JPH084517Y2 - Equipment for forming ducts for PC steel - Google Patents

Description

[Detailed Description of the Invention] << Industrial Application Field >> The present invention relates to an apparatus for forming a duct for PC steel used when constructing a prestressed concrete structure.

<Conventional technology> As a conventional method for constructing a prestressed concrete structure, particularly a tower-like structure, while placing concrete, a formwork for forming the outer surface of the tower-like structure is provided along the tower-like structure. Slide the pipe vertically in the wall of the tower structure together with this formwork to form a duct for inserting PC steel in the wall, and use the PC steel inserted in this duct A method of introducing stress is known (Japanese Patent Laid-Open No. 59-87111, etc.).

In such a method, conventionally, the duct forming pipe is simply slid in the wall of the tower structure. Therefore, on the inner surface of the duct after removing the pipe,
The concrete surface remains exposed, and the PC steel material inserted into this duct is in direct contact with the concrete on the inner surface of the duct.

<Problems to be solved by the invention> As described above, when the PC steel material is in direct contact with the concrete on the inner surface of the duct, the friction resistance between the PC steel material and the concrete becomes large, and sufficient prestress cannot always be obtained. .

Therefore, in the past, it was necessary to prepare a large number of jacks in order to sufficiently pull the PC steel material, or to increase the number of PC steel materials used in some cases. In addition, when the number of PC steel materials used is increased, the diameter of the duct also becomes large, and from this aspect, the construction cost and the construction period are increased, and the storage state of the PC steel materials is also deteriorated.

The present invention has been made in view of such a situation.
The frictional resistance between steel and concrete can be reduced, it is not necessary to give extra tension to PC steel considering friction, and the number of PC steels used and the duct diameter can be optimized, and the construction cost and construction period can be reduced. It is an object of the present invention to provide a device for forming a duct for PC steel, which can reduce the amount of waste and improve the storage condition of PC steel.

<Means for Solving the Problem> The present invention is a pipe for forming a duct for inserting a PC steel material in concrete that is slid into a concrete frame by being slid together with the mold forming the outer surface of a prestressed concrete structure. In the apparatus for forming a duct for PC steel having the above, the injection nozzle for injecting the antifriction material to the inner surface of the duct is provided at the tip of the pipe, and a supply device for supplying the antifriction material is connected to the injection nozzle.

<Operation> According to the present invention, it is possible to inject the anti-friction material from the injection nozzle at the tip of the pipe to the inner surface of the duct while sliding the pipe in the concrete forming the wall to form the duct. Therefore, since the anti-friction material is applied to the inner surface of the duct after the pipe is removed, the friction resistance between the PC steel material and concrete becomes small, and sufficient pre-stress can be obtained. It is not necessary to apply an extra tensile force to the machine, and the number of PC steel materials used and the duct diameter can be optimized, the construction cost can be reduced, and the storage condition of PC steel materials can be improved.

<< Embodiment >> An embodiment of the present invention will be described below with reference to the drawings.

Fig. 1 shows the whole PC steel duct forming device.
The figure shows an enlarged main part.

In the present embodiment, the mold 2 for forming the outer surface of the tower-shaped structure 1 as the prestressed concrete structure is slid in the vertical direction together with the concrete by a yoke (not shown) arranged above. There is. Along with this formwork 2, there is provided a pipe 5 which is vertically slid in the concrete forming the wall body 3 of the tower-shaped structure 1 and forms a duct 4 for inserting a PC steel material in the wall body 3.

An injection nozzle 7 for injecting the antifriction material 6 onto the inner surface of the duct 4 is provided at the tip of the lower end of the pipe 5. The injection nozzle 7 is rotatably supported on the lower end of the pipe 5 via a bracket 8, and is rotated about the axis of the pipe 5 by, for example, a reaction force at the time of ejection. Further, a supply device for supplying an antifriction material is connected to the injection nozzle 7, and as the supply device, an antifriction material supply pump (not shown) arranged above and an antifriction material supply pump are supplied. An anti-friction material supply hose 9 for feeding the anti-friction material 6 to the injection nozzle 7 through the pipe 5 is provided.

As the antifriction material, for example, an oily substance such as grease, an uncured polymer compound, or a powdered Teflon resin is applied.

And at the time of construction, while sliding the pipe 5 in the concrete forming the wall body 3 to form the duct 4,
The antifriction material 6 may be injected from the injection nozzle 7 at the lower end of the pipe 5 to the inner surface of the duct 4. As a result, the antifriction material 6 is applied to the inner surface of the duct 4 after the pipe 5 is pulled out, so that the friction resistance between the PC steel material and the concrete to be inserted thereafter becomes small, and a sufficient pre-treatment is achieved. Get stressed. Therefore, it is not necessary to give an extra tensile force to the PC steel in consideration of friction, and it becomes possible to optimize the number of PC steel materials used and the duct diameter, reduce the construction cost and construction period, and improve the storage condition of PC steel materials. .

<Effect of device> As described above, according to the present invention, when the duct of the prestressed concrete structure is formed, the anti-friction material is injected from the injection nozzle at the tip of the pipe to the inner surface of the duct.
The antifriction material can reduce the frictional resistance between the PC steel and the concrete, and it is not necessary to give the PC steel more tensile force than necessary. Effects such as reduction of construction period and improvement of storage condition of PC steel can be achieved.

[Brief description of drawings]

FIG. 1 is an overall view showing an embodiment of an apparatus for forming a PC steel duct according to the present invention, and FIG. 2 is an enlarged view showing a main part. 1 ... Prestressed concrete structure (tower structure) 2 ... Formwork, 4 ... Duct 5 ... Pipe, 7 ... Injection nozzle 9 ... Supply device (antifriction material supply hose)

Claims (1)

[Scope of utility model registration request] 1. A duct for a PC steel product having a pipe for forming a duct for inserting a PC steel product in concrete which is slid together with a form frame forming an outer surface of a prestressed concrete structure and placed in the mold. In the forming device,
An apparatus for forming a duct for PC steel, characterized in that an injection nozzle for injecting an antifriction material to the inner surface of the duct is provided at the tip of the pipe, and a supply device for supplying the antifriction material is connected to the injection nozzle.