Metal detection device and method for magnetic material

Abstract

The invention provides a metal detection device and method for magnetic materials, and belongs to the technical field of metal detection. The metal detection device comprises a uniform magnetic field generation device, a belt joint identification unit, a signal processing unit and an alarm unit; the signal processing unit collects an oscillating current signal in real time and extracts the amplitude of the oscillating current as a background signal; setting an initial alarm threshold value of the metal according to the fluctuation amplitude of the background signal; when the magnetic material is mixed into the metal, the amplitude of the oscillating current instantaneously exceeds an initial alarm threshold value to trigger an alarm; the signal processing unit is connected with the belt joint recognition unit, when the belt joint signal is received, the alarm threshold value of metal is adjusted to be higher than the initial alarm threshold value, and after the belt joint is far away, the alarm threshold value of metal impurities is recovered to the initial alarm threshold value. Interference of the steel wire rope core conveying belt and the magnetic materials can be effectively restrained, and therefore accurate detection of metal impurities is achieved under the working condition that the steel wire rope core conveying belt conveys various magnetic materials.

Description

Technical Field

[0001] The present invention relates to the technical field of metal detection, and in particular to a metal detection device and method for magnetic materials. Background Art

[0002] In industrial and mining enterprises, belt conveyor metal detectors can detect harmful metals in the belt conveyor system to prevent these metals from damaging the conveyor belt or getting stuck in the machine, thereby reducing the risk of accidents; by timely detecting and eliminating metal impurities, metal detectors help protect downstream equipment from damage, such as crushers, grinders, etc.; metal detectors can monitor harmful metals in material flows in real time, promptly warn and eliminate potential hazards, reduce unexpected downtime and maintenance requirements, and thus improve overall production efficiency.

[0003] However, when the material flow on the conveyor belt is high-grade (≥60%) iron ore, iron ore and other magnetic material flow, due to the magnetic properties of iron ore and iron ore, they can generate interference signals and affect the accuracy of the metal detector. This interference may cause the detector to falsely report or miss reports. The presence of iron ore and iron ore may affect the sensitivity of the metal detector, reducing its ability to detect metals. In some cases, the strong magnetic field of iron ore and iron ore may prevent the metal detector from working properly, limiting its application in specific environments.

[0004] Among the existing technical solutions for metal detectors, the IB (Induction Balance) metal detector uses the induction balance principle and is mainly composed of a transmitting coil and a receiving coil. The transmitting coil is installed above the conveyor belt, and the receiving coil is installed below the conveyor belt. The electromagnetic field generated by the transmitting coil is affected by the metal object, and the signal captured by the receiving coil can be processed to determine the presence of metal. However, this type of metal detector cannot eliminate the interference caused by iron ore, iron ore and steel cord conveyor belts. Therefore, the IB metal detector cannot be used under steel cord conveyor belt conditions and iron ore and iron ore conditions. Summary of the invention

[0005] In view of this, the present invention proposes a metal detection device and method for magnetic materials, aiming to solve the problem that metal impurities in existing magnetic materials are difficult to accurately detect.

[0006] In one aspect, the present invention provides a metal detection device for magnetic materials, comprising: a uniform magnetic field generating device, a belt joint identification unit, a signal processing unit and an alarm unit; wherein the uniform magnetic field generating device is installed in cooperation with a steel cord conveyor belt for conveying magnetic materials, and is used to generate a uniform alternating magnetic field in the peripheral space where the steel cord conveyor belt travels by using an oscillating current, so that the steel cord conveyor belt passes through the alternating magnetic field on its running path; The belt joint identification unit is arranged on the running path of the steel cord conveyor belt, located at the front end of the uniform magnetic field generating device, and located below the steel cord conveyor belt, for detecting the belt joint signal of the steel cord conveyor belt and transmitting it to the signal processing unit; The signal processing unit is connected to the uniform magnetic field generating device, and is used for collecting the oscillating current signal generated by the uniform magnetic field generating device in real time, and extracting the amplitude of the oscillating current signal to construct a background signal; when the steel rope core conveyor belt starts to transport magnetic materials and passes through the alternating magnetic field generated by the uniform magnetic field generating device, the background signal starts to fluctuate, and the fluctuation amplitude of the background signal is proportional to the jitter amplitude of the steel rope core conveyor belt and the instantaneous flow rate of the magnetic material; when the background signal starts to fluctuate, the initial alarm threshold of the metal impurities is set according to the fluctuation amplitude of the background signal; the signal processing unit is also used for generating an alarm trigger signal when the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, thereby prompting that metal impurities are mixed in the magnetic material; The signal processing unit is also connected to the belt joint identification unit to receive the belt joint signal sent by the belt joint identification unit, adjust the alarm threshold of metal impurities to be higher than the initial alarm threshold according to the belt joint signal, and restore the alarm threshold of metal impurities to the initial alarm threshold after the belt joint is away from the uniform magnetic field generating device; and generate an alarm trigger signal when the amplitude of the background signal is instantaneously higher than the adjusted alarm threshold to prompt that metal impurities have fallen into the belt joint area; the alarm unit is connected to the signal processing unit.

