Sensor and method for detecting the thickness of zinc layer on steel wire surface based on eddy current detection

Abstract

The present invention discloses a sensor for detecting the zinc layer thickness on the surface of a steel wire based on eddy current detection, including a detection coil group, a detection circuit and a microprocessor; the detection coil group is an external through-type eddy current detection coil; the detection circuit is used to excite and adjust the current of the detection coil and receive the eddy current response signal of the detection coil, and send it to the microprocessor, and the microprocessor is used to characterize the zinc layer thickness parameter of the detected steel wire according to the eddy current response signal of the through-type eddy current detection coil. The sensor can realize the online detection of the zinc layer thickness of the galvanized steel wire, and adopts the double eddy current detection coil comparison method under the same environment. The influence of environmental changes on the detection can be shielded or weakened as common mode interference through subtraction operation, and it is more convenient to reduce or eliminate the influence of temperature changes on the detection results through software and hardware design means, and can realize high-precision real-time non-contact online detection.

Description

Technical Field

[0001] The present invention relates to the application field of eddy current detection technology, and in particular to an online detection sensor for the zinc layer thickness of a galvanized steel wire based on an eddy current detection method and a detection method thereof. Background Art

[0002] Hot-dip galvanized steel wire is suitable for manufacturing engineering structures with harsh environmental conditions such as steel cables for bridges and sewage tanks, and is widely used in other industries such as the manufacture of springs and wire ropes.

[0003] The thickness of the galvanized steel wire coating has an important influence on its performance. If it is too thin, it will directly reduce the service life of the galvanized steel wire. Therefore, due to unreliable coating control, the manufacturing unit has to increase the thickness of the galvanized layer within the total diameter, resulting in waste and increased costs. Therefore, it is necessary to conduct real-time detection and control of the coating during the galvanizing process.

[0004] Traditional equipment does not have online detection and uses manual adjustment and control. Usually, products are sampled when loading and unloading or at the beginning of the process. The samples are then sent to the laboratory to use chemical methods to test the weight of the sample coating. According to the difference between the test results and the standard values, the corresponding process control points are adjusted to increase or decrease the thickness of the zinc layer to meet the requirements.

[0005] However, in the production process, the thickness of the zinc layer usually changes due to changes in the process control points: for example, in the traditional direct solid foam wiping method, the gradual accumulation of the oxide layer at the zinc outlet, the gradual reduction or change of the wiping material during the working process, and other gradual changes in working conditions; for example, in the more advanced air pressure control method, after the zinc outlet, the galvanized part is still in a hot melt state, so that the steel wire passes through a channel of a specific shape. In this channel, a certain pressure of gas is applied to form an air field, which generates a thrust on the hot-melt galvanized layer and adjusts the air pressure. The thrust can be adjusted to adjust the thickness of the zinc layer. In this method, the channel may be affected by slag and cause changes in shape or changes in air supply pressure and temperature. Or other control methods, there will always be changes in the process control points during the production process, causing changes in the thickness of the zinc layer. The traditional laboratory sampling method has a large workload and poor reliability, which often causes the thickness of the steel wire coating to be unqualified during the production process.

[0006] To this end, a technology of calculating through diameter detection has been proposed: by setting up laser diameter gauges before and after galvanizing respectively, and detecting the difference in diameter before and after galvanizing, the thickness of the coating is calculated; there are also plans to emit X-rays through an X-ray tube, irradiate the steel wire, and then project it onto the X-ray detector, and use the different absorption rates of steel and zinc to X-rays. The different grayscales of the images formed on the X-ray detector are used to convert the X-rays transmitted through the steel wire into a digital image, and the size of the steel wire and the zinc layer is obtained based on the digital image of the steel wire.

[0007] However, due to safety and reliability (involving the application of lasers or rays at production sites, there are great safety hazards during the detection process, and if not properly protected, it is easy to cause harm to the health of the test personnel), high cost, and the impact of wire jitter and temperature changes on the test results is difficult to overcome, and the above solutions have not been widely used in actual applications due to difficulties in adjustment, poor environment, and high failure rate.

[0008] With the advent of the industrial information age, the industrial production of information-based big data will become increasingly dependent on high-precision data. In the hot-dip galvanized steel wire industry, the demand for safe, efficient, low-cost and high-precision zinc thickness measurement has become extremely urgent.

[0009] In view of the above situation, in the production process of hot-dip galvanized steel wire, a high-precision, reliable, and practical application-suitable online detection sensor for the zinc layer thickness of galvanized steel wire is very important. Summary of the invention

[0010] The technical problem to be solved by the present invention is to overcome the difficulties in online detection and complex debugging of the zinc layer thickness of galvanized steel wire in the prior art, and to provide a galvanized steel wire zinc layer thickness online detection sensor based on eddy current detection method and a detection method thereof.

