Coal seam high pressure water jet cutting device and method of use thereof

Abstract

The present application belongs to the technical field of coal mine safety, and relates to a coal seam high-pressure water jet cutting device and a use method thereof, comprising a cutting device body and a function conversion mechanism; the cutting device body has a cylindrical inner cavity accommodating the function conversion mechanism, and at least three axial function round holes communicating with the cylindrical inner cavity; the function conversion mechanism comprises a valve core, a function conversion sliding channel sleeve and an elastic member, at least three elastic guide protruding columns radially extending are arranged on the outer wall of the valve core, a sinusoidal wave arc-shaped structure sliding groove matched with the elastic guide protruding columns is arranged on the inner wall of the function conversion sliding channel sleeve, a step structure is arranged at the function groove of the groove, so that the valve core always rotates in the same direction when the elastic guide protruding column slides in the sliding groove; by controlling the opening and closing of high-pressure water, the sequential switching of different multiple cutting functions is realized. The present application is stable and reliable in function conversion, simple in operation, high in efficiency, and has wide popularization and application value.

Description

Technical Field

[0001] This invention belongs to the field of coal mine safety technology and relates to a high-pressure water jet cutting device for coal seams and its usage method. Background Technology

[0002] The permeability of coal seams in my country is generally low, posing a significant challenge to efficient gas extraction in coal mines. Furthermore, with increasing mining depth, the problems of high gas pressure, high ground stress, and low permeability in coal seams become more pronounced, significantly increasing the risks of excessive gas outbursts and coal and gas outbursts, thus becoming a major obstacle to safe and efficient coal mine production in my country. Hydraulic slotting technology can be widely applied to pressure relief and permeability enhancement in working faces of high-stress, high-gas, and low-permeability coal seams, and is an important technical method for efficient underground gas extraction and prevention of coal and gas outbursts in coal mines.

[0003] Waterjet cutting devices are key components of hydraulic kerfing technology. Conventional waterjet cutting devices typically use high-pressure water to push a valve core to slide and seal the water flow channel, achieving high-low pressure switching for drilling and kerfing functions, thus meeting the integrated drilling and cutting requirements. However, the function switching water pressure threshold of this design depends on the stiffness and deformation length of the return spring. Due to the characteristics of component machining precision and spring dispersion, the high-low pressure switching threshold is difficult to control precisely. In field applications, situations such as difficulty in function switching or unexpected switching due to water flow fluctuations can easily occur, leading to reduced work efficiency due to drill withdrawal and maintenance. Furthermore, the high-low pressure switching threshold setting limits the allowable water flow during drilling, restricting the applicable coal seam range and working conditions for integrated drilling and cutting. In addition, the intelligentization of coal mine safety technology places higher demands on the accuracy and reliability of the device, and conventional designs are no longer sufficient to meet the high-precision and high-reliability requirements of intelligent hydraulic kerfing technology for the waterjet function switching of the cutting device. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a coal seam high-pressure water jet cutting device and its usage method, improve the accuracy and reliability of water jet function conversion, broaden the applicable engineering geological conditions of the water jet cutting device, and improve the working efficiency of hydraulic cutting technology.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A high-pressure water jet cutting device for coal seams includes a cutting device body and a function conversion mechanism. The cutting device body has a cylindrical cavity that accommodates the function conversion mechanism and at least three axial functional holes communicating with the cylindrical cavity. The axial functional holes are arranged on the side of the cylindrical cavity near the front end of the cutting device body. At least two radial holes communicating with different axial functional holes are provided on the side wall of the cutting device body. The radial holes are connected to nozzles, and the nozzles connected to each radial hole have different diameters. A drill bit is connected to the front end of the cutting device body. A drilling water passage is provided in the cutting device body, one end of which communicates with the drill bit. The other end of the drilling water passage communicates with one of the axial functional holes.

