Coaxial push rod capable of transmitting large current and connecting method thereof

Abstract

The invention discloses a coaxial push rod capable of transmitting large current and a connecting method thereof. A shell butt joint male head and a shell butt joint female head are arranged at the two ends of a shell of the push rod; the insulating sleeve is coaxially installed in the shell, and the two ends of the insulating sleeve are provided with an insulating butt joint male head and an insulating butt joint female head. The core tube is coaxially installed in the insulating sleeve, the small connector and the male needle are arranged at the two ends of the core tube respectively, and the end of the small connector is connected to one end of the female needle. An inclined ring spring is arranged on the outer wall of the male needle or the inner wall of the female needle, and the inclined ring spring is installed in an outer annular groove in the outer wall of the male needle or an inner annular groove in the inner wall of the female needle. The inclined ring spring is compressed under the action of the inner wall of the female pin and the bottom surface of the annular groove body, so that the inclined ring spring is tightly abutted against the inner wall of the female pin and the bottom surface of the annular groove body, and the female pin is electrically connected with the male pin. The problem that in the prior art, two pushing rods are connected through two times of threaded connection of an inner conductor and a drill rod body, and the connecting efficiency is low is solved.

Description

Technical Field

[0001] The present application belongs to the field of shock wave technology, and specifically relates to a coaxial propulsion rod capable of transmitting large current and a connection method thereof. Background Art

[0002] Coal mine gas control requires continuous improvement of reservoir permeability. Dynamic measures such as deep hole pre-cracking loosening blasting and carbon dioxide fracturing are prone to cause safety problems in drilling and tunnels due to the huge energy released in a single time. In recent years, shock wave generation technologies represented by liquid-electric effect, metal wire electric explosion, and metal wire electric explosion driven energetic mixture require water injection into the borehole during coal seam permeability enhancement operations. However, soft and structural coal seams are not only difficult to drill holes, but water injection will also cause hole collapse. For coal seams that are not suitable for water injection during drilling and permeability enhancement operations, it is advisable to use operating equipment that does not require direct water injection into the coal seam and can generate shock waves. Such operating equipment requires a thrust rod that is compatible with coal seam drilling and can transmit large pulse currents.

[0003] The patent "A coaxial propulsion rod for transmitting large current" (publication number: CN214424434U) discloses that when the propulsion rod is in use, the inner conductors of the two propulsion rods are connected by the inner and outer thread structures at the ends, thereby reducing the contact resistance between the inner conductors of the two propulsion rods, improving the connection reliability between the inner conductors, and greatly improving the current transmission capacity. When the two propulsion rods are connected, the two inner conductors are connected by threads, and the two drill rod bodies are also connected by threads. The two threaded connections reduce the connection efficiency of the two propulsion rods. In actual use, more than two propulsion rods are usually used, which will lead to the problem of reduced shock wave operation efficiency. Summary of the invention

[0004] The embodiment of the present application solves the problem of low connection efficiency in the prior art that the connection between two propulsion rods requires two threaded connections between the inner conductor and the drill rod body, by providing a coaxial propulsion rod capable of transmitting large current and a connection method thereof.

[0005] In order to achieve the above-mentioned object, an embodiment of the present invention provides a coaxial propulsion rod capable of transmitting large current, comprising a housing, an insulating sleeve and a core tube;

[0006] The shell is a cylindrical structure with openings at both ends, and a shell docking male connector and a shell docking female connector are respectively provided at both ends of the shell;

[0007] The insulating sleeve is coaxially installed in the shell, and both ends of the insulating sleeve are respectively provided with an insulating butt joint male connector and an insulating butt joint female connector;

[0008] The core tube is coaxially installed in the insulating sleeve, and a small joint and a male needle are respectively provided at both ends of the core tube, and the small joint and the male needle are both electrically connected to the inner conductor in the core tube, and the end of the small joint is connected to one end of the female needle;

[0009] The outer wall of the male needle or the inner wall of the female needle is provided with a bevel coil spring, and the bevel coil spring is installed in the outer annular groove body of the outer wall of the male needle or in the inner annular groove body of the inner wall of the female needle.

