PDC drill bit used in cooperation with air screw

Abstract

The invention relates to the technical field of PDC drill bits, in particular to a PDC drill bit used in cooperation with an air screw, the PDC drill bit comprises a drill bit body and a drill bit connector, a plurality of main blades are arranged on the drill bit body in the direction from the front end to the side wall, and the main blades are distributed at intervals along the circumference of the drill bit body; a front auxiliary blade and a rear auxiliary blade are arranged on the two opposite sides of each main blade respectively, a main runner and a rear auxiliary blade runner are arranged between the front auxiliary blade and the main blade and between the rear auxiliary blade and the main blade respectively, and a front auxiliary blade runner is arranged between the front auxiliary blade and the rear auxiliary blade adjacent to the front auxiliary blade. The main flow channel, the rear auxiliary blade flow channel and the front auxiliary blade flow channel are communicated at the front end of the drill bit body to form an air outlet hole, and a replaceable nozzle is installed in the air outlet hole. The multi-flow-channel design is adopted, cooling gas flows through the two sides of the main blade, the two sides of the front auxiliary blade and the two sides of the rear auxiliary blade in the well drilling process through the design of the main flow channel, the rear auxiliary blade flow channel and the front auxiliary blade flow channel, heat is taken away, and the cooling and chip removal effects are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of PDC bits, and particularly to a PDC bit used in cooperation with an air screw. Background Art

[0002] In recent years, air drilling technology has been successively promoted and applied 793 times in deep wells and ultra-deep wells such as those in Sichuan-Chongqing, Tarim, and Songliao Basins, with a cumulative footage of 652,000 meters. It has played an important role in improving the mechanical drilling rate, discovering and protecting reservoirs, and controlling severe lost circulation. The air hammer is one of the most commonly used downhole power drills in the process of air drilling. The air drilling of the air hammer relies on two forms: high-frequency impact and rotation to break rocks. The bottom-hole rocks are broken under the combined action of drilling pressure, impact force, and rotational shear force. However, the application of the air hammer in air drilling has limitations in formation adaptability and is not applicable in humid formations and easily collapsible formations, and there is still a large room for speed increase.

[0003] Currently, in addition to the air hammer being used for air drilling, the conventional PDC bit used in cooperation with an air screw has certain advantages in terms of drilling speed compared to the air hammer. However, the conventional PDC bit still has significant deficiencies in terms of bit service life, and the PDC bit used in cooperation with an air screw requires a completely new design in terms of structure.

[0004] Currently, when used in cooperation with an air screw, the conventional PDC bit is designed the same as the PDC bit used in mud drilling. From the actual drilling performance of the conventional PDC bit used in cooperation with an air screw, the cutting teeth on the inner cone and nose of the bit are slightly worn, but the cutting teeth on the outer shoulder are severely worn. Analyzing that the high drilling speed of the air screw results in too high a linear speed of the cutting teeth on the outer shoulder. At the same time, due to the poor heat conduction efficiency of air and the poor cooling effect, the temperature of the cutting teeth is too high, resulting in thermal cracks, accelerating the wear failure of the cutting teeth, and then grinding to the bit blade body, resulting in annular grooves. The conventional PDC bit used for mud drilling is not suitable for use in cooperation with an air screw drilling, and the bit requires a new design.

[0005] Currently, there is a PDC bit for downhole air drilling with an authorized announcement number CN 111971447 B and a multiple-material composite cutting bit for air screw drilling with an authorized announcement number CN 116241186 B designed for PDC bits for air drilling. The rock-breaking mechanisms of these two designs are roughly the same as those of conventional PDC bits, and there is no obvious advantage in the flow channel design. It is expected that if they are used for air drilling, their performance will not differ much from that of conventional PDC bits. Therefore, the PDC bit used in cooperation with an air screw drilling requires a completely new design in terms of the rock-breaking mechanism of the cutting teeth and the flow channel design. Summary of the Invention

