Hole bottom reaming device for coal rock roadway drill hole

Abstract

The invention discloses a coal rock roadway drilling hole bottom reaming device which comprises a built-in pipe jacking device, a fixing pin, a fan-shaped rotary rock breaking device, a jacking device, a flat spring and a spring jacking thread device, the fan-shaped rotary rock breaking device capable of freely rotating within 0-90 degrees is installed at the front end of the built-in pipe jacking device, and high-strength cutting pick heads are installed on the upper side face and the lower side face of the fan-shaped rotary rock breaking device; the pushing device is located behind the fan-shaped rotary rock breaking device, the pushing device is pushed by the flat spring to move forwards, and then the fan-shaped rotary rock breaking device is unfolded; when the fan-shaped rotary rock breaking device rotates in a drill hole, the fan-shaped rotary rock breaking device is gradually opened under the combined action of centrifugal force and spring thrust, surrounding rock at the bottom and on the side wall of the drill hole is cut, and an expanded area is formed. The contact area of the anchoring body and the surrounding rock is increased through the enlarged area, and the anchoring effect and the overall stability of the roadway are remarkably improved; the device is simple in structure, components are tightly matched, and construction is convenient and fast; and the device is particularly suitable for roadway support under soft rock strata, soft and broken coal bodies and complex geological conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine tunnel support and relates to a hole bottom expanding device for a coal rock tunnel drilling hole. Background Art

[0002] During the construction of coal mine tunnels and underground projects, the stability of the tunnel surrounding rock is directly related to the safety and efficiency of the construction. Traditional support methods mainly include anchor rods, anchor cables, shotcrete and steel arches. Among them, anchor support is widely used because of its simple construction and low cost. However, traditional drilling and support methods have many shortcomings under complex geological conditions:

[0003] (1) The borehole diameter is uniform and the anchoring range is limited: The diameter of traditional boreholes is basically the same from the entrance to the bottom of the hole, usually 30-50 mm. This design results in a limited contact area between the anchor and the surrounding rock, and it is impossible to form a large-scale anchor body. The anchor is unevenly distributed in the hole, and it is easy to accumulate at the bottom of the hole and form a weak area on the hole wall. This uniform structure limits the anchor or resin from forming an effective mechanical lock in the hole, especially in weak surrounding rocks, which is more likely to cause the anchor (cable) to slip as a whole, affecting the support effect.

[0004] (2) Insufficient initial anchoring force under complex geological conditions: When the coal and rock mass is soft, broken or water-containing, the anchoring agent is difficult to fully penetrate and solidify. Water will dilute the anchoring agent and reduce its bonding strength; the soft and broken coal mass is difficult to provide a stable support point for the anchor rod (cable). The initial anchoring force of the anchor rod (cable) is insufficient and cannot meet the support requirements, resulting in deformation, collapse and other accidents in the tunnel surrounding rock, which seriously affects production safety.

[0005] (3) The anchor is easily pulled out, and the support effect is unstable: Due to the small mechanical bite force between the anchor and the surrounding rock, the anchor may be pulled out under stress, especially when the tunnel is subjected to vibration, stress changes or long-term loads. This not only reduces the support effect of a single anchor (cable), but may also trigger a chain reaction, resulting in the failure of the overall support system, increasing safety risks and maintenance costs.

[0006] (4) Existing hole expansion methods have limitations: Although some hole expansion technologies have been applied to tunnel support, such as bolt head expanders and chemical expansion agents, these methods usually have problems such as complex equipment, cumbersome construction, and high costs. It is difficult to operate in narrow underground spaces, and the transportation and installation of equipment are restricted. In addition, these methods often have difficulty in flexibly adjusting the size and shape of the anchoring area according to different geological conditions, resulting in insufficient adaptability in complex and changeable mine environments.

[0007] (5) Lack of targeted solutions: Currently, there is a lack of hole expansion devices specifically designed for coal-rock tunnels with soft surrounding rock conditions on the market, which cannot meet the needs of actual production. Most equipment and technologies are mainly used in hard rock or medium-hard rock formations, and are not very applicable to soft rock and soft and broken coal bodies.

[0008] In summary, the field of coal mine tunnel support urgently needs a device with simple structure, convenient construction, and the ability to form an expanded area at the bottom of the drill hole to improve the anchoring effect and meet the tunnel support needs under complex geological conditions. This not only helps to improve the safety production level of the mine, but also has important economic and social benefits. Summary of the invention

[0009] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a bottom expansion device for drilling holes in coal and rock tunnels to solve the problems of limited anchoring range, insufficient anchoring force, complex construction, and high cost in the existing coal mine tunnel support technology. Through innovative mechanical structure design and scientific construction methods, the present invention realizes the formation of an expansion area at the bottom of the drill hole, significantly increasing the contact area between the anchor body and the surrounding rock, thereby improving the anchoring effect, enhancing the overall stability of the tunnel, and meeting the tunnel support needs under complex geological conditions.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0011] A bottom hole expansion device for drilling a coal rock tunnel, comprising a built-in pipe jacking device, a fixing pin, a fan-shaped rotary rock breaker, a thruster, a flat spring and a spring thrusting threaded device;

[0012] The built-in pipe jacking device is a tubular structure, made of high-strength alloy steel, and its outer diameter is adapted to the borehole diameter so that it can enter the borehole and remain stable; the built-in pipe jacking device has two inner holes of different diameters, namely, the rear end inner hole diameter N and the front inner hole diameter M, and an internal thread located between the two and close to the rear end;

[0013] The fixing pin is arranged at the front end of the built-in pipe jacking device, and is made of high-strength alloy steel. A through hole is provided on the top for installing the fan-shaped rotary rock breaker. The structure of the fixing pin matches the groove of the fan-shaped rotary rock breaker, so that the fan-shaped rotary rock breaker can rotate freely within the range of 0°-90°.

[0014] The pusher can be placed inside the built-in pipe jacking device, behind the fan-shaped rotary rock breaker, and is made of high-strength steel. The front end surface of the pusher is in close contact with the bottom surface of the fan-shaped rotary rock breaker. The flat spring behind the pusher can push the pusher forward to expand the fan-shaped rotary rock breaker.

[0015] The spring pushing thread device is installed at the rear end of the built-in pipe jacking device, is made of alloy steel, and cooperates with the internal thread. By tightening or loosening the spring pushing thread device, the compression state of the flat spring can be accurately adjusted to meet different construction requirements.

[0016] The present invention also includes the following technical features:

[0017] Specifically, the diameter difference between the built-in pipe jacking device and the borehole wall is 2-4mm, so as to ensure that the device can smoothly enter the borehole, while maintaining good stability during the rotation and hole expansion process, avoiding shaking or deviation of the device due to excessive gap, and improving the accuracy and safety of construction.

[0018] Specifically, the diameter difference between the pusher and the built-in pipe jacking device is 0-5mm, so that the pusher can move smoothly in the built-in pipe jacking device, reduce friction resistance, avoid jamming due to too small a gap or shaking due to too large a gap, thereby ensuring the stability and efficiency of the hole expansion process.

[0019] Specifically, the inner diameter N of the built-in pipe jacking device is slightly larger than the inner diameter M, and the diameter difference between the two is 1-4 mm, which facilitates the installation and disassembly of the components, ensures the smooth installation of the pusher, flat spring and spring push threaded device in the built-in pipe jacking device, and also helps to maintain the overall structural strength and stability of the device.

[0020] Specifically, the length of the external thread of the spring pushing thread device is slightly larger than the effective length of the internal thread of the built-in pipe jacking device, ensuring that the flat spring can be completely compressed during the tightening process and ensuring the firmness of the installation, avoiding the risk of the spring pushing thread device loosening or falling off during construction, and improving the reliability and safety of the device.

[0021] Specifically, the groove of the fan-shaped rotary rock breaker matches the fixing pin so that its maximum opening angle is 90°. Through precise mechanical matching, the fan-shaped rotary rock breaker can be smoothly expanded to the designed angle under the action of rotation and centrifugal force, thereby expanding the cutting range, improving the cutting efficiency of the surrounding rock, forming a larger expansion area, and enhancing the anchoring effect.

[0022] Specifically, the distance between the starting section of the thread of the spring pushing thread device and the exposed surface is less than or equal to the length of the inner hole diameter N of the built-in pipe jacking device. During the tightening process, the spring pushing thread device can be completely embedded in the built-in pipe jacking device to avoid the exposed part being too long and being subject to external interference or damage, thereby ensuring the safety and stability of the device during the construction process.

