JPH11100945A - Film forming processing method for whole peripheral surface of prestressed tendon stranded core wire and side line, and film forming processing equipment for the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent pin hole, blister of film and peeling-off of paint film by fully removing before painting oxide scale, rusting occurred during the production of prestressed tendon stranded wire stuck to the core wire and side line and carbonized residue stuck due to blueing treatment of the residue of lubricant during wire drawing process of the core wire and side line before forming rustproof film on the respective outer peripheral surfaces of the core wire and side line of prestressed tendon stranded wire. SOLUTION: Stranded portion of the prestressed tendon stranded wire 1 is sequentially unstranded and turned into the state of element wires. Shot blasting is given to the element wires by giving impacts of steel balls or the like at a high speed from a plurality of directions; residue such as oxide scale, rusting, lubricant, etc., occurred on the surfaces of the core wire 1a and side line 1b are completely removed, and the skin of satin finish being optimum to painting is obtained. Also, as the shot blasting is performed while rotating the side line 1b, the surface treatment on the whole peripheral surface of element wires can be performed uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for prestressed concrete such as architectural structures, civil engineering structures, especially bridges, harbor structures, marine structures, etc., which are likely to be damaged by salt damage, and cables for cable-stayed bridges. The present invention relates to a processing method for forming a rust preventive coating on the entire outer peripheral surface of a core wire and a side wire of a PC steel stranded wire as a tendon and an apparatus for performing the method.

[0002]

2. Description of the Related Art The current state of rust-prevention treatment of PC steel strands as a tensioning material for a pretensioning system often uses bare PC strands that have not yet been subjected to any rust-prevention treatment. One of the reasons is due to the mechanism of introducing prestress into concrete in the case of the pretensioning method. In the pretensioning method, P
After tensioning the C steel strand to a predetermined tensile load, concrete is poured, and after solidification of the concrete, the tensile load of the PC strand that has been tensioned earlier is released to introduce prestress into the concrete. ing.

[0003] The mechanism of prestressing concrete is based on the adhesive force between the surface of the tendon material and the concrete. In the case of a PC steel stranded wire, the spiral groove formed by the twisting between the side wires forms a gap with the concrete. This is the main part for obtaining adhesion. Therefore, forming a rust-preventive film on the surface of the PC steel strand is accomplished by filling the spiral groove portion with the film, reducing the depth and narrowing the width, resulting in a large adhesive force with concrete. This will lead to a decrease. In addition, when the surface of the PC strand is subjected to the formation of a rust-preventive film, the rust-preventive film is not formed on the inner side of the core wire or the side wire, and the problem of internal corrosion cannot be solved.

In the process of forming a rust-preventive coating only on the surface of a PC steel stranded wire, in order to improve the adhesion to concrete,
Sand-like particles are sprayed on the surface of the rust preventive coating as disclosed in "JP-A-59-130960". Further, as a method of solving the problems of the decrease in adhesion to concrete and the problem of internal corrosion, it is known to form a coating on the entire outer peripheral surface of each of the core wire and side wire of the PC steel stranded wire.
6, JP-B-3-1438, JP-B-7-103643, and JP-A-5-329441.
And JP-A-6-142595.

[0005]

In the conventional method of forming a film, the base wire and the side line are adjusted without returning the side line of the PC steel stranded wire to the rust,
Oil film, dirt, etc. are removed with a steel brush.
Also, no adjustment of the inner side of the twisted side lines is performed.

[0006] The final step of the manufacturing process of the PC steel strand is a bluing process, and the residue of the lubricant in the wire drawing process of the oxide scale, rust, the core wire, and the side wire is carbonized by the bluing process and adhered residue. If these are not completely removed, they cause swelling of the coating film and pinholes. Further, since water is used for cooling after the bluing treatment, water remains in the inside of the PC stranded wire, which often causes rust inside. Therefore, if the surface base adjustment is performed in the state of the strand of PC steel as in the prior art, the outer peripheral surfaces of the core wire and the side wires are not completely adjusted.

[0007]

Means for Solving the Problems To solve the above-mentioned problems, return the strands of PC steel to loosen the side lines, separate the side lines from the core wires, maintain the widening at predetermined intervals, and shot blast the core wires and the side lines. Then, the core wire and the side wire were painted, and then returned, so that the base material of the outer peripheral surface of the PC core wire and the side wire could be completely adjusted. Also, as an apparatus for realizing the method,
A loosening device that temporarily returns the side line of the PC steel strand from the periphery of the core wire and a loosening device that brings the returned side line closer to the periphery of the core wire, between these loosening devices and the loosening device. The expansion and maintenance device, core adjustment device, shot blasting device, pre-heating device, coating device, post-heating device, and cooling device for expanding the returned side line to a predetermined size are provided. The surface base adjustment of has been completed.

