JPH10160453A - Method and device for judging external shape of tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify defective irregular sections on the surface of a tire and, at the same time, to recognize the sizes of the section and judge the defective extents of the sections. SOLUTION: When the wavelet corresponding to the frequency of an irregular waveform (extracted defective irregular waveform) based on the displacement detected by means of a displacement sensor 118 is displaced (raised or depressed) by relatively moving the measuring position of the sensor 118 on a concentric circuit on the side surface of a tire 102, a gently rising projecting section, abruptly rising projecting section, gently sinking recessed section, etc., can be expressed by disintegrating the section into planar wavelets. By comparing the waveform obtained as a result of the above-mentioned wavalet processing with a waveform (waveforms) having such a frequency that is prerecognized as a defective irregular waveform, such a waveform that is nearly equal to the frequency which is recognized as the wavelt-processed irregular waveform is extracted from obtained irregular waveforms. When the positions, sizes, shapes, etc., of detective irregular sections are recognized, whether the tire 102 is good or no good is judged in accordance with the recognized results.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for determining the outer shape of a tire for determining the state of the outer shape of the tire.

[0002]

2. Description of the Related Art As a defect detection method using a frequency analysis of a surface unevenness waveform of an object to be detected such as a tire, a method based on a fast Fourier transform has been proposed (for example, Japanese Patent Application Laid-Open No. Hei 7-111333; See JP-A-3-54407. For reference, a method based on matching with test data (see Japanese Patent Application Laid-Open No. 3-54407).
Also, a detection method based on a difference between an original waveform (measured waveform) and a delayed waveform (see JP-A-1-51122) has been proposed.

In the method using the fast Fourier transform, it is possible to remove noise (noise) included in measurement data or extract a defective portion (specify a defect position).

[0004]

However, in the method using the fast Fourier transform described above, it is not possible to determine the size of a defective portion. In addition, since the Fourier transform and the inverse transform are performed, a considerable processing time is required. Further, since the processing is repeated several times for the uneven waveform, the signal may be distorted.

In view of the above facts, the present invention provides a method and an apparatus for determining the outer shape of a tire which can identify the irregularities on the surface of the tire, recognize the size of the irregularities on the tire, and judge the degree of the defect. The purpose is to get.

[0006]

According to the first aspect of the present invention, a measuring point is set on a side surface of a tire, the measuring point is relatively moved on a concentric circle, and the tire is moved at a constant speed over the entire circumference of the tire. Generates a measurement waveform by measuring the amount of surface unevenness displacement, performs wavelet processing to classify and represent the unevenness portion included in the measurement waveform by frequency, expresses the position, size, shape of the unevenness portion, From the wavelet-processed waveform, a waveform that substantially matches a plurality of preset defect unevenness waveforms is extracted, and a defect degree is determined based on the position, size, and shape of the extracted defect unevenness portion. And

According to the first aspect of the present invention, on the side surface of the tire, the logo or the mark of the tire maker has characters or symbols indicating the size of the tire by irregularities. The irregularities are intentionally formed irregularities. On the other hand, there is a portion on the side of the tire where irregularities occur when air is injected. The unevenness occurs due to a difference in the thickness of the tire and the like, and can be referred to as a defect unevenness.

In order to detect the irregularities of the defect, a measuring point is determined, and the amount of irregularity displacement is measured over the entire circumference of the tire on a circle concentric with the measuring point.

At this time, there are few regions where the intentional unevenness does not exist over the entire circumference on the tire side surface, and as a result, one or both positions may pass through the intentional unevenness.

[0010] The measured data is converted into a measured waveform, and is compared with a known waveform corresponding to a plurality of defect irregularities, and the extracted waveform is subjected to wavelet processing. The position is on the x-axis, the frequency according to the type of unevenness is on the y-axis, and the amount of unevenness is on the z-axis. Note that a two-dimensional display may be used. In this case, the horizontal axis represents the tire position, the frequency represents the type of the defect unevenness, and the amplitude represents the magnitude. ).

At this time, the intentional uneven portion such as the tire logo mark is, for example, a convex portion, since the rising thereof is sharp, and corresponds to a high frequency convex portion when the frequency is converted. On the other hand, for example, in the case of a convex
Since it is a mountain shape with a relatively gradual rise, it corresponds to a low-frequency convex portion when frequency-converted (3 to
About 10 Hz).

Therefore, by extracting only the uneven portion in this frequency range, the defective uneven portion can be specified. After that, the degree of defect is determined based on the position, size, and shape of the concave and convex portions.