[0006] The object of the present invention is to provide a PDC bit used in conjunction with an air screw, and to solve the problem in the prior art that the PDC bit used in conjunction with air screw drilling is not optimized for the air screw, resulting in the PDC bit being prone to thermal cracks due to high temperature during actual use, thereby accelerating the wear of the bit.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A PDC bit used in conjunction with an air screw, comprising a bit body and a bit sub, provided at the rear end of the bit body. The bit body is provided with main cutting blades along the front end to the side wall direction. A plurality of main cutting blades are arranged at intervals along the circumference of the bit body. The relative two sides of each main cutting blade are respectively provided with a front auxiliary cutting blade and a rear auxiliary cutting blade. A main flow channel and a rear auxiliary cutting blade flow channel are respectively arranged between the front auxiliary cutting blade and the rear auxiliary cutting blade and the main cutting blade. A front auxiliary cutting blade flow channel is arranged between two adjacent front auxiliary cutting blades and rear auxiliary cutting blades. The sequentially adjacent main flow channel, rear auxiliary cutting blade flow channel and front auxiliary cutting blade flow channel communicate with each other at the front end of the bit body to form an air outlet hole; an installation groove is provided at the rear end of the bit body, and an air flow distribution block is fixedly installed in the installation groove. A first rotation hole is provided at the rear end of the air flow distribution block. A rotating pipe is rotatably arranged in the first rotation hole. Air guide holes corresponding to the plurality of air outlet holes one by one are arranged on the hole wall surrounding the first rotation hole. A first through hole and a plurality of second through holes are arranged on the pipe wall surrounding the rotating pipe. The aperture of the first through hole is larger than that of the second through hole. A pneumatic rotation assembly for driving the rotating pipe to rotate in the first rotation hole is installed at the rear end of the air flow distribution block.

[0009] A central fixed water eye is provided at the center of the front end of the bit body; the pneumatic rotation assembly includes a fixed block, which is fixedly connected to the cavity wall of the installation groove. A rotation cavity is provided in the fixed block. Second rotation holes communicating with the rotation cavity are arranged at the front and rear ends of the fixed block in alignment. The rear end of the rotating pipe sequentially passes through the two second rotation holes and is placed at the rear side of the fixed block, and the rotating pipe is rotatably connected to the two second rotation holes; an installation ring is sleeved on the outer wall of the rotating pipe in the rotation cavity. A plurality of fan blades are arranged at intervals on the outer wall surrounding the installation ring; air inlet holes and air outlet holes aligned with the surface of the fan blades are arranged at intervals on the cavity wall of the rotation cavity. An air inlet pipe communicating with the air inlet hole is provided at the rear end of the fixed block; a central air hole communicating with the central fixed water eye is provided at the front end of the air flow distribution block, and the air outlet hole is communicated with the central air hole.

[0010] An insertion groove is provided at the rear end of the air flow distribution block. The bottom of the insertion groove is communicated with the central air hole through a communication hole. An insertion pipe communicated with the air outlet hole is provided at the front end of the fixed block. The insertion pipe is communicated with the communication hole in the insertion groove.

[0011] A further technical solution is that both the front sub-wing and the rear sub-wing extend to the side of the drill bit body, and gauge polycrystals are convexly provided at the positions of the main wing, the front sub-wing and the rear sub-wing close to the drill bit sub.

[0012] A further technical solution is that main cutting plane teeth are distributed on the main wing, front row impact cone tip teeth are distributed on the front sub-wing, rear row limit cone tip teeth are distributed on the rear sub-wing, and a replaceable nozzle is installed in the air outlet hole.

[0013] A further technical solution is that the height of the front row impact cone tip teeth protruding from the surface of the drill bit body is the same as the height of the main cutting plane teeth protruding from the surface of the drill bit body, and the height of the rear row limit cone tip teeth protruding from the surface of the drill bit body is lower than the height of the main cutting plane teeth protruding from the surface of the drill bit body.

[0014] A further technical solution is that the height of the rear row limit cone tip teeth protruding from the surface of the drill bit body is lower than that of the main cutting plane teeth protruding from the surface of the drill bit body, and the difference is controlled between 0.4 - 2 mm.

[0015] A further technical solution is that the cross-sectional area of the main flow channel is 1.5 - 3 times that of the rear sub-wing flow channel, and the cross-sectional area of the rear sub-wing flow channel is the same as that of the front sub-wing flow channel.

