JPS61258736A - Correction of tire uniformity - Google Patents

Abstract

PURPOSE:To correct LFV of a tire by a method wherein a drum is pushed against the rotating tire to obtain the rigidity in the direction of LF in both side shoulders of the tire through a load cell attached to the shaft of the drum and the position of peak of larger rigidity is worked by buffing. CONSTITUTION:Data of rigidity in the direction of X-axis (components in RF direction: Ax, Bx) and the rigidity in the direction of Y-axis (component in LF direction: Ay, By) of both shoulders W1, W2 of the tire W, which are detected by the X.Y load cells 3a, 3b, are obtained by a shoulder rigidity detector 4 and are outputted to a computer 5. When RFV and LFV are not in a preset range, the computer 5 detects a part of strong rigidities Ax, Bx and outputs signals to servo controllers 9a, 9b so that the correction for deviation of positions between grindstones 6a, 6b and the drum 2 as well as the load currents of load current detectors 8a, 8b, connected to grindstone motors 7a, 7b, enter a predetermined range at the objective place of buffing, whereby the buffing work may be controlled through grindstone-feeding motors 10a, 10b.

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.

[Prior art]

One of the uniformity characteristics of a tire is, for example, the characteristics of tire rigidity, that is, the radial force variation of the tire (the variation in force in the width direction of the tire under the condition of tire mounting is referred to as RFV) and the lateral force variation of the tire. (Tire installation is based on the condition where the force in the tire radial direction changes less than or equal to LFV.) However, in order to correct these RFV and LFV, it is generally effective to buff the tire shoulder area. Are known.

By the way, there are some methods for modifying the Juto RFV, such as the
As disclosed in Japanese Patent No. 4-31239, there is a method of correcting the part where radial force (hereinafter referred to as RF below the crab in the width direction of the tire in the tire mounting condition) is generated, and there is also a method similar to this. As a matter, Japanese Patent Application Laid-Open No. 1973-
83976, JP-A-54-129071, etc.

In addition, as disclosed in Japanese Patent Application Laid-Open No. 54-83975, there is a method for correcting an LFV, in which a lateral force (tire installation is less than a crab in the radial direction of the tire in the condition called LF) is generated. There is a method of buffing a shoulder part and a part which is shifted by 180 degrees from the other shoulder part.

However, both of these methods apply to RFV and LFV.
Despite the fact that is caused by the sum and difference of the stiffness of both shoulder parts, since buffing is performed based on the resultant force of stiffness, RFV and LFV, the stiffness fluctuations of the shoulder part are not uniform, and therefore RFV... There has been a problem in that if one characteristic of the LFV is corrected, the other characteristic deteriorates, and even after the correction, the tire uniformity characteristic deteriorates. In particular, LFV deteriorates significantly after correction. In addition, an attempt to correct uniformity, especially RFV, by individually detecting the stiffness of both shoulder parts of a tire is disclosed in U.S. Patent No. 3,
No. 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,
The roll whose rigidity is measured is (1) that the drum is a single piece, whereas the roller is divided into two parts; (2)
, the ground contact area of the tire differs due to the difference between the drum diameter and the roll diameter.
V and the force that the roller receives are different, and the waveform of the roller is rather a free radial runout (change in outer diameter on the lower two sides FR), which is a change in the surface displacement of the tire shoulder.
(referred to as RO).

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 tire stiffness when correcting tire uniformity, especially against stiffness fluctuations occurring from the shoulder of the tire. By comparing the sizes and buffing the peak position of the one with greater rigidity, the LF
The present invention provides a tire uniformity correction method that improves V characteristics.

[Structure of the invention]

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

[Embodiments of the invention]

The present invention will be described in detail below based on the accompanying drawings.

FIG. 1 shows a schematic configuration diagram of a uniformity machine embodying the present invention, where W is a tire rotatably supported on a support shaft 1, 2 is a rotatable drum pressed against the tire W,
3a and 3b are X-Y attached to both ends of the drum shaft 2a.
This X-Y load cell 3a shows a load cell (a sensor that converts force changes into voltage changes and outputs them).

