Salvage structure for coal mining drilling

Abstract

The invention relates to the technical field of drilling auxiliary equipment, in particular to a fishing structure for coal mining drilling, which comprises a grabbing structure for clamping a drilling tool and a connecting rod for conveying the grabbing structure, the grabbing structure comprises a balance weight disc and a plurality of clamping arms distributed in the circumferential direction of the balance weight disc, and each clamping arm is composed of an inclined part located on the upper side and a vertical part located on the lower side. By adopting the mode that the multiple clamping arms surround and clamp the drilling tool, the drilling tool can be effectively and firmly clamped by the grabbing structure, and therefore the drilling tool can be conveniently and smoothly moved out of a drilled hole, secondary falling of the drilling tool is avoided, and the fishing success rate is increased; and meanwhile, a large space can be defined by the multiple clamping arms, so that even if the drilling tool deviates in a drill hole, the grabbing structure can still effectively clamp and salvage the drilling tool, and functionality is improved.

Description

Technical Field

[0001] This invention relates to the technical field of drilling auxiliary equipment, and in particular to a retrieval structure for drilling in coal mining. Background Technology

[0002] Drilling is a crucial step in coal mining and is widely used in many fields such as gas extraction, coal seam water injection, geological exploration, anchor support, and pressure relief hole construction. These boreholes are usually deep and vary in diameter, and the working environment is complex, often accompanied by unfavorable geological conditions such as high ground pressure, fractured rock strata, and uneven coal and rock mass structure.

[0003] During drilling operations or subsequent use, drilling tools (such as drill rods and drill bits) are prone to accidental detachment, jamming, or even breakage, causing them to remain inside the hole. Such accidents not only directly interrupt current drilling operations, causing delays and wasting manpower and resources, but may also block critical gas extraction channels or water injection paths, affecting mine safety production deployment and disaster prevention effectiveness. Furthermore, if detached metal parts cannot be removed in time, they may pose a serious obstacle to subsequent drilling operations in adjacent areas, and even trigger secondary accident risks. Therefore, retrieving objects from the hole and restoring drilling function is a common and urgent technical challenge to ensure safe and efficient coal mine production.

[0004] Traditional retrieval methods use magnets to pull the drill bit out of the borehole. However, due to the complex environment inside the borehole, metal materials inside the borehole tend to be attracted to the magnet first, which weakens the magnet's ability to attract the drill bit, resulting in a low success rate for this retrieval method. Summary of the Invention

[0005] This invention provides a retrieval structure for drilling in coal mines, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A retrieval structure for drilling in coal mining includes a gripping structure for holding the drill bit and a connecting rod for conveying the gripping structure. The gripping structure includes a counterweight disk and a plurality of clamping arms distributed around the circumference of the counterweight disk. Each clamping arm consists of an inclined portion on the upper side and a vertical portion on the lower side. The inclined portion slides through the counterweight disk in the direction of the axial direction of the counterweight disk, and at least a portion of the vertical portion on the counterweight disk clamps the drill bit. The counterweight plate is provided with a locking unit for fixing the position of the clamping arms, and a limit flat edge is provided on the top of each clamping arm.

[0007] In some embodiments of the present invention, each of the vertical portions is provided with a plurality of locking edges, the locking edges being horizontally arranged and the plurality of locking edges being vertically arranged; The drill bit has several annular grooves arranged along the axial direction of the drill bit, and the annular grooves are used in conjunction with the jack.

[0008] In some embodiments of the present invention, the rim is inclined upwards, and the cross-section of the annular groove is inclined downwards.

[0009] In some embodiments of the present invention, a compression sleeve is slidably fitted on the counterweight disk, and the bottom of the clamping edge is used in conjunction with the inclined portions on a plurality of clamping arms on the counterweight disk that are not clamping the drill bit.

[0010] In some embodiments of the present invention, the bottom of the extrusion sleeve is provided with a plurality of rolling elements.