[0010] In a possible implementation, a plurality of the outer annular grooves are arranged at intervals on the outer wall of the male needle, a bevel coil spring is sleeved in the outer annular groove, and the inner wall of the female needle is arranged to be smooth.

[0011] In a possible implementation, the male needle includes a connected docking section and a threaded section, the threaded section is threadedly connected to the threaded hole at the end of the core tube, a washer is mounted on the threaded section, and both ends of the washer are respectively abutted against one end face of the docking section and the end face of the core tube.

[0012] In a possible implementation, a threaded hole is provided at the connecting end of the small joint, the threaded section at the end of the core tube is threadedly connected to the threaded hole of the small joint, and the connecting end of the small joint abuts against the step surface of the outer wall of the core tube and the step surface of the inner wall of the insulating sleeve.

[0013] In one possible implementation, the threaded section of the butt end of the small connector is threadedly connected to the threaded hole at the end of the female needle, the inner wall of the female needle is provided with a step, and the butterfly spring is clamped between the step surface of the inner wall of the female needle and the end face of the butt end of the small connector.

[0014] In a possible implementation, the bottom surface of the annular groove body includes two inclined surfaces, the two inclined surfaces are symmetrically arranged to form a V-shaped structure, and the two inclined surfaces are inclined downward toward the center of the annular groove body.

[0015] In a possible implementation, the insulating sleeve is coaxially installed in the shell through a support ring, the support ring is arranged between the insulating sleeve and the shell, and a gasket is provided on one side of the support ring located at the insulating docking male head, and the structure of the gasket is adapted to the structure of the support ring.

[0016] The embodiment of the present invention further provides a method for connecting a coaxial propulsion rod capable of transmitting a large current, using the above-mentioned coaxial propulsion rod capable of transmitting a large current, comprising the following steps:

[0017] When two propulsion rods are butt-jointed, one of the propulsion rods is fixed, and then the other propulsion rod is rotated so that the outer shell butt joint male heads and the outer shell butt joint female heads of the two propulsion rods are threadedly connected;

[0018] When the shell docking male connector and the shell docking female connector are gradually connected, the insulated docking male connector is gradually inserted into the insulated docking female connector, and the male pin is gradually inserted into the female pin;

[0019] After the shell docking male heads and the shell docking female heads of the two propulsion rods are threadedly connected in place, the insulated docking male heads and the insulated docking female heads are plugged in place, and the male pins and the female pins are plugged in place;

[0020] At this time, the bevel coil spring is compressed under the action of the inner wall of the female pin and the bottom surface of the annular groove, so that the bevel coil spring is tightly abutted against the inner wall of the female pin and the bottom surface of the annular groove, realizing the electrical connection between the female pin and the male pin.

[0021] In a possible implementation, the bevel coil spring is compressed under the action of the inner wall of the female needle and the bottom surface of the annular groove body, so that the bevel coil spring abuts against both side walls and two inclined surfaces of the annular groove body.

[0022] In a possible implementation, after the male and female shell docking heads of the two push rods are threadedly connected in place, the end of the male needle abuts against the butterfly spring, so that the male needle and the small connector are electrically connected through the butterfly spring.

[0023] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0024] The embodiment of the present invention provides a coaxial push rod capable of transmitting large current and a connection method thereof. The present invention can achieve the docking and electrical connection of the two push rods during the process of threaded connection between the outer shell docking male head and the outer shell docking female head, so the installation efficiency is high, avoiding the problem of complicated operation and low installation efficiency in the prior art that the inner conductor needs to be connected first, and then the two push rods can be docked. When the two push rods are connected, the bevel coil spring abuts against the two side walls and two inclined surfaces of the annular groove body, which can increase the contact area between the bevel coil spring and the male needle, thereby improving the electrical connection effect. The electrical connection effect can be further improved by providing a butterfly spring. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A schematic structural diagram of a coaxial propulsion rod capable of transmitting large current provided in an embodiment of the present invention.

