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

Abstract

The invention discloses a thread sleeve type water pressure maintaining multi-stage adjustable water quantity drill bit which comprises a drilling part and a connecting pipe sleeve which are coaxially connected, a plurality of cutting teeth are arranged at the end, away from the connecting pipe sleeve, of the drilling part, a plurality of drainage holes are formed in the end, away from the connecting pipe sleeve, of the drilling part, the drainage holes are communicated with the interior of the connecting pipe sleeve, and the drainage holes are machined into threaded holes. 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] The present invention relates to the technical field of geotechnical construction equipment, and specifically to a screw sleeve type water pressure maintaining and multi-stage water volume adjustable drill bit. Background Art

[0002] Tunnel (cave) projects have long become an indispensable part of infrastructure such as transportation, water conservancy and hydropower, and energy. Whether it is the TBM (full-face tunnel boring machine) method or (and) the drill and blast method for constructing these tunnel projects, it is inevitable to pass through or accidentally encounter poor geological bodies such as soft and broken surrounding rocks, fracture and fault zones, water-rich areas, large-value deformation of soft rocks, alteration zones, and rock bursts according to the plan. Geological advance prediction, advance support, advance and (or) radial reinforcement and (or) grouting water plugging, and long and strong quick anchors are the main technical means to solve these problems. When advanced geological drills, anchor drills, and water flushing type geotechnical drills such as hydraulic hammer drills drill holes in poor geological bodies, especially in water-sensitive, broken, and loose rock and soil drilling, the control of the flushing water volume has become a crucial link. If the flushing water volume is too large, it will not only erode the hole wall, damage the hole shape, increase the rock debris discharge, but also may cause hole collapse and drill sticking accidents due to the instability of the hole wall; while if the flushing water volume is too small, it will lead to a decrease in the flushing water pressure, affect the slag discharge effect, and may also cause problems such as drill sticking and hole plugging. Therefore, on the premise of maintaining the stability of the flushing water pressure, being able to finely and quickly adjust the flushing water volume to ensure the high efficiency and safety of the drilling operation has become a key step that must be finely operated in tunnel construction. Having the ability to finely adjust the water volume under stable water pressure conditions is not only an important guarantee for ensuring construction safety and improving project quality, but also an important way to speed up the construction progress and achieve project goals. Summary of the Invention

[0003] The purpose of the present invention is to solve the deficiencies of the prior art, and provide a screw sleeve type water pressure maintaining and multi-stage water volume adjustable drill bit, which can quickly realize the adjustment of reducing the water volume without reducing the water pressure during the drilling process by replacing the drainage heads with different medium hole specifications.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A screw sleeve type water pressure maintaining and multi-stage water volume adjustable drill bit, including a drilling part and a connecting pipe sleeve connected coaxially. One end of the drilling part away from the connecting pipe sleeve is provided with a number of cutting teeth and a number of drainage holes are opened, and the drainage holes are communicated with the inside of the connecting pipe sleeve;

[0006] The drainage holes are fixedly connected with drainage heads by internal thread pins, and an axially penetrating medium hole is opened in the drainage head; the medium hole is a tapered hole, and the large diameter end of the medium hole faces the connecting pipe sleeve.

[0007] Preferably, the drainage head includes a screw rod and a screw head connected in sequence; a counterbore is provided at one 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 to the drainage hole, and the screw head is circumferentially limited and embedded in the counterbore.

[0008] Preferably, the medium hole is arranged in the screw rod; a hexagonal through hole is machined on the inner circumference of the screw head; the hexagonal through hole is communicated 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 in the counterbore; a stop pin is fitted and penetrated in the pin hole A and the pin hole B.

[0010] The advantages and technical effects of the present invention are as follows:

[0011] A screw sleeve type water pressure maintaining multi-stage adjustable water volume drill bit of the present invention is an improved structure based on the existing drill bit assembly. The drainage hole on the existing drill bit assembly is machined into a threaded hole, and drainage heads of various specifications are separately machined. A through medium hole is machined in the drainage head, and the diameters of the medium holes in each drainage head are different. When in use, the drainage head is threadedly connected in the drainage hole, and the medium hole can replace the original drainage hole for discharging the flushing water. Thus, by replacing different drainage heads, the diameter of the medium hole can be adjusted, so that the flushing water volume can be quickly adjusted only by replacing the drainage head without significantly changing the water pressure, effectively coping with the challenges of the existing water flushing drilling equipment in the operation of water-sensitive altered surrounding rock, and flexibly coping with various geological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0013] Figure 1 is a schematic structural diagram of the present invention;

[0014] Figure 2 is Figure 1 the disassembled structural diagram of;

[0015] Figure 3 is a schematic cross-sectional structural diagram of the drainage head in the present invention;

[0016] In the figure, 1, drilling part; 2, connecting sleeve; 3, cutting teeth; 4, drainage hole; 5, medium hole; 6, screw rod; 7, screw head; 8, counterbore; 9, hexagonal through hole; 10, pin hole A; 11, stop pin. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application.

