PDC (Polycrystalline Diamond Compact) drill bit with multiple branch flow channels capable of automatically opening and closing liquid outlet

Abstract

The invention belongs to the technical field of oil and gas drilling, particularly relates to a PDC drill bit with multiple branch flow channels capable of automatically opening and closing liquid outlet, and aims to solve the problem that drilling fluid is wasted when the drill bit stops working. The PDC drill bit capable of automatically opening and closing the liquid outlet through the multiple branch flow channels comprises the PDC drill bit and the flow channels of the PDC drill bit, 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 branch flow channels are arranged on the cutter crown. And the automatic opening and closing device is used for closing each branch flow channel. The structure is reasonable, and automatic opening and closing of drilling fluid of the drill bit are achieved through centrifugal force generated by rotation of the drill bit and the reset device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas drilling, and particularly relates to a PDC drill bit with self-opening and closing multi-branch flow channels. BACKGROUND

[0002] A PDC drill bit is mainly composed of a diamond compact and a hard alloy base. This unique design makes the drill bit reach an unprecedented level in hardness and wear resistance. The diamond compact, as the cutting part of the drill bit, has extremely high hardness and excellent wear resistance, and can easily cope with various complex formations, greatly improving drilling efficiency. Compared with traditional three-cone drill bits, PDC drill bits have significant advantages in drilling speed, drilling efficiency, and drill bit life. For example, in some hard formations, the drilling speed of a PDC drill bit can even be more than twice that of a three-cone drill bit, greatly shortening the drilling cycle and reducing costs.

[0003] A plurality of branch flow channels are provided on the PDC drill bit for the flow of drilling fluid to ensure that the drilling fluid can effectively flush and clean the cutters and the surface of the drill bit, and at the same time cool the PDC drill bit, thereby prolonging its service life.

[0004] The PDC drill bit is hollow inside. When drilling fluid is pumped into the interior of the PDC drill bit by a high-pressure pump, the liquid rapidly flows within the interior space of the drill bit, and is then directed to the bottom of the drill hole through the flow channels on the drill bit, providing cooling and cleaning effects for the drill bit, and also helping to carry the drill cuttings to the ground. This circulating drilling fluid flow mode ensures the efficiency and stability of the drilling process.

[0005] However, when the PDC drill bit needs to be temporarily stopped for various reasons, drilling fluid does not need to be injected at this time, but the flow channels inside the PDC drill bit are still in a constant open state. This means that the drilling fluid remaining inside the drill bit will continue to flow out of the flow channels under the action of gravity and pressure, resulting in a large amount of waste of drilling fluid. SUMMARY

[0006] In order to solve the above-mentioned problems in the prior art, i.e. the problem of waste of drilling fluid when the drill bit is temporarily stopped, the present application provides a PDC drill bit with self-opening and closing multi-branch flow channels.

[0007] The technical scheme of the present application comprises:

[0008] A PDC drill bit with self-opening and closing multi-branch flow channels, comprising a PDC drill bit and its flow channels, the PDC drill bit comprising a drill bit body and a crown, and the flow channels comprising

[0009] a main flow channel arranged in the drill bit body and a group of branch flow channels arranged on the crown, the main flow channel being in communication with each branch flow channel;

[0010] The main flow channel is provided with an automatic opening and closing device for closing each branch flow channel.

[0011] The automatic opening and closing device comprises a sealing disc provided with a group of circular holes matched with the inlet ends of the branch flow channels. When the drill bit body rotates, the sealing disc rotates by centrifugal force, so that the circular holes are matched with the inlets of the branch flow channels.

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

[0013] One end of the connecting shaft is arranged at the center of the sealing disc,

[0014] The connecting shaft is arranged in a guide groove capable of moving and rotating along the connecting shaft, the guide groove is coaxially arranged in the drill bit body, and the outer circumferential surface of the other end of the connecting shaft is coaxially fixed with the connecting ring.

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

[0016] The PDC drill bit further comprises a first limiting device arranged in a cavity arranged in the drill bit body. The first limiting device comprises a magnetic disc, one side of the connecting shaft of the magnetic disc is provided with a positioning rod, and the connecting shaft adjacent to the magnetic disc is provided with a positioning groove matched with the positioning rod. The positioning rod can be embedded in the positioning groove and limit the rotation of the connecting shaft.

[0017] The magnetic disc and the electromagnet attract or repel each other, and the electromagnet is fixed in 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 further provided with a second limiting device, the second limiting device comprises a connecting plate arranged on the connecting shaft and a positioning plate fixedly connected with the drill bit body. The positioning plate limits the rotation of the connecting shaft through the connecting plate.

[0020] The branch flow channel is provided with a dredging device for preventing the blockage of the broken stones.

