JPH032018B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spray nozzle pipe used in a concrete spraying method such as the NATM method.

[Conventional technology]

The spray nozzle pipes conventionally used in this type of construction method are simply pipes with a constant flow area. In other words, as shown in Figure 4, a straight pipe nozzle 1' made of a vinyl chloride pipe or the like is installed at the end of the hose, and concrete is sprayed with the tip of the nozzle 1' separated from the spraying surface by about 1 m. .

[Problem that the invention seeks to solve]

To force-feed concrete, a certain level of pressure is required, and considering the adhesion of the material to the spraying surface, the spraying distance must be approximately 1 m. However, since the concrete sprayed from the tip of the nozzle 1' spreads in a conical shape until it reaches the spraying surface, the longer the spraying distance, the more dust and splashes will occur. Especially when coarse aggregate is scattered,
Spraying loss also increases. This in turn leads to variations in quality and poses a safety problem for workers.
It is therefore desirable to shorten the spraying distance, but this is currently difficult due to the high pressure.

In addition, concrete generally has a coarse particle content L of aggregate, etc.
Since it is a mixture of fine particles S such as cement, etc., if the nozzle pipe is straight, the fine particles S will flow along the pipe wall of nozzle 1' due to the difference in gravity, and coarse particles will flow. The amount L is sprayed running along the center of the nozzle 1'. Therefore, the material is sprayed in a separated state, which impairs the adhesion of the material to the spraying surface and further accelerates the generation of dust and the like.

Therefore, an object of the present invention is to provide a nozzle pipe that solves the above problems.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a spray nozzle pipe provided at the tip of a concrete supply channel with a constriction part that reduces the area of the flow passage, and also provides a condensed flow from the constriction blowing. An air suction port is provided in the pipe wall of the flowing section.

It is also possible to provide a plurality of the above-mentioned throttle parts and air suction ports in series, if necessary.

Moreover, the spray nozzle pipe according to the present invention can be wet-type,
Used for both dry methods.

[Effect]

Concrete (in the present invention, this includes not only concrete but also mortar, or materials to which additives such as steel fibers are added) flowing through the nozzle pipe under pressure converges and accelerates at the constricted portion. This flow becomes a contraction flow up to a certain section and becomes a negative pressure, so air from outside the tube is taken in from the air suction port.This air intake reduces the recovery pressure on the downstream side of the contraction flow, so the pumping pressure is reduced. The spraying distance can be shortened without any adverse effects.

Furthermore, since the flow becomes turbulent on the downstream side of the contraction flow, the concrete that has been separated into coarse particles and fine particles during the pumping process is mixed all at once.

〔Example〕

Hereinafter, the present invention will be further explained in detail with reference to specific examples shown in the drawings.

First, the overall device configuration will be explained with reference to FIG. 3. The concrete material M is
The material is fed under pressure through a hose 14 under air pressure from a compressor 12, etc., and if necessary, an quick-setting agent 16 or the like is added along the way, and then sprayed from a spray nozzle pipe 18 onto the spraying surface X.

In this embodiment, the spray nozzle pipe 18 has a two-stage configuration in which throttle parts 20, 22 and air suction ports 24, 26 are arranged in series along the pipe line, as shown in FIGS. 1 and 2. The first-stage constriction section 20 is configured as an integral part by making the tip of the pipe 28 constituting the spray nozzle pipe 18 into a conical head shape, and fixing it to the downstream pipe 30 with a connecting member 32. There is. The first stage air suction port 24 is constituted by a gap created between the pipe 28 and the pipe 30 on the downstream side thereof. The intake air flows along the outer wall of the cone in the direction of contraction.

The second-stage constriction section 22 is located downstream of the section where concrete is properly mixed in the first-stage constriction section 20, and is formed as a conical crest-shaped constriction inside the pipe 30. Second stage air intake port 26
A plurality of holes are formed around the circumference of the wall of the tube 30 near the end of the constricted portion 22.

Next, the operation of this nozzle pipe 18 will be described.

Initially, the concrete M that has been pressure-fed through the hose 14 has coarse particles L such as aggregate running through the center.
The fine particles S, such as cement, are flowing along the pipe wall, but are converged by the first-stage throttle section 20 and flow as a contracted flow while accelerating. In this condensation section, the pressure is lower than atmospheric pressure and air is taken in from the first stage air suction port 24 to prevent the mixture from dispersing and reduce the recovery pressure. Furthermore, turbulent flow occurs downstream of the contraction flow, and the coarse particle fraction L and fine particle fraction S are uniformly mixed. Further mixed concrete M
is converged by the second-stage throttle section 22 on the downstream side, and flows as a contracted flow while accelerating. Here too, the pressure decreases and air is taken in from the second stage air suction port 26. Then, the concrete M is mixed more than before and is sprayed from the tip of the nozzle pipe 18 toward the spraying surface X. Restricted parts 20, 22 and air suction port 2 with two-stage configuration of blowing pressure
4 and 26, the pressure is much lower than the pumping pressure, so the spraying distance can be shortened. Therefore, the spread of the spray flow can be suppressed to a small extent, and scattering of dust and splashing of coarse particles can be prevented. Further, the two-stage constricted portions 20 and 22 uniformly mix the coarse particles L and the fine particles S of the concrete M, resulting in a high-quality spraying method.

〔effect〕

According to the present invention, the following effects are achieved.

Regardless of the concrete pumping pressure, the spraying pressure can be kept low and the amount of air used can be reduced, so the spraying distance can be shortened.

By shortening the spraying distance, the scattering of dust and the rebound of coarse aggregate can be reduced, making the spraying work easier.

Since the amount of dust is small, ventilation equipment becomes easier.

Since the concrete is mixed uniformly, the adhesion is increased, the quality of the shotcrete is improved, and the amount of quick-setting agent used can be lower than the prescribed amount.

Furthermore, since the amount of rebound and the amount of quick-setting agent used are small, economical efficiency is improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is an external view of Fig. 1, Fig. 3 is a schematic view of the entire spraying device, and Fig. 4 is a sectional view showing a conventional nozzle. It is. 18...Blow nozzle pipe, 20, 22... Throttle part, 24, 26... Air suction port.

Claims (1)

[Scope of Claims] 1. In a spray nozzle pipe provided at the tip of a concrete supply channel, a constriction part is provided in the nozzle pipe to reduce the flow area, and a pipe in a section where contracted flow flows from the constriction part. A concrete spray nozzle pipe characterized by having an air suction port in the wall. 2. The concrete spray nozzle pipe according to claim 1, characterized in that a plurality of the constriction portions and the air suction ports are provided in series.