A percussion drill bit assembly for mining

Abstract

The application discloses a mine impact rock drilling drill bit assembly, which comprises a drill bit body, the drill bit body is divided into a head section and a tail section which are integrally formed along an axial direction, an end surface of the head section is an operation surface directly contacting with rocks, an outer periphery of the tail section is provided with an external thread for connecting a drill rod, a center column tooth hole and an edge column tooth hole located at the periphery of the center column tooth hole are formed in the end surface of the head section, a center column tooth is fixedly connected in the center column tooth hole, an edge column tooth is slidably inserted into the edge column tooth hole, a buffer cavity extending inward along the axial direction is formed at the center of the hole bottom of the edge column tooth hole, a buffer piece is contained in the buffer cavity, a butt hard block abuts against the end surface of the buffer piece, a cross-shaped reinforcing rib is arranged in a center through hole and a radial hole channel, and the extrusion rigidity of the flow channel is improved. The application integrates floating energy absorption, active chip removal and structural reinforcement, prevents the bending damage of the edge column tooth, prolongs the service life of the drill bit, and improves the deep hard rock tunneling efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of mining rock drilling equipment, specifically to a mining impact rock drill bit assembly. Background Technology

[0002] In deep-hole rock drilling operations in mines, the impact drill bit is a key component that directly acts on the rock. Its structure directly affects the rock breaking efficiency and the life of the drill bit. Existing impact drill bits generally have cemented carbide pin teeth brazed at a fixed angle to the end face of the drill bit body, and the rock is broken by transmitting stress waves through the axial impact of the piston.

[0003] However, in deep hard rock conditions where the rock compressive strength exceeds 300 MPa, the column teeth in the edge area of ​​the drill bit end face lack lateral restraint. When the bending stress they are subjected to in an instant exceeds the fatigue limit of the alloy, microcracks will form at the brazed interface at the root. The deeper the hole, the more difficult it is for the airflow to blow the rock cuttings out of the bottom of the hole in time. The rock cuttings are repeatedly ground between the drill bit end face and the bottom of the hole to form a buffer pad, which changes the actual transmission path of the stress wave. This causes the edge column teeth to be subjected to unexpected non-axial impact components. Frequent drilling and replacement of the drill bit seriously restricts the tunneling efficiency and increases the operating cost. Summary of the Invention

[0004] The purpose of this invention is to provide an impact rock drill bit assembly for mining, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a mining impact rock drill bit assembly, comprising a drill bit body, wherein the drill bit body is divided into an integrally formed head section and a tail section along the axial direction, the end face of the head section is the working surface that directly contacts the rock, and the outer periphery of the tail section is provided with external threads for connecting drill rods. The head section has a central column tooth hole and an edge column tooth hole located around the central column tooth hole. A central column tooth is fixedly connected in the central column tooth hole, and an edge column tooth is slidably inserted in the edge column tooth hole. A buffer cavity extending inward along the axial direction is opened at the center of the bottom of the edge column tooth hole. The buffer cavity contains a buffer element, and the end face of the buffer element abuts against a hard block. The buffer is a disc spring structure with a yield strength lower than that of the drill bit body material, so that when the bending stress wave acting on the edge column tooth exceeds a preset threshold, the edge column tooth will squeeze the buffer by abutting the hard block to generate a micro-axial displacement relative to the drill bit body.

[0006] Preferably, the axis of the central column tooth hole is parallel to the axis of the drill bit body, and the axis of the edge column tooth hole forms an outwardly flared tilt structure with respect to the axis of the drill bit body.

[0007] Preferably, the head of the central column tooth protrudes from the end face of the head segment, the buffer cavity is coaxial with the edge column tooth hole, and the inner diameter is larger than the outer diameter of the root of the edge column tooth.

[0008] Preferably, the abutting block is fixedly connected to the edge column teeth, the outer diameter of the abutting block is equal to the inner diameter of the buffer cavity, the abutting block extends axially downward into the buffer cavity, and forms an abutment with the end face of the buffer member.

[0009] Preferably, venting micro-holes are respectively opened on the outer peripheral surface of the head section at the position corresponding to the bottom of the buffer cavity, and the venting micro-holes connect the bottom space of the buffer cavity with the outside of the drill bit body.

[0010] Preferably, the drill bit body has a central through hole inside, the air inlet end of the central through hole is connected to the end face of the tail section, and the air outlet end of the central through hole extends into the head section. The head section is provided with radial diversion channels. The inlet end of each radial diversion channel is connected to the outlet end of the central through hole, and the outlet end points to the end face corresponding to the area between two adjacent edge column teeth holes.

[0011] Preferably, a flow guiding recess is provided on the end face of the head segment, each flow guiding recess is located between two adjacent edge column teeth holes, and the outlet end of the radial flow channel opens directly on the bottom surface of the corresponding flow guiding recess.

