Coal mine underground large-diameter hole section reaming drilling tool assembly and hole forming method

Abstract

The invention discloses an underground coal mine large-diameter hole section chambering drilling tool assembly and a hole forming method, the underground coal mine large-diameter hole section chambering drilling tool assembly comprises a chambering drill bit, a plurality of drill rods and a water feeder which are connected in sequence, a centralizer is arranged between part of adjacent drill rods, the chambering drill bit comprises a chambering drill bit main body and an auxiliary drill bit body which are split, and the auxiliary drill bit body can move and displace in the axial direction of a sliding shaft. In the drill retreating process, the assembly is in a piston shape, sediment in a drill hole can be collected together and discharged out of the hole in a mechanical push-out mode, favorable conditions are created for casing pipe lowering of hole sections with different postures, in addition, radial ribs of the reamer bit body and the auxiliary bit body correspond to flow guide grooves in a staggered mode, and the overall outer contour is a cylindrical face. In the rotary drilling and axial push-and-pull process, the drill bit body edge wings cannot generate obvious destructive effect on the lower side hole wall stratum, casing lowering is facilitated, the casing lowering success rate can reach 95% or above, and the technical problems that an existing large-diameter hole section multi-stage reaming drilling tool is complex in combination, large in drilling tool replacement workload and low in efficiency are solved.

Description

Technical Field

[0001] The invention belongs to the field of underground coal mine drilling, and relates to a hole expansion drill tool, in particular to a large-diameter hole expansion drill tool combination and a hole forming method for underground coal mines. Background Art

[0002] In underground drilling projects in coal mines, most of the boreholes for gas control and water hazard prevention require the use of borehole mouth pipe sealing to meet the needs of gas and water gushing control in the borehole during drilling, as well as subsequent negative pressure extraction, water drainage, high-pressure grouting, etc. For multi-branch directional long boreholes, it is usually necessary to seal the borehole with pipes before drilling (that is, before implementing directional drilling with measurement while drilling, first construct the sealing section, insert a certain length of casing and seal it, and then implement directional drilling operations after passing the test). The quality of the pipe sealing is very important for the safe construction and efficient use of the borehole. On the one hand, it is a basic measure to prevent and control the abnormal outburst of gas and formation water during directional drilling and ensure construction safety. On the other hand, it is also a basic prerequisite for giving full play to the function of directional holes and achieving the expected engineering goals.

[0003] Different types of boreholes in coal mines are usually designed with different opening directions based on different engineering purposes. In the cross section, the posture of the sealing section can be divided into three typical forms: nearly horizontal, upward, and downward. Unlike the vertical downward sealing section of most ground holes, the special posture of the sealing section of underground coal mine drilling makes its hole quality have a great impact on the difficulty of pipe laying operations. At present, conventional large-diameter holes and directional drilling sealing sections in coal mines are mainly constructed by the process method of "pilot hole drilling + multi-stage hole expansion drilling". This method is reasonable: first constructing a small-diameter pilot hole is conducive to achieving straight drilling, and then multi-stage hole expansion reduces the requirements for the capacity of the drilling rig equipment and can achieve the purpose of using small machinery and equipment to form large-diameter holes.

[0004] With the continuous improvement of conventional rotary drilling and directional drilling technology and equipment in coal mines, and the continuous improvement of automation and intelligence levels, the number of large-diameter and deep boreholes with a construction diameter exceeding 200mm is increasing. The technical equipment for directional drilling of 200mm long boreholes in one go has been improved and has begun to be promoted and applied on a large scale. The maximum hole expansion diameter exceeds 300mm. The construction volume of conventional large-diameter boreholes is also increasing, and this type of borehole has higher requirements for the sealing of the downpipe. The increase in diameter and depth of the sealing section of underground directional drilling in coal mines has brought new technical difficulties in drilling construction: first, hydraulic slag removal is difficult in large-diameter hole expansion drilling, the cleaning effect in the hole is poor, and the sediment on the lower side of the hole wall causes large resistance to the lower pipe, making it difficult to ensure the depth of the lower pipe; second, the prismatic blades of the large-diameter drill bit often damage the formation of the lower hole wall during the withdrawal and pull-back process, and produce "pseudo drilling slag". Process factors reduce the regularity and integrity of the hole wall in the sealing section of the lower pipe, which in turn increases the difficulty of sealing the lower pipe, increases the complexity of the lower pipe, and reduces the quality of sealing; third, due to the limitation of hydraulic slag removal capacity, the combination of multi-stage hole expansion drill tools in the large-diameter hole section is complex, and the workload of replacing the drill tools is large and the efficiency is low; finally, during the expansion of the large-diameter sealing section, the level difference between the drill rod and the hole wall is large, the existing centralizer is difficult to connect and disassemble, the matching is poor, and the comprehensive timeliness of the drilling construction is deteriorated. At present, there is still a lack of fast hole expansion drilling tool combinations and hole-making methods that are suitable for conventional large-diameter holes, large-diameter directional holes, and long-distance sealing sections in underground coal mines. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a large-diameter hole expansion drill tool combination and a hole-making method for underground coal mines, so as to solve the technical problems that the existing large-diameter hole section multi-stage hole expansion drill tool combination is complicated, the workload of replacing the drill tool is large, and the efficiency is low.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0007] A large-diameter hole section reaming drill tool assembly for underground coal mines, comprising a reaming drill bit, a plurality of drill rods and a water feeder connected in sequence, a centralizer being arranged between some adjacent drill rods, characterized in that the reaming drill bit comprises a sliding shaft, an auxiliary drill bit body is movably sleeved in the middle of the sliding shaft, a limiting short section is sleeved at the axial rear end of the sliding shaft, a reaming drill bit body is sleeved at the axial front end of the sliding shaft, a fixing sleeve is sleeved at the axial front end of the reaming drill bit body, an axial rear end of a ball-end articulated shaft is arranged in the fixing sleeve, and a guide short section is arranged at the axial front end of the ball-end articulated shaft;

