JP6494021B2 - Tire groove depth measurement method - Google Patents

Description

  The present invention relates to a tire groove depth measurement method for measuring the depth of a groove on a tire surface.

  In order to confirm the wear state of the tire, the depth of the tire groove is measured. As a method of measuring the depth of the tire groove, a laser displacement meter that uses a dedicated measuring instrument (depth gauge) to measure the groove depth, or irradiates the tire with laser light and measures the reflected light from the tire at the light receiving portion. Or may be used. The tire groove depth measurement method using a laser displacement meter measures the distance between the tire and the light receiving part using the change in the position of the reflected light received by the light receiving part, and determines the tire groove depth. It is determined (for example, Patent Document 1).

JP-A-5-256738

  In the measurement with the depth gauge, the measurement position tends to be different due to variations in the gauge insertion direction and insertion depth with respect to the tire groove depending on the measurer. In addition, a difference in gauge reading is likely to occur depending on the measurer. Therefore, in the measurement with the depth gauge, the measurement result is easily changed by the measurer, and the measurement accuracy is low. Furthermore, the measurement with a depth gauge is inefficient because the measurement over the entire circumference of the tire takes time.

  On the other hand, the measurement with the laser displacement meter can reduce the measurement difference by the measurer, and can be efficiently performed even for the measurement over the entire circumference of the tire. However, depending on the measurement method of the laser displacement meter and the shape of the tire groove, the reflected light cannot be received by the light receiving part of the laser displacement meter, and there is a case where the measurement data is missing and the tire groove depth cannot be measured appropriately. . For example, when measuring the depth of a tire groove while rotating the tire using a triangulation laser displacement meter, the light emitting portion and the light receiving portion of the laser displacement meter are separated from each other substantially in the circumferential direction of the tire. Consider a case where the light receiving unit receives reflected light that is arranged and reflected in a direction different from the incident light from the light emitting unit. At this time, when the tire groove is a lateral groove formed substantially perpendicular to the circumferential direction of the tire, the reflected light reflected at the bottom of the tire groove is blocked by the side wall portion forming the tire groove and does not reach the light receiving portion. Sometimes. As a result, the data measured by the light receiving unit is lost and the measurement accuracy is lowered.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a tire groove depth measurement method capable of efficiently obtaining a highly accurate tire groove depth. is there.

  The tire groove depth measurement method of the present invention is a tire groove depth measurement method for measuring the groove depth of the tire surface using a laser displacement meter, and includes a reference data acquisition step and an inversion data acquisition step. And a data synthesis step. In the reference data acquisition step, incident light is irradiated from a predetermined direction onto the tread surface of the tire, and reflected light at a predetermined angle with respect to the incident light is received by the light receiving unit, and the tire groove depth data is obtained. get. In the inverted data acquisition step, the relative position of the light receiving portion with respect to the tire is set to a position inverted from the position of the light receiving portion in the reference data acquisition step with incident light interposed therebetween, and the depth of the tire groove is determined. Get the data. The data synthesis step collates the reference data obtained in the reference data acquisition step with the inverted data obtained in the inverted data acquisition step, and measures the laser displacement meter as one of the reference data and the inverted data. When there is missing data due to the method, the other data of the reference data and the inverted data is adopted instead of the missing data, and the data obtained by combining the reference data and the inverted data is used as the depth of the tire groove. Say it.

  As an example of the tire groove depth measurement method, in the reference data acquisition step and the inverted data acquisition step, data is collected over the entire circumference in the circumferential direction of the tire while rotating the tire around its rotation axis. Correction, selecting a position that becomes a reference point in the width direction of the tire in at least one of the reference data and the inverted data, and rearranging the data in the width direction so that the reference points all fit in the circumferential direction. In the data composition step, the corrected data obtained in the width direction correction step is used for collation.

  As an example of the tire groove depth measurement method, in the reference data acquisition step and the inverted data acquisition step, data is collected over the entire circumference in the circumferential direction of the tire while rotating the tire around its rotation axis. And acquiring a reference point in the radial direction of the tire in at least one of the reference data and the inverted data, and acquiring radial data so that the reference point is constant over the entire circumference. A radial direction correction step for correction is provided, and in the data synthesis step, the corrected data obtained in the radial direction correction step is used for verification.

  As an example of the tire groove depth measurement method, in the reference data acquisition step and the inverted data acquisition step, data is collected over the entire circumference in the circumferential direction of the tire while rotating the tire around its rotation axis. And obtaining a reference point in the circumferential direction of the tire in each of the reference data and the inverted data, and data in the circumferential direction so that the reference point in the reference data matches the reference point in the inverted data In the circumferential direction correction step, and in the data synthesis step, the corrected data obtained in the circumferential direction correction step is used for verification.

  As an example of the method for measuring the depth of the tire groove, it is possible to further include a reproduction correction step. In the reproduction correction step, using the composite data obtained in the data synthesis step and one selection data selected from the reference data and the inverted data, the tire groove depth profile uses the composite data, Reproduction data is created for the uneven profile of the tire surface other than the tire groove using the selection data.

  A tire groove depth measuring device that can be used in the tire groove depth measuring method includes a rotation mechanism capable of rotating a tire around its rotation axis, a laser displacement meter, a reversing unit, a storage unit, A data synthesis unit. The laser displacement meter includes a light emitting unit that irradiates incident light from a predetermined direction with respect to the tread surface of the tire, and a light receiving unit that receives reflected light at a predetermined angle with respect to the incident light. The reversing portion can reverse the relative position of the light receiving portion with respect to the tire with the incident light interposed therebetween. The storage unit includes reference data of the tire groove depth acquired by the laser displacement meter, and the tire groove acquired after the position of the light receiving unit when the reference data is acquired is inverted by the inversion unit. Depth inversion data is stored. When the reference data and the inverted data include missing data due to the measurement method of the laser displacement meter in the reference data and the inverted data, the data synthesis unit adopts the inverted data instead of the missing data, and the reference data Composite data is generated by combining data and the inverted data.

