CA1043066A

CA1043066A - Glass fibre products

Info

Publication number: CA1043066A
Application number: CA203,901A
Authority: CA
Inventors: Neil M. Cameron; Kenneth C. Thatcher; Frederick P. Mallinder
Original assignee: Fibreglass Ltd
Current assignee: Fibreglass Ltd
Priority date: 1973-07-12
Filing date: 1974-07-03
Publication date: 1978-11-28
Also published as: DE2433276C3; IT1017108B; AU7096574A; FR2236638B1; FR2236638A1; DE2433276B2; GB1443167A; DE2433276A1; JPS5736134B2; JPS50123779A

Abstract

ABSTRACT
The following specification discloses a process for producing glass fibre reinforcing members with an anchorage point at at least one end by continuously passing glass fibre rovings after impregnation in a bath of resinous material through a die to shape the rovings to ribbon form followed by curing of the resin by passage of the ribbon through a curing oven. The ribbon is surrounded before curing, at discrete intervals along its length, by casings which travel with the ribbon through the curing oven, and provide areas which form or can subsequently be formed into anchorage areas for the members. The glass fibre members are cut from the ribbon on leaving the curing oven at inter-vals determined by the desired length to be formed.

Description

~043(~66 This invention relates to a method for the production of reinforcing members made from glass fibre reinforced material, and to members produced by the method of the invention.
The reinforcing members or straps of the invention are designed for use in the reinforcement of structures whi~ch are simply formed f-rom a bank of gravel, earth or like materials and a wall. They can be used e.g. as reinforcing members in reinforcing structures in the manner disclosed in U.K. Patent Specification 1,069,361. In such a use, it is necessary that the reinforcing members be attached to at least one anchoring member, and the present invention is directed to the semi-continuous production members from a glass fibre reinforced material which are provided with anchorage means to co-operate with an anchoring member in forming a re~nforced earth structure.
It is well known to form rods of various diameters ~rom a combination of glass fibre strands and polyester resins.
Glass fibre rovi`ngs in this process are drawn through a resin impregnating bath, and then throu~h a heated die both to shape and cure the impregnated rovings. Passage through the die also removes entrapped air~ excess resin and assists penetration of the resin into the fibre bundles~ and imparts a desired diameter to the composite. It is also known to pass the impregnated rovings through a split female die, and tQ cure the product in the die either by dielectric heat;ng, or external heating of the die. Once cured the die is opened~ so that tfie next discrete length can be drawn into the die.
We have now found that by a relatiYely simple modification of the processes used previously in the manu-facture of di~e formed glass fibre reinforced plastic rods, we can produce in a continuous manner reinforcing members for use in earth reinforcement. Such members should normally have a length in the range 5 to 30 metres, be about 80 mm

-2-~(~143~6~i wide and have a thickness up to 6 mm. In order to produce such members, it is essential to have a process which can be easily altered to provide reinforcing members of various lengths, as even for one particular structure, the members used are not necessarily all of the same length.
The production of reinforcing members from a combination of glass fibre rovin~s and thermosetting resins, e.g. a polyester resin, therefore invol~es the impregnation of the rovings with the resin, and the passage of the impregnated ro~ings through a die to impart a desired ribbon shape to the impregnated rovings. The material in ribbon form can be continuoùsly cured by passage through a curing oven and subsequently cut into members of convenient length.
It is not then possi~ble to simply bore a hole to pro~ide an anchorage point~ as thi`s destroys the integrity of the reinforced material.
We have now found that we can produce a ribbon and cure it continuously and at the same time provide areas o~ tfie ribbon wi~th anchorages formed in situ, or areas where anchorages can subsequently be formed after divi`sion of the ribbon into the lengths needed to form the members. Anchorages are formed in situ by utilising a die wfi-~ch has the dual funct~on of forming the die for shaping a port~on o~ the ribbon and also acting as a casing at an anchorage point on the member. The die can be shaped so as to slot into a sui`tably shaped retaining wall, or can pro~ide the-means to ensure the inteyrity of the reinforced member if a hole is made thxough the die and the member to proviae a hole through which a bolt can be passed to anchor the member. ~lternatively we surround the ribbon with a casi~ng along a discrete portion of the ribbon r which can be removed after passage throuyh the curing oven. This means that when the ribbon is cut to form the reinforcing members there are portions which because of the casing are