[0023] Specifically, a plurality of cutting teeth are installed on the upper and lower sides of the fan-shaped rotary rock breaker. The cutting teeth are made of cemented carbide material with high hardness and wear resistance. When the fan-shaped rotary rock breaker is unfolded, it can efficiently cut the surrounding rock at the bottom and side wall of the borehole at the same time, thereby accelerating the hole expansion speed, improving the hole expansion effect and improving the construction efficiency.

[0024] Specifically, the flat spring material is made of spring steel with high elasticity and high fatigue strength, has good durability and stability, can adapt to multiple cycles of use, and prolongs the service life of the device.

[0025] The construction method of the bottom hole expansion device for coal-rock tunnel drilling comprises the following steps:

[0026] Step 1. Device assembly:

[0027] Step 1.1, installation of fixing pin and fan-shaped rotary rock breaker: install the fixing pin at the front end of the built-in pipe jacking device, then align the groove of the fan-shaped rotary rock breaker with the fixing pin and install it in place to ensure that it can rotate freely;

[0028] Step 1.2, installation of the thruster and flat spring: Place the thruster into the built-in pipe jacking device so that it contacts the bottom surface of the fan-shaped rotary rock breaker; then place the flat spring behind the thruster;

[0029] Step 1.3, installation of the spring push thread device: screw the spring push thread device into the internal thread of the built-in pipe jacking device, and compress the flat spring to a fully compressed state;

[0030] Step 2. Device installation:

[0031] Slowly push the assembled reaming device into the pre-drilled hole. The outer diameter of the built-in pipe jack matches the borehole diameter to ensure that the device reaches the bottom of the hole stably.

[0032] Step 3. Rotate and unfold:

[0033] Step 3.1, start rotation: connect the built-in pipe jacking device to the drilling rig, start the drilling rig, and make the device start rotating;

[0034] Step 3.2, expansion of the fan-shaped rotary rock breaker: under the combined action of centrifugal force and spring thrust, the fan-shaped rotary rock breaker begins to expand outward;

[0035] Step 3.3, the function of the flat spring: the flat spring gradually relaxes from a fully compressed state, pushing the thruster forward and accelerating the deployment of the fan-shaped rotary rock breaker;

[0036] Step 4. Cutting and expanding the hole:

[0037] Step 4.1, cutting process: the pick head on the fan-shaped rotary rock breaker starts to cut the surrounding rock at the bottom and side walls of the borehole;

[0038] Step 4.2, formation of an enlarged area: as the fan-shaped rotating rock breaker gradually expands to a maximum opening angle of 90°, an enlarged area with a larger diameter is formed;

[0039] Step 5. Complete the hole expansion:

[0040] Step 5.1, meet the design requirements: when the flat spring reaches the preset partial relaxation state, the expansion area reaches the designed size;

[0041] Step 5.2, stop rotation: stop the drilling rig rotation, and the hole expansion process is completed;

[0042] Step 6. Device recovery:

[0043] Step 6.1, loosen the spring push thread device: Use a cross-shaped rotator to loosen the spring push thread device;

[0044] Step 6.2, remove the components: remove the flat spring and the thruster in turn; since the fan-shaped rotary rock breaker loses the centrifugal force and spring thrust, it will automatically collapse;

[0045] Step 6.3, removing the device: remove the built-in pipe jacking device and the fan-shaped rotary rock breaker from the borehole together.

[0046] Compared with the prior art, the present invention has the following technical effects:

[0047] (1) Significantly improve anchoring force: By forming an enlarged area at the bottom of the borehole, the contact area between the anchor or resin anchor and the surrounding rock is increased. Experiments and practical applications have shown that the anchoring force can be increased by 30%-50%. The enlarged area forms a reliable mechanical locking effect, which enhances the bonding and bite force between the anchor and the surrounding rock, greatly reduces the risk of slippage of the anchor rod or cable, and improves the overall stability of the support system.

[0048] (2) Strong adaptability: The device has a simple structure and precise coordination between components. The diameter and depth of the hole can be flexibly adjusted according to different geological conditions. It is particularly suitable for tunnel support under complex geological conditions such as soft rock and soft and broken coal. It effectively solves the problem of insufficient anchoring force of traditional support methods under these conditions and fills the market gap.

[0049] (3) Convenient construction: The design of the device fully considers the limitations of the underground construction environment. It is small in size, light in weight, and easy to carry and install. The device can be used in conjunction with existing drilling rigs, without the need for large-scale equipment replacement, reducing equipment investment and maintenance costs. The construction steps are standardized, the operation is simple, and it is easy for on-site workers to master, which reduces the requirements for the operator's skill level and reduces the possibility of construction errors.

[0050] (4) High cost-effectiveness: By improving the support effect of a single anchor rod or cable, the number of support units can be reduced by 20%-30%, thereby reducing the overall support cost. It improves construction efficiency, reduces labor costs and equipment usage time. Due to the durability and reusability of the device, long-term use can further reduce unit costs and bring significant economic benefits.

[0051] (5) Safe and reliable: The device has high stability during operation and the connection between components is firm, which reduces the risk of failure during construction. The material and structural design of the device have been strictly tested and verified, and can withstand high-intensity construction pressure and complex underground environmental conditions. It reduces construction risks, ensures the safety of construction personnel, and improves the safety production level of the mine.

[0052] (6) Facilitates grouting: The enlarged area provides more space for grouting and improves the distribution of grouting materials in the hole. The grouting materials can more fully penetrate into the cracks in the surrounding rock, fill the voids, enhance the overall performance of the anchor body, and improve the seismic resistance and durability of the support system.

[0053] (7) Extending the life of support: The enhanced anchoring effect helps to extend the service life of the support system and reduce the frequency of subsequent maintenance and reinforcement. This reduces long-term operating costs and improves the efficiency and safety of tunnels. For deep mining and long-distance tunnels, extending the life of support has important economic and safety significance.

[0054] (8) Technological innovation: The present invention is innovative in mechanical design and construction technology, and provides a new solution for the field of coal mine tunnel support. The popularization and application of the device will promote technological progress in the industry and play an important demonstration role.

[0055] (9) High promotion value: Due to its wide application range, significant economic benefits and high safety performance, the device has wide promotion and application value. It can be widely used in coal mines, tunnels and underground projects at home and abroad, promoting the development of related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Schematic diagram of the location of the drilling rig and boreholes in the tunnel.

[0057] Figure 2Schematic diagram of the built-in pipe jacking device being pushed into the borehole.

[0058] Figure 3 Schematic diagram of the pusher being prepared for installation inside the built-in pipe jacking machine.

[0059] Figure 4 The figure is a schematic diagram of the assembly of a flat spring in a relaxed state, a spring-pushing threaded device and a cross-shaped rotator.

[0060] Figure 5 Schematic diagram of the hole-bottom reaming device starting the reaming work.

[0061] Figure 6 Schematic diagram of the hole expansion device completing the hole expansion.

[0062] The meaning of each number in the figure is:

[0063] 1. Drilling machine, 2. Drilling hole; 8. Inner hole diameter N, 9. Internal thread, 10. Built-in pipe jacking device, 11. Fixing pin, 12. Through hole, 13. Fan-shaped rotary rock breaker, 14. Pick head, 16. External surface, 18. Pusher, 20. Cross-shaped rotator, 21. Embedded cross lock, 22. External thread, 23. Front head, 24. Flat spring, 24-2. Gradual relaxation state of flat spring, 24-4. Maximum relaxation state of flat spring, 29. Inner hole diameter M, 34. Embedded threaded hole, 35. Spring push thread device. DETAILED DESCRIPTION

[0064] The present invention provides a device for expanding the bottom of a coal-rock tunnel borehole. Figures 1 to 6 As shown, it includes key components such as a built-in pipe jack 10, a fixing pin 11, a fan-shaped rotary rock breaker 13, a pusher 18, a flat spring 24 and a spring push thread device 35. The front end of the built-in pipe jack is equipped with a fan-shaped rotary rock breaker that can rotate freely within the range of 0°-90°. The upper and lower sides of the fan-shaped rotary rock breaker are both equipped with high-strength pick heads to enhance the cutting ability. The pusher is located behind the fan-shaped rotary rock breaker. The pusher is pushed forward by the thrust of the flat spring, thereby expanding the fan-shaped rotary rock breaker. When rotating in the borehole, the device uses the combined action of centrifugal force and spring thrust to gradually open the fan-shaped rotary rock breaker, cutting the surrounding rock at the bottom and side walls of the borehole to form an expanded area. The expanded area increases the contact area between the anchor body and the surrounding rock, significantly improving the anchoring effect and the overall stability of the tunnel. The device has a simple structure, the components are tightly matched, the construction is convenient and quick, and it can be used in conjunction with the existing drilling rig without the need for additional large-scale equipment investment. It is particularly suitable for tunnel support in soft rock layers, soft and broken coal bodies and complex geological conditions, solving the problem of insufficient anchoring force of traditional support methods under these conditions, and has broad application prospects and promotion value.

