CN114837553A

CN114837553A - Cross-layer drilling extraction type drilling tool and blowout-preventing hole while-drilling gas extraction method

Info

Publication number: CN114837553A
Application number: CN202210251353.3A
Authority: CN
Inventors: 孙玉宁; 李延河; 赵同谦; 李振华; 宋维宾; 王志明; 张海庆; 马建宏
Original assignee: Henan University of Technology
Current assignee: Henan University of Technology
Priority date: 2022-03-15
Filing date: 2022-03-15
Publication date: 2022-08-02

Abstract

The invention discloses a cross-layer drilling extraction type drilling tool and a blowout prevention hole while-drilling gas extraction method, wherein the extraction type drilling tool comprises a plurality of extraction type drilling rods, an extraction type high-low pressure conversion valve, a sieve pore air inlet device, an open-close type drill bit and an extraction type water swivel; the extraction type drill rod consists of an outer pipe and an inner pipe, an extraction type high-low pressure conversion valve consists of an outer valve pipe, an inner valve pipe and a high-low pressure conversion assembly, a sieve mesh air inlet device consists of a convex rib-shaped outer pipe, a convex rib-shaped inner pipe and an air inlet sieve plate, the inner pipes of different names are mutually sealed and connected to form a gas extraction channel of the drilling tool, the axial space between the inner pipe of the same name and the outer pipe of the same name is a flow supply channel of the drilling tool, the space between the outer surface of the drilling tool and the wall of a drilled hole is a slag discharge channel, and the extraction type drilling tool is provided with a spray control drainage box in a matching way at the hole opening.

Description

Cross-layer drilling extraction type drilling tool and blowout-preventing hole while-drilling gas extraction method

Technical Field

The invention relates to the technical field of coal mine gas extraction drilling, in particular to the technical field of drilling, slotting and punching of a cross-layer drilling hole of an outburst coal seam.

Background

And constructing a cross-layer drill hole in a bottom plate rock roadway of the outburst coal seam, and extracting gas from a region to be excavated or a region to be mined of the outburst coal seam to achieve outburst elimination and standard extraction, which are main measures for extracting and treating the gas of the outburst coal seam. In order to fully exert the extraction outburst elimination effect of the cross-layer drill hole, the hydraulic anti-reflection operation of 'slotting' or 'punching' is generally implemented on the coal hole section of the cross-layer drill hole. The current state of the prior art is as follows: the adopted drill rods are commonly slotted drill rods, rib drill rods, triangular slotted drill rods or triangular drill rods and the like, wherein original patent applications of the first three drill rods are the applicant, namely the university of Henan marble, and the patent numbers are ZL200610111830.7, ZL200920088879.4 and ZL200910064973.0 respectively, a high-pressure and low-pressure conversion device with a high-pressure water jet nozzle is arranged between the drill rods and a drill bit, an inner hole of each drill rod is a flow supply channel, and the drilling of a coal hole section is slit or punched, and the drill rod is also called as hydraulic slitting, hydraulic hole making, hydraulic channeling, hydraulic coal drawing and the like by students. As the drill rod is of a single-pipe structure, the function of lowering the hole-protecting sieve pipe during withdrawal of the drill is lost after the high-low pressure conversion device is arranged. The drilling machine is characterized in that a drill bit is arranged on the drill head, a water jet nozzle for punching is directly arranged on the drill head, and a drill bit is arranged on the drill head.

When the cross-layer drilling hole is used for slotting or punching, high-pressure water is used as a drill bit for cooling, jet power and slag discharging power, and a slag discharging channel is positioned between the outer wall of a drill rod and the inner wall of the drilling hole and is called as an outer slag discharging channel. The outburst coal seam cross-layer drilling hole generates a large amount of water coal slag and gas in the process of implementing slotting or punching force permeability increase at a coal hole section, dynamic phenomena of outburst of coal and gas in the hole, coal blasting and the like often occur at the coal hole section, the output amount of the coal slag is extremely uneven, the particle size of the coal slag is uneven, the coal slag does not have fluidity, and the coal slag is required to be converted into a flowable solid-liquid-phase water coal slag fluid by utilizing the water flow effect and the drill rod rotary stirring slag crushing effect and is discharged out of a discharge hole of an outward slag discharge channel of the drilling hole. Because the cinder produced by slotting or punching of the coal hole section has burst property and imbalance, the cinder rushes to an external slag discharge channel of the rock hole section with narrow space by virtue of self-weight action and water flow action, the cinder cannot be timely converted into a flowable solid-liquid-phase water cinder body by virtue of water flow action and drill rod rotation stirring action, non-permeable blockage of the external slag discharge channel of the rock hole section is frequently caused, namely the water cinder inside the cross section of the slag discharge channel occupies 100 percent of the cross section, the water cinder leaks downwards and gas is retained in the slotted or punched coal body and in the cave, the continuous desorption of the gas can cause the gas pressure inside the loose coal body and in the cave of the coal hole section to be far larger than the atmospheric pressure outside the hole, and under the action of water flow and drill rod rotation stirring, once the external slag discharge channel blocked by non-permeability of the rock hole section is dredged, high-pressure gas and water cinder can be sprayed out from a large number of orifices, and even form continuity, The gas of a roadway is often over-limited due to the long-time spraying of the holes, and the gas over-limit accidents of the holes sprayed by the cross-layer drilling account for 30% -80% of the total number of the gas over-limit accidents of the outburst mine, so that the gas over-limit accidents of the outburst mine are important potential safety hazards of the outburst mine.

When the existing outburst coal seam cross-layer drilling is drilled, an orifice is generally provided with a blowout prevention hole device, the blowout prevention hole device generally comprises a collecting box, an exhaust pipe and a water coal slag discharge pipe, gas generated by spraying holes is prevented from diffusing to a roadway space, and when the spraying holes are serious, the blowout prevention hole device can fail to cause the concentration of the roadway gas in a drilling operation place to exceed the limit. A plurality of patents have been reported about gas extraction drilling blowout prevention hole technology, and various orifice blowout prevention devices are designed according to local conditions aiming at specific underground environments. For example, only in 2021 were patents reported relating to blowout preventer ports: blowout preventer devices and systems (CN 202120284095X); a gas control dustproof blowout hole preventing device (CN 202120183981.3); a drilling and spray hole prevention dust removal device (CN 202120116187.7) for coal mines; a semi-open blowout preventer assembly and a gas control collection and discharge device (CN 202120080173.4); an automatic blowout hole preventing device (CN 202120006760.9) of a gas extraction system; a coal mine underground hydraulic punching orifice-preventing and coal amount-measuring device (CN 202121828212.0); a gas control blowout hole preventing device (CN 202121728316.4); a gas control blowout hole preventing device (CN 202121249379.1); a gas control blowout preventer (CN 202120004386.9) convenient to install. The basic starting points of the blowout-preventing hole technical patents are similar, namely, water coal slag and gas sprayed out of a drill hole are collected and separated outside the hole, the gas enters an air exhaust pipe, the water coal slag enters a water coal slag discharge pipe or further enters a water coal slag gas separation box, the gas is prevented from flowing into a roadway space as far as possible, if gas abnormal zones, coal and gas in the hole are protruded and the like, the blowout-preventing devices crack due to insufficient volume of a collecting box, the air exhaust pipe is not enough in extraction speed to break away or crack, a buffer air bag is not enough in volume to burst and the like when the blowout holes are serious, and the gas overrun accident of the blowout holes still can be caused. In a strict cause and effect relationship, the existing blowout preventing hole device cannot prevent the occurrence of the spraying hole phenomenon, but is used for preventing the gas overrun accident during the spraying hole occurrence.

A great deal of engineering practice of drilling, slotting or punching holes for outburst coal seam crossing layers shows that the traditional passive spray hole prevention method cannot fundamentally solve the problem of gas over-limit of spray holes, and a gas power source inducing the spray holes is eliminated from the source in order to solve the problem of gas over-limit of the spray holes. The gas power source of the jet holes is positioned in a loose coal body formed by slotting or punching at a coal hole section and a cave formed by slotting and punching, the loose coal body and the cave contain a large amount of free gas, for the convenience of subsequent description, a 'loose-hole gas bag' is called for short, solid (cinder), liquid (water) and gas (gas) simultaneously exist in the loose coal body and the cave, the gas is at a high position, the water cinder is at a lower position, and the gas is the gas power source for generating the jet holes. The coal body is subjected to large-range pressure relief through slotting or punching, a large amount of gas can be continuously desorbed from the coal body, when coal and gas in holes are protruded, a large amount of coal slag and gas can be suddenly generated, the range of a 'loose hole gas bag' is enlarged, the gas amount and gas pressure in the coal body can be increased, and a large amount of gas energy is accumulated for the generation of spray holes. In the inclined annular outer slag discharging channel of the cross-layer drilling hole, three-phase segregation media of solid, liquid and gas cannot be uniformly mixed and cannot be synchronously transported, the solid and the liquid can be transported to the outer slag discharging channel of the rock hole section by utilizing self weight, the gas can be discharged from the gap of the outer slag discharging channel by utilizing pressure difference, and the gas can be discharged downwards by utilizing the pressure difference only when the sum of the volumes of the solid and the liquid cannot be 100 percent full of the outer slag discharging channel. The actual situation at the site is: the discharged slag channel is filled with the water coal slag uninterruptedly, the gas cannot be discharged downwards in time, and the gas pressure in the 'loose hole gas bag' is increased continuously, so that a gas power source is accumulated for the spray holes. Based on the analysis of the background technology, aiming at a 'loose hole gas bag' hidden with a jet hole power source, the applicant proposes the concept of discharging water coal slag and gas in different ways, namely, through the design of a drilling tool, the water coal slag is led to leave an outer slag discharge channel between the outer surface of the drilling tool and the wall of a drill hole, gas in the 'loose hole gas bag' is led to leave a gas extraction channel at the center of the drilling tool, an extraction type drilling tool with the drilling function, the slotting and punching function, the gas extraction while drilling function and the function of lowering a hole protection sieve tube after the drill is removed is designed, the gas extraction while drilling is carried out by utilizing the extraction type drilling tool, and the gas power source inducing the jet hole is eliminated from the source.

