JP2006242737A - Internal defect inspection method and device of tire sidewall part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detection accuracy, while avoiding misdetections, when inspecting internal defects of an inspection tire 11. <P>SOLUTION: A sidewall part 21 of the inspection tire 11 is divided into a plurality of concentric ring domains, and threshold processing is performed by a detection means 40 to image data of a radiation transmitted through each ring domain of the rotating inspection tire 11. Hereby, the threshold can be set at the optimum value in each ring domain, and consequently the internal defect can be detected, while preventing both misdetections and detection mistakes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to an inspection method and apparatus for inspecting internal defects such as foreign matter contamination in a side wall portion of an inspection tire.

As a conventional internal defect inspection method / apparatus for a tire side wall, for example, the one described in Patent Document 1 below is known.
JP 2003-294655 A

  This is an X-ray irradiation means for the entire side wall of an inspection tire that is driven by a rotating means and rotates about a central axis, or a horizontally placed inspection tire that is conveyed linearly by a conveyor. The X-ray image transmitted through the side wall is photographed by the X-ray line sensor, and then the normal tire X-ray image stored in advance by the detection means and the X-ray line sensor The X-ray image is compared with the X-ray image to detect an internal defect in the side wall. The detection of the internal defect is not limited to the method described above, and a single threshold value is set in advance for the entire side wall portion, and the setting is performed on the X-ray image from the X-ray line sensor by the detecting means. It can also be performed by applying threshold processing based on the threshold value.

    However, as described above, the threshold value processing based on a single threshold value to detect internal defects in the tire side wall portion is erroneous if the threshold value is lowered to improve detection accuracy. On the other hand, in order to avoid erroneous detection, the detection accuracy has to be lowered by increasing the threshold value. Here, as the performance of tires has improved in recent years, the internal structure of tires, particularly the side wall portions for detecting internal defects, has become complicated, and materials, rubber gauges, etc. have become greatly different at each position. In order to avoid detection, the threshold value must be set higher than the conventional value, and as a result, there is a problem that the detection accuracy is lower than the conventional value (detection errors are increased more than the conventional value). It was.

  An object of the present invention is to provide a method and an apparatus for inspecting an internal defect of a tire side wall that can improve detection accuracy while avoiding erroneous detection.

    The purpose of this is to first partition the inspection tire side wall located between the extension line of the inner surface of the tread portion and the bead core into a plurality of concentric ring-shaped regions, On the other hand, the radiation source emits radiation, and the radiation that has passed through each ring-shaped region of the side wall is imaged by an imager. Thereafter, the detection unit uses different values for each ring-shaped region with respect to image data from the imager. It can be achieved by an internal defect inspection method for a tire side wall portion that performs threshold processing based on the threshold value set to detect the internal defects in the ring-shaped region,

  Second, an internal defect inspection device for a tire side wall portion for inspecting an internal defect of a side wall portion of an inspection tire located between an extension line of the inner surface of the tread portion and a bead core, the side wall portion of the inspection tire having a concentric shape A radiation source for irradiating the side wall of the inspection tire with radiation, an imager for imaging the radiation transmitted through each ring-shaped region of the side wall, and an imager Of the tire side wall provided with detection means for performing threshold processing on the image data from the image data based on threshold values set to different values for each ring-shaped region and detecting internal defects in the ring-shaped region This can be achieved by an internal defect inspection device.

  In this invention, while dividing the side wall of the inspection tire into a plurality of concentric ring-shaped regions, the radiation transmitted through each ring-shaped region of the side wall of the inspection tire was imaged and obtained by imaging Although internal defects are detected by performing threshold processing on image data, the aforementioned threshold value can be set to a different optimum value for each ring-shaped region. An internal defect in the region can be detected while preventing both erroneous detection and erroneous detection, thereby improving detection accuracy while easily avoiding erroneous detection in the entire sidewall portion of the inspection tire.

