JP6571499B2 - Rubber friction and wear test method - Google Patents

Description

  The present invention relates to a rubber friction and wear test method used for testing the friction and wear characteristics of rubber.

  For rubber products such as tires, laboratory tests are generally performed in order to quickly evaluate the friction and wear characteristics of rubber materials. As a test apparatus for that purpose, a disc-shaped rubber test member having a rotation axis parallel to the rotation axis of the grindstone is pressed against the outer peripheral surface of the disc-shaped grindstone, and the rubber test member is worn by rotating both. Lambone testing machines are well known. Such a test apparatus is disclosed, for example, in Patent Document 1 below.

  In the lambone tester, it is possible to appropriately give the percentage of the peripheral speed difference between the rubber test member and the grindstone with respect to the peripheral speed of the rubber test member, that is, the slip ratio. Therefore, the wear test can be performed under the condition that the slip ratio is maintained at a predetermined value. For example, the rubber test member corresponding to each of the reference rubber material and the newly developed rubber material is worn in a predetermined time. The wear resistance performance can be evaluated by comparing the amount of wear.

  In laboratory tests, it is effective to bring the characteristics of the simulated road surface closer to the actual road surface in order to improve the evaluation accuracy. Hard aggregate is fixed to the simulated road surface with an adhesive to form an asphalt road surface, etc. To be done. However, in the lambone tester using the outer peripheral surface of the disk as a simulated road surface as described above, a complicated operation is forced to attach the aggregate.

  On the other hand, when the disc-shaped rubber test member 92 is rolled on the turntable 91 as shown in FIGS. The operation of attaching the aggregate on the platform of the turntable 91 that becomes the road surface is convenient and convenient.

  However, in the tests as shown in FIGS. 6 and 7, even if the peripheral speed of the turntable 91 is constant, there is a difference in peripheral speed between the inside of the contact surface passing through the circumference A and the outside of the contact surface passing through the circumference B. It will be. The upward arrow shown in FIG. 7 represents the magnitude of the peripheral speed, and the peripheral speed is greater on the outside of the ground plane than on the inside. For this reason, in the rubber test member 92, the inner side of the grounding surface is dragged outward to generate a clockwise moment, which causes an extra lateral force LF, causing uneven wear and reducing the evaluation accuracy. There was a problem.

JP 2011-174821 A JP 2012-247301 A

  It is an object of the present invention to provide a rubber friction and wear test that can improve the evaluation accuracy in consideration of the influence of lateral force due to the peripheral speed difference in the contact surface when rolling the rubber test member on the turntable. It is to provide a method.

The above object can be achieved by the present invention as described below.
That is, the rubber friction wear test method of the present invention is a rubber friction wear test in which a rotating table is rotated and a disk-shaped rubber test member pressed on the table of the rotating table is rolled to test the friction wear characteristics. A test method,
A step of setting test conditions including a load to be applied to the rubber test member, a longitudinal force, and a lateral force;
Under the conditions of the set load and longitudinal force, the lateral force is measured by rolling the rubber test member at a plurality of different slip angles, and a relational expression between the plurality of slip angles and the corresponding lateral force. The process of seeking
Calculating a zero lateral force, which is a lateral force when the slip angle is 0 °, from the relational expression, and adding a zero lateral force to the set lateral force to obtain a corrected lateral force;
Deriving a slip angle for generating the corrected lateral force from the relational expression;
Applying the derived slip angle to the rubber test member and testing the friction and wear characteristics under the set load and longitudinal force conditions.

  In a so-called turntable type frictional wear test in which a rotating table like the present invention is rotated and a frictional wear characteristic is tested by rolling a disk-shaped rubber test member pressed on the table of the rotating table. Even when the slip angle is 0 °, a lateral force (referred to as a zero-time lateral force in the present invention) is generated in the rubber test member due to the peripheral speed difference in the ground contact surface. According to the rubber friction and wear test method of the present invention, the lateral force calculated in advance is calculated by adding the zero lateral force to the lateral force desired to be applied to the rubber test member. And the frictional wear test is performed at the slip angle that generates the corrected lateral force, so that the evaluation accuracy can be improved in consideration of the influence of the lateral force due to the peripheral speed difference in the contact surface.

Also, the rubber friction wear test method of the present invention is a rubber friction wear test in which a rotating table is rotated and a disk-shaped rubber test member pressed on the table of the rotating table is rolled to test the friction wear characteristics. A test method,
A step of setting test conditions including a load to be applied to the rubber test member, a longitudinal force, and a lateral force;
Under the conditions of the set load and longitudinal force, the lateral force is measured by rolling the rubber test member at a plurality of different slip angles, and a relational expression between the plurality of slip angles and the corresponding lateral force. The process of seeking
Calculating a zero lateral force, which is a lateral force when the slip angle is 0 °, from the relational expression, and adding a zero lateral force to the set lateral force to obtain a corrected lateral force;
Adjusting the slip angle of the rubber test member so as to generate the corrected lateral force, and testing the friction and wear characteristics under the conditions of the set load and longitudinal force.