[0011] In some embodiments of the present invention, an electromagnetic coil is provided on the top of the counterweight plate, the electromagnetic coil is fixedly connected to the counterweight plate through several vertical rods, and a movable ring is slidably sleeved on the outer side of the several vertical rods. The movable ring is used in conjunction with the electromagnetic coil, and a support ring is provided on the movable ring to cooperate with the limiting flat edge on the clamping arm in the clamping state.

[0012] In some embodiments of the present invention, the locking unit is a side pressure ring fixed on the inner wall of the extrusion sleeve, and the inner wall of the side pressure ring is configured as a conical surface that cooperates with the inclined portion on the clamping arm in the clamping state.

[0013] In some embodiments of the present invention, the middle part of the extrusion sleeve is provided with an iron core located inside the support ring and used in conjunction with the electromagnetic coil, and the iron core is fixedly connected to the extrusion sleeve through a plurality of connecting plates.

[0014] In some embodiments of the present invention, a top pressure column is slidably inserted in the middle of the counterweight plate, the top pressure column is connected to the counterweight plate by a spring, and the top pressure column is used in conjunction with the iron core.

[0015] In some embodiments of the present invention, a plurality of insert posts are provided on the top of the counterweight plate, and each insert post slides through the side pressure ring and is connected to the connecting rod through a connecting plate; Each of the insertion posts is fitted with a second spring, which is used to connect the side pressure ring and the counterweight plate.

[0016] The technical solution of this invention can achieve the following technical effects: By using several clamping arms to surround and hold the drill bit, the gripping structure can effectively and firmly hold the drill bit, thus facilitating the smooth removal of the drill bit from the borehole, preventing secondary detachment of the drill bit, and improving the success rate of retrieval. At the same time, since the several clamping arms can form a large space, even if the drill bit shifts within the borehole, the gripping structure can still effectively hold and retrieve the drill bit, improving functionality. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 yes Figure 1 Explosion structure diagram; Figure 3 This is a schematic diagram of the grasping structure in an embodiment of the present invention; Figure 4 yes Figure 3 A schematic diagram of the structure viewed from below; Figure 5 This is a schematic diagram of the internal structure of the extrusion sleeve in an embodiment of the present invention; Figure 6 This is a schematic diagram of the clamping arm structure in an embodiment of the present invention; Figure 7 This is a cross-sectional view of the annular groove in an embodiment of the present invention; Figure 8 This is a schematic diagram of the electromagnetic coil and its structure in an embodiment of the present invention.

[0019] Figure label: 100. Drilling tool; 101. Annular groove; 102. Reamer tooth; 200. Gripping structure; 201. Counterweight plate; 202. Clamping arm; 203. Inclined part; 204. Vertical part; 205. Clamping edge; 206. Extrusion sleeve; 207. Rolling element; 208. Limiting flat edge; 209. Electromagnetic coil; 210. Vertical rod; 211. Moving ring; 212. Support ring; 213. Side pressure ring; 214. Iron core; 215. Connecting plate; 216. Top pressure column; 217. Spring one; 218. Insertion column; 219. Connecting plate; 220. Spring two; 300, connecting rod. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] like Figures 1 to 6 As shown, a retrieval structure for drilling in coal mining according to the present invention includes a gripping structure 200 for holding the drill bit 100 and a connecting rod 300 for conveying the gripping structure 200. The gripping structure 200 includes a counterweight disk 201 and a plurality of gripping arms 202 distributed around the circumference of the counterweight disk 201. Each gripping arm 202 consists of an inclined portion 203 located on the upper side and a vertical portion 204 located on the lower side. The inclined portion 203 slides through the counterweight disk 201 in the direction of the axis of the counterweight disk 201, and at least a portion of the vertical portion 204 on the counterweight disk 201 grips the drill bit 100. A locking unit for fixing the position of the clamping arms 202 is provided on the counterweight plate 201, and a limit flat edge 208 is provided on the top of each clamping arm 202.