[0011] A sensor for detecting the thickness of zinc layer on the surface of a steel wire based on eddy current detection, comprising a detection coil group, a detection circuit and a microprocessor;

[0012] The detection coil group includes an eddy current detection coil, which is an external pass-through eddy current detection coil for the galvanized steel wire to pass through and whose eddy current response is sensitive to the zinc layer thickness of the galvanized steel wire;

[0013] The detection circuit includes a signal detection and processing circuit and an eddy current excitation and adjustment circuit; the eddy current detection coil is electrically connected to the signal detection and processing circuit, the signal detection and processing circuit is used to receive the eddy current response signal of the detection coil and send it to the microprocessor, and the eddy current excitation and adjustment circuit is used to adjust the excitation frequency of the detection and processing circuit;

[0014] The microprocessor characterizes the zinc layer thickness of the steel wire to be detected according to the eddy current response signal of the eddy current detection coil.

[0015] Furthermore, the detection coil group includes two external pass-through eddy current detection coils with the same parameters, and the steel wire with standard zinc layer thickness and the steel wire to be detected are respectively inserted into the external pass-through eddy current detection coils; the microprocessor is used to obtain the zinc layer thickness parameter or deviation value of the detected steel wire based on the deviation value ΔA of the eddy current response signals of the two external pass-through eddy current detection coils.

[0016] Furthermore, the detection coil group includes more than three external eddy current detection coils with the same parameters, and the steel wire with the standard zinc layer thickness and the steel wire to be detected are respectively inserted into different external eddy current detection coils, and the microprocessor is used to calculate the zinc layer thickness parameter or deviation value of each steel wire to be detected according to the deviation value ΔA between the eddy current response signal of each eddy current detection coil inserted into the steel wire to be detected and the eddy current response signal of the eddy current detection coil inserted into the steel wire with the standard zinc layer thickness. Thereby, the simultaneous detection of multiple steel wires to be detected can be achieved.

[0017] Each external through-type eddy current detection coil is respectively connected to the same detection circuit or connected to the same detection circuit and connected to the detection circuit in sequence by switching with an electronic switch.

[0018] When the detection coil group includes two external through-type eddy current detection coils with the same parameters, for the convenience of description, the coil through which the steel wire with standard zinc layer thickness passes can be marked as TR0 external through-type eddy current detection coil, and the coil through which the steel wire to be detected passes can be marked as TR1 external through-type eddy current detection coil;

[0019] The detection circuit includes a signal detection and processing circuit and an eddy current excitation and adjustment circuit; the TR0 external through-type eddy current detection coil and the TR1 external through-type eddy current detection coil are respectively electrically connected to the same signal detection and processing circuit or connected to the same detection circuit by switching an electronic switch, and are connected to the detection circuit in sequence; the signal detection and processing circuit is used to receive the eddy current response signal of the detection coil and send it to the microprocessor, and the eddy current excitation and adjustment circuit is used to adjust the excitation frequency of the detection circuit;

[0020] The microprocessor is used to obtain the zinc layer thickness parameter or deviation value of the detection steel wire according to the deviation value ΔA of the eddy current response signal of the TR0 external through-type eddy current detection coil and the TR1 external through-type eddy current detection coil.

[0021] Furthermore, the frequency of the excitation current of the eddy current excitation and adjustment circuit is adjustable from 50KHZ to 500KHZ, and the frequency can be adjusted for different detection objects. The frequency of the eddy current excitation and adjustment circuit is adjusted to a point where its eddy current response is sensitive to the zinc layer thickness of the galvanized steel wire. Different excitation frequencies will have different sensitivities.

[0022] The adjustment method can be manual or automatic. When adjusting manually, there is no need to set up an additional detection and correction coil group, which has a simple structure and low cost. The debugging method and steps of the manual adjustment method (such as adjusting only the frequency) are as follows:

[0023] 1) First determine the debugging frequency range based on experience, such as 50KHZ ~ 200KHZ, and select or adjust an excitation current frequency such as 50KHZ;

[0024] 2) Pass galvanized steel wires of the same material but with different zinc layer thicknesses through the aforementioned detection coil group in sequence, confirm and record the detection signals corresponding to different zinc layer thicknesses when the excitation current is applied, and obtain the detection sensitivity data within the range of different zinc layer thicknesses.

[0025] 3) The microprocessor increases the frequency by a certain frequency interval, such as 5KHZ, and confirms the start of the test.

