JPH0783630A - Measurement method of cross section of tread of tire - Google Patents

Abstract

PURPOSE:To execute the accurate measurement by a method wherein a mark is put on an inflection point on a border line and a reflection light of a laser light is detected so that a position of the inflection point in the width direction is calculated and a position in the thickness direction specified by a position in the width direction is calculated. CONSTITUTION:A tire tread T having a mark on an inflection point is placed on a tire member loading plate 9. A laser light from a He-Ne laser projector is cost on the top face of the tread T and the reflection light thereof is taken by a CCD camera 25 via a fourth mirror 24, then the image is integrally processed so that data of an approximate shape of a cross section of the tread T is obtained. The measurement is executed by means of upper and lower measuring devices 50, 51 in such a manner that optimum distances from the tread T are maintained. The CCD camera 25 in the measuring devices 50 specifies a position of the mark in the width direction. When the mark spans both of measuring windows, one of the measuring window having a greater analog addition value is selected so that a position of the mark in the X axis direction is specified and a position of the mark in the thickness direction is specified by an analog centroid method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the sectional shape of a tire tread and the thickness of an inflection point in a short time and with high accuracy.

[0002]

2. Description of the Related Art A tire tread is extruded from its mouthpiece by an extruder and molded. However, a predesigned mouthpiece does not always form a cross-sectional shape of a desired tread accurately, and in reality, the tread is molded. The cross-section shape is measured, and the die is adjusted based on the result to obtain a tread having a desired cross-section shape.

Measurement of the cross-sectional shape of a conventional tire tread is
Measure the tread cross-section directly using a scale or calipers, or if there is a tread cross-section shape measuring device, plot the measurement results with an XY plotter, etc. In general, the method of measuring the thickness and reading the thickness from the drawing results was performed.

[0004]

[Problems to be solved] However, when the dimensions of the tire tread are directly measured with a caliper, the tire tread itself is easily elastically deformed, so that there is a measurement error peculiar to the contact type and human error due to manual work is also avoided. Absent. In addition, since manual measurement requires a considerable amount of measurement time, production efficiency is poor.

The present invention has been made in view of the above points,
The object is to provide a method for measuring the sectional shape of a tire tread, which can promptly obtain the result of digitizing the sectional shape of the tire tread at the inflection point with high accuracy.

[0006]

In order to achieve the above object, the present invention provides a step of marking a point of inflection on a contour line along a measurement cross section of an upper surface of a tire tread with a paint having high reflectance. A step of irradiating a laser beam along the contour line and detecting the reflected light with an image element, and analyzing the image detected by the image element to identify the width direction position of the inflection point with the mark And a step of calculating the thickness direction position of the inflection point by calculating the center value in the thickness direction of the inflection point specified in the width direction position in the step by the analog center of gravity method The cross-sectional shape measurement method was used.

A mark is attached to the inflection point on the upper surface of the tire tread, and the widthwise position and the thickness of the inflection point in the tire tread can be calculated based on this mark, so that the cross-sectional shape of the tire tread is high. It can be digitized and measured with accuracy.

[0008]

EXAMPLES An example of the present invention shown in FIGS. 1 to 8 will be described below. FIG. 1 is a side view of an object sectional shape measuring apparatus 1 of this embodiment, and FIG. 2 is a front view thereof.

A frame 4 is constructed by arranging beams 4 on columns 3 standing on the base 2 in the front, rear, left and right directions. A plate-shaped support member 5 is erected in the front part of the base 2 in the left-right direction, a rail 6 is laid on the upper end surface of the support member 5, and a short support is provided behind the support member 5. The members 7 are erected in parallel.

A sliding base 8 in the shape of a rectangular parallelepiped, which is long on the left and right, has its front and rear legs 8a and 8b connected to the rail 6 and a supporting member 7.
It is slidably supported by and is provided. Front leg 8
a has a U-shaped cross section and is slidably fitted to the rail 6. A roller 8c is rotatably supported by a rear leg 8b. It is rotatably mounted on the end face.

