JPH0713564B2 - Tire sidewall inspection equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for inspecting unevenness of a sidewall surface as a factor for judging whether a tire is good or bad.

(Problems to be Solved by the Related Art and Invention) Irregularities may occur on the sidewall surface of a tire when air is filled due to irregular ply cord spacing, excess or deficiency of ply joint amount, or the like. This unevenness adversely affects the uniformity of the tire,
In addition, for reasons such as spoiling the appearance and lowering the product value,
It needs to be detected at the inspection stage.

In this case, in the sidewall, in addition to the irregularities to be detected, lettering such as letters and symbols, or spews, various marks, and non-target elements such as stains on the sidewall surface have irregularities, It is necessary to exclude the unnecessary signal due to this non-target element from the original uneven signal.

Conventionally, a method disclosed in Japanese Patent Publication No. Sho 62-30361 is known as a method for inspecting the unevenness of the sidewall surface. However, according to this known method, since the capacitance sensor is used, the data obtained from the characteristics of this capacitance sensor is, for example, the average value of a wide zone far exceeding 1 mm in the circumferential direction, and the detection itself is Be inaccurate. Further, as a means for removing the unnecessary signal, the measurement range of the capacitance sensor is wide in the radial direction of the sidewall,
Although it is stated that the influence of characters, spews, etc. on the detection signal is weakened by making the selection narrower in the circumferential direction, such a distinction is actually difficult due to the characteristics of the capacitance sensor.

Therefore, there is a high possibility that signals such as spews, lettering, and tire stains that are not required to be detected will be erroneously recognized as signals to be detected, and the detection accuracy will obviously deteriorate.

Further, in the above-mentioned conventional technique, the waveform is deformed due to the use of a filter or the like, which also affects other irregularities to be detected, so that the detection accuracy is lowered.

Therefore, the present invention eliminates the influence of the lettering and dirt of the tire without deforming the waveform, and can accurately detect the abnormal irregularities that are the inspection target, and improve the inspection accuracy. The present invention provides a sidewall inspection device.

(Means for Solving Problems) An object of the present invention is to provide an optical displacement sensor which is provided so as to face a sidewall surface of a rotating tire and which reads a change in distance with respect to the sidewall surface as an uneven signal of the surface. Storage means for storing the signal read by the optical displacement sensor, proper data discriminating means for discriminating whether or not the data read from the storage means is proper as unevenness detection data, and proper data discriminating means Among the data determined to be, the width of the unevenness, the correction means for removing the unevenness that is not the detection target based on whether the central portion of the unevenness is flat, and the unevenness in the data after correction by this correction means Based on the unevenness height calculation means for identifying unevenness that satisfies a certain condition and calculating the height thereof, and the unevenness height calculated by this unevenness height calculation means It is provided with a determination means for determining the presence or absence of abnormal irregularities.

Further, the optical displacement sensor is provided movably with respect to the sidewall surface, and the sensor is provided at an appropriate inspection position of the sidewall that is specified in advance for each tire group or specified by inputting the tire size. You may make it position.

Furthermore, in order to achieve more accurate detection, the spot diameter of the optical displacement sensor is set to 1.0 mmφ or less, and a signal sampling means for sampling the signal read by the sensor at a constant measurement timing is provided, and the measurement is performed. It is desirable to set the timing so that the measurement zones of the sensor do not overlap each other independently in the tire circumferential direction.

In addition, it is desirable that a plurality of sensors be provided at intervals in the tire radial direction, and that unevenness on the sidewall surface be detected by each sensor.

(Operation) As described above, according to the present invention, by the optical displacement sensor,
All the irregularities on the tire sidewall surface are read and stored, the data is corrected to remove only the non-detection target data, the irregularity height is calculated from the remaining data, and the abnormal irregularities are calculated based on this calculation result. Since the presence / absence of the presence or absence is finally determined, the influence of lettering or the like can be surely eliminated and the unevenness can be accurately detected, so that the inspection accuracy is significantly improved.

Moreover, since the sensor is positioned at the optimum inspection position of the sidewall, the inspection accuracy is further improved.

Further, according to the third aspect of the present invention, signals read by the optical displacement sensor do not overlap each other, and accurate signals are acquired.

