A high-pressure water jet drilling-expanding-cutting multifunctional drill bit and use method thereof

Abstract

The present invention belongs to the field of coal mine safety technology, and relates to a high-pressure water jet drilling-expansion-cutting multifunctional drill bit and a method of using the same, including a drill bit body and a function conversion mechanism; the drill bit body has a cylindrical inner cavity for accommodating the function conversion mechanism, and a plurality of axial functional circular holes connected to the cylindrical inner cavity; the function conversion mechanism includes a valve core, a function conversion slideway sleeve, and an elastic member, the outer wall of the valve core is provided with at least two radially extending guide bosses, the inner wall of the function conversion slideway sleeve is provided with a sliding groove matching the guide bosses, and each groove subunit adopts an offset staggered structure at the "human" cross turning point, and under the guidance of the sliding groove, the valve core rotates in the same direction when sliding forward and backward axially. The present invention broadens the applicable coal seams and engineering conditions of the water jet cutting drill bit, greatly improves the working efficiency of the water jet cutting operation, and has significant economic benefits and promotion and application value.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine safety, and relates to a high-pressure water jet drilling-expansion-cutting multifunctional drill bit and a use method thereof. Background Art

[0002] The permeability of coal seams in my country is generally low, and low permeability has become a difficult problem that restricts the efficient extraction of coal seam gas in coal mines. In addition, as the mining depth gradually increases, the problems of high gas pressure, high ground stress, and low permeability in coal seams become more prominent. The risks of excessive gas outburst and coal and gas outbursts faced by coal mining have increased significantly, becoming an important problem that restricts the safe and efficient production of coal mines in my country. Hydraulic cutting technology can be widely used in the decompression and permeability enhancement of working faces in high ground stress, high gas, and low permeability coal seams. It is an important technical method for efficient extraction of gas and prevention and control of coal and gas outbursts in underground coal mines.

[0003] The water jet cutter / drill bit is a key device of hydraulic slitting technology. Conventional water jet cutters usually use high-pressure water to push the valve core to move and block the channel to achieve the closure of the water flow channel, realize the high-low pressure conversion of the drilling-slitting function, and meet the integrated drilling and cutting function requirements of low-pressure water drilling and high-pressure water slitting. However, the water pressure threshold of the function conversion of this type of design depends on the stiffness and deformation length of the reset spring. Due to the characteristics of component processing accuracy and spring discreteness, the high-low pressure conversion threshold is difficult to control accurately. During the field application, it is easy to have difficulty in function conversion or accidental conversion caused by water volume fluctuations, and the drill withdrawal and maintenance will reduce the operation efficiency. In addition, due to the setting of the high-low pressure conversion threshold, the water flow allowed to pass through the cutter during drilling is limited, and the applicable coal seam range and working conditions of drilling and cutting are limited. In addition, the intelligentization of coal mine safety technology has higher requirements for the accuracy and reliability of the device. Conventional designs can no longer meet the requirements of intelligent hydraulic slitting technology for high accuracy and high reliability of the cutter water jet function conversion. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a high-pressure water jet drilling-expanding-cutting multifunctional drill bit and a method of using it, so as to improve the accuracy and reliability of water jet function conversion, broaden the applicable engineering geological conditions of water jet cutting drill bits, and improve the working efficiency of hydraulic cutting technology.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A high-pressure water jet drilling-expansion-cutting multifunctional drill bit, comprising a drill bit body and a function conversion mechanism, wherein the drill bit body is provided with a cylindrical inner cavity for accommodating the function conversion mechanism, and a plurality of axial functional circular holes communicated with the cylindrical inner cavity, and the axial functional circular holes are arranged on one side of the cylindrical inner cavity close to the front end of the drill bit body, and a plurality of radial circular holes communicated with different axial functional circular holes are arranged on the side wall of the drill bit body, the radial circular holes are connected with nozzles, and the apertures of the nozzles connected to each of the radial circular holes are different, and a drilled water hole is also provided in the drill bit body, one end of which is communicated with the end of the drill bit body, and the other end of the drilled water hole is communicated with one of the plurality of axial functional circular holes;

