Electrode drill bit for improving pulse discharge rock breaking efficiency

Abstract

The invention belongs to the technical field of well drilling, exploitation and exploration, and discloses an electrode drill bit used for improving pulse discharge rock breaking efficiency, the electrode drill bit comprises a drill bit body, a cable connecting rod, an insulating sleeve, a high-voltage electrode, a grounding electrode and a strong magnetic source, the drill bit body is hollow, and the cable connecting rod is installed in the drill bit body through the insulating sleeve; the bottom end of the cable connecting rod extends to the position below the drill bit body, the high-voltage electrode is connected with the bottom end of the cable connecting rod, the multiple grounding electrodes are annularly arrayed on the outer side of the high-voltage electrode and fixedly connected with the grounding electrode connecting disc, and the bottom end of the insulating sleeve extends into an annular space between the high-voltage electrode and the grounding electrodes. And the at least one strong magnetic source array is arranged in the insulating sleeve between the high-voltage electrode and the grounding electrode and is used for generating a magnetic field for guiding the plasma channel to extend into the rock during pulse discharge. According to the invention, the length of the discharge channel and the initial damage range in the rock are increased, and the utilization rate of single pulse energy and the rock breaking volume are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of drilling, mining and exploration technology, and specifically relates to an electrode drill bit for improving the efficiency of pulsed discharge rock breaking. Background Technology

[0002] Pulse discharge rock breaking technology is an emerging non-mechanical rock breaking method. Its principle is to create plasma channels within the rock or between the rock and a liquid medium using high-voltage pulses. The shock waves and thermal stress generated by the rapid expansion of the plasma cause the rock to fracture. Compared with traditional mechanical or explosive rock breaking, this method has advantages such as concentrated energy, high rock fragmentation rate, strong controllability, no risk of explosive storage or personnel evacuation, and environmental friendliness.

[0003] However, existing pulsed discharge rock-breaking technology has the following problems: the growth of plasma channels is often random and tends to develop along the shortest path between electrodes (i.e., laterally), resulting in limited rock-breaking depth, small effective fragmentation volume per discharge, and insufficient energy utilization. When other conditions remain constant, the more plasma channels develop downwards into the rock, the larger the rock fragmentation volume per unit energy, and the better the rock-breaking effect. Therefore, improving rock-breaking efficiency requires extending plasma channels downwards into the rock.

[0004] Existing research on pulsed discharge rock breaking has shown that adding an external magnetic field to a traditional pulsed rock breaking device can affect the trajectory of charged particles (plasma channels). During pulsed discharge, if a magnetic field of appropriate direction is applied to the discharge region, the plasma will be subjected to the Lorentz force, causing its direction of motion to deflect. Theoretically, by designing the direction of the magnetic field, the plasma channel can be guided to extend deeper into the rock, thereby increasing the depth and volume of the breaking pit and improving rock breaking efficiency. However, how to effectively integrate the magnetic field generator into the electrode drill bit structure for practical engineering applications and achieve coordinated control of the magnetic field direction, intensity, and discharge process remains a pressing technical challenge. Summary of the Invention

[0005] The purpose of this invention is to solve the problems in the background art and provide an electrode drill bit for improving the rock-breaking efficiency of pulse discharge. This electrode drill bit integrates an adjustable strong magnetic source in the discharge area to actively guide the plasma channel to extend downward into the rock, thereby increasing the rock breaking volume of a single discharge and effectively improving the rock-breaking efficiency.

[0006] The objective of this invention is achieved through the following technical solution: An electrode drill bit for improving the efficiency of pulsed discharge rock breaking includes a drill bit body, a cable connecting rod, an insulating sleeve, a high-voltage electrode, a grounding electrode, and a strong magnetic source. The drill bit body is hollow and includes, from top to bottom, a connector, a limiting sleeve, a drill bit sleeve, and a grounding electrode connecting plate. The cable connecting rod is installed inside the drill bit sleeve and the grounding electrode connecting plate through the insulating sleeve, with the bottom end of the cable connecting rod extending below the grounding electrode connecting plate. The high-voltage electrode is located on the center line below the drill bit body and is connected to the bottom end of the cable connecting rod. Several grounding electrodes are arranged in a ring array outside the high-voltage electrode and are fixedly connected to the grounding electrode connecting plate. The bottom end of the insulating sleeve extends into the annular space between the high-voltage electrode and the grounding electrode. At least one strong magnetic source array is installed inside the insulating sleeve between the high-voltage electrode and the grounding electrode to generate a magnetic field that guides the plasma channel to extend into the rock during pulsed discharge.

