DE2730997A1 - CORRUGATED BOARD STRUCTURE - Google Patents

Description

PAV E NTA N WA LT Ξ A. GRÜNECKER

tr ν-Md

H. KINKELDEY

Λ -7 Q Π QQ 7 ^W · STOCKMAlR ^ f, / »JU ij \ ί 'mm wc« nx

K. SCHUMANN

OR «β * NAT. - ΟΗ, ΊΗΙΙ

P. H. JAKOB G. BEZOLD

8 MUNICH

MAXIMILIAN »TRAS» K * »

July 8, 1977 P 11 793

Nissan Motor Company, Limited

No. 2, Takara-machi, Kanagawa-ku, Yokohama City, Japan

Corrugated cardboard structure

The invention relates to a corrugated or ribbed fiber board or hard cardboard structure, which is to be referred to as "corrugated cardboard structure" in the following; in particular relates the invention relates to such a corrugated cardboard structure with a curved cross-section.

The invention also relates to a method and an apparatus for producing such a corrugated cardboard structure from a flat blank.

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TELEPHONE (OBO) 99 9ββ9

TELEX Ο8-2Ο38Ο

TELEGRAMS MONAPTH

TELECOPER

Such a corrugated cardboard structure can be used in a wide variety of applications, in particular wherever thermal and / or sound insulation and / or damping of mechanical vibrations are required; a special one A suitable area of application is interior cladding for walls, floors and ceilings of residential or office buildings, or Facing or cladding, interior fittings or decorations or edges and intermediate layers for various Structural elements of automobiles, ships, boats or airplanes; this versatile application are particularly due to the rigidity, the excellent heat and sound absorption, the possibility of manufacturing lighter constructions, the low manufacturing and installation costs and, among other things, the possible adaptation attributed to surfaces with compound curvatures.

When a corrugated cardboard structure is to be used as one of the materials mentioned above, and when the part on which the corrugated cardboard structure to be attached is a curved one

Surface, the corrugated cardboard must be bent or curved locally, i.e. at certain points, so that it that it corresponds to the curved surface of the part. Corrugated cardboard to be used in such an element is therefore deformed beforehand so that it has a curved section; for this purpose a driven hot press or hot press used. For example, if the corrugated cardboard structure is deformed so that if there is a sharp bend, a furrow-like or burr-like fold or a kink along the axis can be used around which the corrugated cardboard structure is bid or curved. However, such a fold is affecting the appearance and, accordingly, the commercial value of a

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such a product negative. A corrugated cardboard structure made with such a fold can be made with an additional Sheet or coating overlying the folded area of the structure so that the The crease is obscured by the sheet or coating. The additional sheet or coating used for this purpose must have a thickness sufficient to cover the depth or height of the furrow-like or ridge-like To pick up the fold in the corrugated cardboard. However, such a thick web would make the resulting corrugated cardboard construction unwieldy and therefore usable only in certain cases which further adversely affects the commercial value of the item. With the present invention this Problems are avoided.

It is therefore an essential aim of the present invention to provide an improved corrugated cardboard structure having at least one three-dimensionally curved region, the is free of wrinkles or kinks in the curved area.

Furthermore, a method for producing such a curved corrugated cardboard structure from an initially flat one Blank can be proposed.

Finally, it is an object of the present invention to provide an apparatus which can be used for performing the Process is suitable.

According to an essential aspect of the present invention, one is at least partially and according to one preferred Embodiment three-dimensionally curved corrugated cardboard structure with at least one pair of spaced apart, parallel cover plates or decking boards or Cardboard panels and with at least one corrugated intermediate

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Plate or intermediate panel or intermediate cardboard created, which or which is arranged between the cover plates and attached to the upper Ends of its webs or ribs is connected to the respective inner surfaces of the cover plates, these Corrugated cardboard structure is characterized by at least one area with a curved cross section and a thickness that is smaller than the thickness of the remaining area of the corrugated cardboard structure.

