Coal seam hydraulic pressure relief hole protection drill

Abstract

The invention belongs to the technical field of coal mining and exploration safety, and discloses a coal seam hydraulic pressure relief hole protection drill, including an inner joint, an outer joint, a high and low pressure switching mechanism, an openable core body and a cutter sleeve. The beneficial effects are: simple structure, high reliability, conducive to improving drilling technology, improving hole quality, increasing drilling hole protection rate, simplifying construction process, helping to reduce the blank zone of gas extraction, improving gas extraction efficiency, extending the effective drilling extraction cycle, and ensuring mine safety production.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining and exploration safety, and in particular to a coal seam hydraulic pressure relief hole protection drill. Background Art

[0002] China is the world's largest coal producer and consumer. Most coal seams in China are characterized by heterogeneity, microporosity, low permeability, and high adsorption. The low permeability and heterogeneity of coal seams make it difficult to effectively extract gas. However, for single high-burst coal seams or first-mining layers of high-burst coal seams that do not have the conditions for mining in the protective layer, pre-extraction of coal seam gas by drilling through the layer is the main gas control method. In order to improve the coal seam gas extraction rate, shorten the pre-extraction time, and reduce the number of drilling holes, measures must be taken to increase the permeability of the coal seam. In recent years, researchers have proposed a variety of drilling pressure relief and permeability enhancement methods, the most important of which is hydraulic pressure relief and permeability enhancement technology, such as hydraulic slitting and hydraulic punching. Its main principle is to use high-pressure water as a hydraulic measure to destroy and damage the coal body in the borehole to form a pressure relief space and secondary cracks, so that the coal rock mass is deformed and displaced, so as to achieve the purpose of coal reservoir pressure relief and permeability enhancement. This method has been widely used in coal mining enterprises.

[0003] Although there are many hydraulic punching and slitting equipment used in mines at home and abroad, there are still some problems with the existing equipment, mainly:

[0004] (1) The existing hydraulic punching and cutting devices used in mines are immature and require the replacement of the punching drill bit after the drill is withdrawn. The punching operation cannot be performed efficiently and is prone to problems. Therefore, it has not yet been promoted and applied in coal mines.

[0005] (2) The existing hydraulic punching and cutting equipment used in mines cannot pass the screen pipe in the middle and has no hole protection function. After drilling a hole, it is necessary to withdraw the drill and then put in the hole protection screen pipe. However, the coal seam occurrence is complex and changeable, and the coal body structure is uneven. For soft coal seams, it is easy to form a collapsed hole, resulting in the screen pipe of the hydraulic pressure relief and permeability enhancement technology cannot be completely inserted into the end of the drill hole, which cannot meet the process requirements of coal mine extraction and the pressure relief effect is difficult to guarantee. Summary of the invention

[0006] The purpose of the invention is to provide a coal seam hydraulic pressure relief hole protection drill which is simple to operate, highly adaptable, easy to use and convenient.

[0007] To achieve the above-mentioned object, the present invention is implemented according to the following technical scheme: a coal seam hydraulic pressure relief hole protection drill, comprising an inner joint, an outer joint, a high and low pressure switching mechanism, an openable core body and a cutter sleeve, wherein the inner joint and the outer joint are respectively arranged at both ends of the cutter sleeve and are respectively connected to the cutter sleeve by threads; the inner joint, the outer joint and the cutter sleeve are all internal water-permeable cavities,

[0008] The high-low pressure switching mechanism includes a piston and a switching sleeve, the switching sleeve is sealed and movably connected to the inner wall of the inner joint, and a high-pressure nozzle communicating with the water-passing inner cavity is provided on the side wall of the inner joint; the piston includes a return spring and a pressure head, the return spring is limited and fixed in the water-passing inner cavity of the outer joint, the pressure head is a hollow shaft, an outwardly convex shaft shoulder is provided in the middle of the outer wall of the pressure head, the front end face of the pressure head is crimped to one end of the return spring, and a hole shoulder matching with the pressure head shaft shoulder is provided in the water-passing inner cavity of the outer joint; a low-pressure water passing hole leading from the outer wall to the center is provided on the shaft body between the front end face of the pressure head and the shaft shoulder;

[0009] The openable core body comprises a hollow shell, a low-pressure water flow gap is provided between the outer wall of the hollow shell and the knife sleeve, and an openable and closable valve body is provided in the hollow shell;

[0010] The rear end face of the pressure head is coaxially limitedly contacted with the front end face of the hollow shell and is fixedly connected with the front end face of the valve body; the front part of the switching sleeve is fixedly connected with the rear end face of the hollow shell.