[0016] A further technical solution is that the width of the main flow channel is 12.7 mm and the depth is 20 mm, the width of the rear sub-wing flow channel is 8 mm and the depth is 8 mm.

[0017] A further technical solution is that a central fixed water eye is provided at the center of the front end of the drill bit body, and central impact spherical teeth are provided around the central fixed water eye at the front end of the drill bit body; the air outlet hole is communicated with the central fixed water eye inside the drill bit body.

[0018] A further technical solution is that the diameter of the central fixed water eye is 12.7 mm, and the injection angle of the replaceable nozzle and the axis angle of the drill bit body is 25°.

[0019] A further technical solution is that 6 main wings are distributed at intervals along the circumference of the drill bit body.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention adopts a multi-channel design. Through the design of the main channel, the rear auxiliary blade channel, and the front auxiliary blade channel, cooling air flows through both sides of the main blade, the front auxiliary blade, and the rear auxiliary blade during the drilling process, taking away heat, thereby improving the cooling effect and the chip removal effect. By arranging the front auxiliary blade and the rear auxiliary blade on both sides of the main blade respectively, the main blade can be assisted in drilling during the drilling process, protecting the main blade, and thus improving the overall service life of the main blade and the drill bit body. 2. Based on the cooperation of the first through hole and the second through hole on the rotating pipe, when the rotating pipe rotates, the first through hole can sequentially pass through several air guide holes. By virtue of the fact that the aperture of the first through hole is larger than that of the second through hole, the air flux entering the air guide holes through the first through hole can be more than that entering the air guide holes through the second through hole. In this way, when the air hole is communicated with the first through hole through the air guide hole, the air output of the air hole can suddenly increase, forming a pulsed air output effect, thereby forming a high-speed and high-pressure air flow for the corresponding main channel, rear auxiliary blade channel, and front auxiliary blade channel, and avoiding debris accumulation in the main channel, rear auxiliary blade channel, and front auxiliary blade channel. 3. Conventional air drill bits use the same air flow for cooling and chip removal in the channels between each blade. Although this can achieve a uniform and stable effect, it is difficult to effectively remove or quickly dredge a sudden blockage in a certain channel, which easily leads to increased wear of the drill bit. Through the differential aperture setting of the first through hole and the second through hole, the present invention can periodically perform differential air flow impacts on all channels, so that the blocked debris can be dredged due to the impact of the large air flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 FIG. is an overall schematic diagram of a PDC drill bit used in conjunction with an air screw according to the present invention.

[0022] Figure 2 FIG. is a schematic diagram of the main blade, front auxiliary blade, and rear auxiliary blade of a PDC drill bit used in conjunction with an air screw according to the present invention.

[0023] Figure 3 FIG. is a schematic diagram of the multi-channels of a PDC drill bit used in conjunction with an air screw according to the present invention.

[0024] Figure 4 FIG. is a schematic side sectional view of a PDC drill bit used in conjunction with an air screw according to the present invention.

[0025] Figure 5 FIG. is a schematic diagram of the air flow distribution block and the fixing block of a PDC drill bit used in conjunction with an air screw according to the present invention Figure 1 .

[0026] Figure 6Schematic diagram of the air flow distribution block and the fixing block of a PDC bit used in conjunction with an air screw according to the present invention Figure 2 。

[0027] Figure 7 Cross-sectional schematic diagram of the fixing block of a PDC bit used in conjunction with an air screw according to the present invention.

[0028] Figure 8 Partial cross-sectional schematic diagram of the rotating tube and the first rotating hole of a PDC bit used in conjunction with an air screw according to the present invention.

[0029] Icon: 1 - Front row impact cone tip teeth, 2 - Main cutting plane teeth, 3 - Rear row limit cone tip teeth, 4 - Core impact spherical teeth, 5 - Replaceable nozzle, 6 - Core fixed water eye, 7 - Front auxiliary blade flow channel, 8 - Main flow channel, 9 - Rear auxiliary blade flow channel, 10 - Bit body, 11 - Gauge polycrystalline, 12 - Bit sub, 13 - Front auxiliary blade, 14 - Main blade, 15 - Rear auxiliary blade, 16 - Installation groove, 17 - Air flow distribution block, 18 - First rotating hole, 19 - Rotating tube, 20 - Air guide hole, 21 - First through hole, 22 - Second through hole, 23 - Fixing block, 24 - Rotating cavity, 25 - Second rotating hole, 26 - Installation ring, 27 - Fan blade, 28 - Air inlet hole, 29 - Air exhaust hole, 30 - Air inlet pipe, 31 - Central air hole, 32 - Insertion groove, 33 - Communication hole, 34 - Insertion tube. Detailed implementation manners

[0030] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] Figures 1 to 8 The following shows an embodiment of the present invention.

