An online measurement device and method for the initial magnetic permeability of ship steel

Abstract

This invention relates to the field of magnetic permeability measurement technology, specifically to an online device and method for measuring the initial magnetic permeability of ship steel. The device includes a solenoid frame, a solenoid coil, a magnetic sensor, a support, and a housing. The solenoid coil is wound around a non-magnetic solenoid frame. Two sets of supports are connected to the solenoid frame and symmetrically arranged on both sides of the frame. Two sets of magnetic sensors are respectively located at the center of the adjacent sides of the two sets of supports. The solenoid frame and supports are both housed within the housing. Compared to standard magnetic permeability measurement methods, this method allows for online acquisition of the initial magnetic permeability of ship steel without cutting the steel sample, avoiding the influence of residual stress on the measurement and overcoming the shortcomings of existing technologies.

Description

Technical Field

[0001] This invention relates to the field of magnetic permeability measurement technology, specifically to an online device and method for measuring the initial magnetic permeability of ship steel. Background Technology

[0002] The initial magnetic permeability of ship steel is a crucial parameter for analyzing and compensating for the induced magnetic field of a vessel. Accurately obtaining the initial magnetic permeability helps improve the ship's magnetic stealth performance. Currently, all methods for measuring the initial magnetic permeability of ship steel are offline. This involves cutting a ring-shaped sample from the hull steel plate, winding an H-coil and a B-coil around the sample, and using Ampere's circuital law, accurately calculating the magnetic field strength H within the magnetic circuit based on the magnetizing current i of the H-coil. The magnetic induction intensity B is then determined using the B-coil and a flux integrator, and the magnetic permeability parameter is extracted from the BH curve. However, residual stress is formed inside the sample during the cutting process, which significantly affects the magnetic permeability of the steel and may lead to a large deviation between the measured results and the actual magnetic permeability of the ship steel.

[0003] This invention provides an online measurement device and method for the initial magnetic permeability of ship steel. It utilizes a solenoid coil to generate an additional magnetic field around the ship steel. By measuring the induced magnetic field in the ship steel under the influence of the solenoid's magnetic field, the initial magnetic permeability of the ship steel can be inverted. This method enables non-destructive online measurement of the initial magnetic permeability of ship steel. It does not introduce any residual stress, and the measurement results are closer to the true value, providing an important reference for the design of shipborne degaussing systems. Summary of the Invention

[0004] In response to the above situation and to overcome the shortcomings of the existing technology, this solution provides an online measurement device and method for the initial magnetic permeability of ship steel, which can realize non-destructive measurement of the magnetic permeability of actual ship steel plates without cutting ship steel samples.

[0005] An online measurement device for the initial magnetic permeability of ship steel is achieved by the following specific technical means: it includes a solenoid frame, a solenoid coil, a magnetic sensor, a bracket, and a housing. The solenoid coil is wound on a non-magnetic solenoid frame. Two sets of brackets are connected to the solenoid frame and are symmetrically arranged on both sides of the solenoid frame. The two sets of magnetic sensors are respectively located at the center of the mutually close sides of the two sets of brackets. The solenoid frame and the brackets are both located inside the housing.

[0006] Preferred technical solution 1: The probe direction of the magnetic sensor is parallel to the axis of the solenoid frame.

[0007] Preferred technical solution 2: The solenoid coil is supplied with DC power through a high-precision DC power supply.

[0008] Preferred technical solution 3: The stability of the high-precision DC power supply is better than 1‰.

[0009] Preferred technical solution four: The magnetic sensor is connected to a magnetic field data acquisition device.

[0010] Preferred technical solution five: The solenoid frame and bracket are rigidly connected to the outer shell.

[0011] Preferred technical solution six: The two sets of magnetic sensors are rigidly connected to the two sets of brackets respectively.

[0012] Preferred technical solution seven: The two sets of brackets are rigidly connected to the solenoid frame.

[0013] Preferred technical solution eight: The magnetic sensor is a fluxgate sensor.