According to a further aspect of the present invention, a method for producing an at least partially and According to a preferred embodiment, a three-dimensionally curved corrugated cardboard structure made from a blank that is initially flat with at least two spaced apart, parallel cover plates and at least one corrugated Created intermediate plate, which is arranged between the cover plates and at the upper ends of their ribs with the respective inner surfaces of the cover plates, wherein at least a predetermined area of the blank is inelastically compressed to a thickness which is less than the thickness of the rest of the region of the blank, and wherein the predetermined area is deformed inelastically so that it has a curved cross-section.

According to a further essential aspect of the present invention, finally, there is also a device for generating an at least partially and, according to a preferred embodiment, three-dimensionally curved corrugated cardboard structure from a blank initially flat with at least two parallel cover plates arranged at a distance from one another and at least one corrugated intermediate layer is proposed, which is arranged between the cover plates and is connected at the upper ends of its webs to the respective inner surfaces of the cover plates, wherein

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this device has two rigid clamping parts, one of which one has a partially recessed wall area and the other has a partially protruding wall area, further determined the parts of the clergy in and out of each other in advance Relative positions can be moved in which their respective, partially recessed or protruding wall areas are very close facing each other and face-to-face and between a clearance form with a shape that corresponds to the desired shape of the corrugated cardboard structure to be produced, and the above-mentioned clearance having at least one reduced area having a cross-section that differs from that of remaining portion of the clearance is bent and has a smaller size than the remaining portion of the clearance. After a preferred embodiment, the device with the above The general structure described further comprises heating means for heating each of the clamping members.

According to the present invention, a partially bent corrugated cardboard structure is made from an initially flat blank using two, each correspondingly Recessed and protruding mold blocks made in such a way that they fit the area to be curved Compress the blank; this makes this particular area compared with the rest of the area of the blank made thinner and can be bent without the risk of a crease or crease being formed in the blank.

The disadvantages of the conventional methods of making a curved corrugated cardboard structure and the features and advantages of a curved hardboard according to the present invention Invention and a method and an apparatus for producing such a hardboard structure according to FIG present invention are from the following description

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exercise in connection with the accompanying drawings. In the drawings show:

Fig. 1 is a front view, partly in section, of a representative one Example of a conventional device for producing a curved corrugated cardboard structure an initially flat blank;

2 shows, on an enlarged scale, a cross-section through part of a bent corrugated cardboard structure, which under Using the conventional apparatus shown in Figure 1;

Fig. 3, also on an enlarged scale, a section through the clamping parts or the "male and female" Shapes ", that is, the die and the punch or the corresponding molded parts, which form a part form a preferred embodiment of the device according to the present invention; and

Figure 4 is a view similar to Figure 3 of part of a curved corrugated cardboard structure made using the device has been produced with the clamping parts or mold blocks shown in FIG are.

Before describing the basic principle of the present invention in detail, the conventional techniques should be explained with which a curved corrugated cardboard structure is produced from an initially flat blank.

As can be seen from Figure 1 of the drawings, a conventional one Device for creating a curved corrugated

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cardboard structure by an overpressure type hydraulic heating press 10 formed, so a so-called "upper piston press" (down-stroke press); this hydraulic heating press 10 has a lower, stationary "female" mold block 12, that is to say a die block, and an upper, movable, "male" Form block 14, that is to say a punch block, which is located above the die block 12. The movable patrix or die block 14 is attached to a mold carrier 16 which is attached to the piston of a hydraulic cylinder 18 which in turn is supported on an upper transverse part of a frame structure 20. The frame structure 20 has two spaced, parallel, vertical openings, each of which is vertical guide rails for the mold carrier 16 form; however, these openings are not shown. The upper mold block 14 can therefore be moved vertically on top of the lower, stationary mold block 12 to and from move away from it, which is located under the mold block 14. In the form blocks 12 and 14 are tubes 22 and 24 for circumferential admitted fluid media, the lines 28 and 30 provided with shut-off devices in connection with a source 26 for a hot fluid medium; the line 30 for the movable die block 14 is partially flexible so that it can partially move relative to the source 26 for the hot fluid medium, which is held stationary.

