US 10,648,947 B2Granted

Micro-magnetic detecting method and micro-magnetic detecting device

AssigneeNingbo Yinzhou Citai Electronic Technology Co., Ltd

InventorsRunqiao Yu, Bin Zhang, Bo Hu, Guisuo Xia, Dongfang Cheng, Qiangqiang Cheng

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Abstract

A micro-magnetic detecting method includes the steps of: detecting a magnetic induction intensity along a first direction on a surface of a detected object to generate a detection signal, determining whether an amplitude of the detection signal is an anomalous value at a first position of the surface of the detected object, wherein the anomalous value is a value which is inconsistent with a linear value of the detection signal at the first position, and the linear value is a value that satisfies a linear relationship of the detection signal, and determining there is a defect at the first position of the detected object in case that the amplitude of the detection signal is the anomalous value. Accordingly, it detects the magnetic induction intensity on the surface of the detected object so as to detect its surface and internal defects when it remains in its original status.

Claims6

Dependent claims

A micro-magnetic detecting method for a detected object, comprising the steps of:

(a) detecting a magnetic induction intensity along a first direction on a surface of the detected object and generating a detection signal;
(b) determining whether an amplitude of the detection signal is an anomalous value at a first position of the surface of the detected object, wherein the anomalous value is a value which is inconsistent with a linear value of the detection signal at the first position and the linear value is a value that satisfies a linear relationship of the detection signal in the first direction;
(c) determining that there is a defect at the first position of the detected object when the amplitude of the detection signal is the anomalous value;
and
(d) drawing a first signal curve of the amplitude of the detection signal against the relative distance of the detected object in the first direction;
wherein the step (b) further comprises the steps of:
(b1) determining each maximum value and minimum value on the first signal curve, subtracting two adjacent minimum values from each maximum value respectively to obtain a first difference and a second difference;
(b2) selecting a larger one of the first difference and the second difference as a characteristic of a peak-peak value corresponding to each maximum value;
wherein the step (b2) further comprises the steps of:
based on characteristics of normal distribution of the characteristics of the peak-peak value, wherein ξ is a random variable following normal distribution, μ is mathematical expectation, and σ is mean square error, calculating a probability P of the characteristics of the peak-peak value being in an interval of (0, μ+2σ) to be 0.9545 and obtaining the peak-peak value for the probability P of 0.9545 according to:
P
⁡
(
ξ
)
=
P
⁡
(
μ
-
a
⁢
⁢
σ
<
ξ
<
μ
+
a
⁢
⁢
σ
)
=
∫
μ
-
a
⁢
⁢
σ
μ
+
a
⁢
⁢
σ
⁢
ydx
,
⁢
where
(
1
)
y
=
P
⁡
(
x
)
=
1
2
⁢
⁢
πσ
2
⁢
e
-
(
x
-
μ
)
2
2
⁢
⁢
σ
2
(
2
)
and α is an abscissa μ of a standard normal distribution;
and
(b3) determining that the amplitude of the detection signal is the anomalous value in case that the characteristic of the peak-peak value of the first position is larger than a predetermined threshold of the interval of the peak-peak value for judging and identifying defect signal and locating the defect.

88 more elements

A micro-magnetic detecting method for a detected object, comprising the steps of:

(a) detecting a magnetic induction intensity along a first direction on a surface of the detected object and generating a detection signal;
(b) determining whether an amplitude of the detection signal is an anomalous value at a first position of the surface of the detected object, wherein the anomalous value is a value which is inconsistent with a linear value of the detection signal at the first position and the linear value is a value that satisfies a linear relationship of the detection signal in the first direction;
(c) determining that there is a defect at the first position of the detected object when the amplitude of the detection signal is the anomalous value;
(d) drawing a first signal curve of the amplitude of the detection signal against a relative distance of the detected object in the first direction;
and
(e) calculating magnetic gradient of the magnetic induction intensity of the detection signal based on the amplitude of the magnetic induction intensity of the detection signal;
wherein the step (d) further comprises the steps of:
(d1) drawing a first signal curve of the magnetic gradient of the detection signal against the relative distance of the detected object in the first direction;
wherein the step (b) further comprises the steps of:
based on the characteristics of normal distribution of the magnetic gradient, wherein ξ is a random variable following normal distribution, μ is mathematical expectation, and σ is mean square error, calculating a probability P of the magnetic gradient being in an interval of (μ−ασ, μ+ασ) to be 0.9545 obtaining the interval of the magnetic gradient for the probability of 0.9545 according to:
P
⁡
(
ξ
)
=
P
⁡
(
μ
-
a
⁢
⁢
σ
<
ξ
<
μ
+
a
⁢
⁢
σ
)
=
∫
μ
-
a
⁢
⁢
σ
μ
+
a
⁢
⁢
σ
⁢
ydx
,
⁢
where
(
1
)
y
=
P
⁡
(
x
)
=
1
2
⁢
⁢
πσ
2
⁢
e
-
(
x
-
μ
)
2
2
⁢
⁢
σ
2
(
2
)
and α is an abscissa μ of a standard normal distribution;
wherein the step (c) further comprises a step of determining that the amplitude of the detection signal is the anomalous value when the magnetic gradient of the first position exceeds a predetermined threshold of the interval of the magnetic gradient.

