HONEYCOMB CORE

Abstract: Honeycomb structure (1) built from a package of strips of cellulose material adhered to one another, each strip on the one side being adhered at locations to the adjacent strip on that side, which locations lie offset with regard to the locations where the strip concerned is adhered at the opposite side to the adjacent strip on that side, so that when pulling away the strips from each other to bring the strip package into an expanded state, portions of the adjacent strips form the sides of polygonal cells, the outermost first sides (18) of the cells that are situated on the edges of the strip package which are enlarged during expansion having a combined length which is shorter than the combined length of the opposite second sides of those cells.

Description: Honeycomb core The invention relates to a honeycomb core and to panel- shaped assemblies in which such a core has been accommodated. Such a honeycomb core usually is a structure built from a package of strips of cellulose material adhered to one another, each strip on the one side being adhered at locations to the adjacent strip on that side, which locations lie offset with regard to the locations where the strip concerned is adhered at the opposite side to the adjacent strip on that side, so that when pulling away the strips from each other to bring the strip package into an expanded state, portions of the adjacent strips form the sides of polygonal cells. Such honeycomb cores are often used in a sandwich panel, in which on one side or on both sides of the core which has been brought in pulled-out or expanded state, a plate is attached, for instance by means of gluing. The plates can - like the core - be of cellulose material, but it is also known to accommodate a cellulose core between two plasterboards . Such a panel is used in building industry. When making the cores, plates of core material are provided with glue tracks or glue strips and after that are pressed onto each other, after which the stack of plates is cut into packages of strips, which are later pulled out to form a core. The glue tracks or glue strips are arranged at mutually equal distances. A result of this is that the pulled-out longitudinal edges of the core have a zigzag shape. The side of the sandwich panel made with that core then offers a sloppy sight, which is disadvantageous for the saleability of those panels. Moreover, as a result of the zigzag shape there are open cells in the longitudinal edge area, because of which the filling or occupation of the panel with core material is not optimal in that area. It is an object of the invention to improve on this and to that end provides the measure that the outermost first sides of the cells that are situated on the edges of the strip package which are enlarged during expansion, have a combined length which is shorter than the combined length of the opposite, second sides of those cells. In this way the longitudinal edge with an otherwise usual shape of the more inner situated cells of the core have a more straight shape . Preferably, in the expanded state, the first sides are at least almost in line with each other. In this way a means is provided which forms an upper limit for the extent in which the core may be pulled out . In that way in the maximum pulled-out state, the core can be connected to the plates of the sandwich panel, in which, because of its extended course, the longitudinal edge may come to lie close to the plate edges. The cores known up until now, cannot be kept extended to such an extent , because the cells would then be deformed too much. From another aspect the invention provides a honeycomb structure built from a package of strips adhered to each other in particular made of cellulose material, wherein in the expanded state of the package of strips the cells which are situated on the expanded edges approximately form a polygon with an uneven number of sides, whereas the cells lying within there form a polygon with an even number of sides. The invention further provides a method for gluing plates for forming honeycomb cores, the distance between the outer glue strips and the adjacent glue strips lying within there, being shorter than the distance between the other glue tracks . The invention will now be elucidated on the basis of an exemplary embodiment which is shown in the attached drawing, in which: Figure 1 shows a sandwich panel with a honeycomb core in a usual embodiment; Figure 2 shows a sandwich panel with honeycomb core according to the invention; and Figure 3 shows a partial cross-section of the sandwich panel of figure 2. The sandwich panel 1 in figure 1, which is part of the state of the art, comprises a cover plate 2 made of plaster material and a cover plate 3 made of plaster material. In between them a honeycomb-shaped core 4 is accommodated, which is built from strips 5 of, for instance, cellulose material, such a cardboard. The strips 5 are glued together at offset locations, so that after pulling out in the directions A the indicated honeycomb structure is realized. The honeycomb cells 6 have a diameter Dl in the extended direction and in this case form hexagons, in which the sides 7, situated transverse to the extended- or longitudinal direction of the core, are attached to each other. This attaching to each other can take place by means of a glue layer or glue strip 10 extending over the entire side or a portion of it . The cells 6 here all have almost the same shape and dimensions. This also goes for the cells on the left longitudinal edge as seen in the drawing. The "first" sides 8 have the same dimensions as the "second" sides 9. In each cell the sides 8 are held together by projecting strip portions 7' which are adhered to each other. When pulling out the core (from a package shape) in the direction A care should be taken that the cells 6 get the desired dimensions. When subsequently placing the core 4 on the plaster cover plate 3 it can hardly be prevented that the longitudinal edges have a more or less curved or winding course. Because of this the longitudinal edge of the core 4 should be kept at a sufficient distance from the edges of the plasterboards 2 and 3. This means that either the transverse dimension of the core 4 should be kept sufficiently small or the transverse dimension of the plasterboards 2 and 3 should be taken sufficiently large. A special thing about the core 14 of the panel 11 according to the invention, shown in figure 2, is that the cells which are situated along the longitudinal edge, that is 16', have other dimensions or shapes than the other cells 16. It will be understood that the opposite lon- gitudinal edge, which is not shown, has the same design as the longitudinal edge which is shown. The core 14 is built from strips 15 , which are adhered to each other with their sides 17. Because the distance between the two outer glue strips 20, when applying the glue, is smaller that the mutual distance of the other glue strips 20, the "first" sides 18 are smaller than the "second" sides 19 of the cells 16' . The "first" sides 18 have a combined length which equals Dl . The "first" sides 18 are held together by transversely projecting strip portions 17' that are adhered to each other. The cells 16' are pentagonal and have a side which is directed in the extension directions A. When extending in the directions A these sides form an upper limit for the distance over which the core 4 can be pulled out in the directions A. In this way the core is dimensionally stable when a certain pulling force is maintained and the longitudinal edges will have a more extended course. In this way the longitudinal edge of the core can be laid more closely to the longitudinal edges of the plasterboards 12 and 13.

