JP4260342B2 - Method and apparatus for testing friction characteristics of elastic material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a friction characteristic test method and apparatus capable of measuring the frictional force of various elastic materials, for example, vulcanized rubber, against an abrasive material with high accuracy under each of dry conditions and wet conditions.
[0002]
[Prior art]
For example, as a method for measuring frictional force, which has been widely used in the past in order to obtain the friction characteristics of tread rubber, which has a great influence on the motion performance of pneumatic tires, a method using a portable skid tester, a flat belt, etc. There is a method of measuring using a machine.
[0003]
Here, as shown in FIG. 6, the former method attaches the sample plate 52 with the tread rubber sample 51 attached to the pendulum 53, and the pendulum so that the tread rubber sample 51 properly contacts the road surface material 54. The height of 53 is adjusted by the lock screw 55 and the vertical position adjusting screw 56, and then the pendulum 53 is fixed to the support arm 57 at a predetermined swing height (90 °), and the zero position of the pointer 58 is adjusted. Adjustment, cleaning of the road surface material 54, and setting of wet or dry conditions are performed, then the pendulum 53 is released from the support arm 57, and the tread rubber sample 51 is brought into frictional contact with the road surface material 54. The stopped position is measured by reading the scale plate scale indicated by the pointer 58.
The latter method measures driving frictional force, braking frictional force, and the like by rotating a product tire while pressing it with a required force on a flat traveling belt laid with a road surface material as an abrasive material. is there.
[0004]
[Problems to be solved by the invention]
By the way, in the former method using a portable skid tester, in addition to being able to test with a tread rubber sample, there are advantages that various road surface materials can be tested under dry and wet conditions. Rubs the end face of a sample that has a substantially rectangular parallelepiped shape, and since the contact area greatly depends on the rubber hardness, the measurement result of the friction force includes the influence of the hardness of the tread rubber. In addition to the problem that the friction force of rubber is overestimated, the pressing force of the tread rubber sample against the road surface material cannot be changed, so there is also the problem that the friction force cannot be measured under the required appropriate load conditions. It was.
[0005]
For this reason, even if measurements such as friction force are performed using a skid tester, the full width of the results cannot be relied on. Therefore, for many tread rubbers, actual vehicle running with prototype tires is also performed. In addition, it is inevitable to separately evaluate the driving and braking performance of the tread rubber, and in addition, since this actual vehicle traveling evaluation is performed based on the sensitivity of the driver, it may be quantitative objective data. There was an inconvenience that it was not possible.
[0006]
In contrast, in the latter method using a flat belt machine, objective data can be collected under dry conditions, but it is necessary to prototype tires for all the developed tread rubber types. Therefore, with this method, there has been a problem that rapid and efficient development of tread rubber is virtually impossible.
[0007]
The object of the present invention is to solve such problems of the prior art, and the object of the present invention is to carry out a test using an elastic material sample under the action of a required load. For example, it is possible to accurately measure the intrinsic frictional force as objective data that has a high correlation with that of product tires. An object of the present invention is to provide a method and apparatus for testing the friction characteristics of an elastic material that can realize various research and development.
[0008]
[Means for Solving the Problems]
The friction characteristic test method of the elastic material according to the present invention is a tapered elastic cone-shaped cylindrical elasticity held on a sample shaft that is rotationally driven in a horizontal plane, for example, an annular abrasive material and arranged at an inclination. The circumferential surface of the material sample is pressed with a required force and rotated under a posture in which the slip ratio over the entire width is constant by absorbing the circumferential length difference according to the radial position of the abrasive material, and is driven to rotate. Frictional force when the material speed and the peripheral speed of the elastic material sample are changed relatively, for example, when any one of them is changed in the range of 0 to 100% of the slip ratio with respect to the other. This is also measured, for example, as torque generated in the sample shaft.