  According to the rubber friction and wear test method of the present invention, the zero side force is calculated in advance, and the corrected lateral force is obtained by adding the zero side force to the lateral force to be applied to the rubber test member. Since the frictional wear test is performed by adjusting the slip angle of the rubber test member so as to be generated, the evaluation accuracy can be improved in consideration of the influence of the lateral force due to the peripheral speed difference in the contact surface.

  Further, in the rubber friction wear test method of the present invention, the rubber test member is formed of rubber having the same composition as the tread rubber of a tire, and the friction energy and the contact pressure obtained from the slip amount and the shear force are preliminarily determined for the tire. Preferably, the method further includes a step of measuring, and the step of setting the test conditions preferably sets a load, a longitudinal force, and a lateral force that are the same as the friction energy and the ground pressure measured in advance.

  According to this configuration, the correlation between the friction and wear characteristics obtained by the rubber friction and wear test and the actual friction and wear characteristics of the tire is good.

A perspective view schematically showing a rubber friction and wear test apparatus. FIG. 1 is a block diagram schematically showing the rubber friction and wear test apparatus of FIG. Plan view showing the rotating table and rubber test member The flowchart which shows the rubber friction abrasion test method of this invention Diagram showing the relationship between slip angle and lateral force The perspective view which shows the aspect which rolls a rubber test member on the base of a turntable. The top view which shows the turntable of FIG. 6, and a rubber test member

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 schematically show a rubber friction and wear test apparatus used in this embodiment. This test apparatus is configured to roll a disk-shaped rubber test member 2 on a turntable 1 serving as a simulated road surface. The turntable 1 has a rotary shaft 11 extending in the vertical direction, and a rotary drive unit 12 such as a servo motor is connected to the rotary shaft 11. The rotary drive unit 12 is configured so that the rotary base 1 can be driven to rotate via a rotary shaft 11.

  A shaft member 21 extending in the horizontal direction is attached to the rubber test member 2, and a rotation drive unit 22 such as a servo motor is connected to the shaft member 21. The shaft member 21 is fitted into the central portion of the rubber test member 2 and is fixed so as not to cause a displacement in the rotational direction with respect to the rubber test member 2. The rubber test member 2 is configured to be rotationally driven via the shaft member 21 by the rotational drive unit 22.

  Although not shown in FIG. 1, the shaft member 21 is supported by the support 3 via a bearing. The support 3 can be displaced in the vertical direction by an elevating mechanism 31 that can be configured by a known actuator, and the rubber test member 2 is pressed from above onto the platform of the turntable 1 by the downward displacement. Thus, the support 3 supports the rubber test member 2 pressed on the turntable 1 via the shaft member 21 so as to roll freely.

  The lateral force detector 4 detects the lateral force generated in the rubber test member 2 that rolls on the turntable 1. For example, a load cell can be used as the lateral force detector 4. In the present embodiment, the lateral force detector 4 is installed on the support 3, but is not limited to this as long as the lateral force of the rubber test member 2 can be detected. Moreover, although not shown in figure, the detectors, such as a load cell, for the purpose of detecting the load and front-back force which act on the rubber test member 2 are also installed.

  The swing mechanism 5 has a function of swinging the support 3 so that the rubber test member 2 turns to change the front-rear direction.

  The rotation drive unit 12, the rotation drive unit 22, the elevating mechanism 31, and the swinging mechanism 5 are electrically connected to the control unit 6, and are appropriately determined according to the necessity of each operation by a command signal from the control unit 6. It is comprised so that it may be controlled.

  The control unit 6 controls the rotation drive unit 12 and the rotation drive unit 22 to generate a peripheral speed difference between the turntable 1 and the rubber test member 2 to give a predetermined slip ratio. The slip ratio is expressed as a percentage of the peripheral speed difference with respect to the peripheral speed of the rubber test member 2.

  The control unit 6 controls the elevating mechanism 31 based on the displacement amount of the support 3 or the detected longitudinal load, and applies a predetermined load to the rubber test member 2.

  Further, the control unit 6 swings the support tool 3 under the control of the swing mechanism 5, and thereby controls the slip angle of the rubber test member 2 (angle SA shown in FIG. 3B). A detection result by the lateral force detector 4 is input to the control unit 6. Here, the slip angle is an angle formed by the traveling direction and the front-rear direction (rotational direction) of the rubber test member 2, in other words, a slip angle of the rubber test member 2 with respect to the traveling direction. Corresponds to the skid angle.

