JP2967295B2 - Method and apparatus for measuring dynamic frictional resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for measuring dynamic frictional resistance, which is used for measuring dynamic frictional properties of rubber and other substances used in, for example, tires, footwear, casters and the like, and a method thereof. Related to the device.

[Prior Art] Conventionally, as a method and an apparatus for measuring dynamic friction resistance,
The following are known.

(1) Using a so-called Portable Skid Resistance Tester, the object to be measured attached to the plate at the tip of the pendulum arm is slid on a board on which a frictional body is stuck, and then the swing is performed. The one that determines the rising height as dynamic friction resistance (ASTM-E303-74).

(2) An object to be measured is mounted on a plate, and at least one of the plates is rotated in a state where the friction plate is in contact with a certain surface of the object to be measured. Alternatively, the torque is detected as the torque of a plate on which an object to be measured is attached (Japanese Patent Laid-Open No. 61-117430).

(3) The sliding element attached to the tip of the arm is brought into contact with the rotating disk-shaped sliding member, and the kinetic frictional resistance generated by this is defined as the rotational moment force of the arm.
Measurement using magnification of lever (Japanese Patent Laid-Open No. 61
-258145).

[Problems to be Solved by the Invention] As shown in the above (1), in the measurement in which the object to be measured attached to the plate at the tip of the pendulum arm is slid on the board on which the friction body is stuck, When used for rubber used in tires, there is a problem that the friction speed of an object to be measured is considerably slower than the actual friction speed of a tire, and does not match the tire running conditions.

In addition, since a fixed position of the object to be measured is forcibly rubbed against the friction body, the object to be measured is easily worn by repeating the pendulum sliding friction, so that the sliding friction distance and area change. . In addition, the degree varies depending on each object to be measured, especially when the friction body is not wet with water or the like, and the tendency is strong.Since the measurement conditions are not constant, the measured values vary, and the reproducibility is increased. There are problems such as poor.

As shown in the above (2), the object to be measured is attached to the plate, and at least one of the plates is rotated while the friction plate is in contact with a fixed surface of the object to rub both surfaces. When the dynamic frictional resistance that occurs when the frictional force is detected as a torque of a friction plate or a plate on which an object to be measured is to be detected, the detection force must be electrically amplified.

Further, as a problem common to the above (1) and (2),
For one thing, a large friction area of the friction body may be required. That is, in order to increase the measurement accuracy, the friction surface must be made uniform. However, since it is difficult to obtain such a surface over a wide range, it is difficult to obtain high measurement accuracy.

Secondly, for example, in the case of a car tire or the like, the tread rubber of the tire receives kinetic friction resistance while rotating at the time of driving or cornering, but it is possible to measure the kinetic friction resistance of the measured object in such a state. Therefore, there is a problem that it is difficult to grasp the dynamic friction characteristics generated during actual use.

As shown in (3) above, if the detection power is amplified using the leverage principle, amplification can be performed with higher precision than electrical amplification, but the sliding element comes into contact with the disk. There is a problem that it is not suitable for measurement of an object to be measured, such as a tire, on a sliding member having a shape like a tire.

The present invention has been made in view of the above-described problems, and takes a form of use such as a tire, with good reproducibility of dynamic frictional resistance of various substances including a rubber under conditions suitable for an actual use state. Making measurement possible is an issue to be solved.

[Means for Solving the Problems] Means taken in the present invention to solve the above problems will be described with reference to FIG. 1. According to the first aspect of the present invention, a friction plate 2 is provided on a rotatable measuring plate 1. And a means for detecting a dynamic frictional resistance force caused by bringing the outer peripheral surface of the circular object 3 to be driven and rotated into contact with the friction body 2 as a rotational moment force of the measurement plate 1. .

According to the second aspect of the present invention, the measuring plate 1 that can rotate around the rotating shaft 4, the friction body 2 attached to the measuring plate 1, and a force meter that measures the rotational moment force of the measuring plate 1. 5 and a circular object 3 whose outer peripheral surface rotates in contact with the friction body
And a driving device 6 for rotating the rotating member.

