Device for testing detonation velocity in blast hole

Abstract

The invention belongs to the technical field of detonation velocity testing, and discloses a device for testing detonation velocity in a blast hole, which comprises an anti-explosion tail shell and an anti-impact head shell coaxially and fixedly connected to the top end of the anti-explosion tail shell, the top end of the anti-impact head shell is provided with a detection assembly used for detecting the detonation velocity through wireless signals. And a self-centering assembly is arranged in the explosion-proof tail shell. Axial linear motion is converted into radial synchronous expansion motion of the supporting plate, constant tensioning force is provided in cooperation with a reset spring, the device can automatically adapt to diameter changes and unevenness of the inner wall of a blast hole through the structure, the device body is forcibly locked at the geometric center position of the blast hole, and the device is more stable and reliable. Operation errors caused by traditional manual installation are eliminated, more importantly, it is ensured that the radar wave beam direction in the detection assembly is always kept parallel to the axis of the blast hole, therefore, angle errors caused by inclination of a probe are effectively avoided, and high precision and high consistency of detonation velocity test data are ensured.

Description

Technical Field

[0001] This invention belongs to the field of detonation velocity testing technology, specifically a device for testing detonation velocity inside a borehole. Background Technology

[0002] Detonation velocity is a crucial parameter for evaluating the performance of explosives, and existing testing methods mainly include the resistance wire method and the electromagnetic wave method. Among these, the use of millimeter-wave radar for in-hole testing is highly favored due to its ability to continuously record data.

[0003] One of the main problems with existing technologies is the difficulty in installation and alignment. The inner wall of the borehole is usually uneven, making it difficult for traditional devices to maintain the geometric center of the borehole. If the test probe is tilted, the radar beam will form an angle with the direction of the detonation wave, directly leading to significant deviations in the measurement data. In addition, traditional installation methods often require manual wiring and filling for fixation, which is cumbersome and time-consuming, greatly affecting the efficiency of field operations.

[0004] Another core issue is insufficient protection and pressure relief capabilities. At the moment of explosive detonation, extremely high impact pressure and instantaneous high temperatures are generated inside the borehole. Most existing devices lack effective physical buffering and active pressure relief mechanisms; high-pressure gas often directly impacts the circuitry, causing expensive electronic components to be damaged before data transmission is complete. This not only results in one-time equipment failure (0% recovery rate) and increased testing costs, but also makes it difficult to obtain complete data on the detonation wave growth process. Summary of the Invention

[0005] The purpose of this invention is to provide a device for testing detonation velocity inside a borehole, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a device for testing detonation velocity inside a blast hole, comprising an explosion-proof tail housing and an impact-resistant head housing coaxially fixedly connected to the top of the explosion-proof tail housing;

[0007] The top of the impact-resistant head housing is equipped with a detection component for detecting detonation velocity via wireless signal.

[0008] The explosion-proof tail housing is equipped with a self-aligning component, which is configured with a linkage mechanism that drives the sidewall to expand radially through axial movement, for locking the device at the center of the borehole.

[0009] A venting assembly is provided between the explosion-proof tail housing and the impact-resistant head housing. The venting assembly is equipped with an automatic opening structure that is physically separated when triggered by shock wave pressure, for releasing internal high-pressure gas.

[0010] The anti-impact head housing has a guide post inside, and the guide post has a variable cross-section acceleration channel for rectifying and depressurizing the intruding gas.

[0011] As a further technical solution of the present invention, the linkage mechanism of the self-centering component includes a control rod that is slidably sleeved in the explosion-proof tail housing and a movable plate fixed to its top.

[0012] The bottom end of the movable plate is circumferentially hinged with several first fixed seats, each of which is rotatably connected to a second fixed seat via a support rod, and an installation rod is connected to the outside of the second fixed seat.

[0013] The explosion-proof tail housing has holes on its side wall for the mounting rod to pass through, and the end of the mounting rod is fixed with a support plate located on the outside of the housing.

[0014] By pushing the control lever, the movable plate is displaced, thereby driving the support plate to open radially outward.

[0015] As a further technical solution of the present invention, the self-aligning component further includes an elastic reset mechanism, the elastic reset mechanism including a fixed sleeve and a reset rod passing through the fixed sleeve;

[0016] One end of the reset rod is connected to the movable plate, and the other end is provided with a limiting plate. The fixed sleeve is provided with a reset spring that abuts against the bottom of the limiting plate. The reset spring is used to drive the support plate to retract when the external force on the control rod is removed.

