JPH0379518B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention involves, for example, performing pre-poling while discharging drilling fluid using a special rod, creating an excavation hole in muddy ground, and This invention relates to an excavation bit attached to the special rod in a rotary burying method in which a prefabricated pile set in a special cap is erected and installed in a predetermined supporting ground while being sunk and rotated. In particular, in the above-mentioned rotary burying method, a hole corresponding to the outside diameter of the pile is excavated in the ground, and when the support ground is reached, a trapezoidal enlarged hole is excavated from the hole to construct an enlarged foot hardening bulb. An enlarged bit is used for this purpose, and the invention relates to a drilling bit with such an enlarged bit.

(Prior art and problems to be solved) A forward/reverse type enlarging bit, which is known as an enlarging bit conventionally used for such purposes (a bit with a fixed digging wing is attached with an enlarging wing that expands in diameter by reversing the bit) There are two types of expansion bits: one is a hydraulic expansion bit, but the former has the disadvantage that the fixed blades become an obstacle during reverse expansion drilling, resulting in a significant drop in expansion excavation performance.Also, the expansion blades become an obstruction during forward rotation, significantly reducing excavation performance. On the other hand, the latter has the disadvantage of being expensive and requiring high maintenance costs. As described above, conventional drilling bits have drawbacks, and there is a need for the development of a forward/reverse swing type enlarged drilling bit with satisfactory digging performance.

(Means for Solving the Problems) The present invention satisfies these demands and is configured so that both the excavation blades with a large expansion diameter and the excavation blades with a small expansion diameter are expanded. It has the configuration described below. That is, the present invention has a tip claw protruding perpendicularly to the bottom surface so as to bisect the bottom surface of the bit body, and two enlarged diameter extensions with different enlarged diameter lengths on one side of the bottom surface divided by the tip claw. The digging blades are integrally constructed at an angle to each other and are rotatably attached with pins so that one of the blades expands in diameter when rotating in the forward direction and the other expands in diameter when rotating in the reverse direction.
Moreover, a stopper for restricting the rotation on the tip claw side when each enlarged excavation wing is not expanded is installed on the bottom part of one of the bisected sides of each enlarged excavation wing. This excavation bit is characterized in that an enlarged excavation blade and a pair of stoppers are provided at point-symmetrical positions on the opposite side of the tip claw.

In order to configure this, for example, two enlarged excavation blades having different excavation lengths are oriented in opposite directions, so that when the diameter of each enlarged excavation blade is expanded, The two enlarged excavation blades are integrated at their ends with an angle of 90°, for example, so that the rotating directions of the blades are opposite, and then the enlarged excavation blades can be freely rotated using pins at the ends. Attach to.

With this configuration, when the digging bit is pressed downward while rotating in the opposite direction, one of the enlarged digging wings will be in a state where the direction of the wing at its tip will dig into the soil and excavate the soil. is,
The other enlarged digging wing is closed accordingly. The closed enlarged digging blade is prevented from rotating by the stopper, and the enlarged digging blade whose diameter has been expanded does not open any further.

Also, when the bit rotates in the forward direction, the direction of the enlarged excavation blade, which had expanded in diameter when it was reversed, is reversed and the resistance is reduced, and the direction of the other enlarged excavation blade becomes the digging direction. Since it bites into the soil and receives resistance from the soil, it expands in diameter, and as a result, the enlarged excavation wing, which is integrated with this enlarged excavation wing and which had expanded in diameter during the reversal, is closed. At this time as well, the closed enlarged excavation blade is prevented from rotating by the stopper, and the enlarged excavation blade whose diameter has been expanded does not open any further.

In this manner, when the rotation direction is in the direction in which one of the enlarged excavation blades closes, the other enlarged excavation blade is closed to the stopper position.

The specific opening/closing state of this enlarged excavation blade is shown in FIG. 1B and FIG. It is closed as shown in B.

Although an example of a specific example of the apparatus of the present invention has been shown, the structure shown in the present invention can also be made into a structure other than the above-mentioned example.

(Example) An example of an example of the present invention will be described below using the drawings. FIG. 1 shows the state during normal rotation excavation, and FIG. 2 shows the state during reverse rotation excavation. A tip claw 2 is provided on the bottom surface of the bit body 1 so as to protrude so as to divide the bottom surface into two. Extended excavation blade 3 during normal rotation with short arm length
a and the reversing enlarged excavation wing 3b having a long arm length are integrally constructed as shown in the figure, and the pin 3
There is also a stopper 4 on the bottom of the bit body on the side surface of the tip claw 2 so as to stop the normal rotation excavation blade 3a and reverse rotation excavation blade 3b at predetermined positions during forward rotation M and reverse rotation M'. A reverse rotation stopper 5 is provided, and another set of enlarged excavation blades and a stopper is provided at a point symmetrical position. As a result, during normal rotation M is excavated with a diameter of D, and when reverse rotation
M' is excavated with a diameter of D'. In addition, during forward rotation M
At the time of reverse rotation, the reverse rotation digging blade 3b is closed at the stopper 4 position on the side of the tip claw 2, and at the time of reverse rotation M', the normal rotation digging blade 3a is closed at the position of the stopper 5 on the side surface of the tip claw 2. Excavation efficiency by the enlarged excavation vane is not hindered.

Note that the example shown in the drawing includes drilling fluid injection hole 1a,
It is shown that a hexagonal joint portion 1b, a set pin groove 1c, and a drilling fluid discharge outlet 1d are also present.

(Effects) The effects obtained by the present invention are as follows.

(1) Since the long enlarged digging blades that create digging resistance during forward rotation are closed, digging performance during forward rotation is improved.
In addition, when the machine is reversed, the short expansion digging blades that act as digging resistance are closed, which greatly improves the expansion digging performance.

(2) The short excavation blades that operate during forward rotation are also enlarged blades, so it is possible to excavate with a diameter that is significantly larger than the tip blade.

(3) Since the two types of digging blades are provided independently in this way, after digging with the short digging blade while lowering the drilling bit, you can expand the excavation by lowering the bit while reversing the bit. This improves excavation efficiency.

(4) Despite this, it is inexpensive due to its simple structure.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1A is a front view in normal rotation, B is a bottom view, C is a side view of state A, and FIG. It is a sectional view taken along the A line. Moreover, FIG. 2A is a front view at the time of reverse rotation, and FIG. 2B is a bottom view thereof. 1... Bit body, 2... Tip claw, 3... Pin, 3a... Expanded digging blade with short diameter, 3b... Enlarged digging blade with long diameter, 4... Stopper during normal rotation, 5...
...Stopper when reversing.

Claims (1)

[Claims] 1. A tip claw protrudes perpendicularly to the bottom surface so as to bisect the bottom surface of the bit body, and two enlarged digging wings with different expanded diameter lengths are installed on one side of the bottom surface divided by the tip claw. The diameter expands when rotating in the forward direction, and the diameter expands when the other rotates in the reverse direction.They are integrally constructed at an angle to each other and are rotatably attached with pins, and each enlarged excavation blade does not expand. In some cases, a stopper for restricting the rotation on the tip claw side is installed on the bottom of one of the bisected sides of each enlarged excavation wing, and the pair of enlarged excavation wings and the pair of stoppers are An excavation bit characterized in that the bit is provided at a point-symmetrical position on the opposite side of the tip claw.