Gas-liquid synergistic anti-drag coring drill bit for glutenite cultural relic protection drilling

Abstract

The gas-liquid synergistic anti-drag coring drill bit comprises a drill bit body, bottom inclined atomization holes are evenly distributed in the bottom of the drill bit body, side face tangential air holes are formed in the side face of the drill bit body, a right-handed spiral groove and a straight groove are formed in the peripheral wall of the side edge of the drill bit body, and a ceramic coating coring pipe is arranged in the drill bit body. A top pressure relief hole is formed in the top of the ceramic coating coring pipe, a rubber damping ring is arranged on the periphery of the upper portion of the ceramic coating coring pipe, and a negative pressure dust suction opening is sleeved with the rubber damping ring. According to the gas-liquid synergistic anti-drag coring drill bit for glutenite cultural relic protection drilling, the drilling jamming risk is reduced, the core quality is improved, environmental pollution is inhibited, and energy consumption and thermal damage are optimized.

Description

Technical Field

[0001] The invention relates to a gas-liquid coordinated drag-reducing core drill bit for sandstone cultural relic protection drilling, belonging to the technical field of civil engineering and cultural relic protection engineering. Background Art

[0002] In the protection of sandstone cultural relics and geological research, obtaining complete core samples is of great significance for analyzing rock characteristics, evaluating the preservation environment of cultural relics and formulating protection measures. Traditional core drill bits have many problems in the drilling process: on the one hand, simply using high-pressure water flushing can easily lead to the accumulation of rock chips, causing drill jamming, affecting drilling efficiency. Traditional water drills in sandstone formations cause annular blockage due to poor discharge of rock chips. Statistics show that the probability of drill jamming in 10m deep holes is more than 35%; on the other hand, the lack of effective shock absorption and dust reduction measures not only causes damage to the cultural relics themselves, but also has an adverse impact on the working environment. The penetration depth of the working fluid exceeds 10mm, and visible dust (PM 10 Concentration > 150 μg / m 3 ), which does not meet the cultural relics protection standards (GB / T30688-2014). In addition, existing drill bits also have shortcomings in core protection, making it difficult to ensure the integrity of the core. Conventional drill bits have large vibrations (amplitude > 0.2mm), and the recovery rate of weakly cemented cores is less than 65%. Although the existing technology proposes a spiral chip removal groove design, it does not solve the contradiction between fluid disturbance and cultural relics protection; there is also a pure pneumatic chip removal method, but the core recovery rate is only 72% and dust diffusion cannot be controlled. The existing technology uses a fully enclosed drill bit; the existing technology mostly uses high-pressure water injection for wetting; the existing technology uses a steel pipe casing drill bit; the existing technology does not use a damping device.

[0003] The problems are as follows:

[0004] 1. Low cuttings removal efficiency: Sand and conglomerate particles have a wide distribution in particle size (0.1-50 mm). Traditional high-pressure water flushing (pressure ≥ 2.0 MPa) easily causes fine particles (<2 mm) to form mud cakes in the annulus, causing drill sticking (the probability of drill sticking in a 10 m deep hole is 35%-45%) and increasing drill withdrawal time by more than 30%.

[0005] 2. Severe core damage: Conventional steel drill bits vibrate violently (amplitude > 0.2mm), and weakly cemented gravel cores are easily shattered by mechanical impact, resulting in a recovery rate of less than 65%. Some technologies use soft liners, but these cannot balance chip removal and core protection.

[0006] 3. High risk of environmental pollution: The penetration depth of traditional working fluids (such as alkaline lubricants) is greater than 10mm, leading to chemical degradation of the rock mass; dust diffusion (PM 10 Concentration > 150 μg / m 3) exceeds the limit value (PM 10 ≤50 μg / m 3 ), threatening the cultural relics themselves and the health of the workers.

[0007] 4. Energy consumption and thermal damage: Although pure pneumatic drill bits (air pressure ≥ 1.0 MPa) can reduce liquid contamination, the chip removal energy consumption is high (power > 5 kW / m), and the drill bit temperature is > 80 ° C, which accelerates wear and causes thermal cracking of the core.

[0008] Therefore, a new type of core drill bit that can solve the above problems is urgently needed. Summary of the Invention

[0009] In view of this, in response to the problems in the background technology, the present invention proposes a gas-liquid synergistic drag-reducing core drill bit for gravel and conglomerate cultural relics protection drilling. In response to the core problems existing in gravel and conglomerate cultural relics protection drilling, such as cuttings clogging the drill, poor core integrity, working environment pollution and high energy consumption, the present invention aims to provide a high-efficiency, environmentally friendly and low-damage core drill bit technical solution. The specific goals include: (1) Reducing the risk of drill sticking: By optimizing the chip removal channel and fluid dynamics design, the drill sticking rate of 10m deep holes is reduced from more than 35% of traditional technology to ≤10%. (2) Improving core quality: The core integrity of weakly cemented gravel is increased from less than 65% to ≥85%, and the recovery rate is increased to ≥90%. (3) Suppressing environmental pollution: Dust concentration (PM 10 ) from >150 μg / m 3 Reduced to <30 μg / m 3 , the working fluid penetration depth is controlled from >10mm to ≤5mm, meeting the "GB / T 30688-2014" standard. (4) Optimize energy consumption and thermal damage: the overall energy consumption is reduced by 30%-40%, and the drill bit operating temperature is stabilized at ≤50℃ to avoid thermal damage.

[0010] The present invention solves the above technical problems through the following technical means:

[0011] The gas-liquid synergistic drag-reducing coring drill bit for sandstone cultural relic protection drilling of the present invention has the following structure: it includes a drill bit, bottom oblique atomization holes are evenly distributed on the bottom of the drill bit, side tangential air holes are provided on the side of the drill bit, right-hand spiral grooves and straight grooves are provided on the side circumferential wall of the drill bit, a ceramic-coated coring tube is provided inside the drill bit, a top pressure relief hole is provided on the top of the ceramic-coated coring tube, rubber damping rings are provided around the upper part of the ceramic-coated coring tube, and the rubber damping rings are covered with a negative pressure suction port.

[0012] The bottom oblique atomization hole has a diameter of 1-3 mm and an inclination angle of 10-30 degrees. The inclination angle is designed to allow the atomized liquid flow to cover the cutting surface of the drill bit.

[0013] The side tangential pores have an aperture of 2-4 mm and a tangential angle of 30-60°. A swirl field is formed by the tangential airflow, and the swirl speed is ≥3 m / s, which pushes the cuttings upward along a spiral trajectory to reduce annular space accumulation.

[0014] The right-handed spiral grooves and straight grooves form a chip removal channel. The right-handed spiral grooves have a width of 4-6mm and a depth of 1-3mm. The right-handed spiral grooves rotate in the same direction as the drill bit, using centrifugal force to quickly eject cuttings with a diameter greater than 2mm, at a chip removal speed of ≥0.6m / s. The straight grooves have a width of 1-3mm and are staggered with the right-handed spiral grooves to axially discharge cuttings with a diameter of ≤2mm, preventing microchip stagnation and blockage.

[0015] The core tube of the ceramic coating core tube adopts a zirconium oxide ceramic coating with a thickness of 100-300 μm, a hardness of HV1000-1400, an inner diameter of 4.0-6.0 cm, and a surface roughness Ra≤0.4 μm.

[0016] The diameter of the top pressure relief hole is 3-5 mm, and the pressure difference between the inside and outside of the drill bit is dynamically balanced to make ΔP≤0.05 MPa, thereby preventing the core from breaking due to negative pressure adsorption.

[0017] The rubber damping ring is installed on the neck of the drill bit, has a Shore hardness of 40-60A and a thickness of 2-4 cm, and reduces the vibration amplitude from 0.2 mm to ≤ 0.1 mm through a viscoelastic energy dissipation mechanism, with a vibration energy attenuation rate of ≥ 60%.

[0018] The negative pressure suction port is integrated with a high-efficiency centrifugal fan, and the air volume of the centrifugal fan is ≥30m 3 / h, the negative pressure value of the suction port is ≤-500Pa, the dust collection efficiency is greater than 95%, and the PM10 concentration in the working area is less than 30μg / m 3 .

[0019] In the reverse purge process, pause and reverse purge after drilling every 0.3-0.8m.

[0020] This patent has the following advantages: (1) Gas-liquid synergistic drag reduction system: through the mixed injection of compressed air (0.6MPa) and low-pressure water (1.2MPa) (gas-water ratio 1:5), combined with the layout design of the bottom oblique atomization holes (aperture 2mm, inclination angle 20°) and the side tangential air holes (aperture 3mm, tangential angle 45°), efficient cooling and swirl chip removal are achieved, the fluid density is reduced, and the risk of drill sticking is reduced.

[0021] (2) Optimization of graded chip removal channels: Right-handed spiral grooves (3, 5 mm wide, 2 mm deep) and straight grooves (6, 2 mm wide) work together to guide large-particle rock chips and fine chips for graded discharge, respectively, ensuring a chip removal speed of ≥0.6 m / s.

[0022] (3) Core protection structure: A ceramic-coated core tube with an inner diameter of 5.0 cm is combined with a top pressure relief hole (diameter 4 mm) to improve the core integrity (≥85%) and recovery rate (≥90%) of weakly cemented sandstone by balancing pressure and reducing vibration (amplitude ≤0.1 mm).

[0023] (4) Integrated design of vibration reduction and dust reduction: a 3cm thick rubber damping ring is installed on the drill neck, combined with a negative pressure dust suction port (dust removal efficiency > 95%) to suppress dust diffusion (PM 10 Concentration <30 μg / mL 3 ) to meet the environmental requirements for cultural relics protection.

[0024] (5) Formula of harmless working fluid: Use neutral deionized water with a pH value of 7±0.2 and 0.3% biodegradable thickener, control the working fluid penetration depth to ≤5mm, avoid chemical contamination, and comply with the "GB / T 30688-2014" standard.

[0025] The advantages of the present invention are as follows:

[0026] 1. Efficient chip removal and significantly reduced risk of drill sticking: through the air-water atomization system (air pressure 0.6MPa, water pressure

[0027] 1.2MPa, air-water ratio 1:5) and optimized chip removal channels (cooperative right-hand spiral flutes and straight flutes) achieve efficient, graded discharge of large and fine cuttings, with a chip removal speed of ≥0.6m / s, effectively preventing annular blockage. Field tests have shown that the sticking rate is reduced by over 70% compared to traditional drill bits, improving drilling efficiency by 30%.

[0028] 2. Significantly improved core integrity and recovery rate: The use of a 5.0cm inner diameter ceramic-coated coring tube with a top pressure relief hole, combined with low-speed drilling (speed ≤ 200rpm) and a reverse purge process, significantly reduces drilling vibration (amplitude ≤ 0.1mm). The integrity of weakly cemented sandstone cores is ≥ 85%, and the recovery rate is increased to over 90%, meeting the stringent requirements of cultural relic protection and geological research.

[0029] 3. Dual protection of cultural relics and working environment: through the rubber damping ring shock absorption (amplitude reduction of 50%) and negative pressure dust suction port (dust removal efficiency> 95%), the dust diffusion is effectively suppressed (PM10 concentration < 30μg / m 3 ) and the work area is dust-free. The harmless working fluid (neutral deionized water + 0.3% biodegradable thickener) controls the working fluid penetration depth to ≤ 5mm, avoiding chemical contamination and complying with the "GB / T 30688-2014" cultural relic protection standard.

[0030] 4. Energy conservation, environmental protection, and operational stability: The gas-liquid synergy system reduces fluid density and energy consumption; operating temperatures are stably controlled at ≤50°C to prevent thermal damage to the drill bit and core. Automated processes (such as back-purge and negative pressure mode switching) simplify operational steps and enhance the controllability and safety of the drilling process.

[0031] 5. Wide applicability: The drill bit structural parameters (such as chip groove layout and drag reduction device material) can be flexibly adjusted according to the strength of different rock formations and the requirements of cultural relics protection. It is suitable for the refined drilling needs of complex gravel formations and cultural relics sensitive areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The overall structure diagram of the drill bit of the present invention;

[0033] Figure 2 Top view of the drill bit structure;

[0034] Figure 3 Front view of the drill bit structure.

[0035] In the figure: 101-drill bit, 102-bottom oblique atomization hole, 103-side tangential air hole, 104-right-hand spiral groove, 105-straight groove, 201-ceramic coated core tube, 202-top pressure relief hole, 203-rubber damping ring, 204-negative pressure suction port. DETAILED DESCRIPTION

[0036] The following will be combined with specific embodiments and appendix Figure 1-3 The present invention is described in detail. The gas-liquid synergistic drag reduction coring drill bit for sandstone cultural relics protection drilling in this embodiment has the following structure: it includes a drill bit 101, bottom oblique atomization holes 102 are evenly distributed on the bottom of the drill bit 101, side tangential air holes 103 are provided on the side of the drill bit 101, right-handed spiral grooves 104 and straight grooves 105 are provided on the side circumferential wall of the drill bit 101, a ceramic coated coring tube 201 is provided inside the drill bit 101, a top pressure relief hole 202 is provided on the top of the ceramic coated coring tube 201, rubber damping rings 203 are provided around the upper part of the ceramic coated coring tube 201, and the rubber damping ring 203 is covered with a negative pressure suction port 204.