[0014] This solution also discloses an online method for measuring the initial magnetic permeability of ship steel, including the following steps:

[0015] S1. Place the outer casing of the online measurement device for the initial magnetic permeability of ship steel tightly against the surface of the ship's hull.

[0016] S2. Connect the magnetic sensor to the magnetic field data acquisition device and record the measured values ​​B of the two sets of magnetic sensors at this time. b1 and B b2 ;

[0017] S3. Connect the solenoid coil to a high-precision DC power supply, and pass a constant DC current I through the solenoid coil. Record the measured values ​​B of the two sets of magnetic sensors respectively. c1 and B c2 ;

[0018] S4. Establish a 1:1 static magnetic field numerical model including ship steel and a solenoid coil. The side length of the ship steel model is set to 5 times the outer shell size, and the permeability is set to μ. Apply a current I as excitation in the solenoid coil, and calculate the induced magnetic fields at the two sets of magnetic sensors, respectively, B. j1 and B j2 If |B j1 -B j2 |<|(B c1 -B b1 )-(B c2 -B b2 If ||, then increase μ; otherwise, decrease μ, until ||B|. j1 -B j2 |-|(B c1 -B b1 )-(B c2 -B b2 If || < 1nT, then the corresponding μ can be regarded as the initial permeability measurement value of the ship steel.

[0019] Furthermore, the distance between the outer shell and the outer edge boundary of the ship steel should be greater than 5 times the outer shell size.

[0020] The above structure gives this solution the following advantages:

[0021] Compared to standard permeability measurement methods, this method can obtain the initial permeability of ship steel online without cutting the ship steel sample, thus avoiding the influence of residual stress on permeability measurement and making up for the shortcomings of existing technologies. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic diagram of the online measurement device for the initial magnetic permeability of ship steel.

[0024] Figure 2 Cross-sectional view of the online measurement device for the initial magnetic permeability of ship steel;

[0025] Figure 3 This is a schematic diagram of an online method for measuring the initial magnetic permeability of ship steel.

[0026] Among them: 1-Solenoid frame, 2-Solenoid coil, 3-Magnetic sensor, 4-Bracket, 5-Housing shell, 6-High-precision DC power supply, 7-Magnetic field data acquisition device, 8-Ship steel, 9-Ship hull. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Please see Figures 1-2The system includes a solenoid frame (1), a solenoid coil (2), a fluxgate sensor (3), a bracket (4), a housing (5), a high-precision DC power supply (6), and a magnetic field data acquisition device (7). The solenoid coil (2) is wound around a non-magnetic solenoid frame (1). Two non-magnetic brackets (4) are rigidly connected to the solenoid frame (1) by bolts and are symmetrically arranged on both sides of the solenoid frame (1). Two fluxgate sensors (3) are fixed to the center of the brackets (4) by bolts. The skeleton (1), solenoid coil (2), fluxgate sensor (3), and bracket (4) are all placed inside the non-magnetic outer shell (5). The solenoid skeleton (1) and bracket (4) are rigidly connected to the outer shell 5 by bolts. The probe direction of the fluxgate sensor (3) is parallel to the axis of the solenoid skeleton (1). The solenoid coil (2) is supplied with DC power through a high-precision DC power supply (6). The stability of the high-precision DC power supply (6) is better than 1‰. The fluxgate sensor (3) is connected to the magnetic field data acquisition device (7).

[0029] like Figure 3 As shown, the present invention provides an online method for measuring the initial magnetic permeability of ship steel, comprising the following steps:

[0030] Step 1: Place the outer shell 5 of the online measurement device for the initial magnetic permeability of ship steel tightly against the surface of the ship's hull 9;

[0031] Step 2: Connect the fluxgate sensor 3 to the magnetic field data acquisition device 7, and record the measured values ​​B of the two fluxgate sensors 3 at this time. b1 and B b2 ;

[0032] Step 3: Connect the solenoid coil 2 to the high-precision DC power supply 6, and pass a constant DC current I through the solenoid coil 2. Record the measured values ​​B of the two fluxgate sensors 3 respectively. c1 and B c2 Then the sum of the solenoid magnetic field and the induced magnetic field it induces on the ship steel 8 is B. c1 -B b1 and B c2 -B b2 Since the magnetic field of the solenoid is equal in magnitude at the two fluxgate sensors at point 3, therefore (B) c1 -B b1 )-(B c2 -B b2 This is the difference in the induced magnetic field of the ship's steel.

