JPH053378B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for correcting tire uniformity, and more particularly to a method for correcting lateral force variation (LFV) of tire uniformity. It is.

[Prior art]

As one of the uniformity characteristics of tires, for example, tire stiffness characteristics, that is, tire radial
Force variation (variation of force in the tire radial direction when the tire is installed: hereinafter referred to as RFV)
and tire lateral force variation (variation of force in the tire width direction when the tire is installed: hereinafter referred to as LFV), and these RFV,
To correct LFV, it is generally known that buffing the tire shoulder area is highly effective.

By the way, conventional RFV correction methods include, for example, as disclosed in Japanese Patent Publication No. 54-31239.
There is a method of correcting the part where radial force (force in the tire radial direction when the tire is mounted: hereinafter referred to as RF) is generated, and similar methods are disclosed in Japanese Patent Laid-Open No. 54-83976 and Kaisho
There are publications such as No. 54-129071.

In addition, as disclosed in Japanese Patent Application Laid-open No. 54-83975, there is a method for correcting LFV, in which lateral force (force in the tire width direction when the tire is installed: hereinafter referred to as LF) is generated. There is a method of buffing a shoulder part and a part that is shifted by 180 degrees from the other shoulder part.

However, in both of these methods, despite the fact that RFV and LFV are due to the sum and difference of the stiffness of both shoulder parts, it is the resultant force of stiffness.
Since buffing is performed based on RFV and LFV, the stiffness fluctuations of the shoulder part are not uniform, and therefore RFV,
There was a problem in that when one characteristic of the LFV was corrected, the other characteristic deteriorated, and even after correction, the tire uniformity characteristics deteriorated. In particular, LFV deteriorates significantly after the correction. Further, an attempt to correct uniformity, particularly RFV, by individually detecting the stiffness of both shoulder portions of a tire is disclosed in US Pat. No. 3,553,903. This patent describes a method in which rollers are pressed against both shoulder portions to extract the reaction force, and the portions where the reaction force is large are buffed. However, in the case of this modification method, the drum for measuring RFV and the roll for measuring rigidity are: (1) the drum is one piece, whereas the roller is separated into two; (2) Measurements are taken from the drum because the tire contact area differs due to the difference between the drum diameter and roll diameter.
The forces applied to the RFV and the rollers will be different,
The waveform of the roller is rather similar to free radial runout (variation in outer diameter: hereinafter referred to as FRRO), which is a variation in the surface displacement of the tire shoulder.

Therefore, since the FRRO and RFV of the shoulder portion do not necessarily correlate with each other, there is a problem in that the correction effect may not be obtained depending on the tire.

[Purpose of the invention]

This invention was devised by focusing on the conventional problems, and its purpose is to improve the tire stiffness when correcting the uniformity of the tire, especially with respect to the stiffness fluctuations occurring from the shoulder part of the tire. This invention provides a tire uniformity correction method that improves LFV characteristics by comparing the sizes and buffing the peak position of the one with greater rigidity.

[Structure of the invention]

In order to achieve the above object, this invention presses a drum against a rotating tire, and uses a load cell attached to the drum shaft that supports the drum to determine the stiffness in the LF direction of the shoulder portions on both sides of the tire. The gist is to correct the LFV of the tire by comparing the stiffnesses in the LF direction and buffing the peak position of the one with greater stiffness.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 shows a schematic configuration diagram of a uniform machine embodying the present invention, W is a tire rotatably supported on a support shaft 1, 2 is a rotatable drum pressed against the tire W, 3a, 3b is the drum shaft 2a
X/Y load cells (sensors that convert force changes into voltage changes and output them) installed at both ends of the tire W are shown. The shoulder stiffness detector 4 obtains data detected from the stiffness (components in the RF direction: Ax, Bx) and the stiffness in the Y-axis direction (components in the LF direction: Ay, By), and outputs the data to the computer 5.

If RFV and LFV do not fall within the preset range, this calculator 5 detects the rigid parts of Ax and Bx, and uses this calculator 5 to correct the positional deviation between the grinding wheels 6a, 6b and the drum 2. A signal is output to the servo controllers 9a, 9b so that the load current of the load current detectors 8a, 8b connected to the grindstone motors 7a, 7b is within a certain range at the buffing symmetrical location, and is sent via the grindstone feed motors 10a, 10b. It is something to control.