The upper plate of the sliding base 8 extends rearward to form a tire member mounting plate 9. Tire member device plate 9
Has a long hole formed in the left-right direction at a place where the tread T or the like is placed.

From the bottom plate of the slide base 8, a bracket 10 is vertically hung between the front and rear support members 5 and 7,
A screw rod 11 rotatably supported in the left-right direction is screwed into a screw hole provided in the lower part of the screw rod 10, and the screw rod 11 forms a base 2
It is adapted to be rotationally driven by a motor 12 arranged on the left side of.

Therefore, when the motor 12 is driven, the screw rod 11 is rotated and the bracket having the screw hole screwed into the screw rod 11 is provided.
The slide base 8 can slide to the left and right via 10. That is, the tread T mounted on the tire member mounting plate 9 is moved left and right by driving the motor 12.

A He-Ne laser projector 20 is arranged in front of the support member 5 on the left side, with the projection port on the left side, and the first mirror 21 is arranged on the left side of the He-Ne laser projector 20 in the center. It is arranged with a degree of inclination.

The upper beam 4 occupies the front half of the support plate 26.
Is suspended horizontally by several support rods 27, and is fixed to a support plate 26 directly above the first mirror 21 to form a second mirror.
The second mirror 22 is inclined downward by 45 degrees, and is fixed to the support plate 26 behind the second mirror 22 to form the third mirror 23.
Is inclined 45 degrees forward and is inclined downward.

A tire member mounting plate 9 is provided just below the third mirror 23.
The position to put the tire member of will come. And the third mirror 23
Bracket 28 that is hung from support plate 26 further rearward
A fourth mirror 24 is provided at the lower end of the front side so as to face downward at an angle of 45 degrees, and is fixed to the base 2 directly below the fourth mirror 24 and fixed to the CCD.
A camera 25 is provided.

In the first-stage measurement, the laser light emitted from the He-Ne laser projector 20 first travels to the left, is reflected by the first mirror 21, changes its direction upward, and is reflected by the second mirror 22. Then, the light is reflected from the third mirror 23 toward the rear, travels downward, and is radiated from directly above the tread T mounted on the tire member mounting plate 9.

The reflected light of the laser light applied to the tread T is captured by the fourth mirror 24 obliquely rearward and upward, and the reflected light is sent to the CCD camera 25 below. The CCD camera 25 takes in reflected light of laser light through an optical system and receives the reflected light by an image sensor.

On the other hand, a plate-shaped support member 3 is provided behind the sliding base 8.
0 and 32 are erected in parallel in the front-rear direction, and support member 3
The rail 31 is laid on the upper end surface of 0, and the sliding support plate 3
3, the left and right leg portions 33a are slidably fitted to the rail 31, and the support member 32 is provided with the leg portions 33a via rollers 33c.
b is slidably supported and provided.

The lower measuring device 51 of the second stage is fixedly supported on the sliding support plate 33. The columns 34 are erected on the sliding support plate 33 on the left and right sides behind the measuring instrument 51, and the connection plates 35 are installed to connect the upper ends of the columns 34 to each other.

Two guide rods 36 are erected parallel to the left and right between the connecting plate 35 and the sliding support plate 33, and an elevating member 37 penetrating the two guide rods 36 is a guide rod. An upper measuring device 50 is fixed to the front surface of the guide rod 36 and is provided so as to project forward by being guided by the guide rod 36. The upper measuring machine 50 is located vertically symmetrical to the lower measuring machine 51.

A motor 39 is mounted on the connecting plate 35 via a frame 38, and a drive shaft 39a protruding downward is connected to a screw rod 40. The screw rod 40 is connected in parallel between the left and right guide rods 36. The upper and lower parts are rotatably supported by the sliding support plate 33 and the sliding support plate 33, and threadedly penetrate into a screw hole provided in the elevating member 37 on the way. Therefore, driving the motor 39 causes the screw rod 40 to rotate,
The elevating member 37, which is screwed with this, can move up and down together with the measuring device 50.

