Rotary drilling machine shell type drill bit and manufacturing method thereof

Abstract

This invention discloses a shell-type drill bit for rotary drilling rigs and its manufacturing method. The drill bit body consists of four independently opening and closing shell-like lobes, each controlled by a micro hydraulic cylinder. An arc-shaped scraper is provided on the inner side of the upper section of each lobe, and alloy teeth are inlaid on the outer side of the lower section. The manufacturing method involves high-penetration welding, stress-relieving heat treatment, and high-temperature protective brazing. Compared with existing technologies, this invention solves the problems of hole collapse in soft soil and low drilling efficiency in hard rock in traditional construction, as well as high drill bit wear and frequent drill bit replacements, by precisely controlling the opening and closing state of the shell-like lobes and optimizing the structural design. It achieves efficient, high-quality, and low-cost continuous drilling in alternating soft and hard strata, significantly improving overall construction benefits.

Description

Technical Field

[0001] This invention relates to the field of rotary drilling rig construction technology, and in particular to a shell-type drill bit for rotary drilling rigs and its manufacturing method. Background Technology

[0002] When encountering layered strata of soft soil above and hard rock below during rotary drilling, the unstable wall in the soft soil section is prone to collapse, while the resistance in the hard rock section is relatively high, resulting in the following disadvantages: 1. Equipment wear and tear increased dramatically The hard rock at the bottom (compressive strength often exceeds 100MPa) causes a sudden increase in the load on the drilling tools. Ordinary bucket teeth will crack in 1-2 holes, alloy teeth in the core tube are prone to falling off, and drill pipe joints are prone to stripping. The hydraulic system operates at high pressure (over 30MPa) for a long time, and the oil temperature exceeds 65℃, causing the seals to age and the pump body to burn out. Vibration of the machine body can also cause structural fatigue.

[0003] 2. Construction efficiency plummeted The drilling speed in soft soil sections is 10-20 m / h, while in hard rock sections it is only 0.5-2 m / h, resulting in an efficiency drop of over 90%, and frequent drilling and slag removal are required. In soft soil, hole collapse requires 4-8 hours of backfilling and re-drilling, and each drill bit switching takes 30-60 minutes, which seriously delays the project schedule.

[0004] 3. Drilling quality out of control Hard rock with an inclined rock surface can easily cause the drill rod to deviate, resulting in a hole verticality exceeding the standard (≤1 / 100). In soft soil sections, it can also form a "pear-shaped hole". Hard rock cuttings have large particle sizes (5~20mm), and low-viscosity mud is difficult to suspend in soft soil sections, so the sediment at the bottom of the hole can easily exceed 50mm. Vibration in hard rock can damage the mud skin on the hole wall in soft soil, causing the hole to shrink or collapse, and creating a hidden danger of broken piles.

[0005] 4. Construction costs surge The cost of drilling tools for a single pile in hard rock reaches 2,000 to 3,000 yuan, which is 3 to 4 times higher than that in soft soil; the additional cost of equipment maintenance and hole collapse treatment per hole is 5,000 to 10,000 yuan; delays in the construction period may result in late payment penalties, and if the hole does not meet the standards, additional piles need to be added, which costs 1.5 to 2 times that of the original pile. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a shell-type drill bit for rotary drilling rigs and its manufacturing method. The drill bit body is composed of four independently openable and closable shell flaps. By precisely controlling the opening and closing state of the shell flaps and optimizing the structural design, the cutting resistance in soft soil sections is effectively reduced, the cutting ability in hard rock sections is improved, and construction quality and efficiency are ensured while reducing construction costs.

[0007] To achieve this technical objective, the present invention adopts the following solution: In a first aspect, the present invention provides a shell-type drill bit for a rotary drilling rig, wherein the main body of the drill bit is hinged with four independently openable shell flaps, each shell flap being controlled by a micro hydraulic cylinder; an arc-shaped scraper is provided on the inner side of the upper section of the shell flap, and alloy teeth are inlaid on the outer side of the lower section.

[0008] Furthermore, the main body of the shell petals is made of Q690 high-strength low-alloy structural steel; the alloy teeth are made of YG15 hard alloy with a cobalt content of 15%; the cylinder body of the miniature hydraulic cylinder is made of 27SiMn alloy structural steel, and the inner wall is chrome-plated.

[0009] Furthermore, the edge of the arc-shaped scraper is set with a 15° acute angle, and the distance between adjacent scrapers is 8~12cm.

[0010] Furthermore, the alloy teeth have a conical structure, and the spacing between the alloy teeth is 30~60mm, preferably 50mm.

[0011] Secondly, the present invention provides a method for manufacturing a shell-type drill bit for a rotary drilling rig, comprising the following steps: Shell flap welding: The shell flap body is welded by narrow gap submerged arc welding, and the weld penetration reaches more than 2 / 3 of the material thickness. After welding, it is subjected to stress relief heat treatment at 600~650℃ and held for 120~150min. Alloy tooth inlay: Apply high-temperature brazing material with a melting point of 850~900℃ to the pre-set holes of the shell petals, insert the alloy teeth, and then place them in an inert gas protective furnace to heat at 950~1000℃ and hold for 30~40 minutes to make the bonding strength reach more than 200MPa. Assembly and debugging: After the components are manufactured, they are assembled as a whole. After assembly, a hydraulic system pressure holding test of 35~40MPa is carried out. Then, simulated soft soil conditions and hard rock conditions are tested for drilling, and the parameters are adjusted so that the drilling speed in the soft soil section reaches 15~25m / h and the drilling speed in the hard rock section reaches 3~5m / h. On-site operation and maintenance: Regularly inspect the seals and wear-resistant layers, and replace the steel plates or liners as needed based on wear; record the number of operations and abnormalities for maintenance reference.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: Excellent wall protection effect: Through the design of low-speed, controllable opening and closing shell flaps and inner arc scraper, the disturbance to the soft soil borehole wall is greatly reduced, and the mud skin damage rate of mud wall protection is reduced from the traditional 35% to less than 5%, effectively preventing borehole collapse.

[0013] Highly efficient continuous drilling: Enables "one-drill-through" operation, eliminating the need to change drill bits at the interface between soft soil and hard rock strata. The hydraulic system automatically adjusts the opening and closing speed of the shell flaps in soft soil sections and the opening and closing speed in hard rock sections, allowing the drill bit to adapt to changes in strata and significantly improving drilling efficiency. Drilling speeds can reach 15~25m / h in soft soil sections and 3~5m / h in hard rock sections.

[0014] Significantly reduce costs: Consumable costs: The lifespan of carbide teeth is 8 to 10 times that of traditional bucket teeth, and the cost of consumables for a single pile drilling tool can be reduced from 2,000 to 3,000 yuan to 800 to 1,200 yuan, a reduction of about 60%.

[0015] Maintenance costs: Optimized material and structural design reduced the overall drill bit failure rate from 22% to below 3%, resulting in a 75% reduction in equipment maintenance costs.

[0016] Hole cleaning and construction period cost: The efficient sediment treatment structure keeps the sediment at the bottom of the hole stable within 20mm, saving 800-1500 yuan per hole cleaning cost; the effective operating time of the equipment is extended from 8-10 hours / day to 12-14 hours / day, shortening the construction period and avoiding late payment penalties.

[0017] Overall, the construction cost of a single project can be reduced by 25%-35%. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the shell-type drill bit structure in an embodiment of the present invention.

[0019] Figure 2 This is a front view of a shell-type drill bit in an embodiment of the present invention.

[0020] Figure 3 This is a left view of a shell drill bit in an embodiment of the present invention.

[0021] Figure 4 This is a top view of a shell-type drill bit in an embodiment of the present invention.

[0022] The markings in the image are: 1. Shell petals; 2. Arc-shaped scraper; 3. Alloy teeth. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0024] Please see Figures 1 to 4 The present invention provides a shell-type drill bit for rotary drilling rig. The drill bit body is hinged with four independently openable shell petals 1, each shell petal 1 being controlled by a micro hydraulic cylinder. The shell petal 1 is divided into upper and lower sections. An arc-shaped scraper 2 is provided on the inner side of the upper section, and an alloy tooth 3 is inlaid on the outer side of the lower section.

[0025] In one specific embodiment, the main material of the shell petal 1 is Q690 high-strength low-alloy structural steel, which balances toughness and wear resistance; the alloy teeth 3 are made of YG15 cemented carbide with a cobalt content of 15%, which has high bending strength and is resistant to cracking; the cylinder body of the miniature hydraulic cylinder is made of 27SiMn alloy structural steel, and the inner wall is chrome-plated to improve pressure resistance and wear resistance. The material selection balances the toughness of the soft soil section and the wear resistance of the hard rock section while reducing the cost of drilling tool materials.

[0026] In one specific embodiment, the edge of the arc-shaped scraper 2 is provided with a 15° acute angle, and the scraper spacing is 8~12cm. The acute angle design can reduce cutting resistance, and the reasonable spacing can prevent excessive adhesion of soft soil. The alloy teeth 3 have a conical structure, and the spacing between the alloy teeth 3 is 30~60mm, preferably 50mm.

[0027] The present invention relates to a method for manufacturing a shell-type drill bit for a rotary drilling rig, comprising the following steps: Shell flap 1 welding: The shell flap 1 body adopts narrow gap submerged arc welding to ensure that the weld penetration reaches more than 2 / 3 of the material thickness. After welding, it undergoes stress relief heat treatment at 600~650℃ and is held for 120~150 minutes to eliminate welding internal stress and avoid problems such as stripping or cracking of drill pipe joints during subsequent use.

[0028] Alloy tooth 3 inlay: Apply high-temperature brazing material with a melting point of 850~900℃ to the pre-set hole of shell petal 1, insert alloy tooth 3, and then place it in an inert gas protective furnace to heat at 950~1000℃ and hold for 30~40 minutes to make the bonding strength reach more than 200MPa, so as to prevent alloy tooth 3 from falling off during hard rock drilling.

[0029] Assembly and Debugging: After the components are manufactured, the entire assembly is performed. After assembly, a 35~40MPa hydraulic system pressure test is conducted to ensure no leakage. Then, simulated drilling under soft soil and hard rock conditions are performed, and parameters are adjusted to achieve a drilling speed of 15~25m / h in soft soil sections and 3~5m / h in hard rock sections to ensure performance meets standards.

[0030] On-site operation and maintenance: Regularly inspect the seals and wear-resistant layers, and replace the steel plates or liners as needed based on wear; record the number of operations and abnormalities for maintenance reference.

[0031] The working principle of the shell-type drill bit of the rotary drilling rig of this invention is as follows: Operating principle in soft soil sections: When the drill bit enters the upper soft soil layer, the main control system of the drilling rig sends a command to the micro hydraulic cylinder, controlling the shell flaps to open and close 1-2 times per revolution at a 15° acute angle. At this time, the arc-shaped scraper 2 on the inner side of the upper section of the shell flap 1 cuts into the soft soil as the drill bit rotates. The 15° acute angle edge reduces cutting resistance, and the 8-12cm scraper spacing prevents excessive adhesion of soft soil. Simultaneously, the low-speed opening and closing action reduces the impact and disturbance to the soft soil borehole wall, and together with the drilling mud, a stable mud cake is formed on the borehole wall, achieving wall stability and preventing borehole collapse. The soft soil debris generated during cutting is collected as the shell flap 1 opens and closes. During drill lifting, the arc-shaped scraper 2 has good capacity to contain the debris, preventing it from scattering during the lifting process, thus efficiently completing the soil extraction operation in the soft soil section.

[0032] Hard rock section operation principle: After the drill bit enters the lower hard rock strata, the main control system adjusts the hydraulic parameters, controlling the shell flap 1 to open and close 3-5 times per 60° rotation, ensuring that the carbide teeth 3 fully cut into the rock. The conical carbide teeth 3 on the outer side of the lower section of shell flap 1 can accurately cut into the hard rock under the dual action of high-speed rotation and opening and closing impact. Its high bending strength can effectively prevent tooth breakage. The 50mm tooth spacing design can achieve uniform cutting of hard rock, reduce local resistance concentration, and thus improve overall drilling efficiency. At the same time, the shell flap 1 body, made of Q690 steel, can stably withstand the vibration and load generated during hard rock cutting due to its excellent high hardness and toughness, preventing fatigue damage to the structure due to long-term stress and ensuring continuous and stable operation.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: In soft soil strata operations, this invention effectively reduces borehole wall disturbance in soft soil sections through the combination design of low-speed opening and closing shell flaps 1 and internal arc-shaped scrapers 2. The mud skin damage rate of mud slurry wall protection is reduced from 35% of traditional drill bits to below 5%, effectively avoiding borehole collapse accidents.