Moreover, if comprised as described in Claim 2, detection accuracy can be improved effectively, without making it excessively complicated.
Furthermore, if it comprises as described in Claim 3, the internal defect of a test | inspection tire can be detected with high precision.
Moreover, if comprised as described in Claim 4, the internal defect of a test | inspection tire can be detected with high efficiency.
Furthermore, if comprised as described in Claim 6, the internal defect detection of the whole side wall part can be rapidly performed only by rotating an inspection tire 1 time.
Moreover, if it comprises as described in Claim 7, while being able to simplify the structure of the whole apparatus, manufacturing cost can be made cheap.

Embodiment 1 of the present invention will be described below with reference to the drawings.
1 and 2, reference numeral 11 denotes a pneumatic tire for inspecting internal defects, that is, an inspection tire. The inspection tire 11 includes a pair of bead portions 14 each embedded with a bead core 13 with a filler 12, and these beads. Side wall portions 15 each extending substantially outward in the radial direction from the portion 14, and a substantially cylindrical tread portion 16 that connects the outer ends in the radial direction of the sidewall portions 15 are provided.

  The inspection tire 11 has a carcass layer 17 extending between the bead cores 13 in a substantially toroidal shape to reinforce the sidewall portions 15 and the tread portions 16, and both ends of the carcass layer 17 are formed on the bead core 13. A folded portion 18 is formed that is folded around from the axially inner side toward the axially outer side. A belt layer 19 is disposed outside the carcass layer 17 in the radial direction, and a tread 20 is disposed outside the belt layer 19 in the radial direction.

  21 is a side wall portion located between the bead core 13 and the extended game E on the inner surface of the tread portion 16, and this side wall portion 21 is a concentric ring shape, for example, a ring shape partitioned into four substantially equal widths. It consists of regions 22a, 22b, 22c, and 22d. Here, the ring-shaped regions 22a, 22b, 22c, and 22d are sequentially arranged from the bead core 13 toward the tread portion 16, and as a result, the ring-shaped region 22a has a folded portion 18 and a thick portion of the filler 12. Is located in the ring-shaped region 22b, the thin-walled portion near the tire maximum width position is located in the ring-shaped region 22c, and the ring-shaped region 22d is disposed in the ring-shaped region 22d. Both end portions in the width direction of the tread 20 are located, and the rubber gauge gradually increases in thickness toward the tread portion 16 in the ring-shaped region 22d.

  Reference numeral 25 denotes a moving frame in which a disk-like support base 26 is attached to the front end. The moving frame 25 can be moved in the vertical direction and the horizontal direction by a moving mechanism (not shown). A plurality of gripping rollers 27 extending downward are supported on the support base 26 so as to be rotatable at equal distances in the circumferential direction. These gripping rollers 27 are synchronized in the radial direction by a drive mechanism built in the support base 26. Move and expand and contract as a whole. A flange portion 28 is formed on the outer periphery of the lower end portion of each gripping roller 27.

  At least one of the gripping rollers 27 described above, here, one gripping roller 27a is connected to a rotation drive mechanism (not shown) built in the support base 26. As a result, the rotation drive mechanism is When operated and a rotational driving force is applied to the gripping roller 27a, the gripping roller 27a rotates. Then, after inserting the gripping roller 27 in the reduced diameter state into the upper bead portion 14 of the inspection tire 11 from above along the central axis of the horizontally inspected inspection tire 11, the diameter of the gripping roller 27 is increased. The gripping roller 27 abuts on the inner periphery of the upper bead portion 14, and the flange portion 28 abuts on the inner surface of the upper bead portion 14 to grip the inspection tire 11 from the inside.

  In this state, after the moving frame 25 moves together with the inspection tire 11 until the central axis of the inspection tire 11 is coaxial with the central axis of the inspection position K, if the rotational force is applied to the gripping roller 27a by the rotational drive mechanism, The inspection tire 11 held by the roller 27 from the inside rotates around the central axis. The gripping roller 27 and the rotational drive mechanism described above constitute a rotating means 29 that rotates the inspection tire 11 around the central axis as a whole. And, as described above, since the rotational driving force is applied from the gripping roller 27 to the bead portion 14 having the highest rigidity in the inspection tire 11, the deformation of the inspection tire 11 or between the inspection tire 11 and the gripping roller 27 is performed. Slipping and the like can be prevented.

