JPH0842061A - High-adhesion rustproof covered pc strand and machining method thereof - Google Patents

Abstract

PURPOSE:To display adhesion with concrete sufficiently by covering the internal air gaps and outer circumference of a PC strand, in which a plurality of single element wires are intertwisted, with a rust preventive material consisting of a thermoplastic synthetic resin. CONSTITUTION:Side wires 4 as six single element wires are intertwisted on the outer circumference of a core wire 3 as a single element wire, thus shaping a PC strand 1. The internal air gaps of the PC strand 1 are buried, and the outer circumferences of the core wire 3 and the side wires 4 are covered with a rust preventive material 2 composed of a polyester resin, etc. Spiral recessed grooves 5 corresponding to the recessed sections of the PC strand 1 are malded to the outer circumferential surface of the rust preventive material 2, and small projecting stripes 6 are molded integrally in the axial direction while being continued to the spiral recessed grooves 5. Accordingly, adhesion to concrete and solidifying grout can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-adhesion-corrosion-prevented PC strand having improved adhesion to concrete and solidifying grout when used mainly as a stress-introducing material for prestressed concrete, and a processing method thereof.

[0002]

2. Description of the Related Art In recent years, rust preventive coated PC strands have been used as a stress introducing material for prestressed concrete. For this type of rustproof coated PC strand, insert this into a synthetic resin pipe and
When used as a so-called unbonded PC strand in which a gap is filled with the C strand and filled with a lubricant,
When the C strand is directly embedded in the concrete in a tensioned state, or is passed through a sheath in the concrete, and after being tensioned, it is used as a bond type PC strand that is integrated with the concrete by filling a solidifying grout into the sheath. There is.

However, since the conventional PC-coated anticorrosion strand has an outer peripheral surface covered with an anticorrosive material made of synthetic resin,
Its surface is smooth and its adhesion to concrete is low. For this reason, when it is used as a bond type PC strand, when bending stress acts on the concrete member, P
There is a problem that the C strands and the concrete are peeled off and slide, and as a result, the bending resistance of the concrete member is reduced.

As a solution to this problem, conventionally, before solidification of the anticorrosion coating material, a solid material such as sand is sprayed on the surface thereof, or the solid material is mixed in advance with the anticorrosion material. Some have tried to improve the adhesion between concrete and rust preventive materials.

[0005]

However, if the projections made of solid material such as sand are present on the surface of the PC strand as described above, the PC strands come into contact with the inner surface of the sheath during the tensioning work, and the frictional force becomes large, resulting in the work. In addition to the deterioration of the property, there was a problem that the solid matter fell off and the rust preventive coating was damaged.

In view of the above conventional problems, the present invention is a rust preventive that exerts sufficient adhesion to concrete without deteriorating workability in tension work and damaging the rust preventive coating. The purpose of the present invention is to provide a coated PC strand and a processing method thereof.

[0007]

The features of the high adhesion rust preventive resin PC strand of the present invention for solving the above conventional problems are that the internal voids of the PC strand in which a plurality of single strands are twisted and The outer periphery is covered with a rust preventive material made of a thermoplastic synthetic resin, and the outer peripheral surface has a spiral groove corresponding to the spiral concave portion of the PC strand outer periphery, and the outer peripheral surface including the inside of the spiral concave groove is continuous. It is equipped with a large number of small ridges.

Further, the processing method of the present invention is characterized in that the PC strand is preheated to a temperature suitable for deposition of an anticorrosive material made of a molten synthetic resin material, and the preheated PC strand is crosshead-type synthesized. A primary deposition step in which the rust preventive material is deposited through the resin extrusion molding machine including the internal voids of the PC strand by pressure, and the PC strand after the primary deposition is passed through a molding die to form a PC on the outer peripheral surface. A cross-head type synthesis using a shaping process for adjusting a shape having a groove corresponding to a spiral recess on the outer circumference of the strand, and a PC strand shaped by the shaping process using a molding die having a large number of recesses on the inner circumference. P after shaping through a resin extrusion molding machine
Secondary deposition step of depositing a molten rust preventive material cylinder having a large number of small ridges continuously on the outer periphery of the C strand, and cooling the PC strand after the secondary deposition to solidify the rust preventive material It goes through the process.

[0009]

The rust preventive coated PC strand according to the present invention has a P outer peripheral surface when embedded in concrete or solidifying grout.
The column groove corresponding to the spiral recess on the outer circumference of the C strand is mechanically fitted to the concrete or grout, whereby the movement of the PC strand in the axial direction is prevented, and the small ridge on the entire peripheral surface is mechanically Increase the engagement. When the small ridges are in the direction intersecting the spiral direction of the spiral groove,
The twisting of the PC strands along the spiral groove is prevented by the small ridges, and higher adhesion is obtained.

