A variable drill bit for pipe-roof construction

Abstract

This utility model discloses a variable drill bit for pipe jacking construction, belonging to the technical field of underground engineering construction equipment. It aims to solve problems such as the inability to recycle, inaccurate receiving end positioning, and low construction efficiency caused by the fixed diameter of traditional drill bits. It includes a spherical drill bit at the front end and foldable reaming drill bits symmetrically arranged on both sides of the spherical drill bit. The maximum unfolded diameter of the reaming drill bits is larger than the outer diameter of the pipe jacking steel pipe, and the folded diameter is smaller than the inner diameter of the pipe jacking steel pipe. The foldable reaming drill bit includes a hinged blade with carbide teeth on the cutting surface; the spherical drill bit has an asymmetrical cutting edge and is coated with a wear-resistant coating, and a spiral tube is installed at the upper end for slag removal. This drill bit can achieve multiple uses in one machine, accurately position the receiving end, and can be recycled after folding, improving construction efficiency and quality. It is suitable for various working conditions such as hard strata and concrete.

Description

Technical Field

[0001] This utility model relates to the field of underground engineering construction equipment technology, and in particular to a variable drill bit for pipe jacking construction. Background Technology

[0002] In traditional pipe jacking construction, a spiral casing approach is typically used at the starting drilling platform. The pipe jacking is performed segment by segment, involving simultaneous jacking, cutting, and slag removal, ultimately allowing the pipe jacking to overlap the receiving end's bare wall. However, due to technological limitations, if a drill bit larger than the pipe jacking diameter is used, it cannot be recycled within the pipe jacking; conversely, if a drill bit smaller than the pipe jacking diameter is used, it is difficult to directly drill a groove larger than the pipe jacking diameter into the receiving end's bare wall, resulting in inaccurate positioning of the pipe jacking at the receiving end. Relying solely on traditional drill bits and jacking thrust for receiving the pipe jacking easily leads to insufficient overall drilling directional accuracy and poor end stability, affecting construction quality and efficiency.

[0003] Therefore, this utility model proposes a variable drill bit for pipe jacking construction to solve the above-mentioned technical problems. Utility Model Content

[0004] The purpose of this invention is to provide a variable drill bit for pipe jacking construction to solve the problems of traditional drill bits being unable to be accurately positioned and having an unchangeable diameter.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] A variable drill bit for pipe jacking construction includes a spherical drill bit at the front end of the drill bit and foldable reaming drill bits symmetrically arranged on both sides of the spherical drill bit; the maximum unfolded diameter of the reaming drill bit is greater than the outer diameter of the pipe jacking steel pipe, and the folded diameter is smaller than the inner diameter of the pipe jacking steel pipe.

[0007] Furthermore, the foldable reaming drill bit includes at least two sets of hinged blades, which are connected to the side of the drill bit by pins.

[0008] Furthermore, the cutting surface of the articulated blade is provided with carbide teeth to improve cutting efficiency and wear resistance.

[0009] Furthermore, the spherical drill bit has an asymmetrical cutting edge structure on both sides, which facilitates easy entry of the tool head into the interior of the bare wall, reduces slippage, and improves maneuverability.

[0010] Furthermore, the outer surface of the spherical drill bit is covered with a wear-resistant coating, making it suitable for grinding operations on hard strata and concrete.

[0011] Furthermore, a spiral tube is installed at the upper end of the drill bit for discharging excavated soil.

[0012] Furthermore, the unfolding angle of each set of articulated blades ranges from 0° to 90°, and the diameter of the enlarged hole can be changed according to construction needs.

[0013] Furthermore, the drill bit is provided with two parallel mounting plates, which are made of high-strength alloy steel and are welded and fixed to the drill bit body; the mounting plates are provided with mounting holes, and the reaming drill bit is rotatably connected to the mounting holes through a pin.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] Achieving multiple uses with one machine: By combining a ball drill bit with a foldable reaming drill bit, it can not only grind hard strata and concrete, but also enlarge the hole diameter when reaching the receiving end, without the need to change equipment, reducing the frequency of equipment replacement and improving construction efficiency.

[0016] Precise positioning and recycling: After unfolding, the reaming drill bit can form a groove on the plain wall that is larger than the diameter of the pipe curtain, accurately positioning the receiving end of the pipe curtain; after folding, the diameter is smaller than the inner diameter of the pipe curtain, so it can be returned and recycled inside the pipe curtain, reducing construction costs.