Further, both the measuring device 50 and the measuring device 51 are arranged on the sliding support plate 33, and the whole of the air cylinder 41.
(Not shown in FIGS. 1 and 2; see FIG. 5), the tire member mounting plate 9 can be positioned between the upper and lower measuring machines 50 and 51 when moving forward, When retracted, the optical paths of the laser 20 and the CCD camera 25 are opened to enable the first measurement, and the tire member mounting plate 9 is opened to facilitate mounting and removal of tire members such as the tread T.

The measuring machines 50, 51 are a unit of a projector, an optical system, a CCD camera, etc., and are housed in a case. The internal structure of the measuring machine 50 is shown in FIG.

A semiconductor laser projector is provided at the front of the case 53.
54 is arranged so as to emit laser light downward, and a lens system 55 is located below it, and a case is provided through the lens system 55.
Laser light is emitted from the left and right elongated slit holes 56 provided in the bottom wall of 53.

Behind the slit hole 56, there is a portion where a cylindrical portion 57 is obliquely recessed in the bottom wall of the case 53, and a second lens system 58 is arranged in the central axis direction of the cylindrical portion 57, and behind it. A mirror 59 is located in the camera, and a CCD camera 60 is arranged obliquely below and behind the mirror 59.

The measuring machine 50 has the above structure,
As shown in FIG. 3, the laser light emitted from the measuring device 50 is
Tread T on the tire member mounting plate 9 through the lens system 55
The reflected light is projected from the cylindrical part 57 to the case 53.
It enters the inside, passes through the lens system 58, is reflected by the mirror 59, is focused, and is captured by the CCD camera 60.

The lower measuring device 51 has a vertically symmetrical structure with the measuring device 50. The lower surface of the tread T mounted on the tire member mounting plate 9 is provided on the tire member mounting plate 9. The laser light is irradiated and reflected along the elongated hole.

The principle of measuring the cross-sectional shape of the tread T by the CCD camera of the above measuring device is that when the position (height) at which the laser light is reflected on the surface of the tread T is different, as shown in the explanatory view of FIG. Since there is a shift in the light and the location (pixel) where the image sensor 61 of the CCD camera captures this reflected light is different, by analyzing the position of this pixel,
The surface position of the tread T can be measured.

FIG. 5 shows a block diagram of the entire control system of the object sectional shape measuring apparatus 1 as described above. The personal computer 70 controls the entire system, and the analysis result is output to the CRT 71, the printer 72, the XY recorder 73, and the like.

The personal computer 70 transmits an instruction signal to the image processing device 74 and inputs and analyzes the information obtained by the image processing device 74. The image processing device 74 is a precision CCD camera of the upper side measuring machine 50 of the object sectional shape measuring device 1.
60, the precision CCD camera 62 of the lower measuring device 51 and the whole CC
The detection information of the D camera 25 is input and the laser oscillator 75 is controlled to control the semiconductor laser projector 54 and the lower measuring instrument.
The semiconductor laser projector 63 of 51 is driven.

The personal computer 70 also controls the relay circuit 76 to drive the left and right motors 12, the up and down motors 39, and the front and rear air cylinders 41, as well as the He-Ne laser projector 20.

In this way, the personal computer 70
Motor 12, 39, air cylinder 41 via relay circuit 76
To set the tread to the measurement state, the He-Ne laser projector 20 is driven by the relay circuit 76, and the semiconductor laser projectors 54, 63 are driven by the image processing device 74 via the laser oscillator 75 to emit laser light. Irradiate
The image processing device 74 obtains the detection information from the CCD cameras 25, 60, and 62 that have detected the reflected light, performs image processing, analyzes the processing result in the personal computer 70 and digitizes it, and displays it on the printer 72 or the CRT 71.