In addition, by providing a plurality of the same sensors at intervals in the tire radial direction, the unevenness of the sidewall surface is shared by each sensor, so that the unevenness and the other parts are clearly distinguished and detected. The accuracy will be even better.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

FIG. 4 and FIG. 5 show the inspection state of both sidewalls 1a, 1a of the tire 1 filled with air. Tire 1
Is held by the support cylinder 2 in a horizontal state as shown in FIG.
While being driven to rotate around the center of the tire together with the support cylinder 2 by a rotation drive mechanism (not shown), the sidewall surface is inspected for irregularities.

An optical displacement sensor (hereinafter simply referred to as a sensor) that detects unevenness by measuring changes in the distance to the sidewall surface.
3 is a plurality of pieces (for example, two pieces) spaced apart from each other in the tire radial direction with respect to both sidewalls 1a, vertically facing the sidewall surface vertically and installed at intervals in the tire radial direction. To be done. Reference numerals 4 and 4 denote arms to which the sensors 3 on both sides are attached. The arms 4 and 4 are movably supported vertically and independently on a frame 5, and the movement of the arms 4 and 4 causes the sensor 3 to move against the sidewall surface. The height position of ..., that is, the distance between the two is adjusted. Further, the frame 5 is supported by the frame 6 so as to be movable in the tire radial direction, and the movement of the frame 5 adjusts the positions of the sensors 3 ... In the tire radial direction. In the figure, 31 and 32 are screw shafts, which are rotationally driven by a motor (not shown).

The adjusting function of the tire radial stop position of the sensors 3 will be described in more detail.

A position detector 7 including a light emitting element and a light receiving element 7a, 7b is provided at the base ends of the arms 4, 4, and the sensors 3 ...
When positioning at the optimum inspection position of a, the frame 5 moves horizontally to the tire side to project, and the transmission and reception of light between the light receiving elements 7a and 7b is blocked by the tire 1, so that the plurality of sensors 3 ... Reaching the position is detected.

By the way, the height of the sidewall of the tire is different depending on the size, and therefore, the position of the unevenness due to the disturbance of the ply cord interval or the excess or deficiency of the ply joint amount, which is the detection target, is different for each tire size, Different, the light emitting elements 7a and 7b on the arm 4
And a distance χ (shown in FIG. 5) from a predetermined sensor 3 which is a reference for position determination in the sensor group is fixedly determined, so that transmission / reception of light between the light emitting / receiving elements 7a and 7b is hindered. The stop delay time required for the above-mentioned predetermined sensor 3 to move to the optimum inspection position P after being obtained is predetermined for each tire size.

The reference position detection signal of the position detector 7 is sent to the control unit 9 that controls the frame drive mechanism 8, and the frame 5 moves according to the tire size (tire diameter) based on this signal and the sensor stop delay time. Control is performed. That is, in the case of a tire of a certain size, the movement of the frame 5 is immediately stopped when the reference position is detected by the position detector 7, and in the case of a tire of another size, the timer is started from the time of the reference position detection. The movement of the frame 5 is stopped after a delay time preset by means (not shown) has elapsed.
Next, the arm 4 moves toward and approaches the sidewall surface while measuring the distance from the sidewall surface, and stops when the set constant displacement is reached.

In this way, the sensors 3 ... Are automatically set at the optimum inspection position preset according to the tire size. The preset optimum inspection position is determined as a position that is empirically and statistically known as a position where unevenness is likely to occur in the radial direction in the sidewall of each size tire due to the tire structure. 3 are set to appropriate positions for detecting unevenness.

Two or more of each of the sensors 3 are positioned in the tire radial direction on one side of the sidewall to facilitate the distinction between the unevenness generated continuously in the tire radial direction and other non-detection target objects. The sensor 3 has a small spot diameter (measurement range within the same time), that is, the spot diameter is 1.0 m.
Those with mφ or less are used. This spot diameter is smaller than the width of the lettering component with the narrowest width. Also, if the spot diameter exceeds 1.0 mmφ, it will be detected in the form of the average value of the measurement zone, and as shown in Figs. 6 and 7, the difference between the lettering and the detection target will be an unclear waveform, resulting in an erroneous waveform. Judgment is likely to occur.