[0007] Furthermore, in the above-mentioned metal detection device for magnetic materials, the uniform magnetic field generating device comprises: an oscillating circuit, a first coil and a second coil; wherein the first coil and the second coil are arranged in parallel along the running direction of the steel cord conveyor belt, and the first coil and the second coil are distributed on the upper and lower sides of the steel cord conveyor belt; The oscillation circuit is connected to both the first coil and the second coil to provide an oscillation current to the first coil and the second coil, thereby generating a uniform alternating magnetic field between the first coil and the second coil.

[0008] Furthermore, in the above-mentioned metal detection device for magnetic materials, there are multiple first coils and multiple second coils, and the first coils and the second coils are arranged in a one-to-one correspondence, and each pair of the first coils and the second coils forms a matrix arrangement.

[0009] Furthermore, in the above-mentioned metal detection device for magnetic materials, the uniform magnetic field generating device includes: an oscillation circuit, a third coil and a fourth coil; wherein the third coil and the fourth coil pass through the steel wire core conveyor belt in a direction perpendicular to the running path of the steel wire core conveyor belt, and the third coil and the fourth coil are arranged at a preset distance front and back along the conveying path of the steel wire core conveyor belt; the oscillation circuit is connected to both the third coil and the fourth coil to provide an oscillating current to the third coil and the fourth coil, thereby generating a uniform alternating magnetic field between the third coil and the fourth coil.

[0010] Furthermore, in the above-mentioned metal detection device for magnetic materials, when the uniform magnetic field generating device and the steel rope core conveyor belt are in a relatively static state, the background signal is a straight line.

[0011] Furthermore, the above-mentioned metal detection device for magnetic materials also includes: a protective cover; wherein the protective cover is arranged outside the uniform magnetic field generating device to protect the internal components of the uniform magnetic field generating device from the influence of the external environment.

[0012] Furthermore, in the above-mentioned metal detection device for magnetic materials, the signal processing unit includes: a signal conditioning circuit unit, an ADC sampling circuit unit and an MCU processor circuit unit; wherein the signal conditioning circuit unit is connected to the uniform magnetic field generating device, and is used to obtain the amplitude of the oscillating current signal in the uniform magnetic field generating device, and construct a background signal for metal impurity detection based on the amplitude of the oscillating current signal; The ADC sampling circuit unit is connected to the signal conditioning circuit unit and is used to convert the collected background signal into a digital signal; The MCU processor circuit unit is connected to the ADC sampling circuit unit and the belt joint identification unit, and is used for receiving the background signal and the belt joint signal and processing them.

[0013] Furthermore, in the above-mentioned metal detection device for magnetic materials, the alarm unit includes: an alarm output circuit; wherein the input end of the alarm output circuit is connected to the signal processing unit; and the output end of the alarm output circuit is connected to an external iron removal device or a warning device.

[0014] Furthermore, the above-mentioned metal detection device for magnetic materials also includes: a human-computer interaction unit; wherein the human-computer interaction unit is connected to the signal processing unit, and is used to display the fluctuation amplitude of the background signal and set the initial alarm threshold of metal impurities, display the alarm output status and the number of alarms.

[0015] The present invention generates a uniform alternating magnetic field on the conveying path of a steel rope core conveyor belt conveying magnetic materials through a uniform magnetic field generating device, and sets and adjusts the alarm threshold of metal impurities according to the fluctuation amplitude of the background signal caused when the steel rope core conveyor belt conveys the magnetic materials through the alternating magnetic field, thereby avoiding the influence of the interference signal of the magnetic material and the steel rope core conveyor belt itself on the detection result; since the alternating magnetic field generated by the uniform magnetic field generating device is a uniform magnetic field, the sudden change of the magnetic field will be reduced, thereby reducing the fluctuation of the background signal, and effectively suppressing the interference of the steel rope core conveyor belt and the magnetic material; the signal processing unit adjusts the alarm threshold of the metal impurities to be higher than the initial alarm threshold according to the received belt joint signal, and generates an alarm trigger signal when the amplitude of the collected background signal exceeds the initial alarm threshold, which, on the one hand, filters out the false alarm caused by the belt joint, and on the other hand, can effectively detect the metal impurities in the magnetic material to avoid the situation of missed alarm.

