Residual magnetism detection method and residual magnetism detection device for shielding plate

Abstract

The invention discloses a residual magnetism detection method and a residual magnetism detection device for a shielding plate, and the method comprises the steps: detecting the actual magnetic field intensity vector value of each preset point location for N preset point locations on the surface of a to-be-detected shielding plate, n is an integer greater than or equal to 2; calculating a difference value between the actual magnetic field intensity vector value and the ideal magnetic field intensity vector value at each preset point location, and taking the difference value as a target magnetic field intensity vector value at the preset point location; the ideal magnetic field intensity vector value is a magnetic field intensity vector value when no residual magnetism and magnetic leakage exist at the preset point position; and judging whether the shielding plate is available or not based on the target magnetic field intensity vector values at the N preset point positions on the surface of the shielding plate. The residual magnetism detection method can detect the residual magnetism or magnetic leakage performance of the shielding plate in a general environment or a low-cost magnetic shielding environment.

Description

Technical Field

[0001] The present invention relates to the field of magnetic shielding technology, and in particular to a residual magnetism detection method and a residual magnetism detection device for a shielding plate. Background Art

[0002] In electronic engineering projects, there are many devices that need to provide high-performance magnetic shielding rooms, such as transmission electron microscopes, electron beam lithography machines, etc. The construction of magnetic shielding rooms requires the use of a large number of plates of different thicknesses such as soft iron, low-carbon steel, silicon steel sheets and BoMo alloys to make shielding bodies. Since the DC magnetic properties in the magnetic shielding room are often controlled within a range of tens of nanoteslas, the residual magnetic properties of these shielding construction materials have a serious impact on the performance of the magnetic shielding room. Since the residual magnetism or leakage magnetism of the shielding construction materials has a serious impact on the completed magnetic shielding room, these materials that may have excessive residual magnetism need to be demagnetized in the factory before construction, and then transported to the site for construction. However, the detection of the performance of the shielding construction materials after demagnetization is easily affected by environmental factors, so there is no very economical and reasonable means either in the factory or on the project site.

[0003] In the magnetic field detected by the magnetic sensor, on the one hand, the strength contribution of the external environment magnetic field will be superimposed, on the other hand, the magnetic field strength contribution added by the magnetization of the material to be tested in the external magnetic field will be superimposed, and finally the magnetic field strength contribution brought by the residual magnetism of the material to be tested itself. If the material is not placed in a zero-magnetic environment laboratory for testing, these three magnetic field strength contributions will be mixed together and cannot be distinguished, and the size of the actual residual magnetic field of the material cannot be detected. Placing the material to be tested in a zero-magnetic environment requires a very expensive zero-magnetic laboratory, which makes it difficult to achieve residual magnetism detection of shielding construction materials at present. Summary of the invention

[0004] The present invention provides a residual magnetism detection method and residual magnetism detection device for a shielding plate. The residual magnetism detection method for a shielding plate can detect the residual magnetism or magnetic leakage performance of the shielding plate in a general environment or a low-cost magnetic shielding environment.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for detecting residual magnetism of a shielding plate, comprising:

[0007] For N preset points on the surface of the shielding plate to be tested, detecting the actual magnetic field intensity vector value at each of the preset points, where N is an integer greater than or equal to 2;

[0008] Calculate the difference between the actual magnetic field intensity vector value and the ideal magnetic field intensity vector value at each of the preset points, and use the difference as the target magnetic field intensity vector value at the preset points; the ideal magnetic field intensity vector value is the magnetic field intensity vector value when there is no residual magnetism and leakage magnetism at the preset points;

[0009] Whether the shielding plate is available is determined based on the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate.

[0010] Optionally, the N preset points on the surface of the shielding plate are distributed on two opposite surfaces of the shielding plate.

[0011] Optionally, a method for determining the ideal magnetic field intensity vector value at each of the preset points includes:

[0012] For a preset point at the same position on the surface of M shielding plates to be tested, detecting the actual magnetic field intensity vector value at each preset point, wherein the specifications of the M shielding plates to be tested are the same;

[0013] The average value of the actual magnetic field intensity vector value at the preset point position at the same position of the M shielding plates is calculated, and the average value is used as the ideal magnetic field intensity vector value at the preset point position.

