Method and system for testing impact frequency of hydraulic rock drill

Abstract

The invention relates to a method and system for testing the impact frequency of a hydraulic rock drill, and the method comprises the following steps: collecting the sound generated during the working of the rock drill, collecting the sound of two seconds every ten seconds, and obtaining the audio information; processing the audio information by adopting short-time Fourier transform to obtain a time-frequency spectrogram of the audio information; the real-time impact frequency of the rock drill is extracted according to the time-frequency spectrogram; carrying out band-pass filtering on the acquired audio information with more than three times of impact frequency and more than two times of inherent frequency to obtain an impact characteristic signal; eMD decomposition is carried out on the impact characteristic signals to obtain an eigenmode function C (t), impact energy is calculated according to the eigenmode function C (t), and impact energy data are obtained. Compared with the prior art, the device is long in service life, low in cost, wide in application range and capable of accurately obtaining the impact frequency of the rock drill.

Description

Technical Field

[0001] The present invention relates to the technical field of rock drill testing, and in particular to a method and system for testing the impact frequency of a hydraulic rock drill. Background Art

[0002] A rock drill is a machine that uses a reversing valve to control the reciprocating impact of an impact piston inside a cylinder. The impact frequency of a rock drill, that is, the number of external impacts of the impact piston per unit time, is a key parameter that characterizes its impact capability. Accurately and quickly determining the impact frequency of a rock drill in operation is of great significance for testing, maintenance, and performance improvement of the rock drill.

[0003] Currently, the commonly used impact frequency testing methods include hydraulic method, electromagnetic induction method, and laser method; the hydraulic method uses a pressure sensor to detect the oil chamber connected to the impact piston in the rock drill or the high-pressure accumulator and low-pressure accumulator connected to the oil pipe, and calculates the impact frequency of the rock drill based on the pressure fluctuation period; the electromagnetic induction method uses an external coil to calculate the current generated when the piston passes through the coil to calculate the impact frequency; the laser method projects a laser onto the tail end face of the piston to measure the piston position and realize the calculation of the impact frequency.

[0004] However, these impact frequency testing methods in the existing technology still have shortcomings. The pressure sensor used in the hydraulic method needs to be directly connected to the internal oil circuit of the rock drill. The rock drill has a high working pressure and a large vibration frequency, which can easily cause damage to the sensor; the electromagnetic induction or laser method requires the piston to be exposed. For some rock drills where the impact piston cannot be exposed, these methods are not applicable.

[0005] Rock drills require sufficient energy to break rock, overcoming internal cohesive forces and friction between rock particles. The impact energy determines the amount of work each impact can do on the rock. The greater the impact energy, the more likely a single impact will create more fractures and more effectively break the rock, thereby increasing drilling speed and efficiency, helping to achieve desired drilling depths and other operational requirements in a shorter time. However, existing techniques for testing and calculating rock drill impact energy are complex, necessitating a solution. Summary of the Invention

[0006] The present invention aims to at least partially address one of the aforementioned technical problems in the prior art. To this end, one object of the present invention is to provide a method and system for testing the impact frequency of a hydraulic rock drill, which has a long service life, low cost, a wide range of applications, and can accurately measure the impact frequency of the rock drill.

[0007] The present invention solves the above technical problems with the following technical solutions: A method for testing the impact frequency of a hydraulic rock drill comprises the following steps:

[0008] Collect the sound generated by the rock drill when it is working and obtain audio information;

[0009] The audio information is processed using short-time Fourier transform to obtain a time-frequency spectrum of the audio information;

[0010] The real-time impact frequency of the rock drill is extracted based on the time-frequency spectrum.

[0011] The beneficial effects of the present invention are: no need to contact the rock drill, the radio module is not easily damaged and has a long service life; low cost, no need to expose the piston of the rock drill, and the impact frequency of the rock drill can be accurately obtained; wide range of application, and good universality to the structure of the rock drill.

[0012] On the basis of the above technical solution, the present invention can also be improved as follows.

