JPH07324288A - Corrosion-resistant coated pc strand having spiral depressed grooves and its corrosion-resistant processing - Google Patents

Abstract

PURPOSE:To obtain the corrosion-resistant PC strand having spiral depressed grooves and facilitated to charge a resin for the corrosion-resistant coating into the inner spaces by employing deformed PC steel materials as plural side wires for twisting on the outer periphery of a core for the PC strand. CONSTITUTION:A deformed PC steel material on whose outer periphery spiral depressed grooves 42 are formed is employed as a core wire 2. Plural side wires 3 where all or the outermost layer of the plural side wires 3 comprise the deformed PC steel materials are twisted on the outer periphery of the core wire in a single layer or in plural layers to form the PC strand 4. The PC strand 4 is heated and simultaneously allowed to pass through a synthetic resin extruder. Thus, a corrosion-resistant material 5 comprising a melted thermoplastic resin such as melted polyethylene, melted polypropylene or melted nylon is pressed in to the outer periphery of the core wire 2 through the spaces between the side wires 3 to form the corrosion-resistant coating layer on the whole periphery of the PC strand 4. The coated PC strand is subsequently inserted into a die for rotation molding to form depressed grooves 6 along the spiral depressed grooves 42 of the outermost layer side wires 3, thus obtaining the corrosion- resistant coated PC strand having the spiral depressed grooves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosion-coated PC strand with a spiral groove, which is mainly used for stress-introducing materials for prestressed concrete and suspension materials for cable-stayed bridges, and a method for anticorrosion processing thereof.

[0002]

2. Description of the Related Art In recent years, the outer surface of a PC strand has been coated with a synthetic resin material having adhesiveness, which has been inserted into a synthetic resin sheath to be used in a post-tension unbonding method, or coated with a synthetic resin. What has been developed to be used in a pre-tension bond method for embedding the above-mentioned material in concrete after tension is applied (JP-A 1-215528).
Issue).

Even if such a conventional PC strand is coated with a synthetic resin, there is a gap between the core wire forming the strand and the side wire twisted outside the core wire. There was a problem that water and air entered from the part and corroded the PC strand.

In order to solve this problem, in the production of PC strands, it is proposed that each single wire of the strand is coated with a synthetic resin in advance, the strands are twisted together to form a strand, and the outside thereof is coated with a synthetic resin. Has been done (Actual development 61-
144121 publication).

However, since this conventional PC strand is not subjected to the bluing treatment, there is a problem that the processing strain of the material due to the twisting process remains, it is easy to unravel, and the strength is not stable, and the core wire and the side wire are also problematic. Since the entire circumference of is separately covered, the synthetic resin layer is interposed between the core wire and the side wire, and when pulled, this synthetic resin layer is compressed and the interval between the wires is narrowed, There is a problem that the elongation of the strand becomes large.

In order to solve such a problem, a PC strand in a completed state itself is used, and when this is passed through a synthetic resin extrusion molding machine, a rust preventive coating is applied to the molding machine. The head part is provided, and the high pressure (1
A technique has been developed in which the resin is press-fitted into the internal voids of the PC strand by applying a pressure of about 00 kgf / cm ² ) or more, and a synthetic resin coating is applied to the entire outer circumference of the core wire and the side wire outside the core wire ( Japanese Patent Laid-Open No. 5-98742
And Japanese Patent Application No. 5-37331).

[0007]

However, in the rust preventive treatment method by press-fitting the molten synthetic resin into the strand by the above-mentioned conventional pressurization, the molten synthetic resin material is applied from the gap between the side wires to the outer periphery of the core wire. Since a resin material with high viscosity and a twisted strand with a high degree of jointing between side lines, a large pressure force is required to press it in, and there is a limit to the rustproofing capacity. there were.

Further, the above-mentioned conventional method is intended for a structure in which a single side wire is twisted around the outer circumference of the core wire,
It cannot be applied to a multi-strand PC strand in which a twisted side wire is a middle layer and a plurality of outer layer wires are twisted on the outside thereof.

In view of the conventional problems described above, the present invention provides a method in which a PC strand is passed through a synthetic resin extrusion molding machine and the synthetic resin material is pressed into the central portion of the strand by pressurization. The purpose is to provide a rust-proof coated PC strand with a spiral groove and a rust-proof processing method, which can be applied to pressure-resistant rust-proof coating even to the inside, and which can also be applied to multi-strand PC strands that could not be done conventionally. is there.