In the state where the side wire of the PC stranded wire is returned from the periphery of the core wire and is expanded at a constant interval, the entire outer peripheral surfaces of the core wire and the side wire are completely adjusted by shot blasting. Even if the core wire or the inside of the side wire is rusted,
The rust is completely removed by shot blasting and sufficient base adjustment is performed. Further, the core wire becomes excessive due to the substrate adjustment and the coating forming process, but the excess core wire is absorbed by the automatic core wire adjusting device, and the coating can be formed smoothly.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on an example of a synthetic resin coating in the illustrated embodiment.

Core wire adjusting device When the twist of the PC steel strand is returned, the shot blasting process and the coating are performed on the core wire and side wire, the diameter of the core wire changes, and when the wire is twisted again, the core wire is twisted. Side line that is more closely aligned with the surrounding area becomes insufficient, and the core line becomes excessive.

An example will be specifically described with respect to the influence of the film forming process. Calculation Example Table 1 shows the diameter and pitch of the core wire and the side wire before and after the coating film formation in the case of the steel stranded wire size of 12.7 mm.

[Table 1] Since the pitch of the PC steel strand is the same before and after the film is formed, the side line where the diameter of the core wire has increased due to the film is insufficient, and the core wire becomes extra for the length shown below per pitch. Come.

Circumference before core wire coating formation 4.39 × π = 13.785 mm Circumference after core wire coating formation 4.67 × π = 14.664 mm Difference per pitch 14.664 mm−13.785 mm = 0. 88mm As shown by calculation, 0.88m difference per pitch
m is accumulated, and the side line becomes insufficient. That is, the core wire becomes excessive, and the core wire droops excessively during the re-laying operation of the returned side line, so that the smooth re-laying operation cannot be performed.

This point will be further described with reference to FIGS. As shown in FIG.
77.8 mm. Therefore, the length of the surplus core wire per meter of the core wire is (1000 / 177.8) × 0.88 =
4.95 mm. By the way, since the length per ton is about 1290m, 1290m x 4.95mm = 6.
The 4 m core wire becomes surplus. Therefore, it is assumed that the distance from the release device to the release / closing device is 14 m, and that the side wire is expanded to 150 mm by the expansion maintaining device. )
As shown in FIG. 8, assuming that the widening section distance is (W) and the amount of deflection (H) at the center is as follows.

Embedded image

As described above, assuming that the side wire is expanded over a distance of 14 m, if the core wire becomes approximately 1.1 mm excessive, even if the side line expansion maintenance diameter is expanded to 150 mm, the core wire is expanded. Therefore, a core adjusting device that accumulates and absorbs the excess core is required.

Embodiment FIG. 1 is a schematic view of a processing line for implementing a method for forming a coating film of a synthetic resin powder coating of a PC steel strand. PC steel strand 1
As shown in FIG. 2, there is a core wire 1a at the center, and a plurality of side wires 1b are spirally formed on the outer periphery of the core wire.

The thus formed PC steel strand 1 is as follows.
One having a predetermined length is wound in a coil shape. The PC steel strand 1 is sequentially rewound from one end and supplied to a processing line, and is wound from the other end through a film forming step, and the film is formed continuously.

The processing line shown in FIG.
An uncoiler device 2 on which a C steel strand 1 is set is provided, and is sequentially pulled out from a wound state for the next process. Next, a loosening device 3 for returning the side wire 1b from the periphery of the core wire 1a, an expansion maintaining device 4a for expanding the side wire 1b and maintaining a predetermined interval, a core wire adjusting device 5 for accumulating and absorbing the excess of the core wire, Open maintenance device 4b follows.

Further, a shot blasting device 6, a spread maintaining device 4c, a preheating device 7, an electrostatic powder coating device 8, a post-heating device 9, a cooling device 10, a spreading device for performing surface treatment of the core wire 1a and the side wire 1b. Following the maintenance device 4d, the loose closing device 11, PC, which returns the expanded PC stranded wire to the original twisted state.
A coating thickness measuring device 13 for measuring the coating pressure of the steel strand 1 and an inspection device for the coating pinhole detecting device 14 are provided, and a take-up device 15 and a winding device 16 are provided.

