JP2009176648A - Foreign matter detecting device for metal porous body, and metal porous body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foreign matter detecting device for a metal porous body, enabling continuously, efficiently, easily and surely the detection of foreign matter deposited on the metal porous body. <P>SOLUTION: The foreign matter detecting device for the metal porous body is provided for detecting foreign matter deposited on the sheet metal porous body containing dominantly nickel. The foreign matter reflects the wavelength component of light different from that of Ni. A color image pick-up means is arranged at least on the single face of the metal porous body. The images of a plurality of color tone components are extracted from images picked up by the color image pickup means. On the basis of the degree of a brightness difference between the images of the plurality of color tone components, the foreign matter is detected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus for detecting foreign matter adhering to a porous metal body mainly composed of nickel used as a positive electrode material of a secondary battery such as a nickel metal hydride battery, and a porous metal body inspected using the apparatus.

  The metal porous body used for the battery electrode is mainly a hoop material obtained by subjecting a sheet-like three-dimensional network resin foam to a conductive treatment, electroplating nickel, and then baking and reducing it. Is used. Since these porous metal bodies have a spongy form, a large surface area per unit volume produces good characteristics when used as a battery.

  In recent years, higher performance has been required for this porous metal body. One of them is to prevent foreign matters such as metal impurities from adhering to the surface of the metal porous body. If metal impurities adhere to the surface of the metal porous body, there is a possibility that the output will decrease in the case of a secondary battery. Among these metal impurities, copper-based foreign matters that are easily dissolved and re-deposited in the battery are most likely to affect the battery characteristics.

However, the surface of the metal porous body has a concavo-convex structure, and it is formed in a mesh shape up to the thickness direction of the sheet-like product. Therefore, even if foreign matter adheres to this surface in the production process, etc., it cannot be easily identified with the human eye. To accurately detect and remove foreign matter, the product is finally cut into small pieces of the dimensions to be used. However, the inspection has been performed by observing one by one with a microscope or a magnifying glass.
However, in this method, products on continuous hoops need to be cut at an early stage, which not only lowers productivity but also relies on visual confirmation by humans, which may cause problems such as detection errors. .

  As described above, the present invention provides a foreign object detection device for a metal porous body that can continuously and efficiently detect foreign substances adhering to a metal porous body, easily and reliably, and easily handle the foreign objects. It is an object of the present invention to provide a high-quality porous metal body with no foreign matter adhered by inspecting it using the apparatus.

  As a result of intensive studies to solve the above problems, the present inventors have found that it is effective to use the difference in the wavelength components of light reflected by the foreign material and the metal porous body, and completed the present invention. . That is, the metal porous body foreign material detection device and metal porous body according to the present invention have the following characteristics.

(1) The foreign object detection device for a porous metal body according to the present invention is a detection device for foreign matter adhering to a sheet-like metal porous body containing nickel as a main component, and the foreign object reflects a wavelength component of light different from nickel. A color imaging unit is arranged on at least one surface of the porous metal body, and a plurality of color component images are extracted from an image captured by the color imaging unit, and the difference between the plurality of color component images The foreign matter is detected based on the amount.
(2) The foreign object detection device for a porous metal body according to (1), wherein the color tone component is two or more of three components of red, blue, and green.
(3) In the foreign material detection device for a metal porous body according to (1), the foreign material is a foreign material containing copper, and the color tone component is two components of red and blue, or red and green It is characterized by being two components.
(4) In the foreign substance detection device for a metal porous body according to (1), the color tone component is a component having a wavelength of 600 nm or more and two components having a wavelength of 560 nm or less.
(5) In the metal porous body foreign matter detection device according to any one of (1) to (4), a light emitting unit is disposed on the same surface side as the color imaging unit with respect to the metal porous body. And
(6) In the foreign object detection device for a porous metal body according to any one of (1) to (5), the sheet-like metal porous body supply unit wound in a roll shape and the sheet-like metal porous body 1 set or 2 sets of light emitting means and color image pickup means between one side or both sides of the sheet-like metal porous body between the supply section and the winding section. Features.
(7) In the foreign object detection device for a porous metal body according to any one of (1) to (6), a distance between the color imaging unit and the sheet-like metal porous body is set to a focal length of the color imaging unit. It is characterized by being set differently.

