METHOD AND APPARATUS FOR CONTINUOUSLY MAKING COMPOSITE STRIP OR SHEETS

Abstract

The invention relates to a method for producing composite webs or composite sheets, consisting of at least a first lower cover layer (1) of metal, a second 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 brought together and are integrally bonded to each other by the application of pressure and/or heat. The method is characterized in that the first metal strip (4) and the second metal strip (5) are each continuously coated with an adhesion promoter in a pretreatment line (V) and then wound and that the first metal strip (4), the second metal strip (5), and the plastic web (6) are then brought together in a laminating line that is separate from the pretreatment line (L) and are continuously bonded to each other by the application of pressure and heat in order to form a composite web.

Claims

1. A method of making composite webs or composite 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 that is between the outer layers and integrally joined therewith, the method comprising the steps of: supplying a first metal strip for the first outer layer, a second metal strip for the second outer layer, and at least one plastic web for the core layer, continuously coating each of the first and the second metal strips with an adhesion promoter on a pretreatment line and and thereafter winding up each of the coated first and second metal strips, unwinding and then bringing together the first and the second coated metal strips and the plastic web in a lamination line that is separate from the pretreatment line, and thereafter joining the unwound coated strip together with the plastic web continuously under application of pressure and heat to form a composite web.

2. The method according to claim 1, wherein the pretreatment line is operated at a higher speed than the lamination line.

3. The method according to claim 1, further comprising the step of: cleaning each the metal strips in the pretreatment line.

4. The method according to claim 1, further comprising the step of: straightening the metal strips in the pretreatment line by stretch-bend straightening and/or lengthening.

5. The method according to claim 1, further comprising the step of: heating or drying the metal strips in the pretreatment line after coating with the adhesion promoter.

6. An apparatus for making composite strip or sheets that consist of at least one first outer layer of metal, one second outer layer of metal, and one core layer of plastic that is between the outer layers and integrally joined therewith, the apparatus comprising: a pretreatment line for unwinding, then coating each of the first and second metal strips and for thereafter winding up each of the first and second metal strips; and a lamination line separate from the pretreatment line and having a first unwinder for unwinding the coated first metal strip, a second unwinder for unwinding the coated second metal strip, a third unwinder for the plastic web, and a joiner that brings the unwound and coated first and second metal strips together with interposition of the unwound plastic web.

7. The apparatus according to claim 6, wherein the joiner has: a first laminator with which the plastic web can be brought together with the first metal strip, and a second laminator with which the second metal strip can be brought together with the plastic web that is on the first metal strip.

8. The apparatus according to claim 6, wherein the joiner has: a preheater for the first metal strip, a preheater for the second metal strip, a preheater for the plastic web, and/or a post-heater for the first metal strip and the plastic web thereon.

9. The apparatus according to claim 6, further comprising: a heater and/or press downstream of the joiner.

10. The apparatus according to claim 6, wherein the coater is a roller coater with at least one application roller and one support roller.

11. The apparatus according to claim 6, wherein the pretreatment line has at least one cleaner for the strips.

12. The apparatus according to claim 6, wherein the pretreatment line has a stretch-bend straightener.

13. The apparatus according to claim 6, further comprising: a skin-pass mill for temper-rolling in the pretreatment line.

14. The apparatus according to claim 6, wherein the pretreatment line is operated at a workpiece throughput speed that is at least twice that of the lamination line.

Description

[0038] The invention is explained in further detail below with reference to a schematic drawing that illustrates only one embodiment.

[0039] FIG. 1 is a simplified cross section through a composite strip or sheet,

[0040] FIG. 2 is a highly simplified, schematic view of an apparatus for manufacturing a composite strip with a pretreatment line on the one hand and a separate lamination line on the other hand,

[0041] FIG. 3 is a simplified view of the pretreatment line of the apparatus according to FIG. 1, and

[0042] FIG. 4 is a simplified schematic view of the lamination line of the apparatus according to FIG. 1.

[0043] With the apparatus shown in FIGS. 2 to 4, composite strip or sheets can be produced that are made of at least one lower outer layer 1 of metal, one upper outer layer 2 of metal, and 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 (see FIG. 1).