[0065] (1) Built-in pipe jacking device 10:

[0066] Structural features: It is a tubular structure made of high-strength alloy steel with good wear resistance and impact resistance. The outer diameter is adapted to the borehole diameter, and the gap between the outer surface 16 and the borehole wall is 0-10mm, preferably 2-4mm, to ensure that the device can smoothly enter the borehole and remain stable.

[0067] Internal design: The internal part of the built-in pipe jacking device 10 is composed of two inner holes of different diameters, namely the inner hole diameter N8 at the rear end and the inner hole diameter M29 at the front end, and the inner thread 9 located between the two and close to the rear end, which is used to install the spring pushing thread device 35.

[0068] Function: Serves as the main structure of the device, accommodates and supports other components, and transmits rotational power.

[0069] (2) Fixing pin 11:

[0070] Material selection: The fixing pin 11 is arranged at the front end of the built-in pipe jacking device 10 and is made of high-strength alloy steel material with sufficient strength and toughness.

[0071] Structural features: a through hole 12 is provided on the top for installing a fan-shaped rotary rock breaker 13 ; the structure of the fixing pin 11 matches the groove of the fan-shaped rotary rock breaker 13 .

[0072] Function: The fan-shaped rotary rock breaker 13 can rotate freely within the range of 0°-90°, with a maximum opening angle of 90°, thereby improving the cutting range and efficiency.

[0073] (3) Fan-shaped rotary rock breaker 13:

[0074] Material selection: The fan-shaped rotary rock breaker 13 is installed at the front end of the built-in pipe jacking device 10 through the fixing pin 11. It is made of wear-resistant alloy steel material, and the surface is specially heat-treated and hardened to enhance its wear resistance and service life.

[0075] Structural design: The groove is in a 90° structure and can rotate freely within the range of 0°-90°. A plurality of pick heads 14 are evenly mounted on the upper side and the lower side.

[0076] The pick head 14 is made of cemented carbide material, has high hardness and wear resistance, has excellent cutting performance and wear resistance, and is used for cutting the side wall and bottom of the surrounding rock to achieve efficient hole expansion of the bottom and side wall of the borehole.

[0077] Function: Used to cut the side wall and bottom of the surrounding rock to achieve efficient hole expansion on the bottom and side wall of the drill hole.

[0078] (4) Thruster 18:

[0079] Material selection: The pusher 18 can be placed inside the built-in pipe jacking device 10, behind the fan-shaped rotary rock breaker 13, and is made of high-strength steel, with good mechanical strength and durability.

[0080] Structural features: The front end surface of the thruster 18 is in close contact with the bottom surface of the fan-shaped rotary rock breaker 13, and the rear end is provided with an embedded threaded hole 34, which is convenient for disassembly after the construction is completed.

[0081] Size design: The diameter difference between the pusher 18 and the built-in pipe jacking device 10 is 0-5 mm, preferably 2 mm, to ensure that the pusher can move smoothly in the built-in pipe jacking device without getting stuck.

[0082] Function: The flat spring 24 at the rear of the thruster 18 can push the thruster 18 forward to expand the fan-shaped rotary rock breaker 13.

[0083] (5) Flat spring 24:

[0084] Material selection: The flat spring 24 is installed at the rear of the pusher 18 and is made of spring steel with high elasticity and high fatigue strength. After a special heat treatment process, it has excellent elastic properties and durability.

[0085] The flat spring provides a continuous and stable thrust between the fully compressed state (A1) and the partially relaxed state (A3), and its elastic force satisfies the formula: F = k × (A3-A1), where F is the elastic force and k is the spring constant. By accurately designing the parameters of the spring, it is ensured that sufficient thrust is provided during the working process, so that the fan-shaped rotary rock breaker 13 can be smoothly deployed.

[0086] Parameter design:

[0087] ① Spring constant (k): Calculate accurately according to actual needs to ensure sufficient thrust during operation.

[0088] ② Fully compressed length (A1) and partially relaxed length (A3): By adjusting these two parameters, the thrust range of the spring is controlled.

[0089] Function: Provide continuous and stable thrust between the fully compressed state and the partially relaxed state, so that the fan-shaped rotary rock breaker 13 can be smoothly deployed.

[0090] (6) Spring push thread device 35:

[0091] Material selection: The spring push thread device 35 is installed at the rear end of the built-in pipe jacking device 10 and is made of alloy steel with good mechanical strength and wear resistance.

[0092] Structural features: In cooperation with the internal thread 9, the length L2 of the external thread 22 is slightly greater than the effective length (L1) of the internal thread 9 of the built-in pipe jacking device 10, ensuring the firmness of the installation and the complete compression of the spring.

[0093] Design details: The distance (L4) between the starting section of the thread of the spring push thread device and the exposed surface is designed to be less than or equal to the length (L5) of the inner hole diameter N8 of the built-in pipe jacking device 10 to avoid damage to the spring push thread device during the tightening process.

[0094] Function: By tightening or loosening the spring push thread device 35, the compression state of the flat spring 24 can be accurately adjusted to meet different construction requirements.

[0095] More specifically, the diameter difference between the built-in pipe jacking device 10 and the borehole wall is 2-4 mm to ensure that the device can smoothly enter the borehole, while maintaining good stability during rotation and hole expansion, avoiding shaking or deviation of the device due to excessive gap, and improving the accuracy and safety of construction.

[0096] The diameter difference between the pusher 18 and the built-in pipe jacking device 10 is 0-5 mm, preferably 2 mm. Such a design allows the pusher 18 to move smoothly in the built-in pipe jacking device 10, reduces friction resistance, avoids jamming due to too small a gap or shaking due to too large a gap, thereby ensuring the stability and efficiency of the hole expansion process.

[0097] The inner diameter N8 of the built-in pipe jacking device 10 is slightly larger than the inner diameter M29, and the diameter difference between the two is 1-4 mm, preferably 2 mm. Such a design facilitates the installation and disassembly of the components, ensures the smooth installation of the pusher 18, the flat spring 24 and the spring push thread device 35 in the built-in pipe jacking device 10, and also helps to maintain the overall structural strength and stability of the device.

[0098] The length (L2) of the external thread 22 of the spring push thread device 35 is slightly larger than the effective length (L1) of the internal thread 9 of the built-in pipe jacking device 10, ensuring that the flat spring 24 can be fully compressed during the tightening process and ensuring the firmness of the installation. This design avoids the risk of the spring push thread device 35 loosening or falling off during construction, thereby improving the reliability and safety of the device.

[0099] The groove of the fan-shaped rotary rock breaker 13 matches the fixing pin 11, so that its maximum opening angle is 90°. Through precise mechanical matching, the fan-shaped rotary rock breaker 13 can be smoothly expanded to the designed angle under the action of rotation and centrifugal force, thereby expanding the cutting range, improving the cutting efficiency of the surrounding rock, forming a larger expansion area, and enhancing the anchoring effect.

[0100] The distance (L4) between the starting section of the thread of the spring pushing thread device 35 and the exposed surface is designed to be less than or equal to the length (L5) of the inner hole diameter N8 of the built-in pipe jacking device 10. In this way, during the tightening process, the spring pushing thread device 35 can be completely embedded in the built-in pipe jacking device 10, avoiding the exposed part from being too long and being interfered or damaged by the outside, thereby ensuring the safety and stability of the device during the construction process.

[0101] A plurality of pick heads 14 are installed on the upper and lower sides of the fan-shaped rotary rock breaker 13. The pick heads 14 are made of cemented carbide material with high hardness and wear resistance. This design enables the fan-shaped rotary rock breaker 13 to efficiently cut the surrounding rock at the bottom and side wall of the borehole at the same time after it is unfolded, thereby accelerating the hole expansion speed, improving the hole expansion effect, and improving the construction efficiency.

[0102] The elastic force and size of the flat spring 24 are precisely calculated and designed to provide continuous and stable thrust during the construction process, ensuring that the fan-shaped rotary rock breaker 13 maintains a good expansion state during the hole expansion process. The material of the spring is selected from spring steel with high elasticity and high fatigue strength. After a special heat treatment process, it has good durability and stability, can adapt to multiple cycles, and extend the service life of the device.

[0103] The various components of the device are precisely matched and assembled, and the connection parts between the components are strictly processed and inspected to ensure that the device has good overall stability and reliability under high-intensity and high-speed construction environments. The material and surface treatment of the device are optimized and designed to have wear-resistant, corrosion-resistant and impact-resistant properties, adapting to the complex and changeable geological conditions and environment of coal mine tunnels.

