JP4204967B2 - Tire inspection device - Google Patents

Description

  The present invention relates to a tire inspection apparatus comprising means for rotating an inspection rim mounted with a tire and a position sensor for measuring a radial position of a tread outer surface. The present invention relates to detecting irregularities.

A tire inspection apparatus comprising: a rim rotating means for rotating an inspection rim on which a tire is mounted; and a position sensor mounted at a predetermined position and measuring a radial position of a tread outer surface. There is known a tire inspection apparatus that measures the runout that is the amplitude of the first harmonic component of the circumferential change based on the radial position taken from the sensor (see, for example, Patent Document 1). According to the apparatus, when the runout value is not within a predetermined range by measuring this runout, it can be selected as a rejected product.
JP 7-243947 A

  By the way, in the recent situation where higher quality assurance is required for tires, it is necessary to detect local unevenness of the tire. For example, a tread cut into one tire is formed into a molding drum. In the tread joint formed when the green tire is formed by winding the upper part, a part of the width direction may be thicker or thinner than the other part. Even if vulcanized, there is a risk of failure due to residual stress concentration as unevenness, but inspection of unevenness is performed by human sensitivity, but manual inspection is inefficient and measures the degree of reliability It is difficult and problematic.

  However, although the conventional tire inspection apparatus described above can detect the runout of the tire from the circumferential change in the radial position of the tread surface, it detects such local irregularities on the tread surface. It was not possible to automate the above-described inspection of irregularities manually.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a tire inspection apparatus capable of detecting local irregularities.

<1> The present invention relates to a tire inspection apparatus comprising: a rim rotating means for rotating an inspection rim equipped with a tire; and a position sensor attached to a predetermined position and measuring a radial position of an outer surface of the tread.
Incorporating the radial position data at a predetermined sampling time from the position sensor under the rotation of the tire, comprising unevenness detecting means for detecting unevenness on the tread surface from the circumferential change of the radial position ,
The waveform obtained by plotting the data acquired from the position sensor with the tire rotation angle at the time of capturing the radial position data on the horizontal axis and the captured radial position data on the vertical axis is called the radial position waveform. The waveform obtained by subtracting the primary harmonic component from this radial position waveform is called a differential waveform, and in this differential waveform, the variation of the sign of one of the positive and negative signs appears with respect to the variation that is the difference between two successive data. After that, the peak start point is the point at which the variation of the other code begins to appear a predetermined number of times, and the peak point is the point at which the variation of one code begins to appear a predetermined number of times after the appearance of the peak start point. After the appearance of the peak point, the peak from the peak start point to the peak end point including the peak point is defined as the peak end point where the variation of the other sign begins to appear continuously a predetermined number of times. When calling the minute, the unevenness detecting means extracts the primary harmonic component from the radial position waveform to obtain the difference waveform, and from this difference waveform, all peak portions in the 360 ° tire rotation angle range are obtained. Tires that perform extraction and obtain their width and height and, when both of these width and height are included in a predetermined range, output a signal that abnormal irregularities have been detected Inspection equipment.

<2> The present invention is the tire inspection apparatus according to <1>, further including a runout measurement unit that extracts a first harmonic component from the radial position waveform and obtains a runout from the amplitude.

<3> The present invention provides the tire according to <1> or <2>, wherein the position sensor measures at least three radial positions including a tread width direction central portion and both shoulder portions. Inspection equipment.

According to the invention <1>, since the unevenness detecting means is provided , local unevenness of the unevenness can be detected, and furthermore, since the above-described processing is performed, unevenness on the tread surface which may be a problem is detected. can do.

According to the invention of <2>, since the runout measuring means is provided, both runout and tread surface irregularities can be detected using one rim rotating means and one position sensor, and these are separately detected. The equipment cost can be greatly reduced compared with the case where it is provided.

According to the invention of <3>, the radial position in at least three locations including the center portion in the tread width direction and the shoulder portions where the tread thickness is the largest and therefore uneven tread joining is likely to occur is measured. Therefore, the unevenness can be detected over a wide range in the width direction of the tread, and quality assurance can be further ensured.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a tire inspection apparatus according to an embodiment of the present invention. FIG. 1 (a) is a front view and FIG. 1 (b) is a plan view. A tire inspection apparatus 1 rotates an inspection rim R on which a tire T to be inspected is mounted, for example, a rim rotation means 2 made of a servo motor, a position sensor 3 for measuring a radial position of a point on a tread surface, 4 is provided. As shown in the figure, these position sensors 3 and 4 bring the detection rollers 3a and 4a into contact with the surface of the tire tread, and determine the amount of radial displacement of the contact surface of the detection rollers 3a and 4a from a predetermined position. It is configured by a contact type that detects, and the radial position of the tread surface can be calculated from the amount of displacement. In the figure, reference numeral 5 denotes a common bed on which the rim rotating means 2 and the position sensors 3 and 4 are mounted.