(8) In the metal porous body foreign matter detection apparatus according to (6) or (7), a foreign matter detection location is clearly defined between the color imaging means installation portion and the sheet-like metal porous body winding portion. A marking means is formed.
(9) In the foreign object detection device for a porous metal body according to (8), the marking means includes a single or a plurality of lines extending in the traveling direction of the sheet metal porous body where the foreign object exists. It is described.
(10) In the foreign object detection device for a metal porous body according to (8) above,
The marking means is means for providing an opening in the sheet-like metal porous body.
(11) In the metal porous body foreign material detection device according to (8), the marking means is a means for attaching a light shielding member to a sheet-like metal porous body.
(12) In the metal porous body foreign material detection device according to (11), the light shielding member is a metal porous body having the same composition as the sheet-like metal porous body.

(13) The porous metal body for a secondary battery according to the present invention is characterized in that it has undergone a foreign object detection step by the foreign object detection device for a metal porous body according to any one of (1) to (12).

  The foreign object detection device for a porous metal body according to the present invention makes it possible to continuously and efficiently detect the foreign matter adhering to the porous metal body containing nickel as a main component, easily and reliably. In particular, it is effective for the detection of metallic foreign matters including copper. For this reason, it becomes easy to deal with the foreign matter, and a high-quality porous metal body having no foreign matter adhesion that has been inspected and processed using the foreign matter detection device according to the present invention is preferably used for, for example, a secondary battery. be able to.

A foreign object detection device for a porous metal body according to the present invention is a detection device for foreign matter adhering to a sheet-like metal porous body containing nickel as a main component, and the foreign object reflects a wavelength component of light different from nickel. A color imaging means is disposed on at least one surface of the porous metal body, and images of a plurality of color tone components are extracted from an image captured by the color imaging means, and a difference amount between the images of the color tone components is determined based on And detecting the foreign matter.
Since the metal porous body has a concavo-convex structure, the foreign matter adhering to the metal porous body is hidden in the mottled pattern, and it is difficult to detect minute foreign matter. However, in the case of a metal porous body mainly composed of nickel, the metal porous body is white to black and colorless. On the other hand, if the foreign material is colored, if the image is taken with an imaging device such as a color camera, The spectral components of the colors are different. By paying attention to this, it is possible to extract the image of the foreign matter from the difference between the plurality of tone images. For this reason, if it is a foreign material which reflects the wavelength component of light different from nickel which is a base metal of a metal porous body, it is possible to detect effectively. The foreign material is not particularly limited. For example, a metallic foreign material including a metal impurity, and particularly a copper-based foreign material containing copper that is likely to be dissolved and re-deposited in the battery and affect the battery characteristics. Is preferably detected and removed.
If it is an optical type, since a detection element can be made small compared with other detection principles, it becomes possible to detect minute foreign matter. The color imaging means is not limited to a color camera, and may be a color line sensor, for example.

  The color component is two or more of three components of red, blue, and green. Since the captured image is extracted using the three primary colors of red, blue, and green, a standard apparatus can be used, so that the apparatus can be simplified. An image may be extracted based on all of red, blue, and green, and the difference can be calculated using only two of them.

The difference between the captured images can be calculated using only two of the three primary colors of red, blue, and green. In this case, particularly when the foreign substance is copper, the largest difference is generated between the red component and the blue component, so that the sensitivity is increased as compared with the case where the green component is used.
Also, when processing is performed using only two components, processing can be performed at a higher speed than when three components are used. For this reason, the color tone component is preferably two components of red and blue, or two components of red and green. In particular, when detecting a foreign matter containing copper, it is preferable to compare the difference in luminance between the two components of red and blue.

Hereinafter, a case where the foreign matter is a copper-based foreign matter containing copper will be described as an example.
As described above, the reflected light spectrum of nickel as a base is almost flat regardless of the wavelength, whereas the reflected light spectrum of the copper-based foreign matter to be detected varies greatly between 560 nm and 600 nm (see FIG. 7). Therefore, it is possible to detect with high sensitivity by comparing the wavelength components before and after this. That is, the color tone component is preferably a component having a wavelength of 600 nm or more and two components having a wavelength of 560 nm or less.

