Hammering type rotatable drill bit for down-the-hole drill

Abstract

The utility model provides a hammering type rotatable drill bit for a down-the-hole drill. The hammering type rotatable drill bit comprises a drill bit shaft; a vent hole running axially along the center of the drill bit shaft; the horizontal gas channel guide pipe is connected with the exhaust hole; and a plurality of gas slot channels. Each gas passage conduit is embedded in the drill bit front drilling surface and extends from the level of the vent hole to the peripheral edge of the drill bit. Each gas slot channel extends outwardly from a radial location around a protruding drilling portion of the bit front middle region to a peripheral edge of the bit across a bit front drilling surface aft in a stepped shape. A portion of each gas channel conduit merges with the gas slot channel thereabove from a periphery of the intermediate protruding drilling portion to a portion of the peripheral edge of the drill bit to form a merged gas channel conduit-gas slot channel. The design can guide flushing air to horizontally and stably pass through the front drilling surface of the drill bit without any interference on the drilling ground, and does not weaken the drill bit structure at the same time.

Description

Technical Field

[0001] The utility model generally relates to civil engineering, and more particularly to a hammer-type rotatable drill bit for a down-the-hole (DTH) drilling machine. Background Art

[0002] Down-the-hole drills are widely used in civil engineering fields such as mining, tunneling, quarrying, excavation, construction, etc. A down-the-hole drill bit, such as a percussion hammer, is basically a rock hammer and / or a rotary drill bit attached to the bottom of the drill pipe. The hammering and / or rotating action of the drill bit breaks the rock and soil into small pieces, debris and dust, which are then discharged by the pressurized flushing air flow or by driving the percussion hammer through the front of the drill bit.

[0003] European Patent No. 3097248 discloses a drill bit having a central exhaust hole located at its axis for providing flushing air to the front of the drill bit. The drill bit also has a protruding drilling portion for directing the flushing air flow into a number of grooves belonging to the front surface of the drill bit, which extend from near the center to the edge of the drill bit. This flushing air flow bypassing the front of the drill bit expels debris generated during drilling.

[0004] However, the design of European Patent No. 3097248 will have very limited effect in practical application. This is because the protruding drilling part and the grooves on the front surface of the drill bit form a considerable obstruction to the flushing airflow. As a result, the flushing air blown out from the central exhaust hole will form an unstable turbulent flow on the front surface of the drill bit. This turbulent flushing airflow will in turn inevitably disturb the drilling surface under the drill bit, resulting in unstable drilling conditions, especially when drilling soft ground. In addition, this design causes the flushing air to leave through multiple horizontal openings at the bottom of the central exhaust hole. This causes the airflow velocity vector, which was originally in the vertical downward direction, to experience a sudden 90-degree change in direction, triggering a burst of turbulence at these horizontal openings. Therefore, not only does the unstable flushing airflow induce turbulence, but there is also a considerable velocity vector component in the vertical downward direction, further amplifying the disturbance of the drilling surface under the drill bit.

[0005] Finnish patent No. 20120269 discloses another drill bit design which has an exhaust hole in the center of its front drilling surface to exhaust flushing air. There are horizontal flushing guides on the front surface to guide the flushing air from the center of the front surface to the periphery of the drill bit. In this way, the flushing air is discharged directly into the front surface to discharge the debris to the periphery, which is then collected in the housing tube for transportation back to the surface. However, since the exhaust hole is located exactly in the center of the front surface and the horizontal flushing guide needs to be close to the front surface, this will weaken the structure of the drill bit. In addition, the middle area of ​​the drill bit will receive less flushing because most of the flushing air flow is directed radially to the edge of the drill bit. Summary of the invention

[0006] The utility model aims to provide a hammer-type rotatable drill bit for a down-the-hole drill to solve the above-mentioned problems of the prior art. Another object is to provide a drill bit design that can horizontally and stably guide flushing air through the front drilling surface of the drill bit without interfering with the drilling surface and without weakening the drill bit structure.

[0007] According to one embodiment of the utility model, a hammer-type rotatable drill bit for a down-the-hole drill is provided. The drill bit includes a drill bit front portion having a drilling surface; a protruding drilling portion in the middle area of ​​the drill bit front portion, wherein the rest of the drill bit front drilling surface is a stepped rearward drill bit front drilling surface; an exhaust hole running axially along the center of the drill bit shaft, having: a first end for providing flushing air, and a second end below the protruding drilling portion; a plurality of horizontal gas channel conduits connected to the exhaust hole at or near the second end of the exhaust hole, wherein each of the gas channel conduits is embedded in the drill bit front drilling surface and extends from the level of the exhaust hole to the peripheral edge of the drill bit.

