JP2735520B2 - Method and apparatus for forming rust-proof coating on PC steel strand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PC steel stranded wire used as a pretensioning type tension member in a prestressed concrete construction method for a building structure and a civil engineering structure. The present invention relates to a method of forming and processing a synthetic resin powder coating film, that is, a rust-preventive film on a wire constituting each layer of a PC steel stranded wire, and an apparatus for performing the method.

[0002]

2. Description of the Related Art As a means for forming a rust-preventive film on a PC steel strand of this type, there is a prior application of the same applicant, which was disclosed in Japanese Patent Application Laid-Open No. Hei 6-142595 on May 24, 1994.
Issued as issue. The disclosed invention is directed to forming a rust-proof coating on a so-called two-layer PC steel stranded wire in which a side wire is wound around the outer peripheral surface of a core wire.

In the above disclosed invention, in a two-layer PC steel stranded wire, the winding of the side wire around the core wire is temporarily returned, and a rust-preventing film is formed on the surface of the core wire and the side wire in the returned state. Later, the side line is slowly closed to return to the original stranded state.

[0004]

In the method for forming a rust-preventive film according to the disclosed invention, since the outer diameters of the core wire and the side wire are increased by the amount of the formed film, when the side line is slowly closed. Since the winding diameter with respect to the core wire becomes large, the length of the side wire gradually becomes short as the sequential winding process proceeds, and conversely, since the core wire becomes excessive, a core wire adjusting device is provided before the film forming process. The surplus core wire is processed by the core wire adjusting device, whereby a smooth rust-preventive film forming process is performed.

[0005] However, in the case of three or more layers of PC steel stranded wire, the outer diameter of the middle wire wound around the core wire is also increased by the rust-preventive coating. It is not a countermeasure against the shortage of the outer wire wound around the outside. That is, it is difficult to apply the disclosed invention as it is to the formation of a rust-preventive film on a PC steel strand having a multilayer structure of three or more layers.

[0006] Therefore, in the case of a PC steel stranded wire having a multi-layer structure of three or more layers, there is a problem to be solved in that the rust-preventing film forming process of each layer wire is properly performed.

[0007]

SUMMARY OF THE INVENTION As a specific means for solving the above-mentioned problems of the prior art, the present invention provides a method of temporarily twisting a stranded portion of a PC steel stranded wire formed by winding a plurality of layers of wire around a core wire. Forming a rust-preventive coating of a solvent-type paint or a powder-type paint on the outer peripheral surface of each wire including the returned core wire. Is performed all at once in the same area, the length adjustment of the core wire is performed before the formation of the rust preventive coating, and the length adjustment of the wire after the next stage is performed immediately before the wire of each layer is loosely closed. The present invention provides a method for forming a rust-preventive coating on a PC steel stranded wire, wherein the wire material of each layer returned from the above is maintained over a predetermined length by a plurality of expansion maintaining means,
In the meantime, formation of a rust-preventive film by adhesion of paint and heat welding is performed, and the action of the return is utilized for the action of twisting the layers through the expansion maintaining means.

In addition, a loosening device for temporarily loosening the wires of each layer with respect to the core wire of the PC steel stranded wire and a loosening device for twisting the wires of each layer again with respect to the loosened core wire are provided. A coating device, a heating device and a cooling device are provided between the release device and the release device. This includes providing a core wire adjusting device between the coating device and a wire rod adjusting device for forming a layer immediately before a loosely closing device for forming a next layer.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 schematically shows a processing line or a processing apparatus for performing a method for forming a rust-proof coating on a PC steel strand. As shown, 1 is an uncoiler device, which is located at one end of a processing line or a processing device and rotates a drum on which 19 PC steel stranded wires 2 are wound. The wire can be set freely and the strand 2 of PC steel can be sequentially fed out.

As shown in FIG. 2, the nineteen strands of the PC steel stranded wire are made of nine central wires 2b having a diameter smaller than that of the core wire 2a. In addition, nine outer wires 2c having substantially the same diameter as the core wire 2a are spirally wound therearound.

