JP2004263320A - Method for forming rust-preventing coating film on pc steel twisted cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming rust-preventing coating films on a PC (prestressed concrete) steel twisted cable by which resin coating films are well adhered to an untwisted core wire and untwisted side wires to form double rust-preventing layers on the wires. <P>SOLUTION: This method for forming the rust-preventing coating films on the PC steel twisted cable is characterized by forming a plating coating film 12 on the outer side of an element wire 11, drawing the plating coating film-formed element wire 11 to form the element wire 14 for the twisted cable, twisting a plurality of the element wires 14 for the twisted cable to form the PC steel twisted cable 19 comprising a core wire 17 and side wires 18, temporarily untwisting the PC steel twisted cable 19, blasting the core wire 17 and the side wires 18, forming resin coating films 20 on the outside of the blasted core wire 17 and the blasted side wires 18, cooling the resin coating films 20, and then again twisting the coated wires. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for forming a rust-preventive coating on a stranded PC steel wire used as a tension member in a prestressed concrete method for building structures and civil engineering structures.
[0002]
[Prior art]
As a method of forming a double rust preventive layer for preventing corrosion of a steel wire on a core wire and a side wire of a steel stranded wire, for example, there is an invention disclosed in Japanese Patent Application Laid-Open No. H11-120826. In this method, an aluminum zinc coating layer is formed on the outer peripheral surface of the core wire and the side wire, and a resin coating is formed on the coating layer.
[0003]
[Patent Document 1]
JP-A-11-120826 (FIG. 1)
[0004]
[Problems to be solved by the invention]
However, in the method for forming a double rust preventive layer as described above, the steel stranded wire on which the aluminum zinc coating layer is formed is temporarily returned to form an epoxy resin coating. There was a problem that it was bad due to the oil and fat content of the zinc coating layer.
[0005]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for forming a double rust preventive layer, in which a PC steel stranded wire having good adhesion of a resin coating to a returned core wire and a side wire is provided. To provide a method for forming a rust-preventive film.
[0006]
[Means for Solving the Problems]
The method for forming a rust-preventive coating on a stranded PC steel according to the present invention for solving the above-mentioned problems comprises forming a plating coating on the outer peripheral surface of the strand, and drawing the strand on which the plating coating is formed. Form a strand for stranded wire, combine the strands for stranded wire from a plurality of strands to form a PC steel stranded wire consisting of a core wire and a side wire, and temporarily return the PC steel stranded wire to blast the core wire and the side wire. A resin film is formed on the outer peripheral surface of the blasted core wire and side wire, and the resin film is cooled and then joined again. In addition, the emission amount of the blast processing includes 100 to 250 kg / hr. Further, the blasting treatment uses a mixed iron powder of shot and grit, and includes that the shot is spherical iron powder having a diameter of 0.2 to 0.4 mm and the grit is cubic iron powder having a square of 0.3 to 0.8 mm. It is a thing.
[0007]
By temporarily returning the side wire of the PC steel stranded wire from the core wire and performing the blast treatment, the plating coating surface becomes clean and has a moderately rough surface, so that the adhesion of the resin coating to the core wire and the side wire is enhanced.
[0008]
The optimal amount of the blast treatment is 180 kg / hr. If it is less than 100, there is a problem that the surface oils cannot be completely removed. If it exceeds 250 kg / hr, the plating film disappears and the blast iron powder is broken. And the efficiency becomes poor.
[0009]
Further, by using a mixed iron powder of shot and grit for the blasting treatment, the zinc-coated surface can be made clean and moderately rough.
Further, when the shot has a diameter of less than 0.2 mm, there is a problem that the flat surface cannot be cleaned and the oil and fat on the surface cannot be removed. Further, when the grit is less than 0.3 mm square, there is a problem in the surface roughness, and when it exceeds 0.8 mm square, the surface roughness becomes excessive, the smoothness of the coating resin is deteriorated, and the iron powder is easily broken.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a method for forming a rust-preventive film on a stranded PC steel (hereinafter, referred to as a film forming method) of the present invention will be described with reference to the drawings. The method for forming a film according to the present invention comprises a first step and a second step. FIGS. 1 to 3 show the first step, and FIGS. 4 and 5 show the second step. In each step, the same configuration is denoted by the same reference numeral, and only the different configuration is denoted by the different reference numeral.
[0011]
FIG. 1A is a conceptual diagram of a processing line 1 for forming a plating film in a primary process. (2) in the same figure is a bus bar 2 having a diameter of 10 to 14 mm to be processed. The bus bar 2 is wound around a roller 3 of a predetermined length, and the roller 3 is set on an uncoiler device 4 at one end of the processing line 1.
[0012]
Then, the busbar 2 drawn out from the uncoiler device 4 by the drawing roll 5 passes through a primary cleaning process 6, a wire drawing process 7, a secondary cleaning process 8 and a plating process 9, and is wound around a winding device 10 at the other end. Taken.