[0104] Specifically, Figure 1 It is a schematic diagram of the tunnel drilling of the coal-rock tunnel drilling bottom hole expansion device of the present invention, showing the positions of the drilling rig and the borehole in the tunnel, as well as the overall application environment of the device. Figure 2 This is a schematic diagram of the process of pushing the built-in pipe jacking device into the borehole, showing the process of the built-in pipe jacking device entering the borehole to ensure that the device reaches the predetermined position smoothly. Figure 3 A schematic diagram showing the preparation for installing the pusher into the internal pipe jacking device, showing the relative positions of the pusher and the internal pipe jacking device, as well as the preparations before installation. Figure 4 The diagram is an assembly diagram of a flat spring, a spring push thread device and a cross-shaped rotator in a relaxed state, showing the structural details and assembly relationships of these components, providing guidance for subsequent installation. Figure 5 This is a schematic diagram of the hole-reaming device at the bottom of the borehole starting to expand, showing the working status of the device in the borehole. The fan-shaped rotary rock breaker begins to expand under the action of rotation and centrifugal force to carry out the hole expansion operation. Figure 6A schematic diagram of the borehole bottom reaming device completing the reaming, showing the state after the reaming is completed, with the fan-shaped rotary rock breaker fully deployed to form the expected expansion area.

[0105] Details of the components in the attached drawings: Drilling machine: used to drive the device to rotate and realize drilling and reaming operations. Drilling hole: a hole drilled in the surrounding rock of the tunnel in advance, used to install the device for bottom hole reaming. The first section of the inner diameter of the built-in pipe jack is used to accommodate the jack, flat spring and spring jack threaded device. The internal thread at the rear end of the built-in pipe jack matches the external thread of the spring jack threaded device. The built-in pipe jack is the main structure of the device, which is tubular and accommodates and supports other components. The fixing pin is installed at the front end of the built-in pipe jack to fix the fan-shaped rotary rock breaker, allowing it to rotate freely within the range of 0°-90°. The through hole at the top of the fixing pin is used to install the fan-shaped rotary rock breaker so that it can rotate around the fixing pin. The fan-shaped rotary rock breaker is installed on the fixing pin and has a groove structure, which can be expanded under the action of rotation and centrifugal force to cut the surrounding rock. The pick head embedded on the fan-shaped rotary rock breaker is a carbide pick installed on the fan-shaped rotary rock breaker, which is used to efficiently cut the side wall and bottom of the surrounding rock. The outer surface of the built-in pipe jacking device is in contact with the borehole wall. It has been precisely machined to reduce friction resistance and ensure that the device enters the borehole smoothly. The pusher is located in the built-in pipe jacking device and is pushed by the flat spring to push the fan-shaped rotary rock breaker to expand. The cross-shaped rotator is used to tighten or loosen the spring push thread device and adjust the compression state of the flat spring. The embedded cross lock of the spring push thread device is set in the cross-shaped groove at the rear end of the spring push thread device, which is used to insert the cross-shaped rotator to achieve tightening or loosening operations. The outer thread of the spring push thread device matches the inner thread of the built-in pipe jacking device to adjust the compression degree of the flat spring. The front head of the spring push thread device is located at the front end of the spring push thread device, which is used to compress the flat spring, and the front end surface is in contact with the spring. The flat spring provides thrust to push the pusher forward to expand the fan-shaped rotary rock breaker. The compressed state of the flat spring After installation, the flat spring is fully compressed and ready to provide thrust. The gradual relaxation state of the flat spring During the expansion process, the flat spring gradually relaxes and pushes the pusher forward. Further relaxation state of the flat springThe flat spring continues to relax, the thruster continues to move forward, and the fan-shaped rotary rock breaker gradually expands. Maximum relaxation state of the flat springThe flat spring reaches the designed working length, the thrust reaches the expected value, and the fan-shaped rotary rock breaker is fully expanded.The top surface of the thruster contacts the bottom surface of the fan-shaped rotary rock breaker to transmit the thrust of the flat spring.Inner aperture M of the built-in pipe jacking deviceThe second section of the inner aperture of the built-in pipe jacking device is used to accurately position the thruster and the fan-shaped rotary rock breaker.The embedded threaded hole is set at the rear end of the thruster for inserting tools to remove the thruster during disassembly.The spring push threaded device is installed at the rear end of the built-in pipe jacking device, and the compression state of the flat spring is adjusted by tightening or loosening.

[0106] L1—Effective length of the internal thread: the length that matches the external thread of the spring push thread device to ensure a secure installation. L2—Thread length of the external thread of the spring push thread device: slightly larger than the effective length of the internal thread to ensure full compression of the spring. L3—Effective length of the fixing pin: the depth of the fixing pin inserted into the built-in pipe jacking device and the fan-shaped rotary rock breaker to ensure a secure connection. L4—The distance from the starting section of the thread of the spring push thread device to the exposed surface: designed to be less than or equal to the length L5 of the inner diameter N of the built-in pipe jacking device to avoid damage to the device. L5—The length of the inner diameter N of the built-in pipe jacking device: the partial length that accommodates the flat spring and the pusher. φa—The outer diameter of the pusher: slightly smaller than the inner diameter M to ensure smooth movement of the pusher in the built-in pipe jacking device.

[0107] The construction method of the bottom hole expansion device for coal rock tunnel drilling comprises the following steps:

[0108] Step 1. Device assembly:

[0109] Step 1.1, installation of fixing pin and fan-shaped rotary rock breaker: install the fixing pin at the front end of the built-in pipe jacking device, then align the groove of the fan-shaped rotary rock breaker with the fixing pin and install it in place to ensure that it can rotate freely;

[0110] Step 1.2, installation of the thruster and flat spring: Place the thruster into the built-in pipe jacking device so that it contacts the bottom surface of the fan-shaped rotary rock breaker; then place the flat spring behind the thruster;

[0111] Step 1.3, installation of the spring push thread device: screw the spring push thread device into the internal thread of the built-in pipe jacking device, and compress the flat spring to a fully compressed state (A1);

[0112] Step 2. Device installation:

[0113] Slowly push the assembled reaming device into the pre-drilled hole. The outer diameter of the built-in pipe jack matches the borehole diameter to ensure that the device reaches the bottom of the hole stably.

[0114] Step 3. Rotate and unfold:

[0115] Step 3.1, start rotation: connect the built-in pipe jacking device to the drilling rig, start the drilling rig, and make the device start rotating;

[0116] Step 3.2, expansion of the fan-shaped rotary rock breaker: under the combined action of centrifugal force and spring thrust, the fan-shaped rotary rock breaker begins to expand outward;

[0117] Step 3.3, the function of the flat spring: the flat spring gradually relaxes from a fully compressed state, pushing the thruster forward and accelerating the deployment of the fan-shaped rotary rock breaker;

[0118] Step 4. Cutting and expanding the hole:

[0119] Step 4.1, cutting process: the pick head on the fan-shaped rotary rock breaker starts to cut the surrounding rock at the bottom and side walls of the borehole;

[0120] Step 4.2, formation of an enlarged area: as the fan-shaped rotating rock breaker gradually expands to a maximum opening angle of 90°, an enlarged area with a larger diameter is formed;

[0121] Step 5. Complete the hole expansion:

[0122] Step 5.1, meet the design requirements: when the flat spring reaches the preset partial relaxation state, the expansion area reaches the designed size;

[0123] Step 5.2, stop rotation: stop the drilling rig rotation, and the hole expansion process is completed;

[0124] Step 6. Device recovery:

[0125] Step 6.1, loosen the spring push thread device: Use a cross-shaped rotator to loosen the spring push thread device;

[0126] Step 6.2, remove the components: remove the flat spring and the thruster in turn; since the fan-shaped rotary rock breaker loses the centrifugal force and spring thrust, it will automatically collapse;

[0127] Step 6.3, removing the device: remove the built-in pipe jacking device and the fan-shaped rotary rock breaker from the borehole together.

[0128] The present invention includes the following detailed designs:

[0129] 1. Innovative design of fan-shaped rotary rock breaker:

[0130] (1) Free rotation structure: Through the special combination of the fixed pin and the fan-shaped rotating rock breaker, automatic expansion and contraction under the action of rotation and centrifugal force is achieved.

[0131] (2) Multi-faceted cutting: The upper and lower sides of the fan-shaped rotary rock breaker are equipped with pick heads, which can cut the bottom and side walls of the borehole at the same time, improving the hole expansion efficiency.

[0132] 2. Clever application of flat springs:

[0133] (1) Continuous and stable thrust: By accurately calculating the spring constant and compression amount, the flat spring provides continuous and stable thrust during the hole expansion process, ensuring the smooth deployment of the fan-shaped rotary rock breaker.

