JPH0364823B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for measuring tire uniformity, and more specifically, to a method for measuring tire uniformity, and more specifically, a method for supporting a drum that is pressed against a tire only by a load cell in the X-axis direction (RF direction). This invention relates to a tire uniformity measurement method that can simultaneously measure output in the Y-axis direction (LF direction).

[Prior art]

Conventionally, as a method of measuring tire uniformity, for example, both ends of a drum shaft are
Supported by a load cell, add the X-direction component and the Y-axis direction component to obtain the X-direction output (RF output) and Y-direction output (LF output), and calculate the variation (RFV, LFV). was.

In other words, in order to determine the X-direction component and Y-axis component of a tire with a conventional Uniformity machine, two combined load cells, an X-axis load cell and a Y-axis load cell, are required. It was difficult to simplify the mechanical structure of the machine, and it was also difficult to reduce costs.

[Purpose of the invention]

This invention was devised by focusing on the conventional problems, and its purpose is to
To provide a method for measuring tire uniformity, which is supported by only an axial load cell and can simultaneously extract and measure output in the Y-axis direction.

[Structure of the invention]

In order to achieve the above object, this invention presses a drum against a rotatably supported tire, determines the difference in output in the X-axis direction using two X-axis load cells attached to both ends of the drum, and calculates the difference in the output of the drum. The gist of this is to obtain the output in the Y-axis direction by correcting it with a constant determined from the diameter and drum axis length.

[Embodiments of the invention]

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

1 and 2 show a front view and a bottom view of a schematic configuration diagram of a tire uniformity machine embodying the present invention, which is rotatably supported on a support shaft 1. Drum 2 is attached to the tire W that has been
It is shown that the fluctuations in the force generated by the tire W are measured by load cells 4a and 4b (pressure sensors that convert pressure changes into voltage changes and output them) attached to both ends of the tire shaft 3 against which the tire W is pressed.

Then, the output in the X-axis direction (RF: force in the radial direction) generated from the tire W by the load cells 4a and 4b of the uniform machine as described above,
A method for simultaneously obtaining the output in the Y-axis direction (LF: force in the lateral direction) will be described below.

FIG. 3 shows an explanatory diagram schematically representing FIG. 1, and shows load cells 4a provided at both ends of the drum shaft 3,
The positions of 4b are designated as points A and B, respectively, and the contact point between the tire W and the drum 2 is designated as C.

Then, when the output in the X-axis direction (RF) and the output in the Y-axis direction (LF) generated from the tire W are applied to point C, the moment force of RF/2 and LF (-KLF ), and on the other hand, at point B, the resultant force of RF/2 and LF moment force (KLF) acts.

Here, K is a constant determined by the ratio of the radius d of the drum 2 and the drum axis length l.

Therefore, it is clear that d.LF=l.KLF, d=lK, and therefore K=d/l.

That is, the output in the X direction of the load cell 4a at point A is
Ra, the output in the X direction of load cell 4b at point B is Rb
Then, Ra and Rb can be divided by the following formula.

Ra=RF/2−KLF, Rb=RF/2+KLF, however, K=d/l, From this formula, LF becomes the following formula.

LF=l/2d(-Ra+Rb)...(1) From the right side of equation (1), the left side of the output (LF) in the Y-axis direction can be determined from the two load cells 4a and 4b in the X-axis direction.

Here, regarding the number of poles of LF, equation (1) is LF=d/l(Ra−Rb)…(1)′ It's good as well.

Furthermore, since C is actually a plane, the RF forces acting on A and B will not match perfectly unless the pressure distribution within the plane is uniform.

However, in reality, the in-plane pressure distribution is approximately uniform, so the error is sufficiently small with respect to KLF, and as shown in Figures 5, 6, and 7, which will be described later, (1 ), (1)′ holds true.

Load cell 4 of the above uniform machine
An electrical circuit for simultaneously obtaining the output in the X-axis direction (RF: radial direction force) and the Y-axis direction output (LF: lateral force) generated from the tire W by a and 4b is as follows. For example, it becomes as shown in FIG.

That is, in FIG. 4, Ra and Rb are two load cells, 5a and 5b are amplifiers, and an adder 6.
and subtractor 7, RF: radial direction force,
LF: Find the force in the lateral direction.

Next, the two load cells Ra in this invention
and Rb, two types of tires W1, W2, W3 (Fig. 5 a to 5 c), (Fig. 6 a to 6 c) and (Fig. 7 a to 6 c) 7c) The waveforms obtained by measuring the force fluctuations are compared to the waveforms obtained by measuring the force fluctuations of the tire W measured using the conventional X-axis load cell and Y-axis load cell (Fig. 5d), (Fig. 6)
This will be explained while comparing with Figure d) and (Figure 7 d).

Figures 5a, 6a, and 7a are load cells.
The measured waveforms on the Ra side, Figures 5b, 6b, and 7b are the measured waveforms on the load cell Rb side, and Figures 5c, 6c, and 7c are the Ra and Rb The waveform shown is a composite of the .

Waveforms that synthesize Ra and Rb (Fig. 5c, 6)
Figure c, Figure 7c, and the waveform of tire W measured with a conventional Y-axis load cell (Figure 5d), (Figure 6d),
When compared with (FIG. 7d), it can be seen that the waveforms substantially match.

That is, the output in the Y-axis direction can be measured by the load cells Ra and Rb in the X-axis direction.

〔Effect of the invention〕

In this invention, a drum is pressed against a rotatably supported tire as described above, and two X-axis load cells attached to both ends of this drum are used to determine the difference in output in the X-axis direction, and this is calculated based on the diameter of the drum. Since the output in the Y-axis direction is determined by correcting it with a constant determined from the drum axis length, there is no need for load cells in the X- and Y-axis directions as in the past, which simplifies the mechanical structure and makes it easier to This has the effect of reducing the cost of the Omitei machine.

Moreover, it is particularly effective when applied to a simple uniformity machine.

[Brief explanation of drawings]

Figure 1 is a front view of the Uniformity Machine embodying the present invention, Figure 2 is a bottom view of Figure 1, Figure 3 is a schematic illustration of Figure 1, and Figure 4 is the Uniformity Machine. Explanatory diagram showing the measurement circuit of Teimasin, No. 5
Figures a to 5d, Figures 6a to 6d, and Figures 7a to 7d show two load cells Ra of the present invention.
The waveforms obtained by measuring the force fluctuations of two types of tires W1 and W2 with a uniform machine using Rb and the waveforms obtained by measuring the force fluctuations of tire W measured with a conventional X-axis load cell and Y-axis load cell. It is a graph explanatory diagram for comparison. 2...Drum, 4a, 4b...Load cell (Ra,
Rb), W...Tire, d...Drum diameter, l...Drum shaft length, K...Constant, RF...Output in the X direction, LF...Output in the Y direction.

Claims (1)

[Claims] 1 A drum is pressed against a rotatably supported tire, and the difference in output in the X-axis direction is determined using two X-axis load cells attached to both ends of the drum, and this is calculated using a constant determined from the drum diameter and drum axis length. A method for measuring tire uniformity, characterized in that an output in the Y-axis direction is determined by correction.