JP5478464B2 - Abrasion test equipment - Google Patents

Description

  In the present invention, a sample specimen made of an elastic material such as a rubber material constituting a tire is pressed onto a flat surface of an abrasive body that is relatively displaced with respect to the specimen, and the amount of wear of the sample specimen is measured. The present invention relates to a wear test apparatus that measures with high correlation with a tire. Specifically, in the wear test, in the load rolling of an actual tire, the circumferential direction in the contact surface, the widthwise shear stress state, and the ground contact The present invention proposes a technology capable of accurately reproducing the pressure state and predicting tire wear with high accuracy.

Conventionally, as this type of wear test apparatus, there are those described in Patent Documents 1 and 2.
Patent Document 1 states that “a wear test in which a belt-like abrasive body is mounted between a pair of rollers each having a drive source connected to at least one, and a sample support mechanism is installed to press the sample against the flat surface of the abrasive body. According to this wear test device, “wear can be accurately simulated when a rubber sample constituting a tire tread is used as a sample”.

  Patent Document 2 states that “a rubber tester that tests a rubber test piece by pressing a rubber test piece against a grindstone or a pseudo road surface, and displaces the rubber test piece with respect to the grindstone or the pseudo road surface. The rubber test piece is characterized by providing adhesion and / or slip to the grindstone or simulated road surface. According to this apparatus, “actual products such as tires are worn out”. It was possible to realize a rubber testing machine that can accurately reproduce the behavior of rubber at the time, and accurately match the measured rubber wear level to the actual wear result. . "

JP-A-6-34506 JP 2009-198276 A

  However, in any of the apparatuses described in Patent Documents 1 and 2, for example, a “rubber test piece” or the like is moved only in the vertical direction with respect to the “abrasive body” or “whetstone or simulated road surface” that moves in the horizontal direction. Since it is displaced and pressed, the wear of the tread contact surface in a tire that actually loads and rolls on the road surface cannot be predicted with sufficiently high accuracy.

  An object of the present invention is to solve such problems of the prior art, and the object of the present invention is to provide circumferential and widthwise shear stresses on the ground contact surface during load rolling of a tire. It is another object of the present invention to provide a wear test apparatus that can faithfully reproduce the state of occurrence of contact pressure and thereby predict tire wear with high accuracy.

  The inventor paid attention to the action of force and slip on the microelements in the tread contact surface at the time of rolling load of the tire, and the microelements include the contact pressure of the rubber material on the road surface and shear due to the slip. Under the premise that force acts, the shearing force acting on the minute elements in the contact surface between the stepping on the land portion of the tire and the kicking out is shown as a graph in FIG. 1 over time. I found that it changed.

That is, as shown in the schematic diagram of FIG. 2, for example, the tread block of the tire 100 that freely rolls in the direction indicated by the arrow is mainly based on adhesion with the road surface 110 when the tread block 101a is reached. After receiving a large shear stress, the shear stress decreases to a position 101b immediately below the load, increases in the opposite direction toward the kicking position 101c, and reaches the kicking position 101c. The block slips from the road surface 110, and a large shear stress acts instantaneously. On the other hand, the circumferential shear stress rapidly decreases due to the release from the contact surface of the tread block.
Here, particularly in a pneumatic tire, the tread contact surface is pushed and deformed by the action of the contact pressure, so that the tread block is substantially relative to the road surface between the stepping-in position 101a and the kicking-out position 101c. Contact with each other in parallel.

  Therefore, in the wear test using the sample specimen of the tread rubber material, the degree of wear of the tread ground contact surface of the tire rolling on the road surface by faithfully reproducing the shear stress state shown in FIG. We thought that it was possible to predict with high accuracy with high correlation with actual tires.

  Based on such knowledge, the wear test apparatus of the present invention comprises an endless annular polishing body and a pair of polishing body rollers around which the polishing body is wound, and at least one of which is rotationally driven. A sample specimen made of a material is pressed against the outer peripheral surface of the abrasive body to measure the amount of wear of the sample specimen, and the sample specimen formed in an endless ring is directly or indirectly wound. A pair of specimen rollers that are hung and at least one of which is rotationally driven are provided in such a manner that the flat surface portions on the outer peripheral sides of the wound sample specimen and the abrasive body face each other. The specimen roller is provided with pressing means for separating and approaching the polishing body.