[0007] A support spring is installed between the connector and the drill bit sleeve. The limiting sleeve buckle is installed on the connector and then threadedly connected to the upper part of the drill bit sleeve. The bottom of the drill bit sleeve is threadedly connected to the grounding electrode connecting plate. A rectangular hole is machined in the middle of the drill bit sleeve.

[0008] The top of the cable connecting rod is rectangular to match the outline of the rectangular hole. An integrated cable is installed inside the cable connecting rod. The positive terminal of the integrated cable is connected to the high-voltage electrode, and the negative terminal of the integrated cable is connected to several grounding electrodes.

[0009] The insulating sleeve includes an inner insulating sleeve and an outer insulating sleeve. The inner insulating sleeve wraps around the outside of the cable connecting rod. The bottom of the inner insulating sleeve is provided with an intermediate joint that is threadedly connected to the cable connecting rod and the high-voltage electrode respectively. A spring is provided between the cable connecting rod and the high-voltage electrode.

[0010] Liquid inlets are machined on both sides of the rectangular hole, and a first liquid collection groove aligned with the liquid inlets is machined on the top of the grounding electrode connecting plate. Multiple first flow channels penetrating the grounding electrode connecting plate are uniformly machined in the first liquid collection groove.

[0011] The insulating outer sleeve is machined with a second liquid collection tank aligned with multiple first flow channels. Multiple second flow channels are machined on the second liquid collection tank, penetrating the insulating outer sleeve. The first and second flow channels constitute the internal flow path of the drilling fluid, and the drill bit body and wellbore constitute the external flow path of the drilling fluid. The internal and external flow paths constitute the circulation channel of the drilling fluid.

[0012] The lower outer wall of the insulating outer sleeve is uneven and wavy.

[0013] The strong magnetic source is a permanent magnet or an electromagnet. When the strong magnetic source is an electromagnet, the integrated cable is electrically connected to the electromagnet.

[0014] When the strong magnetic source is an electromagnet, the magnetic field strength generated is not less than the critical magnetic field adaptation value. The method for obtaining the critical magnetic field adaptation value is as follows: control the coil current to affect the magnetic field strength from zero to increase sequentially, and record the magnetic field strength under specific pulse peak parameters and the distance between the high voltage electrode and the ground electrode. Gradually increase the magnetic field strength, and when the volume of rock fragmentation increases by a certain value compared to the magnetic field strength without a magnetic source, the magnetic field strength value corresponding to the inflection point of significant increase appears.

[0015] The beneficial effects of the electrode drill bit for improving the rock-breaking efficiency of pulse discharge provided by this invention are: (1) By setting a strong magnetic source to control the plasma channel generated between the high voltage electrode and the ground electrode to extend into the rock, the discharge channel length and the initial damage range inside the rock are increased, thereby greatly improving the utilization rate of single pulse energy and the rock breaking volume, and improving the rock breaking efficiency. (2) Integrating the strong magnetic source inside the insulator will not change the overall size and external structure of the electrode drill bit, and it is easy to promote it on existing drilling equipment. (3) Using an electromagnet as a strong magnetic source, the magnetic field strength and direction can be changed in real time by adjusting the current, which is suitable for different rocks and working conditions, thus improving the applicability of the electrode drill bit. (4) The corrugated outer wall of the insulating outer tube helps to extend the surface creepage distance and improves the insulation reliability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a structural schematic diagram provided for an embodiment of the present invention.

[0018] Figure 2 This is a cross-sectional view of the shaft provided in an embodiment of the present invention.

[0019] Figure 3 for Figure 2 Cross-sectional view of line A-A in the middle.