[Operation] In the present invention, it is only necessary to measure the force by which the measuring plate 1 tries to rotate.
In this case, the range of the friction surface of the friction body 2 for maintaining uniformity is sufficient with a small range. Therefore, measurement with a large number of friction bodies 2 having different friction surface states and materials is facilitated.

In the present invention, the outer peripheral surface of the DUT 3 that is driven and rotated is brought into contact with the friction body 2 so that, for example, a dynamic friction resistance corresponding to driving or cornering of an automobile tire or the like can be measured. Is what you do. At the same time, when the rotational speed of the DUT 3 is continuously or intermittently changed by recording and measuring the dynamic friction resistance together with the rotation speed of the DUT 3, or the driving body 5 is stopped, It also makes it possible to know the speed dependency of the dynamic frictional resistance when the rotation is decelerated only by the force.

Furthermore, the fact that the dynamic frictional resistance of the DUT 3 is detected as the rotational moment force of the measuring plate 1 is that the distance from the rotation center of the measuring plate 1 to the friction body 2 is increased, so that it is smaller than the electric amplification. Thus, the detection power can be accurately amplified.

[Embodiment] FIG. 1 is an explanatory view of an embodiment of the present invention, which will be described below.

In the figure, reference numeral 1 denotes a measuring plate, on the lower surface of which a rotating shaft 4 is attached. The measuring plate 1 is supported by the rotating shaft 4 and is rotatable around the rotating shaft 4.

A force meter 5 is provided on one side of the measuring plate 1 so that the rotational moment force can be measured when the measuring plate 1 is about to rotate.
Is attached. A friction body 2 is mounted on the other side of the measurement plate 1 (the side opposite to the dynamometer 5 across the rotation shaft 4).

The measured object 3 is located in contact with the friction body 2. The DUT 3 has a circular shape, an outer peripheral surface of which is in contact with the friction body 2. One end of a drive shaft 7 is connected to the center of the DUT 3, and is driven to rotate.

Here, the friction body 2 will be further described.
May have a grindstone or a non-slip sheet-like friction surface generally used for measuring dynamic frictional resistance, but it is preferable that the friction surface is provided with uneven strips at constant intervals in a certain direction. A friction body 2 having a friction surface in which the uneven strips are arranged in parallel
Has less wear on the object 3 and clogging due to the measurement,
Repeated measurement can be easily performed without changing measurement conditions. The frequency given to the object 3 is determined by the irregularities and the rotation speed of the object 3. The degree of deformation applied to the object 3 largely depends on the size of the irregularities. It becomes possible to perform the measurement.

FIGS. 2 (a) and 2 (b) and FIGS. 3 (a) and 3 (b)
FIG. 2 shows an example of a friction body 2 having a friction surface in which the above-mentioned uneven stripes are arranged in parallel. FIG. 2 shows an example in which the uneven stripes are provided at right angles to the friction direction (the rotation direction of the DUT 3). In FIG. 3, uneven stripes are provided obliquely to the friction direction. In particular, as shown in FIG. 3, when the ridges are provided obliquely to the friction direction, the to-be-measured object 3 can be twisted, and the torsional dynamic frictional resistance can be measured.

Therefore, by appropriately determining the unevenness of the friction body 2, it is possible to effectively measure, for example, the dynamic frictional resistance of the tread rubber at the time of driving with an automobile tire or the like or at the time of cornering.

Various shapes such as a triangular shape, a rectangular shape, a semicircular shape, a sine wave shape, and the like can be adopted as the shape of the uneven stripes.
The uneven pitch is preferably 0.1 mm or more in order to prevent wear of the measured object 3 and the clogging thereof, and two or more, particularly three or more ridges are simultaneously in contact with the measured object 3. It is preferred that The material of the friction body 2 may be selected in accordance with conditions required for the dynamic friction resistance to be measured, and is not particularly limited.

In addition, the DUT 3 is generally a rubber such as a natural rubber or a synthetic rubber. However, the present invention is not limited to this rubber and may be, for example, a synthetic resin or another substance.

