JP2002147158A - Expansion-contraction bit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expansion-contraction bit, which can correspond to the kinds of a drill rod or the like by a simple mechanism by which the installation and maintenance of a bit are facilitated and which does not dropout, in which only a wearing section can be exchanged, which is economical and in which the defective rotation of the bit and the closing of a fluid injection path for washing are prevented. SOLUTION: The expansion-contraction bit has a bit body in which a plurality of bits are rotatably mounted axially symmetrically, a bit adapter, to which the bit body is connected rotatably by screws, and a locking member being arranged in a baggy space formed between the bit body and the bit adapter under the state, in which the member is held by the bit body and the bit adapter, and locking the bits by engaging with the bits. The expansion-contraction bit is constituted in such a manner that the fluid injection paths are secured to each of the bits and the bit body while check valves are set up into each fluid injection path, and the check valves are opened and closed at pilot pressure with fluid injection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scaled bit such as a down-the-hole hammer or a rotary percussion drill, and more particularly to a structure of a bit and a bit body.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional expansion / contraction bit (retract bit) 1 such as a down-the-hole hammer or a rotary percussion drill has a bit body 3 connected to the tip of an inner tube 6 and a bit 2 at the tip. It was inserted in a state protruding from the pipe (casing) 7, and was able to expand and contract in diameter with the clockwise and counterclockwise rotations (FIGS. 7 and 8). In this expansion / contraction bit 1, a plurality of divided bodies 2a, 2a, 2a, which are bits 2, are pivotally fitted into a plurality of circular holes 3a formed in the bit body 3 in an axially symmetric manner. As shown in FIGS. 6 and 9, lock plates 4 for locking from outside (outer diameter of the bit body 3) engage with annular grooves 2 c formed on the pivot 2 b, respectively. Is fixed to the bit body 3 with a spring pin 5. A tip 2d of a hard material is press-fitted or brazed to the tip of the bit 2. In addition, the hard material is often made of a super alloy, and the bit 2 is often made of SNCM alloy steel.

In addition, the bit 2 and the bit body 3 have
Fluid ejection paths 2e, 3b, 3c for cleaning the surface pressing the bit 2 against the bit body 3 are provided respectively.

[0004] Such a conventional technique has the following disadvantages. (1) The method of fixing the bit by mounting the locking member consisting of the lock plate and the spring pin from the outer diameter of the bit body reduces the restraining force of the locking member due to the wear of the bit body, or the locking member is damaged and falls off, causing the bit to fall off. Often they remained in the borehole. (2) There are three places where the retaining member of the bit body is attached, and the number of processing steps is large, which is uneconomical.

(3) In the conventional integrated bit body, the outer diameter of the bit mounting portion is rapidly worn, and even if the wear on the connection side to a down-the-hole hammer or the like is slight, the entire body must be replaced. Further, an expensive bit adapter including a bit mounting portion is required according to the type of the drill rod or the down-the-hole hammer, which is extremely uneconomical.

(4) Inflow of groundwater or the like containing cuttings at the time of fluid injection stoppage such as rod connection causes poor rotation of the bit and blockage of the fluid ejection path for discharging the main cuttings.
Drilling was often interrupted.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems by providing a simple mechanism that allows easy attachment and maintenance of a bit removal prevention member and does not fall off.
Compatible with drill rods and down-the-hole hammers.Equipped with a replaceable bit for wear of the bit, it is economical.It also prevents bit rotation failure and blockage of the fluid ejection path for discharging main cutting waste. It is an object of the present invention to provide an expansion / contraction bit that is prevented and that is configured to enhance excavation efficiency.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a bit body in which a plurality of bits are rotatably mounted axisymmetrically, and a bit adapter to which the bit bodies are detachably connected. A retaining member that is disposed in a bag-shaped space provided between the bit body and the bit adapter while being sandwiched between the bit body and the bit adapter, and that prevents the bit from coming off by engaging with the bit. It is characterized by having.

[0009] The bit body and the bit adapter are screw-connected.

Further, a fluid ejection path is provided in each of the bit and the bit body, and a check valve is provided in each of the fluid ejection paths, and the check valve is opened and closed by a pilot pressure accompanying the fluid ejection. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. As shown in FIG. 1, in an enlarged / reduced bit 10 according to an embodiment of the present invention, a bit body 12 for fixing a bit 11 is connected to a drill rod or a down-the-hole hammer (not shown) via a bit adapter 13. With the configuration in which the casing 30 is entrained, the tip of the enlargement / reduction bit 10 at the tip is inserted in a state protruding from the casing 30, and the diameter can be increased / reduced with clockwise / counterclockwise rotation (FIGS. 4 and 5). Has become. The enlargement / reduction bit 10 of the present invention has been described in the prior art example except for the configuration and arrangement of the check member 16 and the check valve 16 and 17 for preventing the inflow of groundwater into the fluid ejection path. The configuration is substantially the same as that of the scaling bit 1.

The expansion / contraction bit 10 includes a bit body 12
A plurality of bits 11 are formed in a plurality of circular holes
Of the plurality of divided bodies 11a, 11a, 11a
b is rotatably fitted. As shown in FIGS. 1 and 3, an annular groove 11c formed in the pivot 11b.
A locking member 14 including a lock plate 14a and a retainer 15 is engaged therein, and the locking member 14 (that is, the retainer 1) is inserted into a bag-shaped space 12b formed by connecting the bit adapter 13.
5 and the lock plate 14a) are configured to be restrained.

In FIGS. 4 and 5, the number of divided bodies 11a of the bit 11 is three. However, the number of divided bodies 11a is not limited to three as long as it is a structure that expands and contracts.

A tip 11d made of a hard material, which is a cutting edge, is brazed to the tip of the bit 11.