The stranded PC steel wire 2 drawn from the uncoiler device 1 is supplied from one end to a processing line or a processing device in succession, and after a predetermined processing step, the finished product is wound at the other end. It is taken and processed continuously. The processing line or the processing apparatus is arranged such that the surface pretreatment device 3, the loosening device 4, the first expansion maintaining device 5, the core wire adjusting device 6, the second expansion maintaining device 7, Heating device 8, coating device 9, post-heating device 10, primary cooling device 11, third expansion maintaining device 12, middle side line gradual closing device 13, middle side line adjusting device 14, fourth expansion maintaining device 1.
5. Outer wire gently closing device 16, secondary cooling device 17, coating outer diameter measuring device 18, coating pinhole detecting device 19, take-up device 20, and take-up device (wooden drum take-up) 21 are formed and installed in series. ing.

The surface pretreatment device 3 treats the outer peripheral surface of the PC steel strand 2 drawn from the uncoiler device 1 by mechanical or scientific means. In this case, dust, grease, or rust attached to the surface of the PC steel strand 2 is removed. For example, grease or grease is removed with a chemical or detergent, rust is removed with a wire brush, and washing is performed with washing water. In other words, it is only necessary to be able to clean the surface of the PC stranded wire 2 cleanly.

[0013] The PC steel strand 2 thus treated is
It is supplied to the next stage of the relaxation device 4,
The C steel strand 2 is continuously returned. That is,
The inner wire 2b and the outer wire 2c wound around the core wire 2a are:
It is temporarily returned in a continuous state, and as shown in FIG. 3, the returned state is changed to the first expansion maintaining device 5 and the second expansion maintaining device 5.
Is maintained in the expanded state by the expansion maintaining device 7.

As shown in FIGS. 4 and 5, the loosening device 4 is provided on a predetermined stand 30 with a ring-shaped radial ball bearing 3.
1, a loosening machine 32 is rotatably mounted, a core wire guide hole 33 is provided at a substantially central portion of the loosening machine 32, and a plurality of middle line guide holes 34 and outer line guide holes 35 are formed in a radial direction. Each is provided. Each of the guide holes has a bush 33a, 34 made of a hard material such as an alumina bush for preventing abrasion due to wear.
a, 35a, etc. are respectively attached by adhesive means or the like.

[0015] PC with respect to the relaxation device 4 having such a configuration
The ends of the steel stranded wire 2 are separated and the core wire 2a is inserted into the corresponding guide holes so that the middle wire 2b and the outside wire 2c are passed therethrough, thereby returning the twist of the middle wire 2b and the outside wire 2c to the core wire 2a. The pieces are separated and the separated states are guided and transported while being maintained at a constant spread by the first and second expansion maintaining devices 5 and 7. The first and second expansion maintaining devices 5 and 7 are arranged at a predetermined interval before the preheating device 8.

The first to fourth expansion maintaining devices 5, 7, 1
Reference numerals 2 and 15 have substantially the same configuration as that of the above-described releasing device 4, except that the outer diameter is increased as a whole and the distance between the middle line guide hole and the outer line guide hole with respect to the core line guide hole is increased. Therefore, a detailed description of this expansion maintaining device will be omitted.

A core adjustment device 6 is provided between the first expansion maintaining device 5 and the second expansion maintaining device 7. As shown in FIG. 6, the core wire adjusting device 6 includes a fixed pulley 36.
The movable pulley 37 is constantly urged in a direction to be separated from the fixed pulley 36 by, for example, a coil spring 38 or the like. The pulleys are rotatably supported by appropriate support members 39.