  32 is a shield box that can be opened and closed to surround the inspection position K in order to prevent leakage of radiation and reflected radiation from the radiation source described later, and this shield box 32 is used as a shielding material. It is made of lead. A storage case 33 formed of a shielding material is attached to the lower surface of the ceiling of the shield box 32 via a mounting base 35, and a plurality of, in this case, ring-shaped regions 22a, 22b, 22c, and 22d are provided in the storage case 33. Four storage chambers 34a, 34b, 34c, 34d, which are the same number, are formed.

  The storage chambers 34a, 34b, 34c, and 34d are sequentially arranged with a substantially equal distance from the center of the inspection position K toward the outer side in the radial direction, and are spaced equiangularly toward one side in the circumferential direction. However, they are arranged sequentially. Radiation sources 36a, 36b, 36c, 36d for irradiating radiation (X-rays) such as X-rays and γ-rays downward are respectively provided on the upper surfaces of the storage case 33, more specifically, the storage chambers 34a, 34b, 34c, 34d. The same number (four) of the ring-shaped regions 22a, 22b, 22c, and 22d is provided.

  Further, through slits 37a, 37b, 37c, 37d communicating with the storage chambers 34a, 34b, 34c, 34d are formed at the lower end of the storage case 33, respectively. When the inspection tire 11 is carried into the inspection position K and is rotated around the central axis, the radiation corresponding to the radiation from the radiation sources 36a, 36b, 36c, 36d is passed through the through slits 37a, 37b, 37c, 37d. By irradiating the respective regions 22a, 22b, 22c, and 22d, the regions are narrowed so as not to diffuse so much. The storage case 33, the mounting base 35, and the radiation sources 36a, 36b, 36c, and 36d described above constitute a radiation generator 38 as a whole.

  39a, 39b, 39c, 39d are installed directly below the radiation sources 36a, 36b, 36c, 36d, respectively, and are composed of the same number of the radiation sources 36a, 36b, 36c, 36d, here four X-ray line sensors, etc. An imager. The imager 39a is on the optical path of the radiation irradiated from the radiation source 36a and transmitted through the ring-shaped region 22a, and the imager 39b is on the optical path of the radiation irradiated from the radiation source 36b and transmitted through the ring-shaped region 22b. Further, the imager 39c is on the optical path of the radiation irradiated from the radiation source 36c and transmitted through the ring-shaped region 22c, and the imager 39d is on the optical path of the radiation irradiated from the radiation source 36d and transmitted through the ring-shaped region 22d. , Each is installed.

  As a result, the imagers 39a, 39b, 39c, and 39d can respectively capture the radiation transmitted through the ring-shaped regions 22a, 22b, 22c, and 22d after being irradiated from the radiation sources 36a, 36b, 36c, and 36d. However, at this time, if any of the ring-shaped regions 22a, 22b, 22c, and 22d has an internal defect, such as a metallic foreign object or a wire, the radiation is absorbed by the internal defect and the image data is displayed. A region with the highest density (black) appears.

  Here, the radiation sources 36a, 36b, 36c, and 36d (the storage chambers 34a, 34b, 34c, and 34d) are shifted in the radial direction and the circumferential direction as described above, so that the radiation sources 36a, 36b, 36c, Radiation from 36d is not incident on any other imager than the corresponding imagers 39a, 39b, 39c, 39d. Reference numeral 40 denotes detection means for inputting image data from the image pickup devices 39a, 39b, 39c, and 39d. The detection means 40 has threshold values having different values for the ring-shaped regions 22a, 22b, 22c, and 22d. Is set.

