JP2013113585A - Defect detection method on slit surface of electrode substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defect detection method capable of accurately detecting existence/non-existence of a defect such as burr and a foreign matter on a slit surface of an electrode substrate to be continuously conveyed.SOLUTION: In the defect detection method for detecting burr 5 generated on a slit surface 1a of an electrode substrate 1 when slitting the electrode substrate 1, an image processing apparatus 22 detects a vertex A which does not exist on a reference surface α of a core material 2 and detects an inclination angle θ1 of the burr 5. When the inclination angle θ1 of the burr 5 is a predetermined angle or more, a length of a segment AD is compared with a standard length X, and when the length of the segment AD is the standard length X and more, the burr 5 is determined as a defect, and when the inclination angle θ1 of the burr 5 is less than the predetermined angle, a vertex B whose distance is closer than the vertex A is detected, a length of a segment BE connecting the vertex B to a middle point of an opposite side of the vertex B is compared with the standard length X, and when the length of the segment BE is the standard length X and more, the burr 5 is determined as a defect.

Description

  The present invention relates to a technique of a defect detection method for detecting defects such as burrs and foreign matters on a slit surface (cut surface) of an electrode substrate.

Conventionally, in the field of lithium ion batteries and the like, sheet-like electrode base materials formed by applying an active material or the like to the front and back surfaces of a core material such as a metal foil have been widely used.
Such an electrode base material is used by slitting (cutting) it into a predetermined width and length using an apparatus such as a slitter. When the slit is formed, burrs from the core material are formed on the slit surface. In some cases, burrs that are generated or shredded become foreign matters and remain on the slit surface.
Since such burrs and foreign matters cause a short circuit inside the battery, it is necessary to confirm that no burrs or foreign matters having a predetermined size or larger exist on the slit surface.

Conventionally, various techniques for detecting a defect such as a minute burr generated in a product have been studied. For example, a burr detection method disclosed in Patent Document 1 shown below has become publicly known. Yes.
In the prior art disclosed in Patent Document 1, two images are selected from among images continuously captured by a camera, compared, and the size of a portion having different brightness when the two images are superimposed Based on the above, it is configured to determine the presence or absence of burrs.

JP 2009-92474 A

  However, in the prior art disclosed in Patent Document 1, it is difficult to use for the purpose of continuously inspecting the slit surface of the electrode substrate, and burrs and foreign substances existing on the slit surface of the electrode substrate are inlined. It could not be detected accurately.

  The present invention has been made in view of such a current problem, and provides a defect detection method capable of accurately and continuously detecting the presence or absence of defects such as burrs and foreign matters on the slit surface of an electrode substrate. The purpose is to do.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, when slitting a sheet-like electrode substrate comprising a core material that is a metal foil-like member, and a coating layer formed on the front surface and the back surface of the core material, A defect detection method for detecting a burr having a triangular shape generated on a slit surface of an electrode base material, wherein the triangular burr is detected based on image data obtained by imaging the slit surface by an image processing device. While detecting the first vertex that does not exist on the reference surface of the core material among each vertex, the first line segment connecting the first vertex and the midpoint of the opposite side of the first vertex, An inclination angle of the burr that is an angle formed with a reference plane of the core material is detected, and when the inclination angle of the burr is equal to or larger than a predetermined angle, the length of the first line segment is set to a predetermined first length. The length of the first line segment is When the value is greater than or equal to the value, the burr is determined to be a defect, and when the burr inclination angle is less than a predetermined angle, the first burr of the burr is closer to the first crest. Two vertices are detected, the length of the second line segment connecting the second vertex and the midpoint of the opposite side of the second vertex is compared with a predetermined first threshold, and the second vertex When the length of the line segment is equal to or greater than the first threshold, the burr is determined as a defect.