[0008] The middle protruding drilling part is made of thickened material layer to strengthen the structure of the drill bit, especially the middle area is stronger. Through the middle protruding drilling part, the rest of the front drilling surface of the drill bit is arranged behind the middle protruding drilling part.

[0009] A plurality of gas groove channels are provided on the stepped rearward front drilling surface portion of the drill bit. Each gas groove channel extends outward from a radial position around the protruding drilling portion to the peripheral edge of the drill bit, spanning the stepped rearward front drilling surface portion of the drill bit. In one embodiment, the shape of each gas groove channel is such that it gradually diverges from a radial position around the middle protruding drilling portion to the peripheral edge of the drill bit. The number of gas groove channels is at least equal to the number of gas channel conduits. Each gas channel conduit has a portion embedded below the middle protruding drilling portion of the front of the drill bit, and a corresponding gas groove channel is arranged above it (or closer to the stepped rearward front drilling surface portion of the drill bit), and the portion of the gas channel conduit from the periphery of the middle protruding drilling portion to the peripheral edge of the drill bit is merged with the gas groove channel above it to form a merged gas channel conduit-gas groove channel.

[0010] The protruding drilling portion, the stepped rear-mounted front drilling surface of the drill bit, the exhaust hole, the gas channel duct, the gas groove channel and the combined gas channel duct-gas groove channel are configured to: cause most of the flushing air to have a velocity vector that propagates horizontally radially from the exhaust hole through the combined gas channel duct-gas groove channel to the outer edge of the drill bit; cause a small portion of the flushing air to be diverted to the stepped rear-mounted front drilling surface of the drill bit, with a velocity vector that propagates in a horizontal direction across the stepped rear-mounted front drilling surface of the drill bit; and avoid turbulence on the front drilling surface of the drill bit.

[0011] In one embodiment, a housing tube is provided for engagement with a drill bit. The housing tube includes a housing boot mounted about its leading edge for securing the housing tube to the drill bit near the front of the drill bit. After installation, a vertical flushing channel is formed between the inner wall of the housing boot and the peripheral edge of the drill bit, corresponding to the horizontal opening of the gas passage conduit at the peripheral edge of the drill bit. This configuration causes most of the flushing air to have a velocity vector propagating horizontally radially from the exhaust port through the combined gas passage conduit-gas slot channel to the peripheral edge of the drill bit, to be captured by the inner wall of the housing boot, and then to enter the annular area between the inner wall of the housing tube and the outer diameter of the down-the-hole drill rig along the vertical flushing channel. A small portion of the flushing air is diverted to the stepped rearward front drilling surface portion of the drill bit, and similarly, the velocity vector propagating horizontally across the stepped rearward front drilling surface portion of the drill bit. This small portion of flushing air carries the chips and debris formed in front of the drill bit to the peripheral edge of the drill bit, where they are collected in the vertical flushing channel between the inner wall of the casing shoe and the peripheral edge of the drill bit and further directed to the annular area between the inner wall of the casing tube and the outer diameter of the down-the-hole drill. In this way, the flushing air can be kept stable and avoid turbulence on the drilling surface below the drill bit.

[0012] In one embodiment, one or more vertical gas grooves are provided on the periphery of the middle protruding drilling portion. Each vertical gas groove extends from the front drilling surface of the middle protruding drilling portion to the stepped rearward drill head front drilling surface portion and is connected to one of the combined gas channel conduits and gas groove channels. On the front drilling surface of the middle protruding drilling portion, there are horizontal gas grooves extending from near the center of the front drilling surface to the peripheral edge of the middle protruding drilling portion, each horizontal gas groove being connected to one vertical gas groove.

[0013] The air flow in the combined gas channel duct and gas slot channel creates a siphon effect on the front drilling surface of the middle convex drilling portion, directing the flushing air flow through the corresponding vertical air slots and horizontal air slots, which provides another way to directly flush and remove chips and debris from the middle area of ​​the drill bit without disturbing the drilling surface.