[0020] Figure 4 for Figure 2 Cross-sectional view of line B-B in the middle.

[0021] Figure 5 This is a schematic diagram of the structure of the drill bit sleeve provided in an embodiment of the present invention.

[0022] Figure 6This is a schematic diagram of the structure of the grounding electrode connection plate provided in an embodiment of the present invention.

[0023] Figure 7 This is a schematic diagram of the cable connecting rod provided in an embodiment of the present invention.

[0024] Figure 8 This is a schematic diagram of the bottom outline of the insulating outer sleeve provided in an embodiment of the present invention.

[0025] Figure 9 This is a schematic diagram of the distribution structure of a strong magnetic source provided in an embodiment of the present invention.

[0026] Figure 10 This is a schematic diagram illustrating the working principle of the electrode drill bit provided in an embodiment of the present invention.

[0027] Figure 11 A schematic diagram illustrating the principle of the electrode drill bit provided in an embodiment of the present invention.

[0028] Figure 12 This is a schematic diagram illustrating the parameter changes during the three stages of electrical breakdown, as provided in an embodiment of the present invention.

[0029] Figure 13 Magnetic change simulation analysis provided for embodiments of the present invention Figure 1 .

[0030] Figure 14 Magnetic change simulation analysis provided for embodiments of the present invention Figure 2 .

[0031] Figure 15 Magnetic change simulation analysis provided for embodiments of the present invention Figure 3 .

[0032] The diagram shows the following markings: 1. Drill bit body; 11. Connector; 12. Limiting sleeve; 13. Drill bit sleeve; 131. Rectangular hole; 132. Liquid inlet; 14. Grounding electrode connecting plate; 141. First liquid collection tank; 142. First flow channel; 15. Support spring; 2. Cable connecting rod; 21. Integrated cable; 3. Insulating sleeve; 31. Insulating inner sleeve; 32. Insulating outer sleeve; 321. Second liquid collection tank; 322. Second flow channel; 4. High voltage electrode; 5. Grounding electrode; 6. Strong magnetic source. Detailed Implementation

[0033] like Figures 1-11 As shown, the electrode drill bit provided in this embodiment for improving the efficiency of pulsed discharge rock breaking includes a drill bit body 1, a cable connecting rod 2, an insulating sleeve 3, a high-voltage electrode 4, a grounding electrode 5, and a strong magnetic source 6.

[0034] like Figures 2-6As shown, the drill bit body 1 is hollow and includes, from top to bottom, a connector 11, a limiting cylinder 12, a drill bit sleeve 13, and a grounding electrode connecting plate 14. The connector 11 is threaded to the drill string. A support spring 15 is installed between the connector 11 and the drill bit sleeve 13 to buffer axial vibration. The limiting cylinder 12 is installed on the connector 11 and then threaded to the upper part of the drill bit sleeve 13. The bottom of the drill bit sleeve 13 is threaded to the grounding electrode connecting plate 14. A rectangular hole 131 is machined in the middle of the drill bit sleeve. Liquid inlets 132 are machined on both sides of the rectangular hole 131. A first liquid collecting groove 141 aligned with the liquid inlets 132 is machined on the top of the grounding electrode connecting plate 14. Six first flow channels 142 are uniformly machined in the first liquid collecting groove 141, penetrating the grounding electrode connecting plate 14. The liquid inlets 132, the first liquid collecting groove 141, and the first flow channels 142 are used for the flow of drilling fluid.

