Reverse circulation concentric simultaneous casing drilling tool

Abstract

The utility model discloses a reverse circulation concentric casing-following drilling tool which comprises a protective pipe assembly, the annular drill bit is sleeved with the protective pipe assembly and fixedly connected with the front end of the protective pipe assembly, and the outer diameter of the annular drill bit is larger than the maximum outer diameter of the protective pipe assembly; the reverse circulation impact assembly is coaxially sleeved with the annular drill bit, a deslagging channel and a high-pressure air channel are arranged in the reverse circulation impact assembly, the high-pressure air channel is arranged on the outer side of the deslagging channel, and the high-pressure air channel is used for being communicated with the hole bottom and blowing residues at the hole bottom into the deslagging channel; a locking state and an unlocking state exist between the reverse circulation impact assembly and the annular drill bit, the reverse circulation impact assembly and the annular drill bit can rotate relatively, and the reverse circulation impact assembly is rotated to be used for switching the locking state and the unlocking state. Compared with the prior art, the reverse circulation concentric casing-following drilling tool can effectively solve the problems of hole shrinkage, collapse and hole wall instability of a soft soil layer, the deslagging effect is better, and the drilling efficiency is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of drilling equipment, more particularly to a reverse circulation concentric pipe following drilling tool. BACKGROUND

[0002] When drilling in loose, poor cementation, easy to break, easy to hydrate and other soft rock soil layers, the construction is difficult, and problems such as difficult coring, difficult hole forming, hole wall collapse and the like are often encountered, and the drilling effect is not ideal, the main reason being that the hole is prone to collapse during drilling, the amount of slag is large, and accidents such as sticking, jamming and burying of the drill may occur, resulting in low drilling efficiency.

[0003] The down-the-hole hammer pipe following drilling technology makes full use of the advantages of the down-the-hole hammer in efficiently impacting and breaking rocks, and while efficiently breaking rocks, the pipe following sleeve protects the hole wall of the drill hole, and the rigid guiding effect of the sleeve can inhibit the bending of the drill hole, thereby ensuring the straightness of the drill hole, so the pipe following reaming tool is widely used in the engineering drilling construction of hard, broken, loose and other complex strata at home and abroad. The existing pipe following drilling tools are mainly divided into eccentric pipe following drilling tools and concentric pipe following drilling tools, and practice has proved that the existing eccentric pipe following drilling tools have certain defects, for example, the required torque for drilling is large, the drilling concentricity is poor, the drill is prone to sticking, the pipe following resistance is large, and the sleeve is prone to being damaged.

[0004] At present, the concentric pipe following drilling tool mainly adopts positive circulation for slag discharge, but when the hole diameter is large or the stratum is complex, the positive circulation for slag discharge is difficult, resulting in reduced drilling efficiency, shortened service life of the drill and increased drilling cost, and the drill bit is prone to being stuck by rock cuttings when the drill is lifted, which brings inconvenience to the work of lifting the drill.

[0005] Therefore, there is an urgent need for a reverse circulation concentric pipe following drilling tool that can effectively solve the problems of diameter reduction, collapse, and hole wall instability of soft soil layers, has better slag discharge effect, and has high drilling efficiency. CONTENT OF THE INVENTION

[0006] To solve the above technical problems, the present application provides a reverse circulation concentric pipe following drilling tool that can effectively solve the problems of diameter reduction, collapse, and hole wall instability of soft soil layers, has better slag discharge effect, and has high drilling efficiency.

[0007] The technical scheme provided by the present application is as follows:

[0008] A reverse circulation concentric pipe following drilling tool, comprising:

[0009] a pipe protection assembly;

[0010] a ring-shaped drill bit sleeved in the pipe protection assembly and fixedly connected to the front end of the pipe protection assembly, the outer diameter of the ring-shaped drill bit being greater than the maximum outer diameter of the pipe protection assembly;

[0011] A reverse circulation impact assembly coaxially sleeved in the annular drill bit, a residue discharge channel and a high-pressure air passage are arranged in the reverse circulation impact assembly, the high-pressure air passage is arranged outside the residue discharge channel, the high-pressure air passage communicates with the hole bottom, and residues of the hole bottom are blown into the residue discharge channel;

[0012] The reverse circulation impact assembly and the annular drill bit have a locked state and an unlocked state, and the reverse circulation impact assembly is rotated to switch the locked state and the unlocked state.

