JPH11303561A - Drilling bit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue the operation of an air hammer device even if an opening of the base is blocked up with slime to automatically eliminate the block state by jetting some part of exhaust of pressure air for driving the air hammer from an upper opening. SOLUTION: A drilling bit 1 mounted on the tip of a casing pipe 2 is pressed and rotated by a rod 3, and the pressure air is supplied through a ventilating path 3a to hammer a drill chip 1c of the base 1a by the vertical motion of a hammer piston 4c of the air hammer device 4, thereby drilling. The pressure air is jetted from the base opening 11 through a ventilating path 1h, and some of the air is jetted from the upper opening 11 disposed above 30 mm or more by regulating the air flow by a choke 1p of a branch path 1j, thereby smoothing discharge of slime. Thus, even if the base opening is blocked with slime, the pressure air can be jetted from the upper opening 11 to continue the operation of the air hammer device 4, so that the block state can be automatically eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill bit for drilling a ground, wherein the ground is excavated with a chip on a bottom surface while being hit and rotated by an upper device, and pressurized air is simultaneously released from the bottom surface. The present invention relates to a drill bit having a structure that ejects slime and cools the drill bit itself. It is mainly useful for a drill bit used in a drilling rig that drills using a down-the-hole hammer.

[0002]

2. Description of the Related Art Many conventional drill bits have a structure in which a ventilation path is provided in the center, a ventilation path is opened at the bottom surface, compressed air is sent from above to the ventilation path, and air is ejected from the bottom opening. The shavings (slime) generated when excavating with the chip at the bottom by the air flow injected from the bottom opening are eliminated, and the slime is discharged upward. This air flow also serves to cool the drill bit, which becomes hot due to friction. However, when the amount of the slime becomes large, the opening of the ventilation path on the bottom surface of the drill bit is closed, and the ejection of the air is often stopped. When the air passage is closed, the pressure in the air passage increases, and the upper air hammer device that uses the air passage as an exhaust passage cannot be operated, so that the excavation operation has been stopped. This situation is likely to occur when a down-the-hole hammer excavator is used on a gravelly or cobblestone ground where it is difficult for the hole to become independent.
In order to solve this, conventionally, the hammer device is manually lifted to finely adjust the hammer device to send pressurized air to the drill bit, and the above operation is repeatedly performed until the air passage is closed. This resolving work is troublesome and time-consuming and cannot be surely solved. As another method of solving this, there is a method of increasing the flow rate and pressure of the air to be sent, but there is a drawback that a large compressor is required for that.

[0003]

The problem to be solved by the present invention is to solve these problems of the prior art, and to improve the simple structure to reduce the number of air passages to be closed and to ensure the operation of the excavator. Another object of the present invention is to provide an excavation bit having a high excavation efficiency by reducing the operation of closing the closure. A second object of the present invention is to provide a drill bit that increases the upward force of the slime to the outside, is less likely to be clogged with the slime on the way, and can discharge the slime reliably.

[0004]

Means for solving the above problems are as follows: 1) A cutting tip is mounted on the bottom of a bit, a ventilation path is provided at the center, the ventilation path is opened at the bottom of the bit, and In a drill bit that receives impact and rotation and introduces air into the ventilation path, blasts air from the opening at the bottom of the bit to eliminate slime and cool the bottom of the bit while excavating the ground with the tip at the bottom of the bit. Excavation bit, characterized in that a fork is provided in the middle of the ventilation path, and the tip of the fork is opened at a higher position from the bottom. 2) The branch point of the ventilation path and the opening position of the fork are from the bottom of the bit bottom. The drill bit according to the above 1) at a position of at least 30 mm or more 3) The drill bit according to the above 1) in which the opening of the fork is opened upward at the outer periphery of the bit upper part 4) From the fork in the middle of the fork Exhaustion In the 1) to 3) drill bit according to any of providing the air flow rate adjustment means for limiting the flow rate of the air.

