JP2013221856A - Method for analyzing road surface roughness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for analyzing road surface roughness for digitalizing road surface roughness so as to evaluate an influence on abrasion of a tire.SOLUTION: A method for analyzing road surface roughness includes: a step of measuring the road surface roughness; a micro roughness acquisition step of processing the measured road surface roughness by setting a small cutoff value; a macro roughness acquisition step of processing the measured road surface roughness by setting a cutoff value larger than the small cutoff value; and a step of specifying road surface roughness characteristics on a two-dimensional coordinates by a measurement value in the micro roughness acquisition step, and a measurement value in the macro roughness acquisition step.

Description

  The present invention relates to a road surface roughness analysis method.

  Vehicle tires are worn and damaged by running. Wear and damage is caused by friction with the road surface. Road surface roughness is closely related to tire wear and damage. The roughness of the road surface is measured and evaluated by various methods.

  As a method for analyzing the road surface roughness, “measuring the macro depth of the pavement surface by the volume method” defined in Annex F of JIS D8301 is known. The measurement method specified here is called the sand patch method. In this method, a large number of minute glass beads are scattered on the road surface. The glass beads are expanded in a circular shape so as to fill the recesses on the road surface. The diameter and volume of the glass beads expanded in a circular shape are measured, and the appropriateness of the slip resistance and noise characteristics of the road surface can be determined based on the measured values. This measuring method is effective for measuring macro texture on the road surface. However, this measurement method is not suitable for evaluating the influence on the tire running on the road surface because the shape, dimensions, and the like of the aggregate on the road surface are not objects of measurement.

  Road surface roughness is also evaluated by human sensuality. In this case, there may be a difference in the evaluation result due to the difference of the evaluator. Furthermore, it is difficult to express the evaluation result obtained by sensory sense as a measured value.

JIS D8301 Annex F

  The present invention has been made in view of the present situation, and an object of the present invention is to provide a road surface roughness analysis method capable of quantifying the road surface roughness so that the influence on the tire wear can be evaluated. Yes.

The road surface roughness analysis method according to the present invention includes:
Measuring the roughness of the road surface;
A micro roughness acquisition step for processing the measured road roughness by setting a small cutoff value;
Macro roughness acquisition step for processing the measured road roughness by setting a cutoff value larger than the small cutoff value;
The step of specifying the roughness characteristics of the road surface on two-dimensional coordinates by the measurement value in the micro roughness acquisition step and the measurement value in the macro roughness acquisition step is included.

  Preferably, the small cut-off value is a numerical value set within a range corresponding to the roughness of the road surface aggregate surface, and the large cut-off value is within a range corresponding to the size of the road surface aggregate. It is a numerical value set by.

  Preferably, the small cut-off value is 0.1 mm to 1.1 mm, and the large cut-off value is 10 mm to 40 mm.

  Preferably, the measurement of the roughness of the road surface is performed at intervals in the X axis direction and the Y axis direction orthogonal to each other on the road surface by scanning with a three-dimensional laser displacement meter.

  According to the road surface roughness analysis method of the present invention, the road surface roughness can be quantified so that the influence on the tire wear can be evaluated.

FIG. 1A is a perspective view showing a road surface shape replica used for measurement of road surface roughness according to an embodiment of the present invention, and FIG. 1B is a scan direction of replica roughness measurement. It is explanatory drawing which shows a pitch. FIG. 2 is a graph showing a process in which a deviation in roughness is obtained from the road surface roughness measured using the replica of FIG. FIG. 3 is a graph showing a process in which the road surface roughness shown in the graph of FIG. 2 is processed by the cutoff value. FIG. 4 is a graph expressing the measured road surface roughness distribution by macro roughness and micro roughness. 5 (a), 5 (b) and 5 (c) are graphs in which the road surface roughness distribution of FIG. 4 is classified and displayed according to the contents of the market complaint.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

Road surface roughness analysis method according to an embodiment of the present invention,
(1) a step of measuring road surface roughness;
(2) Obtaining each micro and macro roughness for processing the measured road surface roughness by setting a small cutoff value and a large cutoff value;
(3) It includes a so-called road surface roughness map creation step of specifying the road surface roughness characteristics on the two-dimensional coordinates based on the measured values in the micro and macro roughness acquisition steps.