As described above, the coiled PC stranded wire 1 set on the uncoiler 2 has the side wire 1b, which is joined to the periphery of the core wire 1a in the refining device 3, successively and continuously returned, and then returned. During the film forming process of the side line 1b, the expanded state is maintained at a predetermined interval by the expansion maintaining devices 4a, 4b, 4c, and 4d. The spacing (D1) between the side line passage holes 20 of the rotating ring 21 of the release device 3 and the release / closing device 11 shown in FIG. 4 is preferably 20 mm or more, and the expansion maintaining devices 4a, 4b, 4c shown in FIG.
Interval of side line passage hole 24 of 4d rotary ring 25 (D2)
Is preferably 30 mm or more.

The side wire 1b is further returned from the periphery of the core wire 1a by the loosening device 3, and is expanded to a required interval by the expansion maintaining device 4a. The surplus portion of the core wire 1a generated by the film formation and the surface base adjustment by the core wire adjusting device 5 is accumulated and absorbed, and is sent to the next shot blast device 6. In the core adjusting device 5, the core 1a passes through the core passing hole 23 at the center of the rotating ring 25 of the expansion maintaining device 4a, is U-turned at the fixed pulley 30, and again at the movable pulley 29, as shown in FIG. It is U-turned and sent to the next process via the fixed pulley 29. Movable pulley 2
The movable distance 9 is determined according to the length of the surplus core wire 1a to be accumulated and absorbed. Since the movable pulley 29 is always pulled by the tension adjusting coil spring 27 toward the release device 3 with a constant tension, an excess amount of the core wire 1a generated while the side line is returned to the original state by the release / closing device 11 is removed. Collected and absorbed.

The fixed pulley 30 and the movable pulley 29 are provided with a shaft 28 so that they can rotate freely without applying a rotational driving force.
1 and is fixed to the pulley arm 28. On the other hand, the loosened side line 1b passes through the side line passage hole 24 on the outer peripheral side of the rotating ring 25 and is sent to the next step. The rotating ring 21 of the gradual closing device 11 and the rotating ring 25 of the expansion maintaining devices 4a to 4d are rotatably supported on the base by bearings 18 and 22, respectively.

The core wire 1a and the side wire 1b that have passed through the core wire adjusting device 5 are guided to the shot blast device 6 while being expanded by the expansion maintaining devices 4b and 4c. In the shot blasting device 6, the abrasive (steel ball of about 0.3 mm) is uniformly projected in all directions by a blade (blade) rotating at high speed, and the entire outer peripheral surface of each of the core wire 1a and the side wire 1b is uniformly formed. The base is adjusted.

Core wire 1a, side wire 1b after base adjustment
Is sent to the next step in a state where it is expanded by the expansion maintaining devices 4c and 4d. Then, the preheating device 7 heats the synthetic resin powder coating material to a predetermined temperature at which the coating material melts. The pre-heating device 7 can be omitted, and only the post-heating device 9 may be used. The heating means is desirably high-frequency induction heating that can easily perform temperature adjustment.

The powder coating adhesion layer is formed on the entire outer peripheral surface of each of the core wire 1a and the side wire 1b heated to a predetermined temperature by the pre-heating device 7 by the electrostatic powder coating device 8,
b formed on the surface, which melts to form a film.

The surface on which the coating is formed on the entire outer peripheral surface of each of the core wire 1a and the side wire 1b is heated by the post-heating device 9 to be completely melted, and the coating of the coating is completely performed.

After the coating formed on the entire outer peripheral surface of each of the core wire 1a and the side wire 1b is completely cured, the cooling device 10 cools the film to room temperature.

After the cooled core wire 1a and side wire 1b pass through the expansion maintaining device 4d, the side wire 1
b is joined to the periphery of the core wire 1a and is restored to the original state of the PC stranded wire.

FIG. 3 shows the coated PC steel strand 12 restored as described above. Core wire 1 as shown
a and a cross-sectional structure in which a coating is formed on the entire outer peripheral surface of the side line 1b. The film thickness is measured by a film thickness measuring device 13 as an inspection device, and an alarm and a signal are issued when the film thickness exceeds an allowable value. The line may be stopped by this signal.

Further, in the next step, the pinhole detecting device 1
4 to inspect the condition of the coating 17. When a pinhole is detected by using a non-contact type, for example, an optical detection means so as not to damage the coating 17, a mark is applied to the detection position and an alarm signal is issued.

The PC stranded wire having the coating formed thereon, which has been inspected as described above, is sent out by a take-off device 15 provided with an endless belt on the upper and lower sides while taking care not to damage the coating 17.
The winding device 16 sequentially winds the coil.