[0013] Furthermore, the rock drill includes an impact part and an impacted part. When the impact part hits the impacted part, components in the impacted part collide, causing the shaft parts to vibrate and resonate, thereby generating sound, and the sound is collected to obtain audio information.

[0014] Furthermore, the sound receiving module for collecting audio information is placed on one side of the rock drill and is on the same horizontal line as the rock drill and the impacted part.

[0015] Furthermore, the window function used in the short-time Fourier transform is a Hamming window. The window function length is selected based on the sampling frequency of the acquisition device. When the sampling frequency is less than 11025 Hz, a narrow window is used, and when the sampling frequency is greater than 11025 Hz, a wide window is used. The overlap ratio between the window function and adjacent windows is 0.5.

[0016] The present invention offers the following advantages: It utilizes a non-contact acoustic detection method, eliminating the need for contact with the rock drill, making the receiver module less susceptible to damage and enabling accurate detection of the rock drill's impact frequency. It also offers advantages such as ease of installation, long service life, low cost, and high detection accuracy without requiring the rock drill's piston to be exposed. Furthermore, it has a wide range of applications and is well-suited to rock drill structures.

[0017] Another technical solution of the present invention to solve the above technical problems is as follows: a hydraulic rock drill impact frequency testing system, comprising:

[0018] A sound receiving module, which is used to collect the sound generated by the rock drill when it is working and obtain audio information;

[0019] A processing module, the processing module is used to process the audio information using short-time Fourier transform to obtain a time-frequency spectrum of the audio information;

[0020] An extraction module is used to extract the real-time impact frequency of the rock drill according to the time-frequency spectrum.

[0021] On the basis of the above technical solution, the present invention can also be improved as follows.

[0022] Furthermore, the rock drill includes an impact part and an impacted part. When the impact part hits the impacted part, the components in the impacted part collide, causing the shaft parts to vibrate and resonate, thereby generating sound. The sound receiving module collects the sound to obtain audio information.

[0023] Furthermore, the sound receiving modules are placed on both sides of the rock drill and are on the same horizontal line as the rock drill and the impacted part.

[0024] The beneficial effects of the present invention are: no contact with the rock drill is required, the radio module is not easily damaged, and the impact frequency of the rock drill can be accurately obtained. It has the advantages of easy installation, long service life, low cost, no need for the piston of the rock drill to be exposed, and high detection accuracy; it has a wide range of applications and good universality to the structure of the rock drill. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a method for testing the impact frequency of a hydraulic rock drill according to the present invention;

[0026] Figure 2 A flow chart for calculating the natural frequency of longitudinal vibration of a rock drill piston according to the present invention;

[0027] Figure 3 This is a module diagram of a hydraulic rock drill impact frequency testing system of the present invention.

[0028] Figure 4 It is a structural schematic diagram of the hydraulic rock drill of the present invention;

[0029] Figure 5 It is a structural schematic diagram of the radio module and the rock drill of the present invention;

[0030] Figure 6 for Figure 5 side view.

[0031] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0032] 1. Sound receiving module, 2. Processing module, 3. Extraction module;

[0033] 4. Rock drill, 401. Impact part, 402. Impacted part. DETAILED DESCRIPTION

[0034] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0035] like Figure 1 As shown, a method for testing the impact frequency of a hydraulic rock drill comprises the following steps:

[0036] Collect the sound generated by the rock drill 4 when it is working, collect two seconds of sound every ten seconds to obtain audio information;

[0037] The audio information is processed using short-time Fourier transform to obtain a time-frequency spectrum of the audio information;

[0038] Extracting the real-time impact frequency of the rock drill 4 according to the time-frequency spectrum;

[0039] Bandpass filtering is performed on the collected audio information at more than three times the impact frequency and more than two times the natural frequency to obtain the impact characteristic signal;

[0040] The impact characteristic signal is subjected to EMD decomposition to obtain the intrinsic mode function C(t), and the impact energy is calculated according to the intrinsic mode function C(t) to obtain the impact energy data.