[0009]
The torque measured in this way can be recorded and displayed as a friction force curve, a friction coefficient curve, etc. using the slip ratio as a parameter by inputting it to the CPU, for example, and the lock braking force The coefficient and the maximum braking force coefficient can be displayed.
[0010]
In such a test method, by measuring a braking frictional force, a driving frictional force, etc. while pressing a thin cylindrical elastic material sample on a rotationally driven abrasive material under a required slip ratio, Circumferential shear deformation within the thickness of the sample can be effectively prevented, and the influence of the shear deformation on the friction force, the influence of the hardness of the sample, the contact area, etc. on the friction force can be sufficiently removed.
[0011]
Also, here, when pressing the elastic material sample against the abrasive material with a required force, the pressing force of the sample can be specified sufficiently accurately by taking into account the weight of the sample shaft etc. that holds the sample, On the other hand, by offsetting the weight with a balance weight or the like, the sample can be pressed with a force smaller than the weight of the sample shaft or the like.
[0012]
In addition, here, the circumferential surface of the elastic material sample according to the radial position of the abrasive material that is rotationally driven by pressing the circumferential surface of the elastic material sample against the abrasive material in a posture in which the slip ratio over the entire width is constant. By absorbing the length difference, the distribution of the slip ratio in the contact surface can be eliminated and uniformized, so that the relative relationship between the slip ratio and the frictional force can be measured more accurately.
Further, since the peripheral speed of the annular abrasive material and elastic material sample to be rotated is about 20 km / h, and measurement is possible at a high speed close to the use conditions of the tire, a very high correlation result with the tire measurement result is obtained.
[0013]
Therefore, according to this method, the elastic material sample is pressed against the polishing material with sufficient pressing force regardless of the size thereof, and the circumferential shear deformation, hardness, The influence of the contact area etc. on the frictional force is made small enough to be ignored, and the slip ratio of the sample in the ground contact surface is made uniform enough to make the slip ratio constant as expected over the entire width. By doing so, the frictional force corresponding to the slip ratio can be objectively measured with extremely high accuracy.
[0014]
Thus, under this method, the friction characteristics of tread rubber and other elastic materials can be accurately obtained as objective data without the need to prototype product tires, etc., so that the speed and efficiency of elastic materials can be determined. Research and development can be realized.
[0015]
By the way, in this method, when the frictional force is measured while sprinkling the abrasive material, the frictional force of the elastic material under the dry condition as well as the frictional force under the wet condition can be obtained with high accuracy.
[0016]
Here, preferably, the environmental temperature for measuring the frictional force is appropriately selected, and for example, it is possible to measure the frictional force of the elastic material that can be a tread rubber under dry and wet conditions throughout the seasons. In addition, preferably, the temperature of the water to be sprinkled is appropriately selected to enhance the seasonal suitability of the water temperature.
Incidentally, it has been confirmed that the frictional force of the elastic material is more greatly affected by the water temperature than the water spray amount.
[0017]
An apparatus for testing friction characteristics of an elastic material according to the present invention is a tapered scissor in which an abrasive material that is rotationally driven in a horizontal plane is horizontally arranged, and a peripheral surface is pressed against the abrasive material at one end via a sample holder. A cylindrical elastic material sample in the shape of a conical cone is held, a sample shaft connected to a motor at the other end is inclined, a torque meter is disposed in the middle of the sample shaft, and the sample shaft is A cylinder or other reciprocating drive means for moving up and down relative to the polishing material is provided, and an elastic material sample that is displaced by the reciprocating drive means and held on the sample shaft, for example, a sample having a hollow frustoconical shape, is polished. A reduction cylinder that presses the material with a required force is provided, and a load sensor that can be a load cell or the like is disposed between the reduction cylinder and the sample shaft.