  In Claim 2, when slitting a sheet-like electrode base material provided with the core material which is a metal foil-like member, and the coating layer formed in the surface and the back of the core material, the electrode base A defect detection method for detecting foreign matter generated on a slit surface of a material, wherein an image processing device detects a maximum length of the foreign matter and an area of the foreign matter based on image data obtained by imaging the slit surface. When the straight line set in the direction of the maximum length of the foreign matter detects an inclination angle of the foreign matter that is an angle formed with a reference surface of the core material, and the inclination angle of the foreign matter is equal to or greater than a predetermined angle The maximum length of the foreign matter is compared with a predetermined first threshold, and when the maximum length of the foreign matter is not less than the first threshold, the foreign matter is determined as a defect and The tilt angle is less than the specified angle In some cases, the maximum length of the foreign matter is compared with a predetermined second threshold, and when the maximum length of the foreign matter is equal to or greater than the second threshold, the area of the foreign matter is set to a predetermined third threshold. If the area of the foreign matter is equal to or greater than a predetermined third threshold value, the foreign matter is determined as a defect.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect, burrs existing on the slit surface of the electrode base material can be detected as defects continuously and accurately in-line.

  In Claim 2, the foreign material which exists in the slit surface of an electrode base material can be detected as a defect continuously and accurately with in-line.

The schematic diagram which shows the whole structure of the electrode base material to which the defect detection method which concerns on one Embodiment of this invention is applied. 1 is a schematic diagram showing an overall configuration of an image inspection system that realizes a defect detection method according to an embodiment of the present invention. The flowchart which shows the flow of the defect detection method for detecting the burr | flash which concerns on one Embodiment of this invention. Explanatory drawing of the defect detection method (in the case of sin (theta) 1> = Z / X) for detecting the burr | flash which concerns on one Embodiment of this invention. Explanatory drawing of the defect detection method (in the case of sin (theta) 1 <Z / X) for detecting the burr | flash which concerns on one Embodiment of this invention. The flowchart which shows the flow of the defect detection method for detecting the foreign material which concerns on one Embodiment of this invention. Explanatory drawing of the defect detection method (in the case of sin (theta) 2> = Z / X) for detecting the foreign material which concerns on one Embodiment of this invention. Explanatory drawing of the defect detection method (in the case of sin (theta) 2 <Z / X) for detecting the foreign material which concerns on one Embodiment of this invention.

Next, embodiments of the invention will be described.
First, the structure of the electrode base material to which the defect detection method according to an embodiment of the present invention is applied will be described with reference to FIG.
As shown in FIG. 1, an electrode substrate 1 to which a defect detection method according to an embodiment of the present invention is applied includes, for example, a core material 2 that is a current collector made of a metal foil such as copper or aluminum, and It is a sheet-like member composed of coating layers 3 and 3 formed by applying a paste material composed of an active material, a conductive material, a binder, and the like on the front and back surfaces of the core material 2.

  Such an electrode substrate 1 is used after being cut into a necessary width and length by a cutting device such as a slitter. The presence or absence of burrs 5 and foreign matter 6 on the cut surface (referred to as slit surface 1a). It is indispensable to confirm the quality of the battery.

Moreover, when the electrode base material 1 is cut | disconnected by cutting devices, such as a slitter, arrangement | positioning of the core material 2 may shift | deviate.
That is, as shown in FIG. 1, even if the reference surface of the core material 2 is at the position γ before the slit, the reference surface of the core material 2 may be displaced to the position α after the slit.
In the present embodiment, when measuring the length of the burr 5 or the foreign material 6 in consideration of the displacement of the core material 2, the reference surface α after the slit is used instead of the reference surface γ before the slit. The standard is used.

Next, a defect detection method according to an embodiment of the present invention will be described with reference to FIGS.
The defect detection method according to the embodiment of the present invention is realized by inspecting the slit surface 1a of the electrode substrate 1 using an image capturing system 20 as shown in FIG.

The image capturing system 20 includes a camera 21, an image processing device 22, and the like. The burrs 5 and the foreign matter 6 are continuously detected in-line by continuously capturing images and processing the captured image data continuously by the image processing device 22.
That is, the defect detection method according to an embodiment of the present invention is realized by an image processing program installed in the image processing apparatus 22.

And according to the defect detection method which concerns on one Embodiment of this invention, while being able to detect the burr | flash 5 which arose in the core material 2 of the electrode base material 1, it is shredded from the core material 2 of the electrode base material 1. Thus, the foreign matter 6 generated in the coating layer 3 can be detected.
In the following, description will be made separately for the burr 5 detection method and the foreign material 6 detection method.