[0007] The function switching mechanism includes a valve core, a function switching slide sleeve, and an elastic element. The valve core has a through circular hole. The function switching slide sleeve is fixedly installed in the inner cavity of the cylinder. The valve core is slidably installed in the function switching slide sleeve. One end of the elastic element is connected to the valve core, and the other end is connected to the end of the inner cavity of the cylinder that has an axial functional circular hole, so as to push the valve core away from the end of the inner cavity of the cylinder that has an axial functional circular hole.

[0008] The outer wall of the valve core is provided with at least three radially extending elastic guide protrusions, and the inner wall of the function conversion slide sleeve is provided with a sliding groove that matches the elastic guide protrusions. Under the guidance of the sliding groove, the valve core rotates in the same direction when sliding forward and backward in the axial direction. The sliding groove is composed of at least three groove sub-units connected in a loop, and the number of groove sub-units is equal to the number of axial functional holes, so that each time the valve core abuts against the end of the cylinder cavity connected to the axial functional hole, the valve core through hole is sequentially aligned with multiple axial functional holes.

[0009] The elastic guide post includes a pin and a compression elastic element. One end of the compression elastic element is fixedly connected to the valve core, and the other end is fixedly connected to the pin. The pin is inserted into the sliding groove. Each groove sub-unit is shaped like a sine wave, with a functional slot at the crest of the sine wave and a recovery slot at the trough. Both the functional slot and the recovery slot have stepped structures facing the same direction, so that when the elastic guide post slides in the sliding groove, it maintains unidirectional sliding to the same side, thereby ensuring that the valve core always rotates in the same direction.

[0010] Furthermore, a first central blind hole is provided at the front end of the cylindrical inner cavity, and a second central blind hole is provided at the end of the valve core near the first central blind hole. The two ends of the elastic element are respectively connected to the first central blind hole and the second central blind hole, and are rotatably connected to the first central blind hole and / or the second central blind hole.

[0011] Furthermore, the elastic element is a return spring, and the compression elastic element is a compression spring.

[0012] Furthermore, the stepped structure includes an inclined ramp arranged upward along the sliding direction of the elastically guiding protrusion and a step connected to the ramp and arranged downward.

[0013] Furthermore, let the number of the groove sub-units be n. When the elastic guide protrusion of the valve core slides through a complete groove sub-unit inside the sliding groove, the valve core rotates θ° in the same rotation direction, and θ = 360 / n.

[0014] Furthermore, the function conversion slide sleeve is installed in the inner cavity of the cylinder by a fixing structure. The fixing structure includes a shoulder, an annular groove, and a retaining ring for holes installed in the annular groove, all arranged on the inner wall of the inner cavity of the cylinder. The two ends of the function conversion slide sleeve are respectively connected to the shoulder and the retaining ring for holes.

[0015] Furthermore, the function conversion slide sleeve and the cylindrical inner cavity are connected by an interference fit or a key, so that the function conversion slide sleeve and the cylindrical inner cavity are circumferentially fixedly connected.

[0016] A method for using a high-pressure water jet cutting device for coal seams, comprising employing the aforementioned high-pressure water jet cutting device, wherein a high-pressure water drill rod is connected to the tail end of the cutting device body, and the method specifically includes the following steps:

[0017] a. When the high-pressure water is turned on, under the combined action of the high-pressure water flow and the sliding groove, the valve core slides and rotates towards the front end of the cutting device body, and then fits tightly against the front end of the cylindrical inner cavity. The axial through hole of the valve core is connected to any one of the multiple axial functional holes. The high-pressure water flows into the connected axial functional hole, and the other axial functional holes are blocked by the end face of the valve core. The water jet cutting device enters the preset functional state.

[0018] b. When a function switch is required, the high-pressure water is shut off. Under the combined action of the elastic element pushing and the sliding groove guiding, the valve core slides and rotates towards the tail end of the cutting device body, and the rotation direction is the same as the rotation direction in step a, so that all axial functional holes are in the open state.

