WO2011055728A1 - Method of inspecting obverse surface of continuous cast material - Google Patents

Method of inspecting obverse surface of continuous cast material Download PDF

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Publication number
WO2011055728A1
WO2011055728A1 PCT/JP2010/069529 JP2010069529W WO2011055728A1 WO 2011055728 A1 WO2011055728 A1 WO 2011055728A1 JP 2010069529 W JP2010069529 W JP 2010069529W WO 2011055728 A1 WO2011055728 A1 WO 2011055728A1
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Prior art keywords
light
cast material
magnesium
continuous
cast
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PCT/JP2010/069529
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French (fr)
Japanese (ja)
Inventor
倫正 宮永
正禎 沼野
武志 内原
幸広 大石
望 河部
博 永易
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住友電気工業株式会社
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Publication of WO2011055728A1 publication Critical patent/WO2011055728A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C23/00—Alloys based on magnesium
    • C22C23/02—Alloys based on magnesium with aluminium as the next major constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
    • G01N21/8914—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the material examined
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
    • G01N21/892—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the flaw, defect or object feature examined
    • G01N21/8921—Streaks

Definitions

  • the present invention is a method for inspecting a continuous cast material suitable for inspecting the surface state of a continuous cast material made of magnesium or a magnesium alloy, a method for manufacturing a magnesium substrate material comprising an inspection step by this inspection method, and a method suitable for this inspection method.
  • the present invention relates to a surface inspection apparatus for continuous cast materials.
  • magnesium As a constituent material of various members, magnesium that is lightweight and excellent in specific strength and specific rigidity and magnesium alloy containing various additive elements in magnesium has been studied.
  • Magnesium or a magnesium alloy has a hexagonal crystal structure (hcp structure) and therefore has poor plastic workability at room temperature, so the member made of magnesium or a magnesium alloy (hereinafter referred to as a magnesium-based member) is a die casting method. Cast materials by the thixomold method are the mainstream. Recently, it has been studied to form a casing of a portable electronic device such as a mobile phone or a notebook personal computer by pressing a plate made of an AZ31 alloy according to the ASTM standard.
  • Patent Document 1 discloses a press material obtained by rolling a continuous cast plate made of an alloy equivalent to the AZ91 alloy in the ASTM standard and pressing the obtained rolled plate.
  • the inventors of the present invention have produced a magnesium base member by performing plastic working such as press working on a rolled plate obtained by rolling a continuous cast plate, and a defect such as a minute crack may occur on the surface of the member. I got the knowledge. Since the defects cause poor appearance and quality deterioration, the generation of such defects reduces the yield, and as a result, the productivity of the magnesium-based member decreases.
  • the present inventors have investigated the cause of the defect generated in the magnesium base member in order to eliminate the defect, and found that the minute defect generated on the surface of the cast plate after continuous casting is one cause. It was. Specifically, the present inventors cut a continuous cast plate obtained by continuous casting into a small plate by cutting to a predetermined length, and using a microscope or a penetrating flaw detection method, The surface condition was examined. Then, the above-mentioned small plate has defects with a depth (size in the thickness direction of the small plate) of about 30 ⁇ m to 500 ⁇ m, and such defects (hereinafter referred to as cracks) are considered to remain after rolling. It is done.
  • the cracks are easily formed in a discontinuous line along the traveling direction of the cast plate and have a very narrow width of several tens of ⁇ m or less.
  • the method using a small plate as described above and using a microscope or the like causes a decrease in productivity of the continuous cast material, and is not practical from the viewpoint of industrial production. Therefore, it is desired to develop an inspection method that can detect the minute cracks with high sensitivity and efficiency.
  • one of the objects of the present invention is to provide a surface inspection method for a continuous cast material capable of efficiently and efficiently inspecting the surface state of a continuous cast material made of magnesium or a magnesium alloy.
  • one of the objects of the present invention is to provide a surface inspection apparatus for a continuous cast material suitable for carrying out the surface inspection method.
  • one of the objects of the present invention is to provide a method for producing a magnesium substrate material, which can produce a high-quality magnesium substrate material with high productivity.
  • the inspection can be performed efficiently.
  • the said cast material which advances between the continuous casting machine which continuously casts the cast material which consists of magnesium or a magnesium alloy, and the winding machine which winds up this cast material
  • the present inventors examined an inspection method using an optical imaging device such as a camera.
  • a light source and a camera are arranged, and the camera is arranged so that an image of the detection light can be captured using specular reflection light generated by applying light emitted from the light source to the cast material as the main detection light.
  • the light source and the camera were arranged so that the optical axis of the light source was orthogonal to the surface of the cast material and the optical axis of the camera was also orthogonal.
  • the light source and the camera are arranged so that the light source and the camera are symmetrical with respect to the light incident point on the surface of the cast material.
  • FIG. 3 (I) is a short cut of a continuous cast material to form a small plate, and is an optical micrograph of this small plate
  • Fig. 3 (II) is a schematic diagram for explaining cracks present on the surface of the small plate
  • FIG. 4 and FIG. 4 are metal photographs of the image by the regular reflection light.
  • the direction from the lower side to the upper side of the drawing is the traveling direction of the cast material.
  • FIG. 3 by using a microscope, even the narrow crack described above can be detected with high accuracy.
  • an image with specularly reflected light as the main detection light is picked up, only a mirror-like image as shown in FIG. .
  • the inventors obtained knowledge that the minute cracks can be detected with high accuracy in an image having diffusely reflected light (diffuse reflected light) as the main detection light.
  • the surface inspection method for a continuous cast material of the present invention based on the above knowledge makes light incident on the surface of a cast material made of magnesium or a magnesium alloy continuously cast by a continuous casting machine, and this incident light is incident on the cast material.
  • the irregularly reflected light generated by hitting the surface defect is used as the main detection light, an image obtained by the detection light is captured by an optical image pickup device, and the surface state of the cast material is inspected based on the image obtained by the optical image pickup device.
  • the surface state of a cast material can be continuously test
  • the surface inspection method of the present invention is expected to contribute to producing a continuous cast material with high productivity. Further, since it is possible to easily and accurately detect surface defects such as the above-described minute cracks, when a defective portion is detected, the defective portion can be appropriately removed. Therefore, by detecting the surface defect by the surface inspection method of the present invention and removing the defective portion, the reliability of the cast material and, in turn, the final product using the cast material as a raw material can be improved.
  • imaging by the optical imaging device is performed at a position where the incident light and the regular reflection light of the incident light are substantially not received and the irregular reflection light is received.
  • an optical imaging device may be disposed.
  • the incident angle of the incident light is less than 90 °
  • the inclination angle of the optical axis of the optical imaging device with respect to the surface of the cast material is 60 ° or less.
  • the incident angle of the incident light (the inclination angle of the incident light with respect to the surface of the casting material) is less than 90 °
  • the specularly reflected light generated when the incident light hits the casting material is optical.
  • the imaging device is difficult to receive and the reduction in detection sensitivity caused by receiving the regular reflection light can be reduced.
  • an optical imaging device is also arranged so that the tilt angle of its optical axis is 60 ° or less so that an image of irregularly reflected light based on the incident light can be captured, it is difficult to be affected by specularly reflected light and disturbance light, The inventor obtained that the image by the irregular reflection light described above becomes an image having a large contrast between light and dark.
  • both the incident angle and the inclination angle of the optical axis are preferably 5 ° or more.
  • the incident angle is preferably 5 ° to 70 °
  • the tilt angle of the optical axis is preferably 5 ° to 40 °, and more preferably 35 ° or less.
  • At least a part of the outer periphery of the cast material is covered with a light shielding member that absorbs specularly reflected light of the incident light and shields disturbance light.
  • the light shielding member may be disposed so as not to block the field of view of the optical imaging device that captures an image of diffusely reflected light, and to absorb and shield regular reflected light and disturbance light, and is disposed so as to cover the entire circumference of the cast material. Or you may arrange
  • the continuous casting machine is a twin roll casting machine.
  • twin roll method there are various continuous casting methods such as a twin roll method, a belt and wheel method, and a twin belt method.
  • a twin roll method since the surface in contact with the molten metal appears continuously by the rotation of the roll, a continuous cast material excellent in plastic workability such as rolling can be obtained by efficiently cooling the molten metal and rapidly solidifying it. Can do.
  • the twin roll method tends to cause fine cracks in the cast material, the surface inspection method of the present invention can be used to efficiently detect surface defects such as fine cracks.
  • imaging by the optical imaging machine is performed until the cast material cast by the continuous casting machine is wound up by the winder.
  • the surface inspection method of the present invention can also be applied to a cast material that has been wound once with a winder and then rewound.
  • the inspection of the surface state can be performed on the continuous cast material existing between the continuous casting machine and the winder, the casting process and the inspection process can be overlapped. It can contribute to manufacturing a cast material with high productivity.
  • the magnesium alloy when the continuous cast material is composed of a magnesium alloy, the magnesium alloy may contain Al in excess of 7.5% by mass and 12% by mass or less.
  • the continuous cast material to be inspected by the surface inspection method of the present invention may be Mg, an additive element, and a magnesium alloy composed of the remaining inevitable impurities, in addition to so-called pure magnesium composed of Mg and the remaining inevitable impurities.
  • magnesium alloys containing Al for example, AZ-based alloys (Mg-Al-Zn-based alloys, Zn: 0.2% to 1.5% by weight) and AM-based alloys (Mg-Al-Mn-based alloys, Mn: 0.15 mass% to 0.5 mass%), AS alloys (Mg-Al-Si alloys, Si: 0.6 mass% to 1.4 mass%), Mg-Al-RE (rare earth elements) alloys, AX alloys (Mg- Al-Ca alloys (Ca: 0.2 mass% to 6.0 mass%) and AJ alloys (Mg-Al-Sr alloys, Sr: 0.2 mass% to 7.0 mass%) have excellent corrosion resistance and mechanical strength. Excellent characteristics.
  • magnesium alloys containing more than 7.5% by mass and less than 12% by mass of Al such as Mg-Al-Zn alloy, AZ80 alloy, AZ81 alloy, AZ91 alloy, Mg-Al-Mn alloy, AM100 alloy, etc.
  • the corrosion resistance is further excellent and preferable.