[0011] Preferably, the valve body includes a spherical valve core and a valve core control switch, the valve core control switch includes an unlocking sleeve, an unlocking spring, a valve core fixing sleeve and an unlocking mechanism, the front end face of the valve core fixing sleeve is in limited sealing contact with the inner cavity of the hollow shell body, and the front end face of the valve core fixing sleeve is provided with a hollow threaded shaft, the front end face of the valve core fixing sleeve is threadedly connected to the rear end of the pressure head through the hollow threaded shaft, the unlocking spring sleeve is arranged on the front part of the outer wall of the valve core fixing sleeve, and the front end face of the unlocking spring is in limited contact with the inner cavity of the hollow shell body, the upper and lower ends of the valve core are respectively provided with valve stems, the valve core is arranged in the valve core fixing sleeve and is fixed to the valve core through the valve stems at both ends. The sleeve is rotatably connected; the two valve stems of the valve core extend outward respectively and are provided with concentric gears; the unlocking sleeve is partially sleeved on the rear part of the outer wall of the valve core fixing sleeve, a water gap is provided between the outer wall of the unlocking sleeve and the inner wall of the hollow shell, and a low-pressure water through hole connecting the inner and outer walls is provided in the middle of the hollow shell; two long grooves are provided on the outer wall of the front part of the unlocking sleeve, and the gears on the two valve stems of the valve core are respectively correspondingly arranged in a long groove, and a straight rack meshing with the gear is fixedly provided on one side wall of the two long grooves; the rear end face of the unlocking spring is in contact with the front end face of the unlocking sleeve;

[0012] The unlocking mechanism comprises a plurality of long holes uniformly distributed in the circumferential direction on the front side wall of the unlocking sleeve, and a locking piece, a pin shaft and a torsion spring corresponding to the number of the long holes. The locking piece is arc-shaped, a locking piece is arranged in each long hole, the middle part of the locking piece is rotatably connected to the long hole through the pin shaft, and the torsion spring is arranged on the pin shaft and is used to control the locking piece to rotate around the pin shaft; the inner wall of the rear of the hollow shell is provided with an annular groove;

[0013] In the initial state, the unlocking spring is in a compressed state, and the outer end of the locking plate is in contact with the inner wall of the annular groove of the hollow shell under the action of the torsion spring, the valve core is in a closed state, and the diameter of the circular area surrounded by the inner end faces of multiple locking plates is smaller than the outer diameter of the screen tube; in the open state, the unlocking spring is reset, and the spur rack in the unlocking sleeve drives the gear on the valve core to rotate, thereby driving the valve core to open, and the outer end of the locking plate is in contact with the inner wall of the hollow shell, and the diameter of the circular area surrounded by the inner end faces of multiple locking plates is greater than or equal to the outer diameter of the screen tube.

[0014] Preferably, the inner joint is provided with an inner conical thread section threadedly connected to the hollow drill rod; and the outer joint is provided with an outer conical thread section threadedly connected to the drill bit.

[0015] The working principle of this application is as follows: 1. According to the water inlet pressure, the high-low pressure switching mechanism can switch the water circuit between high-pressure water and low-pressure water; 2. After the punching operation, when the screen needs to be lowered, the locking plate will be pushed by the front end of the screen, and the locking plate will be stretched open by the torsion spring, and the outer end of the locking plate will be separated from the inner wall of the annular groove of the hollow shell. Under the action of the unlocking spring, the unlocking sleeve moves backward, and the spur rack in the unlocking sleeve drives the gear on the valve core to rotate, thereby driving the valve core to open, and then the hole protection screen is lowered. Thereby, after hydraulic punching, the hole protection screen can be quickly lowered without retracting the drill. By directly lowering the screen to protect the hole without retracting the drill after drilling, it not only solves the problem of hole collapse in soft coal seams, but also solves the problems of the depth of the screen after retracting the drill and the low efficiency of the screen under the bare hole, thereby improving the gas extraction effect and construction efficiency.

[0016] The beneficial effects of the present application are: simple structure, high reliability, conducive to improving drilling technology, improving hole quality, and increasing the drilling qualification rate, thereby promoting the reduction of drilling offset distance, helping to reduce the blank zone of gas extraction, improving gas extraction effect, and ensuring safe production in mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention.