[0013] Preferably, the reverse circulation impact assembly comprises:

[0014] A center drill bit sleeved in the annular drill bit;

[0015] A driving mechanism arranged between the center drill bit and the annular drill bit, the driving mechanism comprises an unlocking groove arranged on the outer circumferential side of the center drill bit and extending along the axial direction of the center drill bit, and a driving groove communicating with the front end of the unlocking groove and extending along the circumferential direction of the center drill bit, and the inner circumferential side of the annular drill bit is provided with a driving boss configured to be capable of sliding to the front end along the unlocking groove and rotating to the driving groove in a first direction for locking;

[0016] An impact structure sleeved on the outer side of the front end of the center drill bit and in driving connection with the center drill bit.

[0017] Preferably, the driving mechanism is provided with at least two groups, and the driving mechanisms are arranged at intervals around the circumferential direction of the center drill bit.

[0018] Preferably, a first channel and a first air passage are arranged in the center drill bit, the inlet of the first channel extends to the front end face of the center drill bit, the first air passage is arranged outside the first channel, and the outlet of the first air passage communicates with the inlet of the first channel.

[0019] Preferably, the impact structure comprises:

[0020] A drill bit sleeve sleeved on the rear end of the center drill bit and in driving connection with the center drill bit, the inner circumferential side of the drill bit sleeve forms a second air passage with the outer circumferential side of the center drill bit, and a third air passage is arranged on the drill bit sleeve and used for communicating the second air passage and the first air passage.

[0021] An outer sleeve fixedly sleeved on the outer side of the rear end of the drill bit sleeve;

[0022] A collection tube coaxially sleeved in the outer sleeve, the collection tube communicates with the first channel to form a residue discharge channel;

[0023] a piston slidingly arranged between the outer sleeve and the collecting pipe;

[0024] a joint assembly fixedly connected with the outer sleeve and arranged outside the rear end of the collecting pipe;

[0025] a gas distribution channel formed between the piston, the collecting pipe, the outer sleeve and the joint assembly, and used for communicating with the second air passage.

[0026] Preferably, the first air passage is arranged along the length direction of the center drill bit, and the impact structure further comprises a plug sleeve arranged between the pipe protection assembly and the drill collar, the plug sleeve being fixedly connected with the outer sleeve and used for plugging the rear end gas outlet of the first air passage.

[0027] Preferably, the outer side of the drill collar is provided with a positioning block, the inner circumferential side of the rear end of the plug sleeve is provided with a positioning step, the front end surface of the positioning step abuts against the positioning block, and the rear end surface of the positioning step abuts against the outer sleeve.

[0028] Preferably, the pipe protection assembly comprises:

[0029] a pipe shoe sleeved outside the annular drill bit and fixedly connected with the annular drill bit.

[0030] a following pipe sleeved outside the reverse circulation impact assembly and fixedly connected with the pipe shoe, the maximum outer diameter of the following pipe being smaller than the maximum outer diameter of the pipe shoe.

[0031] Preferably, the annular drill bit comprises, in sequence from the front end to the rear end, a reaming section, a positioning section and a mounting section, wherein the outer diameter of the reaming section is greater than the outer diameter of the mounting section, and the outer diameter of the mounting section is greater than the outer diameter of the positioning section.

[0032] the front end of the pipe shoe is provided with a positioning stopper used for being connected with the positioning section.

[0033] Preferably, the difference between the maximum outer diameter of the annular drill bit and the maximum outer diameter of the pipe protection assembly is 2mm to 3mm.