In the processing method according to the present invention, P
By passing the C strands through the crosshead in the first deposition step, the molten rust preventive material is pressurized and filled in the voids between the individual strands of the PC strands. At this time, the rust preventive material adheres to the outer peripheral surface to a thickness greater than necessary,
In the shaping step, excess rust preventive material is peeled off by passing through the molding die, and the shape of the spiral recessed portion on the outer peripheral surface of the PC strand is raised on the outer peripheral surface. This is further passed through the crosshead in the secondary deposition step, so that the molding die on the inner surface of the tip covers the cylindrical molten rust-preventive material cylinder having the small ridges formed on the outer periphery, which is the above-mentioned spiral recess. By closely adhering along the outer peripheral surface of the primary coated PC strand having, the rust preventive coating having a spiral concave groove on the outer peripheral surface and having a large number of small ridges continuously formed.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

1 to 3 show a first embodiment of a rust preventive coated PC strand according to the present invention. In the drawings, 1 is a PC strand and 2 is a rust preventive material. The PC strand 1 is configured by twisting six side wires 4, 4, ..., Which are single wires, around the outer circumference of a core wire 3, which is a single wire. The rust preventive material 2 fills the internal voids of the PC strand 1 and the core wire 3
And the outer periphery of the side line 4 is adhered, and a concave groove 5 is formed on the outer peripheral surface along the spiral concave groove of the outer periphery of the PC strand 1. Polyethylene resin is used as the material of the rust preventive material 2, but other than this, polypropylene resin or a copolymer of polyethylene / polypropylene and its modified product, or a nylon resin, or a thermoplastic synthetic resin such as vinyl chloride can be used.

Further, the PC strand 1 is provided on the outer periphery of the rust preventive material 2.
A large number of small ridges 6, 6, ... Which are continuous in the axial direction of are formed.

The small ridges 6 are provided in the axial direction of the PC strand 1 as described above, and as shown in FIG. 4, the spiral direction is opposite to the spiral direction of the concave groove 5, that is, the concave groove 5. It may be various directions such as a direction orthogonal to the direction.

In addition to the above-mentioned 7-strand twist, the PC strand 1 is a multi-strand twist such as a 3-strand twist without using a core wire,
It is possible to use a multi-stranded one such as 19 strands in which side wires are twisted in a multiple arrangement around the core wire.

Next, an example of the embodiment of the processing method according to the present invention will be described with reference to the drawings.

FIG. 5 shows the outline of the method according to this embodiment, in which the PC strand 1 before rust prevention coating is the reel 21.
And is placed on the feeding device 22. And. The tip is passed through a feeding device 23, a heating device 24, a crosshead-type first synthetic resin extrusion molding machine 25, a molding auxiliary die 26, and a crosshead-type second synthetic resin extrusion molding machine 2.
7 and a cooling device 28, and a take-up device 29 and a reel 31 of a take-up device 30.

The heating device 24 preheats the PC strand 1 to a temperature slightly higher than the melting temperature of the resin described below,
The strand 1 is passed through a first synthetic resin extrusion molding machine 25 while maintaining its temperature so that primary deposition is performed. The extrusion molding machine 25 is attached to the tip of the crosshead 32 as shown in FIG. The auxiliary pressure head 33 is connected, and a molding die 34 is attached to the tip thereof.

Further, a heater 36 is installed on the outer periphery of the auxiliary pressure head 33 to heat it to a temperature at which the molten state of the resin inside is maintained. However, when the thermoplastic synthetic resin used is an amorphous polymer having a low molecular weight, heating is not required on purpose.

In the first synthetic resin extrusion molding machine 25 thus constructed, the rust preventive material 2 made of the thermoplastic synthetic resin extruded into the cross head 32 is used as the auxiliary pressure head 33.
Enter the PC from the molding die 34 attached to the end
The strand 1 is coated and then discharged. At this time, the resin pressure is raised in the auxiliary pressure head 33 to a certain level or more, and by this pressure rise, in the case where the PC strand 1 is 7-twisted as shown in FIG. .. to fill the inner space between the outer circumference of the core wire 3 and the side wires to cover not only the side wire 4 but also the outer circumference of the core wire 3.

As shown in FIG. 6, the auxiliary molding die 26 is rotatably supported by a holder 37, and its inner surface shape is shaped so that its cross section matches the outer shape of the PC strand 1 as shown in FIG. Are formed on the inner surface thereof with spiral side recesses 35, 35 ... Fitting the side lines 4, 4, ... And formed into a shape larger than the PC strand 1 by about 0.1 to 0.2 mm. It is designed to be heated. In the auxiliary molding die 26, the portion where the rust preventive material 2 has risen is scraped off by being pressed and extruded in the auxiliary pressurizing head 33, and as shown in FIG.
It is shaped so that the rust preventive material 2 is left on the outer periphery of the C strand 1 to a thickness of 0.1 to 0.2 m / m. As the second synthetic resin extrusion molding machine 27, an ordinary crosshead type synthetic resin extrusion molding machine having no auxiliary pressure head as shown in FIG. 9 is used, and its inner surface has a circular shape as shown in FIG. A molding die 40 that is molded and has a large number of recesses 39 on its inner peripheral surface is used, and a decompression device that decompresses the inside by a vacuum pump 42 is connected to the rear end of the crosshead 41.