In this way, when the unevenness of the sidewall surface is shared by the plurality of sensors 3 having a small spot diameter, the unevenness detection over a wide range in the tire radial direction is performed by one sensor having a large spot diameter. In comparison with the above, since the uneven portion and the other portion are clearly distinguished, the detection accuracy is high.

The output signals of each of the sensors 3 ... Are fetched into the data processing unit 11 by the microcomputer at a predetermined measurement pitch via the input unit 10 as shown in FIG.

The input unit 10 includes an amplifier 12 that amplifies each sensor output signal,
A switch 13 for switching data of a plurality of sensors 3 in a time sufficiently shorter than a sampling time, and an A / D conversion for converting a sensor output signal which is an analog signal into a digital signal in a short time similar to the switch 13. And a signal sampling means 15 such as an encoder and a pulse generator.

The signal sampling means 15 samples continuous signals from the sensors 3 ... At predetermined measurement timings in the tire circumferential direction so that sensor measurement zones in the tire circumferential direction do not overlap each other. In this way, by sampling the sensor signals so that they do not overlap with each other, and by setting the spot diameters of the sensors 3 ... To 1.0 mmφ or less, the measurement zones of the sensors 3 ... Independently exceed each other in the tire circumferential direction. Since no wrapping is performed, more accurate unevenness detection can be performed.

The data processing unit 11 is a storage unit 16 such as a RAM for reading and storing the sampled signal, and an appropriateness for determining whether or not the data read from the storage unit 16 relates to the unevenness of the sidewall surface. Data discrimination means 17
Then, the first and second correction means 18 and 19 for removing the irregularities outside the detection target from the data determined to be appropriate by the appropriate data determination means 17, and the irregularity in the data after the correction, a certain condition is set. Front side and back side uneven height calculating means 20, 21 for identifying the unevenness to be satisfied and calculating the height thereof, and a final judging means 22 for finally judging the presence or absence of abnormal unevenness based on the calculation result. ing. Hereinafter, each means will be described in detail.

(I) Appropriate data discriminating means 17 Sensor output when proper measurement cannot be achieved, for example, when the lens of the sensor 3 or the surface of the sidewall is significantly contaminated, or when the sensors 3 are not set at proper positions. Becomes a high value that exceeds the measurement range. The proper data discriminating means 17 discriminates that the data read from the storage means 16 is improper when the abnormal data contains a certain amount or more of such abnormal data, and does not execute the subsequent processing.

On the other hand, the data determined to be appropriate by the appropriate data determination means 17 is corrected by both the first and second correction means 18 and 19.

(II) First correction means 18 The raw data taken from the proper data discriminating means 17 is the second data.
As shown in the figure (a), the waveform has a large number of minute irregularities. If this is left as it is, the efficiency of the subsequent processing becomes poor due to these minute irregularities. Therefore, the first correction means 18 searches for a portion of the tire in which minute irregularities having a certain width or less continuously appear in a certain number or more for one round of the tire, smoothes the minute irregularities, and fixes them. Obtain the basic waveform shown in (b).

The basic waveform shown in FIG. 2B includes spews on the sidewall surface, peak marks, small letters, bag letters, or small irregularities X due to dirt or the like that has passed through the appropriate data discriminating means 17. Therefore, in the first correction means 18, such so-called small lettering is cut.
Specifically, a horizontal distance (width of the unevenness) between the starting point and the ending point of the unevenness is found to be less than a certain value, and this is cut as unnecessary unevenness. By this processing, the waveform shown in FIG. 2C is obtained.

(III) Second correction means 19 In the data of FIG. 2C, the unevenness Y having a large width such as solid characters remains as the unevenness to be removed. In order to remove such so-called large lettering, the second correction means 19 identifies, among the irregularities, those having a width equal to or greater than a certain value and having a flat central portion which is a characteristic of large lettering, and To cut. In addition, the central portion is not only flat and straight, but the entire central portion is not flat.
It also includes the case where the straight portion occupies a certain proportion or more of the entire width.

In this way, the data as shown in FIG. 2 (d) from which the unnecessary irregularities X and Y are removed are obtained.