[0012] Preferably, the guide recess has a fan-shaped structure on the end face of the head section, with the narrow end of the fan-shaped structure pointing towards the central column tooth hole and the wide end extending to the outer peripheral edge of the head section.

[0013] Preferably, a first reinforcing rib is integrally formed on the central through hole, and the first reinforcing rib has a cross-shaped block structure.

[0014] Preferably, a second reinforcing rib is integrally formed on the radial diversion channel, and the second reinforcing rib is fixedly connected to the first reinforcing rib. The second reinforcing rib has a cross-shaped block structure.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses a sliding insert mechanism with a disc spring buffer to achieve the following: When the bending stress exceeds the threshold due to heterogeneous deep hard rock or debris accumulation at the bottom of the hole, the tooth absorbs energy by generating axial micro-displacement through abutting against the hard block compression buffer. This eliminates the failure of micro-cracks at the root of the traditional brazing interface, significantly extends the effective drilling depth, reduces the frequency of drill bit replacement, and lowers operating costs.

[0016] 2. This invention uses the fan-shaped guide groove on the end face and the radial diversion channel to form a radially flat jet that adheres to the end face, which immediately forces the rock cuttings at the bottom of the hole to be removed, completely eliminating the interference of the rock cuttings buffer pad on the stress wave path, protecting the edge column teeth from additional non-axial impacts, and ensuring that the impact energy is accurately fed into the rock mass. The central through hole and the radial channel have built-in cross-shaped reinforcing ribs to enhance the flow channel's anti-squeezing stiffness, ensure continuous and reliable deep hole powder discharge, and improve tunneling efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the impact rock drill bit assembly for mining of the present invention.

[0018] Figure 2 This is a schematic diagram of the structure of the end face of the head segment of the present invention.

[0019] Figure 3 This is a schematic diagram of the side structure of the drill bit body of the present invention.

[0020] Figure 4 This is a schematic diagram of the structure of the central through hole and the radial diversion channel of the present invention.

[0021] Figure 5 This is a partial cross-sectional view of the head segment of the present invention.

[0022] Figure 6 This is a schematic diagram of the internal structure of the buffer cavity of the present invention.

[0023] Figure 7 This is a schematic diagram of the structure of the second reinforcing rib of the present invention.

[0024] Figure 8 This is a schematic diagram of the structure of the first reinforcing rib of the present invention.

[0025] In the figure: 1-Drill bit body; 11-Head section; 12-Tail section; 121-External thread; 2-Central column tooth; 21-Central column tooth hole; 3-Edge column tooth; 31-Edge column tooth hole; 32-Abutting block; 4-Buffer cavity; 5-Buffer element; 6-Exhaust micro-hole; 7-Guiding recess; 8-Central through hole; 9-Radial diversion channel; 10-First reinforcing rib; 13-Second reinforcing rib. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figures 1 to 3The present invention provides a technical solution: a mining impact rock drill bit assembly, including a drill bit body 1, which is divided into a head section 11 and a tail section 12 along the axial direction, both forged from the same alloy steel billet and heat-treated as a whole. The tail section 12 has external threads 121 machined on its outer periphery for transmission connection with the rock drill rod. The front end face of the head section 11 is the working face for directly impacting and breaking rocks.

[0028] The end face of the head section 11 is provided with a central column tooth hole 21 and an edge column tooth hole 31 located around the central column tooth hole 21. The axis of the central column tooth hole 21 is parallel to the rotation axis of the drill bit body 1. After the central column tooth 2 is inserted into the central column tooth hole 21 with an interference fit, it is brazed at high temperature with copper-based brazing filler metal to form a fixed connection. The head of the central column tooth 2 protrudes from the end face of the head section 11 to ensure that it contacts the bottom rock of the hole first during drilling, thus playing the role of central slotting.

[0029] like Figure 5 As shown, the axis of the edge column tooth hole 31 forms an outward-opening angle with the axis of the drill bit body 1. This angle causes the edge column tooth 3 to be in an outward-biased cutting posture on the bottom plate, which can not only ensure effective hole enlargement and maintain the regularity of the hole wall, but also allow the impact energy to be transmitted to the rock along the oblique direction, thereby improving the rock breaking efficiency of the edge tooth.

[0030] The edge post tooth 3 is slidably inserted into the edge post tooth hole 31. A precise radial gap of 0.06mm is maintained between the post body of the edge post tooth 3 and the hole wall, thereby giving the edge post tooth 3 the freedom to generate axial micro-displacement, replacing the traditional brazing connection method, thus structurally eliminating the failure mode of micro-cracks generated at the brazing interface at the root of the edge post tooth due to bending overload.