[0026] 4) Repeat 2);

[0027] 5) Through the above debugging, a corresponding curve of the detection signal of different zinc layer thicknesses about the excitation current frequency is obtained. Based on the principle of relative stability and sensitivity of sensitivity (difference between detection signals of different thicknesses / difference in zinc layer thickness), one of the excitation frequency bands is selected as the eddy current detection excitation frequency of the detected material.

[0028] 6) Determine the selected excitation frequency, and input the detection signal corresponding to different zinc layer thicknesses at this frequency into the microprocessor. The microprocessor will calculate the corresponding detection sensitivity and its fitting curve based on this. The microprocessor obtains the sensitivity fitting curve based on the manually input data.

[0029] When the automatic adjustment mode is adopted: the detection sensor also includes a detection correction coil group for debugging and calibration, and the detection correction coil group includes a plurality of correction external through-type eddy current detection coils; during debugging and calibration, the detection coil group is disconnected from the detection circuit, and the detection correction coil group is connected to the detection circuit;

[0030] The calibrated external through-type eddy current detection coil performs eddy current response on steel wires of the same material but with different zinc layer thicknesses at different excitation frequencies, and the microprocessor obtains a detection sensitivity curve according to each eddy current detection signal value.

[0031] The excitation current is automatically adjusted. Galvanized steel wires of the same material but with different zinc layer thicknesses are passed through the aforementioned correction detection coils respectively. The detection data of each coil can be selected and collected at any time during operation. The sensitivity can be corrected in real time and accurately, the sensor can be linearly fitted, and automatic calculation can be performed to achieve high-precision real-time non-contact online detection.

[0032] The debugging method and steps of the automatic adjustment method (such as adjusting only the frequency) are as follows:

[0033] 1) Pass galvanized steel wires of the same material and different zinc layer thickness through the aforementioned corrected external through-type eddy current detection coils in sequence;

[0034] 2) First determine the debugging frequency range based on experience, such as 50KHZ~200KHZ, select or adjust an excitation current frequency such as 50KHZ, and confirm to start the test;

[0035] 3) The detection circuit will detect different corrected external eddy current detection coils in turn. The microprocessor obtains the detection signal corresponding to different zinc layer thicknesses when the selected excitation current is obtained, and the detection sensitivity data within the range of different zinc layer thicknesses is obtained to confirm the test.

[0036] 4) The microprocessor increases the frequency by a certain frequency interval, such as 5KHZ, and confirms the start of the test.

[0037] 5) Repeat above 3)

[0038] 6) Through the above debugging, the microprocessor obtains a corresponding curve of the detection signal of different zinc layer thicknesses about the excitation current frequency. Automatically judge, based on the principle of sensitivity (difference of detection signals of different thicknesses / difference of zinc layer thickness) sensitivity and relative stability (small linear deviation), select one of the excitation frequency bands as the eddy current detection excitation frequency of the detected material, record the sensitivity fitting curve, and store the relevant data as future experience.

[0039] Furthermore, the microprocessor includes a storage unit, and the storage unit is used to store the detection data and detection sensitivity curves of the relevant thicknesses of different steel wire materials obtained through debugging and calibration.

[0040] A method for detecting the thickness of zinc layer on the surface of steel wire based on eddy current detection comprises the following steps:

[0041] S1. Prepare multiple steel wire samples with uniform zinc layer thickness and different zinc layer thickness, and accurately detect their zinc layer thickness;

[0042] S2. Select the steel wire samples with the largest and smallest zinc layer thickness, pass them through the two coils of the detection coil group respectively, adjust the current change frequency of the detection circuit from the minimum to the maximum, observe the eddy current response signal of the detection coil group, and determine the frequency range F to be tested based on stability and monotonicity. MIN To F MAX ;

[0043] S3, the detection circuit is disconnected from the detection coil group, and a correction external through-type eddy current detection coil is connected. The current change frequency of the detection circuit is adjusted to F MIN，

[0044] S4, sequentially passing each sample prepared in S1 through the calibration external through-type eddy current detection coil, and the signal detection and processing circuit is used to receive the eddy current response signal of each sample and send it to the microprocessor;

[0045] S5, increase the current change frequency of the detection circuit by ΔF, and repeat S4;

[0046] S6, repeat S5 until the current change frequency of the excitation signal reaches F MAX ;

[0047] S7, the microprocessor processes the eddy current detection signals corresponding to the samples with different zinc layer thicknesses at different excitation current frequencies to obtain a detection sensitivity curve;

[0048] S8, disconnect the detection circuit from the correction external through-type eddy current detection coil, connect it to the detection coil group, the steel wire with standard zinc layer thickness passes through the TR0 external through-type eddy current detection coil, and the steel wire to be detected passes through the TR1 external through-type eddy current detection coil; the steel wire with standard zinc layer thickness and the galvanized steel wire to be detected have the same carbon content and outer diameter, and both use the same excitation adjustment circuit and signal detection processing circuit;

[0049] S9, setting the alternating frequency of the excitation current to the optimal eddy current detection excitation frequency obtained in step S7, and the signal detection and processing circuit receives the eddy current response signal of the detection coil and sends it to the microprocessor;

[0050] The microprocessor will calculate based on the detection sensitivity curve obtained in step S7, obtain the zinc layer thickness deviation value of the steel wire to be detected, and record and display the data.