  • the Al content is in the above range, the plastic workability is inferior and minute cracks are likely to occur. Therefore, it is considered to be very preferable to apply the surface inspection method of the present invention to inspect the surface state for a continuous cast material made of a high Al magnesium alloy having an Al content in the above range.
  • the surface inspection method of the present invention is particularly preferably incorporated in the production process of continuous cast material. Therefore, as a method for producing a magnesium substrate material of the present invention for producing a magnesium substrate material made of magnesium or a magnesium alloy, the present invention includes a casting process for producing a continuous cast material by continuously casting magnesium or a magnesium alloy. In addition, it is proposed to include an inspection step by the surface inspection method for the continuous cast material of the present invention.
  • the continuous casting material can be manufactured with high yield and high productivity by performing surface condition inspection on the casting material continuously manufactured in the casting process.
  • the reliability of the final product that uses the material can be improved.
  • the obtained continuous cast material is suitably used for a material of a magnesium base member such as a press material, for example.
  • a material of a magnesium base member such as a press material
  • heat treatment for strain relief and recrystallization, or correction (typically warm correction) and further plastic processing such as press processing.
  • the magnesium-based member is obtained.
  • anticorrosion treatment such as chemical conversion treatment or coating.
  • the surface inspection apparatus of the present invention is an apparatus for inspecting the surface state of a cast material made of magnesium or a magnesium alloy continuously cast by a continuous casting machine, and includes the following light source, optical imaging device, and image processing. It has an inspection department.
  • Light source emits light to the surface of the cast material.
  • Optical imaging device The irregularly reflected light generated when the emitted light hits the surface defect of the cast material is used as the main detection light, and an image by this detection light is taken.
  • Image processing inspection unit Inspects the surface state of the cast material based on the image obtained by the optical imaging device.
  • the image obtained by the irregularly reflected light obtained by the optical imaging device can be configured to be visually confirmed by an operator, for example.
  • the image processing inspection unit automatically performs surface state inspection (typically, the determination of the presence or absence of minute cracks), so that it can be performed in a relatively short time.
  • the surface state of the cast material can be inspected with high accuracy.
  • the image processing inspection unit can binarize the image of the irregularly reflected light and inspect the surface state based on the binarized image.
  • the surface inspection method for a continuous cast material of the present invention and the surface inspection apparatus for the continuous cast material of the present invention can efficiently inspect the surface state of a cast material made of magnesium or a magnesium alloy.
  • the manufacturing method of the magnesium substrate material of the present invention can appropriately detect a defective portion and can manufacture a continuous cast material with high productivity.
  • FIG. 1 is an explanatory view for explaining a surface inspection method for a continuous cast material of the present invention.
  • FIG. 2 is a metal photograph showing an image of irregularly reflected light in a continuously cast magnesium substrate material (cast plate).
  • FIG. 3 (I) is a micrograph of a continuously cast magnesium substrate material (cast plate), and
  • FIG. 3 (II) is a schematic diagram of this micrograph.
  • FIG. 4 is a metal photograph showing an image of regular reflection light on a continuously cast magnesium substrate material (cast plate).
  • the present invention relates to a surface inspection method for inspecting the surface state of a cast material (hereinafter referred to as Mg-based cast material) 100 made of magnesium or a magnesium alloy.
  • the Mg-based casting material 100 is a thin plate material continuously cast by a continuous casting machine (here, a twin roll casting machine including a pair of movable molds (rolls 200)), for example, as shown in FIG.
  • the paper is cooled while proceeding linearly from the left side to the right side of the paper, and is wound up by a winder (not shown).
  • the surface state of the Mg-based cast material 100 is inspected by the surface inspection apparatus 1 shown in FIG.
  • the surface inspection apparatus 1 will be mainly described.
  • the surface inspection apparatus 1 is an apparatus for inspecting the surface state of the Mg-based cast material 100 that has passed through the roll 200 of the continuous casting machine, and here, exists between the continuous casting machine and the winder.
  • the following constituent members are arranged so that the surface of the Mg-based cast material 100 can be inspected.
  • the surface inspection apparatus 1 includes a light source 10 that emits light to the surface of the Mg-based casting material 100, and an optical imaging device 11 that captures an image of the surface of the Mg-based casting material 100 using light from the light source 10. And an image processing inspection unit 12 that performs image processing on the image obtained by the optical imaging device 11 and inspects the surface state of the Mg-based cast material 100 based on the processed image.
  • the light source 10 is preferably a light source that has high rectilinearity.
  • LEDs light emitting diodes
  • LEDs have a longer life than light sources using filaments and are suitable for continuous use.
  • the number of light sources 10 is the specification of the light source, the number of optical imaging devices, and the width of the Mg-based casting material 100 (the direction orthogonal to the traveling direction of the Mg-based casting material 100 (the direction from the front to the back in FIG. 1)). The length may be selected appropriately according to the length of A commercially available light source can be used.
  • a camera including an imaging device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) can be preferably used. Since these imaging devices have a fast reaction speed, a camera equipped with these imaging devices is capable of continuously imaging the surface state of a continuous casting material that travels (for example, 1 m / min to 10 m / min). Is suitable. In addition, by using a camera having a large number of such image sensors, a wide area can be imaged with high accuracy at a time. Here, a 10 million pixel CCD camera is used.
  • the number of pixels (the number of image pickup devices) and the number of optical image pickup devices 11 may be appropriately selected mainly according to the width of the Mg-based casting material 100. By arranging a plurality of optical imaging devices 11, even when the width of the Mg-based cast material 100 is large, it is possible to image a region over the entire width at a time. A commercially available optical imager can be used.
  • both the light source 10 and the optical imaging device 11 are arranged on the upstream side (continuous casting machine side (left side in FIG. 1)) with respect to the traveling direction of the Mg-based casting material 100 (left and right direction in FIG. 1). .
  • the optical axis 10a of the light source 10 and the optical axis 11a of the optical imaging device 11 are non-orthogonally intersecting with the traveling direction of the Mg-based casting material 100 on the surface of the Mg-based casting material 100. Is arranged.
  • the inclination angle ⁇ of the optical axis 10a of the light source 10 with respect to the traveling direction is about 65 °
  • the inclination angle ⁇ of the optical axis 11a of the optical imaging device 11 with respect to the traveling direction is about 30 °
  • the inclination angle ⁇ of the optical imaging device 11 is smaller than the inclination angle ⁇ of the light source 10.
  • the inclination angle ⁇ (incident angle) of the light source 10 is less than 90 °
  • the inclination angle ⁇ of the optical imaging device 11 is 60 ° or less
  • the light source 10 and the optical imaging device 11 are made to the Mg-based casting material 100.
  • the optical imaging device 11 can emit light emitted from the light source 10 (incident light emitted from the light source 10 and incident on the Mg-based casting material 100) itself, and Both the regular reflection lights of the incident light are not substantially received. Therefore, the optical imager 11 captures a dark image because the light based on the light source 10 is not substantially received unless there is a surface defect such as a minute crack on the surface of the Mg-based cast material 100.
  • the optical imaging device 11 can capture an image by the irregularly reflected light, that is, an image having a large contrast between light and dark, where the surface defect portion is bright and other portions are dark.
  • both the light source 10 and the optical imaging device 11 may be arranged on the downstream side (winder side (right side in FIG. 1)) with respect to the traveling direction of the Mg-based cast material 100. Further, the light source 10 and the optical imaging device 11 may be arranged so that the inclination angle ⁇ is smaller than the inclination angle ⁇ .
  • the image processing inspection unit 12 includes an input unit 121 that acquires an image from the optical imaging device 11, a binarization unit 122 that binarizes the acquired image, and a surface defect based on the obtained binarized image.
  • Light / dark determination means 123 for determining presence / absence is provided.
  • the image obtained by the optical imaging device 11 is an image having a large contrast between light and dark as described above. Therefore, it is easy to distinguish the bright area and the dark area by the binarizing means 122, and the cracked area (bright area) can be extracted with high accuracy.
  • the light / dark determination means 123 may be configured to determine, for example, the presence or absence of a bright region in a binarized image. As described above, when a surface defect exists in the Mg-based cast material 100, the surface defect is indicated by a bright region in the acquired image. Therefore, when it is determined that there is a bright region, it can be determined that there is a surface defect.
  • the size of the bright region is measured, and when the length along the traveling direction of the Mg-based casting material 100 in the bright region is a predetermined length or more,
  • the bright region is a surface defect
  • the light / dark determination means 123 can be configured to determine that there is a surface defect. In this case, it is possible to distinguish and distinguish small wrinkles that disappear in the rolling process after casting from cracks that adversely affect the final product.
  • the measurement of the size of the bright region can be performed automatically and quickly by providing a calculation means in the image processing inspection unit 12 so as to calculate based on the size of the image sensor, for example.
  • the light / dark determination means 123 can be configured to measure the size of each bright region.
  • Such an image processing inspection unit 12 uses commercially available image processing means including the input means 121, binarization means 122, brightness / darkness determination means 123, and arithmetic means, or a part of the commercially available image processing means.
  • the configuration can be appropriately changed and used.
  • the image processing inspection unit 12 includes a recording means 124 for recording a defect portion in the Mg-based cast material 100 when a surface defect is detected.
  • the Mg-based cast material 100 manufactured by the continuous casting machine and wound by the winder has the rotational speed (or rotational speed) of the roll 200 of the continuous casting machine and the rotational speed (or rotational speed) of the winder. ) Controls the traveling speed. Therefore, if the traveling speed of the Mg-based casting material 10, the rotational speed of the winder, and the time at the time of the current detection from the start of casting are known, the Mg-based casting material 100 currently being imaged by the optical imaging device 11 The position in the traveling direction, that is, the position during imaging can be grasped. Therefore, here, the position measuring unit 128 that automatically measures the position during imaging is provided, and the recording unit 124 is configured to store the determination information and the position information from the position measuring unit 128. Yes.
  • the position measuring means 128 includes, for example, a configuration including an encoder that measures the number of revolutions as described above, a timer that measures time, and the like.
  • the defect portion of the Mg-based cast material 100 can be easily grasped even after being wound on the winder. Therefore, with this configuration, a continuous cast material can be manufactured with high productivity without cutting the cast material.
  • the monitor 125 may be provided so that the operator can check the binarized image and the determination result, and operator operation means (not shown) such as a keyboard may be provided so that various setting conditions can be input.