[0031] A buffer cavity 4 is machined to extend axially inward from the center of the bottom of the edge column tooth hole 31. The buffer cavity 4 is coaxial with the edge column tooth hole 31 and its inner diameter is larger than the maximum outer diameter of the root of the edge column tooth 3. The bottom of the buffer cavity 4 is flat-ground to accommodate the buffer element 5. The buffer element 5 is a disc spring structure and is made of spring steel with a yield strength lower than that of the drill bit body 1 material, such as 50CrVA. The load displacement characteristics formed by the stacking of multiple pieces can set a clear axial compression threshold.

[0032] like Figure 6 As shown, the root of the edge column tooth 3 is fixedly connected to the abutting block 32 by high-frequency induction brazing. The outer diameter of the abutting block 32 is equal to the inner diameter of the buffer cavity 4. The two adopt a sliding fit. After assembly, the lower end face of the abutting block 32 is tightly abutted against the upper end face of the disc spring under the pre-tightening force of the buffer 5.

[0033] When drilling deep hard rock, the impact stress wave is transmitted through the drill bit body 1. The central column tooth 2 bears a relatively simple axial pressure, while the edge column tooth 3, due to its inclined arrangement and location at the intersection of the bottom edge of the hole and the hole wall, will inevitably bear the bending stress induced by the heterogeneity of the rock, the irregular shape of the bottom of the hole, and the lateral component of the stress wave during the rock breaking process.

[0034] When the discharge of rock debris at the bottom of the hole is obstructed and a flexible buffer pad is formed by the accumulation of rock cuttings, the actual transmission path of the stress wave changes. The edge column tooth 3 will be subjected to an unexpected non-axial bending impact with an amplitude exceeding the normal level. Once the force component of this non-axial bending impact along the axis of the column tooth exceeds the preset compression threshold of the buffer component 5, the edge column tooth 3 will press against the buffer component 5 by abutting against the hard block 32, generating a slight axial displacement into the buffer cavity 4. During this process, the disc spring absorbs and dissipates the bending impact energy through its own elastic-plastic deformation, effectively limiting the amplitude of the bending stress transmitted between the root of the edge column tooth 3 and the borehole wall of the drill bit body, protecting the cemented carbide column tooth from cracking, and also preventing the propagation of cracks at the root of traditional brazing. After the impact, the buffer component 5 rebounds, and the edge column tooth 3 resets, achieving repeated and reliable energy absorption.

[0035] like Figure 6 As shown, in order to avoid the confined air in the buffer cavity 4 from hindering the transient displacement of the edge column teeth 3, exhaust microholes 6 are radially drilled on the outer peripheral surface of the head section 11 at the position corresponding to the bottom of the buffer cavity 4. The inner opening of the exhaust microholes 6 is connected to the bottom space of the buffer cavity 4. When the edge column teeth 3 are impacted and axially fed, the bottom volume of the buffer cavity 4 is compressed, and the air in the cavity is smoothly discharged to the outside through the exhaust microholes 6, without generating back pressure resistance to the movement of the buffer component 5. When the edge column teeth 3 rebound, the positive pressure of the external flushing airflow can enter the cavity through the exhaust microholes 6 to prevent rock powder or water from being trapped and blocked, and to maintain the sensitive response of the buffer mechanism.

[0036] like Figure 4 and Figure 8 As shown, a central through hole 8 is provided along the axis of the drill bit body 1. The air inlet end of the central through hole 8 is connected to the end face of the tail section 12 to receive the high-pressure airflow or air-water mixture flow input from the drill rod hole. The air outlet end of the central through hole 8 extends into the head section 11. A radial diversion channel 9 is provided in the head section 11. The radial diversion channel 9 diverts the flow to the periphery. The inlet end of each radial diversion channel 9 is perpendicular to and connected to the air outlet end of the central through hole 8. Its outlet end points to the end face area between two adjacent edge column tooth holes 31, and the outlet end opens directly on the bottom surface of the corresponding guide recess 7.

[0037] like Figure 7As shown, the guide recess 7 is located on the working surface of the head section 11. In the top view, it has a fan-shaped structure. The narrow end of the fan points to the central column tooth hole 21, and the wide end extends to the outer peripheral edge of the head section 11. After the high-pressure medium output from the radial diversion channel 9 enters the guide recess 7, it is constrained and guided by the fan-shaped wall to form a flat high-speed jet that closely adheres to the end face and diverges radially outward. This jet completely covers and sweeps the entire rock-breaking area between adjacent edge columns, instantly blowing the broken rock fragments away from the bottom of the hole along the hole wall. During the drilling process, the bottom of the hole remains clean, effectively preventing the formation of rock fragment buffer pads. This ensures that the impact stress wave is always efficiently transmitted to the rock along the designed path, and the edge columns are protected from abnormal non-axial impact components caused by buffer pads, thus maintaining their normal stress state and extending the effective working depth.

