Elastic self-driven pressure-maintaining coring tool
By designing a self-propelled elastic pressure-holding coring tool, the automatic control of coring length and maintenance of the in-situ state of the core were achieved in deep geological environments. This solved the problems of advance control and sample damage in deep coring tools and improved the accuracy of core analysis.
Patent Information
- Application Number
- CN202521833701.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-27
- Publication Date
- 2026-05-15
- Estimated Expiration
- 2035-08-27
AI Technical Summary
Existing drilling core tools are unable to maintain the original properties of the core in deep geological environments, leading to sample loss and mineral transformation, which affects the accuracy of experimental and analytical results. At the same time, there are problems such as insufficient or excessive drilling, which can cause core fragmentation and tool damage.
The spring-driven self-operated pressure-holding coring tool is used. The main spring drives the coring cylinder to automatically retract into the inner cylinder when the advance reaches the target position. The pressure-holding device maintains a sealed environment to prevent the core from contacting the external environment, thus achieving pressure-holding and high-fidelity coring of deep rock strata.
It effectively avoids core damage caused by insufficient or excessive drilling, maintains the in-situ environmental state of deep cores, improves the accuracy of experimental and analytical results of core samples, and is suitable for coring needs in confined spaces and complex wellbores.
Smart Images
Figure CN224244833U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of drilling coring technology, specifically to an elastic self-driven pressure-holding coring tool. Background Technology
[0002] Core drilling is one of the most direct methods in deep resource exploration. Its basic principle is to drill core samples from deep reservoirs, perform loading tests and analysis, and estimate energy reserves and rock mechanical parameters. Core drilling tools typically consist of a casing with an annular core bit at the front end. Inside the casing is a core barrel, the front end of which is fitted to the core bit. As the drilling tool advances, the core bit drills an annular groove in the rock formation. The rock mass located in the center of the groove is the core, which is then inserted into the core barrel through the center of the core bit to complete the core extraction process. In existing core drilling tools, the core barrel is usually rigidly attached to the casing. During core drilling, the advance (represented by the depth of the drill pipe at the wellhead) is controlled by the operator's experience. This often results in insufficient advance (too short a core length) or excessive advance, leading to core fragmentation or even tool damage.
[0003] In shallow resource exploration, conventional coring techniques are generally sufficient for engineering applications. However, with increasing excavation depth, formation pressure and temperature rise significantly, and geological conditions become more complex, posing a significant challenge to conventional coring techniques. In deep geological environments, the release of in-situ temperature and pressure during core extraction causes the loss of oil, gas, water, and other components, as well as mineral transformation. When the core is recovered to the laboratory, it is often difficult to maintain its original state, leading to decreased accuracy in experimental and analytical results and hindering accurate assessment of in-situ energy reserves. Furthermore, under these complex conditions, core samples may undergo physical and chemical changes due to sudden pressure and temperature fluctuations, resulting in crack propagation and other problems that affect subsequent mechanical analysis and formation geological parameter assessment. Therefore, obtaining authentic and effective core samples from deep reservoirs without damaging their original properties has become a core problem urgently needing to be solved in the field of deep resource exploration. Utility Model Content
[0004] The purpose of this utility model is to overcome the shortcomings of the prior art and provide an elastic self-driven pressure-holding coring tool that can automatically retract the coring cylinder into the inner cylinder when the advance reaches the target position, avoiding situations where the coring length is too short due to insufficient advance or the core is broken or even the tool is damaged due to excessive advance. At the same time, when the coring cylinder retracts into the inner cylinder, the pressure-holding device can keep the inner cylinder in a completely closed state, thereby achieving pressure-holding and high-fidelity coring of deep rock strata.
