METHOD AND APPARATUS FOR CONTINUOUSLY MAKING COMPOSITE STRIPS OR SHEETS

Abstract

The invention relates to a method for producing composite strips or composite sheets, consisting of at least a lower cover layer (1) of metal, an upper cover layer (2) of metal, and a core layer (3) of plastic, which is arranged between the cover layers (1, 2) and is integrally bonded thereto, wherein a first metal strip (4) for the lower cover layer (1), a second metal strip (5) for the upper cover layer (2), and a plastic web (6) for the core layer (3) are continuously brought together and continuously integrally bonded to each other by the application of pressure and/or heat. The method is characterized in that the metal strips are locally bonded to each other by means of a strip-bonding device as the metal strips approach the continuous process.

Claims

1. In a method of making composite strips or sheets consisting of at least one first outer layer of metal, one second outer layer of metal, and at least one core layer of plastic between the outer layers and integrally joined therewith, where a first metal strip for the first outer layer, a second metal strip for the second outer layer, and a plastic web for the core layer are brought together continuously and integrally joined with one another continuously under the application of pressure and/or heat, the improvement wherein the metal strips are joined directly together locally by a strip-joining device during startup of the continuous process.

2. The method defined in claim 1, wherein the metal strips are first joined together locally during process startup without an interposed plastic web.

3. The method defined in claim 1, wherein the metal strips are temporarily stopped during process startup and joined together locally while stationary.

4. The method defined in claim 1, wherein the metal strips are joined together locally during transporting of the strips, for example in a low-speed creep mode.

5. The method defined in claim 1, wherein the metal strips are joined together locally through punching, riveting, clinching, gluing, and/or welding.

6. The method defined in claim 1, wherein the metal strips are joined together locally after having been brought together and before being heated together.

7. The method defined in claim 1, wherein the metal strips are joined near the leading end of one of the strips.

8. A system for making composite strips or sheets having at least one lower outer layer of metal, one upper outer layer of metal, and one core layer of plastic between the outer layers and integrally joined therewith, the system comprising; a joining device in which metal strips can be brought together with interposition of a plastic web, and a strip-joining device for the local direct joining of the metal strips during process startup in the joining device or in the direction of travel of the strips downstream of same.

9. The system defined in claim 8, wherein the strip-joining device is a punching device, riveting device, clinching device, gluing device, and/or welding device.

10. The system defined in claim 8, wherein the strip-joining device is set up to produce a strip connection of moving strips by making the strip-joining device movable in the strip-travel direction.

11. The system defined in claim 8, further comprising: a heating and/or pressing device is downstream from the joining device, with the strip-joining device being between the joining device and the heating and/or pressing device.

12. The device defined in claim 8, wherein the strip-joining device is designed for a strip connection in an approximately horizontal travel direction.

13. The device defined in claim 8, wherein the strip-joining device is designed for a strip connection in an approximately vertical travel direction.

Description

[0026] The invention is explained in further detail below with reference to a schematic drawing, that illustrates only one embodiment.

[0027] FIG. 1 is a simplified cross-sectional view of a composite strip or composite sheet,

[0028] FIG. 2 is a highly simplified side view of a system for producing the composite strips according to FIG. 1,

[0029] FIG. 3 shows a second embodiment of the system of FIG. 1, and

[0030] FIG. 4 shows a third embodiment of the system of FIG. 1.

[0031] With the system illustrated in FIGS. 2 to 4, composite strips or composite sheets can be produced that are made of at least one first outer layer 1 of metal, one second outer layer 2 of metal, and at least one core layer 3 of plastic that is between the outer layers 1, 2, with the outer layers 1, 2 being integrally joined with the plastic core layer 3.

[0032] In order to produce such a composite strip according to FIG. 1, a first metal strip 4 for the first outer layer and a second metal strip 5 for the second outer layer and a plastic web 6 for the core layer are supplied in the systems according to FIGS. 2 to 4. The first metal strip 4 and the second metal strip 5 and the plastic web 6 are continuously brought together and joined integrally with one another under the application of pressure and/or heat. For this purpose, at least one joining device 11 is provided in the systems.

[0033] The first metal strip 4 is unwound from a first supply reel 7 and optionally coated with an adhesion promoter. Details in this regard as well as additional optional possibilities for pretreatment are not shown in the figures. The second metal strip 5 for the second outer layer is unwound from another supply reel 13 and optionally coated with an adhesion promoter. Here as well, details regarding these and other optional possibilities for pretreatment are not shown.

[0034] The plastic web 6, which can for example be a plastic film, is unwound from a supply reel 9 and optionally preheated. Details on the preheating of the plastic web as well as on the optional preheating of the metal strips are not shown.

[0035] The first metal strip 4 and the second metal strip 5 are brought together in a continuous process with interposition of the plastic web 6, and the composite web according to the invention is produced in this way. The composite of metal strips 4, 5 and plastic web 6 can then pass through a heating and pressing section (not shown specifically) as well as through other optional system elements. The composite strip produced in this way can either be wound as a continuous strip onto a reel 15 or cut right away in the system into plates or sheets. Details are not shown.

