A PDC drill bit with multi-limb flow channels and self-opening and closing outlets

Abstract

The present application belongs to the technical field of oil and gas drilling, and particularly relates to a PDC drill bit with multiple branch flow channels and self-opening and closing liquid outlet, aiming to solve the problem of waste of drilling fluid when the drilling fluid is paused. The present application comprises a PDC drill bit with multiple branch flow channels and self-opening and closing liquid outlet, including a PDC drill bit and its flow channels. The PDC drill bit comprises a drill bit body and a cutter crown. The flow channels comprise a main flow channel arranged in the drill bit body and a group of branch flow channels arranged on the cutter crown. An automatic opening and closing device is arranged in the main flow channel, and the automatic opening and closing device is used to close each branch flow channel. The present application has a reasonable structure, and utilizes the centrifugal force generated by the rotation of the drill bit and a reset device to realize the automatic opening and closing of the drilling fluid of the drill bit.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas drilling technology, specifically relating to a PDC drill bit with a multi-branch flow channel that automatically opens and closes to discharge fluid. Background Technology

[0002] PDC drill bits are primarily composed of diamond composite plates and a cemented carbide matrix. This unique design allows the drill bit to achieve unprecedented levels of hardness and wear resistance. The diamond composite plates, as the cutting part of the drill bit, possess extremely high hardness and excellent wear resistance, easily handling various complex formations and significantly improving drilling efficiency. Compared to traditional tricone drill bits, PDC drill bits offer significant advantages in drilling speed, drilling efficiency, and drill bit life. For example, in some hard formations, the drilling speed of PDC drill bits can even reach more than twice that of tricone drill bits, greatly shortening the drilling cycle and reducing costs.

[0003] PDC drill bits are equipped with multiple branch channels for drilling fluid outflow, ensuring that the drilling fluid can effectively flush and clean the cutting tools and drill bit surfaces, while also cooling the PDC drill bit to extend its service life.

[0004] The PDC drill bit has a hollow internal structure. When drilling fluid is pumped into the PDC drill bit through a high-pressure pump, the fluid flows rapidly within the internal space of the drill bit. It is then guided to the bottom of the well through channels on the drill bit, providing cooling and cleaning for the drill bit, while also helping to carry drill cuttings to the surface. This circulating drilling fluid flow method ensures the high efficiency and stability of the drilling process.

[0005] However, when a PDC drill bit needs to be temporarily stopped for various reasons, drilling fluid does not need to be injected, but the flow channels inside the PDC drill bit remain open. This means that the drilling fluid remaining inside the drill bit will continue to flow out of the flow channels under the influence of gravity and pressure, resulting in a significant waste of drilling fluid. Summary of the Invention

[0006] To address the aforementioned problem in the prior art, namely the waste of drilling fluid when the drill bit is not in operation, this invention provides a PDC drill bit with a multi-branch flow channel that automatically opens and closes to discharge fluid.

[0007] The technical solution of the present invention includes:

[0008] A PDC drill bit with multi-branch flow channel self-opening and closing fluid discharge, comprising a PDC drill bit and its flow channels, wherein the PDC drill bit includes a drill bit body and a cutting edge, and the flow channels include...

[0009] The main flow channel is provided in the drill bit body and a set of branch flow channels are provided on the cutter head, wherein the main flow channel is connected to each branch flow channel;

[0010] An automatic opening and closing device is installed in the main flow channel, which is used to close each branch flow channel.

[0011] The automatic opening and closing device includes a sealing disc, on which a set of circular holes adapted to the inlet end of each branch channel are provided. When the drill bit body rotates, the sealing disc is driven to rotate by centrifugal force, so that the circular holes correspond to the inlet of the branch channel. When the drill bit body stops rotating, the circular holes are misaligned with the inlet of the branch channel by a reset device.

[0012] The reset device includes a connecting shaft, an annular groove, a connecting ring, and a spring;

[0013] One end of the connecting shaft is located at the center of the sealing disc.

[0014] The connecting shaft is configured in a guide groove that can move and rotate along it. The guide groove is coaxially formed in the drill bit body. A connecting ring is coaxially fixed on the outer circumferential surface of the other end of the connecting shaft. The connecting ring is disposed in the annular groove and rotates and moves axially along the annular groove. The annular groove is coaxially formed in the drill bit body.

[0015] The connecting ring is fixed to one end of the spring, and the other end of the spring is fixed to the annular groove.