87 more elements

A micro-magnetic detecting method for a detected object, comprising the steps of:

(a) detecting a magnetic induction intensity along a first direction on a surface of the detected object and generating a detection signal;
(b) determining whether an amplitude of the detection signal is an anomalous value at a first position of the surface of the detected object, wherein the anomalous value is a value which is inconsistent with a linear value of the detection signal at the first position and the linear value is a value that satisfies a linear relationship of the detection signal in the first direction;
(c) determining that there is a defect at the first position of the detected object when the amplitude of the detection signal is the anomalous value;
(d) drawing a first signal curve of the amplitude of the detection signal against the relative distance of the detected object in the first direction;
and
(e) conducting a gradient process for the amplitude of the magnetic induction intensity of the detection signal to calculate the gradient vectors of each point of the detection signal, wherein directions of the gradient vectors are the directions in which the first signal curve obtains a maximum value of a directional derivative of a certain point, wherein a norm of the gradient vector equals to the maximum value of the directional derivative;
wherein the step (d) further comprises a step of drawing a first signal curve of the gradient vector of the detection signal against a relative distance of the detected object in the first direction;
wherein the step (c) further comprises the steps of:
(c1) based on the characteristics of normal distribution of the gradient vector, wherein ξ is a random variable following normal distribution, μ is mathematical expectation, and σ is mean square error, calculating a probability P of the gradient vector being in an interval of (μ−ασ, μ+ασ) to be 0.9875 when α=2.5 obtaining the interval of the gradient vector for α=2.5 according to:
P
⁡
(
ξ
)
=
P
⁡
(
μ
-
a
⁢
⁢
σ
<
ξ
<
μ
+
a
⁢
⁢
σ
)
=
∫
μ
-
a
⁢
⁢
σ
μ
+
a
⁢
⁢
σ
⁢
ydx
,
⁢
where
,
(
1
)
y
=
P
⁡
(
x
)
=
1
2
⁢
⁢
πσ
2
⁢
e
-
(
x
-
μ
)
2
2
⁢
⁢
σ
2
;
(
2
)
and
(c2) determining that the amplitude of the detection signal is the anomalous value when the gradient vector of the first position exceeds a predetermined threshold of the interval of the gradient vector.

88 more elements

A micro-magnetic detecting device, comprising:

a detecting unit detects detecting a magnetic induction intensity along a first direction on a surface of a detected object to generate detection signal;
a calculating unit for determining whether an amplitude of the detection signal is an anomalous value at the first position of the surface of the detected object, wherein the anomalous value is a value which is inconsistent with a linear value of the detection signal at the first position, and the linear value is a value that satisfies a linear relationship of the detection signal in the first direction,
a determining unit for determining that there is a defect at the first position of the detected object when the amplitude of the detection signal is the anomalous value;
and
a drawing unit drawing a first signal curve of the amplitude of the detection signal against the relative distance of the detected object in the first direction;
wherein the calculating unit is further executed for:
determining each maximum value and minimum value on the first signal curve;
subtracting two adjacent minimum values from each maximum value respectively to obtain a first difference and a second difference;
selecting a larger one of the first difference and the second difference as a characteristic of a peak-peak value corresponding to each maximum value, and
determining that the amplitude of the detection signal is the anomalous value in case that the characteristic of the peak-peak value of the first position is larger than a predetermined threshold;
wherein after selecting the larger one of the first difference and the second difference as the characteristic of the peak-peak value corresponding to each maximum value, based on characteristics of normal distribution of the characteristics of the peak-peak value, when ξ is a random variable following normal distribution, μ is mathematical expectation, and σ is mean square error, the calculating unit is specifically for calculating a probability P of the characteristics of the peak-peak value being in an interval of (0, μ+2σ) to be 0.9545 and obtaining the probability of 0.9545 for the peak-peak value according to:
P
⁡
(
ξ
)
=
P
⁡
(
μ
-
a
⁢
⁢
σ
<
ξ
<
μ
+
a
⁢
⁢
σ
)
=
∫
μ
-
a
⁢
⁢
σ
μ
+
a
⁢
⁢
σ
⁢
ydx
,
⁢
where
(
1
)
y
=
P
⁡
(
x
)
=
1
2
⁢
⁢
πσ
2
⁢
e
-
(
x
-
μ
)
2
2
⁢
⁢
σ
2
(
2
)
and α is an abscissa μ of a standard normal distribution;
wherein the determining unit is specifically for determining that the amplitude of the detection signal is the anomalous value when the characteristics of the peak-peak value of the first position is greater than a predetermined threshold of the interval of the peak-peak value.