As shown in FIGS. 1 and 6, the stranded PC steel strand 2 which has been returned to its original position is coated with the pre-heating device 8 from the first and second expansion maintaining devices 5 and 7, and then coated. Device 9
And is subjected to a coating process in an expanded state by a post-heating device 10 and a primary cooling device 11, passes through a third expansion maintaining device 12, and a middle side wire 2 b with respect to a core wire 2 a by a middle side line loosely closing device 13.
Only will be twisted again.

The coating apparatus 9 employs, for example, an electrostatic fluidized immersion powder coating technique as a coating means, and the PC steel which is separated and maintained in an expanded state while passing through the coating apparatus 9 is used. All the wires constituting the stranded wire 2, that is, the wires forming the respective layers of the core wire 2a, the middle wire 2b, and the outer wire 2c are subjected to electrostatic coating at once.

An outline of the electrostatic fluidized immersion powder coating technique in the coating apparatus 9 will be described.
Is equipped with a plurality of powder feeders 9a for coating, and in the internal electrostatic coater portion, a negatively charged powder coating material is suspended in an airflow, and a preheated and grounded PC steel is placed therein. By returning the wire 2 in a state where the wire 2 is expanded and maintained, an adhesion film of the powder coating material is formed on each outer peripheral surface of the core wire 2a, the middle wire 2b, and the outer wire 2c.

In this coating apparatus 9, even if the number of wires of the PC stranded wire is two or three or more,
By passing this area with the wires of each layer loosened, the wires of all the layers are painted at once, and a coating of the same thickness is formed on the wires of each layer. The thickness of the coating can be set to an arbitrary thickness by adjusting the line speed, that is, the passing speed and the spray amount.

After the powder coating film is formed on the core wire 2a, the middle inner wire 2b and the outer wire 2c in this manner, the film is sequentially moved to the post-heating device 10 in the next step.
As the heating means at 0, an appropriate heating means can be adopted, but for example, a high-frequency induction heating means which can easily adjust the temperature is preferable. Then, the adhered film of the powder coating is heated and welded by a high-frequency induction heating means at a predetermined temperature, for example, about 250 ° C., and as shown in FIG.
A rust-proof coating 40 having excellent adhesion is formed on the outer peripheral surface of the outer wire 2c.

After the rust preventive film 40 is formed, the returned portion is transferred to the next primary cooling device 11 as it is. The cooling means in this cooling device preferably comprises a shower zone through which water is poured, for example, in consideration of economy and simplicity.

In the primary cooling device 11, the rust preventive coating 4
0 is cooled to a predetermined temperature to be cured, but it is sufficient that the rust-preventive coating 40 is cooled to a temperature or hardness that hardly causes any problem in the processing in the next step. The coating device 9, the post-heating device 10, and the primary cooling device 11 are partitioned by a predetermined partition 41 as a processing zone.

After the coating process is completed, the expanded PC steel strand 2 is joined by the middle side wire gently closing device 13 so that the middle side wire 2b is first returned to the original stranded state with respect to the core wire 2a. You. The middle side line loosening device 13 performs a process for returning the middle side line 2b to the core wire 2a by adding the middle side line 2b and returning to the original stranded state, contrary to the above-mentioned relieving device 4. Yes, the specific configuration is substantially the same as that of the above-described defibrating device 4, and is used symmetrically. However, the difference is that the outer line 2c is not yet loosely closed. I have.

The middle wire loosening device 13 allows the core wire 2a
, A twist in a predetermined direction is added to the middle side line 2b,
Only the middle wire 2 is wound around the core wire 2a, and as shown in FIG. 8, the core wire 2a and the middle wire 2b are substantially in the original stranded state.

As shown in FIG. 6, the outer line 2c is maintained in the expanded state by the fourth expansion maintaining device 15,
Unlike the above-described first to third expansion maintaining devices, the fourth expansion maintaining device 15 has a large guide hole in the center portion and a plurality of radially extending holes (for example, at predetermined intervals from the guide hole). 9) are formed with guide holes for the outer lines 2c. The fourth expansion maintaining device 15 is provided at a predetermined interval from the middle line loosening device 13, and a middle line adjustment device 14 is provided between the four devices.

