JP3768625B2 - Tire outer shape determination method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire outer shape determination method and apparatus for determining the state of a tire outer shape.
[0002]
[Prior art]
As a defect detection method using the frequency analysis of the corrugated waveform on the surface of a detected object such as a tire, methods using fast Fourier transform have been proposed (for example, Japanese Patent Laid-Open Nos. 7-11133 and 3-54407). See the official gazette). For reference, a method based on matching with test data (see Japanese Patent Laid-Open No. 3-54407), a detection method based on a difference between an original waveform (measured waveform) and a delayed waveform (see Japanese Patent Laid-Open No. 1-51122), etc. Has been proposed.
[0003]
In the method using the fast Fourier transform, it is possible to remove noise contained in measurement data or to extract a defective portion (specify a defect position).
[0004]
[Problems to be solved by the invention]
However, the method based on the fast Fourier transform cannot directly determine the position and size of the defect portion. Further, since the Fourier transform and the inverse transform are performed, there is a problem that a considerable processing time is required. Furthermore, since the process is repeated several times on the uneven waveform, the signal may be distorted.
[0005]
In consideration of the above-described facts, the present invention can provide a tire outer shape determination method and apparatus capable of identifying a defect unevenness on a tire surface, recognizing the size of the defect unevenness, and determining the degree of defect. Is the purpose.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, two measurement points having different radial dimensions are defined at positions along the radial direction of at least one of the tire side surfaces, and the measurement point is maintained on the entire circumference of the tire while maintaining the radial dimension of the measurement points. The original waveform that is the measurement waveform that measures the uneven displacement amount of the tire surface is generated.
This is a normal waveform when the filtering processing unit removes high-frequency noise due to vibrations during rotation of the tire from the original waveform, and is measured with a displacement sensor with no irregularities on the tire surface based on each original waveform However, an approximate curve is generated, and an uneven waveform obtained by subtracting the approximate curve from each original waveform is generated. By multiplying the at least two uneven waveforms at different radial dimensions, the tire manufacturer's logo mark, In addition, the defect irregularities, which are irregularities appearing in a streak shape along the radial direction of the tire surface, in which the intentional irregularities that are irregularities that can be generated by characters and symbols representing the size are excluded, are extracted. Regarding the waveform of the defect irregularities, the quality of the tire is judged from the number of projections and depressions exceeding the threshold, the size, and the position. It is characterized in that.
[0007]
According to the first aspect of the present invention, the tire manufacturer's logo mark, and characters and symbols indicating the size are present on the side surface of the tire due to the unevenness. The unevenness is intentionally formed unevenness. On the other hand, on the tire side surface, there is a portion where unevenness occurs when air is injected. This unevenness is caused by a difference in the thickness of the tire or the like, and can be referred to as defect unevenness.
[0008]
The defect unevenness has a property of appearing in a streak pattern along the radial direction on the side surface of the tire, and therefore, at least two measurement points common to the radial direction of the tire side surface are defined.
[0009]
For example, when two positions are determined, the uneven displacement amount at the two positions is measured over the entire tire circumference while maintaining the radial dimension from the tire center at the two positions.
[0010]
At this time, there are few regions where the intentional uneven portion does not exist on the entire tire side surface, and as a result, one or both positions may pass through the intentional uneven portion.
[0011]
The measured data is converted into a measurement waveform and subtracted from the normal waveform to form an uneven waveform. In this uneven waveform, the intentional uneven portion and the defect uneven portion are mixed. Therefore, the uneven waveforms obtained at the two positions are multiplied. As a result, the intentional unevenness is 0 when it is involved in one, and is multiplied by the square when it is involved in both, which is clearly distinguished from other unevenness (defect unevenness). Waveform that can be. In particular, when the intentional uneven portion is related only to one side, the unevenness is 0, and therefore only the defective uneven portion is extracted.
[0012]
By determining the degree of the result based on the waveform of the defect uneven portion generated in this way, it is possible to recognize not only the position of the unevenness but also the size and shape.