  Here, at a plurality of locations in the circumferential direction of the polishing body, there are provided three-component force sensors for measuring the three-direction component forces in the circumferential direction and the width direction of the polishing body and in the direction perpendicular to the outer peripheral surface of the polishing body. It is preferable to attach.

  Preferably, a roller displacing means is provided for bringing the pair of specimen rollers apart and approaching each other.

  According to the wear test apparatus of the present invention, the pressing means winds around the pair of specimen rollers around the outer peripheral surface of an endless abrasive body that is wound around the pair of abrasive body rollers and driven to travel in the circumferential direction. The endless annular sample specimen can be pressed in a running state in the circumferential direction based on the rotational drive of the specimen roller, for example, while giving a constant relative rotational speed to the abrasive body. Since the contact between the sample specimen and the polishing body is made between the flat surface portions on the respective outer peripheral sides, as described above, the time required to occur on the ground contact surface of the tire that actually rolls on the road surface is reduced. The circumferential shear stress due to adhesion and slippage with the road surface, which changes with the passage of time, is measured by the pressure of the sample specimen against the abrasive body and the relative velocity of the sample specimen relative to the abrasive body. Can be reproduced faithfully by controlling respectively, as a result, it is possible to predict the wear of the tire with high precision.

  In addition, according to this wear test apparatus, since the polishing body is an endless ring that is driven to travel, the abrasion powder generated when the sample specimen is worn on the outer peripheral surface of the polishing body is Since it is carried forward in the running direction of the polishing body and removed from the polishing body by the brush, the influence of the wear powder on the wear state of the sample specimen can be surely removed.

  Here, when three component force sensors are attached to a plurality of locations in the circumferential direction of the polishing body, the stress in each direction that the sample specimen receives from the polishing body can be measured in real time, and such measured values are obtained. By using feedback control of the pressing force of the sample specimen to the abrasive body and the relative speed of the sample specimen to the abrasive body, circumferential shear on the ground contact surface during tire rolling A more faithful reproduction of the state of stress generation and a change to the test conditions as required is possible.

  Here, when the roller displacement means for providing the mutual separation and proximity displacement of the pair of specimen rollers is provided, various tires having different sizes and types can be adjusted by adjusting the mutual separation distance of the specimen rollers. Accordingly, the degree of wear of the tread contact surface can be accurately predicted.

It is a graph which shows a time-dependent change of the circumferential direction shear stress which generate | occur | produces in a tread land part from a stepping position to a kicking position of the contact surface of the tire which carries out load rolling of the road surface. It is a side view which shows typically the deformation | transformation aspect of the tread block which contacts a road surface. It is an approximate line side view showing one embodiment of an abrasion test device of this invention. It is a schematic sectional drawing which expands and shows the principal part of the apparatus of FIG. It is a figure similar to FIG. 3 which shows the use condition of the apparatus of FIG. It is a graph which shows the shear stress at the time of changing pressing force etc. in the middle of a test. It is a flowchart which shows an example of the control method in the abrasion test performed using the apparatus of FIG. It is a flowchart which shows the other example of the control method in the abrasion test performed using the apparatus of FIG.

Embodiments of the present invention will be described below with reference to the drawings.
An abrasion test apparatus 1 illustrated in FIG. 3 includes an endless annular polishing body 2 and a pair of polishing bodies wound around the polishing body 2 and rotated at least one of them by, for example, connecting to a motor (not shown). An endless annular sample specimen 20 such as a rubber material that forms a tread portion of a tire is directly wound around the body roller 3 and the polishing body 2 at a predetermined interval in the upper part in the figure. While maintaining a posture in which the flat surface portions on the outer peripheral side of the pair of specimen rollers 4 and the sample specimen 20 wound around the pair of specimen rollers 4 and the abrasive body 2 face each other, A pair of specimen rollers 4, together with the sample specimen 20, includes pressing means 5 that separates and approaches the abrasive body 2.
Similarly to the polishing body roller 3, a motor or the like (not shown) is connected to at least one of the specimen rollers 4 in order to apply a rotational driving force.