[0134] (2) Simple and reliable: Compared with complex hydraulic or mechanical drive systems, the application of flat springs simplifies the structure, reduces the failure rate and improves reliability.

[0135] 3. Modular and standardized design of the device:

[0136] (1) Component standardization: Each component adopts standardized dimensions and interfaces to facilitate production, assembly, and maintenance.

[0137] (2) Strong adaptability: The size and parameters of the device can be adjusted according to different drilling diameters and geological conditions, and it has good versatility.

[0138] 4. Optimization of materials and processes:

[0139] (1) High-performance materials: High-strength alloy steel, spring steel and cemented carbide are selected to ensure the wear resistance and service life of the device.

[0140] (2) Advanced processing technology: Heat treatment, surface hardening and other processes are used to improve the mechanical properties and corrosion resistance of components.

[0141] The present invention includes the following application effects:

[0142] 1. Significantly improve anchoring force

[0143] (1) By forming an enlarged area at the bottom of the borehole, the contact area between the anchor and the surrounding rock is increased, and the anchoring force can be increased by 30%-50%.

[0144] (2) The mechanical bite force between the anchor rod (cable) and the surrounding rock is enhanced, reducing the risk of slippage.

[0145] 2. Improve roadway stability

[0146] (1) The enhanced anchoring effect significantly improves the overall stability of the tunnel and reduces the possibility of deformation and collapse.

[0147] (2) The effect is particularly obvious for soft rock layers and loose and broken coal bodies.

[0148] 3. High construction efficiency

[0149] (1) The device has a simple structure and is easy to operate. It can be used with existing drilling rigs without the need for large-scale equipment replacement.

[0150] (2) Standardization of construction steps reduces construction time and labor costs.

[0151] 4. Significant economic benefits

[0152] (1) The support effect of a single anchor (cable) is improved, which can reduce the number of support units and reduce the overall support cost.

[0153] (2) Extend the service life of the support system and reduce the frequency of subsequent maintenance and reinforcement.

[0154] 5. Safe and reliable

[0155] (1) The device operates stably and the components are firmly connected, which reduces construction risks and ensures the safety of construction workers.

[0156] (2) It is applicable to various complex geological conditions and improves the safety of construction.

[0157] Compared with the prior art, the present invention is specifically as follows:

[0158] 1. Disadvantages of traditional methods

[0159] (1) Complex equipment and high cost: Existing hole expansion equipment is usually complex in structure and expensive, which is not conducive to promotion and application.

[0160] (2) The construction is complicated and inefficient: there are many operation steps and the construction time is long, which increases labor costs.

[0161] 2. Advantages of the present invention

[0162] (1) Simple structure and low cost: The device has a simple design, low manufacturing cost and is easy to promote.

[0163] (2) Convenient construction and high efficiency: simple operation, fast construction speed, and improved work efficiency.

[0164] (3) Strong adaptability and high versatility: It can be adjusted according to different needs and has a wide range of applications.

[0165] The present invention includes the following industrialization prospects:

[0166] 1. Market demand

[0167] (1) With the increase in coal mining depth and the complexity of geological conditions, there is an urgent need for efficient and safe tunnel support technology.

[0168] (2) The device of the present invention has strong adaptability and meets the actual needs of the market.

[0169] 2. Economic Benefits

[0170] (1) Improved the safety production level of mines and reduced the occurrence of safety accidents.

[0171] (2) It reduces construction and maintenance costs and has good economic benefits.

[0172] 3. Social Benefits

[0173] (1) It has improved the technical level of the coal mining industry and promoted the progress of the industry.

[0174] (2) It ensures the safety of construction workers and has positive social significance.

[0175] The present invention provides an efficient and reliable coal-rock tunnel drilling bottom expansion device through innovative mechanical structure design and scientific construction methods. The device has a simple structure, convenient construction, strong adaptability, and can significantly improve the anchoring effect and enhance the overall stability of the tunnel. Compared with traditional technologies, it has obvious advantages and has broad application prospects and promotion value. Through the implementation of the present invention, it will provide new ideas for the development of coal mine tunnel support technology, which is of great significance to improving the safety production level of mines, reducing construction costs, and improving economic benefits.

[0176] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0177] Example:

[0178] This embodiment provides a bottom hole expansion device for drilling a coal rock tunnel, specifically comprising:

[0179] 1. Specific structure and parameters of the device

[0180] 1. Built-in pipe jacking device 10

[0181] (1) Material selection:

[0182] ① Made of high-strength alloy steel, such as 42CrMo or 35CrMo, after quenching and tempering, it has excellent mechanical properties and wear resistance. The yield strength of the material is not less than 800MPa, the tensile strength is not less than 1000MPa, and the elongation is above 12%.

[0183] ② In order to adapt to the complex working environment of coal mine tunnels, the surface can be carburized or nitrided to increase the surface hardness to HRC58-62 and enhance wear resistance and corrosion resistance.

[0184] (2) Dimensional parameters:

[0185] ① Outer diameter (D1): Φ42mm, which matches the conventional drilling diameter (Φ45mm) to ensure that the device can enter the drill hole smoothly. The gap between the outer diameter and the drill hole diameter is 1.5mm.

[0186] ② Length (L0): 1500mm, which meets the depth requirements of general tunnel anchor support and can be adjusted within the range of 1000mm to 3000mm according to actual needs.

[0187] (3) Internal structure:

[0188] ①Inner hole diameter N8:

[0189] Inner diameter (d1): Φ32mm, length (L5) is 1400mm.

[0190] It is used to accommodate the pusher 18 , the flat spring 24 and the spring push thread device 35 .

[0191] Wall thickness (δ1): calculated based on the outer diameter and inner diameter, δ1 = (D1-d1) / 2 = (42mm-32mm) / 2 = 5mm, ensuring the strength and rigidity of the built-in pipe jacking device.

[0192] ②Inner hole diameter M29:

[0193] Inner diameter (d2): Φ30mm, located at the front end, length (L6) is 100mm.

[0194] It is used to accurately position the thruster 18 and the fan-shaped rotary rock breaker 13 to ensure that they are not deflected during the working process.

[0195] ③Internal thread 9:

[0196] Thread type: M30×1.5, precision grade 6g, ensuring the firmness and reliability of threaded connection.

[0197] Effective length (L1): 80 mm, meeting the requirements for installation of the spring push thread device 35.

[0198] (4) Outer surface 16:

[0199] ①The surface is precision turned to a roughness of Ra ≤ 1.6μm and kept smooth to reduce friction resistance in the drill hole.

[0200] ②It can be galvanized or sprayed with anti-corrosion paint to enhance corrosion resistance and extend service life.

[0201] 2.Fixing pin 11

[0202] (1) Material selection:

[0203] ①Use alloy steel, such as 40Cr or 45 steel, after quenching and tempering treatment, the surface hardness reaches HRC40-45, with high strength and wear resistance.

[0204] (2) Dimensional parameters:

[0205] ① Diameter (d3): Φ10 mm, ensuring sufficient strength to fix the fan-shaped rotary rock breaker 13 and withstand the torque and shear force generated during the cutting process.

[0206] ② Effective length (L3): 20 mm, ensuring that the fixing pin can be firmly embedded in the front end of the built-in jacking device 10 and the groove of the fan-shaped rotary rock breaker 13.

[0207] ③Through hole 12: with a diameter of Φ6 mm, located at the top of the fixing pin, used to install the fan-shaped rotating rock breaker 13 and allow it to rotate freely within the range of 0°-90°.

[0208] 3. Fan-shaped rotary rock breaker 13

[0209] (1) Material selection:

[0210] ①Use high-strength wear-resistant alloy steel, such as T8 or T10 steel, after quenching and tempering treatment, the surface hardness reaches HRC55-60.

[0211] ②The surface can be carburized or nitrided to further improve wear resistance and impact resistance.

[0212] (2) Structural design:

[0213] ①Size:

[0214] Length (L7): 100mm, can be adjusted from 80mm to 150mm according to the drilling diameter and hole expansion requirements.

[0215] Width (W1): 30mm, to ensure effective cutting of the side wall of the drill hole after expansion.

[0216] Thickness (T1): 15mm, ensuring the strength and rigidity of the fan-shaped rotary rock breaker.

[0217] ②Groove structure:

[0218] Matching with the fixing pin 11, the groove angle is 90° and the depth h1 is 10 mm, ensuring that the fan-shaped rotary rock breaker can rotate freely within the range of 0°-90° under the restriction of the fixing pin.

[0219] ③ Scope of activities:

[0220] Through the cooperation between the fixing pin 11 and the groove, under the action of rotation and centrifugal force, it gradually unfolds from the retracted state (0°) to the maximum open state (90°).