The lower, stationary die block 12 has an upper wall portion which is partially recessed so that therein a cavity or recess 32 is formed which is open at the upper end of the mold block 12 and so shaped is that it corresponds to the desired overall shape of a curved corrugated cardboard structure to be produced. on the other hand the upper, movable punch block 14 has a ridge or a web 34 which protrudes downward and is thus shaped

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is that a certain gap 36 of uniform thickness over its entire area between the partially recessed upper surface of the lower mold block 12 and the partially protruding one upper surface of the upper mold block 14 is formed when the upper mold block 14 is in a predetermined, lowest position is moved over the lower mold block 12, as indicated by the dash-dotted lines. The shapes of the respective upper and lower surfaces of the lower and upper mold blocks 12 and 14, respectively, and accordingly the shape of the space 36 to be formed between the mold blocks 12 and 14 are determined so that they correspond to the desired overall shape and the desired thickness of a curved corrugated cardboard structure made from a blank 38 is to be produced. The blank 38 is formed by a flat, double-faced or single-walled corrugated cardboard structure formed, which consists of two spaced apart, parallel cover plates or cardboard boxes 40 and 40 'and an intermediate layer of cardboard 42, which is arranged between the cover plates 40 and 40' and attached to the upper ends of their webs or "waves" are glued or 'glued to the respective inner surfaces of the cover plates 40 and 40' connected in other ways.

In order to produce a curved corrugated cardboard structure from such a blank 38, the mold blocks 12 and 14 are on heated to an appropriate predetermined temperature by the hot fluid supplied from the hot fluid source 26 circulates through tubes 22 and 24; the blank 38 is then placed on the lower, stationary die block 12 placed, with the upper, movable die block 14 at a suitable distance above the lower mold block 12 is located, as can be seen from the figure. Then the hydraulic cylinder 18 is actuated to the mold carrier 16 after to move down until the upper, movable die block 14

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reaches its predetermined, lowermost position, in which the space 16 between the two mold blocks 12 and 14 is trained. When in this manner the upper mold block is in tight, fitting engagement over the blank 38 with the lower mold block 12 is brought, the blank is clamped firmly and between the respective upper and lower surfaces of the lower and upper mold blocks 12 and 14 are compressed and thereby deformed inelastically to a shape that corresponds to the entire Corresponds to the shape of the space 36 between the mold blocks 12 and 14; significantly contributes to this deformation Heat transferred from the mold blocks to the blank 38. Then the upper, movable mold block 14 is lifted upward away from the lower, stationary mold block 12, and the curved corrugated cardboard structure (not shown), which is now formed on the lower mold block 12, is removed from the mold block 12 so that another work cycle can run.

When the originally flat blank 38 is deformed at certain points in the manner described above, at the same time the cover plate on the inner side of the curved blank subjected to such forces that they are certain Places, so locally, shrunk and can form a furrow or burr-like fold along the axis to which cover plate has been curved or bent; this is shown at 44 in Figure 2, in which the furrow-like Fold can be seen, which is formed in the cover plate 4o. If so with the fold 44 in the cover plate 40 formed curved corrugated cardboard structure is to be used in such a way that the outer surface of the cover plate 40 remains uncovered, this fold 40 affects the appearance and accordingly the commercial value of this Fiber board structure is essential. When an additional sheet or coating is applied to the outer surface of the

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Cover plate 40 is to be applied to cover this fold 44, so must such a sheet or such a coating be thick enough so that this creased area is securely covered and is no longer visible. Such a thick web or one however, such a thick coating makes the resulting corrugated cardboard construction very bulky and unwieldy, so that the commercial value of the product deteriorates even further, as already explained above. It is therefore an essential one The aim of the present invention is to enable the manufacture of a curved corrugated cardboard structure with no Wrinkles or kinks occur in the curved area.