[0018]
In this apparatus, an elastic material sample attached to one end of an inclined sample shaft through a holder is raised to a required height with respect to the abrasive material to be rotated by a reciprocating drive means that can be a cylinder, a screw means or the like. While being displaced, the peripheral surface is precisely pressed against the surface of the polishing material with the required force under the action of a reduction cylinder that is moved down and displaced together with the tilted sample axis. At the same time, a motor connected to the other end of the sample shaft is rotationally driven at a required peripheral speed.
[0019]
In this case, here, the outer contour shape of the elastic material sample is a tapered frustoconical shape corresponding to the diameter size of the abrasive material, which can be substantially an annular shape as a whole, and the inclination of the sample axis is set to be the same. By selecting according to the shape of the head cone, the circumferential length difference between the inside and outside in the radial direction of the abrasive material is absorbed, and the entire contact width of the elastic material sample to the abrasive material is substantially reduced with respect to the abrasive material. A constant slip rate is assumed.
[0020]
Also, here, the pressing force of the elastic material sample to the polishing material surface is obtained by detecting with a load sensor interposed between the reduction cylinder and the sample shaft, and preferably the influence of the sample shaft weight and the sample weight. The sample pressing force is also taken into consideration.
Here, when the balance weight is connected to the middle part of the sample shaft, for example, the center of gravity, and the sample shaft weight including the motor, sample holder and torque meter is offset, the detection result of the load sensor The pressing force can be accurately obtained only by taking the sample weight into consideration, and at the same time, the sample pressing force can be a force smaller than the pressing force corresponding to the sample shaft weight.
[0021]
By the way, the frictional force of the sample under the state where the peripheral surface of the elastic material sample is pressed against the surface of the abrasive material with a required force in this way is, for example, the same for both the abrasive material surface and the sample peripheral surface. From the state of rotating at a predetermined speed, the speed of either the sample or the abrasive material is reduced to generate a constant slip between them, and the torque generated on the sample axis at this time is provided on the sample axis It can be measured by measuring with a torque meter, and this is performed gradually or stepwise in the range of 0 to 100% of the slip rate, so that the braking friction force or drive friction according to the slip rate is achieved. You can ask for power.
[0022]
Thus, according to this apparatus, the elastic material sample can be accurately pressed with the force as intended to the abrasive material by the reduction cylinder, and the elastic material sample is held by the inclined sample axis. Combined with the shape of the sample itself, the sample peripheral surface can be pressed against the surface of the abrasive material without the influence of its radial peripheral length difference, and even with a torque meter, it occurs on the sample axis The torque according to the slip ratio can be measured with high accuracy.
Therefore, by making the elastic material sample thin, as described above, the frictional force of the sample can be measured with high accuracy.
[0023]
In such an apparatus, more preferably, the center of action of the pressing force on the elastic material sample is the central portion of the contact width of the sample with the abrasive material, thereby causing the pressing force to act unevenly. Eliminate the risk of reduced measurement accuracy.
[0024]
Here, when the abrasive material is a road surface material, especially when the elastic material is a tread rubber, the frictional force against various road surface materials such as concrete, asphalt, resin, safety walk, etc. Can be measured below.
[0025]
In this apparatus, when a nozzle for spraying water onto the polishing material is provided, measurement under wet conditions can be performed in addition to frictional force under dry conditions.
[0026]
Further, here, when each of the polishing material and the sample shaft is housed in a temperature-controlled room and provided with a cooling means for cooling the temperature-controlled room, more preferably, when a heating means in the temperature-controlled room is also provided, In addition to setting the temperature in the temperature-controlled room according to the four seasons in Japan, it is possible to measure the frictional force under the required temperature conditions from extreme cold to extreme heat.
[0027]
This is the same when the nozzle is connected to the constant temperature water tank and a cooling means for cooling the inside of the constant temperature water tank is provided, more preferably, also when a heating means is provided in the constant temperature water tank, The wet friction force under the required water temperature condition can be measured as long as the water does not freeze.