[0027] Figure 2A schematic diagram of the structure of a male needle provided in an embodiment of the present invention.

[0028] Figure markings: 1-shell; 2-shell docking male head; 3-shell docking female head; 4-insulating sleeve; 41-insulating docking male head; 42-insulating docking female head; 43-external step; 44-internal step; 45-first sleeve; 46-second sleeve; 5-core tube; 6-small connector; 7-male needle; 71-annular groove; 72-docking section; 73-threaded section; 8-inner conductor; 9-female needle; 10-bevel coil spring; 11-water passage; 12-male end cap; 13-female end cap; 14-bushing; 15-large sealing ring; 16-small sealing ring; 17-washer; 18-butterfly spring; 19-support ring; 20-washer ring; 21-elastic retaining ring. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the description of the embodiments of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present invention. The terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances.

[0031] like Figure 1 and Figure 2 As shown, the coaxial propulsion rod capable of transmitting large current and the connection method thereof provided by the embodiment of the present invention include a shell 1, an insulating sleeve 4 and a core tube 5.

[0032] The shell 1 is a cylindrical structure with two ends opened, and a shell docking male connector 2 and a shell docking female connector 3 are respectively provided at the two ends of the shell 1.

[0033] The insulating sleeve 4 is coaxially installed in the housing 1 , and an insulating butt joint male connector 41 and an insulating butt joint female connector 42 are respectively provided at two ends of the insulating sleeve 4 .

[0034] The core tube 5 is coaxially installed in the insulating sleeve 4, and a small connector 6 and a male needle 7 are respectively provided at both ends of the core tube 5. The small connector 6 and the male needle 7 are both electrically connected to the inner conductor 8 in the core tube 5, and the end of the small connector 6 is connected to one end of the female needle 9.

[0035] The outer wall of the male needle 7 or the inner wall of the female needle 9 is provided with a bevel coil spring 10 , which is installed in the outer annular groove body 71 of the outer wall of the male needle 7 or in the inner annular groove body of the inner wall of the female needle 9 .

[0036] In this embodiment, a plurality of outer annular grooves 71 are arranged at intervals on the outer wall of the male needle 7, and a bevel coil spring 10 is sleeved inside the outer annular groove 71, and the inner wall of the female needle 9 is arranged to be smooth.

[0037] It should be noted that a technical solution may also be adopted in which a plurality of inner annular grooves are arranged at intervals on the inner wall of the female needle 9 and the canted coil spring 10 is arranged in the inner annular grooves.

[0038] It should be noted that the insulating sleeve 4 is made of insulating material. The water passage 11 allows water to flow through, so that the water can be transported to the shock wave generator by the propulsion rod to generate shock waves. Two or more propulsion rods are connected into one, thereby extending the length of the propulsion rod, making it convenient to push the shock wave generator in the borehole.

[0039] The outer wall of the shell docking male head 2 is provided with a tapered thread, and the inner wall of the shell docking female head 3 is provided with a tapered thread. The shell docking male head 2 and the shell docking female head 3 cooperate with each other through the tapered thread, and can achieve a tighter fit during the process of gradually tightening the shell docking male head 2 and the shell docking female head 3, so that a good electrical connection effect can be achieved between the shell docking male head 2 and the shell docking female head 3. The end of the shell docking male head 2 is provided with a female end cap 13, and the female end cap 13 can be detachably installed through the tapered thread of the outer wall of the shell docking male head 2. The end of the shell docking female head 3 is provided with a male end cap 12, and the male end cap 12 can be detachably installed through the tapered thread of the inner wall of the shell docking female head 3. The female end cap 13 and the male end cap 12 can protect the shell docking male head 2 and the shell docking female head 3 of the push rod when the push rod is not in use, and prevent the shell docking male head 2 and the shell docking female head 3 from being damaged or contaminated by collision.