[0032] Embodiment 1:

[0033] A PDC bit used in conjunction with an air screw, comprising a bit body 10 and a bit sub 12 provided at the rear end of the bit body 10. The bit body 10 is provided with main cutting blades 14 along the front end to the side wall direction. A plurality of main cutting blades 14 are arranged at intervals along the circumference of the bit body 10. Front auxiliary cutting blades 13 and rear auxiliary cutting blades 15 are respectively arranged on the opposite sides of each main cutting blade 14. A main flow channel 8 and a rear auxiliary cutting blade flow channel 9 are respectively arranged between the front auxiliary cutting blade 13 and the rear auxiliary cutting blade 15 and the main cutting blade 14. A front auxiliary cutting blade flow channel 7 is arranged between two adjacent front auxiliary cutting blades 13 and rear auxiliary cutting blades 15. The main flow channel 8, the rear auxiliary cutting blade flow channel 9 and the front auxiliary cutting blade flow channel 7 communicate with each other at the front end of the bit body 10 to form an air outlet hole, and a replaceable nozzle 5 is installed in the air outlet hole. An installation groove 16 is provided at the rear end of the bit body 10, and the notch of the installation groove 16 is located at the rear end of the bit sub 12. An air flow distribution block 17 is fixedly installed in the installation groove 16. A first rotation hole 18 is provided at the rear end of the air flow distribution block 17. A rotating pipe 19 is rotatably arranged in the first rotation hole 18. Air guide holes 20 corresponding to and communicating with a plurality of air outlet holes are arranged on the hole wall surrounding the first rotation hole 18. A first through hole 21 and a plurality of second through holes 22 are arranged on the pipe wall surrounding the rotating pipe 19. The aperture of the first through hole 21 is larger than that of the second through holes 22. An air-driven rotation assembly for driving the rotating pipe 19 to rotate in the first rotation hole 18 is installed at the rear end of the air flow distribution block 17. The notch of the installation groove 16 is located at the rear end of the bit sub 12. The present invention adopts a multi-channel design. Through the design of the main flow channel 8, the rear auxiliary cutting blade flow channel 9 and the front auxiliary cutting blade flow channel 7, cooling air flows through both sides of the main cutting blade 14, the front auxiliary cutting blade 13 and the rear auxiliary cutting blade 15 during the drilling process, taking away heat, thereby improving the cooling effect and the chip removal effect. By arranging the front auxiliary cutting blade 13 and the rear auxiliary cutting blade 15 on both sides of the main cutting blade 14 respectively, the front auxiliary cutting blade 13 and the rear auxiliary cutting blade 15 can assist the main cutting blade 14 in drilling during the drilling process, playing a protective role for the main cutting blade 14, thereby improving the overall service life of the main cutting blade 14 and the bit body 10.