[0014] Optionally, a method for determining the ideal magnetic field intensity vector value at each preset position includes:

[0015] For a preset point at the same position on the surface of a rational shielding plate and the surface of a shielding plate to be tested, the actual magnetic field intensity vector value at the preset point is detected, and the actual magnetic field intensity vector value is used as the ideal magnetic field intensity vector value at the preset point; the ideal shielding plate has the same specifications as the shielding plate to be tested, and has no residual magnetism and leakage magnetism problems.

[0016] Optionally, shielding plates of the same specification have the same shape, size, material and mechanical properties.

[0017] Optionally, the determining whether the shielding plate is available includes:

[0018] If the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate are all within a preset range, it is determined that the shielding plate is usable;

[0019] If at least one of the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate is not within a preset range, it is determined that the shielding plate is unusable.

[0020] Optionally, the preset range is [-3σ, +3σ], where σ is the variance of the ideal magnetic field intensity vector value at M×N preset points in the M shielding plates to be tested.

[0021] Optionally, when detecting the actual magnetic field strength at each of the preset points, the extension direction of the long side of the shielding plate to be tested is the same as the extension direction of the earth's magnetic field.

[0022] The present invention also provides a residual magnetism detection device for a shielding plate, comprising a workbench, a frame, a fluxgate sensor and a control module;

[0023] The first surface of the workbench has a detection area and a mounting area arranged around the detection area, and the detection area is used to place the shielding plate to be tested;

[0024] The frame body comprises a supporting frame, a hanging frame and a moving driving part, the supporting frame is connected to the detection area of ​​the workbench, and the hanging frame is located on a side of the supporting frame away from the workbench;

[0025] The fluxgate sensor is suspended on the suspension frame through the mobile driving unit, and the mobile driving unit can drive the fluxgate sensor to move at least along a first direction and a second direction, the first direction and the second direction are perpendicular to each other and are parallel to the first surface, and the fluxgate sensor is used to: for N preset points on the surface of the shielding plate to be tested, detect the actual magnetic field intensity vector value at each of the preset points, where N is an integer greater than or equal to 2;

[0026] The control module is connected to the fluxgate sensor and the mobile drive unit signal, and is used to:

[0027] Obtaining the actual magnetic field intensity vector value at each of the preset points;

[0028] Calculate the difference between the actual magnetic field intensity vector value and the ideal magnetic field intensity vector value at each of the preset points, and use the difference as the target magnetic field intensity vector value at the preset points; the ideal magnetic field intensity vector value is the magnetic field intensity vector value when there is no residual magnetism and leakage magnetism at the preset points;

[0029] Whether the shielding plate is available is determined based on the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate.

[0030] The present invention provides a residual magnetism detection method and residual magnetism detection device for a shielding plate. In the residual magnetism detection method for a shielding plate, the residual magnetism and leakage magnetism detection of the shielding plate can be performed in a common environment without using a zero-magnetic environment laboratory with strict conditions. First, for N preset points on the surface of the shielding plate to be tested, the actual magnetic field intensity vector value at each preset point is detected, and then the difference between the actual magnetic field intensity vector value and the ideal magnetic field intensity vector value at each preset point is calculated, and the difference is used as the target magnetic field intensity vector value at the preset point. Finally, based on the target magnetic field intensity vector value at the N preset points on the surface of the shielding plate, it is judged whether the shielding plate is usable. Wherein, the actual magnetic field intensity vector value at the preset point is subtracted from the ideal magnetic field intensity vector value, which is equivalent to subtracting the environmental magnetic field and the influence of the environmental magnetic field on the magnetic field intensity generated by the magnetization of the shielding plate to be tested at the preset point in the test structure, so that the calculated target magnetic field intensity vector value is the residual magnetism vector value or leakage magnetism vector value to be measured, and then the residual magnetism or leakage magnetism performance of the shielding plate can be detected in a general environment or a low-cost magnetic shielding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic flow chart of a residual magnetism detection method for a shielding plate provided by an embodiment of the present invention;

[0032] Figure 2 A schematic structural diagram of a residual magnetism detection device for a shielding plate material provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Please refer to Figure 1 The present invention provides a method for detecting residual magnetism of a shielding plate, which may include the following steps:

[0035] S101: for N preset points on the surface of the shielding plate to be tested, detecting the actual magnetic field intensity vector value at each of the preset points, where N is an integer greater than or equal to 2;

[0036] S102: Calculate the difference between the actual magnetic field intensity vector value and the ideal magnetic field intensity vector value at each of the preset points, and use the difference as the target magnetic field intensity vector value at the preset points; the ideal magnetic field intensity vector value is the magnetic field intensity vector value when there is no residual magnetism and leakage magnetism at the preset points;

[0037] S103: judging whether the shielding plate is usable based on the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate.

