NL7908336A - METHOD AND APPARATUS FOR JOINING PLATES OF EXPANDED THERMOPLASTIC RESIN - Google Patents

Description

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Method and device for joining plates of expanded thermoplastic resin.

The invention relates to a method of joining a number of plates of expanded thermoplastic resin together into a multilayer panel, to a device for carrying out this method and to the so-formed panels.

In the treatment of thermoplastic resins it is known to manufacture sheets or panels which are of a layer and have a selected thickness, the correct method depending on the purpose of the final product. The method which has hitherto been most widely used can only be used to produce products of relatively high density. In practice, therefore, such a method must be carried out at relatively high temperatures, which in turn means that the extruded expanded panels must be subjected to long-term calibration and cowing treatments before they can be used.

15. Panels manufactured in this way additionally require pears at a controlled temperature, and in view of the voluminous nature of the material this entails the use of large spaces. This has serious disadvantages, both with regard to business operations and the cost price.

The invention provides a method and an apparatus which make it possible to manufacture panels of expanded thermoplastic material, starting from sheets or strips, which sheets or strips have been previously extruded and tempered.

The invention provides a method of joining two pre-formed, tempered sheets of expanded thermoplastic resin of a selected density together, then passing each of the sheets at a controlled rate through an oven, whereby the interior is maintained at a controlled temperature. the sheets expand to a selected thickness, heating at least the opposing surfaces of adjacent sheets near the oven exit, moving the sheets together until they come into contact, at which touch fuse or * 79 0 8 3 36 t '. * -2- * Welding occurs from the opposed abandoned surfaces, draining the thus-joined sheets from the oven through a single outlet and then draining them through a calibration and cooling station. The sheets may be made of a fibrous material, while the fibers may be statistically distributed or parallel to each other.

The invention also provides a panel of extruded expanded thermoplastic resin made by the above method, which panel has a thickness equal to the sum of the thicknesses of the sheets from which it is made after expansion of the sheets and a density has less than the density of the sheets for the oven treatment, but equal to the density of those sheets after separate expansion.

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The invention also provides an apparatus for joining two or more pre-formed sheets of tempered thermoplastic resin together, said apparatus comprising an oven with a heating chamber, said oven having multiple entries, one for each sheet and in an opposite wall of the oven a single outlet for the interconnected sheets, means for continuously carrying and passing each sheet individually through the oven, first heat sources to maintain a controlled temperature within said chamber so that the sheets can expand until they reach a . selected densities, feeding sheets to one another and laying them against each other, second heat sources to further heat at least the opposing surfaces of post-fabric sheets to the melting point of the thermoplastic material, means to placing these further heated portions of adjacent sheets together, fusing or welding the sheets together and means for caulking and cooling the sheets thus joined together.

This makes it possible to produce multilayer panels at relatively low temperatures, with a density less than that of the individual sheets or strips used as the starting material, while this density is f 790 83 36 t * 3-kieiner is then the density that can be obtained when a panel is manufactured as a single layer of equal thickness.

Moreover, the method of the invention makes it unnecessary to temper the panels obtained, thereby reducing production costs and increasing production speed.

The invention is further elucidated with reference to the drawing.

Fig. 1 is a schematic side view of a device according to the invention.

FIG. 2 shows a section of the device in section.

Fig. 3 is a cross section through the obtained composite panel.

The drawing shows an oven used to simultaneously heat two or more sheets 2 of expanded thermoplastic material to be bonded together, and a calibration and cooling station 3 for the sheets after they are bonded together and a station 4 to cut and print the formed web into panels.

The oven 1 comprises a chamber 5 in which supporting and transported d-20 parts are arranged for each sheet, the transport means enabling it to continuously feed each individual sheet 2 through the oven. These transport means can consist, as shown in the drawing, of rollers 6, which define a path for the sheets.

However, the transport means can also consist of endless belts 25 or chains or any other devices suitable for transporting the sheets 2 individually and separately.

The support and transport means 6 correspond to the inlet openings 7 in a wall of the oven 1. The sheets 2 are extruded and tempered and then wound on rolls R. In the method according to the invention, the sheets are unwound from the rolls R and they enter the oven 1 through the openings 7. As the drawing shows, these openings 7 are arranged in one of the end walls of the oven 1.

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It is to be noted, however, that the sheets of expanded material can be fed horizontally as well as vertically, without this adversely affecting the treatment. The guide members 6 for the sheets are then placed correspondingly.

In both cases, in the oven wall opposite the wall with the inlet openings 7, a single outlet 8 is provided for all sheets 2. Inside the oven 1, at least a pair of adjustable guide rollers 9 is arranged near the exit 8 to feed the sheets 2 towards each other and place them against each other, so that they touch each other »- 1 o.

To extrude the sheets of extruded expanded material 2 as they pass through the oven 1. heating means are arranged between the sheets 2 heating means 10, for example electric resistance heating plates, which heating panels keep the oven temperature at a selected value, so that each individual sheet expands to a selected extent. It will be appreciated that expansion of a sheet will decrease its density.

In the region near the exit 8 of the oven, where the sheets 2 'approach each other on the way to the pair of guide rollers 9, even more heating elements 11 are arranged to heat the opposing surface portions of adjacent sheets to a melting point. This melting allows the adjacent sheets to be glued together or melted while they are fed between the rollers 9. This is always irrespective of whether the surfaces of the sheets are smooth or whether they have been subjected to prior mechanical pretreatment.