[0005]

According to the present invention, the pressurized air from the exhaust passage or the air blow passage of the air hammer device enters the ventilation passage of the drill bit and blows out from the opening on the bottom surface of the bit. This eliminates the slime and drains it upward. Also, the drill bit itself is cooled. Also, a part of the pressurized air flows into the branch passage from the ventilation passage and is discharged. However, since the air is discharged from the air hammer device, it does not affect the operation of the air hammer device. When the excavation bit is buried in the slime and the ventilation path near the opening on the bottom is closed, the branch point of the branch path and the tip opening position of the branch path are provided at a position higher than the bottom, so the branch point and the branch path It is less likely to be closed by slime to the tip opening, pressure air is discharged to the outside from the branch road without blowing out from the bottom opening, the air hammer device can operate normally, and the drill bit rotates while being hit In the meantime, the closing of the bottom opening is canceled by the impact vibration or the pressurized air, and the closing of the bottom opening is canceled, so that a normal drilling state can be returned. The position of the tip opening / branch point of the fork differs depending on the bit size.
It works reliably if it is more than a millimeter. If the tip opening of the fork is turned upward at the upper outer periphery, the pressurized air is discharged upward, and the slime is discharged upward or the slime is discharged from the slime discharge passage when the drill bit rod is turned sideways. Help smooth out slime.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The height of a branch point at which a branch path separates from a central ventilation path of a drill bit according to the present invention is preferably 30 mm or more. However, in a ground where sand and earth and sand tend to generate slime, the branch point is branched. The higher the point is, the better it is to be about 80 mm or more. When it is desired to increase the discharging force of the slime upward, it is preferable that the opening of the fork is made upward and the slime is opened above the side surface of the excavation bit and jetted upward. It is practical that the air flow rate adjusting means prepares chokes of various air passage inner diameters which are screwed into the openings of the branch passages, and converts the chokes according to the ground at the site. Other than the choke, a method of adjusting the flow rate according to the degree of screwing with an insertion screw of an opening screw type can also be adopted.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. The embodiment shown in FIGS. 1 to 6 is an example in which an embodiment of a drill bit in which a down-the-hole hammer is built in and a tip end opening of a branch road is provided on an upper outer periphery upward is used for a drilling apparatus. FIG. 1 is a longitudinal sectional view of the embodiment. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a sectional view taken along line BB of FIG. FIG. 4 is a cross-sectional view taken along line CC of FIG. FIG.
It is DD sectional drawing of. FIG. 6 is a bottom view of the embodiment. FIG. 7 is a partially cutaway front view showing another embodiment of the present invention. FIG. 8 is a partially cutaway front view showing another embodiment of the present invention. In the figure, 1 is a drill bit of the product of the present invention,
1a is the bottom of the drill bit, 1b is the bit shank of the drill bit, 1c is the tip attached to the bottom 1a, 1d is the eccentric reamer, 1e is the bit head, 1f is the locking pin, 1g is the rotating boss of the bit head 1e, 1h is an air passage in the drill bit 1, 1i is an opening at the bottom surface 1a of the air passage, 1j is a branch road, 1k is a branch point, 1l is an upper opening of the branch road, and 1m is a pressure receiving surface of the drill bit 1 for impact. Reference numeral 1n denotes a spline for transmitting rotation provided on the outer periphery of the upper part of the excavation bit 1, reference numeral 1o denotes a slime discharge groove, and reference numeral 1p denotes a choke which is an air flow rate adjusting means screwed into the upper opening 1e. 2 is a casing pipe, 2
a is a casing top attached to the lower end of the casing pipe 2, 3 is a rod inserted into the casing pipe 2 and has a ventilation path 3a at the center, and 4 is a down-the-hole hammer air hammer attached to the lower end of the rod 3. 4a is a valve, 4b is a body, 4c is a striking piston, 4d is an air passage provided in the striking piston, 4e is a piston stopper, and 4f is a vertical spline for rotation transmission provided in the lower part of the inner periphery of the body 4b. Therefore, it is engaged with the spline 1n of the drill bit 1. In this embodiment, a casing pipe 2, a pushing force generator for pressing the rod 3 downward, a rotating device for the rod 3, and a compressor (not shown) are installed on the ground side, and the center of the rod 3 is rotated while rotating the rod 3. Pressure air of about 7 to 24 atm is sent into the ventilation path 3a. The pressurized air from the air passage 3a of the rod 3 enters the air hammer device 4 and the valve 4a
The pressure air is sent to the piston chamber in the body 4b via the through while switching the direction, and the striking piston 4c is moved up and down. The striking piston 4c strikes the pressure receiving surface 1m on the upper surface of the drill bit 1 inserted into the body 4b. This impact is performed in a state where the lower end of the body 4b is in contact with the step of the bit shank 1b of the excavating bit 1. The rotation of the rod 3 is transmitted to the body 4b, and transmitted to the excavation bit 1 via splines 4f and 1n at the lower inner periphery of the body 4b. The pressurized air in the ventilation path 3a of the rod 3 is sent to the ventilation path 1h of the drill bit through the ventilation path 4d of the air hammer device 4, and is decompressed through the opening 1i of the bottom surface 1a to 5 to 5.
It is ejected at a pressure of about 20 atm. Some small amounts (20-3
(About 0%) of the compressed air passes through the branch passage 1j and the choke 1p
And is ejected from the upper opening 11. The ejected air is ejected toward the slime discharge path between the outer periphery of the body 4b and the inner peripheral surface of the casing pipe 2 above the excavation bit 1 and serves as a force for sending the slime upward. The excavation bit 1 cuts the ground with the tip 1c while receiving a blow and rotation from the air hammer device 4 and blowing out about 5 to 20 atmospheres of pressure air from the opening 1i on the bottom surface. Slime generated by drilling in the ground is pneumatically fed from a slime groove 1o provided on the outer circumference of the bit shank 1b, and the space between the outer circumference of the body 4b, the outer circumference of the rod 3 and the inner circumference of the casing pipe 2 is used as a slime discharge path. It is sent by air pressure to the surface. In this embodiment, when the opening 1i of the bottom surface 1a of the drill bit 1 is closed with slime, the pressurized air in the ventilation passage flows into the branch passage 1j and is ejected from the upper opening 11l toward the slime discharge passage. As a result, the air hammer device 4 is not fully operated but is operated, and the drill bit 1 is rotated while slightly hitting, and high pressure air at the time of blowing is sent to the air passage 1h, and the closed state is automatically eliminated. It is to let. If this does not solve the problem, the body 4b is lifted to enable forced blow.

