Wire inspection device and wire inspection method

Abstract

To provide a wire inspection device and wire inspection method that can improve the accuracy of detecting irregularities. [Solution] A wire inspection device 30 for inspecting irregularities occurring on an insulated wire CW, which is an insulated wire CW in which resin is extruded onto a conductor, or a sheathed wire CW in which resin is extruded onto a twisted insulated core, comprising: an irradiation unit 31 that irradiates the insulated wire CW with light along the longitudinal direction of the insulated wire CW; and a sensor 32 provided in a direction intersecting the longitudinal direction, which receives reflected light generated when the light irradiated by the irradiation unit 31 is reflected by irregularities on the insulated wire CW.

Description

Technical Field

[0001] The present invention relates to a wire inspection apparatus and a wire inspection method.

Background Art

[0002] Conventionally, when manufacturing a wire, it is known to extrude and coat an insulating resin on a conductor and a sheath resin on an insulating wire core (see Patent Document 1). It is also known that unevenness may be formed on the coating surface of such a coated wire unintentionally (see Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When unevenness occurs on a coated wire as described in Patent Document 2, it may become impossible to satisfy the wire specifications, so inspection is necessary. FIG. 8 is a schematic view showing a part of a wire inspection apparatus according to a comparative example. The wire inspection apparatus shown in FIG. 8 has a light source 100 that irradiates a wire with laser light from a direction intersecting the longitudinal direction of the coated wire CW. The wire inspection apparatus also includes a light receiving unit 200 on the side opposite to the irradiation side. When there is no unevenness on the coated wire CW, as shown in FIG. 8(a), the light receiving unit 200 is in a light receiving state of laser light assumed in advance. On the other hand, when there is unevenness on the coated wire CW, as shown in FIG. 8(b), the light receiving state of the laser light changes by lengths L1 and L2 corresponding to the unevenness in the light receiving unit 200. Thereby, the wire inspection apparatus according to the comparative example detects the unevenness of the coated wire.

[0005] However, such wire inspection devices are prone to false detections when vibrations (wire wobble) occur or when inspecting the appearance of sheathed wires (including cables) that are twisted together and then extruded, as changes in the light-receiving state corresponding to lengths L1 and L2 occur. Therefore, the wire inspection device in the comparative example detects irregularities based on changes in the light-receiving state that are greater than length L1, in order to prevent false detections. Consequently, the wire inspection device in the comparative example can only inspect larger irregularities, and finer irregularities require visual inspection or sensory inspection by inspectors.

[0006] The present invention has been made to solve these problems, and its objective is to provide a wire inspection device and wire inspection method that can improve the accuracy of detecting irregularities. [Means for solving the problem]

[0007] The wire inspection device according to the present invention is a wire inspection device for inspecting irregularities occurring on an insulated wire, which is an insulated wire in which resin is extruded onto a conductor, or a sheathed wire (cable) in which resin is extruded onto a twisted insulated core, and comprises: an irradiation means for irradiating the insulated wire with light along the longitudinal direction of the insulated wire; and a sensor provided in a direction intersecting the longitudinal direction for receiving reflected light generated when the light irradiated by the irradiation means is reflected by irregularities on the insulated wire.

[0008] The wire inspection method according to the present invention is a wire inspection method for inspecting irregularities occurring on an insulated wire, which is an insulated wire in which resin is extruded onto a conductor, or a sheathed wire (cable) in which resin is extruded onto a twisted insulated core, and comprises an irradiation step of irradiating the insulated wire with light along the longitudinal direction of the insulated wire, and a light receiving step of receiving reflected light generated when the light irradiated in the irradiation step is reflected by irregularities on the insulated wire with a sensor provided in a direction intersecting the longitudinal direction. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a wire inspection device and the like that can improve the accuracy of detecting irregularities. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing a wire manufacturing system including a wire inspection device according to this embodiment. [Figure 2] Figure 1 is a diagram showing the detailed configuration of the wire inspection device, where (a) is a schematic perspective view, (b) shows the back of some components, and (c) shows the front of some components. [Figure 3] This schematic diagram shows how a sensor receives reflected light when there are no irregularities on the insulated wire, with (a) showing a side view and (b) showing an example of an image captured by the sensor. [Figure 4] This schematic diagram shows how a sensor receives reflected light when there are irregularities on the insulated wire, with (a) showing a side view and (b) showing an example of an image captured by the sensor. [Figure 5] This is a schematic diagram showing what happens when light is shone on a covered electric wire from two directions, where (a) shows the view from the side and (b) shows an example of an image captured by a sensor. [Figure 6] This is a schematic diagram showing what happens when light is shone on a coated wire from the tip side, with (a) showing a view from the side and (b) showing an example of an image captured by the sensor. [Figure 7] Figure 2 is a side view showing another example of the lighting unit. [Figure 8] This is a schematic diagram showing a part of the wire inspection device related to the comparative example, where (a) shows the case where the insulated wire is not uneven, and (b) shows the case where the insulated wire is uneven. [Modes for carrying out the invention]

[0011] The present invention will be described below in accordance with preferred embodiments. It should be noted that the present invention is not limited to the embodiments shown below, and can be modified as appropriate without departing from the spirit of the invention. Furthermore, in the embodiments shown below, some illustrations and descriptions of certain components are omitted. It goes without saying that, regarding the details of the omitted technologies, publicly known or well-known technologies are applied as appropriate, to the extent that they do not contradict the content described below.

[0012] Figure 1 is a schematic diagram showing a wire manufacturing system including a wire inspection device according to this embodiment. The wire manufacturing system 1 comprises an extruder 10, a cooling tank 20, a wire inspection device 30, a marking device 40, and a winding machine 50. The extruder 10, cooling tank 20, wire inspection device 30, and marking device 40 manufacture marked wires MW while conveying conductors C or insulated wire cores C or insulated coated wires CW or sheathed coated wires CW. The winding machine 50 winds up the marked wires MW.

[0013] The extruder 10 manufactures insulated wire CW or sheathed wire CW by extruding insulating resin or sheathed resin onto a conductor C or a twisted insulating wire core C. The extruder 10 extrudes molten resin and passes it through a die of a predetermined shape to manufacture insulated wire CW or sheathed wire CW. In the following description, both insulated wire CW and sheathed wire CW will be simply referred to as insulated wire CW.

[0014] The cooling tank 20 is composed of, for example, a water tank and cools the insulated electric wire CW extruded from the extruder 10 with cooling water. This cooling tank 20 is composed of a water tank that is long in the direction of transport of the insulated electric wire CW, and introduces the insulated electric wire CW when the insulation has not yet fully hardened, and cools the insulated electric wire CW as it passes through the water tank to fully harden the insulation.

[0015] The wire inspection device 30 inspects unevenness generated on the coating of the coated wire CW. FIG. 2 is a configuration diagram showing the details of the wire inspection device 30 shown in FIG. 1, (a) shows a schematic perspective view, (b) shows the back surface of a partial configuration, and (c) shows the front surface of a partial configuration.

[0016] As shown in FIG. 2, the wire inspection device 30 includes an irradiation unit (irradiation means) 31, a sensor 32, and a diagnosis unit 33, and can inspect unevenness generated on the coated wire CW while transporting the coated wire CW.

[0017] As shown in FIG. 2(a), the irradiation unit 31 irradiates light onto the coated wire CW. The irradiation unit 31 irradiates light along the transport direction (longitudinal direction) of the coated wire CW. More specifically, the wire inspection device 30 has an insertion plate 34 in which a through hole TH is formed. The coated wire CW is transported in a state of passing through the through hole TH of the insertion plate 34. As shown in FIG. 2(a), the irradiation unit 31 is, for example, supported by the insertion plate 34 and has a ring shape. Such a ring-shaped illumination unit 31 is provided around the through hole TH of the insertion plate 34, and it is preferable that the coated wire CW is transported inside the ring-shaped illumination unit 31. Since the illumination unit 31 is ring-shaped in this way, it can appropriately illuminate the outer peripheral portion of the coated wire CW on the cylindrical shape.

[0018] The sensor 32 is provided in a direction intersecting the longitudinal direction, and receives the reflected light generated by the light irradiated by the irradiation unit 31 being reflected by the unevenness on the coated wire CW. In the present embodiment, the sensor 32 is composed of four cameras arranged at 90° intervals centered on the longitudinal direction. Note that the sensor 32 is not limited to four, and may be eight cameras arranged at 45° intervals, and the number is not limited. Further, the sensor 32 may not be limited to a camera, and may simply be an illuminance sensor capable of measuring the intensity of light.

[0019] As shown in FIGS. 2(b) and 2(c), the sensor 32 includes an imaging unit 32a formed on the back surface and a display unit 32b formed on the front surface. The imaging unit 32a images the entire covered electric wire CW to receive the reflected light generated by reflection due to the unevenness on the covered electric wire CW. The display unit 32b displays an image or the like obtained by imaging by the imaging unit 32a. Further, the display unit 32b can also display the sensor value obtained by digitizing the image or the like obtained by imaging.

[0020] FIGS. 3 and 4 are schematic views showing the state of receiving the reflected light by the sensor 32 shown in FIG. 2, where (a) shows the state from the side and (b) shows an example of the captured image of the sensor 32. First, as shown in FIG. 3(a), the light from the irradiation unit 31 illuminates the surface of the covered electric wire CW. Here, when there are no unevennesses formed on the covered electric wire CW, as shown in FIG. 3(b), the sensor 32 cannot observe the reflected light based on the unevennesses. That is, as shown in FIG. 3, the sensor 32 is provided outside both the range where the light from the irradiation unit 31 directly enters and the irradiation range of the light that is specularly reflected from the irradiation unit 31 to the covered electric wire CW without unevennesses.

[0021] On the other hand, when an unevenness U is formed on the covered electric wire CW, as shown in FIG. 4(a), the unevenness U forms a reflecting surface RS that reflects the light from the irradiation unit 31 toward the sensor 32 side. This reflecting surface RS is formed with a certain area on the base side (the irradiation unit 31 side) of the unevenness U (especially the convex part), as shown in FIG. 4(b). Therefore, even if the sensor 32 is formed outside both the above-mentioned ranges, it receives strong light (reflected light) at this reflecting surface RS. The circular broken line shown in FIG. 4(b) indicates only the convex part of the unevenness U. The same applies to FIGS. 5(b) and 6(c) described later.

[0022] The diagnostic unit 33 shown in Figure 2(a) diagnoses whether irregularities U are formed on the surface of the insulated wire CW based on whether or not reflected light from such a reflective surface RS is received by the sensor 32. When reflected light is received, for example, the imaging unit 32a obtains an image that is whitened or blackened at the location of the reflected light. Therefore, the diagnostic unit 33 diagnoses that irregularities U are formed on the surface of the insulated wire CW when it measures the light corresponding to the reflective surface RS in a region above a predetermined threshold, and for example, the whitened or blackened value is above the predetermined threshold. Also, if the sensor 32 is an illuminance sensor, the sensor value will increase due to reflected light. Therefore, the diagnostic unit 33 diagnoses that irregularities U are formed on the surface of the insulated wire CW when it detects an increase in the sensor value above a predetermined threshold.

[0023] In this embodiment, it is preferable that the irradiation unit 31 irradiates light from only one direction along the longitudinal direction of the insulated wire CW. Figure 5 is a schematic diagram showing the situation when light is irradiated from two directions to the insulated wire CW, where (a) shows the view from the side and (b) shows an example of an image captured by the sensor 32.