[0007] The function conversion mechanism comprises a valve core, a function conversion slide sleeve and an elastic member, wherein the valve core has a valve core through-hole, the function conversion slide sleeve is fixedly installed in the cylindrical inner cavity, the valve core is slidably installed in the function conversion slide sleeve, one end of the elastic member is connected to the valve core, and the other end is connected to one end of the cylindrical inner cavity connected to the axial function circular hole, so as to push the valve core away from the end of the cylindrical inner cavity connected to the axial function circular hole;

[0008] At least two radially extending guide bosses are provided on the outer wall of the valve core, and a sliding groove matching the guide bosses is provided on the inner wall of the function conversion slide sleeve. Under the guidance of the sliding groove, the valve core rotates in the same direction during forward axial sliding and backward axial sliding. The sliding groove is composed of at least two groove sub-units that are cyclically connected, and the number of groove sub-units is equal to the number of axial functional circular holes, so that each time the valve core abuts against one end of the cylindrical inner cavity connected to the axial functional circular hole, the through-hole of the valve core is aligned with multiple axial functional circular holes in sequence.

[0009] Furthermore, a first central blind hole is provided at the front end of the cylindrical inner cavity, a second central blind hole is provided at an end of the valve core close to the first central blind hole, and both ends of the elastic member 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.

[0010] Furthermore, the elastic member is a return spring.

[0011] Furthermore, each groove subunit is formed by a combination of a "human" shaped groove and an inverted "human" shaped groove, and an offset staggered structure is adopted at the "human" intersection, so that the guide boss maintains unidirectional sliding when sliding up and down in the sliding groove, so that the valve core always rotates in the same direction.

[0012] Furthermore, assuming that the number of the groove subunits is n, when the guiding protrusion of the valve core slides through a complete groove subunit in the sliding groove, the valve core rotates θ° in the same rotation direction, and θ=360 / n.

[0013] Furthermore, the function conversion slide sleeve is installed in the cylindrical inner cavity through a fixing structure, and the fixing structure includes a step structure arranged on the inner wall of the cylindrical inner cavity, an annular groove, and a hole retaining ring installed in the annular groove, and the two ends of the function conversion slide sleeve are respectively connected to the step structure and the hole retaining ring.

[0014] Furthermore, the function conversion slide sleeve and the cylindrical inner cavity are connected by interference fit or key connection, so that the function conversion slide sleeve and the cylindrical inner cavity are circumferentially fixedly connected.

[0015] A method for using a high-pressure water jet drilling-expanding-cutting multifunctional drill bit, using the above-mentioned high-pressure water jet drilling-expanding-cutting multifunctional drill bit, wherein the tail end of the drill bit body is connected to high-pressure water, and the cutting method specifically comprises the following steps:

[0016] a. The high-pressure water is turned on. Under the combined effect of the high-pressure water flow and the guidance of the sliding groove, the valve core slides toward the front end of the drill body and rotates, and then fits tightly with the front end of the cylindrical inner cavity. The axial through hole of the valve core is connected with any one of the multiple axial functional holes, and the high-pressure water flows into the connected axial functional hole. The other axial functional holes are blocked by the end face of the valve core, and the water jet cutting drill enters the preset functional state;

[0017] b. When the function needs to be switched, the high-pressure water is turned off, and under the combined action of the elastic member pushing and the sliding groove guiding, the valve core slides toward the tail end of the drill body and rotates, and the rotation direction is the same as the rotation direction in step a, so that all axial functional holes are in an open state;

[0018] c. Turn on the high-pressure water again. Under the combined effect of the high-pressure water flow and the guidance of the sliding groove, the valve core slides and rotates toward the front end of the drill body, and then fits tightly with the front end of the cylindrical inner cavity. The axial through hole of the valve core is connected with the axial functional hole adjacent to the axial functional hole connected in step a. High-pressure water flows into the connected axial functional hole, and the remaining axial functional holes are blocked by the end face of the valve core. The water jet cutting drill enters the preset switching functional state;

[0019] d. Repeat the cycle to control the opening and closing of high-pressure water to achieve sequential switching of multiple axial functional holes.