[0019] c. Re-enable the high-pressure water. Under the combined action of the high-pressure water flow and the sliding groove, the valve core slides and rotates towards the front end of the cutting device body, and then fits tightly against the front end of the cylindrical inner cavity. The axial through hole of the valve core connects with the axial functional hole adjacent to the axial functional hole in step a. The high-pressure water flows into the connected axial functional hole, and the other axial functional holes are blocked by the end face of the valve core. The water jet cutting device enters the preset switching function state.

[0020] d. Repeatedly switch between multiple axial functional holes by controlling the opening and closing of high-pressure water.

[0021] Furthermore, there are three axial functional circular holes, two of which are connected to the first nozzle and the second nozzle respectively through radial circular holes, and the other axial functional circular hole is connected to the drilling water passage hole. The diameter of the first nozzle is larger than that of the second nozzle, so that the first nozzle is used as a hole-enlarging nozzle and the second nozzle is used as a slit cutter.

[0022] The axial functional holes connecting the drill bit, the first nozzle, and the second nozzle are arranged sequentially along the rotation direction of the valve core, so as to realize the sequential conversion of drilling-reaming-cutting functions by controlling the opening and closing of the high-pressure water flow.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention provides a high-pressure water jet cutting device for coal seams and its usage method. It employs a motion structure design combining valve core translation and rotation to achieve the opening and closing of different functional water flow channels. By controlling the supply and stop of high-pressure water flow, the device can sequentially switch between drilling, reaming, and kerf cutting functions. The functional switching of this cutting device does not rely on water pressure changes using conventional methods; the water jet function switching is precise and reliable, meeting the functional switching control requirements of intelligent hydraulic kerf cutting technology. Furthermore, the water flow rate allowed to pass through the cutting device is unrestricted in any functional state (drilling, reaming, kerf cutting). The integrated drilling, reaming, and cutting operation is applicable to all coal seam conditions and hole depths, significantly improving the efficiency of coal seam hydraulic kerf cutting operations. This invention is simple to operate, highly efficient, and effective, possessing significant economic benefits and widespread application value.

[0025] Furthermore, the present invention employs a sine wave-shaped sliding groove in conjunction with a stepped structure and an elastic guide protrusion to ensure the stability and reliability of the unidirectional sliding of the elastic guide protrusion at different groove positions, thereby ensuring the accuracy of function switching.

[0026] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0028] Figure 1This is a schematic diagram of the cutting device body in the embodiment when no high-pressure water passes through;

[0029] Figure 2 This is a schematic diagram of the cutting device body in the hole-expanding state in the embodiment.

[0030] Figure 3 for Figure 1 Schematic diagram of the cross-section BB;

[0031] Figure 4 for Figure 1 Schematic diagram of the interrupted surface AA;

[0032] Figure 5 This is an enlarged schematic diagram of an elastically guided convex pillar structure;

[0033] Figure 6 This is a planar unfolded schematic diagram of the sliding groove in the function conversion slide sleeve in the embodiment;

[0034] Figure 7 This is an enlarged schematic diagram of the functional slot structure.

[0035] Reference numerals: 1-Cut device body, 2-Annular groove, 3-Function conversion slide sleeve, 4-Valve core, 5-Shoulder, 6-Cylindrical inner cavity, 7-Reset spring, 8-Axial functional circular hole, 9-Radial circular hole, 10-First nozzle, 11-Drill bit, 12-Front end of cutting device, 13-Hole retaining ring, 14-Filter plate, 15-Guide protrusion, 151-Pin, 152-Compression spring, 16-Valve core through circular hole, 17-Second central blind hole, 18-First central blind hole, 19-Second nozzle, 20-Drilling water passage, 21-Sliding groove, 22-Drilling function slot, 23-Enlarging function slot, 24-Knife cutting function slot, 25-First recovery slot, 26-Second recovery slot, 27-Third recovery slot, 28-Step structure. Detailed Implementation

