JPS5845358Y2 - Pit drilling bit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a pit drilling bit used in the reverse circulation drilling method, the earth organ method, etc.

Figures 1 and 2 show a conventional example of a tool bit, which is one of the bits for pit excavation. 1 is an earth removal pipe that also serves as an excavation rotation axis, and at its lower end there is a main earth and sand suction port 1a, and Auxiliary earth and sand suction ports 1b each having a semicircular shape are provided at the periphery of the suction ports 1a.

2 are three blades provided radially on the earth removal pipe 1, each blade 2
are fixed to the lower part of the earth discharge pipe 1 with angular phases different from each other by 120°, and with a dihedral angle and a rake angle.

A plurality of cutting cutters 3 are fixed to the lower surface of each blade 2.

Reference numeral 4 denotes a head cutter fixed to the lower end of the earth removal pipe 1, and a cutting blade 4a is provided on the front surface of the lower part in the rotating excavation direction. A passage port 4b is formed to smoothly guide the air to the suction port 1a.

The peripheral wall end surface of the upper earth and sand suction port 1a (lower end surface of the earth discharge pipe 1) is formed into a flat surface.

Further, the auxiliary earth and sand suction port 1b is connected to the head cutter 4.
As shown in FIGS. 3 and 4, the inner surface of the suction port peripheral wall is formed into a flat surface.

The tool bit is rotated by the rotation of the earth removal pipe 1 and the blades 2.
As shown in FIGS. 5 and 6, the ground below the blades 2 is excavated by the cutting cutters 3 of each blade 2, and the ground directly below the earth removal pipe 1 is excavated by the head cutter 4.

The excavated earth and sand are sucked directly into the earth removal pipe 1 from the main suction port 1a and the auxiliary suction port 1b of the earth removal pipe 1 together with water, and some of the excavated earth and sand passes through the passage hole 4b of the head cutter 4 and is sucked into the earth earth removal pipe 1. It gets sucked inside.

In addition, in FIG. 5, B indicates the earth and sand attached to the blade 2.

By the way, in the above-mentioned tool bit, the earth and sand excavated by the head cutter 4 accumulates on the front surface of the main body of the head cutter 4, and gradually leaks into the main and auxiliary suction ports 1a and 1b.
It tends to bulge in the direction and be easily compacted.

When the consolidated earth and sand A rises up to the main and auxiliary suction ports 1a and 1b in the earth removal pipe 1 as shown in Fig. 7,
The inner surface of the peripheral wall of the auxiliary suction port 1b becomes a moving surface when the earth and sand A is sucked into the earth discharge pipe 1.

However, in the conventional tool bit, since the inner surface of the peripheral wall of the auxiliary suction port 1b is formed as a flat surface, the earth and sand A is subjected to a force F to be moved into the earth removal pipe 1 and a force F to be moved to the outside of the earth removal pipe 1. ' acts substantially horizontally, and the soil A is in a state where it does not move in either direction, that is, a state where it is stuck to the suction port, giving a large suction resistance to the suction port.

This condition increases as the width of the flat surface, that is, the wall thickness G of the earth removal pipe 1 increases.

In addition, the increase in suction resistance reduces the water pumping performance of the suction pump, and significantly reduces the excavation efficiency in which excavation and earth removal are performed continuously.

Moreover, when the amount of earth and sand A increases, not only the auxiliary suction port 1b but also the main suction port 1a are blocked, and the excavation
There is a habit of making soil removal impossible.

The purpose of the present invention is to solve the problems of the conventional technology, and when compacted green sand rises up to the main and auxiliary sand suction ports in the earth discharge pipe, it prevents the soil from sticking at the suction ports and reduces suction resistance. An object of the present invention is to provide a pit drilling bit which can be made small and can improve excavation efficiency through excavation and soil removal.