[0013]
According to a second aspect of the invention, there is provided at least one of 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 at the time of rotation of the tire by the rotation driving means. Concavity and convexity measurement that obtains the original waveform by measuring the amount of concavity and convexity displacement at the two position points regardless of contact or non-contact, corresponding to two positions with different radial dimensions at the side surface and the radial direction of the tire side surface. Means, filtering processing means for removing high-frequency noise caused by vibrations during rotation of the tire from the original waveform, and normal when measured with a displacement sensor in a state where there is no unevenness on the tire surface based on each original waveform an approximate curve generating means for generating respective approximate curves where a waveform, each near where a normal waveform signal generated by the approximate curve generating means Subtracting from each original waveform of the curve is filtering processing in the filtering processing means, characters and symbols representing a radial appearing streaked along the irregularities is defective unevenness of tire surface, and the tire manufacturer's logo, and the size Multiplying the concavo-convex waveform signal including the intentional concavo-convex that is the concavo-convex that can be generated by the calculation means by multiplying the concavo-convex waveform signal at two positions having different radial dimensions obtained by the arithmetic means, The number of protrusions and recesses exceeding a threshold, and the size thereof, based on the extraction waveform signal extracted by the extraction means, the extraction means that eliminates the uneven portions and extracts only the defect uneven portions, And determining means for judging whether the tire is good or bad from the position.
[0014]
According to the invention described in claim 2, the tire is fixed by the fixing means, and the tire fixed by the rotation driving means is rotated at a constant speed. In this state, the unevenness measuring means measures unevenness displacement amounts at at least two positions on the tire side surface. The filtering processing means removes noise (high-frequency component) caused by vibration during tire rotation and generates a measurement waveform (original waveform).
[0015]
Next, a normal waveform is generated by the approximate curve generation means, and an uneven waveform signal is obtained by subtracting the normal waveform from the measured waveform.
[0016]
Subsequently, in order to extract a defect uneven | corrugated part with an extraction means, the uneven | corrugated waveform measured in 2 positions is multiplied. Based on the waveform (uneven waveform signal) output as a result of this multiplication, the determination means recognizes the position, size, and shape of the uneven portion on the tire side surface and determines the degree of defect.
[0017]
Thus, since the position of the defect (unevenness) occurring on the tire surface in a relatively short time can be grasped, and the degree (size, shape) of the defect can also be recognized, As described above, the processing efficiency does not take time for the Fourier transform and the work efficiency is improved.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a tire shape inspection apparatus 100 (hereinafter simply referred to as inspection apparatus 100) according to the present embodiment.
[0019]
The inspection apparatus 100 includes a holder unit 104 as a fixing unit that holds the tire 102. The holder portion 104 has a role as a wheel for mounting the tire 102, and can inject air after the tire 102 is mounted.
[0020]
In the holder portion 104, a pair of disk portions 106 are arranged opposite to each other and in parallel, and rotating shafts 108 and 110 are coaxially attached to the respective centers.
[0021]
The rotating shaft 108 is connected to a rotating shaft (not shown) of the motor 112 via a gear, a belt, or the like (not shown) so that the driving force of the motor 112 is transmitted. The motor 112 is rotated in accordance with an instruction signal from the drive control unit 116 of the controller 114 so that the holder unit 104 can rotate at a constant speed.
[0022]
Displacement sensors 118 are disposed to face both side surfaces (in FIG. 1, the upper and lower surfaces) of the tire 102 attached to the holder unit 104. Two displacement sensors 118 are provided on each surface and attached to the tip of the support arm 120.
[0023]
Two displacement sensors 118 attached to one support arm 120 are two positions with different radial dimensions at positions along the radial direction of the tire 102.
[0024]
That is, as shown in FIG. 2, by rotating the tire 102, it is possible to measure the uneven displacement amount on both sides of the tire 102 at the same time on two circles having different radial dimensions on the side surface of the tire 102. (4 measurement points in total).
[0025]
Here, out of the side surfaces of one tire 102, one measurement circle passes through a portion where there is an intentional concavo-convex portion 122 such as a tire manufacturer logo mark provided on the side surface of the tire 102, and the other measurement circle. The circle is set so as to pass through a portion where the intentional uneven portion 122 does not exist at all.