[0013]
The primary cleaning process 6 includes acid cleaning and water cleaning. First, the outer peripheral surface of the bus 2 is washed with a hydrochloric acid solution, and then the hydrochloric acid solution remaining on the outer peripheral surface of the bus 2 is washed with water. In the wire drawing process 7, the bus bar 2 having a diameter of 10 to 14 mm, which has been subjected to the cleaning process, is cold-drawn to form a wire 11 having a diameter of 5 to 9 mm. Next, the wire 11 having a diameter of 5 to 9 mm formed by the wire drawing process 7 is subjected to a secondary cleaning process 8. The secondary cleaning process 8 is performed by immersing the wire 11 in a flux solution tank. The flux solution tank contains a saturated solution of ammonium chloride or a double salt solution of ammonium chloride and zinc chloride. Next, the wire 11 on which the secondary cleaning process 8 has been performed is subjected to a drying process, which is immersed in a molten zinc bath filled with molten zinc to form a plating film 12 of zinc. Then, the element wire 11 on which the plating film 12 is formed is taken up by the take-up device 10.
[0014]
The plating film 12 includes, in addition to zinc, a zinc alloy, an aluminum alloy, copper, and chromium.
[0015]
FIG. 2A is a conceptual diagram of a processing line 13 showing a wire drawing process 7 in the first step. Similarly to the above, the roller 3 around which the wire 11 has been wound is set on the uncoiler device 4 at one end of the processing line 13, and the wire 11 drawn by the drawing roll 5 from here is subjected to cold drawing. The wire drawing process 7 is performed, and the wire is wound around the winding device 10 at the other end. By the wire drawing process 7, as shown in (2) of the figure, a strand 14 for a stranded wire having a diameter of about 4 to 5 mm with a plated coating 12 is completed.
[0016]
FIG. 3A is a conceptual diagram of a processing line 16 showing a twisting process 15 in the first step. In the same manner as described above, the roller 3 around which the strand for stranding wire 14 has been wound is set on the uncoiler device 4 at one end of the processing line 16, and the seven strands for stranding drawn out by the draw-out roll 5 from here. The wire 14 is twisted and wound around the winding device 10 at the other end.
[0017]
In this stranded wire processing 15, six side wires 18 made of the stranded wire 14 are spirally fitted to one core wire 17 made of the stranded wire 14, as shown in (2) of FIG. The stranded PC steel wire 19 is formed. Then, in the secondary process, a resin film 20 is applied to the core wire 17 and the side wires 18 of the PC steel stranded wire 19 formed in the primary process.
[0018]
FIG. 4 shows a conceptual diagram of the processing line 21 in the secondary process. An uncoiler device 4 is provided at one end where the roller 3 around which the PC steel stranded wire 19 is wound is set. Toward the other end side, the drawing roll 5, the loosening device 22, the front side expansion maintaining device 23, the core wire adjusting device 24, the primary heating device 25, the powder coating device 26, the secondary heating device 27, the cooling device 28, and the rear The side expansion maintaining device 29, the gradual closing device 30, the film thickness measuring device 31, the pinhole detecting device 32, the pulling device 33, and the winding device 10 are sequentially provided adjacently, and the core wire adjusting device 24 and the primary heating device 25 are provided. The blast device 34 is installed between the blast device and the blast device.
[0019]
The blasting device 34 sprays a mixed iron powder of shot and grit at a rate of 100 to 250 kg / hr onto the plating film 12 of the core wire 17 and the side wire 18 to clean and roughen the coating. Spherical iron powder having a diameter of about 0.4 mm and cubic iron powder having a grit of 0.3 to 0.8 mm square.
[0020]
As described above, the coiled PC steel stranded wire 19 set in the uncoiler device 4 is sequentially pulled out from here by the pull-out roll 5, and the side wire 18 spirally fitted to the core wire 17 is returned by the loosening device 22. This is spread at predetermined intervals by the front and rear expansion maintaining devices 23 and 29, and this state is maintained.
[0021]
The core wire adjusting device 24 installed on the rear side of the front-side expansion maintaining device 23 winds up the surplus core wire 17 generated by forming the resin film 20 on the core wire 17 and the side wire 18. This is because the PC steel stranded wire 19 is loosened, the plated film 12 is formed on the core wire 17 and the side wire 18, and then loosely closed again, the diameter of the core wire 17 and the side wire 18 increases, and the winding of the side wire 18 around the core wire 17 is performed. Is detoured by the film thickness, the length of the side line 18 with respect to the core wire 17 is shorter than before the loosening, and the core wire 17 becomes excessive. The core adjusting device 24 includes a fixed pulley 36 supported by a support arm 35 and a movable pulley 37. The movable pulley 37 is constantly urged by a coil spring or the like in a direction in which the movable pulley 37 is separated from the fixed pulley 36. .