[0023] The connecting rod 300 can transport the gripping structure 200 into the borehole and bring it close to the drill string 100. Simultaneously, the connecting rod 300 can lift and remove the gripping structure 200 and the drill string 100 from the borehole, thus enabling the retrieval of the drill string 100. The limiting flat edge 208 on the clamping arm 202 can be used to limit the position of the clamping arm 202 on the counterweight plate 201, thereby preventing the clamping arm 202 from sliding and falling off the counterweight plate 201. Figure 2As shown, the shoulder of the drill bit 100 has several reaming teeth 102 for reaming or drilling. Some of the clamping arms 202 on the counterweight plate 201 can be used in conjunction with the reaming teeth 102. That is, when the clamping arms 202 move down with the counterweight plate 201, the bottom of the clamping arms 202 contacts the reaming teeth 102. At this time, the reaming teeth 102 will prevent the clamping arms 202 from moving, while the counterweight plate 201 will continue to move due to gravity. At this time, the counterweight plate 201 and the clamping arms 202 will have relative motion. Since the clamping arms 202 are slidably connected to the counterweight plate 201 by their inclined parts 203, the clamping arms 202 will move closer to the drill shank of the drill bit 100. Thus, the multiple clamping arms 202 can clamp the drill bit 100. The locking unit on the counterweight plate 201 can be used to fix the position of the clamping arms 202 in the clamping state, thereby realizing the stable clamping of the drill bit 100 by the gripping structure 200.

[0024] Since there are several clamping arms 202 in the circumferential direction of the counterweight plate 201, some of the clamping arms 202 will always contact and cooperate with several reaming teeth 102 on the drill bit 100, while the remaining clamping arms 202 are allowed to pass through the gap between two adjacent reaming teeth 102 and move. These clamping arms 202 are allowed to be idle. The circumferential distribution of the clamping arms 202 on the counterweight plate 201 can form a large space below the counterweight plate 201. In this way, even if the drill bit 100 shifts in the borehole, the clamping arms 202 can still move to the outside of the drill shank on the drill bit 100 and clamp and fix the drill shank, thereby improving the functionality and applicability of the retrieval.

[0025] By using several clamping arms 202 to surround and hold the drill bit 100, the gripping structure 200 can effectively and firmly hold the drill bit 100, thus facilitating the smooth removal of the drill bit 100 from the borehole, preventing the drill bit 100 from falling off again, and improving the success rate of retrieval. At the same time, since the several clamping arms 202 can form a large space, even if the drill bit 100 shifts within the borehole, the gripping structure 200 can still effectively hold and retrieve the drill bit 100, improving functionality.

[0026] Optimized from the above implementation, such as Figure 6 and Figure 7 As shown, each vertical part 204 is provided with several locking ridges 205, which are horizontally arranged and arranged vertically; the drill bit 100 is provided with several annular grooves 101, which are arranged along the axial direction of the drill bit 100, and the annular grooves 101 are used in conjunction with the locking ridges 205.

[0027] Several annular grooves 101 are located at the drill shank position of the drill tool 100. When the vertical part 204 contacts the drill shank position of the drill tool 100, several locking edges 205 on the vertical part 204 will be locked into the corresponding annular grooves 101 on the drill tool 100. This allows several clamping arms 202 to stably and firmly clamp the drill tool 100, preventing the vertical part 204 from sliding relative to the drill shank position on the drill tool 100 and causing the drill tool 100 to fall off when the gripping structure 200 moves the drill tool 100.

[0028] Optimized from the above implementation, such as Figure 6 and Figure 7 As shown, the clasp 205 is inclined upwards, and the cross-section of the annular groove 101 is inclined downwards. When the clasp 205 is inserted into the annular groove 101, since both the clasp 205 and the annular groove 101 are inclined, the gravity or the friction of the borehole wall on the drill bit 100 will make the clasp 205 and the annular groove 101 more firmly engaged, and the vertical part 204 and the drill bit 100 fit together more tightly. This avoids the drill bit 100 from bending and deforming in a direction away from the drill bit 100 due to excessive resistance when the clasp 205 and the annular groove 101 are horizontally engaged, thus preventing the vertical part 204 from separating from the drill bit 100.