[0017] As a further technical solution of the present invention, the variable cross-section acceleration channel opened in the guide column is a Venturi acceleration channel, which includes, from top to bottom, a funnel-shaped inlet section, a necked throat section, and a cone-shaped outlet section.

[0018] The bottom end of the guide column is connected to a circuit box, the inner diameter of which is adapted to the aperture of the Venturi acceleration channel outlet section, and the circuit box is located above the venting assembly.

[0019] As a further technical solution of the present invention, the venting assembly includes an explosion-proof base plate that is connected to the bottom outlet of the guide column, and the explosion-proof base plate extends outward and is connected to a diffuser tube with a bowl-shaped structure.

[0020] The explosion-proof base plate has a protruding guide cone at its center, with the tip of the guide cone facing the gas outlet of the guide column, which is used to guide and disperse the axial impact airflow into the diffuser tube.

[0021] As a further technical solution of the present invention, the automatic opening structure of the venting component includes a retaining ring covering the top opening of the diffuser tube, and a plurality of locking lugs disposed on the inner sidewall edge of the diffuser tube.

[0022] The lower surface of the retaining ring extends with several anti-detachment rods, and the ends of the anti-detachment rods are fitted with anti-detachment collars; the anti-detachment collars and the locking ear plate are connected in a separable manner by interference fit or snap-fit. When the internal air pressure of the diffuser exceeds the threshold, the anti-detachment collars disengage from the locked state to release the retaining ring.

[0023] As a further technical solution of the present invention, the detection component includes a fixed skirt at the top and a conical diverter cone embedded at the top of the fixed skirt;

[0024] A focusing lens is installed in the internal cavity of the fixed skirt. The focusing lens is located below the flow divider cone and is perpendicular to the axis of the device.

[0025] As a further technical solution of the present invention, the bottom of the fixed skirt is provided with an external threaded tube, and an internal threaded tube is threadedly connected to the external threaded tube. The inner wall of the internal threaded tube is provided with several longitudinal mounting grooves.

[0026] The detection assembly also includes a millimeter-wave radar. The outer wall of the millimeter-wave radar is provided with a protruding locking block that matches the mounting groove. The millimeter-wave radar is axially pressed and fixed by tightening the internal threaded tube.

[0027] As a further technical solution of the present invention, a pair of handles are symmetrically fixed on the outer walls of both sides of the bottom end of the explosion-proof tail housing, for operators to hold and operate the self-centering component.

[0028] As a further technical solution of the present invention, the main body material of the explosion-proof tail shell and the impact-resistant head shell are both titanium alloys, and the outer surfaces of the explosion-proof tail shell and the impact-resistant head shell are covered with a thermal barrier coating structure.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. This invention achieves automatic centering and stable support of the device within irregular boreholes through a linkage and elastic reset mechanism. The invention utilizes the cooperation of a control lever and a movable plate to convert axial linear motion into radial synchronous expansion motion of the support plate, while a reset spring provides constant tension. This structure allows the device to automatically adapt to changes in borehole diameter and unevenness, forcibly locking the main body of the device at the geometric center of the borehole. This not only eliminates operational errors caused by traditional manual installation but, more importantly, ensures that the radar beam direction in the detection component remains parallel to the borehole axis, effectively avoiding angular errors caused by probe tilt and guaranteeing high accuracy and consistency of detonation velocity test data.

[0031] 2. This invention utilizes a Venturi acceleration channel with a specific variable cross-sectional shape designed inside the guide column. By applying the principles of gas dynamics, the high-pressure gas entering the device is forced to experience a surge in velocity and a sharp drop in static pressure as it passes through the throat. This significantly reduces the shock wave pressure directly acting on the rear circuit box at the physical level. Simultaneously, the thermal barrier coating on the outer surface blocks instantaneous high temperatures. This design effectively solves the problem that electronic components are damaged before data recording is completed due to the lack of a buffer mechanism in traditional devices. It ensures that the core circuit can survive and complete the entire data acquisition process even in extreme explosive environments.

