JPH0378478B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a foam generating device used in air drilling type drilling work.

[Technical Background of the Invention] Air drilling methods have been known in which air is pumped into a hole during drilling work to cool the tip of the drill bit inserted into the ground and to transport rock powder out of the hole. As an improvement to this air drilling method, a drilling method is already known in which rock powder is more smoothly discharged from the hole by sending bubbles together with air.

In this type of air drilling method that uses foam, it is necessary to feed the foam together with air to the tip of the drill, and the device for this purpose is an injection pump that sends a foaming agent into the hole and foams the foam inside the hole. Alternatively, a blowing agent is supplied into an air hose that sends compressed air into the hole, and the bubbles generated in the air hose are sent into the hole together with the air.

Of these, regarding the latter,
There are inventions described in Japanese Patent Publication No. 49-6961 and Japanese Patent Publication No. 52-31281.

[Problems with the Background Art] However, the invention described in Japanese Patent Publication No. 49-6961 supplies the blowing agent directly and dripping into the air hose that feeds compressed air to the tip of the drill bit. The diameter of the bubbles formed in the hole is non-uniform, and the bubbles supplied into the hole cannot sufficiently adsorb rock powder, resulting in the disadvantage that the rock powder cannot be effectively discharged from the hole. In other words, the reason why rock powder is discharged by bubbles is that old bubbles with rock powder attached to the surface are pushed up to the entrance of the hole by new bubbles supplied to the bottom of the hole. The ability of foam to adsorb rock powder depends on the size, viscosity, surface tension, etc. of the foam. These are influenced by the properties and concentration of the foaming agent itself, but if the same foaming agent is used, it largely depends on the suitability of foaming.

However, if the blowing agent is supplied directly into the air hose as described above, the mixing ratio of the blowing agent and air will fluctuate due to fluctuations in the air pressure of the air hose during the drilling operation, resulting in uneven shapes of the bubbles and pores. When the rock powder is supplied into the hole, the ability of each bubble to adsorb rock powder may be insufficient or too large, and the bubbles may be crushed during discharge from the hole, resulting in the inconvenience that the rock powder cannot be discharged smoothly. In addition, if the foaming agent is dropped into the air hose and supplied one drop at a time using gravity, the foaming agent will not foam immediately in the air hose because the particle size of the foaming agent is large.
Since foam accumulates on the inner wall of the air hose and then foams, the foam is gradually peeled off from the wall of the hose due to the pressure of the air flowing inside the air hose and is supplied into the hole. There was a drawback that bubbles of uniform shape could not be formed within the air hose.

On the other hand, the invention described in Japanese Patent Publication No. 52-31281 is
The blowing agent in the blowing agent tank is supplied into the air hose by utilizing fluctuations in the air pressure inside the air hose due to the drilling operation. Indeed, in this invention,
This invention is superior to the above inventions because the amount of blowing agent supplied into the air hose changes with changes in air pressure. Moreover, the method of supplying the foaming agent is not by dripping, but by providing an inlet hole where dynamic pressure is applied and an outlet hole where static pressure is applied in the air hose, and using the differential pressure between them, the foaming agent is injected into the air hose. The inconvenience caused by dripping has been resolved.

However, this invention is similar to the above-mentioned invention in that the blowing agent is directly injected into the air hose where the pressure fluctuates as a result of the drilling operation, and even if the blowing agent supply amount is adjusted as the air pressure fluctuates. However, there was a drawback that it was not possible to obtain proper foam. In particular, this invention adjusts the amount of blowing agent supplied to the air hose using the differential pressure between the dynamic pressure and the static pressure within the air hose. However, during actual drilling work, the air pressure in the air hose repeatedly fluctuates in an extremely short period of time. , When the pressure of the air hose is directly used as in this invention, the blowing agent is supplied intermittently,
A phenomenon occurs in which a large amount of foaming agent comes out for a moment, and then the supply is stopped, and there is a gap between the foam generator in the air hose and the tip of the cone, which is caused by the diameter of the foaming agent that was generated when a large amount of foaming agent was supplied. Small, dense bubbles and sparse bubbles are formed alternately when the amount of blowing agent is low, resulting in non-uniformity of the bubbles supplied to the tip, which has the disadvantage of reducing the ability to remove rock powder adhesion. Ta.

In this way, in order to generate uniform foam with excellent adhesion ability for rock powder, it is necessary to keep the supply amount of the blowing agent and air constant at all times, and the above two inventions both solve this problem. The points were not satisfied.

[Object of the Invention] The present invention was proposed to solve the problems of the prior art as described above, and its purpose is to provide a uniform foam with excellent adhesion ability for rock powder to the tip of the drill bit. The object of the present invention is to provide a foam generating device that can generate foam.

[Summary of the Invention] The foam generating device of the present invention focuses on the fact that the drawbacks of conventional foam generating devices are that the foaming agent is directly supplied into the digging air hose. By providing a separate air hose for foam generation and supplying the foaming agent at a constant pressure from the foaming agent tank into the air hose using compressed air at a constant pressure supplied from an air pump, a fixed amount of air and foaming agent can be generated. This makes it possible to obtain uniform foam at all times.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 shows an example of a foam generating device of the present invention and an air excavation device using the same.

In the figure, 1 is a boring machine for drilling, 2 is its rod, and 3 is a sampler tube attached to the tip of the rod 2. The main compressor 4 is located at the upper end of the rod 2.
A digging air hose 5 extending from the hole is connected, and compressed air is supplied to the tip of the drill bit 3 through the air hose 5. A foam supply air hose 7 extending from a foam generation compressor 6 is connected to the middle of this digging air hose 5, and a foam generation device 10 of the present invention is provided midway along this foam supply air hose 7.