In the extrusion molding machine 27, the PC strands coming out from the auxiliary molding die 26 in a state where the rust preventive material 2 is thinly left on the outer peripheral surface of the PC rust preventive material 2 is in a molten state. The outer surface of the molten rust preventive material tube 43 is covered with the molten rust preventive material cylinder 43, and the inner surface of the molten rust preventive material tube 43 is adhered integrally. Since the strips 6, 6 ... Are formed along the outer peripheral surface of the PC strand 1 after being formed, a spiral groove 5 corresponding to the recess of the PC strand 1 is formed on the surface as shown in FIG. A small ridge in the axial direction is continuously formed on the surface.

In addition, as shown in FIG.
Is rotatably attached to the crosshead 41, and is forcedly rotated by the motor 44, and its rotation speed is adjusted, so that the small ridges 6 in a direction intersecting the spiral groove 5 at an appropriate angle. 6 ... can be formed.

In this way, after the molten rust preventive material cylinder 43 having the small ridges 6, 6 ... Is adhered, the rust preventive material 2 is cooled and solidified by passing through the cooling device 28, and the winding device 30 is rotated. Take up on reel 31.

[0025]

As described above, the anticorrosion coated PC strand of the present invention is provided with a large number of continuous ridges on the outer peripheral surface of the anticorrosion material so that when it is used in a bond type prestressed concrete structure. By being mechanically meshed with the curable grout or concrete, the adhesion between the outer periphery of the covering material and the concrete is improved, and the concrete member can have a desired bending resistance.

Further, since the processing method only needs to add a coating step in which the inner surface shape of the molding die in the conventional anticorrosion coating processing line is deformed, the processing can be carried out without particularly increasing the cost.

[Brief description of drawings]

FIG. 1 is a cut end view of an embodiment of a high adhesion rust preventive PC strand according to the present invention.

FIG. 2 is a side view in which the lower half of the above is omitted.

FIG. 3 is a partially enlarged cut-away end view of the above.

FIG. 4 is a side view with the lower half of the other embodiment omitted.

FIG. 5 is a diagram schematically showing the steps of an example of the processing method according to the present invention.

FIG. 6 is a cross-sectional view showing a primary deposition process and a shaping process portion of the above.

FIG. 7 is a cut end view showing the shape of the molding die of the above.

FIG. 8 is a cut end view showing a state of PC strands after the shaping process of the above.

FIG. 9 is a cross-sectional view showing a secondary deposition step portion of the above.

FIG. 10 is a cut end view showing the shape of the forming die in the secondary deposition step of the above.

FIG. 11 is a partial cross-sectional view showing another example of the above secondary deposition step portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PC strand 2 Corrosion preventive material 3 Core wire 4 Side wire 5 Concave groove 6 Small convex line 22 Feeding device 23 Feeding device 24 Heating device 25 1st synthetic resin extrusion molding machine 26 Molding auxiliary die 27 2nd synthetic resin extrusion molding machine 28 Cooling Device 29 Take-up device 30 Rewinding device 31 Reel 32 Cross head 33 Auxiliary pressure head 34 Molding die 35 Recesses 36, 38 Heater 37 Holder 39 Recessed 40 Molding die 41 Cross head 42 Vacuum pump 43 Melt rust prevention cylinder 44 Motor

Front page continued (72) Inventor Kazuyoshi Chigiri 1-14 Nagatano-cho, Fukuchiyama-shi, Kyoto Hien Electric Works Fukuchiyama Plant (72) Inventor Yukihiro Higashi 1-14 Nagatano-cho, Fukuchiyama-shi, Kyoto Hien Electric Works Co., Ltd. Fukuchiyama Factory

Claims (2)

[Claims] 1. A spiral in which the inner voids and the outer periphery of a PC strand in which a plurality of single wires are twisted are covered with a rust preventive material made of a thermoplastic synthetic resin, and the outer peripheral surface corresponds to a spiral recess on the outer periphery of the PC strand. Has a groove and
A high-adhesion rust-proof coated PC strand integrally provided with a large number of small ridges continuous on the outer peripheral surface including the inside of the spiral groove. 2. A step of preheating the PC strands to a temperature suitable for deposition of a rust preventive material made of a molten synthetic resin material, and passing the preheated PC strands through a crosshead type synthetic resin extrusion molding machine. Corresponding to the primary deposition step of depositing the anticorrosive material including the internal voids of the PC strand by pressure, and passing the PC strand after the primary deposition through a molding die to the spiral recess on the outer periphery of the PC strand. The shaping step of shaping into a shape having the recessed groove formed, and the PC strand shaped by the shaping step are passed through a crosshead type synthetic resin extrusion molding machine using a molding die having a large number of recesses on the inner circumference to shape the strand. Secondary deposition step of depositing a molten rust preventive material cylinder having a large number of small ridges continuously on the outer periphery of the subsequent PC strand, and cooling the PC strand after the secondary adhesion to solidify the rust preventive material. Cooling A method of processing PC strands with high adhesion and anticorrosion, characterized by undergoing steps.