First, the burr 5 detection method in the defect detection method according to an embodiment of the present invention will be described.
In the following description, a substantially triangular burr 5 as shown in FIGS. 4 and 5 is set as a defect detection target. When the burr 5 is detected by the image processing device 22, first, each vertex of the triangle is represented by A. , B and C. Here, a vertex that is not on the reference plane α of the core material 2 is selected as the vertex A, and a vertex that is closer to the vertex A than the vertex C is selected as the vertex B.

Further, the midpoints D, E, and F of the opposite side are defined in correspondence with the vertices A, B, and C.
Furthermore, each line segment AD, BE, CF that passes through the center of gravity G of the triangle ABC that connects each vertex A, B, C and each midpoint D, E, F of the opposite side is defined.

The length of the line segment AD at this time is defined as the length L1 of the burr 5, and the length of the line segment BE at this time is defined as the width W1 of the burr 5.
Further, an angle formed by the reference plane α of the core material 2 and the line segment AD is defined as an inclination angle θ1 of the burr 5.

  Further, as design conditions for the electrode base material 1 at this time, an allowable maximum length of the burr 5 (hereinafter referred to as a standard length) is defined as X, and a thickness of the core material 2 is defined as Z.

As shown in FIG. 3, in the defect detection method according to an embodiment of the present invention, first, determination based on the inclination angle θ1 is performed (STEP-101).
Specifically, the image processing device 22 determines whether or not the following formula 1 is satisfied.
That is, here, the image processing device 22 determines whether or not the inclination angle θ1 is equal to or greater than a predetermined angle. The value of sin θ1 is AH / AD when the intersection of the perpendicular to the reference plane α drawn from the vertex A and the reference plane α is defined as H.

If the above formula 1 is satisfied, then the length L1 of the burr 5 is compared with the standard length X which is the first threshold (STEP-102).
Specifically, the image processing device 22 determines whether or not the following Expression 2 is satisfied (that is, whether or not the length L1 of the burr 5 is equal to or greater than the standard length X).

If the above Expression 2 is satisfied, the image processing device 22 determines that the burr 5 is defective (STEP-103).
Alternatively, when Expression 2 is not satisfied, the image processing device 22 determines that the burr 5 is not a defect (STEP-104).

If the above formula 1 is not satisfied (that is, sin θ1 <Z / X), then the width W1 of the burr 5 is compared with the standard length X which is the first threshold (STEP-105).
Specifically, the image processing device 22 determines whether or not the following Expression 3 is satisfied (that is, whether or not the width W1 of the burr 5 is equal to or greater than the standard length X).

And when satisfy | filling the said Numerical formula 3, it determines with the burr | flash 5 being a defect by the image processing apparatus 22 (STEP-106).
Or when not satisfy | filling the said Numerical formula 3, it determines with the burr | flash 5 not being a defect by the image processing apparatus 22 (STEP-104).

  That is, the defect detection method according to an embodiment of the present invention includes a core material 2 that is a metal foil-like member, and coating layers 3 and 3 formed on the front surface and the back surface of the core material 2. A defect detection method for detecting a burr 5 having a triangular shape generated on a slit surface 1a of an electrode base material 1 when slitting a sheet-like electrode base material 1. Based on the image data obtained by imaging the surface 1a, the vertex A, B, and C of the burr 5 is detected as the first vertex A that does not exist on the reference surface α of the core material 2, and the vertex A and A line segment AD, which is a first line segment connecting the midpoint D of the opposite side of the vertex A, detects an inclination angle θ1 of the burr 5 that is an angle formed with the reference plane α of the core material 2, and an inclination angle of the burr 5 When θ1 is equal to or greater than a predetermined angle (ie, sin θ1 ≧ X / Z) The length of the line segment AD is compared with a standard length X that is a predetermined first threshold. If the length of the line segment AD is equal to or greater than the standard length X, the burr 5 is defective. When the inclination angle θ1 of the burr 5 is less than a predetermined angle (that is, when sin θ1 <X / Z), the vertex A of the burr 5 is determined by the vertex A. The vertex B, which is the second vertex that is close in distance, is detected, and the length of the line segment BE, which is the second line segment connecting the vertex B and the midpoint E of the opposite side of the vertex B, is compared with the standard length X. When the length of the line segment BE is equal to or greater than the standard length X, the burr 5 is determined as a defect.