Next, FIGS. 7 and 8 show another embodiment of the present invention. In the embodiment of FIG. 7, the branch road 1j is 120 m from the bottom surface 1a.
It branches off from the position of m, extends horizontally, and becomes the tip opening 1q via the choke 1p. Also in this embodiment, even if the opening 1i of the bottom surface 1a is closed by slime, mud, or the like, the pressurized air is discharged to the outside from the distal end opening 1q through the branch passage 1j which is at a high position and is less likely to be closed. As a result, the air hammer device can be operated even if the lower portion is filled with slime or the like, and the drill bit 1 continues to be operated even though insufficiently.
Will be able to operate fully. In the embodiment shown in FIG. 8, the branch path 1j is formed by extending a portion of 30 to 80 mm from the bottom surface 1a of the ventilation path 1h in a groove shape upward and to the left and right.
Also in this embodiment, pressurized air is jetted at the upper end of the groove 1r. The upper end of the groove 1r is 120 mm from the bottom 1a.
At some point, even if the opening 1i of the bottom surface 1a is closed with slime or mud, a part of the pressurized air can be released to the outside as in the embodiment shown in FIGS. Branch road 1j
By blowing out the slime and mud around by the air blown out from the front end opening, the opening 1i of the bottom surface 1a is helped to be closed. In the embodiment shown in FIGS. 1 to 8, the flow rate of the airflow discharged through the branch path can be adjusted by replacing the choke 1p with a different inner diameter of the ventilation path. In the case of a hard ground, the slime is small, so that the choke 1p is deeply squeezed so that a large amount is ejected from the opening 1i of the bottom surface 1a. On the other hand, in the case of excavation on the ground with a lot of sand and soil, a lot of slime is generated.
The air flow from the opening 11 of the branch passage 1j is increased so that the upper opening 11 is not closed. In the embodiment shown in FIGS. 1 to 7 in which the air in the branch path is ejected upward, as shown in FIGS. 1 to 7, the choke 1p is also used when changing the ratio of the amount of air discharged from the bottom surface to the amount of air ejected upward. Is preferably converted to an appropriate aperture.

