JP2552604B2 - Method for forming synthetic resin coating on PC steel strand and PC strand formed with synthetic resin coating - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin coating forming method for providing a free length portion which is an elastic body and a fixing length portion which is a load bearing body when a PC stranded wire is used for a permanent anchor or the like. It relates to a PC steel strand with a synthetic resin coating obtained by carrying out the method.

[0002]

2. Description of the Related Art Generally, when a PC steel stranded wire is used for a permanent anchor or the like, it is necessary to form some kind of coating layer in order to provide a free length portion serving as an elastic body and a fixing length portion serving as a load bearing body. The reason is that the free length portion that becomes the elastic body must be an elastic body that can slide freely in the axial direction with less frictional resistance against concrete even after being solidified by concrete, and the load bearing body and This is because the fixed length portion has to have a large adhesive force by perfect adhesion to concrete. However, up to now, there is no coating layer forming method for providing the free length portion and the fixing length portion, and therefore a coating layer forming processing method satisfying the above conditions has not been realized yet.

In reality, the invention by the same inventor as the invention of the present invention, "Unbonding method for PC stranded wire", Japanese Patent Publication No. 2
The one disclosed in JP-A-60504 is used, or the one coated with a resin coating layer without heating the PC steel wire at all by the processing method is used. The content of the above-disclosed invention is that, in providing an extruder resin coating layer on a PC steel wire, the primary wire coating layer is formed by heating the PC steel wire at least 50 ° C. higher than the resin pellet melting temperature. An unbonding method for a PC steel strand in which after cooling it, a thin layer of oil or fat is thinly applied to the surface, or a secondary resin coating layer is formed on the surface by an extruder method or the like without application. It is.

Other means include, for example, Japanese Patent Publication No.
There is an invention of "reinforcing bar for prestressed concrete and a method for manufacturing the same" disclosed in Japanese Patent Laid-Open No. 3-47609, and the content thereof is "a multi-strand-one-wire cord, particularly a grease-like composition regarding permeation and fluidity during operation. Covered with a tensided corrosion inhibitor, the corrosion inhibitor smoothed and shaped to give a canopy with a circular surface around the cord, the diameter of the circle being at least 2 mils greater than the diameter of the cord. Reinforcement and pre-stressed concrete rebar wherein a seamless plastic tubular jacket is extruded and contracted around the sheathed twister to provide a snug jacket. "

[0005]

As is clear from the description of the detailed description of the invention, the above-mentioned unbonding method has a rust preventive effect by fusing a primary resin coating layer on the surface of a PC steel wire. The purpose is to increase
C steel stranded wire at least 50 from resin pellet melting temperature
The primary resin coating layer is provided by heating at a temperature higher than ℃. Therefore, in order to form the fixed length portion which becomes the load bearing body, it is not easy to work off the primary resin coating layer from the surface of the PC steel wire.

Further, as described above, the one in which the primary resin coating layer is formed without heating the PC steel wire at all is used, but in this case, the rust preventive power of the entire PC steel wire is remarkably lowered. However, there is a problem of corrosion of the free length portion that becomes the elastic body, which is not desirable.

Further, as is clear from the section of the detailed description of the invention, the above-mentioned manufacturing method is an unbonding method for a PC steel wire, and the PC steel wire formed by this method has its surface. Even if the resin coating layer of the fixing length part that becomes the load bearing body is peeled off, the grease coating layer remains, and the adhesion or adhesion to concrete is greatly reduced. Cannot be used as.

For example, in the above-mentioned manufacturing method, the application of grease to the portion which becomes the fixing long portion is partially stopped, the coating layer is processed, and the coating layer at the corresponding portion is peeled off to form the fixing long portion. In this case, if the lengths of the free length portion and the fixing length portion are not determined, not only can the coating layer be processed, but there is also a change in either the free length portion or the fixing length portion. , Even if the coating layer is bent, it cannot be used.

In any case, in the conventional example, the free length portion serving as the elastic body and the fixing length portion serving as the load bearing body have arbitrary lengths, and the free length portion has sufficient rust preventive power and the fixing length. The part has a problem to be solved in that it can be easily formed so as to obtain sufficient adhesion to concrete.

