Screw sleeve type water pressure maintaining multi-stage adjustable water quantity drill bit

Abstract

The utility model discloses a thread sleeve type water pressure maintaining multistage adjustable water volume drill bit, which comprises a drilling part and a connecting pipe sleeve which are coaxially connected, one end of the drilling part far away from the connecting pipe sleeve is provided with a plurality of cutting teeth and a plurality of drainage holes, the drainage holes are communicated with the inside of the connecting pipe sleeve, the drainage holes are processed into threaded holes, and the threaded holes are communicated with the connecting pipe sleeve. The drainage holes are internally connected with drainage heads in a threaded mode, through medium holes are machined in the drainage heads, a plurality of replaceable drainage heads are further arranged, the sizes of the medium holes in the drainage heads and the sizes of the medium holes in the replaceable drainage heads are different, and the drift diameters of the medium holes can be adjusted by replacing the drainage heads. Therefore, the ballast flushing water quantity can be adjusted under the condition that the water pressure is relatively constant, and the problems that the water pressure is reduced after the flushing water quantity is reduced in water-sensitive, broken and loose rock soil drilling by traditional water flushing drilling equipment, so that the drilling tool is stuck, the hole is blocked and the like due to unsmooth ballast discharging can be avoided.

Description

Technical Field

[0001] This utility model relates to the field of geotechnical construction equipment technology, specifically a screw-type drill bit with multi-stage adjustable water volume for maintaining water pressure. Background Technology

[0002] Tunnel engineering has long been an indispensable part of infrastructure such as transportation, water conservancy and hydropower, and energy. When constructing these tunnels using the TBM (Tunnel Boring Machine) method or (and) drill-and-blast method, it is inevitable to encounter unfavorable geological bodies such as weak and fractured surrounding rock, fractures and fault zones, water-rich areas, large-scale deformation of soft rock, alteration zones, and rock bursts. Geological advance prediction, advance support, advance and / or radial reinforcement and / or grouting for water plugging, and long-strength and fast anchoring are the main technical means to solve these problems. When drilling in unfavorable geological bodies, especially in water-sensitive, fractured, and loose rock and soil, the control of the flushing water volume becomes a crucial link, especially in drilling with advanced geological drilling rigs, anchor drilling rigs, and water hammer drilling rigs. Excessive flushing water volume can erode the borehole walls, damage the borehole shape, and increase the amount of rock debris to be removed. It can also lead to borehole collapse and stuck drill bits due to borehole instability. Conversely, insufficient flushing water volume can reduce flushing water pressure, affecting debris removal and potentially causing stuck drill bits and borehole blockage. Therefore, maintaining stable flushing water pressure while precisely and quickly adjusting the flushing water volume to ensure efficient and safe drilling operations is a crucial step in tunnel construction. The ability to precisely adjust the water volume under stable water pressure is not only essential for ensuring construction safety and improving project quality but also a vital means to accelerate construction progress and achieve project goals. Utility Model Content

[0003] The purpose of this invention is to address the shortcomings of existing technologies and provide a screw-type multi-stage adjustable water volume drill bit that can quickly reduce water volume without reducing water pressure during drilling by changing the drain head with different medium hole specifications.

[0004] The objective of this utility model is achieved through the following technical solution:

[0005] A screw-type multi-stage adjustable water volume drill bit for maintaining water pressure includes a drilling section and a connecting sleeve connected coaxially. The drilling section is provided with several cutting teeth and several drainage holes at the end away from the connecting sleeve. The drainage holes are connected to the inside of the connecting sleeve.

[0006] The drain head is fixedly connected to the drain hole by a threaded pin, and the drain head has an axially penetrating medium hole; the medium hole is a tapered hole, and the large-diameter end of the medium hole faces the connecting sleeve.

[0007] Preferably, the drainage head includes a screw and a screw head connected in sequence; a countersunk hole is provided at the end of the drilling part away from the connecting sleeve, and the countersunk hole is coaxially arranged with the drainage hole; the screw is threadedly connected to the drainage hole, and the screw head is circumferentially limited and embedded in the countersunk hole.