  • the image processing inspection unit 12 includes the light / dark determination unit 123 and the like to automatically determine the presence / absence of a surface defect as described above, because the determination can be easily performed in a short time.
  • the light shielding member 13 is disposed at a position where the regular reflection light can be received so that the regular reflection light from the light source 10 can be absorbed.
  • the contrast between the cracked portion and other portions can be further enhanced, and even a fine crack can be detected with high accuracy.
  • the light blocking member 13 can be made of a material that can absorb specularly reflected light and can block disturbance light, typically a black body.
  • FIG. 1 shows a state where the plate-shaped light shielding member 13 is arranged so that a part of the surface of the Mg-based cast material 100 is covered.
  • the light shielding member 13 may be formed in a cylindrical shape or a bowl shape so that the entire downstream surface of the Mg-based cast material 100 is covered so as not to obstruct the visual field of the light source 10 and the optical imaging device 11.
  • the surface inspection apparatus 1 inspects the surface state until the Mg-based cast material 100 cast by the continuous casting machine is wound up by the winder. With this configuration, the Mg-based cast material 100 is not cut for inspection, and inspection can be performed simultaneously with casting. Therefore, by performing the surface inspection using the surface inspection apparatus 1, the Mg-based cast material 100 can be manufactured with high productivity.
  • the Mg-based cast material 100 is made of a composition equivalent to the AZ91 alloy, so that it is considered that fine cracks are likely to occur.
  • the surface inspection apparatus 1 shown in FIG. As described above, it is possible to accurately capture fine cracks.
  • the Mg-based cast material can be made of pure magnesium or a magnesium alloy having another composition.
  • the method for producing a magnesium substrate material of the present invention can be suitably used for producing a plate made of magnesium or a magnesium alloy used for a housing of various electronic devices such as portable electronic devices.
  • the surface inspection method and the surface inspection apparatus for the continuous cast material of the present invention can be suitably used for the inspection of the surface state of the cast material which is an intermediate product in the production of the magnesium substrate material of the present invention.

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Abstract

Disclosed are a method of, and a device for, inspecting the obverse surface of a continuous cast material that are suited to inspecting the state of the obverse surface of a continuous cast material comprising either magnesium or a magnesium alloy, as well as a method of manufacturing a magnesium substrate material. Light is projected by a light source (10) upon the obverse surface of a magnesium cast substrate material (100) comprising either magnesium or a magnesium alloy, which is continuously cast by a continuous-casting machine, diffusely reflected light arising from the projected light contacting obverse surface imperfections of the magnesium cast substrate material (100) are treated as primary detected light, and an image formed by the detected light is captured by an optical image capture unit (11). The obverse surface state of the magnesium cast substrate material (100) is inspected by an image processing inspection unit (12) on the basis of the image that is obtained by the optical image capture unit (11). Using the image derived from the diffusely reflected light from the light projected from the light source (10), rather than the regular reflected light thereof, allows obtaining high-contrast images. It is possible to suitably detect the microscopic cracks that constitute obverse surface imperfections by using the images thus generated.

Description

連続鋳造材の表面検査方法Surface inspection method for continuous cast material
　本発明は、マグネシウム又はマグネシウム合金からなる連続鋳造材の表面状態の検査に適した連続鋳造材の検査方法、この検査方法による検査工程を具えるマグネシウム基板材の製造方法、及びこの検査方法に適した連続鋳造材の表面検査装置に関するものである。 INDUSTRIAL APPLICABILITY The present invention is a method for inspecting a continuous cast material suitable for inspecting the surface state of a continuous cast material made of magnesium or a magnesium alloy, a method for manufacturing a magnesium substrate material comprising an inspection step by this inspection method, and a method suitable for this inspection method. The present invention relates to a surface inspection apparatus for continuous cast materials.
　各種の部材の構成材料として、軽量で、比強度、比剛性に優れるマグネシウムやマグネシウムに種々の添加元素を含有したマグネシウム合金が検討されている。 As a constituent material of various members, magnesium that is lightweight and excellent in specific strength and specific rigidity and magnesium alloy containing various additive elements in magnesium has been studied.
　マグネシウムやマグシウム合金は、六方晶の結晶構造(hcp構造)を有するため常温での塑性加工性に乏しいことから、上記マグネシウム又はマグネシウム合金からなる部材(以下、マグネシウム基部材と呼ぶ)は、ダイカスト法やチクソモールド法による鋳造材が主流である。最近、ASTM規格におけるAZ31合金からなる板材にプレス加工を施して、携帯電話やノート型パーソナルコンピュータといった携帯用電子機器の筐体を形成することが検討されている。特許文献1には、ASTM規格におけるAZ91合金相当の合金からなる連続鋳造板に圧延を施し、得られた圧延板にプレス加工を施したプレス材が開示されている。 Magnesium or a magnesium alloy has a hexagonal crystal structure (hcp structure) and therefore has poor plastic workability at room temperature, so the member made of magnesium or a magnesium alloy (hereinafter referred to as a magnesium-based member) is a die casting method. Cast materials by the thixomold method are the mainstream. Recently, it has been studied to form a casing of a portable electronic device such as a mobile phone or a notebook personal computer by pressing a plate made of an AZ31 alloy according to the ASTM standard. Patent Document 1 discloses a press material obtained by rolling a continuous cast plate made of an alloy equivalent to the AZ91 alloy in the ASTM standard and pressing the obtained rolled plate.
特開2009-120877号公報JP 2009-120877
　本発明者らは、連続鋳造板に圧延を施した圧延板にプレス加工といった塑性加工を施してマグネシウム基部材を作製したところ、当該部材表面に微小な割れといった欠陥が発生する場合がある、との知見を得た。上記欠陥は、外観の不良や品質の劣化を招くことから、このような欠陥の発生により歩留まりが低下し、結果として、マグネシウム基部材の生産性が低下する。 The inventors of the present invention have produced a magnesium base member by performing plastic working such as press working on a rolled plate obtained by rolling a continuous cast plate, and a defect such as a minute crack may occur on the surface of the member. I got the knowledge. Since the defects cause poor appearance and quality deterioration, the generation of such defects reduces the yield, and as a result, the productivity of the magnesium-based member decreases.
　そこで、本発明者らは、上記欠陥を無くすために上記マグネシウム基部材に発生した欠陥の原因を調べたところ、連続鋳造後の鋳造板の表面に発生した微小な欠陥が一因であると見出した。具体的には、本発明者らは、連続鋳造により得られた連続鋳造板を所定の長さに切断して長さが短い小板とし、顕微鏡や浸透式探傷法を用いて各小板の表面状態を調べた。すると、上記小板には、深さ(小板の厚さ方向の大きさ)が30μm～500μm程度の欠陥があり、このような欠陥(以下、割れと呼ぶ)は、圧延後にも残存すると考えられる。特に、上記割れは、鋳造板の進行方向に沿って不連続な線状に形成され易い上に、幅が数10μm以下といった非常に細幅のものがある。上述の顕微鏡や浸透式探傷法により上記小板の全面を隈なく調べる場合、このような微小で、かつ、不連続に生じる割れであっても精度よく検出できるものの、非常に時間が掛かる上に、連続的に生産される鋳造材を連続的に検査することはできない。そのため、上述のように小板とし、顕微鏡などを用いる手法では、連続鋳造材の生産性の低下を招き、工業生産の観点からすると実用的でない。従って、上記微小な割れを高感度に、かつ効率よく検出することができる検査方法の開発が望まれる。 Therefore, the present inventors have investigated the cause of the defect generated in the magnesium base member in order to eliminate the defect, and found that the minute defect generated on the surface of the cast plate after continuous casting is one cause. It was. Specifically, the present inventors cut a continuous cast plate obtained by continuous casting into a small plate by cutting to a predetermined length, and using a microscope or a penetrating flaw detection method, The surface condition was examined. Then, the above-mentioned small plate has defects with a depth (size in the thickness direction of the small plate) of about 30 μm to 500 μm, and such defects (hereinafter referred to as cracks) are considered to remain after rolling. It is done. In particular, the cracks are easily formed in a discontinuous line along the traveling direction of the cast plate and have a very narrow width of several tens of μm or less. When thoroughly examining the entire surface of the above-mentioned small plate by the above-mentioned microscope or penetration type flaw detection method, even though it is such a small and discontinuous crack, it can be accurately detected, but it takes a very long time. Continuously produced castings cannot be inspected continuously. Therefore, the method using a small plate as described above and using a microscope or the like causes a decrease in productivity of the continuous cast material, and is not practical from the viewpoint of industrial production. Therefore, it is desired to develop an inspection method that can detect the minute cracks with high sensitivity and efficiency.
　そこで、本発明の目的の一つは、マグネシウム又はマグネシウム合金からなる連続鋳造材の表面状態を高精度に、かつ効率よく検査することができる連続鋳造材の表面検査方法を提供することにある。 Therefore, one of the objects of the present invention is to provide a surface inspection method for a continuous cast material capable of efficiently and efficiently inspecting the surface state of a continuous cast material made of magnesium or a magnesium alloy.
　また、本発明の目的の一つは、上記表面検査方法の実施に適した連続鋳造材の表面検査装置を提供することにある。 Also, one of the objects of the present invention is to provide a surface inspection apparatus for a continuous cast material suitable for carrying out the surface inspection method.
　更に、本発明の目的の一つは、高品位なマグネシウム基板材を生産性よく製造することができるマグネシウム基板材の製造方法を提供することにある。 Furthermore, one of the objects of the present invention is to provide a method for producing a magnesium substrate material, which can produce a high-quality magnesium substrate material with high productivity.
　上述のように連続鋳造板を切断する工程を省略し、連続的に製造される鋳造材の製造中に当該鋳造材の表面状態の検査を連続して行うと、効率よく検査することができる。 If the step of cutting the continuous cast plate as described above is omitted and the surface condition of the cast material is continuously inspected during the production of the continuously produced cast material, the inspection can be performed efficiently.
　そこで、連続鋳造材の表面検査方法の一形態として、マグネシウム又はマグネシウム合金からなる鋳造材を連続的に鋳造する連続鋳造機とこの鋳造材を巻き取る巻き取り機との間を進行する上記鋳造材の表面状態を表面検査装置により検査する方法を提案する。 Then, as one form of the surface inspection method of a continuous cast material, the said cast material which advances between the continuous casting machine which continuously casts the cast material which consists of magnesium or a magnesium alloy, and the winding machine which winds up this cast material We propose a method for inspecting the surface condition of a surface using a surface inspection device.