[0036] It will readily be understood that such a system is equipped in a customary manner with appropriate drivers, tension rollers, strip-storage units, etc. Details in this regard are not shown in the figures, either.

[0037] The startup process of such a system, which is shown schematically for the sake of example in various variants in FIGS. 2 to 3, has special significance in the context of the invention. This is because, according to the invention, the metal strips 4, 5 are directly joined together locally by a strip-joining device 17 during startup of the continuous process.

[0038] FIG. 2 shows a first embodiment with substantially horizontal stock travel guide, that is, the strip connection is produced with strips that run substantially horizontally.

[0039] In the illustrated embodiment, the metal strips 4, 5 are brought together in a startup phase without the plastic web 6. The first metal strip 4 and the second metal strip 5 are thus brought together without the plastic web 6 being interposed in this startup phase. This is indicated in FIG. 2. This means that the first metal strip 4 and the second metal strip 5 first pass through the joining device 11 without interposed plastic web and arrive in the area of the strip-joining device 17 where the two metal strips are joined together without interposition of the plastic web 6, specifically locally. The strip connection produced by the strip-joining device 17 that forms a seam that extends over the width of the strip must be differentiated from the integral connection produced via the plastic web during the subsequent continuous process. Here, the strips are stopped for the strip-joining. After the strip connection has been produced, travel of the metal strips is resumed. Only after this strip connection has been produced is the plastic web 6 fed into the joining device 11, so that the local strip connection follows the desired multilayer construction.

[0040] For example, a provision is made in this regard that the first strip 4 is drawn completely into the system, so that it is pulled through the system by a draw roller (not shown) and/or the coiling reel 15. The second metal strip 5 is fed via a drive 16 with its leading end to the lower strip 4, particularly through the joining device 11, through a pair of pressure rollers, for example, and into the area of the strip-joining device 17. As soon as the leading end of the second strip 5 has reached the strip-joining device 17, the second strip 5 is also stopped, and the second strip 5 can be joined locally with the first strip 4 without the plastic web being interposed. After the connection has been established, the drive 16 can be opened, since the strip tension can then be maintained by the strip connection. The first metal strip 4 and the second metal strip 5 are then drawn together through the system, and the plastic web 6 is then also guided into the joining device 11, thus creating the desired multilayer construction.

[0041] FIG. 3 shows a modified embodiment of such a system in which the strip connection is produced not with horizontal but with substantially vertical stock guidance. In the illustrated embodiment, the first metal strip 4 is again first drawn into the system and stopped. The second strip 5 is then fed in via the drive 16. As soon as the leading end of the strip has reached the strip joiner 17, the local strip connection is created, particularly with vertical strip guidance. The joining device 11 is also embodied as a pair of rollers or as a calender that can be opened and closed. In this embodiment, the drive roller 16 is combined with the calender 11, but a separate drive 16 can also be provided. FIG. 3 shows the joining device 11 in the opened position, but the pair of rollers is closed during operation for the bringing-together of the strips. The consolidated composite of metal strips 4, 5 and plastic web 6 can then pass through an additional calender and/or a subsequent heating section and/or a heating and pressing section. This is only shown in FIG. 3 but can also be provided in the variants according to FIGS. 2 and 4.

[0042] FIG. 4 shows a modified embodiment in which the plastic web 6 is fed to the metal strips 4, 5 in two stages in the continuous process. The joining device 11 has a first laminater 11a in which the plastic web 6 is brought together with the first metal strip 4. Moreover, the joining device 11 has a second laminater 11b in which the second metal strip 5 is fed in and joined with the plastic web 6. In this embodiment as well, a strip joiner 17 is provided. During startup, the possibility thus exists of first drawing the first metal strip 4 completely into the system and stopping it. Before the plastic web 6 is fed in, the second metal strip 5 is first loaded in the second laminater 11b. As soon as the leading end of the second metal strip 5 has reached the strip joiner 17, the local strip connection occurs. The drive 16 can then be opened again, so that the strip tension of the second metal strip 5 is maintained by the strip connection. After that, the first metal strip 4 can then be drawn through the system with the second metal strip 5 fastened thereto and the plastic web 6 fed in for the continuous process.

[0043] The separated tension-guiding of the metal strips 4 and 5 shown in FIG. 4 can be implemented not only in the illustrated vertical embodiment, but also in a horizontal embodiment. Such an embodiment is not shown in the figures.

[0044] Moreover, strip shears 12 and additional drive rollers 14 are indicated in the figures which are of importance particularly when the process is momentarily stopped.

[0045] A leading-end strip connection is therefore of importance according to the invention. This offers the advantage that delamination near the leading end of the strip is prevented. Disruptions of the production process are thus prevented. This is very important in terms of the cost-effectiveness of the overall process. Moreover, in the areas of the system after the joining device 11, the plastic web is reliably prevented from being joined with the other system components and particularly rollers, for example pressure rollers, during pressing, so that the system components are also protected and disruptions avoided in this regard.