[0017] Balancing precision and stability: The asymmetrical cutting edge design of the spherical drill bit improves maneuverability, and combined with directional drilling and pipe jacking technology, it ensures the accuracy of the pipe curtain drilling direction and enhances the stability of the end.

[0018] High adaptability: The carbide teeth and wear-resistant coating make the drill bit suitable for various formations and extend its service life. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is an overall schematic diagram of an embodiment of the present utility model;

[0021] Figure 2 , 3 This is a schematic diagram of the unfolded reaming drill bit provided in an embodiment of the present utility model;

[0022] Figure 4 A structural schematic diagram provided for an embodiment of this utility model;

[0023] Figure 5 A schematic diagram of the storage of the reaming drill bit provided in an embodiment of this utility model;

[0024] Figure 6This is a schematic diagram of the unfolded reaming drill bit provided in an embodiment of the present utility model.

[0025] The following are the labeling elements in the figure:

[0026] 1. Spherical drill bit; 2. Reamer bit; 21. Blade; 211. Carbide teeth; 22. Pin; 3. Spiral tube; 4. Pipe curtain steel pipe; 5. Mounting plate; 51. Mounting hole.

[0027] The accompanying drawings have illustrated specific embodiments of the present invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0029] To make the technical solution and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0030] Please see Figures 1-6 As shown, in traditional pipe jacking construction, a spiral casing follow-up process is usually adopted, in which the pipe jacking steel pipe 4 is pushed in section by section by jacking, cutting and slag removal. However, due to process limitations, if a drill bit larger than the pipe jacking diameter is used, it cannot be recycled inside the pipe jacking; if a drill bit smaller than the pipe jacking diameter is used, it is difficult to directly drill a groove larger than the pipe jacking diameter on the plain wall at the receiving end, resulting in the inaccurate positioning of the pipe jacking at the receiving end. Moreover, relying solely on traditional drill bits and jacking thrust to achieve reception easily leads to insufficient accuracy in the overall drilling direction of the pipe jacking and poor end stability, affecting construction quality and efficiency. This variable drill bit for pipe jacking construction is designed to solve these problems.

[0031] The variable drill bit for pipe jacking construction features an ingenious overall structural design, with all components working in tandem to achieve variable diameter and precise operation. Its front end is equipped with a spherical drill bit 1, which uses a forged high-strength alloy steel base and undergoes a precise forging process to ensure sufficient strength and toughness for drilling in complex geological formations. To improve its wear resistance, the outer surface of the spherical drill bit 1 is coated with a tungsten carbide wear-resistant coating using a supersonic flame spraying process. This coating has a Rockwell hardness of 65 or higher, allowing the spherical drill bit 1 to continuously cut high-strength concrete or moderately weathered rock layers without chipping, significantly extending its service life and making it suitable for grinding operations in hard formations and concrete. Simultaneously, the left and right cutting edges of the spherical drill bit 1 have an asymmetrical structure. This design solves the problem of directional accuracy defects, allowing the tool head to easily enter the interior of the raw wall, reducing slippage, effectively improving maneuverability, and ensuring better directional control during drilling.

[0032] On both sides of the spherical drill bit 1, symmetrically arranged are foldable reaming drill bits 2, which are the core components for achieving variable drill bit diameter. The foldable reaming drill bits 2 include at least two sets of articulated cutting inserts 21. The base material of the inserts 21 is made of heat-treated chromium-molybdenum alloy steel. After heat treatment, its tensile strength exceeds 1080 MPa, possessing extremely high strength and wear resistance, capable of withstanding the enormous impact and cutting forces during drilling. The cutting surfaces of the inserts 21 are inlaid with carbide teeth 211. The carbide teeth 211 have excellent cutting performance and wear resistance, significantly improving cutting efficiency and ensuring efficient operation in various complex formations.

[0033] The cutting tool 21 is connected to the mounting hole 51 of the mounting plate 5 via a high-strength alloy steel pin 22, forming a rotating pair. The mounting plate 5 is the load-bearing foundation of the reaming mechanism, consisting of two parallel high-strength steel plates rigidly connected to the drill bit body via bevel welding. This connection method ensures the connection strength between the mounting plate 5 and the drill bit body, preventing loosening or deformation during drilling. The mounting hole 51 is embedded with a graphite bronze self-lubricating bushing with a friction coefficient not exceeding 0.12. Even in high-pressure mud environments, this ensures smooth rotation of the cutting tool 21 and prevents excessive friction from affecting its unfolding and folding.

