GB2172838A - Method for the production of foam-filled rod like members - Google Patents

Abstract

In a method of forming strip material, especially coving for ceilings, a web 38 of material such as a paper web is fed horizontally and longitudinally, and is folded into channel configuration comprising a concave base and inwardly inclined side portions on a conveyer belt 52. Into the corners of the thus folded web is cast liquid chemicals which foam into a rigid cellular form, and with continued movement of the web moving mould pieces 68 engage the top of the web so that the side pieces of the web are overlapped and form covering and the mould pieces restrain the expansion of the liquid chemicals. <IMAGE>

Description

SPECIFICATION Improvements relating to rod or strip like members and a method for the production of such members This invention relates to the rod or strip like members, and to a method for the production of such members.

Specifically, but not exclusively, the invention has particular application to coving strips being strips used to fill the angles between the walls and ceilings of rooms to provide decorative and other effects. As the invention has particular application to such coving strips or as more usually called "coving" for ease of description only the expression coving will be used hereinafter, but it will be appreciated that the invention is applicable to rod or strip like members in general and the word "coving", unless the context prohibits, should be construed to cover all forms of rod or strip like members.

The traditional coving is made from a gypsumtype plaster core within a skin covering of paper.

The paper used is similar to that used in plasterboard, so that it can take the same decorative finishes as the walls and ceilings which are usually of plaster or plasterboard construction.

The method of manufacture of the traditional coving is efficient, and comprises continous process wherein a wet plaster mix is formed or extruded into a moving "belt" of pre-folded paper which is then pressed round the wet plaster. The plaster then hardens while still moving on the production line which is long enough to allow the plaster to harden before it reaches the end of the line, where the complete coving is cut in to lengths by "flying" cutters. The speed of the line, and hence the rate of production, is determined by the length of line and the time taken for the plaster to set sufficiently. The setting time is a few minutes.

There are also known some alternative covings such as expanded polystyrene mouldings but none competes effectively with the coving described above. Either paper is not used for the surface, and the finish is therefore inferior, or the cost is very much higher due to non-continuous production methods having to be used.

The present invention seeks to provide coving which can compete with the traditional coving on quality but can be produced at lower cost.

According to the invention, coving comprises a core of chemical foam with a skin coving, such as a paper covering of quality equal to or better than that used for the traditional coving.

Suitable foams for the core comprise for example polyurethane, polyisocyanurate, and phenolic foams and these are commercially available. They are usually formed by mixing together two liquid chemicals and sometimes also a catalyst. A rapid reaction then takes place in which the foam is formed and hardens into a cellular structure of low density but sufficient strength and durability to form a good core for the proposed product. Foaming/setting times of less then half a minute are quite usual, but pressures generated are high if the expansion takes place in an enclosed space. The foam preferably forms the entire core, but this is not essential to the invention.

The preferred core material is a polyurethane foam with a foaming/setting time of 20 seconds.

This enables high rates of production to be achieved in accordance with the method of the invention set forth hereinafter, on a comparatively short production line, giving substantial production cost advantages and requiring less factory space for the process as compared to the method for manufacturing the traditional coving.

The advantages of the coving of the present invention are: (a) Lower material costs at least when a similar paper to that used in traditional coving is used, as foam at the densities envisaged would be cheaper than plaster.

(b) Lower capital cost of production plant as no blending and mixing machinery would be needed for the core materials, and since in accordance with the method of the invention liquid chemicals would be injected straight into the pre-arranged skin.

Faster setting times of the foam substantially shorten the production line as compared to the method for making traditional coving and therefore less factory space is needed.

The coving of the invention is many times lighter in weight than traditional coving, and is therefore easier to handle and fix.

In accordance with the method of the invention coving is produced by injecting liquid chemicals, which foam into a moving trough defined by a web of covering material, and during the movement the covering material is wrapped round the injected material to form a skin and whilst the liquid chemicals foam they are in a moving mould defining the cross section of the coving so that at the end of the process there results coving comprising a foam core with the said skin therearound.

The skin will preferably be of paper.

The moving mould may comprise a series of rigid mould shells pivotally interlinked to form an endless chain to define the upper (during production) side of the coving whilst the underside may be defined by an endless flexible belt.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings wherein: Figure 1 is a sectional elevation of traditional coving when in position filling a corner between a wall and a ceiling; and Figures 2 to 7 are views showing an embodiment of the method of the present invention.

Referring to Figure 1, the coving 10 shown has a concave side 12 and a convex side 14, the latter facing the corner 16 between the wall 18 and ceiling 20 which is filled by the coving. The side 14 has flats 14A, 14B and adhesive applied thereto enables the adhering of the coving in the position shown. The end faces 22, 24 which lie substantially at right angles to the sides 12, 14 are the upstands and the corners 26 are the arrises. The coving is symmetrical in section about line 29.

The coving 10 has a plaster core 28 and a paper skin 30. It is produced as explained herein.

The method of the embodiment of the present invention will now be described with reference to Figures 2 to 7. In this embodiment the skin web is of paper and the foam forms the entire core.

The process of the embodiment of the invention has the following sequence: (i) Paper creasing.

(ii) Paper folding (partial).

(iii) Liquid chemical injection.

(iv) Paper folding (completion).