[0035] like Figure 2 , Figure 7 As shown, the cable connecting rod 2 is installed inside the drill bit sleeve 13 and the grounding electrode connecting plate 14 via the insulating sleeve 3. The bottom end of the cable connecting rod 2 extends below the grounding electrode connecting plate 14. The top of the cable connecting rod 2 is rectangular and fits the outline of the rectangular hole 131. An integrated cable 21 is installed inside the cable connecting rod 2. The positive terminal of the integrated cable 21 is connected to the high-voltage electrode 4. The negative terminal of the integrated cable 21 passes through the cable connecting rod 2, the insulating sleeve 3, and the grounding electrode connecting plate 14 and is connected to the four grounding electrodes 5 respectively. The integrated cable 21, which isolates the connection between the grounding electrode connecting plate 14 and the high-voltage electrode 4, is connected to the electric pulse generator. The insulating sleeve 3 is used to isolate the power conduction between the grounding electrode connecting plate 14 and the high-voltage electrode 4. The cable connecting rod 2 is installed inside the rectangular hole 131. On the one hand, it is used to prevent the cable connecting rod 2 from rotating and avoid the integrated cable 21 from being twisted. On the other hand, the cable connecting rod 2 can transmit part of the torque to the high-voltage electrode 4.

[0036] like Figure 2 , Figure 8 , Figure 9As shown, the high-voltage electrode 4 is located on the center line below the drill bit body 1. The high-voltage electrode 4 is connected to the bottom end of the cable connecting rod 2. Four grounding electrodes 5 are arranged in a ring array outside the high-voltage electrode 4, and the grounding electrodes 5 are fixedly connected to the grounding electrode connecting plate 14. The bottom end of the insulating sleeve 3 extends into the annular space between the high-voltage electrode 4 and the grounding electrode 5. The insulating sleeve 3 includes an insulating inner sleeve 31 and an insulating outer sleeve 32 threaded onto the insulating inner sleeve 31. The insulating inner sleeve 31 wraps around the outside of the cable connecting rod 2, and the bottom of the insulating inner sleeve 31 is provided with an intermediate joint that connects to the cable connecting rod 2. The cable connecting rod 2 is threadedly connected to the high-voltage electrode 4. A spring is provided between the cable connecting rod 2 and the high-voltage electrode 4 to further buffer axial vibration and prevent damage to the high-voltage electrode 4 and the cable connecting rod 2. The insulating outer sleeve 32 is machined with a second liquid collecting groove 321 aligned with eight first flow channels 142. Multiple second flow channels 322 penetrating the insulating outer sleeve 32 are machined on the second liquid collecting groove 321. The first flow channels 142 and the second flow channels 322 constitute the internal flow path of the drilling fluid, and the drill bit body 1 and the wellbore constitute the external flow path of the drilling fluid. The internal flow path and the external flow path constitute the circulation channel of the drilling fluid. The lower outer wall of the insulating outer sleeve 32 is uneven and wavy. The wavy insulating outer sleeve 32 can prolong the discharge plasma movement of the high-voltage electrode 4 and improve the reliability of the insulating sleeve 3.

[0037] like Figures 9-11 As shown, four strong magnetic sources 6 are arrayed and installed within an insulating sleeve 3 between the high-voltage electrode 4 and the grounding electrode 5. These sources generate a magnetic field during pulsed discharge to guide the plasma channel into the rock. The strong magnetic sources 6 are permanent magnets or electromagnets. When an electromagnet is used, it consists of a coil and a circular iron ring. Insulating wire is wound around the iron ring at a 45° angle, with each winding 45° apart, forming four uniformly distributed circular arrays of electromagnets. The insulating wire runs through the entire ring and is connected to a cable. The entire coil is encased in an insulating outer sleeve 32, almost touching the rock surface. The angle at which the coil is positioned within the insulating outer sleeve 32 depends on the grounding electrode 5. The grounding electrode 5 and the angle at which the coil is wound are staggered, ensuring that the electromagnetic force experienced by the plasma as it passes through the rock is always downward. An integrated cable 21 is electrically connected to the electromagnet. When the strong magnetic source 6 is an electromagnet, the magnetic field strength generated is not less than the critical magnetic field adaptation value. The method for obtaining the critical magnetic field adaptation value is as follows: control the coil current to affect the magnetic field strength from zero to increase sequentially, and record the magnetic field strength under specific pulse peak parameters and the distance between the high voltage electrode 4 and the ground electrode 5. Gradually increase the magnetic field strength, and when the volume of rock fragmentation increases by a certain value compared with the magnetic field strength without the magnetic source, the magnetic field strength value corresponding to the inflection point of significant increase appears.

