Foreign matter detection method for belt conveyor

Abstract

The invention discloses a foreign matter detection method for a belt conveyor, and belongs to the technical field of coal transportation metal detection. Comprising a fluxgate sensor and a signal acquisition unit. Wherein the fluxgate sensor and the signal acquisition unit are integrated into an integrated unit, and a Doppler array structure is constructed by a plurality of integrated units; the signal acquisition unit comprises an excitation signal generation part, a signal processing part, an AD acquisition part and a data processing algorithm part; according to the metal detection device, the magnetic sensor is fixed above the conveying belt through the non-magnetic support, magnetic field environment data generated when no abnormal metal exists serves as the background, magnetic abnormal signals generated by metal on the conveying belt below are detected through the magnetic sensor, and local voice alarm is accessed locally or a sealing-tape machine is controlled to stop. Iron metal in the coal flow is detected, the relative size of the iron metal and the relative position after shutdown are judged, and identification is more accurate.

Description

Technical Field

[0001] The invention provides a method for detecting foreign matter in a belt conveyor, and belongs to the technical field of metal detection in coal transportation. Background Art

[0002] In mining operations, the conveyor belt coal flow is often mixed with various metals of different sizes, such as anchor rods, anchor cables, pallets, coal mining machine picks, equipment fasteners that have fallen off, tools left behind by workers, etc. On the other hand, the iron remover cannot effectively remove large pieces of metal passing through the belt, and these large pieces of metal can easily cause longitudinal tearing of the conveyor belt. If they enter the crusher, they will damage it, resulting in downtime or even production suspension, affecting the company's benefits.

[0003] To avoid the above problems, existing metal detection technologies often include balanced coil detection technology and resonant detection technology. The principle of balanced coil detection technology is to convert the change of inductance and resistance into the change of voltage, and achieve the detection purpose by detecting the voltage; however, due to the large difference in the electromagnetic properties of the metal or material being detected, and the inductance and resistance change factors in the voltage change cannot be independent, which brings limitations to improving the detection accuracy and broadening the application occasions.

[0004] Resonance detection technology is the technology used by common metal detectors. Usually, metal detectors use sinusoidal oscillation circuits as sensor probes. Due to interference from the surrounding environment, the working point drifts, and oscillation distortion or vibration stops easily, which can lead to system instability, large test errors, and other consequences, resulting in missed reports and false reports. In view of the above problems, a more accurate and convenient method for detecting foreign objects in belt conveyors is needed. Summary of the invention

[0005] In order to solve the above problems, the technical scheme proposed by the present invention is: a method for detecting foreign matter in a belt conveyor, comprising a fluxgate sensor and a signal acquisition unit; wherein the fluxgate sensor and the signal acquisition unit are integrated into an integrated unit, and a Doppler array structure is constructed by multiple integrated units; the signal acquisition unit comprises: an excitation signal generating part, a signal processing part, an AD acquisition part, and a data processing algorithm part; the specific working steps of the signal acquisition unit are: S1, using a probe to detect the system magnetic field to generate an excitation signal; S2, using the signal processing part and the AD acquisition part to process and collect the excitation signal; S3, using the data processing algorithm part to perform DSP algorithm processing on the data obtained in S2; S4, transmitting the data processing result obtained in S3 to a host computer for display in real time through a Bluetooth serial port.

[0006] As an improvement, in step S1, a dual-core fluxgate sensor with a parallel structure is used as a probe of the system magnetic field, and an excitation signal is applied to the dual-core fluxgate sensor. When the probe core reaches saturation, the magnetic field signal to be measured is modulated, thereby generating an induced electromotive force reflecting the strength of the ambient magnetic field, and the strength of the ambient magnetic field is characterized by analyzing the induced signal.

[0007] As an improvement, two single-core probes placed in parallel are designed, with the excitation coils connected in series in anti-phase and the induction coils connected in series in phase, so as to offset the induced electromotive force generated by the transformer effect and superimpose the fluxgate signal.