The middle side line adjusting device 14 has substantially the same structure as the core line adjusting device 6, and includes a fixed pulley 42 and a movable pulley 43, and the movable pulley 43 is fixed by an appropriate coil spring 44 or the like. It is urged away from the pulley 42. These pulleys are rotatably supported by appropriate support members 45.

Then, the middle side wire 2b wound around the core wire 2a is suspended between the fixed pulley 42 and the movable pulley 43 in the same manner as in the case of the core wire adjusting device 6, and its length with respect to the winding of the outer wire 2c. Is adjusted.

That is, the outer line gently closing device 16 provided adjacent to the fourth expansion maintaining device 15 adds the outer line 2c to the intermediate line 2b and winds it.
As shown in FIG. 9, the outer wire 2c is located on the outer circumference of the middle wire 2b, and a uniform anti-rust coating 40 is formed on the outer surfaces of the respective wires, that is, the core wire 2a, the middle wire 2b, and the outer wire 2c. Thus, the stranded state of the winding pitch substantially similar to that of the original PC steel stranded wire 2 can be restored.

In this case, the expansion maintaining device 15 rotates in synchronization with the first to third expansion maintaining devices 5, 7, and 12 at the preceding stage.
b and the forced rotation of the outer wire 2c accompanying the loosening of the outer wire 2c. The forced rotation of the loosening machine 32 in the loosening device 4 is transmitted to all the expansion maintaining devices via the middle side wire 2b and the outer wire 2c. Therefore, they rotate synchronously.
Accordingly, the outer line loosening device 16 loosening machine (not shown) also rotates at the same speed in the same direction as the loosening machine 32 of the loosening device 4.

As described above, the rotation due to the loosening of the PC steel strand 2 is transmitted to the slowly closing rotation as it is, during which the first to fourth rotations occur.
Of the core wire 2a by the expansion maintaining devices 5, 7, 12, 15
The expanded state of the middle side line 2b and the outside line 2c is maintained, and the processes in the pre-heating device 8, the coating device 9, the post-heating device 10 and the primary cooling device 11 are continuously performed, and at the same speed in the same direction. And the processing at the set line speed, the formation of the rust preventive coating 40 on the core wire 2a, the middle side line 2b and the outer side line 2c becomes uniform as a whole, and in the present invention, the thickness is approximately 200 μm. The film is uniformly formed.

Further, the relieving device 4 and the middle line loosening device 13 and the outside line loosening device 16 rotate synchronously in the same direction, so that the middle line 2b and the outer line 2 with respect to the core wire 2a.
Since the winding direction of c is the same direction before loosening and after loosening, the loosening operation by the middle side line loosening device 13 and the outer line loosening device 16, that is, rewinding operation is quick and easy. You can do it.

As described above, the PC steel wire 2 is loosened and the core wire 2a, the middle wire 2b, and the outer wire 2c are approximately 200 μm thick.
The thickness of the core wire 2a, the middle wire 2b, and the outer wire 2c is increased by the thickness of the rust preventive coating 40, respectively. The winding of the middle side line 2b with respect to the center side 2a and the outer side line 2c with respect to the middle side line 2b detour outward by the film thickness.

As described above, when the middle wire 2b and the outer wire 2c are wound in a circuitous manner, the length of the middle wire 2b with respect to the core wire 2a and the length of the outer wire 2c with respect to the middle wire 2b as compared with before the loosening. , Respectively, and the core wire 2a and the middle side wire 2b become excessive. According to the calculation, for example, when the loose closing operation of 1 m is performed, the core wire 2a has an extra length of about 0.7 mm with respect to the middle side line 2b. In this calculation, if one ton of the PC steel stranded wire 2 to be treated is to be coated and coated, for example, if the diameter of the PC steel stranded wire is about 12.7 mm, the diameter of the PC steel stranded wire is about 12.7 mm. The length of the wire is about 1300m, and when this is processed, the core wire 2a of 900mm per ton
And the middle side line 2b is similarly left over the outside line 2c.