[0016] The PDC drill bit also includes a first limiting device, which is disposed in a cavity. The cavity is formed in the drill bit body. The first limiting device includes a disk. A positioning rod is provided on one side of the connecting shaft of the disk. A positioning groove adapted to the positioning rod is provided on the connecting shaft adjacent to the disk. The positioning rod can be embedded in the positioning groove and restrict the rotation of the connecting shaft. A return spring is provided on the other side of the disk.

[0017] The disk and the electromagnet attract or repel each other, and the electromagnet is fixed inside the cavity.

[0018] The axial length of the annular groove is greater than the axial length of the connecting ring.

[0019] The connecting shaft is also provided with a second limiting device, which includes a connecting plate respectively disposed on the connecting shaft and a positioning plate fixedly connected to the drill bit body. The positioning plate restricts the rotation of the connecting shaft through the connecting plate.

[0020] The branch channel is equipped with a clearing device to prevent clogging by gravel.

[0021] The unblocking device includes an unblocking rod, which is sleeved in the first through hole of the mounting plate and can slide along the first through hole. The mounting plate is fixedly connected to the wall of the branch channel. An elastic rope is provided between the unblocking rod and the mounting plate. The unblocking rod can move repeatedly along the axial direction of the branch channel under the impact of the sealing disc to unblock the gravel in the branch channel and prevent blockage.

[0022] The unblocking rod is also equipped with a drive blade, which drives the unblocking rod to rotate under the drive of the liquid flow.

[0023] The unblocking rod is provided with one or more support rods at the rod end near the drill bit crown. One end of the support rod is hinged to the unblocking rod, and the other end can open under the action of centrifugal force. An elastic plate is also provided between the support rod and the unblocking rod. The elastic plate has a hollow air chamber and is provided with a constriction hole for gas to enter and exit.

[0024] A sealing ring for automatically opening and closing the main channel is provided at one end near the drill rod. A plate is provided on the sealing ring, and at least one second through hole is provided on the plate. A sealing plate and a torsion spring are provided in the second through hole. The sealing plate automatically opens and closes under the action of centrifugal force and torsion spring.

[0025] The beneficial effects of this invention are:

[0026] (i) This invention incorporates an automatic opening and closing device within the main flow channel of the drill bit body. When the drill bit body rotates at high speed, the sealing disc rotates under centrifugal force. At this time, the reset mechanism applies tension to the connecting shaft, aligning the circular hole with the inlet of the branch flow channel. Then, under the action of the high-pressure pump, the drilling fluid flows from the main flow channel of the drill bit body through the branch flow channel to the bottom of the well, providing cooling and cleaning for the drill bit body. When the drill bit body stops working, there will be residual drilling fluid inside the drill bit. At this time, the reset mechanism drives the connecting shaft to reset, which in turn drives the sealing disc to reset, causing the circular hole of the sealing disc to misalign with the channel of the branch flow channel. That is, the bottom of the sealing disc blocks the channel of the branch flow channel, sealing the remaining drilling fluid inside the drill bit body and preventing drilling fluid waste.

[0027] (II) This invention, by setting a first limiting device on the connecting shaft, utilizes a disk and a positioning rod, with the positioning rod embedded in the positioning groove to restrict the rotation of the connecting shaft. When the drill bit body is pulled out of the wellbore, rock cuttings and gravel may accumulate between the drill bit and the well wall, forming resistance or blockage. At this time, it is necessary to rotate the drill bit body to help clear the debris and rock cuttings accumulated around the drill bit, reduce resistance, and allow the drill bit body to be pulled out smoothly. At this time, the centrifugal force generated by the rotation will cause the sealing disk to stop sealing the branch channel, causing drilling fluid to flow out from the branch channel. However, no drilling fluid needs to flow out during this process, which would cause unnecessary waste of drilling fluid. At this time, when the drill bit body stops rotating, the electromagnet can be activated to push the disk, and the disk drives the positioning rod to insert into the positioning groove, thereby restricting the connecting shaft. In this case, even if the drill bit body rotates, the sealing disk will not rotate because the connecting shaft is restricted, so that the sealing disk can continue to seal the branch channel and prevent drilling fluid from flowing out and causing waste.