[0036] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0037] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0038] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0039] Please see Figures 1 to 7 This is a high-pressure water jet cutting device for coal seams, comprising a cutting device body 1, a first nozzle 10, a second nozzle 19, a drill bit 11, a function conversion mechanism, and a fixing structure; the cutting device body 1 has a cylindrical inner cavity 6 for accommodating the function conversion mechanism and three axial functional circular holes 8 communicating with the cylindrical inner cavity 6, and two radial circular holes 9 communicating with two of the axial functional circular holes 8 on the side wall; the first nozzle 10 and the second nozzle 19 are respectively installed in the two radial circular holes 9;

[0040] The tail end of the cutting device body 1 is connected to a high-pressure water drill rod. The drill bit 11 is threadedly installed at the front end 12 of the cutting device body 1. A drilling water passage 20 is arranged at the front end of the cutting device body 1, and the drilling water passage 20 is connected to another axial functional circular hole 8. The function conversion mechanism includes a valve core 4, a function conversion slide sleeve 3, and a return spring 7. The function conversion slide sleeve 3 is installed in the cylindrical inner cavity 6 through a fixed structure. The valve core 4 is rotatably installed in the function conversion slide sleeve 3 and slidably connected. One end of the return spring 7 is connected to the valve core 4, and the other end is connected to the front end of the cylindrical inner cavity 6 to limit the axial movement of the valve core 4.

[0041] Key references Figures 1-5The cylindrical inner cavity 6 has a central blind hole 18 concentric with it and three axial functional holes 8 distributed around the center at equal angles. The three axial functional holes 8 are respectively connected to water flow channels that realize different functions. The central blind hole 18 is used to install the return spring 7. The valve core 4 is a thick-walled cylindrical design with its opening facing the tail end of the cutting device body 1. One end of the valve core 4 is provided with a second central blind hole 17 and an axially penetrating valve core through hole 16. The second central blind hole 17 is matched with the first central blind hole 18 at the bottom of the cylindrical inner cavity of the cutting device body and is used to install the return spring 7. The return spring 7 is movably connected to the first central blind hole and / or the second central blind hole. The size and position of the valve core through hole 16 match the axial functional holes 8 at the bottom of the cylindrical inner cavity.

[0042] The valve core 4 is installed in the function conversion slide sleeve 3. Three radially extending elastic guide protrusions 15 are provided on the outer wall of the valve core 4. The elastic guide protrusions 15 are composed of pins 151 and springs 152. One end of the compression spring 152 is fixedly connected to the valve core 4, and the other end is fixedly connected to the pin 152, which can realize a certain amount of length extension and contraction of the elastic guide protrusions 15. The inner wall of the function conversion slide sleeve 3 is machined with sliding grooves 21 that match the elastic guide protrusions 15, so that the valve core 4 can always rotate to the same side when it performs axial reciprocating motion, thereby realizing the connection between the valve core through hole 16 and different axial functional holes 8.

[0043] The sliding groove 21 is composed of three groove sub-units connected in a loop, and the number of groove sub-units is equal to the number of axial functional circular holes 8 in the cutting device body, both being three. Each groove sub-unit adopts a sine wave shape, with different functional slots set at the crests and recovery slots set at the troughs. All slots are provided with stepped structures 28 facing the same direction, so that when the elastic guide protrusion 15 slides in different functional slots in the groove, it always maintains unidirectional sliding to the same side, thereby ensuring that the valve core 4 always rotates in the same direction; and When the elastic guide protrusion 15 of the valve core 4 slides from the drilling function slot 22 to the first restoration slot 25, the groove guides the valve core to rotate counterclockwise by 60° along the axial direction. When the elastic guide protrusion slides between different function slots (such as from the drilling function slot 22 to the hole enlarging function slot 23), the valve core rotates counterclockwise by 120°. The three axial function holes 8 are spaced at 120° intervals, so that the elastic guide protrusion 15 performs a water flow function switch once every time it slides a groove sub-unit in the sliding groove 21.