[0009]

As described above, according to the present invention, the exhaust air of the high-pressure air of the air hammer device is ejected from the opening at the tip of the branch path branched from a position higher than the bottom of the ventilation path in the drill bit. In this way, even if the bottom opening is blocked by slime, mud, etc., part of the pressure air can be exhausted through the branch passage, the operation of the air hammer device is continued, and the closing of the opening is performed by rotation and impact vibration. It can be canceled automatically. The use of the drill bit of the present invention can automatically eliminate the blockage without any special operation for removing the blockage, thereby increasing the efficiency of the drilling operation, eliminating the need for a large-capacity compressor for removing the blockage, and improving the autonomy. Down-the-hole hammer method can be used for excavation of unsoiled ground. Further, if the tip opening of the branch path is directed upward at the outer periphery of the upper part of the excavation bit, the slime can be discharged smoothly by the jetting air. The above effect can be more reliably achieved if the branch point / tip opening of the branch path is made 30 mm or more from the bottom surface. If the air flow discharged from the branch can be changed by the flow control means,
An air ejection state suitable for the ground to be excavated can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view taken along the line CC of FIG. 1;

FIG. 5 is a sectional view taken along line DD of FIG. 1;

FIG. 6 is a bottom view of the embodiment.

FIG. 7 is a partially cutaway front view showing another embodiment of the present invention.

FIG. 8 is a partially cutaway front view showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drilling bit 1a Bottom surface 1b Bit shank 1c Tip 1d Eccentric reamer 1e Bit head 1f Locking pin 1g Rotating boss 1h Ventilation passage 1i Opening 1j Branch passage 1k Branch point 1l Upper opening 1m Pressure receiving surface 1n Spline 1o Slime stroke groove Groove 2 Casing pipe 2a Casing top 3 Rod 3a Ventilation path 4 Air hammer device 4a Valve 4b Body 4c Impact piston 4d Ventilation path 4e Piston stopper 4f spline

Claims (4)

[Claims] 1. A drill bit is mounted on a bottom surface of a bit, a ventilation path is provided in the center, the ventilation path is opened at the bottom surface of the bit, and a blow and rotation are applied from above and air is introduced into the ventilation path. In the excavation bit that excavates the ground with the tip of the bit bottom while blasting air from the opening of the slime and removing the slime and cooling the bit bottom, a branch path is provided from the middle of the ventilation path, and the tip of the branch path is A drill bit characterized by opening at a high position from the bottom. 2. The excavation bit according to claim 1, wherein the branch point of the ventilation path and the opening position of the branch path are at least 30 mm or more from the lower end of the bit bottom surface. 3. The excavation bit according to claim 1, wherein an opening of the branch path is opened upward at an outer periphery of an upper part of the bit. 4. An air flow rate adjusting means for limiting an air flow rate discharged from the branch path in the middle of the branch path.
3. The drilling bit according to any one of 3.