[0014] According to another aspect of the utility model, one or more of the merged gas channel conduit-gas slot channels are configured to reach the peripheral edge of the drill bit from the exhaust hole at an upwardly inclined angle. In one embodiment, each of the merged gas channel conduit-gas slot channels is tilted upward at a different angle. In one embodiment with four merged gas channel conduits-gas slot channels, the first merged gas channel conduit-gas slot channel is tilted upward at a first angle, the second (adjacent to the right of the first) merged gas channel conduit-gas slot channel is tilted upward at a second angle, the third (adjacent to the right of the second) merged gas channel conduit-gas slot channel is tilted upward at a third angle, and the fourth (adjacent to the right of the third) merged gas channel conduit-gas slot channel is tilted upward at a fourth angle; wherein the angle gradually increases or decreases from the first angle to the fourth angle. In another embodiment, the merged gas channel conduit-gas slot channel is configured to tilt upward at two different angles so that each of the adjacent merged gas channel conduits-gas slot channels is tilted upward at a different angle.

[0015] This approach can direct the flushing air away from the drill bit with a reduced vertical downward velocity vector component, thereby further reducing the possibility of disturbing the drilling surface. In addition, the different upward inclination angles between the combined gas channel conduit-gas slot channels produce different sizes of vertical upward velocity vector components in the flushing airflows flowing from the combined gas channel conduit-gas slot channels to their respective vertical flushing channels, thereby having different vertical upward velocities in the vertical flushing channels. Once these flushing airflows with different vertical upward velocities leave their respective vertical flushing channels and meet in the annular area between the inner wall of the shell tube and the outer diameter of the down-the-hole drill, different static pressures are generated, thereby generating a guiding effect in the annular area when a pressure difference is generated between each pair of adjacent vertical flushing channels. This guiding effect formed in the annular area due to the pressure difference from the high static pressure area to the low static pressure area creates a siphon effect on the flushing airflow associated with the higher pressure flushing gas channel. This siphon effect further enhances the efficiency and effectiveness of flushing and removing cuttings and debris without disturbing the drilling surface.

[0016] In another embodiment, a similar siphon effect may also be created on the flushing gas flow associated with a higher pressure flushing gas channel by using combined gas channel conduit-gas slot channels of different sizes (widths). BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings, in which:

[0018] Figure 1 A perspective view of a down-the-hole drill according to an embodiment of the present invention is shown;

[0019] Figure 2A A cross-sectional view is shown; Figure 2B A side view is shown; Figure 2C Another side view is shown; Figure 2D A bottom view is shown with markings indicating a cross-sectional view and a side view of the drill bit;

[0020] Figure 3A A side view of an embodiment of the present invention is shown; Figure 3B A bottom view is shown with markings indicating cross-sectional views; Figure 3C A cross-sectional view of an annular drill bit with a housing tube is shown;

[0021] Figure 4A A perspective view with marks indicating a cross-sectional view according to another embodiment of the present invention is shown; Figure 4B A bottom view is shown with markings indicating cross-sectional views; Figure 4C A top view is shown; Figure 4D shows a cross-sectional view; FIG4e shows another cross-sectional view. DETAILED DESCRIPTION

[0022] The following description of a hammer-type rotatable drill bit for a down-to-hole (DTH) drill rig and the like will be described as a preferred example. For those skilled in the art, modifications including additions and / or substitutions may be made to the present invention without departing from the scope and spirit of the present invention. Some specific details may be omitted to avoid making the description of the present invention complicated and difficult to understand; however, the disclosure herein is intended to enable those skilled in the art to implement the contents taught herein without excessive experimentation.

[0023] refer to Figure 1 , Figure 2A , Figure 2B , Figure 2C and Figure 2DThe following description is made. According to one embodiment of the utility model, a hammer-type rotatable drill bit 100 for a down-the-hole drill is provided. The drill bit 100 includes a protruding drilling portion 101 located in the middle area of ​​the front of the drill bit, and the front of the drill bit extends beyond the exhaust hole 110. The exhaust hole 110 is a channel running axially along the center of the drill bit axis, having a first end for providing flushing air and a second end below the protruding drilling portion 101. The flushing air is guided through the channel from a flushing air supply source, and the flushing air can be the exhaust gas that is pressurized and discharged through the exhaust hole 110 after pushing the down-the-hole drill to a plurality of horizontal gas channel conduits 103 connected to the second end (or bottom end) of the exhaust hole 110. Each gas channel conduit 103 is embedded in the drilling surface 102 of the front of the drill bit and extends horizontally from the bottom end of the exhaust hole 110 to the peripheral edge of the drill bit 100.

[0024] The middle protruding drilling part 101 is made of a thickened material layer (i.e. hardened alloy steel) to strengthen the drill bit structure, especially to make the middle area stronger. Surrounding the middle protruding drilling part 101, the remaining part 102 of the drill bit front drilling surface is arranged behind the middle protruding drilling part 101 in a stepped manner.