[0034] The reverse circulation concentric follow-up pipe drilling tool provided by the utility model, firstly, due to the setting of the pipe protection assembly and the annular drill bit, the annular drill bit is sleeved in the pipe protection assembly, the front end of the annular drill bit is fixedly connected with the pipe protection assembly, the outer diameter of the annular drill bit is larger than the maximum outer diameter of the pipe protection assembly, the annular drill bit is used for drilling, the pipe protection assembly drills with the annular drill bit, and the pipe protection assembly is used for supporting the hole wall of the drilling hole, so that the problems of the shrinkage, collapse and hole wall instability of the soft soil layer are avoided. Secondly, the reverse circulation impact assembly is further arranged, the reverse circulation impact assembly is coaxially sleeved in the annular drill bit, the reverse circulation impact assembly is provided with the residue discharge channel and the high-pressure gas channel, the residue discharge channel is used for discharging the residues at the bottom of the hole, the high-pressure gas channel is used for communicating with the bottom of the hole, the high-pressure gas in the high-pressure gas channel discharges the residues at the bottom of the hole into the residue discharge channel while the reverse circulation impact assembly drives the annular drill bit to drill, the reverse circulation impact assembly discharges the residues from the middle and blows gas from the side, so that the residue discharge effect is better. The reverse circulation impact assembly and the annular drill bit have the locking state and the unlocking state, when the reverse circulation impact assembly and the annular drill bit are in the locking state, the annular drill bit and the pipe protection assembly are driven downward to drill by the reverse circulation impact assembly, the residues at the bottom of the hole are discharged along the residue discharge channel, when the reverse circulation impact assembly is in the unlocking state, the reverse circulation impact assembly is convenient for the work of lifting the drill, the reverse circulation impact assembly and the annular drill bit can relatively rotate, the reverse circulation impact assembly is rotated to switch the locking state and the unlocking state, and the reverse circulation impact assembly is rotated to facilitate the lifting of the drill after the drilling is completed. Therefore, compared with the prior art, the reverse circulation concentric follow-up pipe drilling tool in the utility model embodiment can effectively solve the problems of the shrinkage, collapse and hole wall instability of the soft soil layer, the residue discharge effect is better, and the drilling efficiency is high. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0036] Figure 1 A structural schematic view of the reverse circulation concentric follow-up pipe drilling tool provided by the utility model embodiment;

[0037] Figure 2 A structural schematic view of the reverse circulation concentric follow-up pipe drilling tool provided by the utility model embodiment; Figure 1 A partial enlarged view of the reverse circulation concentric follow-up pipe drilling tool provided by the utility model embodiment;

[0038] Figure 3 A partial schematic view of the reverse circulation concentric follow-up pipe drilling tool provided by the utility model embodiment;

[0039] Figure 4A structure schematic view of the annular drill bit provided by the embodiment of the utility model;

[0040] Figure 5 A structure schematic view of the center drill bit provided by the embodiment of the utility model;

[0041] Figure 6 A structure schematic view of the annular drill bit and the pipe shoe connection provided by the embodiment of the utility model;

[0042] The drawing mark: 1, annular drill bit;2, center drill bit;31, unlocking groove;32, drive groove;33, drive boss;4, impact structure;5, pipe shoe;6, follow pipe;11, reaming section;12, positioning section;13, mounting section;21, first channel;22, first air channel;41, drill sleeve;42, outer sleeve;43, collection tube;44, piston;45, joint assembly;46, plug sleeve;411, second air channel;412, third air channel;51, positioning stopper. DETAILED DESCRIPTION

[0043] In order to make the person skilled in the art better understand the technical scheme in the present application, the technical scheme in the embodiment of the present application will be described clearly and completely below, obviously, the described embodiment is only a part of the embodiment of the present application, not all the embodiments. Based on the embodiment in the present application, all other embodiments obtained by the person skilled in the art without creative labor belong to the scope of protection of the present application.

[0044] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly disposed on the other element or indirectly disposed on the other element;When an element is referred to as "connected to" another element, it can be directly connected to another element or indirectly connected to another element.

[0045] It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation to the present application.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" or "several" means two or more, unless otherwise explicitly specified.

[0047] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0048] The embodiments of this utility model are written in a progressive manner.

[0049] like Figures 1 to 6 As shown, a single arrow indicates the direction of high-pressure gas flow, and a double arrow indicates the direction of residue flow at the bottom of the hole. This embodiment of the invention provides a reverse circulation concentric casing drill bit, comprising: a casing assembly; an annular drill bit 1, fitted inside the casing assembly and fixedly connected to its front end, the annular drill bit 1 having an outer diameter larger than the maximum outer diameter of the casing assembly; a reverse circulation impact assembly coaxially fitted inside the annular drill bit 1, the reverse circulation impact assembly having a slag discharge channel and a high-pressure air passage, the high-pressure air passage being located outside the slag discharge channel and communicating with the bottom of the hole, blowing the residue at the bottom of the hole into the slag discharge channel; the reverse circulation impact assembly and the annular drill bit 1 have a locked state and an unlocked state, and rotating the reverse circulation impact assembly is used to switch between the locked and unlocked states.