[0010]

As a specific means for solving the above-mentioned problems of the prior art, the present invention is to twist a plurality of side wires around a core wire and loosen a PC steel stranded wire which has been subjected to predetermined bluing. Temporarily loosen the twisting while heating to a temperature at which plastic working strain does not occur, and by utilizing the heating temperature, synthetic resin powder paint is melted and adhered to the outer periphery of each of the core wire and the side wire to make the synthetic resin powder. After forming an inner layer of coating and restoring the loosened twist, a synthetic resin coated middle layer cylinder is provided on the surface by synthetic resin extrusion molding means, and a lubricant is further applied to the surface thereof, and then synthetic resin extrusion molding means. P forming a synthetic resin coating the outer layer tube, wherein the synthetic resin powder coating inner layer and the synthetic resin coating intermediate tube, characterized in that formed using the peeling easily plastic properties is different by Synthetic resin coating forming method of processing lines than steel, and the core wire twisted PC multiple lateral line around the
A steel stranded wire is provided with a synthetic resin-coated middle layer cylinder and a synthetic resin-coated outer layer cylinder by means of synthetic resin extrusion molding, and a lubricant is interposed between the synthetic resin-coated middle layer and the synthetic resin-coated outer layer cylinder. , On each outer circumference of the core wire and the side wire ,
Synthetic resin-coated middle layer cylinders and synthetic resin powder coatings having different properties that are easily peeled off are melt-adhered to form respective synthetic resin powder-coated inner layers, which are PC steel stranded wires formed with synthetic resin coatings. Is.

[0011]

According to the present invention, since the PC steel stranded wire is temporarily and gradually loosened by heating it to a temperature at which plastic working strain does not occur, variations occur in the elongation between the side wires, and twisting and restoration is performed before loosening. There is no reason not to return to the state of. Then, by forming a synthetic resin-coated middle-layer cylinder having different properties that does not fuse with the synthetic resin powder melt-coated inner layer formed on the front circumference of each of the side wire and the core wire, a fixing length portion that becomes a load bearing body is formed. In this case, the middle-layer cylinder can be easily peeled off, and the core wire and side wires are covered with the synthetic resin powder melt-coated inner layer, so not only is it excellent in rust resistance, but also the synthetic resin powder melt-coated inner layer and concrete. Adhesive strength with is stronger than that of bare PC steel. Also,
In the free length portion serving as the elastic body, the lubricant is interposed between the synthetic resin-coated middle-layer cylinder and the synthetic resin-coated outer-layer cylinder, so that it easily slides and the friction coefficient becomes extremely small.

[0012]

EXAMPLES Next, the present invention will be described in more detail with reference to the examples shown in FIGS. 1 to 15. FIG. 1 is a block diagram showing the arrangement of each device of the synthetic resin coating forming method, and PC steel stranded wire. 10 unwinding devices 31 are located at one end,
A shaft hole of a drum 32 on which the PC steel wire 10 is wound is rotatably supported and housed in the rewinding device.
The PC steel stranded wire 10 in this case is, as shown in FIG.
Twist a plurality of side wires 10a around the core wire 10b,
And it has been bluing.

Reference numeral 33 denotes a feeding device on the supply side, which presses a pair of drive endless belts 33a and 33b into pressure contact with each other and sandwiches the PC steel wire 10 drawn out from the rewinding device 31 between them to drive both endless belts 33a. , 33b
I am forced to send it by driving.

Reference numeral 34 denotes a deposit removing device for the PC stranded wire 10, which can be used, for example, by shot blasting, and sprays fine steel balls, slabs, etc. onto the surface of the PC stranded wire 10,
It is designed to remove deposits such as rust and oil.

Reference numeral 35 denotes a heating device, for example, a high frequency induction heating device is used, which is heated to a temperature at which plastic deformation does not occur even if the twisting of the PC steel strand 10 is loosened, for example, 300 to 350 ° C. is there. Reference numeral 36 denotes a loosening device, which loosens the twisted portion of the PC steel strand 10 by the loosening device to widen between the side wires 10a and the core wire 10b.

As shown in FIG. 2, in the loosening device 36, a loosening guide plate 39 is fixed to a rotary cylinder 38 rotatably supported by a frame 37, and the loosening guide plate 39 is connected via a chain 40. It is made to rotate by the motor 41. As shown in FIGS. 3 and 4, the loosening guide plate 39 is provided with a core wire guide tube 42 at its center,
Further, side line guide holes 43 are provided on the same circumference with a required space around them, and a chain wheel 44 is integrally provided on the outer peripheral surface.