[0025] A plurality of gas slot channels 104 are provided on the stepped rearward drill bit front drilling surface portion 102. Each gas slot channel 104 extends outward from a radial position around the protruding drilling portion 101 to the peripheral edge of the drill bit 100, spanning the stepped rearward drill bit front drilling surface portion 102. The number of gas slot channels 104 is at least equal to the number of gas channel conduits 103. In one embodiment, the shape of each gas slot channel 104 is such that it gradually diverges from a radial position around the middle protruding drilling portion 101 to the peripheral edge of the drill bit 100. Each gas channel conduit 103 is arranged to have a corresponding gas slot channel 104 placed above it (or closer to the stepped rearward drill bit front drilling surface portion 102), and the portion of the gas channel conduit 103 from the periphery of the middle protruding drilling portion to the peripheral edge of the drill bit is merged with the gas slot channel 104 above it to form a merged gas channel conduit-gas slot channel.

[0026] It should be noted that a portion of each gas channel conduit 103 is embedded below the middle protruding drilling portion 101 at the front of the drill bit. Therefore, when the flushing air from the flushing air supply source passes through the exhaust hole 110 in the vertical direction downward, and then passes through the gas channel conduit 103 in the horizontal direction to reach the periphery of the middle protruding drilling portion, since the configuration of the exhaust hole and the gas channel conduit 103 allows the flushing air velocity vector to smoothly transition from the vertical downward direction to the horizontal direction, the velocity vector of the flushing air around the edge of the middle protruding drilling portion is mainly in the horizontal direction, so that no turbulent flushing airflow will be generated during the drilling process to interfere with the drilling surface below the drill bit.

[0027] Please refer to Figure 3A , Figure 3B and Figure 3C The following description is made. In one embodiment, a housing tube 120 is provided around a mating drill bit 100 to form a drill bit and housing tube assembly. The housing tube 120 is coupled to a housing shoe 121 mounted around its leading edge to secure the housing tube 120 to the drill bit 100 near the front of the drill bit. After installation, a vertical flushing channel 108 is formed between the inner wall of the housing shoe 121 and the peripheral edge of the drill bit, corresponding to the horizontal opening of the gas channel conduit at the peripheral edge of the drill bit. This configuration causes most of the flushing air to have a horizontal radial propagation velocity vector from the exhaust hole through the combined gas channel conduit-gas slot channel to the peripheral edge of the drill bit, be captured by the inner wall of the housing shoe 121, and then enter the annular area 107 between the inner wall of the housing tube 120 and the outer diameter of the down-the-hole drill along the vertical flushing channel 108. A small portion of the flushing air is diverted to the stepped rearward front drilling surface portion 102 of the drill bit, and similarly, the velocity vector propagating in the horizontal direction crosses the stepped rearward front drilling surface portion 102 of the drill bit. This small portion of the flushing air carries the chips and debris formed at the front of the drill bit 100 to the peripheral edge of the drill bit 100, and then is collected in the vertical flushing channel 108 between the inner wall of the housing shoe 121 and the peripheral edge of the drill bit 100, and is further guided to the annular area 107 between the inner wall of the housing tube 120 and the outer diameter of the down-the-hole drill. In this way, the flushing air can be kept stable to avoid turbulence on the drilling surface below the drill bit 100.

[0028] In another embodiment, an annular drill bit 122 is provided near the front of the drill bit, surrounding the peripheral edge of the drill bit 100. In this case, the annular drill bit 122 is just outside the edge of the housing tube 120 and the housing shoe 121.

[0029] Reference again Figure 1 , Figure 2A , Figure 2B , Figure 2C and Figure 2DThe following description is made. In another embodiment, one or more vertical gas grooves 105 are provided on the periphery of the middle protruding drilling portion 101. Each vertical gas groove 105 extends from the front drilling surface of the middle protruding drilling portion 101 to the stepped rearward drill head front drilling surface portion 102, and is connected to one of the combined gas channel conduits 103 and gas slot channels 104.

[0030] On the front drilling surface of the middle protruding drilling portion 101 , there are horizontal air grooves 106 extending from near the center of the front drilling surface to the peripheral edge of the middle protruding drilling portion 101 , and each horizontal air groove 106 is connected to a vertical air groove 105 .