[0051] Furthermore, the method for obtaining the detection sensitivity broken line in S6 is to connect the eddy current detection signal data corresponding to the samples with different zinc layer thicknesses under different excitation current frequencies and draw them into a broken line, and calculate the sensitivity and the relative stability value, wherein the sensitivity calculation method is: the difference in the eddy current detection signal values ​​of the steel wire samples with different zinc layer thicknesses / the difference in zinc layer thickness, and the relative stability value is the linear deviation. Based on the principles of high sensitivity and small linear deviation, the optimal eddy current detection excitation frequency is analyzed and obtained, and the fitting equation group is calculated through the fitting algorithm, and the microprocessor stores the corresponding detection sensitivity broken line.

[0052] Furthermore, the fitting algorithm calculates a linear equation formed by adjacent eddy current detection signal values ​​and forms a piecewise linear equation group.

[0053] Furthermore, the detection sensor is also provided with a signal output module, which can output the eddy current response deviation value between the zinc layer thickness to be detected and the standard zinc layer thickness to the production system to guide the control of the zinc layer thickness in steel wire production.

[0054] Furthermore, the microprocessor includes a decision unit, an excitation signal adjustment unit, a calculation unit and a fault detection and alarm unit.

[0055] A deviation threshold is set in the decision unit. The calculation unit monitors the eddy current response of TR0 during operation, and compares it with the eddy current response of TR0 when it just starts working in S8 and S9. The difference is taken and the absolute value is taken. When the absolute value is greater than the deviation threshold, the fault detection and alarm unit issues an alarm and readjusts the excitation current through the excitation signal adjustment unit.

[0056] The storage unit of the microprocessor can collect and store debugging data; the decision unit can calculate decisions and control the excitation signal adjustment unit to control the correction / working detection coil selection; the excitation signal adjustment unit can adjust the current of the eddy current excitation and adjustment circuit; the calculation unit can calculate the zinc layer thickness, and the fault detection and alarm unit can perform real-time online fault detection and alarm, and the fault detection and alarm unit is electrically connected in time to send the signal to the signal output unit to output the signal.

[0057] The detection coil group of the present invention adopts an external through-type eddy current detection coil, and the galvanized steel wire in the production process can be inserted into the eddy current detection coil, thereby realizing continuous online detection. After the eddy current detection coil is passed through the detection circuit with an alternating current, a changing magnetic field will be generated in the eddy current detection coil, and the part of the galvanized steel wire that penetrates the eddy current detection coil will generate an induced potential on its circumference due to electromagnetic induction, forming an eddy current in the zinc layer. According to the electromagnetic induction constant, the rate of change of the induced potential on the circumference and the magnetic induction intensity is related: e=-dφ / dt. Since the zinc layer is conductive, an eddy current is formed.

[0058] The magnitude of the eddy current is also related to the resistance of the zinc layer on the circumference, R = ρ * L / S,

[0059] ρ: Resistivity of zinc layer

[0060] L: The circumference of the zinc layer

[0061] S: axial cross section of the columnar zinc layer, proportional to the thickness of the zinc layer;

[0062] Therefore, for galvanized steel wire, the eddy current response is sensitive to the steel wire material (magnetic permeability), the thickness of the zinc coating, and the outer diameter of the steel wire. Because the factors that are sensitive to eddy currents, such as the diameter of the steel wire and the carbon content, are different, when the rate of change of the magnetic induction intensity remains unchanged (using the same excitation current), the galvanized steel wires with the same zinc layer thickness and different steel wire materials (steel wire diameter, carbon content, etc.) will result in different eddy current responses, and the detection sensitivity of the thickness and detection signal and their fitting curves will change accordingly. By adjusting the excitation current and changing the rate of change of the magnetic field, the eddy current response is adjusted, so that the detection sensitivity of the thickness and detection signal and their fitting curves can be adjusted.