Disclosure of Invention

The invention provides a cross-layer drilling extraction type drilling tool and a matched blowout-preventing hole while-drilling gas extraction method aiming at the problems in the prior art, wherein the extraction type drilling tool is used for extracting gas while drilling, the problem of orifice spraying phenomenon and orifice spraying gas overrun accidents in the water jet slotting or punching process of cross-layer drilling is solved, the safety of hydraulic permeability-increasing operation of cross-layer drilling is improved, and meanwhile, a gas extraction channel of the drilling tool is used as a channel for lowering a protection hole screen pipe during withdrawal of a drill.

The technical scheme adopted for achieving the purpose is as follows:

the cross-layer drilling extraction type drilling tool comprises an extraction type water braid, a plurality of extraction type drill rods, an extraction type high-low pressure conversion valve, a sieve pore air inlet device and an open-close type drill bit which are sequentially connected; and a controlled spraying type drainage box which is matched with the extraction type drill rod and is arranged at the orifice position. A gas extraction channel is constructed in the center of an inner cavity of a cross-layer drilling extraction type drilling tool, a flow supply channel of the drilling tool is constructed between an outer pipe and an inner pipe of an extraction type drilling rod of the cross-layer drilling extraction type drilling tool, a gas extraction channel is constructed for gas in a hole loosening gas bag, a slag discharge channel is constructed for water coal slag in the hole loosening gas bag, a gas power source inducing jet holes is timely eliminated by extracting gas in the hole loosening gas bag while drilling, and the gas extraction channel is used as a channel for discharging a protective hole screen pipe when the drilling is withdrawn.

Furthermore, the extraction type drill rod comprises an outer pipe and an inner pipe which are inserted and matched, the outer pipe protrudes from the inner hole of the outer pipe in a local hot extrusion mode along the length direction to form two groups of local cambered surface protrusions, the local cambered surface protrusions are matched with the excircle of the inner pipe and support and mount the inner pipe to enable the outer pipe and the inner pipe to keep coaxial, the number of the local cambered surface protrusions in each group is two or three, the local cambered surface protrusions are uniformly distributed along the circumference of the inner hole of the outer pipe, the outer surface of the outer pipe is in a spiral groove shape or a spiral rib shape or a triangular shape or a quadrangular shape or a triangular groove shape or a quadrangular groove shape, and therefore the slag crushing, stirring and conveying capacity of the drill rod is improved; the axial space between the outer pipe and the inner pipe is a flow supply channel of the extraction type drilling tool, the central hole of the inner pipe is a gas extraction channel, and the annular space between the outer pipe and the wall of the drilled hole is a slag discharge channel.

Furthermore, the extraction type drill rod comprises an outer pipe, an inner pipe and two groups of cambered surface supporting blocks brazed on the inner wall of the outer pipe, the extraction type drill rod comprises the outer pipe, the inner pipe and two groups of cambered surface supporting blocks welded on the inner wall of the outer pipe, two or three groups of supporting blocks are uniformly distributed along the circumference of the inner hole of the outer pipe in each group of supporting blocks, supporting block welding holes welded with the inner pipe are formed in the supporting blocks, outer pipe welding holes welded with the supporting blocks are formed in the outer pipe, the radius of the outer cambered surface of each supporting block is equal to the radius of the inner hole of the outer pipe, and the radius of the inner cambered surface of each supporting block is equal to the radius of the outer circle of the inner pipe; the outer shape of the outer pipe is spiral groove shape or spiral rib shape or triangular shape or quadrangular shape or triangular groove shape or quadrangular groove shape, so that the slag crushing, stirring and conveying capacity of the drill rod is improved; the axial space between the outer pipe and the inner pipe is a flow supply channel of the extraction type drilling tool, the central hole of the inner pipe is a gas extraction channel, and the annular space between the outer pipe and the wall of the drilled hole is a slag discharge channel.

Furthermore, the extraction type drill rod comprises an outer pipe and an inner pipe, the outer pipe is a special-shaped outer pipe, an axial groove is formed in the outer surface of the special-shaped outer pipe, an axial arc surface bulge corresponding to the axial groove is formed in an inner hole of the special-shaped outer pipe, the axial arc surface bulge of the inner hole of the special-shaped outer pipe is matched with the excircle of the inner pipe and supports the inner pipe to enable the outer pipe and the inner pipe to keep coaxial, two or three axial grooves and two or three axial arc surface bulges are uniformly distributed on the circumference of the axial groove and the axial arc surface bulge, and spiral grooves or spiral ribs are formed in the outer surface of the outer pipe to improve the slag crushing, stirring and conveying capacity of the drill rod; the axial space between the outer pipe and the inner pipe is a flow supply channel of the extraction type drilling tool, the central hole of the inner pipe is a gas extraction channel, and the annular space between the outer pipe and the wall of the drilled hole is a slag discharge channel.

Furthermore, the extraction type drill rod comprises an outer pipe and an inner pipe which are inserted and matched, the outer pipe is a hot-twisted special-shaped outer pipe formed by a hot-twisting method in a constraint state, a large spiral groove is formed in the outer surface of the hot-twisted special-shaped outer pipe, a large-pitch cambered surface bulge corresponding to the large spiral groove is formed in an inner hole of the hot-twisted special-shaped outer pipe, the large-pitch cambered surface bulge of the inner hole of the hot-twisted special-shaped outer pipe is matched with the excircle of the inner pipe to be installed, the inner pipe is supported to enable the outer pipe and the inner pipe to be coaxial, and the number of the large spiral groove and the large-pitch cambered surface bulge is two or three; the axial space between the outer pipe and the inner pipe is a flow supply channel of the extraction type drilling tool, the central hole of the inner pipe is a gas extraction channel, and the annular space between the outer pipe and the wall of the drilled hole is a slag discharge channel.

Furthermore, the extraction type drill rod can also comprise an outer pipe, an inner pipe and a support piece, wherein the support piece is arranged between the outer pipe and the inner pipe, and the support piece enables the outer pipe and the inner pipe to keep coaxial. The outer shape of the outer tube can be spiral groove shape, spiral convex rib shape, triangular shape or triangular groove shape, and the number of the grooves or the number of the convex ribs is two or more; the groove can be a rectangular groove, a trapezoidal groove, a cambered surface groove or a rifling-shaped groove; the convex rib can be welded, lathed and clad, the convex rib surface can be a plane convex rib and a cambered convex rib, the shape of the convex rib is not limited, and the width of the convex rib is equal to or greater than the height of the convex rib. The outer surface of the outer pipe is provided with grooves, convex ribs, arc edges and the like, and the function of the outer pipe is to increase the slag crushing function, the stirring function and the conveying function of the outer pipe. The invention also belongs to the protection scope of the invention when the similar double-wall drill rod is matched with an extraction type high-low pressure conversion valve, a sieve pore air inlet device and the like.

Furthermore, the end part of the outer pipe is changed into a thick-wall circular outer pipe by an extrusion forming method or a friction welding joint method, male and female buttons are arranged at two ends of the thick-wall circular outer pipe, adjacent outer pipes are connected by adopting screw threads with seals, and adjacent inner pipes are connected by adopting lap joint seals or plug-in seal.

Further, the extraction type high-low pressure conversion valve comprises an outer valve pipe, an inner valve pipe and a high-low pressure conversion assembly, wherein the outer valve pipe and the inner valve pipe are coaxially installed in a matched mode, and the high-low pressure conversion assembly is installed in a flow supply channel formed between the outer valve pipe and the inner valve pipe;

the central hole of the valve inner pipe is a gas extraction channel; the two ends of the valve outer pipe are respectively provided with a male buckle and a female buckle, the female buckle of the valve outer pipe is connected with the male buckle of the extraction type drill rod, the male buckle of the valve outer pipe is connected with the female buckle of the sieve pore air inlet device, one end of the valve inner pipe is in sealed connection with the inner pipe of the extraction type drill rod, the other end of the valve inner pipe is in sealed connection with the convex rib-shaped inner pipe of the sieve pore air inlet device, and one end of the valve inner pipe is provided with a sealing element.

Furthermore, two to four axial convex ribs or spiral convex ribs with two ends gradually changed into inclined planes are arranged on the outer surface of the valve outer tube, and a cutting blade is arranged on the side surface of each inclined plane; two axial convex ribs or two spiral convex ribs of the valve outer pipe are provided with radial water jet nozzles or inclined water jet nozzles; the valve outer pipe is characterized in that the axial convex rib or the spiral convex rib of the valve outer pipe is provided with a discontinuous spiral groove, and the discontinuous spiral groove enables the valve outer pipe to have slag crushing, stirring and conveying functions.