[0021] The dredging device comprises a dredging rod sleeved in a through hole of a mounting plate and slidable along the through hole, the mounting plate is fixedly connected with the pipe wall of the branch flow channel, an elastic rope is arranged between the dredging rod and the mounting plate, and the dredging rod is repeatedly movable along the axial direction of the branch flow channel under the impact of the sealing disc to dredge the debris in the branch flow channel and prevent blockage.

[0022] The rod body of the dredging rod is further provided with a driving blade, and the driving blade is driven to rotate the dredging rod under the driving of liquid flow.

[0023] The rod end of the dredging rod close to the crown of the drill bit is provided with one or a group of supporting rods, one end of the supporting rod is hinged to the dredging rod, the other end of the supporting rod is openable under the action of centrifugal force, and an elastic sheet is further arranged between the supporting rod and the dredging rod, the elastic sheet has a hollow air chamber and is provided with a shrinkage hole for gas to enter and exit.

[0024] One end of the main flow channel close to the drill rod is provided with a sealing ring for automatically opening and closing the main flow channel, the sealing ring is provided with a plate, at least one through hole is arranged on the plate, a sealing plate and a torsion spring are arranged in the through hole, and the sealing plate is automatically opened and closed under the action of centrifugal force and the torsion spring.

[0025] The beneficial effects of the present application are as follows:

[0026] (1) The present application sets an automatic opening and closing device in the main flow channel of the drill bit body, and when the drill bit body rotates at high speed, the sealing disc rotates under the action of centrifugal force, at this time, the reset mechanism exerts a pulling force on the connecting shaft, so that the circular hole is aligned with the inlet of the branch flow channel, then the drilling fluid is guided to the bottom of the well under the action of the high-pressure pump, through the main flow channel of the drill bit body and the branch flow channel, to provide cooling and cleaning effects for the drill bit body; when the drill bit body stops working, there will be residual drilling fluid in the drill bit, at this time, the reset mechanism drives the connecting shaft to reset, at this time, the connecting shaft drives the sealing disc to reset, so that the circular hole of the sealing disc is misaligned with the passage of the branch flow channel, that is, the bottom surface of the sealing disc blocks the passage of the branch flow channel, so as to seal the residual drilling fluid in the drill bit body, preventing waste of the drilling fluid.

[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] (Eight) The hollow elastic sheet is arranged between the supporting rod and the dredging rod, the elastic sheet is internally provided with an air chamber, when the supporting rod is contracted, the gas in the air chamber can be sprayed out through the contraction hole, and the sprayed gas flow can further disperse the gravel chips accumulated at the branch flow passage port end.

[0034] (Nine) The sealing ring is arranged at the inlet end of the main flow passage of the drill bit body, the through hole is arranged on the sealing ring, the sealing plate and the torsion spring are arranged in the through hole, the opening and closing of the main flow passage are controlled by the centrifugal force generated by the rotation of the drill bit and the restoring force of the torsion spring. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

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

[0039] Figure 4 is Figure 2 is a partial enlarged view of A;

[0040] Figure 5 is Figure 4 is a partial enlarged view of B;

[0041] Figure 6 is a schematic diagram of the partial cross section of the branch flow passage;

[0042] Figure 7 is Figure 6 is a partial enlarged view of C;

[0043] Figure 8 is a schematic diagram of the partial cross section of the main flow passage.

[0044] LIST OF REFERENCE NUMERALS:

[0045] 1-drill bit body, 2-branch flow passage, 3-sealing disc, 4-round hole, 5-return spring, 6-connection shaft, 7-connection plate, 8-positioning plate, 9-cavity, 10-magnetic disc, 11-positioning rod, 12-positioning groove, 13-annular groove, 14-connection ring, 15-electromagnet, 16-mounting plate, 17-cylinder, 18-dredging rod, 19-elastic rope, 20-driving blade, 21-supporting rod, 22-elastic sheet, 23-contraction hole, 24-sealing ring, 25-through hole, 26-sealing plate, 27-spring. DETAILED DESCRIPTION

[0046] The application 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 merely intended for the purpose of interpretation of the related application and are not limiting of the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for the convenience of description.

[0047] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0048] The application provides a PDC drill bit with self-opening and closing of multiple branch flow channels.

[0049] As shown in Figure 1 , Figure 2 , the drill bit body 1 and the branch flow channel 2 are included, the main flow channel is arranged in the drill bit body 1, the cutter crown part of the drill bit body 1 includes a plurality of blades, the branch flow channel 2 is arranged between adjacent blades, and the lower part of the main flow channel is connected with each branch flow channel 2 through a cavity.

[0050] The automatic opening and closing device is arranged in the main flow channel and used to close each branch flow channel 2.