[0038] like Figure 7 and Figure 8 As shown, to ensure the structural integrity of the high-pressure flow channel under severe impact and multi-directional rock mass reaction, a first reinforcing rib 10 is integrally formed inside the cavity of the central through hole 8. The first reinforcing rib 10 has a cross-shaped block structure. A second reinforcing rib 11 is integrally formed inside the cavity of each radial branch channel 9. The second reinforcing rib 11 also has a cross-shaped block structure. The inner end of the second reinforcing rib 11 and the outer edge of the first reinforcing rib 10 are continuously fused with metal materials through a close casting process at the intersection of the central through hole 8 and the radial branch channel 9 to form a fixed connection, constituting an integral spatial cross skeleton structure. The skeleton structure provides strong support for the powder discharge channel wall to resist impact and extrusion without excessively increasing the weight of the drill bit. This prevents the channel cross section from collapsing or becoming blocked during long-term deep hole operation, ensuring stable airflow distribution and continuous and powerful purging.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A mining impact rock drill bit assembly, comprising a drill bit body (1), characterized in that: The drill bit body (1) is divided into an integrally formed head section (11) and tail section (12) along the axial direction. The end face of the head section (11) is the working surface that directly contacts the rock, and the outer periphery of the tail section (12) is provided with external threads (121) for connecting the drill rod. The head section (11) has a central column tooth hole (21) and an edge column tooth hole (31) located around the central column tooth hole (21). A central column tooth (2) is fixedly connected in the central column tooth hole (21), and an edge column tooth (3) is slidably inserted in the edge column tooth hole (31). A buffer cavity (4) extending inward along the axial direction is provided at the center of the bottom of the edge column tooth hole (31). The buffer cavity (4) contains a buffer member (5), and the end face of the buffer member (5) abuts against a hard block (32). The buffer (5) is a disc spring structure with a yield strength lower than that of the drill bit body (1) material, so that when the bending stress wave acting on the edge column tooth (3) exceeds a preset threshold, the edge column tooth (3) squeezes the buffer (5) by abutting the hard block (32) to generate an axial micro displacement relative to the drill bit body (1).

2. The impact rock drill bit assembly for mining according to claim 1, characterized in that: The axis of the central column tooth hole (21) is parallel to the axis of the drill bit body (1), and the axis of the edge column tooth hole (31) forms an outwardly opening inclined structure with respect to the axis of the drill bit body (1).

3. The impact rock drill bit assembly for mining according to claim 1, characterized in that: The head of the central column tooth (2) protrudes from the end face of the head segment (11), the buffer cavity (4) is coaxial with the edge column tooth hole (31), and its inner diameter is greater than the outer diameter of the root of the edge column tooth (3).

4. The impact rock drill bit assembly for mining according to claim 1, characterized in that: The abutting block (32) is fixedly connected to the edge column tooth (3). The outer diameter of the abutting block (32) is equal to the inner diameter of the buffer cavity (4). The abutting block (32) extends axially downward into the buffer cavity (4) and forms an abutment with the end face of the buffer member (5).

5. The impact rock drill bit assembly for mining according to claim 1, characterized in that: The head section (11) has exhaust microholes (6) at the positions corresponding to the bottom of the buffer cavity (4) on its outer peripheral surface. The exhaust microholes (6) connect the bottom space of the buffer cavity (4) with the outside of the drill bit body (1).

6. The impact rock drill bit assembly for mining according to claim 1, characterized in that: The drill bit body (1) has a central through hole (8) inside. The air inlet end of the central through hole (8) is connected to the end face of the tail section (12), and the air outlet end of the central through hole (8) extends into the head section (11). The head section (11) is provided with radial diversion channels (9). The inlet end of each radial diversion channel (9) is connected to the outlet end of the central through hole (8), and the outlet end points to the end face corresponding to the area between two adjacent edge column teeth holes (31).

7. A mining impact rock drill bit assembly according to claim 6, characterized in that: The head section (11) has a flow guiding recess (7) on its end face. Each flow guiding recess (7) is located between two adjacent edge column tooth holes (31). The outlet end of the radial flow channel (9) opens directly on the bottom surface of the corresponding flow guiding recess (7).

8. A mining impact rock drill bit assembly according to claim 7, characterized in that: The guide recess (7) has a fan-shaped structure on the end face of the head section (11), with the narrow end of the fan-shaped structure pointing to the central column tooth hole (21) and the wide end extending to the outer peripheral edge of the head section (11).

9. A mining impact rock drill bit assembly according to claim 1, characterized in that: The central through hole (8) is integrally formed with a first reinforcing rib (10), which has a cross-shaped block structure.

10. A mining impact rock drill bit assembly according to claim 1, characterized in that: The radial diversion channel (9) is integrally formed with a second reinforcing rib (11), which is fixedly connected to the first reinforcing rib (10). The second reinforcing rib (11) has a cross-shaped block structure.

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