[0034] The dimensions of the reaming drill bit 2 are rigorously designed to precisely match the specifications of the pipe curtain steel pipe 4. When the blade 21 is fully folded, the overall envelope diameter is at least 20 mm smaller than the inner diameter of the pipe curtain steel pipe 4, which allows the drill bit to be completely contained inside the pipe curtain steel pipe 4, facilitating its movement and retrieval within the pipe curtain. When the blade 21 is extended to its 90-degree limit position, the cutting diameter exceeds the outer diameter of the pipe curtain steel pipe 4 by 30 to 100 mm. This design ensures that a sufficiently large receiving groove is ground on the bare wall at the receiving end, providing geometric space for the precise docking of the pipe curtain steel pipe 4, and also enabling the drill bit to be retrieved after operation.

[0035] At the upper end of the drill bit, a spiral tube 3 is installed. The spiral tube 3 is connected to the upper end of the drill body via a flange and is mainly used to discharge the excavated soil generated during drilling. The design of the spiral tube 3 ensures smooth discharge of excavated soil, avoiding its accumulation and ensuring drilling efficiency and construction safety.

[0036] The operation of this variable drill bit is divided into three stages, and its state transitions rely entirely on the mechanical control of the rotation direction. No additional complex control system is required, making it easy to operate and highly reliable.

[0037] During the initial drilling stage, the reamer bit 2 is in a folded and retracted position, with the entire drill bit completely contained within the pipe curtain steel pipe 4. The drive system rotates the drill bit at a speed of 80 to 120 revolutions per minute, while simultaneously applying an axial thrust of 800 to 1200 kN. At this time, the asymmetrical cutting edge of the spherical drill bit 1 continuously cuts through the soil or soft rock. Due to its unique cutting edge design, it can better control the direction during cutting and reduce deviation. The generated excavated soil is discharged backward through the spiral groove of the auger pipe 3, ensuring the smooth progress of the drilling process. Because the reamer bit 2 is constrained within the inner wall of the pipe curtain steel pipe 4, even under centrifugal force, the cutting edge 21 remains folded. This stage continues until the tip of the drill bit reaches the receiving end concrete wall.

[0038] After entering the reaming stage at the receiving end, when the drill bit reaches the receiving end wall after traversing the entire length of the pipe curtain, it continues to advance until the reaming drill bit 2 extends approximately 200 mm beyond the front end of the pipe curtain steel pipe 4. At this point, the drive system is immediately switched to counterclockwise rotation. Under the combined action of the centrifugal force generated by the rotation and the normal reaction force generated by the blade 21 contacting the concrete wall, the blade 21 rapidly unfolds, reaching a 90-degree fully unfolded state within 3 seconds. The unfolded carbide teeth 211 then grind a receiving groove with a diameter larger than the outer diameter of the pipe curtain steel pipe 4 on the plain concrete wall using a ring cutting method. This completely solves the process bottleneck that traditional small-diameter drill bits cannot form large-size receiving grooves, providing a reliable guarantee for the precise docking of the pipe curtain steel pipe 4.

[0039] During the drill bit retrieval phase, after reaming, the drive system switches back to clockwise rotation. At this time, the cutting edge 21 experiences reverse resistance from the concrete wall, and the change in rotation direction reverses the centrifugal force. Both forces together compel the cutting edge 21 to fold inward around the pin 22. Within 5 seconds, the cutting edge 21 is completely folded back to its initial retracted state, and the overall drill bit outer diameter returns to a safe size smaller than the inner diameter of the pipe jacking steel pipe 4. Subsequently, under the traction of the pipe jacking equipment, the drill bit retracts along the inner cavity of the pipe jacking steel pipe 4 back to the starting end. After simple cleaning and maintenance, it can be put into the next cycle of construction. This retrieval mechanism significantly reduces equipment investment costs compared to traditional processes.

[0040] Laboratory simulations and field engineering tests have demonstrated several significant advantages of this drill bit. In moderately weathered sandstone formations with a quartz content of 30%, the wear of the cemented carbide teeth 211 after 120 hours of continuous operation is less than 1.5 mm, exhibiting extremely strong wear resistance. The wear-resistant coating of the spherical drill bit 1 has a lifespan of 800 linear meters when grinding high-strength concrete, meeting the needs of long-term construction. The standard slot hole can be formed in only 1 to 5 minutes during the hole reaming stage at the receiving end, reducing the working time by more than 80% compared to the traditional secondary hole forming process, greatly improving construction efficiency. With the drilling measurement system, the docking deviation of the pipe curtain steel pipe 4 can meet the stringent standards of the subway protection zone, ensuring construction quality. The rotation direction control mechanism maintains a zero-failure record in 200 folding and unfolding cycle tests, demonstrating extremely high reliability.