  In the tire groove depth measurement method, even if there is missing data in the reference data, if the inverted data corresponding to the position of the tire groove where the missing data is confirmed is not missing, the missing data in the reference data is It can be complemented by inverted data. Therefore, even if missing data occurs in each of the reference data and the inverted data, the reference data and the inverted data can be combined to complement each other and to obtain a precise tire groove depth. it can. This is because the light receiving portion used when acquiring the reference data and the light receiving portion used when acquiring the inverted data are in positions where they are reversed with respect to the incident groove as viewed from the tire groove. . That is, the depth of the tire groove is measured in different directions facing each other across the incident light as viewed from the tire groove.

  In the tire groove depth measuring method, even if one light receiving part (laser displacement meter) is used, the one light receiving part is reversed by sandwiching incident light when viewed from the tire groove. Since the measurement can be performed in different directions facing each other with the incident light interposed therebetween, the structure is simple.

  As a method of measuring the depth of the tire groove, it is possible to measure by creating composite data using reference data obtained in the reference data acquisition process and correction data obtained by correcting the inversion data obtained in the inversion data acquisition process. Accordingly, it is possible to correct an error caused by a tire slipping, and to obtain a tire groove depth with high accuracy.

  As a method of measuring the depth of the tire groove, by providing a reproduction correction step, the tire groove depth profile can be deleted, and the tire surface other than the tire groove can obtain reproduction data having an uneven profile. It is possible to grasp the wear form of the tire.

  The tire groove depth measuring device is easy to invert this one light receiving portion across the incident light as seen from the tire groove, even if one light receiving portion (laser displacement meter) is used. It can be measured in different directions facing each other across the incident light as seen from the tire groove.

It is a schematic block diagram which shows the tire groove depth measuring apparatus used with the tire groove depth measuring method which concerns on Embodiment 1. FIG. It is the enlarged view to which the laser displacement meter and tire groove | channel in FIG. 1 were expanded, (a) shows the case where reflected light can be received, (b) shows the case where reflected light cannot be received. 3 is a flowchart illustrating a procedure of a tire groove depth measurement method according to the first embodiment. It is a schematic explanatory drawing which shows an example of the width direction correction | amendment process in the depth measuring method of the tire groove | channel which concerns on Embodiment 1. FIG. It is a schematic explanatory drawing which shows an example of the radial direction correction | amendment process in the depth measuring method of the tire groove | channel which concerns on Embodiment 1. FIG. It is a schematic explanatory drawing which shows an example of the circumferential direction correction | amendment process in the depth measuring method of the tire groove | channel which concerns on Embodiment 1. FIG. It is a schematic explanatory drawing which shows an example of the reproduction correction process in the tire groove depth measuring method according to the first embodiment.

  Hereinafter, the tire groove depth measurement method of the present invention for measuring the groove depth on the tire surface using a laser displacement meter will be described in detail with reference to the drawings. In the figure, the same reference numerals indicate the same names.

Embodiment 1
-Overall configuration The tire groove depth measurement method according to the first embodiment includes a reference data acquisition step, an inversion data acquisition step, reference data obtained in the reference data acquisition step, and inversion data obtained in the inversion data acquisition step. A data synthesis step of synthesizing the data. The reference data acquisition step irradiates the tire tread surface with incident light from a predetermined direction and receives reflected light at a predetermined angle with respect to the incident light at the light receiving unit to acquire tire groove depth data. It is a process to do. The inversion data acquisition step is a step of acquiring tire groove depth data by setting the relative position of the light receiving portion with respect to the tire to a position inverted from the position of the light receiving portion in the reference data acquisition step with the incident light interposed therebetween. It is. The main feature of the tire groove depth measurement method according to the first embodiment is that the light receiving unit used in the reference data acquisition step and the light receiving unit used in the reverse data acquisition step sandwich incident light as seen from the tire groove. And the data obtained by combining the reference data and the inverted data as the depth of the tire groove. Hereinafter, first, a tire groove depth measuring device will be described with reference to FIGS. 1 and 2, and then a tire groove depth measuring method using the above device will be described with reference to FIGS. 3 to 7.

[Tire groove depth measuring device]
As shown in FIG. 1, the tire groove depth measuring apparatus 1 includes a rotation mechanism 10 that can rotate the tire 100 around its rotation axis, a light emitting unit 21 that irradiates the tire 100 with incident light 21L (laser light), and The laser displacement meter 20 having the light receiving portion 22 that receives the reflected light 22L, the reversing portion 30 that changes the relative position of the light receiving portion 22 with respect to the tire 100, and the depth of the tire groove 110 acquired by the laser displacement meter 20 A storage unit 60 that stores data (reference data and inverted data) and a data synthesis unit 70 that combines the reference data and the inverted data are provided. The main features of the tire groove depth measuring apparatus 1 according to the first embodiment are that the reversing unit 30 is provided, and the reversing unit 30 is reversed with respect to the incident light 21L as viewed from the tire groove 110. A data synthesizing unit 70 for synthesizing the reference data acquired by the light receiving unit 22 and the inverted data. Hereinafter, each component will be described in detail.

Rotating mechanism The rotating mechanism 10 includes a wheel 11 having a rim to which the tire 100 is attached, a rotating shaft 12 connected to the center of the wheel 11 to rotatably support the tire 100, and the rotating shaft 12 being rotatable. A drive source (not shown) for driving and a rotary encoder 13 for detecting the rotation speed (rotation speed) of the tire 100 are provided. The rotating shaft 12 is coaxial with the central axis of the tire 100. That is, in the tire 100 attached to the rotation mechanism 10, the outer surface of the tread surface of the tire 100 is substantially equidistant from the center of the rotation shaft 12. When the rotating shaft 12 is rotated by the driving source, the tire 100 attached to the rotating mechanism 10 is rotated around the central axis. The rotation of the tire 100 is measured over time by the rotary encoder 13. Since the depth of the tire groove 110 is measured over time by a laser displacement meter 20 to be described later, the tire groove 110 is calculated from the data of the depth of the tire groove 110 at a specific time and the rotation angle of the tire 100. It is possible to specify the position of the groove in the circumferential direction of the tire 100. Data on the depth of the tire groove 110 and the position of the tire groove 110 are stored in the storage unit 60 described later. Since the tire 100 measures the depth of the tire groove 110 over the entire circumference, the rotation mechanism 10 is controlled to rotate the tire 100 by 360 °.

Laser Displacement Meter The laser displacement meter 20 receives a light emitting unit 21 that irradiates incident light 21L from a predetermined direction with respect to the tread surface of the tire 100, and reflected light 22L that reflects the incident light 21L at a predetermined angle. And a light receiving portion 22 that performs. Here, the angle of the reflected light 22L with respect to the incident light 21L is a reflection angle of the optical axis of the reflected light 22L with respect to the optical axis of the incident light 21L (in FIG. 1, the incident light 21L and the reflected light 22L are light beams). Only the axes are shown). The reflected light 22L has a predetermined angle with respect to the incident light 21L, and is reflected in a different direction from the incident light 21L. The light receiving unit 22 includes a plurality of light receiving elements. The angle of the reflected light 22L with respect to the incident light 21L varies depending on the difference in distance from the light emitting unit 21 to the reflection position. The light receiving position of the light receiving element changes due to the difference in angle of the reflected light 22L. The distance from the light emitting portion 21 to the tire surface can be calculated by triangulation from the light receiving position of the light receiving element.

  In this example, a two-dimensional laser displacement meter using the above triangulation method is used. The two-dimensional laser displacement meter can simultaneously measure the distance between the displacement meter and the object (tire 100) and the width of the object (tire 100). When the two-dimensional laser displacement meter 20 is used, the incident light 21L is irradiated to the tire 100 over a certain region in the width direction. Therefore, by using the two-dimensional laser displacement meter, the depth of the tire groove 110 in the full width of the tire 100 can be measured efficiently.

  In this example, the light emitting unit 21 is disposed so as to pass through the rotating shaft 12 of the rotating mechanism 10 to which the tire 100 is attached, and the light receiving unit 22 is arranged at a predetermined angle (here, the circumferential direction of the tire 100 with respect to the incident light 21L). Is arranged so as to be able to receive the reflected light 22L reflected at about 20 °. Moreover, the light emission part 21 and the light-receiving part 22 are each arrange | positioned one each.

  The tire groove 110 depth data measured by the laser displacement meter 20 is composed of a two-dimensional array of data groups corresponding to the width direction and the circumferential direction of the tire 100.

  When the above-mentioned triangulation type laser displacement meter is used, there is a problem that the reflected light 22L reflected by the bottom 110b of the tire groove 110 cannot reach the light receiving part 22 and the depth of the tire groove 110 cannot be measured appropriately. May occur. This phenomenon will be described with reference to FIG. Here, the tire 110 rotates counterclockwise (arrow direction). First, as shown in FIG. 2A, when the incident light 21L is irradiated to the front side in the rotation direction of the tire 100 (the left side in FIG. 2A) of the bottom 110b of the specific tire groove 110, The reflected light 22L passes through the opening of the tire groove 110 and reaches the light receiving unit 22. That is, the depth on the front side of the bottom 110b of the tire groove 110 can be measured. On the other hand, as shown in FIG. 2B, the tire 100 rotates, and the irradiation position of the incident light 21L on the bottom 110b of the specific tire groove 110 is the rear side in the rotation direction of the tire 100 (FIG. 2B). ) To the right side), the reflected light 22L is blocked by the side wall portion forming the tire groove 110 and cannot reach the light receiving portion 22. That is, the depth on the rear side of the bottom 110b of the tire groove 110 cannot be measured. As described above, in the specific tire groove 110, as shown in FIG. 2B, there are a region M where the depth can be measured and a region N where the depth cannot be measured. The depth data in the region M is acquired as a real value, and the depth data in the region N is acquired as missing data such as an error or a zero value. The regions M and N vary depending on the positional relationship between the light emitting unit 21 and the light receiving unit 22 (the angle of the reflected light 22L with respect to the incident light 21L), the width and depth of the tire groove 110, and the like.

  Of the tire grooves 110, a groove in which a region M where the depth can be measured and a region N where the depth cannot be measured exists is mainly a lateral groove 112 in which the groove is formed substantially perpendicular to the circumferential direction of the tire 100. In the longitudinal groove 111 (see FIG. 6) in which a groove is formed in the circumferential direction of the tire 100, the side wall portion that forms the groove does not block the reflected light 22L. not exist.

-Inversion part The inversion part 30 is a mechanism which can invert the relative position of the light-receiving part 22 with respect to the tire 100 on both sides of the incident light 21L. The reversing unit 30 includes a reversing shaft 31 that supports the light emitting unit 21 so as to be reversible, and a driving source (not shown) that drives the light receiving unit 22 (laser displacement meter 2) 180 degrees reversible around the reversing shaft 31. And comprising. The inversion shaft 31 is disposed along a straight line connecting the light emitting unit 21 and the rotation shaft 12 of the rotation mechanism 10. By reversing the light receiving unit 22 by the reversing unit 30, it is possible to detect the reflected light 22L reflected in a direction facing the specific tire groove 110 across the incident light 21L as shown in FIG. it can. Therefore, the region N (see FIG. 2B) that could not be measured by the light receiving unit 22 before reversal (shown by a thick dotted line) can be measured by the light receiving unit 22 after reversal (shown by a one-dot chain line). . That is, the depth of the region N acquired as the missing data as a result of the measurement by the light receiving unit 22 before inversion can be acquired as a real value of the result measured by the light receiving unit 22 after inversion. However, when the inverted light receiving unit 22 is used, a region M ′ in which the depth can be measured and a region N in which the depth cannot be measured due to a mechanism in which there is a region that cannot be measured due to the triangulation laser displacement meter. 'And exist. The regions M ′ and N ′ are regions obtained by rotating the regions M and N when the light receiving unit 22 before inversion is used by 180 °. Therefore, the data of the region N (missing data) that cannot be measured by the light receiving unit 22 before inversion can be supplemented with the data of the region M ′ that can be measured by the light receiving unit 22 after inversion. Then, the data (missing data) of the area N ′ that cannot be measured can be supplemented with the data of the area M that can be measured by the light receiving unit 22 before inversion. However, depending on the positional relationship between the light emitting unit 21 and the light receiving unit 22 and the width and depth of the tire groove 110, there may be a region where data is lost even if measurement is performed at any light receiving unit 22 before and after inversion.

