JPS5847516B2 - PC steel stranded wire with sheath for unbonded construction method and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sheathed PC steel stranded wire used as a rock anchor and an earth anchor by an unbonding construction method, and to an improvement in a manufacturing method thereof.

Conventionally, sheathed PC steel stranded wire for unbonded construction method was ■
A grease and plastic coating is applied over the entire length of the drum, and this is applied to the unbonded section (usually 10 to 20 m).
) and a fixing section (usually 3 to 5 m) are cut into lengths, and the sheathing material and grease are removed from the fixing section so that a sufficient bond is formed with the grout material.

This grease is removed using steam, hot air, or a solvent, but this process is very time-consuming and not only increases the cost of the product, but also makes it difficult to ensure complete degreasing. Bonding properties tended to be insufficient, and there were also problems in terms of quality.

The purpose of the present invention is to solve the drawbacks of the prior art, and the fixing part of the sheathed PC steel strand is not coated with a rust preventive agent, thereby saving the trouble of degreasing and making it possible to eliminate the need for grouting. The present invention provides a sheathed PC steel stranded wire with excellent bonding properties and a method for manufacturing the same.

Hereinafter, the present invention will be explained with reference to drawings of embodiments.

Figure 1 shows a sheathed PC steel wire 2 buried in the ground in a hole in the ground 1, and a predetermined length of PC steel wire 3 at its tip. 7. Apply grout milk 1 to this part by exposing it to form fixing part B.
It is combined with 0.

In the present invention, the sheathed PC steel strands are formed as shown in FIG. 2, FIG. 3, or FIG. 4.

That is, in FIG. 2, the outer peripheral surface of the PC steel stranded wire 3 is coated with a rust preventive agent 4 such as grease intermittently at regular intervals in the length direction, and the outer peripheral surface is coated with a sheath material 20 such as synthetic resin. As a result, unbonded parts A coated with the rust preventive agent 4 and fixing parts B without the rust preventive agent are alternately formed.

The lengths of the unbonding part A and the fixing part B are set depending on the purpose of use, and the unbonding part A and the fixing part B are combined to form one unit of sheathed PC steel stranded wire.

In FIG. 3, the sheath material 20 is coated only on the intermittently coated portions of the grease 40, and the anchoring portion B exposes the PC steel stranded wire 3.

In addition, in FIG. 4, a nonwoven fabric 5 such as plastic, rubber, cloth, etc. is wrapped around the outer peripheral surface of the PC steel stranded wire 3 only at the fixing part B, and the outer periphery is wrapped with an IJ over the entire length of the PC steel stranded wire 3. The outer periphery is further coated with a sheathing agent 20 over the entire length.

In the case of FIG. 4, the rust preventive agent 4 such as grease and the sheathing agent 20 do not necessarily need to be coated over the entire length, and may be coated only on the unbonded portion.

In that case, the nonwoven fabric 5 may be wound at a slightly longer interval than the unbonded portion to prevent the rust preventive agent 4 from adhering to the outer surface of the PC steel stranded wire 3 at the fixing portion.

In addition to this, various modifications are possible as long as the structure can prevent the rust preventive agent from adhering to the outer surface of the fixing part BI7) PC steel stranded wire.

In each of the above configurations, if the fixing part B and the unbonding part A are cut into lengths as one unit, it is possible to easily form the fixing part B with the PC steel strand 3 exposed at each end. .

That is, in FIG. 2, the sheath material 2 of the fixing section B is cut after cutting.
All you have to do is peel off 0, and in Figure 3, you can leave it as it is cut.
Further, in FIG. 4, the sheath material 20 and the nonwoven fabric 5 may be peeled off.

Moreover, in both cases, the PC steel stranded wire 3 of the anchoring part B has a rust preventive agent 4.
Since there is no adhesion, it is possible to create a fixing surface with excellent bonding properties without performing a degreasing process.

A concrete cylinder with a diameter of 100 mm and a length of 200 mm was attached to the anchoring part B of the PC steel stranded wire with a diameter of 12.4iπ formed in this way, and the adhesion strength was compared with that of the conventional method. The result is shown in Figure 6.

In addition, in the conventional method, the diameter of the PC steel stranded wire and the length of the concrete tube are the same as those above, and the anchoring part is degreased with steam after removing the grease, and then the concrete tube is attached. .

Then, a force was applied to the PC steel stranded wire to pull it out of the tube, and the relationship between the pull-out force (tensile load) and the amount of pull-out was investigated.

In FIG. 6, numeral 15 is the load-dislodgement curve for the product of the present invention, and 16 is the load-removal curve for the conventional product. It can be seen that the product of the present invention has an adhesion force that is more than twice that of the conventional product.

Next, a method for manufacturing the above-mentioned sheathed PC steel stranded wire will be explained.

In FIG. 7, 6 is an electromagnetic automatic counter, 7 is a grease nozzle, 8 is a resin coating machine, 9 is a resin crimping device, 11 is a water cooling tank, 50 is a rubbing machine, 90 is a grease pump, 91 is a grease tank, 92 is a solenoid valve, and 60 is a timer.