  As shown in FIG. 1 (a), in the road surface roughness measurement step, the road surface shape of the traveling road to be measured is shaped (sampling). In sampling, a road surface replica 1 is collected by attaching a silicone impression material to the road surface. The surface roughness of the replica 1 corresponding to the road surface is measured. Only one replica 1 may be formed on one road surface, or a plurality of replicas 1 may be formed. The replica 1 is sampled over a range of 100 mm × 100 mm on the road surface. That is, the length x of the replica 1 is 100 mm, and the width y is also 100 mm. The planar view shape of the replica 1 in this embodiment is a square. The length direction (X-axis direction) of the replica 1 coincides with the traveling direction (lane direction) A of the traveling path, and the width direction (Y-axis direction) coincides with the width direction of the traveling path. In the present invention, the size of the replica 1 is not limited to 100 mm × 100 mm. Both the length x and the width y may be 100 mm or more, or less than 100 mm. However, a size of 100 mm × 100 mm or a size close thereto is preferable because it is easy to handle and the amount of data to be acquired is sufficient.

  The surface shape (road surface roughness) of the collected replica 1 is measured using a laser type three-dimensional measuring device (three-dimensional laser displacement meter) (not shown). This measuring device can measure the Z-axis direction dimension, which is a separation distance from the surface of the replica 1, using a laser beam in a non-contact manner. That is, the unevenness that is the roughness of the surface of the replica 1 can be measured. The measuring probe of the measuring instrument scans in the Y-axis direction of the replica 1 to continuously measure the roughness, and also scans in the X-axis direction to continuously measure the roughness. As shown in FIG. 1B, the Y-axis direction measurement scan 2Y of the replica 1 is 800 or more at intervals of 100 μm along the traveling direction (X-axis), and the X-axis direction scan 2X is perpendicular to the traveling direction. There are 160 or more at 500 μm intervals along the (Y axis). The scanning speed of the measurement probe is set to 46 mm / s. The scan pitch and scan speed are examples, and are not limited thereto.

Ｘ軸方向の偏差ＲａとＹ軸方向の偏差Ｒａとの平均値が、算術平均粗さ（単位：μｍ）とされる。 FIG. 2 shows a cross-sectional shape of the replica surface measured by scanning the measurement probe in the X-axis direction of the replica 1. This cross-sectional shape shows a roughness curve f (x) in the X-axis direction. The scan length is indicated by L in the X-axis direction. The Z axis represents roughness (unevenness). Although not shown, the roughness curve in the Y-axis direction is similarly obtained from the measurement value (cross-sectional shape) in the Y-axis direction. Hereinafter, the roughness in the X-axis direction will be described as a representative. The roughness deviation Ra in the X-axis direction is obtained from the roughness curve f (x) by the following mathematical formula.

The average value of the deviation Ra in the X-axis direction and the deviation Ra in the Y-axis direction is the arithmetic average roughness (unit: μm).

  The direct measurement value (original data) by the measuring instrument includes a large uneven component such as road swell. Waviness is a characteristic unrelated to road roughness. In the micro and macro roughness acquisition steps, cut-off values are employed to remove such unnecessary components from the original data. The cut-off value is a threshold value for excluding that a measured value that is equal to or higher than the cut-off value is not a value in a normal range (a value that is regarded as road surface roughness). The cut-off value is set to specify a range of values that are considered to be road roughness. Here, the value shown as the cutoff value corresponds to the size of the road surface unevenness in plan view. That is, the value indicated as the cutoff value is a value corresponding to the size of each unevenness in the X-axis direction or the Y-axis direction when viewed in the Z-axis direction.

  As illustrated in FIG. 3, in the micro and macro roughness acquisition steps, both measured values in the X-axis direction and the Y-axis direction are processed by applying two types of cut-off values, large and small. The Specifically, as shown in FIG. 3, the unevenness 3 having a size in which the value N in the X-axis direction exceeds the cutoff value is removed from the cross section of the road surface shown in FIG. (Indicated in white) As a result, the roughness Ra after the processing shown in FIG. 3 changes from the deviation Ra shown in FIG. 2 before the cutoff processing. Although not shown, the same processing as described above is performed for the roughness curve in the Y-axis direction.