Therefore, the surplus core wire 2a and middle side wire 2
In order to adjust b, in the case of the core wire 2b, the core wire adjusting device 6 is disposed between the first and second expansion maintaining devices 5 and 7, and in the case of the middle wire 2b, the middle wire is slowly closed. Device 13 and fourth
The middle side line adjusting device 14 is provided between the expansion maintaining devices 15. In each case, a U-turn is applied between the fixed pulleys 36 and 42 and the movable pulleys 37 and 43 to wind around them, and a surplus portion is automatically adjusted by moving the movable pulley.

Processed PC restored as described above
The steel strand 2 has the cross-sectional structure shown in FIG. 9 and is cooled to approximately normal temperature by the next secondary cooling device 17. And
The next outer diameter measuring device 18 uses the treated PC steel strand 2
Is measured to detect whether or not the anticorrosive film 40 having a predetermined thickness is formed.

The measurement is performed in two directions of the X axis and the Y axis. For example, when the thickness of the rust preventive coating 40 is set to 200 μm and the allowable error is set to ± 50 μm, the measured value exceeds the allowable error. And an alarm signal or act to stop the line.

Further, in the next step, the state of the rust preventive film 40 is detected by the binhole detecting device 19. In this case, when a pinhole is detected using a non-contact type, for example, an optical detection unit that does not damage the rust prevention coating 40,
It operates to mark, emit an alarm signal or stop the line at the detection location.

The treated PC steel strand 2 thus inspected is pulled up and down by the take-up device 20 having the endless belts 20a and 20b arranged vertically so as not to damage the rust preventive coating 40 from above and below. The take-up device 21 sequentially takes up the form of a coil.

In the above description, when the PC steel strand 2 is supplied from one end, at the initial stage, the end of the PC steel strand 2 is loosened by hand and loosened. While being inserted into the guide holes, each wire is pulled out to a predetermined length, and while maintaining the loosened state by the first to fourth expansion maintaining devices, the coating process can be performed, and the middle side line is slowly closed and the outer side line is closed. What is necessary is just to lead it out to the winding device so that it can be slowly closed. Alternatively, it may be derived using a dummy line. In the case of a dummy wire, the corresponding wires of the PC steel stranded wire to be processed may be connected by welding or the like.

In the above description, the treatment of a three-layered PC steel strand is described. However, the present invention is not limited to this, and a four-layered or more layered PC steel strand can be similarly treated. In short, no matter how many layers there are, the coating process for the wire material of each layer should be performed at the same position at the same time, and the adjustment of the core wire should be performed before the coating process, and the adjustment of the subsequent wire material should be performed immediately before closing slowly. It is important to do it.

[0043]

As described above, the PC according to the present invention is used.
As a specific means for solving the problems of the conventional example, the present invention provides a method for processing a rust-preventive coating on a steel stranded wire by sequentially winding a stranded portion of a PC steel stranded wire formed by winding a plurality of layers of wire around a core wire. Temporarily returning, forming a rust-preventive coating of a solvent type paint or a powder type paint on the outer peripheral surface of each wire including the returned core wire, and the forming process of the rust-preventive coating includes the core wire. Each wire is performed at once in the same area, the length of the core wire is adjusted before the rust-proof coating is formed, and the length of the wire after the next stage is adjusted immediately before the wire of each layer is loosely closed. By doing so, a uniform coating can be formed on the outer peripheral surface of the wire rod of each layer even with a PC steel stranded wire having a multi-layer structure, and for the shortage of the wire rod of the outer layer due to the thickness of the coating, By adjusting the wire of the inner layer by hand, the overall Reasonably can be returned to the original PC strand lines and substantially the same conditions, an excellent effect that efficiently perform processing of antirust coating.