  The foreign object detection device for a metal porous body according to the present invention is characterized in that a light emitting means is disposed on the same surface side as the color imaging means with respect to the metal porous body. For the metal porous body, it can be placed on the opposite side to the case where the light emitting means is placed on the same side as the color imaging means, but when placed on the opposite side, the transmitted light of the metal porous body is detected, The shadow of the metal porous body or the foreign object is photographed, and it becomes difficult to detect the difference in the color tone of the surface. Therefore, it is preferable to arrange them on the same plane. Moreover, when arrange | positioning on the opposite surface, the light quantity from a light emission means attenuate | damps and the problem of the enlargement of a light emission means arises.

  The light emitting means may generate continuous light, but in order to obtain a sufficient amount of light, a high output is required, in which case the amount of heat generated becomes large and the ambient temperature rises. It is desirable to use the illuminator. In addition, since the image of the foreign material on the continuously moving material is captured, if the exposure time of the camera becomes longer, the image of the foreign material extends in the moving direction and the accuracy of the size of the foreign material to be detected decreases. It is desirable to use short strobes.

Further, the foreign object detection device according to the present invention has a supply part of the sheet-like metal porous body wound in a roll shape, and a winding part of the sheet-like metal porous body, the supply part and the take-up part And one or two sets of light emitting means and color imaging means are provided on one side or both sides of the sheet-like metal porous body.
When detecting foreign matter adhering to the sheet-like metal porous body, continuously supplying the metal porous body wound in a roll shape, winding it, and placing the light emitting means and the color imaging means between them As a result, continuous inspection is possible and efficient inspection is possible. When two sets are provided, foreign matter detection on both the front and back sides of the metal porous body can be performed.

  The distance between the color imaging unit and the sheet-like metal porous body is set to be different from the focal length of the color imaging unit, so that the captured image is out of focus. When focusing, red, blue and green spots are observed on the metal porous body due to the unevenness of the surface of the metal porous body, and this is erroneously detected as a foreign substance. Therefore, it is preferable to shift the focus. A stopper or the like may be provided on the back side of the metal porous body in order to prevent the focal lengths from matching due to vibration of the sheet-like metal porous body during traveling.

  The foreign matter detection apparatus according to the present invention is characterized in that a marking means for clearly indicating a foreign matter detection location is formed between the color imaging means installation portion and the winding portion of the sheet metal porous body. . When a foreign object is detected based on the information of the color imaging means, the location of the foreign object is marked, thereby facilitating the identification of the position of the foreign object and handling such as removing the foreign object.

  In the marking means, the position information of the foreign matter is clearly indicated by printing on the porous metal body one or a plurality of lines extending in the traveling direction of the sheet-like porous metal body where the foreign matter exists. To do. When marking with a marker such as a magic marker, the location of the foreign object is indicated by one or more lines, not only making the position of the foreign object clear, but also when drawing the line It is only necessary to do so, and the equipment can be simplified.

  In the case of drawing a plurality of lines, it is easy to specify a foreign substance in a later process by printing so as to be sandwiched between two lines (see FIG. 4). May not be printed, in which case only one line should be drawn inside (see FIG. 5). When marking with only one line, it is difficult to specify the position of the foreign matter, but since only one line needs to be drawn, there is an advantage that the structure of the marking portion can be simplified.

  The marking means may be a means for providing an opening in the sheet-like metal porous body. When the workpiece is subjected to processing for detecting a foreign substance and providing an opening around the foreign substance, processing such as automatic removal of a foreign substance adhesion portion can be easily performed in a subsequent process based on the information on the presence or absence of the hole.

  Furthermore, the marking means may be a means for attaching a light shielding member to the sheet-like metal porous body. Even if a light shielding member is attached to the periphery of a foreign object detected, processing such as automatic removal of a foreign material adhesion point can be easily performed in the subsequent process based on the information on the presence or absence of the member.