[0026]
This setting is made by driving the support arm 120. The base of the support arm 120 is attached to the positioning drive unit main body 124.
[0027]
The drive unit main body 124 is provided with a driver 126 that receives a signal from the drive control unit 116 of the controller 114, and the driver 126 moves the support arm 120 in the telescopic direction and the direction perpendicular to the axis. The support arm 120 has a structure that translates in a direction toward and away from the tire 102 by the driving force of the driving unit main body 124.
[0028]
Here, when the displacement sensor 118 reaches a predetermined distance (reference position) with respect to the tire 102, the displacement sensor 118 outputs a laser beam and receives a reflected beam from the surface of the tire 102. The light receiving point has a structure that is displaced in a plane with respect to the reference light receiving point according to the unevenness of the tire surface, and the displacement is converted into an electric signal and output to the sensor amplifier 128. It has become.
[0029]
The sensor amplifier 128 amplifies the electric signal from the displacement sensor 118 and sends it to the sampling processing unit 132 in the waveform control unit 130 in the controller 114. As shown in FIG. 3, the sampling processing unit 132 converts the waveform of the captured electric signal to generate an original waveform (since the measurement is performed at two positions with respect to one side surface of the tire 102, each of the original waveform A And the original waveform B).
[0030]
Each of the original waveform A and the original waveform B is sent to the filtering processing unit 134, and is sent to the waveform processing unit 136 in a state in which a high-frequency noise due to vibration during rotation of the tire 102 is removed. Yes.
[0031]
In the waveform processing unit 136, the defect uneven portion is extracted through processing such as creation of an approximate curve, which will be described in detail below, calculation of a difference between the original waveform and the approximate curve, and multiplication of the result. Yes.
(Approximate curve)
This is a normal waveform when measured by the displacement sensor 118 with no irregularities on the tire surface, and is generated based on the original waveform A and the original waveform B (see FIG. 3).
(Difference between original waveform and approximate curve)
This is a calculation necessary for extracting the uneven portion.
[0032]
When the approximate curve is generated, each original waveform has a difference between the approximate curve and the presence / absence and size of the unevenness, and therefore, the curve obtained by subtracting the approximate curve from the original waveform A and the original waveform B. (Uneven waveform) is generated (see FIGS. 4A and 4B).
(Multiplication of subtraction result)
This is an operation necessary for extracting a defective uneven portion excluding the intentional uneven portion 122 (logo mark or the like) of the uneven portion (see FIG. 5).
[0033]
Either one of the concavo-convex waveform based on the original waveform A and the concavo-convex waveform based on the original waveform B includes an intentional concavo-convex portion 122 such as a logo mark as a measurement point. At this time, since the other passes through a measurement point that does not include the intentional uneven portion 122, the intentional uneven portion 122 can be set to 0 by multiplying them. On the other hand, since the defect irregularities appear uniformly in the radial direction, displacement in the same direction (concave or convex) appears at the same measurement point. The amount can be emphasized.
[0034]
In the present embodiment, after the defect uneven portion is extracted, it is classified into a concave portion and a convex portion, and a signal corresponding to each waveform is sent to the determination processing portion 138, and the quality is determined according to the size. It comes to judge.
[0035]
A signal from the determination standard setting unit 140 is input to the determination processing unit 138. The determination standard setting unit 140 has a function of sending a determination reference level and the like to the determination processing unit 138 based on the operation content by the operation unit 142A of the touch panel drive unit 142. In addition, a result display unit 144 is connected to the determination processing unit 138, and the determination result in the determination processing unit 138 is converted into a display form by the display unit 142B of the touch panel drive unit 142. Thereby, on the display part 142B of the touch panel drive part 142, the position and size of the defect uneven part in the tire 102, the final determination result, and the like are displayed.
[0036]
Further, an external output terminal 146 is connected to the determination processing unit 138, and the determination content can be printed out as it is or transmitted to another computer.
[0037]
The operation of this embodiment will be described below.
A tire 102, which is an object to be inspected, is mounted on the holder portion 104, and air is injected. In this state, the motor 112 is driven to rotate the holder unit 104.