The bit body 12 and the bit adapter 1
3 is screw-connected, and the bit 11 and the bit body 12 can be used as common parts by changing the bit adapter 13 according to the type of drill rod or down-the-hole hammer.

The expansion / contraction bit 10 includes fluid injection paths 11e, 12c, 13a and 15a for cleaning the bit 11 in the direction of rotation and for pressing the bit against the bit body 12. The bit 11, the bit body 12, the bit adapter 13 and the retainer 15 and check valves 16 and 17 for preventing groundwater from flowing into the fluid ejection paths 11e, 12c, 13a and 15a are provided on the bit 11 and the bit body 12, respectively, for cleaning. It is configured to open and close with the fluid injection as pilot pressure.

As shown in FIGS. 1 and 2, a check valve 16 disposed in a check valve chamber 11f provided so as to be orthogonal to the fluid ejection path 11e of the bit 11 is a check valve main body. 16a, a spring 16b, and a bush 16c. The check valve body 16a includes a spring 16b.
Thus, when the fluid ejection is stopped, the fluid ejection path 11e is closed, and the inflow of groundwater or the like containing excavated waste is prevented. On the other hand, at the time of cleaning fluid ejection, the fluid ejection path 1
Pilot channel 11g provided bypassing from 1e
The fluid pressure (pilot pressure) rises, and the check valve body 16a is pushed toward the spring 16b, and the fluid ejection path 1
1e is opened, and a cleaning fluid is injected outside the bit 11.

The fluid ejection path 12c of the bit body 12
Check valve 1 disposed in a check valve chamber 12d provided therein.
Reference numeral 7 includes a check ball 17a and a stopper 17b. When the fluid injection is stopped, the check ball 1
7a is pressed against the fluid jetting path 15a by the pressure of the external groundwater, and the fluid jetting path 15a is closed, thereby preventing the inflow of groundwater containing excavated waste. On the other hand, when the cleaning fluid is ejected, the fluid pressure in the fluid ejection path 15a rises and the check ball 17a is moved to the fluid ejection path 12a.
Pushed back to the stopper 17b provided on the c side, the fluid flows into the fluid ejection path 12c from the gap between the check ball 17a and the stopper 17b (open state), and ejects the cleaning fluid to the outside of the bit body 12. .

[0019]

According to the present invention described in detail above,
The following excellent effects are provided. (1) Since the retaining member 14 is provided in the bag-shaped space 12b formed by the connection between the bit 11 and the bit adapter 12, the retaining member 14 is less likely to be worn or damaged. No drop of bit 11 occurs.

(2) A retaining member 14 for the bit body 12
Since the mounting structure is simple and there is no complicated processing from the outer diameter of the bit body 12, it is inexpensive. Also, the attachment of the retaining member 14 is easy, and a jig for mounting a conventional spring pin is unnecessary. For this reason, assembly and maintenance work of the enlargement / reduction bit 10 are easily performed.

(3) Since the bit 11 and the bit body 12 are made common parts and the bit body 12 and the bit adapter 13 are screw-connected, the bit adapter 13 can be changed according to the type of drill rod or down-the-hole hammer. This is very economical because only the worn portion can be replaced with respect to the wear of the bit 11 mounting portion.

(4) Non-return valves 16 and 17 are provided in each of the bit 11 and the bit body 12 to provide a fluid ejection path 11e,
Since the configuration is such that groundwater inflow to 12c, 13a, and 15a is prevented, poor rotation of the bit and blockage of the fluid ejection path for discharging the main cutting waste are prevented, problems in construction are improved, and excavation efficiency is increased.

[0023]

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view showing an enlarged / reduced bit according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along a line B in FIG. 1;

FIG. 3 is a sectional view taken along the line A in FIG. 1;

FIG. 4 shows a state in which a bit is enlarged on a lower bit surface of FIG. 1;

FIG. 5 shows a state in which the bit diameter is reduced on the lower bit surface of FIG. 1;

FIG. 6 is a longitudinal sectional view showing a conventional scaling bit.

FIG. 7 shows a state in which the diameter is enlarged on the bit surface on the lower surface in FIG. 6;

FIG. 8 shows a state in which the bit diameter is reduced on the lower bit surface of FIG. 6;

FIG. 9A is a sectional view taken along a line C in FIG. 6; (B) is a part D view of (a).

[Explanation of symbols]

1, 10 Enlargement / reduction bit 2, 11 bit 3, 12 bit body 4, 14a Lock plate 5 Spring pin 6 Inner tube 7, 30 Outer tube (casing) 2a, 11a Bit divided body 2b, 11b (bit) pivot 2c, 11c Groove 2d, 11d Tip (blade) 3a, 12a Circular hole 13 Bit adapter 2e, 3b, 3c, 11e, 12c, 13a, 15a
Cleaning fluid injection path 11f, 12d Check valve chamber 11g Pilot flow path 12b Bag-shaped space 14 Retaining member 15 Retainer 16, 17 Check valve 16a Check valve body 16b Spring 16c Bush 17a Check ball 17b Stopper

Claims (3)

[Claims] A bit body in which a plurality of bits are rotatably mounted axially symmetrically, a bit adapter to which the bit body is detachably connected, and a bit body sandwiched between the bit body and the bit adapter. A retractable member which is disposed in a bag-shaped space provided between the bit adapters and which prevents the bit from coming off by engaging with the bit. 2. The bit body and the bit adapter,
The expansion / contraction bit according to claim 1, wherein the expansion / contraction bit is screw-connected. 3. A fluid ejection path is provided in each of the bit and the bit body, and a check valve is provided in each of the fluid ejection paths, and the check valve is opened and closed by a pilot pressure accompanying the fluid ejection. The expansion / contraction bit according to claim 1 or 2, wherein: