JP6200214B2 - Tire inspection method and tire inspection apparatus - Google Patents

Description

  The present invention relates to a tire inspection method and a tire inspection device, and more particularly to a tire inspection method and a tire inspection device that inspects for the presence or absence of abnormality in the surface shape of a tread.

  Conventionally, a tire inspection method using master data indicating a reference surface shape of a tread is known in order to determine an abnormality in the surface shape of the tread of the tire, that is, whether or not there is a defect in the tread (for example, patent literature). 1).

  The surface shape of the tread is defined by the groove and the land defined by the groove. The master data is data for specifying the reference surface shape of the tread. In the tire inspection method, the presence or absence of abnormality in the surface shape of the tread is determined by comparing the data measured by imaging the tread with the master data.

JP 2012-59129 A

  However, there is a possibility that the master data includes an error that occurs when the tread is imaged. In order to improve the accuracy of the master data, it is effective to take an image with a larger number of pixels. However, as the number of pixels increases, the amount of data processing also increases.

  Accordingly, an object of the present invention is to provide a tire inspection method and a tire inspection apparatus that efficiently determine the presence or absence of an abnormality in the surface shape of a tread while suppressing an increase in the amount of data processing.

  The tire inspection method according to the present invention is a tire inspection method for inspecting a tire (tire T) including a tread having a land portion (tread Ts), and measuring a plurality of data for specifying the surface shape of the tread. And a step B of determining whether there is an abnormality in the surface shape of the tread based on the plurality of measurement data and a plurality of reference data for specifying the reference surface shape of the tread. The step B is a step B1 of extracting corner position data indicating the position of a corner formed on the contour line of the land portion from the plurality of measurement data and the plurality of reference data, and from the plurality of measurement data. Comparing the extracted corner position data with the corner position data extracted from the plurality of reference data And summarized in that and a 2.

  Moreover, the tire inspection apparatus (tire inspection apparatus 1) according to the present invention is a tire inspection apparatus that inspects a tire including a tread having a land portion, and measures a plurality of data for specifying the surface shape of the tread. The presence or absence of abnormality in the surface shape of the tread is determined based on the measurement unit (measuring device 10), the plurality of measurement data, and the plurality of reference data for specifying the reference surface shape of the tread. An abnormality determination unit (abnormality determination device 20), wherein the abnormality determination unit includes corner position data indicating a position of a corner formed on a contour line of the land portion, the plurality of measurement data, and the plurality of reference data. The corner position data extracted from the plurality of measurement data and the corner position data extracted from the plurality of reference data are paired with each other. And it is required to.

  ADVANTAGE OF THE INVENTION According to this invention, the tire inspection method and tire inspection apparatus which determine efficiently the presence or absence of abnormality in the surface shape of a tread can be provided, suppressing the increase in the processing amount of data.

FIG. 1 is a diagram illustrating a tire inspection apparatus according to the present embodiment. FIG. 2 is a block diagram illustrating the abnormality determination device according to the present embodiment. FIG. 3 is a flowchart showing the tire inspection method according to the present embodiment.

  Hereinafter, a tire inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Hereinafter, the tire inspection apparatus according to the present embodiment will be described. FIG. 1 is a diagram showing a tire inspection apparatus 1 according to the present embodiment.

  As shown in FIG. 1, the tire inspection device 1 includes a measurement device 10 and an abnormality determination device 20. The measuring device 10 includes a tire rotating device 11, an irradiator 12, and an imager 13. The abnormality determination device 20 includes a data processing device 30 and a display device 40.

  The tire rotating device 11 holds the tire T in the vertical direction at the center in the radial direction, and rotates it in the circumferential direction by a motor.

  The irradiator 12 irradiates the surface of the tread Ts with slit-shaped red laser light, white laser light, or other monochromatic laser light (slit light). In FIG. 1, as the irradiator 12, irradiators 12 a, 12 b, and 12 c arranged in parallel with the width direction of the tire T are shown. The irradiators 12a, 12b, and 12c irradiate the tread Ts with slit light so that the slit light emitted from the irradiators 12a, 12b, and 12c extends in a straight line in the width direction of the tire T.

  The imager 13 is a CCD camera or a CMOS camera, for example, and images the surface shape of the tread Ts rotated by the tire rotating device 2. In FIG. 1, imagers 13 a, 13 b and 13 c are shown as the imager 13. The imaging devices 13a, 13b, and 13c receive the slit light from the irradiators 12a, 12b, and 12c reflected at the irradiation position 14 of the tread Ts, and measure a plurality of data for specifying the surface shape of the tread Ts. That is, data (hereinafter, measured data) measured for a plurality of points located on the surface of the tread Ts includes a distance (height) from the radial center of the tire T. Based on the measurement data, the imager 13 generates an image of the surface shape of the tread Ts as a band-like image having, for example, 256 tone (grayscale) tone information, and outputs the image to the data processing device 30.

  The data processing device 30 includes a data input unit 31, a data processing unit 32, a data storage unit 33, and a data output unit 34.

  The data input unit 31 acquires measurement data from the measurement device 10.

  The data processing unit 32 generates an image of the surface shape of the tread Ts based on the measurement data acquired by the data input unit 31. Specifically, the data processing unit 32 identifies, as a point on the land, a point whose distance (height) from the radial center of the tire is equal to or greater than a threshold based on the measurement data, and the height is the threshold Points that are less than are identified as points on the groove. The data processing unit 32 specifies a line connecting a point on the land and a point on the land adjacent to the groove as an outline. In this way, the data processing unit 32 generates an image of the surface shape of the tread Ts having land portions and groove portions.

  The data processing unit 32 calculates a plurality of reference data for specifying the reference surface shape of the tread Ts based on the measurement data acquired by the data input unit 31. Specifically, the data processing unit 32 cuts out an image of the surface shape of the tread Ts with a constant cutout width in the circumferential direction. The cut-out width is, for example, the narrowest interval among the pitch variations of the tread pattern. The data processing unit 32 calculates reference data by matching a plurality of cut out images.

  The data processing unit 32 extracts corner position data indicating the position of the corner formed on the contour line of the land from a plurality of measurement data and a plurality of reference data. Here, the corner means a point where the angle of the contour line of the land portion changes greatly. The corner is usually formed at a portion where a plurality of groove portions meet or at an end portion of the groove portion, etc., but even when a defect is present on the surface of the tread Ts, the angle of the outline changes greatly at the missing portion. Therefore, a corner is formed.

  Examples of methods for extracting corner position data from a plurality of measurement data and a plurality of reference data include, for example, SUSAN operator, Harris operator, KLT tracker, principal curvature method, FAST, Trajkovic and Hedley method, Moravec operator, Shi and Tomasi. An arbitrary corner detection method such as a method can be used, but here, a SUSAN operator will be described as an example.

  The data processing unit 32 determines the ratio of the points on the land portion within the predetermined distance from the specified point based on the measurement data corresponding to the points located within the predetermined distance from the specified point on the contour line. The specified point is specified as the corner when it is in the numerical value range. Specifically, in the image of the surface shape of the tread Ts, the data processing unit 32, for example, draws a circle with a radius R around a specified point on the contour line. At this time, the data processing unit 32 calculates the ratio of the points on the land portion in the circle with the radius R based on the measurement data corresponding to the points belonging to the circle with the radius R. As a result, when the ratio of the points on the land portion in the circle with the radius R is within a predetermined numerical range, the data processing unit 32 specifies the designated point as a corner.

  The predetermined numerical range can be set arbitrarily, but can be set as follows, for example. When the designated point is located at a flat portion of the contour line, the circle with the radius R includes approximately 50% of the points on the land and the points on the groove. Therefore, when the ratio of the points on the land portion in the circle with the radius R is in a numerical range in which an error is added to 50% (for example, 45% to 55%), the specified point is a corner. It is determined that it is not. In other cases (for example, less than 45% or 55% or more), the data processing unit 32 determines that the ratio of the points on the land portion in the circle with the radius R is within a predetermined numerical range and designates it. A point may be specified as a corner.

  When the corner corresponding to the corner position data extracted from the plurality of measurement data is separated from the corner corresponding to the corner position data extracted from the plurality of reference data by a predetermined distance or more, the data processing unit 32 It is determined that there is an abnormality in the surface shape of Ts. The predetermined distance can be arbitrarily set according to the angle change condition of the contour line for specifying the corner.

  The data storage unit 33 stores reference data. The data output unit 34 outputs the image of the surface shape of the tread Ts generated by the data processing unit 32 and the image of the reference surface shape of the tread Ts to the display device 40.

  FIG. 2 is a diagram illustrating an example of an image displayed on the display device 40 according to the present embodiment. As illustrated in FIG. 2, the display device 40 displays the image of the surface shape of the tread Ts acquired from the data processing device 30 and the image of the reference surface shape of the tread Ts.

  FIG. 2A shows an image of the surface shape of the tread Ts generated based on the measurement data. As shown in FIG. 2A, corners P11 to P17 are formed on the contour line C1.

  FIG. 2B shows an image of the reference surface shape of the tread Ts generated based on the reference data. As shown in FIG. 2B, corners P01 to P06 are formed on the contour line C0.

  FIG. 2C shows a diagram in which the image of the surface shape of the tread Ts shown in FIG. 2A and the image of the reference surface shape of the tread Ts shown in FIG. Here, when all corners on the contour line C1 correspond to all corners on the contour line C0 (when the corner on the contour line C0 is located within a predetermined distance from the corner on the contour line C1) ), The abnormality determination device 30 (data processing unit 32) determines that there is no abnormality on the surface of the tread Ts. On the other hand, when the corner adjacent to the corner on the contour line C1 does not exist on the contour line C0 (when the corner on the contour line C0 does not exist within a predetermined distance from the corner on the contour line C1), the corner Does not correspond to the corner on the contour line C0, and the abnormality determination device 30 determines that the surface of the tread Ts is abnormal.

  In FIG. 2C, a corner adjacent to the corner P12 on the contour line C1 does not exist on the contour line C0. Further, the corner P11 on the contour line C1 and the corner P01 on the most adjacent contour line C0 are present at positions separated by a predetermined distance or more. Therefore, it can be seen that a defect on the surface of the tread Ts is generated between the corners P11 and P12.

(Tire inspection method)
Hereinafter, a tire inspection method according to the present embodiment will be described. FIG. 4 is a flowchart showing the tire inspection method according to the present embodiment.

  In step S10, the measuring apparatus 10 measures a plurality of data for specifying the surface shape of the tread Ts. The measurement data includes distances between a plurality of points located on the surface of the tread Ts and the radial center of the tire T.

  In step S <b> 11, the data processing device 30 calculates a plurality of reference data for specifying the reference surface shape of the tread Ts based on the plurality of measurement data.

  In step S12, the data processing device 30 specifies a point where the distance (height) from the radial center of the tire is equal to or greater than a threshold value as a point on the land portion, and determines that the height is less than the threshold value as a groove Identify as the top point.

  In step S13, the data processing device 30 specifies a line connecting the point on the land and the point on the land adjacent to the groove as the contour line of the land.

  In step S14, the data processing device 30 extracts corner position data indicating the position of the corner formed on the contour line of the land portion from the plurality of measurement data and the plurality of reference data. Specifically, the data processing device 30 specifies the specified point as a corner when the ratio of the points on the land is within a predetermined numerical range within a predetermined distance from the point specified as the contour line. .