[0022]
Also, as shown in FIG. 5A, the returned twisted PC steel wire 19 passes from the blast device 34 to the primary heating device 25, the powder coating device 26, the secondary heating device 27, and the cooling device 28 to the core wire. When the plating film 12 is applied to the wire 17 and the side line 18, and then re-twisted by the gradual closing device 30 shown in (2) of FIG. Then, the stranded PC steel wire 19 having the plating film 12 is completed.
[0023]
In the powder coating apparatus 26, an electrostatic fluid immersion powder coating technique is adopted as a resin coating means, and the returned core wire 17 and side wire 18 are coated with epoxy resin, polyester resin, fluororesin, polyethylene resin, heat An electrostatic coating such as a curable resin or a thermoplastic resin is performed. In order to enhance the adhesion of the resin film 20 to the core wire 17 and the side wire 18 by the electrostatic coating, the blasting process 38 is performed on the plating film 12 by the blasting device 34 before the powder coating.
[0024]
In this blasting process 38, a mixed iron powder of shot and grit is sprayed onto the plating film 12 of the core wire 17 and the side wire 18 at an emission rate of 100 to 250 kg / hr, and the coating film is cleaned and roughened to improve the adhesion of the resin film. Spherical iron powder is used as the shot, and cubic iron powder is used as the grit. The spherical iron powder has a diameter of 0.2 to 0.4 mm, and the grit of 0.3 to 0.8 mm square is optimal. The blasting process is applied in the range of the emission amount of 100 to 250 kg / hr, and 180 kg / hr is optimal. Also, if the amount of blast treatment is less than 100, there is a problem that the surface oil and fat cannot be completely removed. is there.
[0025]
【The invention's effect】
According to the method for forming a rust-preventive coating of a stranded PC steel wire of the present invention, the adhesion of the resin coating to the plating coating of the core wire and the side wire is improved. Further, the rust prevention performance of the resin film is improved.
[0026]
By using a blasting treatment with an emission rate of 100 to 250 kg / hr and using a mixed iron powder of shot and grit, the plating film on the core wire and the side wire can be cleaned and appropriately roughened.
[Brief description of the drawings]
FIG. 1 shows a plating process in a first step, wherein (1) is a conceptual diagram of a processing line, and (2) is a cross-sectional view of a bus bar and an element wire to be processed.
FIG. 2 shows a drawing process in a first step, in which (1) is a conceptual diagram of a processing line, and (2) is a cross-sectional view of a twisted strand to be processed.
FIGS. 3A and 3B show a stranded wire treatment in a first step, wherein FIG. 3A is a conceptual diagram of a processing line, and FIG. 3B is a cross-sectional view of a stranded PC steel wire to be processed.
FIG. 4 is a conceptual diagram of a processing line of a resin film processing in a secondary process.
FIG. 5 shows a stretched PC steel stranded wire obtained by applying a resin coating to a drawn wire and a side wire of the returned stranded wire, and (1) shows a cross section of the returned stranded wire. Drawing, (2) is a sectional view of a loose closing device, and (3) is a sectional view of a PC steel stranded wire.
[Explanation of symbols]
1, 13, 16, 21 Processing line 2 Busbar 3 Roller 4 Uncoiler device 5 Extraction roll 6 Primary cleaning process 7 Wire drawing process 8 Secondary cleaning process 9 Plating process 10 Winding device 11 Element wire 12 Plating film 14 For stranded wire Wire 15 Twisting treatment 17 Core wire 18 Side wire 19 PC steel stranded wire 20 Resin coating 22 Relief device 23 Front side expansion maintaining device 24 Core wire adjusting device 25 Primary heating device 26 Powder coating device 27 Secondary heating device 28 Cooling device 29 Rear-side expansion maintaining device 30 Loose closing device 31 Film thickness measuring device 32 Pinhole detecting device 33 Pick-up device 34 Blast device 35 Support arm 36 Fixed pulley 37 Movable pulley 38 Blast processing

Claims (3)

A plating film is formed on the outer peripheral surface of the wire, and the wire on which the plating film is formed is drawn to form a wire for a stranded wire. Forming a stranded PC steel wire comprising side wires, temporarily returning the stranded PC steel wire, blasting the core wire and the side wire, forming a resin coating on the outer peripheral surface of the blasted core wire and the side wire, A method for forming a rust-preventive coating on a stranded PC steel, the method comprising the steps of: The method for forming a rust-preventive coating on a stranded PC steel according to claim 1, wherein the discharge amount of the blasting treatment is 100 to 250 kg / hr. The blasting process uses a mixed iron powder of shot and grit, the shot is a spherical iron powder having a diameter of 0.2 to 0.4 mm, and the grit is a cubic iron powder of 0.3 to 0.8 mm square. The method for forming a rust-proof coating on a stranded PC steel wire according to claim 1 or 2.

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