US 3066059 A
Description (OCR text may contain errors)
Nov. 27, 1962 G. M. ADIE STRUCTURAL E :LmENTs Filed Sept. 3, 1958 2 Sheets-Sheet 1 ggg?? www fl Attorneys Nov. 27, 1962 G. M. ADIE STRUCTURAL ELEMENTS 2 Sheets-Sheet 2 Filed Sept. 5, 1958 Q EM Attarney nited States Patent Y 3,055,959 Patented Nov. 27, 1962 3,066,059 STRUCTURAL ELEMENTS George Mountford Adie, 7 Carlos Place, London, England Filed sept. 3, 195s, ser. No. 758,731 Claims priority, application Great Britain Sept. 3, 1957 7 Claims. (Cl. 154-43) This invention relates to materials and elements for use in building construction and the like.
The use of cellular materials for such purposes is attractive for various reasons including their lightness. Generally speaking, however, cellular materials are not suitable for use by themselves but have to be faced with a material which is more resistant to concentrated loads, and they are most commonly used as the filling material between two boards of substantial rigidity and tensile and compressive strengths.
Cellular materials (by cellular material is meant a material which throughout its length and breadth comprises a series of regular closed cells) can be made by the juxtaposition of cell forming elements but are more commonly made by a casting or moulding process designed to leave pores or voids in the starting material. In the former case, it has been usual to use cells all of the same size; while in the latter case, it is found difficult t control the size of the cells with any great accuracy, and impossible to exercise any substantial degree of control over the distribution of the cells.
The invention includes within its scope a slab, panel, plank or the like, of cellular material in which the density of the material is graded so as to be a maximum in the neighbourhood of one or both of its faces, and a minimum in the neighbourhood of the opposite face, or the median plane as the case may be. As will be explained in due course, that can lead to a very significant saving in material, and consequently in weight and cost.
In general, it will be advisable to face such a slab (on one or both faces) with a non-cellular material which is more resistant to concentrated loads, and a slab so faced `falls within the scope of the invention. The facing element need not, however, be a board such as has usually been used but is preferably in the nature of a skim that is to say a thin sheet having little inherent rigidity but which may have been rigidied by the provision of thin ribs which project from one of its faces and serve as a means for keying the skin to the slab.
The variation in density of the cellular material which is characteristic of the invention can be contrived in various ways. For example, the slab can be made up of layers or slices having cells of different sizes, of different shapes. or of different wall thicknesses, or of different materials. Ideally, the density would vary smoothly with increasing distance from one or both faces but, in practice, it is sufficient that it vary step-by-step. v
The best form of cell for maximum economy of material for a given strength is the spherical. However, very acceptable results can be obtained with cells which depart quite substantially from the spherical, for example cells formed by the juxtaposition, base to base, of two truncated cones or pyramids.
The invention extends also to a novel form of cellular material formed by the juxtaposition of thin sheets of mouldable material, such as a thermoplastic, having dimples or cups formed in them, the open sides of the dimples being brought opposite each other to provide the cells.
The invention further includes a plant for the fabrication of such a cellular material.
In order that the invention may be thoroughly understood it will now be explained further with reference to 2 the accompanying drawings given by way of example in which:
FIGURES l and 2 are explanatory diagrams;
FIGURE 3 shows diagrammatically a plant for fabricating a cellular material;
FIGURE 4 shows a dimpied sheet produced at an intermediate stage by the plant of FIGURE 3;
FIGURE 5 is a section taken on the line V-V in FIGURE 4;
FIGURE 6 shows one use of a cellular element in accordance with the invention; and
FIGURE 7 shows an element containing cells formed by truncated cones.
In the diagram of FIGURE 1 is shown a mass 10 having throughout its length and breadth a series of symmetrical closed cells bounded by `a skin 12 of non-cellular material which provides the cellular mass with a substantially improved resistance to penetration under the effect of la concentrated compressive load, such as is indicated at As is well known, the force F which is applied over a very small area becomes diffused over a much larger area as it travels through the mass, as indicated in the drawing. Consequently, with increasing distance from the skin 12, the strength which the cellular material must have in order to resist the force F decreases. The density of the cellular material can therefore be made to decrease away from the skin 12. Here, that is done by gradually increasing the size of the cells 14.
A slab such as is shown in FIGURE l can be used where the face remote from the skin 12 is protected as, for example, when the slab is used as a iloor or wall covering. :I
If, however, both faces are to be made resistant to penetration, a double-sided slab can be used as shown in FIGURE 2 in which there is a skin 12 on each side, and the density of the cellular material decreases away from each skin so as to be a minimum in the neighbourhood of the median plane of the slab.
The most common method of giving materials such as rubber and plastics a cellular structure of closed cells is the so-called foaming The methods of foaming in use to-day do not, however, allow the specific gravity of the end product to be predicted with any degree of accuracy. Foamed products can, however, be used in accordance with the invention if the precaution is taken of producing blocks of distinctly different nominal densities (for example, in the ratio 1:224), cutting the blocks into thin slices and grading the slices by weight before assembling them to form the desired slab. The slices must, of course, be caused to adhere strongly to each other, for example, by interleaving them with adhesive cellulose or like strips.
FIGURE 3 shows a plant which can be used to make a cellular material in accordance with the invention from material in roll form.
As will be seen there is a series of rolls A1, A11,
which can be assumed to carry foils F1, F11, .d of a thermo-plastic material, such as polyvinyl chlor1 e.
These rolls are arranged in groups of three, such as A1, A2, A3; A4, A5, A6, etc., separated by the rolls A4, A8, etc.
