JPH0425743A - Unevenness deciding method for tire surface - Google Patents

Abstract

PURPOSE:To speedily and accurately decide the unevenness of the tire without being affected by the strain of the whole tire by sequentially calculating the displacement quantities of the maximum and minimum values of displacement data within the circumferential-directional unevenness length of the tire to the entire periphery and comparing them with a deviation standard value. CONSTITUTION:The frequency R of sampling of measurement data P on the length l in the circumferential direction of the tire is set previously as the decided number (n) of sampled data and decision memories a1 - an are stored with the displacement data P inputted from displacement gauges C and D in order to replace internal data with the latest displacement data P; and the difference between the maximum value X and minimum value Y among the displacement data P in the memories a1 - an is calculated as displacement values T in order, and the maximum displacement value L is found among them and compared with the previously set displacement standard value Q to decide a defective when the former is larger. Consequently, speedy and accurate decision making is performed without being affected by the strain, etc., of the whole tire.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a tire surface unevenness determination method for determining whether a tire is good or bad based on the tire surface unevenness.

<Prior Art> When internal pressure is applied to a tire, unevenness may occur on the tire surface. A possible cause of this is variation in the overlapping length of the joint portions at the end portions of the carcass, tread, sidewalls, etc. during the molding process. As a general method for determining the unevenness of the tire surface, as shown in Fig. 5, a vulcanized tire A is hung on a special rim B.
A method is used in which the rim B is rotated by a motor M under increased internal pressure, and the unevenness of the tire surface is determined using displacement gauges C and D.

<Problems to be Solved by the Invention> Figure 6 shows waveforms showing the results of measuring the unevenness of the tire surface over one circumference of the tire A using the displacement meters C and D. In order to accurately determine the local unevenness of the tire surface, frequency analysis of the overall surface waveform is performed, since the displacement caused by the distortion of the entire tire caused by play in the rim B is added to the displacement caused by the unevenness of the tire surface. To achieve this, additional equipment is required, such as adding an analog circuit device such as a low-pass filter or bypass filter, or running a digital waveform analysis program. The problem was that it was not possible.

In view of the above-mentioned problems, the present invention has been made to enable rapid and accurate determination of irregularities on the tire surface without being affected by distortion of the entire tire.

<Means for Solving the Problem> The technical means of the present invention to solve this technical problem is to sequentially measure displacement due to unevenness on the tire surface in the tire circumferential direction using displacement meters C and D, and to collect the displacement data P. In a tire surface unevenness determination method that determines whether the tire A is good or bad, the number of samples R of measurement data P for the length l of irregularities in the circumferential direction of the tire is set in advance as the number of determinations n, and the number of determinations is determined by n judgment memory a l-a, 1, displacement meter C
, D are sequentially stored and replaced with the latest displacement data P, and the judgment memory a
, ~a, , the difference between the maximum value The product is compared with a preset displacement standard value Q, and if the maximum displacement value is large, it is determined to be a defective product, and if it is small, it is determined to be a good product.

<Operation> The determination operation will be explained with reference to the flowchart in FIG. When a measurement command is input from the control unit 4 in step (2), it is determined in step (2) that a measurement command has been input, and the process proceeds to step (2).

In step ■, the displacement data P from the displacement meters C and D is taken in, and in step ■, the determination memory a is read as shown in FIG.
The displacement data P is sequentially stored in l-afi, and the process proceeds to step (2).

In step (2), it is determined whether the number of judgment pieces n is smaller than the number of samples R of the captured displacement data P, and if it is smaller, all the displacement data P in the judgment memories a, ~a,
is stored, and the process proceeds to step (2). If it is large, it means that the displacement data P has not been stored in all of the judgment memories a to a, and the process proceeds to step [phase].
Proceed to.

In step ■, the maximum value X is selected from among the displacement data P stored in the judgment memories at-a, , and in step ■, the maximum value Select the minimum value Y from , and proceed to step (2).

In step ■, the maximum displacement value recorded in the memory 9 is the difference between the maximum value X and the minimum value Y obtained in step ■■ (
It is determined whether or not it is smaller than the displacement value T), and if it is smaller, the lower displacement value is stored in the memory 9 as the new maximum displacement value in step (2), and then the process proceeds to step [phase]. If the maximum displacement value is greater than the difference between the maximum value X and the minimum value Y, then
Proceed from step ■ to step [phase]. As a result, the maximum displacement values at the current unevenness measurement stage are sequentially stored in the memory 9.

In step [phase], 1 is added to the number of samples R, and in step
1 is added to , thereby incrementing the storage address A of the determination memory 81-a, 1 by 1.

In step @, it is determined whether the storage address A is greater than the number of determination items n, and if the storage address A is a dog, step
Initialize the storage address A with the initial value a1 and proceed to step [stock]. If the storage address A is small, proceed from step knob @ to step [phase].