Further, the apparatus for forming a rust-preventive film on a PC steel stranded wire according to the present invention comprises: a relieving device for temporarily relieving a wire of each layer with respect to a core wire of a PC steel stranded wire; By providing a loosening device that re-wires the wires of each layer again, and by having a coating device, a heating device, and a cooling device disposed between the loosening device and the loosening device on the previous stage,
Even if multiple layers of PC steel strands are used, the wires constituting each layer can be treated at once in a given area to form an anti-corrosion coating, and a uniform coating can be formed. The effect is excellent.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an entire rust-preventing coating forming apparatus according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a part A of a PC steel stranded wire processed by the apparatus.

FIG. 3 is an enlarged cross-sectional view of a portion B of the PC stranded wire where the strand is loosened.

FIG. 4 is a front view showing a release device in the same device.

FIG. 5 is a schematic sectional view of the release device.

FIG. 6 is an explanatory diagram schematically showing, in an enlarged manner, only a main part of the rust-preventing film forming apparatus according to the present invention.

FIG. 7 is an enlarged cross-sectional view of a rust-proof PC steel stranded wire in a portion C of FIG. 1;

8 is a PC in which a middle side line in a D part of FIG. 1 is loosely closed.
It is an expanded sectional view of a steel strand.

FIG. 9 is an enlarged cross-sectional view of a treated PC steel strand at a portion E in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Uncoiler apparatus 2 PC steel strand 2a Core wire 2b Middle side line 2c Outer line 3 Surface treatment device 4 Relief device 5 First expansion maintaining device 6 Core adjustment device 7 Second expansion maintaining device 8 Preheating device 9 Painting device DESCRIPTION OF SYMBOLS 10 After-heating apparatus 11 Primary cooling device 12 3rd expansion maintenance device 13 Middle side line slow closing device 14 Middle side line adjustment device 15 4th expansion maintenance device 16 Outside line slow closing device 17 Secondary cooling device 18 Coating outer diameter Measuring device 19 Film pinhole detecting device 20 Pulling device 20a, 20b Endless belt 21 Winding device 30 Stand 31 Ring-shaped radial ball bearing 32 Loosening machine 33 Core wire guide holes 33a, 34a, 35a Bush 34 Middle side guide hole 35 Outer wire Guide holes 36, 42 Fixed pulley 37, 43 Movable pulley 38, 44 Coil spring 39, 45 Support member 40 Rust prevention Coating 41 partition

Claims (5)

(57) [Claims] 1. A stranded portion of a PC steel stranded wire formed by winding a plurality of layers of a wire around a core wire and temporarily returning the stranded portion together, and a solvent type wire is attached to the outer peripheral surface of each wire material including the returned core wire. A rust-preventive film is formed by paint or powder type paint. The process of forming the rust-preventive film is carried out at once in the same area for each wire including the core wire. A method for forming a rust-preventive film on a PC steel strand, wherein the length adjustment is performed immediately before the wires of each layer are loosely closed. 2. The method according to claim 1, wherein the returned wire rod of each layer is maintained over a predetermined length by a plurality of expansion maintaining means, and a rust-preventive film is formed by applying paint and heat welding during that time. Item 4. The method for forming a rust-preventive coating on a PC stranded wire according to Item 1. 3. The process for forming a rust-preventive film on a stranded PC steel wire according to claim 1, wherein the effect of the twisting is utilized for the effect of twisting the respective layers via the expansion maintaining means. Method. 4. A loosening device for temporarily loosening the wire of each layer with respect to the core wire of the PC stranded wire, and a loosening device for twisting the wire of each layer again with respect to the loosened core wire,
An apparatus for forming a rust-preventive film on a PC steel strand, comprising a coating device, a heating device and a cooling device disposed between a release device and a release device on the front side. 5. A core wire adjusting device is provided between a release device and a coating device, and a wire rod adjusting device for forming a layer is provided immediately before a loose closing device for forming a next layer. The apparatus for forming a rust-proof coating on a PC steel strand according to claim 4.