The foils F1 and F3 from the extreme rolls in the first group are passed through pairs of rolls B1, B3 which form them to the shape shown in FIGURES 4 and 5, that is to say put dimples or cups 16 into them. The foil F2 from the centre roll is not dimpled but passes between a pair of sprays S1 which spray an adhesive on to both its sides and the facing sides of the dimpled foils. The three foils F1, F2, F3 then pass through a pressing roller assembly Cl which causes them to be joined together as a single sheet having substantiallyspherical cells of a size determined by the dimpling rolls B1, B3.
The foils from the rolls A5, A6, A7 are subjected to the same process but are providedwith larger cells; the foils from the rolls A9, A10, A11, are also similarly treated but are provided with still larger cells.
The cellular sheets D so formed are fed onwardly between a further pair of presser roll assemblies C2. They are interleaved with foils F4, Fg, F12 which are provided with adhesive from the sprays S2.
Also, skins E corresponding to the skins 12 of FIG URE 2, and of somewhat greater thickness than the foils, are fed to the presser roll assemblies C2 after having been coated with adhesive.
The foils and the skins are thus pressed into a cellular slab or block of indefinite length having a regular series of symmetrical closed cells which can be cut as desired and the density of which decreases with increasing distance from the outer skins.
The plant required is of a very simple nature and formed of parts which are readily available as they are akin to those used in paper-making machines.
When using thermoplastic foils, they can be welded together instead of being stuck, the sprays S1 and S2 being replaced by radiant heaters.
The dimples formed by the rolls B1 etc. need not be hemispherical. As already indicated, they could be truncated cones or pyramids.
The foils can be very thin. They can, for example, be as thin as say 0.006 inch. Their thickness will depend on the material and in general will not exceed -,O inch. The outer skins can also be quite thin, for example, up to about 1,432 inch.
The method just described lends itself to the use of foils of different materials or thicknesses, and to the provision of as many layers or slices -as are desired. Also, the inter-cellular spaces and/or cells may be filled with any desired hardening, fire-proofing or other material.
Cellular materials in accordance with the invention can be used for a wide variety of purposes. An obvious use is partitioning. Another is as a facing material, for heat or sound insulation or any other purpose, in which case, one of the outer skins can with advantage be omitted s as to provide a non-plane face which may prove a good key for plaster cement and the like.
One particularly interesting use is as permanent formwork or shuttering as shown in FIGURE 6.
Therein is shown a slab comprising a cellular mass 10 andprotective skins 12 to one of which has been applied a dimpled foil of the kind shown in FIGURES 4 and 5 t with the dimples opening upwardly. vBefore use, the dimples are covered by a foil which can be stripped off as shown. Thereupon concrete or plaster 22 can be laid and supported by the slab acting as a shutter or form which, however, remains attached to the cast mass.
in the case of a very light mass to be cast, the upper skin 12 can be omitted. In the case of a heavy mass, the dimpled foil i8 can be replaced by a ribbed skin of the kind with which my British patent application Nos. 12923/56 and 5484/57 are concerned, the ribs projecting away from the cellular slab.
Although the invention lends itself very well to the use of plastics, and particularly thermoplastics, it olers a wide choice of material which depends on the ultimate use of the nal product, and will be governed by such G5 tial considerations as toughness; ability of surface to withstand scratching; and to provide a decorative effect; high tensile and compressive strength; ability to resist impact and sharp point loads while being of light weight and of a desired thickness; non-inammability; resistance to melting and deformation at high temperature; resistance to attack by inescts, weather and industrial fumes; high strength per unit of weight; and so on.
Above all,` the invention provides for economy of material, and thus allows materials to be used which have so far been neglected because of their high cost.
1. A building element formed of at least three pairs ofjuxtaposed thin exible sheets of mouldable material, cachY sheet of a pair havingra series of regular shaped dimplesformed in it, the dimples being arranged in a regular pattern with flat portions between the dimples, the open sides of the dimples in the sheets of a pair being disposed opposite each other to provide closed cells, the cells formed byy one pair of sheets varying in size from those of the others and the pairs being arranged so that the diameters of the cells are graduated in size progressively from vone of its faces to the other, and foils disposed between each pair of cell sheets.
2. A building element according to claim 1 in which the element is faced on at least one side with a skin of a non-cellular material having a substantial lresistance to penetration by concentrated compressive loads.
3. A building element according to claim l in which the cells have the shape of two juxtaposed truncated cones.
4. A building element according to claim 1 in which the cells are substantially spherical.
5. A building element formed of at least five pairs of juxtaposed thin flexible sheets of mouldable material, each sheet of a pair having a series of regular shaped dimples formed in it, the dimples being arranged in a regular pattern with flat portions between the dimples, the open sides of the dimples in the sheets of a pair being disposed opposite each other to provide closed cells, the cells formed by at least three pairs of sheets varying in size from each other and the pairs of sheets being arranged so that the diameters of the cells are graduated in size progressively from a minimum in the vicinity of one of its faces to a maximum in the vicinity of its median plane, and foils disposed between each pair of cell sheets.
6. A building element according to claim 5 in which the cells have the shape of two juxtaposed truncated cones.
7. A building element according to claim 5 in which the cells are substantially spherical.
References Cited in the le of this patent UNITED STATES PATENTS 1,116,185 White Nov. 3, 1914 1,802,880 Cumfer Apr. 28, 1931 2,129,488 Bomberger Sept. 6, 1938 2,268,049 McGuire Dec. 30, 1941 2,333,343 Sendzimir Nov. 2, 1943 2,759,523 Goldstein et al Aug. 21, 1956 2,855,021 Hoppe Oct. 7, 1958 3,003,599 Rubissow Oct. l0, 1961 FOREIGN PATENTS A551,733 Great Britain Mar. 8, 1943