JP4445215B2 - Method for inspecting unevenness of tire side - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for inspecting unevenness of a tire side portion that can inspect unevenness of a tire side portion with high accuracy by simple processing.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, prior to shipping manufactured tires, inspecting the unevenness of the tire side portion has been performed. This unevenness is likely to occur mainly when the rigidity of the sidewall portion of the tire is uneven in the tire circumferential direction, and a portion having a small rigidity when filled with air may be referred to as a convex (hereinafter referred to as “bulge”). On the contrary, the portion having high rigidity becomes concave (hereinafter sometimes referred to as “dent”). Since such irregularities impair the appearance of the tire, it is necessary to inspect for irregularities that exceed a certain reference value. Conventionally, various methods have been proposed for sampling unevenness data on a tire side portion using a non-contact displacement meter and judging the unevenness from the waveform (see, for example, Patent Documents 1 to 3 below).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. Sho 62-232507 [Patent Document 2]
Japanese Patent Publication No. 7-65894 [Patent Document 3]
Japanese Patent No. 3283536 [0004]
The inventors repeated various experiments from a viewpoint different from the conventional one. Then, considering the results and past empirical rules, various irregularities such as bulges and dents generated in the tire side part are included, but among them, those that have a serious influence on the appearance of the tire are shown in FIG. As shown in A) and (B), it was found that the width W in the tire circumferential direction is mainly 10 to 50 mm. Therefore, the present invention has been completed by finding that the inspection can be carried out more effectively and efficiently by focusing on the unevenness having such a width.
[0005]
As described above, an object of the present invention is to provide a tire side portion unevenness inspection method capable of inspecting tire side portion unevenness with high accuracy by simple processing.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is a method for inspecting unevenness of a tire side part for inspecting unevenness of a tire side part,
Scanning a smooth region without a lettering on the tire side portion in the tire circumferential direction with a non-contact displacement meter to obtain first unevenness data according to the tire rotation angle;
Decomposing the first concavo-convex data into Fourier component data by Fourier transform;
Obtaining the second unevenness data for displaying a bulge or dent having a width of 10 to 50 mm by performing inverse Fourier transform on the data while leaving only the order component A in the following range . .
[0007]
The invention according to claim 2 further includes a step of measuring the outer diameter of the tire, wherein the method for inspecting unevenness of the tire side portion according to claim 1 is characterized.
[0008]
Further, the invention according to claim 3 is a step of reading the position of the smooth region from a storage means that stores in advance the position of the smooth region without the lettering in the tire side portion for each tire size and model prior to each step; The method for inspecting unevenness of a tire side portion according to claim 1, further comprising a step of moving the displacement meter to a position of the smooth region.
[0009]
Further, in the invention according to claim 4, prior to each step, the step of inputting the size and model of the tire to be inspected, and the outer diameter of the tire from the storage means that stores the outer diameter of the tire in advance for each tire size and type. The method for inspecting unevenness of a tire side portion according to claim 1 or 3, wherein a step of reading an outer peripheral length is performed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall conceptual diagram of a tire side unevenness inspection apparatus 1 suitable for performing the inspection method of the present embodiment. A tire to be inspected (hereinafter simply referred to as “tire”) T to be inspected is mounted on, for example, a test rim 3 of the tire holding device 2 and filled with a predetermined internal pressure. The test rim 3 is connected to the rotational drive device 4 via the shaft 5. Thereby, the tire T can be rotated at a constant speed. In the present embodiment, the tire T is installed in a direction in which the rotation axis is substantially vertical. However, the present invention is not limited to this.
[0011]
The displacement meter 6 employs a non-contact type using an LED, a laser, or the like, and is installed above and below the tire side portion S, respectively. By performing predetermined sampling with the displacement meter 6 while rotating the tire T, the unevenness of the tire T can be measured. The displacement meter 6 can measure the distance to the side part s in a non-contact manner by irradiating the search light toward the side part s of the tire T and receiving the reflected light. In the present embodiment, each displacement meter 6 is provided with a position adjuster 9. The position adjuster 9 includes a servo motor M and a drive mechanism D such as a ball screw that can move the displacement meter 6 in the radial direction of the tire T by driving the servo motor M.
[0012]
As shown in FIG. 2, the tire T is provided with a lettering L or the like made of raised characters on the side portion s. When this portion is measured by the displacement meter 6, it is difficult to identify whether it is lettering or bulge. Therefore, if the displacement adjuster 6 is movable in the tire radial direction by providing the position adjusting tool 9 and driving the servo motor M as described above, a smooth region without the lettering L or the like according to the tire T. It is possible to position the displacement meter 6 in the position.