[0034] A central fixed water hole 6 is provided at the center of the front end of the drill bit body 10; the pneumatic rotary assembly includes a fixed block 23, the fixed block 23 is fixedly connected to the cavity wall of the installation groove 16, a rotating cavity 24 is provided in the fixed block 23, and second rotating holes 25 communicating with the rotating cavity 24 are provided at the front and rear ends of the fixed block 23 in alignment. The rear end of the rotating pipe 19 passes through the two second rotating holes 25 in sequence and is placed at the rear side of the fixed block 23, and the rotating pipe 19 is rotatably connected to the two second rotating holes 25; an installation ring 26 is sleeved on the outer wall of the rotating pipe 19 in the rotating cavity 24, and a plurality of fan blades 27 are arranged at intervals around the outer wall of the installation ring 26; air inlet holes 28 and exhaust holes 29 are arranged at intervals on the cavity wall of the rotating cavity 24 and are aligned with the surfaces of the fan blades 27, and an air inlet pipe 30 communicating with the air inlet holes 28 is provided at the rear end of the fixed block 23; a central air hole 31 communicating with the central fixed water hole 6 is provided at the front end of the air flow distribution block 17, and the exhaust hole 29 is communicated with the central air hole 31. When the air of the air screw enters the drill bit position from the rod body, it enters the rotating pipe 19 and the air inlet pipe 30 through the installation groove 16. The diameter of the air inlet pipe 30 is smaller than the diameter of the rotating pipe 19. In this way, most of the air flow will enter the rotating pipe 19 and a small part of the air flow will enter the air inlet pipe 30. After the air enters the rotating cavity 24 through the air inlet pipe 30, it will blow towards the surface of the fan blade 27 through the air inlet hole 28, so as to drive the fan blade 27 to rotate. The fan blade 27 drives the installation ring 26 and the rotating pipe 19 to rotate together, and the air will be discharged through the exhaust hole 29 after driving the fan blade 27 to rotate, and finally passes through the central air hole 31 and the central fixed water hole 6 in sequence and is discharged to cool the front end of the drill bit body 10 and discharge chips. When the rotating pipe 19 rotates, it will make the first through hole 21 communicate with different air guide holes 20, so that a large amount of air flow is periodically discharged from all the air holes. As Figure 8 shown, the aperture of the first through hole 21 is larger than the aperture of the air guide hole 20, the aperture of the second through hole 22 gradually increases from the inside to the outside, the aperture of the outer end matches the aperture of the air guide hole 20, and the aperture of the inner end is smaller than the aperture of the outer end. In this way, the gas flux of each second through hole 22 is smaller than the gas flux of the first through hole 21, and the edge distance between the orifices of two adjacent air guide holes 20 is generally about 3-5 mm. In this way, when the rotating pipe 19 rotates, it can be avoided that too many first through holes 21 or second through holes 22 are blocked by the hole wall between two adjacent air guide holes 20. A positioning groove is recessed at the position where the air outlet hole communicates with the bottom of the installation groove 16, and at the same time, a positioning convex block is protruded from the front end of the air flow distribution block 17 to communicate with the air guide hole 20. In this way, the installation of the gas distribution block can be quickly realized, and at the same time, the air guide hole 20 and the air outlet hole can be communicated. A limit ring is threadedly matched and connected at the position where the installation groove 16 fits the rear end of the fixed block 23 to prevent the fixed block 23 and the air flow distribution block 17 from falling out of the installation groove 16.

[0035] The rear end of the air flow distribution block 17 is provided with an insertion groove 32. The bottom of the insertion groove 32 is communicated with the central air hole 31 through a communication hole 33. The front end of the fixed block 23 is provided with an insertion pipe 34 communicated with the exhaust hole 29. The insertion pipe 34 is communicated with the communication hole 33 in the insertion groove 32. By providing the insertion groove 32 and the insertion pipe 34, the exhaust hole 29 and the communication hole 33 can be accurately communicated.

[0036] Both the front sub-wing 13 and the rear sub-wing 15 extend to the side surface of the drill bit body 10. At the position close to the drill bit sub-joint 12, the main wing 14, the front sub-wing 13 and the rear sub-wing 15 are all convexly provided with gauge polycrystals 11.

[0037] Main cutting plane teeth 2 are distributed on the main wing 14, front row impact cone tip teeth 1 are distributed on the front sub-wing 13, and rear row limit cone tip teeth 3 are distributed on the rear sub-wing 15.