[0032] 3. This invention employs a locking mechanism that combines an anti-detachment ring with a locking lug. This mechanism has a specific mechanical threshold. Under normal conditions, it can ensure the sealing and integrity of the structure. At the moment of explosion, the huge aerodynamic impact force will dislodge the anti-detachment ring, instantly release the lock and throw away the retaining ring, thereby completely opening the pressure relief channel at the tail of the diffuser tube within milliseconds. This mechanism of actively guiding and releasing pressure avoids the pressure buildup and rupture caused by the accumulation of explosive gas inside the shell. This ensures that the main metal structure of the device remains intact after testing and can be reused with only a few vulnerable parts replaced, significantly reducing long-term testing costs. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0034] Figure 2 This is a schematic diagram of the bottom of the overall structure of the present invention;

[0035] Figure 3 This is a cross-sectional schematic diagram of the internal structure of the explosion-proof tail housing of the present invention;

[0036] Figure 4 This is a partial structural schematic diagram of the self-alignment component of the present invention;

[0037] Figure 5 This is a schematic diagram showing the cooperation between a portion of the self-aligning component and the venting component structure of the present invention;

[0038] Figure 6 This is a side cross-sectional view of the venting component of the present invention;

[0039] Figure 7 This is a partial schematic diagram of the structure of the venting component of the present invention;

[0040] Figure 8 This is a schematic diagram showing the interaction between a partial structure of the venting component and the impact-resistant head housing structure of the present invention;

[0041] Figure 9 This is a cross-sectional schematic diagram of the guide column and venting assembly structure of the present invention;

[0042] Figure 10 This is an exploded view of the structure of the detection component of the present invention.

[0043] In the diagram: 1. Explosion-proof tail housing; 2. Handle; 3. Self-centering assembly; 301. Control lever; 302. Movable plate; 303. First fixed seat; 304. Second fixed seat; 305. Support rod; 306. Mounting rod; 307. Support plate; 308. Fixing sleeve; 309. Reset rod; 3010. Reset spring; 3011. Limiting plate; 4. Impact-resistant head housing; 5. Guide post; 6. Venturi accelerator. 7. Circuit box; 8. Venting assembly; 801. Explosion-proof base plate; 802. Guide cone; 803. Diffuser tube; 804. Locking ear plate; 805. Retaining ring; 806. Anti-detachment rod; 807. Anti-detachment collar; 9. Detection assembly; 901. Fixing skirt; 902. Diverter cone; 903. Focusing lens; 904. External threaded tube; 905. Internal threaded tube; 906. Mounting slot; 907. Millimeter-wave radar. Detailed Implementation

[0044] 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.

[0045] like Figures 1 to 10 As shown, this embodiment of the invention provides a device for testing detonation velocity inside a borehole, which mainly includes an explosion-proof tail housing 1, and an anti-impact head housing 4 is fixedly connected to the top of the explosion-proof tail housing 1. In order to improve the explosion-proof performance of both, the explosion-proof tail housing 1 and the anti-impact head housing 4 are both made of titanium alloy. The top of the anti-impact head housing 4 is equipped with a detection component 9 for detecting detonation velocity, and a venting component 8 is installed on the outer side between the explosion-proof tail housing 1 and the anti-impact head housing 4.

[0046] To facilitate the installation of this device, a self-aligning component 3 is installed inside the explosion-proof tail housing 1. The top of the self-aligning component 3 is connected to the bottom of the venting component 8. Meanwhile, to meet the installation requirements, the explosion-proof tail housing 1 is designed as a cylinder with a smaller top diameter and a larger bottom diameter. In addition, to facilitate hand-holding when installing the device, handles 2 are installed on both sides of the bottom of the explosion-proof tail housing 1.

[0047] To reduce pressure during decompression, a guide post 5 is installed inside the anti-impact head housing 4. A Venturi acceleration channel 6 is also provided inside the guide post 5. The top of the Venturi acceleration channel 6 is funnel-shaped, while the bottom of the Venturi acceleration channel 6 is conical. A narrow throat is provided between the two to connect the upper and lower channels. Specifically, the width of the top of the Venturi acceleration channel 6 is smaller than the width of the bottom of the Venturi acceleration channel 6, but larger than the width of the throat in the middle.

[0048] The structural parameters of the Venturi acceleration channel 6 are based on gas dynamics design, aiming to rectify and depressurize the incoming airflow using Bernoulli's principle and Laval nozzle effect;

[0049] Let the cross-sectional area of ​​the entrance at the top of the channel be... The cross-sectional area of ​​the throat is The cross-sectional area of ​​the bottom outlet is Based on the gas continuity equation and the law of conservation of energy, the design proportions satisfy... : : =5:1:3, throat diameter The selection is based on the maximum estimated pressure generated by the explosion. With the sensor's allowable pressure The relationship between them satisfies the following formula:

[0050]

[0051] Where D is the inner diameter of guide post 5. With a flow coefficient of 0.85-0.95, the Venturi acceleration channel 6 achieves a rapid increase in flow velocity and a decrease in static pressure when the explosive gas passes through the throat. This effectively reduces the impact pressure directly acting on the top of the circuit box 7 to 30%-40% of the original pressure, thus achieving physical protection without affecting signal transmission.