To achieve this purpose, the present invention provides a rotatable soil removal pipe having a main earth and sand suction port at the lower end and a semicircular auxiliary earth and sand suction port at the periphery of the suction port; A plurality of blades fixed radially at the bottom with a dihedral angle and a rake angle, a plurality of cutting cutters attached to each member, and a plurality of blades fixed to the lower end of the earth removal pipe, and an earth and sand passage section in the center. The pit drilling bit is equipped with a head cutter having a hole, and is characterized in that a blade portion capable of cutting earth and sand is formed on the peripheral wall of the auxiliary earth and sand suction port.

The details of the present invention will be explained below with reference to the drawings.

Fig. 8 is a front view of the three-membered bit according to the present invention, Fig. 9 is a view taken along the - arrow in Fig. 8, and Fig. 10 is a cross-sectional view of the auxiliary earth and sand suction port of the earth removal pipe in Fig. 8. ing.

In the figures, the same reference numerals as in FIGS. 1 and 2 represent the same or equivalent items.

The inner surface of the peripheral wall of the auxiliary earth and sand suction port 1'b in the earth discharge pipe 1 has two tapered surfaces T1. A blade portion consisting of T2 is formed.

However, in the three-membered bit according to the present invention, when the consolidated earth and sand A' rises up to the suction ports 1a and l'b in the earth removal pipe 1 as shown in FIG. Cut by the blade.

That is, the earth and sand A' is cut by the force E that moves the consolidated earth and sand A' in the suction direction and the force E' that moves the earth and sand A' out of the earth discharge pipe 1 in a direction crossing the suction direction.

Therefore, since the soil A' is not layered at the suction port, the suction resistance is reduced, and the efficiency of excavation and soil removal is improved.

Further, the suction port will not be blocked due to cutting of the earth and sand A'.

In the present invention, the blade portion on the inner surface of the peripheral wall of the auxiliary suction port 1'b may be formed with one tapered surface as shown in FIGS. It may be formed with a convex curved surface as shown in FIG.

Further, in the present invention, a blade similar to the above may be formed on the end surface of the peripheral wall of the main earth and sand suction port 1a.

As explained above, in the pit drilling bit according to the present invention, when consolidated earth and sand rises up to the suction port of the earth removal pipe, by cutting it, it is possible to prevent the solid state at the suction port and reduce the suction resistance. , the excavation efficiency of excavation and soil removal will be improved.

[Brief explanation of drawings]

Fig. 1 is a front view of a conventional three-member bit, Fig. 2 is a view taken along arrows II-II in Fig. 1, Fig. 3 is a front view showing the auxiliary suction port of the earth removal pipe in Fig. 1, and Fig. 4 is a front view of a conventional three-member bit. The figure is a cross-sectional view of Figure 3,
Figure 5 is a front view showing the state of excavation, Figure 6 is v■ of Figure 5.
-v ■ arrow view, Figure 7 is an enlarged view of the suction part of the earth removal pipe in Figure 5, Figure 8 is a front view of the three-membered bit according to the present invention,
Figure 9 is a view from the ■-■ arrow in Figure 8, Figure 10 is a sectional view of the auxiliary earth and sand suction port of the earth removal pipe in Figure 8, and Figure 11 is an enlarged view of the suction part of the earth removal pipe in the excavated state. , FIGS. 12 to 14 are sectional views showing other examples of the auxiliary earth and sand suction port. 1...Earth removal pipe, 1a...Main earth and sand suction port, 1'b...Auxiliary earth and sand suction port, TI, T2
...Tapered surface forming the blade part, 2...
Wing, 3... Cutting cutter, 4... Head cutter, 4b... Earth and sand passage hole.

Claims (1)

[Scope of utility model registration request] a rotatable earth discharge pipe having a main earth and sand suction port at the lower end and a semicircular auxiliary earth and sand suction port around the periphery of the suction port;
A plurality of blades fixed radially at the bottom of the earth removal pipe with a dihedral angle and a rake angle, a plurality of cutting cutters attached to each blade, and a plurality of cutting cutters fixed at the lower end of the earth removal pipe and at the center thereof. and a head cutter having an earth and sand passage hole, the bit further comprising: a blade portion capable of cutting earth and sand formed on a peripheral wall of the auxiliary earth and sand suction port.