[0041] Among them, EMD specifically stands for Empirical Mode Decomposition, and its Chinese name is empirical mode decomposition. It is an adaptive signal processing method, mainly used to analyze nonlinear and non-stationary signals.

[0042] Impact energy E i

[0043]

[0044] like Figure 2 As shown, the natural frequency of longitudinal vibration of the piston of the rock drill 4 is calculated;

[0045] When β approaches 0, the algorithm Calculate the natural frequency of the longitudinal vibration of the piston of rock drill 4;

[0046] When β does not tend to 0, the natural frequency of the longitudinal vibration of the rock drill 4 piston is calculated using the graphical method;

[0047] The sampling frequency should be set to more than twice the natural frequency.

[0048] γ=kl,

[0049] Where k is the piston stiffness, l is the piston length, and β is the ratio of the piston mass to the total mass of the object being impacted.

[0050] In the above embodiment, the rock drill 4 includes an impact part 401 and an impacted part 402. When the impact part 401 hits the impacted part 402, the components in the impacted part 402 collide, causing the shaft parts to vibrate and resonate, thereby generating sound, and the sound is collected to obtain audio information.

[0051] The impact part 401 in this embodiment is usually an impact piston, and the impacted part 402 is usually a drill rod or a connecting sleeve. When the impact part 401 hits the impacted part 402, all the shaft parts of the impacted part 402 will undergo double-end or single-end fixed forced vibration. For the shaft parts, the infinitesimal method is used to analyze and find that under the excitation of the circular frequency Ω, the shaft parts will generate vibrations that are integer multiples of this frequency, and the vibrations on the surface of the shaft parts will cause the surrounding air to resonate with the same frequency. This resonance is the sound that can be received by the human ear; the sound receiving module 1 collects the sound to obtain audio information.

[0052] In the above embodiment, the sound receiving module 1 for collecting audio information is placed on one side of the rock drill 4 and is on the same horizontal line as the rock drill 4 and the impacted part 402 .

[0053] In the above embodiment, the window function used in the short-time Fourier transform is a Hamming window; the window function length is selected according to the sampling frequency of the acquisition device. When the sampling frequency is less than 11025 Hz, a narrow window is selected, and when the sampling frequency is greater than 11025 Hz, a wide window is selected; the overlap rate between the window function and the adjacent window is 0.5.

[0054] In specific applications of this embodiment, the sound receiving module 1 is installed on an independent bracket, and then the independent bracket is placed at a suitable position outside the rock drill 4. The sound receiving module 1 is used to collect the sound generated by the rock drill 4 when it is working to obtain audio information; the processing module 2 is also used to process the audio information using short-time Fourier transform to obtain a time-frequency spectrum of the audio information; finally, the extraction module 3 is used to extract the real-time impact frequency of the rock drill 4 according to the time-frequency spectrum, thereby obtaining the impact frequency of the rock drill.

[0055] This embodiment uses a non-contact acoustic detection method, which does not require contact with the rock drill, and the radio module 1 is not easily damaged, so the impact frequency of the rock drill 4 can be accurately obtained. It has the advantages of easy installation, long service life, low cost, no need to expose the piston of the rock drill, and high detection accuracy. This embodiment has a wide range of applications and good universality for the structure of the rock drill. The impact energy calculation is simple and efficient.

[0056] Example 2:

[0057] like Figure 3 As shown, a hydraulic rock drill impact frequency testing system includes:

[0058] A sound receiving module 1, which is used to collect the sound generated by the rock drill 4 when it is working and obtain audio information;

[0059] Processing module 2, the processing module 2 is used to process the audio information using short-time Fourier transform to obtain a time-frequency spectrum of the audio information;

[0060] The extraction module 3 is used to extract the real-time impact frequency of the rock drill 4 according to the time-frequency spectrum.

[0061] In the above embodiment, Figure 4 As shown, the rock drill 4 includes an impact part 401 and an impacted part 402. When the impact part 401 hits the impacted part 402, the components in the impacted part 402 collide, causing the shaft parts to vibrate and resonate, thereby generating sound. The sound receiving module 1 collects the sound to obtain audio information.