Reference numeral 45 is a powder coating material supply device, and as shown in FIGS.
Radially arranged spray guns 47 in three directions at intervals.
Relieved part 1 of the PC steel strand 10 from the spray gun 47
It sprays a synthetic resin powder paint such as polyethylene or epoxy together with air toward 0F. The synthetic resin powder paint sprayed has a heating temperature of 300 to 35.
The synthetic resin powder melt coating inner layer 23 is formed by melting and adhering to the entire circumference of the side wire 10a and the core wire 10b at 0 ° C.

Reference numeral 48 denotes a post-heating device, which acts to make the melt-adhered synthetic resin powder melt-coated inner layer 23 uniform. Reference numeral 49 denotes a cooling device, which cools the coated portion 10A of the PC steel wire after the synthetic resin powder molten coating inner layer 23 is formed by circulating water or cold air to room temperature.

Reference numeral 55 denotes an extruder for forming a synthetic resin-coated middle layer cylinder 24 on the surface of the coated portion 10A of the PC stranded wire. 56 is a cooling device,
Water or cold air is circulated to cool the coated portion 10B on which the synthetic resin-coated middle-layer cylinder 24 is formed to room temperature.

Reference numeral 57 denotes a lubricant applying device, which applies a lubricant 26 such as grease to the surface of the coated portion 10B. Reference numeral 58 denotes an extrusion molding machine for fitting and coating the synthetic resin-coated outer layer cylinder 25 on the surface of the coated portion 10B coated with the lubricant 26.

Reference numeral 59 denotes a cooling device for circulating water or cold air to cool the coated portion 10C on which the synthetic resin coated outer layer cylinder 25 is formed to room temperature. Reference numeral 50 denotes a pulling device, which has a pair of endless belts 50a and 50b that are driven in pressure contact with each other, and forcibly pulls out the wire 10 by sandwiching the wire 10 from the PC steel having the synthetic resin-coated outer cylinder 25 formed thereon.

Reference numeral 51 is a winding device provided at the other end of the winding device. The winding device houses a wooden drum 52 rotatably, and the processed PC steel strand 10 drawn by the drawing device 50. It is to wind up sequentially. still,
Reference numeral 53 is a winding device for the leading wire 54 for preparatory work.

Next, a method for forming a coating of PC steel strand according to the present invention using the apparatus having the above-mentioned structure will be described.
This device performs preparatory work prior to continuous operation. First, the tip end of the PC steel wire 10 is pulled out from the rewinding device 31, sandwiched between the endless belts 33 a and 33 b of the feeding device 33, and passed through the inside of the deposit removing device 34 to release the loosening device 36.
Send up to.

In the loosening device 36, the PC steel strand 1
As shown in FIG. 6, the side wires 10a are loosened in the side wire guide holes 43 of the loosening guide plate 39, and the core wires 10b are connected to the core wire guide tube 42 as shown in FIG. Insert each into, and as shown in FIG.
The loosened portion 10F having a certain length L is formed, and the tip side is manually twisted again. This re-twisting does not require much labor because each side wire 10a is permanently deformed to a more state. Then, the leading wire 54 is fixed to the twisted tip portion.

The lead wire 54 is the powder coating supply device 4
5, post-heating device 48, cooling device 49, extruder 55,
It is wound around the lead wire winding device 53 through the cooling device 56, the lubricant applying device 57, the extrusion molding machine 58, the cooling device 59, and the drawing device 50.

When each device is driven in this state to start continuous operation, the PC steel strand 10 is continuously drawn out from the rewinding device 31 to the feeding device 33, and passes through each device to obtain a predetermined synthetic resin. The coating forming process is performed, and the drawing device 50 sequentially draws. Then, when the portion that has been subjected to the synthetic resin coating forming process is pulled out of the drawer device 50, the incomplete portion on the tip side is cut, and the synthetic resin that is successively drawn out is completely covered. The wound PC steel wire is wound on the wooden drum 52 of the winding device 51.

Among the synthetic resin coating forming methods described above, the coating layer forming treatment step up to the inside (side wire / core wire) of the PC steel stranded wire 10 and the coating layer formation of the fixing length portion will be described. Between the feeding device 33 and the drawing device 50, the PC steel stranded wire 10 is prevented from rotating in the circumferential direction while applying a constant tension by proportional control, and is moved only in the axial direction.