[0038] The height of the front row impact cone tip teeth 1 protruding from the surface of the drill bit body 10 is the same as the height of the main cutting plane teeth 2 protruding from the surface of the drill bit body 10. The height of the rear row limit cone tip teeth 3 protruding from the surface of the drill bit body 10 is lower than the height of the main cutting plane teeth 2 protruding from the surface of the drill bit body 10. The main cutting plane teeth 2 are made of PDC composite sheets, which can improve the overall aggressiveness of the drill bit body 10 and improve the ROP performance. Moreover, the front row impact cone tip teeth 1 and the rear row limit cone tip teeth 3 can protect the main cutting plane teeth 2, avoid the premature damage of the main cutting plane teeth 2, and improve the service life of the drill bit when used in conjunction with an air motor. The main cutting plane teeth 2 are used as the main rock-breaking cutting teeth. The cutting edge of the front row impact cone tip teeth 1 is the same as that of the main cutting plane teeth 2, which plays an impact and damage role on the formation and assists the main cutting plane teeth 2 in rock breaking. The cutting edge of the rear row limit cone tip teeth 3 has a certain height difference from the main cutting teeth (DOC-depth of cut can be adjusted between 0.4-2mm according to the drillability of the formation), which controls the depth of the main cutting plane teeth 2 biting into the formation and avoids the premature damage of the main cutting plane teeth 2 due to excessive instantaneous force. The front row impact cone tip teeth 1 and the rear row limit cone tip teeth 3 cooperate with the mechanism of the main cutting plane teeth 2 to form a new rock-breaking mechanism, improve the adaptability of the drill bit body 10 to the formation, better adapt to the power output of the air motor, improve the adaptability between the drill bit and the air motor, and thus improve the ROP and service life of the drill bit.

[0039] The cross-sectional area of the main runner 8 is 1.5-3 times that of the rear sub-wing runner 9. The cross-sectional area of the rear sub-wing runner 9 is the same as that of the front sub-wing runner 7. By reasonably distributing the air kinetic energy, it is ensured that the main cutting plane teeth 2, the front row impact cone tip teeth 1 and the rear row limit cone tip teeth 3 on the main wing 14, the front sub-wing 13 and the rear sub-wing 15 have the same service life, achieving an improvement in the overall life.

[0040] At the center of the front end of the drill bit body 10, a central fixed water eye 6 is provided. Around the central fixed water eye 6 at the front end of the drill bit body 10, central impact spherical teeth 4 are provided; the air outlet hole communicates with the central fixed water eye 6 inside the drill bit body 10. The air output from the central fixed water eye 6 is mainly responsible for cooling the central impact spherical teeth 4 and discharging rock debris.

[0041] Six main cutter wings 14 are arranged at intervals along the circumference of the drill bit body 10. The present invention is mainly a new drill bit design combined with the characteristics of air drilling and based on the output characteristics of the air motor. Compared with the previous designs, the present invention has made a new design in the rock-breaking mechanism of the cutting teeth and the air kinetic energy distribution (flow channel design), so that the drill bit can cooperate with the air motor to achieve better ROP and footage performance. The key points of the present invention lie in the rock-breaking tooth arrangement methods of each cutter wing, that is, one main cutter wing 14, one front auxiliary cutter wing 13 and one rear auxiliary cutter wing 15, and the flow channel design made in cooperation with the tooth arrangement of each cutter wing. The shallow flow channel design is conducive to the maximum transfer of air kinetic energy, improving the cooling and chip removal efficiency. The multi-flow channel design ensures that the front row impact cone tip teeth 1 and the rear row limit cone tip teeth 3 of the front auxiliary cutter wing 13 and the rear auxiliary cutter wing 15 can also be effectively cooled, improving the overall service life of the drill bit. These two key technical points of the present invention complement each other and are indispensable, and can maximize the ROP and footage performance of the drill bit.

[0042] Embodiment 2:

[0043] The embodiments described below in conjunction with the drawings are specifically applied to air drilling in the 215.9mm well section of the Ziyang Dongfeng block.

[0044] As Figure 1 shown, the present invention is a PDC drill bit used in cooperation with an air motor, including a drill bit body 10, six main cutter wings 14 on the drill bit body, and two auxiliary cutter wings (front auxiliary cutter wing 13 and rear auxiliary cutter wing 15) in front of and behind each main cutter wing. Main cutting plane teeth 2 are arranged on the main cutter wing 14, front row impact cone tip teeth 1 are arranged on the front auxiliary cutter wing 13, rear row limit cone tip teeth 3 are arranged on the rear auxiliary cutter wing 15, central impact spherical teeth 4 are arranged at the center of the drill bit body, heat-stable polycrystalline wear-resistant joints are arranged on the drill bit gauge, a central fixed water eye 6 is arranged at the center of the drill bit body, six replaceable nozzles 5 are arranged on the drill bit body, and the drill bit body is connected to the air motor through a drill bit sub 12;

