JP2012154910A - Measuring device for measuring cross-sectional shape of tire tread surface and depth of tread groove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for quickly measuring a cross-sectional shape of a tread surface of a tire and a depth of a tread groove in a non-contact state.SOLUTION: The device of the present invention measures a cross-sectional shape of a tread surface of a tire, and measures a depth of a tread groove based on a measurement result. The device comprises: a guide mechanism juxtaposed near the tread surface of the tire in a width direction; a light source unit for irradiating the tread surface with single light; a digital camera for photographing a reflected bright spot of the single light; a control unit for photographing the reflected bright spot while moving the light source unit and the digital camera along the guide mechanism; and means for measuring the cross-sectional shape of the tread surface and the depth of the tread groove, based on photographed image data.

Description

Detailed Description of the Invention

Field of Invention

The present invention relates to a measuring device for measuring a cross-sectional shape of a tread surface of a tire and a depth of a tread groove, and more specifically, a cross-sectional shape of a tire tread surface that can easily measure the cross-sectional shape of the tread surface and the depth of the tread groove without contact, and The present invention relates to a tread groove depth measuring device.

Generally, since the groove on the tire tread surface is relatively narrow and deep, a physical contact method using a depth gauge or the like is often employed. This is because the groove shape is not uniform and there are various patterns such as waviness, and this is because it is the most reliable and simple method for measuring a height difference of several mm to several tens of mm with sufficient accuracy. . However, the contact method is likely to cause measurement errors due to factors such as the probe insertion angle, the contact point at the bottom of the groove, and gauge reading errors. Further, an elastic body such as rubber is likely to cause deformation errors due to contact. In addition, since usually only one point can be measured at a time, it takes time and man-hours to efficiently measure a large number of measurement points. Furthermore, it is impossible to measure the cross-sectional shape of the tread surface with a depth gauge.

In addition, the conventionally known non-contact type measuring device is not limited to the tread groove, but can measure the cross-sectional shape of the tread, but is a large device and requires a dedicated installation place. Therefore, it is difficult to measure with the tire mounted on the vehicle, or even if possible, it is difficult to perform measurement easily because preparation work such as moving the vehicle to the installation location of the measuring device is necessary.

Problems to be solved by the invention

An object of the present invention is to measure the cross-sectional shape of a tread surface of a tire and the depth of a tread groove with high measurement accuracy and relatively easily regardless of the operator's experience, operation method, or tire state.

Means for solving the problem

The invention according to claim 1 is an apparatus for measuring the cross-sectional shape of the tire tread surface, and by placing the guide mechanisms close to each other in the width direction of the tire tread surface, the axis of the guide mechanism is taken as the measurement baseline along the measurement baseline. A tire tread cross-sectional shape and a tread groove depth measuring device including a moving light source device and a digital camera, and a control device for moving the light source device and the digital camera.

According to a second aspect of the present invention, a reflected bright spot is photographed while moving the light source device and the digital camera along the measurement baseline via the control device of the first aspect, and the photographed image data, the light source device, and the digital camera are photographed. And a process for measuring the depth of the tread groove while converting the accumulated analysis data into information that can be graphically displayed as a shape and displaying the shape of the tire tread surface. A tire tread cross-sectional shape and a tread groove depth measuring method.

Action

According to the present invention, when measuring the cross-sectional shape of the tire tread surface and measuring the depth of the tread groove, the guide mechanism is brought close to the axis of the tire tread surface so as to be substantially parallel to the width direction of the tire tread surface. The light source device is moved along the guide mechanism while physically maintaining a specific positional relationship between the digital camera and the digital camera, and a reflected bright spot is photographed every time a certain amount is moved. This fixed amount of movement is determined by the required measurement resolution. For example, if the required measurement resolution is 0.1 mm, at least one image is taken for each movement amount of 0.1 mm.

Since both the light source device and the digital camera move along the guide mechanism, the light source device and the digital camera move through the guide mechanism while maintaining a constant distance between the opposed surfaces of the tire tread surface and the movement axis as a reference. As a result, a certain relational expression is established between the reflected bright spot on the tread surface and the reflected bright spot image on the captured image data, with the positions of the light source device and the digital camera as variables.