[0044] Specifically, such as Figure 5-7As shown, the compression spring 152 is installed through a blind hole on the outer circle of the valve core 4, and the depth of the blind hole is greater than the length of the compression spring 152, so that one end of the pin 151 is inserted into the blind hole, thereby ensuring the stability of the elastic guide protrusion 15. Secondly, the step height of the step structure 28 matches the compression length of the compression spring 152, so as to ensure that the elastic guide protrusion 15 always abuts against the sliding groove 21 and can pass smoothly through the step structure 28. The step structure 28 has a uniform orientation, and the step structure 28 includes an inclined upward slope along the sliding direction of the elastic guide protrusion 15 and a step connected to the slope and arranged downward, so as to ensure that when the elastic guide protrusion 15 slides in different functional slots in the groove, it maintains a unidirectional rightward sliding under the action of the step structure 28 and the sliding groove 21, thereby ensuring that the valve core 4 always rotates in the same direction.

[0045] When fluid exceeding a predetermined limit value (i.e., pressure exceeding the elastic force of the return spring 7, which is generally selected as a model with a smaller elastic force) is applied through a high-pressure water pipe at the inlet of the function conversion mechanism, i.e. the tail end of the cutting device body 1, the valve core 4 overcomes the elastic force applied to it by the return spring 7 and moves to the right, pressing against the bottom (right end) of the cylindrical inner cavity 6. After the high-pressure water is turned off, the valve core 4 moves to the left under the action of the return spring 7, thereby resetting.

[0046] The fixing structure includes a shoulder 5 arranged at the front end (near the drill bit 11) of the inner wall of the cylindrical cavity 6, an annular groove 2 arranged at the tail end, and a retaining ring 13 installed in the annular groove 2. One end of the function conversion slide sleeve 3 is fixed by the shoulder 5, and the other end is fixed by the retaining ring 13 installed in the annular groove 2 and the filter 14, thereby axially fixing the function conversion slide sleeve 3.

[0047] Preferably, the function conversion slide sleeve 3 and the cylindrical inner cavity 6 are connected by an interference fit or a key connection so that the function conversion slide sleeve 3 and the cylindrical inner cavity 6 are circumferentially fixedly connected.

[0048] Furthermore, the first nozzle 10 and the second nozzle 19 installed in the two radial circular holes 9 on the side wall of the cutting device body 1 have different diameters, namely, an enlarging nozzle and a slit-cutting nozzle, and the diameter of the enlarging nozzle is larger than that of the slit-cutting nozzle.

[0049] In another embodiment, the valve core 4 is cylindrical.

[0050] Application process in this embodiment:

[0051] like Figure 5As shown, before the high-pressure water is turned on, the elastic guide protrusion 15 is located in the sliding groove 21 on one side near the tail end of the cutting device body 1. When the high-pressure water is turned on, the valve core 4 slides to the right under the push of the high-pressure water flow from the tail end of the cutting device body 1, and rotates counterclockwise under the guidance of the elastic guide protrusion 15 and the sliding groove 21. When the valve core 4 is tightly fitted with the bottom of the cylindrical cavity 6, the valve core 4 rotates counterclockwise by 60°, and the axial through hole 16 matches and connects with the axial functional hole 8 that connects to the first nozzle 10. The other axial functional holes 8 are blocked by the end face of the valve core 4. At this time, the cutting device is in the hole expansion function state.

[0052] When the high-pressure water is turned off, under the combined action of the push of the return spring 7 and the guidance of the elastic guide protrusion 15 and the sliding groove 21, the valve core returns to its original position, slides to the left, and rotates counterclockwise by 60°, and all the axial functional holes 8 at the bottom of the cylindrical inner cavity 6 are in the open state.

[0053] When the high-pressure water is turned on again, the valve core 4 slides to the right again and rotates 60° counterclockwise. The valve core through hole 16 connects with the axial functional hole 8 that connects to the second nozzle 19. At this time, the cutting device is in the kerf cutting function state.

[0054] When the high-pressure water is turned off, under the combined action of the push of the return spring 7 and the guidance of the elastic guide protrusion 15 and the sliding groove 21, the valve core returns to its original position, slides to the left, and rotates counterclockwise by 60°, and all the axial functional holes 8 at the bottom of the cylindrical inner cavity 6 are in the open state.