[0029] Because the diameters of the drill shank and the helical portion of the drill body of drill string 100 are different, the shoulder of drill string 100 is typically tapered towards the drill tip. Figure 2 As shown in the drill bit 100, since some of the clamping arms 202 on the counterweight plate 201 are used in conjunction with several reaming teeth 102 on the drill bit 100, while the remaining clamping arms 202 pass through the gap between adjacent reaming teeth 102 and are idle, in order to utilize the idle clamping arms 202, a method can be adopted as follows: Figure 4 As shown, a compression sleeve 206 is slidably sleeved on the counterweight plate 201, and the bottom of the clamping edge 205 is used in conjunction with the inclined part 203 on several clamping arms 202 on the counterweight plate 201 that do not clamp the drill bit 100.

[0030] In its natural state, most of the inclined portions 203 on the clamping arm 202 are located below the counterweight plate 201. When the squeezing sleeve 206 moves downward on the counterweight plate 201, the bottom of the squeezing sleeve 206 contacts the outer wall of the inclined portion 203 below the counterweight plate 201. At this time, the squeezing sleeve 206 squeezes the inclined portion 203, causing the clamping arm 202 to bend towards the axis of the counterweight plate 201 and undergo elastic deformation. The vertical portion 204 on the clamping arm 202 contacts the conical surface of the shoulder of the drill bit 100. At this time, several vertical portions 204 clamp and fix the shoulder of the drill bit 100. Since the clamping area is conical, its firmness is higher and it is not easy for the drill bit 100 to fall off the gripping structure 200.

[0031] Using the above structure, some of the clamping arms 202 can clamp the drill shank area of ​​the drill bit 100, while the remaining clamping arms 202 can clamp the shoulder area of ​​the drill bit 100. This makes full use of all the clamping arms 202 on the counterweight plate 201 and improves the clamping effect.

[0032] It should be noted that the clamping arm 202, which is used in conjunction with the drill shank position on the drill bit 100, is displaced in the direction of the axis of the counterweight plate 201, and therefore separates from the compression sleeve 206.

[0033] Optimized from the above implementation, such as Figure 4 As shown, the bottom of the extrusion sleeve 206 is provided with several rolling elements 207. By using the rolling elements 207, when the extrusion sleeve 206 pushes the clamping arm 202 to bend and deform, the rolling elements 207 and the clamping arm 202 can roll relative to each other, thereby reducing the friction between the extrusion sleeve 206 and the clamping arm 202. Since the position of the clamping arm 202 on the counterweight plate 201 that is used in conjunction with the shoulder of the drill bit 100 is uncertain, several rolling elements 207 can be arranged in the circumferential direction at the bottom of the extrusion sleeve 206. No matter which clamping arm 202 is used in conjunction with the shoulder of the drill bit 100, there will be a corresponding rolling element 207 in contact with that clamping arm 202.

[0034] In practical use, such as Figure 4 As shown, the bottom inner side of the extrusion sleeve 206 is set in a conical shape, and the rolling element 207 is rotatably embedded in the conical surface. Specifically, an auxiliary ring can be added to the bottom of the extrusion sleeve 206. The auxiliary ring cooperates with the bottom of the extrusion sleeve 206 and locks the rolling element 207 between them.

[0035] Optimized from the above implementation, such as Figure 8 As shown, an electromagnetic coil 209 is provided on the top of the counterweight plate 201. The electromagnetic coil 209 is fixedly connected to the counterweight plate 201 through several vertical rods 210. A movable ring 211 is slidably sleeved on the outer side of the several vertical rods 210. The movable ring 211 is used in conjunction with the electromagnetic coil 209. A support ring 212 is provided on the movable ring 211 to cooperate with the limiting flat edge 208 on the clamping arm 202 in the clamping state.

[0036] A wire can be inserted inside the connecting rod 300 to connect the electromagnetic coil 209 to an external power source. In its natural state, due to gravity, the moving ring 211 is located on the lower side outside the electromagnetic coil 209. When the electromagnetic coil 209 is energized, a magnetic field is generated around the electromagnetic coil 209 and attracts the moving ring 211. At this time, the moving ring 211 moves upward and pushes the support ring 212 to move synchronously. The top of the support ring 212 pushes the limiting flat edge 208 on several clamping arms 202 that are used in conjunction with the drill shank position of the drill tool 100, thereby assisting in pushing some of the clamping arms 202 to clamp and fix the drill shank position of the drill tool 100. Furthermore, this structure can cause several clamping arms 202 that have already undergone partial displacement to actively move closer to each other and clamp the drill tool 100 when the drill tool 100 is tilted and the counterweight plate 201 cannot provide an effective lateral pushing force to the clamping arms 202.