[0005] The objective of this utility model is achieved through the following technical solution:
[0006] A spring-loaded self-driven pressure-holding coring tool includes a housing, a coring drill bit fixedly mounted at the front end of the housing, and a coring assembly coaxially disposed within the housing. The coring assembly includes a main spring, a positioning cylinder, a coring cylinder, a feed rod, and a locking device. The main spring provides a pulling force to the positioning cylinder toward the rear end of the housing. One end of the coring cylinder is rotatably connected to the front end of the positioning cylinder, and the other end of the coring cylinder is adapted to the coring drill bit. The locking device restricts the movement of the positioning cylinder toward the rear end of the housing. The feed rod passes through the front end of the positioning cylinder and is slidably connected to the positioning cylinder. The feed rod is adapted to the locking device, and when the feed rod slides toward the rear end of the positioning cylinder, the restriction of the locking device between the positioning cylinder and the housing is released.
[0007] Furthermore, it also includes an inner cylinder, which is coaxially disposed inside the housing and sleeved outside the core-taking assembly. The rear end of the inner cylinder is closed and fixedly connected to the housing, and the front end of the inner cylinder is provided with a pressure-holding device. The positioning cylinder is slidably disposed inside the inner cylinder. The two ends of the main spring are respectively connected to the rear end of the inner cylinder and the rear end of the positioning cylinder. The front end of the core-taking cylinder can be retracted to the side of the pressure-holding device away from the core-taking drill bit, and the pressure-holding device can close the front end of the inner cylinder.
[0008] Specifically, the locking device includes a locking element, a locking spring, and an unlocking element, all coaxially arranged within the positioning cylinder. The locking element includes several circumferentially distributed claws, one end of which is fixedly connected to the rear end of the positioning cylinder, and the other end of which extends towards the front end of the positioning cylinder. A first locking tooth is provided on each claw along a direction away from the axis of the positioning cylinder. A through-hole is formed on the positioning cylinder in a radial direction. A positioning groove is machined on the inner wall of the inner cylinder. The end of the first locking tooth away from the claw passes through the locking hole and extends to the... Within the positioning groove, a second locking tooth is provided on the chuck along the direction close to the axis of the positioning cylinder. The unlocking component includes a conical disc and an unlocking disc, both of which are fixedly sleeved on the advance rod. The large-diameter end of the conical disc faces the rear end of the positioning cylinder. The two ends of the locking spring are respectively connected to the rear end of the positioning cylinder and the large-diameter end of the conical disc. The outer conical surface of the conical disc is adapted to the end of the second locking tooth away from the chuck. The end of the unlocking disc facing the rear end of the positioning cylinder is machined with an inner conical hole, and the inner conical surface of the inner conical hole is adapted to the end of the chuck away from the rear end of the positioning cylinder.
[0009] Furthermore, the rear end of the inner cylinder is threaded with a connector, which is disposed inside the rear end of the housing and fixedly connected to the housing.
[0010] Furthermore, the connector has an axial blind hole machined inward at the end away from the inner cylinder, and a radial hole machined on the connector. An annular cavity is formed between the inner cylinder and the shell. The two ends of the radial hole are respectively connected to the axial blind hole and the annular cavity. A through flow channel is provided on the pressure holding device. One end of the through flow channel is connected to the annular cavity, and the other end of the through flow channel is positioned directly opposite the core drill bit.
[0011] Furthermore, there are several radial holes and several through channels, with the radial holes and through channels being evenly distributed around the circumference.
[0012] Furthermore, the inner wall of the core-taking cylinder is evenly distributed with several ratchet teeth, which are wedge-shaped and have their tips facing away from the positioning cylinder.
[0013] Furthermore, a check sleeve is fixedly installed inside the core tube, and a plurality of ratchet racks are evenly distributed around the inner circumference of the check sleeve. A plurality of ratchet teeth are provided on the ratchet racks, and the plurality of ratchet teeth are arranged in a straight line on the ratchet racks along a direction parallel to the axial direction of the core tube.