[0018] In the description of the present application, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

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

[0020] As Figures 1 to 3 shown, a screw sleeve type water pressure maintaining multi-stage adjustable water volume drill bit can be manufactured by modifying on the basis of the existing drill bit assembly structure. The existing drill bit assembly includes a drilling part 1 and a connecting pipe sleeve 2 connected coaxially. At one end of the drilling part 1 away from the connecting pipe sleeve 2, a plurality of cutting teeth 3 are provided and a plurality of drainage holes 4 are opened. The drainage holes 4 are communicated with the inside of the connecting pipe sleeve 1. On this basis, the drainage holes 4 are processed into threaded holes, and a drainage head is processed separately, so that the drainage head is threadedly connected in the drainage holes 4. A through medium hole 5 is processed in the drainage head, and the through medium hole 5 replaces the original empty area in the drainage holes 4 to enable the flushing water to flow out.

[0021] By the above setting, the drainage head is designed to be detachable, and the drainage head can be replaced during application. Specifically, a plurality of specifications of replacement drainage heads are also processed. The above-mentioned drainage head and the plurality of replacement drainage heads have the same other structures, only the aperture diameters of the medium holes 5 are different. Thus, by replacing different replacement drainage heads, the through diameter of the medium holes 5 can be adjusted, so that without significantly changing the water pressure, only by replacing the drainage head, the rapid adjustment of the flushing water volume can be realized, which can effectively cope with the challenges of the existing water flushing drilling equipment in the operation of water-sensitive altered surrounding rock, and flexibly cope with various geological conditions. For example, in the hard rock formation, a water hammer drill bit assembled with a drainage head with a larger aperture is selected to provide sufficient water volume and impact force to break the rock; while in the water-sensitive altered surrounding rock, a water hammer drill bit assembled with a drainage head with a smaller aperture is selected to avoid the collapse of the hole wall due to excessive water volume while ensuring the slag discharge effect.

[0022] Furthermore, the dielectric hole 5 is processed into a tapered hole, and the large-diameter end of the dielectric hole 5 is arranged towards the connecting pipe sleeve 2. In terms of fluid mechanics principle, the special structure of the tapered hole can effectively guide the water flow, reduce the turbulence phenomenon, make the water flow more stable when flowing out of the drill bit, and greatly reduce the adverse impact of the water flow fluctuation on the drilling operation; moreover, under specific pressure conditions, the tapered hole can also accelerate the water flow, increase the speed of the water flowing out of the drill bit, thereby enhancing the impact force on the rock debris and improving the slag discharge efficiency.

[0023] During specific implementation, the drainage head includes a screw rod 6 and a screw head 7 connected in sequence. A counterbore 8 is opened at one end of the drilling part 1 away from the connecting pipe sleeve 2. The counterbore 8 is coaxially arranged with the drainage hole 4. The screw rod 6 is threadedly connected with the drainage hole 4. The screw head 7 is arranged in the counterbore 8. The dielectric hole 5 is arranged in the screw rod 6. A hexagonal through hole 9 is processed on the screw head 7, and the hexagonal through hole 9 is communicated with the dielectric hole 5. Adopting the above-mentioned threaded connection method not only has excellent mechanical strength and sealing performance, but also can effectively resist the impact of high-pressure water flow and severe vibration, ensuring the connection reliability between the drill bit and the equipment; adopting the above-mentioned sunk design, after installing the drainage head, the end of the drainage head sinks into the end face of the drilling part 1, avoiding affecting the drilling process; designing the form of the hexagonal through hole 9 can facilitate disassembly and assembly with an internal hexagonal wrench.

[0024] Furthermore, a pin hole A10 is processed in the radial direction of the screw head 7, a pin hole B is processed on the drilling part 1, and a stop pin 11 is also included. After installing the drainage head on the drilling part 1 by threaded connection, the stop pin 11 is inserted so that its two ends are respectively fitted and inserted into the pin hole A10 and the pin hole B, and the drainage head can be prevented from reversing and loosening by the stop pin 11, ensuring the stability of the equipment during the operation process.

[0025] During specific implementation, three specifications of drainage heads (or replacement drainage heads) are designed, and the minimum end diameters of the dielectric holes 5 are 2mm, 3mm, and 4mm respectively. Among them, the 2mm small-diameter drainage head is suitable for highly water-sensitive rock formations, and its smaller outlet flow rate can effectively reduce the disturbance to the rock formation; the 3mm and 4mm larger-diameter drainage heads are more suitable for operating in low water-sensitive rock formations and can provide a larger water flow rate to meet the construction requirements. The specific design and verification process are as follows:

[0026] According to the basic principle of fluid mechanics, the flow rate calculation formula is used:

[0027]

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

[0029]

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

[0031] In the rock permeability experiment, the water absorption per unit time of the rock mass is accurately measured by means of the drilling water injection test, and the maximum allowable flow rate Qmax is determined by combining the safety factor with a value range of 0.5-0.8. The key parameters corresponding to different rock formation types are shown in the following table:

[0032]

[0033] After the rock formation type is determined, the corresponding Qmax value is selected and then substituted into formula (1) to reversely calculate the water outlet diameter in combination with the known flow coefficient. d The conventional value is 0.82, and the system pressure P is accurately adjusted to about 5MPa through the pressure relief valve.