[0051] The automatic opening and closing device includes a sealing disc 3, a group of circular holes 4 adapted to the inlet ends of each branch flow channel 2 are arranged on the sealing disc 3, the sealing disc 3 is driven to rotate by centrifugal force when the drill bit body 1 rotates, the circular holes 4 correspond to the inlets of the branch flow channels 2, and the circular holes 4 are dislocated from the inlets of the branch flow channels 2 through a reset device when the drill bit body 1 stops rotating.

[0052] The sealing disc 3 is arranged in the cavity.

[0053] As shown in Figure 3 , the sealing disc 3 is a thin sheet shell body adapted to the inner wall of the cavity, and a plurality of circular holes 4 are arranged on the sealing disc 3, and the number and size of the circular holes 4 are adapted to the inlet ends of the branch flow channels 2.

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

[0055] In this embodiment, the reset device includes a connecting shaft 6, an annular groove 13, a connecting ring 14 and a spring 27, as shown in Figure 4 and Figure 5 .

[0056] One end of the connecting shaft 6 is arranged at the center of the sealing disc 3, the connecting shaft 6 is arranged in a guide groove capable of moving and rotating along it, the guide groove is coaxially arranged in the drill bit body 1, and the outer circumferential surface of the other end of the connecting shaft 6 is coaxially fixed with a connecting ring 14, the connecting ring 14 is arranged in the annular groove 13 and rotates and moves axially along the annular groove 13, and the annular groove 13 is coaxially arranged in the drill bit body 1.

[0057] The connecting ring 14 is fixed with one end of the spring 27, and the other end of the spring 27 is fixed with 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, the centrifugal force drives the sealing disc 3 to rotate around the axis. The rotating motion is synchronously transmitted to the end through the connecting shaft 6 fixed in the center of the sealing disc. The connecting shaft 6 drives the connecting ring 14 to make a rotating motion in the annular groove 13, at this time:

[0060] The spring 27 is twisted and stretched due to the rotation of the connecting ring 14, at this time the torque potential energy is accumulated; the sealing disc 3 is rotated to a certain angle, so that the surface hole 4 is accurately aligned with the entrance of the branch flow passage 2, and the flow passage is opened.

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

[0062] The spring 27 drives the connecting ring 14 to rotate in the opposite direction; the connecting ring 14 drives the sealing disc 3 to rotate in the opposite direction through the connecting shaft 6; the hole 4 of the sealing disc 3 is completely misaligned with the entrance of the branch flow passage 2, and the flow passage is reliably closed.

[0063] The first limiting device is arranged in the cavity 9, the cavity 9 is arranged in the drill bit body 1, the first limiting device includes a magnetic disc 10, one side of the connecting shaft 6 of the magnetic disc 10 is provided with a positioning rod 11, the connecting shaft 6 adjacent to the magnetic disc 10 is provided with a positioning groove 12 matched with the positioning rod 11, the positioning rod 11 can be embedded in the positioning groove 12 and limit the rotation of the connecting shaft 6, and the other side of the magnetic disc 10 is provided with a reset spring 5.

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

[0065] When the drill bit body 1 needs to be pulled out from the drilled well, the rock debris may be accumulated between the drill bit and the well wall, forming resistance or blockage, at this time, the drill bit body 1 needs to be rotated to help remove the rock debris accumulated around the drill bit, reduce the resistance, and make the drill bit body 1 smoothly pulled out. However, the centrifugal force generated by the rotation of the drill bit will cause the sealing disc 3 to rotate, so that the drill fluid flows out from the branch flow channel 2, but the drill fluid does not need to flow out in this process, which will inevitably cause unnecessary waste of the drill fluid.

[0066] Therefore, when the drill bit body 1 stops rotating, the electromagnet 15 is started to push the magnetic disc 10, and the magnetic disc 10 drives the positioning rod 11 to be inserted into the positioning groove 12, thereby limiting the connecting shaft 6. In this case, even if the drill bit body 1 rotates, because the connecting shaft 6 is limited, the sealing disc 3 will not rotate, so that the sealing disc 3 can continue to seal the branch flow channel 2, preventing the waste caused by the flow of the drill fluid.

[0067] When the connecting shaft 6 rotates, it is controlled by the centrifugal force. When the centrifugal force is too large, the round hole 4 and the branch flow channel 2 cannot be aligned. In view of this situation, the second limiting device is arranged in the embodiment, which includes the connecting plate 7 and the positioning plate 8. When the connecting shaft 6 drives the connecting plate 7 to rotate, it is blocked by the positioning plate 8, and correspondingly, the connecting shaft 6 will be limited to continue to rotate, ensuring that the round hole 4 and the branch flow channel 2 are aligned to ensure that the drill fluid in the drill bit can flow normally.

[0068] As shown in Figure 6 As an embodiment, the branch flow channel 2 is also provided with a dredging rod 18, and the mounting plate 16 is fixedly arranged in the branch flow channel 2. The dredging rod 18 is connected with the mounting plate 16 through the cylinder 17 and can slide or rotate along the mounting hole of the mounting plate 16.