[0037] The vertical rod 210 and the support ring 212 are both made of non-metallic materials, while the moving ring 211 is made of metallic magnetic material.

[0038] It should be noted that the clamping arm 202, which is not supported by the enlarging tooth 102, will move between two adjacent enlarging teeth 102, and the limiting flat edge 208 on the clamping arm 202 is located outside the supporting ring 212. The supporting ring 212 cannot be used in conjunction with the limiting flat edge 208. Only when the clamping arm 202 tilts and moves and the limiting flat edge 208 moves into the moving path of the supporting ring 212 can the supporting ring 212 assist in pushing the limiting flat edge 208.

[0039] Optimized from the above implementation, such as Figure 5 As shown, the locking unit is a side pressure ring 213 fixed on the inner wall of the extrusion sleeve 206. The inner wall of the side pressure ring 213 is set as a conical surface that cooperates with the inclined portion 203 on the clamping arm 202 in the clamping state. When the extrusion sleeve 206 moves downward, it will drive the side pressure ring 213 to move synchronously. At this time, the inner conical surface of the side pressure ring 213 will come into contact with the outer wall of the inclined portion 203 on the upper part of the counterweight plate 201 and press and fix it, thereby realizing the locking work of the clamping arm 202 in the clamping state. The top of the clamping arm 202 that cooperates with the shoulder of the drill bit 100 is close to the top of the counterweight plate 201. The clamping arm 202 does not reach the height position of the side pressure ring 213, so the side pressure ring 213 cannot fix this part of the clamping arm 202.

[0040] It should be noted that, using the above-described structure, the clamping arm 202, which is used in conjunction with the drill shank of the drill bit 100, can be fixed at any position.

[0041] Optimized from the above implementation, such as Figure 3 As shown, the middle part of the extrusion sleeve 206 is provided with an iron core 214 located inside the support ring 212 and used in conjunction with the electromagnetic coil 209. The iron core 214 is fixedly connected to the extrusion sleeve 206 through several connecting plates 215.

[0042] The iron core 214, electromagnetic coil 209, support ring 212, and side pressure ring 213 are coaxial, and the electromagnetic coil 209 is located between the moving ring 211 and the iron core 214. The iron core 214 is fixedly connected to the extrusion sleeve 206 through several connecting plates 215. In its natural state, the iron core 214 is located above the electromagnetic coil 209. When the electromagnetic coil 209 is energized, magnetic fields are generated inside and outside the electromagnetic coil 209. The magnetic field outside the electromagnetic coil 209 provides power for the movement of the moving ring 211, and the magnetic field inside the electromagnetic coil 209 provides power for the movement of the iron core 214. The iron core 214 moves down and drives the extrusion sleeve 206 to move.

[0043] In actual use, the moving distance of the moving ring 211 is shorter than that of the iron core 214. This allows the moving ring 211 to first push and fix several clamping arms 202, and then the side pressure ring 213 to squeeze and lock several clamping arms 202.

[0044] Optimized from the above implementation, such as Figure 8 As shown, a top pressure column 216 is slidably inserted in the middle of the counterweight plate 201. The top pressure column 216 is connected to the counterweight plate 201 by a spring 217, and the top pressure column 216 is used in conjunction with the iron core 214.

[0045] When the iron core 214 moves downward, it will contact the top pressure column 216 and push the top pressure column 216 downward. The spring 217 undergoes elastic deformation. The bottom of the top pressure column 216 contacts the top of the drill bit 100 and provides downward auxiliary thrust to the drill bit 100. At this time, the cooperation of the clamping rib 205 and the annular groove 101 can make the clamping arm 202 fit more tightly with the drill bit 100 and the connection more secure. The top pressure column 216 is made of non-metallic material. The top pressure column 216 and the iron core 214 can be connected to each other or separated from each other.