[0008] The axial front end surface of the fixing sleeve is evenly provided with a plurality of U-shaped grooves, and the inner cavity of the fixing sleeve is a spherical cavity and a conical cavity connected to each other;

[0009] The reaming drill bit body comprises a body, a plurality of rib wings are evenly arranged on the axial front end surface of the body, a PDC composite sheet with different diameters is welded on the front end surface of each rib wing, and a guide groove distributed along the axial direction is formed between adjacent rib wings, a ball socket is arranged in the middle of the body, a blocking ball seat connected to the ball socket is arranged at the axial rear end of the body, a hole bottom flow channel evenly distributed along the circumferential direction is opened on the inner wall of the blocking ball seat, the hole bottom flow channel comprises radial holes and axial holes that are connected and evenly distributed along the circumferential direction, and the axial hole is connected to the outside of the reaming drill bit body;

[0010] The sliding shaft comprises a first cylinder, a plurality of guide keys are arranged on the outer wall of the first cylinder at equal intervals in the circumferential direction, a first through-flow groove and a second through-flow groove of different depths and connected are opened on the guide key, a radial flow channel is arranged in the second through-flow groove, and the radial flow channel connects the inner cavity of the first cylinder, the first through-flow groove and the second through-flow groove;

[0011] The auxiliary drill body comprises a second cylinder, the axial front end of the outer wall of the second cylinder is evenly provided with auxiliary rib wings, the auxiliary rib wings correspond to the guide grooves of the reamer drill body in a circumferential direction, and the axial rear end of the auxiliary rib wings is provided with cemented carbide cutting teeth;

[0012] The circumferential width of the auxiliary wing is greater than the width of the guide groove on the reaming drill body, and the circumferential width of the auxiliary guide groove is less than the width of the wing on the reaming drill body;

[0013] A plurality of guide key grooves are arranged on the inner wall of the second cylinder at equal intervals along the circumferential direction, and the plurality of guide key grooves are matched one-to-one with the plurality of guide keys on the outer wall of the sliding shaft; a connecting groove is opened on the inner wall of the second cylinder, and the connecting groove is connected with the guide key groove;

[0014] A sliding cavity is provided at the axial rear end of the inner wall of the second cylinder, and a plurality of liquid flow holes are evenly provided on the side wall of the sliding cavity along the circumferential direction.

[0015] The present invention also includes the following technical features:

[0016] The centralizer comprises a front rod body and a rear rod body which are connected to each other; a plurality of centralizing wings are sleeved at the connection between the front rod body and the rear rod body, and the plurality of centralizing wings form a cylinder.

[0017] The front rod body comprises a mounting rod body, a plurality of dovetail grooves and a plurality of rectangular grooves are arranged alternately along the circumferential direction on the outer wall of the mounting rod body, a third mounting groove is opened on the outer wall of the mounting rod body, and the third mounting groove is perpendicular to and connected with the dovetail groove and the plurality of rectangular grooves; a central flow channel is opened inside the front rod body;

[0018] The rear rod body comprises a connecting support section and a limiting truncated cone connected in the axial direction, the connecting support section has a cylindrical surface with the same outer diameter as the drill rod, and the limiting truncated cone has the same outer diameter as the mounting rod body of the front rod body; a central channel is opened inside the rear rod body;

[0019] A straight rib plate is respectively arranged at both circumferential ends of the inner wall of each of the righting wings, and the straight rib plate is located in the rectangular groove. A dovetail rib plate is arranged in the middle of the inner wall of the righting wing, and the dovetail rib plate is located in the dovetail groove. A limiting groove is arranged on the dovetail rib plate, and a limiting block is arranged in the limiting groove.

[0020] A locking hole is provided in the limiting groove; a limiting hole is provided on the limiting block, and bolts are provided in both the limiting hole and the locking hole.

[0021] The limiting block comprises a rectangular block and a fan-shaped block. The rectangular block cooperates with the limiting groove on the righting wing; the fan-shaped block cooperates with the third mounting groove on the front rod body.

[0022] The outer wall of the first cylinder is in a step shape with an increasing diameter along the axial direction, and the outer wall of the axial rear end of the first cylinder is in a tapered shape.

[0023] The axial rear end face of the rib wing of the reaming drill body is provided with a conical surface, and the axial front end face of the auxiliary rib wing of the auxiliary drill body is provided with a conical surface with the same angle as the axial rear end face of the rib wing.

[0024] A plurality of windows are provided on the righting wing.

[0025] A method for drilling a hole with a large-diameter hole section expansion drill tool assembly in a coal mine, based on the large-diameter hole section expansion drill tool assembly in a coal mine, specifically comprises the following steps:

[0026] Step 1: Use a small-diameter drill bit and a drill rod to construct a pilot hole to a designed depth, and then withdraw the drill rod and the small-diameter drill bit in sequence;

[0027] Step 2: lower the guide sub of the reaming drill bit into the pilot hole obtained in step 1, start the mud pump, and high-pressure water enters the water feeder through the pipeline. After reaching the bottom of the hole, the high-pressure water cools the PDC composite sheet and carries the drill cuttings back out of the borehole;

[0028] Step 3: After the hole is expanded to a certain depth, observe the slag return at the hole mouth and perform mechanical slag removal by lifting the drill in the local hole section;

[0029] The local hole section drilling mechanical slag removal adopts a 'piston' body composed of an auxiliary drill bit body and a hole reaming drill bit body to collect the drill slag deposited in the expanded hole section and push it out into the hole;

[0030] Step 4, re-drilling and continuing hole expansion, repeating step 3 at intervals of a certain hole depth according to the length of the hole expansion section and the slag return during the hole expansion process until the hole is expanded to a predetermined depth, thereby obtaining a large-diameter drill hole;

[0031] Step 5, pull back the large-diameter hole section reaming drill assembly in the coal mine in a short distance and rotate it slowly, so that the auxiliary drill bit body and the reaming drill bit body are fitted together to form a combination, put a sealing ball into the center hole of the drill rod, and flush it into the reaming drill bit body at the bottom of the hole with water;

[0032] Step 6, start to withdraw the drill, the reaming drill collects the sediment in the borehole at its rear end and discharges it mechanically; when the pull-back resistance of the drill increases significantly during the withdrawal, turn on the mud pump to inject water into the hole to stir and disperse the drill residue accumulated at the rear end of the reaming drill bit, and continue to withdraw the drill until the reaming drill bit body is out of the hole, completing the slag removal and hole forming;

[0033] Step 7, insert casing into the obtained large diameter borehole and seal it by grouting as needed.