[0028] (iii) The present invention also includes a second limiting device, including a spring and a connecting ring. When the drill bit body stops rotating, the connecting shaft can be moved downward by means of the tension of the spring on the connecting ring. At this time, the sealing disc will fit tightly against the inner wall of the drill bit body, improving the sealing effect on the branch flow channel.

[0029] (iv) When the connecting shaft of the present invention rotates, it is controlled by centrifugal force. If the centrifugal force is too large, the round hole and the branch flow channel may not be aligned. The present invention sets a third limiting device, including a connecting plate and a positioning plate. When the connecting plate is blocked by the positioning plate, the connecting shaft will be restricted accordingly, so that the connecting shaft will not be driven by the centrifugal force to continue to rotate. At this time, the round hole and the branch flow channel are aligned, ensuring the normal flow of drilling fluid in the drill bit.

[0030] (v) The present invention provides a clearing device in the branch channel to prevent stone debris from clogging the channel. The device includes a clearing rod and an elastic rope. By using the impact of the sealing disc, the clearing rod can move back and forth along the branch channel repeatedly to prevent stone debris from clogging the branch channel.

[0031] (vi) Based on the unblocking rod, the present invention also provides a driving blade. The liquid flow in the branch channel is used to apply a driving force to the driving blade, thereby driving the unblocking rod to rotate. The rotation of the unblocking rod can keep the gravel in the branch channel loose, thereby improving the unblocking efficiency.

[0032] (vii) The present invention further provides a support rod at the front part of the unblocking rod. One end of the support rod is hinged to the unblocking rod, and the other end can open with the centrifugal force generated by the rotation of the drill bit. The opened support rod can effectively prevent the stone chips from entering the branch flow channel.

[0033] (viii) The present invention provides a hollow elastic sheet between the support rod and the unblocking rod. The elastic sheet contains an air chamber. When the support rod contracts, the gas in the air chamber can be ejected through the contraction hole. The ejected airflow can further disperse the gravel accumulated at the end of the branch channel.

[0034] (ix) The present invention also provides a sealing ring at the inlet end of the main channel of the drill bit body. By providing a second through hole on the sealing ring and providing a sealing plate and a torsion spring in the second through hole, the opening and closing of the main channel is controlled by the centrifugal force generated by the rotation of the drill bit and the restoring force of the torsion spring. Attached Figure Description

[0035] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0036] Figure 1 This is a schematic diagram of the external structure of the PDC drill bit of the present invention;

[0037] Figure 2 This is a schematic diagram of the internal cross-sectional structure of the PDC drill bit of the present invention;

[0038] Figure 3 This is a schematic diagram of the sealing disc;

[0039] Figure 4 yes Figure 2 Enlarged view of part A in the middle;

[0040] Figure 5 yes Figure 4 Enlarged view of part B in the middle;

[0041] Figure 6 This is a partial cross-sectional schematic diagram of the branch flow channel;

[0042] Figure 7 yes Figure 6 A magnified view of a portion of the C-shaped area;

[0043] Figure 8 This is a partial cross-sectional schematic diagram of the main channel.

[0044] Figure label:

[0045] 1-Drill bit body, 2-Branch flow channel, 3-Sealing disc, 4-Round hole, 5-Reset spring, 6-Connecting shaft, 7-Connecting plate, 8-Positioning plate, 9-Cavity, 10-Disk, 11-Positioning rod, 12-Positioning groove, 13-Annular groove, 14-Connecting ring, 15-Electromagnet, 16-Mounting plate, 17-Cylinder, 18-Dredging rod, 19-Elastic rope, 20-Drive blade, 21-Support rod, 22-Elastic sheet, 23-Contraction hole, 24-Sealing ring, 25-Second through hole, 26-Sealing plate, 27-Spring. Detailed Implementation

[0046] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] This invention provides a PDC drill bit with a multi-branch flow channel that automatically opens and closes to discharge fluid.

[0049] like Figure 1 , Figure 2 As shown, the drill bit body 1 and branch flow channels 2 are included. The drill bit body 1 is provided with a main flow channel. The cutting edge of the drill bit body 1 includes several cutting edges. Branch flow channels 2 are provided between adjacent cutting edges. The lower part of the main flow channel is connected to each branch flow channel 2 through a chamber.

[0050] An automatic opening and closing device is provided in the main channel, which is used to close each branch channel 2.