[0046] Optimized from the above implementation, such as Figure 5 As shown, the top of the counterweight plate 201 is provided with several inserts 218, each insert 218 sliding through the side pressure ring 213 and connected to the connecting rod 300 through the connecting plate 219; Each insertion post 218 is fitted with a second spring 220, which is used to connect the side pressure ring 213 and the counterweight plate 201.

[0047] Several inserts 218 and connecting plates 219 can connect the connecting rod 300 and the counterweight plate 201, thus avoiding the extrusion sleeve 206 and several connecting plates 215 on it, so that the entire structure operates with the counterweight plate 201 as the reference. At the same time, several inserts 218 can guide the side pressure ring 213 to prevent the extrusion sleeve 206 from rotating arbitrarily in the circumferential direction. Spring 220 can connect the side pressure ring 213 and the counterweight plate 201, so that in the natural state, the iron core 214 is located above the electromagnetic coil 209.

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A fishing structure for drilling in coal mines, characterized in that, It includes a gripping structure for holding the drill bit and a connecting rod for conveying the gripping structure; The gripping structure includes a counterweight disk and a plurality of clamping arms distributed around the circumference of the counterweight disk. Each clamping arm consists of an inclined portion on the upper side and a vertical portion on the lower side. The inclined portion slides through the counterweight disk in the direction of the axial direction of the counterweight disk, and at least a portion of the vertical portion on the counterweight disk clamps the drill bit. The counterweight plate is provided with a locking unit for fixing the position of the clamping arms, and a limit flat edge is provided on the top of each clamping arm.

2. The fishing structure for coal mining boreholes according to claim 1, characterized in that, Each of the vertical portions is provided with a plurality of locking edges, the locking edges being horizontally arranged and the plurality of locking edges being vertically arranged; The drill bit has several annular grooves arranged along the axial direction of the drill bit, and the annular grooves are used in conjunction with the jack.

3. The fishing structure for coal mine drilling according to claim 2, characterized in that, The rim is tilted upwards, and the cross-section of the annular groove is tilted downwards.

4. The fishing structure for coal mining boreholes according to claim 1, characterized in that, A compression sleeve is slidably fitted on the counterweight plate, and the bottom of the clamping edge is used in conjunction with the inclined portions on several clamping arms on the counterweight plate that are not clamping the drill bit.

5. The fishing structure for coal mining boreholes according to claim 4, characterized in that, The bottom of the extrusion sleeve is provided with several rolling elements.

6. The fishing structure for coal mining boreholes according to claim 4, characterized in that, An electromagnetic coil is provided on the top of the counterweight plate. The electromagnetic coil is fixedly connected to the counterweight plate through several vertical rods. A movable ring is slidably sleeved on the outer side of the several vertical rods. The movable ring is used in conjunction with the electromagnetic coil. A support ring is provided on the movable ring to cooperate with the limiting flat edge on the clamping arm in the clamping state.

7. The fishing structure for coal mining boreholes according to claim 4, characterized in that, The locking unit is a side pressure ring fixed on the inner wall of the extrusion sleeve, and the inner wall of the side pressure ring is configured as a conical surface that cooperates with the inclined portion on the clamping arm in the clamping state.

8. A fishing structure for coal mine drilling according to claim 6, characterized in that, The extrusion sleeve has an iron core located inside the support ring and used in conjunction with the electromagnetic coil in the middle. The iron core is fixedly connected to the extrusion sleeve by several connecting plates.

9. A fishing structure for coal mine drilling according to claim 8, characterized in that, A top pressure column is slidably inserted in the middle of the counterweight plate. The top pressure column is connected to the counterweight plate by a spring, and the top pressure column is used in conjunction with the iron core.

10. A fishing structure for coal mining boreholes according to claim 7, characterized in that, The top of the counterweight plate is provided with several inserts, and each insert slides through the side pressure ring and is connected to the connecting rod through the connecting plate. Each of the insertion posts is fitted with a second spring, which is used to connect the side pressure ring and the counterweight plate.

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