Gas-driven drill bit for dredging gas extraction drill hole

Abstract

The utility model discloses a gas-driven drill bit for dredging a gas extraction drill hole. The gas-driven drill bit consists of a spray pipe base and a rotary drill bit; the spray pipe base mainly comprises a Laval spray pipe, a spray pipe connecting piece, an inner connecting chamber, a quick connector and the like; the Laval nozzle provides power for gas to drive the drill bit to advance. The rotary drill bit crushes coal briquettes blocking the drill hole, coal slag is discharged out of the drill hole through gas jet flow jetted by the Laval spray pipe / nozzle, and gas extraction drill hole dredging is effectively achieved. In addition, a rotary drill bit at the front end of the gas-driven drill bit is replaced by a comprehensive measuring instrument integrated with a gas concentration sensor and an extraction negative pressure sensor, and in-situ measurement of parameters such as gas concentration and extraction negative pressure in a drill hole can be achieved.

Description

Technical Field

[0001] This utility model belongs to the field of coal mine gas extraction technology, and in particular relates to a gas-driven drill bit for unblocking gas extraction boreholes. Background Technology

[0002] Coal seam gas is one of the main causes of coal mine accidents, severely restricting safe and efficient coal mine production. Gas drainage boreholes have become an effective measure for efficient gas drainage and control in my country. Most coal seams in my country are soft seams. With increasing mining depth, gas drainage boreholes frequently experience collapse and blockage due to mining activity and ground stress, obstructing gas transport channels and causing a rapid decline in gas drainage flow, resulting in long drainage cycles and hindering the alternation of mining and coal production. Unblocking collapsed boreholes that have lost their drainage capacity and restoring their drainage capabilities is an economical and efficient technical means.

[0003] To address issues such as borehole collapse and blockage in gas drainage boreholes, patent CN201210489910.1 discloses a "Comprehensive Method for Drilling, Permeability Enhancement, Repair, and Gas-Driven Replacement of Boreholes in Coal Mines." This method uses a flexible steel pipe of a hydraulic drilling rig to deliver a water jet nozzle into the borehole, using the water jet to flush and remove slag. However, this invention is limited by drilling conditions, and the hydraulic drilling rig is complex, heavy, and has a short effective operating length. Patent CN202110557026.6 discloses a "Hydraulic Combined Mechanical Borehole Repair Device and Method." This method uses a high-pressure water jet from a reverse nozzle at the drill bit's tip to power the mechanical drill bit, driving it to advance and rotate to break coal and remove slag. However, as the length of the gas drainage borehole increases, the weight of the high-pressure water pipeline increases linearly, leading to increased system resistance. The power provided by the reverse nozzle is insufficient to allow the mechanical drill bit to reach the bottom of the borehole, making it impossible to clear the entire section of the gas drainage borehole. Summary of the Invention

[0004] The purpose of this invention is to provide a gas-driven drill bit for unblocking gas extraction boreholes.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] A gas-driven drill bit for unblocking gas drainage boreholes comprises a nozzle base and a rotary drill bit. The nozzle base provides forward propulsion, ensuring the normal advance of the gas-driven drill bit within the gas drainage borehole. The rotary drill bit has stepped cutting teeth at its tip, which efficiently breaks up coal blocks clogging the borehole during its advance, thus unblocking the borehole.

[0007] Furthermore, the nozzle base includes a quick-connect fitting, a Laval nozzle, a nozzle connector, and an inner connector. Both the nozzle connector and the inner connector have through holes to serve as gas flow channels.

[0008] Furthermore, the Laval nozzle and nozzle connector are connected by threads. Compressed air flows through the through-hole of the nozzle connector to the inlet of the Laval nozzle. The airflow is further accelerated inside the Laval nozzle, forming a supersonic gas jet. The ejected gas jet generates retro-thrust, providing forward propulsion for the device. The dimensions of the Laval nozzle are calculated based on the required thrust.

[0009] Furthermore, the nozzle connector has a through-hole thread, and the inner connector has a threaded hole. The nozzle connector and the inner connector are connected by screws. An O-ring 1 is placed between the Laval nozzle and the nozzle connector, and an O-ring 2 is placed between the nozzle connector and the inner connector to ensure the airtightness of the nozzle base.

