Bent reinforcement rod having improved mechanical strength at the bending point thereof, and method for producing same

Abstract

The invention relates to a bent rod having improved mechanical strength at the bending point thereof, characterized in that it is made from a bundle of twisted fibers that are secured together using a binder matrix preferably consisting of a thermosetting resin. The invention also relates to a method and device for producing said rod.

Claims

1. A method for producing a curved rod having mechanical resistance at the location of its curvature, said method comprising the following steps: (i) pulling a set of fibers according to a movement of torsion through a bin containing a liquid matrix so as to form a strand of twisted fibers saturated with said matrix; (ii) winding into a helix about the strand of twisted fibers a thread or other medium in the clockwise direction and another thread or other medium in an anticlockwise direction so as to form a flexible envelope; (iii) bending the rod about at least one bending mount, giving the rod a curved portion at a level of said at least one mount; (iv) putting into place the rod placed on said at least one mount, in conditions where the matrix binding the fibers can harden; and (v) when the binding matrix is hardened, removing the rod from said at least one mount.

2. The method according to claim 1, and in pulling the fibers to form a strand, the fibers are twisted by means of at least one carrousel on which spools of said fibers are mounted.

3. The method according to claim 2, the carrousel having a revolution frequency which is variable and subject to the longitudinal displacement of the strand of fibers.

4. The method according to claim 2, and passing the fibers through holes made in a rotating device, forming a sealing joint at the inlet of the bin containing the liquid matrix.

5. The method according to claim 4, the rotating device having a rotation speed identical to the rotation speed of the at least one carrousel.

6. The method according to claim 4, the diameter of the holes through which pass the fibers originating from the spools of the carrousel having a dimension which is sufficiently large to let the fibers from the carrousel slide through, but sufficiently small to restrict the flow of the liquid matrix from the saturation bin.

7. The method according to claim 1, the winding into a helix of two threads around the strand of fibers saturated by the liquid matrix being accomplished by means of at least two spools that move by releasing their threads under tension along a circular path whose axis is that of the strand of fibers.

8. The method according to claim 1, the bending of the rod being made on at least two bending mounts on which the rod formed by the strand of fibers is wound into a loop.

9. The method according to claim 8, each bending mount being provided with a plurality of parallel segments in which the rod formed by the strand of fibers is wound in the form of a helix.

10. The method according to claim 1, the rod obtained being cut to have at least one section in the shape of J, U, C or L, or a continuously and arbitrary sequence of such shapes.

11. A method for producing a curved rod having mechanical resistance at the location of its curvature, said method comprising the following steps: (i) pulling a set of fibers according to a movement of torsion through a bin containing a liquid matrix so as to form a strand of twisted fibers saturated with said matrix; (ii) winding into a helix about the strand of twisted fibers a thread or other medium in the clockwise direction and another thread or other medium in an anticlockwise direction so as to form a flexible envelope; (iii) bending the rod about at least one bending mount, giving the rod a curved portion at a level of said at least one mount; (iv) putting into place the rod placed on said at least one mount, in conditions where the matrix binding the fibers can harden; and (v) when the binding matrix is hardened, removing the rod from said at least one mount; (vi) in pulling the fibers to form a strand, twisting the fibers by means of at least one carrousel on which spools of said fibers are mounted; and (vii) bending of the rod on at least two bending mounts on which the rod formed by the strand of fibers is wound into a loop.

12. A method for producing a curved rod having mechanical resistance at the location of its curvature, said method comprising the following steps: (i) pulling a set of fibers according to a movement of torsion through a bin containing a liquid matrix so as to form a strand of twisted fibers saturated with said matrix; (ii) winding into a helix about the strand of twisted fibers a thread or other medium in the clockwise direction and another thread or other medium in an anticlockwise direction so as to form a flexible envelope; (iii) bending the rod about at least one bending mount, giving the rod a curved portion at a level of said at least one mount; (iv) putting into place the rod placed on said at least one mount, in conditions where the matrix binding the fibers can harden; and (v) when the binding matrix is hardened, removing the rod from said at least one mount; (vi) in pulling the fibers to form a strand, twisting the fibers by means of at least one carrousel on which spools of said fibers are mounted; (viii) bending of the rod on at least two bending mounts on which the rod formed by the strand of fibers is wound into a loop; and (ix) winding into a helix of two threads around the strand of fibers saturated by the liquid matrix being accomplished by means of at least two spools that move by releasing their threads under tension along a circular path whose axis is that of the strand of fibers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1a and 1b respectively show a strand of rectilinear fibers such as used in a classical construction rod and a strand of twisted fibers as used in the present invention.

(2) FIGS. 2a and 2b respectively show a portion of a rectilinear rod and a portion of a curved rod as they present themselves at the end of production.

(3) FIG. 3 is a graphic which shows the relation that exists between the degree of torsion of the fiber strand and the mechanical resistance of a rod manufactured by means of such a strand.

(4) FIG. 4 shows the overview of the device which enables the production of a rod such as the one claimed in the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) As previously indicated, the present invention has as an object a reinforcement rod for concrete, composed of fibers drenched in a binding matrix and comprising a central bundle of twisted fibers.

(6) To help in better understanding the description of the invention claimed, FIG. 1 a shows a conventional and already known rod, which comprises a strand of rectilinear fibers (1) which are held amongst them provisionally by means of a flexible envelope composed of two wound threads (2).

(7) FIG. 1b shows a rod according to the invention which distinguishes itself from the conventional rod in that the fibers (3) of the strand are twisted and are held amongst each other provisionally by a flexible envelope composed of two wound threads (2).

(8) FIG. 2a shows how the strand of twisted fibers and the flexible envelope composed of two wound threads such as illustrated in FIG. 1b, present themselves when everything is soaked with a binding matrix such as a thermohardening polymer (4) in its liquid form.

(9) When the strand soaked with polymer (4) such as shown in FIG. 2a is bent and subjected to a suitable thermal treatment, it forms a curved rigid rod such as the one shown in FIG. 2b with rectilinear sections (5) or arbitrary curvatures (6).

(10) FIG. 3 demonstrates that the degree of torsion of the strand of fibers (3), such as shown in FIGS. 1b, 2a and 2b, enables to increase the mechanical resistance in the curved portion of a rod in comparison to a rod of conventional construction of same dimension and manufactured with the same materials. In the specific case illustrated in FIG. 3, the rod having been tested had a section of 71.3 mm.sup.2 and had been built by means of a strand of 30 threads of roving of glass fibers saturated with polyester resin.

(11) FIG. 4 shows the mechanical device through which such a rod can be manufactured. A carousel (7) which supports the multitude of spools (8) of glass fibers turns at the same speed as the perforated disk (10) through which the fibers (8) pass when they are pulled by the rotating disk (14). This pulling movement that unwinds the fibers (9) from the spools (8) makes the fibers pass in a bin (11) which is thus saturated with liquid matrix of said fibers. The strand (12) thus saturated with the liquid matrix becomes consolidated by two threads wound by the spools mounted on motorized arms (13) which turn about the strand, one in a clockwise direction and the other in an anticlockwise direction. The strand thus saturated and consolidated is wound by the mounts (15) mounted on the rotating disk (14). Afterwards, the disk (14) is subject in an oven to a thermal treatment that hardens the resins. The rod is removed from the mount and optionally cut to produce rigid and curved rods such as the one shown in FIG. 2b.