  The position sensor 3 measures the radial position at the center in the width direction of the tire tread, and the other two position sensors 4 measure the radial positions of the left and right shoulder portions, respectively. Here, the position sensor 4 that measures the radial position of the shoulder portion determines the direction and position of the position sensor 4 so that the position in the width direction of the shoulder portion that is predetermined for each size can be measured according to the size of the tire. Configured to be adjustable. In the drawing, a contact type position sensor is shown, but a non-contact type position sensor can also be used.

  FIG. 2 shows a process in which the tire is rotated by the rim rotating means, the position data in the radial direction of the tread portion surface under the rotation of the tire is taken to detect abnormal irregularities, and the runout is measured to detect the runout abnormality. It is a flowchart. The processing shown in this flowchart is processing performed for each of the three sensors 3 and 4, and the processing performed based on data from the position sensor 3 corresponding to the center in the width direction of the tread will be described below as an example. explain. First, in step s1, the tire T is rotated by the rim rotating means 2, the detection roller 3a is brought into contact with the tread surface under the rotation, and the radial position data of the tread surface is obtained from each position sensor 3 at a predetermined sampling time. At the same time, data representing a tire rotation angle is input from a tire rotation angle sensor (not shown). The number of data corresponding to one round of the tire is preferably 3000 to 6000 in order to ensure the required unevenness detection accuracy without requiring much processing time.

  In step s2, the radial direction of the tread surface corresponding to one rotation of the tire is obtained by taking the radial position of the tread surface on the vertical axis and the tire rotation angle on the horizontal axis from the respective data taken at every sampling time interval. Although the position waveform is calculated, if the data acquired from the position sensor 3 is the position of the tread surface itself and the data acquired from the tire rotation angle sensor is the tire rotation angle itself, step s2 can be omitted. A waveform CV1 shown in FIG. 3A is an example of a radial position waveform.

  Subsequently, in step s3, noise removal processing is performed. This processing is for preventing noise from deteriorating the predetermined unevenness detection performance by using noise other than the predetermined unevenness as an example. For example, noise is obtained by cutting high frequency components generated by a tread pattern or the like by FFT processing. Remove. A waveform CV2 shown in FIG. 3B is a waveform obtained by performing noise removal processing on the radial position waveform CV1 of FIG.

  Subsequently, in step s4, as shown in FIG. 4A, the primary harmonic component CV3 is calculated from the waveform CV2 from which noise has been removed, and in step s5, as shown in FIG. 4B. The differential waveform CV4 obtained by subtracting CV3 from the waveform CV2 is calculated. Subsequently, in step s6, the offset value F is subtracted from the differential waveform CV4 using the minimum value of the differential waveform CV4 shown in FIG. A waveform CV5 is obtained.

Next, in step s7, peak detection processing is performed. In this process, as shown in FIG. 6, with respect to a variation that is a difference between two adjacent data, after the occurrence of a variation δ ₁ of one of the positive and negative signs, the variation δ ₂ of the other sign is a predetermined number of times. points begin to appear in succession as the peak start point P _1, after the appearance of the peak start point P _1, and variational [delta] ₃ of one code is the peak point P ₀ points begin to appear in succession a predetermined number of times, the peak point After the appearance of P _0, the point at which the variation δ ₄ of the other code begins to appear continuously a predetermined number of times is set as the peak end point P ₂ , and processing for detecting these points P ₀ , P ₁ , P ₂ is performed. When all of these points P ₀ , P ₁ , and P ₂ are detected, a process of specifying a region from the peak start point P ₁ including the peak point P ₀ to the peak end point P ₂ as a peak portion is performed. Do.

  Note that variation refers to the difference between two data that follow each other at a predetermined sampling time, and positive variation refers to the later data that is greater than the previous data. In the case of FIG. The peak part which makes a variation the variation of one code | symbol is shown.