[0040] In this embodiment, a bushing 14 is sleeved on the shell-jointed male connector 2, and the two ends of the bushing 14 are respectively in contact with the end of the female end cap 13 and the stepped surface of the shell-jointed male connector 2. The bushing 14 is used to protect the external thread section 73 of the shell-jointed male connector 2, so there is no need to screw the female end cap 13 into more threads, thereby facilitating the disassembly and assembly of the female end cap 13.

[0041] In this embodiment, the insulating sleeve 4 is coaxially installed in the shell 1 through the support ring 19, and the support ring 19 is sleeved between the insulating sleeve 4 and the shell 1. The support ring 19 is located on one side of the insulating docking male head 41 and is provided with a gasket 20. The structure of the gasket 20 is adapted to the structure of the support ring 19.

[0042] It should be noted that a support ring 19 is provided inside the housing joint male connector 2 and the housing joint female connector 3. A water passage 11 is formed between the outer wall of the insulating sleeve 4 and the inner wall of the housing 1. The support ring 19 includes two cylindrical ring bodies, an annular passage is formed between the two cylindrical ring bodies, and the two ring bodies are connected by a connecting rod. The gasket 20 is used to improve the matching accuracy of the end face of the support ring 19.

[0043] In this embodiment, an elastic retaining ring 21 is installed on the outer wall of the insulating butt male connector 41 , and two ends of the gasket 20 are respectively in contact with the support ring 19 and the elastic retaining ring 21 .

[0044] In this embodiment, the outer wall of the insulating butt joint female connector 42 is provided with an external step 43, and the step surface of the external step 43 abuts against the end surface of the support ring 19. The inner wall of the insulating butt joint female connector 42 is provided with an internal step 44, and the step surface of the internal step 44 is used to abut against the end surface of the insulating butt joint male connector 41 of the next push rod. By providing the external step 43 and the internal step 44 of the insulating butt joint female connector 42, a better matching effect can be achieved after the push rod is assembled, which improves the sealing inside the push rod on the one hand, and makes the components firmly abut and not easy to loosen on the other hand.

[0045] In this embodiment, the outer wall of the insulating butt joint male connector 41 is provided with a plurality of large sealing rings 15 that match the inner wall of the insulating butt joint female connector 42, and the plurality of large sealing rings 15 are respectively installed in a plurality of grooves on the outer wall of the insulating butt joint male connector 41. The large sealing rings 15 can improve the sealing between the insulating butt joint male connector 41 and the insulating butt joint female connector 42, and prevent water from entering the female pin 9. The plurality of large sealing rings 15 have a better sealing effect.

[0046] In this embodiment, the insulating sleeve 4 includes a first sleeve body 45 and a second sleeve body 46 connected to each other, the end outer wall of the first sleeve body 45 is provided with a first step, the end inner wall of the second sleeve body 46 is provided with a second step matched with the first step, and a small sealing ring 16 is provided between the first step and the second step. There are multiple first steps and second steps, and the area matched with multiple first steps and second steps is larger, so it has better sealing. The small sealing ring 16 can further improve the sealing between the first sleeve body 45 and the second sleeve body 46. The insulating sleeve 4 includes the first sleeve body 45 and the second sleeve body 46 connected to each other, so it is convenient to install the core tube 5, and avoid the problem that the insulating sleeve 4 takes a long time to install due to the long length of the core tube 5.

[0047] In this embodiment, the shell docking female connector 3, the insulating docking male connector 41 and the male pin 7 are located on the same side of the housing 1. The shell docking female connector 3, the insulating docking male connector 41 and the male pin 7 partially overlap in the width direction of the push rod, thereby facilitating the assembly of the push rod body.