[0014] The beneficial effects of this utility model are:
[0015] This elastic self-driven pressure-holding coring tool includes a housing, with a coring drill bit fixedly mounted at the front end of the housing. A coring assembly is coaxially arranged inside the housing, comprising a main spring, a positioning cylinder, a coring cylinder, a feed rod, and a locking device. During coring operations, the locking device limits the positioning cylinder to a predetermined position within the housing. Force is transmitted through the housing, locking device, and positioning cylinder to provide a reaction force to the coring cylinder, allowing the drilled core to be smoothly squeezed into the coring cylinder through the center of the drill bit. As the coring process continues, more and more core material enters the coring cylinder. When the feed rod reaches its destination, the end of the core material abuts against the end of the feed rod and pushes the feed rod towards the rear end of the positioning cylinder. The movement of the feed rod triggers the locking device to release the restriction between the positioning cylinder and the housing. Subsequently, under the tension of the main spring, the positioning cylinder, coring cylinder, and core material are retracted towards the rear end of the housing. Therefore, it can be seen that the elastic self-driven pressure-holding coring tool can automatically retract the coring cylinder when the advance reaches the target position, which can avoid the situation of insufficient advance leading to too short coring length or excessive advance leading to core fragmentation or even tool damage during operation.
[0016] The tool also includes an inner cylinder, coaxially mounted within the housing and fitted over the coring assembly. The rear end of the inner cylinder is closed and fixedly connected to the housing, while the front end is equipped with a pressure-holding device. When the coring cylinder is retracted towards the rear end of the housing by the main spring, it is pushed back into the inner cylinder. The pressure-holding device then seals the front end of the inner cylinder, and with the rear end also closed, a completely sealed environment is created inside the inner cylinder, where the obtained core sample is obtained. Therefore, this elastic self-driven pressure-holding coring tool can achieve pressure-holding and high-fidelity coring of deep rock formations, which helps maintain the in-situ environmental state of deep core samples and avoids the impact of changes in the surrounding environment on core properties during extraction from deep locations. This improves the accuracy of experimental and analytical results from core samples. Furthermore, the tool has a compact overall structure with small axial and radial dimensions, making it particularly suitable for coring in complex wellbore environments with confined spaces and ultra-short radii of curvature. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the external structure of a self-driven, elastic pressure-holding coring tool according to the present invention.
[0018] Figure 2 This is a cross-sectional schematic diagram of the internal structure of the shell in the elastic self-driven pressure-holding coring tool of this utility model;
[0019] Figure 3 This is a cross-sectional schematic diagram of the internal structure of the inner cylinder in a self-driven, elastic pressure-holding coring tool according to this utility model.
[0020] Figure 4 for Figure 3 A schematic diagram of the structure in its full cross-section;
[0021] Figure 5 This is a disassembly diagram of the locking device in a spring-loaded self-driven pressure-holding core-taking tool according to this utility model;
[0022] Figure 6 for Figure 5 A cross-sectional view of the locking device in its assembled state.
[0023] Figure 7 This is a schematic diagram of the structure of the stop sleeve of the elastic self-driven pressure-holding coring tool of this utility model;
[0024] In the figure, 1-shell, 2-core drill bit, 3-main spring, 4-positioning cylinder, 5-core cylinder, 6-feed rod, 7-inner cylinder, 8-pressure holding device, 9-locking spring, 10-claw, 11-first clasp, 12-second clasp, 13-conical disc, 14-unlocking disc, 15-connector, 16-axial blind hole, 17-radial hole, 18-through flow channel, 19-ratchet. Detailed Implementation
[0025] The technical solution of this utility model is described in further detail below with reference to the accompanying drawings, but the scope of protection of this utility model is not limited to the following description.
[0026] like Figure 1 As shown, a self-propelled elastic pressure-holding coring tool includes a housing 1. A coring drill bit 2 is fixedly installed at the front end of the housing 1. The coring drill bit 2 is a ring drill bit. During coring operations, a drill rod is connected to the rear end of the housing 1. Driven by the drill rod, the housing 1 and the coring drill bit 2 can drill forward. The coring drill bit 2 drills an annular groove in the rock stratum. The rock mass in the middle area of the annular groove is the rock core to be obtained.