[0038]
Next, the displacement sensor 118 disposed facing both side surfaces of the tire 102 mounted on the holder portion 104 is positioned at a position away from the tire 102 by a predetermined distance.
[0039]
This positioning is easily performed by operating the support arms 120, since the two displacement sensors 118 disposed on each side of the tire 102 are attached to one support arm 120. Can do.
[0040]
Here, when the positioning of the displacement sensor 118 is completed, the measurement is started. That is, as the tire 102 rotates, the amount of uneven displacement on both side surfaces of the tire 102 can be measured at the same time on two circles having different radial dimensions on the side surface of the tire 102.
[0041]
The measurement result obtained by the displacement sensor 118 is sent to the sampling processing unit 132 via the sensor amplifier 128, and a waveform corresponding to the unevenness on the side surface of the tire 102 is generated. After the high frequency noise due to vibration or the like is removed, the original waveform A and the original waveform B are sent to the waveform processing unit 136.
[0042]
A processing procedure in the waveform processing unit 136 will be described with reference to FIG.
In the waveform processing unit 136, first, when the original waveform A and the original waveform B are captured (procedure 1), an approximate curve is created. This approximate curve is created based on the original waveform and is used as a normal waveform with no irregularities on the surface of the tire 102 (procedure 2).
[0043]
In the next procedure 3, the original waveform is subtracted from the created approximate curve. As a result, a waveform in which the concavo-convex portion becomes 0 on the horizontal straight line is generated. In other words, the amplitude indicates irregularities on the surface of the tire 102, and the amplitude length indicates the magnitude.
[0044]
By the way, on the side surface of the tire 102, there is an intentional uneven portion 122 such as a logo mark of a tire manufacturer. For this reason, the intentional uneven portion 122 is also mixed in the waveform generated in the procedure 3.
[0045]
Therefore, in step 4, the uneven waveform generated based on the original waveform A and the uneven waveform generated based on the original waveform B are multiplied. That is, the intentional uneven portion 122 such as the logo mark exists on one detection locus by the displacement sensor 118, but the displacement sensor 118 does not exist on the other detection locus at the same time. The detection position is determined. For this reason, the other waveform corresponding to the position where the intentional uneven portion 122 exists is close to 0, and the intentional uneven portion 122 can be eliminated (almost 0) by multiplying.
[0046]
As described above, by removing the intentional uneven portion 122 from the uneven waveform based on each of the original waveform A and the original waveform B in the procedure 4, it is possible to generate a waveform in which the defective uneven portion is extracted.
[0047]
Up to this point, the process is performed by the waveform processing unit 136. Thereafter, the determination processing unit 138 determines whether the defect unevenness is good or bad.
[0048]
In step 5, the waveform generated in step 4 is divided into a plus-side displacement (convex waveform) and a minus-side displacement (concave waveform), and the pass / fail judgment is made based on the set threshold value. Perform (procedure 6).
[0049]
This threshold value is determined by the determination standard unit 140 based on the model of the tire 102 to be inspected and the like input by the operation of the operation unit 142A of the touch panel drive unit 142, and is sent to the determination processing unit 138. .
[0050]
In step 7, the quality of the tire 102 is comprehensively determined from the number of convex portions and concave portions exceeding the threshold value, the size, the position, and the like.
[0051]
The determination result is sent to the display unit 142B of the touch panel drive unit 142 via the result display unit 144, and necessary information is displayed. Selection of necessary information can be arbitrarily changed according to a 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 defect uneven portions may be displayed together.
[0052]
Further, by connecting a personal computer or the like to the external output terminal 146, it is possible to accumulate inspection result data and leave a history. It is also possible to print out data by connecting a printer directly to the external output terminal.
[0053]
Thus, in this Embodiment, the uneven | corrugated | grooved part of the surface of the tire 102 can be test | inspected, without performing the Fourier transformation (and inverse transformation) which requires time for arithmetic processing. In addition, it is possible to distinguish between the intentionally formed uneven portion 122 and the defective uneven portion, and further, the size and position of the uneven portion can be recognized, and these can be easily performed in a relatively short time. Can be done.