[0016] On the other hand, the present invention also proposes a metal detection method for magnetic materials, using the metal detection device for magnetic materials as described above, comprising: The oscillating current signal in the uniform magnetic field generating device is collected in real time, and a background signal is constructed according to the amplitude change of the oscillating current signal; when the steel cord conveyor belt starts to transport magnetic materials and passes through the alternating magnetic field, the background signal starts to fluctuate, and the fluctuation amplitude of the background signal is proportional to the vibration amplitude of the steel cord conveyor belt and the instantaneous flow rate of the magnetic materials; when the background signal starts to fluctuate, the initial alarm threshold of the metal impurities is set according to the fluctuation amplitude of the background signal; When the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, an alarm trigger signal is generated, indicating that the magnetic material is mixed with metal impurities; When a belt joint signal is received, the alarm threshold of metal impurities is adjusted to be higher than the initial alarm threshold according to the belt joint signal, and after the belt joint is away from the uniform magnetic field generating device, the alarm threshold of metal impurities is restored to the initial alarm threshold; when the amplitude of the background signal exceeds the adjusted alarm threshold, an alarm trigger signal is generated to indicate that metal impurities have fallen into the belt joint, and is sent to the alarm unit for alarm action.

[0017] The metal detection method for magnetic materials provided by the present invention sets the initial alarm threshold of metal impurities according to the fluctuation amplitude of the background signal constructed when the steel wire core conveyor belt and the magnetic material pass through the alternating magnetic field generated by the uniform magnetic field generating device, and generates an alarm trigger signal when the received oscillating current signal intensity exceeds the initial alarm threshold of the metal impurities, indicating that the magnetic material is mixed with metal impurities; and the alarm threshold of the metal impurities is short-term adjusted to be higher than the initial alarm threshold according to the received belt joint signal; and when the received oscillating current signal intensity exceeds the adjusted alarm threshold, an alarm trigger signal is generated, indicating that metal impurities have fallen into the belt joint portion, which can effectively suppress the interference between the steel wire core conveyor belt and the magnetic material, thereby realizing the accurate detection of metal impurities in the magnetic material under the working condition that the steel wire core conveyor belt transports the magnetic material (such as iron ore concentrate, iron ore). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: Figure 1 A schematic structural diagram of a metal detection device for magnetic materials provided by an embodiment of the present invention; Figure 2 A structural block diagram of a metal detection device for magnetic materials provided by an embodiment of the present invention; Figure 3 A schematic structural diagram of a uniform magnetic field generating device in a metal detection device for magnetic materials provided by an embodiment of the present invention; Figure 4 Another structural schematic diagram of a uniform magnetic field generating device of a metal detection device for magnetic materials provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0020] Device Example: See also Figure 1 and Figure 2The metal detection device for magnetic materials of the embodiment of the present invention comprises: a uniform magnetic field generating device 1, a belt joint identification unit 4, a signal processing unit 3 and an alarm unit 5; wherein the uniform magnetic field generating device 1 is installed in cooperation with a steel cord conveyor belt 2 for transporting magnetic materials, so as to generate a uniform alternating magnetic field in the peripheral space where the steel cord conveyor belt 2 travels, so that the steel cord conveyor belt 2 for transporting magnetic materials passes through the alternating magnetic field on its running path; the belt joint identification unit 4 is arranged at a position at the front end of the uniform magnetic field generating device 1 on the running path of the steel cord conveyor belt 2, and is located below the steel cord conveyor belt 2, so as to detect the belt joint signal of the steel cord conveyor belt 2, and transmit the detected belt joint signal to the signal processing unit 3; the signal processing unit 3 is connected to the uniform magnetic field generating device 1, and is used to collect the oscillating current signal generated by the uniform magnetic field generating device 1 in real time, and extract the amplitude of the oscillating current signal to construct a background signal; when the steel cord conveyor belt 2 starts to transport magnetic materials, ... and is When the material passes through the alternating magnetic field generated by the uniform magnetic field generating device 1, the background signal begins to fluctuate, and the fluctuation amplitude of the background signal is proportional to the jitter amplitude of the steel wire core conveyor belt 2 and the instantaneous flow rate of the magnetic material; when the background signal begins to fluctuate, the initial alarm threshold of the metal impurities is set according to the fluctuation amplitude of the background signal; the signal processing unit 3 is also used to generate an alarm trigger signal when the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, thereby prompting that metal impurities are mixed in the magnetic material; the signal processing unit 3 is also connected to the belt joint identification unit 4 to receive the belt joint signal sent by the belt joint identification unit 4, and when the belt joint signal is received, the alarm threshold of the metal impurities is adjusted to be higher than the initial alarm threshold according to the belt joint signal, and after the belt joint is away from the uniform magnetic field generating device 1, the alarm threshold of the metal impurities is restored to the initial alarm threshold; and when the amplitude of the background signal is instantaneously higher than the adjusted alarm threshold, an alarm trigger signal is generated to prompt that metal impurities have fallen into the belt joint part; The alarm unit 5 is connected to the signal processing unit 3 to receive the alarm trigger signal sent by the signal processing unit 3 and perform an alarm action accordingly.