[0010]

The features of the anticorrosion coated PC strand with spiral groove according to the present invention for solving the above-mentioned conventional problems and achieving the intended purpose are as follows. On the outer circumference of the wire, a PC strand of multiple side wires twisted together,
In a rust preventive coated PC strand obtained by closely adhering a rust preventive coating layer made of a thermoplastic synthetic resin on the entire circumference of the core wire and each side wire, a part or all of the side wire is integrally formed with an uneven shape on its outer peripheral surface. It is a deformed PC steel material and has a groove along the spiral groove between the side lines on the outer periphery of the rust-proof coating layer (claim 1), and secondly, on the outer periphery of the core wire. , A PC strand formed by twisting a plurality of side wires into a plurality of layers is a deformed PC steel material in which some or all of the side wires are integrally formed with an uneven shape on the outer peripheral surface, and each of the core wire and the side wires of each layer is A spiral groove having a rust preventive coating layer made of a thermoplastic synthetic resin adhered to the entire circumference, and having a groove along the spiral groove between each side line of the outermost layer on the outer circumference of the rust preventive coating layer. The grooved rustproof coated PC strand is present (Claim 2).

The PC strand rust preventive coating method according to the present invention is characterized in that a plurality of side wires are twisted in a single layer or in a plurality of layers on the outer circumference of the core wire, and at least a part of the side wires is uneven on the outer peripheral surface. A PC strand made of a deformed PC steel material having an integrally molded shape is passed through a synthetic resin extrusion molding machine while being heated, and a thermoplastic composition in a molten state while being pressed by a pressure head of the synthetic resin extrusion molding machine. A resin material is press-fitted into the outer circumference of the core wire from between the side wires, and the thermoplastic synthetic resin material is adhered to the entire circumference of the core wire and each side wire of the strand, and then passed through a rotating molding die to form a synthetic resin layer. The outer peripheral surface is formed with a groove along the spiral groove between the side lines of the outermost layer (claim 5). The PC strand may be made of a deformed PC steel material for the core wire, or may be used for all side wires or may be used for various arrangements such as alternate side wires (claims 3, 4, 6, 7).

[0012]

In the present invention, since the side wire is a deformed PC steel material, when the PC strands are twisted together, the side wires are twisted together with a strong joining force. A large number of voids are positively formed, and when the voids are passed through a synthetic resin extrusion molding machine, the molten synthetic resin is easily flown into the outer circumference of the core wire from the voids due to the pressure applied by the pressure head portion. In addition, the PC strands are passed through an extruder while being heated, so that the fluidity of the synthetic resin material does not decrease, the flow into the core wire is smooth, and a strong adhesion is obtained after cooling and solidification. To be Further, before the synthetic resin is cooled and solidified, it is passed through a rotatable molding die to form a groove along the spiral groove between the lateral lines on the outer peripheral surface.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a first embodiment of an anticorrosion-coated PC strand with spiral grooves according to the present invention. This anticorrosion-coated PC strand 1 with spiral grooves has one core wire 2 and six side wires. It consists of PC strands 4 made of 3, 3 ... And a rust preventive material 5. The PC strands 4 are formed on the outer circumference of the core wire 2 made of PC steel, and the side wires 3, 3 ... Also made of PC steel.
... are twisted in a single arrangement in a spirally wound arrangement. As shown in FIG. 3, each lateral wire 3 is made of a deformed PC steel material in which a plurality of concave grooves 6 are continuously integrally formed on the outer peripheral surface.

The rust preventive material 5 covers the entire outer peripheries of the core wire 2 and the side wire 3, and polyethylene resin is used as the material, but polypropylene resin or polyethylene-polypropylene copolymer and The modified product and a thermoplastic synthetic resin such as nylon resin can be used.

On the outer peripheral surface of the rust preventive material 5, side lines 3, 3 ...
A groove 42 is formed along the spiral groove on the outside of the space.