[0018] Figure 2 It is a schematic structural diagram of the valve body of the present invention in a closed state.

[0019] Figure 3 for Figure 2 AA view of the .

[0020] Figure 4 It is a schematic structural diagram of the valve body of the present invention in an open state.

[0021] Figure 5 for Figure 4 BB view.

[0022] Figure 6 It is a state schematic diagram of the present invention under low pressure water state.

[0023] Figure 7 It is a schematic diagram of the state of the present invention under high pressure water state.

[0024] Figure 8 It is a schematic diagram of the state of the present invention when the screen pipe is lowered. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0026] like Figure 1 A coal seam hydraulic pressure relief hole protection drill shown in the figure comprises an inner joint 1, an outer joint 2, a high and low pressure switching mechanism, an openable core 3 and a cutter sleeve 4, wherein the inner joint and the outer joint are respectively arranged at both ends of the cutter sleeve and are respectively connected to the cutter sleeve by threads; the inner joint, the outer joint and the cutter sleeve are all internal water-permeable cavities,

[0027] The high-low pressure switching mechanism includes a piston and a switching sleeve 6, the switching sleeve is sealed and movably connected to the inner wall of the inner joint, and a high-pressure nozzle 7 communicating with the water-passing inner cavity is provided on the side wall of the inner joint; the piston includes a reset spring 8 and a pressure head 9, the reset spring is limited and fixed in the water-passing inner cavity of the outer joint, the pressure head is a hollow shaft, an outwardly convex shaft shoulder is provided in the middle of the outer wall of the pressure head, the front end face of the pressure head is crimped to one end of the reset spring, and a hole shoulder matching with the pressure head shaft shoulder is provided in the water-passing inner cavity of the outer joint; a low-pressure water through hole 10 leading from the outer wall to the center is provided on the shaft body between the front end face of the pressure head and the shaft shoulder;

[0028] The openable core body 3 comprises a hollow shell 301, a first low-pressure water flow gap 302 is provided between the outer wall of the hollow shell and the knife sleeve, and an openable and closable valve body 303 is provided in the hollow shell;

[0029] The rear end face of the pressure head is coaxially limitedly contacted with the front end face of the hollow shell and is fixedly connected with the front end face of the valve body; the front part of the switching sleeve is fixedly connected with the rear end face of the hollow shell.

[0030] Specifically, Figure 2 Figure 3As shown, the valve body 303 includes a spherical valve core 3031 and a valve core control switch, and the valve core control switch includes an unlocking sleeve 3032, an unlocking spring 3033, a valve core fixing sleeve 3034 and an unlocking mechanism, the front end face of the valve core fixing sleeve is in limited sealing contact with the inner cavity of the hollow shell body, and the front end face of the valve core fixing sleeve is provided with a hollow threaded shaft 15, the front end face of the valve core fixing sleeve is threadedly connected with the rear end of the pressure head through the hollow threaded shaft, the unlocking spring sleeve is provided at the front part of the outer wall of the valve core fixing sleeve, and the front end face of the unlocking spring is in limited contact with the inner cavity of the hollow shell body, the upper and lower ends of the valve core are respectively provided with valve stems 3035, the valve core is provided in the valve core fixing sleeve and is rotatably connected with the valve core fixing sleeve through the valve stems at both ends; The two valve stems of the valve core extend outwards respectively and are provided with concentric gears 3036; the unlocking sleeve is partially sleeved on the rear part of the outer wall of the valve core fixing sleeve, a second low-pressure water flow gap 3037 is provided between the outer wall of the unlocking sleeve and the inner wall of the hollow shell, and a low-pressure water flow through hole 3038 connecting the first low-pressure water flow gap and the second low-pressure water flow gap is provided in the middle of the hollow shell; two long grooves are provided on the outer wall of the front part of the unlocking sleeve, and the gears on the two valve stems of the valve core are respectively correspondingly arranged in a long groove, and a straight rack 3039 meshing with the gear is fixedly provided on one side wall of the two long grooves; the rear end face of the unlocking spring is in contact with the front end face of the unlocking sleeve;

[0031] The unlocking mechanism comprises a plurality of long holes 11 uniformly distributed in the circumferential direction on the front side wall of the unlocking sleeve, and a locking piece 12, a pin 13 and a torsion spring 14 corresponding to the number of the long holes. The locking piece is arc-shaped, and a locking piece is arranged in each long hole. The middle part of the locking piece is rotatably connected to the long hole through the pin. The torsion spring is arranged on the pin and is used to control the locking piece to rotate around the pin. The inner wall of the rear part of the hollow shell 301 is provided with an annular groove 3011;