[0021] Specifically, the uniform magnetic field generating device 1 may be a Helmholtz coil. Preferably, the uniform magnetic field generating device 1 may be composed of an oscillating circuit 10 and a plurality of Helmholtz coils, so as to generate an oscillating current and an alternating magnetic field between the Helmholtz coils. The alternating magnetic field may be a sinusoidal alternating magnetic field.

[0022] The magnetic material in this embodiment may include iron ore and iron concentrate of various grades.

[0023] The Helmholtz coil can make the magnetic field change experienced by the steel cord conveyor belt 2 transporting magnetic materials through the coil relatively gentle. The Helmholtz coil has a uniform magnetic field, which can reduce the sudden change of the magnetic field relative to the moving steel cord conveyor belt 2 and the magnetic material flow, thereby reducing the fluctuation of the background signal and effectively suppressing the interference between the steel cord conveyor belt 2 and the iron ore concentrate.

[0024] It should be noted that the magnetic material in “taking the oscillating current signal when the steel cord conveyor belt 2 and the magnetic material pass through the alternating magnetic field as the background signal” does not include metal impurities.

[0025] The signal processing unit 3 collects the oscillating current signal generated by the uniform magnetic field generating device 1 in real time, and extracts the amplitude of the oscillating current signal to construct a background signal. The fluctuation amplitude of the background signal can be regarded as a curve of the oscillating current amplitude changing with time.

[0026] In this embodiment, when the uniform magnetic field generating device 1 and the steel wire core conveyor belt 2 are in a relatively static state, the background signal is a straight line; when the steel wire core conveyor belt 2 starts to transport magnetic materials and passes through the alternating magnetic field generated by the uniform magnetic field generating device 1, the background signal starts to fluctuate, and the fluctuation amplitude of the background signal is proportional to the jitter amplitude of the steel wire core conveyor belt 2 and the instantaneous flow rate of the magnetic material. In practical applications, the average value of each amplitude of the background signal can be used as the initial warning threshold. According to the specific situation on site, the initial alarm threshold can be adjusted up and down to adapt to different environmental conditions and requirements. For example, for large-volume magnetic materials and steel wire core conveyor belts with large jitter amplitudes, the alarm threshold can be adjusted to a certain range higher than the initial alarm threshold. In this way, the initial alarm threshold can be flexibly set according to the grade of iron ore concentrate and iron ore, and the accurate detection of harmful metal impurities in various grades of iron ore concentrate and iron ore can be achieved, and even the detection of harmful metal impurities (including magnetic metals and non-magnetic metals) in high-grade (≥60%) iron ore concentrate and iron ore can be achieved, and alarm output can be performed according to the detection results.

[0027] When the steel cord conveyor belt 2 and the magnetic material pass through the alternating magnetic field generated by the uniform magnetic field generating device 1, the oscillating current amplitude will fluctuate. The stronger the magnetism of the magnetic material flow and the greater the vibration amplitude of the steel cord, the more obvious the fluctuation of the oscillating current amplitude. Therefore, the initial alarm threshold of metal impurities is set according to the fluctuation amplitude of the background signal. In this embodiment, the fluctuation amplitude of the background signal is always smaller than the initial alarm threshold, and the alarm will not be triggered when the magnetic material flow and the steel cord conveyor belt 2 pass through the uniform magnetic field generating device 1. When metal impurities are mixed into the magnetic material, the fluctuation amplitude of the background signal instantly exceeds the initial alarm threshold and triggers an alarm.

[0028] Since the belt joint of the steel cord conveyor belt 2 contains a large amount of metal, a false alarm will be triggered when the belt joint passes through the uniform magnetic field generating device 1, which is not allowed in the production process. In this embodiment, the signal processing unit 3 is connected to the belt joint identification unit 4, and the metal impurity alarm threshold can be adjusted so that the alarm will not be triggered when the belt joint passes through the uniform magnetic field generating device 1. Only when metal happens to fall on the belt joint, the amplitude of the background signal will instantly exceed the adjusted alarm threshold to trigger the alarm.