FIG. 2 shows an anticorrosion coating P with a spiral groove according to the present invention.
The second embodiment of the C strand is shown. This rust-proof coated PC strand 11 with spiral groove has nine core side wires 13, 13 twisted in a spiral arrangement on the outside of one core wire 12, and Nine outer layer side wires 14, 14 ... Are composed of a PC strand 15 of a multi-winding structure and a rust preventive material 5, which are twisted in a spiral arrangement on the outer periphery thereof. Each of the middle-layer side wires 13 is made of the deformed PC steel material shown in FIG. 3 described above, and the core wire 12 and each outer-layer side wire 14 have a normal P surface with a smooth outer peripheral surface.
C steel material is used. Further, on the outer peripheral surface of the rust preventive material 5, the groove 4 is formed along the spiral groove on the outer side between the outer side lines 13, 13 ,.
3 is formed.

In addition to the above, the outer layer side wire 14 may also be a modified PC steel material as shown in FIG. Further, as the deformed PC steel material, in addition to that shown in FIG. 3, a circular or other recess 16 is integrally formed on the outer surface as shown in FIG. 4, and a short recess in a direction orthogonal to the longitudinal direction as shown in FIG. One in which the groove 17 is integrally formed, and one in which a plurality of meandering concave grooves 18 are integrally formed on the outer periphery in the longitudinal direction as shown in FIG.
Various types can be used.

Next, an embodiment of the rustproofing method according to the present invention will be described with reference to the drawings starting from FIG.

First, the strand material 23 consisting of the PC strand 4 or 15 before the anticorrosion coating of the anticorrosion coated PC strand 1 or 11 with spiral groove as shown in FIGS. The PC strand coil 21 wound around () is placed on the feeding device 22 so that the PC strand material 23 can be continuously fed.

The PC strand material 23 is successively drawn out and heated through a heating device 24 while being heated by the extruder 2.
Introduce to 5. This heating is maintained at a temperature of about 200 ° C.

In the extrusion molding machine 25, as shown in FIG. 8, an auxiliary pressing head portion 27 is connected to the tip of the cross head portion 26, and a molding die 28 is attached to the tip thereof.

The PC strand material 23 heated through the heating device 24 is transferred to the crosshead portion 2 of the extruder 25.
The auxiliary pressing head portion 27 and the molding die 28 at the tip thereof are passed from 6 and are joined to a leading wire (not shown) here. The leading wire is taken up by the take-up device 29 and taken up by the leading wire take-up device 30 on the leading wire reel 31.

On the other hand, the rust preventive material 5 made of a thermoplastic synthetic resin material is about 200 ° C. in the extruder 25 in this embodiment.
Is melted by heating and is press-fitted into the auxiliary pressure head part 27 from the cross head part 26. As the thermoplastic synthetic resin material, in addition to polyethylene resin as described above, polypropylene resin or polyethylene, copolymers of polypropylene and polypropylene, and modified resins thereof, and synthetic resins such as nylon resin can be used.

The auxiliary pressurizing head portion 27 connected to the cross head portion 26 can be heated by a heater 32 (shown in FIG. 8), and the molten thermoplastic synthetic resin is not cooled but inside the PC strand material 23. However, when the thermoplastic synthetic resin is an amorphous polymer having a low molecular weight, it does not need to be heated.

The rust preventive material 5 made of thermoplastic synthetic resin extruded into the cross head portion 26 is used as the auxiliary pressure head portion 27.
The PC strand material 23 is covered with the molding die 28 attached to the tip of the PC strand material 23 and exits. At this time, the resin pressure is increased to a certain level or more in the auxiliary pressurizing head portion 27, and this increase in pressure causes the PC strand material 23 to rise. In the case of the PC strand 4 shown in FIG. 10, the molten rust preventive material 5 enters into the inner space a between the side wires 3, 3 ... Not only the side wire 3 but also the outer circumference of the core wire 2 is covered. The inflow of the rust preventive material 5 between the side lines 3 and 3 is made smooth and sufficient because a large gap is formed between the side lines because each side line 3 has a different shape.

When the PC strand material 23 is the multi-stranded PC strand shown in FIG. 11, the outer layer side wire 1
The rust preventive material 5 flows in from between 4, 14, ..., Further, it passes through between the middle layer side wires 13 and 13 and reaches the outer periphery of the core wire 12, and the inner space b between the middle layer side wire 13 and the outer layer side wire 14 and the core wire 12 are formed. And the inner space a between the middle-layer side line 13 and the lines 12, 13, 14
The entire surface of is covered with the rust preventive material 5.