Next, both tire shoulder portions W1 of the present invention,
The principle of extracting the rigidity of W2 will be explained with reference to the schematic diagrams of FIGS. 2 and 3.

In Fig. 2, W indicates a tire in an inflated state, and 2 indicates a rotating drum for measuring tire uniformity. Y load cell 3
a and 3b are attached.

Note that when measuring the uniformity of the tire W using the drum 2, high ground contact pressure is applied to both shoulder portions W1 and W2 of the tire W as shown in FIG.
It is generally known that X ₁ and X ₂ occur. And both shoulder parts W1,
W2 presses the drum 2 as shown in A and B in FIG. 2 by ground pressures X1 and X2.

Further, it has been found through experiments and research that the fluctuation in the sum of the X components (RF) of A and B mentioned above is RFV, and the difference between the X components (RF) of A and B is LFV.

Ax, which is the X component (RF) of A and B,
Bx can be taken out independently by combining the outputs of the X and Y load cells 3a and 3b according to the following formula. That is, Ax=Ra(1+l/S)+Rb(1-l/S)+2d/S(La+Lb)...Equation (1).

Bx=Ra(1-l/S)+Rb(1+l/S) -2d/S(La+Lb)...Equation (2).

Here, Ra and Rb are the outputs of the X components (RF) of the load cells 3a and 3b, and La and Lb are the outputs of the load cells 3a and 3b.
The output of the Y component (LF) of a and 3b, l is the drum axis length, d is the drum radius, and S is the shoulder width of the tire W.

From the above equations (1) and (2), Ax and Bx are taken out by inputs to the load cells 3a and 3b using the analog circuit shown in the block diagram shown in FIG.

To explain the block diagram of FIG. 4 in more detail,
In the figure, A ₁ to _{A 4} indicate amplifiers that amplify the load cell output to a possible voltage.

A ₅ , A ₇ (1+S/l) times the gain, A ₆ ,
_A8 is an amplifier with a gain of (1-S/l). And in adder A ₉ , Ra(1+l/S)
+Rb(1-S/l) is calculated and input to _A11 . Similarly, A ₁₀ is Ra(1-l/S)+Rb(1+
l/S) is calculated and input to _A12 .

On the other hand, _A15 is an adder with a gain of 2d/S, and its output is (La+Lb)2d/S.

A ₁₁ is obtained by adding the output of A ₉ and the output of A ₁₅ to Ra (1 + l/S) + Rb (1 - S/l) + (La +
Lb) Outputs 2d/S. Similarly, A ₁₂ can be calculated by subtracting the output of A ₁₅ from the output of A ₁₀ .
l/S)+Rb(1+S/l)-(La+Lb)2d/S is output.

_A16 performs addition of Ra+Rb. Also, A ₁₇ is
Add (La+Lb).

By offsetting the load applied to the tire W from the outputs of A ₁₁ , A ₁₂ , and A ₁₆ , the amount of variation is calculated, and the load at A ₁₃ , A ₁₄ , and A ₁₈ is calculated from the outputs of A ₁₁ , A ₁₂ , and A ₁₅ . is subtracted to obtain the outputs of Ax, Bx, and RFV.

Similarly, since LFV can be found from _A17 by offsetting the weight of drum 2, this subtraction is performed in _A19 .

Here, l and d are fixed constants, but S is a variable that varies depending on the size of the tire W.

However, from equations (1) and (2), even if the value of S is not given correctly, it will not affect the phases of Ax and Bx, so
In this analog circuit, it is treated as a fixed constant.

In addition, Fig. 4 was created with the shoulder width S of the tire W as a fixed value, and the amplification degree of the amplifier G in Fig. 4 can be changed to correspond to the shoulder width S according to the tire W. Also good.

In this invention, both tire shoulder portions W1, W
Since the purpose of the block diagram shown in FIG. 4 is to know the strength and phase of the stiffness of No. 2, it is sufficient if it is based on the above equations (1) and (2). Furthermore, as shown in the block diagram of Fig. 4, when the shoulder width S is set to a fixed value,
The phase and amplitude ratios of Ax and Bx do not change even if the tire shoulder width S changes.