　更に、効率よく、かつ高精度に検査するために、本発明者らは、カメラといった光学撮像機を利用した検査方法を検討した。具体的には、光源及びカメラを配置し、上記光源からの出射光を上記鋳造材に当てて生じた正反射光を主たる検出光として、この検出光による像が撮像できるようにカメラを配置した。より具体的には、上記鋳造材の表面に対して光源の光軸が直交するように、かつカメラの光軸も直交するように、光源及びカメラを配置した。或いは、上記鋳造材の表面における光の入射点を中心として光源とカメラとが対称位置となるように、光源及びカメラを配置した。これらの配置状態で、連続鋳造機から製造されてくる鋳造材をカメラにより連続的に撮像した。しかし、上記配置形態では、上述した微小な割れを実質的に検出することができなかった。 Furthermore, in order to inspect efficiently and with high accuracy, the present inventors examined an inspection method using an optical imaging device such as a camera. Specifically, a light source and a camera are arranged, and the camera is arranged so that an image of the detection light can be captured using specular reflection light generated by applying light emitted from the light source to the cast material as the main detection light. . More specifically, the light source and the camera were arranged so that the optical axis of the light source was orthogonal to the surface of the cast material and the optical axis of the camera was also orthogonal. Alternatively, the light source and the camera are arranged so that the light source and the camera are symmetrical with respect to the light incident point on the surface of the cast material. With these arrangements, the cast material produced from the continuous casting machine was continuously imaged with a camera. However, in the arrangement form, the above-described minute cracks could not be substantially detected.
　図3(I)は、連続鋳造材を短く切断して小板とし、この小板の光学顕微鏡写真であり、図3(II)は、小板の表面に存在した割れを説明するための模式図、図4は、上記正反射光による像の金属写真である。なお、図3,4のいずれも、紙面の下方から上方に向かう方向が鋳造材の進行方向である。図3に示すように、顕微鏡を利用することで、上述した細幅の割れであっても、精度よく検出することができる。これに対して、正反射光を主たる検出光とした像を撮像すると、上述したような微小な割れでは表面の凹凸が小さいことで、図4に示すような鏡面のような像しか得られない。このように正反射光を主たる検出光とする像では、上記微小な割れを適切に検出することができない。そこで、光源及びカメラの配置を種々変更したところ、乱反射光(拡散反射光)を主たる検出光とする像では、上記微小な割れを高精度に検出することができる、との知見を得た。 Fig. 3 (I) is a short cut of a continuous cast material to form a small plate, and is an optical micrograph of this small plate, Fig. 3 (II) is a schematic diagram for explaining cracks present on the surface of the small plate FIG. 4 and FIG. 4 are metal photographs of the image by the regular reflection light. In both FIGS. 3 and 4, the direction from the lower side to the upper side of the drawing is the traveling direction of the cast material. As shown in FIG. 3, by using a microscope, even the narrow crack described above can be detected with high accuracy. On the other hand, when an image with specularly reflected light as the main detection light is picked up, only a mirror-like image as shown in FIG. . Thus, in the image which uses regular reflection light as the main detection light, the above-mentioned minute crack cannot be detected appropriately. Therefore, when various arrangements of the light source and the camera were changed, the inventors obtained knowledge that the minute cracks can be detected with high accuracy in an image having diffusely reflected light (diffuse reflected light) as the main detection light.
　上記知見に基づく本発明の連続鋳造材の表面検査方法は、連続鋳造機により連続的に鋳造されるマグネシウム又はマグネシウム合金からなる鋳造材の表面に光を入射し、この入射光が上記鋳造材の表面欠陥に当たることで生じた乱反射光を主たる検出光とし、この検出光による像を光学撮像機により捉え、上記光学撮像機により得られた像に基づいて上記鋳造材の表面状態を検査する。 The surface inspection method for a continuous cast material of the present invention based on the above knowledge makes light incident on the surface of a cast material made of magnesium or a magnesium alloy continuously cast by a continuous casting machine, and this incident light is incident on the cast material. The irregularly reflected light generated by hitting the surface defect is used as the main detection light, an image obtained by the detection light is captured by an optical image pickup device, and the surface state of the cast material is inspected based on the image obtained by the optical image pickup device.
　上述のように乱反射光を利用すると、微小な割れの部分とそれ以外の部分との明暗のコントラストが大きい像が得られる。具体的には、割れの部分が非常に明るく、それ以外の部分が非常に暗い像が得られる。従って、この像を利用すれば、明るい部分を割れとして簡単に、かつ精度よく検出することができる。また、上記構成によれば、カメラに代表される光学撮像機を利用することで、連続的に製造される鋳造材を切断することなく、鋳造材の表面状態を連続的に検査することができる。更に、光学撮像機を利用することで、比較的短時間で広範囲な領域の検査を行える。このように鋳造ラインの中で本発明表面検査方法により表面欠陥を検出する、即ち、鋳造材の製造と同時に検査を行うと共に、切断による廃棄分を低減することができるため歩留まりが高いことから、本発明表面検査方法は、連続鋳造材を生産性よく製造することに寄与することができると期待される。また、上述のような微小な割れといった表面欠陥を簡単に、かつ精度よく検出することが可能であることから、欠陥部分が検出されたら、当該欠陥部分を適切に除去することができる。従って、本発明表面検査方法によって表面欠陥の検出を行って欠陥部分の除去を行うことで、鋳造材、引いてはこの鋳造材を素材とした最終製品の信頼性を高められる。 As described above, when irregularly reflected light is used, an image having a large contrast between light and dark between a minute cracked portion and other portions can be obtained. Specifically, an image is obtained in which the cracked portion is very bright and the other portions are very dark. Therefore, if this image is used, a bright part can be detected easily and accurately as a crack. Moreover, according to the said structure, the surface state of a cast material can be continuously test | inspected, without cut | disconnecting the cast material manufactured continuously by utilizing the optical imaging device represented by the camera. . Furthermore, by using an optical imaging device, it is possible to inspect a wide area in a relatively short time. In this way, surface defects are detected by the surface inspection method of the present invention in the casting line, i.e., the inspection is performed simultaneously with the production of the cast material, and the waste due to cutting can be reduced, so the yield is high. The surface inspection method of the present invention is expected to contribute to producing a continuous cast material with high productivity. Further, since it is possible to easily and accurately detect surface defects such as the above-described minute cracks, when a defective portion is detected, the defective portion can be appropriately removed. Therefore, by detecting the surface defect by the surface inspection method of the present invention and removing the defective portion, the reliability of the cast material and, in turn, the final product using the cast material as a raw material can be improved.
　本発明表面検査方法の一形態として、上記光学撮像機による撮像を、上記入射光、及びこの入射光の正反射光の双方を実質的に受光せず、かつ上記乱反射光を受光する位置に上記光学撮像機を配置して行うことが挙げられる。 As one form of the surface inspection method of the present invention, imaging by the optical imaging device is performed at a position where the incident light and the regular reflection light of the incident light are substantially not received and the irregular reflection light is received. For example, an optical imaging device may be disposed.
　上記形態によれば、入射光やその正反射光による影響を受け難く、乱反射光による像を光学撮像機でより確実に捉えることができる。従って、上記微細な割れをより高精度に検出することができる。 According to the above embodiment, it is difficult to be influenced by incident light and its regular reflection light, and an image by diffuse reflection light can be captured more reliably by an optical imaging device. Therefore, the fine crack can be detected with higher accuracy.
　本発明表面検査方法の一形態として、上記入射光の入射角を90°未満、及び上記鋳造材の表面に対する上記光学撮像機の光軸の傾斜角度を60°以下にすることが挙げられる。 As one form of the surface inspection method of the present invention, the incident angle of the incident light is less than 90 °, and the inclination angle of the optical axis of the optical imaging device with respect to the surface of the cast material is 60 ° or less.
　本発明者らが調べたところ、上記入射光の入射角(上記鋳造材の表面に対する入射光の傾斜角度)を90°未満とすると、上記入射光が上記鋳造材に当たって生じた正反射光を光学撮像機が受け難く、当該正反射光を受光することによる検出感度の低下を低減することができる、との知見を得た。また、上記入射光に基づく乱反射光による像を捉えられるように、光学撮像機もその光軸の傾斜角度が60°以下となるように配置すると、正反射光や外乱光による影響を受け難く、上述した乱反射光による像が明暗のコントラストが大きい像となる、との知見を得た。但し、上記入射光や上記光軸の傾斜角度が5°未満では、鮮明な画像が捉え難い恐れがある。従って、上記入射角及び上記光軸の傾斜角度はいずれも、5°以上が好ましい。特に、上記入射角は、5°以上70°以下が好ましく、上記光軸の傾斜角度は、5°以上40°以下、更に35°以下が好ましい。上記入射角及び傾斜角度が上記範囲を満たす場合、光学撮像機及び光を出射する光源の上下の位置(鋳造材に対する垂直方向の位置)関係は適宜選択することができる。 As a result of investigation by the present inventors, when the incident angle of the incident light (the inclination angle of the incident light with respect to the surface of the casting material) is less than 90 °, the specularly reflected light generated when the incident light hits the casting material is optical. It has been found that the imaging device is difficult to receive and the reduction in detection sensitivity caused by receiving the regular reflection light can be reduced. In addition, if an optical imaging device is also arranged so that the tilt angle of its optical axis is 60 ° or less so that an image of irregularly reflected light based on the incident light can be captured, it is difficult to be affected by specularly reflected light and disturbance light, The inventor obtained that the image by the irregular reflection light described above becomes an image having a large contrast between light and dark. However, if the incident light or the tilt angle of the optical axis is less than 5 °, a clear image may be difficult to capture. Therefore, both the incident angle and the inclination angle of the optical axis are preferably 5 ° or more. In particular, the incident angle is preferably 5 ° to 70 °, and the tilt angle of the optical axis is preferably 5 ° to 40 °, and more preferably 35 ° or less. When the incident angle and the inclination angle satisfy the above ranges, the relationship between the vertical position (position in the vertical direction with respect to the cast material) of the optical imaging device and the light source that emits light can be selected as appropriate.