  In this embodiment, the radiation transmittance in the ring-shaped region 22a is the lowest from the structure as described above, and the overall density of the image data is the highest (dark), so that the threshold value is set to the highest value in order to avoid false detection. On the other hand, the radiation transmittance in the ring-shaped region 22c is the highest in the configuration as described above, and the overall density of the image data is the lowest (bright), so try to avoid detection errors (improve detection accuracy) The threshold value is set to the lowest value.

  Further, since the radiation transmittance in the ring-shaped regions 22b and 22d is an intermediate value different from the above-described structure, and the overall density of the image data is also a different height (darkness), erroneous detection and detection error are caused. In an attempt to avoid both, the threshold value is set to a different intermediate value. When the image data is input from the image pickup devices 39a, 39b, 39c, and 39d, the detection means 40 immediately changes the image data to different values for each of the ring-shaped regions 22a, 22b, 22c, and 22d as described above. Threshold processing is performed based on the set threshold value, and internal defects are detected for each of the ring-shaped regions 22a, 22b, 22c, and 22d.

  Thus, the radiation sources 36a, 36b, 36c, 36d are provided in the same number as the number of ring-shaped regions 22a, 22b, 22c, 22d, and the radiation sources 36a, 36b corresponding to the respective ring-shaped regions 22a, 22b, 22c, 22d. , 36c, and 36d are irradiated, so that it is possible to quickly detect internal defects in the entire side wall portion 21 only by rotating the inspection tire 11 once. Further, as described above, the side wall portion 21 is defined by four ring-shaped regions 22a, 22b, 22c, and 22d having substantially the same width, so that the detection accuracy is effectively improved without making it excessively complicated. Can be made.

Next, the operation of the first embodiment will be described.
First, after inserting the gripping roller 27 in a reduced diameter state into the upper bead portion 14 from above along the central axis of the inspection tire 11 stored in a horizontal position in a storage place (not shown), the gripping roller 27 is Increase the diameter. As a result, the gripping rollers 27 come into contact with the inner periphery of the upper bead portion 14, the flange portion 28 comes into contact with the inner surface of the upper bead portion 14, and the inspection tire 11 is gripped by the gripping rollers 27 from the inside.

  In this state, the moving frame 25 moves together with the inspection tire 11 until the central axis of the inspection tire 11 is coaxial with the central axis of the inspection position K surrounded by the shield box 32. When the rotational force is applied from the rotating means 29 to the inspection tire 11 carried into the inspection position K in this way, the inspection tire 11 rotates around the central axis while being gripped by the gripping roller 27 from the inside.

  At this time, when radiation is irradiated downward from the radiation sources 36a, 36b, 36c, 36d, the radiation passes through the ring-shaped regions 22a, 22b, 22c, 22d while being narrowed by the through slits 37a, 37b, 37c, 37d. After that, the image pickup devices 39a, 39b, 39c, and 39d are reached and imaged by the image pickup devices 39a, 39b, 39c, and 39d. Thereafter, when image data is input from the image pickup devices 39a, 39b, 39c, 39d to the detection means 40, the detection means 40 immediately sets different values for the ring-shaped regions 22a, 22b, 22c, 22d for these image data. Threshold processing is performed based on the threshold value.

  At this time, if any of the ring-shaped regions 22a, 22b, 22c, and 22d has an internal defect, for example, a metal foreign object or a wire protrusion, radiation is absorbed by the internal defect, and the highest density ( Since a black area appears, an internal defect can be easily detected. In this way, when detecting one after another simultaneously with radiation irradiation, if an internal defect is detected in the inspection tire 11, the subsequent internal defect detection operation can be stopped, so that the work efficiency is improved. Can do. Further, when the inspection tire 11 is rotated as described above and irradiated with radiation, the influence of the tread portion 16 and the bead core 13 can be minimized, so that internal defects are detected with high accuracy. be able to.