[0034] The method also includes: adding a centralizer to the drill rod in the hole at a certain interval, and sending the centralizer into the hole to continue expanding the hole and drilling.

[0035] Compared with the prior art, the present invention has the following beneficial technical effects:

[0036] (I) The reaming drill bit in the present invention comprises a separate reaming drill bit body and an auxiliary drill bit body. The auxiliary drill bit body is movable and displaceable in the axial direction of the sliding shaft. During the drilling withdrawal process, the assembly is in the shape of a "piston", which can collect the sediment in the borehole and discharge it out of the hole in a mechanical manner, thereby creating favorable conditions for lowering the casing in different hole sections, and the comprehensive casing lowering efficiency can be improved by more than 30%; in addition, the radial ribs of the reaming drill bit body and the auxiliary drill bit body correspond to the guide grooves in an offset manner, and the overall outer contour is a cylindrical surface; during the rotary drilling and axial pushing and pulling process, the ribs of the drill bit body will not have a significant destructive effect on the lower side of the hole wall formation, will not produce "pseudo drill residues", can keep the hole wall relatively intact and regular in cross section, and has a more obvious protective effect on the hole wall of the softer layer section, which is conducive to lowering the casing, and the casing lowering success rate can reach more than 95%, solving the technical problems of complex combination of existing multi-stage reaming drill tools in large-diameter hole sections, large workload and low efficiency in replacing drill tools.

[0037] (II) The centralizer of the drill bit assembly of the present invention is a modular structure, which is mechanically assembled and disassembled with the drill rod, and has the characteristics of flexibility, high efficiency, and low labor intensity. The efficiency of connection and disassembly is increased by more than 50% compared with the one-piece structure; the "variable diameter" feature can adapt to the expansion construction requirements of holes with different diameters.

[0038] (III) The use of the drill tool assembly of the present invention can achieve one-time drilling and expansion of conventional large-diameter boreholes, large-diameter directional boreholes, and long-distance sealing sections in coal mines, with high borehole quality and fast speed, and can meet the requirements for lowering large-diameter sealing pipes of more than 200 mm. In addition, in this method, the flushing fluid discharge volume requirement is low. With the help of a special combined structure, the drilling rig's pulling ability is utilized, and the sediment in the hole is mechanically discharged to the outside of the hole by pulling back the drill, and deep hole expansion can be completed progressively, eliminating the need for multi-stage hole expansion and drilling and disassembly and replacement of drill tool assemblies of different specifications, and the disassembly and assembly workload is reduced by more than 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of a large-diameter hole expansion drilling tool assembly for underground coal mines of the present invention;

[0040] FIG2( a ) is a schematic diagram of the drilling state of the large-diameter hole-reaming drill bit of the present invention;

[0041] FIG2( b ) is a schematic diagram of the large diameter reaming drill bit of the present invention in the drill withdrawal state;

[0042] Figure 3 It is a schematic diagram of the structure of the fixing sleeve of the large-diameter hole-reaming drill bit of the present invention;

[0043] Figure 4 It is a schematic diagram of the main structure of the large-diameter hole-reaming drill bit of the present invention;

[0044] Figure 5 It is a schematic diagram of the sliding shaft structure of a large-diameter hole-reaming drill bit of the present invention;

[0045] Figure 6 It is a schematic diagram of the structure of the auxiliary drill body of the large-diameter hole-reaming drill of the present invention;

[0046] Figure 7 It is a schematic diagram of the structure of the centralizer supporting the large-diameter hole section expansion drill bit of the present invention;

[0047] Figure 8 It is a schematic diagram of the front rod structure of the centralizer of the present invention;

[0048] Fig. 9 2 is a schematic diagram of the structure of the centralizing wing of the centralizer of the present invention;

[0049] Fig.10 It is a schematic diagram of the positioning block structure of the centralizer of the present invention;

[0050] Fig.11 It is a schematic diagram of the rear rod structure of the centralizer of the drilling tool assembly of the present invention;

[0051] Fig.12 This is a schematic diagram of the principle of a large-diameter hole expansion drilling tool assembly for removing slag and forming holes in underground coal mines of the present invention;

[0052] The reference numerals in the figure are as follows: 1-reamer drill bit, 2-stabilizer, 3-drill rod, 4-water feeder, 5-sealing ball, 6-pilot borehole, 7-large diameter borehole, 8-borehole wall sediment, 9-stratum;

[0053] 101-guide short section, 102-ball head hinge shaft, 103-fixed sleeve, 104-reaming drill body, 105-sliding shaft, 106-auxiliary drill body, 107-limiting short section;

[0054] 1031-inner cone, 1032-U-shaped groove, 1033-inner spherical surface;

[0055] 1041-wing, 1042-guiding groove, 1043-hole bottom flow channel, 1044-ball socket, 1045-blocking ball seat, 1046-PDC composite sheet, 1047-convex cone surface;

[0056] 1051-guide key, 1052-first through-flow groove, 1053-radial flow channel, 1054-second through-flow groove, 1055-central flow channel, 1056-first cylinder;

[0057] 1061- auxiliary wing, 1062- guide keyway, 1063- auxiliary guide groove, 1064- sliding cavity, 1065- liquid flow hole, 1066- concave cone surface, 1067- connecting groove, 1068- hard alloy cutting tooth; 1069- second cylinder;

[0058] 201-front rod body, 202-righting wing, 203-bolt, 204-limiting block, 205-rear rod body;

[0059] 2011-mounting rod, 2012-first mounting slot, 2013-second mounting slot, 2014-central flow channel, 2015-third mounting slot;

[0060] 2022-window, 2023-limiting groove, 2024-straight rib plate, 2025-dovetail rib plate, 2026-locking hole;

[0061] 2041- rectangular block, 2042- fan-shaped block, 2043- limiting hole;

[0062] 2051-connecting support section, 2052-center channel, 2053-limiting truncated table.