[0052] Meanwhile, a circuit box 7 is installed at the bottom of the guide column 5, located above the venting assembly 8. The circuit box 7 contains a circuit board and is connected to the detection assembly 9 wirelessly. In order to prevent the circuit box 7 from being damaged during the explosion, the inner diameter of the circuit box 7 is the same as the width of the bottom of the Venturi acceleration channel 6, so the explosion will not cause direct impact on the circuit box 7.

[0053] The titanium alloy material used for the explosion-proof tail shell 1 and the impact-resistant head shell 4 is specifically TC4 (Ti-6Al-4V) titanium alloy, which undergoes a double annealing process, namely, holding at 750℃ for 1 hour and air cooling and holding at 550℃ for 2 hours and air cooling, to obtain an equiaxed α+β two-phase structure, thus taking into account both high strength and high toughness. Furthermore, in order to cope with the instantaneous high temperature generated at the moment of explosion, the outer surface of the impact-resistant head shell 4 and the explosion-proof tail shell 1 is sprayed with a nano-zirconia ZrO2 thermal barrier coating with a coating thickness of 0.3mm-0.5mm. This coating has an extremely low thermal conductivity coefficient, which can effectively block the heat transfer to the internal circuit box 7 within milliseconds of the arrival of the explosion shock wave, ensuring that the internal electronic components do not fail due to overheating before completing data recording.

[0054] The circuit board installed inside the circuit box 7 consists of an RF front-end board, a signal processing main control board, and a power management board. The RF front-end board consists of a millimeter-wave radar chip SoC and a printed antenna array, which is used to receive signals from the detection component 9 and perform pre-processing. The signal processing main control board consists of a high-speed DSP for FFT transformation to calculate the detonation velocity and a large-capacity Flash memory, which is used to calculate the detonation velocity and store data. The power management board consists of a voltage regulator chip and a power-loss protection capacitor, which is used to connect the built-in battery pack to power the entire circuit board.

[0055] To achieve complete separation between the detection sensor and the circuit processing section, the device uses two sets of built-in batteries to power the sensor and the circuit respectively. The sensor section is powered by a lithium-manganese dioxide pouch battery, and the circuit section is powered by a lithium-thionyl chloride battery. Neither of these structures is shown in the figure.

[0056] To facilitate rapid installation of the device and quick alignment of the detection component 9, a self-alignment component 3 is introduced. This component mainly includes a control lever 301, which is movably connected to the middle of the explosion-proof tail housing 1. A movable plate 302 located inside the explosion-proof tail housing 1 is fixedly installed at the top of the control lever 301. The self-alignment component 3 also includes a fixed sleeve 308, whose top is connected to the bottom of the venting component 8. A limiting plate 3011 is movably fitted inside the fixed sleeve 308. A reset rod 309 is fixedly installed at the bottom of the limiting plate 3011, penetrating the bottom of the fixed sleeve 308 and connecting to the top of the movable plate 302. To reset the self-alignment component 3, a reset spring 3010 is movably fitted inside the reset rod 309. The upper and lower ends of the reset spring 3010 are connected to the bottom of the limiting plate 3011 and the inner bottom wall of the fixed sleeve 308.

[0057] Meanwhile, a first fixed seat 303 is axially and equally spaced at the bottom end of the movable plate 302 near the outer side. A support rod 305 is movably mounted on the end of the first fixed seat 303 away from the movable plate 302 via a pivot. A second fixed seat 304 is movably mounted on the end of the support rod 305 away from the first fixed seat 303 via a pivot. A mounting rod 306 is installed on one end of the outer side of the second fixed seat 304. A through hole adapted to the mounting rod 306 is opened at the corresponding position on the outer side of the explosion-proof tail housing 1. The mounting rod 306 passes through the through hole and is mounted on a support plate 307 located on the outer side of the explosion-proof tail housing 1. To improve anti-slip properties, an anti-slip groove is opened on the outer side of the support plate 307 to increase friction.