[0037] The bottom oblique atomization hole 102 has a diameter of 1-3 mm and an inclination angle of 10-30 degrees. The inclination angle is designed so that the atomized liquid flow covers the cutting surface of the drill bit.

[0038] The side tangential air holes 103 have an aperture of 2-4 mm and a tangential angle of 30-60°. The tangential airflow forms a swirl field with a swirl speed of ≥3 m / s, pushing the cuttings upward along a spiral trajectory to reduce annular space accumulation.

[0039] The right-handed spiral groove 104 and the straight groove 105 form a chip removal channel: the groove width of the right-handed spiral groove 104 is 4-6mm and the depth is 1-3mm. The rotation direction of the right-handed spiral groove 104 is consistent with the rotation direction of the drill bit. The centrifugal force is used to quickly throw out the rock chips with a diameter of more than 2mm, and the chip removal speed is ≥0.6m / s. The width of the right-handed spiral groove 104 is 1-3mm. The straight groove 105 and the right-handed spiral groove 104 are staggered and are used for the axial discharge of rock chips with a diameter of ≤2mm to prevent micro-chips from being retained and blocked.

[0040] The ceramic-coated core tube 201 is coated with zirconium oxide ceramics with a thickness of 100-300 μm, a hardness of HV1000-1400, an inner diameter of 4.0-6.0 cm, and a surface roughness of Ra≤0.4 μm.

[0041] The diameter of the top pressure relief hole 202 is 3-5 mm, and the pressure difference between the inside and outside of the drill bit is dynamically balanced to make ΔP≤0.05 MPa, thereby preventing the core from being broken due to negative pressure adsorption.

[0042] The rubber damping ring 203 is installed on the neck of the drill bit 101, has a Shore hardness of 40-60A and a thickness of 2-4 cm, and reduces the vibration amplitude from 0.2 mm to ≤ 0.1 mm through a viscoelastic energy dissipation mechanism, with a vibration energy attenuation rate of ≥ 60%.

[0043] The negative pressure suction port 204 is integrated with a high-efficiency centrifugal fan, and the air volume of the centrifugal fan is ≥30m 3 / h, the negative pressure value of the suction port is ≤-500Pa, the dust collection efficiency is greater than 95%, and the PM10 concentration in the working area is less than 30μg / m 3 .

[0044] Example 1

[0045] The drill bit 101 of the present invention has a size of 55×300 mm and a structural design as follows:

[0046] 1. Air-water atomization system:

[0047] (1) Mixed injection: Compressed air (0.6MPa) and low-pressure water (1.2MPa) are mixed and injected, with a volume ratio of air to water of 1:5. This ratio is optimized through fluid mechanics simulation to ensure that the atomized droplet size is ≤50μm and the fluid density is reduced to 0.8g / cm 3 (Traditional water-based fluids are 1.0 g / cm 3 ), reducing the resistance of rock cuttings suspension.

[0048] (2) Nozzle layout:

[0049] ① Bottom inclined atomization holes 102: Four atomization holes with a diameter of 2 mm and an inclination angle of 20° are evenly distributed on the bottom of the drill bit. The inclination angle design allows the atomized liquid flow to cover the cutting surface of the drill bit, improving the cooling efficiency by 40% while avoiding direct impact on the core.

[0050] ② Side tangential air holes 103: Three groups of air holes with a diameter of 3 mm and a tangential angle of 45° are set on the side of the drill bit. The tangential airflow forms a swirl field (swirl speed ≥ 3 m / s), pushing the cuttings upward along a spiral trajectory to reduce annular accumulation.

[0051] 2. Drill bit structure optimization:

[0052] (1) Chip removal channel:

[0053] ① Right-hand spiral groove 104: The three spiral grooves are 5mm wide and 2mm deep. The right-hand design (consistent with the drill bit rotation direction) uses centrifugal force to quickly eject large rock cuttings (>2mm), with a chip removal speed of ≥0.6m / s.

