Patent Publication Number: US-2021193350-A1

Title: Manufacturing method of plated wire rod and manufacturing apparatus of plated wire rod

Description:
TECHNICAL FIELD 
     The present disclosure is related to a manufacturing method of a plated wire rod, and a manufacturing apparatus of a plated wire rod. The present application claims priority based on Japanese Patent Application No. 2018-186596 filed on Oct. 1, 2018, the entire content of which is incorporated herein by reference. 
     BACKGROUND ART 
     Conventionally, a metal terminal is used to connect electrical components to each other. For example, a metal terminal is fixed to a resin base and is soldered to a printed circuit board as an electrical component to form a substrate connector, and the printed circuit board and a connector as the other electrical component provided at an end of an external electric wire are connected to each other; or a pair of printed circuit boards as the electrical components are connected to each other using a metal terminal as an inter-substrate connection terminal. 
     The metal terminal is manufactured by press-cutting a conductive metal plate, a surface of which is plated with metal, or by cutting a plated wire rod, which is a metal wire rod plated with metal, into a predetermined length. Such a metal terminal is disclosed in Japanese Patent Laying-Open No. 2004-303680 (PTL 1), for example. 
     In recent years, electrification of vehicles is being accelerated, and the number of circuits in an electrical appliance is on the increase. Accordingly, multiplication of terminals are becoming more and more advanced. The insertion force at the time of assembly is increased in proportion to the number of terminals, and thus, the challenge is to suppress an increase in the workload and to stably maintain the connection. 
     For example, with respect to a material of a removable metal terminal, the coefficient of friction is reduced by forming, on an outermost layer of a conductive material, a metal plating layer or an alloy layer containing metal, or by further specifying the degree of exposure of the alloy layer (for example, see Japanese Patent Laying-Open No. 2003-147579 (PTL 2)). 
     Moreover, as a manufacturing method of a metal square wire-connector terminal, there is also known a method that uses a plated wire rod that is formed by applying metal plating to a conductive metal that is molded by a die, a roller or the like, and then performing die-drawing after heat treatment (for example, see Japanese Patent Laying-Open No. 2015-120966 (PTL 3)). 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Laying-Open No. 2004-303680 
     PTL 2: Japanese Patent Laying-Open No. 2003-147579 
     PTL 3: Japanese Patent Laying-Open No. 2015-120966 
     SUMMARY OF INVENTION 
     A manufacturing method of a plated wire rod according to a mode of the present disclosure is a manufacturing method of a plated wire rod including: 
     preparing a plated wire rod precursor including a base material that is wire-drawn and that has a linear shape and a plating film that is provided on a surface of the base material, where the base material is made of first metal and the plating film is made of second metal of a different composition from the first metal; 
     obtaining a plated wire rod-intermediate body by performing skin-passing on the plated wire rod precursor using a die; 
     inspecting, after the skin-passing, for presence/absence of a defect in the plated wire rod-intermediate body using an eddy current testing device and a camera inspection device; and 
     obtaining a plated wire rod by removing the defect in the plated wire rod-intermediate body that is detected in the inspecting. 
     Additionally, in the present disclosure, skin-passing refers to rolling or drawing of the plated wire rod precursor. 
     A manufacturing apparatus of a plated wire rod according to a mode of the present disclosure is a manufacturing apparatus of a plated wire rod including: 
     a supply unit that draws out a plated wire rod precursor from a reel around which the plated wire rod precursor is wound, the plated wire rod precursor including a base material having a linear shape and a plating film provided on a surface of the base material; 
     a processing unit that obtains a plated wire rod-intermediate body by performing skin-passing on the plated wire rod precursor using a die; 
     an inspection unit that inspects for presence/absence of a defect in the plated wire rod-intermediate body using an eddy current testing device and a camera inspection device; and 
     a removal mechanism that obtains a plated wire rod by removing the defect in the plated wire rod-intermediate body. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram showing an example of a manufacturing apparatus of a plated wire rod according to an embodiment of the present disclosure. 
         FIG. 2  is a schematic diagram showing an example structure of the plated wire rod. 
         FIG. 3  is a schematic diagram showing an example of a defect occurring in a plated wire rod-intermediate body. 
         FIG. 4  is a schematic diagram showing another example of the defect occurring in the plated wire rod-intermediate body. 
     
    
    
     DETAILED DESCRIPTION 
     Problem to be Solved by the Present Disclosure 
     To cause a high current to flow through a metal terminal, it is important to increase the diameter of the metal terminal and to secure contact with another member. In the case of a metal terminal that uses a plated wire rod that is formed by applying metal plating to the surface of a metal base material, defects such as scratches on the base material or failed plating of metal plating may result in increased contact resistance of the metal terminal. Furthermore, if, after heat treatment, die-drawing is performed on the plated wire rod, the surface of the metal base material of which is plated with metal, metal plating is possibly scratched or peeled off. 
     In view of the circumstances described above, the present disclosure has its object to provide a manufacturing method of a plated wire rod with few defects by highly accurately detecting, for a plated wire rod that is formed by applying metal plating to the surface of a metal base material, defects present on an interface between the base material and the metal plating and on the surface of the metal plating, and a manufacturing apparatus of a plated wire rod capable of performing the method. 
     Advantageous Effect of the Present Disclosure 
     According to the present disclosure, there may be provided a manufacturing method of a plated wire rod with few defects by highly accurately detecting, for a plated wire rod that is formed by applying metal plating to the surface of a metal base material, defects present on an interface between the base material and the metal plating and on the surface of the metal plating, and a manufacturing apparatus of a plated wire rod capable of performing the method. 
     DESCRIPTION OF EMBODIMENTS 
     First, modes of the present disclosure will be enumerated. 
     (1) A manufacturing method of a plated wire rod according to a mode of the present disclosure is a manufacturing method of a plated wire rod including: 
     preparing a plated wire rod precursor including a base material that is wire-drawn and that has a linear shape and a plating film that is provided on a surface of the base material, where the base material is made of first metal and the plating film is made of second metal of a different composition from the first metal; 
     obtaining a plated wire rod-intermediate body by performing skin-passing on the plated wire rod precursor using a die; 
     inspecting, after the skin-passing, for presence/absence of a defect in the plated wire rod-intermediate body using an eddy current testing device and a camera inspection device; and 
     obtaining a plated wire rod by removing the defect in the plated wire rod-intermediate body that is detected in the inspecting. 
     According to the mode described in (1) above, there may be provided a manufacturing method of a plated wire rod with few defects by highly accurately detecting, for a plated wire rod that is formed by applying metal plating (a plating film) of second metal to the surface of a base material of first metal, defects present on an interface between the base material and the metal plating or on the surface of the metal plating. 
     Defects that can be detected by the manufacturing method of a plated wire rod according to the embodiment of the present disclosure include not only parts where the metal plating is peeled off, but also scratches on the surface of the metal plating where the base material is not exposed. 
     (2) In the manufacturing method of a plated wire rod described in (1) above, preferably, 
     the camera inspection device includes
         a light source that radiates light on a surface of the plated wire rod-intermediate body, and   an imaging mechanism that detects reflected light that is the light from the light source reflected by the surface of the plated wire rod-intermediate body, and       

     an image of a plurality of color components is extracted from an image captured by the imaging mechanism, and the defect in the plated wire rod-intermediate body is detected on a basis of an amount of difference in luminance between images of the plurality of color components. 
     According to the mode described in (2) above, a defect due to peeling-off of the plating film from the surface of the plated wire rod may be detected with high accuracy. 
     (3) In the manufacturing method of a plated wire rod described in (2) above, the image of the plurality of color components that is extracted from the image captured is preferably a color image or a monochrome image. 
     According to the mode described in (3) above, a defect due to peeling-off of the plating film from the surface of the plated wire rod over a large area, or a defect due to peeling-off of the plating film over a small area may be detected depending on the purpose. 
     (4) In the manufacturing method of a plated wire rod described in (2) or (3) above, the plurality of color components that are extracted from the image captured are preferably two or more among three components of red, blue and green. 
     According to the mode described in (4) above, by extracting an image using three primary colors of red, blue and green, a common device is allowed to be used, and simplification of a device is made possible. 
     (5) In the manufacturing method of a plated wire rod described in any one of (2) to (4) above, the light source is preferably a bar light (a line light). 
     According to the mode described in (5), occurrence of color unevenness due to the light source may be suppressed, and erroneous detection of defects may be inhibited. 
     Additionally, the bar light refers to a light where light emitting elements are linearly arranged and that performs surface light emission. 
     (6) In the manufacturing method of a plated wire rod described in any one of (2) to (5) above, the light source is preferably a white LED. 
     According to the mode described in (6) above, because the light source includes all visible light, binarization by which brightness is made the same for all colors is enabled. 
     (7) In the manufacturing method of a plated wire rod described in any one of (1) to (6) above, preferably, 
     a cross-section of the plated wire rod-intermediate body is quadrangular, and 
     the camera inspection device simultaneously inspects, using a mirror, for presence/absence of a defect for at least a pair of facing surfaces of the plated wire rod-intermediate body. 
     According to the mode described in (7) above, presence/absence of a defect may be inspected by one measurement, for at least a pair of facing surfaces of the plated wire rod. 
     (8) A manufacturing apparatus of a plated wire rod according to a mode of the present disclosure is a manufacturing apparatus of a plated wire rod including: 
     a supply unit that draws out a plated wire rod precursor from a reel around which the plated wire rod precursor is wound, the plated wire rod precursor including a base material having a linear shape and a plating layer (a plating film) provided on a surface of the base material; 
     a processing unit that obtains a plated wire rod-intermediate body by performing skin-passing on the plated wire rod precursor using a die; 
     an inspection unit that inspects for presence/absence of a defect in the plated wire rod-intermediate body using an eddy current testing device and a camera inspection device; and 
     a removal mechanism that obtains a plated wire rod by removing the defect in the plated wire rod-intermediate body. 
     According to the mode described in (8) above, there may be provided a manufacturing apparatus of a plated wire rod capable of performing the manufacturing method of a plated wire rod with few defects by highly accurately detecting, for a plated wire rod that is formed by applying metal plating to the surface of a base material, defects present on an interface between the base material and the metal plating or on the surface of the metal plating. 
     DETAILS OF MODES OF PRESENT DISCLOSURE 
     Specific examples of the manufacturing method of a plated wire rod and the manufacturing apparatus of the plated wire rod according to the modes of the present disclosure will be described below in greater detail. Additionally, the present invention is not limited to the examples, but is defined by the appended claims and is intended to include all modifications within the scope and meaning equivalent to those of the claims. 
     &lt;Manufacturing Method of Plated Wire Rod&gt; 
     The manufacturing method of a plated wire rod according to an embodiment of the present disclosure includes a step of preparing a plated wire rod precursor (a preparation step), a step of obtaining a plated wire rod-intermediate body by performing skin-passing on the plated wire rod precursor (a processing step), and a step of inspecting, after the skin-passing, for presence/absence of a defect in the plated wire rod-intermediate body (an inspection step). Details of each step will be described below. 
     (Preparation Step) 
     The preparation step is a step of preparing a plated wire rod precursor including a conductive metal base material that is wire-drawn and that has a linear shape (hereinafter simply referred to as “base material”) and a plating film provided on a surface of the base material. In the present embodiment, the base material is made of first metal. Furthermore, the plating film is made of second metal of a different composition from the first metal. 
       FIG. 2  shows a schematic diagram of a structure of a plated wire rod  20 . In an aspect of the present embodiment,  FIG. 2  may be assumed to be a schematic diagram of a structure of a plated wire rod precursor  20   a , or may be assumed to be a schematic diagram of a structure of a plated wire rod-intermediate body  20   b  described later. Plated wire rod  20  is not limited with respect to a cross-sectional shape as long as plated wire rod  20  is wire-drawn and has a linear shape. For example, the cross-sectional shape of plated wire rod  20  may be a circle, an oval, a square, a rectangle, or a square or a rectangle with rounded corners. Furthermore, it is sufficient if plated wire rod  20  includes a plating film  22  on a surface of a base material  21  that is wire-drawn and that has a linear shape, where plating film  22  is made of the second metal different from the first metal forming base material  21 . 
     Additionally, plating film  22  is formed around an entire circumference of base material  21 . Furthermore, there may be provided a plurality of layers of plating film  22 , instead of one layer of the same. 