[0058] Example: When installing the device and aligning the detection component 9, first, by holding the two handles 2 at the bottom of the explosion-proof tail housing 1, press the control lever 301 towards the device and insert the device vertically into the borehole. At this time, the control lever 301 and the movable plate 302 move towards the venting component 8, and the reset lever 309 and the limiting plate 3011 move towards the venting component 8. At this time, the reset spring 3010 is stretched, and the distance between the movable plate 302 and the venting component 8 decreases. At this time, the multiple support rods 305 deflect towards the center, that is, the multiple second fixed seats 304 move towards each other and apply tension to the mounting rod 306 until the multiple support plates 307 move towards each other simultaneously until the multiple support plates 307 retract into the borehole at the same time.

[0059] At this point, the pressure on the control lever 301 can be released, and the reset spring 3010 will automatically reset, causing multiple support rods 305 to deflect away from the control lever 301. This will eventually cause multiple support plates 307 to move closer to the inner wall of the borehole until the multiple support plates 307 are pressed against the inner wall of the borehole. At this point, the device can be supported and installed by the self-centering component 3. At the same time, the three support plates 307 ensure that the detection component 9 is in the exact center of the borehole, completing the installation and self-centering process.

[0060] By utilizing the cooperation between the self-alignment component 3, the explosion-proof tail housing 1, and the detection component 9, the device can be quickly installed in the borehole and the detection component 9 can be quickly aligned. The whole process can be completed quickly, avoiding the complicated wiring and installation process of traditional devices. At the same time, it can be fully and automatically positioned and aligned after installation without manual adjustment, effectively reducing preparation time and improving overall testing efficiency.

[0061] To cope with the high-pressure impact generated by the explosion, the top of the detection component 9 is provided with a fixed skirt 901. Preferably, the main body of the fixed skirt 901 is made of high-strength titanium alloy material, so as to utilize the excellent impact resistance of titanium alloy to prevent the structure from being damaged at the moment of the explosion. A diverter cone 902 is embedded and installed on the top of the fixed skirt 901. The diverter cone 902 has a conical structure with its tip pointing upward. The diverter cone 902 is made of microwave transparent composite material (such as PEEK, polytetrafluoroethylene or alumina ceramic). This material has impact resistance while allowing millimeter-wave radar signals to penetrate. At the bottom of the diverter cone 902, that is, in the internal cavity of the fixed skirt 901, a focusing lens 903 is coaxially installed. The focusing lens 903 is located directly above the millimeter-wave radar 907. Its function is to converge the signals transmitted or received by the millimeter-wave radar 907, or to act as a protective layer for the radar to prevent external impurities from directly contacting the radar sensing surface.

[0062] To enable rapid replacement and maintenance of the millimeter-wave radar 907, this application sets up a quick-release structure that combines threaded connection and slot positioning. Specifically, the bottom end of the fixed skirt 901 extends downward to form an external threaded tube 904, which is matched with an independent internal threaded tube 905. The upper inner wall of the internal threaded tube 905 is provided with an internal thread that matches the external threaded tube 904. Through the threaded connection between the external threaded tube 904 and the internal threaded tube 905, the mechanical locking and disassembly of the upper and lower parts of the detection component are realized.

[0063] The millimeter-wave radar 907 is installed inside the internally threaded tube 905. To ensure the stability of the millimeter-wave radar 907 during the testing process and to prevent it from rotating circumferentially or swaying axially, several mounting grooves 906 are provided on the inner side wall of the internally threaded tube 905. Correspondingly, protruding locking blocks are provided on the outer wall of the millimeter-wave radar 907. During installation, the millimeter-wave radar 907 is placed into the internally threaded tube 905, and its locking blocks slide into the mounting grooves 906, thereby achieving circumferential limiting.

[0064] In practice, if it is necessary to replace the millimeter-wave radar 907, for example, if the radar is damaged after a blast test, the operator only needs to loosen the inner threaded tube 905 to separate it from the outer threaded tube 904. At this time, since the millimeter-wave radar 907 is limited in the inner threaded tube 905 by a snap-fit, the operator can easily take out the old millimeter-wave radar 907 from the inner threaded tube 905 and install the new radar. Finally, the inner threaded tube 905 is tightened back onto the outer threaded tube 904 to complete the assembly.