(IV) Front-side and back-side unevenness height calculating means 20, 21 The unevenness height calculating means 20, 21 detect unevenness under a certain condition and calculate the height.

That is, in the data shown in FIG. 2 (d), as the unevenness to be detected, the unevenness of the entire sidewall, that is, the so-called tire deflection is included. Further, minute irregularities that cannot be completely processed by the first correction means 18 are also included in the irregularities to be detected. Therefore, first, the unevenness having an extremely large width due to the runout of the tire is ignored, and only the other unevenness is determined. Also,
A large unevenness having a minute unevenness group is recognized as one unevenness, and a minute discontinuity and a retrograde inclination are recognized as the same unevenness within a certain range (shape recognition).

Then, the height of data satisfying such conditions is calculated.

In this calculation, each sensor 3
The evaluation is different depending on the position of ..., and there is a gap between the sensor data and the data actually perceived by humans (generally, the convex looks low and the concave looks deep),
Since this gap also varies depending on the surrounding conditions such as knurling around the irregularities, it is calculated as a total value considering these conditions.

Specifically, the comprehensive evaluation (total value) in the tire radial direction at a certain position in the tire circumferential direction is obtained by the following formula.

Overall value = maximum height + n × a + b Here, the maximum height means the maximum height among the heights obtained by the plurality of sensors in the radial direction.
It should be noted that a convex with a certain height or more is evaluated as an abnormal convex. Also,
n is the number of sensors evaluated as abnormal in the radial direction, a
Is a coefficient for not evaluating abnormality as normal, and b is a correction value when knurling or the like is performed.

The same calculation is performed for each convex in the data, the maximum one of the obtained total values is indexed as the total total value, and this is sent to the final determination means 22 separately for the front side and the back side.

(V) Final determination means 22 Here, the overall total values of the fed front and back sides are compared, and the larger one is taken.

Then, the final data is converted into A to
The tires are ranked in four stages of D, and those including irregularities of D rank are judged to be out (defective tire).

This determination result is sent to the output unit 23, and a signal from the output unit 23 is used to display a defect by an alarm device or the like.

The flow of operation of the entire apparatus including this series of data processing will be further described with reference to the flowchart of FIG.

When the operation is started, the forward movement of the frame 5 to the tire side is first started in step S ₁ , and the frame 5 is moved forward in step S _2.
Has reached the above-mentioned reference position based on a signal from the position detector 7. For example, in the case of an A size tire, a certain delay time t has elapsed from that point, and in the case of a B size tire, that point in time. At (t = 0), frame 5
There is stopped (Step S _3). Then, the forward movement of the arms 4, 4 to the side wall side is started (step S ₄ ),
Sensor 3 ... the side walls 1a, whether it is set to a proper position having a predetermined distance is determined by the sensor output voltage with respect to 1a (step S _5). Further, after the arm is stopped (step S ₆ ), signal acquisition from each sensor 3 ..., Sampling is started (step S ₇ ), signal acquisition for one round of the tire, and arm 4, 4 and frame 5 when sampling is completed. Are returned to their original positions (step ₈ ).

On the other hand, the sampled data is stored in the storage means 16 of the data processing unit 11 (step S ₉ ), and the proper data discriminating means 17 discriminates whether or not the data read from the storage means 16 is proper. (step S _10), when it is determined that proper data, the sequence proceeds to step S _11, first, the correction by the second double-correcting means 18 and 19 are performed. Then, after the final determination by the final determination means 22 was carried out in uneven extraction of unevenness of certain conditions by the height calculation means 20, 21 and calculating height of unevenness, further steps S ₁₃ in step S _12, the output unit 23 output signal to alarm or the like is issued (step S _14). Note that, in step S _10,
If the data is determined to be improper by detecting dirt on the sidewall surface, etc., go directly to step S ₁₄
Then, the output section 23 outputs a signal indicating that the data is incorrect. Further, the series of operations shown in FIG. 3 may be controlled by one computer, or the control of the proper position stop and return of the sensor and the data processing may be controlled by different computers. Good. According to the latter method, step S ₈ and step S ₉ onward in the flowchart of FIG. 3 can be performed simultaneously (step
Since the time required for S ₈ can be deleted, the time required for the entire inspection can be shortened.