[0029] The belt joint identification unit 4 can be a photoelectric sensor, a magnetic sensor, a visual sensor or an ultrasonic sensor, which can be installed on one side below the steel wire core conveyor belt 2 and located at the front end of the uniform magnetic field generating device 1 through a bracket. The signal processing unit 3 can dynamically adjust the alarm threshold of metal impurities according to the received belt joint signal, so that the background signal is temporarily lower than the metal alarm threshold, so that the alarm will not be triggered. After the belt joint leaves the rectangular Helmholtz coil, the alarm threshold of metal impurities is restored to the previous initial alarm threshold. At the same time, when metal happens to fall on the belt joint, the amplitude of the background signal will instantly exceed the adjusted alarm threshold, and a trigger alarm signal will be generated. On the one hand, it effectively filters out the false alarms caused by the belt joint, and on the other hand, if metal happens to fall on the belt joint, the metal can still be detected without missing alarms.

[0030] Continue reading Figure 2 In this embodiment, the signal processing unit 3 includes: a signal conditioning circuit unit 31, an ADC sampling circuit unit 32 and an MCU processor circuit unit 33; wherein the signal conditioning circuit unit 31 is connected to the uniform magnetic field generating device 1, and is used to obtain the amplitude of the oscillating current signal in the uniform magnetic field generating device 1, and construct a background signal for metal detection based on it; the ADC sampling circuit unit 32 is connected to the signal conditioning circuit unit 31, and is used to convert the collected background signal into a digital signal; the MCU processor circuit unit 33 is connected to the ADC sampling circuit unit 32 and the belt joint identification unit 4, and is used to receive the background signal and the belt joint signal and process them.

[0031] Specifically, the signal conditioning circuit unit 31 is composed of a peak detection circuit 311, a filter circuit 312 and an amplifier circuit 313, and its function is to obtain the background signal of metal detection. Among them: the peak detection circuit 311 is connected to the oscillation circuit 10, and is used to extract the peak value of the oscillation current. The filter circuit 312 is a second-order low-pass filter circuit, which is used to filter out the high-frequency components in the peak signal. The amplifier circuit 313 is a proportional amplifier circuit, which is used to amplify the low-frequency peak signal, thereby forming the final metal detection background signal and transmitting it to the ADC sampling circuit unit 32. The ADC sampling circuit unit 32 is used to convert the conditioned background signal into a digital signal and provide it to the MCU processor circuit unit 33.

[0032] The MCU processor circuit unit 33 uses an STM32H7B0 or ​​STM32H750 chip, and is responsible for digital signal processing of the background signal and the belt connector signal transmitted by the ADC sampling circuit unit 32, setting a suitable alarm threshold, and determining whether metal is present.

[0033] Of course, the signal processing unit 3 may also include: a housing (not shown in the figure); wherein the signal conditioning circuit unit 31, the ADC sampling circuit unit 32 and the MCU processor circuit unit 33 are placed inside the housing. The housing adopts an IP68 waterproof aluminum housing, and the width×height×depth of the housing is 290×186×73mm. The touch screen is embedded in the panel of the waterproof aluminum housing, and the wiring method adopts a waterproof aviation plug.

[0034] In this embodiment, the alarm unit 5 includes: an alarm output circuit; wherein the input end of the alarm output circuit is connected to the MCU processor circuit unit 33 of the signal processing unit 3, and is used to receive the alarm trigger signal sent by the MCU processor circuit unit 33; the output end of the alarm output circuit is connected to an external iron removal device or warning device, and is used to send an alarm signal when receiving the alarm trigger signal sent by the MCU processor circuit unit 33.

[0035] The alarm output circuit adopts two output modes to meet the needs of different working conditions, one is passive output and the other is active output. The passive output is a relay output mode, and the active output adopts a solid-state relay output mode. The passive output is used for interlocking iron removal equipment such as iron removers and metal separators, and the active output is used to directly drive warning devices such as alarm lights.

[0036] This embodiment may further include: a memory (not shown in the figure); wherein the memory is connected to the signal processing unit 3 and is used to store configuration parameters, historical records and processing results.

[0037] In this embodiment, it also includes: a human-computer interaction unit 6; wherein the human-computer interaction unit 6 is connected to the signal processing unit 3, and is used to display the fluctuation amplitude of the background signal and set the initial alarm threshold of metal impurities, display the alarm output status and the number of alarms.

[0038] Specifically, the human-computer interaction unit 6 may be a touch screen.

