JP7138025B2 - Rubber adhesion test method and rubber adhesion test system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber adhesion test method and a rubber adhesion test system.

The friction of rubber used in tires and the like is mainly classified into adhesive friction (adhesion) and deformation loss friction (hysteresis loss). Deformation loss friction is energy loss due to deformation of rubber caused by contact with a road surface, and can be evaluated by tan δ. Adhesive frictional force is a shearing force required to separate the rubber and road surface by contacting them, and is considered to depend on the real contact area and the adhesive force. In order to improve the friction performance, it is necessary to properly evaluate not only the hysteresis loss of rubber but also the adhesive friction.

As a method for evaluating the adhesive friction of rubber, Patent Document 1 discloses that a small contactor is pressed against the surface of a rubber test member to be tested, peeled off, and the maximum attractive force when peeled off is measured. Adhesive force is calculated as an evaluation value of adhesive friction by converting to adhesive force per area.

JP 2016-170138 A

By the way, it is thought that the surface temperature of highly heat-generating rubber is higher than that of rubber with low heat-generating property, even when rubbed on the same road surface. However, no particular consideration was given to the exothermicity of each rubber compound.

The present invention has been made with a focus on such problems, and for that purpose, it provides a rubber adhesion test method and a rubber adhesion test system capable of evaluating adhesive strength in consideration of heat build-up. That is.

In order to achieve the above objects, the present invention takes the following means.

That is, in the rubber adhesion test method of the present invention, at least one flat surface of the rubber test member is moved along the direction of the road surface while being pressed against a first road surface with a predetermined load. rubbing;
measuring a post-friction temperature, which is the temperature of the flat surface immediately after the friction treatment;
a step of adjusting the temperature of the flat surface, which has decreased over time immediately after the rubbing treatment, to the post-rubbing temperature;
The temperature-controlled flat surface is pressed against the second road surface for a predetermined contact time and then peeled off, the attractive force acting at the time of peeling off is measured, and based on the measured attractive force data, the adhesive force corresponding to the attractive force is specified. and a step.

As a result, by measuring the post-friction temperature, which is the temperature of the flat surface immediately after the friction treatment, and adjusting the temperature of the flat surface to the post-friction temperature, the adhesive strength is specified, which allows for a more practical application that takes heat build-up into consideration. Adhesive strength close to conditions can be evaluated.

BRIEF DESCRIPTION OF THE DRAWINGS The conceptual diagram which shows the rubber adhesion test method and adhesion test system of this invention. The flowchart which shows the rubber adhesion test method of this invention. FIG. 4 is a diagram showing the pressure measured during pressing and peeling of the rubber test member; The figure which shows the relationship between the maximum value of attraction, and contact time. The figure which shows the relationship between the time integral value of attraction, and contact time.

An embodiment of the present invention will be described below with reference to the drawings.

The rubber adhesion test method uses a rubber tester. The rubber test apparatus 1 is configured such that a block-shaped rubber test member 2 and a flat plate-shaped simulated road surface are relatively movable in at least two directions (X direction and Z direction). For this purpose, the rubber test member 2 is pressed against the first road surface 10 and then slid in the direction of the road surface (X direction) by a friction action, and the rubber test member 2 is pressed against the second road surface 12 and then pulled away. Adhesion measurement operations can be performed. The rubber test member 2 is attached to a plate 11, to which pressure sensors such as load cells are attached for detecting forces in three directions. In this embodiment, the simulated road surface (the first road surface 10 or the second road surface 12) is fixed and the plate 11 is configured to move, but the simulated road surface may move conversely.