The position information of the light source device and the digital camera when the reflected bright spot is photographed can be specified from the amount of movement from the measurement start point, and the photographed image data and the position information of each device are output as measurement data as a group.

From the output measurement data, from the coordinate data of the reflected bright spot with the origin of the optical axis center of the digital camera on the image data, the physical positional relationship between the light source device and the digital camera, and the positional information at the time of shooting of the light source device, Are converted into coordinates of the tire tread surface on which the reflected bright spot is generated with reference to the movement axis.

The converted measurement data is the actual size value obtained by sampling the cross-sectional shape of the tread surface with sufficient density, with the reference axis as the abscissa axis, and the coordinate value of the measurement data is plotted on the display monitor connected to the measurement controller. Then, the cross-sectional shape of the tread surface is illustrated, and the tread groove depth is calculated by calculating using the data of the top and bottom of the tread groove in the measurement data.

Embodiment of the Invention

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a moving mechanism constituted by the guide mechanism 11, the light source device 12, the digital camera 13, the drive servo motor 14, the rack gear feeder G, the movable frame 15, and the movable frame base T according to claim 1. . In FIG. 1A, the guide mechanism 11 has a structure in which both ends of a guide support bar 11a and a guide rail 11b are fixed by a back panel 11c. The light source device 12 using a laser diode and the digital camera 13 are fixed to the movable base 15 so that the irradiation optical axis passing through the center of the irradiation light and the photographing optical axis passing through the focal point of the digital camera 13 and perpendicular to the imaging surface are on the same plane. Has been. The movable gantry 15 is connected to the guide rail 11b via the movable gantry pedestal T, and the driving servo motor 14 and the rack gear feeder G mounted on the movable gantry 15 constitute a moving mechanism. In this embodiment, the moving mechanism is shared by fixing the light source device 12 and the digital camera 13 to one moving gantry 15, but the moving mechanism can be provided to the light source device 12 and the digital camera 13, respectively. . The movable gantry 15 moves while being positioned by the drive servo motor 14 from one end to the other end of the measurement area W determined by the measurement area detection sensors 16 at both ends of the measurement area W.

In the present embodiment, the movable gantry 15 moves along the guide rail 11b. The physical positional relationship between the light source device 12 and the digital camera 13 fixed to the movable gantry 15 depends on the position of the movable gantry 15 on the guide rail 11b. In this case, the captured reflected bright spot appears in all image data at a position that is moved only in the vertical direction with the axis of the guide mechanism 11 as the horizontal axis about the imaging optical axis.

FIG. 2 shows functional blocks of the measurement control device 21 that controls the light source device 12, the digital camera 13, and the drive servo motor 14. Control of blinking of the light source device 12, image capturing of the digital camera 13 and output request control of the captured image data, movement control of moving the moving base 15 to a specific position via the drive servo motor 14, and cross-sectional shape from the captured image data To measure the depth of the tread groove.

FIG. 3 shows a processing procedure executed by the measurement control device 21 according to claim 2. Details of the operation will be described below in accordance with this procedure. When a process start command is input to the measurement control device 21 from a keyboard connected to the keyboard input 213, the process is started. In the first movement command S1, the measurement control device 21 issues a movement command from the motor control output 216 to the drive servo motor 14 to move the movable base 15 to one end of the measurement area W that is the measurement start position. In the movement position confirmation process S2, the measurement control device 21 detects that the movement base 15 has moved to the measurement start position by the measurement area detection sensor 16, and confirms that the first movement command S1 has been completed.

After confirming that the movable gantry 15 is at the measurement start position, the measurement control device 21 stores the position of the movable gantry 15 as position information data, and issues a lighting command to the light source device 12 from the light source control output 214 in the photographing command S3. A shutter command and a photographed image data output command are issued from the camera control output 215 to the digital camera 13. Thereafter, it waits for the image data captured in the measurement data acquisition S4 to be input and transferred from the digital camera 13 to the image data input 212.

The light source device 12 that has received the above-described lighting command turns on the laser beam. Upon receiving the shutter command and the image data output command, the digital camera 13 captures the reflected bright spot and outputs the captured image data to the measurement control device 21.