[0050] Currently, concentric casing drills mainly use positive circulation for cuttings removal. However, when the borehole diameter is large or the formation is complex, positive circulation cuttings removal is difficult, leading to reduced drilling efficiency, shortened drill life, and increased drilling costs. In addition, the drill bit is easily jammed by rock cuttings when lifting the drill bit, which causes inconvenience to the lifting operation.

[0051] The reverse circulation concentric following pipe drilling tool provided by the utility model is firstly provided with the pipe protection assembly and the annular drill bit 1, wherein the annular drill bit 1 is sleeved in the pipe protection assembly, the front end of the annular drill bit 1 is fixedly connected with the pipe protection assembly, the outer diameter of the annular drill bit 1 is larger than the maximum outer diameter of the pipe protection assembly, the annular drill bit 1 is used for drilling, the pipe protection assembly drills with the annular drill bit 1, and the pipe protection assembly is used for supporting the hole wall of the drilled hole, so that the problems of the shrinkage, collapse and hole wall instability of the soft soil layer are avoided. Secondly, the reverse circulation impact assembly is further provided, the reverse circulation impact assembly is coaxially sleeved in the annular drill bit 1, the reverse circulation impact assembly is provided with the residue discharging channel and the high-pressure gas channel, the residue discharging channel is used for discharging the residue at the bottom of the hole, the high-pressure gas channel is used for communicating with the bottom of the hole, the high-pressure gas in the high-pressure gas channel discharges the residue at the bottom of the hole into the residue discharging channel to discharge the residue, the reverse circulation impact assembly discharges the residue in the middle and blows gas at the side, so that the residue discharging effect is better. The reverse circulation impact assembly and the annular drill bit 1 have the locking state and the unlocking state, when the reverse circulation impact assembly and the annular drill bit 1 are in the locking state, the annular drill bit 1 and the pipe protection assembly are driven downward to drill by the reverse circulation impact assembly, the residue at the bottom of the hole is discharged along the residue discharging channel, when the reverse circulation impact assembly is in the unlocking state, the reverse circulation impact assembly is convenient for lifting the drill, the reverse circulation impact assembly and the annular drill bit 1 can relatively rotate, the reverse circulation impact assembly is rotated to switch the locking state and the unlocking state, after the drilling is completed, the reverse circulation impact assembly is rotated to facilitate lifting the drill. Therefore, compared with the prior art, the reverse circulation concentric following pipe drilling tool in the utility model embodiment can effectively solve the problems of the shrinkage, collapse and hole wall instability of the soft soil layer, the residue discharging effect is better, and the drilling efficiency is high.

[0052] Specifically, when the reverse circulation impact assembly and the annular drill bit 1 are in the locking state, the reverse circulation impact assembly drives the annular drill bit 1 and the pipe protection assembly to continue rotating in the first direction, and at the same time, the reverse circulation impact assembly drives the annular drill bit 1 to drill downward to realize reaming; the reverse circulation impact assembly reversely rotates in the second direction, so that the reverse circulation impact assembly and the annular drill bit 1 are in the unlocking state, the reverse circulation impact assembly can move along the axis, so as to be separated from the annular drill bit 1, and the reverse circulation impact assembly is convenient for lifting the drill.

[0053] Furthermore, the maximum outer diameter of the annular drill bit 1 is larger than the maximum outer diameter of the pipe protection assembly, and the annular drill bit 1 is fixedly connected with the pipe protection assembly, when the reverse circulation impact assembly drives the annular drill bit 1 to drill downward, the annular drill bit 1 drives the pipe protection assembly to move downward, the hole wall of the drilled hole is supported by the pipe protection assembly, so that the hole collapse is avoided, when the reverse circulation impact assembly lifts the drill, the annular drill bit 1 and the pipe protection assembly still remain in the hole, so as to be convenient for subsequent construction operation.

