WO2013006964A1

WO2013006964A1 - Curved reinforcing rod having an improved mechanical strength at the location of the curvature thereof and method for producing same

Info

Publication number: WO2013006964A1
Application number: PCT/CA2012/050354
Authority: WO
Inventors: Danny St-Cyr; Alexandre LALLIER
Original assignee: Pultrall Inc.
Priority date: 2011-07-14
Filing date: 2012-05-29
Publication date: 2013-01-17
Also published as: CA2746281A1

Abstract

The invention relates to a curved reinforcing rod having an improved mechanical strength at the location of the curvature thereof, characterized in that it is made from a bundle of fibres firmly attached together using a binder polymer and in that it has rectilinear parts that each have one and the same essentially circular cross section and a curved part that is found between the rectilinear parts, this curved part being and having an essentially rectangular or ellipsoidal cross section. The fact that a flattening is produced at the curvature of each rod is of great advantage since this reduces the difference in values between the radii of internal and external curvature at the curvature, which reinforces the mechanical strength of the final product. The invention also relates to a method for producing this rod.

Description

REINFORCED BENDING ROD HAVING IMPROVED MECHANICAL STRENGTH IN PLACE OF ITS BENDING AND METHOD

TO PRODUCE IT DOMAIN OF THE INVENTION

The present invention relates to a curved reinforcing rod having improved mechanical strength at the point of its curvature. The present invention also relates to a method for producing this curved rod of the reinforcement.

DESCRIPTION OF THE PRIOR ART It is known in the field of construction to use curved rods made of a composite material for the purpose of reinforcing concrete parts or structures.

Examples of such parts and works will be detailed below.

The production of such reinforcing rods made of a composite material is known and exploited commercially for several years. This production comprises the shaping of a bundle of fibers of polymeric, mineral, natural or metallic nature which are coated with a thermosetting resin, its winding on templates supported by a rotating frame, the submission of the bundled bundle to a sufficient temperature to ensure the hardening of the resin and optional cutting of the rigid product obtained in sections. As for this type of known production, one can also refer to the US patents cited below.

No. 2,684,318 [Meek] discloses a method which makes it possible to produce rigid rods by saturating a bundle of glass fibers previously saturated with thermosetting resin and pulling it continuously through an oven so as to harden the resin.

US 4,154,634 [Shobert] discloses a method for producing rods by pulling a bundle of fibers previously saturated with thermosetting resin and pulling this bundle discontinuously through at least one heating die so as to cure the resin.

Similarly, US 4,445,957 [Harvey] discloses a method for producing curved rod sections by introducing sections of a thermosetting resin saturated fiber bundle into heating molds which impose the curved shape on the sections of said bundle while ensuring hardening of the resin. If the curved rods obtained so far are known to be very useful, they have however a problem of mechanical strength in their curvatures. This is explained by the fact that the bundle of fibers, when bent, produces a compression of the fibers positioned in the internal curvature. As a result, the fibers are somehow folded and become unable to compete with tension. This situation is magnified by the difference in radii of curvature between the largest and the smallest radii.

It has now been discovered in the context of the present invention that this situation can be improved by changing the shape of the curved section of to maintain the same area of the section but decreasing the difference in values between the inner and outer radius of curvature.

SUMMARY OF THE INVENTION

The present invention therefore relates to a curved reinforcing rod particularly useful as a reinforcement for reinforcing a part or a concrete structure, which rod has an improved mechanical strength at the point of its curvature.

The rod according to the invention is characterized in that it is made from a bundle of fibers bonded together by means of a binder polymer and in that it has straight portions each having a same section substantially circular and a curved portion that is between the straight portions, the curved portion being flattened and having a substantially rectangular or ellipsoidal section.

The invention as claimed also relates to a method for producing the curved reinforcing rod described above having improved mechanical strength at its curvature, said method comprising the following basic steps:

(i) producing a rectilinear rod of substantially circular section from a bundle of fibers by joining together said fibers with a binder polymer;

(ii) folding of this rod around at least one folding jig, this folding giving the rod a curved portion at each of said jig or templates;

(iii) placing the shank placed on the fold template (s) under conditions where the fiber-binding polymer is allowed to harden; and (iv) when the binder polymer is sufficiently hardened, removing the rod from the template (s).

