JP2021089210A - Method for evaluating friction - Google Patents

Abstract

To clarify the dependency of the hysteresis component of a frictional force on a temperature.SOLUTION: The method for evaluating a friction according to an embodiment is a method for measuring a frictional force when a rubber member or a resin member is let slide on a test surface. In the method, the test surface is a lubricated surface on which at least one of oil and powder of a material having a hexagonal crystal structure is applied, and the measurement is done at different temperatures.SELECTED DRAWING: Figure 1

Description

The present invention relates to a friction evaluation method.

It is known that the frictional force generated between a rubber member (for example, a tread portion of a pneumatic tire) and a friction surface (for example, a road surface) is composed of an adhesion component and a hysteresis component. In recent years, it has been required to clarify the size of the adhesion component and the size of the hysteresis component in the frictional force.

In order to meet this demand, as described in Patent Document 1, the friction coefficient when the rubber material is rubbed on the friction surface sprinkled with surfactant-containing water (water containing a surfactant) is measured. The first step, the second step of measuring the friction coefficient when the rubber material is rubbed on the friction surface sprinkled with water containing no surfactant (water containing no surfactant), and the first step. A friction evaluation method including a third step of calculating the difference between the friction coefficient measured in the above step and the friction coefficient measured in the second step has been proposed.

According to this method, the friction coefficient caused by the hysteresis friction is measured in the first step, and the friction coefficient caused by the adhesive friction and the hysteresis friction is measured in the second step. Therefore, the adhesive friction component is calculated in the third step. It is supposed to be done.

Japanese Unexamined Patent Publication No. 2016-200563

However, in reality, even if the friction surface is wetted with water containing a surfactant or the like, the adhesion component of the frictional force cannot be completely removed, and the magnitude of the hysteresis component cannot be known. Further, in recent years, there has been interest in the temperature dependence of the hysteresis component of the frictional force, but this cannot be known by the method of Patent Document 1.

Therefore, it is an object of the present invention to provide a method capable of clarifying the temperature dependence of the hysteresis component of the frictional force.

The friction evaluation method of the embodiment is a friction evaluation method performed by measuring the frictional force when a rubber or resin member is slid on a test surface, and the test surface is formed of an oil and a hexagonal crystal structure. It is characterized in that the lubrication surface is coated with at least one of the powder of the substance having the above, and the measurement is carried out at a plurality of different temperatures.

According to the above embodiment, the frictional force from which the adhesive component is removed can be measured by sliding the rubber member on the lubricating surface, and the temperature dependence of the hysteresis component can be measured by measuring at a plurality of different temperatures. Can be clarified.

The flowchart of the friction evaluation method of an embodiment. A flowchart confirming that a proper second simulated road surface has been created. The figure which shows the outline of the adhesive strength test. The figure which shows the example of the measurement result of the adhesive strength test. The figure which shows the outline of the 2nd test. The figure which shows the example of the measurement result of the 2nd test. The figure which shows the adhesion component and the hysteresis component by the difference of a road surface.

The embodiment will be described with reference to the drawings. It should be noted that the embodiments described below are merely examples, and those which have been appropriately modified without departing from the spirit of the present invention shall be included in the scope of the present invention.

<Overall process>
This embodiment is an embodiment for clarifying the size of the adhesion component and the size of the hysteresis component of the frictional force between the rubber member and the actual road surface.

As shown in FIG. 1, the friction evaluation method of the embodiment includes a first simulated road surface creating step (S1) for creating a first simulated road surface made of resin that reproduces the unevenness of the actual road surface, and macro unevenness and micro unevenness. The temperature dependence of the adhesive force between the rubber member and the resin surface in the second simulated road surface creation step (S2) in which the second simulated road surface is created by removing microscopic irregularities from the first simulated road surface having the above. Based on the results of the adhesive strength test (first test) step (S3) and the adhesive strength test (first test), the frictional force between the rubber member and the resin surface depends on the temperature of the adhesion component. the temperature-dependent coefficient a _i determination step of determining the coefficients a _i (S4), to measure the frictional force by sliding the rubber member on the bearing surface at a plurality of temperature conditions upon which the second simulated road surface and bearing surface a second test step (S5), the temperature dependence coefficient b _i determination step of determining the temperature-dependent coefficient b _i of the hysteresis component of friction force between the rubber member and the second simulated road surface based on the second test result (S6 ), And the frictional force of the rubber member against each of the actual road surface, the first simulated road surface and the second simulated road surface is measured at the reference temperature, and the frictional force of the rubber member with respect to the second simulated road surface is measured at a temperature other than the reference temperature. including friction force measuring step and (S7), and measured each frictional force and the temperature-dependent coefficient a _i, using the b _i seek adhesion component and hysteresis component of friction force calculating step (S8), the ..

<First simulated road surface creation process>
In the first simulated road surface creating step, a resin-made first simulated road surface that reproduces the unevenness of the actual road surface made of asphalt or the like is created. As a specific example of the production method, the unevenness of the actual road surface is molded with silicon rubber, the resin is poured into the silicon rubber mold, and the resin is cured to become the first simulated road surface. Examples of the resin used include a two-component mixed type resin, and a more specific example thereof includes a two-component mixed type urethane resin.