[0038] In the residual magnetism detection method of the shielding plate provided in the embodiment of the present invention, the residual magnetism and leakage magnetism detection of the shielding plate can be performed in a normal environment without using a zero-magnetic environment laboratory with strict conditions; first, for N preset points on the surface of the shielding plate to be tested, the actual magnetic field intensity vector value at each preset point is detected, and then the difference between the actual magnetic field intensity vector value and the ideal magnetic field intensity vector value at each preset point is calculated, and the difference is used as the target magnetic field intensity vector value at the preset point; finally, based on the target magnetic field intensity vector value at the N preset points on the surface of the shielding plate, it is determined whether the shielding plate is usable; wherein, subtracting the ideal magnetic field intensity vector value from the actual magnetic field intensity vector value at the preset point is equivalent to subtracting the environmental magnetic field and the influence of the environmental magnetic field on the magnetic field intensity generated by the magnetization of the shielding plate to be tested at the preset point in the test structure, so that the calculated target magnetic field intensity vector value is the residual magnetism vector value or leakage magnetism vector value that needs to be measured, and then the residual magnetism or leakage magnetism performance of the shielding plate can be detected in a general environment or a low-cost magnetic shielding environment.

[0039] Specifically, the shielding plate may be a rectangular plate, and the shielding plate may have two opposite surfaces and four side surfaces.

[0040] In the embodiment of the present invention, the N preset points on the surface of the shielding plate may be distributed on two opposite surfaces of the shielding plate, so as to achieve sufficient detection of the residual magnetic vector value and the leakage magnetic vector value at each position of the shielding plate.

[0041] Specifically, the number of the preset points on the two opposite surfaces of the shielding plate may be equal, and the preset points on the two surfaces of the shielding plate may be arranged relative to each other.

[0042] Specifically, the preset points on the surface of the above-mentioned shielding plate can be located in any area of ​​the surface of the shielding plate. There is no restriction here. They can be distributed in different areas as much as possible to achieve full detection of the residual magnetic vector values ​​or leakage magnetic vector values ​​in different areas of the surface of the shielding plate.

[0043] Specifically, the preset points on the surface of the shielding plate may be distributed in an array, or may be arranged in other ways, which are not limited here and depend on the actual situation.

[0044] The number N of preset points can be as large as possible, so as to collect as many samples of the magnetic field intensity vector value on the shielding plate as possible, so as to facilitate the determination of whether the shielding plate is usable.

[0045] In the embodiment of the present invention, the method for determining the ideal magnetic field intensity vector value at each preset point may include the following steps:

[0046] S1021: for a preset point at the same position on the surface of M shielding plates to be tested, detecting an actual magnetic field intensity vector value at each preset point, wherein the M shielding plates to be tested have the same specifications;

[0047] S1022: Calculate the average value of the actual magnetic field intensity vector value at the preset point at the same position of the M shielding plates, and use the average value as the ideal magnetic field intensity vector value at the preset point.

[0048] In the above method of determining the ideal magnetic field strength vector value at each preset point, the M shielding plates to be tested can be from the same batch and the same specifications, and the residual magnetic vector values ​​and leakage magnetic vector values ​​on the shielding plates are randomly and independently distributed. Therefore, the average value of the actual magnetic field strength vector value at a preset point of the same batch of M shielding plates is equal to the magnetic field strength vector value on the ideal shielding plate of the same specification, and the residual magnetic vector value and leakage magnetic vector value of the ideal shielding plate are zero.

[0049] In the above-mentioned residual magnetism detection method of the shielding plate, M shielding plates of the same batch and the same specification are detected, and each shielding plate has N preset points on its surface. First, the preset points on the surface of the M shielding plates can be detected. Optionally, the determination method of the ideal magnetic field intensity vector value at each preset position can also be:

[0050] For the preset point at the same position on the surface of the rational shielding plate and the surface of the shielding plate to be tested, the actual magnetic field intensity vector value at the preset point is detected, and the actual magnetic field intensity vector value is used as the ideal magnetic field intensity vector value at the preset point; the ideal shielding plate has the same specifications as the shielding plate to be tested, and has no residual magnetism and leakage magnetism problems.