Furthermore, the jet nozzle of the extraction type high-low pressure conversion valve can be replaced, hydraulic slotting on medium-hard coal can be realized when a nozzle with a small drift diameter is adopted, and hydraulic punching on a soft coal layer can be realized when a nozzle with a large drift diameter is adopted. The three-station high-low pressure conversion assembly is designed into a four-station high-low pressure conversion assembly, namely a locking station, a low-pressure drilling station, a medium-pressure punching station and a high-pressure slotting station, and is also within the protection scope of the invention, but the switching accuracy of the punching station and the slotting station is reduced due to the influence of medium pressure in a hole outside the outer pipe of the valve, the selection difficulty of the spring is increased, and the reliability is reduced. If the extraction type high-low pressure conversion valve is designed into four stations, the invention is also in the protection scope.

Further, the high-low pressure conversion assembly comprises a sliding valve core, a spring, a front support, a rear support and a fixing pin; a sliding valve core is arranged between the front support and the rear support, a spring is sleeved between the sliding valve core and the valve inner pipe, and the front support and the rear support are both connected with the valve outer pipe through fixing pins; when the valve works, two ends of the spring are in contact fit with the sliding valve core and the rear support.

Further, the slide valve core has three working positions: firstly, a drill stopping locking station prevents water and coal cinder in a hole from flowing back to a flow supply channel of an extraction type drill rod when drill rods are assembled and disassembled and the like are stopped; secondly, a low-pressure drilling station, wherein low-pressure fluid is completely supplied to the open-close type drill bit; and thirdly, a water jet slotting or punching station, high-pressure fluid is supplied to the jet flow nozzle, and a small amount of fluid is supplied to the open-close type drill bit in a leakage mode or a micropore leakage mode so as to reduce the temperature of the drill bit. The mode of supplying a small amount of water flow to the open-close type drill bit under the high pressure state is various, and a common engineer can slightly change the slide valve core and the support position according to the requirement, thereby being in the protection scope of the invention.

Further, the sieve pore air inlet device comprises a convex rib-shaped outer pipe, a convex rib-shaped inner pipe and an air inlet sieve pore plate, wherein the convex rib-shaped outer pipe and the convex rib-shaped inner pipe are coaxially installed in a matched mode, preferably, the convex rib-shaped inner pipe is embedded into the convex rib-shaped outer pipe, the convex rib-shaped inner pipe and the convex rib-shaped outer pipe are integrated by adopting a method of combining dipping sealing and a fixed pin, a space between the convex rib-shaped outer pipe and the convex rib-shaped inner pipe is a flow supply channel, and an inner hole of the convex rib-shaped inner pipe is a gas extraction channel; a male buckle and a female buckle are respectively arranged at two ends of the convex rib-shaped outer pipe, and a sealing element is arranged at one end of the convex rib-shaped inner pipe;

the convex ribs of the convex rib-shaped outer pipe and the convex rib-shaped inner pipe are axial convex ribs or spiral convex ribs, and the number of the convex ribs of the convex rib-shaped outer pipe and the convex rib-shaped inner pipe is two or three or four; the radial air inlet through holes penetrating through the inner convex ribs and the outer convex ribs are formed in the convex ribs of the convex rib-shaped outer pipe and the convex ribs of the convex rib-shaped inner pipe, and the air inlet sieve plate is welded on the convex ribs of the convex rib-shaped outer pipe and covers the radial air inlet through holes.

Furthermore, the air inlet sieve plate is provided with inverted cone-shaped sieve pores, the diameter of an air inlet of each sieve pore is one half to one fifth of the diameter of the radial air inlet through hole, and the sum of the areas of the air inlets of all the sieve pores is larger than the cross section area of the inner hole of the rib-shaped inner pipe.

Furthermore, the convex ribs on the convex rib-shaped outer pipe are eliminated, or the convex rib-shaped outer pipe is changed into the groove-shaped outer pipe, and the radial through holes are arranged in the grooves of the groove-shaped outer pipe, so that the change not only can further increase the coal cinder quantity in the gas extraction channel, but also can increase the water inflow in the gas extraction channel, the gas inlet function is weakened, and the gas inlet function is still realized, and the change is also in the protection scope of the invention.

Further, the open-close type drill comprises a drill body, a short section inner pipe and an open cover; a short section inner pipe is coaxially arranged in the drill bit body; one end of the drill bit body is provided with a female buckle matched with the convex rib-shaped outer pipe; the outer edge of the other end of the drill bit body is provided with end teeth, and the center of the other end of the drill bit body is provided with an opening cover for covering the inner pipe of the short section; two pairs of pin holes are formed in the opening cover, a high-strength pin shaft is installed in one pair of pin holes, and a low-strength shearing pin is installed in the other pair of pin holes. In the practical implementation process, the opening mode of the opening cap is various, general mechanical engineers can selectively design according to the double-channel structure and the geometric space of the opening and closing type drill bit with the short section inner pipe, such as a shear pin type opening cap, a self-locking wedge type opening cap, a hinged hinge type opening cap and the like, and the changes are also in the protection scope of the invention if the changes are matched with the components of the invention.

Further, take out the formula water swivel and draw out including the hollow water swivel ectosome, take out and adopt pipe, manometer, take out and adopt switch and water supply port, hollow water swivel ectosome inner chamber cavity is installed hollow water swivel inner tube, the hole of hollow water swivel inner tube is the gas and takes out the passageway, the outer pipe of hollow water swivel ectosome one end and the formula of taking out drilling rod passes through the screw thread and is connected, the other end of hollow water swivel ectosome is installed and is connected the taking out pipe of hollow water swivel inner tube, the other end of hollow water swivel inner tube passes through the screw thread with the inner tube of taking out the formula drilling rod and be connected, take out installation pressure table and taking out and draw out the switch on the pipe, the manometer shows the gas pressure of drilling tool inner chamber and the gas pressure in "loose hole gas bag" during the gas is taken out and is drawn out along with the drill hole. The gas pressure in the 'loose hole gas bag' can be known by closing the switch, and the slotting or punching operation method is adjusted according to the gas pressure in the inner cavity of the drilling tool and the gas pressure in the 'loose hole gas bag', and necessary auxiliary spray control measures are taken.

Further, other combination modes of the cross-layer drilling extraction type drilling tool are explained as follows: the sieve pore air inlet device and the open-close type drill bit can be designed and processed into a whole, the extraction type high-low pressure change-over valve and the sieve pore air inlet device can be processed into a whole, the hole blowout prevention function of the extraction type drilling tool and the function of lowering the hole protection sieve pipe before the drill is lifted can be realized, and the invention also belongs to the protection scope of the invention.

Further, a hole spraying prevention function of the cross-layer drilling extraction type drilling tool is realized, a hole opening is matched with a controlled spraying type drainage box, and the controlled spraying type drainage box comprises a hole packer, a drainage box, a gas drainage tube, a water-coal-slag drainage tube, a dustproof brush and a controlled spraying insertion plate arranged in the drainage box; during installation, the controlled spraying type drainage box is installed at the orifice through the hole packer;

a hole packer is arranged at one end of the drainage box, a dustproof brush is arranged inside the other end of the drainage box, a gas drainage tube is arranged at the upper part of the drainage box, and a water coal cinder drainage tube is arranged at the lower part of the drainage box; two symmetrical injection control inserting plates are arranged at one end of the hole packer in the drainage box, the sectional area of a slag inlet channel in the drainage box is controlled by moving the inserting plates, and forced injection prevention and injection control are implemented when coal and gas outburst occurs at a coal hole section. When the drainage box works, the position of the inserting plate is manually moved, and the sectional area of a slag discharging channel in the drainage box is reduced. The spray control inserting plate is provided with a plurality of round holes, and the diameter of each round hole is equivalent to the annular gap width of a slag discharge channel in the drainage box.

Further, when the inclination angle of the drill hole is small, the sieve pore air inlet device is easily submerged by water coal slag to influence the radial air inlet function, an extraction type drill rod can be additionally arranged between the extraction type high-low pressure conversion valve and the sieve pore air inlet device, the height difference between the sieve pore air inlet device and the extraction type high-low pressure conversion valve is increased, and the phenomenon that the sieve pore air inlet device is submerged by water to weaken the air inlet function is avoided.

Further, when drilling is conducted on the extremely soft protruding coal seam which is difficult to form holes, the extraction type high-low pressure conversion valve is removed, 2-4 oblique water jet nozzles for punching are installed on the opening-closing type drill bit portion, an included angle of about 45 degrees is formed between the outlet direction of each water jet nozzle and the drilling direction, and drilling and punching are conducted on the coal hole section synchronously. Although the gas extraction while drilling method can cause the gas extraction channel to have a small amount of water, when the drilling speed is slow, the sieve mesh air inlet device can be in a suspended state in the punched hole, and the water inflow in the gas extraction channel can be controlled through the punching progress.

Further, when a medium-hard outburst coal seam which is easy to form holes is drilled, the sieve pore air inlet device is removed, slotting or punching and gas extraction while drilling are not carried out during the drilling period of the coal pore section, the coal pore section is conventionally drilled, the hole protection sieve tube is placed after a drill bit enters a top plate of the coal seam, slotting or punching and gas extraction while drilling are carried out during the drill withdrawal period, and gas extraction while drilling is carried out during the drill withdrawal slotting or punching period by utilizing the hole protection sieve tube. The simplified processing method is suitable for medium-hard coal beds in non-outburst areas of outburst coal beds, if coal and gas in holes are outburst in the process of back-drilling and slotting or punching, the hole-protecting sieve tube can be damaged, and after the hole-protecting sieve tube is damaged, gas extraction while drilling is difficult to implement.