Here, the reason why the first simulated road surface and the second simulated road surface, which will be described later, is formed of resin is that the adhesive force between the rubber and the resin changes greatly depending on the temperature, and as a result, the rubber This is because the adhesion component of the frictional force between the member and the resin-based second simulated road surface changes greatly depending on the temperature. This temperature dependence is utilized in this embodiment as will be described later. That is, when the frictional force is measured while changing the temperature on the same surface of the resin property, the frictional force changes depending on the temperature, and this change in the frictional force can be regarded as being caused by the temperature change of the adhesive component. From this, it is possible to obtain the adhesion component and the hysteresis component of the frictional force. The temperature dependence of the adhesive force between the actual road surface made of asphalt or the like and the rubber is small.

The surface roughness of the first simulated road surface is preferably reproduced on the order of 1 μm when the surface roughness is measured by a needle-contact type surface roughness meter. Further, the first simulated road surface needs to have a hardness that does not cause a visually obvious deformation when the rubber member is pressed against the road surface. Specifically, it is preferable that the durometer type D hardness of the first simulated road surface is 80 or more and 84 or less. Further, the elastic modulus of the resin forming the first simulated road surface is preferably 10 times or more the elastic modulus of the rubber forming the rubber member. Further, the tensile strength of the resin forming the first simulated road surface measured by the method of JIS K 7113 is, for example, 55 MPa or more and 65 MPa or less.

<Second simulated road surface creation process>
In the second simulated road surface preparation step, the surface of the first simulated road surface is polished to remove the micro unevenness from the first simulated road surface having macro unevenness and micro unevenness, and the second simulated road surface is obtained. .. A fine-grained polishing cloth is used for polishing.

Here, the actual road surface is formed by embedding aggregates such as pebbles in a base material such as asphalt. The macro unevenness is a large unevenness based on the rough shape of the aggregate. Further, the micro unevenness is a small unevenness based on the fine unevenness on the surface of the base material, the fine unevenness on the surface of the aggregate, and the like. It is known that micro-concavities and convexities are effective for the hysteresis component of the frictional force, and by removing the micro-concavities and convexities from the first simulated road surface, the hysteresis component of the frictional force becomes smaller on the second simulated road surface.

<How to confirm that the second simulated road surface is appropriate>
It is confirmed by the method shown in FIG. 2 that an appropriate second simulated road surface has been created. First, as described above, micro unevenness is removed from the first simulated road surface to create a second simulated road surface (S2-1).

Next, the surface roughness of the first simulated road surface and the second simulated road surface are measured by a surface roughness meter (S2-2). The measured surface roughness data is taken into the frequency analyzer and frequency-analyzed (S2-3).

Here, among the waves obtained by frequency analysis of the surface roughness data of the road surface, a wave having a predetermined wavelength within a range of 0.1 mm or more and 1.0 mm or less is used as a reference, and a wavelength larger than the wavelength of the reference wave is used as a reference. It is considered that the wave is due to macro unevenness and the wave having a wavelength smaller than the reference wave wavelength is due to micro unevenness. Based on this idea, the frequency of a wave having a predetermined wavelength within the range of 0.1 mm or more and 1.0 mm or less among the waves obtained by frequency analysis of the road surface roughness data is set as the cutoff frequency. A filter that attenuates components having a frequency lower than the cutoff frequency and attenuates components having a frequency higher than the cutoff frequency is set as a low-pass filter (S2-4). Further, a filter that hardly attenuates the component having a frequency higher than the cutoff frequency and attenuates the component having a frequency lower than the cutoff frequency is set as a high-pass filter (S2-4).

Next, a low-pass filter is applied to the frequency analysis result of the surface roughness of the first simulated road surface, and a wave having a large wavelength is acquired. The waveform formed by synthesizing the waves acquired in this way can be regarded as reproducing the macro unevenness of the first simulated road surface. Therefore, the surface roughness (for example, arithmetic mean roughness) is calculated from the synthesized waveform (S2-5). The calculation result can be regarded as the surface roughness (macro surface roughness) based on the macro unevenness of the first simulated road surface. Similarly, a waveform is synthesized from the wave obtained by applying a low-pass filter to the frequency analysis result of the surface roughness of the second simulated road surface, and the surface roughness (for example, arithmetic mean roughness) is synthesized from the synthesized waveform. Is calculated (S2-5).

Next, the surface roughness (that is, macro surface roughness) of the waveform composed of waves obtained by applying a low-pass filter to the frequency analysis result of the surface roughness of the first simulated road surface and the surface of the second simulated road surface. The surface roughness (that is, macro surface roughness) of the waveform consisting of waves obtained by applying a low-pass filter to the frequency analysis result of roughness is compared. When the difference between the two is 5% or less, that is, when the difference between the two is 5% or less of either value (YES in S2-6), the first simulated road surface and the second simulated road surface have macro unevenness. Is judged to have hardly changed, and it is judged that the macro unevenness of the second simulated road surface is appropriate.