[0010] Furthermore, the main body of the rotary drill bit is a rotating body with stepped cutting teeth. The rotating body has four rotationally symmetrical cylindrical holes for installing Laval nozzles. An O-ring seal is located between the rotating body and the cover plate to ensure the airtightness of the rotary drill bit. The stepped cutting teeth are located at the very tip of the rotary drill bit and, under pressure and torque, cut and break up the coal and rock mass blocking the borehole. The rotating body and cover plate have through-hole threads, and the stepped cutting teeth have threaded holes. The rotating body, cover plate, and stepped cutting teeth are connected by screws.

[0011] Furthermore, deep groove ball bearings are placed at both ends of the rotating body, with washers placed between the two bearings. The rotating cylinder housing secures the rotating drill bit to the nozzle base by locking it into grooves on the inner connector of the nozzle base. The rotating cylinder housing is divided into left and right parts, both of which have through-threaded holes, and the left and right housings are fixed together with screws.

[0012] The advantages of this utility model are:

[0013] 1. The gas-driven drill bit of this device uses a Laval nozzle as its power structure. The propulsion force provided by compressed gas is strong enough to ensure that the device can reach the bottom of the gas drainage borehole smoothly.

[0014] 2. The gas-driven drill bit provided by this device is small in size. When clearing gas extraction boreholes, it enters the borehole through the gas extraction pipe without damaging the original sealing settings, thus ensuring the integrity of the borehole.

[0015] 3. The gas-driven drill bit of this device adopts a split design. Different structural components can be installed at the front end of the gas drive device to achieve different functions. For example, a rotary drill bit installed at the front end of the gas drive device can realize the unblocking of gas extraction boreholes; a comprehensive measuring instrument installed at the front end of the gas drive device can realize in-situ measurement of parameters such as borehole trajectory, gas concentration and extraction negative pressure in the borehole.

[0016] 4. Compared to hydraulically driven devices, this device uses gas as a power source. The device can be equipped with sensors or electronic components with measurement functions. The gas-driven method will not damage the electronic components, thus enhancing its functionality. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the gas-driven drill bit structure of this utility model.

[0018] Figure 2 This is a schematic diagram of the nozzle connector structure.

[0019] Figure 3 This is a schematic diagram of the internal connecting component.

[0020] Figure 4 This is a diagram showing the arrangement of lateral Laval nozzles in a rotating body.

[0021] 8-Gas-driven drill bit; 810-Nozzle base; 811-Quick connector; 812-Laval nozzle; 813-Nozzle connector; 814-Inner connector; 815-O-ring one; 816-O-ring two; 817-Screw one; 820-Rotary drill bit; 821-Rotary cylinder housing; 822-Deep groove ball bearing; 823-Washer ring; 824-Rotating body; 825-Cover plate; 826-Laval nozzle; 827-O-ring three; 828-Stepped cutting teeth; 829-Screw two. Detailed Implementation

[0022] like Figure 1As shown, a gas-driven drill bit for unblocking gas drainage boreholes is disclosed. The gas-driven drill bit 8 consists of a nozzle base 810 and a rotary drill bit 820. The nozzle base provides forward propulsion to ensure the normal forward movement of the gas-driven drill bit in the gas drainage borehole. The front end of the rotary drill bit has stepped cutting teeth, which can efficiently break up coal blocks blocking the borehole during the forward movement, thereby unblocking the borehole. The main body of the nozzle base 810 consists of a nozzle connector 813 and an inner connector 814. The Laval nozzle and the nozzle connector are connected by threads. Compressed air flows through the through hole of the nozzle connector to the inlet of the Laval nozzle. The airflow is further accelerated inside the Laval nozzle to form a supersonic gas jet. The ejected gas jet generates a reverse thrust, providing forward propulsion for the device. The dimensions of the Laval nozzle are calculated based on the required thrust. The nozzle connector has a through-hole thread, and the inner connector has a threaded hole. The nozzle connector and the inner connector are connected by screw 817. An O-ring 815 is placed between the Laval nozzle and the nozzle connector, and an O-ring 816 is placed between the nozzle connector and the inner connector to ensure the airtightness of the nozzle base. Both have through holes as gas flow channels. The quick-connect fitting 811 is threaded to one side of the nozzle base 810. The Laval nozzle 812 is threadedly connected to the center of the nozzle base 810. The rotating body 824 of the rotary drill bit 820 is fitted onto the inner connector 814 of the nozzle base 810. A pair of deep groove ball bearings 822 are placed at both ends of the rotating body 824, and a washer 823 is placed between the deep groove ball bearings 822. The rotary cylinder housing 821 fixes the rotary drill bit 820 and the nozzle base 810 by locking the groove on the inner connector of the nozzle base 810. The rotary cylinder housing 821 is divided into left and right parts, which are fixed by screws. The rotating body 824 has four rotationally symmetrical cylindrical holes for installing the Laval nozzle 826. The cover plate 825 is used to seal the rotating body 824. The O-ring 827 is located between the rotating body 824 and the cover plate 825 to ensure airtightness. The stepped cutting teeth 828 are located at the foremost end of the rotary drill bit 820. The rotating body 824, the cover plate 825 and the stepped cutting teeth 828 are fixedly connected by screws 829.