In a method according to the present invention, a blank initially flat is assumed, which consists of at least two parallel cover plates arranged at a distance from one another and at least one intermediate layer of corrugated cardboard which is arranged between the cover plates and connected to them; the or each area of the initially flat blank that is to be curved in a three-dimensional manner is inelastically compressed so that it has a thickness which is less than the thickness of the remaining area of the blank before the particular area is inelastically deformed so that it becomes one has curved cross-section, or according to a preferred embodiment, while the area is inelastically deformed that it has a curved cross-section. The curving portion of the blank to be compressed in a preferred embodiment by providing a mechanical force is applied to the blank in a direction that is substantially perpendicular to the faces of the initial blank. According to a preferred embodiment , the blank is kept in a heated state while it is compressed and deformed.

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Apparatus for practicing this method according to the present invention can be much the same Be constructed and arranged in a manner similar to the conventional apparatus shown in Figure 1; compared with this conventional one Device, however, the device for carrying out the method according to the invention is characterized by clamping parts which are each formed by the die and punch blocks 46 and 48 shown in FIG. In in a manner similar to that of the die and punch blocks 12 and 14 of the conventional apparatus shown in FIG the die bodies or die and punch blocks 46 and 48 of the apparatus of the present invention and protruding wall portions 50 and 52, respectively, which have substantially the same dimensions. These Die or punch blocks 46 and 48 can be moved relative to one another into and out of previously determined relative positions, in which their respective partially omitted or protruding Wall portions 50 and 52 are close to each other and face to face so that there is a gap between them arises, the shape of which corresponds to the desired shape of a curved hardboard structure; part of that structure is shown in FIG. While the partially recessed and protruding wall areas of the die and punch blocks 12 and 14 of the conventional device shown in Figure 1 are shaped so that the space formed between them 36 is uniformly thick over the entire area of the gap 36, the gap 54 is that between the respective partially recessed or protruding wall areas 50 and 52 of the clamping parts or die and punch blocks 46 and 48 of the device according to the present invention is formed so that it has at least one Area 54a, the cross section of which is bent or curved from the remaining area of the intermediate space 54 and its Size smaller than that of the rest of the area of the intermediate

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Space 54, so that the size t of the special area 54a is smaller than the size I _ of the remaining area of the space 54. Figure 4 shows part of an example of a partially bent corrugated cardboard structure made from an initially flat blank that has been clamped between mold blocks 46 and 48 thus formed; How can this figure refer, there These are double-face or single wall corrugated structures arranged in two spaced, parallel cover plates 56 and 56 ^f and a corrugated intermediate layer 58 is disposed between the cover plates 56 and 56 *, and at the upper ends its webs is connected to the respective inner surfaces of the cover plates 56 and 56 '. The hardboard structure also has an area 60 which has been clamped in the tapered area 54a of the space between the mold blocks 46 and 48 and has therefore been curved by the remaining area of the hardboard structure and pressed in or clamped to a thickness which is smaller than that Thickness of the remaining area of the hardboard structure is.

The area 54a of the gap 54 can be stepwise, as shown at 50a, from the remaining area of the Gap 54 are tapered so that the compressed and bent portion 60 of the corrugated cardboard structure, the is made between the mold blocks 46 and 48, stepwise from the remainder of the hardboard structure becomes thinner, as can be seen in FIG. This form of the corrugated cardboard structure is to take advantage of the original one Rigidity of a corrugated cardboard construction useful because the hardboard structure only has a extremely small area is compressed. The gradually tapered portion 54a of the space 54 between Form blocks 46 and 48 form a blunt edge 62

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between the compressed and bent area and the remaining area of the corrugated cardboard structure made between the mold blocks, as shown in FIG. For this reason, the stepped surface should be formed on the mold block which is to be in contact with the surface of the hardboard structure that is left uncovered when the hardboard structure is used. If necessary, the tapered area 54a of the interspace 54 between the shape blocks 46 and 48 can be continuously tapered from the remaining area of the interspace 54, as indicated in FIG. 3 by a dot-dash line. In addition, the tapered region 54a of the space between the mold blocks 46 and 48 and, accordingly, the compressed and curved region 60 of the resulting hardboard structure can be uniformly thick over the entire surface of the regions or continuously thicker or thinner depending on the radii of curvature of the curved cross-sections of the regions. v ^r grounded.