Further, the method for extracting gas while drilling by using the blowout prevention hole of the cross-layer drilling extraction type drilling tool can be a method for extracting gas while drilling by adopting forward slotting and punching, and can also be a method for extracting gas while drilling by adopting backward slotting and punching, wherein the method for extracting gas while drilling by adopting forward slotting and punching is taken as an example, and the method for extracting gas while drilling by using prevention and control jetting is explained. When the advancing type slotting and punching are carried out, the method comprises the following steps:

first, preparation work

And (3) reaming the hole, installing a spray-control drainage box at the hole opening, removing the extraction pipe on the extraction type water braid, connecting the extraction pipe with the existing slag discharge water drainage device through a telescopic hose, and connecting the slag discharge water drainage device with an extraction pipe network.

Because no gas is generated during the drilling of the rock hole section, gas extraction while drilling is not needed, and the removal of an extraction pipe (containing a pressure gauge) at the tail part of the extraction type water swivel can reduce the labor intensity of workers for loading and unloading the water swivel. And a special light extraction type water swivel for the rock hole section can be designed, and the extraction type water swivel can be processed more conveniently because the rock hole section does not need high-pressure water.

Second, drilling in the rock hole section

And (3) the drilling of the rock hole section is not carried out while drilling gas extraction, similar to the existing drilling, static pressure water of about 3MPa is supplied to an extraction type water swivel, and the drilling of the rock hole section is carried out. The pressure of the static pressure water in a 300m deep mine is about 3Mpa, the actual use pressure is controlled through flow, and the power consumption of a pump station can be saved by adopting the static pressure water.

Thirdly, preparation work before slotting and punching

Once the drill hole enters the coal seam, the extraction pipe is installed at the tail part of the extraction type water braid, a high-pressure pump station used for slotting and punching is started, and the high-pressure pump station is connected with a related pipeline of the controlled spray type drainage box.

Fourthly, the blowout-preventing hole is extracted while drilling gas

The advancing type slotting and punching process is similar to the existing advancing type slotting and punching process, a cross-layer drilling and extracting type drilling tool serves as an extraction pipe which rotates and moves along with drilling, a sieve mesh air inlet device serves as a sieve mesh pipe which rotates and moves along with drilling, gas in a loose-hole gas bag formed by slotting and punching is extracted along with drilling, during the gas extraction along with drilling, a driller observes a pressure gauge on an extraction type water swivel, the pressure gauge displays the gas pressure in an inner cavity of the drilling tool during the gas extraction along with drilling, and three conditions can occur during the advancing type slotting and punching along with drilling during the gas extraction along with drilling:

case I: under the normal condition, normal water jet slotting or punching operation and drill rod installation are carried out under the condition that the gas pressure of the inner cavity of the cross-layer drilling extraction type drilling tool is under the negative pressure condition, and gas extraction while drilling is carried out on the gas of the hole loosening gas bag. Other outward manifestations of the normal case are: the slag discharge condition of the controlled spraying type drainage box is normal, the water coal slag is normally discharged, a small amount of gas is discharged, if the controlled spraying type drainage box is found to have air entering a drill hole, the extraction transition is indicated, and a switch on an extraction type water braid can be properly closed.

Case II: when the gas pressure in the inner cavity of the cross-layer drilling extraction type drilling tool is in a positive pressure or higher pressure condition, reducing the flow supply flow rate of the cross-layer drilling extraction type drilling tool, reducing the rotation speed of the cross-layer drilling extraction type drilling tool, stopping the front and back movement of the cross-layer drilling extraction type drilling tool, suspending the installation of a drill rod, and when the gas pressure in the inner cavity of the cross-layer drilling extraction type drilling tool is reduced to a negative pressure or normal pressure, then performing normal slotting or punching operation and drill rod installation, and performing gas extraction while drilling on the gas of a 'loose hole gas bag'; other extrinsic manifestations of an abnormal situation are: the controlled spraying type drainage box has intermittent impact sound, and has the defects of intermittent blockage of a drill hole and abnormal discharge of water coal slag.

Case iii: the coal and gas in the hole are protruded, when the power phenomena such as the coal and gas in the hole are protruded, the gas pressure in the inner cavity of the cross-layer drilling extraction type drilling tool can be sharply increased to be positive pressure, and the control injection operation adopted under the condition is as follows: 1. reducing the flow supply rate of the cross-layer drilling extraction type drilling tool, reducing the rotation speed of the cross-layer drilling extraction type drilling tool, and strictly prohibiting the back-and-forth movement of the cross-layer drilling extraction type drilling tool; 2. the opening degree of a switch of an extraction pipe of the extraction type water braid is properly controlled, so that the gas is prevented from exceeding the limit due to the fact that a telescopic hose and a slag discharge water discharger are damaged by flushing; 3. the position of the control spraying inserting plate in the movable control spraying type drainage box prevents the gas from exceeding the limit due to the orifice spraying holes. By adopting the measures, when the gas pressure in the inner cavity of the cross-layer drilling extraction type drilling tool is reduced to negative pressure or normal pressure, normal slotting or punching operation and drill rod installation are resumed, and gas extraction while drilling is carried out on the gas of the hole-loosening gas bag;

fifthly, lowering the hole-protecting sieve tube before withdrawing the drill

When the slotting and punching operation advances to the coal seam roof or a drill bit enters the coal seam roof, removing an extraction pipe and a pressure gauge at the tail part of the extraction type water swivel, lowering a hole protection sieve pipe before performing bit withdrawal, and placing the hole protection sieve pipe with barbs into the top of a coal hole section through an inner hole of the extraction type water swivel, an extraction type drill rod inner pipe, a valve inner pipe, a convex rib-shaped inner pipe, a short section inner pipe of an opening and closing type drill bit and an opening cover; and after the hole-protecting sieve tube is lowered, the extraction pipe and the pressure gauge of the extraction type water braid are installed again, and the gas extraction while drilling is started after the drill is withdrawn.

Sixthly, withdrawing the drill while drilling gas extraction

In the process of withdrawing the drill, normal extraction of the extraction type water swivel is kept, repeated operation of withdrawing slotting or punching is carried out according to needs, the gas extraction while drilling is carried out by replacing the air inlet function of a sieve mesh air inlet device with an inserted hole protecting sieve tube, gas extraction while drilling is carried out on gas at the top of a 'loose hole gas bag', the gas pressure in the inner cavity of the cross-layer drilling extraction type drilling tool is kept in a negative pressure or normal pressure state, and spray holes in the process of withdrawing the drill are avoided.

Other description of gas extraction while drilling method:

aiming at the extraction type drilling tool, the gas extraction method while drilling adopting forward slotting and punching belongs to an optimal gas extraction method while drilling, and in addition, a backward slotting and punching gas extraction while drilling method is adopted, the backward slotting and punching gas extraction while drilling method adopts wind power to drill in a coal hole section, a hole protection sieve pipe is placed in a coal hole after the drilling reaches a coal seam top plate, and the gas extraction while drilling of slotting and punching is carried out in the process of withdrawing the drilling, and the method has the following risks: in the process of retreating, cutting and punching, once coal and gas outburst occurs in the holes, the guard hole sieve holes are possibly damaged, and due to the fact that the guard hole sieve tubes exist in the sieve hole air inlet device, the guard hole sieve tubes and the sieve hole air inlet device can fail in a double-failure mode, and difficulty is brought to subsequent gas extraction while drilling in cutting and punching. Therefore, the retreating type slotting and punching gas extraction method while drilling is only suitable for medium-hard coal seams in non-outburst areas of outburst coal seams.

The invention has the following beneficial effects:

1. the existing blowout-preventing hole technology does not relate to the improvement of a drilling tool, only solves the problem through a hole opening blowout-preventing device, and cannot eliminate a gas power source inducing the hole opening. The invention indicates that a gas power source for inducing the spray holes is positioned in a 'loose hole gas bag' formed by slotting or punching a coal hole section, and provides an extraction type drilling tool and a blowout prevention hole while drilling gas extraction method.

2. The extraction type drilling tool is formed by connecting a plurality of extraction type drill rods, extraction type high-low pressure conversion valves, sieve pore air inlet devices, open-close type drill bits and extraction type water braids, and is generally characterized in that: the extraction type drilling tool is used as an extraction pipe which rotates and moves while drilling, wherein the sieve pore gas inlet device is used as a sieve pore pipe which rotates and moves while drilling, and gas extraction while drilling is carried out on gas in a loose hole gas bag formed by slotting and punching; the gas extraction channel of the gas extraction type drilling tool is arranged in the 'loose-hole gas bag', and the water coal slag in the 'loose-hole gas bag' is arranged in the slag discharge channel between the outer surface of the drilling tool and the wall of the drilled hole, so that the water coal slag and the gas are extracted and discharged in the hole in a separated way, and the problem that the gas of the spraying holes of the cross-drilled hole is over-limited can be solved from the source.

3. The existing hole external blowout prevention device collects extracted gas at a hole opening, the concentration of the extracted gas is extremely low, the low concentration gas enters a gas extraction pipe network and then greatly affects the concentration of the gas in the pipe network, and the negative interference on the utilization of the gas in a coal mine is serious. The gas extracted by the extraction type drilling tool is pure gas which is not mixed with air at the top part in a hole-drilling hole gas bag, and has positive beneficial effect on the utilization of the gas in the coal mine.