In the heating device 35, the relaxation device 36 in the next step is used.
In the above, the twisting of the PC steel wire 10 is loosened, but the PC steel wire 10 immediately before the softening is heated to a temperature at which plastic working strain does not occur due to the loosening, for example, about 300 to 350 ° C. Then, the PC steel strand 10 is sent to the loosening device 36 while being heated.

In the relieving device 36, the PC steel stranded wire 1
In accordance with the twisting pitch of 0, the loosening guide plate 39 is rotated by the motor 41 in the twisting direction, whereby the PC steel strand 10 is always unraveled by the constant length L unraveled in the previous preparation work. The state is maintained, and after moving for a certain length L, the lines are automatically twisted again.

The unfixed constant length L is one in which the synthetic resin powder coating material, which will be described later, is sprayed and begins to cure after being melted and adhered by the heating temperature for preventing plastic deformation strain due to the above-mentioned loosening. The length is set in advance to maintain the loosened state.

The heating performed by the heating device 35 is for performing the loosening of the PC steel stranded wire 10 in a warm state at a predetermined temperature, and unlike the conventional case of performing the cold loosening, the side wire No processing strain occurs in 10a and the bluing effect is maintained, so when twisting is returned again,
Each lateral line 10a is completely restored to its original state. At the same time, the heating also serves to form a synthetic resin powder melt coating inner layer 23 by melting and closely adhering the synthetic resin powder coating material to the entire circumferences of the side wire 10a and the core wire 10b.

PC steel stranded wire 1 loosened in the above-mentioned state
0 enters the spray booth 46 of the powder coating supply device 45, and the synthetic resin powder coating applied with a negative charge is sprayed by the spray gun 47, which is given a positive charge by the relieving device 36. Lateral line 10a
9 and adheres to the surface of the core wire 10b and melts and adheres to the surface of the core wire 10b. As shown in FIG. 9, a synthetic resin powder melt-coated inner layer 23 having a substantially uniform thickness is formed on the outer periphery of each side wire 10a and the core wire 10b by so-called electrostatic coating. It

Thus, the synthetic resin powder melt-coated inner layer 23
As a result of being formed and passing through the fixed length L and being twisted again, as shown in FIG. 10, each side wire 10a is twisted around the core wire 10b around the core wire 10b, and complete protection is achieved. Rust treated PC steel wire 10A is obtained. Then, the surface of the synthetic resin powder melt-coated inner layer 23 is re-heated by the post-heating device 48 to be uniform, and the synthetic resin powder melt-coated inner layer 23 that is cooled and melt-adhered by the subsequent cooling device 49 is completely formed. Hardened.

The above-mentioned post-heating device 48 is not always necessary depending on the kind of the synthetic resin powder paint,
Further, the powder coating means by the so-called electrostatic coating method, in which a positive charge is applied to the PC steel wire and a negative charge is applied to the powder coating material, the powder coating means has been described. It is also possible to employ a so-called fluidized-bed powder coating method in which the material is heated and passed through a fluidized-bed tank, or the electrostatic coating method and the fluidized-bed powder coating method are used in combination.

As described above, each side wire 10a and core wire 10
This is a so-called rustproof PC steel strand 10A in which the synthetic resin powder melt coating inner layer 23 is formed on the entire surface of b. In order to easily provide the free length 60 portion and the fixing length 61 portion on the rustproof PC steel strand 10A, the extruder 55 does not weld the synthetic resin powder melt coating inner layer 23. The synthetic resin-coated middle-layer cylinder 24 having different properties is formed, and the lubricant 26 for reducing the frictional resistance of the free length 60 portion is applied to the surface of the synthetic resin-coated middle-layer cylinder 24 by the lubricant applying device 57.

Then, the synthetic resin-coated outer layer cylinder 25 is fitted and coated on the coated surface of the lubricant 26 by the extrusion molding machine 58 of the next stage, cooled to room temperature by the cooling device 59, and continuously drawn by the drawing device 50. And is sequentially wound by the winding device 51. The PC stranded wire processed in this way has a cross-sectional structure as shown in FIG.