[0027] like Figure 3 , Figure 4 As shown, a core-taking assembly is coaxially arranged inside the housing 1. This assembly includes a main spring 3, a positioning cylinder 4, a core-taking cylinder 5, a feed rod 6, and a locking device. One end of the core-taking cylinder 5 is rotatably connected to the front end of the positioning cylinder 4, and the other end of the core-taking cylinder 5 is adapted to the core-taking drill bit 2. During core drilling, the front end of the core-taking cylinder 5 is close to the center hole of the core-taking drill bit 2. The locking device restricts the positioning cylinder 4 from moving towards the rear end of the housing 1. The housing 1, the locking device, and the positioning cylinder 4 sequentially transmit force to the core-taking cylinder 5 to provide a reaction force. During core drilling, the rock core can smoothly enter the core-taking cylinder 5 through the center of the core-taking drill bit 2. The main spring 3 is a tension spring, which provides tension to the positioning cylinder 4 towards the rear end of the housing 1. Since the positioning cylinder 4 is restricted from moving towards the rear end of the housing 1 by the locking device during core drilling, the main spring 3 remains in a stretched state. The feed rod 6 is slidably connected to the positioning cylinder 4. One end of the feed rod 6 passes through the front end of the positioning cylinder 4 and extends into the core tube 5. The feed rod 6 is adapted to the locking device. As the core extraction process continues, the core entering the core tube 5 becomes longer and longer. When the end of the core in the core tube 5 abuts against the end of the feed rod 6 that extends into the core tube 5, the feed rod 6 can be driven to slide towards the rear end of the positioning cylinder 4. At this time, the feed rod 6 can trigger the locking device to release the restriction between the positioning cylinder 4 and the housing 1. Afterward, the main spring 3 retracts and drives the positioning cylinder 4, the core tube 5 and the core to move towards the rear end of the housing 1.
[0028] Therefore, this elastic self-driven pressure-maintaining coring tool can automatically and accurately control the cutting depth of coring operations, reducing the operational precision required at the wellhead for the drill pipe's diving depth. It effectively avoids situations where insufficient cutting leads to excessively short coring length, or excessive cutting leads to core fragmentation or even tool damage. It should be noted that during actual drilling operations, this tool is driven by the drill pipe and extends to a considerable depth in the well. During drilling, there is some vibration. When the core enters the coring cylinder 5, the vibration causes it to break into small segments. When the locking device releases the restriction between the positioning cylinder 4 and the housing 1, the main spring 3 can directly pull the coring cylinder 5 and the core inside back towards the rear end of the housing 1, without the need for additional intervention to cut off the core root.
[0029] Furthermore, such as Figures 2 to 4 As shown, the elastic self-driven pressure-holding coring tool also includes an inner cylinder 7, which is coaxially disposed inside the housing 1 and sleeved outside the coring assembly. The rear end of the inner cylinder 7 is closed and fixedly connected to the housing, and a pressure-holding device 8 is provided at the front end of the inner cylinder 7. The pressure-holding device 8 can be any device in the prior art that can close the front end of the inner cylinder 7, such as a ball valve or flap valve controlled by elastic force or gravity. The pressure-holding device selected in this embodiment can refer to Chinese Patent A Pressure-Holding Control Device and Fidelity Controller Based on Magnetic Field Action (Application No.: 202110349469.6), which includes a magnetic valve seat, a valve cover, and a magnetic trigger. When the valve cover is released from its limit, it can begin to close under the magnetic force of the magnetic trigger and finally firmly adsorb onto the end of the magnetic valve seat under the magnetic force of the magnetic valve seat to form a seal. The aforementioned positioning cylinder 4 is slidably disposed within the inner cylinder 7. The two ends of the main spring 3 are connected to the rear ends of the inner cylinder 7 and the positioning cylinder 4, respectively. When the core is advanced to the desired depth, the main spring 3 will cause the positioning cylinder 4, the core cylinder 5, and the core to move towards the rear end of the inner cylinder 7. At the end of this movement, the front end of the core cylinder 3 retracts to the side of the pressure-holding device 8 away from the core drill bit 2. The pressure-holding device 8 then seals the front end of the inner cylinder 7. Combined with the fact that the rear end of the inner cylinder 7 is already closed, this creates a completely sealed environment within the inner cylinder 7. Since this process occurs in the deep environment of the core drilling operation, the sealed environment within the inner cylinder 7 upon completion of this action is the deep in-situ environment. The core obtained from the core cylinder 5 is located within this sealed environment, ensuring that the external environment of the core cylinder 5 remains unchanged.