[0045] Each front auxiliary cutter wing 13 is provided with front row impact cone tip teeth 1, and their cutting edges are the same as those of the main cutting plane teeth 2 of the corresponding main cutter wing 14;

[0046] Each rear auxiliary cutter wing is provided with rear row limit cone tip teeth 3, and their cutting edges are 1mm lower than those of the main cutting plane teeth 2 of the corresponding main cutter wing 14;

[0047] The width of the main flow channel 8 is designed to be 12.7mm, and the depth is designed to be 20mm;

[0048] The widths of the front sub - cutter blade flow channel and the rear sub - cutter blade flow channel are designed to be 8 mm, and the depths are designed to be 8 mm;

[0049] The cutter blade crown type adopts a short crown type design, and the tooth density of the 14 main cutter blades adopts a medium tooth density;

[0050] The diameter of the central fixed water eye 6 is designed to be 12.7 mm, and the replaceable nozzle 5 adopts an MZ16 nozzle (the minimum inner diameter of the through - hole is 12.7 mm);

[0051] The main cutting plane teeth 2 adopt planar composite sheets with comprehensive performance biased towards impact resistance;

[0052] Through hydrodynamic analysis, after optimization, the radial injection angle of the replaceable nozzle 5 is 25°, and the injection angle of the nozzle - cutter blade at the center is - 3°;

[0053] On the gauge protection of the drill bit, there are heat - stable polycrystalline wear - resistant nodules with a diameter of 10 mm;

[0054] Furthermore, through a professional optimization software, the forces on the cutting teeth are optimized to make the axial force and tangential force on each tooth balanced, and the overall unbalanced force of the drill bit is reduced to 0.8% (the standard value is 3%).

[0055] The inventor produced the drill bit according to the above - mentioned technical solution and used it on - site.

[0056] Although the present invention has been described herein with reference to multiple illustrative embodiments of the invention, it should be understood that those skilled in the art can design many other modifications and embodiments that will fall within the scope of the principles and spirit disclosed in this application. More specifically, within the scope of this application's disclosure, the drawings, and the claims, various variations and improvements can be made to the components and / or the layout of the subject combination layout. In addition to the variations and improvements made to the components and / or the layout, other uses will also be apparent to those skilled in the art.

Claims

1. A PDC bit used in conjunction with an air screw, comprising a bit body (10), characterized in that, The drill bit body (10) is provided with main cutting blades (14) along the direction from the front end to the side wall. A plurality of main cutting blades (14) are arranged at intervals along the circumference of the drill bit body (10). Front auxiliary cutting blades (13) and rear auxiliary cutting blades (15) are respectively arranged on the opposite sides of each main cutting blade (14). A main flow channel (8) and a rear auxiliary cutting blade flow channel (9) are respectively arranged between the front auxiliary cutting blade (13) and the rear auxiliary cutting blade (15) and the main cutting blade (14). A front auxiliary cutting blade flow channel (7) is arranged between two adjacent front auxiliary cutting blades (13) and rear auxiliary cutting blades (15). The main flow channel (8), the rear auxiliary cutting blade flow channel (9) and the front auxiliary cutting blade flow channel (7) that are adjacent in sequence communicate with each other at the front end of the drill bit body (10) to form an air outlet hole; An installation groove (16) is arranged at the rear end of the drill bit body (10). An air flow distribution block (17) is fixedly installed in the installation groove (16). A first rotation hole (18) is arranged at the rear end of the air flow distribution block (17). A rotating pipe (19) is rotatably arranged in the first rotation hole (18). Air guide holes (20) corresponding to a plurality of air outlet holes one by one are arranged on the hole wall surrounding the first rotation hole (18). A first through hole (21) and a plurality of second through holes (22) are arranged on the pipe wall surrounding the rotating pipe (19). The aperture of the first through hole (21) is larger than that of the second through hole (22). An air-driven rotation assembly for driving the rotating pipe (19) to rotate in the first rotation hole (18) is installed at the rear end of the air flow distribution block (17).