-Storage part The storage part 60 memorize | stores the data (reference | standard data and inversion data) of the depth of the tire groove 110 acquired with the laser displacement meter 20. FIG. The reference data is data obtained by measurement by the light receiving unit 22 before inversion, and the inversion data is obtained by the inverted light receiving unit 22 in which the position of the light receiving unit 22 when the reference data is acquired is inverted by the inversion unit. Data obtained by measurement. Specifically, the storage unit 60 stores data on the depth of the tire groove 110 acquired by the laser displacement meter 20 and stores the position of the tire groove 110 detected by the rotary encoder 13 of the rotation mechanism 10. .

  The storage unit 60 stores data (raw data) acquired by the laser displacement meter 20, and also stores processing data such as correction data corrected by a correction unit, which will be described later, and synthesized data combined by a data combining unit.

Data synthesizer The data synthesizer 70 replaces the reference data and the inverted data in place of the missing data when there is missing data due to the laser displacement meter 20 in one of the reference data and the inverted data. The other data is used to create composite data by combining the reference data and the inverted data. The specific processing of this data synthesizing unit will be described in detail in the description of the tire groove depth measuring method described later.

Correction unit Reference data and inverted data (raw data that has not been processed) acquired by the laser displacement meter 20 are errors due to measurement (such as those caused by rotational deviation of the tire 100 by the rotation mechanism 10), tire radii, etc. Errors due to directional runout (RRO: radial runout) and lateral runout (axial direction) of the tire (LRO: lateral runout) occur. Therefore, it is preferable to include a correction unit 80 that corrects errors generated in the reference data and the inverted data. The correction unit 80 is generated in the circumferential direction of the tire 100, a width direction correction unit 81 that corrects an error generated in the width direction of the tire 100, a radial direction correction unit 82 that corrects an error generated in the radial direction of the tire 100. And a circumferential direction correction unit 83 that corrects the error. The data synthesis unit 70 synthesizes the reference data corrected by at least one of the width direction correction unit 81, the radial direction correction unit 82, and the circumferential direction correction unit 83 and the corrected inverted data. In addition, the correction unit includes a reproduction correction unit 84 that reproduces the state of the tire 100 (particularly, the surface state other than the tire groove 110) based on the combined data obtained by the data combining unit 70. Specific processing of each correction unit will be described in detail in the description of the tire groove depth measurement method described later.

Others An image processing unit (not shown) that performs image processing on data acquired by the laser displacement meter 20, data corrected by the correction unit 80, data synthesized by the data synthesis unit 70, and the like is provided. Can do. Since the reference data and the inverted data acquired by the laser displacement meter 20 are values measured by the light receiving unit 22 at positions where the incident light 21L is inverted with respect to the tire groove 110, the image data is used as it is. The images are reversed from each other. Therefore, when creating image data, it is preferable that the image processing unit is provided with a left / right reversing unit, and either the reference data or the reversed data is reversed left / right with respect to the central axis in the width direction. Moreover, the display part 90 which displays the data acquired by the laser displacement meter 20, the data correct | amended by the correction | amendment part, the data synthesize | combined by the data synthetic | combination part, the image processed by the image process part, etc. can be provided. The correction unit 80, the data synthesis unit 70, the image processing unit, and the storage unit 60 are incorporated in a computer, and a display unit 90 is connected to the computer.

[Tire groove depth measurement method]
A method for measuring the depth of the tire groove 110 of the tire 100 using the tire groove depth measuring apparatus 1 will be described. The tire groove depth measurement method according to the first embodiment includes the following reference data acquisition step, inverted data acquisition step, and data synthesis step. Further, the first embodiment includes a correction process for correcting the reference data obtained in the reference data acquisition process and the inverted data obtained in the inverted data acquisition process. In this example, the tire groove 110 of the tire 100 includes two longitudinal grooves 111 and 111 formed in parallel in the circumferential direction with the center in the width direction, and the tire groove 110 on the outer side of the longitudinal grooves 111 and 111. A description will be given of an example in which a plurality of lateral grooves 112,... Formed substantially perpendicular to the circumferential direction are provided (see FIG. 6) and the depths of these tire grooves 110 are measured. Below, the concrete process of each process is demonstrated.

Reference data acquisition step In the reference data acquisition step, the tread surface of the tire 100 is irradiated with incident light 21L from a predetermined direction, and reflected light 22L with a predetermined angle with respect to the incident light 21L is received by the light receiving unit 22. This is a step of acquiring the depth data of the tire groove 110. In the reference data acquisition step, the tire 100 is attached to the rotation mechanism 10 and measurement is performed in a state where the tire 100 is rotated about its central axis, and a two-dimensional array of data groups corresponding to the width direction and the circumferential direction of the tire 100 is measured. Is getting.

  In this example, the incident light 21L is irradiated so as to pass through the rotation shaft 12 of the rotation mechanism 10 to which the tire 100 is attached, and the reflected light 22L reflected at a predetermined angle in the circumferential direction of the tire 100 with respect to the incident light 21L. Was received by the light receiving unit 22 and measured.