[0020] 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 drill bit, and the aperture of the first nozzle is larger than the aperture of the second nozzle, so that the first nozzle is used as a hole expansion nozzle and the second nozzle is used as a slit;

[0021] Among them, the axial functional circular hole connected to the drill bit, the axial functional circular hole connected to the first nozzle and the axial functional circular hole connected to the second nozzle are arranged in sequence along the rotation direction of the valve core, so as to realize the sequential conversion of the drilling-expansion-cutting functions of the water jet cutting drill bit by controlling the opening and closing of the high-pressure water flow.

[0022] The beneficial effects of the present invention are:

[0023] The present invention provides a high-pressure water jet drilling-expansion-cutting multifunctional drill bit and a method for using the same. The motion structure design combining the translation and rotation of the valve core is used to realize the opening and closing of water flow channels with different functions. By controlling the supply and stop of the high-pressure water flow, the sequential conversion of the drilling, reaming and slitting functions of the cutting drill bit can be realized. The functional conversion of the cutting drill bit does not rely on the water flow pressure change of the conventional method. The water jet functional conversion is accurate and reliable, which can meet the functional conversion control requirements of the intelligent hydraulic slitting technology for the cutting drill bit. Moreover, the water flow rate allowed to pass through the cutting drill bit in any functional state of drilling, reaming and slitting is not restricted. The integrated operation of drilling, expanding and cutting can be applied to all coal seam conditions and hole depth conditions, which can greatly improve the working efficiency of coal seam hydraulic slitting operations. The present invention is easy to operate, highly efficient, and has good use effect, and has significant economic benefits and promotion and application value.

[0024] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 It is a schematic diagram of the structure of a high-pressure water jet drilling-expanding-cutting multifunctional drill bit in a state where no high-pressure water passes through;

[0027] Figure 2 for Figure 1 Schematic diagram of cross section BB;

[0028] Figure 3 for Figure 1Schematic diagram of cross section AA;

[0029] Figure 4 It is a planar development schematic diagram of the sliding groove in the function conversion slideway sleeve in the embodiment;

[0030] Figure 5 Schematic diagram of the structure of the cutting drill bit in the hole enlarging state in the embodiment.

[0031] Figure numerals: 1-drill bit body, 2-annular groove, 3-function conversion slide sleeve, 4-valve core, 5-step structure, 6-cylindrical inner cavity, 7-reset spring, 8-axial functional circular hole, 9-radial circular hole, 10-first nozzle, 11-front end of drill bit, 12-drill teeth, 13-hole retaining ring, 14-filter plate, 15-guide boss, 16-valve core through hole, 17-second center blind hole, 18-first center blind hole, 19-second nozzle, 20-drilling water hole, 21-sliding groove. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways 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 only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0033] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0034] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0035] See also Figure 1 to Figure 5 , which is a high-pressure water jet drilling-expansion-cutting multifunctional drill bit, comprising a drill bit body 1, a first nozzle 10, a second nozzle 19, a drill bit front end 11, a function conversion mechanism and a fixing structure; the drill bit body 1 is provided with a cylindrical inner cavity 6 for accommodating the function conversion mechanism and three axial functional circular holes 8 connected with the cylindrical inner cavity 6, and two radial circular holes 9 connected with two of the axial functional circular holes 8 are provided on the side wall; the first nozzle 10 and the second nozzle 19 are respectively installed in the two radial circular holes 9;

[0036] The tail end of the drill body 1 is connected to the high-pressure water pipeline, and the front end 11 of the drill bit of the drill body 1 is arranged with a drilled water hole 20, and the drilled water hole 20 is connected to another axial functional circular hole 8, and the end of the front end 11 of the drill bit is provided with a drill bit pick 12 to facilitate the drilling of the drill bit; the function conversion mechanism includes a valve core 4, a function conversion slide sleeve 3 and a reset spring 7, the function conversion slide sleeve 3 is installed in the cylindrical 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 reset spring 7 is connected to the valve core 4, and the other end is connected to the front end of the cylindrical cavity 6 to limit the axial position of the valve core 4.