[0030] Therefore, this elastic self-driven pressure-maintaining coring tool can also achieve pressure-maintaining and high-fidelity coring of deep rock formations, which is beneficial to maintaining the in-situ environmental state of deep rock cores and avoiding the impact of changes in the surrounding environment on the performance of rock cores during the process of retrieving them from deep locations. This helps to improve the accuracy of experimental and analytical results of rock core samples. In addition, the tool has a compact overall structure and small axial and radial dimensions, making it suitable for coring needs in complex wellbores with confined spaces and ultra-short radii of curvature.
[0031] In specific implementation, such as Figures 3 to 6 As shown, the locking device includes a locking element, a locking spring 9, and an unlocking element, all of which are coaxially arranged inside the positioning cylinder 4. The locking element includes several circumferentially distributed claws 10. One end of each claw 10 is fixedly connected to the rear end of the positioning cylinder 4, and the other end of each claw 10 extends toward the front end of the positioning cylinder 4. A first locking tooth 11 is provided on the claw 10 along the direction away from the axis of the positioning cylinder 4. A through-hole is provided on the positioning cylinder 4 in the radial direction. A positioning groove is machined on the inner wall of the inner cylinder 7. When the end of the first locking tooth 11 away from the claw 10 passes through the locking hole and extends into the positioning groove, the aforementioned function of restricting the movement of the positioning cylinder 4 toward the rear end of the housing 1 is achieved. The unlocking component includes a conical disc 13, which is fixedly sleeved on the feed rod 6. The large-diameter end of the conical disc 13 faces the rear end of the positioning cylinder 4. The two ends of the locking spring 9 are respectively connected to the rear end of the positioning cylinder 4 and the large-diameter end of the conical disc 13. A second locking tooth 12 is also provided on the pawl 10 along the direction close to the axis of the positioning cylinder 4. The outer conical surface of the conical disc 13 is adapted to the end of the second locking tooth 12 away from the pawl 10. Under the elastic force of the locking spring 9, the outer conical surface of the conical disc 13 can be pressed against the end of each second locking tooth 12, keeping each pawl 10 in a state of being open outward, thereby ensuring the reliability of the limiting state of the locking device in restricting the movement of the positioning cylinder 4 towards the rear end of the housing 1. The unlocking device also includes an unlocking disc 14, which is also fixedly sleeved on the advance rod 6. The end of the unlocking disc 14 facing the rear end of the positioning cylinder 4 is machined with an inner conical hole. The inner conical surface of the inner conical hole is adapted to the end of the chuck 10 away from the rear end of the positioning cylinder 4. When the core advance is in place, the core pushes the advance rod 6 to move towards the rear end of the positioning cylinder 4. The conical disc 13 and the unlocking disc 14 move together with the advance rod 6. The conical disc 13 releases the abutment limit state of the ends of each second chuck tooth 12. The inner conical hole on the unlocking disc 14 drives the ends of each chuck 10 to retract inward. When the chuck 10 retracts inward, it can drive the first chuck tooth 11 to swing until the first chuck tooth 11 is dislodged from the positioning groove, thus releasing the restriction between the locking device and the positioning cylinder 4 and the housing 1. At this time, the positioning cylinder 4 and the core cylinder 5 can move towards the rear end of the housing 1 under the pull of the main spring 3.