Inversion data acquisition process In the inversion data acquisition process, the relative position of the light receiving unit 22 with respect to the tire 100 is set to a position inverted from the position of the light receiving unit 22 in the reference data acquisition process with the incident light 21L interposed therebetween, and the tire groove This is a step of acquiring data having a depth of 110. Also in the reverse data acquisition process, the tire 100 is attached to the rotation mechanism 10 and the measurement is performed in a state where the tire 100 is rotated about its central axis, and the data group is a two-dimensional array corresponding to the width direction and the circumferential direction of the tire 100. Is getting.

  In the reverse data acquisition step, the relative position of the light receiving unit 22 with respect to the tire 100 is reversed from the position of the light receiving unit 22 in the reference data acquisition step. For this inversion, the inversion unit 30 in the tire groove depth measuring device 1 is used. The light receiving unit 22 can be easily reversed by rotating the light receiving unit 22 about 180 ° by the reversing unit 30. By changing the arrangement of the light receiving unit 22, the measurement target tire 100 can remain attached to the rotating mechanism 10, so that the replacement work of the tire 100 can be omitted, and the displacement caused by the replacement can be prevented.

  The rotation direction of the tire 100 may be the same direction as the rotation direction of the tire 100 in the reference data acquisition step, or may be a reverse direction. The starting position in the circumferential direction of the tire 100 that acquires the inverted data may be matched with the starting position in the circumferential direction of the tire 100 that acquires the reference data. By matching the acquisition start positions of both data, it is easy to synthesize the reference data and the inverted data in the data synthesis process described later. When providing reference points 201 and 202 such as bolts in the circumferential direction of the tire 100 (see FIG. 6, details will be described later), in the data synthesis step, the reference data and the inverted data correspond to each other by combining the bolts. Since the data can be synthesized by position, it is not necessary to match the data acquisition start position in the data acquisition process.

・ Data synthesis process The data synthesis process compares the reference data obtained in the reference data acquisition process with the inverted data obtained in the inverted data acquisition process, and combines the reference data and the inverted data into the tire groove data. This is a process of depth. When combining the reference data and the inverted data, if there is missing data due to the measurement method of the laser displacement meter in one of the reference data and the inverted data, the other data of the reference data and the inverted data is substituted for the missing data. Is adopted.

  There are two patterns as a method of combining the reference data and the inverted data. The first pattern is a form in which composite data based on one of reference data and inverted data is created. The procedure of the first pattern will be described, for example, based on reference data. When there is missing data (indicated by an error or zero value) in the depth data in the reference data, the inverted data corresponding to the position of the tire groove 110 of the missing data is adopted (replaced) instead of the missing data. . At this time, the inverted data adopted may be a real value or may be missing data. Therefore, even if the missing data is replaced with inverted data, the missing data in the reference data may be a real value or may remain as missing data. In any case, in the first pattern, the composite data is data in which only missing data is inverted among the reference data, and real values other than the missing data are reference data. Inversion data may be used as the basic data.

  In the second pattern, when there is missing data in one of the reference data and the inverted data, the other data of the reference data and the inverted data is used instead of the missing data. When both the inverted data and the inverted data are real values (both are not missing data), the average value of the reference data and the inverted data is adopted. In the second pattern, the reference data and the inverted data are collated for each position of the tire groove 110, and if both the reference data and the inverted data are real values, the average value is the position of the tire groove 110 collated. Composite data is created as the depth of the tire groove 110 at. If there is missing data in one of the reference data and the inverted data, the value is adopted unless the other of the reference data and the inverted data is missing data. When both the reference data and the inverted data are missing data, the depth at the position of the tire groove 110 is assumed to be missing data.

Correction process The reference data and reverse data (raw data that has not been processed) acquired by the laser displacement meter 20 include errors due to measurement (such as those caused by rotational deviation of the tire 100 by the rotation mechanism 10), and RRO of the tire. And errors due to LRO occur. Therefore, it is preferable to provide a correction process for correcting the error for each of the reference data and the inverted data. The correction process includes a width direction correction process for correcting an error generated in the width direction of the tire 100, a radial direction correction process for correcting an error generated in the radial direction of the tire 100, and an error generated in the circumferential direction of the tire 100. And a circumferential direction correction step for correction. In the data composition step described above, the reference data corrected by performing at least one correction step of the width direction correction step, the radial direction correction step, and the circumferential direction correction step, and the similarly corrected inverted data may be combined. preferable. Moreover, it is preferable to provide the reproduction correction process which reproduces the state of the tire 100 based on the synthetic data obtained at the data synthesis process. Each correction process is not essential, and any correction process may not be performed, any one correction process may be performed, and several correction processes may be combined.

  The flow of the tire groove depth measuring method in the case where the correcting step is provided will be described with reference to the flowchart showing the procedure of the tire groove depth measuring method of FIG. First, reference data is acquired by a reference data acquisition step (S1). This reference data is stored in the storage unit 60. This reference data is corrected (width direction correction step, radial direction correction step). In performing the correction, a reference point for correction is set (S2). The reference point for correction will be described in detail in a width direction correction step and a radial direction correction step described later. Based on this reference point, the reference data is corrected to generate corrected reference data (S3). The corrected reference data is stored in the storage unit 60. Next, reverse data is acquired by a reverse data acquisition step (S4). The inverted data is stored in the storage unit 60. This inverted data is also corrected (width direction correction step, radial direction correction step). In performing the correction, a correction reference point is set in the same manner as the correction of the reference data (S5). Based on this reference point, the inverted data is corrected to create inverted data with correction (S6). The corrected inverted data is stored in the storage unit 60. Correction is performed when combining the reference data with correction and the inverted data with correction (circumferential correction step). In performing the correction, a reference point serving as a reference for synthesis is set (S7). The reference point for correction will be described in detail in the circumferential direction correction step described later. Based on this reference point, the reference data with correction and the inverted data with correction are combined by the data combining step (S8). The corrected combined data is stored in the storage unit 60. Finally, the composite data is corrected so as to reproduce the surface state of the tire other than the tire groove to the state before correction in the reference data and the inverted data (reproduction correction step). In performing this correction, data to be reproduced (whether reference data or inverted data) is set (S9). Based on the set data, reproduction data is created by reproducing the surface state of the synthesized data other than the tire groove to the surface state of the tire 100 as the test object (S10). The corrected reproduction data is stored in the storage unit 60. Details of each correction step will be described below.