[0032] In the initial state, the unlocking spring is in a compressed state, the outer end of the locking plate contacts the inner wall of the annular groove of the hollow shell under the action of the torsion spring, the valve core is in a closed state, and the diameter of the circular area surrounded by the inner end faces of the multiple locking plates is smaller than the outer diameter of the screen tube ( Figure 3 The dotted circle in the middle is the outer contour of the sieve tube);

[0033] like Figure 4 Figure 5 As shown, in the open state, the unlocking spring is reset, and the spur rack in the unlocking sleeve drives the gear on the valve core to rotate, thereby driving the valve core to open, and the outer end of the locking plate abuts against the inner wall of the hollow shell. The diameter of the circular area surrounded by the inner end faces of multiple locking plates is greater than or equal to the outer diameter of the screen tube.

[0034] Specifically, the inner joint is provided with an inner conical thread section which is threadedly connected to the hollow drill rod; and the outer joint is provided with an outer conical thread section which is threadedly connected to the drill bit.

[0035] The specific use method of this embodiment is as follows: when the coal seam hydraulic pressure relief hole drill of the present application is used, the outer joint is screwed to the hollow drill bit, and the inner joint is screwed to the hollow spiral drill rod, such as Figure 6 As shown ( Figure 6 The drill bit and drill rod are omitted in the figure). During the drilling process of the drilling rig, compressed air or low-pressure water is introduced to remove powder and slag. The direction of the arrow in the figure is the path of low-pressure water (the compressed air path and the low-pressure water path are the same and omitted). Under the action of low-pressure water, the pressure head is pushed to compress the reset spring 8, so that the pressure head shoulder is located between point C and point D, so that the low-pressure water flow can pass. At the same time, in this process, the pressure head 9 drives the openable core body 3 and the switching sleeve 6 to move forward as a whole. At this time, the valve body in the openable core body 3 is in a closed state; in this process, the path of the low-pressure water flow is the inner joint 1→switching sleeve 6→the second low-pressure water water gap 3037→the low-pressure water water through hole 3038→the first low-pressure water water gap 302→the low-pressure water through hole 10→the outer joint 2;

[0036] The construction technology of punching and drilling is adopted. When the drilling rig drills to the first punching point, the clean water pump is turned on to increase the water inlet pressure. When the water pressure reaches a high pressure of more than 6MPa, the hydraulic punching and cutting mode is turned on. Figure 7 As shown, high-pressure water pushes the pressure head, so that the pressure head shoulder presses against point D. At this time, the low-pressure water on the pressure head is closed through 10, and the pressure head 9 drives the openable core body 3 and the switching sleeve 6 to move forward as a whole, and the high-pressure nozzle 7 is exposed. High-pressure water is sprayed from the high-pressure nozzle 7 (the arrow is the direction of water flow) to perform hydraulic punching and slitting. In this state, the valve body in the openable core body 3 is in a closed state.

[0037] After the punching and cutting is completed, there is no need to withdraw the drill. After the drill pipe is lifted 2m from the bottom of the hole, the high-pressure water whip is removed and the screen pipe is lowered. The front end of the screen pipe is conical, such as Figure 4 Figure 5 Figure 8 As shown, when the front end of the screen tube abuts against the locking plate 12 of the unlocking mechanism, the screen tube head pushes the locking plate 12, and the locking plate rotates around the pin shaft and disengages from the annular groove 3011 provided on the rear inner wall of the hollow shell 301. After that, under the recovery of the unlocking spring, the unlocking sleeve moves backward, and the spur gear on it drives the gear on the valve core to rotate, thereby driving the valve core to open, and the outer end of the locking plate abuts against the inner wall of the hollow shell. The diameter of the circular area surrounded by the inner end faces of multiple locking plates is greater than or equal to the outer diameter of the screen tube. After that, the screen tube can pass through the coal seam hydraulic pressure relief hole drill and then penetrate into the borehole through the drill bit. The "dovetail" wing of the bottom suspension device of the screen tube is opened and hung upside down on the hole wall, which can fix the screen tube at the bottom of the hole. The average insertion depth of the hole-protecting screen tube reaches more than 95% of the hole depth. Finally, the screen tube is left in the hole, and the hole is quickly sealed and pumped out. According to the drilling construction and sealing conditions, the borehole is managed by hanging a sign.