Further, after extracting the peak portion by the above procedure, the peak start point P ₁ is set as the temporary peak start point, the peak end point P ₁ is set as the temporary peak end point, and these temporary peak start point and temporary peak end point are The point giving the maximum value or the minimum value is redefined as the peak point, and the search is performed from the redefined peak point toward the temporary peak start point, and the variation δ _{1 of one} sign is performed. After that, the point at which the variation δ ₂ of the other code begins to appear continuously a predetermined number of times is redefined as the peak start point, and the search is performed from the redefined peak point toward the temporary peak end point. Then, the point at which the variation δ ₄ of one code begins to appear continuously a predetermined number of times may be redefined as the peak end point, which makes it possible to more reliably extract the peak portion.

  When a peak is detected, in steps s8 to s11, the peak width exceeds the lower limit value W1 and is lower than the upper limit value W2 with respect to the predetermined values W1, W2, and H, and the peak height is H If the peak is within the range, abnormal unevenness processing is performed as shown in s11. The abnormal unevenness processing s11 outputs, for example, a peak height and width, a tire rotation angle corresponding to the peak, a tire identification code, and the like to a display device (not shown) and discharges the tire as an abnormal tire out of the line. This means the process of outputting the command.

  Also, here, the peak height is defined as the difference in height between the peak point and the peak start point or peak end point, while the peak width is the width direction between the peak start point and the peak end point. Shall be defined as the difference between

  Then, the processing from the peak detection processing s7 to step s11 is performed for the entire region of the tire rotation angle of 360 degrees as shown in step s12.

  Subsequently, the run-out calculated as the amplitude is obtained from the primary harmonic component obtained in step s4 as shown in step s13, and this run-out exceeds the predetermined upper limit value RR1 as shown in step s14. In this case, the abnormal run-out process shown in step s15 is performed. This abnormal run-out process outputs, for example, a run-out value, a run-out phase, a tire identification code, and the like to the display device, and uses this tire as an abnormal tire line. This means processing to output a command to be discharged out of the box.

  Of the steps s1 to s15 shown in FIG. 2, the steps s1 to s12 are processed by the unevenness detection processing means, and the steps s13 to s15 are processed by the runout measuring means.

It is the front view and top view which show the tire inspection apparatus of embodiment which concerns on this invention. It is a flowchart which shows the process which a tire inspection apparatus performs. It is a figure which shows the radial direction position waveform and the waveform which carried out the noise removal process of this waveform. It is a figure which shows the waveform of a primary harmonic component, and a difference waveform. It is a figure which shows the difference waveform which performed the offset process. It is a figure explaining a peak detection process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire inspection apparatus 2 Rim rotation means 3, 4 Position sensor 3a, 4a Detection roller 5 Common bed

Claims (3)

In a tire inspection apparatus comprising rim rotation means for rotating an inspection rim mounted with a tire, and a position sensor attached at a predetermined position and measuring a radial position of an outer surface of the tread,
Incorporating the radial position data at a predetermined sampling time from the position sensor under the rotation of the tire, comprising unevenness detecting means for detecting unevenness on the tread surface from the circumferential change of the radial position ,
The waveform obtained by plotting the data acquired from the position sensor with the tire rotation angle at the time of capturing the radial position data on the horizontal axis and the captured radial position data on the vertical axis is called the radial position waveform. The waveform obtained by subtracting the primary harmonic component from this radial position waveform is called a differential waveform, and in this differential waveform, the variation of the sign of one of the positive and negative signs appears with respect to the variation that is the difference between two successive data. After that, the peak start point is the point at which the variation of the other code begins to appear a predetermined number of times, and the peak point is the point at which the variation of one code begins to appear a predetermined number of times after the appearance of the peak start point. After the appearance of the peak point, the peak from the peak start point to the peak end point including the peak point is defined as the peak end point where the variation of the other sign begins to appear continuously a predetermined number of times. When calling the minute, the unevenness detecting means extracts the primary harmonic component from the radial position waveform to obtain the difference waveform, and from this difference waveform, all peak portions in the 360 ° tire rotation angle range are obtained. Tires that perform extraction and obtain their width and height and, when both of these width and height are included in a predetermined range, output a signal that abnormal irregularities have been detected Inspection device. The tire inspection apparatus according to claim 1 , further comprising runout measurement means for extracting a first harmonic component from the radial position waveform and obtaining a runout from the amplitude. 3. The tire inspection apparatus according to claim 1 , wherein the position sensor measures the radial position at at least three locations including a center portion in a tread width direction and both shoulder portions.

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