.. Width Direction Correction Step The width direction correction step is a step of correcting a data shift in the width direction of the tire 100. In performing the correction in the width direction, in the reference data acquisition step and the inverted data acquisition step, data is acquired over the entire circumference of the tire 100 while rotating the tire 100. Then, in at least one of the reference data and the inverted data, correction is performed by selecting a position to be a reference point in the width direction of the tire 100 and rearranging the data in the width direction so that the reference points are all aligned (aligned) in the circumferential direction. Do. As the reference point, a longitudinal groove 111 (see FIG. 6) formed in the circumferential direction of the tire 100 can be used. The vertical groove 111 is usually formed straight in the circumferential direction of the tire 100. Therefore, when the tire 100 is developed in the circumferential direction, the longitudinal grooves 111 should be arranged straight. However, when a deviation occurs in the width direction due to a mounting error of the tire 100 or a blurring of the tire 100 during rotation, the longitudinal groove 111 developed in the circumferential direction does not become straight. Therefore, paying attention to the vertical groove 111 developed in the circumferential direction, and correcting the vertical groove 111 to be straight, the data shift in the width direction of the tire 100 is corrected. This width direction correction step may be performed on at least one of the reference data and the inverted data, and is preferably performed on both data.

In performing the width direction correcting step, the vertical groove 111 is set as a reference point. As this setting, when there are a plurality of vertical grooves 111, it is possible to select which vertical groove 111 is used as a reference point. By setting the reference point, specific data of the selected vertical groove 111, for example, two points constituting the opposite corners of the opening edge of the tire groove 110 (here, P _n and P _{n + 1} : n described later are A positive natural number) is extracted as a reference point. This reference point is used for width direction correction and radial direction correction described later.

The processing in the width direction correcting step will be described below with reference to FIG. 4 (arrow T indicates the circumferential direction and arrow W indicates the width direction). The right view of FIG. 4 is a cross-sectional view of the vertical groove 111 at a position arbitrarily selected along the circumferential direction of the tire 100 shown in the left view (here, three points are selected as an example). The left side of the right diagram of FIG. 4 shows the vertical groove 111 before correction, and the right side shows the vertical groove 111 after correction. When the tire 100 is displaced in the width direction, the center line of each vertical groove 111 does not become straight as shown on the left side of the right diagram of FIG. Therefore, when the positions P ₁₁ -P ₁₂ , P ₂₁ -P ₂₂ , and P ₃₁ -P ₃₂ where the gradients change from the bottom 110b to the vertical grooves 111 at the respective positions are extracted as the reference points, their respective center lines A ₁ , A ₂ and A ₃ are derived. As shown on the right side of the right diagram of FIG. 4, the correction is performed by rearranging the data in the circumferential direction of the tire 100 with the center lines A ₁ , A ₂ , A ₃ as a straight line. In addition, the positions P ₁₁ , P ₂₁ , and P ₃₁ may be a straight line, and the positions P ₁₂ , P ₂₂ , and P ₃₂ may be a straight line.

  Here, an example in which the longitudinal groove 111 formed in the circumferential direction of the tire 100 is used as the reference point has been described, but a member independent of the tire 100 may be used. For example, the tire 100 may be rotated in a state where a disc-shaped reference plate is disposed on the side edge of the tire 100. What is necessary is just to set the surface and each part of this reference | standard board as a reference point.

.. Radial direction correction step The radial direction correction step is a step of correcting a data shift in the radial direction of the tire 100. In performing the correction in the radial direction, in the reference data acquisition step and the reverse data acquisition step, data is acquired over the entire circumference of the tire 100 while rotating the tire 100. Then, in at least one of the reference data and the inverted data, a position serving as a reference point is selected in the radial direction of the tire 100, and the radial data is corrected so that the reference point is constant over the entire circumference. As the reference point, a longitudinal groove 111 (see FIG. 6) formed in the circumferential direction of the tire 100 can be used. The vertical groove 111 is usually formed straight in the circumferential direction of the tire 100. Specifically, as shown in FIG. 5, an intersection of a line portion connecting positions P ₁₁ -P _{12 where the} slope changes from the bottom 110 b of the tire groove 111 and the center line A ₁ of P ₁₁ -P ₁₂ , looking at the distance _{h 1} between the light emitting portion 21 (the laser displacement meter 20). If the tire 100 is a perfect circle and is properly attached to the rotating shaft 12 of the rotating mechanism 10, the distance h ₁ should be constant in the circumferential direction of the tire 100. However, the distance h ₁ is not constant in the circumferential direction of the tire 100 when a deviation occurs in the radial direction due to an attachment error of the tire 100, a blurring of the tire 100 during rotation, an error due to the RRO or LRO of the tire, and the like. Therefore, paying attention to the distance h _1, by correcting as this distance h ₁ is constant, to correct the deviation of the data in the radial direction of the tire 100. This radial direction correction step may be performed on at least one of the reference data and the inverted data, and is preferably performed on both data.