Research has shown that the thickness of the compressed and bent portion 60 of an adhesive fiberboard structure made in accordance with the present invention should be in the range of about 1/9 to about 5/9 the thickness of the remainder of the fibreboard structure. The space 54 between the mold blocks 46 and 48 of the device according to the present invention should therefore be dimensioned so that the size Z. of the tapered area 54a of the gap 54 is in the range from approximately 1/9 to approximately 5/9 the size t ~ of the remaining area of the gap 54. So if the initially flat blank from which a curved corrugated cardboard structure is to be made according to the present invention is 5 mm thick, and if, for example, the size Ij of the gap 54 between the mold blocks 46 and 48 is 4.5 mm, then

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For example, the size I of the tapered portion 54a of the gap 54 may range from about 0.5 mm to about 2.5 mm. According to a particularly expedient embodiment, the thickness of the compressed and bent area 60 of a hardboard structure to be produced according to the present invention is approximately 1/3 the thickness of the remaining area of the hardboard. The size I * of the tapered area 54a of the space 54 between the mold blocks 46 and 48

of the device according to the present invention should therefore be determined as a function of the size L _{7 of} the remaining area of the gap 54.

Thus the inelastic deformation of a corrugated cardboard structure to be produced is ensured, each clamping member or each mold block 46 and 48 of the device according to the present invention Invention be provided with a heating device, such as pipes arranged in the mold blocks for circulation a hot fluid; these pipes are available with a suitable source for the hot fluid medium or a electrical conductor in communication connected to a suitable source of electrical energy; these heating devices are not shown in the figures. The heater is embedded or in each mold block otherwise in heat transfer contact with each mold block to keep the mold blocks at a predetermined temperature to hold when they are in operation.

Although the present invention has been described in connection with a double-faced or single-walled corrugated cardboard structure with two cover plates and a single corrugated cardboard intermediate layer, the basic idea of the present invention can also be applied to other corrugated cardboard structures, for example to corrugated cardboard structures with a single cover plate and a single corrugated cardboard intermediate layer.

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layer, or on a structure with three or more cover plates and two or more corrugated cardboard intermediate layers.

- patent claims -

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Claims (25)

