TANK FORMED FROM PANELS OF COMPOSITE MATERIAL

Abstract

A tank is formed from one or more panels fastened together edge to edge to form a rectangular tank or one or more curved panels defining a cylindrical wall and a circular end wall to form a cylindrical tank. The panels are composite and formed from a honeycomb core panel with a foam material filling the tubular cells and a fibrous reinforcing cover sheets extending over the top and bottom of the panel. The cover sheets are filled with a set resin material which extends into the porous fibrous material of the walls of the core panel so as to form an integral structure of the resin extending between the walls and the sheets.

Description

BACKGROUND OF THE INVENTION

A number of prior proposals have been made for manufacturing a composite core panel formed from a honeycomb panel formed with tubular cells at right angles to the panel where the panel is filled with a reinforcing foam extending through the cells so as to provide an enhanced compression strength of the core in a direction longitudinally of the cells. This strength is commonly significantly greater than the compression strength of the core and the foam separately. The core panel is then covered on top and bottom by reinforcing sheets of a fibrous reinforcing material which are then resin filled by a resin impregnation process, for example infusion, so as to attach the top and bottom sheets to the foam and honeycomb core panel. The compression strength of the core panel has a direct relationship to the shear strength of the finished panel so that it has been desirable to maximize this compression strength. Such panels have become widely used for many products.

The materials commonly used for the honeycomb panel are phenolic paper, aluminum and various types of plastic materials. The selection is made in part dependant on cost relative to the desired strength with the aluminum of course providing the highest strength at the highest cost. Phenolic paper is the simplest and cheapest option and is very widely used. The honeycomb, in many cases, is formed by bonding strips side by side with the tubular cells formed around rods or simply by stretching the bonded strips longitudinally of the panel to open them up. Adhesive and heat sealing can be used for attaching the strips.

However there is always an ongoing requirement for yet further increasing the strength of such panels to enable additional markets to be entered or for strength requirements to be met with a thinner panel of less material.

SUMMARY OF THE INVENTION

It is one object of the invention to provide a tank manufactured from composite panels.

According to one aspect of the invention there is provided a tank comprising:

a tank wall formed at least in part by at least one panel member;

the panel member comprising a honeycomb core panel having a first face and a second opposite face with an array of generally hexagonal tubular cells defined by walls of the core panel extending between the first and second faces;

a foam material filling the tubular cells;

a first fibrous reinforcing cover sheet extending over the first face of the core panel;

a second fibrous reinforcing cover sheet extending over the second face of the core panel;

the first and second cover sheets being filled with a set resin material;

wherein the walls of the honey comb core panel are formed from a porous fibrous material;

and wherein the set resin in the cover sheets extends from the cover sheets into the porous fibrous material of the walls of the core panel so as to form an integral structure of the resin extending between the walls and the sheets.

In one arrangement the tank may be rectangular. In this case the tank is formed from a plurality of panels arranged edge to edge.

The panel members can be connected edge to edge by an adhesive or by channel members into which an edge of the panel is inserted.

In another arrangement the tank may have a cylindrical wall and at least one circular end wall.

In this case the circular end wall can be formed of a single panel member and the cylindrical wall is formed of one or more curved panel members.

Thus the cylindrical wall can be formed of a single peripheral panel member with the first cover sheet defining an inner surface of the tank and the second cover sheet defining an outer surface of the tank.

Preferably the walls of the honey comb core panel are formed from a porous fibrous material and the set resin in the cover sheets extends from the cover sheets into the porous fibrous material of the walls of the core panel so as to form an integral structure of the resin extending between the walls and the sheets.

Preferably the resin substantially fills the material of the core walls and preferably the resin extends through the core walls from the first sheet to the second sheet. However the first intention is that the resin acts firstly to form an integral connection between the layer defined by the face sheets and the core walls so as to provide and increased resistance to shear forces tending to delaminate the structure at the junction between the sheet and the core. Hence, it will be appreciated that, in order to achieve this requirement, the resin may not extend fully through the structure to form the tubular reinforcement. Thus other resins can be used in the core material provided they do not interfere with the formation of the integral connection.