According to a second aspect of the present invention, at least a fixing means for fixing the tire, a rotation driving means for rotating the tire fixed to the fixing means at a constant speed, and a tire rotating when the rotation driving means rotates the tire. The unevenness displacement amount on the concentric circle of the side surface is one pattern, an unevenness measuring means for measuring a predetermined pattern, a filtering processing means for removing noise from a pattern measurement waveform measured by the unevenness measuring means, and Based on the measured waveform signal that has been removed, while classifying the position of the tire surface by frequency, size, wavelet processing means for performing processing to represent the shape, a plurality of predetermined defect irregularities waveform, A defect asperity extracting means for comparing a waveform subjected to wavelet processing and extracting a waveform of the defect asperity, and a defect extracted by the defect asperity extracting means; Position on the tire surface of the convex, size, based on the shape, and has a determination means for determining defective degree of the tire.

According to the second aspect of the present invention, the tire is fixed by the fixing means, and the fixed tire is rotated by the rotation driving means. In this state, the unevenness measuring means measures the amount of unevenness displacement of the tire side surface. The filtering processing means removes noise (for high frequency) due to vibration or the like during rotation of the tire, and generates a measurement waveform (original waveform).

Next, wavelet processing is performed by the wavelet processing means, and a plurality of predetermined waveforms of the defect irregularities are compared with the wavelet-processed waveform.
The defect unevenness waveform is extracted. The determining means determines the degree of defect of the tire based on the position, size, and shape of the extracted irregularities on the tire surface.

As described above, the position of a defect (unevenness) occurring on the tire surface can be grasped in a relatively short time, and the degree (size, shape) of the defect can be recognized. In addition, the processing efficiency does not need to be time-consuming because of Fourier transform or the like unlike the related art.

[0017]

FIG. 1 shows a tire shape inspection apparatus 100 (hereinafter, simply referred to as an inspection apparatus 100) according to the present embodiment.

The inspection apparatus 100 has a holder 104 as a fixing means for holding the tire 102. The holder portion 104 has a role as a wheel on which the tire 102 is mounted. After the tire 102 is mounted, air can be injected.

The holder section 104 has a pair of disk sections 106 arranged facing each other and parallel to each other. Rotary shafts 108 and 110 are coaxially mounted at the centers of the disk sections 106, respectively.

The rotating shaft 108 is connected to a rotating shaft (not shown) of the motor 112 via gears or belts (not shown) so that the driving force of the motor 112 is transmitted. The motor 112 is rotated in response to an instruction signal from the drive control unit 116 of the controller 114, and
4 can be rotated at a constant speed.

Tire 102 mounted on holder 104
Displacement sensors 118 are disposed opposite to both side surfaces (the upper and lower surfaces in FIG. 1). The displacement sensor 118 is
Two are provided on each surface, and are attached to the distal end of the support arm 120. The number of the displacement sensors 118 is not limited to two, and the larger the number, the better. However, in the present embodiment, data detected by the two displacement sensors 118 is used.

The two displacement sensors 118 attached to one support arm 120 are located along the radial direction of the tire 102 and have two different radial dimensions.

That is, as shown in FIG.
02 rotates on two circles having different radial dimensions on the side surface of the tire 102 at the same time.
Can measure the amount of irregularity displacement on both side surfaces (the total number of measurement points is four).

Here, of the side surfaces of one tire 102,
It is preferable that both measurement circles avoid a portion where intentional unevenness 122 such as a tire manufacturer's logo mark provided on the side surface of the tire 102 exists, but is not particularly limited.

In the present embodiment, the displacement sensor 118 is set so that both measurement circles do not pass through the intentionally uneven portion 122 by driving the support arm 120. The base of the support arm 120 is attached to the positioning drive unit main body 124.

The drive unit main body 124 includes the controller 11
4 that receives a signal from the drive control unit 116
The support arm 120 is moved by the driver 126 in the direction of expansion and contraction and the direction perpendicular to the axis. With the driving force of the driving section main body 124, the support arm 120 has a structure in which the support arm 120 moves in parallel in a direction approaching and leaving the tire 102.

Here, the displacement sensor 118 is
When a predetermined distance (reference position) is reached, the displacement sensor 118 outputs a laser beam and the tire 102
Receives the reflected beam from the surface. The light receiving point has a structure in which the light receiving point is planarly displaced with respect to the reference light receiving point in accordance with the unevenness of the tire surface. The amount of displacement is converted into an electric signal and output to the sensor amplifier 128. Has become.

In the sensor amplifier 128, the displacement sensor 11
8 is amplified and sent to the sampling processing unit 132 in the waveform control unit 130 in the controller 114. In the sampling processing unit 132, as shown in FIG. 3, the captured electric signal is subjected to waveform conversion to generate an original waveform (since the measurement is performed at two positions with respect to one side surface of the tire 102, the original waveform A And the original waveform B).