The rubber adhesion testing system of the present embodiment includes the rubber testing device 1, the temperature sensor 21 (an example of a temperature measuring device), the heat transfer plate 22 (an example of a temperature controller), and the measurement results obtained by the rubber testing device 1. It has a measurement result storage unit 14 for storing, an adhesion force specification unit 15 for specifying the adhesion force from the measurement result, and a relational expression calculation unit 16 for calculating the relational expression between the adhesion force and the contact time. A controller for controlling the rubber testing apparatus 1 is provided with a drive control section 13 for controlling driving of the rubber testing apparatus 1 . In the present embodiment, the controller is provided with the measurement result storage unit 14, the adhesive force identification unit 15, and the relational expression calculation unit 16, but is not limited to this. At least one of the measurement result storage unit 14, the adhesive force identification unit 15, and the relational expression calculation unit 16 may be implemented in another device. In this embodiment, systemization is performed, but a person may operate the rubber testing apparatus 1 to measure the attractive force, and perform the processing performed by the adhesive force specifying unit 15 and the relational expression calculating unit 16. .

An example of a rubber adhesion test method using the above system will be described with reference to FIGS. 1 and 2. FIG.

First, in step ST1, the rubber testing apparatus 1 performs a friction process. In the friction step, the rubber test member 2 is slid a predetermined number of times along the road surface direction (X direction) while being pressed against the first road surface 10 with a predetermined load. Then the lower surface) is rubbed. In this embodiment, the first road surface 10 is dry, but the friction may be performed on a wet road surface, and it is preferable to reproduce the road surface condition to be evaluated. By rubbing the rubber test member 2 on the first road surface 10, the contact surface of the rubber test member 2 is changed in properties by heat, an adhesive layer is formed, and the adhesive strength is improved. In this embodiment, the rubber test device 1 slides the rubber test member 2 15 times while pressing it against the dry first road surface 10 at 300 kPa. The load and the number of slide movements can be changed as appropriate. Examples of the first road surface 10 include an actual road surface, a test road surface, a flat plate, and a road surface processed to have unevenness.

In the next step ST2, a surface temperature measurement process is executed. In the surface temperature measuring step, the temperature of the flat surface 2a of the rubber test member 2 immediately after the friction treatment (referred to as post-friction temperature t1) is measured. Immediately after the friction treatment is within 10 seconds, preferably within 3 seconds, after the end of the friction treatment.

In the surface temperature measurement step, the post-friction temperature t1 is preferably measured by a non-contact temperature measuring instrument. In this embodiment, the temperature is measured by the non-contact temperature sensor 21 .

In the next step ST3, a temperature control process is executed. In the temperature control step, the temperature of the flat surface 2a of the rubber test member 2, which has decreased over time immediately after the friction treatment, is adjusted to the post-friction temperature t1.

In the temperature control step, the temperature of the flat surface 2a is preferably controlled by a temperature controller that does not come into contact with the flat surface 2a. In this embodiment, the temperature of the flat surface 2a is adjusted by pressing the temperature-controllable heat transfer plate 22 against the side surface of the rubber test member 2 to heat it, but the present invention is not limited to this. The temperature of the flat surface 2a may be adjusted by pressing the heat transfer plate 22 against the plate 11 to indirectly heat the rubber test member 2 . Alternatively, a temperature-controllable chamber (not shown) may be provided, and the temperature of the flat surface 2a may be adjusted by adjusting the temperature of the entire rubber test member 2 in the chamber. The temperature control process is performed while measuring the temperature of the flat surface 2a with the temperature sensor 21 described above, for example.

In the next step ST4, the rubber testing device 1 performs an adhesion measurement step. In the adhesion measurement step, the flat surface 2a of the rubber test member 2 is pressed against the second road surface 12 for a predetermined contact time, then peeled off, and the attractive force acting at the time of peeling off is measured. Examples of the second road surface 12 include an actual road surface, a test road surface, a flat plate, and an uneven road surface. In this embodiment, hard sandstone having a smooth surface with a surface roughness Ra of 3 to 7 μm is used as the second road surface 12 . Either dry or wet road conditions can be set. The second road surface 12 used in the adhesion measurement process and the first road surface 10 used in the friction process may be the same or different.

In the next step ST5, the adhesive force corresponding to the attractive force is specified based on the measured attractive force data. For example, as shown in FIG. 3, the adhesive force may be the maximum value Fmax of the attractive force acting upon peeling off. By doing so, it is possible to calculate the adhesive force with a simple process.

