JPH07300990A - Precast member and its manufacture - Google Patents

Abstract

PURPOSE:To prevent electric wires, etc., from being damaged in wiring work for electric wires, etc., by burying flexible tubes through which twist string is passed as prime line into the inside of precast member. CONSTITUTION:Reinforcements are arranged in the upper and lower parts of a framework at specified intervals vertically and horizontally. Also a metallic wiring box 3 is fixed at locations required. Then one end of flexible tubes 1 through which a prime line 2 is passed beforehand are fixed to the box 3 using a connector 4, and the other end is extended to the outside of the framework. Then the flexible tube to be connected without connecting to the box 3 is inserted into the framework, and both ends of these tubes are extended to the outside of the formwork. After that, concrete is deposited. Thus a precast member is formed which has an improved workability and has no danger of damaging the surfaces of electric wires, etc., in wiring work for electric wires, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precast member (hereinafter referred to as a PC member) used for construction of buildings, houses, bridges and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In the construction of buildings, houses, bridges, etc., so-called precast, in which PC members for pillars, beams, outer walls, and floor boards, which have been manufactured in advance in the factory for labor saving, are carried to a construction site and mounted and assembled by a crane or the like. The construction method (PC construction method) is widely adopted. Further, there is also an increasing number of so-called half-PC construction methods in which a PC member is manufactured on the ground at a construction site rather than in a factory and then attached and assembled with a crane or the like. The PC member used here is a pipe such as an electric wire, a cable or a fluid transport pipe (hereinafter referred to as an electric wire).
As a pipe for wiring, there is a pipe in which a flexible tube made of synthetic resin is embedded.

The work of passing an electric wire or the like to the flexible tube embedded in the PC member at a construction site is usually performed as follows. First, the PC member is attached and assembled as designed. Then, when the sum of the lengths of the flexible tubes connected when the PC member is assembled is as short as about 20 m or less, sufficient tensile strength for pulling an electric wire or the like into the flexible tube embedded in the PC member is provided. Push the piano wire made wire from one end to the other end. Further, when the sum of the lengths is relatively long, such as 20 m or more, the flexible tube is driven by the force of the blown arrow by the force of the compressed air sent from the compressor to the thread in which the blade corresponding to the tube diameter is tied to the tip. Feed it inside and pull it to the opposite pipe end. Then, the nominal line is tied to one end of the thread, and the nominal line is drawn into the flexible tube by pulling out the thread from the flexible tube. Then, connect the above-mentioned nominal line and electric wire. As the method, a method of connecting an electric wire or the like to the nominal wire, a method of peeling off the end of the electric wire to expose the conductor, and crimping the conductor and the nominal wire are adopted. By pulling out the nominal wire to which the electric wires and the like are connected from the flexible tube in this manner, the electric wires and the like are drawn into the flexible tube.

[0004]

By the way, since many flexible tubes having a relatively short length are buried in the PC member in many cases, the method of using compressed air among the above-mentioned method of passing the nominal wire. Is troublesome, and the method of pushing the piano wire from one end is widely adopted. However, at the construction site, there are many cases where the working environment is bad (high places, dark places, narrow places, etc.), and the method of pushing in the piano wire is dangerous. Further, since the piano wire has poor flexibility and high rigidity, pushing the piano wire in as described above may damage the inside of the flexible tube. When an electric wire or the like is passed through the thus-damaged flexible tube, there is a problem that the surface of the electric wire or the like is caught by the scratch inside the flexible tube and is damaged. The present invention has been made in view of the above points, and an object of the present invention is to provide a precast member that has good workability and that does not damage the surface of an electric wire or the like during a wire passing operation.

[0005]

The invention of claim 1 is a precast member in which a flexible tube 1 in which a twisted cord is previously passed as a calling wire 2 is embedded. A second aspect of the present invention is a method for producing a precast member in which a flexible tube 1 having a twisted cord made of a nominal wire 2 is piped and then concrete is poured and solidified.