[0054]
In the present embodiment, two displacement sensors 118 are arranged on each side surface of the tire 102, but one each may be arranged and different radial dimension positions may be measured twice or more by the same displacement sensor 118. . In addition, although there are two measurement circles, the more the number of circles is three or more, the more accurate the inspection results, but the processing time is delayed as the amount of data increases, so the inspection is suitable for a limited time. It is preferable to set the number of locations.
[0055]
【The invention's effect】
As described above, the tire outer shape determination method and apparatus according to the present invention are excellent in that it is possible to identify the defect irregularities on the tire surface, recognize the size of the defect irregularities, and determine the degree of defects. Has an effect.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a tire shape inspection apparatus according to the present embodiment.
FIG. 2 is a perspective view of a tire to be inspected.
FIG. 3 is a characteristic diagram of an original waveform A and an original waveform B;
FIG. 4 is a characteristic diagram of an uneven waveform (approximate curve—original waveform).
FIG. 5 is a characteristic diagram of a defect uneven waveform (multiplication of the uneven waveform).
FIG. 6 is a flowchart showing a procedure from measurement of unevenness of a tire to determination of pass / fail.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Tire shape inspection apparatus 102 Tire 104 Holder part (fixing means)
112 motor (rotation drive means)
114 controller 118 displacement sensor (unevenness measuring means)
130 Waveform Control Unit 132 Sampling Processing Unit 134 Filtering Processing Unit (Filtering Processing Means)
136 Waveform processing unit (approximate curve generation means, calculation means, extraction means)
138 Determination processing unit (determination means)

Claims (2)

Two measurement points with different radial dimensions are defined at positions along the radial direction of at least one tire side surface, and the uneven displacement amount of the tire surface is measured over the entire circumference of the tire while maintaining the radial dimension of the measurement points. Generate an original waveform that is the measured waveform ,
This is a normal waveform when the filtering processing unit removes high-frequency noise due to vibrations during rotation of the tire from the original waveform, and is measured with a displacement sensor with no irregularities on the tire surface based on each original waveform However, each approximate curve is generated, and an uneven waveform obtained by subtracting each approximate curve from each original waveform is generated,
By multiplying the corrugations at least at two positions with different radial dimensions, the tire surface is free of intentional irregularities, which are irregularities that can be generated by the tire manufacturer's logo mark and the letters and symbols representing the size. Extract defect irregularities that are irregularities appearing in a streak pattern along the radial direction of
A method for determining the outer shape of a tire, wherein the quality of the tire is determined from the number of convex portions and concave portions exceeding a threshold value, the size, and the position of the extracted waveform of the defect uneven portion. Fixing means for fixing at least the tire;
Rotation drive means for rotating the tire fixed to the fixing means at a constant speed;
At the time of rotation of the tire by the rotation driving means, at least one tire side surface and a position along the radial direction of the tire side surface correspond to two positions having different radial dimensions, the two position points regardless of contact or non-contact. An unevenness measuring means for measuring an uneven displacement amount of an object and obtaining an original waveform ;
Filtering processing means for removing high-frequency noise from the original waveform due to vibration during rotation of the tire, and the like,
Based on each original waveform, an approximate curve generating means for generating an approximate curve that is a normal waveform when measured with a displacement sensor in a state where there is no unevenness on the tire surface ,
Contours appearing in a streak shape along the radial direction of the tire surface by subtracting each approximate curve that is a normal waveform signal generated by the approximate curve generation means from each original waveform filtered by the filtering processing means A calculation means for obtaining an uneven waveform signal including a defect unevenness and a tire manufacturer's logo mark, and an intentional unevenness that can be generated by characters and symbols representing the size,
An extraction unit that eliminates the intentional concavo-convex part and extracts only the defective concavo-convex part by multiplying the concavo-convex waveform signals at two positions different in at least the radial dimension obtained by the arithmetic unit;
Based on the concavo-convex waveform signal extracted by the extracting means, the number of convex portions and concave portions exceeding the threshold value, as well as the size and position of the tire, determination means,
A tire outer shape determining device.

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