  In FIG. 3A, the rubber test member 2 is disposed directly beside the rotating shaft 11, and the vertical direction in the drawing is the traveling direction DD. The circumference C is a virtual line that is centered on the rotating shaft 11 and passes through the center point P of the turning motion of the rubber test member 2 accompanying the swinging of the support 3. The traveling direction DD is parallel to the tangent to the circumference C at the point P. The shaft member 21 (not shown in FIG. 3) of the rubber test member 2 extends in the normal direction of the circumference C at the point P, and the front-rear direction LD (rotation direction) of the rubber test member 2 orthogonal to the point C is a point. It is parallel to the tangent to the circumference C at P.

  In FIG. 3 (a), the rubber test member 2 rolls on the turntable 1 under the condition that the slip ratio is maintained at a predetermined value, and the angle formed by the traveling direction DD and the front-rear direction LD. That is, the slip angle is 0 °. Circumferences A and B are concentric circles around the rotation axis 11 and are virtual lines passing through the inside and outside of the ground contact surface of the rubber test member 2, respectively. As described above, even if the peripheral speed of the turntable 1 is constant, a difference in peripheral speed occurs between the inside of the ground contact surface passing through the circumference A and the outside of the ground contact surface passing through the circumference B. An extra lateral force LF1 acts on the rubber test member 2.

  FIG. 3B is a view in which the rubber test member 2 is turned clockwise from the state of FIG. When the slip angle SA is set to a value other than 0 ° in this way, the lateral force due to the peripheral speed difference in the contact surface acts on the rubber test member 2 in addition to the lateral force due to the slip angle SA, and the lateral force as a whole is increased. Force LF2 acts.

  An example of a rubber friction wear test method using the above apparatus will be described.

  First, in step S100, the frictional energy obtained from the slip amount and the shearing force and the contact pressure are measured for an actual tire whose wear friction characteristics are to be evaluated. The measurement of friction energy and contact pressure can be performed by a conventionally known method.

  In the next step S101, test conditions to be given to the rubber test member 2 are set so as to be the same as the frictional energy and the contact pressure measured in step S100. The test conditions set here are a load Fz, a longitudinal force Fx, and a lateral force Fy.

  In the next step S102, the rubber test member 2 is rolled at a plurality of different slip angles under the conditions of the load Fz and the longitudinal force Fx set in step S101. Measurement is performed by the detector 4. Thereafter, the relationship between a plurality of slip angles and the measured lateral force is plotted. Specifically, a predetermined number or more of slip angles are applied to the rubber test member 2 to measure the lateral force, respectively, and a plurality of slip angles and the measured lateral force are plotted on the horizontal axis as shown in FIG. Plot the lateral force as the vertical axis. In this example, the lateral force is measured while changing the slip angle by 1 ° in the range of −5 ° to + 5 °, and a total of 11 points are plotted.

  In the next step S103, a relational expression between a plurality of slip angles and the corresponding lateral force is obtained. Specifically, each point plotted in step S102 is linearly approximated to obtain an expression representing an approximate straight line. In this example, the equation of the straight line is y = 12.364x + 25.455.

In the next step S104, it is determined whether the square (R ² ) of the correlation coefficient R between the slip angle and the lateral force is 0.9 or more. In this example, R ² is 0.9735. When R ² is equal to or greater than 0.9, the flow proceeds to step S105, whereas, if ^{R 2} is smaller than 0.9, the process returns to step S102, the lateral force is measured by increasing the number of slip angle, ^{R 2} is Steps S102 to S104 are repeated until it becomes 0.9 or more.

  In the next step S105, a zero side force Fy0, which is a lateral force when the slip angle is 0 °, is calculated from the relational expression obtained in step S103, and the zero side force Fy is set to the lateral force Fy set in step S101. The corrected lateral force Fy ′ (= Fy + Fy0) is obtained by adding Fy0.

  In the next step S106, the slip angle SA for generating the corrected lateral force Fy 'is derived from the relational expression obtained in step S103.

  In the next step S107, the slip angle SA derived in step S106 is applied to the rubber test member 2, and a frictional wear test is performed under the conditions of the load Fz and the longitudinal force Fx set in step S101. Evaluate the friction and wear characteristics.

  According to the above, when the rubber test member is rolled on the turntable, the frictional wear test can be performed in consideration of the influence of the lateral force due to the peripheral speed difference in the contact surface. Can be increased. This also makes it possible to improve the correlation between the frictional wear characteristics obtained in the rubber frictional wear test and the actual frictional wear characteristics of the tire.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention, and the configuration and control contents of the apparatus can be changed as appropriate. It is. For example, the turntable is not limited to the one that rotates through the rotation shaft positioned at the center thereof, and may be driven to rotate by a rotating body adjacent to the rotation base. According to such a configuration, the rotation speed is controlled with high accuracy. It becomes easy.