[0063] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0064] It should be noted that, unless otherwise specified, all components in the present invention are components known in the art.

[0065] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0066] See also Figure 1 to Figure 6 The present invention provides a large-diameter hole section reaming drilling tool assembly for underground coal mines, comprising a reaming drill bit 1, a plurality of drill rods 3 and a water feeder 4 connected in sequence, and a centralizer 2 is arranged between some adjacent drill rods 3;

[0067] Referring to FIG. 2 , the reaming drill bit 1 comprises a sliding shaft 105, an auxiliary drill body 106 is movably sleeved in the middle of the sliding shaft 105, a limiting short section 107 is sleeved at the axial rear end of the sliding shaft 105, a reaming drill body 104 is sleeved at the axial front end of the sliding shaft 105, a fixing sleeve 103 is sleeved at the axial front end of the reaming drill body 104, an axial rear end of a ball-end articulated shaft 102 is arranged in the fixing sleeve 103, and a guide short section 101 is arranged at the axial front end of the ball-end articulated shaft 102;

[0068] See also Figure 3 The axial front end surface of the fixing sleeve 103 is evenly provided with a plurality of U-shaped grooves 1032, and the inner cavity of the fixing sleeve 103 is a spherical cavity 1033 and a conical cavity 1031 which are connected;

[0069] See also Figure 4 The reaming drill bit body 104 comprises a body, a plurality of rib wings 1041 are evenly arranged on the axial front end surface of the body, a PDC composite sheet 1046 with different diameters welded is arranged on the front end surface of each rib wing 1041, a guide groove 1042 distributed along the axial direction is formed between adjacent rib wings 1041, a ball socket 1044 is arranged in the middle of the body, a blocking ball seat 1045 connected to the ball socket 1044 is arranged at the axial rear end of the body, a hole bottom flow channel 1043 evenly distributed along the circumferential direction is opened on the inner wall of the blocking ball seat 1045, the hole bottom flow channel 1043 comprises radial holes and axial holes that are connected and evenly distributed along the circumferential direction, and the axial hole is connected to the outside of the reaming drill bit body 104;

[0070] See also Figure 5 The sliding shaft 105 includes a first cylinder 1056, and a plurality of guide keys 1051 are arranged on the outer wall of the first cylinder 1056 at equal intervals in the circumferential direction. The guide keys 1051 are provided with a first flow groove 1052 and a second flow groove 1054 of different depths and connected. The second flow groove 1054 is provided with a radial flow channel 1053, and the radial flow channel 1053 is connected with the inner cavity of the first cylinder 1056, the first flow groove 1052 and the second flow groove 1054;

[0071] See also Figure 6The auxiliary drill body 106 includes a second cylinder 1069, and auxiliary rib wings 1061 are evenly arranged at the axial front end of the outer wall of the second cylinder 1069. The auxiliary rib wings 1061 correspond to the guide grooves 1042 of the reaming drill body 104 in a circumferential direction, and the axial rear end of the auxiliary rib wings 1061 is provided with cemented carbide cutting teeth 1068;

[0072] The circumferential width of the auxiliary wing 1061 is greater than the width of the guide groove 1042 on the reaming drill body 104, and the circumferential width of the auxiliary guide groove 1063 is less than the width of the wing 1041 on the reaming drill body 104;

[0073] A plurality of guide key grooves 1062 are arranged at equal intervals along the circumferential direction on the inner wall of the second cylinder 1069, and the plurality of guide key grooves 1062 are matched one by one with the plurality of guide keys 1051 on the outer wall of the sliding shaft 105; a connecting groove 1067 is opened on the inner wall of the second cylinder 1069, and the connecting groove 1067 is connected with the guide key groove 1062;

[0074] A sliding cavity 1064 is formed at the axial rear end of the inner wall of the second cylinder 1069, and a plurality of liquid flow holes 1065 are formed evenly along the circumferential direction on the side wall of the sliding cavity 1064;

[0075] In the above technical solution, when the reaming drill bit 1 is in the drilling state, the auxiliary drill bit body 106 and the reaming drill bit main body 104 are axially separated, and the guide groove 1042 and the auxiliary guide groove 1063 are axially connected; when the reaming drill bit 1 is in the retracting state, due to the movement of the auxiliary drill bit body 106, the auxiliary guide groove 1063 of the auxiliary drill bit body 106 overlaps with the rib wing 1041 of the reaming drill bit main body 104, and the guide groove 1042 of the reaming drill bit main body 104 overlaps with the auxiliary rib wing 1061 of the auxiliary drill bit body 106, and the guide groove 1042 and the auxiliary guide groove 1063 are axially disconnected. The multiple guide key grooves 1062 arranged axially on the inner side of the auxiliary drill bit body 106 cooperate with the guide key 1051 on the outer side of the sliding shaft 105 to meet the requirements of axial sliding and circumferential torque transmission;

[0076] The U-shaped groove 1032 is used to rotate the fixing sleeve 103 so that it can be connected and disassembled with the reaming drill body 104 through threads; the conical cavity 1031 is used to limit the floating range of the guide short section 101 and the ball head hinge shaft 102, and the spherical cavity 1033 is used to cooperate with the ball head hinge shaft 102 to realize the conical swing function.