[0038] The working principle of the electrode drill bit is as follows: Figure 11As shown, in the high-voltage electrode 4 and grounding electrode 5 of the electrode drill bit, a plasma growth region is formed in the rock from the top. The ends of the high-voltage electrode 4 and grounding electrode 5 are in contact with the tops of the plasma growth region on both sides, respectively. The rock, high-voltage electrode 4, and grounding electrode 5 are all located in the drilling fluid, which provides a liquid environment with a conductivity of less than 60 μS / m for rock breaking. Under the action of the electric field, the medium in the rock or liquid is broken down, forming a random, usually short plasma channel, accompanied by a violent electrohydraulic effect (similar to discharge in water) that generates a shock wave.

[0039] The method of using this invention is as follows: Before use, the electrode drill bit is connected to the drill string. Drilling fluid flows in through the inlet 132, the first flow channel 142, and the second flow channel 322, and flows out between the electrode drill bit and the drill string wall, forming a circulation. At the same time, the integrated cable 21 transmits an electric pulse between the high-voltage electrode 4 and the grounding electrode 5. The electric field direction is from the high-voltage electrode 4 to the grounding electrode 5. After the electromagnet is energized, it generates a magnetic field, the direction of which is designed to be approximately along the circumferential tangent direction (perpendicular to the plane) within the discharge area. According to the left-hand rule, regardless of the direction of the discharge current, the Lorentz force (F) on the plasma channel is always perpendicular to the interior of the rock, thereby guiding the plasma channel to develop downwards.

[0040] When using, such as Figure 12 As shown, the electric pulse generator provides an instantaneous pulse voltage with a rising edge of <500ns and a pulse voltage peak of Up; by adjusting the direction of the electric field and the magnetic field line of the strong magnetic source 6 between the high voltage electrode 4 and the ground electrode 5 through the pulse voltage, an electromagnetic force along the direction of the rock interior exists in the plasma growth area; increasing the magnetic field strength generated by the strong magnetic source 6 changes the growth path of the plasma channel in the rock and liquid medium during the electric pulse rock breaking and electrical breakdown process, and increases the overall plasma channel length.

[0041] The electric field lines point from the high-voltage electrode 4 to the grounding electrode 5. The magnetic force in the magnetic field follows the left-hand rule. The direction of the magnetic field lines is perpendicular to the direction of plasma movement. When the plasma moves to the left from the high-voltage electrode 4 to the grounding electrode 5, the direction of the magnetic field lines inside the rock passes through the palm of the left hand from the inside out. The electric field of the four fingers is from high to low, and the electromagnetic force is in the direction of the thumb. At this time, the electromagnetic force points downwards into the rock. When the plasma moves to the right from the high-voltage electrode 4 to the grounding electrode 5, the direction of the magnetic field lines inside the rock points from the south (S) pole of the previous electromagnet to the north (N) pole of the next electromagnet. The direction of the magnetic field lines inside the rock passes through the palm of the left hand from the outside in. The electric field of the four fingers is from high to low, and the electromagnetic force is in the direction of the thumb. At this time, the electromagnetic force still points downwards into the rock.

[0042] The entire discharge process consists of three stages: pre-breakdown, breakdown, and arc / explosion. The duration of the magnetic field should at least cover the period from the initial voltage rise to the complete opening of the plasma channel and the peak current. p This is the rising peak voltage, which is positively correlated with the capacitor charging voltage; U i I is the initial voltage of the channel. i I is the initial current of the channel; p t represents the peak current of the channel. bd The breakdown time delay is the sum of the pre-breakdown and breakdown times, and the magnetic field strength must be greater than or equal to a specific parameter. The greater the longitudinal penetration depth of the plasma channel within the rock, the larger the initial damage area inside the rock; the longer the plasma channel inside the liquid medium, the higher the impedance. According to Joule's law, when the same large current passes through, higher impedance leads to more energy deposition in the channel. The combined effect of the initial damage area inside the rock and the electrohydraulic impact force acting on the rock surface ultimately improves the efficiency of the electric pulse rock breaking.