  In this way, the threshold value can be set to a different optimum value for each ring-shaped region 22a, 22b, 22c, 22d, so that internal defects in each ring-shaped region 22a, 22b, 22c, 22d are erroneously detected and It is possible to detect while preventing both detection mistakes, and thereby the detection accuracy can be improved while avoiding erroneous detection easily in the entire sidewall portion 21 of the inspection tire. Here, after the inspection tire 11 is rotated once to obtain image data of the entire side wall 21, a transmitted radiation image of the entire side wall 21 is created based on this image data, and then this transmitted radiation image is formed in each ring shape. The area is divided into four concentric ring-shaped areas corresponding to the regions 22a, 22b, 22c, and 22d, and threshold processing is performed for each of these areas using the corresponding threshold value, so that internal defects of the inspection tire 11 are detected. May be detected.

    FIG. 3 is a diagram showing a second embodiment of the present invention. In the figure, reference numeral 45 denotes a pair of brackets attached to the lower surface of the ceiling of the shield box 32, and both ends of horizontal guide rods 46 extending in the radial direction from the center of the inspection position K are fixed to the pair of brackets 45. Has been. 47 is a screw shaft that extends directly above and parallel to the guide rod 46. The front end portion of the screw shaft 47 is rotatably supported by the front bracket 45 and the rear end portion thereof is rotatably supported by the rear bracket 45, respectively. A motor 49 attached to the lower surface of the ceiling of the shield box 32 is installed on the extension line of the screw shaft 47, and the rear end of the screw shaft 47 is connected to the output shaft 48 of the motor 49.

  Reference numeral 50 denotes a moving block slidably engaged with the guide rod 46, and the screw shaft 47 is screwed into the moving block 50. As a result, when the motor 49 operates and the screw shaft 47 rotates, the moving block 50 moves in the radial direction with respect to the center of the inspection position K while being guided by the guide rod 46. The guide rod 46, the screw shaft 47, the motor 49, and the moving block 50 described above constitute a moving means 51 that moves a radiation source, which will be described later, from the center of the inspection position K in the radial direction.

  Reference numeral 52 denotes a storage case made of a shielding material attached to the lower surface of the moving block 50. In the storage case 52, a storage chamber 53 in which one radiation source 54 is installed is formed. The moving block 50 and the radiation source 54 are moved intermittently by the operation of the moving means 51, the first position A immediately above the ring-shaped region 22a, the second position B directly above the ring-shaped region 22b, It is possible to stop at the third position C immediately above the ring-shaped region 22c and the fourth position D directly above the ring-shaped region 22d. Further, a through slit 55 communicating with the storage chamber 53 is formed at the lower end of the storage case 52 as in the first embodiment.

  56a, 56b, 56c, 56d are arranged in the radial direction directly below the first position A, second position B, third position C, fourth position D, and the ring-shaped regions 22a, 22b, 22c, 22d The same number, here, four imagers, these imagers 56a, 56b, 56c, 56d are irradiated from the radiation sources 54 stopped at the respective positions A, B, C, D, and ring-shaped regions 22a, 22b, 22c. , 22d can be imaged respectively.

  When inspecting an internal defect of the inspection tire 11, first, a ring-shaped region of the inspection tire 11 rotating at the inspection position K is irradiated with radiation from the radiation source 54 located at the first position A through the through slit 55. At this time, the radiation transmitted through the ring-shaped region 22a is captured by the imager 56a and then output to the detection means 40 as image data. As described above, when the image data is input from the image pickup device 56a to the detection means 40, the detection means 40 sets a threshold value set to an optimum value corresponding to the internal structure of the ring-shaped region 22a. Based on this, threshold processing is performed to detect internal defects in the ring-shaped region 22a.

  Next, after moving the radiation source 54 to the second position B by the moving means 51, an internal defect in the ring-shaped region 22b is detected as described above. Thereafter, internal defects in the ring-shaped regions 22c and 22d are also detected at the third position C and the fourth position D. Thus, since only one radiation source 54 is provided and the radiation source 54 is intermittently moved in the radial direction by the moving means 51, the structure of the entire apparatus can be simplified and the manufacturing cost can be reduced. It can be inexpensive. Other configurations and operations are the same as those in the first embodiment.