[0065] Specifically, the signal processing main control board calculates the detonation velocity based on the Doppler effect, and the millimeter-wave radar 907 transmits at a frequency of [frequency missing]. Continuous wave (CW) or frequency-modulated continuous wave (FMCW), when the detonation wave surface is at a velocity When the signal approaches the radar, the echo signal will experience a Doppler frequency shift. , explosive speed The calculation formula is as follows:

[0066]

[0067] in, At the speed of light, The angle between the radar beam and the direction of motion of the detonation wave in this device Therefore

[0068] In actual processing, the DSP chip performs the following steps on the received signal:

[0069] Mixing and filtering: The received signal is mixed with the transmitted signal to extract the intermediate frequency signal;

[0070] Windowing: Apply a Hamming window to the sampled data to suppress sidelobe leakage;

[0071] STFT Transform: Perform short-time Fourier transform to obtain the time-frequency spectrum;

[0072] Ridge Extraction: Energy ridges in the time-frequency plot are extracted using the constant false alarm rate (CFAR) algorithm. The frequency corresponding to these ridges is the frequency that changes over time. This allows for the inversion of the instantaneous velocity of the detonation wave at different locations. Compared to the traditional resistance wire method, which can only measure the average velocity, this device can plot a complete detonation velocity-time curve.

[0073] To effectively depressurize explosive gases, this application includes a depressurization assembly 8. Specifically, the main structure of the depressurization assembly 8 includes an explosion-proof base plate 801 at the bottom, which is connected to the outlet of the Venturi acceleration channel 6. To optimize airflow and prevent damage caused by vertical gas impact on the base plate, a conical guide cone 802 is fixedly installed at the center of the inner bottom wall of the explosion-proof base plate 801. The tip of the guide cone 802 faces upward and is aligned with the outlet of the Venturi acceleration channel 6. Simultaneously, the explosion-proof base plate 801 extends outward and is fixedly connected to a diffuser tube 803 with a bowl-shaped or disc-shaped open structure. During operation, high-speed explosive gases rush out of the Venturi acceleration channel 6 and directly impact the guide cone 802, where they are physically dispersed and guided to the surrounding area. Subsequently, the airflow enters the internal space of the diffuser tube 803 along the extension direction of the explosion-proof base plate 801, thereby achieving the safe extraction and diffusion of the explosive gases.

[0074] In order to protect the internal structure and prevent explosive gases from flowing directly into the internal cavity of the diffuser tube 803 without guidance, a retaining ring 805 is covered at the top opening of the diffuser tube 803. The retaining ring 805 is fixed by a movable snap-fit ​​method to facilitate installation and automatic separation in the event of an explosion. Specifically, a number of locking lugs 804 are evenly spaced along the circumferential direction at the top edge of the inner wall of the diffuser tube 803. Correspondingly, a number of anti-detachment rods 806 are provided on the bottom surface of the retaining ring 805 extending axially downwards. An anti-detachment collar 807 is fixedly sleeved at the end of the outer side of each anti-detachment rod 806. During assembly, the retaining ring 805 is pressed down to insert the anti-detachment rod 806 into the diffuser tube 803. The anti-detachment collar 807 and the locking ear plate 804 are locked together by an interference fit or snap-fit ​​structure. This design allows the retaining ring 805 to stably cover the diffuser tube 803 under normal conditions, preventing it from falling off. However, during an explosive impact, the fit between the anti-detachment collar 807 and the locking ear plate 804 is released due to the explosive impact. The anti-detachment collar 807 falls off from the anti-detachment rod 806, and the anti-detachment rod 806 falls off along the locking ear plate 804, ultimately causing the retaining ring 805 and the diffuser tube 803 to separate. The explosive gas is completely discharged from the tail of the diffuser tube 803, completing the depressurization process.

[0075] Example: Under normal conditions, the retaining ring 805 is securely locked above the diffuser 803 through the cooperation of the anti-detachment rod 806 and the anti-detachment collar 807 with the locking ear plate 804, providing a sealing and protective function. When an explosion occurs, the high-speed, high-pressure explosive gas is first accelerated and diffused through the Venturi acceleration channel 6 and then rushes into the explosion-proof base plate 801. Subsequently, under the physical guidance of the guide cone 802, it is diverted to the surrounding areas and flows into the internal cavity of the diffuser 803. Under the action of huge gas impact force and pressure, the locking cooperation between the anti-detachment collar 807 and the locking ear plate 804 is forcibly released, and the anti-detachment collar 807 falls off from the anti-detachment rod 806, allowing the anti-detachment rod 806 to break free from the restraint of the locking ear plate 804. Finally, the retaining ring 805 is quickly separated from the diffuser 803. At this time, the pressure relief channel of the diffuser 803 is fully opened, and the accumulated explosive gas can be smoothly discharged from its tail, completing the automatic pressure relief process.