[0054] In the above structure, as one of the embodiments, the anti-circulation impact assembly in the embodiment of the utility model comprises a center drill bit 2, a driving mechanism and an impact structure 4, the center drill bit 2 is sleeved in the annular drill bit 1, the driving mechanism is arranged between the center drill bit 2 and the annular drill bit 1, the impact structure 4 is sleeved on the outside of the front end of the center drill bit 2, the impact structure 4 is used for being in transmission connection with the center drill bit 2, and the impact structure 4 is used for providing the center drill bit 2 with downward pulse acting force. Further, the driving mechanism comprises an unlocking groove 31 and a driving groove 32 arranged on the outer circumferential side of the center drill bit 2, the unlocking groove 31 extends along the axis direction of the center drill bit 2, the driving groove 32 is in communication with the front end of the unlocking groove 31, and the driving groove 32 extends along the circumferential direction of the center drill bit 2, and the inner circumferential side of the annular drill bit 1 is provided with a driving boss 33, the driving boss 33 can slide to the front end along the unlocking groove 31 and rotate to the driving groove 32 in the first direction to be locked.

[0055] More specifically, when the center drill bit 2 is installed, the unlocking groove 31 is aligned with the driving boss 33, the center drill bit 2 is moved along the axis direction, so that the driving boss 33 is moved to the front end of the unlocking groove 31, the center drill bit 2 is rotated in the first direction, so that the driving boss 33 is rotated to the driving groove 32 to be locked, and the center drill bit 2 is continuously driven to rotate in the first direction to work for drilling; when the drilling is completed, the center drill bit 2 is driven to rotate in the second direction, so that the driving boss 33 is rotated to the unlocking groove 31, the center drill bit 2 is moved along the axis, and the drill bit is moved along the unlocking groove 31 to separate the center drill bit 2 from the annular drill bit 1. The above is only a specific structure for connecting the center drill bit and the annular drill bit provided by the utility model, and other embodiments exist in the prior art, which are disclosed in CN101956525A and CN211144383U, and will not be described here.

[0056] In the above structure, as one of the embodiments, the driving mechanism in the embodiment of the utility model can be provided in a group, if the driving mechanism is provided in only one group, the condition of unbalanced load may occur, as one of the preferred embodiments, the driving mechanism in the embodiment of the utility model is provided in at least two groups, and the driving mechanisms are arranged at intervals along the circumferential direction of the center drill bit 2.

[0057] In the above structure, as one of the embodiments, the center drill bit 2 in the embodiment of the utility model is provided with a first channel 21 and a first air duct 22, the inlet of the first channel 21 extends to the front end surface of the center drill bit 2, the first air duct 22 is arranged on the outside of the first channel 21, and the outlet of the first air duct 22 is in communication with the first channel 21.

[0058] Specifically, the mounting rod of the center drill bit 2 is connected with the impact structure 4 through a spline transmission, high-pressure gas is discharged from the first gas channel 22, and residues at the bottom of the hole are blown into the first channel 21 for residue discharge.

[0059] Further, as one of the embodiments, the impact structure 4 in the embodiment of the utility model comprises a drill sleeve 41, an outer sleeve 42, a collecting pipe 43, a piston 44 and a joint assembly 45, wherein the drill sleeve 41 is sleeved at the rear end of the center drill bit 2, the drill sleeve 41 is connected with the center drill bit 2 in transmission, the inner circumferential side of the drill sleeve 41 and the outer circumferential side of the center drill bit 2 form a second gas channel 411, the third gas channel 412 is arranged on the drill sleeve 41 and is used for connecting the first gas channel 22 and the second gas channel 411, the outer sleeve 42 is sleeved at the rear end of the drill sleeve 41, the outer sleeve 42 is fixedly connected with the drill sleeve 41, the collecting pipe 43 is coaxially sleeved in the outer sleeve 42, the collecting pipe 43 is communicated with the first channel 21 to form a residue discharge channel, the piston 44 is slidably arranged between the collecting pipe 43 and the outer sleeve 42, the joint assembly 45 is arranged at the outer side of the rear end of the collecting pipe 43, the joint assembly 45 is fixedly connected with the outer sleeve 42, and the piston 44, the collecting pipe 43, the outer sleeve 42 and the joint assembly 45 form a gas distribution channel, which is used for being communicated with the second gas channel 411.

[0060] Specifically, the piston 44, the collecting pipe 43, the outer sleeve 42 and the joint assembly 45 form a rear gas chamber, the piston 44, the collecting pipe 43, the outer sleeve 42 and the center drill bit 2 form a front gas chamber, there is a gas pressure difference between the front gas chamber and the rear gas chamber, the piston 44 is reciprocated along the axial direction of the collecting pipe 43 to provide a pulse force for the center drill bit 2.