[0013]
Moreover, in this embodiment, the thing provided with the 2nd displacement meter 7 which can measure the outer diameter of a tire toward the tread surface t of the tire T is illustrated. The distance between the second displacement meter 7 and the rotation axis of the tire T is stored in advance in the storage unit 11 described later as a known value. Accordingly, by measuring the distance between the second displacement meter 7 and the tread surface t, the outer diameter of the tire (or the same applies to the radius below) can be measured. The output signals of the displacement meters 6 and 7 are amplified by the amplifier 12 and then input to the control device 13.
[0014]
The control device 13 includes a storage unit 11 such as a magnetic disk in which a program and necessary predetermined information are stored in advance, an input unit 14 including, for example, a keyboard and a mouse that receives input from the user, a monitor and / or a printer. The output unit 15 composed of the above and the like and a memory 16 for calculation work are connected directly or via an interface (not shown). Note that a personal computer PC or the like can be used as these devices.
[0015]
The storage unit 11 preferably includes, for example, tire specification information as predetermined information. The tire specification information is obtained by correlating and storing “tyre size”, “tire type”, and “smooth area” as visualized in FIG. 4A, for example. In this example, by specifying the tire size and the tire type, the smooth region for the tire (in this example, the region without lettering and from the tire rotation axis suitable for installing the displacement meter 6 is used. Distance).
[0016]
The control device 13 can control each device according to a predetermined procedure and inspect the tire T, and will be described below in a specific procedure of the present embodiment. This procedure is merely an example, and the present invention is not limited to such a specific procedure.
[0017]
First, the control device 13 reads the output signal of the displacement meter 7 and measures the outer diameter R of the tire T. This outer diameter R is temporarily stored in the memory 16. Next, the control device 13 prompts the user to input the tire size and tire type. When predetermined information is input from the input unit 14, the tire specification information in the storage unit 11 is referred to, and the position of the smooth region N without positive irregularities such as lettering on the side portion s in the tire T is determined. read out. Then, based on the deviation between the current position of the displacement meter 6 and the position of the smooth region N, the servo motor M is driven to move the displacement meter 6 to the position of the smooth region N. Thereby, the displacement meter 6 can measure unevenness in the smooth region N without the lettering.
[0018]
Next, the tire holding device 2 is rotated at a predetermined constant speed, and the side portion s is scanned in the tire circumferential direction with a predetermined sampling time by the displacement meter 6 to obtain first unevenness data corresponding to the tire rotation angle. . In this embodiment, the time required for one rotation of the tire is set to 1 second, and 1024 data are sampled from 6 displacement meters per rotation of the tire T. However, the present invention is not particularly limited to this condition. Absent.
[0019]
An example of the first unevenness data is shown in FIG. The LRO on the vertical axis is lateral runout, and the horizontal axis is the tire rotation angle. In the graph, the waveform is drawn for easy viewing, but the actual examination is composed of a set of 1024 points / 360 ° points. In the example of the first concavo-convex data, a large swell is generated as a whole. Such a large swell is inconspicuous as a whole. Further, it is difficult to specify a bulge and dent having a width of 10 to 30 mm concealed in the width of the swell.
[0020]
Next, the control device 13 performs Fourier transform on the first unevenness data to obtain order component data, and inverse Fourier transforms this data leaving only the order component A in the following range. As a result, as shown in FIG. 3B, it is possible to obtain second unevenness data displaying only a bulge or dent having a width of 10 to 50 mm.
Tire circumference (mm) / 20 ≦ A ≦ tire circumference (mm) / 100 (1)
The result of “tire outer peripheral length (mm) / 20” is rounded down after the decimal point, and “tire outer peripheral length (mm) / 100” is rounded up to the nearest whole number.
[0021]
In the Fourier transform, the first unevenness data is decomposed into order components from 1 to 512. On the other hand, as described above, bulges and dents (hereinafter sometimes simply referred to as “bulges etc.”) have a tire circumferential width W of 10 to 50 mm. . Such a bulge or the like has a wavelength twice that of the width W when considered in the waveform shown in FIG. Therefore, a bulge having a width of 10 to 50 mm is considered as a wave having a wavelength of 20 to 100 mm, and the order component having this wavelength can be expressed by the above formula (1).
[0022]
As shown in FIG. 3 (B), the waveform obtained by Fourier transform is subjected to inverse Fourier transform so that only the order component of A remains, so that only a bulge having a width of 10 to 50 mm is obtained. Second unevenness data, which is a waveform to be displayed according to the tire rotation angle, can be obtained. In this example, it can be immediately understood from the second unevenness data that two bulges having a width of 10 to 50 mm are included. As described above, since the second unevenness data excludes all unevenness except for the width of 10 to 50 mm, only necessary and sufficient unevenness is inspected, so that the inspection process can be greatly streamlined. .