[0051] The automatic opening and closing device includes a sealing disc 3, on which a set of circular holes 4 are provided that are adapted to the inlet end of each branch channel 2. When the drill bit body 1 rotates, the sealing disc 3 is driven to rotate by centrifugal force, so that the circular holes 4 correspond to the inlet of the branch channel 2. When the drill bit body 1 stops rotating, the circular holes 4 are misaligned with the inlet of the branch channel 2 by a reset device.

[0052] The sealing disc 3 is disposed within the cavity.

[0053] like Figure 3 As shown, the sealing disc 3 is a thin shell that is adapted to the inner wall of the cavity, and it is provided with a number of round holes 4, the number and size of which are adapted to the inlet end of the branch channel 2.

[0054] When the sealing disc 3 is attached to the inner wall of the chamber, and each round hole 4 corresponds to the inlet of the branch flow channel 2, then each branch flow channel 2 is completely unobstructed, and the drilling fluid can flow through the branch flow channel 2 to the cutting surface of the drill bit without any obstruction; when each round hole 4 is completely misaligned with the inlet of the branch flow channel 2, then each branch flow channel 2 is completely sealed by the sealing disc 3, and the drilling fluid will be blocked in the main flow channel of the drill bit.

[0055] Among them, see Figure 4 and Figure 5In this embodiment, the reset device includes a connecting shaft 6, an annular groove 13, a connecting ring 14, and a spring 27;

[0056] One end of the connecting shaft 6 is located at the center of the sealing disc 3. The connecting shaft 6 is disposed in a guide groove that can move and rotate along it. The guide groove is coaxially opened in the drill bit body 1. A connecting ring 14 is coaxially fixed on the outer circumferential surface of the other end of the connecting shaft 6. The connecting ring 14 is disposed in the annular groove 13 and rotates and moves axially along the annular groove 13. The annular groove 13 is coaxially opened in the drill bit body 1.

[0057] The connecting ring 14 is fixed to one end of the spring 27, and the other end of the spring 27 is fixed to the annular groove 13.

[0058] The axial length of the annular groove 13 is greater than the axial length of the connecting ring 14.

[0059] In this embodiment, when the drill bit body 1 rotates, centrifugal force drives the sealing disc 3 to rotate around its axis. This rotational motion is synchronously transmitted to the end via the connecting shaft 6 fixed at the center of the sealing disc. The connecting shaft 6 drives the connecting ring 14 to rotate within the annular groove 13. At this time:

[0060] Spring 27 is twisted and stretched due to the rotation of connecting ring 14, at which time torque potential energy is accumulated; sealing disc 3 rotates to a specific angle, so that the surface circular hole 4 is precisely aligned with the inlet of branch channel 2, and the channel is opened.

[0061] When the drill bit body 1 stops rotating, the centrifugal force disappears, and spring 27 releases the torsional potential energy.

[0062] Spring 27 drives connecting ring 14 to rotate in the opposite direction; connecting ring 14 drives sealing disc 3 to rotate back to the initial angle through connecting shaft 6; the circular hole 4 of sealing disc 3 is completely misaligned with the inlet of branch channel 2, and the channel is reliably sealed.

[0063] The first limiting device is disposed in the cavity 9, which is opened in the drill bit body 1. The first limiting device includes a disk 10. A positioning rod 11 is provided on one side of the connecting shaft 6 of the disk 10. A positioning groove 12 adapted to the positioning rod 11 is provided on the connecting shaft 6 adjacent to the disk 10. The positioning rod 11 can be embedded in the positioning groove 12 and restrict the rotation of the connecting shaft 6. A return spring 5 is provided on the other side of the disk 10.

[0064] The disk 10 and the electromagnet 15 attract or repel each other, and the electromagnet 15 is fixed inside the cavity 9.

[0065] When the drill bit body 1 needs to be pulled out of the drilled wellbore, rock cuttings may accumulate between the drill bit and the well wall, creating resistance or blockage. At this time, the drill bit body 1 needs to rotate to help clear the rock cuttings accumulated around the drill bit, reducing resistance and allowing the drill bit body 1 to be pulled out smoothly. However, the centrifugal force generated by the rotation of the drill bit will cause the sealing disc 3 to rotate, no longer sealing the branch channel 2, allowing drilling fluid to flow out from the branch channel 2. However, this process does not require the drilling fluid to flow out, inevitably causing unnecessary waste of drilling fluid.