(v) Foaming and hardening of foam within the paper skin.

(vi) Cutting to length.

(vii) Packaging and stacking.

The coving which is produced by the method to be explained has the same sectional shape as the coving shown in Figure 1. It is formed with its concave side 12 facing downwards.

Referring to Figure 2, paper 38 of the correct width is fed from a roll 40 through nipping or creasing rollers 42 which indent the paper 38 to form creases at the desired positions 44, 46 along the paper (see Figure 3).

A series of vanes or ploughs, rollers and formers such as formers 48, 50 in Figures 4 and 5 gradually fold the paper 38 at its crease points 44, 46 until the paper 38 is in the partially folded trough form shown in Figure 6. During the folding process, after the concave shape has been formed (as in Figure 5), the paper 38 is carried onto a driven conveyor belt 52 (Figure 2) running on a fixed former 54 (Figure 6) which enables the upper surface of the belt 52 to take up the desired shape of the concave side 12 of the coving. Solid rubber strips 56 are fixed to the conveyor belt 52 on each side of the section, to provide support for the coving upstands 22, 24 during the foaming process and to ensure that the arrises 26 are clean and sharp (see Figure 6).

In an alternative arrangement instead of the nip ping and creasing rollers 42 being used shallow Vshaped grooves are milled in the paper. This per mits easier folding of the paper in the manner to be explained to provide a sharper arris in the final product.

The conveyor belt 52 can be held centrally on its former by guide rollers 58 running on the rear side of the rubber upstand strips 56 (see Figure 6). The height of the rubber strips 56 is equal to the de sired width of the coving upstands 22, 24, and the strips are tapered on their upper surfaces 60 to align with the tapers forming the flats 14A, 14B at the coving edges.

With the paper 38 now on the belt 52, and in its partially folded condition, liquid chemicals 62 are sprayed through fixed nozzles 64 into the folded paper. Preferably, the chemicals 62 are sprayed into the lower corners 66 of the folded paper (see Figure 6) so that when the foaming reaction com mences the foam builds upwards towards the top of the paper trough and no air bubbles are trap ped.

As the foaming reaction commences the paper 38 is folded to its final shape in which the free edges become adjacent as shown in Figure 7. To hold the section in its desired shape while the foam expansion is taking place it is necessary to totally enclose it within a rigid mould cavity of the correct shape. The lower part of the cavity is defined by the convex surface of the conveyor belt 52 and its rubber strips 56. The upper part of the cavity is provided by a series of rigid formers 68 joined together by hinged links 70 to form an endless chain 72 which is driven by drive pinion 74 at the same speed as the conveyor belt 32 (see Figures 2 and 7). The outer lower faces 76 of the formers 68 locate against the upper surfaces 60 of the rubber strips, and are held firmly against them by thrust rollers 78 (see Figure 7). The formers 68 can be centrally located in position by guide rollers (not shown).

The pressure of the expanding foam presses the paper 38 firmly against the surfaces of the moving cavity, thus providing the tractive drive for the paper 38 and contained chemicals, and for ejecting the formed coving from the conveyor 52 to the cutting apparatus. The direction of movement, which is continuous, is indicated by arrow 80.

The length of the chain of upper formers 68 is determined by the desired speed of production and the hardening time of the foam.

When it emerges from the forming section the completed coving is cut to the desired lengths by moving cutters, or "nipping" knives, and removed for stacking and packing.

Claims (13)

1. A method of producing coving by injecting liquid chemicals which foam into a rigid cellular foam, into a moving trough defined by a web of covering material, and during the movement the covering material is wrapped round the injected material to form a skin and whilst the liquid chemicals foam they are moving in a mould defining the cross section of the coving so that at the end of the process there results coving comprising a foam core with said skin there around.

2. A method according to Claim 1, wherein the skin is of paper.

3. A method according to Claim 1 or 2, wherein the moving mould comprises a series of rigid mould shells pivotally interlinked to form an endless chain to define the upper side of the coving.

4. A method according to Claim 3 wherein the underside of the coving is defined by an endless flexible belt.

5. A method according to Claim 4, wherein the belt is lead over a lower former to shape the underside of the coving, and the belt has integral shoulders thereon to define the coving arrises.

6. A method according to Claim 4 or 5, wherein the shoulders and belt are supported against guide rollers mounted on the lower former.

7. A method according to any of Claims 3 to 6, wherein the rigid mould shells are held in position by thrust rollers so as to resist the expansion of the liquid chemicals when they are foaming into rigid cellular form, so as to control the shape of the final coving.

8. A method according to any preceding claim, wherein the covering material which forms the skin comprises a web which is creased and folded into a shape having a concave base and side portions defining edge recesses, into which recesses the liquid chemicals are injected, and the side pieces are moved into a covering position so as to lie in such position whilst they are in the moving mould.

9. A method of producing coving substantially as hereinbefore described with reference to Figures 2 to 7 of the accompanying drawings.

10. A coving produced by the method according to any preceding claim.

11. A coving comprising a core of chemical foam with a skin covering.

12. A coving according to Claim 11 wherein the skin is a paper of a quality equal to or better than that used for traditional coving.

13. A coving substantially as hereinbefore described with reference to Figures 2 to 7 of the accompanying drawings.