[0069] In the embodiment, the cylinder 17 can be fixedly connected with the dredging rod 18 or fixedly connected with the mounting plate 16.

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

[0071] The elastic rope 19 is arranged between the dredging rod 18 and the mounting plate 16. On the one hand, the dredging rod 18 is impacted and moves with the up-down movement of the sealing disc 3, and on the other hand, under the action of the elastic rope 19, the dredging rod 18 reciprocates under the impact of the sealing disc 3 and the restoring force of the elastic rope 19, dredges the rock debris flowing into the branch flow channel 2, and avoids blockage.

[0072] The up and down movement of the sealing disc 3 can be achieved by controlling the magnetism of the electromagnet 15, which constantly attracts or repels the magnetic disc 10, thereby driving the connecting shaft 6 to move up and down.

[0073] As another embodiment, one or a set of driving blades 20 can be arranged on the dredging rod 18, which has the profile of a propeller blade and can generate driving force under the impact of the drilling fluid flow, thereby driving the dredging rod 18 to rotate, which can facilitate the loosening of the accumulated gravel chips in the branch flow channel 2 and the flushing of the gravel chips out of the branch flow channel 2 by the drilling fluid flow, thereby avoiding blockage.

[0074] As another embodiment, one or a set of support rods 21 can be arranged on the dredging rod 18 near the outlet end of the branch flow channel 2, one end of the support rod 21 being hinged to the dredging rod 18 and the other end being in a free state and capable of rotating with the drill bit and automatically expanding under the action of centrifugal force, the expanded support rod 21 being capable of blocking a portion of the gravel chips from entering the branch flow channel 2.

[0075] As shown in Figure 7 As an embodiment, a resilient sheet 22 with a hollow air chamber can be arranged between the support rod 21 and the dredging rod 18, the side of the resilient sheet 22 facing the branch flow channel 2 being provided with a contraction hole 23, when the support rod 21 is contracted under the action of the resilient sheet 22, the air chamber in the resilient sheet 22 is compressed, and the air in the air chamber is sprayed outwards through the contraction hole 23, which can further hinder the gravel chips from entering the branch flow channel 2.

[0076] As shown in Figure 8 As an embodiment, a sealing ring 24 can be arranged in the main flow channel of the drill bit body 1 near the upper end of the drill bit, the sealing ring 24 being fixed to the inner wall of the main flow channel, one or a set of through holes 25 being arranged on the sealing ring 24, the drilling fluid being capable of flowing through the through holes 25, and a sealing plate 26 being arranged in the through holes 25, the sealing plate 26 being kept open under the action of centrifugal force generated by the rotation of the drill bit and being closed under the action of a torsional spring arranged in the through hole 25 when the drill bit stops rotating.

[0077] In the description of the present application, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicating the direction or positional relationship are based on the direction or positional relationship shown in the drawings, which is merely for the convenience of description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0078] In addition, it needs to be explained that in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0079] The term "comprising" or any other similar word is intended to encompass a non-exclusive inclusion, so that a process, method, article, or equipment / device including a series of elements includes not only those elements, but also other elements not explicitly listed, or inherent elements of these processes, methods, articles, or equipment / devices.

[0080] So far, the technical solutions of the present application have been described in combination with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after the changes or replacements will fall within the protection scope of the present application.

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 branch channel (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.

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 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). 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 arranged 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). 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).

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 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).

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

5. A PDC drill bit with self-opening and closing fluid discharge in a multi-branch flow channel as described in claim 4, 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).

6. The PDC drill bit with multi-branch flow channel self-opening and closing fluid discharge as described in claim 1, characterized in that, The branch channel (2) is equipped with a dredging device to prevent stone debris from clogging it.

7. A PDC drill bit with self-opening and closing fluid discharge in a multi-branch flow channel as described in claim 6, characterized in that, The unblocking device includes an unblocking rod (18), which is fitted into the through hole of the mounting plate (16) and can slide along the through hole. The mounting plate (16) is fixedly connected to the wall of the branch channel (2). An elastic rope (19) is provided between the unblocking rod (18) and the mounting plate (16). 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.

8. A PDC drill bit with self-opening and closing fluid discharge in a multi-branch flow channel as described in claim 7, characterized in that, 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.

9. A PDC drill bit with self-opening and closing fluid discharge in a multi-branch flow channel as described in claim 8, characterized in that, The unblocking rod (18) has one or a set of support rods (21) near the end of the rod of the drill bit 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.

10. 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, 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 through hole (25) is provided on the plate. A sealing plate (26) and a torsion spring are provided in the through hole (25). The sealing plate (26) automatically opens and closes under the action of centrifugal force and torsion spring.

Images