[0023] In practical use, determine the location of the gas drainage borehole that needs to be cleared, and disassemble the gas drainage borehole sealing pipe joint of that borehole; connect the gas supply pipe to the quick-connect fitting of the gas-driven drill bit; place the gas-driven drill bit 8 at the inlet of the drainage pipe, and open the flow control valve on the common gas pipe; determine the required gas pressure and flow parameters based on the length and angle of the gas drainage borehole, and control the flow control valve to ensure that the pressure and flow reach the required values; the Laval nozzle 812 on the nozzle base 810 of the gas-driven drill bit 8 provides forward thrust, and the lateral Laval nozzle 826 installed on the rotating drill bit 820 provides torque, driving the drill bit to rotate. Under the action of thrust and torque, the stepped cutting teeth 828 of the drill bit break the coal blockage in the borehole into coal slag; the gas jets ejected from the Laval nozzle 812 and Laval nozzle 826 discharge the broken coal slag from the borehole. When the scale value of the gas supply pipe matches the depth of the gas extraction borehole, it indicates that the dredging of the gas extraction borehole is complete. The gas supply pipe is then retrieved, and the gas-driven drill bit is pulled out.

Claims

1. A gas-driven drill bit for unblocking gas extraction boreholes, characterized in that: The gas-driven drill bit includes a nozzle base and a rotary drill bit connected thereto. The nozzle base includes a nozzle connector and an inner connector located at the front end of the nozzle connector. Both the nozzle connector and the inner connector have a through hole at their center. The rear end of the nozzle connector is fixedly connected to the Laval nozzle contraction section. The nozzle connector has a quick-connect plug receiving cavity. The inner connector has an inclined hole channel. One end of the inclined hole channel is connected to the through hole at the center of the inner connector, and the other end is connected to the central hole of the quick-connect plug. The rotary drill bit includes a rotating body and stepped cutting teeth at the front end. The rotating body is movably sleeved on the front end of the inner connector. Both the upper and lower ends of the rotating body are provided with a pair of deep groove ball bearings. The outer periphery of the front end of the rotating body has symmetrical cylindrical holes. A Laval nozzle is provided in the cylindrical hole. The Laval nozzle is connected to the through hole at the center of the inner connector.

2. The gas-driven drill bit for unblocking gas extraction boreholes as described in claim 1, characterized in that: The inner connector is T-shaped, including a horizontal part and a vertical part at the center of the front end. The deep groove ball bearing is located outside the horizontal part of the inner connector. A washer is provided between adjacent deep groove ball bearing positions. A rotating cylinder shell is provided outside the deep groove ball bearing. The rotating cylinder shell fixes the rear end of the rotating drill bit to the nozzle base by locking the groove on the inner connector.

3. The gas-driven drill bit for unblocking gas extraction boreholes as described in claim 1, characterized in that: The front end of the rotating body, i.e. the front end of the Laval nozzle, is provided with a sealing cover plate. The front end of the sealing cover plate is provided with stepped cutting teeth. The rotating body, the cover plate and the stepped cutting teeth are fixedly connected by screws.

4. The gas-driven drill bit for unblocking gas extraction boreholes as described in claim 2, characterized in that: The rotating cylinder shell consists of two parts, upper and lower, fixed together by screws.

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