    4, 5, 6, and 7 are views showing Embodiment 3 of the present invention. In the figure, reference numeral 61 denotes a conveyor that continuously conveys the horizontally inspected inspection tire 11 linearly forward (in the direction of the arrow). The conveyor 61 includes a number of synchronously rotating rollers 62 that extend in the left-right direction. Have. Reference numeral 63 denotes a shield box arranged so as to surround the inspection position K. Radiation (X-rays) is applied to the lower end of the mounting base 64 fixed to the ceiling of the shield box 63 downward, that is, to the transport conveyor 61 at the inspection position K. A pair of radiation sources 65 and 66 that irradiate toward the surface are attached, and these radiation sources 65 and 66 are arranged immediately above the left and right ends of the tread portion 16 of the inspection tire 11 that has reached the inspection position K, respectively.

70 and 71 are two rollers 62 adjacent to each other immediately below the conveyor 61 at the inspection position K.
The number of the radiation sources 65 and 66 arranged between them is an imager composed of a pair of X-ray line sensors and the like here, and these imagers 70 and 71 are both in a direction orthogonal to the conveyance direction of the inspection tire 11, that is, While extending in the left-right direction, adjacent ends overlap each other. The imagers 70 and 71 are separated from each other by a predetermined distance in the transport direction of the inspection tire 11, and the radiation emitted from the radiation sources 65 and 66 is narrowed between the radiation sources 65 and 66 and the imagers 70 and 71. Each of the slits 72 is provided so that the radiation irradiated from the radiation source 65 is incident only on the imager 70 and the radiation irradiated from the radiation source 66 is incident only on the imager 71.

  As a result, when the inspection tire 11 passes through the inspection position K, the imagers 70 and 71 receive the radiation transmitted through the ring-shaped regions 22a, 22b, 22c, and 22d of the side wall portion 21 of the inspection tire 11. At this time, the imager 70 images the left half of the inspection tire 11, while the imager 71 images the right half of the inspection tire 11. Thereafter, the left half image data and the right half image data are respectively output from the imagers 70 and 71 to the detection means 75. At this time, the detection means 75 uses the left half image data and the right half transmission radiation half image data based on the image data. Create images 76 and 77. Here, actually, these transmitted radiation half-images 76 and 77 are shifted by the same amount because the image pickup devices 70 and 71 are arranged slightly shifted in the transport direction, but they overlap in the drawing. Is largely shifted so that no interference occurs on the drawing.

  After that, the detecting means 75 combines the transmitted radiation half images 76 and 77 to create one transmitted radiation image, and then erases the region of the highest density portion (black) formed by the tread portion 16 and the bead core 13. Thereafter, the transmitted radiation image (which has been subjected to various processes, but is essentially image data from the imagers 70 and 71) 78 is converted into four concentric ring shapes corresponding to the ring-shaped regions 22a, 22b, 22c and 22d. Are divided into areas 78a, 78b, 78c, 78d (regions where the radiation transmitted through the ring-shaped regions 22a, 22b, 22c, 22d respectively arrives), and each of the areas 78a, 78b, 78c of these transmitted radiation images 78 , 78d using the corresponding threshold value to detect internal defects in the inspection tire 11. At this time, since the radiation sources 65 and 66 are arranged immediately above the left and right ends of the tread portion 16 of the inspection tire 11, the blind spots for detection by the bead core 13 and the belt layer 19 can be greatly reduced.

  Thus, the threshold value can be set to a different optimum value for each ring-shaped region 22a, 22b, 22c, 22d. Therefore, in this embodiment as well, each ring-shaped region 22a, 22b, 22c, 22d is similarly applied. It is possible to detect an internal defect in, while preventing both erroneous detection and erroneous detection. Further, when the horizontally inspected inspection tire 11 is linearly transported by the transport conveyor 61 as in this embodiment, radiation is applied to the inspection tire 11 from the radiation sources 65 and 66. Since the internal defects of the inspection tire 11 can be continuously detected one after another, the internal defects of the inspection tire 11 can be detected with high efficiency. Other configurations and operations are the same as those in the first embodiment.