[0037] Key References Figure 1 to Figure 3 The bottom of the cylindrical inner cavity 6 is provided with a concentric central blind hole 18 and three axial functional circular holes 8 distributed around the center and at equal angles. The three axial functional circular holes 8 are respectively connected to water flow channels for realizing different functions, and the central blind hole 18 is used to install the reset spring 7; the valve core 4 is designed to be cylindrical, and 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 matches the position of the first central blind hole 18 at the bottom of the cylindrical inner cavity of the drill body, and is used to install the reset spring 7, and the reset spring 7 is movably connected to the first central blind hole and / or the second central blind hole, and the size and position of the valve core through hole 16 match the axial functional circular hole 8 at the bottom of the cylindrical inner cavity.

[0038] The valve core 4 is installed in the function conversion slide sleeve 3, and three radially extending guide bosses 15 are arranged on the outer wall of the valve core 4. The guide bosses 15 are fixed to the valve core 4 by means of a screw structure. A sliding groove 21 matching the guide bosses 15 is processed on the inner wall of the function conversion slide sleeve 3, so that the valve core 4 can always rotate to the same side when performing axial reciprocating motion, thereby realizing the connection between the valve core through hole 16 and different axial functional holes 8.

[0039] like Figure 4As shown, the sliding groove 21 is composed of three groove sub-units connected in a loop, and the number of the groove sub-units is equal to the number of the axial functional circular holes 8 in the drill body, which are both three; each groove sub-unit is formed by a combination of a "human"-shaped groove and an inverted "human"-shaped groove, and the groove adopts an offset staggered structure at the "human" intersection, so that the guiding protrusion 15 always maintains a unidirectional sliding to the right when sliding up and down in the groove, thereby ensuring that the valve core 4 always rotates to the same side; and when the guiding protrusion 15 of the valve core 4 slides through a "human" structure inside the sliding groove, the groove guides the valve core to rotate 60° counterclockwise along the groove, and rotates 120° when sliding through a complete groove sub-unit; the three axial functional circular holes 8 are spaced at an angle of 120°, so that the water flow function is switched every time the guiding protrusion 15 slides one groove sub-unit in the sliding groove 21.

[0040] When a fluid higher than a predetermined limit value (i.e., a pressure higher than the elastic force of the reset spring 7) is applied through a high-pressure water pipeline at the inlet of the function conversion mechanism, i.e., the tail end of the drill bit body 1, the valve core 4 overcomes the elastic force applied by the reset spring 7 and moves to the right, pressing on 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 reset spring 7, thereby resetting.

[0041] The fixing structure includes a step structure 5 arranged at the front end of the inner wall of the cylindrical inner cavity 6 (the end close to the drill end 11), an annular groove 2 arranged at the rear end, and a hole clamping ring 13 installed in the annular groove 2. One end of the function conversion slideway sleeve 3 is fixed by the step structure 5, and the other end is fixed by the hole clamping ring 13 and the filter plate 14 installed in the annular groove 2, so as to axially fix the function conversion slideway sleeve 3;

[0042] Preferably, the function conversion slideway sleeve 3 and the cylindrical inner cavity 6 are connected by interference fit or key connection so that the function conversion slideway sleeve 3 and the cylindrical inner cavity 6 are fixedly connected circumferentially.

[0043] Furthermore, the first nozzle 10 and the second nozzle 19 installed in the two radial circular holes 9 on the side wall of the drill body 1 have different apertures, namely, a hole expansion nozzle and a slotting nozzle, and the aperture of the hole expansion nozzle is larger than that of the slotting nozzle.

[0044] In another embodiment, the valve core 4 is designed to be thick-walled cylindrical.

[0045] The application process of this embodiment:

[0046] like Figure 5As shown, before the high-pressure water is turned on, the guide boss 15 is located on one side of the sliding groove 21 close to the rear end of the drill 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 rear end of the drill body 1, and rotates counterclockwise under the guidance of the guide boss 15 and the sliding groove 21; when the valve core 4 is tightly fitted with the bottom of the cylindrical inner cavity 6, the valve core 4 rotates 60° counterclockwise, and the axial through hole 16 is matched and connected with the axial functional hole 8 connected to the first nozzle 10, and the remaining axial functional holes 8 are blocked by the end face of the valve core 4. At this time, the cutting drill bit is in the hole expansion function state;