3b, the stiffness of both shoulder portions of the tire W in the X-axis direction (RF force direction components: Ax, Bx) and the Y-axis direction stiffness (LF force direction component: Ay).

By) is obtained by the shoulder stiffness detector 4 and output to the computer 5.

When RFV and LFV do not fall within the preset range, this calculator 5 detects the rigid portions of Ax and Bx, and calculates the positional deviation between the grinding wheels 5a, 5b and the drum 2 from the calculator 5. Correction and grinding wheel motor 7a, 7
A signal is output to the servo controllers 9a, 9b so that the load currents of the load current detectors 8a, 13b connected to the buffing motors 8a, 13b are within a certain range at the symmetrical buffing locations.
10b.

Next, the principle of extracting the rigidity of the tire shoulder portions Wl and W2 of the present invention 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. 3a and 3b are attached.

Note that when measuring the uniformity of the tire W using the drum 2, both shoulder portions W1. of the tire W are measured as shown in FIG. It is generally known that high ground pressures X, , X, occur at W2. And, due to the ground pressures Xi and X2, both shoulder parts W1 and shoulder part 2 are
Press the drum 2 as shown at -OA and →B in FIG.

Also, the fluctuation in the sum of the X components (RF) of =6At=OB above is RFV, and the X component (RF) of −>A, =>B
As a result of experiments and research, it has been found that the difference between the two is the LFV.

This 1-OA, Ax which is the X component (RF) of <B.

13x can be taken out independently by combining the outputs of the XY load cells 3a and 3b according to the following formula. That is, A x = Ra (1 + AIS) + Rb (1-1
/S") +2d/S (La + Lb)...(
1) Equation.

B x = Ra(1-g/S) +Rb(1+ j!
/S) -2d/S (La + Lb)...(2)
formula.

Here, Ra and Rb are the outputs of the X component (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 b, i is the drum axis length, d is the drum radius, and S is the shoulder width of the tire W.

From equations (1) and (2) above, Ax
, take out Bx.

To explain the block diagram of FIG. 4 in more detail,
I"" A a indicates an amplifier that amplifies the load cell output to a possible voltage.

AS+Aff has a gain of (1+S#), A,
, AI is an amplifier with a gain of 0 times to (1-8).And in adder A, Ra(l+f/S) +
Rb (calculation of 〇 is performed to 1-S and input to All. Similarly, A H6 is Ra (1-j!/S) +Rb
(1+l/S) is calculated and input to A Hz.

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

AH is obtained by adding the output of A and the output of AIs,
Ra (1+l/S) +Rh (1-5/l) +
(La+Lb) Outputs 2d/S. Similarly, A1□ is A. By subtracting the output of A15 from the output of
Ra (1-j2/S) +Rb (1+S/l (L
a+Lb) Outputs 2d/S.

A: Addition of Ra+Rb is performed. Also, A17 is (
La−Hb) is added.

When the load applied to the tire W is offset from the output of A + r + A t z + A + b, the variation is found and A ry + A , a r
A r s and Az + AH.

Subtract the load from the AIS output to obtain Ax and Bx.

This is to obtain the output of RFV.

Similarly, LFV can be found by offsetting the weight of drum 2 from AI 7, so AI.

Perform subtraction of leverage.

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

However, from equation 21, even if the value of S is not given correctly, it does not affect the phases of Ax and Bx, so it is treated as a fixed constant in this analog circuit.

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 so that it corresponds to the shoulder width S according to the tire W. Also good.

In this invention, - Since the intention of the block diagram in FIG. 4 is to know the strength and phase of the rigidity of both tire shoulder parts Wl and W2, if it is based on the above equations (1) and (2), good. Further, 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+Bx, A of the tire W obtained by the analog circuit in Figure 4.
x-Bx, both tire shoulder parts-1. FRR of Enemy 2
This is a graph showing O. In this Figure 5,
It can be seen that the waveforms of Ax+Bx and RFV and Ax-Bx and LFV are substantially the same. Furthermore, the FRRO of both tire shoulder portions Wl and W2 do not match Ax and Bx, and the composite waveform also does not match RFV.