[0039] It can be obviously concluded from the above that the metal detection device for magnetic materials provided in this embodiment generates a uniform alternating magnetic field on the conveying path of the steel wire core conveyor belt 2 that conveys the magnetic material through the uniform magnetic field generating device 1, and sets and adjusts the alarm threshold of metal impurities according to the fluctuation amplitude of the background signal caused when the steel wire core conveyor belt 2 conveys the magnetic material through the alternating magnetic field, which can avoid the influence of the interference signal of the magnetic material and the steel wire core conveyor belt 2 itself on the detection result; since the alternating magnetic field generated by the uniform magnetic field generating device 1 is a uniform magnetic field, the sudden change of the magnetic field will be reduced, thereby reducing the fluctuation of the background signal, and effectively suppressing the interference between the steel wire core conveyor belt 2 and the magnetic material; the signal processing unit 3 adjusts the alarm threshold of the metal impurities to be higher than the initial alarm threshold according to the received belt joint signal, and generates an alarm trigger signal when the amplitude of the collected background signal exceeds the initial alarm threshold, which on the one hand filters out the false alarm caused by the belt joint, and on the other hand can also effectively and accurately detect the metal impurities in the magnetic material to avoid the situation of missed alarm.

[0040] Combination Figure 2 and Figure 3 In a specific implementation of the present embodiment, the uniform magnetic field generating device 1 comprises: an oscillating circuit 10, a first coil 11 and a second coil 12; wherein the first coil 11 and the second coil 12 are arranged in parallel along the running direction of the steel wire rope core conveyor belt 2, and the first coil 11 and the second coil 12 are distributed on the upper and lower sides of the steel wire rope core conveyor belt 2; the oscillating circuit 10 is connected to both the first coil 11 and the second coil 12 to provide an oscillating current to the first coil 11 and the second coil 12, thereby generating a uniform alternating magnetic field between the first coil 11 and the second coil 12.

[0041] Preferably, the first coil 11 and the second coil 12 are both multiple, and the first coil 11 and the second coil 12 are arranged one by one, and each pair of the first coil 11 and the second coil 12 forms a matrix arrangement. More specifically, each first coil 11 is arranged in a collinear manner, and each second coil 12 is arranged in a collinear manner. The spacing between two adjacent first coils 11 and the spacing between two adjacent second coils 12 are as small as possible to reduce the detection blind area.

[0042] More specifically, the first coil 11 and the second coil 12 are rectangular, square, triangular or circular Helmholtz coils.

[0043] Preferably, the first coil 11 and the second coil 12 are rectangular. The rectangular Helmholtz coils are arranged in a matrix and form a whole. The uniformity of the magnetic field will not decrease due to the increase of the coil size, and the detection capability will not be affected as the width of the steel cord conveyor belt 2 increases.

[0044] The uniform magnetic field generating device 1 further includes an oscillating power supply 100 , which supplies power to the oscillating circuit 10 to generate an oscillating current in the first coil 11 and the second coil 12 .

[0045] In this embodiment, the oscillation circuit 10 may be a sinusoidal oscillation circuit, and a sinusoidal alternating magnetic field is formed in the first coil 11 and the second coil 12. In this specific implementation, after the non-magnetic metal passes through the rectangular Helmholtz coil, an obvious eddy current effect is generated, thereby affecting the oscillating current signal, making it possible to detect non-magnetic metal impurities.

[0046] Combination Figure 2 and Figure 4 In another specific implementation of the present embodiment, the uniform magnetic field generating device 1 comprises: an oscillating circuit 10, a third coil 13 and a fourth coil 14; wherein the third coil 13 and the fourth coil 14 pass through the steel wire core conveyor belt 2 in a direction perpendicular to the running path of the steel wire core conveyor belt 2, and the third coil 13 and the fourth coil 14 are arranged at a preset distance from front to back along the conveying path of the steel wire core conveyor belt 2; the oscillating circuit 10 is connected to both the third coil 13 and the fourth coil 14 to provide an oscillating current to the third coil 13 and the fourth coil 14, thereby generating a uniform alternating magnetic field between the third coil 13 and the fourth coil 14.

[0047] The third coil 13 and the fourth coil 14 are rectangular, square, triangular or circular Helmholtz coils. In this embodiment, the oscillation circuit 10 can be a sinusoidal oscillation circuit, forming a sinusoidal alternating magnetic field in the third coil 13 and the fourth coil 14 .

[0048] The above embodiments further include: a protective cover (not shown in the figure); wherein the protective cover is arranged outside the uniform magnetic field generating device 1 to protect the internal components of the uniform magnetic field generating device 1 from the influence of the external environment.

[0049] Specifically, the protective cover is a rectangular or square frame structure, wherein the size of the hollow portion can be determined according to actual conditions, and only needs to be able to pass through the steel cord conveyor belt 2. The protective cover is made of PVC material.