[0063] In the present invention, the TR0 external through-type eddy current detection coil and the TR1 external through-type eddy current detection coil of the detection coil group are in the same environment, and the two external through-type eddy current detection coils have the same structure and parameters. The two external through-type eddy current detection coils can be installed in the same housing to ensure that the working environment is relatively consistent. To ensure that other conditions are consistent, the detection and processing circuits and eddy current excitation and adjustment circuits of the two are also the same, or the same excitation circuit and detection circuit are used to detect the eddy current response signals of the two detection coils respectively through switching of electronic switches, and input them into the microprocessor.

[0064] The microprocessor calculates the eddy current response signal deviation value ΔA of the TR0 external through-type eddy current detection coil and the TR1 external through-type eddy current detection coil in real time online. Since other conditions are set to be consistent, the deviation value ΔA is only sensitive to thickness. Therefore, the deviation value ΔA can be directly used as the basis for thickness control and deviation over-limit alarm.

[0065] Furthermore, the microprocessor can calculate the detected thickness based on the eddy current response signals of the TR0 external pass-through eddy current detection coil and the TR1 external pass-through eddy current detection coil, combined with the pre-debugging obtained thickness and the detection sensitivity of the detection signal and its fitting curve.

[0066] When the present invention is used for real-time monitoring of online production of galvanized steel wire, when it is detected that the deviation value of the current value of the TR0 eddy current detection coil of the steel wire passing through the standard zinc layer thickness (compared with the end of debugging of the currently used excitation current) is large, the microprocessor can prompt to readjust the excitation current of the circuit and recalibrate the sensor.

[0067] For galvanized steel wires of different diameters and materials, the present invention can also adjust the eddy current excitation and the excitation current of the adjustment circuit (preferably adjusting the frequency, and can also be combined with adjusting the amplitude) to adjust the magnetic field change rate to obtain the best detection sensitivity and its fitting curve. Usually, when the material and diameter of the galvanized steel wire are changed and production begins; or during operation, when prompted to readjust the excitation current, the excitation current needs to be adjusted.

[0068] Beneficial effects: The present invention adopts the principle of external through-type eddy current sensor, has a simple structure, is easy to use, is mainly composed of eddy current detection coils and related detection elements, has small current, basically does not generate heat, can be epoxy-cast packaged, has high safety and reliability, has strong adaptability to the working environment, is suitable for long-term use at the galvanized steel wire production site, can be connected with the steel wire production system, and adopts a double eddy current detection coil comparison method under the same environment to detect the eddy current response value of the steel wire with a standard zinc layer thickness and the eddy current response value of the steel wire to be detected in real time, and calculates the difference ΔA between the eddy current responses of the two, so that the control is more based on evidence;

[0069] The present invention can realize automatic adjustment of the frequency (or size) of the excitation current to obtain the best sensitivity; a method for adjusting the excitation frequency is proposed for galvanized steel wires of different diameters and materials, which can be used as a basis for adjusting the excitation frequency during manual and automatic correction to obtain the best sensitivity; in particular, the automatic adjustment method adopts a multi-eddy current detection coil comparison method to automatically detect and analyze to obtain the best excitation frequency, obtain the detection coil output signal of each relevant zinc thickness at any time, perform linear fitting of the sensor in real time and accurately, and automatically calculate to achieve high-precision real-time non-contact online detection.

[0070] When detecting the coating of galvanized steel wire, the sensor of the present invention adopts a double eddy current detection coil comparison method under the same environment. Under the same environment, the influence of environmental changes on the detection can be shielded or weakened as common mode interference through subtraction operations, which makes it more convenient to reduce or eliminate the influence of temperature changes on the detection results through software and hardware design means. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0072] Figure 1 It is a structural block diagram of the detection sensor of the present invention. DETAILED DESCRIPTION

[0073] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0074] Example

[0075] A sensor for detecting the thickness of zinc layer on the surface of steel wire based on eddy current detection, comprising a detection coil group, a detection circuit, a microprocessor and a detection correction coil group;

[0076] The detection coil group includes a TR0 external through-type eddy current detection coil and a TR1 external through-type eddy current detection coil with the same parameters; a steel wire with a standard zinc layer thickness passes through the TR0 external through-type eddy current detection coil, and a steel wire to be detected passes through the TR1 external through-type eddy current detection coil;

[0077] The detection circuit includes a signal detection and processing circuit and an eddy current excitation and adjustment circuit; the TR0 external through-type eddy current detection coil and the TR1 external through-type eddy current detection coil are electrically connected to the signal detection and processing circuit respectively, the signal detection and processing circuit is used to receive the eddy current response signal of the detection coil and send it to the microprocessor, and the eddy current excitation and adjustment circuit is used to adjust the excitation frequency of the detection circuit;

[0078] The microprocessor is used to obtain the zinc layer thickness parameter or deviation value of the detection steel wire according to the deviation value ΔA of the eddy current response signal of the TR0 external through-type eddy current detection coil and the TR1 external through-type eddy current detection coil.