  With such a configuration, the burr 5 present on the slit surface 1a of the electrode substrate 1 can be detected as a defect continuously and accurately in-line.

Next, a method for detecting the foreign matter 6 in the defect detection method according to an embodiment of the present invention will be described.
In the following description, a substantially rectangular foreign substance 6 as shown in FIGS. 7 and 8 is a defect detection target, and the foreign substance 6 is detected by the image processing device 22 based on the image of the slit surface photographed by the camera 21. When detected, first, each vertex of the rectangle is defined as A, B, C, and D.
In this embodiment, for the sake of simplicity of explanation, a case where a substantially rectangular foreign object 6 is a detection target is described as an example. However, a foreign object that is a defect detection target by the defect detection method according to the present invention is described. However, the present invention is not limited to this, and can be applied regardless of the outer shape of the foreign matter.

The maximum length of the foreign matter 6 at this time is the length of the line segment AC, and this maximum length is defined as the maximum length L2 of the foreign matter 6.
Furthermore, an angle formed by the reference plane α of the core material 2 that is a boundary line between the core material 2 and the coating layer 3 and a straight line K obtained by extending the line segment AC is defined as an inclination angle θ2 of the foreign material 6.
Further, the area of the foreign material 6 (here, the area of the square ABCD) S is calculated by the image processing device 22.

  Moreover, as a design condition of the electrode base material 1 at this time, an allowable maximum area (hereinafter referred to as a standard area) of the foreign material 6 is defined as Y, and a thickness of the core material 2 is defined as Z.

As shown in FIG. 6, in the defect detection method according to the embodiment of the present invention, first, determination based on the inclination angle θ2 is performed (STEP-201).
Specifically, the image processing device 22 determines whether or not the following Expression 4 is satisfied.
That is, here, the image processing device 22 determines whether or not the inclination angle θ2 is equal to or larger than a predetermined angle. Note that the value of the inclination angle θ2 is θ2 = 0, for example, as shown in FIG. 8 (when the straight line K and the reference plane α do not intersect).

And when satisfy | filling the said Numerical formula 4, next, the maximum length L2 of the foreign material 6 is compared with the standard length X which is a 1st threshold value (STEP-202).
Specifically, the image processing device 22 determines whether or not the following Expression 5 is satisfied.

And when satisfy | filling said Numerical formula 5, it determines with the foreign material 6 being a defect by the image processing apparatus 22 (STEP-203).
Or when not satisfy | filling the said Numerical formula 5, it determines with the image processing apparatus 22 that the foreign material 6 is not a defect (STEP-204).

In addition, when the above formula 4 is not satisfied, the maximum length L2 of the foreign material 6 is compared with a second threshold value set with the standard area Y as a reference (STEP-205).
Specifically, the image processing device 22 determines whether or not the following Expression 6 is satisfied.

And when satisfy | filling the said Numerical formula 6, the area S of the foreign material 6 is further compared with the standard area Y which is a 3rd threshold value (STEP-206).
Specifically, the image processing device 22 determines whether or not the following Expression 7 is satisfied.

If the above Expression 7 is satisfied, the image processing device 22 determines that the foreign material 6 is defective (STEP-207).
Or when the said Numerical formula 6 and the said Numerical formula 7 are not satisfy | filled, it determines with the foreign material 6 not being a defect by the image processing apparatus 22 (STEP-204).