　本発明表面検査方法の一形態として、上記入射光の正反射光を吸収し、かつ外乱光を遮蔽する遮光部材により、上記鋳造材の外周の少なくとも一部を覆うことが挙げられる。 As one form of the surface inspection method of the present invention, at least a part of the outer periphery of the cast material is covered with a light shielding member that absorbs specularly reflected light of the incident light and shields disturbance light.
　ここで、連続鋳造機が配置される工場内などでは、照明の他、種々の光源となるもの(以下、外部光源と呼ぶ)が配置されていることが考えられる。これらの外部光源の光により、乱反射光による像は、明暗のコントラストが十分に大きい像とならない恐れがある。これに対し、上記構成によれば、このような外部光源による光(外乱光)を遮光部材により遮蔽することで、乱反射光による像をより適切に得ることができる。かつ、上記構成によれば、正反射光をも遮光部材により吸収することで、乱反射光による像をより適切に得ることができる。上記遮光部材は、乱反射光による像を撮像する光学撮像機の視野を遮らず、かつ正反射光や外乱光を吸収・遮蔽できるように配置すればよく、鋳造材の全周を覆うように配置してもよいし、鋳造材の一部の外周を覆うように配置してもよい。 Here, in a factory where a continuous casting machine is arranged, it is conceivable that various light sources (hereinafter referred to as external light sources) are arranged in addition to illumination. Due to the light from these external light sources, the image of irregularly reflected light may not be an image with sufficiently high contrast between light and dark. On the other hand, according to the above configuration, an image of diffusely reflected light can be more appropriately obtained by shielding light (disturbance light) from such an external light source with the light shielding member. And according to the said structure, the image by irregular reflection light can be obtained more appropriately by absorbing specular reflection light also with a light-shielding member. The light shielding member may be disposed so as not to block the field of view of the optical imaging device that captures an image of diffusely reflected light, and to absorb and shield regular reflected light and disturbance light, and is disposed so as to cover the entire circumference of the cast material. Or you may arrange | position so that the outer periphery of a part of casting material may be covered.
　本発明表面検査方法の一形態として、上記連続鋳造機が双ロール鋳造機であることが挙げられる。 As one form of the surface inspection method of the present invention, the continuous casting machine is a twin roll casting machine.
　連続鋳造法には、双ロール法、ベルトアンドホイール法やツインベルト法といった種々の方法がある。中でも、双ロール法は、溶湯に接触する面がロールの回転により連続的に現れることから、溶湯を効率よく冷却して急冷凝固させることで、圧延といった塑性加工性に優れる連続鋳造材を得ることができる。また、双ロール法は、鋳造材に生じる割れが微細となる傾向にあるため、本発明表面検査方法を利用することで、微細な割れといった表面欠陥の検出を効率よく行える。 There are various continuous casting methods such as a twin roll method, a belt and wheel method, and a twin belt method. Above all, in the twin roll method, since the surface in contact with the molten metal appears continuously by the rotation of the roll, a continuous cast material excellent in plastic workability such as rolling can be obtained by efficiently cooling the molten metal and rapidly solidifying it. Can do. In addition, since the twin roll method tends to cause fine cracks in the cast material, the surface inspection method of the present invention can be used to efficiently detect surface defects such as fine cracks.
　本発明表面検査方法の一形態として、上記光学撮像機による撮像は、上記連続鋳造機により鋳造された鋳造材が巻き取り機により巻き取られるまでの間に行うことが挙げられる。 As one form of the surface inspection method of the present invention, imaging by the optical imaging machine is performed until the cast material cast by the continuous casting machine is wound up by the winder.
　本発明表面検査方法は、連続鋳造材を巻き取り機で一旦巻き取った後、巻き戻した鋳造材に対しても適用することができる。しかし、上述のように、連続鋳造機と巻き取り機との間に存在する連続鋳造材に対して表面状態の検査を行うことで、鋳造工程と検査工程とを重複させることができるため、連続鋳造材を生産性よく製造することに寄与することができる。 The surface inspection method of the present invention can also be applied to a cast material that has been wound once with a winder and then rewound. However, as described above, since the inspection of the surface state can be performed on the continuous cast material existing between the continuous casting machine and the winder, the casting process and the inspection process can be overlapped. It can contribute to manufacturing a cast material with high productivity.
　本発明表面検査方法の一形態として、連続鋳造材がマグネシウム合金から構成される場合、当該マグネシウム合金としてAlを7.5質量％超12質量％以下含有するものが挙げられる。 As an embodiment of the surface inspection method of the present invention, when the continuous cast material is composed of a magnesium alloy, the magnesium alloy may contain Al in excess of 7.5% by mass and 12% by mass or less.
　本発明表面検査方法の検査対象となる連続鋳造材は、Mg、残部不可避不純物からなるいわゆる純マグネシウムの他、Mg及び添加元素、残部不可避不純物からなるマグネシウム合金のいずれでもよい。中でもAlを含有するマグネシウム合金、例えば、ASTM規格におけるAZ系合金(Mg-Al-Zn系合金、Zn:0.2質量％～1.5質量％)、AM系合金(Mg-Al-Mn系合金、Mn:0.15質量％～0.5質量％)、AS系合金(Mg-Al-Si系合金、Si:0.6質量％～1.4質量％)、Mg-Al-RE(希土類元素)系合金、AX系合金（Mg-Al-Ca系合金、Ca:0.2質量％～6.0質量％）、AJ系合金(Mg-Al-Sr系合金、Sr:0.2質量％～7.0質量％)は、耐食性に優れる上に強度といった機械的特性にも優れる。 The continuous cast material to be inspected by the surface inspection method of the present invention may be Mg, an additive element, and a magnesium alloy composed of the remaining inevitable impurities, in addition to so-called pure magnesium composed of Mg and the remaining inevitable impurities. Among them, magnesium alloys containing Al, for example, AZ-based alloys (Mg-Al-Zn-based alloys, Zn: 0.2% to 1.5% by weight) and AM-based alloys (Mg-Al-Mn-based alloys, Mn: 0.15 mass% to 0.5 mass%), AS alloys (Mg-Al-Si alloys, Si: 0.6 mass% to 1.4 mass%), Mg-Al-RE (rare earth elements) alloys, AX alloys (Mg- Al-Ca alloys (Ca: 0.2 mass% to 6.0 mass%) and AJ alloys (Mg-Al-Sr alloys, Sr: 0.2 mass% to 7.0 mass%) have excellent corrosion resistance and mechanical strength. Excellent characteristics.
　特に、Alを7.5質量％超12質量％以下含有するマグネシウム合金、例えば、Mg-Al-Zn系合金では、AZ80合金、AZ81合金、AZ91合金、Mg-Al-Mn系合金では、AM100合金などは、耐食性に更に優れて好ましい。Alの含有量が上記範囲である場合、塑性加工性に劣り、微小な割れなどが生じ易くなる。従って、Alの含有量が上記範囲である高Alマグネシウム合金からなる連続鋳造材に対して、表面状態を検査するにあたり、本発明表面検査方法を適用することは、非常に好ましいと考えられる。 In particular, magnesium alloys containing more than 7.5% by mass and less than 12% by mass of Al, such as Mg-Al-Zn alloy, AZ80 alloy, AZ81 alloy, AZ91 alloy, Mg-Al-Mn alloy, AM100 alloy, etc. Further, the corrosion resistance is further excellent and preferable. When the Al content is in the above range, the plastic workability is inferior and minute cracks are likely to occur. Therefore, it is considered to be very preferable to apply the surface inspection method of the present invention to inspect the surface state for a continuous cast material made of a high Al magnesium alloy having an Al content in the above range.
　上記本発明表面検査方法は、特に、連続鋳造材の製造過程に組み入れることが好ましい。そこで、マグネシウム又はマグネシウム合金からなるマグネシウム基板材を製造する本発明のマグネシウム基板材の製造方法として、マグネシウム又はマグネシウム合金を連続的に鋳造して連続鋳造材を製造する鋳造工程を具え、この鋳造工程に、上記本発明連続鋳造材の表面検査方法による検査工程を含むことを提案する。 The surface inspection method of the present invention is particularly preferably incorporated in the production process of continuous cast material. Therefore, as a method for producing a magnesium substrate material of the present invention for producing a magnesium substrate material made of magnesium or a magnesium alloy, the present invention includes a casting process for producing a continuous cast material by continuously casting magnesium or a magnesium alloy. In addition, it is proposed to include an inspection step by the surface inspection method for the continuous cast material of the present invention.
　上記構成によれば、鋳造工程において連続的に製造される鋳造材に表面状態の検査を行うことで、歩留まりが高く、連続鋳造材を生産性よく製造することができる上に、この連続鋳造材を素材に用いた最終製品の信頼性を高められる。 According to the above configuration, the continuous casting material can be manufactured with high yield and high productivity by performing surface condition inspection on the casting material continuously manufactured in the casting process. The reliability of the final product that uses the material can be improved.
　得られた連続鋳造材は、例えば、プレス材といったマグネシウム基部材の素材に好適に利用される。代表的には、連続鋳造材に圧延を施した後、歪取り及び再結晶化のための熱処理、又は矯正(代表的には温間矯正)を施し、更にプレス加工といった塑性加工を施すことで、上記マグネシウム基部材が得られる。上記熱処理又は矯正後、或いは塑性加工後に、更に化成処理などの防食処理を施したり、塗装などを施したりしてもよい。 The obtained continuous cast material is suitably used for a material of a magnesium base member such as a press material, for example. Typically, after rolling the continuous cast material, heat treatment for strain relief and recrystallization, or correction (typically warm correction), and further plastic processing such as press processing. The magnesium-based member is obtained. After the heat treatment or correction, or after plastic working, it may be further subjected to anticorrosion treatment such as chemical conversion treatment or coating.
　上記本発明表面検査方法を実行するには、例えば、以下の本発明の表面検査装置を利用することが挙げられる。本発明の表面検査装置は、連続鋳造機により連続的に鋳造されるマグネシウム又はマグネシウム合金からなる鋳造材の表面状態を検査するための装置であり、以下の光源と、光学撮像機と、画像処理検査部とを具える。
　光源:上記鋳造材の表面に光を出射する。
　光学撮像機:上記出射光が上記鋳造材の表面欠陥に当たることで生じた乱反射光を主たる検出光とし、この検出光による像を撮像する。
　画像処理検査部:上記光学撮像機により得られた像に基づいて上記鋳造材の表面状態を検査する。 In order to execute the surface inspection method of the present invention, for example, the following surface inspection apparatus of the present invention is used. The surface inspection apparatus of the present invention is an apparatus for inspecting the surface state of a cast material made of magnesium or a magnesium alloy continuously cast by a continuous casting machine, and includes the following light source, optical imaging device, and image processing. It has an inspection department.