[0054] ② Straight groove 105: 6 straight grooves with a width of 2mm are staggered with spiral grooves, which are specially used for the axial discharge of fine chips (less than 2mm) to prevent fine chips from being retained and blocked.

[0055] (2) Core protection:

[0056] ① Ceramic-coated coring pipe 201: The coring pipe with an inner diameter of 50 mm adopts zirconium oxide ceramic coating (thickness 200 μm), with a hardness of HV1200 and wear resistance 5 times that of traditional steel pipes. The surface roughness Ra ≤ 0.4 μm reduces core friction damage.

[0057] ② Top pressure relief hole 202: The 4mm diameter pressure relief hole is located at the top of the core tube. It prevents the core from rupturing due to negative pressure adsorption by dynamically balancing the pressure difference between the inside and outside of the drill bit (ΔP≤0.05MPa).

[0058] 3. Special design for cultural relics protection:

[0059] (1) Vibration reduction and dust suppression:

[0060] ① Rubber damping ring 203: A natural rubber damping ring (Shore hardness 50A, thickness 30mm) is installed on the drill neck to reduce the vibration amplitude from 0.2mm to ≤0.1mm through the viscoelastic energy dissipation mechanism, and the vibration energy attenuation rate is ≥60%.

[0061] ② Negative pressure suction port 204: integrated high-efficiency centrifugal fan (air volume ≥ 30m 3 / h), the negative pressure value of the suction port is -500Pa, the dust collection efficiency is greater than 95%, and the PM 10 Concentration <30 μg / mL 3 .

[0062] (2) Harmless working fluid:

[0063] ① Neutral deionized water: conductivity ≤ 1μs / cm, pH 7±0.2, to avoid chemical degradation of the rock mass caused by ion exchange.

[0064] ② Biodegradable thickener: Adding 0.3% hydroxypropyl guar gum (HPG) increases the viscosity to 15mPa·s, enhances the chip-carrying capacity, and at the same time, the natural degradation rate within 28 days is ≥90%.

[0065] (2) Key parameters

[0066]

[0067]

[0068] (3) Implementation process

[0069] 1. Start the air-water mixing system, connect the air compressor and water pump, set the air pressure to 0.6MPa, the water pressure to 1.2MPa, and the air-water mixing ratio to 1:5; calibrate the negative pressure vacuum system to ensure that the fan air volume is ≥30m 3 / h, negative pressure value -500Pa.

[0070] 2. Open the hole at low speed, with initial speed ≤200rpm and axial pressure ≤5kN to avoid instantaneous impact on the core barrel.

[0071] 3. Dynamic drainage: after drilling 0.5m, pause and blow in the reverse direction for 10 seconds (air pressure 0.8MPa) to remove residual rock chips in the spiral groove.

[0072] 4. Switch to negative pressure mode before lifting the drill to remove residual dust at the bottom of the hole.

[0073] 5. After the core tube is taken out, it should be immediately sealed in a humidity control box (RH 50% ± 5%) to prevent environmental oxidation.

[0074] (IV) Effect estimation

[0075] 1. The drill sticking rate is reduced by 70%.

[0076] 2. Core integrity ≥ 85%.

[0077] 3. There is no visible dust in the working area.

[0078] Example 2

[0079] At the gravel and conglomerate cultural relic protection drilling site, an air compressor and a water pump are connected to the top of the drill bit 101 to provide a low-density solution, and the core drill bit of the present invention is installed on the drilling rig. During the drilling process, a mixed fluid with an air pressure of 0.6 MPa and a water pressure of 1.2 MPa is provided by the air-water mixing system, with an air-water ratio of 1:5. The bottom oblique atomization hole 102 is used to cool the drill bit, and the side tangential air holes 103 form an ascending vortex to remove chips. The right-handed spiral groove 104 and the straight groove 105 work together to guide the discharge of large-particle rock chips and fine chips. The ceramic-coated core tube 201 and the top pressure relief hole 202 are used to protect the core and balance the pressure. The rubber damping ring 203 and the negative pressure suction port 204 are used to reduce vibration and dust, ensuring that there is no visible dust in the working area. The use of neutral deionized water and biodegradable thickeners ensures that the working fluid is harmless to cultural relics. By precisely controlling the parameters, damage to the gravel can be effectively reduced, meeting the requirements of cultural relic protection. After actual operation, the drill bit of the present invention was used to successfully drill a core sample with a length of about 10m in sandstone, the sampling efficiency was improved by 30%, and the integrity of the core was well maintained, meeting the requirements of cultural relics protection projects and geological research.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. Gas-liquid synergistic drag reduction core drill bit for sandstone cultural relic protection drilling, characterized by: The invention comprises a drill bit (101), wherein bottom oblique atomization holes (102) are evenly distributed on the bottom of the drill bit (101), and side tangential air holes (103) are provided on the side of the drill bit (101); a right-handed spiral groove (104) and a straight groove (105) are provided on the side peripheral wall of the drill bit (101); a ceramic coating core tube (201) is provided inside the drill bit (101), and a top pressure relief hole (202) is provided on the top of the ceramic coating core tube (201); a rubber damping ring (203) is provided around the upper part of the ceramic coating core tube (201), and the rubber damping ring (203) is covered with a negative pressure dust suction port (204); a low-speed drilling process is adopted during the drilling process, the drill bit speed is ≤200rpm, and a reverse purge process is performed every set drilling depth, the reverse purge air pressure is 0.6-1.0MPa, and the purge time is 5-15 seconds.