  The light shielding member is a porous metal body having the same composition as the sheet-like porous metal body. The material of the light shielding member is not particularly limited. However, if the light shielding member is a material having the same composition as the workpiece, even if the workpiece cannot be removed in a later process and mixed into the product, Does not adversely affect the characteristics of the product used. Furthermore, if it is a metal porous body, it becomes an interface contact between a workpiece and a metal porous body, and it can be pasted without using a special adhesive etc. Because there is, it is preferable.

Whether the marking means is a method of printing a line, forming an opening, or attaching a light shielding member, foreign matter can be removed in a subsequent process based on such information. At this time, it is not easy to visually check the small foreign matter adhered to the surface of the metal porous body in the state where the metal porous body is flowing even if the foreign material adhesion portion is marked. When the vehicle is run in a flat shape and illuminated from below, a marking portion (foreign matter) can be easily found.

  The porous metal body for a secondary battery according to the present invention is characterized in that it has been subjected to a foreign object detection step by a foreign object detection device for the metal porous body. The metal porous body from which foreign matter is detected using the foreign matter detection device according to the present invention and from which the foreign matter has been removed is effective when used, for example, as a material for a secondary battery whose characteristics deteriorate when foreign matter is attached. Is.

  As described above, the present invention can continuously and efficiently detect the copper-based foreign matter adhering to the metal porous body containing nickel as a main component, easily and reliably, and easily deal with the foreign matter. By inspecting using this apparatus, it is possible to obtain a high-quality porous metal body with no foreign matter adhered.

FIG. 1 is a schematic block diagram showing a first embodiment of the present invention.
The porous metal body made of nickel component is wound around a stainless steel reel installed in the supply section on the left side of the figure. In the figure, the sheet-like porous metal body is sent out while rotating counterclockwise. ing. Thereafter, the metal porous body passes through the plane portion via a transport roller and a roller (work pressing roller) that presses the traveling metal porous body. In this plane portion, two xenon / stroboscopic illuminators (15 W) were installed as light emitting means on the upper side of the metal porous body, and a color camera was installed on the upper part that is flush with the metal porous body. Note that a strobe with a short light emission time was used as the light emitting means from the viewpoint of the above-described suppression of the increase in the ambient temperature and the reduction in the accuracy of the foreign matter size.

In this embodiment, the distance between the camera and the sheet-like metal porous body was set to 405 mm. The focal length of the camera used in this example was 415 mm. However, when the focal length of the camera matches the actual object (that is, when the focus is adjusted), the influence of the unevenness on the surface of the metal porous body is affected. A red, blue, and green spot was observed, and this was mistakenly detected as a foreign object. Therefore, by shifting the camera focus by 10 mm, the image is blurred, which eliminates false detection.
In addition, in order to prevent the traveling metal porous body from being in a state where the focal lengths are matched (in focus) due to vibration during traveling, the back of the traveling metal porous body has a “work receiving” as shown in the figure. Was used as a stopper.

In the color camera, reflected light from the porous metal body of light illuminated by the light emitting means was detected, and images of red, blue and green components were extracted. When these three color images are compared, the difference in luminance between the three colors is small in the base nickel metal porous body portion, but the red luminance and green in the adhesion portion of the foreign matter containing copper (copper-based foreign matter adhesion portion). The brightness of blue and blue is very different. Therefore, the difference between these luminances was calculated, and a portion where the difference in luminance was a certain level or more was specified as a copper-based foreign matter adhesion portion.
In this example, the three color images were compared with each other, and the calculation was performed using the value at which the maximum difference occurred. However, as another method, only the difference between the two colors of the red component and the blue component is used. The same detection was possible.

  FIG. 7 shows the result of comparison of the spectrum of the reflected nickel light and the spectrum of the copper foreign matter to be detected. Thus, the reflectivity changes greatly between 560 nm and 600 nm. This difference in reflectance is the difference in luminance between the captured images. By using the colors on both sides of the wavelength between 560 nm and 600 nm, it is possible to accurately detect the copper-based foreign matter. In particular, between the three colors of red, green, and blue, the difference in reflectance occurs most between red and blue, so the two colors were compared.