[0221] The expansion angle (θ) of the fan-shaped rotary rock breaker is related to the rotation speed (n) and the centrifugal force (F_c), which can be calculated by the formula:

[0222] F_c=m·r·ω^2

[0223] in:

[0224] m-mass of the fan-shaped rotary rock breaker;

[0225] r - radius of rotation;

[0226] ω-angular velocity, ω=2πn / 60.

[0227] ④ Pick head 14:

[0228] Three carbide picks are installed on the upper side and the lower side respectively.

[0229] Cutting tooth diameter (d4): Φ8mm, made of YG11C cemented carbide, with a hardness of HRA89 or above and a bending strength of not less than 2200MPa.

[0230] The picks are arranged at equal intervals with a spacing (s) of 25 mm to ensure uniform distribution of cutting force and improve hole expansion efficiency.

[0231] ⑤Surface treatment:

[0232] The surface of the fan-shaped rotary rock breaker is shot peened to eliminate stress concentration and increase fatigue life.

[0233] Can be coated with wear-resistant coatings such as TiN or Al 2 O 3 , improve surface hardness and wear resistance.

[0234] 4. Pusher 18

[0235] (1) Material selection:

[0236] ① Use high-strength steel, such as 42CrMo, which has been quenched and tempered to a hardness of HRC28-32, and can withstand the thrust of the flat spring 24 and the pressure generated during the construction process.

[0237] ②The surface is precision machined, with a roughness of Ra ≤ 0.8μm, to reduce friction resistance.

[0238] (2) Structural design:

[0239] ①Outer diameter : Φ29.5mm, which is 0.5mm smaller than the inner hole diameter M29, ensuring smooth movement in the built-in pipe jacking device 10 without jamming.

[0240] ② Length (L8): 200 mm, which meets the travel requirement for pushing the fan-shaped rotary rock breaker 13 to be fully deployed.

[0241] ③Top surface:

[0242] The front end surface is in close contact with the bottom surface of the fan-shaped rotary rock breaker 13 and is designed to be in plane or spherical contact to reduce contact stress.

[0243] The rear end surface contacts the flat spring 24 and is designed to be flat to ensure uniform force.

[0244] ④Embedded threaded hole 34:

[0245] The thread specification is M12×1.75, and the depth is 30 mm. After the construction is completed, the pusher 18 can be taken out through a screw rod or a special tool for easy reuse.

[0246] ⑤Surface treatment:

[0247] The surface can be chrome plated or nickel plated with a coating thickness of 0.02-0.05mm to improve wear resistance and corrosion resistance.

[0248] 5. Flat spring 24

[0249] (1) Material selection:

[0250] ① Use high-quality spring steel, such as 60Si2Mn or 50CrVA, after oil quenching and tempering treatment, the elastic modulus is 196GPa, and the ultimate strength is not less than 1500MPa.

[0251] (2) Parameter design:

[0252] ① Spring constant (k):

[0253] Set to 500N / mm to ensure sufficient thrust during compression and relaxation.

[0254] Spring constant calculation formula:

[0255] k=Gd^4 / (8nD^3)

[0256] in:

[0257] G is the shear modulus, which is about 79.3GPa;

[0258] d is the spring wire diameter;

[0259] n is the effective number of turns;

[0260] D is the spring center diameter.

[0261] ②Size parameters:

[0262] Spring wire diameter (d5): Calculated based on the spring constant, take d5 = 8mm.

[0263] Spring middle diameter (D2): Take D2 = 28mm to ensure matching with the inner hole diameter N8 of the built-in pipe jacking device 10, with a clearance of 2mm.

[0264] Effective number of turns (n): through calculation, take n = 5 turns.

[0265] ③Length design:

[0266] Completely relaxed length (A2): 200mm, that is, the free length of the spring when it is not stressed.

[0267] Fully compressed length (A1): 50mm, which is the length of the spring when it is subjected to maximum compression force.

[0268] Working length (A3): 100mm, which is the actual working length of the spring during construction.

[0269] ④ Elastic force calculation:

[0270] Elastic force calculation formula:

[0271] F=k×(A2-A3)

[0272] Substituting the values:

[0273] F=500N / mm×(200mm-100mm)=50,000N

[0274] Ensure that the elastic force meets the requirement of pushing the pusher 18.

[0275] ⑤Fatigue life:

[0276] After special heat treatment and surface strengthening treatment, the fatigue life of the spring can reach more than 10^6 cycles, meeting the requirements of long-term use.

[0277] 6. Spring push thread device 35

[0278] (1) Material selection:

[0279] ①Use alloy steel, such as 40Cr, after quenching and tempering treatment, the surface hardness is HRC40-45, with high strength and wear resistance.

[0280] (2) Structural design:

[0281] ①External thread 22:

[0282] The thread specification is M30×1.5, and the thread length (L2) is 85 mm, which is slightly larger than the effective length (L1) 80 mm of the internal thread 9 of the built-in pipe jacking device 10, ensuring the firmness of the installation.

[0283] ②Pre-head 23:

[0284] The length (L9) is 20 mm and the diameter (D3) is Φ28 mm, and is used to compress the flat spring 24.

[0285] The front end surface is finely ground, with a roughness of Ra ≤ 0.8 μm, and pressure is applied evenly.

[0286] ③Built-in cross lock 21:

[0287] The depth (h2) is 10 mm and the width (b1) is 10 mm, which is used to insert the cross-shaped rotator 20 to achieve the tightening and loosening of the spring-pushing threaded device.

[0288] ④Surface treatment:

[0289] The threaded part is precision machined, the thread accuracy grade is 6g, the surface is smooth, and the friction resistance is reduced.

[0290] It can be nitrided to improve surface hardness and corrosion resistance.

[0291] 7. Cross rotator 20

[0292] (1) Material selection:

[0293] ① High-strength steel, such as 45 steel, is used. The handle part adopts an anti-slip design, and the surface is covered with rubber or anti-slip texture to increase grip comfort and ensure safe operation.

[0294] (2) Dimension design:

[0295] ① Adaptability: Perfectly matches the embedded cross lock 21 of the spring push thread device 35, with an insertion depth (h2) of 10 mm and a width (b1) of 10 mm.

[0296] ②Handle length (L10): 300mm, handle diameter (D4) is 20mm, which is convenient for applying sufficient torque to complete the tightening and loosening of the thread.

[0297] ③Structure: The handle adopts a "T" or "X" shape design to increase the operating arm and reduce the burden on the operator.

[0298] 2. Working Principle of the Device

[0299] 1. Initial state

[0300] (1) The fan-shaped rotary rock breaker 13 is in a retracted state, fixed to the front end of the built-in pipe jacking device 10, and the opening angle θ=0°.

[0301] (2) The flat spring 24 is completely compressed by the spring-pushing threaded device 35 to a length A1 = 50 mm, and the elastic force reaches a maximum value.

[0302] (3) The pusher 18 is located at the rearmost position of the built-in pipe jacking device 10, and its rear end surface is in contact with the flat spring.

[0303] 2. Rotation process

[0304] (1) The internal pipe jacking device 10 is connected to the drilling machine 1 through a connector and starts rotating.

[0305] (2) The rotation speed is set to n = 60 rpm, and the angular velocity ω = 2πn / 60 = 6.28 rad / s.

[0306] (3) During the rotation process, the fan-shaped rotary rock breaker 13 begins to open outwards under the action of centrifugal force.

[0307] 3. Spring release

[0308] (1) As the rotation proceeds, the flat spring 24 is restricted by the spring push screw device 35 and gradually relaxes from the fully compressed length A1 = 50 mm to the working length A3 = 100 mm.

[0309] (2) Under the thrust of the flat spring, the pusher 18 moves forward by a distance ΔL=A3-A1=50 mm.

[0310] (3) The forward movement of the thruster pushes the bottom of the fan-shaped rotary rock breaker 13, further causing it to expand outward.

[0311] 4. Cutting surrounding rock

[0312] (1) The pick head 14 on the fan-shaped rotary rock breaker 13 begins to cut the surrounding rock at the bottom and side wall of the borehole under the combined action of centrifugal force and spring thrust.

[0313] (2) The diameter of the expanded hole D = D1 + 2W1sinθ. When θ = 90°, the diameter of the expanded hole D = 42mm + 230mm = 102mm.

[0314] (3) The cutting force F_s can be estimated by the formula:

[0315]

[0316] Where: F_c is the centrifugal force; It is the front angle of the pick head, which is generally 15°.

[0317] 5.Complete hole expansion

[0318] (1) When the flat spring 24 reaches a working length A3 = 100 mm, the fan-shaped rotary rock breaker 13 is fully expanded to a maximum opening angle θ = 90°.