The process in the radial direction correction step will be described below with reference to FIG. 5 (arrow T indicates the circumferential direction and arrow D indicates the radial direction). The lower diagram of FIG. 5 is a cross-sectional view of the longitudinal groove 111 at a position arbitrarily selected along the circumferential direction of the tire 100 shown in the upper diagram (here, three points are selected as an example). 5 shows the vertical groove 111 before correction, and the lower side shows the vertical groove 111 after correction. When the tire 100 is displaced in the radial direction, the distance h ₁ from the light receiving unit 21 to the tire 100 is not constant (h ₁ ≠ h ₂ ≠ h ₃ ) as shown in the upper side of the lower diagram of FIG. Therefore, as shown in the lower side of FIG. 5, for example, when the distance (here, h ₁ ) at an arbitrarily selected position is extracted as a reference point, the distance (position P at a different position in the circumferential direction) is extracted. ₂₁ and a line section connecting the -P _22, the intersection and the distance _{h 2} by the center line _{a 2} of the P 21 _{-P 22,} and a line section connecting the position _P 31 _{-P 32,} the center line a of the P 31 _{-P 32 3} is corrected so that the distance h ₃ ) at the intersection with ₃ becomes the distance h ₁ . For example, the correction can be performed by subtracting the distance h ₁ from the measurement value (h ₂ or h ₃ ), subtracting the difference from the measurement value arranged in the same width direction as the measurement position, and rearranging the data. This _allows the _{h 1 = h 1 '= h} 2' = h 3 '. Although the details will be described later, the depth of the lateral groove 112 can be grasped from the data after the correction by this correction. However, if the same data is seen in the circumferential direction of the tire 100, tires other than the lateral groove 112 from the laser displacement meter 20 are obtained. The distance to the surface of 100 is substantially constant (see the upper diagram of FIG. 7).

-Circumferential direction correction process The circumferential direction correction process is a process of correcting a data shift in the circumferential direction of the tire 100. In the data synthesis process, when the reference data and the inverted data are synthesized, each data is acquired independently, so that the phase is shifted. Therefore, in the circumferential direction correction step, the phases of the reference data and the inverted data are matched. By combining the phases, the synthesis positions of the reference data and the inverted data match each other. In performing the correction in the circumferential direction, in the reference data acquisition step and the inverted data acquisition step, data is acquired over the entire circumference of the tire 100 while rotating the tire 100. Then, in each of the reference data and the inverted data, a position that becomes a reference point in the circumferential direction of the tire 100 is selected, and the circumferential data is corrected so that the reference point in the reference data matches the reference point in the inverted data. As this reference point, it is mentioned that the bolts 201 and 202 are provided in the longitudinal groove 111 (refer to FIG. 6) formed in the circumferential direction of the tire 100. Specifically, the circumferential correction is performed by combining the phases of the two data so that the bolt position of the reference data and the bolt position of the inverted data correspond to each other.

  In performing the circumferential correction process, the bolts 201 and 202 are set as reference points. One reference point in the circumferential direction may be selected, but by specifying two or more points, more accurate circumferential correction can be performed.

  Hereinafter, the processing in the circumferential direction correction step will be described with reference to FIG. 6 (the vertical arrow T indicates the circumferential direction). The upper diagram of FIG. 6 shows a reference data image 2A obtained by subjecting the reference data before correction to image processing, and a reverse data image 2B obtained by subjecting the reverse data before correction to image processing. In the reference data image 2A and the inverted data image 2B, the hatched portion of the lateral groove 112 indicates missing data. The reference data image 2A and the inverted data image 2B have different phases, and the positions of the bolts 201 and 202 are shifted. The lower diagram of FIG. 6 shows a reference data image 2A ′ obtained by performing image processing on the corrected reference data, and a reversed data image 2B ′ obtained by performing image processing on the reversed data after correction. Since the bolts 201 and 202 are set as the reference points, the reference data image 2A 'and the inverted data image 2B' are corrected so that the phases of the bolts 201 and 202 are matched with each other. When collation and synthesis are performed using the reference data as the base data in the state in which the phases are matched, the synthesis is such that the missing data of the reference data image 2A (2A ′) is complemented by the effective data of the inverted data image 2B (2B ′). A data image 2C is obtained. Here, for the sake of convenience of explanation, an example in which all missing data is complemented has been shown, but originally, the combined data depends on the positional relationship between the light emitting unit 21 and the light receiving unit 22, the width and depth of the tire groove 110, and the like. In some cases, missing data may remain. Even in that case, the region where the missing data is generated can be narrowed as compared with the case where the synthesis is not performed.

-Reproduction correction process The reproduction correction process will be described below with reference to FIG. 7 (the arrow T in the left-right direction indicates the circumferential direction). Since the composite data obtained by combining the reference data and the inverted data obtained by performing each of the correction processes described above is obtained by correcting the state of the original tire 100, the surface condition other than the tire groove 110 is usually the original tire 100. The state is different. For example, as shown in the upper diagram of FIG. 7 (cross sectional view of the lateral groove 112 arranged along the circumferential direction of the tire 100), the composite data image 2C obtained by image processing of the composite data is supplemented with the missing data of the tire groove 110. However, by performing the radial direction correcting step, the surface state other than the tire groove 110 is a flat surface having no unevenness. The original surface state of the tire 100 is an uneven surface like a pre-correction reference (reversal) data image 2D obtained by image processing of pre-correction reference data or reversal data (middle of FIG. 7). In the pre-correction reference (inverted) data image 2D, the tire groove 110 has a missing data area Em. Therefore, in the reproduction correction process, a process opposite to the process performed in the radial direction correction process is mainly performed, and the missing data of the tire groove 110 is complemented, and the surface condition other than the tire groove 110 is changed to the original tire 100. A reproduction data image 2E in a state is created (lower diagram in FIG. 7).

When performing the reproduction correction process, the reference data or the inverted data is selected as reproduction source data. In this example, reference data is selected. In the data selected by the setting of the reproduction source data, for example, two points constituting opposite corners of the opening edge of the tire groove 110 (here, Q _n , Q _{n + 1} : n described later is a positive natural number) Are extracted as reference points. Specifically, the position Q ₁₁ and Q ₁₂ changes from the bottom 110b of rising gradient of the respective transverse groove 112 is extracted as a reference point, the position as a base point, using the synthesis data images 2C value of the transverse grooves 112, it A reproduction data image 2E is created using the pre-correction reference data image 2D for the surface values other than. By doing so, it is possible to reproduce the surface state of the tire 100 to the original state of the tire 100, and it is possible to grasp the wear form such as heel and toe wear and feather edge wear. If only the depth of the tire groove 110 is measured, this reproduction correction step can be omitted.

