase of the medium B supplied from the container14. As can be seen, the volume of the batch A supplied per unit of time to the metering device10or to the line20is reduced, while the volume of the batch B supplied per unit of time is increased until only the medium of the batch B is supplied.

Finally,FIG.1shows that both containers12and14can each be provided with a stirring unit60,62to condition the medium in one container while medium from the other container is supplied to the metering device10. In addition, the containers can be provided with a temperature control device and/or a degassing device.

It is understood that the embodiment described above is of a purely exemplary nature. For example, the pumps16and18can also be replaced by any other pumps. A regulation of the media quantity supplied can in any case be achieved by predefining the pumping volume to be conveyed by a pump per unit of time.