3~143~66 still in a state where they can be shaped to form an anchorage, and then cured to a final form.
According to the invention therefore, there is provided a process for producing glass fibre reinforcing members with an anchorage point at at least one end by continuously passing glass fibre rovings after impregnation in a bath of resinous material through a die to shape the rovings to ribbon form followed by curiny of the resin by passage of the ribbon through a curing oven~ the ribbon bei`ng surrounded before curing at discrete intervals along its length by casings which travel with the ribbon through the curing oven, and provide areas which form or can subse-quently be foEmed into anchorage areas for the members, the members being cut ~rom the ribbon on leaving the curing oven at intervals determined by the desired length of member to be formed.
In one form of our invention, we provide a process for the production of reinforcing members in which glass fi~bre rovings are impregnated with a thermosetting-resin, and continuously shaped to ribbon form by passage through a die followed by curing of the resin on passage of the shaped ribbon through a curing oven, the improvement of providing means surrounding the ribbon at intervals be~ore it is cured to prevent or inhibit curing in discrete locations, and divlding the ribbon after passage through the oven into mem~ers, ana subsequently shaping each member at an uncured position to provide an anchorage point on the strap.
In another form of our invention~ we provide a process for forming a glass fibre reinforcing member com-prising the steps of passing glass fibre rovings through a bath of resinous material to impregnate the rovings, drawing the impregnated rovings through a split female die to shape the impregnated rovingsr remove excess air and assist impregnation, the die being mounted so as to be released to ~36~
travel to a curing position along with the impregnated rovings once sufficient roving has been shaped and passed through the die to give a desired length of reinforcing me~ber, curing the formed member with the die in place, replacing the die now at the curing position with a further die at the shaping position to form and become part of the next reinforcing member, and so on, and finally separating the cured members as they leave the curing position, the dies being shaped to give a flat strip and are themselves wedge shaped on at least one surface.
Considering first the form of our invention, where we use a removeable casing, the selection of the position where the ribbon is divided will determine the final type of reinforcing member produced. If it is simply divided at an uncured portion, the anchorage can be simply formed by splitting the uncured portion along its length, and wrapping the split ends formed around an insert or alternatively a simple former, and then curing. By dividing so as to leave an uncured portion at the centre of a len~th of the ribbon, one can form a double-member by bending the uncured portion around an insert or alternatively a former so that the cured portions are at a convenient angle to one another. An alternative~ where there is an uncured portion at the centre of the length of ribbon, is to bring the two parts into alignment with one another~ so as to form what is virtually a single strap.
The means to prevent or inhibit completion of curing along a discrete portion of the ribbon is most conveniently formed by using a pair of rectangular recessed trays which can be clamped together to form a box-like structure surrounding the ribbon. The trays are recessed to prevent direct contact between the surrounded portion of the ribbon and the major flat surfaces of the trays, and thus provide an air space which acts to insulate that portion ~L~4;3(~6 of the ribbon while passing through the curing oven. The material used to form the trays can be either a metal or a ceramic material.
Our invention, therefore, also includes the forms of reinforcing member produced in the manner described above~
In the form of our invention where we use a die to both shape the member and as a casing surrounding the rib~on at an anchorage point, the die used must be of a two part construction to enable it to be placed around the glass fibre as it leaves the impregnating bath. It is preferable to use a simple construction where one part rests within the other so as to avoid the need for clamps or bolts which will increase the time taken to place the die in position~ and the actual cost of the die. We prefer to use a die of the kind shown in Figure 3~ where one part A`is made from a sheet of metal tapered in one direction, and turned over on the tapering sides to form a flange, while in the case of B the flange is turned o~er yet again so as to retain A within B, when A is slotted into place.
The cured members with the encased wedge shaped ena can be drilled so that a bolt can be passed through to anchor the end to a retaining wall when using the members to reinforce an embankment. ~igure 5 shows a typical arrangement of strips and Figures 4A and 4B show two alternative ~ethods of anchoring the members in a retaining wall. In Figure 4A, a retaining slot into which the end can ~it is cast with the wall as it is formed~ the member can then be easily slotted ~n and bolted into place~ In Eigure 4B, a metal ~etaining member 19 is cast in situ in the wall, a wedge 20 can then be placed on this member 19, and the retai`ning member 21 in turn placed on top of 20 and the whole bolted to~ether.

The production of glass fibre reinforced resins by impregnation and extrusion is a well known process, and ~3~;6 there are available resins specially formulated for use in such processes making selec~ion of resin simple for those practised in the art. The curing time is dictated by the nature of the resin used, and again can be easily determined by the man practised in the art.
The strength of the members must be sufficient to accept the maximum working load in a reinforced earth structure with an adequate margin of safety. Such a working load is unlikely to exceed 3 tons.
The process and products of the process will be more fully described with reference to the attached drawings, in which:
Figure 1 is a sectional view of one form of reinforcing member.
Figure 2 (a) is a schematic view of the process used to produce the members with an in situ anchorage with clamping members 4 removed for clarity.
Figure 2 (b) is a plan view to show how the die 3 can be clamped between members 4.
Figure 3 is a view showing the construction of the die used in the process shown in Figure 2.
Figure 4A and B show how the expanded end of the reinforcing member with the in situ anchorage may be incorporated in anchor means.
Figure 5 is a cross-sectional view showing the reinforcing members of ~igure 1 in position in an earth structure.
Figure 6 (a) is a schematic layout of the equipment used in producing the members with a removeable casing to prevent or substantially reduce curing.