[0028]
By the way, when measuring the frictional force under the relative slip between the elastic material sample and the abrasive material, the surface recesses of the abrasive material are gradually embedded by the scraped sample powder, etc., and the measured value varies accordingly. Therefore, it is preferable to provide means for cleaning the surface of the abrasive material so that the surface can be cleaned as required.
Here, this cleaning means can be a rotating brush pressed against the abrasive material.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
FIG. 1 is a partial sectional schematic front view showing the main part of the apparatus according to the present invention, and FIG. 2 is a partial sectional schematic line side view showing the entire apparatus.
[0030]
Here, a road surface material 1 as an example of an abrasive material, which has a substantially annular shape as a whole, is disposed horizontally, and this road surface material 1 is rotationally driven by a motor 2 at a required speed via a speed reducer 3. Make it possible.
[0031]
In addition, here, the sample shaft 4 is disposed in an inclined posture above the road surface material 1, and the outer contour shape of the sample shaft 4 at one end of the sample shaft 4 on the road surface material side is substantially reduced via the sample holder 5. A thin cylinder-shaped elastic material sample having a conical head shape, here a thin-tube-shaped tread rubber sample 6 is detachably held, and at the other end, a motor 7 that rotationally drives the tread rubber sample 6 at a required peripheral speed. And a torque meter 8 for measuring the torque around the axis generated in the sample shaft 4 is disposed in the middle portion thereof.
[0032]
Here, each of the sample shaft 4 and the motor 7 is attached to the lifting plate 9 on the back side thereof, and the lifting plate 9 is lifted and lowered with respect to the fixed plate 10 on the further back side of the lifting plate 9. In the figure, it is guided by a pair of left and right linear guides 11 and is moved up and down by the action of a moving cylinder 12 as an example of a reciprocating drive means attached to the fixed plate 10.
[0033]
Here, the balance weight 14 is preferably connected to the center of gravity of the sample shaft 4 including the sample holder 5, the motor 7 and the torque meter 8, for example, more preferably to the center of gravity including the elevating plate 9 via the fixed pulley 13. To substantially offset their weight. For example, as shown in FIG. 3 from the rear side of the lifting plate, the hook 14a attached to the lifting plate 9 is engaged with one end of the wire 14b wound around the fixed pulley 13 and the other end of the wire 14b. This can be done by attaching a balance weight 14 to the part.
According to this, the sample shaft 4 or the like can be freely moved up and down with a very small external force acting thereon.
[0034]
Furthermore, in this apparatus, as is apparent from the right side view taken along the line IV-IV in FIG. 4, the sample shaft 4 or the like is attached to the rod 12 a of the test unit moving cylinder 12 attached to the fixed plate 10. At the same time, a reduction cylinder 15 that is moved up and down is attached via an intermediate plate 12b, and this reduction cylinder 15 is connected to the sample shaft 4 via a rotary bearing 16. Preferably, the arrangement position of the reduction cylinder 15 is determined. The center of the pressing force acting on the tread rubber sample 6 is selected to be the central portion of the contact width to the road surface material 1 as shown in FIG. In addition, a load sensor, for example, a load cell 17 for measuring the sample pressing force by the reduction cylinder 15 is disposed between the reduction cylinder 15 and the sample shaft 4, and preferably the center axis of the load cell 17 is The center portion of the above-described road surface material contact width of the sample 6 and the rod axis of the reduction cylinder 15 are aligned and positioned.
[0035]
In the apparatus configured as described above, the sample shaft 4 holding the tread rubber sample 6 is moved under the action of the test portion moving cylinder 12, and the sample 6 is separated from the road surface material 1 and the sample 6. Can be moved up and down in parallel with a close position sufficiently approaching the road surface material 1, and the circumferential surface of the tread rubber sample 6 is pressed against the road surface material 1 with a required force by the action of the reduction cylinder 15. The pressing force can be increased or decreased as required.
