JPS6343552B2 - - 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 into the hole 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, when the foaming agent is dropped into the air hose, that is, when it is supplied drop by drop using gravity, the foaming agent does not foam immediately inside 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 by the pressure of the air flowing through 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 in the air hose that is subject to dynamic pressure and an outlet hole that is subject to static pressure, and the blowing agent is injected into the air hose using the pressure difference between them. 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 supply amount of the blowing agent is adjusted as the air pressure fluctuates. However, there was a drawback that it was not possible to obtain proper foam. In particular, in this invention, the amount of blowing agent supplied to the air hose is adjusted by the differential pressure between the dynamic pressure and the static pressure inside the air hose, but 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 used directly as in this invention, the blowing agent is supplied intermittently, and a phenomenon occurs in which a large amount of blowing agent comes out momentarily and then the supply is stopped. Between the foam generator and the tip of the cone, dense bubbles with a small diameter are formed alternately when a large amount of blowing agent is supplied, and loose bubbles are formed when there is a small amount of blowing agent. As a result, the foam supplied to the tip of the drill became non-uniform, resulting in a decrease in the ability to remove the adhesion of rock powder.

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 results were not satisfactory.

[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 a tank with a constant pressure valve inside this air hose, it is possible to constantly obtain uniform foam using a fixed amount of air and the foaming agent. I made it possible.

[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 pressure pipe 12 whose one end is connected to the air hose 7 for supplying foam is provided above the foaming agent liquid level in the foaming agent tank 11, and a constant pressure valve 13 is installed on the pipe line of the pressure pipe 12. It is provided. On the other hand, near the inner surface of the bottom of the foaming agent tank 11, the lower end of the liquid feeding pipe 14 is opened.
The upper end thereof passes through the upper part of the tank 11 and opens into the air hose 7 for supplying foam. The opening part of the liquid sending pipe 14 in the air hose 7 for supplying foam is a ventilator 15 whose inner diameter is smaller than that of other parts.
An adjustment valve 16 whose tip end is inserted into the liquid feeding pipe 14 is provided on the outside thereof.
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 ventilate 15.

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.

In this case, in the foam generator itself, as shown in FIG. 2, compressed air from a dedicated compressor 6 is supplied into the foaming agent tank 11 through a pressurizing pipe 12 with a constant pressure valve 13 in the middle. . Therefore, since a constant pressure is always applied to the upper space of the blowing agent tank 11, the blowing agent is transferred to the liquid sending pipe 1.
4 to a section of the ventilate 15 at constant pressure. In this part of bench ury 15,
Since the flow of air in the foam supply pipe 7 is fast, the foaming agent discharged from the liquid supply pipe 14 is sprayed out in the form of mist and foams immediately.

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. Furthermore, since the amount of blowing agent supplied to the ventilate is kept constant by the action of the constant pressure pulse, uniform foam can be formed at all times using a constant amount of air and blowing agent.

Furthermore, 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, the foaming agent was sprayed into the air hose using a ventilator instead of dripping, so the foaming agent could be foamed immediately, which was different from previous inventions. The disadvantage of non-uniform foaming due to adhesion to the inner wall of the air hose is also eliminated.

Furthermore, in the illustrated embodiment, a monitoring window 17 is provided on the air hose 7, and an adjustment valve 16 is provided on the ventilate 15, so that various adjustments can be made depending on the start of work, the time of work, or the ground on which drilling work is performed. When using different types of blowing agents, there is also the advantage of being able to monitor the condition of the foam and adjust the amount of blowing agent supplied.
Further, if the digging air hose is directly used as the foam generating air hose as in the conventional invention, it is difficult to change the amount of air and the amount of foam generated. For example, when conducting drilling deep below the groundwater level, it is preferable to reduce the amount of air to generate firm, fine bubbles, but with conventional inventions, such adjustment is not possible. In the present invention, this is possible using a dedicated air hose and constant pressure valve.

Moreover, since the conventional invention utilizes differential pressure, the foaming agent is not supplied from the tank into the air hose unless the air amount and pressure within the digging air hose exceed a certain level. Therefore, when drilling is carried out at a depth below the groundwater level in a loose sand layer, the high air pressure causes sand to eject (boiling).
However, with the present invention, foam can be generated even with a small amount of air and foaming agent using an air hose and constant pressure valve dedicated to foam generation, so it is possible to generate sufficient foam while using low air pressure for digging into the loose sand layer. can be supplied without boiling.

[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 into the air hose at a constant pressure, rock powder adhering to the hole can be discharged. It has the effect of generating bubbles with excellent ability.

[Brief explanation of the drawing]

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... Constant pressure valve, 14... Liquid feeding pipe, 15... Ventilation, 16... Adjustment valve, 17... Monitoring window.

Claims (1)

[Claims] 1. An air hose for foam generation is provided in a separate system from the air hose for excavation, and this air hose is connected above the liquid level of the foaming agent tank via a pressure pipe having a constant pressure valve, and the foaming A foam generating device characterized in that one end of a liquid feeding pipe is opened into the liquid in the agent tank, and the other end of the liquid feeding pipe is opened into the foam generating air hose. 2. The foam generating device according to claim 1, wherein the opening of the liquid feeding pipe in the foam generating air hose is a ventilate. 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.