In step [phase], a measurement command from the control unit 4 is input and the process proceeds to step ■, and in step ■, it is determined whether or not the measurement command is off, and if it is not off, the process returns to step ■.
Repeat the operation from step ■ to step [phase]. If the measurement command is off, this means that the measurement of the unevenness of the tire surface for one circumference has been completed, and the process proceeds to step (3).

In step [phase], the displacement standard value Q and the maximum displacement value are compared, and if the maximum displacement value is large, it is determined that the product is defective, and in step ■, a defective signal S2 is issued and the process returns to step ■. If the maximum displacement value is small, it is determined that the product is non-defective, a non-defective product signal S is outputted at step 2, and the process returns to step 4°.

<Example> Hereinafter, the present invention will be explained according to the illustrated example.
In the figure, reference numeral 1 denotes a CPU constituting a personal computer or the like, which inputs displacement data P from displacement meters C and D via an amplifier 2.3. 4 is a control unit that sends a measurement command to the CPU to measure the unevenness of the surface of tire A over one lap.
give to The CPUI has, as shown in FIG. 2, determination memories a to a7, displacement value calculation means 7, maximum displacement value determination means 8, maximum displacement value storage memory 9, good/bad determination means 10, and the like.

The determination memories a1 to a7 sequentially store the displacement data P of the determined number n taken in from the displacement meters C and D, and sequentially replace the recorded contents with the latest measurement data P. Here, the number of determinations n is the length of one unevenness included in the entire waveform (tire circumferential direction) shown in FIG. 3! (For example, 10
Number of samples R for inch tires (approximately 200mm)
is set as the judgment number, and the value n is set in advance by a setting means 12 such as a volume.

The displacement value calculation means 7 selects the maximum value X and the minimum value Y from among the displacement data P of the number n of determinations stored in the determination memo 'J at ~ a, and calculates the difference between the two as the displacement value T. Calculate sequentially (see Part 3).

The maximum displacement value determining means 8 compares the displacement value T calculated by the displacement value calculating means 7Q with the maximum displacement value of past sampling, and if the calculated displacement value T is large, this value is set as the maximum displacement value. If the calculated displacement value T is small, the maximum displacement value of the past sampling is left in the memory as it is. As a result, the maximum displacement value over the entire circumferential direction of the tire A is selected.

When the measurement command from the control unit 4 is turned off, the pass/fail determining means 1O compares the maximum displacement value determined by the maximum displacement value determining means 8 with a displacement standard value Q preset by a setting means 13 such as a volume. If it is above the standard (the maximum displacement value is larger than the displacement standard value Q), a defect signal S2 is output, and if it is within the standard (the maximum displacement value is smaller than the displacement standard value Q), it is a good product. Outputs a signal S.

<Effects of the Invention> According to the present invention, the displacement value T between the maximum value χ and the minimum value Y of the displacement data P within the range of the length p of the unevenness in the tire circumferential direction is calculated over the entire circumference of the tire. The maximum displacement value among the displacement values T and the displacement standard value Q are compared,
If it is within the standard, it is determined to be a good product, and if it is above the standard, it is determined to be a defective product, so that unevenness on the tire surface can be accurately determined locally without being affected by displacement due to distortion of the entire tire.

Moreover, it is no longer necessary to perform frequency analysis of waveforms as in the past, and high-speed processing can be performed with a simple device, which has a significant practical effect.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the present invention, Fig. 2 is a block diagram thereof, and Fig. 3 is a waveform diagram of displacement data showing the results of measuring irregularities on the tire surface in the tire circumferential direction using the same displacement meter. , FIG. 4 is a flowchart for explaining the same operation. Fifth
The figure is a configuration diagram for explaining a conventional example, and FIG. 6 is a waveform diagram of displacement data. 1-CPU, a,, a2. -a, -Judgment memory-7...Displacement value calculation means, 8...Maximum displacement value discrimination means, 9...Memory, 10...Good/bad judgment means.

Claims (1)

[Claims] (1) Displacements due to unevenness on the tire surface are sequentially measured in the tire circumferential direction using displacement meters (C) and (D), and the quality of the tire (A) is determined from the displacement data P. In the determination method, the number of samples R of measurement data P for the length l of irregularities in the circumferential direction of the tire is set in advance as the determination number n, and displacement meters ( C) Sequentially stores the displacement data P taken in from (D) and sequentially replaces it with the latest displacement data P, and also stores the displacement data P in the judgment memory (a_1).
The difference between the maximum value X and the minimum value Y of the displacement data P of ~(a_n) is sequentially calculated as a displacement value T, and the calculated displacement value T
Find the maximum displacement value L from among them, compare this maximum displacement value L with a preset displacement standard value Q, and if the maximum displacement value L is large, it is determined to be a defective product, and if it is small, it is determined to be a good product. A method for determining unevenness on a tire surface.