The friction body 2 and the object 3 are housed in a thermostat 8 provided on the measuring plate 1. A heater 9 for changing the atmosphere in the thermostat 8 and the temperature of the friction body 2 is provided in the thermostat 8, and the heater 9 is connected to a temperature controller 10 for controlling these temperatures. Have been. Since the dynamic frictional resistance is greatly affected by the temperature of the friction body 2 and the measured object 3, the temperature of the friction body 2 and the measured object 3 is controlled by the constant temperature bath 8, the heater 9, etc. in order to accurately know the influence. It is preferable to be able to adjust.

Further, a liquid spraying device 11 is connected to the thermostat 8. The liquid spraying device 11 supplies liquid continuously or intermittently between the friction body 2 and the object 3 in the thermostat 8. Since the dynamic frictional resistance is greatly affected by the presence of a liquid, in order to accurately know the influence of various liquids, it is necessary to allow the liquid to be sprayed between the friction body 2 and the object 3 to be measured. preferable. Also, the dynamic frictional resistance is affected by the temperature of the intervening liquid,
It is preferable that the liquid spraying device 11 is provided with a temperature control device.

The other end of the drive shaft 7 having the DUT 3 attached to one end thereof penetrates through the load mounting arm 12 in a freely rotatable state,
It is connected to the driving body 6 via a drive transmission pulley 13.

The load mounting arm 12 can be tilted about a support shaft 14 provided in parallel with the drive shaft 7 at a position shifted from the penetrating portion of the drive shaft 7, and load mounting portions 15a, 15
b is provided. The load mounting arm 12 controls the contact time between the friction body 2 and the object 3 by moving up and down, and also adjusts the force for pressing the object 3 against the friction body 2. is there. The dynamic frictional resistance is greatly affected by the pressing force of the object 3 against the friction body 2, so that it is necessary to adjust the force for pressing the object 3 against the friction body 2 in order to accurately know the influence. Is preferred.

The adjustment of the pressing force by the load mounting arm 12 is performed by attaching a weight to one of the load mounting portions 15a and 15b. That is, when a weight is attached to the load attachment portion 15a located in the front in the figure, the pressing force becomes strong, and when the weight is attached to the load attachment portion 15b located in the rear in the figure, the pushing force becomes weak. .

The drive unit 6 rotates the drive shaft 7 via a drive transmission pulley 13, and the drive is controlled by a drive unit transmission 16 and a drive unit control unit 17 that controls switching thereof. In addition, the driving body control unit 17 and the force meter 5
Each of them is connected to the recording analyzer 18 so that the rotational speed of the rubber 3 to be measured by the driving body 6 and the dynamic friction resistance are simultaneously inputted to the recording analyzer 18 so that the speed dependency of the dynamic friction resistance can be known. Has become.

According to the above device, the friction body 2 is attached to the measurement plate 1,
The dynamic frictional resistance can be measured as the rotational moment force of the measuring plate 1 by pressing the object 3 against the frictional body 2 with an appropriate force while being driven and rotated by the driving body 6.

The principle of the measurement will be described with reference to FIG. 4. When the object 3 driven and rotated in the direction shown by the arrow in the figure is pressed against the friction body 2, the measuring plate 1 tries to rotate counterclockwise in the figure. The rotational moment force will be measured by the dynamometer 5. The rotational moment force to be measured is based on the ratio of the distance from the mounting portion of the dynamometer 5 to the measuring plate 1 to the rotating shaft 4 and the distance from the friction body 2 to the rotating shaft 4, based on the principle of leverage. Is amplified and measured.

As described above, amplification of the detection force is performed by the lever principle based on the ratio of the distance between the attachment portion of the dynamometer 5 to the measurement plate 1 and the rotation axis 4 of the friction body 2. Is
As shown in the figure, the friction member 2 and the rotation shaft 4 need not be connected to each other on the opposite side, but may be connected to the same side as the friction member 2.

Further, in the above measurement, if a liquid is sprayed between the friction body 2 and the measured object 3, the dynamic friction resistance can be measured in a state where the liquid is interposed, and the friction body 2 and the measured object 3 can be measured.
By adjusting the temperature, the dynamic frictional resistance at an arbitrary temperature can be measured.

