CA2360079A1

CA2360079A1 - Method for producing angular components consisting of flat-strip laminated sections

Info

Publication number: CA2360079A1
Application number: CA002360079A
Authority: CA
Inventors: Alexander Bleibler
Original assignee: Individual
Current assignee: Sika Schweiz AG
Priority date: 1999-01-29
Filing date: 2000-01-14
Publication date: 2000-08-03
Also published as: JP2002535187A; DE19903681A1; AU2291000A; CN1114019C; EP1147269B1; KR20010101875A; DE50002441D1; CN1338021A; ATE242378T1; WO2000045009A1; EP1147269A1

Abstract

The invention relates to a method for producing angular components consistin g of flat-strip laminated sections for the retrofitted reinforcement of concre te structures. According to said method several monolayer supporting fibre laye rs which are embedded in a binding agent film (140) are drawn, wound or pressed onto a shaping element (142, 144, 154) having at least one shaping edge (148 , 152, 155) such that they are superimposed on their broad sides and then compressed under the influence of pressure and heat until said layers are joined across their broad sides. After curing of the binding agent the composite part (158) produced in this way is removed from the shaping elemen t and divided into angular components (110) having defined leg lengths and/or widths.

Description

METHOD FOR PRODUCING ANGULAR COMPONENTS CONSISTING
OF FLAT-STRIP LAMINATED SECTIONS
Description The invention relates to a method for producing angular components consisting of flat-strip laminated sections, useful for reinforcing load bearing or load transmitting structures.
Angular reinforcing lamella of this type are known for example from WO 98/32933. The flat strip lamella are comprised of a number of parallel oriented, flexible or bendable reinforcing fibers, which are embedded in a binder matrix comprised of a duraplastic (thermosetting) or a thermoplastic material. The stiff elastic binder matrix does not permit bending with sharp bend angles. In order to make possible reinforcement over corners, angular lamella are preferably employed (WO 98/32933), which are comprised of two lamella shanks engaging each other along a corner-edge running perpendicular to the orientation of the reinforcing fibers, bonded with each other at a defined angle of 30° to 150° into a single unit. Since the structure edges to be reinforced are predominantly formed as right-angles, the lamella shanks preferably join each other at an angle of 90°. In order to transmit tension over a corner without danger of breakage, the corner between the lamella shanks is preferably formed with a corner radius of 5 to 50 mm, preferably 15 to 30 mm. For the production of this type of angular lamella, several possibilities are proposed in WO 98/32933:
- A longitudinally extending flat strip lamella impregnated with binder matrix is subjected, in an intermediate area, to a temperature of 300 to 600°C, to bend-pressing, and subsequently to cooling to the ambient temperature with temporary maintenance of the pressure force, thereby forming two lamella shanks joined to each other at an angle. In this process it was found to be disadvantageous that, in the edge or bend area, pull forces occur externally and compression forces occur internally, which result in an undesired deformation and wave formation in the edge area. This occurs primarily during bending of flat strip lamella with a duraplastic binder matrix.
- A fiber cord or web comprised of reinforcing fibers is wound about a support body with square or rectangular circumference and of f fixed in this wound state . Subsequently the wound f fiber cord is submerged in a liquid synthetic resin to form the binder matrix. The synthetic resin is solidified with formation of a square tube-shaped composite material tube, which is then separated multiple times longitudinally and transversely to form angular lamellas with reinforcing fibers running over the corners in the direction of their longitudinal direction. In this process it was found to be disadvantageous that the reinforcing fibers can break during the wrapping process, and during the subsequent interaction with binder can be incompletely embedded in the binder matrix.
The rigidity characteristic of the end product is thereby subjected to substantial quality fluctuations.
- A further known process is comprised therein, that first the flat strip lamella completely impregnated with binder matrix is heated in at least one intermediate area to the decomposition temperature of the binder and thereby the binder matrix is removed with exposure of the reinforcing fibers.
The thus-prepared flat strip lamella can be bent about a rigid body edge along the exposed reinforcing fibers, and prior to or thereafter this area can be permeated with a fluid hardenable resin. Here there likewise exists the danger, that injury or breakage occurs in the exposed reinforcing fibers, which could lead to degradation of the tensile strength of the angular shaped reinforcing element.