In the present invention, as a method of passing the twisted string inside the flexible tube 1 in advance, at the same time as molding the flexible tube 1, the calling wire 2 is sent inside, or the manufactured flexible tube 1 Another example is a method of sending compressed air to the calling line 2 in which a blade-shaped, parachute-shaped, or balloon-shaped object is tied to the tip. In these cases, unlike inserting the nominal wire 2 into the flexible tube 1 having a short length in the field, the flexible tube 1 having a long length is inserted.
It is rational and there is no danger because the caller wire 2 is inserted into and is cut into a predetermined length.

In the present invention, the twisted string is a plurality of fibers twisted together. As the fiber, a twisted string made of polyester fiber, amide fiber, synthetic fiber such as cotton or natural fiber is preferably used.

The twisted string is preferably excellent in flexibility. For example, as shown in Figure 2, 10 cm from the end
It is preferable that the tip has flexibility such that the tip thereof is directed vertically downward when fixed. This is because such a flexible twisted cord does not have a risk of damaging the inside of the flexible tube 1 when passing through the nominal wire 2.

Further, the tensile strength of the twisted cord is preferably 300 N or more. More preferably, it is 500 N or more. More preferably, it is 1000 N or more. This is because if the tensile strength is equal to or more than the above value, the piano wire can be sufficiently used as the nominal wire 2 without re-passing the piano wire.

[0010]

In the present invention, since the flexible tube 1 is preliminarily provided with the nominal line 2, it is not necessary to work through the nominal line 2 at a construction site where the working environment is poor. The call wire 2 is made of a twisted cord. Therefore, since the rigidity of the nominal line 2 is reduced, there is no fear of damaging the inner surface of the flexible tube 1. Further, if the call wires 2 are previously passed as in the present invention, when the PC member is assembled, the call wires 2 passed through both the flexible tubes 1 to be connected must be connected to each other. In such a case, if the calling wire 2 is a piano wire, the inside of the flexible tube 1 may be damaged by the joint at the time of pulling in the electric wire or the like. Therefore, a protective tape or the like must be wrapped, but the present invention When the twisted string is used as described above, there is no fear of damaging the inside of the flexible tube 1, and it is not necessary to wind a protective tape or the like.

[0011]

【Example】

(Example) A PC member of this example will be described together with a manufacturing method with reference to FIG. In order to manufacture this PC member, first, reinforcing bars (not shown) are arranged vertically and horizontally at intervals of 20 cm in the upper and lower parts of the mold, and the metal wiring boxes 3 are bound to the necessary positions of the reinforcing bars. Fixed by lines. Next, the flexible tube 1 with the calling line 2 previously passed through
One end of each of the books was fixed to the wiring box 3 by using a connector 4, and the other end was passed through a pipe passage portion of the form and was taken out of the form. In addition, the flexible tube 1 which is connected to the wiring box 3 without being connected to the wiring box 3 is put in a mold and both ends thereof are passed through the pipe passage portions of the mold to be taken out of the mold.

Then, the concrete is filled in the form,
Vibration was applied by a vibrator so that the concrete was uniformly filled. Then, the concrete surface was finished smooth using a trowel. At this time, the openings of the connector 4, the wiring box 3 and the like were sealed with a film so that concrete toro would not enter. Then, the mold in which this concrete was poured was put into a curing tank and cured at 50 ° C. for 5 hours to solidify the concrete, and then it was removed from the mold to obtain a PC member as shown in FIG.

The flexible tube 1 used here is J
It is a synthetic resin flexible electric wire tube having an inner diameter of 16 mm according to IS C 8411, and the nominal wire 2 is a twisted string having a tensile strength of 400 N, which is formed by twisting a plurality of polyester fibers.
The method of passing the call wire 2 to the flexible tube 1 is as follows. When the flexible tube 1 was manufactured, it was fed into the flexible tube 1 at the same time and passed through. Then, only the flexible tube 1 is cut to a required length without cutting the inner nominal wire 2. Then, the nominal wires 2 having an extra length were fixed to the ends of the respective flexible tubes 1 with tapes 5 so as not to return to the inside, and then the nominal wires 2 were cut.