[0041] This drill bit is particularly suitable for a variety of complex working conditions. In underground utility tunnel projects that pass under existing buildings in densely populated urban areas, it can strictly control ground disturbance and avoid affecting surrounding buildings. In river crossing projects with boulders or reinforced concrete obstacles, its powerful cutting ability can easily handle various obstacles. In the construction of tunnel connecting passages with high-strength retaining piles at the receiving end, it can accurately form receiving slots to ensure the smooth progress of construction.

[0042] Based on the core concept of this utility model, further reasonable expansions can be made. Depending on the diameter of the pipe curtain steel pipe 4, the number of blades 21 of the reaming drill bit 2 can be adjusted. For large-diameter pipe curtains, a three-piece hinged design can be adopted to enhance stability. The carbide teeth 211 can be replaced with polycrystalline diamond composite plates to adapt to highly abrasive granite formations. The spiral tube 3 can be integrated with a high-pressure water jet nozzle to loosen hard rock and improve drilling efficiency.

[0043] The innovation of this utility model lies in achieving autonomous switching of the drill bit's working state entirely through mechanical structure design. In the initial stage, the combined effect of clockwise rotation and the constraint of the inner wall of the tubular steel pipe 4 keeps the cutting blade 21 in a folded state. At the receiving end, the centrifugal force triggered by counterclockwise rotation and the cutting reaction force work together to unfold the cutting blade 21. During retrieval, the reverse mechanical effect generated by clockwise rotation ensures that the cutting blade 21 automatically resets. This purely mechanical control avoids the risk of sealing failure of the hydraulic system in harsh geological environments, while reducing manufacturing costs by more than 40%. The quantitative relationship between the unfolding angle of the cutting blade 21 and the rotational speed has been verified by dynamics. When the rotational speed is increased to 150 revolutions per minute, the unfolding time can be shortened to 1 second, but the impact load on the cutting blade 21 and the fatigue strength of the pin 22 must be balanced. Engineering applications show that in strata where silty clay and strongly weathered mudstone interbedde, the optimal rotational speed range is 100 to 120 revolutions per minute. The true innovative value of this utility model lies in providing a state-transformation mechanism that relies entirely on mechanical dynamics; this principle can be extended to the field of intelligent control of other underground engineering tools.

[0044] In summary, this variable drill bit for pipe jacking construction, through its ingenious structural design and innovative working principle, effectively solves many problems existing in traditional pipe jacking construction. It boasts significant advantages such as multi-functionality, precise positioning and retrieval, a balance between accuracy and stability, and strong adaptability, making it a promising candidate for widespread application and significant potential for promotion in the field of underground engineering construction. Its rational structural design, reliable performance, and simple operation significantly improve construction quality and efficiency while reducing construction costs, providing a novel and efficient solution for underground engineering construction.

[0045] Other embodiments of the present invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the foregoing claims.

[0046] It should be understood that this invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this invention is limited only by the appended claims.

Claims

1. A variable drill bit for pipe jacking construction, characterized in that: include A spherical drill bit (1) is located at the front end of the drill bit; A foldable reaming drill bit (2) symmetrically arranged on both sides of the spherical drill bit (1); The maximum unfolded diameter of the reaming drill bit (2) is greater than the outer diameter of the pipe curtain steel pipe (4), and the folded diameter is smaller than the inner diameter of the pipe curtain steel pipe (4).

2. The variable drill bit for pipe jacking construction according to claim 1, characterized in that: The foldable reaming drill bit (2) includes at least two sets of hinged blades (21), which are connected to the side of the drill bit by pins (22).

3. A variable drill bit for pipe jacking construction according to claim 2, characterized in that: The cutting surface of the articulated blade (21) is provided with carbide teeth (211).

4. A variable drill bit for pipe jacking construction according to claim 1, characterized in that: The upper end of the drill bit is equipped with a spiral tube (3) for slag removal.

5. A variable drill bit for pipe jacking construction according to claim 1, characterized in that: The spherical drill bit (1) has an asymmetrical cutting edge structure on both sides.

6. A variable drill bit for pipe jacking construction according to claim 2, characterized in that: The unfolding angle range of each set of hinged blades (21) is 0°-90°.

7. A variable drill bit for pipe jacking construction according to claim 1, characterized in that: The drill bit is provided with two parallel mounting plates (5), and the mounting plates (5) are provided with mounting holes (51). The reaming drill bit (2) is rotatably connected to the mounting holes (51) through a pin (22).

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