[0043] Example 2

[0044] Let the width of the plasma growth region be Ls, i.e., the distance between the high-voltage electrode 4 and the ground electrode 5 be Ls, the longitudinal depth of the plasma growth region be 0.5Ls, and the thickness of the plasma growth region be 0.5Ls; the distance between the strong magnetic source 6 and the high-voltage electrode 4 be Lc, and the vertical distance between the strong magnetic source 6 and the end connection of the high-voltage electrode 4 and the ground electrode 5 be hc; change the spatial position of the strong magnetic source 6 (the longitudinal distance of the strong magnetic source 6 and the lateral distance of the strong magnetic source 6) or the direction of the magnetic field lines of the strong magnetic source 6 to achieve the direction control and adjustment of the electric pulse rock breaking.

[0045] When the longitudinal distance hc of the strong magnetic source 6 remains constant, the closer the strong magnetic source 6 is to the high voltage electrode 4, the more the rock-breaking direction of the electric pulse deviates towards the high voltage electrode 4, and the greater the degree of deviation of the rock-breaking direction of the electric pulse towards the high voltage electrode 4; conversely, when the lateral distance lc of the strong magnetic source 6 is greater than Ls / 2, the closer the strong magnetic source 6 is to the grounding electrode 5, the more the rock-breaking direction of the electric pulse deviates towards the grounding electrode 5, and the greater the degree of deviation of the rock-breaking direction of the electric pulse towards the grounding electrode 5.

[0046] In this embodiment, through experimental simulation, the width Ls of the plasma growth region is set to 28 mm, and the longitudinal depth and thickness of the plasma growth region are both 10 mm. Ignoring the size of the strong magnetic source 6, it is assumed that the strong magnetic source 6 is a point, and the intensity B of the strong magnetic source 6 is 5 T. Figure 13 As shown, lc = 5 mm, hc takes the values ​​of 2 mm, 5 mm, 10 mm, 15 mm, and 20 mm. The electrical pulse rock-breaking efficiency is best when hc = 2 mm. Figure 14As shown, lc = 10 mm, and values ​​of 2 mm, 5 mm, 10 mm, 15 mm, and 20 mm are taken. The best improvement in electric pulse rock-breaking efficiency is achieved when hc = 2 mm. Figure 15 As shown, lc = 15 mm, hc takes the values ​​of 2 mm, 5 mm, 10 mm, 15 mm, and 20 mm. When hc = 2 mm, the efficiency of electric pulse rock breaking is the best. Therefore, it can be seen that the closer the strong magnetic source 6 is to the top surface of the plasma growth area, the better its electric pulse rock breaking efficiency.

[0047] Simulation results show that when the lateral distance lc of the strong magnetic source 6 is hc / 2, the longitudinal distance hc of the strong magnetic source 6 is closer to 0, the efficiency of electric pulse rock breaking is the best, and the direction of electric pulse rock breaking is the best away from the rock surface.

[0048] In summary, considering all factors, hc=2mm is the best for rock breaking effect. The lateral distance should be adjusted according to the direction of rock breaking. In the electrode drill bit, the lateral distance lc=14mm, which is on the center line between the high-voltage electrode 4 and the grounding electrode 5.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications and substitutions based on the technical solutions and inventive concepts provided by the present invention should be covered within the scope of protection of the present invention.

Claims

1. An electrode drill bit for improving the efficiency of pulsed discharge rock breaking, characterized in that: The system includes a drill bit body (1), a cable connecting rod (2), an insulating sleeve (3), a high-voltage electrode (4), a grounding electrode (5), and a strong magnetic source (6). The drill bit body (1) is hollow and includes, from top to bottom, a connector (11), a limiting sleeve (12), a drill bit sleeve (13), and a grounding electrode connecting plate (14). The cable connecting rod (2) is installed inside the drill bit sleeve (13) and the grounding electrode connecting plate (14) through the insulating sleeve (3). The bottom end of the cable connecting rod (2) extends below the grounding electrode connecting plate (14). The high-voltage electrode (4)... Located on the center line below the drill bit body (1), the high voltage electrode (4) is connected to the bottom end of the cable connecting rod (2), and several grounding electrodes (5) are arranged in a ring array outside the high voltage electrode (4), and the grounding electrodes (5) are fixedly connected to the grounding electrode connecting plate (14). The bottom end of the insulating sleeve (3) extends into the annular space between the high voltage electrode (4) and the grounding electrode (5). At least one strong magnetic source (6) array is installed in the insulating sleeve (3) between the high voltage electrode (4) and the grounding electrode (5) to generate a magnetic field that guides the plasma channel to extend into the rock during pulse discharge.