[0008] As an improvement, in step S2, the signal processing part uses a harmonic selection method, in which even harmonics are proportional to the magnetic field strength, and the signal processing part completes the detection and extraction of harmonics; at the same time, the AD acquisition part can convert the analog signal of the harmonic into a digital signal.

[0009] As an improvement, in step S3, an excitation square wave signal is generated by DSP and the phase is adjusted, and a power amplifier chip MIC4428 is added after the excitation signal for power amplification; after the excitation signal is input from two paths, the output signal is loaded on both ends of the fluxgate excitation coil, and the excitation coil causes the magnetic core to enter the saturation region.

[0010] As an improvement, in step S3, the data processing algorithm part is connected to the alarm module circuit of the system itself.

[0011] Beneficial effects of the present invention:

[0012] The detection mechanism is simple as a whole and can detect metal substances mixed in coal in time, especially for long metals such as anchor rods, and can alarm in time. The metal detection device of this scheme uses a non-magnetic bracket to fix the magnetic sensor above the conveyor belt. The magnetic field environment data when there is no abnormal metal is used as the background. The magnetic sensor detects the magnetic abnormality signal generated by the metal on the conveyor belt below, and connects to the local voice alarm or controls the belt conveyor to stop. Detect iron metal in the coal flow and determine its relative size and relative position after shutdown. Compared with traditional metal detectors, the identification is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a structural diagram of the signal acquisition unit of the present invention.

[0014] Figure 2 It is a working schematic diagram of the dual-core fluxgate sensor of the present invention.

[0015] Figure 3 It is a schematic diagram of the integrated fluxgate external magnetic field emission unit of the present invention.

[0016] Figure 4A state diagram showing the relationship between the external magnetic field, the signal acquisition unit and the metal object of the present invention.

[0017] Figure 5 It is a schematic diagram of the integrated unit of the present invention.

[0018] Figure 6 Schematic diagram of the integrated Doppler array of the present invention.

[0019] Figure 7 This is a diagram showing the dynamic test results of the metal rod of the present invention.

[0020] Figure 8 This is a static test result diagram of the metal rod of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings.

[0022] according to Figure 1-6 As shown: The present invention provides a method for detecting foreign matter in a belt conveyor: comprising a fluxgate sensor and a signal acquisition unit; wherein the fluxgate sensor and the signal acquisition unit are integrated into an integrated unit, and a Doppler array structure is constructed by multiple integrated units, such as Figure 5-6 As shown;

[0023] like Figure 1 As shown, the signal acquisition unit includes: an excitation signal generating part, a signal processing part, an AD acquisition part, and a data processing algorithm part; the specific working steps of the signal acquisition unit are: S1, using a probe to detect the system magnetic field to generate an excitation signal; S2, using the signal processing part and the AD acquisition part to process and collect the excitation signal; S3, using the data processing algorithm part to perform DSP algorithm processing on the data obtained in S2; S4, transmitting the data processing results obtained in S3 to the host computer for display in real time through the Bluetooth serial port.

[0024] like Figure 2 The schematic diagram of the dual-core fluxgate sensor is shown in Figure 1. In step S1, a dual-core fluxgate sensor with a parallel structure is used as the probe of the system magnetic field. An excitation signal is applied to the dual-core fluxgate sensor. When the probe core reaches saturation, the magnetic field signal to be measured is modulated, thereby generating an induced electromotive force reflecting the strength of the environmental magnetic field. The strength of the environmental magnetic field is characterized by analyzing the induced signal. Two single-core probes placed in parallel are designed, with the excitation coils connected in series in opposite phases and the induction coils connected in series in the same phase, so as to offset the induced electromotive force generated by the transformer effect and superimpose the fluxgate signal.

[0025] In step S2, the signal processing part uses the harmonic selection method. In the harmonic selection method, the even harmonics are proportional to the magnetic field strength. The signal processing part completes the detection and extraction of the harmonics; at the same time, the AD acquisition part can convert the analog signal of the harmonic into a digital signal.