     The first metal forming base material  21  may be a simple metal or an alloy, and for example, copper, tough-pitch copper, copper alloys (brass and the like), iron, iron alloys, aluminum, aluminum alloys and the like may be cited as the first metal. 
     The second metal forming plating film  22  may be a simple metal or an alloy, and copper, nickel, tin, silver, gold and the like may be cited as the second metal. 
     Considering that plated wire rod  20  that is obtained by the manufacturing method of a plated wire rod according to the embodiment of the present disclosure is to be used as a metal terminal, the first metal forming base material  21  is preferably copper or a copper alloy, and the second metal forming plating film  22  is preferably tin, from the standpoint of contact resistance, contact reliability, durability, solderability, economic performance and the like. Furthermore, plating film  22  may also preferably include an underlying plating film of copper, nickel or the like, and a plating film of tin or an alloy containing tin as the main element may be formed on a surface of the underlying plating film. Furthermore, plated wire rod  20  may be annealed. 
     A cross-sectional dimension of the plated wire rod is not particularly specified, and may be adjusted to a desired dimension. A thickness of plating film  22  is also not limited, and may be selected as appropriate. 
     (Processing Step) 
     The processing step is a step of performing skin-passing on the plated wire rod precursor that is prepared in the preparation step. Skin-passing may be performed using a die. A plated wire rod-intermediate body may be obtained by performing the processing step. 
     The shape of a surface of the plated wire rod-intermediate body may be processed into a desired shape by performing skin-passing on the plated wire rod precursor. For example, even in a case of a plated wire rod precursor having a flat base material, and having a plating film of a relatively non-uniform thickness formed on the surface of the base material, a plated wire rod-intermediate body with a plating film having a uniform and thin thickness may be obtained by performing skin-passing using a die. 
     However, in skin-passing, a relatively large force is applied to a processing target object. Accordingly, if skin-passing is performed on plated wire rod precursor  20   a , plating film  22  on the surface of plated wire rod-intermediate body  20   b  is possibly scratched and dented (see  FIG. 3 ), or peeling-off is possibly caused at an interface between base material  21  and plating film  22  (see  FIG. 4 ). If plated wire rod-intermediate body  20   b  with plating film  22  including a defect such as a scratch or peeling-off is processed into and used as a metal terminal, contact between the metal terminal and another connection member becomes poor, and contact resistance is increased. Accordingly, the part of the plated wire rod-intermediate body where a defect is present has to be removed in a manufacturing process of the plated wire rod. 
     In the manufacturing method of a plated wire rod according to the embodiment of the present disclosure, presence/absence of a defect in plated wire rod-intermediate body  20   b  is inspected in the inspection step, and also, removal of the defect in the plated wire rod-intermediate body is performed in the removal step that is subsequently performed. 
     Additionally, generally, a plated wire rod precursor may include, even before skin-passing, a failed plating portion where an adhesive force of the plating film on the surface of the base material is low. Such a failed plating portion may become evident in the form of a defect when the plating film is peeled off at a time when the plated wire rod precursor is wound around the reel, for example. Furthermore, even if the defective plating portion does not become evident in the form of a defect, the failed plating portion has to be removed because, when the plated wire rod is processed into and used as a metal terminal, the failed plating portion causes an increase in the contact resistance between the metal terminal and another connection member. However, the defective plating portion is difficult to detect simply by observing the plated wire rod-intermediate body from outside. 
     In the manufacturing method of a plated wire rod according to the embodiment of the present disclosure, skin-passing performed in the processing step serves the role of a stress test, and may cause the failed plating portion that is latent in the plated wire rod-intermediate body to be made evident in the form of a defect. That is, when skin-passing is performed, the plating film is peeled off at the failed plating portion, and the failed plating portion becomes detectable as an external defect. 
     (Inspection Step) 
     The inspection step is a step performed after skin-passing, of inspecting for presence/absence of a defect in the plated wire rod-intermediate body using an eddy current testing device and a camera inspection device. According to an aspect of the present embodiment, the order of inspection using the eddy current testing device and inspection using the camera inspection device is not particularly specified. The inspection using the eddy current testing device may be performed first, or the inspection using the camera inspection device may be performed first. 
     —Eddy Current Testing Device— 
     By performing inspection of the plated wire rod-intermediate body using the eddy current testing device, step-shaped defects such as scratches formed on the surface of plated wire rod-intermediate body  20   b  as shown in  FIG. 3  and impurities deposited on the surface of plating film  22  may be mainly detected. Any conventionally known eddy current testing device may be used. 
     Generally, when an inspection target object sways while inspection is being performed by the eddy current testing device, a scratch is erroneously determined to be present on the inspection target object. In the case of an inspection target object for which wire shaking tends to occur at the time of transfer, such as the plated wire rod-intermediate body, noise which leads to erroneous determination of a scratch is easily caused. 
     In the manufacturing method of a plated wire rod according to the embodiment of the present disclosure, because skin-passing is performed on the plated wire rod precursor immediately before inspection by the eddy current testing device, the plated wire rod-intermediate body is firmly fixed by a die. Accordingly, wire shaking of the plated wire rod-intermediate body is not easily caused, and inspection by the eddy current testing device may be performed with higher accuracy. 
     —Camera Inspection Device— 
     By performing inspection of the plated wire rod-intermediate body using the camera inspection device, peeling-off of plating film  22  from the surface of plated wire rod-intermediate body  20   b  as shown in  FIG. 4  may be mainly detected. 