Further, as indicated by diagonal lines in the figure, the adhesive force may be a value obtained by time-integrating the attractive force acting upon peeling off. The value of the measured attraction force is time-integrated based on the 0 axis. The time-integrated value corresponds to the hatched area in the figure. In this way, not only the maximum value Fmax of the attractive force but also the change over time is included, so that the influence of noise is reduced and the accuracy is improved. The direction in which the rubber test member 2 is pressed against the second road surface 12 is the Z direction. When the detected force Fz is positive, it is the pressing force. become a force of attraction.

The measurement of the attractive force in step ST5 is preferably performed a plurality of times (N times) with different contact times. Although N may be a natural number of 2 or more, the larger the number, the better. Further, in this embodiment, the contact time is 0 to 10 seconds, but the contact time is preferably 0.5 to 1.5 seconds. By setting the time to 0.5 to 1.5 seconds, the relaxation phenomenon of the rubber can be suppressed. This makes it possible to avoid factors of rubber viscoelasticity, such as changes in area due to relaxation, as the contact time becomes longer. Note that the determination of the adhesive force in step ST5 may be performed each time the attractive force is measured, or may be performed collectively after all the measurements are completed.

After all the measurements are completed (step ST6: YES), in step ST7, based on a plurality of measurement results, a relational expression between the adhesive force corresponding to the attractive force and the contact time is calculated. Specifically, as shown in FIGS. 4A and 4B, one measurement result is plotted with the adhesive force on the y-axis and the contact time on the x-axis, and each plotted point is approximated using an approximation formula. to calculate the relational expression. In the present embodiment, an approximation obtained by logarithmic approximation is used as a relational expression, y=αln(x)−β. α and β are coefficients. As an approximation method, the method of least squares is used. The logarithmic approximation is preferred since the adhesion varies logarithmically with contact time. However, the approximation is not limited to logarithmic approximation, and may be linear or polynomial approximation, for example.

FIG. 4A is a diagram showing the relationship between the adhesive force and the contact time, with the maximum value Fmax of the attractive force being the adhesive force. The circular marks in the figure are the measurement results of a certain compounded rubber, and the diamonds in the figure are the measurement results of another compounded rubber. The line in the figure indicates the logarithmic approximation. FIG. 4B is a diagram showing the relationship between the adhesive force and the contact time, using the time integral value of the attractive force as the adhesive force. It can be seen that the same tendency as in FIG. 4A is shown.

In the above-described embodiment, the speed at which the rubber test member 2 is pressed against the second road surface 12 and the speed at which it is peeled off is the same for all measurements, but this may be changed in various ways. By measuring the attractive force a plurality of times while varying the pressing speed and the peeling speed of the rubber test member 2, it is possible to make the same evaluation as when the rubber contact time is varied.

As described above, in the rubber adhesion test method of the present embodiment, the rubber test member 2 is pressed against the first road surface 10 with a predetermined load and moved along the direction of the road surface. A step (ST1) of friction-treating at least one flat surface 2a; a step (ST2) of measuring a post-friction temperature t1, which is the temperature of the flat surface 2a immediately after the friction treatment; A step (ST3) of adjusting the temperature of the surface 2a to the post-friction temperature t1, pressing the temperature-adjusted flat surface 2a against the second road surface 12 for a predetermined contact time and then peeling it off, and an attractive force acting at the time of peeling off. and determining the adhesive force corresponding to the attractive force based on the measured attractive force data (ST4, ST5).
As a result, the post-friction temperature t1, which is the temperature of the flat surface 2a immediately after the friction treatment, is measured, the attractive force is measured after adjusting the temperature of the flat surface 2a to the post-friction temperature t1, and based on the measured attractive force data, By specifying the adhesive force corresponding to the attractive force, it is possible to evaluate the adhesive force that is closer to the actual conditions in consideration of heat generation.

In this embodiment, the post-friction temperature t1 is measured by a non-contact temperature measuring instrument.
As a result, the post-friction temperature t1 can be measured without the temperature measuring device coming into contact with the adhesive layer formed on the flat surface 2a, so that the adhesive strength can be evaluated with higher accuracy.