After receiving the image data from the digital camera 13 via the image data input 212, the measurement control device 21 associates the image data with the stored position information data of the movable platform 15 as a group of measurement data.

In the coordinate conversion / correction processing S5, measurement data conversion processing described later is performed. As described above, the reflected bright spot on the image data is a position coordinate that is moved only in the vertical direction with the guide mechanism 11 as the horizontal axis, with the photographing optical axis as the center, and thus the position information data of the movable gantry 15 is used as the horizontal position. By using the coordinates, the coordinates are converted into data in the height direction at the position of the moving frame 15 on the tire tread surface. Further, the vertical position coordinate value on the above-described image data produces a parallax with respect to the true value due to the angle of deviation of the light source optical axis and the photographing optical axis. Correction processing for obtaining a difference between the true value due to the parallax and the measured value from the declination is performed to obtain the true value in the vertical direction.

Further, when the light source device 12 and the digital camera 13 are each provided with a moving mechanism as a form different from the present embodiment, the light source device 12 and the digital camera 13 are not only affected by the vertical parallax but also in the moving direction of the moving mechanism. In order to generate the corresponding horizontal parallax, the true value is obtained by performing the correction process for the vertical parallax and the correction process for the horizontal parallax.

After finishing the coordinate conversion / correction process S5, the measurement control device 21 stores and stores the measurement data subjected to the conversion process in the data storage and storage S6 in the storage unit 202.

The measurement control device 21 determines whether the measurement data received in the measurement area determination S <b> 7 is data in the measurement area W. If it is within the range of the measurement area W, the moving base 15 is moved to the next photographing point by the movement command S1. Hereinafter, the movement command S1 to the determination in the measurement area S7 are repeated until the movable gantry 15 moves outside the measurement area W.

The measurement control device 21 determines that the measurement of the tread cross section has been completed when detecting that the movable platform 15 has moved outside the measurement area W in the determination S7 within the measurement area, and is given in advance in the groove depth measurement / display S8. The tread groove depth is obtained from the measurement data stored in the storage unit 202 based on the condition for measuring the tread groove depth, and the guide mechanism 11 is set on the display monitor connected to the display monitor output 218 as the horizontal axis. The tread groove depth is displayed together with the graph display as the tread cross-sectional shape of the tire, and the measurement process is terminated.

The invention's effect

Since the present invention can be measured by simply juxtaposing the guide mechanism in the width direction of the tire tread surface, the measurement interval between the measuring device and the tire tread surface is constant even when the tire outer diameter and the tread width are different for each tire. Can be measured with high accuracy.

Further, the measurement can be performed even when the tire is in contact with the road surface or in a lifted-up non-contact state, or when the tire is mounted on the vehicle or not. For this reason, a place for installing and measuring a large-sized measuring device is not required, and measurement work is facilitated because the installation state of the tire is not restricted.

Apparatus configuration in an embodiment of the apparatus of the present invention Measurement controller functional block diagram Process flow diagram of measurement control device

11: Guide mechanism 11a: Guide support bar 11b constituting the guide mechanism: Guide rail 11c constituting the guide mechanism: Back panel 12 constituting the guide mechanism: Light source device 13: Digital camera 14: Drive servo motor 15: Moving stand 16 : Measurement area detection sensor 21: Measurement control device G: Rack gear feeder T: Moving base pedestal S: Tire W: Measurement area

Claims (2)

A guide mechanism for juxtaposition near the tread surface of the tire, a light source device that generates a single light that irradiates the tread surface, a moving mechanism that moves the light source device to a predetermined position along the guide mechanism, and a single light A digital camera that shoots the reflected bright spot generated on the tread surface, a moving mechanism that moves the digital camera to a predetermined position within the reflected bright spot shooting range, and a measurement that controls the light source device, the digital camera, and the moving mechanism A cross-sectional shape of a tire tread and a tread groove depth measuring device including a control device. Using the apparatus of claim 1, the analysis data in which the image data obtained by photographing the reflected bright spot and the light source device and the positional information of the digital camera are associated is accumulated, and the shape of the tread surface is obtained from the accumulated analysis data, A method for obtaining the depth of the tread groove from the obtained tread surface shape.

Images