[0077] The PDC composite sheet 1046 is used for cutting, crushing rocks and expanding holes for drilling; the guide groove 1042 is a circulation channel for drilling circulating water; the ball socket 1044 is used to install the ball head hinge shaft 102; the bottom hole flow channel 1043 is used as a flow channel for water flow to flush the expanding hole and crushing the rock surface and cool the PDC composite sheet 1046;

[0078] The number of the auxiliary ribs 1061 is the same as that of the ribs of the reamer drill body 104. The cemented carbide cutting teeth 1068 inlaid at the rear end of the auxiliary ribs 1061 are used to assist in hole repairing during the back drilling process.

[0079] A connecting groove 1067 is arranged circumferentially inside the auxiliary drill bit body, which serves as a water flow channel to ensure reliable sliding of the auxiliary drill bit; the inner side of the rear end of the auxiliary drill bit body 106 is a sliding cavity 1064, which cooperates with the limiting short section 107 to achieve axial sliding and limiting; a liquid flow hole 1065 is opened on the side wall of the sliding cavity 1064, which is used to assist in slag discharge during the drilling process.

[0080] See also Fig.12 The structure of the large-diameter hole section reaming drill tool combination in a coal mine is 'water feeder 4+N×drill rod 3+stabilizer 2+N×drill rod 3+...+reaming drill bit 1'. The reaming drill is carried out along the pilot hole 6 to form a large-diameter hole 7 at the designed depth. Before the drill is withdrawn, a plugging ball 5 is put into the central channel of the drill tool, and the ball seat of the reaming drill bit 1 at the bottom of the hole is flushed with water to block the downward channel of the water flow; during the withdrawal process, the reaming drill bit 1 collects the sediment 8 on the hole wall together by the 'piston' action principle and pushes it out of the hole mechanically; when the pulling force increases during the withdrawal process, the water feeder 4 is connected to the drill rod column, and high-pressure water is injected into the hole. With the cooperation of the plugging ball 5, the water flows directly into the annulus through the rear end of the combined reaming drill bit 1, cooperates with the rotation and stirring of the drill tool to disperse the drill slag accumulated at the rear end of the drill bit, and carries the slag upward to reduce the resistance to lifting the drill;

[0081] After the reaming drill bit 1 is pulled out, the drill cuttings deposited on the lower side of the hole are discharged out of the hole. During the mechanical slag discharge process of the reaming drill bit 1, its cylindrical "piston" structure will not cause damage to the stratum 9 on the lower side of the hole wall during the drilling withdrawal process, and can keep the hole wall regular, which is conducive to lowering the casing.

[0082] The reaming drill bit is composed of a separate reaming drill bit body 104 and an auxiliary drill bit body 106. The auxiliary drill bit body can be axially movable and displaced on the sliding shaft 105. During the drilling withdrawal process, the assembly is in the shape of a "piston", which can collect the sediment in the borehole and discharge it out of the hole in a mechanical push-out manner, creating favorable conditions for lowering the casing in different posture hole sections, and the comprehensive pipe lowering efficiency can be improved by more than 30%; in addition, the radial ribs of the reaming drill bit body 104 and the auxiliary drill bit body 106 correspond to the misalignment of the guide groove, and the overall outer contour is a cylindrical surface; during the rotary drilling and axial pushing and pulling process, the ribs of the drill bit body will not have a significant destructive effect on the lower side of the hole wall formation, will not produce "pseudo drill residues", can keep the hole wall relatively intact and regular in cross section, and has a more obvious protective effect on the hole wall of the softer layer section, which is conducive to lowering the casing, and the casing lowering success rate can reach more than 95%, solving the technical problems of complex combination of existing multi-stage reaming drill tools in large-diameter hole sections, large workload and low efficiency in replacing drill tools.

[0083] The present invention also includes the following technical features:

[0084] See also Figure 7 , Figure 8 , Fig. 9 and Fig.11 The centralizer 2 includes a front rod body 201 and a rear rod body 202 connected to each other; a plurality of centralizing wings 202 are sleeved at the connection between the front rod body 201 and the rear rod body 202, and the plurality of centralizing wings 202 form a cylinder.

[0085] The front rod body 201 includes a mounting rod body 2011, on the outer wall of the mounting rod body 2011, a plurality of dovetail grooves 2012 and a plurality of rectangular grooves 2013 are arranged alternately along the circumferential direction, a third mounting groove 2015 is opened on the outer wall of the mounting rod body 2011, and the third mounting groove 2015 is perpendicular to and connected with the dovetail groove 2012 and the plurality of rectangular grooves 2013; a central flow channel 2014 is opened inside the front rod body 201;

[0086] The rear rod body 202 includes a connecting support section 2051 and a limiting truncated cone 2053 connected in the axial direction. The outer diameter of the connecting support section 2051 is the same as the cylindrical surface of the drill rod 3, and the outer diameter of the limiting truncated cone 2053 is the same as the outer diameter of the mounting rod body 211 of the front rod body 201. A central channel 2052 is opened inside the rear rod body 202.

[0087] A straight rib plate 2024 is respectively provided at both circumferential ends of the inner wall of each righting wing 202, and the straight rib plate 2024 is located in the rectangular groove 2013. A dovetail rib plate 2025 is provided in the middle of the inner wall of the righting wing 202, and the dovetail rib plate 2025 is located in the dovetail groove 2012. A limiting groove 2023 is provided on the dovetail rib plate 2025, and a limiting block 204 is provided in the limiting groove 2023.

[0088] See also Figure 7 , 8 , 9 and Fig.11 , the central angle corresponding to a single righting wing 202 is 120°, and the diameter corresponds to the diameter of the expanded hole;

[0089] The central channel 2014 serves as a passage for water flow and ball pitching; the central channel 2052 also serves as a passage for water flow and ball pitching.