[0051] In the above-mentioned method of determining the ideal magnetic field strength vector value at each preset position, an ideal shielding plate known to have no residual magnetism and leakage magnetic problems can be directly provided, and each preset point on the surface of the ideal shielding plate is detected to obtain the actual magnetic field strength vector value at each preset point. The actual magnetic field strength vector value can be used as the ideal magnetic field strength vector value, and the ideal magnetic field strength vector value can be directly determined.

[0052] In the embodiment of the present invention, the shielding plates of the same specification may be shielding plates having the same shape, size, material, mechanical properties, etc.

[0053] In the embodiment of the present invention, judging whether the shielding plate is usable specifically includes the following steps:

[0054] S1031: If the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate are all within a preset range, it is determined that the shielding plate is usable;

[0055] S1032: If at least one of the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate is not within a preset range, it is determined that the shielding plate is unusable.

[0056] In the above-mentioned residual magnetism detection method, it can be determined whether the target magnetic field strength vector values ​​at N preset points on the surface of the shielding plate are within a preset range. If the target magnetic field strength vector values ​​at the N preset points on the surface of the shielding plate are all within the preset range, it can be determined that the shielding plate has no residual magnetism and leakage magnetism, and the shielding plate is usable. If the target magnetic field strength vector values ​​at the N preset points on the surface of the shielding plate have values ​​outside the preset range, it can be determined that the shielding plate has residual magnetism or leakage magnetism, and the shielding plate is unusable and needs to be returned to the factory for annealing and demagnetization.

[0057] In the embodiment of the present invention, the above-mentioned preset range may be [-3σ, +3σ], where σ is the variance of the ideal magnetic field intensity vector value at M×N preset points in the M shielding plates to be tested.

[0058] Specifically, M shielding plates to be tested of the same batch and the same specification need to be subjected to residual magnetism detection, N preset points are set on the surface of each shielding plate to be tested, and residual magnetism detection is performed on the M shielding plates to be tested respectively. Residual magnetism detection needs to be performed at M×N preset points, and M×N actual magnetic field intensity vector values ​​can be calculated, and then the corresponding M×N ideal magnetic field intensity vector values ​​can be obtained, and then the variance σ of the M×N ideal magnetic field intensity vector values ​​can be calculated, and then a preset range [-3σ, +3σ] can be obtained.

[0059] In the embodiment of the present invention, when detecting the actual magnetic field strength at each preset point, the extension direction of the long side of the shielding plate to be detected is the same as the extension direction of the earth's magnetic field.

[0060] In the above-mentioned residual magnetism detection method of the shielding plate, during the process of detecting the shielding plate to be tested, the extension direction of the long side of the shielding plate to be tested can be set to be the same as the extension direction of the geomagnetic field, so as to facilitate the use of the magnetization influence of the geomagnetic field and better detect the leakage magnetic field problem caused by stress concentration or internal defects of the shielding plate.

[0061] The present invention also provides a residual magnetism detection device for a shielding plate, such as Figure 2 As shown, it includes a workbench 1, a frame, a fluxgate sensor 3 and a control module;

[0062] The first surface of the workbench 1 has a detection area and a mounting area arranged around the detection area, and the detection area is used to place the shielding plate 100 to be tested;

[0063] The frame includes a support frame 21, a suspension frame 22 and a mobile driving unit 23. The support frame 21 is connected to the detection area of ​​the workbench 1, and the suspension frame 22 is located on a side of the support frame 21 away from the workbench;

[0064] The fluxgate sensor 3 is suspended on the suspension frame 22 through the mobile driving unit 23. The mobile driving unit 23 can drive the fluxgate sensor 3 to move at least along the first direction and the second direction. The first direction and the second direction are perpendicular to each other and are parallel to the first surface. The fluxgate sensor 3 is used to: detect the actual magnetic field intensity vector value at each preset point on the surface of the shielding plate to be tested at N preset points, where N is an integer greater than or equal to 2;

[0065] The control module is connected to the fluxgate sensor 3 and the mobile drive unit 23 for:

[0066] Obtain the actual magnetic field strength vector value at each preset point;

[0067] Calculate the difference between the actual magnetic field strength vector value and the ideal magnetic field strength vector value at each preset point, and use the difference as the target magnetic field strength vector value at the preset point; the ideal magnetic field strength vector value is the magnetic field strength vector value when there is no residual magnetism and leakage magnetism at the preset point;

[0068] Whether the shielding plate is usable is determined based on the target magnetic field intensity vector values ​​at N preset points on the surface of the shielding plate.