The PC member thus obtained was transported to a construction site and mounted and assembled by a crane. At this time, the calling wires 2 inside the flexible tube 1 at the positions to be connected to each other must be connected, but since the twisted cord is used as the calling wire 2 in this embodiment product, only tie them to each other. I was able to connect easily. This was easier than connecting piano wires together. Thereafter, the conductor sectional area is tied directly to the called line 2 to 22 mm ² of 600V vinyl insulated wires (IV), was carried out the wire pull operations. In the product of this example, the tensile strength of the nominal wire 2 made of the twisted cord is 4
Since it was 00N, the pulling work could be completed in a short time without breaking the calling line 2 during the pulling work.
Further, when the electric wire passed through the flexible tube 1 was pulled out and the surface was observed, there was no scratch.

(Comparative Example) A PC member similar to that of the example was obtained except that a piano wire was used as the nominal wire 2. This PC member was assembled in the same manner as in the example. At this time, it was impossible to connect the call wires 2 made of piano wires inside the both flexible tubes 1 connected to each other in the same manner as in the embodiment. Therefore, the piano wires were crimped together. For this reason, the work is more time-consuming than that of the example, and the joint between the piano wires is in a state where the flexibility is lost. In addition, the connection area has grown considerably. After that, the wire was pulled in in the same manner as in the example, and then the wire was pulled out and the surface was observed. As a result, the surface of the wire was scratched.

(Reference Example) A PC member similar to that of the example was obtained, except that a twisted string having a tensile strength of 200 N made by twisting cotton together was used as the nominal wire 2. This PC member was transported to the construction site and mounted and assembled with a crane. Similar to the embodiment after this example, the conductor sectional area is working pull wires tied directly to the called line 2 to 22 mm ² of 600V vinyl insulated wires (IV). In this reference example product, since the tensile strength of the twisted cord used as the nominal wire 2 was only 200 N, the nominal wire 2 was broken during the drawing operation. When a wire having a low tensile strength is used, it is necessary to pull in the high-strength nominal wire 2 before the wire drawing operation.

[0017]

As described above, the invention of claim 1 is
Since the flexible tube 1 is preliminarily provided with the call wire 2, it is not necessary to perform the work of passing the call wire 2 at a construction site where the working environment is bad. Further, the nominal wire 2 which is previously passed through the flexible tube 1 is made of a twisted cord. The call wire 2 is made of a twisted cord.
Further, if the call wires 2 are passed through in advance as in the invention of claim 1, when the PC member is assembled, the call wires 2 passed through both the flexible tubes 1 to be connected must be connected to each other. In this case, if the calling line 2 is a piano wire,
Since there is a possibility that the inside of the flexible tube 1 may be damaged by this joint during the work of pulling in electric wires, a protective tape or the like must be wrapped. However, if a twisted string is used as in the present invention, the inside of the flexible tube 1 is There is no need to wrap protective tape or the like because there is no risk of damaging the Therefore, according to the first aspect of the invention, it is possible to provide a precast member which has good workability and which does not damage the surface of the electric wire or the like during the wire passing operation of the electric wire or the like. According to the second aspect of the present invention, since the flexible tube 1 having the twisted cord's nominal wire 2 passed through is piped and then concrete is poured and solidified, the precast member of the first aspect can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a precast member.

FIG. 2 is a schematic view showing flexibility of a twisted string.

[Explanation of symbols]

 1 Flexible tube 2 Nominal line 3 Wiring box 4 Connector 5 Tape

Claims (2)

[Claims] 1. A precast member, characterized in that a flexible tube (1) having a twisted string preliminarily passed therein as a nominal wire (2) is embedded. 2. A method for producing a precast member, in which a flexible tube (1) is piped in a formwork, and then concrete is poured and solidified, in which case a twisted cord's nominal wire (2) is passed through. A method for producing a precast member, characterized in that a flexible tube (1) is piped, and then concrete is poured and solidified.