As they pass through the oven 1, the sheets 2 can be "treated" at any suitable temperature for a selected time. During this treatment they undergo an expansion above the expansion which they had previously undergone, so that it becomes possible to reduce the density of the sheet to a selected value. After this additional expansion, the surfaces to be glued together are exposed to the influence of the heating elements 790 83 36 -5-elements 11, so that at least hm surface parts are heated to their melting point, when the sheets are thus moved between the guide rolls 1 fed, the sheets are welded together to form a single panel 2Q, which consists of a number of 5 layers corresponding to the number of sheets while the thickness of the panel is equal to the. the sum of the thickness of the sheets used and the density of the panel depends on the densities of the sheets used.

Depending on the nature of the thermoplastic material 10 from which the sheets are formed, the temperature in the oven may vary from 1 ° C to 200 ° C and the speed at which the sheets are fed through the oven may vary from U-15 now. these parameters make it possible to reduce the density from 60-70 g / l in the starting material to 22 g / l in the finished product.

In other words, the method and the device according to the invention make it possible to considerably increase the volume of the starting material, without this entailing any significant technical difficulties.

The multi-layered panel formed is then passed to and through a calibration and cooling ion 3, in which the physical properties of the final product are fixed. As shown in Fig. 2, this station 3 comprises two sets of adjustable rollers 12 which face each other so that a path is defined between them through which the panel 20 must pass. During its passage between the rollers, the sheet is cooled, for example by air supplied through openings 13 provided below and above the rollers 12 and / or by water.

After cooling, the product is ready to be cut to size and possibly printed. This can be carried out in the treatment station b, if used.

With the aforementioned method, it is possible to form panels from arbitrarily extruded and expanded thermoplastic material, while the sheets from which the panel is formed can also be produced if desired. still additives may include "such as flame retardant materials and dyes. When the sheets are made of fibrous material, the fibers may be oriented or statistically oriented.

It is also possible to apply a plastic laminate or a plain paper or bituminized paper to one or both outer surfaces of the final product during the process to obtain a final product having the desired structure and properties. .

Furthermore, according to the invention, a multilayer product is obtained in a simple and inexpensive manner with a density, a thermal insulation value, mechanical strength, and a water absorption, a. resistance to diffusion of water vapor therethrough and dimensional stability equivalent to similar products obtained directly by extrusion as a Sên layer structure.

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Claims (13)

3. Method of making two or more pre-formed, tempered sheets. Expanding expanded thermoplastic resin of selected density with each other, characterized in that the different sheets are each passed at a controlled speed through an oven, the interior of which is kept at a controlled temperature, to expand the sheets there to a selected thickness, near the exit of the oven, to heat at least the opposing surfaces of neighboring sheets, moving the sheets together until they are on top of each other, thereby fusing or welding the 10 opposed heated surfaces together, drain the bonded layers out of the oven through an outlet and pass them to and through a calibration and cooling station. 2. A method according to claim 1, characterized in that the bonded sheets are printed and cut to size after they have been passed through the calibration and cooling station. A method according to claim 1 or 2, characterized in that the thermoplastic material is fibrous, and the fibers are oriented parallel to each other. h. Method according to claim 1 or 2, characterized in that the thermoplastic material is fibrous and the fibers are statistically oriented. 5. Method according to claims 1 to ¼, characterized in that during the passage of the thermoplastic sheets through the oven sheets of plastic, laminates, paper or bitumen-coated paper are applied to the panel. 6. Method according to claims 1-5 substantially as described above. 7. Panel of extruded, expanded thermoplastic resin, manufactured by the method of claims 1-6, which. The panel has a thickness equal to the sum of the thickness of the sheets, t 790 8 3 36 Λ from which it is made after expansion of those sheets and a density less than the density of the sheets before the treatment in the oven, but - equal to the density of those sheets after expansion., 8. Device for connecting two or more preformed and tempered sheets of thermoplastic resin, characterized in that the device is provided with an oven, which comprises a heating chamber, which oven has a number of entrances, namely one for each sheet and in the opposite wall of the oven a single outlet for the interconnected. sheets, means to support and pass the sheets separately and continuously, through the furnace, first heat sources to maintain a controlled temperature within the furnace chamber and expand the sheets to the desired density, guide members around the sheets moving and laying on top of each other, a second set of heat sources to further heat at least the opposing surface portions of adjacent sheets to the melting point of the thermoplastic material, means to heat these further heated portions of adjacent sheets together to be melted or welded together and means to calibrate and cool the sheets thus joined together. 9. Device as claimed in claim 8, characterized in that the device is also provided with means for printing the interconnected sheets and with means for cutting the interconnected sheets to the desired size. ' 10. Device as claimed in claims 8 or 9, characterized in that the means for transporting the sheets consist of opposed pairs of rollers, conveyor belts or endless chains. "," 11. Device according to claims 8-10, characterized in that the guide members comprise a pair of adjustable rollers, which are arranged near the exit of the oven. 12. Device according to claims 8-11, characterized in that the heat sources are electrically powered. • 790 83 36 T "£ * T 13. Device as claimed in claims 8--32, characterized in that the calibration means comprise two sets of opposed rollers, between which a cock for the interrelated sheets is defined. 5 1 ^. Device according to claim 13, characterized in that the cooling means comprise air diffusion nozzles, which are arranged under and above the calibrating means. 15. Device for adhering two or more sheets of thermoplastic resin, which is constructed and arranged to operate 10 substantially as described above and illustrated in the accompanying drawing. 790 83 36