[0050] Method Example: The present invention also provides a metal detection method for magnetic materials, comprising: The oscillating current signal in the uniform magnetic field generating device 1 is collected in real time, and a background signal is constructed according to the amplitude change of the oscillating current signal; when the steel rope core conveyor belt 2 starts to transport magnetic materials and passes through the alternating magnetic field, the background signal starts to fluctuate, and the fluctuation amplitude of the background signal is proportional to the jitter amplitude of the steel rope core conveyor belt and the instantaneous flow rate of the magnetic material; when the background signal starts to fluctuate, the initial alarm threshold of metal impurities is set according to the fluctuation amplitude of the background signal.

[0051] Specifically, when the steel cord conveyor belt 2 and the magnetic material pass through the alternating magnetic field generated by the uniform magnetic field generating device 1, interference signals will be generated, causing changes in the amplitude of the oscillating current.

[0052] Under normal working conditions (i.e., without additional metal interference), the signal processing unit 3 continuously collects oscillating current signals from the uniform magnetic field generating device 1, which represent the "background" state of the system without abnormalities. The initial alarm threshold for metal impurities can be set based on the historical data of the background signal and its fluctuation amplitude. This threshold can be set high enough to ensure that normal background signal fluctuations will not trigger an alarm.

[0053] When the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, an alarm trigger signal is generated, indicating that the magnetic material is mixed with metal impurities. In other words, when abnormal metal impurities pass through, the amplitude of the background signal will obviously exceed the initial alarm threshold, thereby triggering an alarm.

[0054] When a belt joint signal is received, the alarm threshold of metal impurities is adjusted to be higher than the initial alarm threshold according to the belt joint signal, and after the belt joint is away from the uniform magnetic field generating device 1, the alarm threshold of metal impurities is restored to the initial alarm threshold; when the amplitude of the background signal exceeds the adjusted alarm threshold, an alarm trigger signal is generated to indicate that metal impurities have fallen into the belt joint, and is sent to the alarm unit 5 for alarm action.

[0055] Specifically, the belt joint increases the fluctuation amplitude of the background signal, which exceeds the alarm threshold and causes the metal detection device to falsely alarm. Therefore, it is necessary to filter out the signal so that the background signal is temporarily lower than the initial alarm threshold so that the alarm will not be triggered. After the belt joint leaves the uniform magnetic field generating device 1, the metal alarm threshold is restored to the previous initial alarm threshold.

[0056] The related parts of the method embodiment and the above-mentioned device embodiment can be referred to each other and will not be described in detail here.

[0057] In summary, the present invention can effectively suppress the interference between the steel wire rope conveyor belt 2 and magnetic materials such as iron ore and iron concentrate, so that metal impurities can be accurately and effectively detected when the steel wire rope conveyor belt 2 transports magnetic materials, and can even accurately detect metal impurities contained in magnetic materials under the working conditions of high-grade (≥60%) magnetic materials (such as iron ore and iron concentrate).

[0058] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A metal detection device for magnetic materials, characterized in that: include: A uniform magnetic field generating device, a belt joint identification unit, a signal processing unit and an alarm unit; wherein the uniform magnetic field generating device is installed in cooperation with a steel cord conveyor belt for conveying magnetic materials, and is used to generate a uniform alternating magnetic field in the peripheral space where the steel cord conveyor belt passes through by using an oscillating current, so that the steel cord conveyor belt passes through the alternating magnetic field on its running path; The belt joint identification unit is arranged on the running path of the steel cord conveyor belt, located at the front end of the uniform magnetic field generating device, and located below the steel cord conveyor belt, for detecting the belt joint signal of the steel cord conveyor belt and transmitting it to the signal processing unit; The signal processing unit is connected to the uniform magnetic field generating device, and is used to collect the oscillating current signal generated by the uniform magnetic field generating device in real time, and extract the amplitude of the oscillating current signal to construct a background signal; When the steel cord conveyor belt starts to transport magnetic materials and passes through the alternating magnetic field generated by the uniform magnetic field generating device, the background signal starts to fluctuate, and the fluctuation amplitude of the background signal is proportional to the vibration amplitude of the steel cord conveyor belt and the instantaneous flow rate of the magnetic materials; when the background signal starts to fluctuate, the initial alarm threshold of metal impurities is set according to the fluctuation amplitude of the background signal; the signal processing unit is also used to generate an alarm trigger signal when the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, thereby prompting that metal impurities are mixed in the magnetic materials; The signal processing unit is also connected to the belt joint identification unit to receive the belt joint signal sent by the belt joint identification unit, adjust the alarm threshold of metal impurities to be higher than the initial alarm threshold according to the belt joint signal, and restore the alarm threshold of metal impurities to the initial alarm threshold after the belt joint is away from the uniform magnetic field generating device; and generate an alarm trigger signal when the amplitude of the background signal is instantaneously higher than the adjusted alarm threshold to prompt that metal impurities have fallen into the belt joint area; the alarm unit is connected to the signal processing unit.