The original waveform A and the original waveform B are sent to the filtering section 134, respectively, and are sent to the waveform processing section 136 in a state where high-frequency noise components caused by vibrations of the tire 102 during rotation are removed. It has become.

The waveform processing unit 136 extracts a concave and convex portion through a wavelet process described in detail below. (Wavelet processing) This is a process in which a plane having time (tire position) and frequency as coordinate axes is filled with a wavelet having an inherent spread, and the signal indicates how strong each wavelet is included.

Specifically, the measurement position is relatively moved on a concentric circle on the surface of the side surface of the tire 102 (the displacement sensor 118 is fixed and the tire 102 is rotated), and the unevenness based on the displacement amount detected by the displacement sensor 118 is obtained. By displacing (elevating or depressing) the wavelet corresponding to the frequency of the waveform (extracted irregularity waveform of the defect), even with the same irregularity, a gently rising ridge, a sharply rising ridge, a gently dent, etc. , Can be represented by being decomposed into planar wavelets. (Extraction of defect unevenness) A waveform obtained by the wavelet processing is compared with a plurality of waveforms having a frequency previously recognized as the defect unevenness waveform, and the frequency recognized as the wavelet-processed unevenness waveform is compared. This is a process of extracting a waveform that substantially matches with the irregular waveform.

In this embodiment, when the position, size, shape, and the like of the concave and convex portions are recognized, pass / fail is determined according to the recognition result.

A signal from the judgment standard setting unit 140 is input to the judgment processing unit 138. In this determination standard setting unit 140, the touch panel driving unit 14
It has a function of transmitting a determination reference level and the like to the determination processing unit 138 based on the operation content of the second operation unit 142A. In addition, a result display unit 144 is connected to the determination processing unit 138, and converts the determination result of the determination processing unit 138 into a display form on the display unit 142B of the touch panel driving unit 142. Thereby, the touch panel driving unit 14
In the second display section 142B, the position and size of the concave and convex portion of the tire 102, the final determination result, and the like are displayed.

An external output terminal 146 is connected to the judgment processing unit 138, so that the judgment contents can be printed out as it is or transmitted to another computer.

It is also possible to print out as it is or send it to another computer.

The operation of this embodiment will be described below. The tire 102 to be inspected is mounted on the holder 104,
Inject air. In this state, the motor 112 is driven to rotate the holder 104.

Next, a displacement sensor 118 disposed opposite to both side surfaces of the tire 102 mounted on the holder portion 104.
Is positioned at a predetermined distance from the tire 102.

The positioning can be easily performed by operating two support sensors 120 since the two displacement sensors 118 provided for each side surface of the tire 102 are attached to one support arm 120. Can be done.

Here, when the positioning of the displacement sensor 118 is completed, the measurement is started. That is, by rotating the tire 102, it is possible to measure the amount of unevenness displacement on both sides of the tire 102 at the same time on two circles having different radial dimensions on the side surfaces of the tire 102.

The result of measurement by the displacement sensor 118 is sent to the sampling processing unit 132 via the sensor amplifier 128 to generate a waveform corresponding to the unevenness of the side surface of the tire 102. After the high-frequency noise caused by vibration during rotation or the like is removed, the waveform is sent to the waveform processing unit 136 as an original waveform A and an original waveform B.

In the waveform processing unit 136, first, the original waveform A,
When the original waveform B is fetched, wavelet processing is performed sequentially from either one. Wavelet processing results of the original waveform A and the original waveform B are expressed in a superimposed manner.

By the wavelet processing, the obtained irregularity waveform of the frequency distribution is compared with each of a plurality of types of known irregularity waveforms of defects, and a matching one is extracted. For example, FIG. 3 shows a waveform in which the original waveform A subjected to the wavelet processing is expressed two-dimensionally. This waveform includes waveforms of a plurality of frequencies, and it can be determined that a waveform having a large amplitude at the corresponding frequency has irregularities. Therefore, a plurality of uneven portions that can be generated on the surface of the tire 102 are experimentally confirmed in advance, and a waveform having a frequency corresponding to the uneven portions is generated. Each of the plurality of generated waveforms is compared with the two-dimensionally expressed waveform, and the corresponding waveform is extracted.

In the wavelet-processed waveform,
There may be intentional irregularities, and such a waveform is not extracted because of its relatively high frequency. Therefore,
Only the concave and convex portions can be extracted.