[0048] In this embodiment, the male needle 7 includes a connected docking section 72 and a threaded section 73, the threaded section 73 is threadedly connected to the threaded hole at the end of the core tube 5, and a gasket 17 is mounted on the threaded section 73. The two ends of the gasket 17 are respectively abutted against one end face of the docking section 72 and the end face of the core tube 5.

[0049] It should be noted that the washer 17 also abuts against the step surface of the inner wall of the insulating sleeve 4, so as to achieve a close fit. The male needle 7 and the core tube 5 are connected by threads for easy disassembly and assembly.

[0050] In this embodiment, a threaded hole is provided at the connecting end of the small joint 6, and the threaded section at the end of the core tube 5 is threadedly connected to the threaded hole of the small joint 6, and the connecting end of the small joint 6 abuts against the step surface of the outer wall of the core tube 5 and the step surface of the inner wall of the insulating sleeve 4.

[0051] It should be noted that the connecting end of the small joint 6 abuts against the step surface of the outer wall of the core tube 5 and the step surface of the inner wall of the insulating sleeve 4, thereby achieving a close fit.

[0052] In this embodiment, the threaded section of the butt end of the small connector 6 is threadedly connected to the threaded hole at the end of the female needle 9, and a step is provided on the inner wall of the female needle 9. The butterfly spring 18 is clamped between the step surface of the inner wall of the female needle 9 and the end face of the butt end of the small connector 6.

[0053] It should be noted that the inner wall of the female needle 9 is provided with a step, which is used to clamp the circumference of the butterfly spring 18 to achieve the installation of the butterfly spring 18. In this state, the butterfly spring 18 can be compressed.

[0054] In the first embodiment, the bottom surface of the outer annular groove body 71 includes two inclined surfaces, which are symmetrically arranged to form a V-shaped structure, and the two inclined surfaces are arranged to be inclined downward toward the center of the outer annular groove body 71 .

[0055] It should be noted that the angle between the two inclined surfaces is 150 degrees. The two inclined surfaces can increase the contact point between the helical coil spring 10 and the male needle 7, thereby increasing the contact area, thereby increasing the conduction current under a certain axial force.

[0056] In the second embodiment, the bottom surface of the outer annular groove 71 is an arc surface, and the curvature of the arc surface is consistent with the curvature of the compressed bevel coil spring 10, thereby increasing the contact area between the bevel coil spring 10 and the male needle 7, thereby increasing the conduction current.

[0057] In the third embodiment, the surface of the male pin 7 and the female pin 9 that match is a conical surface, and the angle of the conical surface is about 5°, so that after the male pin 7 and the female pin 9 are plugged into place, the height of the compressed helical coil spring 10 is smaller. According to Anker's law, such a matching form has a higher current flow capacity. By setting the conical surface, it is also possible to have a smaller friction force when the male pin 7 and the female pin 9 begin to dock.

[0058] It should be noted that the elastic retaining ring 21 prevents the backing ring 20 from loosening.

[0059] like Figure 1 and Figure 2 As shown, a method for connecting a coaxial propulsion rod capable of transmitting a large current provided by an embodiment of the present invention adopts the above-mentioned coaxial propulsion rod capable of transmitting a large current, and includes the following steps:

[0060] When two propulsion rods are butt-jointed, one of the propulsion rods is fixed, and then the other propulsion rod is rotated, so that the outer shell butt joint male head 2 and the outer shell butt joint female head 3 of the two propulsion rods are threadedly connected.

[0061] When the shell docking male connector 2 and the shell docking female connector 3 are gradually connected, the insulating docking male connector 41 is gradually inserted into the insulating docking female connector 42 , and the male pin 7 is gradually inserted into the female pin 9 .

[0062] After the shell docking male head 2 and the shell docking female head 3 of the two propulsion rods are threadedly connected in place, the insulating docking male head 41 and the insulating docking female head 42 are plugged into place, and the male pin 7 and the female pin 9 are plugged into place.