[0047] When the high-pressure water is turned off, under the combined action of the reset spring 7 pushing and the guide boss 15 and the sliding groove 21 guiding, the valve core returns to the position, slides to the left, and rotates 60° counterclockwise, and all the axial functional holes 8 at the bottom of the cylindrical cavity 6 are in an open state;

[0048] 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 is connected with the axial functional hole 8 connected to the second nozzle 19, and the cutting drill bit is in the slitting function state at this time;

[0049] When the high-pressure water is turned off, the valve core returns to its original position and slides to the left and rotates 60° counterclockwise under the combined action of the reset spring 7, the guide boss 15 and the sliding groove 21, and all the axial functional holes 8 at the bottom of the cylindrical cavity 6 are in an open state;

[0050] 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 is connected with the axial functional hole 8 connected to the drilled water hole 20, and the cutting drill bit is in the drilling function state at this time;

[0051] The high-pressure water is opened and closed in this way, and the guide boss 15 slides through a groove subunit. The water flow channels of the circular holes 8 with different axial functions are opened and closed in the order of "drilling-expansion-slit cutting", so that the sequential conversion of the drilling-expansion-slit cutting function of the cutting drill bit can be realized.

[0052] The embodiment of the above application process takes the case where the guide boss 15 is aligned with the axial functional circular hole 8 connected to the first nozzle 10 after being displaced to the right and rotated as an example, but it is not limited to this. When the guide boss 15 is located in the first interval recovery groove 26 or the second interval recovery groove 27, it can also be used as the initial position for function switching.

[0053] It should be noted that the above embodiment is a cutting drill bit with three functions of drilling-reaming-slitting, and the order of its function conversion can be achieved by adjusting the connecting nozzle on the drill body. In addition, the number of functions of the cutting drill bit can be adjusted by adjusting the number of axial functional circular holes at the bottom of the cylindrical cavity of the cutting drill bit. For example, by reducing one axial functional circular hole, the cutting drill bit can be changed into a "drilling-slitting" two-function sequence conversion cutting drill bit, or a drilling-reaming two-function sequence conversion cutting drill bit; for example, the axial functional circular holes can be increased to four, and the cutting drill bit can be changed into a "drilling-reaming-slitting-punching" four-function sequence conversion cutting drill bit; it should be noted that when adding or reducing axial functional circular holes, the groove subunits in the sliding groove 21 should be adjusted accordingly, so that they correspond one to one with the number of axial functional circular holes. This type of change implementation scheme is generally similar to the above implementation scheme and will not be described in detail.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A high-pressure water jet drilling-expanding-cutting multifunctional drill bit, characterized in that: The drill bit body comprises a drill bit body and a function conversion mechanism, wherein the drill bit body has a cylindrical inner cavity for accommodating the function conversion mechanism, and a plurality of axial functional circular holes connected to the cylindrical inner cavity, and the axial functional circular holes are arranged on one side of the cylindrical inner cavity close to the front end of the drill bit body, and the side wall of the drill bit body is provided with a plurality of radial circular holes connected to different axial functional circular holes, the radial circular holes are connected to nozzles, and the apertures of the nozzles connected to each of the radial circular holes are different, and a drilled water hole is also provided in the drill bit body, one end of which is connected to the end of the drill bit body, and the other end of the drilled water hole is connected to one of the plurality of axial functional circular holes; The function conversion mechanism comprises a valve core, a function conversion slide sleeve and an elastic member, wherein the valve core has a valve core through-hole, the function conversion slide sleeve is fixedly installed in the cylindrical inner cavity, the valve core is slidably installed in the function conversion slide sleeve, one end of the elastic member is connected to the valve core, and the other end is connected to one end of the cylindrical inner cavity connected to the axial function circular hole, so as to push the valve core away from the end of the cylindrical inner cavity connected to the axial function circular hole; At least two radially extending guide bosses are provided on the outer wall of the valve core, and a sliding groove matching the guide bosses is provided on the inner wall of the function conversion slide sleeve. Under the guidance of the sliding groove, the valve core rotates in the same direction during forward axial sliding and backward axial sliding. The sliding groove is composed of at least two groove sub-units that are cyclically connected, and the number of groove sub-units is equal to the number of axial functional circular holes, so that each time the valve core abuts against one end of the cylindrical inner cavity connected to the axial functional circular hole, the through-hole of the valve core is aligned with multiple axial functional circular holes in sequence.

