JPH0422960Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an abrasive jet nozzle used for edge-cutting objects to be cut, such as rock or concrete structures, into a predetermined shape in order to destroy them.

[Prior art] For example, as shown in Fig. 1, there is a tunnel T underground.
When forming a cavity like this, if the underground soil is made of bedrock, it is common to excavate while crushing the bedrock by blasting. By the way, when blasting work is carried out, there will be more or less cracks S in the bedrock R.
occurs. Then, the ground, or bedrock R
becomes weaker, which is harmful to structures such as House H, which are built on that surface. Therefore, if there are facilities such as houses on the ground, construction methods that weaken the bedrock must be avoided.

Considering the causes of cracks caused by blasting using Figure 1, for example, when excavating a tunnel T, multiple explosive holes B, B, etc. are drilled, and these Gunpowder is loaded into the bomb hole and detonated. Then, cracks S, S, . . . will be generated outward from these explosive holes B, B. These cracks will not propagate outward if there is a layer in the rock that prevents crack propagation. The layer that prevents the propagation of cracks is a layer whose hardness is sufficiently lower than that of rock, but it is clear both theoretically and empirically that if this layer were to be formed artificially, it would be voids. Similar inconveniences also occur when, for example, a wall of a large structure is torn down or a side shaft is installed in a tunnel.

[Technical Background] In recent years, a cutting technique using an abrasive jet has been developed in which a mixture of granular materials such as sand and a high-pressure water jet is sprayed onto the workpiece to cut the workpiece. According to this abrasive jet technique, a workpiece can be cut relatively easily. However, for example, inserting an abrasive jet nozzle to a predetermined depth (length) along the circumferential surface M of the tunnel T shown in FIG. This is substantially difficult in an abrasive nozzle where a strong reaction force is applied. Furthermore, it is difficult and impractical to open dot-like holes successively adjacent to each other along the circumferential surface M.

In general, techniques for cutting tunnels etc. using high-pressure water are disclosed in, for example, JP-A-59-38489 and JP-A-59-38489.
It is described in Publication No. 52087, Japanese Unexamined Patent Publication No. 58-32270, etc. However, these known techniques simply use high-pressure water and do not use granular materials (so-called abrasive), resulting in poor cutting efficiency.
For example, reinforcing bars cannot be cut. Additionally, abrasive jet nozzles are also known, such as the
-Described in Publication No. 42413. Furthermore, the above-mentioned Japanese Patent Publication No. 58-32270 discloses a technique for injecting jets diametrically opposite each other.

However, in the case of an abrasive jet, the particulate material cuts the flow path, so if there is a curved portion in the nozzle flow path, the curved portion will wear out and cannot withstand long-term use. Particularly in the case of abrasive jets, the reaction force due to injection is large, and when multiple nozzles are installed in a direction perpendicular to the axis of the nozzle body to offset this, the flow path inevitably bends. Wear occurs.

[Problem to be solved by the invention] Therefore, the purpose of the invention is to provide an abrasive jet nozzle that has a long life and less wear even when the nozzle is oriented substantially perpendicular to the axis of the nozzle body. is to provide.

[Means for Solving the Problems] According to the present invention, a pilot hole is bored at a predetermined position in the workpiece, and the abrasive jet is applied while moving the abrasive jet nozzle into the pilot hole. An abrasive jet nozzle is used to form a slit by ejecting fluid radially outward toward a side wall. It is equipped with a channel through which a mixture of substances and high-pressure water is pumped, and the distal end of the channel is connected to an enlarged pressure chamber formed in the main body, and the distal end of the pressure chamber is fixed to the main body. The pressure chamber is closed by a lid, and a pair of nozzles are provided on the outer periphery of the pressure chamber at almost right angles to the axis of the nozzle body. The nozzle is connected to a hose for feeding a mixture of granules, and the nozzle is provided on the outer periphery of the nozzle body at a hydrodynamically symmetrical position so as to offset the reaction force of ejecting the mixture.

[Operation] Therefore, during the work, holes are first drilled at appropriate intervals in the circumferential surface of the workpiece to be cut, into which the abrasive jet nozzles can be inserted. This hole drilling operation may be performed using a mechanical device such as an earth auger, or a fluid device such as an abrasive jet. Then, the abrasive jet nozzle according to the present invention is inserted into the hole. At this time, the mixture is sprayed while the abrasive jet nozzle is inserted so that the jetting direction of the nozzle is directed toward the circumferential surface of the workpiece to be cut. Slits are then formed on both sides of the hole toward the circumferential surface to be cut. By setting the distance between adjacent holes to be approximately twice the length of the slit to be cut by the abrasive jet, edge cutting work can be performed along the circumferential surface of the workpiece. Further, even if adjacent slits are separated, they are substantially edged, so even if blasting is performed on the inside of the edged circumferential surface, for example, the blast will not affect the outside of the circumferential surface.

Furthermore, if the object to be cut is relatively thin, such as a concrete block or the wall of a building, it can easily break due to impact force or the like.