Figure 5 shows the Ax, Bx, RFV, LFV and Ax+ of the tire W obtained by the analog circuit in Figure 4.
Bx, Ax-Bx, both tire shoulder parts W1, W
This is a graph showing the FRRO of 2. In this Figure 5, Ax+Bx, RFV and Ax−Bx
It can be seen that the waveforms of both LFV and LFV are approximately the same. Also, both tire shoulder parts W1 and W2
FRRO does not match Ax and Bx, and the composite waveform also
Not consistent with RFV.

Furthermore, it has been confirmed through experiments that when part of the shoulder portions W1 and W2 of the tire W is buffed, the buffed portions of Ax and Bx shift to the negative side.

From the above, the correction of uniformity, namely
It is clear that the best way to modify RFV and LFV is to make the rigidities of Ax and Bx of the present invention uniform.

Also, if you buff the same phase using RFV as a reference,
It is also clear from Figure 5 that LFV deteriorates.

Next, when correcting the tire uniformity based on the principle of determining the tire stiffness described above, as shown in FIG.
Shoulder stiffness detector 4 by input from 3b
and output it to the computer 5. And in this calculator 5, if LFV is not within the preset range, LFV is the difference between Ax and Bx (≒ difference between Ay and By)
Therefore, when Ax and Bx are compared, when Ax is large, the peak position of Ax's LFV (-) is
When Bx is large, the LFV (+) peak position of Bx is buffed to correct the LFV.

6 to 8 a and b show examples of LFV correction, and FIG. 6 shows the waveform of Bx before buffing, with the upper side showing the + side and the lower side showing the - side.

Also, Fig. 7a is before buffing of Ax, and Fig. 7b is
Shows the waveform after Ax buffing, LFV(-)
By buffing the peak position P of
This is to correct the .

In addition, Figures 8a and 8b also show correction examples similar to the above, with Figure 8a being before Ax buffing, and Figure 8b being Ax before buffing.
The waveform after buffing is shown, and the LFV is corrected by buffing the peak position P of LFV(-).

In this LFV correction, the computer 5 detects a highly rigid part, and the computer 5 corrects the positional deviation between the grinding wheels 6a, 6b and the drum 2, and the load currents of the grinding wheel motors 7a, 7b are buffed symmetrically. Servo controller 9 so that the area is within a certain range.
Output signals to a and 9b, and drive the grindstone feed motor 10.
a, 10b.

All of the above operations are performed automatically, and the tire uniformity is automatically corrected.

〔Effect of the invention〕

In this invention, a drum is pressed against a rotating tire as described above, and the stiffness in the LF direction of the shoulder portions on both sides of the tire is determined using a load cell attached to the drum shaft that supports the drum. The LFV of the tire is corrected by comparing the stiffnesses of each and buffing the peak position of the one with greater stiffness. Since it is possible to correct LFV and therefore solve the problem of not being able to obtain a correction effect with tires as in the past, the correction effect is significantly greater than that of conventional tire correction methods. There is an effect that can be done.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a uniform machine embodying the present invention, Figs. 2 and 3 are principle explanatory diagrams showing a method for extracting the rigidity of a tire shoulder portion according to this invention, and Fig. 4 is an analog A block diagram showing the circuit, Fig. 5 shows the Ax, Bx, RFV, and
Graph explanatory diagrams comparing FRRO of LFV, Ax+Bx, Ax-Bx, and both tire shoulder parts W1 and W2, Fig. 6, Fig. 7 a, b, Fig. 8 a, b,
FIG. 6 is an explanatory diagram of waveforms showing an example of LFV correction. 2...Drum, 2a...Drum shaft, 3a, 3b
...X/Y load cell, W...tire, W1, W
2...Shoulder part of the tire.

Claims (1)

[Claims] 1 A drum is pressed against the rotating tire, and a load cell attached to the drum shaft that supports the drum is used to control the LF at the shoulder sections on both sides of the tire.
A tire uniformity correction method that corrects the tire's LFV by determining the stiffness in each direction, comparing the stiffness in the LF direction, and buffing the peak position of the larger stiffness.