     Base material  21  is exposed to the surface of plated wire rod-intermediate body  20   b , at a part where plating film  22  is peeled off. Because wavelengths of light reflected by base material  21  and plating film  22  are different, presence/absence of a defect due to peeling-off of plating film  22  may be determined by radiating light on plated wire rod-intermediate body  20   b  and analyzing components of reflected light. 
     Specifically, first, light is radiated on the surface of plated wire rod-intermediate body  20   b  using an appropriate light source. Then, reflected light reflected by the surface of the plated wire rod-intermediate body is detected by an imaging mechanism. The imaging mechanism extracts an image of a plurality of color components from a captured image, and may inspect for presence/absence of a defect on the surface of the plated wire rod-intermediate body on the basis of an amount of difference in luminance between images of the plurality of color components. 
     The image of the plurality of color components extracted from the captured image may be a color image or a monochrome image. Furthermore, it is also possible to extract a plurality of color images and perform comparison on the basis of the amount of difference in luminance between the images of the plurality of color components, and also, to convert a color image into a monochrome (gray or binarized) image and perform a detection process. In the case of performing the detection process by converting the captured image into a monochrome image, the detection process may be performed by performing conversion into a gray image (a monochrome image) by extracting only brightness from the color image. 
     In the case of extracting a plurality of color images and performing the detection process on the basis of the amount of difference in luminance between the images of the plurality of color components (color inspection), peeling-off of plating film  22  over a relatively large area (an area with a diameter of 0.20 mm or more) may be detected. 
     Furthermore, in the case of converting a color image into a monochrome image and performing the detection process, peeling-off of plating film  22  over a relatively small area (an area with a diameter of 0.15 mm or more) may also be detected. 
     The plurality of color components that are extracted from the captured color image are preferably two or more among three components of red, green and blue, for example. In the case of extracting two or more among three primary colors of red, green and blue, a common device is allowed to be used, and simplification of a device is made possible. With respect to color comparison of red, green and blue in images, comparison and detection process are performed on a per-segment basis for each of hue, brightness and saturation. Moreover, in the case of performing processing using only two components, processing may be performed at a higher speed than in the case of performing processing using three components. 
     Additionally, in the inspection of the surface of plated wire rod-intermediate body  20   b , imaging may be performed by dividing a field of view in a planar direction into several parts (such as a center portion, corner portions and the like). Furthermore, in the case of performing imaging by dividing the field of view in the planar direction on the surface of plated wire rod-intermediate body  20   b , different processes may be performed on respective images (for example, the process based on a color image and the process based on a monochrome image described above). 
     The light source may be any light source as long as light can be radiated on the plated wire rod-intermediate body, and a coaxial epi-illumination or a bar light (a line light) may be used, for example. 
     The coaxial epi-illumination vertically radiates light toward the plated wire rod-intermediate body from the direction of a lens, and radiated light is vertically reflected by the surface of the plated wire rod-intermediate body and travels straight to the lens. For example, the coaxial epi-illumination may be made by using a semitransparent mirror as the lens. 
     If the coaxial epi-illumination is used in a case where the plated wire rod-intermediate body has a wide, flat shape as shown in  FIG. 2 , for example, it is difficult to uniformly radiate light on the surface of the plated wire rod-intermediate body, and color unevenness is possibly caused. Furthermore, specularly reflected light that is vertically reflected from the surface of the plated wire rod-intermediate body possibly causes halation. 
     Even in the case where the plated wire rod-intermediate body has a wide, flat shape, light may be uniformly radiated on the surface of the plated wire rod-intermediate body by using a bar light (a line light) as the light source. In the case of using a bar light as the light source, the bar light may be disposed such that light is obliquely radiated on the surface of the plated wire rod-intermediate body so that the specularly reflected light that causes halation is not generated. Then, diffusely reflected light may be detected and imaged, and presence/absence of a defect may be determined. 
     Furthermore, by capturing the specularly reflected light by tilting the camera at a same angle as the bar light, an edge component may be made to stand out. 
     As the light source, a white light emitting diode (LED) is preferably used. Because white light includes all visible light, all colors may be grayscaled (binarized) with the same level of lightness if the lightness (brightness) of the colors are the same. When the white LED is used in the case where the color of the plated wire rod-intermediate body includes multiple colors, a singular point may be captured without being affected by the colors. 
     In the case where the cross-section of the plated wire rod-intermediate body is a flat quadrangular shape, the camera inspection device preferably simultaneously inspects, using a mirror, for presence/absence of a defect for at least a pair of facing surfaces of the plated wire rod-intermediate body. In the present embodiment, a “quadrangle” is a concept including a substantially quadrangular shape without being limited to a geometric quadrangle. For example, a shape formed from a square or a rectangle by modifying its corners into arc shape are also included as the “quadrangle” described above. By simultaneously inspecting both of upper and lower surfaces of the plated wire rod-intermediate body using a mirror, an inspection time may be reduced, or a device configuration may be simplified. Furthermore, when a mirror is arranged to enable simultaneous inspection of both of left and right surfaces, in addition to the upper and lower surfaces, entire circumference of the plated wire rod-intermediate body may be simultaneously inspected. 