This method according to the invention is characterized in that it comprises the following additional step:

(v) flattening of the rod with the aid of one or more shoes pressed on the curved portion or portions thereof in contact with the folding template or jigs, said flattening being effected after the folding step ( ii), the one or more shoes being removed only after step (iii) so that the setting of the rod under conditions where the fiber-binding polymer can harden, is carried out with the shoes still in position pressing.

Preferably, the curved portion of the rod has a rectangular section and this section is wider than the circular section of the rod. Alternatively, the curved portion of the rod has an ellipsoidal section and this section is wider than the circular section of the rod.

Due to the portion forming the curvature of the rod is flattened, the difference in value between the inner and outer radius of curvature is decreased, which reinforces its mechanical strength.

The present invention as well as its advantages will be better understood on reading the non-restrictive description which follows, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1a, 1b and 1c are respectively partial sectional views of a concrete pavement, a concrete beam and a barrier type "Jersey", each of the parts in question being reinforced using a curved reinforcing rod.

Figure 2 illustrates the machine as well as the different steps implemented along it to produce curved reinforcing rods.

Figure 3 illustrates in more detail the structure of the jig used in this machinery. Figure 4 illustrates the shape of a rod thus obtained, in the form of a spiral.

FIGS. 5a, 5b and 5c are perspective views which respectively illustrate a rod obtained by the known method currently used, a rod obtained by the method according to the invention, the curved portion of which is of rectangular section, and a rod obtained by the method according to the invention but whose curved portion has an ellipsoidal shape, the rods in question being all respectively obtained by sawing in appropriate places a rigid spiral as shown in Figure 4. Figure 6 is a perspective view of jigs used in the rotary frame of the machine used in the context of the present invention, this view also illustrating how the shoes can come to fit into each of the parallel paths in the template. FIG. 7 is a more detailed view of a group of shoes that can be used in the template illustrated in FIG.

Figure 8 is a side view of the rotary frame in which the rod is wound to be folded while being also flattened by the hooves. Figures 9a, 9b and 9c are views illustrating the shape that can have the curved rod according to the number of templates used and their respective positioning.

Figure 10 is a graph illustrating the improvements obtained on the mechanical properties of a rod according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Figures 1a, 1b and 1c illustrate the importance of incorporating curved reinforcing rods into concrete structures.

Thus, Figure 1a illustrates how a rod can be used to anchor a parapet (31) on the floor of a bridge (32).

Figure 1b illustrates how a curved reinforcing rod (30b) can be incorporated into a concrete beam (34) which is intended to carry loads. It will be understood that if the rods can withstand tensions to disengage from the concrete, the bearing capacity of the beam (34) can then be substantially increased.

Figure 1c illustrates how a curved reinforcing rod (30c) can be incorporated into a Jersey type barrier (36) used to protect the road edge.

As previously mentioned, the subject of the present invention is a new structure of curved reinforcing rods and a method for manufacturing them. As previously described, the method according to the invention consists in producing curved reinforcing rods as illustrated in FIGS. 1a to 1c described above, from a bundle of fibers (1) which are impregnated a binder polymer capable of curing the binder polymer in question is preferably a thermosetting resin.

As illustrated in FIG. 2, which shows usable machinery for the implementation of the method, the fibers (1) which are wound on the coils (2) upstream of the machine are unwound and brought to converge towards a device. saturation (4) by a tension exerted on them by a motorized frame (3). This device (4) consists of a tray (5) and guide rollers (6). It is used to wet the fibers (1) using the binder polymer which is preferably a thermosetting resin is contained in the tray (5). The fibers (1) wetted by the resin terminate their convergent strokes by passing through a calibrated orifice (7) to thereby form at this precise location, a bundle (8) of said parallel fibers (1) saturated with thermosetting resins whose the excess disgorged by the calibrated orifice (7) flows into a collection tank (9). At its exit from the calibrated orifice (7), the bundle (8) is then subjected to consolidation by means of two wires (10) tightly wound in a spiral around its structure. This consolidation can be obtained by means of a device (1 1) consisting of two son coils (12) mounted on two counter-rotating arms (13) in the axes of rotation of which the beam (8) is located. In this device (1 1), one of the consolidation son is dextrorotically wound while the other wire is wound in the opposite direction, or levorotatory.