The resin pressure in the auxiliary pressing head portion 27 when each of these PC strand materials 23 is used is shown in FIG.
In the case of the PC strand material shown in (1), when the resin material is polyethylene resin, 80 to 100 kgf / cm ²
In the case of the multi-strand PC strand material shown in FIG. 11, it is required to be 100 kgf / cm ² or more.

The length L ₂ of the auxiliary pressurizing head portion 27 is
It is longer than the conventional die length L ₁ of the crosshead portion. This may be 2 times or more of L ₁ in the case of a low molecular weight amorphous polymer, but is preferably 3 times or more of L ₁ in the case of other thermoplastic synthetic resins. Then, in the case of 5 times or more of L ₁ , it is preferable to perform redrawing again through the auxiliary forming die 34. This is because, when it exceeds 5 times L ₁ , the coating layer rises only by the die 28 due to overpressure, and it is difficult to obtain a predetermined outer layer.

Further, as shown in FIG. 9, each of the molding dies 28 and 34 is molded into a cross-sectional shape having a convex portion d on the inner peripheral surface along the spiral concave groove between the lateral lines of the outermost layer of the PC strand 23,
As shown in FIG.
It is rotatably supported via 1 and is swung by the movement of the PC strand 23 along the spiral groove on the outer periphery thereof. As a result, as shown in FIGS. 1 and 2, the anticorrosion-coated PC strand with spiral grooves having spiral grooves 42 and 43 formed along the outer surface of the PC strands 4 and 15 along the spiral grooves on the outer surface is obtained. .

In some cases, as the molding die 28 on the side of the auxiliary pressure head, one having a cylindrical inner surface is fixed and used, and only the molding die 34 is used on the inner surface of the spiral groove of the PC strand outer peripheral surface. It is also possible to have a convex portion d that is matched with.

As described above, the anticorrosion-coated PC strand with the spiral groove having the anticorrosion material 5 made of the thermoplastic synthetic resin is formed into the molding die 28 or, if necessary, the auxiliary molding die 3
After being extruded from 4, it is cooled through the cooling device 35,
The winding device 36 winds the reel 37. 3 in the figure
Reference numeral 9 is a pressure gauge.

After passing through the cooling device 35, the corona electric discharge machine 38 may be passed through. This is to apply corona discharge in order to appropriately roughen the surface of the PC strand coated with anticorrosion, particularly when the adhesion to concrete is required.

The anticorrosion-coated PC strand with a spiral groove produced in this manner has the anticorrosion coating layer completely adhered to the entire circumference of the core wire, the side wire and the outer layer wire as shown in FIGS. You can get what you did.

The rust-proof coated PC strand with spiral grooves and the PC strand before rust-proof coating used in the rust-proof processing method of the present invention are, in addition to the above, core wires 2 and 12 as shown in FIGS. A deformed PC steel material may be used for all of the side wires 3, 13, and 14, and a deformed PC steel material may be used for the middle-layer side wire 13 and the core wire 12 as shown in FIG. 14, and further as shown in FIG. All side lines 13 and 14 except 12
Alternatively, a deformed PC steel material may be used.

Furthermore, as shown in FIG. 16, it is possible to adopt various arrangements such as alternate side wires 3 made of deformed PC steel.

The PC strand may be a multi-strand such as 28-strand, 37-strand and 46-strand in addition to the above-mentioned 7-strand and 19-strand.

[0037]

As described above, in the present invention, the PC
Since the deformed PC steel material is used for the side wires on the outer circumference of the core wire of the strand, the void ratio between the side wire gaps leading to the inner space formed between the outer circumference of the core wire and the side wires is high, and moreover, it is formed substantially uniformly over the entire circumference. Since the resin material that is heated and melted flows smoothly and evenly when it passes through the head section under the pressure condition of the synthetic resin extrusion molding machine, a sufficient amount of anticorrosion-coated resin even under low pressure conditions It has become possible to fill the inner voids with the rust-preventive coating resin for the multi-twisted PC strands which could not be conventionally applied.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of a rustproof coated PC strand with spiral groove according to the present invention.

FIG. 2 is a sectional view of a second embodiment of the same.

FIG. 3A is a side view showing an example of a lateral line in the first and second embodiments, and FIG. 3B is a sectional view thereof.

FIG. 4 (a) is a side view of another example of the same lateral line, and (b).
Is a sectional view of the same.

FIG. 5 (a) is a side view of still another example of the same lateral line,
(B) is the same sectional view.