[0062] In the above embodiment, Figure 5 and Figure 6 As shown, the sound receiving module 1 is placed on both sides of the rock drill 4 and is on the same horizontal line with the rock drill 4 and the impacted part 402.

[0063] In the specific application of this embodiment, the two sound receiving modules 1 should be placed on both sides of the rock drill 4, and each sound receiving module 1 should be more than 1 meter away from the impact point of the rock drill 4, that is, the connection point between the drill tail of the rock drill 4 and the drill rod. The sound receiving module 1 is on the same horizontal line as the rock drill 4 and the impacted part 402; Figure 5 and Figure 6 Where X and Y represent the distance between the radio module 1 and the rock drill 4, and Z represents the height of the radio module 1.

[0064] The sound generated by the rock drill 4 when it is working is collected by the sound receiving module 1 to obtain audio information; the audio information is processed by the processing module 2 using short-time Fourier transform to obtain a time-frequency spectrum of the audio information; finally, the real-time impact frequency of the rock drill 4 is extracted according to the time-frequency spectrum, thereby obtaining the impact frequency of the rock drill.

[0065] This embodiment does not require contact with the rock drill, and the radio module 1 is not easily damaged, so the impact frequency of the rock drill 4 can be accurately obtained. It has the advantages of easy installation, long service life, low cost, no need to expose the piston of the rock drill, and high detection accuracy. This embodiment has a wide range of applications and good universality for the structure of the rock drill. The impact energy calculation is simple and efficient.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for testing the impact frequency of a hydraulic rock drill, characterized in that: The following steps are involved: collecting the sound generated by the rock drill (4) when it is working to obtain audio information; The audio information is processed using short-time Fourier transform to obtain a time-frequency spectrum of the audio information; The real-time impact frequency of the rock drill (4) is extracted based on the time-frequency spectrum.

2. The hydraulic rock drill impact frequency testing method according to claim 1, characterized in that: The rock drill (4) comprises an impact part (401) and an impacted part (402). When the impact part (401) strikes the impacted part (402), components in the impacted part (402) collide, causing shaft parts to vibrate and resonate, thereby generating sound, and the sound is collected to obtain audio information.

3. The hydraulic rock drill impact frequency testing method according to claim 2, characterized in that: The sound receiving module (1) for collecting audio information is placed on one side of the rock drill (4) and is on the same horizontal line as the rock drill (4) and the impacted part (402).

4. The hydraulic rock drill impact frequency testing method according to claim 1, characterized in that: The window function used in the short-time Fourier transform is the Hamming window. The window function length is selected according to the sampling frequency of the acquisition device. When the sampling frequency is less than 11025 Hz, a narrow window is used, and when the sampling frequency is greater than 11025 Hz, a wide window is used. The overlap rate between the window function and the adjacent window is 0.

5.

5. A hydraulic rock drill impact frequency testing system, characterized in that: include: A sound receiving module (1), the sound receiving module (1) is used to collect the sound generated by the rock drill (4) when it is working, and obtain audio information; A processing module (2), the processing module (2) is used to process the audio information using a short-time Fourier transform to obtain a time-frequency spectrum of the audio information; An extraction module (3) is used to extract the real-time impact frequency of the rock drill (4) based on the time-frequency spectrum.

6. The hydraulic rock drill impact frequency testing system according to claim 5, characterized in that: The rock drill (4) comprises an impact part (401) and an impacted part (402). When the impact part (401) strikes the impacted part (402), components in the impacted part (402) collide, causing shaft parts to vibrate and resonate, thereby generating sound. The sound receiving module (1) collects the sound to obtain audio information.

7. The hydraulic rock drill impact frequency testing system according to claim 5, characterized in that: The sound receiving modules (1) are placed on both sides of the rock drill (4) and are on the same horizontal line as the rock drill (4) and the impacted part (402).

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