[0034] Traditional construction methods require separate switching between "soft soil bucket" and "rock bucket" for soft soil and hard rock, respectively. Each switching operation takes 30-60 minutes and is prone to rework due to misjudgment of the formation interface. This invention, through its axial segmented functional design and hydraulically controllable opening and closing structure, can complete continuous "soft soil-hard rock" operations without changing drilling tools. It is adaptable to formations with compressive strength ranging from soft soil to hard rock, achieving "one-drill-through" construction.

[0035] In hard rock operations, the service life of YG15 carbide teeth 3 is 8 to 10 times that of traditional bucket teeth. Traditional drill bits need to be replaced every 3 to 5 meters of drilling, while the drill bit of this invention can drill continuously for 30 to 40 meters without maintenance. The cost of consumables for a single pile drilling tool is reduced from 2,000 to 3,000 yuan to 800 to 1,200 yuan, a reduction of 60% in consumable costs. At the same time, the design of the shell-shaped body 1 made of Q690 high-strength low-alloy structural steel and the chrome-plated hydraulic cylinder reduces the overall failure rate of the drill bit from the traditional 22% to below 3%, reducing equipment maintenance costs by 75%. Moreover, it eliminates the need for frequent downtime for maintenance, extending the effective daily working time of the drilling rig from the traditional 8 to 10 hours to 12 to 14 hours. In addition, the efficient sediment treatment structure keeps the sediment thickness at the bottom of the hole stable within 20mm, eliminating the need for additional hole cleaning procedures and saving 800 to 1,500 yuan in hole cleaning costs per hole. Combined with the indirect benefits such as equipment idle fees and avoidance of late payment penalties brought about by the shortened construction period, the overall cost of a single project can be reduced by 25% to 35%.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should all be considered to be within the protection scope of the present invention.

Claims

1. A shell-type drill bit for a rotary drilling rig, characterized in that, The drill bit body is hinged with four independently openable shell flaps (1), each shell flap (1) is controlled by a micro hydraulic cylinder; the upper inner side of the shell flap (1) is provided with an arc-shaped scraper (2), and the lower outer side is inlaid with alloy teeth (3).

2. The shell-type drill bit for rotary drilling rigs according to claim 1, characterized in that, The main material of the shell petal (1) is Q690 high-strength low-alloy structural steel; the alloy tooth (3) is YG15 hard alloy with a cobalt content of 15%; the cylinder body of the micro hydraulic cylinder is made of 27SiMn alloy structural steel and the inner wall is chrome plated.

3. The shell-type drill bit for rotary drilling rigs according to claim 1, characterized in that, The edge of the arc-shaped scraper (2) is set with a 15° acute angle, and the distance between adjacent scrapers is 8~12cm.

4. The shell-type drill bit for rotary drilling rigs according to claim 1, characterized in that, The alloy teeth (3) have a conical structure and the spacing between the alloy teeth (3) is 30~60mm.

5. A method for manufacturing a shell-type drill bit for a rotary drilling rig as described in any one of claims 1-4, characterized in that, Includes the following steps: Shell petal (1) welding: The shell petal (1) body adopts narrow gap submerged arc welding, the weld penetration reaches more than 2 / 3 of the material thickness, and after welding, it undergoes stress relief heat treatment at 600~650℃ and is kept at 120~150min. Alloy teeth (3) Inlay: Apply high-temperature brazing material with a melting point of 850~900℃ to the pre-set hole of the shell petal (1), embed the alloy teeth (3), and then place it in an inert gas protection furnace at 950~1000℃ for heating and holding for 30~40 minutes to make the bonding strength reach more than 200MPa; Assembly and debugging: After the components are manufactured, they are assembled as a whole. After assembly, a hydraulic system pressure holding test of 35~40MPa is carried out. Then, simulated soft soil conditions and hard rock conditions are tested for drilling, and the parameters are adjusted so that the drilling speed in the soft soil section reaches 15~25m / h and the drilling speed in the hard rock section reaches 3~5m / h. On-site operation and maintenance: Regularly inspect the seals and wear-resistant layers, and replace the steel plates or liners as needed based on wear; record the number of operations and abnormalities for maintenance reference.

Images