[0031] The air flow in the combined gas channel conduit 103 and gas slot channel 104 creates a siphon effect on the front drilling surface of the middle protruding drilling portion, directing the flushing air flow through the vertical air slots 105 and the horizontal air slots 106, which provides another way to directly flush and remove chips and debris from the middle area of ​​the drill bit without disturbing the drilling surface.

[0032] Please refer to Figure 4A , Figure 4B , Figure 4C and Figure 4D The following description is made. According to another aspect of the utility model, one or more of the merged gas channel conduit-gas slot channels 104a are configured to reach the peripheral edge of the drill bit from the exhaust hole at an upwardly inclined angle. In one embodiment, each of the merged gas channel conduit-gas slot channels 104a is tilted upward at a different angle. In an embodiment with four merged gas channel conduits-gas slot channels, the first merged gas channel conduit-gas slot channel is tilted upward at a first angle, the second (adjacent to the right of the first) merged gas channel conduit-gas slot channel is tilted upward at a second angle, the third (adjacent to the right of the second) merged gas channel conduit-gas slot channel is tilted upward at a third angle, and the fourth (adjacent to the right of the third) merged gas channel conduit-gas slot channel is tilted upward at a fourth angle; wherein the angle gradually increases from the first angle to the fourth angle (i.e.: the first angle < the second angle < the third angle < the fourth angle) or gradually decreases (i.e.: the first angle > the second angle > the third angle > the fourth angle).

[0033] In another embodiment, the combined gas channel conduit-gas slot channel 104a is configured to tilt upward at two different angles, so that each of each pair of adjacent combined gas channel conduit-gas slot channels 104a tilts upward at a different angle. For example, the first and third angles are the same angle, and the second and fourth angles are another angle (i.e.: (first angle = third angle) ! = (second angle = fourth angle)).

[0034] This approach can direct the flushing air away from the drill bit with a reduced vertical downward velocity vector component, thereby further reducing the possibility of disturbing the drilling surface. In addition, the different upward tilt angles between the combined gas channel conduit-gas slot channels produce different sizes of vertical upward velocity vector components in the flushing airflows flowing from the combined gas channel conduit-gas slot channels 104a to their respective vertical flushing channels 108, thereby having different vertical upward velocities in the vertical flushing channels 108. Once these flushing airflows with different vertical upward velocities leave their respective vertical flushing channels 108 and meet in the annular area 107 between the inner wall of the shell tube 120 and the outer diameter of the down-the-hole drill, different static pressures are generated, thereby generating a guiding effect in the annular area 107 when a pressure difference is generated between each pair of adjacent vertical flushing channels 108. This guiding effect formed in the annular region 107 due to the pressure difference from the high static pressure area to the low static pressure area creates a siphon effect on the flushing gas flow associated with the higher pressure flushing gas channel (i.e., from the vertical flushing channel 108, the combined gas channel conduit-gas slot channel 104a to the vertical and horizontal gas slots in the middle raised drilling section). This siphon effect further enhances the efficiency and effectiveness of flushing and removing cuttings and debris without disturbing the drilling surface.

[0035] In another embodiment, a similar siphon effect may be created on the flushing gas flow associated with a higher pressure flushing gas channel by using merged gas channel conduit-gas slot channels 104a of different sizes (widths); for example, by gradually increasing or decreasing the width, or alternating the width between adjacent merged gas channel conduit-gas slot channels.

[0036] The above description of the utility model is provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. For practitioners skilled in the art, many modifications and variations will be apparent.

[0037] The selection and description of these embodiments are to best explain the principles of the utility model and its practical application, so that other ordinary technicians in the field can understand various embodiments and various modifications suitable for the specific use considered. The scope of the utility model should be defined by the following claims and their equivalents.