[0008] Preferably, the medium hole is located inside the screw; a hexagonal through hole is machined on the inner circumference of the screw head; the hexagonal through hole communicates with the medium hole.

[0009] Preferably, a radially penetrating pin hole A is machined on the screw head; a pin hole B is radially machined inside the countersunk hole; and a stop pin is fitted inside pin hole A and pin hole B.

[0010] The advantages and technical effects of this utility model are as follows:

[0011] This utility model discloses a screw-type multi-stage adjustable water volume drill bit for maintaining water pressure, which is an improved structure based on the existing drill bit assembly. It improves upon the existing drill bit assembly by machining the drainage hole into a threaded hole and separately machining various specifications of drainage heads. Each drainage head has a through medium hole with a different diameter. In application, the drainage head is threaded into the drainage hole, and the medium hole can replace the original drainage hole for flushing water discharge. By changing different drainage heads, the diameter of the medium hole can be adjusted. Thus, without significantly changing the water pressure, the flushing water volume can be quickly adjusted simply by changing the drainage head. This effectively addresses the challenges of existing water-flushing drilling equipment in water-sensitive altered surrounding rocks and flexibly adapts to various geological conditions. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the structure of this utility model;

[0014] Figure 2 for Figure 1 A schematic diagram of the disassembled structure;

[0015] Figure 3 This is a cross-sectional view of the drainage head in this utility model;

[0016] In the diagram, 1 is the drilling section; 2 is the connecting sleeve; 3 is the cutting tooth; 4 is the drainage hole; 5 is the medium hole; 6 is the screw; 7 is the screw head; 8 is the countersunk hole; 9 is the hexagonal through hole; 10 is the pin hole A; and 11 is the stop pin. Detailed Implementation

[0017] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0018] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0019] The present invention will now be described in further detail with reference to the accompanying drawings.

[0020] like Figures 1 to 3 As shown, a threaded sleeve type multi-stage adjustable water flow drill bit for maintaining water pressure can be manufactured by modifying an existing drill bit assembly structure. The existing drill bit assembly includes a coaxially connected drilling section 1 and a connecting sleeve 2. The drilling section 1, at its end away from the connecting sleeve 2, has several cutting teeth 3 and several drainage holes 4, which communicate with the interior of the connecting sleeve 1. Based on this, the drainage holes 4 are machined into threaded holes, and a drainage head is separately machined, threaded into the drainage hole 4. The drainage head has a through-hole 5, which replaces the original empty area inside the drainage hole 4 to allow flushing water to flow out.

[0021] The drainage head is designed to be detachable, allowing for replacement during application. Several different sizes of replacement drainage heads are also manufactured. The main drainage head and these replacement heads share the same structure, except for the diameter of the medium hole 5. By replacing different replacement drainage heads, the diameter of the medium hole 5 can be adjusted. This allows for rapid adjustment of the flushing water volume without significantly altering the water pressure, effectively addressing the challenges of existing water-flushing drilling equipment in water-sensitive altered surrounding rock operations. It also allows for flexible adaptation to various geological conditions. For example, in hard rock formations, a water hammer drill bit with a larger diameter drainage head can be selected to provide sufficient water volume and impact force to break the rock; while in water-sensitive altered surrounding rock, a water hammer drill bit with a smaller diameter drainage head can be used to ensure effective flushing while preventing borehole collapse due to excessive water volume.

[0022] Furthermore, the medium hole 5 is machined into a conical shape, with the large-diameter end of the medium hole 5 facing the connecting sleeve 2. From the perspective of fluid mechanics, the special structure of the conical hole can effectively guide the water flow, reduce turbulence, and make the water flow out of the drill bit more stable, greatly reducing the adverse effects of water flow fluctuations on drilling operations; moreover, under specific pressure conditions, the conical hole can also accelerate the water flow, increasing the speed of the water flowing out of the drill bit, thereby enhancing the impact force on the rock cuttings and improving the efficiency of cuttings removal.