Next, a high-pass filter is applied to the frequency analysis result of the surface roughness of the second simulated road surface, and a wave having a small wavelength is acquired. The waveform formed by synthesizing the waves acquired in this way can be regarded as reproducing the micro unevenness of the second simulated road surface. Therefore, the surface roughness (for example, arithmetic mean roughness) is calculated from the synthesized waveform (S2-7). The calculation result can be regarded as the surface roughness (micro surface roughness) based on the micro unevenness of the second simulated road surface. When this surface roughness (for example, arithmetic mean roughness) is 10 μm or less (YES in S2-8), it is determined that the second simulated road surface has micro-concavities and convexities removed, and the second simulated road surface is microscopic. It is judged that the unevenness is appropriate.

When it is determined that the macro unevenness or micro unevenness of the second simulated road surface is not appropriate (NO in S2-6, NO in S2-8), the second simulated road surface is created so that each unevenness becomes appropriate. It will be fixed (S2-1).

The steps S2-3 to S2-8 are performed by a frequency analyzer or a computer connected thereto. The order of the steps from S2-5 to S2-6 and the steps from S2-7 to S2-8 may be interchanged.

<Adhesive strength test process>
On the other hand, a test is conducted to examine the temperature dependence of the adhesive force between the rubber member and the adhesive force test surface made of resin. As shown in FIG. 3, in this test, the rubber member 1 is pressed against the resin adhesive force test surface 2 with a predetermined load and then separated, and the force (N) required to separate is measured. A known device can be used for this measurement.

As the rubber member 1 in this test, the rubber member to be finally evaluated for friction is used. Further, the adhesive strength test surface 2 is formed of the same resin as the resin forming the first simulated road surface and the second simulated road surface. The reason is that if the resin is the same, the temperature dependence of the adhesive force (and the adhesive component of the frictional force) between the rubber member and the resin surface is the same, so the adhesive force test result (that is, the adhesive force test surface) This is because the temperature dependence of the adhesive force in 2) can be used for the temperature dependence of the adhesion component of the frictional force on the second simulated road surface. The adhesive strength test surface 2 is preferably the second simulated road surface itself, but may be the first simulated road surface, or may be a resin road surface prepared separately from the first simulated road surface and the second simulated road surface. good.

As the test temperature for investigating the temperature dependence of the adhesive force, it is necessary to select a temperature of 2 points or more, and it is more preferable to select a temperature of 3 points or more. When three or more temperature points are selected, the temperature is, for example, normal temperature (for example, 20 to 25 ° C.) and low temperature (for example, 0) at which the adhesion component of frictional force is expected to be about twice that at room temperature. 10 ° C.) and high temperature (for example, 35-40 ° C.) where the adhesion component of the frictional force is expected to be about 1/2 of that at room temperature. Then, at each temperature, the above measurement is performed. The measurement is performed in a state where the rubber member 1 and the adhesive strength test surface 2 have reached the test temperature. In this embodiment, the test is performed at three points of normal temperature, low temperature and high temperature.

Since the adhesive force between the rubber member and the resin surface changes greatly depending on the temperature, the adhesive force test result can be obtained as a measurement result that differs greatly depending on the temperature. An example of the measurement result is shown as a bar graph in FIG.

<Temperature dependence coefficient _ai determination process>
_{Next, based on the adhesive force test result, the temperature dependence coefficient ai} of the adhesion component of the frictional force between the rubber member and the resin surface is determined.

Specifically, first, as the temperature dependence coefficient of adhesion between the rubber member and the adhesion test surface, each of the coefficients a _i at another temperature T _i for the coefficients 1 at a certain reference temperature T _base is determined.

As an example of how to obtain it, linear regression is performed on the data of the adhesive force for each temperature by the least squares method or the like to approximate the change in the adhesive force with respect to the temperature change (for example, in FIG. 4, a bar graph). A function (which approximates the vertices of a plurality of bars) is obtained (an example of the function is shown by a straight line in FIG. 4). Based on Motoma' function, the proportion of adhesion at another temperature T _i of when the adhesive strength at a certain reference temperature T _base 1 is determined as the coefficient a _i at the temperature T _i. For example, the adhesive strength at the reference temperature T _base at room temperature is 26.0 N, the adhesive strength at the low temperature T ₁ (that is, i = 1) is 48.4 N, and the adhesive strength at the high temperature T ₂ (that is, i = 2). If the adhesive strength is 8.8 N, the coefficient _{a 1} is 48.4 / 26.0 = 1.86 at a temperature _{T 1,} the coefficient _{a 2} in temperature _{T 2} is a 8.8 / 26.0 = 0.34 ..

Here, as the reference temperature T _base and another temperature T _i, the temperature at the time of later-described frictional force measurement is selected. In the present embodiment, the normal temperature frictional force measurements above to be described later, shall be carried out at three points low and high temperature, room temperature is selected as the reference temperature T _base, low temperature T ₁ and high-temperature T ₂ as another temperature T _i Suppose that is selected.

Here, the adhesive force in the present embodiment is the force required to separate the rubber member pressed against the resin road surface as described above, and the frictional force when the rubber member slides against the road surface is agglomerated. The size is different from the wear component. However, with respect to temperature dependence, the adhesive strength and the adhesive component can be regarded as the same. _{Therefore, the temperature-dependent coefficient ai} of the adhesive force between the rubber member and the adhesive force test surface obtained as described above is the adhesive component of the frictional force between the rubber member and the adhesive force test surface as it is. It is defined as the temperature dependence coefficient _ai .