[0055] When the high-pressure water is turned on again, the valve core 4 slides to the right again and rotates 60° counterclockwise. The valve core through hole 16 connects with the axial functional hole 8 that connects to the drilling water hole 20. At this time, the cutting device is in the drilling function state.

[0056] By repeatedly opening and closing the high-pressure water, the elastically guided protrusion 15 slides through a groove subunit, and the water flow channels of the circular holes 8 with different axial functions open and close in the order of "drilling-reaming-cutting", which can realize the sequential conversion of the drilling-reaming-cutting functions of the cutting device.

[0057] The above application process is exemplified by the case where the elastic guide post 15 is aligned with the axial functional hole 8 of the first nozzle 10 after being displaced to the right and rotated. However, it is not limited to this case. When the guide post 15 is located in the first interval restoration groove 26 or the second interval restoration groove 27, it can also be used as the initial position for function switching.

[0058] It should be noted that the above embodiments are three-function cutting devices for drilling, reaming, and kerf cutting. The sequence of function switching can be achieved by adjusting the connecting nozzles on the cutting device body. Furthermore, the number of functions of the cutting device can be adjusted by changing the number of axial functional holes at the bottom of the cylindrical cavity. For example, reducing one axial functional hole changes the cutting device to a two-function sequential cutting device for drilling and kerf cutting, or a two-function sequential cutting device for drilling and reaming. Alternatively, increasing the number of axial functional holes to four changes the cutting device to a four-function sequential cutting device for drilling, reaming, kerf cutting, and punching. It is important to note that when adding or removing axial functional holes, the groove sub-units in the sliding groove 21 should be adjusted accordingly to correspond one-to-one with the number of axial functional holes. Such variations are generally similar to the embodiments described above and will not be described in detail further.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high-pressure water jet cutting device for coal seams, characterized in that: The device includes a cutting device body and a function conversion mechanism. The cutting device body has a cylindrical cavity that accommodates the function conversion mechanism and at least three axial functional holes that communicate with the cylindrical cavity. The axial functional holes are arranged on the side of the cylindrical cavity near the front end of the cutting device body. At least two radial holes that communicate with different axial functional holes are provided on the side wall of the cutting device body. The radial holes are connected to nozzles, and the nozzles connected to each radial hole have different diameters. A drill bit is connected to the front end of the cutting device body. The cutting device body has a drilling water passage with one end communicating with the drill bit and the other end communicating with one of the multiple axial functional holes. The function switching mechanism includes a valve core, a function switching slide sleeve, and an elastic element. The valve core has a through circular hole. The function switching slide sleeve is fixedly installed in the inner cavity of the cylinder. The valve core is slidably installed in the function switching slide sleeve. One end of the elastic element is connected to the valve core, and the other end is connected to the end of the inner cavity of the cylinder that has an axial functional circular hole, so as to push the valve core away from the end of the inner cavity of the cylinder that has an axial functional circular hole. The outer wall of the valve core is provided with at least three radially extending elastic guide protrusions, and the inner wall of the function conversion slide sleeve is provided with a sliding groove that matches the elastic guide protrusions. Under the guidance of the sliding groove, the valve core rotates in the same direction when sliding forward and backward in the axial direction. The sliding groove is composed of at least three groove sub-units connected in a loop, and the number of groove sub-units is equal to the number of axial functional holes, so that each time the valve core abuts against the end of the cylinder cavity connected to the axial functional hole, the valve core through hole is sequentially aligned with multiple axial functional holes. The elastic guide post includes a pin and a compression elastic element. One end of the compression elastic element is fixedly connected to the valve core, and the other end is fixedly connected to the pin. The pin is inserted into the sliding groove. Each groove sub-unit is shaped like a sine wave, with a functional slot at the crest of the sine wave and a recovery slot at the trough. Both the functional slot and the recovery slot have stepped structures facing the same direction, so that when the elastic guide post slides in the sliding groove, it maintains unidirectional sliding to the same side, thereby ensuring that the valve core always rotates in the same direction.