2. The gas-liquid synergistic drag-reducing core drill bit for sandstone cultural relic protection according to claim 1, characterized in that: The bottom oblique atomization hole (102) has a hole diameter of 1-3 mm and an inclination angle of 10-30 degrees. The inclination angle is designed so that the atomized liquid flow covers the cutting surface of the drill bit.

3. The gas-liquid synergistic drag-reducing core drill bit for sandstone cultural relic protection according to claim 1, characterized in that: The side tangential air holes (103) have an aperture of 2-4 mm and a tangential angle of 30-60 degrees. A swirl field is formed by the tangential airflow, and the swirl speed is ≥3 m / s, pushing the cuttings upward along a spiral trajectory to reduce annular space accumulation.

4. The gas-liquid synergistic drag-reducing core drill bit for sandstone cultural relic protection according to claim 1, characterized in that: The right-handed spiral groove (104) and the straight groove (105) form a chip discharge channel. The right-handed spiral groove (104) has a groove width of 4-6 mm and a depth of 1-3 mm. The rotation direction of the right-handed spiral groove (104) is consistent with the rotation direction of the drill bit. The rock chips with a diameter greater than 2 mm are quickly thrown out by centrifugal force. The chip discharge speed is greater than or equal to 0.6 m / s. The width of the straight groove is 1-3 mm. The straight groove (105) and the right-handed spiral groove (104) are staggered and distributed, and are used for axial discharge of rock chips with a diameter less than or equal to 2 mm to prevent micro-chips from being retained and blocked.

5. The gas-liquid synergistic drag-reducing core drill bit for sandstone cultural relic protection according to claim 1, characterized in that: The ceramic coating core tube (201) adopts a zirconium oxide ceramic coating with a thickness of 100-300 μm, a hardness of HV1000-1400, an inner diameter of 4.0-6.0 cm, and a surface roughness Ra≤0.4 μm.

6. The gas-liquid synergistic drag-reducing core drill bit for sandstone cultural relic protection according to claim 1, characterized in that: The diameter of the top pressure relief hole (202) is 3-5 mm, and the pressure difference between the inside and outside of the drill bit is dynamically balanced to make ΔP≤0.05 MPa, thereby preventing the core from being broken due to negative pressure adsorption.

7. The gas-liquid synergistic drag-reducing core drill bit for sandstone cultural relic protection according to claim 1, characterized in that: The rubber damping ring (203) is installed on the neck of the drill bit (101), has a Shore hardness of 40-60A and a thickness of 2-4 cm, and reduces the vibration amplitude from 0.2 mm to ≤ 0.1 mm through a viscoelastic energy dissipation mechanism, with a vibration energy attenuation rate of ≥ 60%.

8. The gas-liquid synergistic drag-reducing core drill bit for sandstone cultural relic protection according to claim 1, characterized in that: The negative pressure dust suction port (204) is integrated with a high-efficiency centrifugal fan, and the air volume of the centrifugal fan is ≥30m 3 / h, the negative pressure value of the suction port is ≤-500Pa, the dust collection efficiency is >95%, and the PM 10 Concentration <30 μg / mL 3 .

9. The gas-liquid synergistic drag-reducing core drill bit for sandstone cultural relic protection according to claim 1, characterized in that: In the reverse purge process, the drilling is paused and reverse purge is performed after drilling 0.3-0.8 m.

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