[0069] The residual magnetism detection device for shielding plates provided in the embodiment of the present invention can implement any of the residual magnetism detection methods for shielding plates provided in the above technical solutions. The shielding plate to be tested is placed in the detection area of ​​the first surface of the workbench. The actual magnetic field strength at N preset points on the surface of the shielding plate can be detected by moving the fluxgate sensor. The control module can process the actual magnetic field strength at each of the N preset points to obtain the vector value of the target magnetic field strength at the N preset points. Based on the target magnetic field strength vector value at the N preset points on the surface of the shielding plate, it is determined whether the shielding plate is usable. The target magnetic field strength vector value is the true residual magnetism or leakage magnetic vector value. The above residual magnetism detection device can detect the residual magnetism or leakage magnetic properties of the shielding plate in a general environment or a low-cost magnetic shielding environment, which is convenient for the detection of the shielding plate.

[0070] Specifically, the frame may be a mobile scanning gantry.

[0071] Specifically, the specific steps of performing residual magnetism detection on the shielding plate using the residual magnetism detection device of the shielding plate may be:

[0072] S1: placing the shielding plates to be tested of the same specifications on the testing area of ​​the first surface of the workbench in sequence;

[0073] S2: Using a fluxgate sensor to perform a multi-point magnetic field scan at a fixed point on each shielding plate according to a preset moving trajectory, and detecting an actual magnetic field intensity vector value at a preset point on a surface of one side of the shielding plate;

[0074] S3: Calculate the difference between the actual magnetic field intensity vector value and the ideal magnetic field intensity vector value at each preset point, and use the difference as the target magnetic field intensity vector value at the preset point;

[0075] S4: Turn over each shielding plate to be tested, and place them in the detection area of ​​the first surface of the workbench in turn, use the fluxgate sensor to detect the actual magnetic field intensity vector value at the preset point on the other side of each shielding plate according to the preset moving trajectory, and calculate the target magnetic field intensity vector value at each preset point;

[0076] S5: judging whether the shielding plate is usable based on the target magnetic field intensity vector values ​​at the preset points on the two surfaces of the shielding plate.

[0077] Specifically, the control module can control the mobile driving unit 23 to drive the fluxgate sensor 3 to move, and record the position of the fluxgate sensor 3, so as to enable the fluxgate sensor to scan the shielding plate according to a preset moving trajectory.

[0078] Optionally, the fluxgate sensor 3 is further used for:

[0079] For a preset point at the same position on the surface of M shielding plates to be tested, detecting the actual magnetic field intensity vector value at each preset point, wherein the specifications of the M shielding plates to be tested are the same;

[0080] The control module is also used for:

[0081] The average value of the actual magnetic field intensity vector value at the preset point position at the same position of the M shielding plates is calculated, and the average value is used as the ideal magnetic field intensity vector value at the preset point position.

[0082] Optionally, the fluxgate sensor 3 is further used for:

[0083] For a preset point at the same position on the surface of the ideal shielding plate and the surface of the shielding plate to be tested, the actual magnetic field intensity vector value at the preset point is detected, and the specifications of the ideal shielding plate and the shielding plate to be tested are the same, and there is no problem of residual magnetism and leakage magnetism;

[0084] The control module is also used for:

[0085] The actual magnetic field intensity vector value is used as the ideal magnetic field intensity vector value at the preset point.

[0086] Optionally, the control module is used to:

[0087] If the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate are all within a preset range, it is determined that the shielding plate is usable;

[0088] If at least one of the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate is not within a preset range, it is determined that the shielding plate is unusable.

[0089] Optionally, the preset range is [-3σ, +3σ], where σ is the variance of the ideal magnetic field intensity vector value at M×N preset points in the M shielding plates to be tested.