The marking operation is performed before the measurement by controlling the object sectional shape measuring apparatus 1 by the above control system. Tire tread T extruded from the extruder base
6 has a shape as shown in FIG. 6, and the upper surface of the tire tread T is composed of a series of planes having different inclinations in sequence by means of a die having a cross section formed by a polygonal line, and a plurality of variations of the inclination are changed. The curve C is formed in parallel.

On the upper surface of the tire tread T, an inflection point at which the contour line L along the measurement cross section and the inflection curve C intersect is marked linearly with a silver pen. A mark M is also attached to the edge of the tire tread T.

By the above marking operation, the tire tread T having the mark M at the inflection point is placed at a predetermined position on the tire member mounting plate 9, and first, the rough sectional shape is measured by the first measuring machine.

That is, a laser beam is emitted from the He-Ne laser projector 20 and is radiated to the upper surface (full width) of the tread through the first, second and third mirrors 21, 22, 23, and its reflected light (full width). Is captured by the CCD camera 25 through the fourth mirror 24, and the image is collectively processed to obtain approximate sectional shape data of the tread T.

The measurement accuracy in this first step is about ± 1 mm. It is sufficient to measure only the upper surface of the tread T having a trapezoidal shape with a substantially flat cross section, and the lower surface is placed on the tire member mounting plate 9 and is substantially flat. Yes, it is assumed that the distance from the measuring device 51 is within a predetermined distance.

Next, the measuring machines 50 and 51 are moved forward to sandwich the tire member mounting plate 9 and the optical axes of the laser projector 54 and the lens system 55 of the upper and lower measuring machines 50 and 51 are aligned with the measurement sectional position of the tread T. Let

Then, the tire member mounting plate 9 is moved to measure every 5 mm pitch. The motor 39 is driven every time based on the sectional shape data obtained in the measurement in the first step, and the measuring machine 50 is moved up and down. , The distance from the upper surface of the tread T to the measuring machine 50 is always controlled within an appropriate range, and the distance from the raised / lowered reference position is stored. The lower measuring device 51 is fixed and is within an appropriate distance from the lower surface of the tread T.

As described above, the measuring machines 50 and 51 always carry out the measurement while keeping the optimum distance from the tread T, and the measured value of the measuring machine 50 determines the sectional shape of the tread T in consideration of the stored moving distance. .

Here, a CCD camera for the upper measuring machine 50
The measurement visual field of 60 is 5 mm × 5 mm, and as shown in FIG. 7, a slit-shaped laser light irradiation portion Le reflected on the surface of the tread T is imaged in this visual field 80, and this slit-shaped irradiation portion Le is The inflection point of the mark M previously marked with the silver pen is reflected with high reflectance, and the reflected portion Me is imaged in a particularly large area.

The field of view 80 of the CCD camera 60 is 1 per 1 mm ^2.
A measurement window 81, which is filled with a little less than ten thousand pixels and is obtained by dividing the visual field 80 into 10 parts in the left-right direction, is used as a unit in the left-right direction. The reflection portion Me of the mark M is the measurement window.
The width of the mark M (inflection point) is the width of the mark M (inflection point) (X-axis direction) if you select the measurement window where the area occupying this large area is located. ) The position can be specified.

When the mark M straddles two measurement windows 81, the measurement window 81 having the larger analog added value is selected. In this way, the position of the mark M (inflection point) in the X-axis direction is specified, and in the selected measurement window 81, the thickness direction of the mark M (inflection point) is measured by the analog centroid method which is a generally known image processing method. The (Y-axis direction) position is specified.

That is, in the selected measurement window 81, a floating window 82 having a height of 0.5 to 1.0 mm is applied in the thickness direction with the reflected light as the center, and the light quantity in the floating window 82 is analog-added each time the movement is made.
The position of the floating window 82 where this value is larger than a certain threshold value and is maximum is determined as the position of the mark M in the Y-axis direction.

The position of the mark M in the visual field 80 in the X-axis and Y-axis directions is converted into the value of the entire XY coordinates. If the Y coordinate of the mark M attached to the edge of the tread T is set to 0, the Y coordinate of the other mark M is tread T at the corresponding inflection point.
Shows the thickness of. Measure the tread T in the width direction by 5 mm
Each time it is sent, it is performed over the entire width direction.