_{Further, the temperature dependence coefficient ai} of the adhesive force (or the adhesive component of the frictional force) on the adhesive force test surface can be used as it is for the entire surface formed of the same resin as the adhesive force test surface. The resin forming the adhesive strength test surface and the resin forming the second simulated road surface are the same. _{Therefore, the temperature dependence coefficient ai} of the adhesion component of the frictional force between the rubber member and the adhesive force test surface is the temperature dependence coefficient ai of the adhesion component of the frictional force between the rubber member and the second simulated road surface. It can be regarded as the same as _i.

_{As described above, the temperature dependence coefficient ai} of the adhesion component of the frictional force between the rubber member and the resin surface (specifically, the adhesive force test surface or the second simulated road surface) is determined.

By using the temperature dependence coefficient _ai , the adhesion component of the frictional force at each temperature can be obtained. That is, the adhesion component of friction force Datosuruto _{F3 adh} at a reference temperature T _base, adhesion component of friction force when the another temperature _{T i} is determined as _{a i} × _{F3 adh.}

<Second test process>
Further, a second test is performed in which a lubricant is applied to the second simulated road surface to form a lubricating surface, and the rubber member 1 is slid on the lubricating surface under a plurality of temperature conditions to measure the frictional force.

First, a lubricant is applied to the second simulated road surface. As the lubricant applied to the second simulated road surface, oil or powder of a substance having a hexagonal crystal structure is used. By applying these lubricants to the second simulated road surface, the adhesion component is removed from the frictional force between the rubber member 1 and the second simulated road surface, and the frictional force can be regarded as consisting only of the hysteresis component. ..

As the oil, vegetable oil, mineral oil or silicone oil having a viscosity of 10 cSt or more and 1000 cSt or less is suitable. An oil film is formed between the second simulated road surface and the rubber member 1 by applying the oil, but if the viscosity of the oil is 10 cSt or more, the phenomenon that the oil film is not easily broken by the convex portion of the second simulated road surface is unlikely to occur, and If it is 1000 cSt or less, the viscous resistance of the oil film does not easily affect the measurement of the frictional force.

A particularly preferable oil is a vegetable oil having a viscosity of 50 cSt or more and 500 cSt or less. Examples of vegetable oils include salad oil and olive oil. Note that cSt stands for Centistokes, and 1 cSt = 1 mm ² / s. Viscosity is measured by the method of JISZ8803.

Examples of the powder of the substance having a hexagonal crystal structure include graphite powder and molybdenum disulfide powder. These powders may be applied (sprayed) to the second simulated road surface as they are, or may be applied to the second simulated road surface together with the solvent. In a substance having a hexagonal crystal structure, the bond between the layers of the crystal structure is weak, and when a shearing force is applied, slippage easily occurs between the layers. Therefore, when a powder of a substance having a hexagonal crystal structure is applied to the second simulated road surface, lubricity occurs in the second simulated road surface.

Next, under a plurality of temperature conditions, a test is performed in which the rubber member is slid on the lubricating surface to measure the frictional force. As shown in FIG. 5, the rubber member 1 is arranged on the lubricating surface 3, and a load is applied to the rubber member 1 from above as shown by arrow A, along the lubricating surface 3 in the direction of arrow B. The rubber member 1 slides, and the frictional force at that time is measured. A known device can be used for this measurement. As the rubber member 1 in this test, the same rubber member 1 used in the adhesive strength test is used.

The test temperature of the second test is the same room temperature, low temperature and high temperature as in the adhesive strength test. The measurement is performed in a state where the rubber member 1 and the lubricating surface 3 have reached the test temperature.

In the second test, the frictional force measured on the lubrication surface 3 can be considered to consist only of the hysteresis component. The temperature dependence of the hysteresis component is not as great as the temperature dependence of the adhesion component, but it is slight. An example of the measurement result in the second test is shown as a bar graph in FIG.

<Temperature-dependent coefficient _{b i} determining step>
Then, based on the second test result, the temperature dependence coefficient b _i of the hysteresis component of friction force between the rubber member 1 and the second simulated road surface is determined.

Here, what was obtained in the second test was the temperature dependence of the hysteresis component of the frictional force between the lubricating surface 3 and the rubber member 1, but this temperature dependence is the second simulated road surface to which nothing is applied. It can be considered to be the same as the temperature dependence of the hysteresis component between the rubber member 1 and the temperature dependence of the hysteresis component between the second simulated road surface coated with water and the rubber member 1. Therefore, by obtaining the temperature dependency coefficient b _i of the hysteresis component of friction force between the rubber member 1 and the bearing surface 3, the temperature dependence coefficient b _i, second simulated road surface and the rubber member Nothing is applied 1 it can be treated as the temperature dependence coefficient b _i hysteresis components between and temperature dependence coefficients b _i of the hysteresis component and the second simulated road surface and the rubber member 1 the water is applied between.

In this step, as the temperature dependence coefficient of the hysteresis component of friction force between the rubber member 1 and the bearing surface 3, each of the coefficients b _i in another temperature T _i for the coefficients 1 at a certain reference temperature T _base is determined.

As an example of how to obtain it, linear regression is performed on the data of the second test for each temperature by the least squares method or the like, and a function that approximates the change of the hysteresis component with respect to the temperature change is obtained (example of the function). (Shown by a straight line in FIG. 6). Based on Motoma' function, the ratio of the hysteresis component in another temperature T _i of when the 1 hysteresis component at a reference temperature T _base is determined as the coefficient b _i at the temperature T _i.