Secondly the intention is that the resin forms an increased compression resistance in the core panel by forming a series of resin reinforced tubes through the panel at the walls. Hence, it will be appreciated that, in order to achieve this requirement, the resin may not extend fully into each and every pore or space in the walls but the resin will extend into the structure sufficiently to form the integral connection at the sheets and the tubular reinforcement extending through the panel.

It will be appreciated that the walls generally do not contain any existing resin filling material when the resin introduction occurs since this will prevent or inhibit the penetration of the resin into the walls and the formation of the tubular structures through the panel and the integral connection to the sheets. However the walls may contain some reinforcing resin provided it does not prevent the formation of the integral connection.

Preferably the resin is a thermosetting resin such as thermosetting polyester. However other types of resin can be used such as polyurethane or epoxy, vinyl ester, phenolic resin.

Preferably the walls are connected each to the next to form the honeycomb panel by a heat seal. This is preferred as the heat seals are less likely to interfere with the entry of the resin during the resin introduction process and are easier to effect and less expensive. However adhesive connection may be used.

Preferably the walls are formed from a non-woven fibrous material such as a spun bond fibrous plastics material. However the material selected can be of any construction provided it is porous so as to allow the penetration of the resin during the resin introduction step. Thus of course aluminum and plastics film cannot be used. The material should also bond to the foam during the foam filling step. The compressive strength of the material in the honeycomb construction is of less importance and can be quite low in comparison with other materials, such as those conventionally used, provided it is sufficient to allow the foam filling step to occur.

Preferably the sheets contain glass reinforcing fibers as these are inexpensive and are known to provide the required strength characteristics. However other reinforcing fibers can be used.

While the term “honeycomb” is used generally and in this document it will be appreciated that the tubular cells formed are generally not accurately hexagonal in cross section, particularly where, as described herein, the cells are formed from a porous fibrous material without reinforcing resin available during the filling process to maintain a regular shape of the cells.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:

FIG. 1 is horizontal cross sectional view through a panel to be used in the present invention.

FIG. 2 is a vertical cross sectional view through the panel of FIG. 1

FIG. 3 is an isometric view of a tank according to the present invention.

FIG. 4 is a cross sectional view through one edge of the tank of FIG. 3.

FIG. 4A is a cross sectional view through one edge of an alternative arrangement of the tank of FIG. 3.

FIG. 5 is an isometric view of a second tank according to the present invention.

DETAILED DESCRIPTION

The composite panel described in general above is shown in FIGS. 1 and 2 and is formed by a honeycomb core panel 10 having a first face 11 and a second opposite face 12 with an array of generally hexagonal tubular cells defined by walls 10A of the core panel extending between the first and second faces. The cells are formed from strips 15, 16 arranged side by side of a porous fibrous material which is heat sealed at a sealing line 14 to define the generally hexagonal cells.

A foam material such as a polyurethane foam 18 fills the tubular cells.

A first fibrous reinforcing cover sheet such as a fiberglass mat (or carbon fiber, aramid fiber, Kevlar fiber, polyester fiber, natural fiber—e.g. hemp, flax, straw) 19 extends over the first face 11 of the core panel and a second fibrous reinforcing cover sheet 20 extends over the second face of the core panel.

The first and second cover sheets are filled with a set resin material 21 which extends from the cover sheets 19, 20 into the porous fibrous material of the walls 15, 16 of the core panel so as to form an integral structure of the resin extending between the walls and the sheets.

In FIGS. 3 and 4 is shown a tank 10 which is rectangular and is formed from a plurality of panels 11 to 14 arranged edge to edge. In the example shown, each side wall 11 to 14 is formed of a single panel, but in other examples (not shown) each side wall can be formed of a plurality of panels arranged in rows or arranged in rows and columns. The bottom panel 15 is also a single panel as shown but again more panels can be provided depending on dimensions.

The panel members are connected edge to edge by channel members 16 into which an edge of the panel is inserted. The channel members can be arranged at 90 degrees as shown in FIG. 4 or can be at 180 degrees or at other angles as required.