[0063] At this time, the bevel coil spring 10 is compressed under the action of the inner wall of the female needle 9 and the bottom surface of the outer annular groove body 71, so that the bevel coil spring 10 is tightly abutted against the inner wall of the female needle 9 and the bottom surface of the outer annular groove body 71, realizing the electrical connection between the female needle 9 and the male needle 7.

[0064] It should be noted that the bevel coil spring 10 is also called a finger spring. The basic parameters of the bevel coil spring 10 in this embodiment are: wire diameter 0.3mm, coil diameter 2.4mm, bevel coil spring 10 includes 20 to 50 spring coils, heavy BOLI spring is used for bevel coil spring 10, and the static pressure is 20N at a phase angle of 22°. The flow requirement of the bevel coil spring 10 is: 2kA / cm 2 The requirement is 10N, and by linear extrapolation, 20N can reach 4kA / cm 2 requirements.

[0065] The contact width between the spring coil and the male pin 7 and the female pin 9 after compression is calculated as 0.15mm, and the contact length between the spring coil and the male pin 7 and the female pin 9 after compression is calculated as 3mm. The contact area of ​​a single 50-turn helical coil spring 10 is 22.5mm 2 The contact area of ​​20 helical coil springs 10 is about 4.6 cm 2, can pass 18.4kA.

[0066] In the process of threaded connection between the outer shell docking male head 2 and the outer shell docking female head 3, the present invention can realize the docking and electrical connection of the two push rods, so the installation efficiency is high, avoiding the problem of complicated operation and low installation efficiency in the prior art that the inner conductor 8 needs to be connected first and then the two push rods can be docked.

[0067] In this embodiment, the bevel coil spring 10 is compressed under the action of the inner wall of the female needle 9 and the bottom surface of the outer annular groove body 71 , so that the bevel coil spring 10 abuts against both side walls and two inclined surfaces of the outer annular groove body 71 .

[0068] It should be noted that the bevel coil spring 10 abuts against both side walls and two inclined surfaces of the outer annular groove body 71, which can increase the contact area between the bevel coil spring 10 and the male needle 7, thereby improving the electrical connection effect.

[0069] In this embodiment, after the outer shell docking male head 2 and the outer shell docking female head 3 of the two push rods are threaded into place, the end of the male needle 7 abuts against the butterfly spring 18, so that the male needle 7 and the small connector 6 are electrically connected through the butterfly spring 18.

[0070] It should be noted that the electrical connection effect can be further improved by providing the disc spring 18 .

[0071] In this embodiment, it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and therefore it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A coaxial propulsion rod capable of transmitting large current, characterized in that: It comprises a shell (1), an insulating sleeve (4) and a core tube (5); The shell (1) is a cylindrical structure with openings at both ends, and a shell docking male connector (2) and a shell docking female connector (3) are respectively provided at the two ends of the shell (1); The insulating sleeve (4) is coaxially installed in the housing (1), and an insulating butt joint male connector (41) and an insulating butt joint female connector (42) are respectively provided at two ends of the insulating sleeve (4); The core tube (5) is coaxially installed in the insulating sleeve (4), and a small joint (6) and a male needle (7) are respectively provided at two ends of the core tube (5), and the small joint (6) and the male needle (7) are both electrically connected to the inner conductor (8) in the core tube (5), and the end of the small joint (6) is connected to one end of the female needle (9); The outer wall of the male needle (7) or the inner wall of the female needle (9) is provided with a bevel coil spring (10), and the bevel coil spring (10) is installed in an outer annular groove body (71) on the outer wall of the male needle (7) or in an inner annular groove body on the inner wall of the female needle (9).

2. The coaxial propulsion rod capable of transmitting large current according to claim 1, characterized in that: The outer wall of the male needle (7) is provided with a plurality of outer annular grooves (71) at intervals, and a helical coil spring (10) is sleeved inside the outer annular groove (71). The inner wall of the female needle (9) is smoothly arranged.