Here, as the reference temperature T _base and another temperature T _i, the temperature at the time of later-described frictional force measurement is selected. In the present embodiment, the normal temperature frictional force measurements above to be described later, shall be carried out at three points low and high temperature, room temperature is selected as the reference temperature T _base, low temperature T ₁ and high-temperature T ₂ as another temperature T _i Suppose that is selected.

By using the temperature-dependent coefficient b _i with Motoma' as described above, the hysteresis component is obtained at each temperature. That is, the hysteresis component of friction force _F3 Datosuruto _his at a reference temperature T _base, adhesion component of friction force when the another temperature _{T i} is determined as _{b i} × _{F3 his.}

<Friction force measurement process>
_{Next, the frictional force F1 at the reference temperature T base} between the rubber member and the actual road surface, the frictional force F2 at the _{reference temperature T base} between the rubber member and the first simulated road surface, and the rubber member and the second reference temperature T and the frictional force F3 _base at _base, a rubber member and the temperature T _{i (i} is one or more) each of the frictional force F3 _i in between the second simulated road surface between the simulated road surface And are measured. The frictional forces F1, F2, F3 _base and F3 _i may be measured with nothing applied to all road surfaces (actual road surface, first simulated road surface and second simulated road surface), or all. It may be carried out in a state where water is applied to the road surface (actual road surface, first simulated road surface and second simulated road surface).

Here, in this embodiment the low temperature T ₁ and high temperature T ₂ as described above is selected as the temperature T _i. Accordingly, in the present embodiment, as a friction force between the rubber member and the second simulated road surface, a frictional force F3 _base at a reference temperature T _base, and the frictional force F3 ₁ at low temperature T _1, at a high temperature T ₂ The frictional force F3 ₂ is measured.

A known friction force measuring device can be used for the measurement. The measurement is performed in a state where the rubber member and each road surface have reached their respective temperatures.

The measured frictional force shall consist of an adhesion component and a hysteresis component. That is,
F1 = F1 _adh + F1 _his ... (Equation 1)
F2 = F2 _adh + F2 _his ... (Equation 2)
F3 _base = F3 _adh + F3 _his ... (Equation 3)
_{F3 i = a i × F3 adh} + b i × F3 his ··· ( Equation 4)
_{(F1 adh} in formula 1, F2 _{adh in formula 2, F3 adh} in formula 3 _{and ai} × F3 _adh in formula 4 are adhesion components in each frictional force, _{F1 his in formula 1, F2 his} in formula 2, formula 3 _{b i} × _{F3 his} hysteresis component in the friction force in the _{F3 his-and} formula 4 in)
Shall hold.

As shown here, since the measurement temperature of the frictional force is different between the formula 3 and the formula 4, the magnitudes of the adhesion component and the hysteresis component of the frictional force are different. Specifically, in the frictional force of adhesion component _{F3 adh} at a reference temperature T _base (see Equation 3), adhesion component of friction force when the another temperature _{T i} is _{a i} × _{F3 adh} (formula 4). _ai is a coefficient determined in the above-mentioned temperature dependence coefficient _{ai determination step.} Further, at the reference temperature T _base hysteresis component of friction force _{F3 his-time} (see Equation 3), the hysteresis component of friction force when the another temperature _{T i} is the _{b i} × _{F3 his} (see Equation 4) .. b _i is a coefficient determined by the temperature dependence coefficient b _i determining step.

As described above, in the present embodiment, the frictional force between the rubber member and the second simulated road surface is measured at the low temperature T ₁ and the high temperature T _{2 in addition to the reference temperature T base} , so that the equation 4 is F3 ₁ = a. ₁ x F3 _adh + b ₁ x F3 _his ... (Equation 4-1)
F3 ₂ = a ₂ x F3 _adh + b ₂ x F3 _his ... (Equation 4-2)
It consists of two equations.

<Calculation process>
Based on the above equations 1 to 4, the adhesion component F1 _adh and the hysteresis component F1 _his of the frictional force between the rubber member and the actual road surface are calculated. This calculation is performed, for example, by a computer. The following are assumed as the premise of the calculation.

As shown in Table 1, the actual road surface and the first simulated road surface are made of different materials and have the same surface roughness. Since the actual road surface is made of asphalt or the like, the first simulated road surface is made of resin, so if the adhesion component of the frictional force on the actual road surface is the reference value, the adhesion component of the frictional force on the first simulated road surface is the reference value. Greater. On the other hand, since it can be said that the actual road surface and the first simulated road surface have the same uneven state, it can be assumed that the hysteresis component of the frictional force is the same.

Further, as shown in Table 1, the first simulated road surface and the second simulated road surface have the same material but different surface roughness. Since both the first simulated road surface and the second simulated road surface are made of the same resin, it can be assumed that the adhesion components of the frictional forces on these road surfaces are the same. On the other hand, the surface roughness of the first simulated road surface includes micro-roughness, whereas the surface roughness of the second simulated road surface does not include micro-roughness, so that the frictional force on the second simulated road surface is included. It can be assumed that the hysteresis component of is smaller than the hysteresis component of the frictional force on the actual road surface or the first simulated road surface.