[0319] (2) The hole expansion process is completed, and the expected enlarged hole is formed. The bottom diameter of the hole reaches 102 mm, which meets the design requirements.

[0320] 6. Stop Spinning

[0321] (1) Gradually reduce the rotation speed of the drilling rig 1 to avoid sudden stops that may cause equipment damage or hole wall instability.

[0322] (2) Finally stop rotating and prepare for subsequent operations.

[0323] 7. Disassembly device

[0324] (1) Use the cross-shaped rotator 20 to rotate counterclockwise to loosen the spring push thread device 35 and release the residual elastic force of the flat spring.

[0325] (2) Take out the spring push thread device 35, the flat spring 24 and the pusher 18 in sequence.

[0326] (3) The fan-shaped rotary rock breaker 13 automatically retracts to its original position (θ=0°) without the action of centrifugal force and spring thrust.

[0327] (4) Slowly pull the built-in pipe jacking device 10 together with the fan-shaped rotary rock breaker 13 out of the borehole.

[0328] 3. Installation and use of the device

[0329] 1. Preparation

[0330] (1) Equipment inspection: Check the integrity of all parts, especially threads, pick heads, springs, etc., and lubricate and replace if necessary.

[0331] (2) Personnel training: Ensure that operators are familiar with the structure, working principle and operating procedures of the device and have the necessary safety knowledge.

[0332] 2. Install the fan-shaped rotary rock breaker 13

[0333] (1) Installation of the fixing pin 11: Insert the fixing pin into the hole at the front end of the built-in pipe jacking device 10 to ensure that it is firmly fixed.

[0334] (2) Installation of fan-shaped rotary rock breaker: Align the groove of the fan-shaped rotary rock breaker with the fixing pin 11, insert it into place, and check that it can rotate freely within the range of 0°-90° without any obstruction.

[0335] 3. Push in the built-in pipe jack 10

[0336] (1) Lubrication treatment: Apply a proper amount of lubricating oil or graphite powder evenly on the outer surface of the built-in pipe jacking device 10 to reduce the pushing resistance.

[0337] (2) Pushing process: Two workers hold the rear end of the built-in pipe jacking device and slowly and evenly push it into the borehole 2 until the fan-shaped rotating rock breaker 13 reaches the bottom of the borehole.

[0338] (3) Position confirmation: Ensure that the built-in pipe jacking device reaches the predetermined position through measurement or marking, with an error of no more than ±10 mm.

[0339] 4. Install the pusher 18 and the flat spring 24

[0340] (1) Thruster inspection: Ensure that the surface of the thruster is smooth, free of burrs, and that the dimensions meet the requirements.

[0341] (2) Pushing in the jacking device: Slowly push the jacking device in from the rear end of the built-in pipe jacking device until the front end surface contacts the bottom surface of the fan-shaped rotary rock breaker.

[0342] (3) Place the flat spring: Place the flat spring in the built-in pipe jacking device, behind the pusher, and ensure that the axis of the spring coincides with the axis of the built-in pipe jacking device to prevent deflection.

[0343] 5. Install the spring push thread device 35

[0344] (1) Initial screwing in: Align the outer thread of the spring-pushing threaded device with the inner thread of the built-in pipe jacking device and screw it in manually for 2-3 turns.

[0345] (2) Using a cross-shaped rotator 20: Insert the built-in cross lock and rotate it clockwise to gradually compress the flat spring until it reaches a fully compressed state (A1 = 50 mm).

[0346] (3) Fix the built-in pipe jacking device: During the tightening process, use a pipe clamp or special tools to fix the exposed part of the built-in pipe jacking device to prevent it from rotating.

[0347] 6. Connect the drilling rig 1

[0348] (1) Connection method: Use a special joint or connecting rod to connect the built-in pipe jacking device to the drilling rig to ensure that the connection is firm and reliable.

[0349] (2) Safety check: Check all connections to make sure they are not loose or damaged and that the power supply and hydraulic system are functioning properly.

[0350] 7. Start expanding the hole

[0351] (1) Rotation parameter setting: Set the appropriate rotation speed n and propulsion speed v according to geological conditions and design requirements.

[0352] (2) Start the drilling rig: Start slowly and gradually reach the set rotation speed and propulsion speed to avoid sudden acceleration that may cause equipment damage or safety accidents.

[0353] (3) Monitoring process: Operators should pay close attention to the operating status of the equipment, pay attention to signals such as sound, vibration and torque, and promptly detect and handle abnormal situations.

[0354] 8.Complete hole expansion

[0355] (1) Stop rotation: When the fan-shaped rotary rock breaker is fully deployed and the hole expansion reaches the expected effect, gradually reduce the rotation speed of the drilling rig until it stops.

[0356] (2) Checking the hole expansion effect: Use measuring tools, such as a caliper or probe, to confirm that the diameter and depth of the expanded hole meet the design requirements.

[0357] (3) Cleaning debris in the hole: Use compressed air or suction equipment to clean the debris and rock powder in the borehole to ensure that the hole is clean and ready for subsequent anchoring operations.

[0358] 9. Disassembly device

[0359] (1) Loosen the spring push thread device: Use the cross-shaped rotator to rotate counterclockwise to gradually loosen the spring push thread device and release the elastic force of the flat spring.

[0360] (2) Remove the components: Remove the spring push thread device, flat spring and pusher in turn, taking care to prevent them from falling or being damaged.

[0361] (3) Withdraw the built-in pipe jacking device and the fan-shaped rotary rock breaker: slowly pull the built-in pipe jacking device together with the fan-shaped rotary rock breaker out of the borehole, and check whether the fan-shaped rotary rock breaker returns to the retracted state.

[0362] 1. Safe operation

[0363] (1) Personal protection: Construction workers must wear protective equipment such as safety helmets, safety belts, protective gloves, protective glasses and dust masks.

[0364] (2) Operating procedures: Strictly abide by the equipment operating procedures and do not modify equipment parameters or perform illegal operations without authorization.

[0365] (3) Environmental monitoring: In tunnels with high gas concentration, gas detectors should be installed to ensure that construction is carried out within a safe range.

[0366] 2. Equipment maintenance

[0367] (1) Regular inspection: Before and after construction every day, check all parts of the equipment, especially wearing parts such as pick heads, springs, threaded parts, etc., and replace or repair them in time.

[0368] (2) Lubrication and maintenance: Threads and moving parts should be lubricated regularly to reduce wear and extend equipment life.

[0369] (3) Storage and maintenance: When the equipment is not in use, it should be properly stored in a dry and ventilated place to prevent moisture, rust or damage.

[0370] 3. Construction environment

[0371] (1) Roof support: During the construction process, the stability of the surrounding roof should be ensured. Temporary support measures such as support nets, scaffolding or temporary supports can be adopted.

[0372] (2) Temperature conditions: In a low temperature environment (below 0°C), attention should be paid to the performance changes of the equipment and the applicability of the lubricating oil, and insulation measures should be taken if necessary.

[0373] (3) Geological conditions: According to different geological conditions, adjust the construction parameters, such as rotation speed, advancement speed and expansion depth.

[0374] 4. Quality Control

[0375] (1) Construction records: Detailed records of construction parameters (such as rotation speed, propulsion speed), time, personnel, geological conditions, and other information are required to facilitate later tracing and analysis.

[0376] (2) Hole expansion effect detection: After the construction is completed, the hole diameter and depth are measured to ensure that the hole expansion effect meets the design requirements.

[0377] (3) Anchoring effect detection: After the subsequent anchoring construction is completed, a pull-out test is carried out to detect whether the anchoring force meets the design requirements.

[0378] The application effect of this embodiment:

[0379] 1. Improved anchoring force

[0380] (1) Experimental results: After the pull-out test, the anchoring force increased by about 50%, from the original 150kN to more than 225kN.

[0381] (2) Analysis: The enlarged area increases the contact area between the anchor and the surrounding rock, forming a mechanical locking effect and significantly enhancing the bonding force between the anchor (cable) and the surrounding rock.

[0382] 2. High construction efficiency

[0383] (1) Time saving: The expansion time of a single hole is about 5 minutes, which reduces the construction time by 30% compared with the traditional method.

[0384] (2) Personnel requirements: Simple operation and high degree of standardization reduce the dependence on highly skilled operators and reduce labor costs.

[0385] 3. Strong applicability

[0386] (1) Geological conditions: It is applicable to various geological conditions, especially in complex conditions such as soft rock, soft and broken coal, and aquifers, and can achieve good support effects.

[0387] (2) Scope of application: It can be used in coal mine tunnels, tunnels, underground projects and other places where the anchoring force needs to be improved.