4. In order to avoid the gas overrun accident of the cross-layer drilling and orifice spraying of the outburst mine, a plurality of mines adopt passive measures of firstly drilling, then extracting and then slotting and punching, so that the engineering efficiency is greatly reduced, the engineering cost is greatly improved, and meanwhile, the opportunity of breaking coal by utilizing the natural power (coal and gas outburst in holes) of the outburst coal layer is lost. By using the extraction type drilling tool, slotting, punching and blowout prevention hole drilling gas extraction are carried out on the coal hole section, so that the gas extraction treatment efficiency of the cross-layer drilling hole can be improved, and the gas extraction treatment cost of the cross-layer drilling hole can be reduced.

5. The gas overrun accidents of the jet holes of the cross-layer drill holes of the outburst coal seam account for 30% -80% of the total number of the gas overrun accidents of the outburst coal seam and become main potential safety hazards of the outburst coal seam, and the cross-layer drill hole extraction type drilling tool and the blowout prevention hole while drilling gas extraction method have important significance for coal mine safety production.

Drawings

FIG. 1 is a general scheme diagram of an extraction type drilling tool and field construction thereof;

FIG. 2 shows the outer surface and the structure of a local groove-pressing type extraction drill rod;

FIG. 3 is a diagram of a welded cambered surface supporting block type extraction drill rod structure;

FIG. 4 is a view of the appearance and structure of the special-shaped pipe type extraction drill pipe;

FIG. 5 shows the external surface and structure of the extraction drill rod with the support;

FIG. 6 is a sealing connection diagram between extraction drill rods;

FIG. 7 is a perspective view of a part of an extraction type high-low pressure change-over valve;

FIG. 8 is an explanatory diagram of a station of a drainage type high-low pressure change-over valve;

fig. 9 is a structural explanatory view of the sieve pore air inlet device;

FIG. 10 is a view of open-close drill bit parts;

FIG. 11 is a drawing of an extraction type drilling tool for small inclination angle cross-layer drilling;

FIG. 12 is a drawing of an extraction type drilling tool for cross-seam drilling of a very soft outburst coal seam;

FIG. 13 is a drawing of an extraction type drilling tool for cross-seam drilling of a hard outburst coal seam;

FIG. 14 is a drawing of a drainage pigtail structure;

fig. 15 is an explanatory view of the structure of the controlled spray type drainage box.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As shown in fig. 1, the overall scheme diagram of the cross-layer drilling extraction type drilling tool is shown, and the cross-layer drilling extraction type drilling tool comprises an extraction type water swivel 5, a plurality of extraction type drill rods 1, an extraction type high-low pressure conversion valve 2, a sieve pore air inlet device 3 and an open-close type drill bit 4 which are connected in sequence; in order to better realize the hole blowout prevention function of the drilling tool, the traditional orifice drainage box is improved, and a controlled spraying type drainage box 6 which is matched with the extraction type drill rod 1 is arranged at the orifice. A gas extraction channel is constructed in the center of an inner cavity of a cross-layer drilling extraction type drilling tool, a flow supply channel of the drilling tool is constructed between an outer pipe and an inner pipe of an extraction type drilling rod of the cross-layer drilling extraction type drilling tool, a gas extraction channel is constructed for gas in a hole loosening gas bag, a slag discharge channel is constructed for water coal slag in the hole loosening gas bag, a gas power source inducing jet holes is timely eliminated by extracting gas in the hole loosening gas bag while drilling, and the gas extraction channel is used as a channel for discharging a protective hole screen pipe when the drilling is withdrawn.

As shown in fig. 2, the extraction drill rod 1 further includes an outer pipe 11 and an inner pipe 12 which are coaxially disposed, the outer pipe 11 forms two sets of local arc protrusions 111 in an inner hole of the outer pipe in a local hot extrusion manner, the local arc protrusions 111 in the inner hole of the outer pipe are matched with an outer circle of the inner pipe and support the inner pipe 12, so that the outer pipe 11 and the inner pipe 12 are kept coaxial, each set of the local arc protrusions 111 is two or three, the outer pipe 11 can be spiral groove-shaped (as shown in fig. 2 a-2 b) and spiral rib-shaped (as shown in fig. 2 c), and the drill rod can also be three (four) rib-shaped or three (four) rib-carved groove-shaped, so as to increase the slag crushing, stirring and conveying capabilities of the drill rod. The axial space between the outer pipe 11 and the inner pipe 12 of the extraction type drill rod 1 is a flow supply channel 14 of the drilling tool, the central hole of the inner pipe of the extraction type drill rod is a gas extraction channel 15, and the annular space between the outer pipe and the wall of a drilled hole is a slag discharge channel.

As shown in fig. 3, the extraction drill rod 1 further includes an outer pipe 11, an inner pipe 12 and two or three cambered surface support blocks 13 welded on the inner wall of the outer pipe 11, each group of support blocks 13 is uniformly distributed along the circumference of the inner hole of the outer pipe, a support block welding hole 131 is formed in each support block 13, an outer pipe welding hole 112 is formed in the outer pipe 11, the radius of the outer cambered surface of each support block 13 is equal to the radius of the inner hole of the outer pipe 11, and the radius of the inner cambered surface of each support block 13 is equal to the radius of the outer circle of the inner pipe 12. The support block 13 is welded to the inner wall of the outer pipe 11 by the outer pipe welding hole 112 of the outer pipe 11, and the support block 13 is welded to the outer circumference of the inner pipe 12 by the support block welding hole 131. The outer shape of the outer pipe 11 is spiral groove shape or spiral rib shape or triangular shape or quadrangular shape or triangular groove shape or quadrangular groove shape, so that the slag crushing, stirring and conveying capacity of the drill rod is improved;

as shown in fig. 4, the extraction drill rod 1 further comprises an outer special-shaped pipe 11 and an inner pipe 12, wherein an axial groove 113 is formed in the outer surface of the outer special-shaped pipe 11, an axial arc protrusion 114 corresponding to the axial groove is formed in an inner hole of the outer special-shaped pipe, the axial arc protrusion 114 of the inner hole of the outer special-shaped pipe is matched with the outer circle of the inner pipe and supports the inner pipe 12, the outer pipe 11 and the inner pipe 12 are kept coaxial, the number of the axial grooves 113 and the number of the axial arc protrusions 114 are 2 or 3, and a spiral groove or a spiral rib is formed in the arc surface of the outer pipe, so that the slag crushing, stirring and conveying capacity of the drill rod is improved.

As shown in fig. 4c, the extraction drill rod 1 includes an outer pipe 11 and an inner pipe 12 which are coaxially arranged, the outer pipe 11 is a hot-twisted special-shaped outer pipe 11 formed by a hot-twisted method in a constrained state, a large spiral groove 115 is formed on the outer surface of the hot-twisted special-shaped outer pipe 11, a large-pitch arc protrusion corresponding to the large spiral groove 115 is formed in an inner hole of the hot-twisted special-shaped outer pipe 11, the large-pitch arc protrusion of the inner hole of the hot-twisted special-shaped outer pipe 115 is matched with an outer circle of the inner pipe 12, the inner pipe 12 is supported to enable the outer pipe 11 and the inner pipe 12 to be coaxial, the outer pipe 11 and the inner pipe 12 are enabled to be coaxial, and two or three large-pitch arc protrusions are formed on the large-pitch arc protrusion 115; the axial space between the outer pipe 11 and the inner pipe 12 is a flow supply channel 14 of an extraction type drilling tool, the central hole of the inner pipe 12 is a gas extraction channel, and an annular gap between the outer pipe 11 and the wall of a drilled hole is a slag discharge channel.

As shown in fig. 5, the extraction drill rod 1 includes an outer pipe 11, an inner pipe 12, and a support 16, the support 16 being installed between the outer pipe 11 and the inner pipe 12, the support keeping the outer pipe 11 and the inner pipe 12 coaxial. The outer shape of the outer tube 11 can be spiral ribs (as shown in fig. 5 a), spiral grooves (as shown in fig. 5 b), prisms (as shown in fig. 5 c) or prism-engraved grooves (as shown in fig. 5 d), and the number of the grooves and the number of the ribs are two or more; the grooves can be rectangular grooves, trapezoidal grooves, cambered surface grooves and rifling-shaped grooves; the convex rib can be welded, lathed and clad, the convex rib surface can be a plane convex rib and a cambered convex rib, the shape of the convex rib is not limited, and the width of the convex rib is equal to or greater than the height of the convex rib. The outer surface of the outer pipe 11 is provided with grooves, convex ribs, arc edges and the like, and the functions of slag crushing, stirring and conveying of the outer pipe are enhanced. The invention also discloses a method for controlling the gas content of the soft stratum by using the gas extraction type high-low pressure conversion valve 2 and the sieve pore gas inlet device 3.

As shown in fig. 6, for several extraction drill rods 1 described in fig. 2 to 5, the end portions of the outer pipes 11 of different shapes of the extraction drill rods 1 are changed into thick-wall circular outer pipes by an extrusion forming method or a friction welding joint method, male and female threads are arranged at two ends of each thick-wall circular outer pipe, the adjacent outer pipes 11 are connected by using threaded threads with seals, and the adjacent inner pipes 12 are connected by using lap seals (fig. 6 a) or plug seals (fig. 6 b). In order to reduce the influence of the plug seal or lap seal on the flow supply channel 14, one end of the inner tube 12 extends out of the male buckle, so that the plug seal or lap seal is located in the outer tube 11 with a larger inner bore diameter.