[0076] Through the coordinated design of the anti-detachment ring 807, anti-detachment rod 806, and locking ear plate 804, the structure achieves blocking in normal conditions and rapid separation during explosion. In normal transportation or standby conditions, this structure ensures that the retaining ring 805 is firmly covered on the diffuser tube 803, effectively providing protection and preventing external debris from entering or internal gas turbulence. At the moment of explosion, this structure can use the impact force to automatically break the connection of the anti-detachment ring 807, thereby achieving automatic ejection of the retaining ring 805. Without the need for an additional drive mechanism, the pressure relief channel can be opened to the maximum extent instantly, ensuring rapid release of internal pressure and protecting the main structure of the device from severe damage due to overpressure.

[0077] Application Testing and Verification: In order to verify the measurement accuracy and protective performance of the present invention, a field comparative test was conducted in an open-pit mine. The test object was No. 2 rock emulsion explosive with a borehole diameter of 90mm. The comparison group used the traditional "fixed-length resistance wire method" for testing.

[0078]

[0079] Working principle and usage process of this invention:

[0080] Rapid installation and self-alignment process: The operator holds the handle 2 at the bottom of the explosion-proof tail housing 1 and presses the operating lever 301 at the bottom inward. The operating lever 301 pushes the internal movable plate 302 and reset rod 309 to move towards the venting assembly 8, compressing the reset spring 3010. At this time, the movable plate 302 drives the first fixed seat 303 to move, forcing the support rod 305 to deflect, pulling the second fixed seat 304 and mounting rod 306 to retract inward, thereby driving the external support plate 307 to retract into the projection range of the explosion-proof tail housing 1. After pushing the device into the predetermined depth of the borehole, the operating lever 301 is released, and the reset spring 3010 releases its elastic force to reset the mechanism. The support plate 307 expands outward under the action of the connecting rod and fits tightly against the inner wall of the borehole. The support structure formed by the three support plates 307 automatically adjusts the axis of the device to the geometric center of the borehole, completing the fixation.

[0081] Detonation velocity detection and signal processing: After detonation, the millimeter-wave radar 907 on the top of the detection component 9 emits a signal and receives the echo through the focusing lens 903. The signal is transmitted to the circuit box 7 located at the bottom of the guide post 5. The internal circuit board processes and stores the signal, and records the velocity change of the detonation wave.

[0082] Physical protection and rectification pressure reduction: The high-pressure gas generated by the explosion first impacts the top diversion cone 902, and then the gas enters the guide column 5 inside the impact-resistant head housing 4. When the gas flows through the Venturi acceleration channel 6, the change in the flow channel cross section makes the airflow accelerate at the throat and produce a static pressure reduction effect, thereby greatly reducing the impact force directly acting on the top of the circuit box 7. At the same time, the thermal barrier coating on the surface of the housing blocks high temperature and protects the internal circuit.

[0083] Automatic pressure relief process: After depressurization, the gas rushes out of the guide column 5 and hits the guide cone 802 at the bottom of the gas relief component 8. It is dispersed and guided into the diffuser tube 803. When the internal gas pressure exceeds the critical value, the powerful impact force forces the anti-detachment ring 807 to fall off the anti-detachment rod 806, releasing the locking relationship with the locking ear plate 804. The retaining ring 805 then separates from the diffuser tube 803, instantly opening a huge pressure relief channel, allowing the explosive gas to be smoothly discharged from the tail, and preventing the main body of the device from exploding due to pressure buildup.

Claims

1. A device for testing detonation velocity inside a blast hole, characterized in that: It includes an explosion-proof tail housing (1) and an impact-resistant head housing (4) coaxially fixed to the top of the explosion-proof tail housing (1). The top of the impact-resistant head housing (4) is provided with a detection component (9) for detecting detonation velocity via wireless signal. The explosion-proof tail housing (1) is provided with a self-centering assembly (3) inside. The self-centering assembly (3) is equipped with a linkage mechanism that drives the side wall to expand radially through axial movement, which is used to lock the device at the center of the borehole. A venting assembly (8) is provided between the explosion-proof tail housing (1) and the impact-resistant head housing (4). The venting assembly (8) is equipped with an automatic opening structure that is physically separated by shock wave pressure to release internal high-pressure gas. The anti-impact head housing (4) is provided with a guide post (5) inside, and the guide post (5) is provided with a variable cross-section acceleration channel for rectifying and depressurizing the intruding gas.