2. The high-pressure water jet cutting device for coal seams according to claim 1, characterized in that: A first central blind hole is provided at the front end of the cylindrical inner cavity, and a second central blind hole is provided at the end of the valve core near the first central blind hole. The two ends of the elastic element are respectively connected to the first central blind hole and the second central blind hole, and are movably connected to the first central blind hole and / or the second central blind hole.

3. The high-pressure water jet cutting device for coal seams according to claim 1, characterized in that: The elastic element is a return spring, and the compression elastic element is a compression spring.

4. The high-pressure water jet cutting device for coal seams according to claim 1, characterized in that: The stepped structure includes an upwardly inclined ramp along the sliding direction of the elastically guiding protrusion and steps connected to the ramp and arranged downwards.

5. The high-pressure water jet cutting device for coal seams according to claim 1, characterized in that: Let the number of groove sub-units be n. When the elastic guide protrusion of the valve core slides through a complete groove sub-unit inside the sliding groove, the valve core rotates θ° in the same rotation direction, and θ = 360 / n.

6. The high-pressure water jet cutting device for coal seams according to claim 1, characterized in that: The function conversion slide sleeve is installed in the inner cavity of a cylinder by a fixing structure. The fixing structure includes a shoulder, an annular groove, and a retaining ring for holes installed in the annular groove, all arranged on the inner wall of the cylinder. The two ends of the function conversion slide sleeve are respectively connected to the shoulder and the retaining ring for holes.

7. The high-pressure water jet cutting device for coal seams according to claim 6, characterized in that: The function conversion slide sleeve and the cylindrical inner cavity are connected by an interference fit or a key, so that the function conversion slide sleeve and the cylindrical inner cavity are circumferentially fixedly connected.

8. A method of using a high-pressure water jet cutting device for coal seams, characterized in that: The method of using a high-pressure water jet cutting device for coal seams according to any one of claims 1 to 7, wherein a high-pressure water drill rod is connected to the tail end of the cutting device body, specifically includes the following steps: a. When the high-pressure water is turned on, under the combined action of the high-pressure water flow and the sliding groove, the valve core slides and rotates towards the front end of the cutting device body, and then fits tightly against the front end of the cylindrical inner cavity. The axial through hole of the valve core is connected to any one of the multiple axial functional holes. The high-pressure water flows into the connected axial functional hole, and the other axial functional holes are blocked by the end face of the valve core. The water jet cutting device enters the preset functional state. b. When a function switch is required, the high-pressure water is shut off. Under the combined action of the elastic element pushing and the sliding groove guiding, the valve core slides and rotates towards the tail end of the cutting device body, and the rotation direction is the same as the rotation direction in step a, so that all axial functional holes are in the open state. c. Re-enable the high-pressure water. Under the combined action of the high-pressure water flow and the sliding groove, the valve core slides and rotates towards the front end of the cutting device body, and then fits tightly against the front end of the cylindrical inner cavity. The axial through hole of the valve core connects with the axial functional hole adjacent to the axial functional hole in step a. The high-pressure water flows into the connected axial functional hole, and the other axial functional holes are blocked by the end face of the valve core. The water jet cutting device enters the preset switching function state. d. Repeatedly switch between multiple axial functional holes by controlling the opening and closing of high-pressure water.

9. The method of using the high-pressure water jet cutting device for coal seams according to claim 8, characterized in that: There are three axial functional circular holes. Two of the axial functional circular holes are connected to the first nozzle and the second nozzle respectively through radial circular holes. The other axial functional circular hole is connected to the drilling water passage. The diameter of the first nozzle is larger than that of the second nozzle, so that the first nozzle is used as a hole-enlarging nozzle and the second nozzle is used as a slit cutter. The axial functional holes connecting the drill bit, the first nozzle, and the second nozzle are arranged sequentially along the rotation direction of the valve core, so as to realize the sequential conversion of drilling-reaming-cutting functions by controlling the opening and closing of the high-pressure water flow.

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