As shown in fig. 7, the extraction type high-low pressure conversion valve 2 is provided, and the extraction type high-low pressure conversion valve 2 comprises an outer valve tube 21, an inner valve tube 22 and a high-low pressure conversion assembly; the central hole of the valve inner pipe 22 is a gas extraction channel, the two ends of the valve outer pipe 21 are respectively provided with a male buckle and a female buckle, the female buckle of the valve outer pipe 21 is connected with the male buckle of the extraction type drill rod 1, the male buckle of the valve outer pipe 21 is connected with the female buckle of the sieve pore air inlet device 3, one end of the valve inner pipe 22 is in sealing connection with the inner pipe 12 of the extraction type drill rod 1, the other end of the valve inner pipe 22 is in sealing connection with the convex rib-shaped inner pipe 32 of the sieve pore air inlet device 3, and a sealing part is arranged at one end of the valve inner pipe 22.

As shown in fig. 7, the valve outer tube 21 is provided with two, three or four axial ribs or spiral ribs 211, the two ends of which are gradually changed into inclined planes 212, and the side surfaces of the inclined planes 212 are provided with cutting blades 213; two radial or oblique water jet nozzles 214 are arranged on two convex ribs of the valve outer pipe 21; the ribs of the outer valve pipe are provided with discontinuous spiral grooves 215, so that the outer valve pipe 21 has slag crushing and conveying functions. The purpose of arranging the convex ribs on the valve outer tube 21 is mainly as follows: firstly, provide with many spaces for the row's of drilling tool sediment, secondly provide bigger radial dimension for the installation of nozzle, thirdly let valve outer tube 21 have the stirring function. If the wall thickness of the valve outer tube 21 is increased, the exterior of the valve outer tube 21 is not provided with a convex rib, and the exterior shape of the valve body is designed to be polygonal or circular, and the like, which also belongs to the protection scope of the invention.

As shown in fig. 7, the high and low pressure switching assembly, which includes a spool 231, a spring 232, a front support 233, a rear support 234, and a fixing pin 235, is installed in the annular supply passage 24 between the valve outer tube 21 and the valve inner tube 22; a sliding valve core 231 is arranged between the front support 233 and the rear support 234, a spring 232 is sleeved between the sliding valve core 231 and the valve inner tube 22, and the front support 233 and the rear support 234 are both connected with the valve outer tube 21 through fixing pins; in operation, the ends of the spring 232 engage the spool 231 and the rear support 234.

As shown in fig. 8, the sliding valve core 231 has three working positions, the first drawing in the first row in fig. 8 shows a drill stopping locking station, and when a drill rod is loaded and unloaded and the like stops drilling, water, coal slag in a hole are prevented from flowing backwards to a flow supply channel of the extraction type drill rod; the second diagram in the first row of fig. 8 shows a low pressure drilling station, with low pressure fluid all supplied to the open-close drill bit 4; the third diagram in the first row of fig. 8 shows a water jet slitting or punching station, where high pressure fluid is supplied to the jet nozzle 214 and a small amount of fluid is supplied to the open-close type drill 4 in a leakage manner or a micropore leakage manner for cooling the drill. The method for supplying a small amount of water flow to the drill bit under the high-pressure state is various, and common engineers can slightly change the slide valve core and the support position according to the requirements, and the method is also within the protection scope of the invention.

In the implementation process of the invention, the jet nozzle 214 of the extraction type high-low pressure conversion valve 2 can be replaced, hydraulic slotting on medium-hard coal can be realized when a small-drift-diameter nozzle is adopted, and hydraulic punching on a soft coal layer can be realized when a large-drift-diameter nozzle is adopted. Two groups of nozzles 214, one group of two radial slotting nozzles and one group of two radial or oblique punching nozzles, can be arranged on the convex rib 211 of the valve body, and the three-station high-low pressure conversion assembly is designed into a four-station high-low pressure conversion assembly, namely a locking station, a low-pressure drilling station, a medium-pressure punching station and a high-pressure slotting station, which is also within the protection scope of the invention, but is influenced by the pressure of a medium in a hole outside the valve outer tube 21, so that the switching accuracy between the punching station and the slotting station is reduced, the selection difficulty of a spring is increased, and the reliability is reduced. If the extraction type high-low pressure conversion valve 2 is designed into four stations, the invention is also within the protection scope.

Fig. 9 is a structural view of the sieve pore air inlet device 3, wherein the sieve pore air inlet device 1 comprises a convex rib-shaped outer pipe 31, a convex rib-shaped inner pipe 32 and an air inlet sieve plate 33; the male buckle and the female buckle are respectively arranged at two ends of the convex rib-shaped outer pipe 31, the female buckle is connected with the extraction type high-low pressure conversion valve 2, and the male buckle is connected with the open-close type drill bit 4; a sealing piece is installed at one end of the convex rib-shaped inner pipe 32, a central hole of the convex rib-shaped inner pipe 32 is a gas extraction channel, the convex rib-shaped inner pipe 32 is embedded into the convex rib-shaped outer pipe 31, the convex rib-shaped inner pipe 32 and the convex rib-shaped outer pipe 31 are integrated by adopting a method of combining dipping sealing and a fixing pin, and a space between the convex rib-shaped outer pipe 31 and the convex rib-shaped inner pipe 32 is a flow supply channel 14. The outer tube convex ribs 311 and the inner tube convex ribs 321 can be axial convex ribs or spiral convex ribs, the number of the convex ribs is two or three or four, and the convex ribs are provided with radial air inlet through holes 312 penetrating through the outer convex ribs and radial air inlet through holes 322 penetrating through the inner convex ribs; the air inlet sieve plate 33 is welded on the convex rib 311 of the convex rib-shaped outer pipe 31 and covers the radial air inlet through hole 312; the screen holes 331 of the air inlet screen hole plate 33 are conical holes, the diameter of an air inlet of each conical hole 331 is far smaller than the diameter of the radial air inlet through hole 312 of the outer convex rib and the diameter of the radial air inlet through hole 322 of the inner convex rib, and the sum of the areas of the air inlets of all the conical holes 331 is larger than the inner hole sectional area of the convex rib-shaped inner pipe 32.

Furthermore, the convex ribs 311 on the convex rib-shaped outer pipe 31 are eliminated, even the convex rib-shaped outer pipe 31 is changed into a groove-shaped outer pipe, and the radial air inlet through holes 312 are arranged in the grooves of the groove-shaped outer pipe, so that the change not only can further increase the coal cinder quantity in the gas extraction channel, but also can increase the water inflow in the gas extraction channel, the air inlet function is weakened, but the air inlet function is still realized, and the change is also in the protection scope of the invention.

As shown in fig. 10, the open-close type drill 4 includes a drill body 41, a short section inner tube 42, and an opening cap 43; a short section inner pipe 42 is coaxially arranged in the drill bit body 41; one end of the drill bit body 41 is provided with a female buckle matched with the convex rib-shaped outer pipe 31; the outer edge of the other end of the drill bit body 41 is provided with end teeth, and the center of the other end of the drill bit body 41 is provided with an opening cover 43 for covering the short section inner pipe 42; two pairs of pin holes are formed in the opening cover 43, a high-strength pin shaft is installed in one pair of pin holes, and a low-strength shearing pin is installed in the other pair of pin holes. In practice, there are various opening methods of the opening cap 43, and general mechanical engineers can selectively design the opening cap according to the double-channel structure and geometric space of the openable drill 4 with the pup joint inner tube 42, such as the shear pin type opening cap 43, the self-locking wedge type opening cap 43, and the hinged hinge type opening cap 43.

As shown in fig. 11, the extraction type drilling tool formed by connecting a plurality of extraction type drill rods 1, an extraction type high-low pressure conversion valve 2, a sieve pore air inlet device 3, an open-close type drill bit 4 and an extraction type water swivel 5 is used, when the inclination angle of a drill hole is small, the sieve pore air inlet device 3 is easily submerged by water coal slag to influence the radial air inlet function, therefore, an extraction type drill rod 7 with a certain length can be additionally arranged between the high-low pressure conversion valve 2 and the sieve pore air inlet device 3, the purpose is to increase the height difference between the sieve pore air inlet device 3 and the extraction type high-low pressure conversion valve 2, and the sieve pore air inlet device 3 is prevented from being submerged by water.

As shown in fig. 12, the extraction type drilling tool formed by connecting a plurality of extraction type drill rods 1, an extraction type high-low pressure conversion valve 2, a sieve pore air inlet device 3, an open-close type drill bit 4 and an extraction type water swivel 5 cancels the extraction type high-low pressure conversion valve 2 for a very soft protruding coal seam difficult to form a hole, 2-4 oblique water jet nozzles 45 for punching are installed at the end part of the open-close type drill bit 4, an included angle of about 45 degrees is formed between the outlet direction of the water jet nozzles 45 and the drilling direction, and the drilling and punching are synchronously performed at a coal hole section. Although the gas extraction while drilling method can cause the gas extraction channel to have a small amount of water, when the drilling speed is slow, the sieve mesh air inlet device 3 can be in a suspended state in the punched hole, and the water inflow in the gas extraction channel can be controlled through the punching progress.

As shown in fig. 13, the extraction type drilling tool is formed by connecting a plurality of extraction type drill rods 1, an extraction type high-low pressure conversion valve 2, a sieve pore air inlet device 3, an open-close type drill bit 4 and an extraction type water braid 5, the sieve pore air inlet device 3 is omitted for a medium-hard outburst coal seam which is easy to form a hole, slotting or punching and gas extraction while drilling are not performed during the drilling period of a coal pore section, conventional drilling is performed on the coal pore section, a hole protection sieve pipe is placed downwards after the drill bit enters a coal seam roof, slotting or punching and gas extraction while drilling are performed during the withdrawal period, and gas extraction while drilling is performed during the withdrawal slotting or punching period by using the hole protection sieve pipe. The simplified processing method is suitable for medium-hard coal beds in non-outburst areas of outburst coal beds, if coal and gas in holes are outburst in the process of back-drilling and slotting or punching, the hole-protecting sieve tube can be damaged, and after the hole-protecting sieve tube is damaged, gas extraction while drilling is difficult to implement.