  By this treatment, micro roughness and macro roughness can be obtained. The small cut-off value is selected from the range of 0.6 mm ± 0.5 mm. The large cutoff value is selected from the range of 25 mm ± 15 mm. The range of the two types of cut-off values is set as described above, as a rule of thumb, the roughness of the aggregate surface is in the range of 0.1 to 1.0 mm in plan view, and the size of the aggregate This is because it is understood that it is in the range of 10 to 30 mm in plan view. A small cut-off value removes aggregate dimensions and road waviness from the measured values, resulting in a measured aggregate surface roughness as micro-roughness. A large cut-off value eliminates road surface waviness, resulting in a measure of the aggregate itself as macro roughness. Further, the block on the tread surface of the tire generally has a longitudinal dimension of about 40 mm or more in plan view. Therefore, the cut-off value is preferably 40 mm or less in order to evaluate the wear of the ground contact surface of the block.

  If the small cut-off value is less than 0.1, it may be difficult to evaluate the wear of the tire on the target road surface. On the other hand, when the small cut-off value exceeds 1.1 mm, problems other than the problem caused by the roughness of the aggregate surface may occur on the tire. If the large cut-off value is less than 10 mm, the aggregate size may not be measured. On the other hand, if the large cut-off value exceeds 40 mm, problems other than the problem caused by the size of the aggregate on the road surface may occur with respect to the tire. A large cut-off value (25 mm ± 15 mm) is set in order to remove unevenness considered to be road surface waviness. A small cut-off value (0.6 mm ± 0.5 mm) is set in order to remove the size of the aggregate itself (aggregate size) and irregularities that are considered to be road swells.

  As described above, the micro roughness and the macro roughness of one road surface can be measured from one replica 1 by applying two kinds of cut-off values, large and small. One micro roughness measurement value and one macro roughness measurement value obtained from one replica 1 are provided. The roughness of the road surface can be specified from the micro viewpoint of the roughness of the aggregate surface, and the same road surface roughness can also be specified from the macro viewpoint of the size of the aggregate. This makes it possible to evaluate the road surface roughness by applying the data of wear claims and damage claims on the road surface in the market.

Based on the stress and strain generated in the tire due to friction with the road surface, the tire wear mechanism is roughly divided into the following two.
(1) abrasion due to scratching;
The wear of scratches is affected by the size of the road aggregate itself. When stress and strain are large, the rubber is destroyed and scraped. Such wear is likely to occur on rough road surfaces.
(2) Wear due to adhesion;
The roughness of the aggregate surface of the road surface affects the abrasion due to adhesion. When stress and strain are small, chemical bonds are broken by hysteresis loss of rubber. Such wear is likely to occur on a smooth road surface.

The relationship between the specific damage resulting from abrasion and road surface roughness is illustrated below.
(1) chipping;
Chipping is tire block damage due to cuts. Chipping is likely to occur on road surfaces where the angle of the aggregate is sharp or where the protruding height is high. The larger the aggregate, the sharper the angle and the higher the protruding height, so that chipping is likely to be induced.
(2) Early wear;
The larger the aggregate and the rougher the surface of the aggregate, the more easily the wear is promoted and the early wear tends to occur.
(3) H & T (Hill and Toe) wear;
H & T wear is the difference in the amount of wear between the first and last wear on the road surface in the tire block. It occurs mainly in the two stages of generation and growth. This slip is more likely to occur as the road surface is less likely to scratch or stick. That is, H & T wear tends to occur when the aggregate itself is small and the surface of the aggregate is smooth.

  The road surface roughness map creation step will be described with reference to FIG. This road surface roughness map is a graph with macro roughness with a large cutoff value on one of the vertical and horizontal axes and a micro roughness with a small cutoff value on the other axis. This is a plot of the roughness value of the course road surface. In the present embodiment, the horizontal axis represents macro roughness and the vertical axis represents micro roughness. First, the base of the road surface roughness map is created by setting 0.8 mm as the small cutoff value on the vertical axis and 25 mm as the large cutoff value on the horizontal axis. Actually measured road surface data is plotted on this base, and a road surface roughness map is completed. By displaying the actual wear claims for the market road surface plotted on the map, the correlation between various wear and road surface roughness can be confirmed.

  The wear damage claims for each plotted road surface are categorized as “chipping”, “early wear” and “H & T wear”. Chipping is indicated by a circle. Premature wear is indicated by a triangle. H & T wear is indicated by a cross. According to this road surface roughness map, the range of road surface roughness where “chipping” is likely to occur, the range of road surface roughness where “early wear” is likely to occur, and the road surface roughness where “H & T wear” is likely to occur Range assumptions are possible. That is, the road surface roughness can be analyzed from the viewpoint of tire wear and damage.