[0024] As shown in Figure 5(a), when light is irradiated from two directions along the insulated wire CW, the insulated wire CW is irradiated by two irradiating units 31. In this case, the irradiated light becomes too strong compared to when there is only one irradiating unit 31. As a result, depending on the performance of the sensor 32, the sensor 32 may malfunction, such as the captured image becoming completely white. Therefore, to avoid such a situation, when irradiating from two directions, it is necessary to weaken the light from each irradiating unit 31. However, if the irradiated light is weakened, the amount of light reflected by the uneven surface U and received by the sensor 32 also decreases. That is, as shown in Figures 5(a) and 5(b), the values ​​that function as reflective surfaces RS1 and RS2 become smaller than in the example shown in Figure 4. Here, since the two irradiating units 31 are irradiating from two directions, reflective surfaces RS1 and RS2 are formed on both the tip and base sides of the uneven surface U, and it would seem that the uneven surface U would be easier to detect by both reflective surfaces RS1 and RS2. However, the inventors of this case have found through their research that when light is irradiated from two directions by the two irradiation units 31, the sum of the reflective surfaces RS1 and RS2 is smaller than the reflective surface RS shown in Figure 4. Consequently, the sensor 32 becomes less able to capture reflected light than in the example shown in Figure 4, leading to a decrease in the detection accuracy of the unevenness U. Therefore, it is preferable for the irradiation unit 31 to irradiate light from only one direction along the longitudinal direction of the insulated wire CW.

[0025] Furthermore, in this embodiment, when the extrusion direction of the insulated wire CW is towards the tip side of the insulated wire CW, it is preferable that the irradiation unit 31 irradiates light in a direction from the root side to the tip side of the insulated wire CW. Figure 6 is a schematic diagram showing the situation when light is irradiated onto the insulated wire CW from the tip side, where (a) shows the view from the side and (b) shows an example of an image captured by the sensor 32.

[0026] In extrusion molding, the surface irregularities U tend to form with convex portions first, followed by concave portions. That is, as shown in Figure 4(a), the irregularities U are composed of convex portions at the tip and concave portions at the base. Therefore, when light is shone from the base to the tip of the insulated wire CW, reflected light is generated on the wide reflective surface RS extending from the concave portion to the convex portion. In contrast, as shown in Figure 6(a), when light is shone from the tip to the base of the insulated wire CW, reflected light is generated on the small reflective surface RS3 formed only by the convex portion without the concave portion. For these reasons, it is preferable for the irradiation unit 31 to irradiate the insulated wire CW in the direction from the base to the tip.

[0027] Refer to Figure 1 again. The marking device 40 marks the insulated wire CW to make it a marked wire MW. This marking device 40 is installed downstream of the wire inspection device 30 in the transport direction so that it marks the insulated wire CW after inspection by the wire inspection device 30. Depending on the color of the marking, light may reflect and it may be mistakenly identified as a bump U. Therefore, by having the marking device 40 mark after inspection, the possibility of the wire inspection device 30 misdetecting a bump U can be reduced.

[0028] Figure 7 is a side view showing another example of the illumination unit 31 shown in Figure 2. As shown in Figure 7, when viewed from the side, it is preferable that the optical axis Ax of the illumination unit 31 is directed toward the insulated wire CW. In this case, the optical axis Ax is directed toward the insulated wire CW at an appropriate angle θ with respect to the longitudinal direction of the insulated wire CW. This allows the light from the illumination unit 31 to be irradiated toward the insulated wire CW more appropriately.

[0029] Here, the illumination unit 31 may be attached to the insertion plate 34 such that the optical axis Ax itself faces the insulated wire CW side, or the illumination unit 31 may be equipped with a lens member 31a, and the optical axis Ax of the emitted light may be directed towards the insulated wire CW side by the lens member 31a.

[0030] In the configuration shown in Figure 7, the sensor 32 is positioned outside both the range where light from the irradiation unit 31 is directly incident and the irradiation range of light that is specularly reflected by the insulated wire CW, which does not have any irregularities U.

[0031] In addition, if the sensor 32 is configured to have an imaging unit 32a (see Figure 2), it is preferable to include the intersection portion CR of light from the illumination unit 31 within the imaging range of the imaging unit 32a, as shown in Figure 7. This makes it easier to detect surface irregularities U.

[0032] Next, a method for manufacturing a marked electric wire MW, including an electric wire inspection method according to this embodiment, will be described. First, a long conductor C or insulating wire core C is supplied to the extruder 10. The extruder 10 coats the conductor C or insulating wire core C with molten resin and outputs a coated electric wire CW. The output coated electric wire CW is supplied to a cooling tank 20 and cooled while being transported in the cooling tank 20. As a result, the resin on the conductor C and insulating wire core C hardens appropriately.