  In step S15, the data processing device 30 compares the corner position data extracted from the plurality of measurement data with the corner position data extracted from the plurality of reference data. Specifically, the data processing device 30 has an abnormality in the surface shape of the tread Ts when the corner position data extracted from the plurality of measurement data does not correspond to the corner position data extracted from the plurality of reference data. Is determined.

  As described above, the tire inspection apparatus according to the present invention compares the corner position data extracted from the measurement data with the corner position data extracted from the reference data. Thereby, it is possible to determine the presence or absence of a defect in the tread Ts by comparing only the position of the corner which is a characteristic part on the contour line without comparing all the measurement data with the reference data. In addition, the corner formed on the contour line can easily extract position data from a plurality of measurement data without increasing the number of pixels of the image captured by the imager 13. Therefore, the tire inspection method and the tire inspection apparatus according to the present invention can efficiently determine the presence or absence of abnormality in the surface shape of the tread while suppressing an increase in the data processing amount.

[Other Embodiments]
Although the present invention has been described with reference to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the embodiment, the data processing device 30 has been described as calculating a plurality of reference data for specifying the reference surface shape of the tread based on the plurality of measurement data. However, the embodiment is not limited to this. As the reference data, a numerical value set in advance for each tire type may be used.

  DESCRIPTION OF SYMBOLS 1 ... Tire inspection apparatus, 10 ... Measuring apparatus, 11 ... Tire rotating apparatus, 12 ... Irradiator, 13 ... Imaging device, 14 ... Irradiation position, 20 ... Data processing apparatus, 30 ... Abnormality determination apparatus, 31 ... Data input part, 32 ... Data processing unit, 33 ... Data storage unit, 34 ... Data output unit, 40 ... Display device, T ... Tire, Ts ... Tread

Claims (4)

A tire inspection method for inspecting a tire including a tread having a land portion,
Measuring a plurality of measurement data for specifying the surface shape of the tread; and
A step B of determining whether or not there is an abnormality in the surface shape of the tread based on the plurality of measurement data and a plurality of reference data for specifying the reference surface shape of the tread;
Step B includes
Step B1 for extracting corner position data indicating the position of a corner formed on the contour line of the land portion from the plurality of measurement data and the plurality of reference data;
E Bei and step B2 for comparing said corner position data extracted from the plurality of measurement data, and the corner position data extracted from the plurality of reference data,
In step B2, when the plurality of corners corresponding to the corner position data extracted from the measured data, apart the above plurality of the distance from the corner of the predetermined corresponding to the corner position data extracted from the reference data , the filter ear test method to determine that there is an abnormality in the surface shape of the tread. The step B1 is based on measurement data corresponding to a point located within a predetermined distance from the point designated on the contour line, and the points on the land portion within the predetermined distance from the designated point are measured. The tire inspection method according to claim 1, further comprising a step B3 of specifying the designated point as the corner when it is determined that the ratio is in a predetermined numerical range. A tire inspection apparatus for inspecting a tire including a tread having a land portion,
A measurement unit for measuring a plurality of measurement data for specifying the surface shape of the tread;
Based on the plurality of measurement data and a plurality of reference data for specifying a reference surface shape of the tread, an abnormality determination unit that determines whether there is an abnormality in the surface shape of the tread,
The abnormality determination unit
Corner position data indicating the position of the corner formed on the contour line of the land portion is extracted from the plurality of measurement data and the plurality of reference data;
Comparing the corner position data extracted from the plurality of measurement data with the corner position data extracted from the plurality of reference data ;
When the corner corresponding to the corner position data extracted from the plurality of measurement data is separated from the corner corresponding to the corner position data extracted from the plurality of reference data by a predetermined distance or more, Ruta ear inspection apparatus to determine that there is an abnormality in the surface shape. The abnormality determination unit, based on measurement data corresponding to a point located within a predetermined distance from a point specified on the contour line, points on the land portion within the predetermined distance from the specified point The tire inspection device according to claim 3 , wherein the designated point is specified as the corner when the ratio is within a predetermined numerical range.

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