[0044] As shown in FIG. 2, in order to produce composite strips as in FIG. 1, a first metal strip 4 for the lower outer layer and a second metal strip 5 for the upper outer layer and a plastic web 6 for the core layer are supplied to the apparatus. 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. The metal strips 4 and 5 are thus provided as a starting product for the process according to the invention for manufacturing composite strips. They are metal strips made of steel, for example, such as electrolytically galvanized and optionally oiled steel strips. Alternatively, however, strips of aluminum or other metals can also be used.

[0045] According to the invention, composite strips are manufactured from such steel strips 4 and 5 in an apparatus that is composed of two separate, continuously operating lines, namely a pretreatment line V on the one hand and a lamination line L on the other hand (see FIG. 2).

[0046] Both the first metal strip 4 and the second metal strip 5 are each coated on one side with an adhesion promoter on a (single) continuously operating pretreatment line V and then wound up.

[0047] The (pretreated and precoated) first metal strip 4 and the (pretreated and precoated) second metal strip 5 and the plastic web 6 are subsequently brought together in a continuously operating lamination line L separate from the pretreatment line V and joined together continuously under application of pressure and heat to form a composite strip. The pretreatment line V is shown in detail in FIG. 3, and the lamination line L, which is separate therefrom, is shown in detail in FIG. 4.

[0048] The pretreatment line V has at least one unwinder 7 for the first metal strip 4 and the second metal strip 5, at least one coater 8 for coating the metal strips 4 and 5 with an adhesion promoter, and a winding device 9.

[0049] In this way, pretreated and/or precoated metal strips 4 and 5 that are wound onto coils are available for the subsequent lamination process.

[0050] The lamination line L in turn has a first unwinder 10 for the first metal strip 4, a second unwinder 11 for the second metal strip 5, and an unwinder 12 for the plastic web 6. Moreover, a winder 13 for the finished composite web can be provided, for example. Furthermore, the lamination line L has a joiner 14 in which the metal strips 4 and 5 are brought together with interposition of the plastic web 6. The joiner 14 is then followed by a heater and/or press 15 in which the bond between the outer sheets 4 and 5 and the sandwiched plastic web 6 is created and/or completed.

[0051] Of particular importance according to the invention is the fact that, as shown in FIG. 2, the pretreatment on the one hand and the lamination and/or covering on the other hand are carried out on separate lines, with these separate lines then each operating continuously. Provision is made that only a single pretreatment line V that pretreats both the lower outer sheets 4 and the upper outer sheets 5 is associated with the lamination line L. It is advantageous in this regard if the pretreatment line V operates at a substantially higher speed than the lamination line L, preferably at (approximately) twice the speed, so that the pretreatment line, at twice the speed, is adapted to the capacity of the lamination line, enabling both first metal strips 4 and second metal strips 5 to be provided in sufficient quantity by the pretreatment line V.

[0052] The construction and functionality of the pretreatment line V can be clarified on the basis of FIG. 3:

[0053] The metal strips 4 and 5 are unwound by the unwinder 7 and initially aligned in a first straightener 16. The purpose of this first straightener 16 (immediately) downstream of the unwinder 7 is to correct curvature, particularly to eliminate curvatures that are created by winding up of the strips. Various processing machines can follow that are not shown in detail (scissors, scrap disposal, drives, staplers, side punches, etc.). The metal strips 4 and 5 then pass through a first cleaner and/or precleaner 17 and, optionally, a strip accumulator 18. The first cleaner 17 is followed by a second cleaner 19 that can be a stretch-bend straightener for improving the flatness of the strip. This second straightener 19 is followed by a second cleaner 20 and/or post-cleaner. The strip then passes through a dryer 21, for example that can be a hot-air dryer, for example. The above-described coating with an adhesion promoter is then performed with the strip coater 8 that is a roll coater or roller coater here and has at least one application roller 8a and one support roller 8b. The strip coater 8 is followed by a heater 22 (for example a furnace) and optionally a cooler 23 (for example an air cooler).

[0054] The metal strip 4 and 5 pretreated in this way is then wound up by the winder 9. The pretreated metal strip 4 and 5 is thus provided as a cleaned, straightened strip that has been precoated with adhesion promoter on coils that are then available for the manufacture of the composite strips in the lamination line L.