Beginning therewith, it is the task of the invention to develop a process for production of angular shaped construction components comprised of flat strip lamella, of which the products of the process exhibit reproducible physical properties, particularly tensile strength.
For the solution of this task the combination of characteristics set forth in Patent Claim 1 are proposed. Advantageous embodiments and further developments of the invention can been seen from the dependent claims.
The inventive solution is based upon the recognition, that single layers of parallel oriented reinforcing fibers, which in certain cases may be interwoven with a certain proportion of transverse fibers, can be relatively simply embedded in a binder composition film, so that they can be easily handled without danger of damage. In accordance therewith it is proposed in the present invention that multiple single-layer reinforcing fiber sheets or layers embedded in a binder film are applied one upon the other, with their broad surfaces contacting, upon a shaped body exhibiting at least one shaped edge, and are so wound or pressed thereupon that the binder films are pressed against each under the influence of pressure and/or heat and thereby are broad surface bonded with each other, and that the thus formed composite part as removed from the shape body after hardening of the binder and is subdivided into angular shaped components with predetermined shank lengths and breadths.
In a first variation of the invention it is envisioned that the binder films with the single layer reinforcing fiber layers are drawn over each other in tailored shape at their bend-point over the outer edge of a shaped body. According to a second alternative solution, the binder films provided with single layer reinforcing fibers are pressed-in over each other at their bend point in tailored shape against an inner edge or concavity of a shaped body.

Preferably, the duraplastic binder is only partially hardened during heating or pressing of the binder film upon the shaped body, and thus still is adhesive and flexible. The duraplastic binder is herein hardened under the influence of pressure or heat.
In the case of the use of a thermoplastic binder the binder film provided with the reinforcing fibers is deformable and preferably dry during heating or pressing upon the shape body. The binder films are heated to the softening or melting point of the binder under the influence of pressure and heat, and are surface-bonded to each other. The finished component produced using a thermoplastic binder can be deformed at any time by a simple heating.
A further alternative solution envisions that the binder film provided with single layer reinforcing fibers and having the shape of a ribbon or a band is multi-layer wound upon- a beam provided with a shaped edges, that the wound layers are surface bonded with each other under the influence of pressure and heat and that the wound material after the hardening of the preferably thermoplastic binder is separated in suitable manner for providing the angular shaped components.
In the following the invention will be described in greater detail on the basis of the representative embodiment shown schematically in the drawings. There is shown Fig. 1 a flat-strip lamella formed as angular lamella in elevated perspective representation;
Fig. 2 a binder film provided with reinforcing fibers for the production of the angular lamella according to Fig. 1;
Fig. 3 a side view of a device for production of angular lamella according to Fig. 1 employing binder films according to Fig. 2;

Fig. 4 a side view of a device different from Fig. 3 for production of angular lamella with employment of binder films;
Fig. 5a-c a schematic for explaining a further process for the production of angular lamella according to Fig. 1.
The flat-strip lamella shown in Fig. 1 is designed as a preformed angular lamella 110, which is designed for reinforcing load bearing or load transmitting structural components. The angular lamella 110 is comprised of two lamella shanks 134 bonded unitarily with each other in the area of a rounded off transverse edge 130 extending transverse to the. longitudinal direction of the reinforcing fibers 126 and describing an angle of 90°. The curvature radius in the area of the transverse edge 130 is for example 5 to 50 mm. For the production of the angular lamella 110 there are various possibilities:
All of the production variations described in the following begin with an intermediate product, which is comprised of a single layer of unidirectional, parallel to each other oriented reinforcing fibers 126, which in certain cases may be interwoven with a certain proportion of transverse fibers, and which are embedded in a binder film 140. As reinforcing fibers 126, primarily carbon fibers are employed, which are characterized by a high modulus of elasticity. The reinforcing fibers and/or the transverse fibers can however be comprised of or additionally contain aramid fibers, glass fibers, polypropylene fibers and the like. The binder in the binder film 140 is comprised preferably of a duraplastic (i.e., the material undergoes an irreversible change of mechanical and physio-chemical properties during the hardening process, as compared to thermoplastic which softens upon heating), for example, epoxy resin, polyurethane resin, acrylic resin or polyester ester, which in the following described process is somewhat pre-hardened, however is not completely hardened. The binder provided with the reinforcing fibers is still flexible in the process steps, and the binder is still tacky or adhesive.
It is basically also possible to use thermoplastic materials as binders in the binder film. In this case also the binder film should be sufficiently flexible for manipulation.
Figures 3 and 4 respectively show a shape body 142, 144 for production of angular lamellas 110 of suitably tailored binder films 140 with a' single layer reinforcing fiber layers 126 of the type shown in Fig. 2. The shape body 142 according to Fig. 3 exhibits two forming surfaces 146 oriented perpendicular to each other, which are joined to each other via an internal concave forming edge 148. For production of an angular lamella the reinforcing fiber reinforced binder films 140 are sequentially applied in the direction of the arrows 151 and pressed against the shape surface 146 and the shape edge 148 and there, under the influence of pressure and heat, are surface-bonded with each other. The bonding occurs in the case of the duraplastic binder film by hardening of the binder under the influence of pressure and heat, and in the case of the thermoplastic binder film by increasing the temperature to the softening temperature of the binder under the influence of pressure and heat. The composite produced in this manner can be cut into angular lamella 110 with desired dimensions or measurements after the hardening.
The shape. body shown in Fig. 4 is comprised of two forming surfaces 150 oriented perpendicular to each other, which are joined to each other via an external, convex forming edge 152.
For production of the angular lamella 110 the binder films 140 reinforced with single layer reinforcing fiber layers are drawn sequentially over the forming edge 152 upon the shape surface 150, until the desired wall thickness is achieved. Then the binder films are bonded to each other under the influence of pressure and heat in the above described manner and then further processed.
A further process variation is explained on the basis of Figs.
5a through c: A binder film 140 reinforced with a single layer reinforcing fiber layer 126 is wound in a continuous track upon a shaped body 154 with quadratic cross section and forming edges 155, thereby forming a multi-layer winding 156. Then the superimposed layers of the winding are bonded to each other under the influence of pressure and heat. After a hardening of the binder there results a composite part 158 in the shape of a four-sided tube, which can be removed from the shaped body 154 (Fig.
5b). The four-sided tube can then be separated along cut lines or section lines 160 and 162, so that angular lamella 110 result (Fig. 5c), in which the reinforcing fibers 126 in their longitudinal direction run over the edge 130 in the sense of Fig. 1.
In summary the following is to be concluded: The invention is concerned with a process for production of angular reinforcing components comprised of flat-strip lamella, which are designed for supplemental or follow-up reinforcing of cement structures.
In the inventive process multiple single-layer reinforcing fiber layers each embedded in a binder film 140 are drawn, wound or pressed with their broadsides against each other upon a shape body 142, 144, 154 exhibiting at least one forming edge 148. 152, 155, and under the influence of pressure and heat are pressed against each other and thereby surface bonded with each other.
The thus formed composite part 158 is, after the hardening of the binder, removed from the shape body and separated into the angular shaped components 110 with predetermined shank length and/or breadth.