2. The PDC bit used in cooperation with an air screw according to claim 1, wherein: A central fixed water eye (6) is arranged at the center of the front end of the drill bit body (10); The air-driven rotation assembly includes a fixed block (23). The fixed block (23) is fixedly connected to the cavity wall of the installation groove (16). A rotation cavity (24) is arranged in the fixed block (23). Second rotation holes (25) communicating with the rotation cavity (24) are arranged at the front and rear ends of the fixed block (23) in alignment. The rear end of the rotating pipe (19) sequentially passes through the two second rotation holes (25) and is placed at the rear side of the fixed block (23), and the rotating pipe (19) is rotatably connected to the two second rotation holes (25); An installation ring (26) is sleeved on the outer wall of the rotating pipe (19) in the rotation cavity (24). A plurality of fan blades (27) are arranged at intervals on the outer wall surrounding the installation ring (26); Air inlet holes (28) and exhaust holes (29) aligned with the surfaces of the fan blades (27) are arranged at intervals on the cavity wall of the rotation cavity (24). An air inlet pipe (30) communicating with the air inlet holes (28) is arranged at the rear end of the fixed block (23); A central air hole (31) communicating with the central fixed water eye (6) is arranged at the front end of the air flow distribution block (17). The exhaust hole (29) is communicated with the central air hole (31).

3. The PDC bit used in cooperation with an air screw according to claim 2, characterized in that: An insertion groove (32) is provided at the rear end of the air flow distribution block (17). The bottom of the insertion groove (32) is communicated with the central air hole (31) through a communication hole (33). An insertion pipe (34) communicated with the exhaust hole (29) is provided at the front end of the fixed block (23). The insertion pipe (34) is communicated with the communication hole (33) in the insertion groove (32).

4. A PDC bit used in conjunction with an air screw, characterized in that: Both the front sub-cutting blades (13) and the rear sub-cutting blades (15) extend to the side surface of the drill bit body (10). Diameter-maintaining polycrystals (11) are convexly provided at positions of the main cutting blades (14), the front sub-cutting blades (13) and the rear sub-cutting blades (15) close to the drill bit sub (12).

5. A PDC bit used in conjunction with an air screw, characterized in that: Main cutting plane teeth (2) are distributed on the main cutting blades (14). Front row impact cone tip teeth (1) are distributed on the front sub-cutting blades (13). Rear row limiting cone tip teeth (3) are distributed on the rear sub-cutting blades (15). Heart impact spherical teeth (4) are provided around the central fixed water eye (6) at the front end of the drill bit body (10). A replaceable nozzle (5) is installed in the air outlet hole.

6. The PDC bit used in cooperation with an air screw according to claim 5, wherein: The height of the front row impact cone tip teeth (1) protruding from the surface of the drill bit body (10) is the same as the height of the main cutting plane teeth (2) protruding from the surface of the drill bit body (10). The height of the rear row limiting cone tip teeth (3) protruding from the surface of the drill bit body (10) is lower than the height of the main cutting plane teeth (2) protruding from the surface of the drill bit body (10).

7. A PDC bit used in conjunction with an air screw, characterized in that: The height that the rear row limiting cone tip teeth (3) protrude from the surface of the drill bit body (10) is lower than the height that the main cutting plane teeth (2) protrude from the surface of the drill bit body (10), and is controlled between 0.4 - 2 mm.

8. A PDC bit used in cooperation with an air screw according to claim 7, characterized in that: The cross-sectional area of the main flow channel (8) is 1.5 - 3 times that of the rear sub-cutting blade flow channel (9). The cross-sectional area of the rear sub-cutting blade flow channel (9) is the same as that of the front sub-cutting blade flow channel (7). The width of the main flow channel (8) is 12.7 mm, and the depth is 20 mm. The width of the rear sub-cutting blade flow channel (9) is 8 mm, and the depth is 8 mm.

9. A PDC bit used in cooperation with an air screw according to claim 8, characterized in that: The diameter of the central fixed water eye (6) is 12.7 mm. The spraying angle of the replaceable nozzle (5) and the axis angle of the drill bit body (10) is 25°. Six main cutting blades (14) are distributed at intervals along the circumference of the drill bit body (10).

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