In order to manufacture the PC steel stranded wire shown in FIG.
and the length of the anchoring part B, and set the length of the PC steel stranded wire 3.
is transferred at a constant speed, and the transfer length is measured by an electromagnetic automatic counter 6.

While being transferred, the PC steel stranded wire 3 is coated with a rust preventive agent 4 by a grease nozzle 7, then coated with a sheath material 20 by a resin coating machine 8, and sent into a water cooling tank 11.

When this coating reaches a predetermined length of the unbonded part A, this is measured by the electromagnetic auto-counter 6, and this measurement signal is sent to the electromagnetic valve 92 to remove the grease that was being supplied from the grease tank 91 to the grease nozzle 7. Return to tank 91.

Then, the coating of the grease is stopped for a predetermined length of the fixing part B, and when the unbonding part is reached again, the solenoid valve 92 is switched by a signal from the electromagnetic automatic counter 6 and starts supplying grease to the grease nozzle 7. Thereafter, the unbonding part A and the fixing part B are formed alternately by the same operation.

In addition, in order to manufacture the sheathed l-PC steel stranded wire shown in Fig. 3,
Almost the same as above, after the coating by the grease nozzle 7 is stopped, the time until the end of the coating reaches the resin coating machine 8 is delayed by the timer 60, and the operation of the resin coating machine 8 is stopped.

Also, when coating with the rust preventive agent is started, the timer 60 is used to delay the start of operation of the grease nozzle I by a certain period of time, and then the operation of the resin coating machine 8 is started.

Further, when the starting end and the terminal end of the resin coating reach the resin crimping device 9, the resin crimping device 9 is operated to bring the end of the sheath material 20 into close contact with the PC steel stranded wire 3.

Furthermore, in order to manufacture the sheathed PC steel stranded wire shown in FIG.
When the predetermined length of the fixing part B is reached, the winding is stopped by a signal from the electromagnetic automatic counter 6, and when the predetermined length of the unbonding part A is reached, the winding is restarted by the signal from the electromagnetic automatic counter 6. Then, while repeating this process, the rust preventive agent 4 and the sheath material 20 are coated.

Even in this case, the coating with the rust preventive agent 4 and the sheath material 20 may be performed intermittently in the manner described above.

As explained above, the present invention prevents coating agents such as grease from adhering to the fixing part of the sheathed PC steel stranded wire, thereby eliminating the need for degreasing treatment and significantly improving the bonding properties to grout. It is something that

In addition, the manufacturing method is such that the prestressed steel strands are transferred and measured with a measuring device to automatically determine which areas are coated with rust preventive and which areas are not, and are degreased before use. Since there is no need to carry out this process, the structural cost can also be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view of a sheathed PC steel strand in a buried state, Fig. 2 is a partial longitudinal cross-sectional view showing an embodiment of the present invention, Fig. 3 is a longitudinal cross-sectional view showing another embodiment, and Fig. 4 is a vertical sectional view showing still another embodiment, FIG. 5 is a sectional view taken along the line V-V in FIG. 2,
Figure 6 is a comparison diagram of bonding properties between the product of the present invention and the conventional product.
The figure is a conceptual diagram of an apparatus for explaining the method of the present invention. 2... Sheet PC steel stranded wire, 3...
PC steel stranded wire, 4... Rust preventive agent, 5...
Non-woven fabric, 6...Electromagnetic autocoat/ta, 7...
... Grease nozzle, 8 ... Resin coating machine, 2
0...Sheath material.

Claims (1)

[Scope of Claims] I A sheath formed by covering a PC steel strand with a sheath material such as a synthetic resin} A PC steel strand, which is provided at regular intervals along its length on the outer peripheral surface of the PC steel strand. A sheathed PC steel stranded wire for unbonded construction, characterized in that it is coated with a rust preventive agent such as grease intermittently. 2 A sheathed PC steel stranded wire made by covering a PC steel stranded wire with a sheath material such as a synthetic resin, which has a sheathed PC steel wire intermittent at regular intervals in the length direction on the outer circumferential surface of the PC steel stranded wire to prevent grease, etc. A sheathed PC steel stranded wire for use in an unbonded construction method, characterized in that the wire is coated with a rust agent, and only the portion coated with the rust preventive agent is coated with a sheath material. a. A method for manufacturing a sheathed PC steel stranded wire, which is made by covering a PC steel stranded wire with a sheath material such as a synthetic resin, in which the PC steel stranded wire is transferred in its length direction, and a measuring device and a rust preventive agent are used. passing through a coating device and a sheath material coating device in sequence;
The above measuring device measures the areas coated with rust preventive agent on the passing PC steel strands, and when the PC steel strands reach the rust preventive coating device based on this measurement signal, the device is activated to prevent rust only in the necessary areas. A method for producing a sheathed PC steel stranded wire for use in an unbonded method, characterized in that a prestressing agent is applied.