[0079] The frequency of the excitation current of the eddy current excitation and adjustment circuit is adjustable from 50KHZ to 500KHZ, and the frequency can be adjusted according to different detection objects.

[0080] The detection correction coil group is used for debugging and calibration, and the detection correction coil group includes a plurality of correction external through-type eddy current detection coils; during debugging and calibration, the detection coil group is disconnected from the detection circuit, and the detection correction coil group is connected to the detection circuit;

[0081] The calibrated external through-type eddy current detection coil performs eddy current response on steel wires of the same material but with different zinc layer thicknesses at different excitation frequencies, and the microprocessor obtains a detection sensitivity curve according to each eddy current detection signal value.

[0082] The excitation current is automatically adjusted. Galvanized steel wires of the same material but with different zinc layer thicknesses are passed through the aforementioned correction detection coils respectively. The detection data of each coil can be selected and collected at any time during operation. The sensitivity can be corrected in real time and accurately, the sensor can be linearly fitted, and automatic calculation can be performed to achieve high-precision real-time non-contact online detection.

[0083] The debugging method and steps of the automatic adjustment method (such as adjusting only the frequency) are as follows:

[0084] 1) Pass galvanized steel wires of the same material and different zinc layer thickness through the aforementioned corrected external through-type eddy current detection coils in sequence;

[0085] 2) First determine the debugging frequency range based on experience, such as 50KHZ~200KHZ, select or adjust an excitation current frequency such as 50KHZ, and confirm to start the test;

[0086] 3) The detection circuit will detect different corrected external eddy current detection coils in turn. The microprocessor obtains the detection signal corresponding to different zinc layer thicknesses when the selected excitation current is obtained, and the detection sensitivity data within the range of different zinc layer thicknesses is obtained to confirm the test.

[0087] 4) The microprocessor increases the frequency by a certain frequency interval, such as 5KHZ, and confirms the start of the test.

[0088] 5) Repeat above 3)

[0089] 6) Through the above debugging, the microprocessor obtains a corresponding curve of the detection signal of different zinc layer thicknesses about the excitation current frequency. Automatically judge, based on the principle of sensitivity (difference of detection signals of different thicknesses / difference of zinc layer thickness) sensitivity and relative stability (small linear deviation), select one of the excitation frequency bands as the eddy current detection excitation frequency of the detected material, record the sensitivity fitting curve, and store the relevant data as future experience.

[0090] The microprocessor comprises a storage unit, and the storage unit is used to store the detection data and the detection sensitivity broken line of the relevant thickness of different steel wire materials obtained through debugging and calibration.

[0091] A method for detecting the thickness of zinc layer on the surface of steel wire based on eddy current detection comprises the following steps:

[0092] S1. Prepare multiple steel wire samples with uniform zinc layer thickness and different zinc layer thickness, and accurately detect their zinc layer thickness;

[0093] S2. Select the steel wire samples with the largest and smallest zinc layer thickness, pass them through the two coils of the detection coil group respectively, adjust the current change frequency of the detection circuit from the minimum to the maximum, observe the eddy current response signal of the detection coil group, and determine the frequency range F to be tested based on stability and monotonicity. MIN To F MAX ;

[0094] S3, the detection circuit is disconnected from the detection coil group, and a correction external through-type eddy current detection coil is connected. The current change frequency of the detection circuit is adjusted to F MIN，

[0095] S4, sequentially passing each sample prepared in S1 through the calibration external through-type eddy current detection coil, and the signal detection and processing circuit is used to receive the eddy current response signal of each sample and send it to the microprocessor;

[0096] S5, increase the current change frequency of the detection circuit by ΔF, and repeat S4;

[0097] S6, repeat S5 until the current change frequency of the excitation signal reaches F MAX ;

[0098] S7, the microprocessor processes the eddy current detection signals corresponding to the samples with different zinc layer thicknesses at different excitation current frequencies to obtain a detection sensitivity curve;

[0099] S8, disconnect the detection circuit from the correction external through-type eddy current detection coil, connect it to the detection coil group, the steel wire with standard zinc layer thickness passes through the TR0 external through-type eddy current detection coil, and the steel wire to be detected passes through the TR1 external through-type eddy current detection coil; the steel wire with standard zinc layer thickness and the galvanized steel wire to be detected have the same carbon content and outer diameter, and both use the same excitation adjustment circuit and signal detection processing circuit;

[0100] S9, setting the alternating frequency of the excitation current to the optimal eddy current detection excitation frequency obtained in step S7, and the signal detection and processing circuit receives the eddy current response signal of the detection coil and sends it to the microprocessor;

[0101] The microprocessor will calculate based on the detection sensitivity curve obtained in step S7, obtain the zinc layer thickness deviation value of the steel wire to be detected, and record and display the data.