[0061] The high-pressure gas between the front gas chamber or the rear gas chamber is alternately communicated with the second gas channel 411 through the gas distribution channel, the high-pressure gas is discharged through the second gas channel 411, the third gas channel 412 and the first gas channel 22, and the residues at the bottom of the hole are blown up, and since there is a negative pressure between the bottom of the hole and the first channel 21, the residues are discharged through the first channel 21 and the collecting pipe 43.

[0062] In the above structure, the first gas channel 22 in the embodiment of the utility model is arranged through along the length direction of the center drill bit 2, in order to avoid the leakage of the high-pressure gas from the rear end of the first gas channel 22, as one of the preferred embodiments, the impact structure 4 further comprises a plug sleeve 46, the plug sleeve 46 is arranged between the drill sleeve 41 and the drill sleeve 41, the plug sleeve 46 is fixedly connected with the outer sleeve 42, and the plug sleeve 46 is used for plugging the rear end gas outlet of the first gas channel 22.

[0063] In the above structure, the fixed connection between the plug sleeve 46 and the outer sleeve 42 is specifically that: a positioning block is arranged on the outer circumferential side of the front end of the drill sleeve 41, a positioning step is arranged on the inner circumferential side of the rear end of the plug sleeve 46, the front end face of the positioning step abuts against the positioning block, and the rear end face of the positioning step abuts against the outer sleeve 42. By fixedly connecting the outer sleeve 42 and the drill sleeve 41, the plug sleeve 46 is clamped.

[0064] More specifically, in the above structure, the drill sleeve 41 in the utility model embodiment is fixedly connected with the outer sleeve 42 through threads, and is more convenient to disassemble and assemble.

[0065] In the above structure, as one of the embodiments, the pipe protection assembly in the utility model embodiment comprises a shoe 5 and a following pipe 6, the shoe 5 is arranged outside the annular drill bit 1 and is fixedly connected with the annular drill bit 1, the following pipe 6 is arranged outside the reverse circulation impact assembly and is fixedly connected with the shoe 5, and the maximum outer diameter of the following pipe 6 is not greater than that of the shoe 5.

[0066] The following pipe 6 is fixedly connected with the shoe 5, specifically, the following pipe 6 is connected with the shoe 5 through threads, or the following pipe 6 is connected with the shoe 5 through welding, or the shoe 5 is connected with the following pipe 6 through threads and then the shoe 5 and the following pipe 6 are connected through welding.

[0067] In the above structure, as one of the embodiments, the annular drill bit 1 in the utility model embodiment comprises a reaming section 11, a positioning section 12 and a mounting section 13 connected in sequence from the front end to the rear end, the outer diameter of the reaming section 11 is greater than that of the mounting section 13, the outer diameter of the mounting section 13 is greater than that of the positioning section 12, the front end of the shoe 5 is provided with a positioning stopper 51, and the positioning stopper 51 is used for clamping in the positioning section 12.

[0068] Furthermore, the shoe 5 is fixedly connected with the annular drill bit 1 through buckling, specifically, in the initial state, the inner diameter of the positioning stopper 51 is greater than the outer diameter of the mounting section 13, so that the positioning stopper 51 can be aligned with the positioning section 12, then the shoe 5 is pressed by a buckling machine, so that the positioning stopper 51 is clamped with the positioning section 12, at this time, the inner diameter of the positioning stopper 51 is greater than the outer diameter of the positioning section 12 and smaller than the outer diameter of the mounting section 13.

[0069] Furthermore, as one of the embodiments, the difference between the maximum outer diameter of the annular drill bit 1 and the maximum outer diameter of the pipe protection assembly is 2mm to 3mm.

