JPS58200140A - Detector for ruggedness of tire side wall - Google Patents

Abstract

PURPOSE:To accurately detect the ruggedness in the form of an electric signal by a method which is intended to obtain the difference between original signals resulted from sampling displacements of the tire side wall, which are detected by a detector, at predetermined time intervals and signals generated to be delayed by the predetermined number of samplings. CONSTITUTION:Displacements on the side wall surface of a rotating tire is detected by a detector 1 to generate signal voltage in proportion to the detected displacement amounts and signal voltages having the same values and delayed by the predetermined number of samplings. The difference between both signals is calculated in an arithmetic unit C to take out those displacements only which result from fine ruggedness present on the tire surface. By so doing, even with a simple circuit configuration, measure accuracy can be increased and fine ruggedness can be surely detected in the form of an electric signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an excuse detection device that can accurately detect minute excuses occurring on the sidewall of a pneumatic tire.

Consumers' interest in the quality of automobile tires is rapidly increasing, and in addition to durability, tires are strongly desired to have good balance and uniformity. Uniformity measurement, correction, and pass/fail determination are incorporated as an important part of the production process.

Furthermore, during the tire manufacturing process, tire cords that make up the tie carcass often overlap at the joints, or when the sidewall rubber and inner lychee overlap at the joints. Customers react sensitively to minute excuses on the tire sidewall surface, and even though these excuses have nothing to do with tire durability, balance, uniformity, or other safety or ride comfort, they tend to be sensitive to quality issues. This resulted in a sense of distrust as the product was considered inferior.
Since there is a strong tendency to avoid purchasing tires, manufacturers reject tires that have an excuse for the internal pressure filling state to exceed a certain value on the side wall as defective products.

In this case, the presence or absence of a pretext is normally tested by the inspector's sight and touch, but this tends to result in inaccurate judgments and requires a large number of man-hours, so mechanization is strongly desired.

As a countermeasure against this, there is a detection device as shown in Japanese Patent Application Laid-Open No. 52-69659, but this is equipped with a rotating roller and a minute roller on a connecting plate to keep the distance between the connecting plate and the surface of the tire to be measured constant. However, the installation of both rollers was not efficient due to limitations in distance and rotational speed of the tire to be measured, and was not satisfactory as a practical device. .

The present invention has been made to address these conventional problems and provide a highly accurate and efficient device capable of detecting minute pretexts on the ear side wall. In particular, the displacement of the tire side wall detected by a detector is sampled at regular time intervals, and an original signal is generated, and a signal with the same value as the original signal is generated after a very short delay by a predetermined number of samplings. It is characterized by a configuration in which the pretext can be reliably detected as an electrical signal by determining the difference.

Hereinafter, one example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of one example of the device of the present invention, in which a tire to be measured (T) is mounted on a measuring rim (not shown) and is normally held horizontally while being filled with compressed air at a predetermined pressure. The tire is rotated at a predetermined speed by a rotation device, but of course it may be in a position other than horizontal, and the key is to rotate the tire at a predetermined speed around the center axis of the tire. 2) For example, it consists of an optical non-contact displacement detector and a processor (3), whose projected light beam is perpendicular to the measurement plane of the tire to be measured (T). They are installed at a predetermined distance in each direction, receive the reflected light beam of the projected light beam, convert the amount of light into electric current 1, and send it to the processor (3).

The processor (3) is an amplifier that converts the output current of the detection head (2) into a voltage, amplifies it, and sends it to the arithmetic unit (C).

(4) is a rotor provided to be able to rotate synchronously with the tire (T), and is combined with a fixed proximity switch (5) to open and close the switch (5) every rotation of the tire ('I'). It is designed to generate one pulse each time and send it to the arithmetic unit (C).

(6) The Hapulus encoder rotates synchronously with the tire (T) to generate a predetermined number of pulses for each rotation of the tire (tT) and send them to the computing unit (3).

The arithmetic unit (C) has the configuration shown in the block diagram in FIG. 2, and consists of a sampling circuit (7), a delay circuit (8), a differential amplification circuit (9)B, and a comparison circuit t10). .

The sampling circuit (7) is a well-known circuit that samples the output voltage signal of the processor (2) at fixed time intervals, and operates in response to a synchronizing signal from the pulse encoder (6). Output is provided to the amplification circuit (9) and the delay circuit (8).

The delay circuit (8) operates in response to the synchronization signal of the pulse encoder (6), and converts the wavelength range that corresponds to the minute pretext that is the detection target into the sampling interval. The output is delayed for a very short time to compensate for the delay.

When the differential amplification circuit (9) receives the synchronization signal from the pulse encoder (6), it performs a subtraction to subtract the output of the delay circuit (81) from the output of the sampling circuit (7), and generates a proportionally amplified output.