[0023]
The control device 13 can display the second unevenness data on the output unit 15. Therefore, the inspector may make a judgment based on this result. The control device 13 can also automatically determine whether the inspection is successful by comparing the LRO of the waveform of the second unevenness data with a predetermined threshold value.
[0024]
As another embodiment, as shown in FIG. 4B, the tire specification information may include information on the tire outer diameter. In this case, not only the second displacement meter 7 can be omitted, but also the process of measuring the outer diameter is not required, so that the inspection process can be further simplified and the efficiency can be further increased. Although the embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment described above, and it is needless to say that the present invention can be modified in various ways.
[0025]
【The invention's effect】
As described above, the invention according to claim 1 is a tire side portion unevenness inspection method for inspecting the tire side portion unevenness, wherein the tire side portion is scanned in the tire circumferential direction by a non-contact displacement meter. The first unevenness data is obtained, the first unevenness data is Fourier-transformed and decomposed into the order component data, and the data is only the constant order component A associated with the outer circumference of the tire. Obtaining second concavo-convex data for displaying a bulge or dent having a width of 10 to 50 mm by performing an inverse Fourier transform so as to remain. In general, the width of the bulge and dent in the tire circumferential direction is 10 to 50 mm, so by obtaining data by concentrating the irregularities in this range, the irregularities that do not require inspection can be excluded. Only the second unevenness data can be inspected directly. Therefore, it helps to make the inspection more efficient and improve tire productivity. Further, since the numerical calculation can be sufficiently processed by a personal computer, the processing can be simplified. Also, the inspection accuracy can be sufficiently secured in practice.
[0026]
Further, as in the second aspect of the invention, the order component A can be calculated more easily by further including a step of measuring the outer diameter of the tire.
[0027]
According to a third aspect of the present invention, prior to each of the steps, the step of reading the position of the smooth region from the storage means that stores in advance the position of the smooth region without the lettering in the tire side portion for each tire size and model. And the step of moving the displacement meter to the position of the smooth region, the unevenness data of the tire side portion can be automatically obtained in the smooth region without the lettering. Adjustment and the like are unnecessary, and the inspection efficiency can be further improved.
[0028]
Further, as in the invention described in claim 4, prior to each step, the step of inputting the size and / or model of the tire to be inspected, and the storage means storing the tire outer diameter for each tire size and model in advance. When performing the step of reading the outer diameter or the outer peripheral length, it is not necessary to measure the outer diameter of the tire each time, so that the inspection efficiency can be further improved.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an apparatus used in a method for inspecting unevenness of a tire side portion of the present embodiment.
FIG. 2 is a side view of a tire.
3A is a graph of first unevenness data, and FIG. 3B is a graph of second unevenness data.
4A and 4B are graphs showing a tire specification table as another embodiment of the present invention. FIG.
5A is a perspective view of a tire having a bulge, FIG. 5B is a cross-sectional view taken along the line I-I showing the bulge, and FIG. 5C is a waveform diagram illustrating the order component of the bulge.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Concavity and convexity inspection apparatus 2 of tire side part Tire holding apparatus 3 Rim 6, 7 Displacement meter 13 Control part T Tire

Claims (4)

A method for inspecting unevenness of a tire side part for inspecting unevenness of a tire side part,
Scanning a smooth area without a lettering on the tire side portion in the tire circumferential direction with a non-contact displacement meter to obtain first unevenness data according to the tire rotation angle;
Decomposing the first concavo-convex data into Fourier component data by Fourier transform;
Obtaining the second concavo-convex data displaying a bulge or dent having a width of 10 to 50 mm by performing inverse Fourier transform on the data while leaving only the order component A in the following range. Method for inspecting unevenness of tire side part.
Tire circumference (mm) / 20 ≦ A ≦ tire circumference (mm) / 100   The method for inspecting unevenness of a tire side portion according to claim 1, further comprising a step of measuring an outer diameter of the tire. Prior to each step,
A step of reading the position of the smooth region from a storage means that stores in advance the position of the smooth region without the lettering on the tire side portion for each tire size and model;
The method according to claim 1 or 2, further comprising a step of moving the displacement meter to a position of the smooth region. Prior to each step,
Inputting the size and model of the inspected tire;
4. The method for inspecting unevenness of a tire side part according to claim 1 or 3, wherein a step of reading out the tire outer diameter or outer peripheral length from a storage means that stores the tire outer diameter in advance for each tire size and model is performed.

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