[0090] A locking hole 2026 is defined in the limiting groove 2023 , a limiting hole 2043 is defined on the limiting block 204 , and bolts 203 are disposed in both the limiting hole 2043 and the locking hole 2026 .

[0091] In the above technical solution, a locking hole 2026 is provided at a position corresponding to the limiting groove 2023 for installing the bolt 203 .

[0092] When withdrawing the drill and disassembling the centralizer 2, first remove the bolt 203 and the limit block 204, then withdraw and remove the centralizer wing 202 from the first mounting groove 2012 and the second mounting groove 2013 of the front rod body 201; the combination of the front rod body 201 and the rear rod body 205 is disassembled from the drilling rig by connecting the clamping rod body 2051;

[0093] The limiting block 204 includes a rectangular block 2041 and a sector block 2042 . The rectangular block 2041 cooperates with the limiting groove 2023 on the righting wing 202 ; the sector block 2042 cooperates with the third mounting groove 2015 on the front rod body 201 .

[0094] In the above technical solution, the limiting block 204 is used to limit the axial position of the righting wing 202 on the front rod body 201 .

[0095] The outer wall of the first cylinder 1056 is in a step shape with an increasing diameter along the axial direction, and the outer wall of the axial rear end of the first cylinder 1056 is tapered.

[0096] In the above technical solution, it is used as a matching surface corresponding to the auxiliary drill body 106.

[0097] The axial rear end face of the rib wing 1041 of the reaming drill body 104 is provided with a conical surface, and the axial front end face of the auxiliary rib wing 1061 of the auxiliary drill body 106 is provided with a conical surface with the same angle as the axial rear end face of the rib wing 1041 .

[0098] In the above technical solution, when the reaming drill bit 1 is in the retracted state, the conical surface of the auxiliary drill bit body 106 overlaps with the conical surface of the reaming drill bit body 104, and the two are fitted together, and the guide groove 1042 and the auxiliary guide groove 1063 are axially closed.

[0099] A plurality of windows 2022 are provided on the righting wing 202 .

[0100] In the above technical solution, the window 2022 is provided, on the one hand, to provide an operating space for disassembling and assembling the limit block 204, and on the other hand, to reduce weight.

[0101] Example:

[0102] This embodiment provides a method for drilling a large-diameter hole section in a coal mine using a hole-reaming drill assembly, comprising the following steps:

[0103] Step 1: Use a small-diameter drill bit and drill rod to construct a pilot hole to the designed depth, and then withdraw the drill rod and small-diameter drill bit in sequence;

[0104] Step 2: Use the ball-end articulated shaft 102, the fixed sleeve 103 and the limit short section 107 to assemble and connect the guide short section 101, the reaming drill bit body 104, the sliding shaft 105 and the auxiliary drill bit body 106 together, connect the drill rod 3 and the water feeder 4 to the limit short section 107, put the guide short section 101 into the pilot hole 6, start the mud pump water supply cycle, and the drilling rig rotates the drill rod 3 to drive the reaming drill bit body 104 and the auxiliary drill bit body 106 to rotate synchronously, and reaming and drilling along the pilot hole 6 under the guidance of the guide short section 101; during the reaming drilling process, the auxiliary drill bit body 106 is axially separated and disengaged from the reaming drill bit body 104 due to the friction resistance of the hole wall, and the auxiliary drill bit body 106 is The sliding cavity 1064 is occupied by the limiting short section 107, and the water flow channel of the liquid flow hole 1065 is closed. Most of the circulating water that reaches the central flow channel 1055 of the sliding shaft 105 through the central flow channel of the drilling tool flows out through the bottom flow channel 1043 on the reaming drill bit body 104, cools the PDC composite plate 1046, and carries drill cuttings through the guide groove 1042 and the auxiliary guide groove 1063 into the borehole annulus and returns; a small part of the circulating water enters the first flow groove 1052 and the connecting groove 1067 on the auxiliary drill bit body 106 through the radial flow channel 1053 of the sliding shaft 105, and then flows out from the space between the auxiliary drill bit body 106 and the reaming drill bit body 104, which can prevent drill cuttings from entering the guide key groove 1062.

[0105] Step 3: During the hole expansion process, add the front rod body 201 and the rear rod body 205 of the centralizer to the drill pipe 3 in the hole at intervals of 10m to 15m, then clamp the three centralizing wings 202 in the first installation groove 2012 and the second installation groove 2013 of the front rod body 201 through the straight rib plate 2024 and the dovetail rib plate 2025, and make the end face of the centralizing wing 202 fit with the end face of the upper limit round table 2053 of the rear rod body 205; install the three limit blocks 204 on the front rod body 2 through the window 2022 on the centralizing wing 202 01, and align the limiting hole 2043 on the limiting block 204 with the locking hole 2026 on the righting wing 202, screw on the bolt 203, the rectangular block 2041 of the limiting block 204 is located in the limiting groove 2023 of the righting wing 202, and the fan-shaped block 2042 of the limiting block 204 is located in the third installing groove 2015 of the front rod body 201 of the centralizer, so as to realize the axial positioning of the righting wing 202 and the front rod body 201, and then connect the drill rod 3 to the rear end rod body 201 of the centralizer, and continue to expand the hole and drill.

[0106] Step 4: Deslagging of local hole sections In the downward inclined reaming state, the drill can be withdrawn midway for mechanical deslagging of local hole sections at intervals of 15m to 30m in hole depth and in combination with the return of slag at the hole mouth during reaming drilling; during the process of withdrawing the drill, the auxiliary drill body 106 slides axially relative to the guide key 1051 on the sliding shaft 105 under the action of reverse friction resistance, and fits together with the reaming drill body 104, that is, the conical surface of the front end of the auxiliary drill body 106 coincides with the conical surface of the rear end of the reaming drill main body 104, the auxiliary ridge 1061 and the auxiliary guide groove 1063 of the auxiliary drill body 106 correspond crosswise with the guide groove 1042 and the ridge 1041 of the reaming drill body 104, and the axial flow channel is blocked to form a "piston" body, so as to perform one-time efficient mechanical deslagging of the large diameter hole section.