[0102] The method for obtaining the detection sensitivity broken line in S6 is to connect the eddy current detection signal data corresponding to the samples with different zinc layer thicknesses under different excitation current frequencies and draw a broken line, and calculate the sensitivity and the relative stability value, wherein the sensitivity calculation method is: the difference in the eddy current detection signal values ​​of the steel wire samples with different zinc layer thicknesses / the difference in zinc layer thickness, and the relative stability value is the linear deviation. Based on the principles of high sensitivity and small linear deviation, the optimal eddy current detection excitation frequency is analyzed and obtained, and the fitting equation group is calculated through the fitting algorithm, and the microprocessor stores the corresponding detection sensitivity broken line.

[0103] The fitting algorithm is to calculate the linear equation formed by the adjacent eddy current detection signal values ​​and form a piecewise linear equation group.

[0104] The detection sensor is also provided with a signal output module, which can output the eddy current response deviation value between the zinc layer thickness to be detected and the standard zinc layer thickness to the production system to guide the control of the zinc layer thickness in steel wire production.

[0105] The microprocessor includes a decision-making unit, an excitation signal adjustment unit, a calculation unit, and a fault detection and alarm unit.

[0106] A deviation threshold is set in the decision unit. The calculation unit monitors the eddy current response of TR0 during operation, and compares it with the eddy current response of TR0 when it just starts working in S8 and S9. The difference is taken and the absolute value is taken. When the absolute value is greater than the deviation threshold, the fault detection and alarm unit issues an alarm and readjusts the excitation current through the excitation signal adjustment unit.

[0107] The microprocessor can collect and store debugging data, make calculation decisions, control the excitation signal adjustment unit, control the correction / working detection coil selection, calculate the zinc layer thickness, perform online fault detection and alarm, and send it to the signal output unit in a timely electrical connection.

[0108] When detecting the coating of galvanized steel wire, the sensor of the present invention adopts a double eddy current detection coil comparison method under the same environment. Under the same environment, the influence of environmental changes on the detection can be shielded or weakened as common mode interference through subtraction operations, which makes it more convenient to reduce or eliminate the influence of temperature changes on the detection results through software and hardware design means.

[0109] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sensor for detecting the thickness of zinc layer on the surface of steel wire based on eddy current detection, characterized in that: It includes a detection coil group, a detection circuit and a microprocessor; The detection coil group includes an eddy current detection coil, which is an external pass-through eddy current detection coil for the galvanized steel wire to pass through and whose eddy current response is sensitive to the zinc layer thickness of the galvanized steel wire; The detection circuit includes a signal detection and processing circuit and an eddy current excitation and adjustment circuit; the eddy current detection coil is electrically connected to the signal detection and processing circuit, the signal detection and processing circuit is used to receive the eddy current response signal of the detection coil and send it to the microprocessor, and the eddy current excitation and adjustment circuit is used to adjust the excitation frequency of the detection and processing circuit; The microprocessor characterizes the zinc layer thickness of the steel wire to be tested according to the eddy current response signal of the eddy current detection coil; The detection coil group includes two or more external through-type eddy current detection coils with the same parameters. The steel wire with standard zinc layer thickness and the steel wire to be detected are respectively inserted into different external through-type eddy current detection coils. The microprocessor is used to calculate the zinc layer thickness parameter or deviation value of each steel wire to be detected according to the deviation value ΔA between the eddy current response signal of each eddy current detection coil inserted into the steel wire to be detected and the eddy current response signal of the eddy current detection coil inserted into the steel wire with standard zinc layer thickness.

2. The sensor for detecting the thickness of zinc layer on the surface of steel wire based on eddy current detection as claimed in claim 1, characterized in that: Each external through-type eddy current detection coil is respectively connected to the same detection circuit or connected to the same detection circuit and connected to the detection circuit in sequence by switching with an electronic switch.

3. The sensor for detecting the thickness of zinc layer on the surface of steel wire based on eddy current detection as claimed in claim 1, characterized in that: The detection sensor also includes a detection correction coil group for debugging and calibration, and the detection correction coil group includes a plurality of correction external through-type eddy current detection coils; During debugging and calibration, the detection coil group is disconnected from the detection circuit, and the detection correction coil group is connected to the detection circuit; The calibrated external through-type eddy current detection coil performs eddy current response on steel wires of the same material but with different zinc layer thicknesses at different excitation frequencies, and the microprocessor obtains a detection sensitivity curve according to each eddy current detection signal value.