[0023] In specific implementation, the drainage head includes a screw 6 and a screw head 7 connected in sequence. A countersunk hole 8 is provided at the end of the drilling section 1 away from the connecting sleeve 2. The countersunk hole 8 is coaxially arranged with the drainage hole 4. The screw 6 is threadedly connected to the drainage hole 4. The screw head 7 is located inside the countersunk hole 8, and the medium hole 5 is located inside the screw 6. A hexagonal through hole 9 is machined on the screw head 7, communicating with the medium hole 5. Using the aforementioned threaded connection method not only provides excellent mechanical strength and sealing performance but also effectively resists the impact of high-pressure water flow and severe vibration, ensuring the reliability of the connection between the drill bit and the equipment. With the aforementioned recessed design, after the drainage head is installed, the end of the drainage head is recessed into the end face of the drilling section 1, avoiding any impact on the drilling process. The hexagonal through hole 9 design allows for easy disassembly and assembly using an Allen wrench.

[0024] Furthermore, a pin hole A10 is machined in the radial direction of the screw head 7, and a pin hole B is machined in the drilling part 1. It also includes a stop pin 11. After the drain head is installed on the drilling part 1 by threaded connection, the stop pin 11 is inserted so that its two ends are respectively adapted to fit into the pin hole A10 and the pin hole B. The stop pin 11 can prevent the drain head from reversing and loosening, and ensure the stability of the equipment during operation.

[0025] In practical implementation, three specifications of drainage heads (or replacement drainage heads) were designed, with minimum end diameters of the medium orifice 5 of 2mm, 3mm, and 4mm, respectively. The 2mm small-diameter drainage head is suitable for highly water-sensitive rock formations, and its smaller outlet flow rate effectively reduces disturbance to the rock formation. The 3mm and 4mm larger-diameter drainage heads are more suitable for operations in low-water-sensitive rock formations, providing a larger water flow rate to meet construction requirements. The specific design and verification process is as follows:

[0026] Based on the fundamental principles of fluid mechanics, the flow rate calculation formula is used:

[0027]

[0028] In the specific context of this study, the formula can be reasonably simplified to:

[0029]

[0030] In the above formula, Q is the flow rate, A is the flow cross-sectional area, and C... dd is the flow coefficient, d is the orifice diameter, and P is the pressure.

[0031] In the rock mass permeability test, the water absorption per unit time of the rock mass was accurately measured using borehole injection tests. Combined with a safety factor ranging from 0.5 to 0.8, the maximum allowable flow rate Qmax was determined. Details of the key parameters corresponding to different rock strata types are shown in the table below:

[0032]

[0033] Once the rock strata type is identified, the corresponding Qmax value is selected, and then substituted into formula (1). The orifice diameter is then calculated in reverse, based on the known flow coefficient. Given that the conical orifice has the advantage of stable water flow, the flow coefficient C... d The standard value is 0.82, and the system pressure P is precisely adjusted to approximately 5 MPa via the pressure relief valve.

[0034] The specific calculations are as follows:

[0035] When Qmax=0.4L / s, P=5MPa, C d When =0.82, we can calculate d≈2.26mm using formula (1). Considering the actual engineering situation, a 2mm aperture is the most suitable.

[0036] When Qmax = 0.9 L / s, P = 5 MPa, C d When = 0.82, the calculated value is: d ≈ 3.39 mm. To meet the engineering requirements, a 3 mm hole diameter is appropriate.

[0037] When Qmax = 1.7 L / s, P = 5 MPa, C d When = 0.82, we can obtain: d≈4.66mm, and selecting a 4mm aperture is the optimal choice.

[0038] After the above optimization, the flow rate of the original diameter outlet hole is in the range of 1.5-4.5L / s, which effectively reduces the amount of flushing fluid used, significantly reduces water consumption and mud treatment costs, and avoids the risk of borehole wall morphology changes or even collapse caused by high flow rate flushing, thus providing a strong guarantee for rock engineering construction.