-Effect The tire groove depth measurement method according to the first embodiment is such that, even if there is missing data in the reference data, the inverted data corresponding to the position of the tire groove 110 where the missing data is confirmed is not missing. The missing data of the reference data can be complemented with the inverted data. Therefore, even if missing data occurs in each of the reference data and the inverted data, the reference data and the inverted data can be combined to complement each other and to obtain a precise tire groove depth. it can. This is because the light receiving unit 22 used for acquiring the reference data and the light receiving unit 22 used for acquiring the inverted data are reversed from each other with the incident light 21L as viewed from the tire groove 110. Because there is. That is, the depth of the tire groove 110 is measured in different directions facing each other across the incident light 21L as viewed from the tire groove 110.

  Since the tire groove depth measuring method of the first embodiment can easily obtain composite data simply by reversing each other with the incident light 21L as viewed from the tire groove 110, one light receiving unit 22 (laser It can be measured by the displacement meter 2), and a highly accurate tire groove depth can be efficiently obtained while the structure is simple.

  The tire groove depth measurement method according to the first embodiment creates composite data using reference data obtained in the reference data acquisition step and correction data obtained by correcting the reverse data obtained in the reverse data acquisition step. Thus, it is possible to correct an error caused by a tire being shifted due to the measurement, and to obtain a tire groove depth with high accuracy.

<< Embodiment 2 >>
In the first embodiment, the light receiving unit 22 used when acquiring the reference data and the light receiving unit 22 used when acquiring the inverted data are reversed with respect to the incident groove 21L as viewed from the tire groove 110. The example which uses the inversion part 30 was demonstrated as the method of setting it as a position. In addition, by replacing the tire 100, the light receiving portions 22 can be reversed with respect to the incident light 21L as viewed from the tire groove 110. When replacing the tire 100, the front and back of the tire 100 are reversed with respect to the rotating shaft 12 of the rotating mechanism 10. With this method, it is not necessary to move the light receiving unit 22 (laser displacement meter 2), and thus the rotating unit 30 can be omitted.

  The tire groove depth measurement method of the present invention can be suitably used for confirming the tire wear state by measuring the groove depth on the tire surface.

DESCRIPTION OF SYMBOLS 1 Tire groove depth measuring apparatus 10 Rotating mechanism 11 Wheel 12 Rotating shaft 13 Rotary encoder 20 Laser displacement meter 21 Light emission part 21L Incident light 22 Light receiving part 22L Reflected light 30 Inversion part 31 Inversion axis 60 Storage part 70 Data composition part 80 Correction part DESCRIPTION OF SYMBOLS 81 Width direction correction | amendment part 82 Radial direction correction | amendment part 83 Circumferential direction correction | amendment part 84 Reproduction correction | amendment part 90 Display part 100 Tire 110 Tire groove 111 Vertical groove 112 Horizontal groove 110b Bottom part 201,202 Bolt (reference point)
2A, 2A ′ reference data image 2B, 2B ′ inverted data image 2C composite data image 2D reference data image before correction 2E reproduction data image Em missing data area

Claims (2)

Using a laser displacement meter, a depth measurement method of the tire grooves for measuring the depth of the groove in the surface of the tire,
The laser displacement meter is a two-dimensional laser displacement meter,
While rotating the tire around its rotation axis, irradiate the tread surface of the tire with incident light from a predetermined direction, and receive reflected light at a predetermined angle with respect to the incident light with a light receiving unit, A reference data acquisition process for acquiring tire groove depth data;
While the relative position of the light receiving unit with respect to the tire is a position that is reversed with the incident light sandwiched from the position of the light receiving unit in the reference data acquisition step , while rotating the tire around its rotation axis, An inversion data acquisition step of acquiring data of the depth of the tire groove;
The reference data obtained in the reference data acquisition step is compared with the inverted data obtained in the inverted data acquisition step, and one of the reference data and the inverted data is caused by the measurement method of the two-dimensional laser displacement meter. If there is missing data to be used, the other data of the reference data and the inverted data is used instead of the missing data, and the data obtained by combining the reference data and the inverted data is the depth of the tire groove. A tire groove depth measurement method comprising: a synthesis step.   The tire groove depth measurement method according to claim 1, further comprising at least one of the following requirements (A) to (D).
  (A) In at least one of the reference data and the inverted data, a position that is a first reference point in the width direction of the tire is selected, and the first reference point is aligned with the circumferential direction of the tire. A width direction correction step for correcting rearrangement of data in the tire width direction is provided.
  In the data synthesis step, the corrected data obtained in the width direction correction step is used for collation.
  (B) A position to be a second reference point in the radial direction of the tire is selected in at least one of the reference data and the inverted data, and the second reference point is constant over the entire circumference of the tire. A radial direction correcting step for correcting the radial data of the tire is provided.
  In the data synthesis step, the corrected data obtained in the radial direction correction step is used for verification.
  (C) In each of the reference data and the inverted data, a position that becomes a third reference point in the circumferential direction of the tire is selected, and a third reference point in the reference data and a third reference point in the inverted data And a circumferential direction correction step of correcting the circumferential data of the tire so as to match.
  In the data synthesis step, the corrected data obtained in the circumferential direction correction step is used for verification.
  (D) using the synthesized data obtained in the data synthesizing step and one selected data selected from the reference data and the inverted data, the tire groove depth profile uses the synthesized data, and The uneven profile on the surface of the tire other than the tire groove includes a reproduction correction step of creating reproduction data using the selection data.

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