  In the above-described embodiment, 11 points of the lateral force corresponding to the slip angle are plotted in step S102. However, the present invention is not limited to this, and it may be less or more than 11 points.

[Other Embodiments]
In the above-described embodiment, the slip angle for generating the corrected lateral force Fy ′ is obtained in advance from the relational expression, and this slip angle is given to the rubber test member 2 (slip angle control). The slip angle of the rubber test member 2 may be adjusted during the test so as to occur (lateral force control). That is, the rubber friction and wear test method according to the present invention rotates the turntable 1 and rolls the disk-shaped rubber test member 2 pressed on the turntable 1 to test the friction wear characteristics. A method for setting a test condition including a load Fz, a longitudinal force Fx, and a lateral force Fy to be applied to the rubber test member 2, and a condition for the set load Fz and the longitudinal force Fx. Then, the step of rolling the rubber test member 2 at a plurality of different slip angles to measure the lateral force to obtain a relational expression between the plurality of slip angles and the corresponding lateral force, and the slip angle from the relational expression Calculating a zero lateral force Fy0 which is a lateral force when the angle is 0 °, and adding the zero lateral force Fy0 to the set lateral force Fy to obtain a corrected lateral force Fy ′; The slip angle of the rubber test member 2 is adjusted so as to generate And a step of testing the friction and wear characteristics under the conditions of the set load Fz and the longitudinal force Fx that are set.

  Examples that specifically show the structure and effects of the present invention will be described below. The frictional wear test of the rubber test member without considering the influence of the lateral force due to the peripheral speed difference in the contact surface was set as Comparative Examples 1 and 2, and the frictional wear test of the rubber test member was performed by the method according to the present invention. These were designated as Examples 1 and 2. Comparative Example 1 and Example 1 were rubbers with the same formulation a, and Comparative Examples 2 and 2 were rubbers with the same formulation b.

  A tire having a tread rubber having the same composition as each rubber test member was subjected to a wear test, the wear evaluation result was indexed, and each rubber test member was subjected to a wear test, and the wear evaluation result was indexed. The smaller the difference in the wear evaluation index between the tire and the rubber test member, the better the correlation between the friction and wear characteristics obtained by the rubber friction and wear test and the friction and wear characteristics of the actual tire. These results are shown in Table 1.

  As shown in Table 1, in Examples 1 and 2, the difference in the results of wear evaluation between the tire and the rubber test member was smaller than in Comparative Examples 1 and 2.

1 rotating table 2 rubber test member 4 lateral force detector

Claims (4)

A rubber friction and wear test method for testing friction and wear characteristics by rotating a turntable and rolling a disk-shaped rubber test member pressed on the turntable,
A step of setting test conditions including a load to be applied to the rubber test member, a longitudinal force, and a lateral force;
Under the conditions of the set load and longitudinal force, the lateral force is measured by rolling the rubber test member at a plurality of different slip angles, and a relational expression between the plurality of slip angles and the corresponding lateral force. The process of seeking
Calculating a zero lateral force, which is a lateral force when the slip angle is 0 °, from the relational expression, and adding a zero lateral force to the set lateral force to obtain a corrected lateral force;
Deriving a slip angle for generating the corrected lateral force from the relational expression;
Applying the derived slip angle to the rubber test member and testing the friction and wear characteristics under the set load and longitudinal force conditions. A rubber friction and wear test method for testing friction and wear characteristics by rotating a turntable and rolling a disk-shaped rubber test member pressed on the turntable,
A step of setting test conditions including a load to be applied to the rubber test member, a longitudinal force, and a lateral force;
Under the conditions of the set load and longitudinal force, the lateral force is measured by rolling the rubber test member at a plurality of different slip angles, and a relational expression between the plurality of slip angles and the corresponding lateral force. The process of seeking
Calculating a zero lateral force, which is a lateral force when the slip angle is 0 °, from the relational expression, and adding a zero lateral force to the set lateral force to obtain a corrected lateral force;
Adjusting the slip angle of the rubber test member so as to generate the corrected lateral force, and testing the friction and wear characteristics under the set load and longitudinal force conditions. Wear test method.   The relational expression gives a predetermined number or more of slip angles to the rubber test member to measure the lateral force, plots the relationship between the slip angle and the measured lateral force, and linearly approximates each plotted point. The rubber frictional wear test method according to claim 1 or 2, wherein the formula represents an approximate straight line obtained. The rubber test member is formed of rubber having the same composition as the tread rubber of the tire, and further includes a step of measuring in advance the friction energy and the contact pressure obtained from the slip amount and the shearing force for the tire,
The step of setting the test conditions sets a load, a longitudinal force, and a lateral force that are the same as the friction energy and the ground pressure measured in advance. The rubber friction and wear test method described.

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