2. The device for testing detonation velocity inside a borehole according to claim 1, characterized in that: The linkage mechanism of the self-centering component (3) includes a control lever (301) slidably sleeved in the explosion-proof tail housing (1) and a movable plate (302) fixed at its top. The bottom end of the movable plate (302) is circumferentially hinged with a plurality of first fixed seats (303), each of the first fixed seats (303) is rotatably connected to a second fixed seat (304) via a support rod (305), and an installation rod (306) is connected to the outside of the second fixed seat (304). The explosion-proof tail housing (1) has a hole on its side wall for the mounting rod (306) to pass through, and the end of the mounting rod (306) is fixed with a support plate (307) located on the outside of the housing. By pushing the control lever (301), the movable plate (302) is displaced, thereby driving the support plate (307) to open radially outward.

3. The device for testing detonation velocity inside a borehole according to claim 2, characterized in that: The self-centering component (3) further includes an elastic reset mechanism, which includes a fixed sleeve (308) and a reset rod (309) passing through the fixed sleeve (308). One end of the reset rod (309) is connected to the movable plate (302), and the other end is provided with a limiting plate (3011). The fixed sleeve (308) is provided with a reset spring (3010) that abuts against the bottom of the limiting plate (3011). The reset spring (3010) is used to drive the support plate (307) to retract when the external force of the control lever (301) is removed.

4. The device for testing detonation velocity inside a borehole according to claim 1, characterized in that: The variable cross-section acceleration channel opened in the guide column (5) is a Venturi acceleration channel (6). The Venturi acceleration channel (6) includes, from top to bottom, a funnel-shaped inlet section, a constricted throat section, and a cone-shaped outlet section. The bottom end of the guide post (5) is connected to a circuit box (7), the inner diameter of the circuit box (7) is adapted to the aperture of the outlet section of the Venturi acceleration channel (6), and the circuit box (7) is located above the venting assembly (8).

5. The apparatus for testing detonation velocity inside a borehole according to claim 1, characterized in that: The venting assembly (8) includes an explosion-proof base plate (801) connected to the bottom outlet of the guide post (5), and the explosion-proof base plate (801) extends outward and is connected to a diffuser tube (803) with a bowl-shaped structure. The explosion-proof base plate (801) has a protruding guide cone (802) at its center. The tip of the guide cone (802) is directly opposite the gas outlet of the guide column (5) and is used to guide and disperse the axial impact airflow into the diffuser (803).

6. The apparatus for testing detonation velocity inside a borehole according to claim 5, characterized in that: The automatic opening structure of the venting assembly (8) includes a retaining ring (805) covering the top opening of the diffuser tube (803) and a plurality of locking lugs (804) disposed on the inner sidewall edge of the diffuser tube (803). The lower surface of the retaining ring (805) extends with a plurality of anti-detachment rods (806), and the ends of the anti-detachment rods (806) are fitted with anti-detachment collars (807); the anti-detachment collars (807) and the locking ear plate (804) are connected in a separable manner by interference fit or snap-fit. When the internal air pressure of the diffuser tube (803) exceeds the threshold, the anti-detachment collars (807) disengage from the locked state to release the retaining ring (805).

7. The apparatus for testing detonation velocity inside a borehole according to claim 1, characterized in that: The detection component (9) includes a fixed skirt (901) at the top and a conical diversion cone (902) embedded at the top of the fixed skirt (901). A focusing lens (903) is installed in the internal cavity of the fixed skirt (901). The focusing lens (903) is located below the flow divider cone (902) and perpendicular to the axis of the device.

8. The apparatus for testing detonation velocity inside a borehole according to claim 7, characterized in that: The bottom of the fixed skirt (901) is provided with an external threaded tube (904), and an internal threaded tube (905) is threaded onto the external threaded tube (904). The inner wall of the internal threaded tube (905) is provided with several longitudinal mounting grooves (906). The detection component (9) also includes a millimeter-wave radar (907). The outer wall of the millimeter-wave radar (907) is provided with a protruding locking block that is adapted to the mounting groove (906). The millimeter-wave radar (907) is axially pressed and fixed by tightening the internal threaded tube (905).

9. The apparatus for testing detonation velocity inside a borehole according to claim 1, characterized in that: A pair of handles (2) are symmetrically fixed on the outer walls of both sides of the bottom end of the explosion-proof tail housing (1) for the operator to hold and operate the self-centering component (3).

10. The apparatus for testing detonation velocity inside a borehole according to claim 1, characterized in that: The main body material of the explosion-proof tail shell (1) and the impact-resistant head shell (4) is titanium alloy, and the outer surface of the explosion-proof tail shell (1) and the impact-resistant head shell (4) is covered with a thermal barrier coating structure.

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