     (Removal Step) 
     The removal step is a step of removing a defect in the plated wire rod-intermediate body detected in the inspection step. When the removal step is performed, a plated wire rod as a finished product is obtained from the plated wire rod-intermediate body. A plated wire rod from which a metal terminal with small contact resistance to another member can be manufactured can be manufactured by removing a defect in the plated wire rod-intermediate body. The method of removing a defect in the plated wire rod-intermediate body is not particularly specified, and for example, a defective portion may be cut and removed by a cutter, a knife and the like. 
     Furthermore, plated wire rod-intermediate bodies that are cut may be connected by welding or the like after a defective portion is removed, or the plated wire rod-intermediate bodies may be wound around separate reels without being connected after the defective portion is removed. Furthermore, removal of a defect does not have to be performed immediately after the defect is detected, and a defective portion may be marked, and the defective portion may be cut and removed by detecting the defect at a desired stage, by performing image processing again, for example. 
     The plated wire rod that is obtained by the manufacturing method of a plated wire rod according to the embodiment of the present disclosure may be used for various uses other than a terminal for a connector, such as a conductor of an electric wire, a material for a spring, a wiring material for a communication appliance, a wiring material for a measurement appliance, a plated flat wire for a solar panel, a contact terminal, a connector, a relay, a chip component, an automotive electrical equipment, a component for a digital household appliance, an electronic component and the like. 
     &lt;Manufacturing Apparatus of Plated Wire Rod&gt; 
     An example structure of the manufacturing apparatus of a plated wire rod according to the embodiment of the present disclosure is schematically shown in  FIG. 1 . 
     As shown in  FIG. 1 , a manufacturing apparatus  10  of a plated wire rod according to the embodiment of the present disclosure includes a supply unit  15  that draws out plated wire rod precursor  20   a  from a reel around which plated wire rod precursor  20   a  is wound, a processing unit  13  that obtains plated wire rod-intermediate body  20   b  by performing skin-passing on plated wire rod precursor  20   a , an inspection unit that inspects for presence/absence of a defect in plated wire rod-intermediate body  20   b  using an eddy current testing device  11  and a camera inspection device  12 , and a removal mechanism  17  that obtains plated wire rod  20  by removing the defect in plated wire rod-intermediate body  20   b . According to an aspect of the present embodiment, the order of arrangement of eddy current testing device  11  and camera inspection device  12  is not particularly specified. Eddy current testing device  11  may be arranged in front, or camera inspection device  12  may be arranged in front. 
     It is sufficient if plated wire rod precursor  20   a  that is wound around a reel is prepared by the preparation step described in relation to the manufacturing method of a plated wire rod according to the embodiment of the present disclosure described above. Plated wire rod precursor  20   a  that is drawn out from supply unit  15  is sometimes fixed in a curved state, and thus, it is preferably straightened into a straight shape by a straightening roller unit  14 . 
     Processing unit  13  that obtains plated wire rod-intermediate body  20   b  by performing skin-passing on plated wire rod precursor  20   a  may be configured such that processing unit  13  is capable of processing plated wire rod precursor  20   a  into a desired shape using a die such as a diamond die, as described above with respect to the processing step. 
     Eddy current testing device  11  and camera inspection device  12  positioned on a downstream side of processing unit  13  may be configured in the same manner as those described in relation to the manufacturing method of a plated wire rod according to the embodiment of the present disclosure described above. Various defects on plated wire rod-intermediate body  20   b  may be detected by eddy current testing device  11  and camera inspection device  12 . 
     Manufacturing apparatus  10  of a plated wire rod according to the embodiment of the present disclosure includes removal mechanism  17  that is capable of removing various defects on plated wire rod-intermediate body  20   b  detected by eddy current testing device  11  and camera inspection device  12 . It is sufficient if removal mechanism  17  is configured to be capable of removing defects in plated wire rod-intermediate body  20   b , and removal mechanism  17  may be a cutter, a knife and the like, for example. 
     Plated wire rod  20  from which a defective portion is cut and removed by removal mechanism  17  passes through straightening roller unit  14  again and is wound around a reel by a winding unit  16 . Additionally, after the defective portion is cut, plated wire rods  20  may be connected by welding or the like, or may be wound around separate reels without being connected. 
     The description given above includes features additionally noted below. 
     (Note 1) 
     A manufacturing method of a plated wire rod, the method including: 
     preparing a plated wire rod including, on a surface of a conductive metal base material that is wire-drawn and that has a linear shape, a plating film of metal different from the conductive metal, 
     performing skin-passing on the plated wire rod using a die, 
     inspecting, after the skin-passing, for presence/absence of a defect in the plated wire rod using an eddy current testing device and a camera inspection device, and 
     removing the defect in the plated wire rod that is detected in the inspecting. 
     (Note 2) 
     The manufacturing method of a plated wire rod described in Note 1, where 
     the defect reflects light of a different wavelength from light that is reflected by the metal forming a surface of the plated wire rod, 
     the camera inspection device includes
         a light source that radiates light on the surface of the plated wire rod, and   an imaging mechanism that detects reflected light that is the light from the light source that is reflected by the surface of the plated wire rod, and   an image of a plurality of color components is extracted from an image captured by the imaging mechanism, and the defect is detected on a basis of an amount of difference in luminance between images of the plurality of color components.       