Claims

1. Process for production of angular components (110) comprised of flat-strip lamella, in which a plurality of parallel-oriented flexible or bendable reinforcing fibers (126), which may be interwoven with transverse fibers, are embedded in a hardenable binder matrix of a duraplastic or thermoplastic material and are form-retentively bent, in the area of a transverse edge (130) running transverse to the longitudinal direction of the reinforcing fiber, at a defined angle of 30° to 150°, preferably 90°, thereby characterized, that multiple single-layer. reinforcing fiber layers (126) individually embedded in a binder matrix film (140) are drawn, wound or pressed with their broad surfaces against each other upon a shape body (142, 144, 154) exhibiting at least one forming edge (148, 152, 155), that the binder matrix films (140) are pressed against each other under the influence of pressure and/or heat and thereby surface-bonded with each other, and that the thus formed composite part (158) after hardening of the binder is removed from the shape body and separated into angular components (110) with predetermined shank lengths and/or breadth.

2. Process according to Claim 1, thereby characterized, that the binder matrix films (140) reinforced with the single layer reinforcing fiber layers (126) are tailored in shape and at their bending point (130) are drawn over each other and over a convex forming edge (152) of the shape body (144).

3. Process according to Claim 1, thereby characterized, that the binder matrix films (140) reinforced with the single layer reinforcing fiber layers (126) are tailored in shape and at their bending point (130) are pressed upon each other and against a concave forming edge (148) of the shape body (142).

4. Process according to one of Claims 1 through 3, thereby characterized, that the duraplastic binder during drawing or pressing of the binder matrix film (140) upon the shape body (142, 144) is partially hardened, yet still adhesive and flexible.

5. Process according to Claim 4, thereby characterized, that the duraplastic binder is hardened while on the shape body (142, 144) under the influence of pressure and heat.

6. Process according to one of Claims 1 through 3, thereby characterized, that the thermoplastic binder during heating or pressing of the binder matrix film (140) is deformable and preferably dry, and that the binder matrix film (140) is heated to the softening or melting temperature of the binder under the influence of pressure and heat and that the films are bonded to each other.

7. Process according to Claim 1, thereby characterized, that the binder matrix film (140) containing the single layer reinforcing fiber layer (126) is wound in the manner of a ribbon or a band in multiple layers upon a shape body (154) in the shape of a beam provided with shaped edges (155), that the winding is surface bonded to itself other under the influence of pressure and heat and that the winding (156, 158) after the hardening of the preferably thermoplastic binder is separated preferably multiple times transversely and longitudinally with formation of angular components (110) with reinforcing fibers (126) extending in their longitudinal direction over the edge.

8. Process according to Claim 7, thereby characterized, that the winding (158) is removed from the shape body (154) prior to separation.