In the image for which the difference was calculated, a portion having a value greater than a certain value (a set threshold value or more) was recognized as a foreign object. This threshold is calculated by setting a good range based on the average brightness of the captured image and variations in the brightness, and extracting the location as a foreign object when the good range exceeds either the positive side or the negative side. .
In this calculation, when the range of variation was set to ± 4.5σ (σ: standard deviation), the normal good part and the foreign part could be separated with the highest accuracy, but in the range of ± 3σ to ± 6σ. If so, it could be realized as image processing. In other words, if a threshold value is set in an area of ± 3σ or less, the frequency of false detection of a foreign object is increased even in a location where no foreign object is present. Conversely, if a threshold value is set to ± 6σ or more, it can be overlooked even if a foreign object actually exists. Increased.

  Table 1 summarizes the types and sizes of copper-based foreign substances (foreign substances containing copper) that can be detected by this apparatus. As long as it was a copper-based foreign substance intended to be detected as described in Table 1, it was possible to detect a pure copper, phosphor bronze, or brass, and a foreign substance having a diameter of 0.15 mm or more could be detected. On the other hand, this apparatus did not detect copper foreign matter having a diameter of 0.1 mm or less or nickel foreign matter that does not need to be detected.

When foreign matter was detected in this way, printing indicating the presence of the foreign matter was performed around the foreign matter with a marking pen made of a commercially available magic placed at a stage after the light emitting means and the color camera were installed. As shown in FIG. 4, the printing was performed so as to be sandwiched between two lines. However, at the end of the metal porous body, there are cases where two lines cannot be printed. Only one line was printed.
As described above, the printing unit can also indicate the position of the foreign matter by printing only one line as shown in FIG. The printing position may normally be either the upper or lower part of the foreign matter, but it is necessary to set the printable position at the end of the metal porous body on the sheet (see the case of foreign matter at the end in FIG. 5). . Thus, when printing with only one line, it is difficult to specify the position of the foreign matter, but since only one line needs to be drawn, there is an advantage that the structure of the marking part can be simplified.

In this way, foreign substances are removed from the marked metal porous body by the operator at the subsequent stage. At this time, even if it is marked, it is not easy to visually check the small foreign matter adhering to the surface of the metal porous body in a state where the metal porous body is flowing, but the sheet-like metal porous body travels in a planar shape. It was also found that the marking part (foreign matter) can be easily found by illuminating from the bottom. For this reason, in the present Example, the planar illuminating device was installed under the metal porous body. In addition to removing foreign matter, it is also possible to cut and remove the periphery of the workpiece to which the foreign matter has adhered. In this embodiment, the operator manually performed cutting work.

In addition, after the cutting and removal, the subsequent porous metal body may be reconnected except for the removal portion, and may continuously be wound around the winding portion, or a new winding may be performed every time cutting is performed without performing a connection operation. It can also be wound on a reel.
In this example, when cut and removed, the front and rear of the cut portion were overlapped and connected by compressing the portion with a pressure-bonding roller. In general, the metal porous body has self-connectivity like Velcro (registered trademark), and can be connected without using an adhesive only by compressing the overlapping portion.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the present invention.
The basic configuration of the present invention is the same as that of the first embodiment. The following mainly describes the differences and their actions or supplementary explanations.
1) The reel rotating direction and feeding position of the supply unit were changed.
As described above, the reel feeding position and the rotation direction of the supply unit and the winding unit do not limit the present invention.
2) A color line sensor was adopted as the color imaging means.
Even if a one-dimensional color line sensor is used without using a two-dimensional image sensor such as a color camera, the size of a foreign substance can be recognized in calculation because the workpiece is continuously running.

3) Two sets of color line sensors and illumination were installed, and foreign matters were detected from the top and bottom (front and back) of the sheet-like metal porous body.
Foreign matter attached to both the upper surface (front surface) and the lower surface (back surface) of the workpiece can be detected.
4) A hole punch was adopted as the marking means.
When marking with a punch, it is possible to perform processing such as automatic cutting and removal based on the punch hole information in a subsequent process without removing foreign matter. Therefore, the visual inspection operator shown in the first embodiment does not have to remove the foreign matter, and therefore only needs to play an auxiliary role.
As shown in FIG. 6, the marking hole was formed with a hole having a diameter of 20 mm at a position lying in the running direction with respect to the foreign matter. However, in order to avoid the overlap of the foreign object and the hole, it is preferable that the foreign object is opened upward when it is below the center in the figure, and when the foreign object is located on the upper side, the hole is opened downward.