Light source: emits light to the surface of the cast material.
Optical imaging device: The irregularly reflected light generated when the emitted light hits the surface defect of the cast material is used as the main detection light, and an image by this detection light is taken.
Image processing inspection unit: Inspects the surface state of the cast material based on the image obtained by the optical imaging device.
　上記光学撮像機により得られた乱反射光による像は、例えば、作業者が目視により確認する構成とすることができる。これに対して、上述のように画像処理検査部により自動的に表面状態の検査(代表的には微小な割れの有無の判定)を行う構成とすることで、簡単に、比較的短時間で、かつ精度よく上記鋳造材の表面状態を検査することができる。例えば、画像処理検査部は、上記乱反射光による像を二値化処理し、この二値化像に基づいて表面状態の検査を行う形態が挙げられる。 The image obtained by the irregularly reflected light obtained by the optical imaging device can be configured to be visually confirmed by an operator, for example. On the other hand, as described above, the image processing inspection unit automatically performs surface state inspection (typically, the determination of the presence or absence of minute cracks), so that it can be performed in a relatively short time. In addition, the surface state of the cast material can be inspected with high accuracy. For example, the image processing inspection unit can binarize the image of the irregularly reflected light and inspect the surface state based on the binarized image.
　本発明連続鋳造材の表面検査方法、及び本発明連続鋳造材の表面検査装置は、マグネシウム又はマグネシウム合金からなる鋳造材の表面状態を効率よく検査することができる。本発明マグネシウム基板材の製造方法は、欠陥部分を適切に検出できると共に、連続鋳造材を生産性よく製造できる。 The surface inspection method for a continuous cast material of the present invention and the surface inspection apparatus for the continuous cast material of the present invention can efficiently inspect the surface state of a cast material made of magnesium or a magnesium alloy. The manufacturing method of the magnesium substrate material of the present invention can appropriately detect a defective portion and can manufacture a continuous cast material with high productivity.
図1は、本発明連続鋳造材の表面検査方法を説明する説明図である。FIG. 1 is an explanatory view for explaining a surface inspection method for a continuous cast material of the present invention. 図2は、連続鋳造されたマグネシウム基板材(鋳造板)において、乱反射光による像を示す金属写真である。FIG. 2 is a metal photograph showing an image of irregularly reflected light in a continuously cast magnesium substrate material (cast plate). 図3(I)は、連続鋳造されたマグネシウム基板材(鋳造板)の顕微鏡写真であり、図3(II)は、この顕微鏡写真の模式図である。FIG. 3 (I) is a micrograph of a continuously cast magnesium substrate material (cast plate), and FIG. 3 (II) is a schematic diagram of this micrograph. 図4は、連続鋳造されたマグネシウム基板材(鋳造板)において、正反射光による像を示す金属写真である。FIG. 4 is a metal photograph showing an image of regular reflection light on a continuously cast magnesium substrate material (cast plate).
　以下、図面を参照して本発明の実施の形態を説明する。
　本発明は、マグネシウム又はマグネシウム合金からなる鋳造材(以下、Mg基鋳造材と呼ぶ)100の表面状態を検査するための表面検査方法に係るものである。Mg基鋳造材100は、連続鋳造機(ここでは、一対の可動鋳型(ロール200)を具える双ロール鋳造機)により連続的に鋳造される薄い板材であり、例えば、図1に示すように紙面の左側から右側に向かって、直線状に進行する間に冷却されて、巻き取り機(図示せず)により巻き取られる。ここでは、Mg基鋳造材100の表面状態の検査を図1に示す表面検査装置1により行う。以下、表面検査装置1を中心に説明する。 Embodiments of the present invention will be described below with reference to the drawings.
The present invention relates to a surface inspection method for inspecting the surface state of a cast material (hereinafter referred to as Mg-based cast material) 100 made of magnesium or a magnesium alloy. The Mg-based casting material 100 is a thin plate material continuously cast by a continuous casting machine (here, a twin roll casting machine including a pair of movable molds (rolls 200)), for example, as shown in FIG. The paper is cooled while proceeding linearly from the left side to the right side of the paper, and is wound up by a winder (not shown). Here, the surface state of the Mg-based cast material 100 is inspected by the surface inspection apparatus 1 shown in FIG. Hereinafter, the surface inspection apparatus 1 will be mainly described.
　[表面検査装置]
　表面検査装置1は、連続鋳造機のロール200を通過したMg基鋳造材100の表面状態を検査するための装置であり、ここでは、上記連続鋳造機と上記巻き取り機との間に存在するMg基鋳造材100の表面を検査できるように、以下の各構成部材が配置されている。 [Surface inspection equipment]
The surface inspection apparatus 1 is an apparatus for inspecting the surface state of the Mg-based cast material 100 that has passed through the roll 200 of the continuous casting machine, and here, exists between the continuous casting machine and the winder. The following constituent members are arranged so that the surface of the Mg-based cast material 100 can be inspected.
　表面検査装置1は、Mg基鋳造材100の表面に対して光を出射する光源10と、光源10からの光を利用して、Mg基鋳造材100の表面の像を撮像する光学撮像機11と、光学撮像機11により得られた像を画像処理し、この処理像に基づいて、Mg基鋳造材100の表面状態を検査する画像処理検査部12とを具える。 The surface inspection apparatus 1 includes a light source 10 that emits light to the surface of the Mg-based casting material 100, and an optical imaging device 11 that captures an image of the surface of the Mg-based casting material 100 using light from the light source 10. And an image processing inspection unit 12 that performs image processing on the image obtained by the optical imaging device 11 and inspects the surface state of the Mg-based cast material 100 based on the processed image.
　＜光源＞
　光源10は、出射光の直進性が高いものが好ましい。ここでは、LED(発光ダイオード)を利用している。LEDは、フィラメントを利用した光源と比較して寿命が長く、連続的な使用に適している。光源10の数は、光源の仕様、光学撮像機の数、及びMg基鋳造材100の幅(Mg基鋳造材100の進行方向と直交する方向(図1において紙面の手前から奥に向かう方向)の長さ)に応じて適宜選択するとよい。市販の光源を利用することができる。 <Light source>
The light source 10 is preferably a light source that has high rectilinearity. Here, LEDs (light emitting diodes) are used. LEDs have a longer life than light sources using filaments and are suitable for continuous use. The number of light sources 10 is the specification of the light source, the number of optical imaging devices, and the width of the Mg-based casting material 100 (the direction orthogonal to the traveling direction of the Mg-based casting material 100 (the direction from the front to the back in FIG. 1)). The length may be selected appropriately according to the length of A commercially available light source can be used.
　＜光学撮像機＞
　光学撮像機11は、CCD(Charge　Coupled　Device),CMOS(Complementary　Metal　Oxide　Semiconductor)といった撮像素子を具えるカメラを好適に利用することができる。これらの撮像素子は、反応速度が速いことから、これらの撮像素子を具えるカメラは、走行する連続鋳造材(例えば、1m/min～10m/min)の表面状態を連続的に撮像することに適している。また、このような撮像素子を多く具えるカメラを利用することで、一度に広範囲の領域を高精度に撮像することができる。ここでは、1000万画素のCCDカメラを利用している。画素数(撮像素子の数)や光学撮像機11の数は、主としてMg基鋳造材100の幅に応じて適宜選択するとよい。複数の光学撮像機11を配置することで、Mg基鋳造材100の幅が大きくても一度に全幅に亘る領域を撮像することができる。市販の光学撮像機を利用することができる。 <Optical imager>
As the optical imaging device 11, a camera including an imaging device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) can be preferably used. Since these imaging devices have a fast reaction speed, a camera equipped with these imaging devices is capable of continuously imaging the surface state of a continuous casting material that travels (for example, 1 m / min to 10 m / min). Is suitable. In addition, by using a camera having a large number of such image sensors, a wide area can be imaged with high accuracy at a time. Here, a 10 million pixel CCD camera is used. The number of pixels (the number of image pickup devices) and the number of optical image pickup devices 11 may be appropriately selected mainly according to the width of the Mg-based casting material 100. By arranging a plurality of optical imaging devices 11, even when the width of the Mg-based cast material 100 is large, it is possible to image a region over the entire width at a time. A commercially available optical imager can be used.
　《光源及び光学撮像機の配置》
　ここでは、Mg基鋳造材100の進行方向(図1では左右方向)に対して上流側(連続鋳造機側(図1では左側))に光源10及び光学撮像機11の双方を配置している。具体的には、Mg基鋳造材100の表面において当該Mg基鋳造材100の進行方向に対して光源10の光軸10a及び光学撮像機11の光軸11aがいずれも、非直交に交差するように配置されている。より具体的には、上記進行方向に対する光源10の光軸10aの傾斜角度θ(入射光の入射角に等しい)が約65°、上記進行方向に対する光学撮像機11の光軸11aの傾斜角度αが約30°となるように、光源10及び光学撮像機11が配置されている。ここでは、光学撮像機11の傾斜角度αが光源10の傾斜角度θよりも小さい。なお、図1に示すθ,αの角度は例示である。 《Arrangement of light source and optical imaging device》
Here, both the light source 10 and the optical imaging device 11 are arranged on the upstream side (continuous casting machine side (left side in FIG. 1)) with respect to the traveling direction of the Mg-based casting material 100 (left and right direction in FIG. 1). . Specifically, the optical axis 10a of the light source 10 and the optical axis 11a of the optical imaging device 11 are non-orthogonally intersecting with the traveling direction of the Mg-based casting material 100 on the surface of the Mg-based casting material 100. Is arranged. More specifically, the inclination angle θ of the optical axis 10a of the light source 10 with respect to the traveling direction (equal to the incident angle of incident light) is about 65 °, and the inclination angle α of the optical axis 11a of the optical imaging device 11 with respect to the traveling direction. The light source 10 and the optical imaging device 11 are arranged so that the angle is about 30 °. Here, the inclination angle α of the optical imaging device 11 is smaller than the inclination angle θ of the light source 10. The angles θ and α shown in FIG. 1 are examples.