FIG. 6 (a) is a side view of still another example of the lateral line of the above,
(B) is the same sectional view.

FIG. 7 is a diagram showing a schematic process of an example of the method of the present invention.

FIG. 8 is a sectional view of the extruder part of the above.

9 is a cross-sectional view taken along the line AA in FIG.

FIG. 10 is a cut end view of an example of a PC strand material used in the present invention.

FIG. 11 is a cut end view of still another example of the above.

FIG. 12 is a cut end view of still another example of the above.

FIG. 13 is a cut end view of still another example of the above.

FIG. 14 is a cut end view of still another example of the above.

FIG. 15 is a cut end view of still another example of the above.

FIG. 16 is a cut end view of still another example of the above.

[Explanation of symbols]

 1,11 Spiral grooved anticorrosion coated PC strand 2,12 Core wire 3 Side wire 4,15 PC strand 5 Anticorrosion material 6 Groove 13 Middle layer side wire 14 Outer layer side wire 16 Recess 17 Short recessed groove 18 Meandering groove 21 PC strand Coil 22 Feeding device 23 Strand material 24 Heating device 25 Extrusion molding machine 26 Crosshead part 27 Auxiliary pressure head part 28 Forming die 29 Pulling device 30 Leading wire winding device 31 Leading wire reel 32 Heater 34 Auxiliary forming die 35 Cooling device 36 Winding device 37 Reel 38 Corona discharge machine 39 Pressure gauge 40, 41 Bearing 42, 43 Spiral groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuyoshi Chigiri 1-14 Nagatano-cho, Fukuchiyama-shi, Kyoto Hien Electric Works Co., Ltd. Fukuchiyama factory (72) Inventor Yukihiro Higashi 1-14, Nagano, Fukuchiyama-shi, Kyoto Facility Hien Electric Works Fukuchiyama Factory

Claims (7)

[Claims] 1. A rust preventive coating formed by tightly adhering a rust preventive coating layer made of a thermoplastic synthetic resin on the entire circumference of the core wire and each side wire of a PC strand formed by twisting a plurality of side wires around the outer circumference of the core wire. In the PC strand, a part or all of the side wire is a deformed PC steel material in which an uneven shape is integrally formed on the outer peripheral surface thereof, and along the spiral groove between the side wires on the outer periphery of the anticorrosion coating layer. Anticorrosion coated PC strand with spiral groove having a groove. 2. A PC strand formed by twisting a plurality of side wires in a plurality of layers on the outer circumference of a core wire, wherein a part or all of the side wires is a deformed PC steel material integrally formed with an uneven shape on the outer peripheral surface, The rust preventive coating layer made of a thermoplastic synthetic resin is adhered to the entire circumference of each of the core wire and the side wire of each layer,
Further, the rust preventive coating P with a spiral groove having a groove along the spiral groove between the side lines of the outermost layer on the outer periphery of the rust preventive coating layer.
C strand. 3. The anticorrosion-coated PC strand with spiral grooves as claimed in claim 2, wherein a deformed PC steel material is used for the middle layer side wires excluding the outer layer side wire among the side wires of each layer. 4. The anticorrosion-coated PC strand with spiral groove as claimed in claim 1, wherein the deformed PC steel material is used for the core wire. 5. A PC strand made of a deformed PC steel material in which a plurality of side wires are twisted in a single layer or a plurality of layers around the outer circumference of a core wire, and at least a part of the side wires is integrally formed with an uneven shape on the outer peripheral surface. Through a synthetic resin extrusion molding machine while heating, and press the molten synthetic resin material in the molten state while pressurizing it with the pressure head part of the synthetic resin extrusion molding machine from between the side wires to the outer circumference of the core wire. Then, after the thermoplastic synthetic resin material is adhered to the core wire of the strand and the entire circumference of each side wire, it is passed through a rotating molding die, and the spiral groove between the side wires of the outermost layer is formed on the outer peripheral surface of the synthetic resin layer. Rust-proof coated PC with spiral groove characterized by forming a groove along the groove
Strand rust prevention processing method. 6. A modified PC on all lateral lines of a PC strand.
The method for rust-proofing a rust-proof coated PC strand with a spiral groove according to claim 5, which is made of a steel material. 7. The core wire is a deformed PC steel material.
Alternatively, the method for rust-proofing a rust-proof coated PC strand with a spiral groove according to item 6.