Comparison circuit 1 (1) compares the output of differential amplification circuit (9) with a predetermined tolerance value (reference value), and generates a signal based on the difference S whether the output is larger or smaller than the tolerance value. Issued as a pass/fail signal.

The mode of pretext detection by the detection device having the above-mentioned configuration will be explained below. The tire to be measured (T) is rotated by the rotation device in a state filled with internal pressure, and the detection head (2
) and the tire side wall surface to maintain a predetermined relative position.

The detector (1) is adjusted in advance so that its projected light beam is perpendicular to the measurement station surface of the tire (T). The detection head (2) receives reflected light from the measurement surface of the tire (T), but at this time, the amount of reflected light changes depending on the distance between the detection head (21) and the measurement surface of the tire +T+. receives the reflected light beam proportional to the displacement of the measurement surface of the tire (T+), converts it into an electric current, and sends it to the processor (3).

The processor (3) converts this output current into voltage and amplifies it to the arithmetic unit (C)! Send this.

By the way, the output voltage signal emitted by the processor (3) is illustrated in FIG. Displacement due to a long collision or unevenness in the tire.
On the other hand, a waveform with a short period is a displacement based on a minute collision on the tire surface.

Therefore, it is natural that pretexts can be detected by distinguishing between a waveform with a large rate of change with a short period and a waveform with a slow change with a long period.

Every time the arithmetic unit (C) receives a pulse from the encoder (6), it converts the signal received from the processor ('3) at that time into the original signal shown in Figure 3 (A) and the original signal shown in Figure 3 (A). The two types of signals (B) and the delayed signal are extracted, and the difference between the two signals is calculated. The signal portions caused by long-cycle collisions or discrepancies in the tires are clearly identified in Figure 3 (C). As shown in Fig. 3 (c), the difference in the signal is small and the signal is almost completely removed. As shown in FIG. 2, a waveform signal in which only signal elements caused by minute collisions formed on the tire side wall surface appear conspicuously is output from the differential amplification circuit (9).

Therefore, if the comparator circuit 10) makes a comparison with a set value serving as a reference value and automatically makes a pass/fail determination, stable test results and a reduction in test man-hours can be obtained.

Although the arithmetic unit (C) in the above example is constructed from an analog circuit, it is easy to replace it with a digital computer. If necessary, it is possible to set multiple delay pulses in the same measurement, and if necessary, it is possible to reduce the measurement error by setting multiple delayed pulses in the same measurement. It is also easy to do.

As described above, the present invention detects the displacement of the side wall surface of a rotating tire with a detector (1), and generates a signal voltage having a proportional relationship to the detected displacement amount and a predetermined sampling number equal to this and a signal voltage having a proportional relationship to the detected displacement amount. Since only the displacement caused by the delayed signal is collected, it is possible to increase the accuracy of measurement with a simple circuit configuration.

Furthermore, it is possible to respond accurately even during measurements at high speeds, which greatly contributes to streamlining inspections.

In addition, by installing detectors on both sides of the tire to be measured, it is possible to inspect both walls at the same time, and if necessary, multiple detectors can be installed on one side, making it possible to simultaneously measure both sides of several locations. The scope of application of the invention is extremely wide, and it is a pretext detection device with great practical value.

[Brief explanation of drawings]

Fig. 1 is a schematic structural diagram of the device array of the present invention, Fig. 2 is a block diagram of the arithmetic unit in Fig. 1, and Fig. 3 (A).
~i/→ is an output signal diagram of each output section according to the example of the device of the present invention, (a) is the output magnetic pressure of the sampling circuit, (b) is the output voltage of the delay circuit, and (c) is the differential amplification. The output voltages of the circuits are shown respectively. (T)・・・・・・・・・Tire to be measured. (1)・・・・・・・・・Detector. (7) Sampling circuit. (8)・・・・・・・・・Communication circuit. (9)・・・・・・・・・Differential amplifier circuit. (10)・・・・・・・・・Comparison circuit. 1112 Figure C Figure 3 (a) Corporate power (0) (l\)

Claims (1)

[Claims] 1. A rotating device that rotates the tire to be measured (T) at a predetermined speed around the tire center axis while being filled with compressed air at a predetermined pressure; A detector (1) that detects and converts it into a voltage signal, a sampling circuit (7) that samples the voltage signal of the detector (1) at fixed time intervals, and a voltage signal from the detector (1). a delay circuit (8) for delaying and outputting a wavelength range corresponding to a minute pretext that is a detection target for an extremely short period of time commensurate with a predetermined sampling number converted into the sampling interval, and the sampling circuit; A differential amplifier circuit (9) for determining the difference between the original signal from (7) and the delayed signal from the delay circuit (8), and compares the output of the differential amplifier circuit (9) with a preset tolerance value. A device for detecting a pretext on a tire sidewall, comprising a comparison circuit for determining pass/fail.