     (Note 3) 
     The manufacturing method of a plated wire rod described in Note 2, where the image of the plurality of color components that is extracted from the image captured is a color image or a monochrome image. 
     (Note 4) 
     The manufacturing method of a plated wire rod described in Note 2 or 3, where the plurality of color components that are extracted from the image captured are two or more among three components of red, blue and green. 
     (Note 5) 
     The manufacturing method of a plated wire rod described in any one of Notes 2 to 4, where the light source is a bar light. 
     (Note 6) 
     The manufacturing method of a plated wire rod described in any one of Notes 2 to 5, where the light source is a white LED. 
     (Note 7) 
     The manufacturing method of a plated wire rod described in any one of Notes 1 to 6, where 
     a cross-section of the plated wire rod is substantially quadrangular, and 
     the camera inspection device simultaneously inspects, using a mirror, for presence/absence of a defect for both surfaces of at least a pair of facing surfaces of the plated wire rod. 
     (Note 8) 
     A manufacturing apparatus of a plated wire rod, the apparatus including: 
     a supply unit that draws out a plated wire rod from a reel around which the plated wire rod is wound, the plated wire rod including, on a surface of a conductive metal base material having a linear shape, a plating layer of metal different from the conductive metal; 
     a processing unit that performs skin-passing on the plated wire rod using a die; 
     an inspection unit that inspects for presence/absence of a defect in the plated wire rod after the skin-passing, using an eddy current testing device and a camera inspection device; and 
     a removal mechanism that removes the defect in the plated wire rod. 
     EXAMPLES 
     Hereinafter, the present invention will be described in greater detail with reference to examples, but the examples are merely exemplary, and the manufacturing method and the like of a plated wire rod according to the present invention are not limited to the examples. The scope of the present invention is defined by the appended claims and is intended to include all modifications within the scope and meaning equivalent to those of the claims. 
     Example 1 
     —Preparation Step— 
     A flat wire rod of tough-pitch copper of 0.65 mm×1.05 mm that was molded by a die was used as a base material. A plated wire rod precursor was fabricated by applying underlying plating of copper on the surface of the base material, applying a tin plating after the underlying plating, and thus forming a plating film. 
     A copper (Cu) plating film of 1 μm was formed under plating conditions for copper plating of copper sulfate bath (copper sulfate 250 g/L, sulfuric acid 40 g/L), a liquid temperature of 25° C., and a current density of 5 A/dm 2 . 
     A tin (Sn) plating film of 1.3 μm was formed under plating conditions for tin plating of tin sulfate bath (tin sulfate 80 g/L, sulfuric acid 80 g/L, additive agent 10 g/L), a liquid temperature of 25° C., and a current density of 5 A/dm 2 . 
     A plated wire rod was fabricated using manufacturing apparatus  10  of a plated wire rod shown in  FIG. 1 . 
     —Processing Step— 
     A reflow process was performed on a plated wire rod precursor prepared in the preparation step described above at 250° C. for 3 minutes. Then, skin-passing was performed on the plated wire rod precursor using a diamond die, and the wire rod precursor was drawn to 0.64 mm×1.5 mm. That is, a plated wire rod-intermediate body was obtained from the plated wire rod precursor by performing the processing step. 
     —Inspection Step— 
     Subsequent to skin-passing, presence/absence of scratches formed on the surface of the plated wire rod-intermediate body and of impurities deposited on the surface of the plated wire rod-intermediate body was inspected using the eddy current testing device. 
     Subsequent to the inspection by the eddy current testing device, inspection was performed using the camera inspection device, for presence/absence of peeling-off of the plating film from the surface of the plated wire rod-intermediate body. Observation of the surface of the plated wire rod-intermediate body was performed by dividing the field of view on the surface of the plated wire rod-intermediate body into a center portion and corner portions at both ends. A coaxial epi-illumination of white LED was used as the light source of the camera inspection device. Then, specularly reflected light was detected and imaged by the imaging mechanism. Furthermore, presence/absence of a defect was inspected using a mirror, simultaneously for both of an upper surface and a lower surface of the plated wire rod-intermediate body. 
     Extracting a red component and a blue component from an image captured by the imaging mechanism and performing comparison on the basis of the amount of difference in luminance between images of the color components, and converting a color image into a monochrome (gray or binarized) image and performing a detection process were both performed. 
     —Removal Step— 
     A defective portion such as a scratch or peeling-off of the plating film on the plated wire rod-intermediate body detected in the inspection step was cut and removed by a cutter, and a plated wire rod No. 1 from which the defective portion was removed was obtained. 
     Example 2 
     A plated wire rod No. 2 was fabricated in the same manner as in Example 1, except that the light source of the camera inspection device in the inspection step in Example 1 was configured as follows. 
     A bar light of white LED was used as the light source of the camera inspection device, and light was obliquely radiated on the surface of the plated wire rod-intermediate body. Then, diffusely reflected light was detected and imaged by the imaging mechanism. 
     Comparative Example 1 
     A plated wire rod No. 3 was fabricated in the same manner as in Example 1, except that the processing step in Example 1 was not performed, and only inspection by the eddy current testing device was performed in the inspection step and inspection by the camera inspection device was not performed. 
     Comparative Example 2 
     A plated wire rod No. 4 was fabricated in the same manner as in Example 1, except that only inspection by the eddy current testing device was performed in the inspection step in Example 1 and inspection by the camera inspection device was not performed. 
     Comparative Example 3 
     A plated wire rod No. 5 was fabricated in the same manner as in Example 1, except that the processing step in Example 1 was not performed. 
     Comparative Example 4 
     A plated wire rod No. 6 was fabricated in the same manner as in Example 2, except that the processing step in Example 2 was not performed. 
     &lt;Evaluation Result&gt; 
     Types of defects that were able to be detected in the process of fabricating plated wire rods Nos. 1 to 6 are summarized in Table 1. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Plated  
                 Type (Size) of Defect 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Wire  
                   