[0066] Therefore, when the drill bit body 1 stops rotating, the electromagnet 15 is activated to push the disk 10. The disk 10 drives the positioning rod 11 to insert into the positioning groove 12, thereby restricting the connecting shaft 6. In this case, even if the drill bit body 1 rotates, the sealing disk 3 will not rotate because the connecting shaft 6 is restricted, so that the sealing disk 3 can continue to seal the branch flow channel 2 and prevent drilling fluid from flowing out and causing waste.

[0067] When the connecting shaft 6 rotates, it is controlled by centrifugal force. When the centrifugal force is too large, the circular hole 4 and the branch flow channel 2 may not be aligned. To address this, this embodiment provides a second limiting device, including a connecting plate 7 and a positioning plate 8. When the connecting shaft 6 drives the connecting plate 7 to rotate, it is blocked from contacting the positioning plate 8. Consequently, the connecting shaft 6 will be restricted from continuing to rotate, ensuring that the circular hole 4 and the branch flow channel 2 remain aligned, so as to ensure that the drilling fluid in the drill bit can flow normally.

[0068] like Figure 6 As shown in the figure, in one embodiment, a dredging rod 18 is also provided in the branch channel 2, and an installation plate 16 is fixedly provided in the branch channel 2. The dredging rod 18 is connected to the installation plate 16 through a cylinder 17 and can slide or rotate along the first through hole of the installation plate 16.

[0069] In this embodiment, the cylinder 17 can be fixedly connected to either the unblocking rod 18 or the mounting plate 16.

[0070] As a preferred embodiment, the cylinder 17 is fixedly connected to the mounting plate 16. The cylinder 17 also serves as the cylindrical guide rail for the unclogging rod 18, and the unclogging rod 18 slides or rotates along the inner hole of the cylinder 17.

[0071] An elastic rope 19 is provided between the unblocking rod 18 and the mounting plate 16. On the one hand, the unblocking rod 18 is impacted and moves with the sealing disc 3 as it moves up and down. On the other hand, under the action of the elastic rope 19, the unblocking rod 18 reciprocates under the continuous impact of the sealing disc 3 and the restoring force of the elastic rope 19, thus unblocking the gravel that flows into the branch channel 2 and preventing blockage.

[0072] In addition to the impact, the up-and-down movement of the sealing disk 3 can also be achieved by controlling the magnetism of the electromagnet 15 to continuously attract or repel the disk 10, thereby driving the connecting shaft 6 to move up and down.

[0073] In another embodiment, one or a group of drive blades 20 can be provided on the unblocking rod 18. The drive blades 20 have the profile of propeller blades and can generate driving force under the impact of drilling fluid flow to drive the unblocking rod 18 to rotate. The rotation of the unblocking rod 18 can loosen the accumulated rock debris in the branch channel 2, making it easier for the drilling fluid flow to flush the rock debris out of the branch channel 2 and avoid blockage.

[0074] As another embodiment, one or a group of support rods 21 are provided at the front end of the unblocking rod 18 near the outlet end of the branch channel 2. One end of the support rod 21 is hinged to the unblocking rod 18, and the other end is in a free state. It can automatically open under the action of centrifugal force as the drill bit rotates. The opened support rod 21 can block some of the stone chips from entering the branch channel 2.

[0075] like Figure 7 As shown, in one embodiment, an elastic sheet 22 with an air chamber can also be provided between the support rod 21 and the unblocking rod 18. A shrinkage hole 23 is provided on the side of the elastic sheet 22 facing the branch channel 2. When the support rod 21 contracts under the action of the elastic sheet 22, the air chamber in the elastic sheet 22 is squeezed, and the air in the air chamber is ejected outward through the shrinkage hole 23, which can further prevent the gravel from entering the branch channel 2.

[0076] like Figure 8 As shown in the figure, in one embodiment, a sealing ring 24 is provided in the main channel of the drill bit body 1 near the upper end of the drill bit. The sealing ring 24 is fixed to the inner wall of the main channel. One or a set of second through holes 25 are provided on the sealing ring 24, through which drilling fluid can flow. A sealing plate 26 is provided in the second through hole 25. The sealing plate 26 is kept open under the action of centrifugal force generated by the rotation of the drill bit. When the drill bit stops rotating, it is closed under the action of torsion spring built into the second through hole 25.