[0033] The insulated and sheathed coated wire CW is supplied to the wire inspection device 30. The wire inspection device 30 inspects the coated wire CW while it is being transported, without stopping its transport. During this process, the irradiation unit 31 of the wire inspection device 30 irradiates light in one direction from the root side to the tip side of the coated wire CW (irradiation step). If the coated wire CW has irregularities U, the sensor 32 receives reflected light from the reflective surface RS of the irregularities U (light receiving step). On the other hand, since the sensor 32 is located outside the ranges of both of the above, it does not receive such reflected light if the coated wire CW does not have irregularities U. The diagnostic unit 33 determines the presence or absence of irregularities U based on the light receiving state of the sensor 32 (imported image, sensor values, etc.). For example, the diagnostic unit 33 diagnoses that irregularities U are formed on the surface of the coated wire CW when reflected light corresponding to the reflective surface RS is observed in a region above a predetermined threshold.

[0034] Subsequently, the insulated wire CW is supplied to the marking device 40, which then applies the predetermined markings. In particular, the marking by the marking device 40 is performed after the inspection process (including the irradiation process and the light receiving process) by the wire inspection device 30. Therefore, misdetection of unevenness U due to reflected light from the markings is prevented. After marking, the marked wire MW is wound up by the winding machine 50.

[0035] Furthermore, the wire inspection device 30 may be configured to include a display device instead of the diagnostic unit 33, allowing the inspector to determine the presence or absence of irregularities U by referring to the display content of the display device. In this case as well, the accuracy of detecting irregularities U can be improved compared to visually inspecting or sensory inspecting the entire insulated wire CW. In addition, if the diagnostic unit 33 diagnoses the presence of irregularities U, that is, if irregularities U are detected on the surface of the insulated wire CW, the wire inspection device 30 may stop transporting the insulated wire CW, or it may provide a predetermined notification or output. Moreover, if irregularities U are detected on the surface of the insulated wire CW, the wire inspection device 30 may transmit information to the subsequent marking device 40 and apply a mark indicating the presence of irregularities U at the location of the irregularities U or within a predetermined length from the location of the irregularities U.

[0036] In this way, the wire inspection device 30 and wire inspection method according to this embodiment irradiate light along the insulated wire CW in the longitudinal direction of the insulated wire CW. Therefore, even if vibration occurs in the insulated wire CW, if there are no irregularities U on the surface of the insulated wire CW and it is smooth, reflected light toward the sensor 32 will be less likely to occur. Similarly, with respect to sheathed insulated wire CW, due to the twist pitch, if there are no irregularities U on the surface of the sheathed insulated wire CW and it is smooth, reflected light toward the sensor 32 will be less likely to occur. Even if some light is reflected toward the sensor 32 due to the effect of twisting, the amount of light is small and can be addressed by adjusting the sensitivity of the sensor 32. In this way, the wire inspection device 30, etc., irradiates light along the insulated wire CW in the longitudinal direction of the insulated wire CW and detects the reflected light with a sensor 32 provided in the intersecting direction, thereby reducing the possibility of false detection. Furthermore, since the possibility of false detection can be reduced, the wire inspection device 30, etc., does not need to be set to detect only large irregularities U. Therefore, it is possible to provide a wire inspection device 30 and a wire inspection method that can improve the detection accuracy of uneven surfaces U.

[0037] Furthermore, the wire inspection device 30 according to this embodiment irradiates light from only one direction along the insulated wire CW. If light is irradiated from two directions along the insulated wire CW, the irradiated light may become too strong, causing the entire wire to whiten, making detection by the sensor 32 difficult. For this reason, when irradiating light from two directions, it is necessary to weaken each irradiated light. However, if the irradiated light is weakened, the sensor 32 will have difficulty detecting the reflected light. Therefore, by irradiating light from one direction along the insulated wire CW, it is possible to provide a wire inspection device 30 that can avoid such problems and improve the detection accuracy of unevenness U.