Furthermore, it has been confirmed through experiments that when part of the shoulder portion WLW2 of the tire W is buffed, the buffed portions of Ax and Bx shift to the negative side.

From the above, uniformity correction, that is, RFV,
The modification of LFV is Ax of this invention.

It is clear that the best way is to make the stiffness of Bx uniform.

Also, if the same phase is buffed using RFV as a reference, LFV
It is also clear from FIG. 5 that the

Next, when correcting tire uniformity based on the principle of determining tire rigidity described above, first, as shown in FIG. The rigidity is determined by the load cell 3a.

The shoulder stiffness is determined by the shoulder stiffness detector 4 based on the input from the shoulder stiffness detector 3b, and is output to the computer 5.

In this calculator 5, if LFV is not within the preset range, LFV is the difference between Ax and Bx (#Ay and B
y), compare Ax and Bx and find A
When x is large, the peak position of LFV (-) of Ax is
When Bx is large, the peak position of LFV (+) of Bx is buffed to correct LFV.

Figures 6 to 8 (al, (1)) show examples of LFV correction, and Figure 6 shows the waveform of Bx before buffing, with the upper side showing the + side and the lower side showing one side. .

In addition, FIG. 7(a) shows the waveform before buffing of Ax, and FIG. 7(bl shows the waveform after buffing of Ax). This is what I did.

8(a) and 8(b) also show examples of correction similar to the above, with FIG. 8(a) showing the waveform before buffing of Ax, and FIG. 8(bl showing the waveform after buffing Ax). , LFV is corrected by buffing the peak position P of LFV (=).

Such LFV correction is performed by detecting a highly rigid part using the calculator 5, and using this calculation m5, correcting the positional deviation between the grinding wheels 6a, 6b and the drum 2, and adjusting the grinding wheel motors 7a, 7.
A signal is output to the servo controllers 9a, 9b so that the load current b is within a certain range at the symmetrical buffing location, and control is performed via the grindstone feed motors 10a, 10b.

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

〔Effect of the invention〕

This invention presses a drum against a rotating tire as described above, and uses a load cell attached to a drum shaft that supports this drum to adjust the L at the shoulder portions on both sides of the tire.
The LFV of the tire was corrected by determining the F force direction stiffness, comparing the LF force direction stiffnesses, and buffing the peak position of the one with greater stiffness, so the LFV (± ) The LFV can be corrected by buffing the peak position P of the tire, which solves the problem of not being able to obtain the correction effect depending on the tire as in the past. There is an effect that can significantly increase the effect.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a uniformity machine embodying the present invention; FIGS. 2 and 3 are principle explanatory diagrams showing a method for extracting the rigidity of a tire shoulder according to the present invention;
FIG. 4 is a block diagram showing the analog circuit, and FIG. 5 shows the Ax of the tire W obtained by the analog circuit in FIG.
Bx, RFV, LFV, Ax+Bx, Ax-BX, both tire shoulder parts, graph explanatory diagram comparing -2 FRRO, FIG. 6, FIG. 7 (a), (1)). FIGS. 8(a) and 8(b) are explanatory diagrams of waveforms showing examples of LFV correction. . 2...Drum, 2a...Drum shaft, 3a, 3b...
・X/Y load cell, W...tire, Wl, W2...
・Shoulder part of the tire. Figure 6 Bx (buff 17I) Figure 7 (G) 711m (b) AI (before buff) Ax () (after) procedural amendment August 5, 1985

Claims (1)

[Claims] A drum is pressed against a rotating tire, and a load cell attached to the drum shaft that supports this drum is used to determine the stiffness in the LF direction of the shoulder sections on both sides of the tire.The stiffness in the LF direction is compared to calculate the stiffness. By buffing the larger peak position of the tire,
How to correct tire uniformity to correct FV.