Abrasive jet nozzles have been well known for a long time. Conventional jet nozzles have a nozzle installed in the axial direction at the tip of the main body, so they are effective as axial drilling machines, that is, boring machines. Excavation at right angles was not possible.
However, according to the present invention, the nozzle is provided so as to eject the jet outward from the main body in a substantially perpendicular direction, so that cutting in a direction perpendicular to the axis, that is, edge cutting in an arbitrary shape, is possible. Also, a mixture of granules and high-pressure water is ejected from the nozzle, but the pressure is approximately
It can reach up to 1000Kg/ ^cm2 . Therefore, the reaction force of the jet is also large, but according to the present invention, the nozzles are hydrodynamically symmetrical, for example, two nozzles are provided at an interval of 180 degrees, so
There is an advantage that these reaction forces are canceled out and the support and operating force for the nozzle can be small.

In particular, according to the present invention, a pressure chamber with an enlarged diameter is provided at the end of the mixture flow path, so that the velocity energy of the mixture flowing through the flow path is converted into pressure energy in the pressure chamber. Therefore, the injection pressure from the nozzle provided in the pressure chamber can be maintained sufficiently high, and wear of the lid body due to the velocity energy of the mixture can be reduced.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

Now, referring to FIG. 2, the abrasive jet nozzle 1 according to the present invention includes a main body 2 having a predetermined length in the axial direction, and a 180 mm diameter on the outer circumference of the tip thereof.
Two nozzles 3 provided with a degree interval,
It consists of 3.

The main body 2 has a cylindrical shape, and a flow path 4 is formed in the center thereof, through which a mixture (slurry) of high-pressure water and particulate matter such as garnet is pumped. A pressure chamber 5 with an enlarged diameter is formed at one end of the main body, and a flow path 4 is opened in this pressure chamber. One side wall of the pressure chamber 5 is comprised of a lid 6, which is attached to the end of the main body 2 by suitable means such as screws. Nozzles 3, 3 are provided on the outer periphery of the pressure chamber 5, and the jet is ejected from these nozzles in a direction substantially perpendicular to the axis of the main body. In the illustrated embodiment, two nozzles 3, 3 are provided on the outer periphery of the main body 2 at an interval of 180 degrees.
Therefore, the reaction force of the jet is canceled out.

A joint 7 is attached to one end of the main body 2, and a hose 8 is connected via this joint. Then, pressure water is sent from a high pressure source (not shown) to the main body 2 through a hose 8, and is injected from the nozzles 3, 3 together with the particulate matter.

[Operations and Effects of the Embodiment] An example of excavating a tunnel using the abrasive jet nozzle 1 configured as described above will be described. First, as shown in FIG. 3, pilot holes P, P, . . . are bored at predetermined intervals and to a predetermined depth. A conventional boring machine is applied for this drilling. Next, the abrasive jet nozzle 1 is inserted into the pilot hole P. The nozzle 1 is freely operated by a device such as a manipulator 9. As shown in FIG. That is, the directions of the nozzles 3, 3 are made to match the outline, ie, the circumferential surface M, of the tunnel T formed in the rock R, and the main body 2 is operated so as to be able to move in and out of the pilot hole. At the same time, a mixture (slurry) of granules and high-pressure water is injected outward from the nozzles 3,3. Then, the rock is cut by the jet, and a slit D is formed. Slits D
are formed on both sides of the pilot hole P as shown in FIG. 3, but the tip of the slit may coincide with the tip of the adjacent slit D, or a small gap l may remain. After the edges have been cut using the slits in this manner, blasting is applied to the center to crush the rock and excavate the tunnel T. Even with blasting, the cracks are prevented from propagating out of the tunnel by the continuous slits.

[Effects of the invention] As described above, the present invention provides the following excellent effects.

(1) It is easy to cut the workpiece with an abrasive jet, and a relatively long distance can be cut when forming a slit.

(2) The expanded pressure chamber converts the velocity energy of the mixture into pressure energy, so sufficient pressure can be applied to the nozzle and the cutting distance can be extended.

(3) Since the velocity energy decreases due to the pressure chamber,
The wear of the lid body can be reduced and the usage time of the nozzle body can be extended. Note that if the lid gets rubbed, it can be replaced.

(4) Since the reaction force of the abrasive jet is offset, the supporting force of the nozzle body is small and operation is easy.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram for explaining the conventional tunnel construction method, Figure 2 is a sectional view showing one embodiment of the abrasive jet nozzle of the present invention, and Figure 3 is a case in which the present invention is applied to the edge cutting method. It is a conceptual diagram for explaining. D...slit, P...pilot hole, R...
Rock (workpiece), T...Tunnel, 1...Abrasive jet nozzle, 2...Main body, 3, 3...
... Nozzle, 4 ... Channel, 5 ... High pressure chamber.

Claims (1)

[Scope of utility model registration request] A pilot hole is drilled at a predetermined position in the workpiece, and the abrasive jet is ejected radially outward toward the side wall while moving the abrasive jet nozzle into the pilot hole to form a slit. An abrasive jet nozzle used for , the tip side of the flow path is connected to a pressure chamber with an enlarged diameter formed in the main body, the tip side of the pressure chamber is closed with a lid fixed to the main body, and a pair of a nozzle is provided approximately at right angles to the axis of the nozzle body, the other end of said flow path being connected to a hose for conveying a mixture of high pressure water and particulate matter through a coupling provided in the body; An abrasive jet nozzle for use in an edge cutting method, characterized in that the abrasive jet nozzle is provided on the outer periphery of the nozzle body at hydrodynamically symmetrical positions so as to offset the reaction force of ejecting the mixture.