METHOD FOR MEASURING DEPTH OF MAIN GROOVE IN TIRE ROTATION DIRECTION AND DEVICE FOR MEASURING DEPTH OF MAIN GROOVE IN ROTATION DIRECTION USING THE SAME

To provide a device for measuring the depth of a main groove (circumferential main groove) in the tire rotation direction formed on the tread surface of a tire removed from a vehicle.SOLUTION: Disclosed is a method for measuring the depth of a main groove in the rotation direction which includes steps of: irradiating at least two different places on the tread surface of a tire with line laser light; acquiring picked-up images of the line laser light for each place; detecting light-cutting line coordinates which are a coordinate of an image of the line laser light for each picked-up image; calculating the groove depths formed on the tread surface based on triangulation from each light-cutting line coordinate; and determining that the grooves whose coordinates of the calculated groove depths in the rotation direction substantially coincide with each other are rotation direction main grooves, respectively, and determining that the groove depths are the depths of the rotation direction main groove, respectively.SELECTED DRAWING: Figure 3 【課題】車両から取り外されたタイヤのトレッド面に形成されたタイヤの回転方向の主溝（周回主溝）の深さを測定する装置を提供する。【解決手段】タイヤのトレッド面の異なる少なくとも２か所にラインレーザ光を照射し、ラインレーザ光の撮像画像をそれぞれ取得し、撮像画像のそれぞれについて、ラインレーザ光の像の座標である光切断線座標を検出し、それぞれの光切断線座標から三角測量法に基づいてトレッド面に形成された溝深さを算出し、算出された溝の深さの回転方向の座標が略一致する溝をそれぞれ回転方向主溝とし、その溝深さをそれぞれ回転方向主溝の深さと判定する。【選択図】図３