Claims: Clai s 1. Honeycomb structure built from a package of strips of cellulose material adhered to one another, each strip on the one side being adhered at locations to the adjacent strip on that side, which locations lie offset with regard to the locations where the strip concerned is adhered at the opposite side to the adjacent strip on that side, so that when pulling away the strips from each other to bring the strip package into an expanded state, portions of the adjacent strips form the sides of polygonal cells, the outermost first sides of the cells that are situated on the edges of the strip package which are enlarged during expansion having a combined length which is shorter than the combined length of the opposite second sides of those cells . 2. Honeycomb structure according to claim 1, in which in the expanded state the first sides are at least almost in line with each other. 3. Honeycomb assembly with a core in the shape of a honeycomb structure according to claim 1 or 2 in the expanded state and two panels arranged on both its sides. 4. Honeycomb assembly according to claim 3, at least one of the panels being a plaster board. 5. Honeycomb structure according to any one of the preceding claims, the first sides of the cells situated on the longitudinal edges having a combined length which equals the diameter of the cells, measured in the extended direction of the core. 6. Honeycomb structure built from a package of strips adhered to each other in particular made of cellulose material, wherein in the expanded state of the package of strips the cells which are situated on the expanded edges approximately forming a polygon with an uneven number of sides, whereas the cells lying within there form a polygon with an even number of sides . 7. Method for gluing plates for forming honeycomb cores, the distance between the outer glue strips and the adjacent glue strips lying within there being shorter than the distance between the other glue tracks. 8. Honeycomb structure comprising one or more of the characterizing measures described in the description and/or shown in the drawings . 9. Honeycomb assembly, comprising one or more of the characterizing measures described in the description and/or shown in the drawings.

Inventors: NAUTA AUKE JOHANNES, NAUTA, AUKE, JOHANNES
Applicants: BESIN BV, NAUTA AUKE JOHANNES, BESIN B.V., NAUTA, AUKE, JOHANNES
Application year: 1998
Main classification: B31D3
IPC codes: B31D3