    In the above-described embodiment, the side wall portion 21 is divided into four ring-shaped regions 22a, 22b, 22c, and 22d. However, in the present invention, 2, 3, or 5 depending on the internal structure of the inspection tire. You may make it divide into the above ring-shaped area | regions. In the second embodiment, the same number of imagers 56a, 56b, 56c, and 56d as the ring-shaped regions 22a, 22b, 22c, and 22d are arranged side by side in the radial direction. One imager that covers the entire part is installed, and the imager is divided into the same number as the number of ring-shaped regions, and the first to fourth positions each time the radiation source moves to the first to fourth positions. The image data may be output to the detection means from the divided area of the image pickup device corresponding to.

  The present invention can be applied to an industrial field for inspecting an internal defect of a tire side wall.

It is front sectional drawing which shows Example 1 of this invention. It is the II arrow directional view of FIG. It is front sectional drawing which shows Example 2 of this invention. It is a partially broken top view which shows Example 3 of this invention. It is the partially broken side view. It is a meridian sectional view of a tire showing an inspection tire and its transmitted radiation image. It is a top view which shows the transmitted radiation image at the time of performing a threshold value process.

Explanation of symbols

11 ... Inspection tire 13 ... Bead core
16 ... Tread part 21 ... Side wall part
29 ... Rotating means 40 ... Detecting means
51 ... Moving means E ... Extension line
22a, 22b, 22c, 22d ... Ring-shaped region
36a, 36b, 36c, 36d ... Radiation source
39a, 39b, 39c, 39d ... Imager

Claims (7)

    While dividing the side wall portion of the inspection tire located between the extension line of the inner surface of the tread portion and the bead core into a plurality of concentric ring-shaped regions, while irradiating the side wall portion of the inspection tire with radiation from a radiation source, Radiation that has passed through each ring-shaped region of the side wall is imaged by an imager, and then based on threshold values set to different values for each ring-shaped region with respect to image data from the imager by the detection means. A method for inspecting an internal defect in a tire sidewall, wherein threshold processing is performed to detect an internal defect in the ring-shaped region.     The method for inspecting internal defects in a tire side wall according to claim 1, wherein the side wall is defined by four ring-shaped regions having substantially equal widths.     The method for inspecting an internal defect in a tire side wall according to claim 1 or 2, wherein when the inspection tire is driven by a rotating means and rotates about a central axis, the inspection tire is irradiated with radiation.     The internal defect inspection method for a tire side wall according to claim 1 or 2, wherein when the inspection tire in a horizontally placed state is linearly conveyed by a conveyor, the inspection tire is irradiated with radiation.     An internal defect inspection device for a tire side wall portion for inspecting an internal defect of a side wall portion of an inspection tire positioned between an extension line of an inner surface of a tread portion and a bead core, wherein the inspection tire side wall portion has a plurality of concentric circular shapes. A radiation source that irradiates the sidewall of the inspection tire with radiation when it is partitioned into ring-shaped regions, an imager that captures radiation that has passed through each ring-shaped region of the sidewall, and image data from the imager Tire side wall having a threshold value process based on a threshold value set to a different value for each ring-shaped region and detecting an internal defect in the ring-shaped region Internal defect inspection equipment.     The internal defect inspection device for a tire side wall according to claim 5, wherein the number of the radiation sources is the same as the number of ring-shaped regions, and the radiation from the corresponding radiation source is irradiated to each ring-shaped region.     In addition to providing only one radiation source, a moving means for moving the radiation source in the radial direction is provided, and the radiation source is intermittently moved in the radial direction by the moving means, so that each ring-shaped region is successively moved. The internal defect inspection device for a tire side wall according to claim 5, wherein radiation is irradiated from a radiation source.

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