The foam generating device of the present invention has, for example, a structure as shown in FIG. 2, and includes a foaming agent tank 11 supported by leg portions 11a.
This foaming agent tank 11 has a foaming agent injection port 11.
b, a water drain pot 11c, a liquid level meter 11d, and an air vent pot 11e are provided, and the air hose 7 for supplying foam is supported by a support member 11f provided above.

A pressurizing pipe 12 having one end connected to an air pump 13 is provided above the foaming agent liquid level of the foaming agent tank 11 . This air pump 13
is controlled by a constant pressure switch 14 provided above the liquid level of the foaming agent tank 11.
It is operated so that the air pressure above the liquid level is always maintained constant.

On the other hand, near the bottom inner surface of the foaming agent tank 11,
The lower end of the liquid feed pipe 15 is open, and the upper end of the liquid feed pipe 15 passes through the upper part of the tank 11 and opens into the air hose 7 for supplying foam. An adjustment valve 16 whose tip end is inserted into the liquid feed pipe 15 is provided at the opening of the foam supply air hose 7 on the air hose side of the liquid feed pipe 15 . Further, a window 17 for monitoring the state of the foam in the foam supply air hose 7 is provided on the foam discharge side of the liquid sending pipe 15 in the foam generation air hose 7.

In the foam generating device of this embodiment having such a configuration, as shown in FIG.
At the same time, the compressed air from the foam compressor 6 is sent to the foam generator 10, and the foam generated here is sent to the foam generator 10 through the air hose 5. It is supplied into the drilling air hose 5 through the drilling air hose 5, and is sent to the drilling tip together with the drilling compressed air inside, to discharge rock powder from the drilling hole.

On the other hand, in the foam generator itself, as shown in FIG. 2, constant pressure compressed air from an air pump 13 is supplied into a foaming agent tank 11 through a pressurizing pipe 12. Therefore, since a constant pressure is always applied to the upper space of the foaming agent tank 11, the foaming agent is supplied into the foam supply pipe 7 through the liquid feed pipe 15 at a constant pressure. In this case, since the air pump 13 can apply a higher pressure to the foaming agent tank 11 than the air hose 7, the foaming agent discharged from the liquid feed pipe 15 is sprayed into the air hose 7 in the form of a mist, and immediately Foam.

At this time, unlike the two inventions shown as prior art, the air hose that supplies the foaming agent is provided exclusively for foam generation, so it is less affected by pressure fluctuations like the air hose for digging. Moreover, the amount of foaming agent supplied to the air hose 7 is kept constant by the action of the air pump 13 controlled by the constant pressure switch 14, so uniform foam is always formed by a fixed amount of air and the foaming agent. be able to.

Moreover, unlike the conventional invention of Japanese Patent Publication No. 52-31281, there is no inconvenience caused by fluctuations in the amount of foaming agent supplied due to pressure fluctuations in the air hose for excavation; It is possible to always supply uniform foam to the tip of the drill. In addition, unlike the invention of Japanese Patent Publication No. 49-6961, instead of dropping the foaming agent, air with a higher pressure than the compressed air inside the air hose was sprayed into the air hose using the air pump 13, so the foaming agent immediately foamed. This eliminates the drawback of conventional inventions where the foam adheres to the inner wall of the air hose and the degree of foaming becomes uneven.

Furthermore, in the illustrated embodiment, a monitoring window 17 is provided on the air hose 7, and an adjustment valve 16 is provided at the opening of the liquid feed pipe 15, so that the air hose 7 is provided with a monitoring window 17, and an adjustment valve 16 is provided at the opening of the liquid feeding pipe 15. When using various types of blowing agents, there is also the advantage that the foam condition can be monitored and the amount of blowing agent supplied can be adjusted accordingly.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but when the pressure of the air pump is kept low and constant, a ventilate in which the inner diameter of the air hose is tapered is formed at the outlet of the liquid sending pipe, A foaming agent may be sprayed into the air hose. Furthermore, the constant pressure air pump is not limited to one driven by a compressor, but one using a compression cylinder or the like may also be used.

[Effects of the Invention] As described above, according to the foam generating device of the present invention, since an air hose exclusively for foam is provided and a foaming agent is supplied to the air hose at a constant pressure, the ability to discharge rock powder adhering to the inside of the hole is improved. It has the effect of generating excellent foam.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an overview of an air excavation method using the foam generating device of the present invention, and FIG. 2 is a sectional view showing an embodiment of the foam generating device of the present invention. 1... Bowling machine, 2... Rod, 3...
... Awl, 4 ... Main compressor, 5 ... Air hose for digging, 6 ... Compressor for foam generation, 7
... air hose for foam generation, 10 ... foam generation device,
11... Foaming agent tank, 12... Pressure pipe, 1
3...Air pump, 14...Constant pressure switch, 15
...Liquid feed pipe, 16...Adjustment valve, 17...Monitoring window.

Claims (1)

[Claims] 1. An end of a pressurizing pipe, one end of which is connected to an air pump, is connected above the liquid level of the foaming agent tank, and the air pressure above the liquid level is detected to control the air pump. An air hose for foam generation is installed in a separate system from the air hose for digging, and one end of the liquid feed pipe is opened into the liquid in the foaming agent tank, and the other end of the liquid feed pipe is connected to the foam generating air hose. A foam generating device characterized by having an opening inside an air hose. 2. The foam generating device according to claim 1, wherein the air pump supplies air pressure higher than the air pressure within the foam generating air hose to the foaming agent tank. 3. The foam generating device according to claim 1, wherein the liquid feeding pipe has a valve for adjusting the supply amount of the foaming agent.