[0026] In step S3, the excitation square wave signal is generated by DSP and the phase is adjusted. The power amplifier chip MIC4428 is added after the excitation signal for power amplification; MIC4428 is a push-pull structure MOSFET driver chip with high power and low distortion. After the excitation signal is input from two channels, the output signal is loaded on both ends of the fluxgate excitation coil, and the excitation coil causes the magnetic core to enter the saturation zone.

[0027] In step S3, the data processing algorithm part is connected to the alarm module circuit of the system itself.

[0028] like Figure 5-6 As shown, when the method provided in the present application works normally, the fluxgate sensor and the signal acquisition unit are integrated into an integrated unit, and a Doppler array structure is constructed by multiple integrated units; each integrated unit works independently, and performs transmission and receiving operations in sequence in the array, and performs partitioned detection and reception of the conveyor belt carrying medium from top to bottom, and forms a scanning array in combination with the movement of the conveyor belt to detect magnetic field change information, thereby finding metal objects and making preliminary shape judgments on the metal objects.

[0029] The external field excitation coil, signal acquisition unit and shielding cover of this system are integrated into one. Figure 3 shown.

[0030] Test verification

[0031] 1. Dynamic testing

[0032] The test was conducted on a belt conveyor using a 0.5-meter-long, 5-cm-diameter metal rod with a belt speed of 3.5 m / s. The metal rod slid back and forth, and the accuracy rate reached 92.5%. Figure 7 This is a diagram of the dynamic test results of the metal rod.

[0033] 2. Static test

[0034] The test was conducted on a belt conveyor using a metal rod of 1 meter in length and 5 cm in diameter. The metal rod was slid back and forth for the test, and the accuracy rate reached 100%. Figure 8 This is a diagram of the static test results of a metal rod.

[0035] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A method for detecting foreign matter in a belt conveyor, characterized in that: It includes a fluxgate sensor and a signal acquisition unit; wherein the fluxgate sensor and the signal acquisition unit are integrated into an integrated unit, and a Doppler array structure is constructed by multiple integrated units; the signal acquisition unit includes: an excitation signal generating part, a signal processing part, an AD acquisition part, and a data processing algorithm part; the specific working steps of the signal acquisition unit are: S1, using a probe to detect the system magnetic field to generate an excitation signal; S2, using the signal processing part and the AD acquisition part to process and collect the excitation signal; S3, using the data processing algorithm part to perform DSP algorithm processing on the data obtained in S2; S4, transmitting the data processing results obtained in S3 to the host computer for display in real time through the Bluetooth serial port.

2. A method for detecting foreign matter in a belt conveyor according to claim 1, characterized in that: In step S1, a dual-core fluxgate sensor with a parallel structure is used as a probe of the system magnetic field. An excitation signal is applied to the dual-core fluxgate sensor. When the probe core reaches saturation, the magnetic field signal to be measured is modulated, thereby generating an induced electromotive force reflecting the strength of the ambient magnetic field. The strength of the ambient magnetic field is characterized by analyzing the induced signal.

3. A method for detecting foreign matter in a belt conveyor according to claim 2, characterized in that: Two single-core probes placed in parallel are designed, with the excitation coils connected in series in anti-phase and the induction coils connected in series in phase, so as to offset the induced electromotive force generated by the transformer effect and superimpose the fluxgate signal.

4. A method for detecting foreign matter in a belt conveyor according to claim 1, characterized in that: In step S2, the signal processing part uses the harmonic selection method. In the harmonic selection method, the even harmonics are proportional to the magnetic field strength. The signal processing part completes the detection and extraction of the harmonics; at the same time, the AD acquisition part can convert the analog signal of the harmonic into a digital signal.

5. A method for detecting foreign matter in a belt conveyor according to claim 1, characterized in that: In step S3, an excitation square wave signal is generated by DSP and the phase is adjusted, and a power amplifier chip MIC4428 is added after the excitation signal for power amplification; after the excitation signal is input from two channels, the output signal is loaded on both ends of the fluxgate excitation coil, and the excitation coil causes the magnetic core to enter the saturation zone.

6. A method for detecting foreign matter in a belt conveyor according to claim 1, characterized in that: In step S3, the data processing algorithm part is connected to the alarm module circuit of the system itself.

Images