Claims

1. A hammer-type rotatable drill bit for a down-the-hole drill, comprising: Drill bit shaft; a front portion of the drill bit having a drilling surface; a convex drilling portion (101) in the middle region of the front of the drill bit, wherein the remainder of the front drilling surface of the drill bit is a stepped rearward front drilling surface of the drill bit (102); an exhaust hole (110) running axially along the center of the drill bit shaft, having: a first end for providing flushing air, and a second end below the protruding drilling portion (101); A plurality of horizontal gas passage conduits (103) connected to the exhaust hole (110) at or near the second end of the exhaust hole (110), wherein each of the gas passage conduits (103) is embedded in the front drilling surface of the drill bit and extends horizontally from the second end of the exhaust hole (110) to the peripheral edge of the drill bit; a plurality of gas slot channels (104), wherein each of the gas slot channels (104) extends outwardly from a radial position around the protruding drilling portion (101) to a peripheral edge of the drill bit, across the stepped rearward drill bit front drilling surface (102); Features: Each gas channel conduit (103) has a portion extending from the periphery of the central protruding drilling portion to the peripheral edge of the drill bit and merged with the gas groove channel (104) above it to form a merged gas channel conduit-gas groove channel; The arrangement of the protruding drilling portion (101), the stepped rearward drill head front drilling surface (102), the exhaust hole (110), the gas channel conduit (103), the gas slot channel (104) and the combined gas channel conduit-gas slot channel is configured as follows: causing a majority of the flushing air to have a horizontal radially propagating velocity vector from the exhaust hole (110) through the combined gas passage conduit-gas slot passage to the peripheral edge of the drill bit; Causing a small portion of the flushing air to be diverted to the stepped rearward front drilling surface (102) of the drill bit, with a velocity vector propagating in a horizontal direction across the stepped rearward front drilling surface (102); and Avoid turbulence on the drilling surface in front of the drill bit.

2. The hammer-type rotatable drill bit for a down-the-hole drill according to claim 1, characterized in that: Also included is a housing tube surrounding the mating drill bit, forming an assembly of the drill bit and the housing tube; wherein the housing tube (120) is coupled to a housing shoe (121) mounted around a leading edge thereof for fixing the housing tube (120) to the hammer-type rotatable drill bit; wherein the drill bit and housing tube assembly has one or more vertical flushing channels located between the inner wall of the housing shoe (121) and the peripheral edge of the drill bit; The flushing air is captured by the inner wall of the housing boot (121) and further enters the annular area (107) between the inner wall of the housing tube (120) and the outer diameter of the down-the-hole drill along the vertical flushing channel.

3. The hammer-type rotatable drill bit for a down-the-hole drill according to claim 1, characterized in that: Also included is an annular drill bit (122) surrounding the peripheral edge of the drill bit and adjacent the front of the drill bit.

4. The hammer-type rotatable drill bit for a down-the-hole drill according to claim 1, characterized in that: It also includes one or more vertical air grooves (105) arranged around the middle protruding drilling portion (101); Each of the vertical gas grooves (105) extends from the front drilling surface of the middle protruding drilling portion (101) to the stepped rearward drill head front drilling surface (102) and is connected to one of the combined gas channel conduits-gas groove channels.

5. The hammer-type rotatable drill bit for a down-the-hole drill according to claim 4, characterized in that: Also included is one or more horizontal air grooves (106) disposed on the front drilling surface of the middle protruding drilling portion (101); Each of the horizontal air grooves (106) extends from near the center of the front drilling surface to the periphery of the middle protruding drilling portion (101), and is connected to one of the vertical air grooves (105).

6. The hammer-type rotatable drill bit for a down-the-hole drill according to claim 1, characterized in that: Each gas slot channel (104) is shaped so as to gradually diverge from a radial position around the central protruding drilling portion (101) to the peripheral edge of the drill bit (100), across the stepped rearward drill bit front drilling surface (102).

7. The hammer-type rotatable drill bit for a down-the-hole drill according to claim 1, characterized in that: Each of the merged gas channel conduit-gas slot channels is configured to reach the peripheral edge of the drill bit from the exhaust hole at a different upward inclination angle than an adjacent merged gas channel conduit-gas slot channel; and wherein the upward inclination angle of the merged gas channel conduit-gas slot channel gradually increases.

8. The hammer-type rotatable drill bit for a down-the-hole drill according to claim 1, characterized in that: Each of the merged gas channel conduit-gas slot channels is configured to reach the peripheral edge of the drill bit from the exhaust hole at a different upward inclination angle than an adjacent merged gas channel conduit-gas slot channel; and wherein the upward inclination angle of the merged gas channel conduit-gas slot channel gradually decreases.

9. The hammer-type rotatable drill bit for a down-the-hole drill according to claim 1, characterized in that: Each of the merged gas channel conduit-gas slot channels is configured to reach the peripheral edge of the drill bit from the exhaust hole at a different upward inclination angle than an adjacent merged gas channel conduit-gas slot channel; and wherein the upward inclination angle of each of the merged gas channel conduit-gas slot channels is one of two angles.

10. The hammer-type rotatable drill bit for a down-the-hole drill according to claim 1, characterized in that: each merged gas passage conduit-gas slot channel being configured to have a different width than an adjacent merged gas passage conduit-gas slot channel; And wherein the width of the combined gas channel conduit-gas slot channel gradually increases or decreases.

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