2. A high-pressure water jet drilling-expanding-cutting multifunctional drill bit according to claim 1, characterized in that: A first central blind hole is provided at the front end of the cylindrical inner cavity, a second central blind hole is provided at one end of the valve core close to the first central blind hole, and two ends of the elastic member 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 drilling-expanding-cutting multifunctional drill bit according to claim 1, characterized in that: The elastic member is a return spring.

4. The high-pressure water jet drilling-expanding-cutting multifunctional drill bit according to claim 1, characterized in that: Each groove subunit is formed by a combination of a "human" shaped groove and an inverted "human" shaped groove, and an offset staggered structure is adopted at the "human" intersection, so that the guide boss can maintain unidirectional sliding when sliding up and down in the sliding groove, so that the valve core always rotates in the same direction.

5. The high-pressure water jet drilling-expanding-cutting multifunctional drill bit according to claim 4, characterized in that: Assuming the number of the groove subunits is n, when the guiding protrusion of the valve core slides through a complete groove subunit inside the sliding groove, the valve core rotates by θ° in the same rotation direction, and θ=360 / n.

6. The high-pressure water jet drilling-expanding-cutting multifunctional drill bit according to claim 1, characterized in that: The function conversion slide sleeve is installed in the cylindrical inner cavity through a fixing structure, and the fixing structure includes a step structure arranged on the inner wall of the cylindrical inner cavity, an annular groove and a hole clamping ring installed in the annular groove, and the two ends of the function conversion slide sleeve are respectively connected with the step structure and the hole clamping ring.

7. A high-pressure water jet drilling-expanding-cutting multifunctional drill bit according to claim 6, characterized in that: The function conversion slideway sleeve and the cylindrical inner cavity are connected by interference fit or key, so that the function conversion slideway sleeve and the cylindrical inner cavity are fixedly connected in the circumferential direction.

8. A method for using a high-pressure water jet drilling-expanding-cutting multifunctional drill bit, characterized in that: A high-pressure water jet drilling-expanding-cutting multifunctional drill bit according to any one of claims 1 to 7 is used, wherein the tail end of the drill bit body is connected to high-pressure water, and the cutting method specifically comprises the following steps: a. The high-pressure water is turned on. Under the combined effect of the high-pressure water flow and the guidance of the sliding groove, the valve core slides toward the front end of the drill body and rotates, and then fits tightly with the front end of the cylindrical inner cavity. The axial through hole of the valve core is connected with any one of the multiple axial functional holes, and the high-pressure water flows into the connected axial functional hole. The other axial functional holes are blocked by the end face of the valve core, and the water jet cutting drill enters the preset functional state; b. When the function needs to be switched, the high-pressure water is turned off, and under the combined action of the elastic member pushing and the sliding groove guiding, the valve core slides toward the tail end of the drill body and rotates, and the rotation direction is the same as the rotation direction in step a, so that all axial functional holes are in an open state; c. Turn on the high-pressure water again. Under the combined effect of the high-pressure water flow and the guidance of the sliding groove, the valve core slides and rotates toward the front end of the drill body, and then fits tightly with the front end of the cylindrical inner cavity. The axial through hole of the valve core is connected with the axial functional hole adjacent to the axial functional hole connected in step a. High-pressure water flows into the connected axial functional hole, and the remaining axial functional holes are blocked by the end face of the valve core. The water jet cutting drill enters the preset switching functional state; d. Repeat the cycle to control the opening and closing of high-pressure water to achieve sequential switching of multiple axial functional circular holes.

9. The method for using a high-pressure water jet drilling-expanding-cutting multifunctional drill bit according to claim 8, characterized in that: 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 drilled water hole, and the aperture of the first nozzle is larger than the aperture of the second nozzle, so that the first nozzle is used as a hole expansion nozzle and the second nozzle is used as a slit; Among them, the axial functional circular hole connected to the drill bit, the axial functional circular hole connected to the first nozzle and the axial functional circular hole connected to the second nozzle are arranged in sequence along the rotation direction of the valve core to realize the sequential conversion of drilling-expansion-cutting functions by controlling the opening and closing of the high-pressure water flow.

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