[0031]

As described above, according to the present invention, P
The method and apparatus for forming a film of a C steel stranded wire are such that the side wire of the PC steel stranded wire is returned from the periphery of the core wire by a loosening device,
Further, the side line that has been returned is expanded at a predetermined interval by the expansion maintaining device, and during this time, the core wire and the entire outer peripheral surface of each side line are completely adjusted by the shot blasting device, and the core wire or the inside of the side line is adjusted. The generated rust was completely removed to solve the problem of internal corrosion, which had been a problem in the past. In addition, the core wire adjusting device is arranged next to the uncoiler device, and a constant tension is always applied to the core wire by integrating and absorbing the excess core wire by shot blasting and forming the synthetic coating, so that the coating can be formed smoothly. I did it.

[Brief description of the drawings]

FIG. 1 is a schematic view of a film formation processing line according to the present invention.

FIG. 2 is a sectional view of a PC steel strand to be processed.

FIG. 3 is a cross-sectional view of a coated PC steel strand.

FIG. 4 is a front view of a release device and a release device.

FIG. 5 is a front view of the spread maintaining device.

FIG. 6 is an enlarged view of a main part of the core wire adjusting device.

FIG. 7 is an explanatory view of a winding state of a side line before and after a film is formed.

FIG. 8 is an explanatory view of a bent state of a core wire.

[Explanation of symbols]

 1: PC steel stranded wire 1a: core wire 1b: side wire 2: uncoiler device 3: loosening device 4a, 4b, 4c, 4d: expansion maintaining device 5: core wire adjusting device 6: shot blast device 7: pre-heating device 8: static Electro-powder coating device 9: Post-heating device 10: Cooling device 11: Loose closing device 12: PC steel stranded wire with film formed 13: Film thickness measuring device 14: Pinhole detecting device 15: Pulling device 16: Winding device 17 : Coating 18: Bearing 19: Core wire passing hole 20: Side wire passing hole 21: Rotating ring 22: Bearing 23: Core wire passing hole 24: Side wire passing hole 25: Rotating ring 26: Core wire adjusting device outer ring 27: Tension adjusting spring 28: Pulley Arm 29: Movable pulley 30: Fixed pulley

Claims (10)

[Claims] 1. A method of forming a coating on the entire outer peripheral surface of each of a core wire and a side wire of a PC steel stranded wire, wherein the PC steel stranded wire is returned to loosen the side wire, and the side wire and the core wire are separated from each other at a predetermined interval. Maintain the spread, apply shot blasting to the surface of the core wire and the side line, paint and twist the side line again.
A method for forming a coating film on the entire outer peripheral surface of a C steel stranded wire and side wire. 2. The method according to claim 1, wherein the coating of the core wire and the side wire is a resin-coated PC steel wire core wire and a side wire. 3. The method according to claim 1, wherein
A method for forming a coating film of the entire outer peripheral surface of a PC core wire and a side wire in which a core wire and a side wire are heated at least after coating. 4. The method according to claim 1, wherein
PC stranded wire core wire that heats core wire and side wire before and after painting,
A method for forming the entire outer peripheral surface of the side wire. 5. The method for forming a coating film on a whole outer peripheral surface of a PC core wire and a side wire according to claim 1, wherein shot blasting is performed while rotating the side wire. 6. A loosening device for returning the side line of the PC steel stranded wire from around the core wire, a loosening device for adjusting the returned side line to the periphery of the core wire again, and a core wire between the loosening device and the loosening device. P is characterized by including a required number of expansion maintaining devices for maintaining side lines at a predetermined interval, a core wire adjusting device for absorbing excess core wire, a shot blast device, and a coating device.
Film forming and processing equipment for core wire and side wire of C steel strand. 7. A coating apparatus for forming a core wire and side wires of a PC steel wire, wherein the coating apparatus is an electrostatic powder resin coating apparatus, and a heating apparatus is provided at least after the coating apparatus. 8. The apparatus according to claim 6, wherein the coating device is an electrostatic powder resin coating device, and a PC steel stranded core wire and a side wire coating forming device are provided with heating devices before and after the coating device. 9. The rotating device according to claim 6, wherein the loosening device, the slowly closing device, and the expansion maintaining device have a rotary ring shape, a core wire passing hole is provided at the center of the rotary ring, and the outer periphery of the rotary ring. PC with side line passage holes at equal intervals
Film forming and processing equipment for steel stranded wires and side wires. 10. The PC steel according to claim 9, wherein the interval between the side line passage holes of the rotating ring of the release device and the slowly closing device is 20 mm higher, and the interval of the side line passage hole of the rotating ring of the expansion maintaining device is 30 mm or more. Wire core and side wire coating forming equipment.