                   
                   
                   
                   
                 Foreign Matter 
                 Foreign Matter 
                   
               
               
                 Rod  
                 Failed Plating 1  
                 Failed Plating 2 
                 Streak 
                 Dent/Scratch 1 
                 Dent/Scratch 2 
                 Deposition 1 
                 Deposition 2 
                 Fogging 
               
               
                 No. 
                 (&gt;100 μm) 
                 (&gt;100 μm) 
                 (&lt;1 μm) 
                 (5 μm) 
                 (30 μm) 
                 (30 μm) 
                 (30 μm) 
                 (5 μm) 
               
               
                   
               
               
                 1 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
               
               
                 2 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
               
               
                 3 
                 Non-Detectable 
                 Non-Detectable 
                 Non-Detectable 
                 Non-Detectable 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
               
               
                 4 
                 Detected 
                 Detected 
                 Non-Detectable 
                 Non-Detectable 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
               
               
                 5 
                 Non-Detectable 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Non-Detectable 
                 Detected 
                 Non-Detectable 
               
               
                 6 
                 Non-Detectable 
                 Detected 
                 Detected 
                 Detected 
                 Detected 
                 Non-Detectable 
                 Detected 
                 Non-Detectable 
               
               
                   
               
            
           
         
       
     
     Details of the types of defects shown in Table 1 are as follows. 
     —Failed Plating  1   
     A state where adhesion between plating film  22  and base material  21  is poor, and base material  21  is exposed when plated wire rod  20  is bent. 
     —Failed Plating  2   
     A state where plating film  22  is not formed, and base material  21  is exposed. 
     —Streak 
     A state where a thin, line-shaped dent (of a thickness equal to or smaller than that of plating film  22 ) is present on the surface of plating film  22 . 
     —Dent/Scratch  1   
     A state where a dent or a scratch is present on the surface of plating film  22 . 
     —Dent/Scratch  2   
     A state where a dent or a scratch is present on the surface of plating film  22 . 
     —Foreign Matter Deposition  1   
     A state where plating residue is deposited on the surface of plating film  22  (a case where a deposited matter is of a same color as plating film  22 ). 
     —Foreign Matter Deposition  2   
     A state where a matter of a different plating color is deposited on the surface of plating film  22 . 
     —Fogging 
     Copper fogging on base material  21  (a state where crack is present on base material  21 , and a plating film is formed on the surface of the crack). 
     As shown in Table 1, with the manufacturing methods of plated wire rods in Example 1 and Example 2, all types of defects on plated wire rod  20  (plated wire rod-intermediate body  20   b ) were able to be detected, and a high-quality plated wire rod with few defects was obtained by removing the defects. 
     REFERENCE SIGNS LIST 
       10  manufacturing apparatus of plated wire rod,  11  eddy current testing device,  12  camera inspection device,  13  processing unit,  14  straightening roller unit,  15  supply unit,  16  winding unit,  17  removal mechanism,  20  plated wire rod,  20   a  plated wire rod precursor,  20   b  plated wire rod-intermediate body,  21  base material,  22  plating film