  5A to 5C show road surface roughness maps, respectively. FIG. 5A to FIG. 5C are graphs classified and displayed for each content of the market complaint based on the graph of FIG. In any graph, the vertical axis represents the micro road surface roughness with a small cut-off value of 0.8 mm, and the horizontal axis represents the macro road surface roughness with a large cut-off value of 25 mm. In FIG. 5 (a), the courses for which the “chipping” complaint was made are indicated by circles. In FIG. 5 (b), a course having a claim of “early wear” is indicated by Δ. In FIG. 5 (c), a course having a claim of “H & T wear” is indicated by “x”.

  When the wear complaints related to the road surface plotted on the road surface roughness map are displayed, the correlation between various types of wear and the road surface roughness can be confirmed. That is, from the road surface roughness map, there is a risk of any tire damage on the road surface due to the combination of the roughness due to the small cutoff value (0.8 mm) of the actual road surface and the roughness due to the large cutoff value (25 mm). It is possible to guess. The following is an example.

(1) The road surface roughness level at which chipping may occur is 7 μm or more and less than 9 μm at a cut-off value of 0.8 mm, and 20 μm or more and less than 70 μm at a cut-off value of 25 mm.
(2) The road surface roughness level at which early wear may occur is 5 μm or more and less than 9 μm at a cutoff value of 0.8 mm, and 20 μm or more and less than 70 μm at a cutoff value of 25 mm.
(3) The road surface roughness level at which H & T wear may occur is less than 5 μm at a cutoff value of 0.8 mm and less than 20 μm at a cutoff value of 25 mm.

  As cut-off values in FIGS. 5A to 5C, 0.8 mm and 25 mm are set. This is because, for example, an arbitrary numerical value cannot be set as a cutoff value in a specific roughness analysis program, and it is necessary to select from a plurality of prepared cutoff values. Is. Accordingly, in the present invention, as described above, the small cutoff value is preferably selected from the range of 0.6 mm ± 0.5 mm, and the large cutoff value is preferably selected from the range of 25 mm ± 15 mm.

  When the cutoff value is changed from 0.8 mm and 25 mm within the above-mentioned range (0.6 mm ± 0.5 mm and 25 mm ± 15 mm), FIG. 4 and FIG. 5A to FIG. The plurality of points plotted in (1) move in the directions of the XY axes on the graph while maintaining the distribution tendency. For example, when the small cut-off value is changed from 0.8 mm to a smaller 0.3 mm, the plot group on the graph is displaced downward so as to approach 0 while maintaining the mutual distribution tendency. When the large cut-off value is changed from 25 mm to smaller 15 mm, the plot group on the graph is displaced to the left so as to approach 0 while maintaining the mutual distribution tendency. When the cut-off value is changed to a larger value, the plot group is displaced upward or rightward in a direction away from 0 while maintaining the mutual distribution tendency. Therefore, the function as a road surface roughness map that can assume the type of tire damage from the road surface roughness is not impaired.

  The road surface roughness analysis method described above can be applied to the development of tires and the evaluation of test results therefor.

DESCRIPTION OF SYMBOLS 1 ... Replica 2X, 2Y ... (Replica) Measurement scan 3 ... Concavity and convexity exceeding cut-off value A ... Travel direction of vehicle (x, etc.) x ... (Replica) length y ... Width of replica

Claims (4)

A method for analyzing the roughness of a road surface,
Measuring the roughness of the road surface;
A micro roughness acquisition step for processing the measured road roughness by setting a small cutoff value;
Macro roughness acquisition step for processing the measured road roughness by setting a cutoff value larger than the small cutoff value;
A road surface roughness analysis method comprising: a step of specifying a roughness characteristic of the road surface on two-dimensional coordinates based on a measurement value in the micro roughness acquisition step and a measurement value in the macro roughness acquisition step.   The small cut-off value is a value set within a range corresponding to the roughness of the road surface aggregate surface, and the large cut-off value is set within a range corresponding to the size of the road surface aggregate. The road surface roughness analysis method according to claim 1, wherein the road surface roughness is a numerical value.   The road roughness analysis method according to claim 1 or 2, wherein the small cut-off value is 0.1 mm to 1.1 mm, and the large cut-off value is 10 mm to 40 mm.   The road surface according to any one of claims 1 to 3, wherein the measurement of the roughness of the road surface is performed by a three-dimensional laser displacement meter at intervals in the X-axis direction and the Y-axis direction perpendicular to each other on the road surface. Roughness analysis method.

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