4. The galvanized steel wire zinc layer thickness detection sensor based on eddy current detection as claimed in claim 1, characterized in that: The microprocessor includes a storage unit, and the storage unit is used to store the detection data and detection sensitivity broken lines of the relevant thicknesses of different steel wire materials obtained through debugging and calibration.

5. The sensor for detecting the thickness of zinc layer on the surface of steel wire based on eddy current detection as claimed in claim 1, characterized in that: The frequency of the excitation current of the eddy current excitation and adjustment circuit is adjustable from 50KHZ to 500KHZ, and the frequency can be adjusted according to different detection objects.

6. The sensor for detecting the thickness of zinc layer on the surface of steel wire based on eddy current detection as claimed in claim 1, characterized in that: The microprocessor includes a decision-making unit, an excitation signal adjustment unit, a calculation unit, and a fault detection and alarm unit. A deviation threshold is set in the decision unit, and the calculation unit monitors the eddy current response in the eddy current detection coil through which the steel wire of quasi-zinc layer thickness passes, and compares it with the eddy current response in its initial working state, makes a difference and takes the absolute value. When the absolute value is greater than the deviation threshold, the fault detection and alarm unit issues an alarm and readjusts the excitation current through the excitation signal adjustment unit.

7. The sensor for detecting the thickness of zinc layer on the surface of steel wire based on eddy current detection as claimed in claim 1, characterized in that: The detection sensor is also provided with a signal output module, which is electrically connected to the microprocessor. The signal output module can output the eddy current response deviation value between the zinc layer thickness to be detected and the standard zinc layer thickness to the production system to guide the control of the zinc layer thickness in steel wire production.

8. A detection method for the zinc layer thickness detection sensor on the surface of a steel wire based on eddy current detection according to claim 1, characterized in that: The following steps are involved: S1. Prepare multiple steel wire samples with uniform zinc layer thickness and different zinc layer thickness, and accurately detect their zinc layer thickness; S2. Select the steel wire samples with the largest and smallest zinc layer thickness, pass them through the two coils of the detection coil group respectively, adjust the current change frequency of the detection circuit from the minimum to the maximum, observe the eddy current response signal of the detection coil group, and determine the frequency range F to be tested based on stability and monotonicity. MIN To F MAX ; S3, the detection circuit is disconnected from the detection coil group, and a correction external through-type eddy current detection coil is connected. The current change frequency of the detection circuit is adjusted to F MIN， S4, sequentially passing each sample prepared in S1 through the calibration external through-type eddy current detection coil, and the signal detection and processing circuit is used to receive the eddy current response signal of each sample and send it to the microprocessor; S5, increase the current change frequency of the detection circuit by ΔF, and repeat S4; S6, repeat S5 until the current change frequency of the excitation signal reaches F MAX ; S7, the microprocessor processes the eddy current detection signals corresponding to the samples with different zinc layer thicknesses at different excitation current frequencies to obtain a detection sensitivity curve; S8, disconnect the detection circuit from the correction external through-type eddy current detection coil, connect it to the detection coil group, and let the steel wire with standard zinc layer thickness and the steel wire to be detected pass through two external through-type eddy current detection coils respectively; the steel wire with standard zinc layer thickness and the galvanized steel wire to be detected have the same carbon content and outer diameter, and both use the same excitation adjustment circuit and signal detection processing circuit; S9, setting the alternating frequency of the excitation current to the optimal eddy current detection excitation frequency obtained in step S7, and the signal detection and processing circuit receives the eddy current response signal of the detection coil and sends it to the microprocessor; The microprocessor will calculate based on the detection sensitivity curve obtained in step S7, obtain the zinc layer thickness deviation value of the steel wire to be detected, and record and display the data.

9. The detection method according to claim 8, characterized in that: The method for obtaining the detection sensitivity broken line in S6 is to connect the eddy current detection signal data corresponding to the samples with different zinc layer thicknesses under different excitation current frequencies and draw a broken line, and calculate the sensitivity and the relative stability value, wherein the sensitivity calculation method is: the difference in the eddy current detection signal values ​​of the steel wire samples with different zinc layer thicknesses / the difference in zinc layer thickness, and the relative stability value is the linear deviation. Based on the principles of high sensitivity and small linear deviation, the optimal eddy current detection excitation frequency is analyzed and obtained, and the fitting equation group is calculated through the fitting algorithm, and the microprocessor stores the corresponding detection sensitivity broken line.

10. The detection method according to claim 9, characterized in that: The fitting algorithm is to calculate the linear equation formed by the adjacent eddy current detection signal values ​​and form a piecewise linear equation group.

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