88 more elements

A micro-magnetic detecting device, comprising:

a detecting unit detecting a magnetic induction intensity along a first direction on a surface of a detected object to generate detection signal;
a calculating unit for determining whether an amplitude of the detection signal is an anomalous value at the first position of the surface of the detected object, wherein the anomalous value is a value which is inconsistent with a linear value of the detection signal at the first position, and the linear value is a value that satisfies a linear relationship of the detection signal in the first direction,
a determining unit for determining that there is a defect at the first position of the detected object when the amplitude of the detection signal is the anomalous value;
a drawing unit drawing a first signal curve of the amplitude of the detection signal against the relative distance of the detected object in the first direction;
and a first processing unit calculating magnetic gradient of the magnetic induction intensity of the detection signal based on the amplitude of the magnetic induction intensity of the detection signal;
wherein the drawing unit is specifically for drawing a first signal curve of the magnetic gradient of the detection signal against the relative distance of the detected object in the first direction;
wherein, the calculating unit is specifically for, based on the characteristics of normal distribution of the magnetic gradient, when ξ is a random variable, μ is mathematical expectation, and σ is mean square error, calculating a probability P of the magnetic gradient being in the interval of (μ−ασ, μ+ασ) to be 0.9545 and obtaining the interval of the magnetic gradient for the probability of 0.9545 according to:
P
⁡
(
ξ
)
=
P
⁡
(
μ
-
a
⁢
⁢
σ
<
ξ
<
μ
+
a
⁢
⁢
σ
)
=
∫
μ
-
a
⁢
⁢
σ
μ
+
a
⁢
⁢
σ
⁢
ydx
,
⁢
where
(
1
)
y
=
P
⁡
(
x
)
=
1
2
⁢
⁢
πσ
2
⁢
e
-
(
x
-
μ
)
2
2
⁢
⁢
σ
2
(
2
)
and α is an abscissa μ of a standard normal distribution;
wherein the determining unit is specifically for determining that the amplitude of the detection signal is the anomalous value when the magnetic gradient of the first position exceeds a predetermined threshold of the interval of the magnetic gradient.

84 more elements

A micro-magnetic detecting device, comprising:

a detecting unit detecting a magnetic induction intensity along a first direction on a surface of a detected object to generate detection signal;
a calculating unit for determining whether an amplitude of the detection signal is an anomalous value at the first position of the surface of the detected object, wherein the anomalous value is a value which is inconsistent with a linear value of the detection signal at the first position, and the linear value is a value that satisfies a linear relationship of the detection signal in the first direction;
a determining unit for determining that there is a defect at the first position of the detected object when the amplitude of the detection signal is the anomalous value;
a drawing unit drawing a first signal curve of the amplitude of the detection signal against the relative distance of the detected object in the first direction;
and
a second processing unit conducting a gradient process for the amplitude of the magnetic induction intensity of the detection signal to calculate the gradient vectors of each point of the detection signal, wherein directions of the gradient vectors are the directions in which the first signal curve obtains a maximum value of a directional derivative of a certain point, wherein a norm of the gradient vector equals to the maximum value of the directional derivative, and the drawing unit is specifically for drawing a first signal curve of the gradient vector of the detection signal against the relative distance of the detected object in the first direction;
wherein, the calculating unit is specifically for, based on the characteristics of normal distribution of the gradient vector, when ξ is a random variable following normal distribution, μ is mathematical expectation, and σ is mean square error, calculating the probability of the gradient vector being in the interval of (μ−ασ, μ+ασ) to be 0.9875 when α=2.5 and obtaining the interval of the gradient vector for α=2.5 according to:
P
⁡
(
ξ
)
=
P
⁡
(
μ
-
a
⁢
⁢
σ
<
ξ
<
μ
+
a
⁢
⁢
σ
)
=
∫
μ
-
a
⁢
⁢
σ
μ
+
a
⁢
⁢
σ
⁢
ydx
,
⁢
where
(
1
)
y
=
P
⁡
(
x
)
=
1
2
⁢
⁢
πσ
2
⁢
e
-
(
x
-
μ
)
2
2
⁢
⁢
σ
2
;
(
2
)
wherein the determining unit is specifically for determining that the amplitude of the detection signal is the anomalous value when the gradient vector of the first position exceeds a predetermined threshold of the interval of the gradient vector.

84 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/125,181Filed 24 Jun 2016
Priority: CN 2015 1 042268116 Jul 2015
Published: US 2017/0176391 A122 Jun 2017
Granted: 12 May 2020
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G01N 27/82
By investigating magnetic variables: for investigating the presence of flaws
G01R 19/04
Arrangements for measuring currents or voltages or for indicating presence or sign thereof: measuring peak values or amplitude or envelope of AC…
G01R 33/10
Measuring direction or magnitude of magnetic fields or magnetic flux: plotting field distribution ; Measuring field distribution
G01R 33/1223
Measuring magnetic properties of articles or specimens of solids or fluids: measuring permeability, i.e. permeameters