As shown in FIG. 8, the measurement result shows the entire cross-sectional shape by the XY recorder 73 and the position of the mark M (inflection point) with an arrow on the upper surface thereof. Further, the printer 72 sequentially prints out the XY coordinates of a plurality of marks M (inflection points).

Further, the coordinate data of the inflection point can be transferred to another device via the floppy disk. A desired tire tread T can be molded with high accuracy by adjusting the die shape of the extruder based on this coordinate data.

By marking the inflection point of the tire tread T with the mark M as described above, the inflection point can be specified and the coordinates can be measured automatically in a short time with high accuracy by making full use of image processing technology. It can be carried out.

The mark M is applied with a silver pen, but other suitable paint having a high reflectance may be applied other than the silver pen.

[0051]

According to the present invention, the inflection point on the upper surface of the tire tread is previously marked with a paint having high reflectance,
The coordinates of the inflection point in the width direction and the thickness direction can be measured with high accuracy and in a short time. Therefore, this coordinate data can be effectively utilized for adjusting and manufacturing the die of the extruder and controlling other devices.

[Brief description of drawings]

FIG. 1 is a side view of an object cross-sectional shape measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a front view in which the same portion is cut away.

FIG. 3 is a diagram showing an internal structure of a measuring machine.

FIG. 4 is a diagram illustrating a measurement principle of a measuring machine.

FIG. 5 is a block diagram of a control system.

FIG. 6 is a perspective view of a tire tread.

FIG. 7 is a diagram showing a measurement field of view of a CCD camera.

FIG. 8 is a diagram showing a cross-sectional shape of a tire tread displayed by an XY recorder.

[Explanation of symbols]

1 ... Object cross-sectional shape measuring device, 2 ... Base, 3 ... Support post, 4 ...
Beam, 5 ... Supporting member, 6 ... Rail, 7 ... Supporting member, 8 ... Sliding base, 9 ... Tire member mounting plate, 10 ... Bracket, 11 ... Screw rod, 12 ... Motor, 20 ... He-Ne laser projector , 21 ... first mirror, 22 ... second mirror, 23 ... third mirror, 24 ... fourth
Mirror, 25 ... CCD camera, 26 ... Support plate, 27 ... Support rod,
30 ... Support member, 31 ... Rail, 32 ... Support member, 33 ... Sliding support plate, 34 ... Strut, 35 ... Connecting plate, 36 ... Guide rod, 37 ... Elevating member, 38 ... Stand, 39 ... Motor, 40 ... Screw rod, 41 ... Air cylinder, 50 ... Upper measuring machine, 51 ... Lower measuring machine. 53 ... Case, 54 ... Semiconductor laser projector, 55 ... Lens system, 56 ... Slit hole, 57 ... Cylindrical part, 58 ... Lens system, 59 ... Mirror, 60
... CCD camera, 61 ... Image sensor, 62 ... CCD camera, 63 ... Semiconductor laser projector, 70 ... Personal computer, 71 ... CRT, 72 ... Printer, 73 ... XY recorder, 74 ... Image processing device, 75 ... Laser oscillator, 76 ... Relay circuit, 80 ... Field of view, 81 ... Measurement window, 82 ... Floating window, T ... Tread, C ... Deflection curve, M ... Mark, L ... Contour line.

Claims (1)

[Claims] 1. A step of marking a point of inflection on a contour line along a measurement cross section of a tire tread upper surface with a paint having high reflectance, irradiating a laser beam along the contour line, and reflecting the reflected light. A step of detecting with an image element, a step of analyzing an image detected by the image element to specify and calculating a position in the width direction of the inflection point with the mark, and an inflection in which the position in the width direction is specified in the step And a step of calculating the thickness direction position of the inflection point by indexing the center value of the points in the thickness direction by the analog center of gravity method.