[0107] Step 5: Progressively expand the hole. After deslagging the local hole section, drill again to continue expanding the hole. Depending on the length of the expanded hole section and the slag return during the expansion process, step 4 can be repeated at certain intervals until the drilling and expansion reaches the predetermined depth.

[0108] Step 6: Drilling back to form a hole Before drilling back, the sealing ball 5 is put into the central channel of the drill rod 3, and is flushed to the sealing ball seat 1045 in the reaming drill body 104 at the bottom of the hole by water flow to block the flow channel 1043 at the bottom of the hole; during the drilling back process, the reaming drill body 104 and the auxiliary drill body 106 are fitted together, at this time, the limit short section 107 is withdrawn from the sliding cavity 1064 of the reaming drill body 106, and the water flow channel of the liquid flow hole 1065 is opened; the reaming drill body 104 and the auxiliary drill body 106 act in a "piston" manner Principle: The drilling sediment 8 is collected at the rear end of the reaming drill bit 1 and pushed to the hole mouth; when the pulling force of the drill tool becomes larger during the withdrawal of drilling, the water feeder 4 is connected to the drill pipe column 3, and circulating water is injected into the hole. The circulating water that reaches the reaming drill bit 1 through the central flow channel of the drill pipe 3 all enters the sliding cavity 1064 of the auxiliary drill bit body 106 through the radial flow channel 1053 of the sliding shaft 105 and the second flow channel 1054, and then flows out from the liquid flow hole 1065, stirring and dispersing the drilling sediment 8 accumulated at the rear end of the reaming drill bit 1, thereby reducing the resistance to withdrawing drilling.

[0109] Step 7: Lower the casing and seal it. Lower the casing into the large diameter borehole and seal it with grouting as needed.

[0110] When withdrawing the drill and disassembling the centralizer 2, first remove the centralizing wing 202, and then use the drilling rig to mechanically disassemble the front and rear rods; after the reaming drill bit 1 is lifted out, the drill cuttings deposited on the lower side of the hole are discharged out of the hole together, and the cylindrical profile surface structure of the reaming drill bit 1 will not cause damage to the stratum 9 on the lower side of the hole wall during the withdrawal process, and the hole wall is kept regular, which is conducive to lowering the casing.

Claims

1. A large-diameter hole section reaming drilling tool assembly for underground coal mines, comprising a reaming drill bit (1), a plurality of drill rods (3) and a water feeder (4) connected in sequence, wherein a centralizer (2) is arranged between some adjacent drill rods (3), characterized in that: The reaming drill bit (1) comprises a sliding shaft (105), an auxiliary drill body (106) is movably sleeved in the middle of the sliding shaft (105), a limiting short section (107) is sleeved at the axial rear end of the sliding shaft (105), a reaming drill bit body (104) is sleeved at the axial front end of the sliding shaft (105), a fixing sleeve (103) is sleeved at the axial front end of the reaming drill bit body (104), an axial rear end of a ball-end hinge shaft (102) is arranged in the fixing sleeve (103), and a guide short section (101) is arranged at the axial front end of the ball-end hinge shaft (102); The axial front end surface of the fixing sleeve (103) is evenly provided with a plurality of U-shaped grooves (1032); the inner cavity of the fixing sleeve (103) is a spherical cavity (1033) and a conical cavity (1031) that are connected; The reaming drill bit body (104) comprises a body, a plurality of rib wings (1041) are evenly arranged on the axial front end surface of the body, a PDC composite sheet (1046) with different diameters welded is arranged on the front end surface of each rib wing (1041), and a flow guide groove (1042) distributed along the axial direction is formed between adjacent rib wings (1041), a ball socket (1044) is arranged in the middle of the body, a blocking ball seat (1045) connected to the ball socket (1044) is arranged at the axial rear end of the body, and a hole bottom flow channel (1043) evenly distributed along the circumferential direction is opened on the inner wall of the blocking ball seat (1045), and the hole bottom flow channel (1043) includes radial holes and axial holes that are connected and evenly distributed along the circumferential direction, and the axial hole is connected to the outside of the reaming drill bit body (104); The sliding shaft (105) comprises a first cylinder (1056), a plurality of guide keys (1051) are arranged on the outer wall of the first cylinder (1056) at equal intervals in the circumferential direction, a first flow groove (1052) and a second flow groove (1054) of different depths and connected are provided on the guide key (1051), a radial flow channel (1053) is arranged in the second flow groove (1054), and the radial flow channel (1053) connects the inner cavity of the first cylinder (1056), the first flow groove (1052) and the second flow groove (1054); The auxiliary drill body (106) comprises a second cylinder (1069), the axial front end of the outer wall of the second cylinder (1069) is evenly provided with auxiliary rib wings (1061), the auxiliary rib wings (1061) correspond to the guide grooves (1042) of the reamer drill body (104) in a circumferential direction, and the axial rear end of the auxiliary rib wings (1061) is provided with cemented carbide cutting teeth (1068); The circumferential width of the auxiliary rib wing (1061) is greater than the width of the guide groove (1042) on the reaming drill body (104), and the circumferential width of the auxiliary guide groove (1063) is less than the width of the rib wing (1041) on the reaming drill body (104); A plurality of guide key grooves (1062) are arranged at equal intervals along the circumferential direction on the inner wall of the second cylinder (1069), and the plurality of guide key grooves (1062) are matched one-to-one with the plurality of guide keys (1051) on the outer wall of the sliding shaft (105); a connecting groove (1067) is provided on the inner wall of the second cylinder (1069), and the connecting groove (1067) is connected with the guide key groove (1062); A sliding cavity (1064) is provided at the axial rear end of the inner wall of the second cylinder (1069), and a plurality of liquid flow holes (1065) are evenly provided on the side wall of the sliding cavity (1064) along the circumferential direction.