　このように光源10の傾斜角度θ(入射角)を90°未満、光学撮像機11の傾斜角度αを60°以下とし、かつ光源10と光学撮像機11とをMg基鋳造材100に対して同じ側(ここでは上流側)に配置することで、光学撮像機11は、光源10から出射された出射光(光源10から出射されてMg基鋳造材100に入射する入射光)そのもの、及び当該入射光の正反射光の双方を実質的に受光することがない。従って、光学撮像機11は、Mg基鋳造材100の表面に微小な割れなどの表面欠陥が無ければ、光源10に基づく光が実質的に受光されないことから、暗い像を撮像することになる。 Thus, the inclination angle θ (incident angle) of the light source 10 is less than 90 °, the inclination angle α of the optical imaging device 11 is 60 ° or less, and the light source 10 and the optical imaging device 11 are made to the Mg-based casting material 100. By disposing on the same side (here upstream), the optical imaging device 11 can emit light emitted from the light source 10 (incident light emitted from the light source 10 and incident on the Mg-based casting material 100) itself, and Both the regular reflection lights of the incident light are not substantially received. Therefore, the optical imager 11 captures a dark image because the light based on the light source 10 is not substantially received unless there is a surface defect such as a minute crack on the surface of the Mg-based cast material 100.
　一方、Mg基鋳造材100に表面欠陥が存在する場合、光源10からの光がこの表面欠陥に当たることで乱反射光を生じ、光学撮像機11は、この乱反射光を受光することができる。従って、この場合、光学撮像機11は、上記乱反射光による像、即ち、表面欠陥部分が明るく、その他の部分が暗い、明暗のコントラストが大きな像を撮像することができる。 On the other hand, when there is a surface defect in the Mg-based cast material 100, the light from the light source 10 hits the surface defect to generate irregular reflection light, and the optical imaging device 11 can receive the irregular reflection light. Therefore, in this case, the optical imaging device 11 can capture an image by the irregularly reflected light, that is, an image having a large contrast between light and dark, where the surface defect portion is bright and other portions are dark.
　なお、光源10及び光学撮像機11の双方をMg基鋳造材100の進行方向に対して下流側(巻き取り機側(図1では右側))に配置させてもよい。また、傾斜角度θが傾斜角度αより小さくなるように、光源10及び光学撮像機11を配置してもよい。 Note that both the light source 10 and the optical imaging device 11 may be arranged on the downstream side (winder side (right side in FIG. 1)) with respect to the traveling direction of the Mg-based cast material 100. Further, the light source 10 and the optical imaging device 11 may be arranged so that the inclination angle θ is smaller than the inclination angle α.
　＜画像処理検査部＞
　画像処理検査部12は、光学撮像機11からの像を取得する入力手段121と、取得した像を二値化する二値化手段122と、得られた二値化像に基づいて表面欠陥の有無を判定する明暗判定手段123とを具える。 <Image processing inspection unit>
The image processing inspection unit 12 includes an input unit 121 that acquires an image from the optical imaging device 11, a binarization unit 122 that binarizes the acquired image, and a surface defect based on the obtained binarized image. Light / dark determination means 123 for determining presence / absence is provided.
　光学撮像機11により得られた像は、上述ように明暗のコントラストが大きい像である。従って、二値化手段122によって明領域と暗領域との区別を行い易く、割れの領域(明領域)を精度よく抽出することができる。 The image obtained by the optical imaging device 11 is an image having a large contrast between light and dark as described above. Therefore, it is easy to distinguish the bright area and the dark area by the binarizing means 122, and the cracked area (bright area) can be extracted with high accuracy.
　明暗判定手段123は、例えば、二値化像において明領域の有無を判定する構成とすることができる。上述のようにMg基鋳造材100に表面欠陥が存在した場合、表面欠陥は、取得した像において明るい領域で示される。従って、明領域が有ると判定された場合、表面欠陥が有ると判別することができる。 The light / dark determination means 123 may be configured to determine, for example, the presence or absence of a bright region in a binarized image. As described above, when a surface defect exists in the Mg-based cast material 100, the surface defect is indicated by a bright region in the acquired image. Therefore, when it is determined that there is a bright region, it can be determined that there is a surface defect.
　或いは、明領域が有ると判定された場合に、その明領域の大きさを測定し、当該明領域におけるMg基鋳造材100の進行方向に沿った長さが所定の長さ以上の場合に、当該明領域は表面欠陥であり、表面欠陥が有ると判定するように明暗判定手段123を構成することができる。この場合、鋳造後の圧延工程において消滅するような小さな疵と、最終製品に悪影響を及ぼすような割れとを区別して判別することができる。上記明領域の大きさの測定は、例えば、撮像素子の大きさに基づき演算するように画像処理検査部12に演算手段を設けておくことで、自動的に、かつ迅速に行うことができる。また、明領域が複数存在した場合は、各明領域について大きさを測定するように明暗判定手段123を構成することができる。 Alternatively, when it is determined that there is a bright region, the size of the bright region is measured, and when the length along the traveling direction of the Mg-based casting material 100 in the bright region is a predetermined length or more, The bright region is a surface defect, and the light / dark determination means 123 can be configured to determine that there is a surface defect. In this case, it is possible to distinguish and distinguish small wrinkles that disappear in the rolling process after casting from cracks that adversely affect the final product. The measurement of the size of the bright region can be performed automatically and quickly by providing a calculation means in the image processing inspection unit 12 so as to calculate based on the size of the image sensor, for example. In addition, when there are a plurality of bright regions, the light / dark determination means 123 can be configured to measure the size of each bright region.
　このような画像処理検査部12は、上記入力手段121や二値化手段122、明暗判定手段123、演算手段を具える市販の画像処理手段を利用したり、市販の画像処理手段の一部の構成を適宜変更して利用することができる。 Such an image processing inspection unit 12 uses commercially available image processing means including the input means 121, binarization means 122, brightness / darkness determination means 123, and arithmetic means, or a part of the commercially available image processing means. The configuration can be appropriately changed and used.
　更に、ここでは、画像処理検査部12は、表面欠陥を検出した場合、Mg基鋳造材100における欠陥箇所を記録するための記録手段124を具える。ここで、連続鋳造機により製造され、巻き取り機により巻き取られるMg基鋳造材100は、連続鋳造機のロール200の回転速度(或いは回転数)、及び巻き取り機の回転速度(或いは回転数)により、その走行速度が制御される。従って、Mg基鋳造材10の走行速度や巻き取り機の回転速度などと、鋳造開始からの現検出時の時間とが分かれば、光学撮像機11により現に撮像しているMg基鋳造材100の進行方向における位置、即ち、撮像中の位置を把握することができる。そこで、ここでは、撮像中の位置を自動的に測定する位置計測手段128を設けており、記録手段124は、上記判定情報と位置計測手段128からの位置情報とを記憶するように構成している。 Furthermore, here, the image processing inspection unit 12 includes a recording means 124 for recording a defect portion in the Mg-based cast material 100 when a surface defect is detected. Here, the Mg-based cast material 100 manufactured by the continuous casting machine and wound by the winder has the rotational speed (or rotational speed) of the roll 200 of the continuous casting machine and the rotational speed (or rotational speed) of the winder. ) Controls the traveling speed. Therefore, if the traveling speed of the Mg-based casting material 10, the rotational speed of the winder, and the time at the time of the current detection from the start of casting are known, the Mg-based casting material 100 currently being imaged by the optical imaging device 11 The position in the traveling direction, that is, the position during imaging can be grasped. Therefore, here, the position measuring unit 128 that automatically measures the position during imaging is provided, and the recording unit 124 is configured to store the determination information and the position information from the position measuring unit 128. Yes.
　位置計測手段128は、例えば、上述のように回転数を計測するエンコーダや、時間を計測するタイマなどを具えた構成が挙げられる。 The position measuring means 128 includes, for example, a configuration including an encoder that measures the number of revolutions as described above, a timer that measures time, and the like.
　記録手段124を具えて上記欠陥箇所を記録しておくことで、巻き取り機に巻き取られた後であっても、Mg基鋳造材100の欠陥箇所を容易に把握することができる。従って、この構成では、鋳造材を切断することなく、生産性よく連続鋳造材を製造することができる。 By recording the defect portion with the recording means 124, the defect portion of the Mg-based cast material 100 can be easily grasped even after being wound on the winder. Therefore, with this configuration, a continuous cast material can be manufactured with high productivity without cutting the cast material.
　その他、二値化像や判定結果を作業者が確認できるようにモニタ125や、各種の設定条件を入力できるようにキーボードなどの作業者操作手段(図示せず)を具えていてもよい。 In addition, the monitor 125 may be provided so that the operator can check the binarized image and the determination result, and operator operation means (not shown) such as a keyboard may be provided so that various setting conditions can be input.
　なお、例えば、画像処理検査部12に別途記憶手段を具えて二値化像をこの記憶手段に保存しておき、記憶手段から二値化像を呼び出して、作業者が目視などで確認する構成とすることができる。しかし、上述のように画像処理検査部12に明暗判定手段123などを具えて、表面欠陥の有無の判定を自動的に行う構成とすると、当該判定を短時間で、かつ容易に行えて好ましい。 Note that, for example, a configuration in which the image processing inspection unit 12 is separately provided with storage means and the binarized image is stored in the storage means, and the binarized image is called from the storage means and checked by the operator visually. It can be. However, it is preferable that the image processing inspection unit 12 includes the light / dark determination unit 123 and the like to automatically determine the presence / absence of a surface defect as described above, because the determination can be easily performed in a short time.
　＜遮光部材＞
　その他、ここでは、光源10からの正反射光を吸収できるように、正反射光を受光可能な位置に遮光部材13を配置している。遮光部材13を配置することで、例えば、割れの部分とその他の部分とのコントラストを更に高め易く、微細な割れであっても精度良く検出することができる。また、遮光部材13を配置することで、連続鋳造機が工場内などに配置されて、工場内の照明などの外部光源が存在する場合でも、この外部光源による光(外乱光)をも遮蔽することができる。遮光部材13は、正反射光を吸収することができ、外乱光を遮蔽することが可能な材質からなるもの、代表的には黒体が挙げられる。 <Light shielding member>
In addition, here, the light shielding member 13 is disposed at a position where the regular reflection light can be received so that the regular reflection light from the light source 10 can be absorbed. By disposing the light shielding member 13, for example, the contrast between the cracked portion and other portions can be further enhanced, and even a fine crack can be detected with high accuracy. In addition, by arranging the light shielding member 13, even when the continuous casting machine is arranged in a factory or the like and there is an external light source such as lighting in the factory, the light (disturbance light) from the external light source is also shielded. be able to. The light blocking member 13 can be made of a material that can absorb specularly reflected light and can block disturbance light, typically a black body.