FIG. 4 is a three-dimensional representation of a wavelet-processed waveform. In this manner, the three-dimensional representation allows the uneven portions to be classified for each frequency. For example, by focusing only on 3 Hz to 10 Hz where the frequency corresponding to the defective uneven portions is concentrated, the defective uneven portions can be classified. Can be easily recognized.

Up to this point, the process is performed in the waveform processing unit 136, and thereafter, the quality of the defect unevenness is determined by the determination processing unit 138.

Next, the judgment processing section 138 judges pass / fail of the extracted defect irregularities based on a preset threshold value.

This threshold value is determined by the touch panel drive unit 14
The determination unit 140 determines the type of the tire to be inspected 102 by the operation of the second operation unit 142 </ b> A and the like, and sends it to the determination processing unit 138.

Next, based on the number of convex portions and concave portions exceeding the threshold value and their sizes and positions, the tire 10
2 is determined.

The judgment result is sent to the display section 142B of the touch panel drive section 142 via the result display section 144, and necessary information is displayed. Selection of necessary information can be arbitrarily changed depending on the conversion format in the result display unit 144.
That is, only the quality of the tire 102 may be displayed, or the number and size of the defective uneven portions may be displayed together.

Further, by connecting a personal computer or the like to the external output terminal 146, inspection result data can be accumulated and a history can be left. Further, a printer can be directly connected to the external output terminal to print out data.

As described above, in the present embodiment, it is possible to inspect the unevenness on the surface of the tire 102 without performing the Fourier transform (and the inverse transform) which requires a long time for the arithmetic processing. In addition, it is possible to distinguish the intentionally formed uneven portion 122 from the defective uneven portion, and it is also possible to recognize the size and position of the uneven portion, and to perform these operations in a relatively short time in a simple operation. Can be done with

In the present embodiment, the displacement sensor 11
Two pieces 8 are arranged on each side surface of the tire 102, but one piece may be arranged one by one, and the same displacement sensor 118 may be used to measure different radial dimension positions two or more times. Also, the measurement circle is 2
Although the number of pieces is three or more, the more the number is three or more, the higher the accuracy of the inspection result is, but the processing time becomes slower due to the increase in the amount of data. Is preferred.

In addition to a pinpoint sensor like the displacement sensor 118, a line sensor or the like can be applied.

[0054]

As described above, the method and apparatus for judging the outer shape of a tire according to the present invention specify defect irregularities on the tire surface, recognize the size of the defect irregularities, and judge the degree of defect. It has an excellent effect that it can be produced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a tire shape inspection device according to the present embodiment.

FIG. 2 is a perspective view of a tire to be inspected.

FIG. 3 is a characteristic diagram in which a wavelet processing result is expressed in a two-dimensional manner with respect to an unevenness measurement waveform.

FIG. 4 is a characteristic diagram in which a wavelet processing result is three-dimensionally expressed in the unevenness measurement waveform.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 tire shape inspection device 102 tire 104 holder unit (fixing unit) 112 motor (rotation driving unit) 114 controller 118 displacement sensor (concavo-convex measuring unit) 130 waveform control unit 132 sampling processing unit 134 filtering processing unit (filtering processing unit) 136 waveform Processing unit (wavelet processing unit, defect unevenness extraction unit) 138 Judgment processing unit (judgment unit)

Claims (2)

[Claims] 1. A measurement point is defined on a side surface of a tire, the measurement point is relatively moved on a concentric circle, and the amount of unevenness displacement of the tire surface is measured at a constant speed over the entire circumference of the tire to generate a measurement waveform. Then, wavelet processing is performed to classify and represent the irregularities included in the measured waveform by frequency, and the position, size,
Expressing the shape, extracting from the wavelet-processed waveform a waveform that substantially matches a plurality of preset defect unevenness waveforms, based on the position, size, and shape of the extracted defect unevenness portion, Determining the outer shape of the tire. 2. A fixing means for fixing at least the tire; a rotation driving means for rotating the tire fixed to the fixing means at a constant speed; The unevenness displacement amount is defined as one pattern, an unevenness measuring means for measuring a predetermined pattern, a filtering processing means for removing noise from a pattern measurement waveform measured by the unevenness measuring means, and a measurement waveform signal from which the noise has been removed. Based on the above, while classifying the position of the tire surface by frequency, the size, wavelet processing means for performing processing to represent the shape, a plurality of predetermined defect irregularities waveform, the waveform subjected to the wavelet processing Comparing the defect irregularities extracting means for extracting the waveform of the defect irregularities, and the defect irregularities extracted by the defect irregularity extracting means on the tire surface A determination unit configured to determine a defect degree of the tire based on a position, a size, and a shape.