[0077] In the description of this invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate direction or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0078] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0079] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0080] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A PDC drill bit with multi-branch flow channel self-opening and closing fluid discharge, comprising a PDC drill bit and its flow channels, wherein the PDC drill bit comprises a drill bit body (1) and a cutting edge, characterized in that, The flow channel includes: The main flow channel is provided in the drill bit body (1) and a set of branch flow channels (2) are provided on the cutter crown, wherein the main flow channel is connected to each branch flow channel (2); An automatic opening and closing device is provided in the main channel, which is used to close each of the branch channels (2). The automatic opening and closing device includes a sealing disc (3), on which a set of circular holes (4) adapted to the inlet end of each branch channel (2) are provided. When the drill body (1) rotates, the sealing disc (3) is driven to rotate by centrifugal force, so that the circular holes (4) correspond to the inlet of the branch channel (2). When the drill body (1) stops rotating, the circular holes (4) are misaligned with the inlet of the branch channel (2) by a reset device. The reset device includes a connecting shaft (6), an annular groove (13), a connecting ring (14), and a spring (27). One end of the connecting shaft (6) is located at the center of the sealing disc (3). The connecting shaft (6) is arranged in a guide groove that can move and rotate along it. The guide groove is coaxially opened in the drill bit body (1). The connecting ring (14) is coaxially fixed on the outer circumferential surface of the other end of the connecting shaft (6). The connecting ring (14) is arranged in the annular groove (13) and can rotate and move axially along the annular groove (13). The connecting ring (14) is fixed to one end of the spring (27), and the other end of the spring (27) is fixed to the annular groove (13); The PDC drill bit also includes a first limiting device, which is disposed in a cavity (9) and the cavity (9) is opened in the drill bit body (1). The first limiting device includes a disk (10). A positioning rod (11) is provided on one side of the connecting shaft (6) of the disk (10). A positioning groove (12) adapted to the positioning rod (11) is provided on the connecting shaft (6) adjacent to the disk (10). The positioning rod (11) can be embedded in the positioning groove (12) and restrict the rotation of the connecting shaft (6). A return spring (5) is provided on the other side of the disk (10). The disk (10) and the electromagnet (15) attract or repel each other, and the electromagnet (15) is fixed inside the cavity (9); The branch channel (2) is equipped with a clearing device to prevent stone debris from clogging it; The unblocking device includes an unblocking rod (18), which is sleeved in the first through hole of the mounting plate (16) and can slide along the first through hole. The mounting plate (16) is fixedly connected to the wall of the branch channel (2), and an elastic rope (19) is provided between the unblocking rod (18) and the mounting plate (16). The unblocking rod (18) is also provided with a driving blade (20), which drives the unblocking rod (18) to rotate under the drive of liquid flow; The unblocking rod (18) has one or a set of support rods (21) near the end of the blade crown. One end of the support rod (21) is hinged to the unblocking rod (18), and the other end can open under the action of centrifugal force. An elastic sheet (22) is also provided between the support rod (21) and the unblocking rod (18). The elastic sheet (22) has a hollow air chamber and is provided with a constriction hole (23) for gas to enter and exit. A sealing ring (24) for automatically opening and closing the main channel is provided at one end near the drill rod. A plate is provided on the sealing ring (24), and at least one second through hole (25) is provided on the plate. A sealing plate (26) and a torsion spring are provided in the second through hole (25). The sealing plate (26) automatically opens and closes under the action of centrifugal force and the torsion spring.

2. The PDC drill bit with multi-branch flow channel self-opening and closing fluid discharge as described in claim 1, characterized in that, The annular groove (13) is coaxially formed inside the drill bit body (1).

3. The PDC drill bit with multi-branch flow channel self-opening and closing fluid discharge as described in claim 2, characterized in that, The axial length of the annular groove (13) is greater than the axial length of the connecting ring (14).

4. The PDC drill bit with multi-branch flow channel self-opening and closing fluid discharge as described in claim 1, characterized in that, The connecting shaft (6) is also provided with a second limiting device, which includes a connecting plate (7) respectively disposed on the connecting shaft (6) and a positioning plate (8) fixedly connected to the drill bit body (1). The positioning plate (8) restricts the rotation of the connecting shaft (6) through the connecting plate (7).

5. A PDC drill bit with self-opening and closing fluid discharge in a multi-branch flow channel as described in claim 1, characterized in that, The unblocking rod (18) can move repeatedly along the axial direction of the branch channel (2) under the impact of the sealing disc (3) to unblock the gravel in the branch channel (2) and prevent blockage.

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