[0032] Furthermore, such as Figure 2 As shown, the rear end of the inner cylinder 7 is threaded with a connector 15, which closes the rear end of the inner cylinder 7. The connector 15 is located inside the rear end of the shell 1 and is fixedly connected to the shell 1 by parts such as snap rings. The connector 15, the inner cylinder 7 and the shell 1 are all manufactured independently, and their processing and disassembly are relatively easy. After the tool is removed from the wellhead, it can be easily disassembled to remove the core from the core tube 5.
[0033] Furthermore, such as Figure 2As shown, the connector 15 has an axial blind hole 16 machined inward at the end away from the inner cylinder 7, and a radial hole 17 machined on the connector 15. An annular cavity is formed between the inner cylinder 7 and the shell 1. The two ends of the radial hole 17 are connected to the axial blind hole 16 and the annular cavity, respectively. A through flow channel 18 is provided on the pressure holding device 8. One end of the through flow channel 18 is connected to the annular cavity, and the other end of the through flow channel 18 is positioned directly opposite the core drill bit 2. During core drilling operations, drilling fluid is injected into the axial blind hole 16. The drilling fluid can flow sequentially through the radial hole 17, the annular cavity, and the through flow channel 18, and finally flow to the core drill bit 2, so as to play a role in cooling, lubrication, and carrying rock cuttings. Furthermore, there are several radial holes 17 and several through flow channels 18. The radial holes 17 are evenly distributed around the circumference, and the through flow channels 18 are also evenly distributed around the circumference, so that the drilling fluid flowing out through the through flow channels 18 is evenly distributed, which fully ensures the effectiveness of the drilling fluid in cooling, lubrication, and carrying rock cuttings.
[0034] Furthermore, such as Figure 4 As shown, several ratchet teeth 19 are evenly distributed around the inner circumference of the core barrel 5. The ratchet teeth 19 are wedge-shaped, with their tips pointing away from the positioning cylinder 4. Through the wedge-shaped structure of the ratchet teeth 19, the core can be smoothly squeezed into the core barrel 5 between the ratchet teeth 19 during drilling. Simultaneously, during the retraction of the core barrel 5 and subsequent tool removal, the thick ends of each ratchet tooth 19 can effectively clamp the core, preventing it from slipping out of the core barrel 5. In specific implementation, a setup such as... Figure 7 The check sleeve shown is fixedly assembled inside the core barrel 5 by bolts, etc. A number of ratchet racks are evenly distributed around the inner circumference of the check sleeve, and a number of ratchet teeth 19 are provided on the ratchet racks. The ratchet teeth 19 are arranged in a straight line on the ratchet racks along the axial direction parallel to the core barrel 5. By setting multiple sets of ratchet teeth 19, it is beneficial to ensure the reliability of the core being clamped after the core enters the core barrel 5. At the same time, the core barrel 5 and the check sleeve are designed as a split structure, which facilitates processing and manufacturing, and also allows for the core sampling of core samples of different diameters by changing the check sleeve and the core drill bit 2 of different specifications.
[0035] The above description is merely a preferred embodiment of this utility model. It should be understood that this utility model is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this utility model should be protected within the scope of the appended claims.
Claims
1. A spring-loaded self-driven pressure-holding coring tool, comprising a housing, wherein a coring drill bit is fixedly disposed at the front end of the housing, characterized in that, A core-taking assembly is coaxially arranged inside the housing. The core-taking assembly includes a main spring, a positioning cylinder, a core-taking cylinder, a feed rod, and a locking device. The main spring provides a pulling force to the positioning cylinder in the rearward direction of the housing. One end of the core-taking cylinder is rotatably connected to the front end of the positioning cylinder, and the other end of the core-taking cylinder is adapted to the core drill bit. The locking device is used to restrict the positioning cylinder from moving towards the rear end of the housing. The advance rod passes through the front end of the positioning cylinder and is slidably connected to the positioning cylinder. The advance rod is adapted to the locking device. When the advance rod slides towards the rear end of the positioning cylinder, the restriction of the locking device between the positioning cylinder and the housing can be released.