Following the consolidation step, the fiber bundle saturated with resin and consolidated by the spirally wound wires, forms a rod which is then introduced from a rotary frame (15) comprising templates (14) on which the beam is spirally wound.

To do this, each template comprises a plurality of parallel paths on which the rod is wound in the form of a spiral.

In practice, the rotating frame (15) may comprise two or four templates. In the embodiment illustrated, particularly with reference to FIG. 8, the rotary frame (15) comprises four templates, which makes it possible to obtain a spiral (40) as shown in FIG. 4.

The spiral (15) thus obtained can then be cut along lines (42) as shown in dashed lines in FIG. 4. This makes it possible to obtain curved rods such as those particularly illustrated in FIG. 9a. However, it will be understood that when using a rotary frame comprising only two jigs (14), it is possible after cutting to obtain curved rods such as those illustrated in Figures 9b and 9c. The curved reinforcing rods that are obtained may therefore have, depending on the number of templates used and the type of cut, a J, L or U shape.

The steps just described are known per se and commonly used. In fact, the present invention differs from what has been described essentially in the fact that, once the capacity of the rotary frame has been reached, shoes (1 6) are set up and pressed in the paths of each of the jigs (14) in which is located the rod wound on the band of a turn to ensure a flattening of said rod at the place where the shoe is applied.

From a practical point of view, the parallel paths of the jigs (14) in which the fibers are wound so as to form the rod in the form of a spiral, may have a flat bottom or a curved bottom. In this case, the shoes are advantageously designed so as to have either a flat surface or a curved surface so as to give the part which is crushed a substantially rectangular shape as illustrated in FIG. 5b, or a ellipsoidal shape as illustrated in Figure 5c.

It will be understood, of course, that the shapes in question rectangular and ellipsoidal apply only in each curved section since it is only there that the shoes (1 6) come to apply.

It should be mentioned that the press step thus carried out using the shoes (1 6) takes place before the thermosetting resin has undergone its curing treatment. It is indeed important that the work done to obtain the desired flattening in support of the templates at the curvatures is carried out before the thermosetting resin has undergone its treatment in order to harden it and thus obtain the desired fibers in rigid form .

The assembly thus obtained, which therefore consists of the bundle (8) of saturated resin fibers wound on the jigs (14) fixed to the frame (15) and on which the shoes (1 6) are applied, is subsequently transferred to an oven that allows the temperature to increase to harden the thermosetting resin.

When the reaction of the thermosetting resin is completed, the frame (15) is removed from the oven, the shoes (1 6) are removed, the templates (14) are removed and the spiral (40) now become rigid is removed.

Subsequently, this spiral (40) can be used directly in its shape obtained as illustrated in Figure 4, or be cut into various portions as already described and illustrated in Figures 9a to 9c, according to the uses to which they are intended. FIG. 5a shows the curved portion of a rod obtained by the usual method whereas FIGS. 5b and 5c each show the curved portion of the same rod obtained according to the shape chosen for the hooves. In summary, the method according to the invention therefore consists in producing a curved reinforcing rod as described above, from a bundle of fibers using a binder polymer preferably consisting of a thermosetting resin. . The saturated fiber bundle of resin is pulled through a calibrated orifice that allows the excess resin to be removed. The bundle of fibers is then consolidated using at least two filaments that wrap it spirally helically, one spiral clockwise and the other counterclockwise around the saturated bundle. The saturated resin beam is then wound on at least two templates mounted on a rotating frame and in the paths of which shoes are applied to compress and deform the curved parts. The whole is then introduced into an oven, while the resin saturated fiber bundle is still under pressure. After sufficient time in the oven to the required temperature to cure the resin, the hooves are removed and the rod is removed from the jigs. It can subsequently be used as is, or can be cut into various portions depending on the use for which it is intended.