[0038] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A coal seam hydraulic pressure relief hole protection drill, characterized in that: It includes an inner joint, an outer joint, a high-low pressure switching mechanism, an openable core body and a knife sleeve. The inner joint and the outer joint are respectively arranged at both ends of the knife sleeve and are respectively connected to the knife sleeve by threads; the inner joint, the outer joint and the knife sleeve are all water-permeable cavities, the inner joint is provided with an inner cone thread section that is threadedly connected to the hollow drill rod; the outer joint is provided with an outer cone thread section that is threadedly connected to the drill bit; The high-low pressure switching mechanism includes a piston and a switching sleeve, the switching sleeve is sealed and movably connected to the inner wall of the inner joint, and a high-pressure nozzle communicating with the water-passing inner cavity is provided on the side wall of the inner joint; the piston includes a return spring and a pressure head, the return spring is limited and fixed in the water-passing inner cavity of the outer joint, the pressure head is a hollow shaft, an outwardly convex shaft shoulder is provided in the middle of the outer wall of the pressure head, the front end face of the pressure head is crimped to one end of the return spring, and a hole shoulder matching with the pressure head shaft shoulder is provided in the water-passing inner cavity of the outer joint; a low-pressure water passing hole leading from the outer wall to the center is provided on the shaft body between the front end face of the pressure head and the shaft shoulder; The openable core body comprises a hollow shell, a low-pressure water flow gap is provided between the outer wall of the hollow shell and the knife sleeve, and an openable and closable valve body is provided in the hollow shell; the valve body comprises a spherical valve core and a valve core control switch, and the valve core control switch comprises an unlocking sleeve, an unlocking spring, a valve core fixing sleeve and an unlocking mechanism, the front end face of the valve core fixing sleeve is in limited sealing contact with the inner cavity of the hollow shell and the front end face of the valve core fixing sleeve is provided with a hollow threaded shaft, the front end face of the valve core fixing sleeve is threadedly connected with the rear end of the pressure head through the hollow threaded shaft, the unlocking spring sleeve is provided at the front part of the outer wall of the valve core fixing sleeve and the front end face of the unlocking spring is in limited contact with the inner cavity of the hollow shell, and valve stems are provided at the upper and lower ends of the valve core, respectively. The valve core is arranged in the valve core fixing sleeve and is rotatably connected with the valve core fixing sleeve through the valve stems at both ends; the two valve stems of the valve core extend outward respectively and are provided with concentric gears; the unlocking sleeve is partially sleeved on the rear part of the outer wall of the valve core fixing sleeve, a water gap is provided between the outer wall of the unlocking sleeve and the inner wall of the hollow shell, and a low-pressure water through hole connecting the inner and outer walls is provided in the middle of the hollow shell; two long grooves are provided on the outer wall of the front part of the unlocking sleeve, and the gears on the two valve stems of the valve core are respectively arranged in a long groove, and a straight rack meshing with the gear is fixed on one side wall of the two long grooves; the rear end face of the unlocking spring is in contact with the front end face of the unlocking sleeve; The unlocking mechanism comprises a plurality of long holes uniformly distributed in the circumferential direction on the front side wall of the unlocking sleeve, and a locking piece, a pin shaft and a torsion spring corresponding to the number of the long holes. The locking piece is arc-shaped, a locking piece is arranged in each long hole, the middle part of the locking piece is rotatably connected to the long hole through the pin shaft, and the torsion spring is arranged on the pin shaft and is used to control the locking piece to rotate around the pin shaft; the inner wall of the rear of the hollow shell is provided with an annular groove; In the initial state, the unlocking spring is in a compressed state, and the outer end of the locking plate is in contact with the inner wall of the annular groove of the hollow shell under the action of the torsion spring, the valve core is in a closed state, and the diameter of the circular area surrounded by the inner end faces of the multiple locking plates is smaller than the outer diameter of the screen tube; in the open state, the unlocking spring is reset, and the spur rack in the unlocking sleeve drives the gear on the valve core to rotate, thereby driving the valve core to open, and the outer end of the locking plate is in contact with the inner wall of the hollow shell, and the diameter of the circular area surrounded by the inner end faces of the multiple locking plates is greater than or equal to the outer diameter of the screen tube; The rear end face of the pressure head is coaxially limitedly contacted with the front end face of the hollow shell and is fixedly connected with the front end face of the valve body; the front part of the switching sleeve is fixedly connected with the rear end face of the hollow shell.

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