"ε. \ ι Ι" α ν W α ί-τ ε: Claims A. GRÜNECKER Ot \ - WG. H. KINKELDEY οη-Μα W. STOCKMAIR K. SCHUMANN P. H. JAKOB G. BEZOLD 8 MUNICH MAXIMIUANCTRASS P 11 793 1 Λ At least partially curved corrugated cardboard structure with at least two parallel cover plates arranged at a distance and at least one corrugated intermediate layer disposed between the cover plates and at the upper ends of its webs is connected to the respective inner surfaces of the cover plates, marked dur.c at least one area (60) with a curved cross-section and with a thickness which is less than the thickness of the remaining area the corrugated cardboard structure is. 2. Corrugated cardboard structure according to claim 1, characterized in that that the thickness of the area (60) with a curved cross-section tapers gradually from the remaining area. 3. Corrugated cardboard structure according to claim 1, characterized in that the thickness of the area (60) with the curved cross section continuously tapers from the rest of the area. 709882/1129 TILEFON (Οββ) α? 9ββ9 TELEX OS-Q9 38O TELEGRAMS MONAPAT ORIGINAL INSPECTED 4. Corrugated cardboard structure according to one of claims 1 to 3, characterized in that the thickness of the region (60) with the curved cross-section is substantially uniform over the entire surface of the area. 5. Corrugated cardboard structure according to one of claims 1 to 3, characterized in that the thickness of the area (60) changes with the curved cross-section, with the radius of curvature of the curved cross-section. 6. Corrugated cardboard structure according to one of claims 1 to 5, characterized in that the thickness of the region (60) with the curved cross-section is in the range from 1/9 to 5/9 the thickness of the remaining area. 7. Process for producing a v. At least partially curved Corrugated cardboard structure made from a blank initially flat with at least two parallel cover plates arranged at a distance and with at least one corrugated intermediate layer, which is arranged between the cover plates and attached to the upper Ends of their webs is connected to the respective inner surfaces of the cover plates, characterized in that at least a predetermined area of the blank is inelastically compressed to a thickness that is smaller than the thickness of the Remaining area of the blank is, and that the predetermined area is deformed inelastic so that it one has a curved cross-section. 8. The method according to claim 7, characterized in that the blank is compressed simultaneously during the Blank is deformed so that it has a curved cross section. 709882/1129 9. The method according to claim 8, characterized in that the blank is compressed by applying a mechanical force exerting the blank in a direction substantially perpendicular to the faces of the starting blank. 10. The method according to claim 9, characterized in that the blank between two correspondingly shaped, each concave or convex surfaces is pressed together, which are arranged at a distance from each other, so that there is a gap between them, the shape of which corresponds to the desired shape of the corrugated cardboard structure to be produced and which has at least one area which is smaller than the remaining area of the gap, and that the predetermined area of the blank is clamped in the tapered area of the gap. 11. The method according to claim 9, characterized in that the predetermined area of the blank is so compressed becomes that it has a thickness which gradually decreases from the rest of the area. 12. The method according to claim 9, characterized in that the predetermined area of the blank is compressed so that it has a thickness which is continuous from the remaining area reduced. 13. Device according to one of claims 7 to 12, characterized characterized in that the predetermined area of the blank is compressed so that its thickness over the entire Area of the predetermined area is substantially uniform. 709882/1129 14. The method according to any one of claims 7 to 12, characterized in, that the predetermined area of the blank is compressed so that its thickness is continuously with the radius of curvature of the curved cross-section changes. 15. The method according to any one of claims 7 to 14, characterized in that that the predetermined area of the blank is compressed so that its thickness in the range of 1/9 up to 5/9 of the thickness of the remaining area. 16. The method according to any one of claims 7 to 15, characterized in that that the thickness of the predetermined area is approximately 1/3 of the thickness of the initially flat blank amounts to. 17. The method according to any one of claims 7 to 16, characterized in that that the blank is kept heated while the predetermined area of the blank is compressed and is deformed. 18. Device for producing an at least partially curved corrugated cardboard structure from a blank that is initially flat with at least two spaced, parallel cover plates and at least one corrugated intermediate layer, which are arranged between the cover plates and at the upper ends of their webs with the respective inner surfaces of the cover plates is connected, characterized by two rigid clamping parts (46, 48), one of which is partially recessed Wall area (50) and the other has a partially protruding wall area (52), wherein the Kienunteile (46, 48) can be moved relative to one another into and out of previously determined relative positions in which their respective partial recessed and protruding wall areas (50.52) 709882/112 « are close together and face-to-face and between a gap (54) is formed with a shape which corresponds to the desired shape of the corrugated cardboard structure to be produced and wherein the gap (54) has at least one tapered region the cross-section of which is different from the rest Area of the gap (54) is bent, and which has a smaller size than the remaining area. 19. The device according to claim 18, characterized in that that the tapered area of the interspace (54) is gradually tapered from the remaining area of the interspace (54). 20. Apparatus according to claim 18, characterized in that that the tapered area of the interspace (54) tapers continuously from the remaining area of the interspace (54) is. 21. Device according to one of claims 18 to 20, characterized in that the tapered region of the space (54) is substantially uniform in size over the entire area of the tapered area. 22. Device according to one of claims 18 to 20, characterized in that the tapered region of the space (54) has a size which changes with the radius of curvature of the cross section of the tapered region. 23. Device according to one of claims 18 to 22, characterized in that the tapered region of the intermediate space (54) has a size which is in the range of between 1/9 and 5/9 the size of the remaining area of the gap (54). 709882/1129 24. The device according to claim 23, characterized in that the size of the tapered region of the intermediate space (54) is approximately 1/3 the size of the remaining area of the gap (54). 25. Device according to one of claims 18 to 24, characterized in that by a heater which keeps each clamping member (46, 48) heated when the clamping members (46, 48) are in operation are. 709882/1129