[0036]
Here, the frictional force of the tread rubber sample 6 is measured from the state in which each of the road material 1 and the sample 6 is rotated at the same speed by the respective motors 2 and 7, for example, the respective servo motors. The slip speed between the sample 6 and the road surface material 1 is changed from 0% to 100% by gradually or gradually decreasing the peripheral speed, and the shaft axis generated in the sample shaft 4 under each slip ratio is changed. The torque for increasing the rotation can be obtained by measuring with the torque meter 8, and the frictional force in this case is the braking frictional force.
[0037]
On the other hand, when the slip is generated by reducing the speed of the road surface material 1, and when the slip is generated by increasing the peripheral speed of the sample 6, the torque generated in the direction that prevents the rotation of the sample shaft 4 is measured. By doing so, the driving frictional force can be measured.
[0038]
By the way, in such an apparatus, as shown in FIG. 2, when a nozzle 18 for spraying water is provided on the road surface material 1 and the road surface material 1 is brought into a wet state by the water spray, The frictional force can be measured, and each of the road surface material 1 and the sample shaft 4 is accommodated in the temperature-controlled room 19 and a cooling means for cooling the temperature-controlled room 19 such as a dual refrigerator 20 is provided. In some cases, the friction force measurement conditions can be adapted to the four season temperatures.
[0039]
In addition, when the nozzle 18 is connected to the constant temperature water tank 21 and the water in the constant temperature water tank 21 is cooled by the above-described binary refrigerator 20, the wet conditions can also be adapted to the four seasons. .
[0040]
FIG. 5 is a partial cross-sectional view illustrating a cleaning device preferably attached to the device as described above. This is, for example, in the diameter direction of the road surface material 1 with respect to the arrangement position of the sample shaft 4. It is provided at a position to oppose.
[0041]
This is because the movable plate 31 to which the drive motor 30 is attached is disposed so as to be movable up and down under the action of the screw shaft 32 and the lift guide 33 penetrating the movable plate 31, and the drive motor 30 and the movable plate 31 with respect to the road surface material 1. The relative height can be adjusted by the rotation of the screw shaft 32 by operating the handle 34, while the unexpected rotation of the screw shaft 32 can be restrained by a built-in lock bolt based on the rotation of the screw shaft lock handle 35. However, a boss portion of a brush holder 38 equipped with a brush 37 as a cleaning means, which is pressed against the road surface material 1, is attached to a tip portion of the output shaft 36 of the drive motor 30 with a screw (not shown).
[0042]
In this cleaning device, by operating the handle 34, the drive motor 30 is displaced downward to bring the brushes 37 into full contact with the road surface material 1, and while maintaining the contact state by the screw shaft lock handle 35, the drive motor By rotating 30, the rubber material adhering to the rotating road surface material 1 can be sufficiently scraped over its entire width.
[0043]
【The invention's effect】
Thus, according to the present invention, the peripheral surface of the thin cylindrical elastic sample is pressed against the rotationally driven abrasive material as expected without causing a so-called side slip. By measuring the torque generated on the sample axis while pressing with pressure, the frictional force corresponding to the slip ratio can be measured with high accuracy with objective values, not only under dry conditions but also under wet conditions. Therefore, it is possible to evaluate the friction characteristics of each elastic material with high reliability without producing trial tires or the like for each elastic material. Therefore, the elastic material can be evaluated quickly and efficiently. R & D etc. can be made possible.
[Brief description of the drawings]
FIG. 1 is a partial sectional schematic front view showing a main part of an apparatus according to the present invention.
FIG. 2 is a partial cross-sectional schematic line side view showing the entire apparatus according to the present invention.
FIG. 3 is a view showing a lift plate together with a fixed pulley from the back side.
4 is a right side view taken along line IV-IV in FIG. 1. FIG.
FIG. 5 is a partial cross-sectional view illustrating a cleaning device.