2. The large-diameter hole section expansion drilling tool assembly for underground coal mines as claimed in claim 1, characterized in that: The centralizer (2) comprises a front rod body (201) and a rear rod body (202) which are connected to each other; a plurality of centralizing wings (202) are sleeved at the connection between the front rod body (201) and the rear rod body (202), and the plurality of centralizing wings (202) form a cylinder.

3. The large-diameter hole section expansion drilling tool assembly for underground coal mines as claimed in claim 2, characterized in that: The front rod body (201) comprises a mounting rod body (2011), a plurality of dovetail grooves (2012) and a plurality of rectangular grooves (2013) are arranged alternately along the circumferential direction on the outer wall of the mounting rod body (2011), a third mounting groove (2015) is provided on the outer wall of the mounting rod body (2011), and the third mounting groove (2015) is perpendicular to and connected with the dovetail groove (2012) and the plurality of rectangular grooves (2013); a central flow channel (2014) is provided inside the front rod body (201); The rear rod body (202) comprises a connection support section (2051) and a limiting truncated cone (2053) connected in the axial direction, the connection support section (2051) is a cylindrical surface with the same outer diameter as the drill rod (3), and the limiting truncated cone (2053) has the same outer diameter as the mounting rod body (211) of the front rod body (201); a central channel (2052) is provided inside the rear rod body (202); A straight rib plate (2024) is respectively provided at two circumferential ends of the inner wall of each of the righting wings (202), and the straight rib plate (2024) is located in the rectangular groove (2013). A dovetail rib plate (2025) is provided in the middle of the inner wall of the righting wing (202), and the dovetail rib plate (2025) is located in the dovetail groove (2012). A limiting groove (2023) is provided on the dovetail rib plate (2025), and a limiting block (204) is provided in the limiting groove (2023).

4. The large-diameter hole section expansion drilling tool assembly for underground coal mines as claimed in claim 3, characterized in that: A locking hole (2026) is provided in the limiting groove (2023); a limiting hole (2043) is provided on the limiting block (204), and a bolt (203) is provided in both the limiting hole (2043) and the locking hole (2026).

5. The large-diameter hole section expansion drilling tool assembly for underground coal mines as claimed in claim 3, characterized in that: The limiting block (204) comprises a rectangular block (2041) and a fan-shaped block (2042); the rectangular block (2041) cooperates with the limiting groove (2023) on the righting wing (202); and the fan-shaped block (2042) cooperates with the third installation groove (2015) on the front rod body (201).

6. The large-diameter hole section expansion drilling tool assembly for underground coal mines as claimed in claim 1, characterized in that: The outer wall of the first cylinder (1056) is in a step-like shape with an increasing diameter along the axial direction, and the outer wall of the axial rear end of the first cylinder (1056) is conical.

7. The large-diameter hole section expansion drilling tool assembly for underground coal mines as claimed in claim 1, characterized in that: The axial rear end face of the rib wing 1041 of the reaming drill body (104) is provided with a conical surface, and the axial front end face of the auxiliary rib wing (1061) of the auxiliary drill body (106) is provided with a conical surface with the same angle as the axial rear end face of the rib wing 1041.

8. The large-diameter hole section expansion drilling tool assembly for underground coal mines as claimed in claim 1, characterized in that: The righting wing (202) is provided with a plurality of windows (2022).

9. A method for drilling a large-diameter hole section in a coal mine using a drilling tool assembly, characterized in that: Based on the large-diameter hole section expansion drilling tool assembly of any one of claims 1 to 8, the invention specifically comprises the following steps: Step 1, using a small diameter drill bit and a drill rod to construct a pilot hole 1 to a designed depth, and then withdrawing the drill rod and the small diameter drill bit in sequence; Step 2: lower the guide sub of the reaming drill bit 1 into the pilot hole 1 obtained in step 1, start the mud pump, and high-pressure water enters the water feeder 4 through the pipeline. After reaching the bottom of the hole, the high-pressure water cools the PDC composite sheet 1046 and carries the drill cuttings out of the borehole; Step 3: After the hole is expanded to a certain depth, observe the slag return at the hole mouth and perform mechanical slag removal by lifting the drill in the local hole section; The local hole section drilling mechanical slag removal adopts a 'piston' body composed of an auxiliary drill bit body 106 and a reaming drill bit body 104 to collect the drill slag deposited in the expanded hole section and push it out into the hole; Step 4, re-drilling and continuing to expand the hole, and repeating step 3 at intervals of a certain hole depth according to the length of the expanding section and the slag return during the expanding process until the hole is expanded to a predetermined depth, thereby obtaining a large-diameter drill hole 7; Step 5, pull back the large-diameter hole section reaming drill assembly in the coal mine in a short distance and rotate it slowly, so that the auxiliary drill body 106 and the reaming drill body 104 are attached together to form a combination, put a sealing ball into the center hole of the drill rod 3, and flush it into the reaming drill body 104 at the bottom of the hole with water; Step 6, start to withdraw the drill, the reaming drill bit 1 collects the sediment in the borehole at its rear end and discharges it mechanically; when the pull-back resistance of the drill increases significantly during the withdrawal, turn on the mud pump to inject water into the hole to stir and disperse the drill residue accumulated at the rear end of the reaming drill bit 1, and continue to withdraw the drill until the reaming drill bit 1 is out of the hole, completing the slag removal and hole forming; Step 7, insert casing into the obtained large diameter borehole and seal it by grouting as needed.

10. The method for drilling a hole with a large diameter hole section expansion drill assembly in a coal mine as claimed in claim 9, characterized in that: Also includes: At certain intervals, a centralizer is added to the drill rod in the hole and sent into the hole to continue expanding the hole and drilling.

Images