2. The electrode drill bit for improving the efficiency of pulsed discharge rock breaking according to claim 1, characterized in that: A support spring (15) is installed between the connector (11) and the drill bit sleeve (13). The limiting sleeve (12) is installed on the connector (11) and then threadedly connected to the upper part of the drill bit sleeve (13). The bottom of the drill bit sleeve (13) is threadedly connected to the grounding electrode connecting plate (14). A rectangular hole (131) is machined in the middle of the drill bit sleeve.

3. The electrode drill bit for improving the efficiency of pulsed discharge rock breaking according to claim 1 or 2, characterized in that: The top of the cable connecting rod (2) is rectangular and fits the outline of the rectangular hole (131). An integrated cable (21) is installed inside the cable connecting rod (2). The positive terminal of the integrated cable (21) is connected to the high voltage electrode (4), and the negative terminal of the integrated cable (21) is connected to several grounding electrodes (5).

4. The electrode drill bit for improving the efficiency of pulsed discharge rock breaking according to claim 3, characterized in that: The insulating sleeve (3) includes an insulating inner sleeve (31) and an insulating outer sleeve (32). The insulating inner sleeve (31) wraps around the outside of the cable connecting rod (2). The bottom of the insulating inner sleeve (31) is provided with an intermediate joint that is threadedly connected to the cable connecting rod (2) and the high voltage electrode (4) respectively. A spring is provided between the cable connecting rod (2) and the high voltage electrode (4).

5. The electrode drill bit for improving the efficiency of pulsed discharge rock breaking according to claim 4, characterized in that: The rectangular hole (131) has liquid inlets (132) on both sides, and the grounding electrode connecting plate (14) has a first liquid collection groove (141) aligned with the liquid inlets (132) on the top. Multiple first flow channels (142) that penetrate the grounding electrode connecting plate (14) are uniformly processed in the first liquid collection groove (141).

6. The electrode drill bit for improving the efficiency of pulsed discharge rock breaking according to claim 5, characterized in that: The insulating outer sleeve (32) is machined with a second liquid collection tank (321) aligned with multiple first flow channels (142). Multiple second flow channels (322) penetrating the insulating outer sleeve (32) are machined on the second liquid collection tank (321). The first flow channels (142) and the second flow channels (322) constitute the internal flow path of the drilling fluid. The drill bit body (1) and the wellbore constitute the external flow path of the drilling fluid. The internal flow path and the external flow path constitute the circulation channel of the drilling fluid.

7. The electrode drill bit for improving the efficiency of pulsed discharge rock breaking according to claim 4, characterized in that: The lower outer wall of the insulating outer sleeve (32) is uneven and wavy.

8. The electrode drill bit for improving the efficiency of pulsed discharge rock breaking according to claim 1, characterized in that: The strong magnetic source (6) is a permanent magnet or an electromagnet. When the strong magnetic source (6) is an electromagnet, the integrated cable (21) is electrically connected to the electromagnet.

9. The electrode drill bit for improving the efficiency of pulsed discharge rock breaking according to claim 8, characterized in that: When the strong magnetic source (6) is an electromagnet, the magnetic field strength generated is not less than the critical magnetic field adaptation value. The method for obtaining the critical magnetic field adaptation value is: control the coil current to affect the magnetic field strength from zero to increase sequentially, and record the magnetic field strength gradually under specific pulse peak parameters and the distance between the high voltage electrode (4) and the ground electrode (5). When the volume of rock fragmentation increases by a certain value compared to the magnetic field strength without a magnetic source, the magnetic field strength value corresponding to the inflection point of significant increase appears.

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