The above assumption is illustrated in FIG. 7. The grid-like portion in the bar graph of FIG. 7 represents the adhesion component, and the dot-shaped portion represents the hysteresis component. From the above, in Equations 1 to 4, F3 _adh = F2 _adh can be regarded as, and F2 _his = F1 _his can be regarded as. _{Utilizing this, the adhesion component F1 adh} and the hysteresis component F1 _his of the frictional force between the rubber member and the actual road surface can be obtained.

_{First, F3 adh} and F3 _his are obtained from Equations 3 and 4. As _{an example of a specific method for obtaining F3 adh} and F3 _his , all combinations of the two equations are extracted from the equation 3 and a plurality of equations 4 that hold for each temperature, and provisional from each combination. F3 _adh and provisional F3 _his are obtained, and the median value of the obtained plurality of provisional F3 _{adh and the value of F3 his when F3 adh} is the median value are the final F3 _adh. And F3 _his .

As a specific example, in the present embodiment, there are equations 3, equation 4-1 and equation 4-2 as equations for the frictional force on the second simulated road surface. From these three formulas, three combinations of the two formulas can be made. That is,
F3 _base = F3 _adh + F3 _his ... (Equation 3) and F3 ₁ = a ₁ x F3 _adh + b ₁ x F3 _his ... (Equation 4-1)
The first combination of
F3 ₁ = a ₁ x F3 _adh + b ₁ x F3 _his ... (Equation 4-1) and F3 ₂ = a ₂ x F3 _adh + b ₂ x F3 _his ... (Equation 4-2)
The second combination of, and F3 _base = F3 _adh + F3 _his ... (Equation 3) and F3 ₂ = a ₂ x F3 _adh + b ₂ x F3 _his ... (Equation 4-2)
Is the third combination of.

Since F3 _base , F3 ₁ and F3 ₂ have been clarified by measurement and a ₁ , a ₂ , b ₁ and b ₂ have been obtained, the simultaneous equations of the first combination are solved to provide a provisional F3. _Adh and provisional F3 _his can be determined. Similarly, Motomari is provisional _{F3 adh} and provisional _{F3 his-from} simultaneous equations of the second combination, provisional _{F3 adh} and provisional _{F3 his-is} determined from simultaneous equations of the third combination.

_{Ideally, the provisional F3 adh} and the provisional F3 _his will have the same value regardless of which simultaneous equations of the first to third combinations are solved. _{However, in reality, the provisional F3 adh} and the provisional F3 _{his to} be obtained are different for each simultaneous equation due to the measurement error of the frictional force and the like.

Therefore, the median of the three provisional F3 _adhs obtained is the final (in other words, formal) F3 _adh . Then, when F3 _adh is that value (that is, the median value described above), F3 _his is calculated from Equation 3 (may be Equation 4-1 or Equation 4-2), and is used as the final F3 _his .

Next, since F3 _adh = F2 _adh can be regarded as described above, the value of F3 _{adh can be entered as F2 adh} in Equation 2, and F2-F3 _adh can be calculated to obtain F2 _his .

Next, since F2 _his = F1 _his can be regarded as described above, the value of F2 _{his can be entered as F1 his} in Equation 1, and F1-F2 _his can be calculated to obtain F1 _adh .

_{As described above, the adhesion component F1 adh} and the hysteresis component F1 _his of the frictional force between the rubber member and the actual road surface can be obtained.

As described above, according to the method of the present embodiment, the adhesion component F1 _adh and the hysteresis component F1 _his of the frictional force between the rubber member and the actual road surface can be clarified.

<Change example 1>
An example of modification will be described. In this modification, as the temperature dependence coefficient a _i of adhesion component of friction force between the rubber member and the resin surface, the coefficient a ₁ in another one temperatures T ₁ for the coefficients 1 at a certain reference temperature T _base Is required. Further, as a temperature dependence coefficient b _i of the hysteresis component of friction force between the rubber member and the second simulated road surface, the coefficient b ₁ of the one temperature T ₁ of the alternative for the coefficients 1 at a certain reference temperature T _base is determined. Further, as a friction force between the rubber member and the second simulated road surface, a frictional force F3 _base at a reference temperature T _base, and the frictional force F3 ₁ at another temperature low T ₁ is measured.

Therefore,
F3 _base = F3 _adh + F3 _his ... (Equation 3)
F3 ₁ = a ₁ x F3 _adh + b ₁ x F3 _his ... (Equation 4)
There are two formulas. Since F3 _base and F3 ₁ are measured and the coefficients a ₁ and b _{1 are obtained, F3 adh} and F3 _his can be obtained by solving these two simultaneous equations. If F3 _adh and F3 _{his are obtained, the adhesion component F1 adh} and the hysteresis component of the frictional force between the rubber member and the actual road surface are obtained based on the formulas 1 and 2 in the same manner as in the calculation step of the above embodiment. F1 _his is required.

_{When the measurement error of the frictional force is small, F3 adh} and F3 _his with sufficiently high accuracy can be obtained by solving the simultaneous equations of the above two equations, and F1 _adh and F1 _his can be clarified.