Figure 6 (b) is a plan view of the layout of 6(a).
Figure 7 (a) a member having an insert or thimble ~L0430G6 insert in the anchorage.
(b) a member having no thimble or insert in the anchorage.
(c), (d) and (e) :Linked members formed using the equipment shown in Figures 6(a) and 6(b).
One ~orm of our invention is illustrated by figures 2(a) and 2(b) and will now be described with reference to those figures.
Glass fibre is unwound from roving cakes 1 and passes into a resin impregnating bath 2, and then through a die 3. The die 3 is constructed as shown in Figure 3, and is shaped so that the resin/fibre mixture leaving the die is in ribbon or strip form. The die 3 is positioned between a pair of clamping members 4 as shown in Figure 2(b). Once sufficient material has been extruded to give a reinforcing strip of the desired length, a capping pin 5 is inserted in the wide end of the die to prevent the resin oozing out, and the clamping members 4 are moved to free the die, which is then moved toward the curing oven. A further die to produce the next strip is then placed round the glass fibres, the clamping members 4 are moved to hold the die~
and forward movement of the flrst assembly is continued into a curing oven 6, resulting in fibre being drawn through the new die to form the next member~ the process being repeated when sufficient material has passed through the die. As the cured memhers leave the curing oven 6, they are sepa~ated into separa~e reinforcing strips each strip having a wedge shaped end surrounded by a metal casing which was the die used to form the reinforcing strip.
Another form of our invention is illustrated by figures 6(a) and 6(b) and will now be described with reference to those figures.

Glass fibre 1 is unwound from cakes and passes into a resin impregnating bath 2, and then through a die 3.
The shaped ribbon leaves the die 3, and passes to a curing ~8--1~3~66 oven 6. As the ribbon passes to the curing oven, means 12 is placed around the ribbon to prevent or inhibit curing at that area of the ribbon during passage through the curing oven. The ribbon is drawn through the curing oven and the die by means of driven pull wheels 13. On leaving the curing oven, means 12 is removed, and the ribbon may be cut at that point by cut-off saw 7. The uncured end is split and the split ends either wrapped round a thimble 14 as in Figure 7(a~, or simply shaped round a former to give after curing the strap shown in Figure 7(b). The uncured portion is then cured to give the final form of the reinforcing strap. Alternatively the system shown beyond the broken lines 10 may be used. In this case the ribbon is passed onto a trolley 8 with wheels which run on trolley rails 9, and around an anchorage forming pin 11, so as to turn back on itself and form a member of the kind shown in Figures 7(c~, 7~d) or 7(e). The trolley's final position is fixed by the distance from the anchorage to the cut-off point.

Claims

We claim:

1. A process for producing glass fibre reinforcing members with an anchorage point at least at one end comprising passing resin impregnated glass rovings through a shaping die and through a curing oven and cutting the rovings to desired lengths, the rovings being passed through the oven while surrounded by casings at longitudinally spaced apart locations which correspond to the anchorage points and which either shape the rovings to form the anchorage points and permit curing of the resin at the locations during passage through the oven or prevent curing of the resin at the locations at which, after removal of the casings, the anchorage points are subsequently formed and the resin cured.

2. A process according to claim 1 which comprises drawing the impregnated rovings through a first split female die which is wedge shaped on at least one surface and is disposed at a shaping position to shape the impregnated rovings passing through, remove excess air and assist impregnation, the die being mounted so as to form the casing and to travel from the shaping position through the curing oven with the impregnated rovings once a sufficient length of rovings has been shaped and passed through the die to give the desired length of reinforcing member, and curing the length of ribbon in passage through the curing oven with the die shaping the anchorage point.

3. A process as claimed in claim 1 in which the casing is removed after passage of the member through the curing oven so as to leave an uncured portion of ribbon which can be shaped to form an anchorage point.

4. A process as claimed in claim 3 where the ribbon is divided so as to leave an uncured portion at one end which is then split and shaped to form an anchorage.

5. A process as claimed in claim 3 in which the ribbon is divided so as to produce members having uncured portions between their ends, so that a double strap can be formed by bending the member back on itself at the uncured portion, thus forming an anchorage at the uncured portion.

6. A process as claimed in any of claims 3 to 5 where the easing is formed from a pair of recessed trays clamped together to form a flat box-like structure surrounding the ribbon.