[0038] Furthermore, the wire inspection device 30 according to this embodiment irradiates light from the base side to the tip side of the insulated wire CW. In extrusion molding, the irregularities U are formed by first creating convex portions followed by concave portions. Therefore, when light is irradiated from the base side to the tip side of the insulated wire CW, reflected light is generated over a wide range of values ​​from concave portions to convex portions. Thus, it is possible to provide a wire inspection device 30 that can further improve the detection accuracy of irregularities U.

[0039] Furthermore, the illumination unit 31 has its optical axis Ax tilted toward the insulated wire CW side with respect to the longitudinal direction. This allows for more appropriate illumination of the insulated wire CW from the illumination unit 31, and provides a wire inspection device 30 that can further improve the detection accuracy of irregularities U.

[0040] Furthermore, in the wire inspection method according to this embodiment, inspection steps such as irradiating the insulated wire CW with light and receiving reflected light are performed prior to the marking step. Therefore, the possibility of mistakenly identifying markings formed on the insulated wire CW as reflected light can be reduced, and a wire inspection method that can further improve the detection accuracy of irregularities U can be provided.

[0041] Although the present invention has been described above based on embodiments, the present invention is not limited to the above embodiments, and modifications may be made without departing from the spirit of the invention, and other technologies may be combined as appropriate to the extent possible. Furthermore, publicly known or well-known technologies may be combined as appropriate to the extent possible.

[0042] For example, in the above embodiment, the illumination unit 31 is composed of a ring-shaped LED (Light Emitting Diode), but it is not limited to a ring shape and may be composed of multiple LEDs arranged in a ring. Also, if possible, the illumination unit 31 may be a single LED. Furthermore, the illumination unit 31 may be composed of other light sources, not just LEDs, as long as the light output is sufficient.

[0043] Furthermore, in this embodiment, the position of the sensor 32 is not particularly limited, as long as it is provided in a position that can receive reflected light even if it intersects the longitudinal direction of the insulated wire CW. However, when the sensor 32 is the imaging unit 32a, it is preferable that the optical axis and the orthogonal axis of the sensor surface be provided at an angular position that is substantially orthogonal to the longitudinal direction (for example, a position that is 80° or more and 100° or less). [Explanation of Symbols]

[0044] 30: Wire inspection device 31: Irradiation part (irradiation means) 32: Sensor Ax: Optical axis C: Conductor, insulated core CW: Insulated wire, insulated wire, sheathed wire U: Unevenness θ: Angle

Claims

1. A wire inspection device for inspecting irregularities occurring in an insulated wire, which is an insulated wire in which resin is extruded onto a conductor, or a sheathed wire in which resin is extruded onto a twisted insulated core, An irradiation means for irradiating the insulated wire with light along the longitudinal direction of the insulated wire, A sensor provided in a direction intersecting the longitudinal direction, which receives reflected light generated when light irradiated by the irradiation means is reflected by irregularities on the insulated wire, A wire inspection device characterized by being equipped with the following features.

2. The irradiation means irradiates light from only one direction along the longitudinal direction of the insulated wire. The wire inspection device according to claim 1.

3. When the extrusion direction of the insulated wire is towards the tip of the insulated wire, the irradiation means irradiates light from the base of the insulated wire toward the tip. The wire inspection device according to feature 2.

4. The irradiation means has an optical axis tilted toward the insulated wire with respect to the longitudinal direction. The wire inspection device according to claim 1.

5. A wire inspection method for inspecting irregularities occurring in an insulated wire, which is an insulated wire in which resin is extruded onto a conductor, or a sheathed wire in which resin is extruded onto a twisted insulated core, A process of irradiating the insulated wire with light along the longitudinal direction of the insulated wire, A light receiving step is performed in which the reflected light generated when the light irradiated in the irradiation step is reflected by the irregularities on the insulated wire is received by a sensor provided in a direction intersecting the longitudinal direction, A method for inspecting electric wires, characterized by comprising the following features.

6. The irradiation step and the light receiving step are performed prior to the marking step, in which markings are applied to the insulated wire. The wire inspection method according to feature 5.

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