FIG. 5 shows the dynamic frictional resistance of vulcanized rubber compositions for tire treads (100 parts by weight of polymer, 85 parts by weight of carbon, 50 parts by weight of oil) of SBR having different glass transition temperatures measured by the method and the apparatus of the present invention. It shows the results.
FIG. 6 shows the results of ASTM-E-
It shows the result of measurement by the measurement method shown in 303-74.

As is clear from the figure, the results shown in FIG.
The dynamic frictional resistance of the rubber and the glass transition temperature of the rubber are correlated and are consistent with the conventional general recognition.
On the other hand, in the results shown in FIG. 6, the difference in the kinetic frictional resistance of the rubber due to the difference in the glass transition temperature of the rubber is hardly expressed, and the method and the apparatus of the present invention have higher measurement results and higher accuracy. It is clear that it is.

In FIGS. 5 and 6, the values in parentheses are
It shows an index value when the rubber composition having a glass transition temperature of −49 ° C. is set to 100.

FIG. 7 shows that the method and apparatus of the present invention
3 shows the results of measuring the speed dependence of dynamic friction resistance of vulcanized rubber compositions of R, BR, and NR (polymer 100 parts by weight, carbon 50 parts by weight, oil 5 parts by weight).

As is clear from the figure, the speed dependency of the dynamic friction resistance differs depending on the type of rubber. However, information on the speed dependence of such dynamic frictional resistance is
It cannot be obtained by the measurement method of TEM-E303-74.

[Effects of the Invention] The present invention is as described above, and has the following effects.

(1) Since the object 3 is driven to rotate and the outer peripheral surface thereof is brought into contact with the friction body 2 to perform the measurement, the dynamic friction resistance or the dynamic friction resistance corresponding to, for example, driving or cornering of an automobile tire or the like. Information under actual use conditions such as speed dependency, and measurement results of extremely high practical value can be obtained.

(2) The friction surface of the friction body 2 only needs to be uniform in a small range, and it is easy to maintain uniformity. Therefore, it is easy to increase the measurement accuracy, and many friction bodies 2 having different friction surface conditions and materials. Measurement is also easy.

(3) Since the dynamic frictional resistance of the workpiece 3 is detected as the rotational moment force of the measuring plate 1, the detection power can be amplified by increasing the distance from the rotating shaft 4 to the friction body 2, and the electric power can be increased. Amplification accuracy is higher than typical amplification,
High-precision measurement is possible.

(4) By providing the constant temperature bath 8, the heater 9, and the liquid spraying device 11, the dynamic frictional resistance on the dry friction surface and the wet friction surface at each temperature can be easily measured.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of the present invention, and FIGS. 2 and 3 each show an example of a body to be rubbed. FIG. 1 (a) is a plan view, FIG. FIG. 5 is an explanatory view of the measurement principle of the present invention, FIG. 5 is a graph showing the measurement result of the dynamic friction resistance according to the present invention, FIG. 6 is a graph showing the measurement result of the dynamic friction resistance according to ASTM-E303-74, and FIG. 4 is a graph showing a measurement result of the speed dependence of the dynamic friction resistance according to the present invention. 1: Measuring plate, 2: Friction body, 3: Object to be measured, 4: Rotary axis, 5: Dynamometer,
6: drive body, 7: drive shaft, 8: constant temperature bath, 9: heater, 10: temperature control unit, 11: liquid spraying device, 12: load mounting arm, 1
3: drive transmission pulley, 14: support shaft, 15a, 15b: load mounting section, 16: drive body transmission, 17: drive body control section, 18: recording analysis device.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 19/02 G01N 3/56

Claims (2)

(57) [Claims] 1. A frictional body is attached to a rotatable measuring plate, and a dynamic frictional resistance generated by bringing the outer peripheral surface of a circular object to be driven into contact with the frictional body is defined as a rotational moment force of the measuring plate. A method for measuring dynamic frictional resistance, characterized by detecting. 2. A measuring plate capable of rotating about a rotation axis, a friction member attached to the measuring plate, a dynamometer for measuring a rotational moment force of the measuring plate, and an outer peripheral surface rotating in contact with the friction member. A driving device for rotating a circular object to be measured.