The PC steel stranded wire of the present invention, which has been subjected to the synthetic resin coating forming process as described above, corresponds to the use part thereof.
The free length 60 part which becomes an elastic body by cutting into a predetermined length and the fixing length 61 part which becomes a body are dimensionally indexed, and the part which becomes the fixing length 61 is a synthetic resin-coated outer layer cylinder 25 and a synthetic resin-coated middle layer. By peeling off 24, it can be easily obtained with high dimensional accuracy. In particular, since the synthetic resin-coated middle layer cylinder 24 is formed of a material that is easily peeled from the synthetic resin powder melt-coated inner layer 23, the peeling work can be performed very easily.

Since the fixed length 61 portion is almost completely rustproofed by the synthetic resin powder melt coating inner layer 23, for example, in the JISz2371 salt spray test result, even after 2000 hours, no rust is found. However, it showed excellent rust resistance. Regarding the adhesion between the fixed length 61 part and the concrete, for example, even when used in the pretensioning method in the prestressed concrete construction method, the concrete adhesion force is based on the fixing length test result, and the strength numerical value is equal to or more than the bare PC steel wire which is conventionally used. Indicated.

[0039]

As described above, according to the method for forming a synthetic resin coating of a PC steel wire according to the present invention, a plurality of side wires are twisted around the core wire and a predetermined blueing is applied to the P wire.
While heating the C steel stranded wire to a temperature at which plastic deformation strain does not occur due to the loosening, the twisting is gradually loosened sequentially, and the heating temperature is used to apply the synthetic resin powder paint to the outer circumferences of the core wire and the side wires. After forming a synthetic resin powder-coated inner layer by melt-adhesion and restoring the loosened twist, a synthetic resin coated intermediate layer cylinder is provided on the surface by synthetic resin extrusion molding means, and a lubricant is further applied to the surface. Then, the synthetic resin coated outer layer cylinder is formed by the synthetic resin extrusion molding means,
The synthetic resin powder-coated inner layer and the synthetic resin-coated middle layer cylinder are formed by using a synthetic resin having different properties and easily peeled off , and the PC steel wire is heated at a temperature at which plastic deformation strain does not occur. While relieving, the subsequent restoration can be easily performed, and the heating temperature is utilized to provide an excellent effect that a substantially uniform synthetic resin powder melt-coated inner layer can be easily formed on the side wires and core wires in the relieved state. Play.

Further, since the synthetic resin powder melt-coated inner layer and the synthetic-coated middle-layer cylinder formed on the surface of the synthetic resin powder are made of a synthetic resin which has different properties so as not to be welded integrally and which is easily peeled off , the space between the two is simple. This has the excellent effect that the free length portion and the fixed length portion can be easily formed with high dimensional accuracy.

Further, the PC steel stranded wire formed with the synthetic resin coating according to the present invention is synthesized with the synthetic resin coated middle layer cylinder by the synthetic resin extrusion molding means on the PC steel stranded wire in which a plurality of side wires are twisted around the core wire. A resin-coated outer layer cylinder is provided, a lubricant is interposed between the synthetic resin-coated middle layer and the synthetic resin-coated outer layer cylinder, and the synthetic resin-coated middle-layer cylinder is provided on each outer periphery of the core wire and the side wire. Different in easy peeling property
The synthetic resin powder coating material is melted and adhered to form the synthetic resin powder coating inner layer, and the synthetic resin coating inner layer is formed. Not only can the free length part and the fixed length part be easily formed by partially peeling off the synthetic resin-coated outer layer cylinder, but the friction resistance of the free length part can freely slide in the axial direction due to the presence of the lubricant. Since it can be done, it is significantly smaller than the conventional one, and the fixing length part is rustproofed by the synthetic resin powder melt coating inner layer, so of course no rust is generated, especially synthetic resin powder melt coating With respect to the adhesion between the inner layer and concrete, various excellent effects such as being significantly stronger than the conventionally used bare PC steel wire are exhibited.

Furthermore, when forming the free length portion and the fixed length portion, the work of peeling the synthetic resin-coated middle layer cylinder and the synthetic resin-coated outer cylinder from the synthetic resin powder melt-coated inner layer is performed by the core wire.
And it is easy to peel off from the synthetic resin coated middle layer cylinder on each outer circumference of the side line
Synthesized by melting and adhering synthetic resin powder coatings with different properties
Since the inner layers coated with resin powder are formed separately , the middle layer cylinder and outer layer cylinder are peeled off at the same time with the lubricant coating layer wrapped around them.
It is possible to obtain the excellent effect that there is no possibility that the lubricant adheres to the fixing long portion.