[0388] 4. Significant economic benefits

[0389] (1) Material saving: By improving the support effect of a single anchor (cable), the number of support units can be reduced by 20%-30%, thereby reducing the overall support cost.

[0390] (2) Extended service life: The enhanced anchoring effect extends the service life of the support system, reduces the frequency of subsequent maintenance and reinforcement, and reduces long-term operating costs.

[0391] 5. Improved safety level

[0392] (1) Risk reduction: The risk of surrounding rock collapse and anchor (cable) failure is reduced, ensuring the safety of construction workers.

[0393] (2) Enhanced stability: The deformation of the tunnel is significantly reduced, the stability of the surrounding rock is effectively controlled, and the safety production level of the mine is improved.

[0394] In summary, the coal rock tunnel drilling bottom hole expansion device of the present invention significantly improves the anchoring effect and enhances the overall stability of the tunnel through innovative mechanical structure design and scientific construction methods. The device has a simple structure, convenient construction, strong adaptability, and has broad application prospects and promotion value.

[0395] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0396] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0397] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A bottom hole expansion device for coal and rock tunnel drilling, characterized in that: It comprises a built-in pipe jacking device (10), a fixing pin (11), a fan-shaped rotary rock breaker (13), a pusher (18), a flat spring (24) and a spring push thread device (35); The built-in pipe jacking device (10) is a tubular structure made of high-strength alloy steel, and its outer diameter is adapted to the borehole diameter so that it can enter the borehole and remain stable; the built-in pipe jacking device (10) has two inner holes of different diameters, namely, a rear end inner hole diameter N (8) and a front end inner hole diameter M (29), and an internal thread (9) located between the two and close to the rear end; The fixing pin (11) is arranged at the front end of the built-in pipe jacking device (10), and is made of high-strength alloy steel. A through hole (12) is provided on the top for installing a fan-shaped rotating rock breaker (13). The structure of the fixing pin (11) matches the groove of the fan-shaped rotating rock breaker (13), so that the fan-shaped rotating rock breaker (13) can rotate freely within a range of 0°-90°. The thruster (18) can be placed inside the built-in pipe jacking device (10) and located behind the fan-shaped rotating rock breaker (13). The thruster (18) is made of high-strength steel. The front end surface of the thruster (18) is in close contact with the bottom surface of the fan-shaped rotating rock breaker (13). The flat spring (24) behind the thruster (18) can push the thruster (18) to move forward so that the fan-shaped rotating rock breaker (13) can be deployed. The spring push thread device (35) is installed at the rear end of the built-in pipe jack (10), is made of alloy steel, and matches the internal thread (9). By tightening or loosening the spring push thread device (35), the compression state of the flat spring (24) can be accurately adjusted to meet different construction requirements.

2. The bottom hole expansion device for coal rock tunnel drilling according to claim 1, characterized in that: The diameter difference between the built-in pipe jacking device (10) and the borehole wall is 2-4 mm, so as to ensure that the device can smoothly enter the borehole, while maintaining good stability during the rotation and hole expansion process, avoiding shaking or deviation of the device due to excessive gap, and improving the accuracy and safety of construction.

3. The bottom hole expansion device for coal rock tunnel drilling according to claim 1, characterized in that: The diameter difference between the pusher (18) and the built-in pipe jack (10) is 0-5 mm, so that the pusher (18) can move smoothly in the built-in pipe jack (10), reduce friction resistance, avoid jamming due to too small a gap or shaking due to too large a gap, thereby ensuring the stability and efficiency of the hole expansion process.

4. The bottom hole expansion device for coal rock tunnel drilling according to claim 1, characterized in that: The inner diameter N (8) of the built-in pipe jacking device (10) is slightly larger than the inner diameter M (29), and the diameter difference between the two is 1-4 mm, which facilitates the installation and disassembly of the components, ensures the smooth installation of the pusher (18), the flat spring (24) and the spring push thread device (35) in the built-in pipe jacking device (10), and also helps to maintain the overall structural strength and stability of the device.

5. The bottom hole expansion device for coal rock tunnel drilling according to claim 1, characterized in that: The length of the external thread (22) of the spring-pushing threaded device (35) is slightly greater than the effective length of the internal thread (9) of the built-in pipe jacking device (10), thereby ensuring that the flat spring (24) can be completely compressed during the tightening process and that the firmness of the installation is guaranteed, thereby avoiding the risk of the spring-pushing threaded device (35) loosening or falling off during the construction process, and improving the reliability and safety of the device.

6. The bottom hole expansion device for coal rock tunnel drilling according to claim 1, characterized in that: The groove of the fan-shaped rotary rock breaker (13) matches the fixing pin (11) so that its maximum opening angle is 90°. Through precise mechanical matching, the fan-shaped rotary rock breaker (13) can be smoothly expanded to a designed angle under the action of rotation and centrifugal force, thereby expanding the cutting range, improving the cutting efficiency of the surrounding rock, forming a larger expansion area, and enhancing the anchoring effect.

7. The bottom hole expansion device for coal rock tunnel drilling according to claim 1, characterized in that: The distance between the thread start section of the spring-pushing threaded device (35) and the exposed surface is less than or equal to the length of the inner hole diameter N (8) of the built-in pipe jacking device (10). During the tightening process, the spring-pushing threaded device (35) can be completely embedded in the built-in pipe jacking device (10), avoiding external interference or damage due to the exposed part being too long, thereby ensuring the safety and stability of the device during the construction process.

8. The bottom hole expansion device for coal and rock tunnel drilling according to claim 1, characterized in that: The upper side and the lower side of the fan-shaped rotary rock breaker (13) are both equipped with a plurality of pick heads (14), and the pick heads (14) are made of a hard alloy material with high hardness and wear resistance, so that after the fan-shaped rotary rock breaker (13) is deployed, it can simultaneously efficiently cut the surrounding rock at the bottom and side wall of the borehole, thereby accelerating the hole expansion speed, improving the hole expansion effect, and improving the construction efficiency.

9. The bottom hole expansion device for coal rock tunnel drilling according to claim 1, characterized in that: The flat spring (24) is made of spring steel with high elasticity and high fatigue strength, has good durability and stability, can be used for multiple cycles, and prolongs the service life of the device.

10. The construction method of the bottom hole expansion device for coal-rock tunnel drilling according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1. Device assembly: Step 1.1, installation of fixing pin and fan-shaped rotary rock breaker: install the fixing pin at the front end of the built-in pipe jacking device, then align the groove of the fan-shaped rotary rock breaker with the fixing pin and install it in place to ensure that it can rotate freely; Step 1.2, installation of the thruster and flat spring: Place the thruster into the built-in pipe jacking device so that it contacts the bottom surface of the fan-shaped rotary rock breaker; then place the flat spring behind the thruster; Step 1.3, installation of the spring push thread device: screw the spring push thread device into the internal thread of the built-in pipe jacking device, and compress the flat spring to a fully compressed state; Step 2. Device installation: Slowly push the assembled reaming device into the pre-drilled hole. The outer diameter of the built-in pipe jack matches the borehole diameter to ensure that the device reaches the bottom of the hole stably. Step 3. Rotate and unfold: Step 3.1, start rotation: connect the built-in pipe jacking device to the drilling rig, start the drilling rig, and make the device start rotating; Step 3.2, expansion of the fan-shaped rotary rock breaker: under the combined action of centrifugal force and spring thrust, the fan-shaped rotary rock breaker begins to expand outward; Step 3.3, the function of the flat spring: the flat spring gradually relaxes from a fully compressed state, pushing the thruster forward and accelerating the deployment of the fan-shaped rotary rock breaker; Step 4. Cutting and expanding the hole: Step 4.1, cutting process: the pick head on the fan-shaped rotary rock breaker starts to cut the surrounding rock at the bottom and side walls of the borehole; Step 4.2, formation of an enlarged area: as the fan-shaped rotating rock breaker gradually expands to a maximum opening angle of 90°, an enlarged area with a larger diameter is formed; Step 5. Complete the hole expansion: Step 5.1, meet the design requirements: when the flat spring reaches the preset partial relaxation state, the expansion area reaches the designed size; Step 5.2, stop rotation: stop the drilling rig rotation, and the hole expansion process is completed; Step 6. Device recovery: Step 6.1, loosen the spring push thread device: Use a cross-shaped rotator to loosen the spring push thread device; Step 6.2, remove the components: remove the flat spring and the thruster in turn; since the fan-shaped rotary rock breaker loses the centrifugal force and spring thrust, it will automatically collapse; Step 6.3, removing the device: remove the built-in pipe jacking device and the fan-shaped rotary rock breaker from the borehole together.

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