[0090] Optionally, when the actual magnetic field strength at each preset point is detected using the above-mentioned residual magnetism detection device, the extension direction of the long side of the shielding plate to be tested may be the same as the extension direction of the earth's magnetic field.

[0091] Obviously, those skilled in the art can make various changes and modifications to the embodiments of 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 method for detecting residual magnetism of a shielding plate, characterized in that: include: For N preset points on the surface of the shielding plate to be tested, detecting the actual magnetic field intensity vector value at each of the preset points, where N is an integer greater than or equal to 2; Calculate the difference between the actual magnetic field intensity vector value and the ideal magnetic field intensity vector value at each of the preset points, and use the difference as the target magnetic field intensity vector value at the preset points; the ideal magnetic field intensity vector value is the magnetic field intensity vector value when there is no residual magnetism and leakage magnetism at the preset points; Whether the shielding plate is available is determined based on the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate.

2. The residual magnetism detection method according to claim 1, characterized in that: The N preset points on the surface of the shielding plate are distributed on two opposite surfaces of the shielding plate.

3. The residual magnetism detection method according to claim 1, characterized in that: The method for determining the ideal magnetic field intensity vector value at each of the preset points includes: For a preset point at the same position on the surface of M shielding plates to be tested, detecting the actual magnetic field intensity vector value at each preset point, wherein the specifications of the M shielding plates to be tested are the same; The average value of the actual magnetic field intensity vector value at the preset point position at the same position of the M shielding plates is calculated, and the average value is used as the ideal magnetic field intensity vector value at the preset point position.

4. The residual magnetism detection method according to claim 1, characterized in that: The method for determining the ideal magnetic field intensity vector value at each preset position includes: For a preset point at the same position on the surface of a rational shielding plate and the surface of a shielding plate to be tested, the actual magnetic field intensity vector value at the preset point is detected, and the actual magnetic field intensity vector value is used as the ideal magnetic field intensity vector value at the preset point; the ideal shielding plate has the same specifications as the shielding plate to be tested, and has no residual magnetism and leakage magnetism problems.

5. The residual magnetism detection method according to claim 3 or 4, characterized in that: Shielding plates of the same specifications have the same shape, size, material and mechanical properties.

6. The residual magnetism detection method according to claim 1, characterized in that: The step of judging whether the shielding plate is usable includes: If the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate are all within a preset range, it is determined that the shielding plate is usable; If at least one of the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate is not within a preset range, it is determined that the shielding plate is unusable.

7. The residual magnetism detection method according to claim 6, characterized in that: The preset range is [-3σ, +3σ], where σ is the variance of the ideal magnetic field intensity vector value at M×N preset points in the M shielding plates to be tested.

8. The residual magnetism detection method according to claim 1, characterized in that: When detecting the actual magnetic field strength at each of the preset points, the extension direction of the long side of the shielding plate to be tested is the same as the extension direction of the earth's magnetic field.

9. A residual magnetism detection device for a shielding plate, characterized in that: It includes a workbench, a frame, a fluxgate sensor and a control module; The first surface of the workbench has a detection area and a mounting area arranged around the detection area, and the detection area is used to place the shielding plate to be tested; The frame body comprises a supporting frame, a hanging frame and a moving driving part, the supporting frame is connected to the detection area of ​​the workbench, and the hanging frame is located on a side of the supporting frame away from the workbench; The fluxgate sensor is suspended on the suspension frame through the mobile driving unit, and the mobile driving unit can drive the fluxgate sensor to move at least along a first direction and a second direction, the first direction and the second direction are perpendicular to each other and are parallel to the first surface, and the fluxgate sensor is used to: for N preset points on the surface of the shielding plate to be tested, detect the actual magnetic field intensity vector value at each of the preset points, where N is an integer greater than or equal to 2; The control module is connected to the fluxgate sensor and the mobile drive unit signal, and is used to: Obtaining the actual magnetic field intensity vector value at each of the preset points; Calculate the difference between the actual magnetic field intensity vector value and the ideal magnetic field intensity vector value at each of the preset points, and use the difference as the target magnetic field intensity vector value at the preset points; the ideal magnetic field intensity vector value is the magnetic field intensity vector value when there is no residual magnetism and leakage magnetism at the preset points; Whether the shielding plate is available is determined based on the target magnetic field intensity vector values ​​at the N preset points on the surface of the shielding plate.

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