3. The coaxial propulsion rod capable of transmitting large current according to claim 1, characterized in that: The male needle (7) comprises a connected docking section (72) and a threaded section (73); the threaded section (73) is threadedly connected to the threaded hole at the end of the core tube (5); a washer (17) is mounted on the threaded section (73); two ends of the washer (17) are respectively in contact with an end face of one end of the docking section (72) and an end face of the core tube (5).

4. The coaxial propulsion rod capable of transmitting large current according to claim 1, characterized in that: The connecting end of the small joint (6) is provided with a threaded hole, the threaded section at the end of the core tube (5) is threadedly connected to the threaded hole of the small joint (6), and the connecting end of the small joint (6) abuts against the step surface of the outer wall of the core tube (5) and the step surface of the inner wall of the insulating sleeve (4).

5. The coaxial propulsion rod capable of transmitting large current according to claim 4, characterized in that: The threaded section of the butt end of the small connector (6) is threadedly connected to the threaded hole at the end of the female needle (9), the inner wall of the female needle (9) is provided with a step, and the butterfly spring (18) is clamped between the step surface of the inner wall of the female needle (9) and the end face of the butt end of the small connector (6).

6. The coaxial propulsion rod capable of transmitting large current according to claim 2, characterized in that: The bottom surface of the outer annular groove body (71) comprises two inclined surfaces, the two inclined surfaces are symmetrically arranged to form a V-shaped structure, and the two inclined surfaces are arranged to be inclined downward toward the center of the outer annular groove body (71).

7. The coaxial propulsion rod capable of transmitting large current according to claim 1, characterized in that: The insulating sleeve (4) is coaxially installed in the shell (1) via a support ring (19); the support ring (19) is sleeved between the insulating sleeve (4) and the shell (1); a gasket (20) is provided on one side of the support ring (19) located at the insulating butt joint male connector (41); the structure of the gasket (20) is adapted to the structure of the support ring (19).

8. A method for connecting a coaxial propulsion rod capable of transmitting large current, characterized in that: The coaxial propulsion rod capable of transmitting large current as claimed in any one of claims 2 to 7 comprises the following steps: When the two propulsion rods are butt-jointed, one of the propulsion rods is fixed, and then the other propulsion rod is rotated, so that the outer shell butt joint male heads (2) and the outer shell butt joint female heads (3) of the two propulsion rods are threadedly connected; When the shell docking male connector (2) and the shell docking female connector (3) are gradually connected, the insulating docking male connector (41) is gradually inserted into the insulating docking female connector (42), and the male pin (7) is gradually inserted into the female pin (9); After the shell docking male heads (2) and the shell docking female heads (3) of the two propulsion rods are threadedly connected in place, the insulating docking male heads (41) and the insulating docking female heads (42) are plugged in place, and the male pin (7) and the female pin (9) are plugged in place; At this time, the bevel coil spring (10) is compressed under the action of the inner wall of the female needle (9) and the bottom surface of the outer annular groove body (71), so that the bevel coil spring (10) is tightly abutted against the inner wall of the female needle (9) and the bottom surface of the outer annular groove body (71), thereby realizing the electrical connection between the female needle (9) and the male needle (7).

9. The method for connecting a coaxial propulsion rod capable of transmitting a large current according to claim 8, characterized in that: The bevel coil spring (10) is compressed under the action of the inner wall of the female needle (9) and the bottom surface of the outer annular groove body (71), so that the bevel coil spring (10) abuts against both side walls and two inclined surfaces of the outer annular groove body (71).

10. The method for connecting a coaxial propulsion rod capable of transmitting a large current according to claim 8, characterized in that: After the shell docking male heads (2) and the shell docking female heads (3) of the two propulsion rods are threadedly connected in place, the end of the male needle (7) abuts against the butterfly spring (18), so that the male needle (7) and the small connector (6) are electrically connected through the butterfly spring (18).

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