  That is, the defect detection method according to an embodiment of the present invention includes a core material 2 that is a metal foil-like member, and coating layers 3 and 3 formed on the front surface and the back surface of the core material 2. This is a defect detection method for detecting foreign matter 6 generated on the slit surface 1a of the electrode substrate 1 when slitting the sheet-like electrode substrate 1, and an image obtained by imaging the slit surface 1a by the image processing device 22 Based on the data, the maximum length L2 of the foreign matter 6 and the area S of the foreign matter 6 are detected, and the straight line K set in the direction of the maximum length L2 of the foreign matter 6 is an angle formed with the reference plane α of the core material 2. When a tilt angle θ2 of a foreign object 6 is detected and the tilt angle θ2 of the foreign object 6 is equal to or larger than a predetermined angle (that is, when sin θ2 ≧ X / Z), the maximum length L2 of the foreign object 6 is Compared with the length X, the maximum length L2 of the foreign matter 6 is the standard When the thickness X is equal to or greater than X, the foreign object 6 is determined as a defect, and when the inclination angle θ2 of the foreign object 6 is less than a predetermined angle (that is, when sin θ2 <X / Z), the maximum of the foreign object 6 is obtained. When the length L2 is compared with a predetermined second threshold (that is, 2Y / Z), and the maximum length L2 of the foreign material 6 is equal to or greater than the second threshold (that is, when L2 ≧ 2Y / Z) ), The area S of the foreign matter 6 is compared with a predetermined third threshold (ie, the standard area Y), and when the area S of the foreign matter 6 is equal to or greater than the standard area Y (ie, S ≧ Y). The foreign matter 6 is determined as a defect.

  With such a configuration, the foreign matter 6 present on the slit surface 1a of the electrode substrate 1 can be detected as a defect continuously and accurately in-line.

  In the present embodiment, the defect detection method for the foreign material 6 that is completely separated from the core material 2 is exemplified. For example, the connection length at the connection location between the burr 5 and the core material 2 is illustrated. In such a short case, it is possible to apply a defect detection method for detecting a foreign matter to the burr 5 by regarding the burr 5 as a foreign matter 6 even in the embodiment of the burr 5.

DESCRIPTION OF SYMBOLS 1 Electrode base material 1a Slit surface 2 Core material 3 Coating layer 5 Burr 6 Foreign material 22 Image processing apparatus

Claims (2)

A core material that is a metal foil,
A coating layer formed on the front surface and the back surface of the core material;
When slitting a sheet-like electrode substrate comprising:
A defect detection method for detecting burrs having a triangular shape generated on the slit surface of the electrode substrate,
Depending on the image processing device,
Based on image data obtained by imaging the slit surface,
While detecting the first vertex that does not exist on the reference surface of the core material among the respective vertices of the triangular burr,
A first line segment connecting the first vertex and a midpoint of the opposite side of the first vertex detects an inclination angle of the burr that is an angle formed with a reference surface of the core material;
When the inclination angle of the burr is not less than a predetermined angle,
Comparing the length of the first line segment with a predetermined first threshold;
When the length of the first line segment is not less than the first threshold,
While determining the burr as a defect,
The inclination angle of the burr is
When it is less than the predetermined angle,
Among the vertices of the burr, detect a second vertex closer to the first vertex,
Comparing the length of a second line segment connecting the second vertex and the midpoint of the opposite side of the second vertex with a predetermined first threshold;
When the length of the second line segment is not less than the first threshold,
The burr is determined as a defect,
A method for detecting a defect on a slit surface of an electrode substrate. A core material that is a metal foil,
A coating layer formed on the front surface and the back surface of the core material;
When slitting a sheet-like electrode substrate comprising:
A defect detection method for detecting foreign matter generated on the slit surface of the electrode substrate,
Depending on the image processing device,
Based on image data obtained by imaging the slit surface,
While detecting the maximum length of the foreign matter and the area of the foreign matter,
A straight line set in the direction of the maximum length of the foreign matter detects an inclination angle of the foreign matter that is an angle formed with a reference surface of the core material;
When the tilt angle of the foreign object is equal to or greater than a predetermined angle,
Comparing the maximum length of the foreign object with a predetermined first threshold;
When the maximum length of the foreign matter is not less than the first threshold value,
While determining the foreign matter as a defect,
The tilt angle of the foreign matter is
When it is less than the predetermined angle,
Comparing the maximum length of the foreign object with a predetermined second threshold;
When the maximum length of the foreign matter is not less than the second threshold value,
Comparing the area of the foreign object with a predetermined third threshold;
When the area of the foreign material is not less than a predetermined third threshold value,
The foreign matter is determined as a defect,
A method for detecting a defect on a slit surface of an electrode substrate.

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