[0033] Step 4: Establish a 1:1 static magnetic field numerical model including the ship steel 8 and the solenoid coil 2. The side length of the ship steel model is set to 5 times the size of the outer shell 5. The permeability is set to μ. A current I is applied as excitation in the solenoid coil 2. The induced magnetic fields at the two fluxgate sensors 3 are calculated as B. j1 and B j2If |B j1 -B j2 |<|(B c1 -B b1 )-(B c2 -B b2 If ||, then increase μ; otherwise, decrease μ, until ||B|. j1 -B j2 |-|(B c1 -B b1 )-(B c2 -B b2 If || < 1nT, then the corresponding μ can be regarded as the initial permeability measurement value of ship steel 8.

[0034] The distance between the outer shell 5 and the outer edge of the ship steel 8 should be greater than 5 times the size of the outer shell 5.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for online measurement of the initial magnetic permeability of ship steel, characterized in that, The device includes an online measuring device for the initial magnetic permeability of ship steel. The online measuring device for the initial magnetic permeability of ship steel includes a solenoid frame (1), a solenoid coil (2), a magnetic sensor (3), a bracket (4), a housing (5), a high-precision DC power supply (6), and a magnetic field data acquisition device (7). The solenoid coil (2) is wound on a non-magnetic solenoid frame (1). Two sets of brackets (4) are connected to the solenoid frame (1) and symmetrically arranged on both sides of it. Two sets of magnetic sensors (3) are respectively located at the center of the two sets of brackets (4) on the mutually close sides. The solenoid frame (1) and the brackets (4) are both located inside the housing (5). The solenoid coil (2) is supplied with DC power through the high-precision DC power supply (6). The magnetic sensor (3) is connected to the magnetic field data acquisition device (7). The online measurement method includes the following steps: S1. Place the outer shell (5) of the online measurement device for the initial magnetic permeability of the ship steel (8) tightly against the surface of the ship hull (9); S2. Connect the magnetic sensor (3) to the magnetic field data acquisition device (7) and record the measured values ​​Bb1 and Bb2 of the two sets of magnetic sensors (3) at this time. S3. Connect the solenoid coil (2) to the high-precision DC power supply (6), pass a constant DC current I through the solenoid coil (2), and record the measured values ​​Bc1 and Bc2 of the two sets of magnetic sensors (3) respectively. S4. Establish a 1:1 static magnetic field numerical model containing ship steel (8) and solenoid coil (2). Set the side length of the ship steel (8) model to 5 times the size of the shell (5). Set the permeability μ. Apply current I as excitation in solenoid coil (2). Calculate the induced magnetic fields at the two sets of magnetic sensors (3) as Bj1 and Bj2 respectively. If |Bj1-Bj2|<|(Bc1-Bb1)-(Bc2-Bb2)|, increase μ; otherwise, decrease μ until ||Bj1-Bj2|-|(Bc1-Bb1)-(Bc2-Bb2)||<1nT. Then the corresponding μ can be regarded as the initial permeability measurement value of ship steel (8).

2. The method for online measurement of the initial magnetic permeability of ship steel according to claim 1, characterized in that: The distance between the outer shell (5) and the outer edge of the ship steel (8) should be greater than 5 times the size of the outer shell (5).

3. The method for online measurement of the initial magnetic permeability of ship steel according to claim 1, characterized in that: The magnetic sensor (3) is a fluxgate sensor, and its probe direction is parallel to the axis of the solenoid frame (1).

4. The method for online measurement of the initial magnetic permeability of ship steel according to claim 1, characterized in that: The high-precision DC power supply (6) has a stability better than 1‰.

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