As an alternative arrangement shown in FIG. 4A, a corner is formed by constructing the tank as an integral member without use of a separate channel member 16. In this arrangement the corner is formed by two portions of the honey comb material indicated at 30 and 30A where the portion 30 butts against the side of the portion 30A at its edge and the sheets 20 and 21 wrap around the corner so that the sheets form an integral structure at the corner. Thus the sheet 21 wraps around the outside surface of the honeycomb portions and the sheet 20 forms an inside surface. The fact that the resin drawn through the structure integrates the honeycomb and the sheets allows sufficient tensile strength to prevent fracture at the corner. Thus the joints between the honeycomb core panels 30 and 30A are formed with the first and second cover sheets bridging the joints. These joints can lie in a common plane where necessary. However, also at corners which can be at right angles or at another angle different from 90 degrees, the joints between the honeycomb core panels are formed at an angle to one another so as to form a corner of the tank with the first and second cover sheets bridging the joints.

In FIG. 5, the tank has a cylindrical wall 18 and at least one circular end wall 19.

The panel members are connected edge to edge by an adhesive layer 20. The circular end wall is formed of a single panel member and the cylindrical wall is formed of a cylindrical one or more curved panel members.

Thus the cylindrical wall is formed of a single peripheral panel member with the first cover sheet defining an inner surface of the tank and the second cover sheet defining an outer surface of the tank. In the alternative the tank can be formed from flat panels arranged as a polygonal arrangement.

Thus the circular end wall is formed of a single panel member.

The curved panels can be formed using the honeycomb as previously described where the honeycomb material is laid into a mold and the polyurethane foam injected while the honeycomb is in the required shape. The inner and outer sheets are then applied and the resin introduced into the sheets and the walls of the honeycomb by a resin infusion system while the panel is shaped in its required shape. The honeycomb material is shapable into required shapes by curving the sheet so that the top and bottom surfaces curve to the required shape without distorting the tubes.

Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.

Claims

1. A tank comprising: a tank wall formed at least in part by at least one panel member;the panel member comprising a honeycomb core panel having a first face and a second opposite face with an array of generally hexagonal tubular cells defined by walls of the core panel extending between the first and second faces;a foam material filling the tubular cells;a first fibrous reinforcing cover sheet extending over the first face of the core panel;a second fibrous reinforcing cover sheet extending over the second face of the core panel;the first and second cover sheets being filled with a set resin material;wherein the walls of the honey comb core panel are formed from a porous fibrous material;and wherein the set resin in the cover sheets extends from the cover sheets into the porous fibrous material of the walls of the core panel so as to form an integral structure of the resin extending between the walls and the sheets.

2. The tank according to claim 1 wherein the resin substantially fills the core walls.

3. The tank according to claim 1 wherein the resin extends through the core walls from the first sheet to the second sheet.

4. The tank according to claim 1 wherein the resin is a thermosetting resin.

5. The tank according to claim 1 wherein the walls are connected each to the next to form the honeycomb panel by a heat seal.

6. The tank according to claim 1 wherein the walls are formed from a non-woven fibrous material.

7. The tank according to claim 1 wherein the walls are formed from a spun bond fibrous plastics material.

8. The tank according to claim 1 wherein the sheets contain glass reinforcing fibers.

9. The tank according to claim 1 wherein the tank is rectangular.

10. The tank according to claim 9 wherein the tank is formed from a plurality of panels arranged edge to edge.

11. The tank according to claim 10 wherein the panel members are connected edge to edge by an adhesive.

12. The tank according to claim 10 wherein the panel members are connected edge to edge by channel members into which an edge of the panel is inserted.

13. The tank according to claim 1 wherein the tank has a cylindrical wall and at least one circular end wall.

14. The tank according to claim 13 wherein the circular end wall is formed of a single panel member.

15. The tank according to claim 13 wherein the cylindrical wall is formed of one or more curved panel members.

16. The tank according to claim 13 wherein the cylindrical wall is formed of a single peripheral panel member with the first cover sheet defining an inner surface of the tank and the second cover sheet defining an outer surface of the tank.

17. The tank according to claim 16 wherein the circular end wall is formed of a single panel member.

18. The tank according to claim 1 wherein joints between the honeycomb core panels are formed with the first and second cover sheets bridging the joints.

19. The tank according to claim 18 wherein the joints between the honeycomb core panels are formed at an angle to one another so as to form a corner of the tank with the first and second cover sheets bridging the joints.