In this embodiment, the temperature of the flat surface 2a is adjusted by a temperature controller that does not come into contact with the flat surface 2a.
As a result, the temperature controller can adjust the temperature of the flat surface 2a without coming into contact with the adhesive layer formed on the flat surface 2a, so that the adhesive strength can be evaluated with higher accuracy.

In this embodiment, the measurement of the attractive force is performed within two hours immediately after the friction treatment.
Since the adhesive strength decreases with the lapse of time, there is a possibility that the evaluation accuracy of the adhesive strength will decrease if two hours have passed since immediately after the friction treatment.

In this embodiment, the contact time is 0.5-1.5 seconds.
Due to the relaxation phenomenon, the stress (contact pressure) of rubber decreases over time, so if the contact time is long, there is a risk that the evaluation accuracy of the adhesive strength will decrease.

The rubber adhesion test system of this embodiment moves the rubber test member 2 along the direction of the road surface while pressing it against the first road surface 10 with a predetermined load. A drive control unit 13 that controls the rubber testing apparatus 1 so as to friction-process the flat surface 2a, a temperature measuring instrument that measures the post-friction temperature t1, which is the temperature of the flat surface 2a immediately after the friction process, and A temperature controller that adjusts the temperature of the flat surface 2a that has been lowered to a post-friction temperature t1; The rubber testing apparatus 1 is controlled by the drive control unit 13 so as to measure the acting attractive force, and has an adhesive force specifying unit 15 that specifies the adhesive force corresponding to the attractive force based on the measured attractive force data.
By using this system as well, it is possible to obtain the effects of the above method.

Although the embodiments of the present invention have been described above with reference to the drawings, it should be considered that the specific configuration is not limited to these embodiments. The scope of the present invention is indicated not only by the description of the above embodiments but also by the scope of claims, and includes all modifications within the scope and meaning equivalent to the scope of claims.

It is possible to adopt the structure adopted in each of the above embodiments in any other embodiment. The specific configuration of each part is not limited to the above-described embodiment, and various modifications are possible without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1... Rubber test apparatus 2... Rubber test member 2a... Flat surface 10... 1st road surface 12... 2nd road surface 13... Drive control part 15... Adhesive force specific part

Claims (6)

rubbing at least one flat surface of the rubber test member by moving the rubber test member along the direction of the road surface while pressing the rubber test member against the first road surface with a predetermined load;
measuring a post-friction temperature, which is the temperature of the flat surface immediately after the friction treatment;
a step of adjusting the temperature of the flat surface, which has decreased over time immediately after the rubbing treatment, to the post-rubbing temperature;
The temperature-controlled flat surface is pressed against the second road surface for a predetermined contact time and then peeled off, the attractive force acting at the time of peeling off is measured, and based on the measured attractive force data, the adhesive force corresponding to the attractive force is specified. A rubber adhesion test method comprising the steps of: The adhesion test method according to claim 1, wherein the post-friction temperature is measured by a non-contact thermometer. The adhesion test method according to claim 1 or 2, wherein the temperature of said flat surface is adjusted by a temperature controller that does not come into contact with said flat surface. The adhesion test method according to any one of claims 1 to 3, wherein the measurement of the attractive force is performed within 2 hours immediately after the friction treatment. The adhesion test method according to any one of claims 1 to 4, wherein the contact time is 0.5 to 1.5 seconds. The rubber testing apparatus is controlled so that at least one flat surface of the rubber test member is rubbed by moving the rubber test member along the direction of the road surface while pressing the rubber test member against the first road surface with a predetermined load. a drive control unit;
a temperature measuring instrument for measuring a post-friction temperature, which is the temperature of the flat surface immediately after the friction treatment;
a temperature controller that adjusts the temperature of the flat surface, which has decreased over time immediately after the rubbing treatment, to the post-rubbing temperature;
The rubber test device is controlled by the drive control unit so that the temperature-controlled flat surface is pressed against the second road surface for a predetermined contact time and then peeled off, and the attractive force acting at the time of peeling off is measured. and an adhesion force identifying unit that identifies an adhesion force corresponding to the attraction force based on the obtained attraction force data.

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