As shown in fig. 14, the extraction type water swivel 5 includes a hollow water swivel outer body 51, an extraction pipe 52, a pressure gauge 53, an extraction switch 54 and a flow supply port 55, the hollow water swivel inner pipe 56 is installed in the hollow inner cavity of the hollow water swivel outer body 51, an annular flow liquid channel is formed between the hollow water swivel outer body 51 and the hollow water swivel inner pipe 56, the inner hole of the hollow water swivel inner pipe 56 is a gas extraction channel, one end of the hollow water swivel outer body 51 is connected with the outer pipe of the extraction type drill pipe through a screw thread, the extraction pipe 52 connected with the hollow water swivel inner pipe 56 is installed at the other end of the hollow water swivel outer body 51, the other end of the hollow water swivel inner pipe 56 is connected with the inner pipe of the extraction type drill pipe through a screw thread, the flow supply port 55 is formed in the outer side of the hollow water swivel outer body 51, and the flow supply port 55 is communicated with the annular flow liquid channel. And a pressure gauge 53 and an extraction switch 54 are arranged on the extraction pipe 52, and the pressure gauge 53 displays the gas pressure in the inner cavity of the drilling tool and the gas pressure in the hole loosening gas bag during the gas extraction while drilling. The gas pressure in the 'loose hole gas bag' can be known by closing the switch, and the slotting or punching operation method is adjusted according to the gas pressure in the inner cavity of the drilling tool and the gas pressure in the 'loose hole gas bag', and necessary auxiliary spray control measures are taken.

In addition, other combination modes of the extraction type drilling tool need to be explained: for the extraction type drilling tool formed by combining a plurality of extraction type drill rods 1, extraction type high-low pressure conversion valves 2, sieve pore air inlet devices 3, open-close type drill bits 4 and extraction type water braids 5, the sieve pore air inlet devices 3 and the open-close type drill bits 4 can be designed and processed into a whole, the extraction type high-low pressure conversion valves 2 and the sieve pore air inlet devices 3 can be processed into a whole, and the hole blowout preventing function of the extraction type drilling tool and the function of lowering and protecting a hole sieve pipe before lifting the drilling tool can be realized as well, and the protection scope of the invention is also disclosed.

In order to realize the hole blowout prevention function of the cross-layer drilling extraction type drilling tool, a controlled spraying type drainage box 6 is matched with an orifice, wherein the controlled spraying type drainage box 6 comprises a hole packer 61, a drainage box 62, a gas drainage pipe 63, a water-coal cinder drainage pipe 64, a dustproof brush 65 and a controlled spraying insertion plate 66 arranged in the drainage box 62; during installation, the controlled spraying type drainage box 6 is installed at an orifice through a hole packer 61; a hole packer 61 is arranged at one end of the drainage box 62, a dustproof brush 65 is arranged inside the other end of the drainage box 62, a gas drainage pipe 63 is arranged at the upper part of the drainage box 62, and a water coal cinder drainage pipe 64 is arranged at the lower part of the drainage box 62; two symmetrical injection control inserting plates 66 are arranged at one end of the hole packer 61 in the drainage box 62, the sectional area of a slag inlet channel in the drainage box 62 is controlled by moving the positions of the injection control inserting plates 66, and forced blowout prevention and injection control are implemented when coal and gas outburst occurs at a coal hole section. When the automatic slag discharging device works, the position of the injection inserting plate 66 is manually moved, and the sectional area of a slag discharging channel in the drainage box 62 is reduced. The injection control inserting plate 66 is provided with a plurality of round holes, and the diameter of the round holes is equivalent to the annular gap width of the slag discharge channel in the drainage box 62.

The present embodiment is not intended to limit the shape, material, structure, etc. of the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.

In the description of the present invention, it is to be understood that the terms "central", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be considered as limiting the scope of the present invention.

If the terms "first," "second," etc. are used herein to define parts, those skilled in the art will recognize that: the use of "first" and "second" is merely for convenience in describing the invention and to simplify the description, and unless otherwise stated the above words are not intended to have a special meaning.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: it is to be understood that modifications may be made to the technical solutions described in the foregoing embodiments, or equivalents may be substituted for some of the technical features thereof, but such modifications or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. The cross-layer drilling extraction type drilling tool is characterized by comprising an extraction type water swivel, a plurality of extraction type drill rods, an extraction type high-low pressure change-over valve, a sieve pore air inlet device and an open-close type drill bit which are sequentially connected; and a controlled spraying type drainage box which is matched with the cross-layer drilling extraction type drilling tool for installation is arranged at the position of the orifice.

2. The cross-layer drilling extraction type drilling tool according to claim 1, wherein the extraction type drilling rod comprises an outer pipe and an inner pipe which are inserted and matched, the outer pipe protrudes in the inner hole of the outer pipe in a local hot extrusion mode along the length direction to form two groups of local cambered surface protrusions, the local cambered surface protrusions are matched with the excircle of the inner pipe and support and mount the inner pipe to enable the outer pipe and the inner pipe to keep coaxial, the number of the local cambered surface protrusions in each group is two or three, the outer pipe is in a spiral groove shape or a spiral rib shape or a triangular shape or a quadrangular shape or a triangular groove shape or a quadrangular groove shape, and accordingly slag crushing, stirring and conveying capacity of the drilling rod is improved;

the axial space between the outer pipe and the inner pipe is a flow supply channel of the extraction type drilling tool, the central hole of the inner pipe is a gas extraction channel, and the annular space between the outer pipe and the wall of the drilled hole is a slag discharge channel.

3. The cross-layer drilling extraction type drilling tool according to claim 1, wherein the extraction type drilling rod comprises an outer pipe, an inner pipe and two groups of cambered surface supporting blocks welded on the inner wall of the outer pipe, two or three supporting blocks are uniformly distributed along the circumference of an inner hole of the outer pipe in each group, supporting block welding holes welded with the inner pipe are formed in the supporting blocks, outer pipe welding holes welded with the supporting blocks are formed in the outer pipe, the radius of the outer cambered surface of each supporting block is equal to the radius of the inner hole of the outer pipe, and the radius of the inner cambered surface of each supporting block is equal to the radius of the outer circle of the inner pipe; the outer shape of the outer pipe is spiral groove shape or spiral rib shape or triangular shape or quadrangular shape or triangular groove shape or quadrangular groove shape, so that the slag crushing, stirring and conveying capacity of the drill rod is improved;

4. The cross-layer drilling extraction type drilling tool according to claim 1, wherein the extraction type drilling rod comprises an outer pipe and an inner pipe, the outer pipe is a special-shaped outer pipe, an axial groove is formed in the outer surface of the special-shaped outer pipe, an axial arc surface bulge corresponding to the axial groove is formed in an inner hole of the special-shaped outer pipe, the axial arc surface bulge of the inner hole of the special-shaped outer pipe is installed in a matched mode with the outer circle of the inner pipe and supports the inner pipe to enable the outer pipe and the inner pipe to be coaxial, two or three axial grooves and two or three axial arc surface bulges are evenly distributed in the circumferential direction, and spiral grooves or spiral ribs are formed in the outer surface of the outer pipe to improve slag crushing, stirring and conveying capacity of the drilling rod;

5. The cross-layer drilling extraction type drilling tool according to claim 1, wherein the extraction type drilling rod comprises an outer pipe and an inner pipe which are inserted and matched, the outer pipe is a hot-twisted special-shaped outer pipe formed by a hot-twisting method in a constraint state, a large spiral groove is formed in the outer surface of the hot-twisted special-shaped outer pipe, a large-pitch arc protrusion corresponding to the large spiral groove is formed in an inner hole of the hot-twisted special-shaped outer pipe, the large-pitch arc protrusion of the inner hole of the hot-twisted special-shaped outer pipe is matched with an outer circle of the inner pipe and supports the inner pipe to enable the outer pipe and the inner pipe to be coaxial, and the number of the large spiral groove and the large-pitch arc protrusion is two or three;

the axial space between the outer pipe and the inner pipe is a flow supply channel of the extraction type drilling tool, the central hole of the inner pipe is a gas extraction channel, and an annular gap between the outer pipe and the wall of the drilled hole is a slag discharge channel.

6. The cross-layer drilling extraction type drilling tool according to any one of claims 2 to 5, wherein the end of the outer pipe is changed into a thick-wall circular outer pipe by an extrusion forming method or a friction welding joint method, male and female buttons are arranged at two ends of the thick-wall circular outer pipe, adjacent outer pipes are connected through screw threads with seals, and adjacent inner pipes are connected through lap joint seals or plug joint seals.

7. The cross-bore extraction drilling tool according to claim 6, wherein the extraction type high-low pressure conversion valve comprises an outer valve pipe, an inner valve pipe and a high-low pressure conversion assembly, the outer valve pipe and the inner valve pipe are coaxially installed in a matched mode, and the high-low pressure conversion assembly is installed in a flow supply channel formed between the outer valve pipe and the inner valve pipe;

8. The cross-layer drilling extraction type drilling tool according to claim 7, wherein two to four axial convex ribs or spiral convex ribs with two ends gradually changed into inclined planes are arranged on the outer surface of the valve outer tube, and cutting blades are arranged on the side surfaces of the inclined planes; two axial convex ribs or two spiral convex ribs of the valve outer pipe are provided with radial water jet nozzles or inclined water jet nozzles; the valve outer pipe is characterized in that the axial convex rib or the spiral convex rib of the valve outer pipe is provided with a discontinuous spiral groove, and the discontinuous spiral groove enables the valve outer pipe to have slag crushing, stirring and conveying functions.