FIG. 3 is a schematic block diagram showing a third embodiment of the present invention.
The basic configuration of the present invention is the same as that of the second embodiment. Only the differences are described below.
1) Marking was performed by attaching a light shielding piece.
As in the case of marking with a hole punch, it is possible to perform processing such as automatic cutting and removal based on the information of the light shielding piece in a subsequent process without removing foreign matter.
Here, a circular sheet having a diameter of 30 mm made of the same material as the metal porous body to be inspected is pasted as the light shielding piece. If the same material is used in this way, even if the light shielding piece flows out while being stuck to the metal porous body as a product, there will be no major problem in the subsequent process.

The schematic block diagram which shows schematic structure of the foreign material detection apparatus of this invention. The schematic block diagram which shows schematic structure of the other foreign material detection apparatus of this invention. The schematic block diagram which shows schematic structure of the further another foreign material detection apparatus of this invention. In the foreign material detection apparatus of this invention, explanatory drawing in the case of clearly indicating the position of a foreign material between two lines by the marking means by magic. In the foreign material detection apparatus of this invention, explanatory drawing in the case of clearly indicating the position of a foreign material with one line by the marking means by a magic. Explanatory drawing in the case of marking by opening in the foreign material detection apparatus of this invention. Explanatory drawing of the spectral reflectance of a copper foreign material and a nickel base.

Claims (13)

  An apparatus for detecting foreign matter adhering to a sheet-like metal porous body containing nickel as a main component, wherein the foreign substance reflects a wavelength component of light different from nickel, and color imaging means on at least one surface of the metal porous body And extracting the image of a plurality of tone components from the image captured by the color imaging means, and detecting the foreign matter based on a difference in luminance between the images of the plurality of tone components. Foreign metal detection device for metal porous body.   2. The foreign object detection device for a metal porous body according to claim 1, wherein the color tone component is two or more of three components of red, blue, and green.   2. The porous metal body according to claim 1, wherein the foreign matter is a foreign matter containing copper, and the color tone component is two components of red and blue, or two components of red and green. Foreign object detection device.   2. The foreign object detection device for a metal porous body according to claim 1, wherein the color tone component is a component having a wavelength of 600 nm or more and two components having a wavelength of 560 nm or less.   The foreign object detection device for a metal porous body according to any one of claims 1 to 4, wherein a light emitting means is disposed on the same surface side as the color imaging means with respect to the metal porous body.   A sheet-like metal porous body supply section wound in a roll, and a sheet-shaped metal porous body winding section, between the supply section and the winding section, the sheet-shaped metal porous body The foreign object detection device for a metal porous body according to any one of claims 1 to 5, wherein one or two sets of light emitting means and color imaging means are provided on one side or both sides of the body.   The foreign object of the metal porous body according to any one of claims 1 to 6, wherein a distance between the color imaging unit and the sheet-like metal porous body is set to be different from a focal length of the color imaging unit. Detection device.   8. A marking means for clearly indicating a foreign matter detection location is formed between the color imaging means installation section and the sheet metal porous body winding section. The foreign object detection apparatus of the metal porous body of description.   9. The foreign object detection device for a metal porous body according to claim 8, wherein the marking means describes a place where the foreign substance exists with one or a plurality of lines extending in a traveling direction of the sheet metal porous body. .   The foreign object detection device for a metal porous body according to claim 8, wherein the marking means is means for providing an opening in the sheet-like metal porous body.   The foreign object detection device for a metal porous body according to claim 8, wherein the marking means is means for attaching a light shielding member to the sheet-like metal porous body.   The foreign object detection device for a metal porous body according to claim 11, wherein the light shielding member is a metal porous body having the same composition as the sheet-like metal porous body.   A porous metal body for a secondary battery, which has undergone a foreign object detection step using the foreign object detection apparatus for a metal porous body according to any one of claims 1 to 12.

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