<Change example 2>
Another example of modification will be described. In this modification, as a friction force between the rubber member and the second simulated road surface, a frictional force F3 _base at a reference temperature T _base, or another three-point temperature T _{i (i} = 1,2,3 · The respective frictional forces F3 _i (i = 1, 2, 3 ...) At) are measured. _{Further, at each temperature, the temperature dependence coefficient ai} (i = 1, 2, 3 ...) Of the adhesion component of the frictional force between the rubber member and the resin surface, and the rubber member and the second simulated road surface. temperature dependence coefficient of hysteresis component of friction force between the _b i (i = 1,2,3 ···) is obtained.

Therefore,
F3 _base = F3 _adh + F3 _his ... (Equation 3)
_{F3 i = a i × F3 adh} + b i × F3 his (i = 1,2,3 ···) ··· ( Equation 4)
You can make four or more formulas. All combinations of the two equations are extracted from these equations, _{and a provisional F3 adh} and a provisional F3 _his are obtained from each combination. Then, the median value of the obtained plurality of provisional F3 _{adh and the value of F3 his when F3 adh} is the median value are defined as the final F3 _adh and F3 _his .

<Change example 3>
Even if the second simulated road surface of the above embodiment is not used, the adhesion component and the hysteresis component of the frictional force between the rubber member and the actual road surface can be clarified.

Specifically, first, the same first simulated road surface preparation step (S1), adhesive strength test step (S3), and temperature dependence coefficient _ai determination step (S4) as in the above embodiment are performed.

Next, the second test of measuring the frictional force by sliding the rubber member under a plurality of temperature conditions on the lubricating surface coated with oil or powder of a substance having a hexagonal crystal structure is the above-described embodiment. It is performed not on the second simulated road surface as in the above, but on the first simulated road surface. That is, the frictional force is measured with the first simulated road surface as the lubricating surface. Then, based on the results of the second test, as the temperature dependence coefficient b _i of the hysteresis component of friction force between the rubber member and the bearing surface (first simulated road surface), another for the coefficients 1 at the reference temperature T _base 1 or each of the coefficients _{b i} in two or more temperature _{T i} is determined.

_{Next, the frictional force measurement step is performed. In this modified example, the frictional force F1 at the reference temperature T base} between the rubber member and the actual road surface and the reference temperature T between the rubber member and the first simulated road surface _{The frictional force F2 at the base and each frictional force F2 i at the temperature Ti} (i is one or two or more) between the rubber member and the first simulated road surface are measured. Here, it is assumed that the low temperature T ₁ and high-temperature T ₂ is selected as the temperature T _i.

It can be considered that the following equation holds for the measured frictional force.

F1 = F1 _adh + F1 _his ... (Equation 5)
F2 _base = F2 _adh + F2 _his ... (Equation 6)
_{F2 i = a i × F2 adh} + b i × F2 his ··· ( Equation 7)
_{(F1 adh} in equation 5, _{F2 adh} in Equation 6, the adhesion component in _{a i} × _{F2 adh} Each frictional force in Equation 7, _{F1 his-in} equation 5, _{b i} × _{F2 his} in _{F2 his-,} Formula 7 in the formula 6 Is the hysteresis component at each frictional force)
Next, each of the friction force measured and the temperature-dependent coefficient a _i, computation step of obtaining the adhesion component and hysteresis component of friction force using the b _i is performed. Specifically, first, F2 _adh and F2 _his are obtained from Equations 6 and 7. The specific method is the same as the method for obtaining F3 _adh and F3 _his from the formulas 3 and 4 in the above embodiment.

Next, since F2 _his = F1 _his can be regarded as described above, the value of F2 _{his can be entered as F1 his} in Equation 5, and F1-F2 _his can be calculated to obtain F1 _adh .

_{As described above, the adhesion component F1 adh} and the hysteresis component F1 _his of the frictional force between the rubber member and the actual road surface can be obtained.

<Change example 4>
The above embodiment is an embodiment for clarifying the magnitudes of the adhesion component and the hysteresis component of the frictional force between the rubber member and the actual road surface, and the temperature dependence of the hysteresis component was obtained in the embodiment. , Apart from such embodiments, only the temperature dependence of the hysteresis component may be determined independently.

If the frictional force is measured by sliding the rubber member on the lubricated surface coated with oil or the lubricating surface coated with powder of a substance having a hexagonal crystal structure, the measured frictional force is only the hysteresis component. Can be considered to consist of. If such measurements are made under a number of different temperature conditions, the temperature dependence of the measured frictional force can be considered equal to the temperature dependence of the hysteresis component.

This method of determining the temperature dependence of the hysteresis component can be used in various embodiments other than the above-described embodiment.

<Change example 5>
In the above embodiment, the frictional force between the rubber member and the actual road surface is investigated, but not only the rubber member but also the frictional force between the resin member and the actual road surface is investigated in the same manner as in the above embodiment. Can be done.

<Change example 6>
In the above embodiment, oil or a powder of a substance having a hexagonal crystal structure was applied to the second simulated road surface as a lubricant, but both oil and a powder of a substance having a hexagonal crystal structure were applied as a lubricant. May be applied to the second simulated road surface.