9. The cross-drilled extraction drilling tool of claim 8, wherein the high-low pressure conversion assembly comprises a sliding valve core, a spring, a front support, a rear support and a fixing pin; a sliding valve core is arranged between the front support and the rear support, a spring is sleeved between the sliding valve core and the valve inner pipe, and the front support and the rear support are both connected with the valve outer pipe through fixing pins; when the valve works, two ends of the spring are in contact fit with the sliding valve core and the rear support.

10. The cross-layer drilling extraction type drilling tool according to claim 9, wherein the sieve mesh air inlet device comprises a convex rib-shaped outer pipe, a convex rib-shaped inner pipe and an air inlet sieve mesh plate, the convex rib-shaped outer pipe and the convex rib-shaped inner pipe are coaxially installed in a matched mode, a space between the convex rib-shaped outer pipe and the convex rib-shaped inner pipe is a flow supply channel, and an inner hole of the convex rib-shaped inner pipe is a gas extraction channel; a male buckle and a female buckle are respectively arranged at two ends of the convex rib-shaped outer pipe, and a sealing element is arranged at one end of the convex rib-shaped inner pipe;

11. The cross-layer drilling extraction drilling tool as claimed in claim 10, wherein inverted-cone-shaped sieve holes are formed in the air inlet sieve plate, the diameter of air inlets of the sieve holes is one half to one fifth of the diameter of the radial air inlet through holes, and the sum of the areas of the air inlets of all the sieve holes is larger than the cross-sectional area of the inner hole of the rib-shaped inner pipe.

12. The cross-drilled extraction drilling tool of claim 11, wherein the open-close drill bit consists of a drill bit body, a short section inner pipe and an open cover; a short section inner pipe is coaxially arranged in the drill bit body; one end of the drill bit body is provided with a female buckle matched with the convex rib-shaped outer pipe; the outer edge of the other end of the drill bit body is provided with end teeth, and the center of the other end of the drill bit body is provided with an opening cover for covering the inner pipe of the short section; two pairs of pin holes are formed in the opening cover, a high-strength pin shaft is installed in one pair of pin holes, and a low-strength shearing pin is installed in the other pair of pin holes.

13. The cross-layer drilling extraction type drilling tool according to claim 12, wherein the extraction type water swivel comprises a hollow water swivel outer body, an extraction pipe, a pressure gauge, an extraction switch and a flow supply port, a hollow water swivel inner pipe is coaxially installed in an inner cavity of the hollow water swivel outer body, an inner hole of the hollow water swivel inner pipe is a gas extraction channel, one end of the hollow water swivel outer body is connected with an outer pipe of the extraction type drilling rod, the other end of the hollow water swivel inner pipe is connected with an inner pipe of the extraction type drilling rod, the extraction pipe connected with the hollow water swivel inner pipe is installed at the other end of the hollow water swivel outer body, the extraction pipe is provided with the pressure gauge and the extraction switch, and the pressure gauge displays gas pressure in the inner cavity of the drilling tool during gas extraction while drilling and gas pressure in a loose hole gas bag.

14. The cross-layer drilling extraction type drilling tool according to claim 13, wherein the controlled spray type drainage box comprises a hole packer, a drainage box, a gas drainage tube, a water-coal-cinder drainage tube, a dustproof brush and a controlled spray inserting plate arranged in the drainage box;

a hole packer is arranged at one end of the drainage box, a dustproof brush is arranged inside the other end of the drainage box, a gas drainage tube is arranged at the upper part of the drainage box, and a water coal cinder drainage tube is arranged at the lower part of the drainage box; two symmetrical injection control inserting plates are arranged at one end of the hole packer in the drainage box, the sectional area of a slag inlet channel in the drainage box is controlled by moving the inserting plates, and forced injection prevention and injection control are implemented when coal and gas outburst occurs in a coal hole section.

15. The cross-layer drilling extraction type drilling tool according to claim 1, wherein when the inclination angle of the drill hole is small, an extraction type drill rod can be additionally arranged between the extraction type high-low pressure conversion valve and the sieve pore air inlet device, the height difference between the sieve pore air inlet device and the extraction type high-low pressure conversion valve is increased, and the phenomenon that the sieve pore air inlet device is submerged by water to weaken the air inlet function is avoided.

16. The cross-layer drilling extraction type drilling tool according to claim 1, wherein when drilling is conducted on an extremely soft protruding coal seam which is difficult to form a hole, an extraction type high-low pressure conversion valve is removed, 2-4 oblique water jet nozzles for punching are installed on the opening and closing type drilling head, an included angle of about 45 degrees is formed between the outlet direction of each water jet nozzle and the drilling direction, and drilling and punching are conducted on a coal hole section synchronously.

17. The cross-drilled hole extraction type drilling tool as claimed in claim 1, wherein when drilling is performed on a medium-hard outburst coal seam which is easy to form a hole, the sieve pore air inlet device is removed, no slotting or punching and gas extraction while drilling are performed during the drilling of the coal pore section, the hole protection sieve tube is placed downwards before the drill is withdrawn, slotting or punching and gas extraction while drilling are performed during the drill withdrawal, and gas extraction while drilling is performed during the drill withdrawal slotting or punching by using the hole protection sieve tube.

18. The blowout-preventing hole while-drilling gas extraction method of the cross-layer drilling extraction type drilling tool according to any one of claims 1 to 17 is adopted, and the current advancing type slotting and punching are characterized by comprising the following steps:

first, preparation work

Reaming the hole, installing a spray-control drainage box at the hole opening, removing an extraction pipe on the extraction type water braid, connecting the extraction pipe with the existing slag discharge water discharger through a telescopic hose, and connecting the slag discharge water discharger with an extraction pipe network;

second, drilling in the rock bore section

The drilling of the rock hole section is not implemented with gas extraction while drilling, similar to the existing drilling, static pressure water of about 3MPa is supplied to an extraction type water swivel, and the drilling of the rock hole section is implemented;

thirdly, preparation work before slotting and punching

Once the drill hole enters the coal seam, firstly installing an extraction pipe at the tail part of an extraction type water braid, opening a high-pressure pump station used for slotting and punching, and connecting a related pipeline of a controlled spray type drainage box;

fourthly, the blowout-preventing hole is extracted while drilling gas

case I: under the normal condition, performing normal water jet slotting or punching operation and drill rod installation under the condition that the gas pressure of the inner cavity of the cross-layer drilling extraction type drilling tool is at negative pressure, and performing gas extraction while drilling on the gas of the hole loosening gas bag;

case II: when the gas pressure in the inner cavity of the cross-layer drilling extraction type drilling tool is in a positive pressure or higher pressure condition, reducing the flow supply flow rate of the cross-layer drilling extraction type drilling tool, reducing the rotation speed of the cross-layer drilling extraction type drilling tool, stopping the front and back movement of the cross-layer drilling extraction type drilling tool, suspending the installation of a drill rod, and when the gas pressure in the inner cavity of the cross-layer drilling extraction type drilling tool is reduced to a negative pressure or normal pressure, then performing normal slotting or punching operation and drill rod installation, and performing gas extraction while drilling on the gas of a 'loose hole gas bag';

case iii: the coal and gas in the hole are protruded, when the power phenomena such as the coal and gas in the hole are protruded, the gas pressure in the inner cavity of the cross-layer drilling extraction type drilling tool can be sharply increased to be positive pressure, and the control injection operation adopted under the condition is as follows: 1. reducing the flow supply rate of the cross-layer drilling extraction type drilling tool, reducing the rotation speed of the cross-layer drilling extraction type drilling tool, and strictly prohibiting the back-and-forth movement of the cross-layer drilling extraction type drilling tool; 2. the opening degree of a switch of an extraction pipe of the extraction type water braid is properly controlled, so that the gas is prevented from exceeding the limit due to the fact that a telescopic hose and a slag discharge water discharger are damaged by flushing; 3. the position of a control spraying inserting plate in the control spraying type drainage box is moved, so that gas exceeding caused by orifice spraying holes is prevented; by adopting the measures, when the gas pressure in the inner cavity of the cross-layer drilling extraction type drilling tool is reduced to negative pressure or normal pressure, normal slotting or punching operation and drill rod installation are resumed, and gas extraction while drilling is carried out on the gas of the hole-loosening gas bag;

fifthly, lowering the hole-protecting sieve tube before withdrawing the drill

When the slotting and punching operation advances to the coal seam roof or a drill bit enters the coal seam roof, removing an extraction pipe and a pressure gauge at the tail part of the extraction type water swivel, lowering a hole protection sieve pipe before performing bit withdrawal, and placing the hole protection sieve pipe with barbs into the top of a coal hole section through an inner hole of the extraction type water swivel, an extraction type drill rod inner pipe, a valve inner pipe, a convex rib-shaped inner pipe, a short section inner pipe of an opening and closing type drill bit and an opening cover; after the hole-protecting sieve tube is lowered, the extraction pipe and the pressure gauge of the extraction type water braid are installed again, and the gas extraction while drilling is started after the drill is withdrawn;

sixthly, withdrawing the drill while drilling gas extraction