[0055] The construction and functionality of the lamination line V can be clarified with reference to FIG. 4:

[0056] The lamination line L has a first unwinder 10 for the first metal strip 4 and a second unwinder 11 for the second metal strip 5. The unwinders 10 and 11 can each be optionally followed by respective straightening machines 25 and 26 and, optionally, respective strip accumulators 27 and 28. The first metal strip 4 for the lower outer sheet is preheated in a preheater 29, for example a furnace. This preheated lower metal strip 4 is subsequently brought together with the plastic web 6. To achieve this, the plastic web 6 is unwound by the unwinder 12 and also preheated in a preheater 30 and then brought together with the first metal strip 4, particularly in a first laminater 31 that can be a roller arrangement or calender. This first laminater 31 is followed by a post-heater 32, for example a furnace, with which the temperature of the first metal strip and the plastic web 6 thereon are further controlled.

[0057] The second metal strip 5 is also preheated in a preheater 33 and then brought together in a second laminater 34 with the first metal strip 4 and the plastic web 6 thereon. This second laminater 34 can again be a roller arrangement or calender. The second laminater 34 is followed by the heater and press 15 that has at least one heater 35, for example a furnace, and a press 36 and optionally an additional heater 37 and an additional press 38. Moreover, coolers 39, 40 are then preferably provided with which the finished composite strip is cooled before it is subsequently wound by the winding device 13 or optionally subdivided right away into sheets in a suitable apparatus.

[0058] Moreover, FIG. 4 shows that the lamination line is equipped with a strip joiner 41 that joins the two metal strips 4 and 5 together locally during startup of the lamination line L (in addition to) and independently of the integral connection via the plastic web. For this purpose, the strip joiner 41 makes a punched or stapled connection, for example, or is a clincher or as a welder or the like. Preferably, the two metal strips 4 and 5 are joined together locally with one another during the startup process without the plastic web 6. This local strip connection at the leading end of a strip prevents delamination at the leading end of the strip as it continues to pass through the following apparatus components, particularly the heaters and presses.

[0059] During startup of the lamination line L, the first (lower) metal strip 4 is preferably drawn completely into the lamination line and pulled through the lamination line L by the winding device 13. The plastic web 6 is laminated onto the lower metal strip 4 in the first laminater 31. Before the first metal strip with the plastic web 6 thereon then reaches the second laminater 34, the lower metal strip 4 is stopped. Now the upper metal strip 5 is fed via a drive 42 so that the upper metal strip 42 is placed onto the lower metal strip 4 without a plastic web. The upper metal strip 5 is guided into the vicinity of the strip joiner 41 where the metal strips 4 and 5 can then be joined together, for example by stapling, clinching, welding, gluing, or the like. The strip connection is thus created near the leading end of one of the strips, the upper strip 5 in this embodiment. The drive 42 can then be opened, and the lower metal strip 4 is then pulled with the upper metal strip 5 secured thereto through the apparatus, so that the plastic web 6 also reaches the second laminater 34 and the continuous manufacturing process can begin.

[0060] By virtue of the heaters provided in the described lamination line L, the manufacturing process can be varied and particularly adapted to the characteristics of the plastic web being used, particularly to its melting point. A plastic web or plastic film is thus preferably used that has a melting point of greater than 200 C., for example about 220 C., that can have a recrystallization temperature of about 190 C. to 200 C.

[0061] The heater 29 raises a temperature of the first metal strip 4 to above the melting point of the plastic web, for example to a temperature greater than 200 C., for example about 250 C. The plastic web 6 is also preheated in the heater 30, but to a temperature substantially below the melting point of the plastic web, for example to a temperature from 25 C. to 100 C. The composite of first metal strip 4 and plastic web 6 is subsequently heated together in the furnace 32, particularly to a temperature near the melting point of the plastic web, for example to a temperature between 200 C. and 250 C., for example about 220 C. to 230 C.

[0062] The second metal strip 5 is also heated in the heater 33 to a temperature above the melting point of the plastic web, for example to a temperature above 200 C., for example about 250 C.

[0063] In the second laminater 34, the metal strips 4 and 5 and the plastic web 6 thus have a temperature near the melting point of the plastic web. Subsequently, there is additional heating in the heater 35, particularly preferably to temperatures above the melting point, for example temperatures greater than 220 C., for example about 250 C. At this temperature, the strips are joined together with interposition of the liquefied plastic web in the press 36. Additional adjustment of the temperature is effected in the heater 37, and further joining occurs in the press 38 at temperatures below the melting point of the plastic web. Cooling and consolidation is then performed in steps in the above-mentioned coolers.

[0064] It will readily be understood that the described temperature control is cited merely for the sake of example and is adapted according to the characteristics of the plastic web used.