[Brief description of drawings]

1 is a block diagram schematically showing the steps of carrying out the method for forming a synthetic resin coating of a PC steel strand according to the present invention. 2 is a schematic cross-sectional view of the relaxation device included in the steps of the method. 3 is a front view showing a loosening guide plate of the same loosening device. 4 is a side sectional view of the loosening guide plate. 5 is a front view schematically showing the main part of the powder coating material supply device included in the steps of the method. <Figure 6> In the execution of the method, it is the side view which unravels and shows the tip of the PC stranded wire. 7 is a side view showing a state in which the tip of the PC stranded wire is unraveled and inserted into the loosening guide plate in carrying out the method. 8 is an enlarged cross-sectional view of a PC steel strand before carrying out the method of the present invention. 9 is an enlarged cross-sectional view of a state in which the synthetic resin powder melt coating inner layer is formed in a loosened state in the practice of the present invention. FIG. 10 is an enlarged cross-sectional view of a state in which the alignment is restored after forming the synthetic resin powder melt-coated inner layer in the practice of the invention. 11 is an enlarged cross-sectional view of a state in which a synthetic resin coated middle cylinder is formed in the practice of the present invention. 12 is an enlarged cross-sectional view of a PC steel strand completed by forming a synthetic resin powder-coated outer layer cylinder after applying a lubricant in the practice of the present invention. FIG. 13 is a side view showing a part of a state in which a free length portion and a fixing length portion are formed using a PC steel strand completed by carrying out the present invention. 14 is a cross-sectional view taken along the line AA of FIG. 15 is a cross-sectional view taken along the line BB of FIG.

[Explanation of symbols]

 10 PC Steel stranded wire 10a Side wire 10b Core wire 10A Corrosion-proof treated portion 10B, 10C Coated processed portion 10F Relieved portion 23 Synthetic resin powder melt coating inner layer 24 Synthetic resin coated middle layer cylinder 25 Synthetic resin coated outer layer cylinder 26 Lubricant 31 Rewinding Device 32 Drum 33 Feeding device 33a, 33b Drive endless belt 34 Adhesion removing device 35 Heating device 36 Releasing device 37 Frame 38 Rotating cylinder 39 Releasing guide plate 40 Chain 41 Motor 42 Core wire guide cylinder 43 Side wire guide hole 44 Chain wheel 45 Powder Paint supply device 46 Spray booth 47 Spray gun 48 Post-heating device 49 Cooling device 50 Drawer device 50a, 50b Endless belt 51 Winding device 52 Wooden drum 53 Winding device 54 Lead wire 55 Extrusion molding machine 56 Cooling device 5 7 Lubricant coating device 58 Extrusion machine 59 Cooling device

Claims (3)

(57) [Claims] 1. A plurality of side lines are twisted around a core wire,
While heating the PC steel wire that has been subjected to the prescribed bluing to a temperature at which plastic deformation does not occur due to relaxation, the twisting is gradually relieved sequentially, and the heating temperature is used to
A synthetic resin powder coating is melt-adhered to each outer circumference of the core wire and the side wire to form a synthetic resin powder coating inner layer, and after the loosened twist is restored, a synthetic resin coating middle layer is formed on the surface thereof by a synthetic resin extrusion molding means. A cylinder is provided, and then a lubricant is applied to the surface thereof to form a synthetic resin-coated outer layer cylinder by a synthetic resin extrusion molding means. The synthetic resin powder-coated inner layer and the synthetic resin-coated middle layer cylinder have different properties. Peeling
P made of a synthetic resin that is easy to process
A method for forming a synthetic resin coating on a C steel stranded wire. 2. The synthetic resin powder coating inner layer is electrostatic coating means,
2. The method for forming a synthetic resin coating on a PC steel strand according to claim 1, which is formed by fluidized dipping powder coating means or a combination thereof. 3. A PC steel stranded wire in which a plurality of side wires are twisted around a core wire is provided with a synthetic resin coated middle layer cylinder and a synthetic resin coated outer layer cylinder by synthetic resin extrusion molding means,
A lubricant is interposed between the synthetic resin-coated middle layer and the synthetic resin-coated outer layer cylinder, and the property of easily peeling from the synthetic resin-coated middle layer cylinder is different on each outer circumference of the core wire and the side wire.
Synthetic resin powder coating melt adhesion is caused by the synthetic resin powder coating inner layer respectively formed PC strand forming a synthetic resin coating, characterized in that the.