2. The elastic self-driven pressure-holding coring tool according to claim 1, characterized in that, It also includes an inner cylinder, which is coaxially disposed inside the housing and sleeved outside the core-taking assembly. The rear end of the inner cylinder is closed and fixedly connected to the housing, and the front end of the inner cylinder is provided with a pressure-holding device. The positioning cylinder is slidably disposed inside the inner cylinder. The two ends of the main spring are respectively connected to the rear end of the inner cylinder and the rear end of the positioning cylinder. The front end of the core-taking cylinder can be retracted to the side of the pressure-holding device away from the core-taking drill bit. The pressure-holding device can close the front end of the inner cylinder.
3. The elastic self-driven pressure-holding coring tool according to claim 2, characterized in that, The locking device includes a locking element, a locking spring, and an unlocking element, all of which are coaxially arranged inside the positioning cylinder. The locking component includes a plurality of circumferentially distributed claws. One end of each claw is fixedly connected to the rear end of the positioning cylinder, and the other end of each claw extends toward the front end of the positioning cylinder. A first locking tooth is provided on each claw along a direction away from the axis of the positioning cylinder. A through-hole is formed on the positioning cylinder in a radial direction. A positioning groove is machined on the inner wall of the inner cylinder. The end of the first locking tooth away from the claw passes through the locking hole and extends into the positioning groove. A second locking tooth is provided on each claw along a direction close to the axis of the positioning cylinder. The unlocking component includes a conical disc and an unlocking disc, both of which are fixedly sleeved on the feed rod. The large-diameter end of the conical disc faces the rear end of the positioning cylinder. The two ends of the locking spring are respectively connected to the rear end of the positioning cylinder and the large-diameter end of the conical disc. The outer conical surface of the conical disc is adapted to the end of the second locking tooth away from the locking claw. The end of the unlocking disc facing the rear end of the positioning cylinder is machined with an inner conical hole, and the inner conical surface of the inner conical hole is adapted to the end of the locking claw away from the rear end of the positioning cylinder.
4. The elastic self-driven pressure-holding coring tool according to claim 2, characterized in that, The inner cylinder is threaded to a connector at its rear end, and the connector is located inside the rear end of the housing and is fixedly connected to the housing.
5. The elastic self-driven pressure-holding coring tool according to claim 4, characterized in that, The connector has an axial blind hole machined inward at the end away from the inner cylinder, and a radial hole machined on the connector. An annular cavity is formed between the inner cylinder and the shell. The two ends of the radial hole are respectively connected to the axial blind hole and the annular cavity. A through flow channel is provided on the pressure holding device. One end of the through flow channel is connected to the annular cavity, and the other end of the through flow channel is positioned directly opposite the core drill bit.
6. The elastic self-driven pressure-holding coring tool according to claim 5, characterized in that, There are several radial holes and several through channels, with the radial holes and through channels being evenly distributed around the circumference.
7. The elastic self-driven pressure-holding coring tool according to claim 1, characterized in that, The inner wall of the core-taking tube is evenly distributed with several ratchet teeth. The ratchet teeth are wedge-shaped, and the tips of the ratchet teeth are set towards the end away from the positioning tube.
8. A self-driven, elastic, pressure-holding coring tool according to claim 7, characterized in that, A check sleeve is fixedly installed inside the core-collecting cylinder. A number of ratchet racks are evenly distributed around the inner circumference of the check sleeve. A number of ratchet teeth are provided on the ratchet racks, and the ratchet teeth are arranged in a straight line on the ratchet racks along the axial direction parallel to the core-collecting cylinder.