FIG. 6 is a view showing a portable skid tester.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Road surface material 2,7 Motor 3 Reduction gear 4 Sample axis 5 Sample holder 6 Tread rubber sample 8 Torque meter 9 Lifting plate 10 Fixed plate 11 Direct acting guide 12 Test part moving cylinder 12a Rod 12b Intermediate plate 13 Fixed pulley 14 Balance weight 14a Wire 14b Wire 15 Rolling cylinder 16 Rotating bearing 17 Load cell 18 Nozzle 19 Constant temperature chamber 20 Dual refrigerator 21 Constant temperature water tank 30 Drive motor 31 Movable plate 32 Screw shaft 33 Lift guide 34 Handle 35 Screw shaft lock handle 36 Output shaft 37 Brush 38 Brush holder

Claims (16)

The slip ratio over the entire width of the circumferential surface of the tapered truncated cone-shaped cylindrical elastic material held on the sample shaft tilted on the polishing material that is rotationally driven in the horizontal plane is the radius of the polishing material. Under a constant posture that absorbs the difference in circumferential length according to the direction position, it is pressed with a required force and rotated to change the speed of the abrasive material and the circumferential speed of the elastic material sample relatively. A method for testing the friction characteristics of an elastic material, in which the friction force is measured by the generated torque.   The method for testing friction characteristics of an elastic material according to claim 1, wherein the outer contour shape of the elastic material sample is a tapered frustoconical shape corresponding to the diameter of the abrasive material.   The method for testing the friction characteristics of an elastic material according to claim 2, wherein the inclination of the sample axis is selected according to the frustoconical shape of the elastic material sample.   The method for testing the friction characteristics of an elastic material according to any one of claims 1 to 3, wherein the abrasive material has an annular shape. The method for testing friction characteristics of an elastic material according to any one of claims 1 to 4, wherein the frictional force is measured while watering the abrasive material. The method for testing a friction characteristic of an elastic material according to any one of claims 1 to 5 , wherein an environmental temperature for measuring the friction force is appropriately selected. The method for testing the friction characteristics of an elastic material according to claim 5 or 6 , wherein the temperature of water to be sprinkled is appropriately selected. A polishing material that is rotationally driven in a horizontal plane is disposed horizontally, and a tapered elastic cone-shaped cylindrical elastic material sample whose peripheral surface is pressed against the polishing material via a sample holder is held at one end. A sample shaft connected to a motor is inclined at the other end, a torque meter is disposed in the middle of the sample shaft, and a reciprocating drive means for moving the sample shaft up and down is provided. A friction cylinder is provided with a reduction cylinder that presses the elastic material sample held on the sample shaft against the polishing material with a required force, and a load sensor is disposed between the reduction cylinder and the sample axis. apparatus. The apparatus for testing a friction characteristic of an elastic material according to claim 8 , wherein a balance weight is connected to an intermediate portion of the sample shaft. 10. The apparatus for testing friction characteristics of an elastic material according to claim 8 or 9 , wherein the center of action of the pressing force on the elastic material sample is a central portion of the contact width of the elastic material sample with the abrasive material. The apparatus for testing friction characteristics of an elastic material according to any one of claims 8 to 10 , wherein the polishing material is used as a road surface material. The apparatus for testing a friction characteristic of an elastic material according to any one of claims 8 to 11 , further comprising a nozzle for spraying water onto the abrasive material. The apparatus for testing a friction characteristic of an elastic material according to any one of claims 8 to 12 , wherein the polishing material and the sample shaft are housed in a temperature-controlled room, and cooling means for cooling the inside of the temperature-controlled room is provided. The elastic material friction characteristic testing apparatus according to claim 12 or 13 , wherein the nozzle is connected to a constant temperature water tank and a cooling means for cooling the inside of the constant temperature water tank is provided. The elastic material friction characteristic testing device according to any one of claims 8 to 14 , further comprising a polishing material cleaning means. The elastic material friction characteristic testing device according to claim 15 , wherein the cleaning means is constituted by a rotating brush pressed against the abrasive material.

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