1 ... Rubber member, 2 ... Adhesive strength test surface, 3 ... Lubricating surface

Claims (5)

In a friction evaluation method performed by measuring the frictional force when a rubber or resin member is slid on a test surface.
The test surface was used as a lubricating surface to which at least one of oil and powder of a substance having a hexagonal crystal structure was applied.
A friction evaluation method, characterized in that the measurement is performed at a plurality of different temperatures. In a friction evaluation method for obtaining an adhesion component and a hysteresis component in the frictional force between a rubber or resin member and a friction surface.
A process of creating a first simulated road surface made of resin that reproduces the unevenness of the actual road surface as the friction surface, and
A step of creating a second simulated road surface by removing microscopic irregularities from the first simulated road surface, and
A step of performing a first test for examining the temperature dependence of the adhesive force between the member and the resin surface, and
Based on the result of the first test, another temperature of 1 or 2 or more with respect to the coefficient 1 at the _{reference temperature T base} as the temperature dependence coefficient of the adhesion component of the frictional force between the member and the resin surface. a step of obtaining the respective coefficients _{a i} in T _i,
At least one of oil and powder of a substance having a hexagonal crystal structure is applied to the second simulated road surface to form a lubricating surface, and the member is slid on the lubricating surface under a plurality of temperature conditions to provide a frictional force. And the process of performing the second test to measure
Based on the second test result, as the temperature dependence coefficient of the hysteresis component of friction force between the member and the bearing surface, each in a different one or more of the temperature T _i for the coefficients 1 at the reference temperature T _base a step of determining the coefficients _{b i} of
The frictional force F1 between the member and the actual road surface at the reference temperature T _base,
The frictional force F2 between the member and the first simulated road surface at the reference temperature T _base,
The frictional force F3 _base between the member and the second simulated road surface at the reference temperature T _base ,
And measuring the respective frictional force F3 _i in said one or more temperature T _i between the second simulated road surface and the member,
F1 = F1 _adh + F1 _his ... (Equation 1)
F2 = F2 _adh + F2 _his ... (Equation 2)
F3 _base = F3 _adh + F3 _his ... (Equation 3)
_{F3 i = a i × F3 adh} + b i × F3 his ··· ( Equation 4)
_{(F1 adh} in formula 1, F2 _{adh in formula 2, F3 adh} in formula 3 _{and ai} × F3 _adh in formula 4 are adhesion components in each frictional force, _{F1 his in formula 1, F2 his} in formula 2, formula 3 _{b i} × _{F3 his} hysteresis component in the friction force in the _{F3 his-and} formula 4 in)
The process of obtaining F3 adh and F3 _{his from Eqs.} 3 and 4 and the process of obtaining F3 adh and F3 his.
The process of calculating _{F2-F3 adh} based on Equation 2 to obtain _{F2 his , assuming that F3 adh} = F2 _adh.
The process of _{assuming that F2 his} = F1 _his and calculating _{F1-F2 his} based on Equation 1 to obtain F1 adh, and
A friction evaluation method comprising. In a friction evaluation method for obtaining an adhesion component and a hysteresis component in the frictional force between a rubber or resin member and a friction surface.
A process of creating a first simulated road surface made of resin that reproduces the unevenness of the actual road surface as the friction surface, and
A step of performing a first test for examining the temperature dependence of the adhesive force between the member and the resin surface, and
Based on the result of the first test, another temperature of 1 or 2 or more with respect to the coefficient 1 at the _{reference temperature T base} as the temperature dependence coefficient of the adhesion component of the frictional force between the member and the resin surface. a step of obtaining the respective coefficients _{a i} in T _i,
At least one of oil and powder of a substance having a hexagonal crystal structure is applied to the first simulated road surface to form a lubricating surface, and the member is slid on the lubricating surface under a plurality of temperature conditions to provide a frictional force. And the process of performing the second test to measure
Based on the second test result, as the temperature dependence coefficient of the hysteresis component of friction force between the member and the bearing surface, each in a different one or more of the temperature T _i for the coefficients 1 at the reference temperature T _base a step of determining the coefficients _{b i} of
The frictional force F1 between the member and the actual road surface at the reference temperature T _base,
The frictional force F2 between the member and the first simulated road surface at the reference temperature T _base,
And measuring the respective frictional force F2 _i in said one or more temperature T _i between the first simulated road surface and the member,
F1 = F1 _adh + F1 _his ... (Equation 5)
F2 _base = F2 _adh + F2 _his ... (Equation 6)
_{F2 i = a i × F2 adh} + b i × F2 his ··· ( Equation 7)
_{(F1 adh} in equation 5, _{F2 adh} in Equation 6, the adhesion component in _{a i} × _{F2 adh} Each frictional force in Equation 7, _{F1 his-in} equation 5, _{b i} × _{F2 his} in _{F2 his-,} Formula 7 in the formula 6 Is the hysteresis component at each frictional force)
The process of obtaining F2 adh and F2 _{his from Eqs.} 6 and 7 and the process of obtaining F2 adh and F2 his.
The process of _{assuming that F2 his} = F1 _his and calculating _{F1-F2 his} based on Equation 5 to obtain F1 adh, and
A friction evaluation method comprising. The friction evaluation method according to any one of claims 1 to 3, wherein the lubricated surface is a lubricated surface coated with a vegetable oil having a viscosity of 50 to 500 cst. The friction evaluation method according to any one of claims 1 to 3, wherein the lubricating surface is a lubricating surface coated with graphite powder or molybdenum disulfide powder.

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