[0034] The specific calculation is as follows:

[0035] When Qmax=0.4L / s, P=5MPa, C d =0.82, it can be deduced by formula (1) that: d≈2.26mm. Considering the actual project, 2mm aperture is the most appropriate.

[0036] When Qmax=0.9L / s、P=5MPa、C d When =0.82, it is calculated that: d≈3.39mm. In order to meet the engineering requirements, it is appropriate to select a 3mm aperture.

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

[0038] After the above optimization, the flow rate of the original aperture water hole is in the range of 1.5-4.5L / s, which effectively reduces the amount of flushing fluid, effectively reduces water resource consumption and mud treatment costs, and at the same time avoids the risk of changes in the borehole wall morphology and even collapse caused by large-flow scouring, providing strong guarantees for rock engineering construction.

[0039] Flow rate and pressure analysis:

[0040] The flow rate calculation follows the formula:

[0041] Q=A·v (2)

[0042] Further deduction yields:

[0043]

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

[0045] Precisely substitute the flow rates corresponding to different pore diameters into formulas (2) and (3) to calculate the flow velocity:

[0046] For the water outlet with a pore diameter of 2 mm, the flow velocity v ≈ 100.05 m / s

[0047] For the water outlet with a pore diameter of 3 mm, the flow velocity v ≈ 100.13 m / s

[0048] For the water outlet with a pore diameter of 4 mm, the flow velocity v ≈ 48.85 m / s

[0049] The increase in flow velocity significantly enhances the ability to carry rock debris, which plays a key role in the debris cleaning operation in rock mass engineering.

[0050]

[0051] Ignoring the viscosity of the fluid and the internal resistance loss, substitute the flow velocity v of the water outlet holes with the above-mentioned various pore 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] The water outlet pressure P1 for a 2-mm pore diameter is approximately 5 MPa

[0053] The water outlet pressure P1 for a 3-mm pore diameter is approximately 5 MPa

[0054] The water outlet pressure P1 for a 4-mm pore diameter is approximately 11.9 MPa

[0055] The original pressure P of the water outlet hole is in the range of 6 - 18 MPa. After pressure relief by the pressure relief valve, the current pressure change range is small enough 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 footage in strongly water-sensitive formations is reduced from the traditional 4.8 m 3 / m to 1.2 m 3 / m, reducing the amount of flushing fluid used, lowering the water resource consumption and the mud treatment cost. The hole collapse rate in the water-sensitive surrounding rock section is greatly reduced, and the conical nozzle structure reduces the drill bit wear rate by 60%.

[0057] This embodiment is only used to illustrate the present invention, rather than to limit the present invention. Any person skilled in the art can modify and improve the technical solution of this invention patent within the technical scope of the present invention without departing from it. Therefore, all modifications or equivalent replacements made to the above embodiments based on the technical solution of the present invention within the spirit and scope of the present invention belong to the protection scope of the technical solution of this invention patent.

Claims

1. A screw-type multi-stage adjustable water volume drill bit for maintaining water pressure, comprising a coaxially connected drilling part and a connecting sleeve, wherein the end of the drilling part away from the connecting sleeve is provided with a plurality of cutting teeth and a plurality of drainage holes, wherein the drainage holes are connected to the interior of the connecting sleeve, and characterized in that: The threaded pin in the drainage hole is fixedly connected to the drainage head, and an axially penetrating medium hole is opened in the drainage head; the medium hole is a tapered hole, and the large diameter end of the medium hole faces the connecting pipe sleeve.

2. A screw-type drill bit for maintaining water pressure and multi-stage adjustable water volume according to claim 1, characterized in that: The drainage head includes a screw and a screw head connected in sequence; a countersunk hole is provided at one end of the drilling portion away from the connecting pipe 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.

3. A screw-type drill bit for maintaining water pressure and multi-stage adjustable water volume according to claim 2, characterized in that: The medium hole is arranged in the screw rod; the inner circumference of the screw rod head is processed with a hexagonal through hole; the hexagonal through hole is connected with the medium hole.

4. A screw-type drill bit for maintaining water pressure and multi-stage adjustable water volume according to claim 2, characterized in that: The screw head is processed with a radially penetrating pin hole A; the countersunk hole is radially processed with a pin hole B; and the pin holes A and B are adapted to be penetrated with stop pins.

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