2. The metal detection device for magnetic materials according to claim 1, characterized in that: The uniform magnetic field generating device comprises: an oscillating circuit, a first coil and a second coil; wherein the first coil and the second coil are arranged in parallel along the running direction of the steel cord conveyor belt, and the first coil and the second coil are distributed on the upper and lower sides of the steel cord conveyor belt; The oscillation circuit is connected to both the first coil and the second coil to provide an oscillation current to the first coil and the second coil, thereby generating a uniform alternating magnetic field between the first coil and the second coil.

3. The metal detection device for magnetic materials according to claim 2, characterized in that: There are a plurality of the first coils and a plurality of the second coils, and the first coils and the second coils are arranged in a one-to-one correspondence, and each pair of the first coils and the second coils forms a matrix arrangement.

4. The metal detection device for magnetic materials according to claim 1, characterized in that: The uniform magnetic field generating device comprises: an oscillating circuit, a third coil and a fourth coil; wherein the third coil and the fourth coil pass through the steel cord conveyor belt in a direction perpendicular to the running path of the steel cord conveyor belt, and the third coil and the fourth coil are arranged at a preset distance in front and behind along the conveying path of the steel cord conveyor belt; The oscillation circuit is connected to both the third coil and the fourth coil to provide an oscillation current to the third coil and the fourth coil, thereby generating a uniform alternating magnetic field between the third coil and the fourth coil.

5. The metal detection device for magnetic materials according to claim 1, characterized in that: When the uniform magnetic field generating device and the steel cord conveyor belt are in a relatively static state, the background signal is a straight line.

6. The metal detection device for magnetic materials according to claim 1, characterized in that: Also includes: A protective cover; wherein the protective cover is arranged outside the uniform magnetic field generating device to protect the internal components of the uniform magnetic field generating device from the influence of the external environment.

7. The metal detection device for magnetic materials according to claim 1, characterized in that: The signal processing unit includes: a signal conditioning circuit unit, an ADC sampling circuit unit and an MCU processor circuit unit; wherein the signal conditioning circuit unit is connected to the uniform magnetic field generating device, and is used to obtain the amplitude of the oscillating current signal in the uniform magnetic field generating device, and construct a background signal for metal impurity detection based on the amplitude of the oscillating current signal; The ADC sampling circuit unit is connected to the signal conditioning circuit unit and is used to convert the collected background signal into a digital signal; The MCU processor circuit unit is connected to the ADC sampling circuit unit and the belt joint identification unit, and is used for receiving the background signal and the belt joint signal and processing them.

8. The metal detection device for magnetic materials according to claim 1, characterized in that: The alarm unit comprises: an alarm output circuit; wherein the input end of the alarm output circuit is connected to the signal processing unit; and the output end of the alarm output circuit is connected to an external iron removal device or a warning device.

9. The metal detection device for magnetic materials according to claim 1, characterized in that: Also includes: Human-computer interaction unit; wherein the human-computer interaction unit is connected to the signal processing unit, and is used to display the fluctuation amplitude of the background signal and set the initial alarm threshold of metal impurities, display the alarm output status and the number of alarms.

10. A metal detection method for magnetic materials, using the metal detection device for magnetic materials as claimed in claim 1, characterized in that: include: Collecting an oscillating current signal in a uniform magnetic field generating device in real time, and constructing a background signal according to the amplitude change of the oscillating current signal; When the steel cord conveyor belt starts to transport magnetic materials and passes through the alternating magnetic field, the background signal starts to fluctuate, and the fluctuation amplitude of the background signal is proportional to the vibration amplitude of the steel cord conveyor belt and the instantaneous flow rate of the magnetic materials; when the background signal starts to fluctuate, the initial alarm threshold of metal impurities is set according to the fluctuation amplitude of the background signal; When the amplitude of the background signal instantaneously exceeds the initial alarm threshold of the metal impurities, an alarm trigger signal is generated, indicating that the magnetic material is mixed with metal impurities; When a belt joint signal is received, the alarm threshold of metal impurities is adjusted to be higher than the initial alarm threshold according to the belt joint signal, and after the belt joint is away from the uniform magnetic field generating device, the alarm threshold of metal impurities is restored to the initial alarm threshold; when the amplitude of the background signal exceeds the adjusted alarm threshold, an alarm trigger signal is generated to indicate that metal impurities have fallen into the belt joint, and is sent to the alarm unit for alarm action.

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