FIG. 10 shows a graph which illustrates the substantial improvement in the breaking strength expressed under the MPa value according to the ACI 440 B5 standard as a function of the flattening of the portion of the curved section of rods as illustrated in FIGS. Figures 5a and 5b. The rod thus used for this test was 1 6 mm (5/8 inch) in diameter. The materials used were fiberglass and a vinylester type resin as a thermosetting matrix. The resin contained an organic peroxide type catalyst to start and complete the polymerization reaction as well as other additives and fillers. The The major axis / minor axis ratio (1) was that of the conventional rod as shown in Figure 5a.

The value of resistance to voltage was of the order of 450. With the rod according to the invention as illustrated in FIG. 5b, the values of resistance to the voltage were of the order of 510 and 650 according to major axis / minor axis ratios of 1, 44 and 2.56 obtained thanks to the hooves.

As will be understood on the basis of what has been explained above, the fact that a flattening is done at the curvature of each rod is of great interest since it reduces the difference in values between the inner and outer radius of curvature at the level of the curvature, which reinforces the mechanical strength of the final product.

It goes without saying that various modifications could be made to the method which has just been described with reference to the accompanying drawings without departing from the scope of the present invention as defined in the appended claims.

Claims

1. A curved reinforcing rod having improved mechanical strength at the point of its curvature, characterized in that it is made from a bundle of fibers joined to one another by means of a binder polymer and in that it has rectilinear portions each having a same substantially circular section and a curved portion which is between the straight portions, the curved portion being flattened and having a substantially rectangular or ellipsoidal section.

2. The rod of claim 1, characterized in that the curved portion of the rod has a rectangular section and this section is wider than the circular section of said rod.

3. The rod of claim 1, characterized in that the curved portion of the rod has an ellipsoidal section and this section is wider than the circular section of said rod.

4. The rod according to any one of claims 1 to 3, characterized in that the fibers are polymeric, mineral, natural or metallic.

5. The rod according to any one of claims 1 to 4, characterized in that the binder polymer is of a thermosetting or thermoplastic nature.

A method for producing a curved reinforcing rod having improved mechanical strength at its curvature, said method comprising the steps of: (i) producing a straight rod of substantially circular section from a bundle of fibers by joining said fibers together with a binder polymer;

(iii) placing the shank placed on the fold template (s) under conditions where the fiber-binding polymer is allowed to harden; and

(iv) when the binder polymer is sufficiently hardened, removing the rod from the jig (s);

said method being characterized by comprising the further step of:

7. The method according to claim 6, characterized in that:

the folding of the rod takes place on at least two folding jigs on which the rod is wound in a loop, and

the flattening with the help of a shoe is done on each jig.

8. The method according to claim 7, characterized in that:

each folding template is provided with a plurality of parallel paths in which the rod is wound in the form of a turn, and

Flattening with a hoof is done in each path.

9. The method of claim 8, characterized in that it further comprises cutting the turn obtained elements having a shape of J, L or U, each element thus cut having its curved portion flattened.

10. The method according to any one of claims 6 to 9, characterized in that the flattening is performed so as to give a substantially rectangular or ellipsoidal section to each curved portion of the rod.

1 1. The method according to claim 10, characterized in that each curved portion of the rod has a rectangular section and this section is wider than the circular section of said rod.

12. The method of claim 10, characterized in that each curved portion of the rod has an ellipsoidal section and this section is wider than the circular section of said rod.

13. The method according to any one of claims 6 to 12, characterized in that the fibers are polymeric, mineral, natural or metallic.

14. The method of claim 13, characterized in that the binder polymer is of thermosetting or thermoplastic nature.

15. Use of a rod according to any one of claims 1 to 5 or obtained by the method according to any one of claims 6 to 14 for reinforcing a room or a concrete structure.