〔The invention's effect〕

As described above, according to the present invention, all the irregularities (raw data) on the sidewall surface of the tire are read by the optical displacement sensor, and this displacement data is not unsuitable due to dirt on the tire or improper sensor position. After checking whether or not, the correction means removes unnecessary data such as large and small lettering that is not detected, extracts irregularities under certain conditions from the remaining data, and calculates the height of irregularities. Since the presence / absence of abnormal irregularities is determined on the basis of the above, it is possible to reliably eliminate the influence of lettering and the like and accurately detect irregularities, and it is possible to significantly improve the inspection accuracy. Especially in the correction means,
In addition to the width of the unevenness, the data correction is performed based on whether or not the central portion of the unevenness is flat, so that the lettering can be eliminated more accurately.

Further, according to the configuration of claim 2 in which the optical displacement sensor is automatically positioned at the optimum inspection position, the position setting of the sensor is simple and accurate, and the inspection accuracy is further improved.

Further, according to the third aspect of the present invention, since the measurement zones of the sensor do not overlap each other independently in the tire circumferential direction, the unevenness detection becomes more accurate.

Further, as in claim 4, by providing a plurality of sensors on the sidewall surface at intervals in the tire radial direction, the unevenness of the sidewall surface can be shared by each sensor. As compared with the case where one sensor detects unevenness over a wide range in the tire radial direction, the uneven portion and other portions are clearly distinguished, and the detection accuracy is further improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 (a) is a data waveform diagram before correction by the correction means, and (b), (c), and (d) are stepwise by the correction means. FIG. 3 is a waveform diagram of processed data, FIG. 3 is a flow chart for explaining the overall operation, FIG. 4 is a diagram showing a sensor arrangement and a sensor support structure in the embodiment apparatus, FIG. 6 (a), (b), and (c) are comparative explanatory views of the convex detection by the sensors of large and small spot diameters, and FIG. 7 (a).
(B) and (C) are comparative explanatory views of lettering detection by sensors of large and small spot diameters. 1 ... tire, 1a, 1a sidewall, 3 ... sensor,
4,4 ... Arm with sensor attached, 5 ... Frame with arm attached, 6 ... Frame with frame attached, 10 ... Input section, 15 ... Signal sampling means, 11
...... Data processing unit, 16 …… Storing means of the processing unit, 17 ……
Same appropriate data discriminating means, 18 ... First correcting means, 19 ... Same second correcting means, 20, 21 ... Same unevenness height calculating means, 22 ...
Final decision means.

Claims (4)

[Claims] 1. An optical displacement sensor which is provided so as to face a sidewall surface of a rotating tire and which reads a change in the distance to the sidewall surface as an uneven signal of the surface, and stores the signal read by the optical displacement sensor. Storage means, proper data discriminating means for discriminating whether or not the data read from the storing means is proper as the concavo-convex detection data, and the width of the concavo-convex among the data discriminated by the proper data discriminating means. And a correction unit that removes the unevenness that is not the inspection target based on whether the central portion of the unevenness is flat, and the unevenness that satisfies a certain condition is identified from the unevenness in the data after correction by this correction unit. Then, the unevenness height calculating means for calculating the height thereof and the judgment for determining the presence or absence of abnormal unevenness based on the unevenness height calculated by this unevenness height calculating means Inspection device of the sidewall of the tire, characterized by comprising; and a stage. 2. An optical displacement sensor is provided so as to be movable toward and away from a sidewall surface, and the sensor is specified in advance for each tire group or specified by inputting a tire size. The tire sidewall inspection apparatus according to claim 1, wherein the tire sidewall inspection apparatus is configured to be positioned at an optimum inspection position of the side wall. 3. A spot diameter of the optical displacement sensor is set to 1.0 mmφ or less, and signal sampling means for sampling a signal read by the sensor at a constant measurement timing is provided, and the measurement timing is measured by the sensor. The tire sidewall inspection device according to claim 1 or 2, wherein the zones are set independently of each other in the tire circumferential direction so as not to overlap each other. 4. An apparatus for inspecting a sidewall of a tire according to claim 1, wherein a plurality of optical displacement sensors are provided on the sidewall surface at intervals in the tire radial direction. .