[0039] Flow rate and pressure analysis:

[0040] Flow rate calculation follows the formula:

[0041] Q = A·v (2)

[0042] Further derivation yields:

[0043]

[0044] In the above formula, v is the flow velocity, A is the cross-sectional area of ​​the flow path, and d is the orifice diameter.

[0045] Substitute the flow rates corresponding to different orifice sizes into formulas (2) and (3) to calculate the flow velocity:

[0046] For a 2mm orifice, the flow velocity v≈100.05m / s

[0047] For a 3mm orifice, the flow velocity v≈100.13m / s

[0048] For a 4mm orifice, the flow velocity v≈48.85m / s

[0049] The increased flow rate significantly enhances the carrying capacity for rock debris, which plays a crucial role in debris removal operations in rock engineering.

[0050]

[0051] Ignoring the viscosity and internal resistance loss of the fluid, substituting the flow velocity v of each of the above orifice diameters into (4), given that P0 is the atmospheric pressure and ρ is the density of the flushing water, the following can be calculated:

[0052] Water pressure P1 ≈ 5 MPa with a 2mm orifice diameter

[0053] The outlet water pressure P1 ≈ 5 MPa with a 3mm orifice diameter

[0054] The outlet pressure P1 of a 4mm orifice is approximately 11.9MPa.

[0055] The original outlet pressure P was in the range of 6-18MPa. After the pressure was released by the pressure relief valve, the current pressure change was small, which was sufficient to achieve the expected purpose of flushing away the rock debris and ensure the smooth progress of the project.

[0056] Under the above design, the water consumption per unit advance in highly water-sensitive formations is reduced from the traditional 4.8m. 3 / m decreased to 1.2m 3 / m, reducing flushing fluid usage, lowering water consumption and mud treatment costs, significantly reducing the collapse rate in water-sensitive surrounding rock sections, and the conical nozzle structure reduces drill bit wear rate by 60%.

[0057] This embodiment is only used to illustrate the present utility model and is not intended to limit the present utility model. Any person skilled in the art can modify and improve the patented technical solution of the present utility model by utilizing the above-disclosed technical content and concept without departing from the technical scope of the present utility model. Therefore, any modifications or equivalent substitutions made to the above embodiments based on the technical solution of the present utility model within the spirit and scope of the present utility model shall fall within the protection scope of the patented technical solution of the present utility model.

Claims

1. A screw sleeve type water pressure maintaining multi-stage adjustable water flow drill bit, comprising a drilling part and a connecting sleeve coaxially connected, the drilling part being provided with a plurality of cutting teeth and a plurality of drainage holes at an end away from the connecting sleeve, the drainage holes being in communication with the inside of the connecting sleeve, characterized in that: a drainage head is fixedly connected in the drainage hole by a threaded pin, and an axially through medium hole is formed in the drainage head; the medium hole is a taper hole, and the large diameter end of the medium hole faces the connecting sleeve.

2. A screw sleeve type water pressure maintaining multi-stage adjustable water flow drill bit according to claim 1, characterized in that, The drainage head comprises a screw rod and a screw rod head connected in sequence; a counterbore is formed at the end of the drilling part away from the connecting sleeve, and the counterbore is coaxially arranged with the drainage hole; the screw rod is threadedly connected with the drainage hole, and the screw rod head is circumferentially and limitingly embedded in the counterbore.

3. The screw sleeve type maintaining water pressure multi-stage adjustable water flow drill bit according to claim 2, characterized in that: The medium hole is arranged in the screw rod; a hexagonal through hole is formed in the inner wall of the screw rod head; the hexagonal through hole is in communication with the medium hole.

4. The screw sleeve type maintaining water pressure multi-stage adjustable water flow drill bit according to claim 2, characterized in that, A radial pin hole A is formed on the screw rod head; a pin hole B is radially formed in the counterbore; a stop pin is fittedly arranged in the pin hole A and the pin hole B.

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