[0070] The above description of disclosed embodiments enables one of ordinary skill in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A reverse circulation, concentric liner drill string, characterized by, The utility model relates to a kind of drilling tools, including: A protection tube assembly; A ring bit (1) is sleeved in the protection tube assembly, and is fixedly connected with the front end of the protection tube assembly, the outer diameter of the ring bit (1) is greater than the maximum outer diameter of the protection tube assembly; A reverse circulation impact assembly is coaxially sleeved in the ring bit (1), a residue discharge channel and a high-pressure air passage are provided in the reverse circulation impact assembly, the high-pressure air passage is arranged outside the residue discharge channel, the high-pressure air passage is communicated with the bottom of the hole, and the residue at the bottom of the hole is blown into the residue discharge channel; The reverse circulation impact assembly and the ring bit (1) have a locked state and an unlocked state, and the locked state and the unlocked state are switched by rotating the reverse circulation impact assembly; The reverse circulation impact assembly includes: A center bit (2) is sleeved in the ring bit (1); A drive mechanism is arranged between the center bit (2) and the ring bit (1), the drive mechanism includes an unlocking groove (31) arranged on the outer circumferential side of the center bit (2) and a drive groove (32), the unlocking groove (31) extends along the axis direction of the center bit (2), the drive groove (32) is communicated with the front end of the unlocking groove (31), the drive groove (32) extends along the circumferential direction of the center bit (2), the inner circumferential side of the ring bit (1) is provided with a drive boss (33), the drive boss (33) is configured to be able to slide to the front end along the unlocking groove (31) and rotate in a first direction to be locked with the drive groove (32); An impact structure (4) is sleeved on the outer side of the front end of the center bit (2) and is in transmission connection with the center bit (2); The center bit (2) is provided with a first channel (21) and a first air passage (22), the inlet of the first channel (21) extends to the front end face of the center bit (2), the first air passage (22) is arranged outside the first channel (21), and the outlet of the first air passage (22) is communicated with the inlet of the first channel (21); The impact structure (4) includes: A drill collar (41) is sleeved on the rear end of the center bit (2) and is in transmission connection with the center bit (2), the inner circumferential side of the drill collar (41) forms a second air passage (411) with the outer circumferential side of the center bit (2), a third air passage (412) is arranged on the drill collar (41), and the third air passage (412) is used to communicate the second air passage (411) and the first air passage (22); An outer sleeve (42) is fixedly sleeved on the outer side of the rear end of the drill collar (41); A collection tube (43) is coaxially sleeved in the outer sleeve (42), the collection tube (43) is communicated with the first channel (21) to form a residue discharge channel; A piston (44) is slidingly arranged between the outer sleeve (42) and the collection tube (43); A joint assembly (45) is arranged on the outer side of the rear end of the collection tube (43) and is fixedly connected with the outer sleeve (42). The piston (44), the collection pipe (43), the outer sleeve (42) and the joint assembly (45) form a gas distribution channel for communicating with the second air passage (411).

2. The reverse circulation concentric liner drill tool according to claim 1, characterized in that, The driving mechanism is provided in at least two groups and is circumferentially spaced around the center drill bit (2).

3. The reverse circulation concentric liner drill tool according to any one of claims 1 to 2, characterized in that, The first air passage (22) is provided through along the length direction of the center drill bit (2), and the impact structure (4) further comprises a blocking sleeve (46) provided between the pipe protection assembly and the drill collar (41), the blocking sleeve (46) is fixedly connected with the outer sleeve (42) and used for blocking the rear end air outlet of the first air passage (22).

4. The reverse circulation concentric liner drill tool according to claim 3, characterized in that, The outer side of the drill collar (41) is provided with a positioning block, the inner circumferential side of the rear end of the blocking sleeve (46) is provided with a positioning step, the front end surface of the positioning step abuts against the positioning block, and the rear end surface of the positioning step abuts against the outer sleeve (42).

5. The reverse circulation concentric liner drill tool according to any one of claims 1 to 2, 4, characterized in that, The pipe protection assembly comprises: A pipe shoe (5) sleeved on the outer side of the annular drill bit (1) and fixedly connected with the annular drill bit (1); A liner (6) sleeved on the outer side of the reverse circulation impact assembly and fixedly connected with the pipe shoe (5), the maximum outer diameter of the liner (6) is smaller than the maximum outer diameter of the pipe shoe (5).

6. The reverse circulation concentric liner drill tool according to claim 5, characterized in that, The annular drill bit (1) comprises a reaming section (11), a positioning section (12) and a mounting section (13) connected in sequence from the front end to the rear end, wherein the outer diameter of the reaming section (11) is greater than the outer diameter of the mounting section (13), and the outer diameter of the mounting section (13) is greater than the outer diameter of the positioning section (12); The front end of the pipe shoe (5) is provided with a positioning stopper (51) used for clamping connection with the positioning section (12).

7. The reverse circulation concentric liner drill tool according to any one of claims 1 to 2, 4, 6, characterized in that, The difference between the maximum outer diameter of the annular drill bit (1) and the maximum outer diameter of the pipe protection assembly is 2mm to 3mm.

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