　図1では、Mg基鋳造材100の表面の一部が覆われるように板状の遮光部材13を配置した状態を示している。その他、光源10及び光学撮像機11の視野を遮らないようにMg基鋳造材100において下流側の表面全体が覆われるように、遮光部材13を筒状にしたり、樋状にしてもよい。 FIG. 1 shows a state where the plate-shaped light shielding member 13 is arranged so that a part of the surface of the Mg-based cast material 100 is covered. In addition, the light shielding member 13 may be formed in a cylindrical shape or a bowl shape so that the entire downstream surface of the Mg-based cast material 100 is covered so as not to obstruct the visual field of the light source 10 and the optical imaging device 11.
　[効果]
　上記表面検査装置1を用いて光学撮像機11により、Mg基鋳造材100の表面状態を検査するにあたり、撮像した画像を確認したところ、図2に示すように、線状の明るい領域と、それ以外が非常に暗い領域とからなる、明暗のコントラストが大きい像が得られた。このMg基鋳造材100に対して、別途、顕微鏡観察を行ったところ、上記線状の領域に微細な割れが存在していることを確認できた。従って、上述のような像を取得するように光源10及び光学撮像機11を具える表面検査装置1は、微小な割れであっても、高精度に、かつ迅速にその存在を検出することができると期待される。 [effect]
When inspecting the surface state of the Mg-based cast material 100 with the optical imaging device 11 using the surface inspection apparatus 1, the captured image was confirmed, and as shown in FIG. An image with a large contrast between light and dark was obtained. When this Mg-based cast material 100 was separately observed with a microscope, it was confirmed that fine cracks were present in the linear region. Therefore, the surface inspection apparatus 1 including the light source 10 and the optical imaging device 11 so as to acquire the image as described above can detect the presence thereof with high accuracy and speed even if it is a minute crack. It is expected to be possible.
　また、上記表面検査装置1を用いることで、Mg基鋳造材100に比較的粗い凹凸が存在する場合でも、微細な割れと比較的大きな割れとを選択的に検出することができると期待される。 Further, by using the surface inspection apparatus 1, it is expected that a fine crack and a relatively large crack can be selectively detected even when the Mg-based cast material 100 has relatively rough irregularities. .
　更に、上記表面検査装置1は、連続鋳造機により鋳造されたMg基鋳造材100が巻き取り機により巻き取られるまでの間に上記表面状態の検査を行う。この構成により、検査のためにMg基鋳造材100を切断することが無く、鋳造と同時に検査を行える。従って、上記表面検査装置1を利用して表面検査を行うことで、Mg基鋳造材100を生産性よく製造することができる。 Further, the surface inspection apparatus 1 inspects the surface state until the Mg-based cast material 100 cast by the continuous casting machine is wound up by the winder. With this configuration, the Mg-based cast material 100 is not cut for inspection, and inspection can be performed simultaneously with casting. Therefore, by performing the surface inspection using the surface inspection apparatus 1, the Mg-based cast material 100 can be manufactured with high productivity.
　特に、ここでは、Mg基鋳造材100として、AZ91合金相当の組成からなるものとしたことで微細な割れが生じ易いと考えられるが、上記表面検査装置1を利用することで、図2に示すように、微細な割れを精度よく捉えることができる。 In particular, here, it is considered that the Mg-based cast material 100 is made of a composition equivalent to the AZ91 alloy, so that it is considered that fine cracks are likely to occur. However, by using the surface inspection apparatus 1 shown in FIG. As described above, it is possible to accurately capture fine cracks.
　なお、上述した実施形態は、本発明の要旨を逸脱することなく、適宜変更することが可能であり、上述した構成に限定されるものではない。例えば、Mg基鋳造材として、純マグネシウムやその他の組成のマグネシウム合金からなるものとすることができる。 It should be noted that the above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the Mg-based cast material can be made of pure magnesium or a magnesium alloy having another composition.
　本発明マグネシウム基板材の製造方法は、携帯用電子機器といった種々の電子機器類の筐体などに利用されるマグネシウム又はマグネシウム合金からなる板材の製造に好適に利用することができる。本発明連続鋳造材の表面検査方法及び表面検査装置は、上記本発明マグネシウム基板材の製造にあたり、中間生産物である鋳造材の表面状態の検査に好適に利用することができる。 The method for producing a magnesium substrate material of the present invention can be suitably used for producing a plate made of magnesium or a magnesium alloy used for a housing of various electronic devices such as portable electronic devices. The surface inspection method and the surface inspection apparatus for the continuous cast material of the present invention can be suitably used for the inspection of the surface state of the cast material which is an intermediate product in the production of the magnesium substrate material of the present invention.
　1　表面検査装置　10　光源　11　光学撮像機　12　画像処理検査部
　13　遮光部材
　10a,11a　光軸　121　入力手段　122　二値化手段　123　明暗判定手段
　124　記録手段　125　モニタ　128　位置計測手段
　100　Mg基鋳造材　200　ロール 1 Surface inspection device 10 Light source 11 Optical imager 12 Image processing inspection unit 13 Shading member 10a, 11a Optical axis 121 Input means 122 Binarization means 123 Brightness / darkness judgment means 124 Recording means 125 Monitor 128 Position measurement means 100 Mg base cast material 200 roll

Claims (7)

  1. 　連続鋳造機により連続的に鋳造されるマグネシウム又はマグネシウム合金からなる鋳造材の表面に光を入射し、
    　前記入射光が前記鋳造材の表面欠陥に当たることで生じた乱反射光を主たる検出光とし、この検出光による像を光学撮像機により捉え、
    　前記光学撮像機により得られた像に基づいて前記鋳造材の表面状態を検査することを特徴とする連続鋳造材の表面検査方法。     Light is incident on the surface of the cast material made of magnesium or magnesium alloy continuously cast by a continuous casting machine,
    The incident light is mainly detected light that is irregularly reflected light generated by hitting a surface defect of the cast material, and an image obtained by the detected light is captured by an optical imaging device.
    A method for inspecting a surface of a continuous cast material, wherein the surface state of the cast material is inspected based on an image obtained by the optical imaging device.
  2. 　前記光学撮像機による撮像は、前記入射光、及びこの入射光の正反射光を実質的に受光せず、前記乱反射光を受光する位置に前記光学撮像機を配置して行うことを特徴とする請求項1に記載の連続鋳造材の表面検査方法。 Imaging by the optical imaging device is performed by placing the optical imaging device at a position where the incident light and the regular reflection light of the incident light are not substantially received and the irregular reflection light is received. 2. The surface inspection method for a continuous cast material according to claim 1.
  3. 　前記入射光の入射角を90°未満、及び前記鋳造材の表面に対する前記光学撮像機の光軸の傾斜角度を60°以下にすることを特徴とする請求項1又は2に記載の連続鋳造材の表面検査方法。 3. The continuous cast material according to claim 1, wherein an incident angle of the incident light is less than 90 °, and an inclination angle of the optical axis of the optical imaging device with respect to the surface of the cast material is 60 ° or less. Surface inspection method.
  4. 　前記入射光の正反射光を吸収し、外乱光を遮蔽する遮光部材により、前記鋳造材の外周の少なくとも一部を覆うことを特徴とする請求項1～3のいずれか1項に記載の連続鋳造材の表面検査方法。 4. The continuous apparatus according to claim 1, wherein at least a part of the outer periphery of the cast material is covered with a light shielding member that absorbs specularly reflected light of the incident light and shields disturbance light. Cast surface inspection method.
  5. 　前記マグネシウム合金は、Alを7.5質量％超12質量％以下含有することを特徴とする請求項1～4のいずれか1項に記載の連続鋳造材の表面検査方法。 5. The method for inspecting a surface of a continuous cast material according to claim 1, wherein the magnesium alloy contains more than 7.5 mass% and not more than 12 mass% of Al.
  6. 　マグネシウム又はマグネシウム合金からなるマグネシウム基板材の製造方法であって、
    　マグネシウム又はマグネシウム合金を連続的に鋳造して連続鋳造材を製造する鋳造工程を具え、
    　前記鋳造工程には、請求項1～5のいずれか1項に記載の連続鋳造材の表面検査方法による検査工程を含むことを特徴とするマグネシウム基板材の製造方法。     A method for producing a magnesium substrate material made of magnesium or a magnesium alloy,
    Comprising a casting process of continuously casting magnesium or a magnesium alloy to produce a continuous cast material,
    6. The method for producing a magnesium substrate material, wherein the casting step includes an inspection step by the surface inspection method for a continuous cast material according to any one of claims 1 to 5.
  7. 　連続鋳造機により連続的に鋳造されるマグネシウム又はマグネシウム合金からなる鋳造材の表面状態を検査するための表面検査装置であり、
    　前記鋳造材の表面に光を出射する光源と、
    　前記出射光が前記鋳造材の表面欠陥に当たることで生じた乱反射光を主たる検出光とし、この検出光による像を撮像する光学撮像機と、
    　前記光学撮像機により得られた像に基づいて前記鋳造材の表面状態を検査する画像処理検査部とを具えることを特徴とする連続鋳造材の表面検査装置。     A surface inspection device for inspecting the surface state of a cast material made of magnesium or a magnesium alloy continuously cast by a continuous casting machine,
    A light source that emits light to the surface of the cast material;
    An optical imager that captures an image by this detection light, with the irregularly reflected light generated when the emitted light hits a surface defect of the cast material as the main detection light;
    An apparatus for inspecting a surface of a continuous cast material, comprising: an image processing inspection unit for inspecting a surface state of the cast material based on an image obtained by the optical imaging device.
PCT/JP2010/069529 2009-11-06 2010-11-02 Method of inspecting obverse surface of continuous cast material WO2011055728A1 (en)

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