Here, the abrasive body 2 can be formed, for example, by adhering an abrasive cloth 2b or abrasive paper or other abrasive member over the entire outer peripheral surface of the endless annular rubber member 2a, or the rubber member 2a. It can also be formed by uniformly applying an abrasive such as crushed stone on the outer surface. The polishing member can be made of, for example, stainless steel, and can be formed of various materials as long as it can be attached to the outer peripheral surface of the rubber member 2a.
In addition, "abrasive cloth" etc. here shall be shown by JISK6264.

Here, when performing a wear test to be described later, in order to feedback control the pressing force of the sample specimen 20 to the polishing body 2, etc., the circumferential direction of the polishing body 2 and the circumferential direction of the polishing body 2 It is preferable to provide a three-component force sensor (not shown) that measures component forces in three directions in the width direction and in a direction orthogonal to the outer peripheral surface of the polishing body 2.
Such a three-component force sensor can be disposed, for example, on the inner peripheral surface of the polishing body 2 or the polishing cloth 2b, or embedded in the polishing body 2, and these sensors are, for example, Further, it is connected to a measuring instrument (not shown) in a wired or wireless manner using a slip ring or the like.

  Further, here, for the purpose of applying a required tension to the polishing body 2 after the polishing body 2 is wound around the polishing body roller 3, the distance between the pair of polishing body rollers 3 is between them. A piston, a rack and pinion, a ball screw or the like (not shown) can be provided.

  Also, it is preferable to provide a roller displacing means for adjusting the distance between the rollers, such as a piston, between the pair of specimen rollers 4. In this case, the specimen rollers 4 are wound around the specimen roller 4 during a wear test described later. In addition to being able to apply the required tension to the hung sample specimen 20, the distance between the pair of specimen rollers 4 is appropriately changed according to the size and type of the tire to be reproduced, and the sample specimen 20 By adjusting the contact length between the abrasive body 2 and the abrasive body 2, it is possible to predict the wear of the tread contact surface with a high correlation with the assumed tire.

In addition, although illustration is omitted, when the sample specimen 20 is pressed against the polishing body 2, the inner peripheral surface of the polishing body 2 is interposed between the pair of polishing body rollers 2 in order to suppress bending deformation of the polishing body 2. One or a plurality of supporting rollers can be provided.
Such a support roller can be provided between the pair of specimen rollers 4.

In the illustrated apparatus 1, the endless sample specimen 20 is directly wound between the pair of specimen rollers 4, but the endless annular sample specimen is, for example, a metal belt, an adhesive, a double-sided tape, or the like. It is also possible to indirectly wind between the specimen rollers via the.
Thus, preferably, a metal belt harder than the rubber material constituting the sample specimen is interposed between the sample specimen and the specimen roller 4 to reinforce the inner peripheral side of the tread rubber. The actual load rolling behavior of a tire in which layers and the like are embedded can be reproduced even more faithfully.

By the way, as the pressing means 5 for separating and approaching the pair of specimen rollers 4 together with the sample specimen 20 wound around the abrasive body 2, for example, a cam mechanism illustrated in an enlarged sectional view in FIG. Can be used.
That is, the illustrated pressing means 5 is attached to a frame 6 that supports a pair of specimen rollers 4, and has one end portion (upper end portion in the figure) sealed with a top wall 7a, and the cylindrical body. A shaft member 8 that is slidably displaced with respect to the inner peripheral surface of the cylindrical body 7 on the inner side of the cylindrical body 7, and an inner surface of the top wall 7 a of the cylindrical body 7 is attached The coil spring 9 elastically supports the member 8 and a cam 10 which is provided in contact with the outer surface of the top wall 7a of the cylinder 7 and is driven to rotate.

According to the pressing means 5, the cylinder 7 that is spring-biased with respect to the shaft member 8 based on the rotation of the cam 10 that is rotationally driven around the eccentric shaft is accompanied by the vertical displacement indicated by the arrow in the drawing. Thus, the frame 6 attached to the cylinder 7 and the pair of specimen rollers 4 supported by the frame 6 are separated and approached to the polishing body 2 together with the sample specimen 20.
It should be noted that, although not shown in the figure, a ball screw or a rack and pinion can be used as the pressing means 5 instead of the cam mechanism of the pressing means 5, and in this case, a larger separation and approaching displacement are sufficient. Can be done under high accuracy.

  And by installing this abrasion test apparatus 1 in a thermostat (not shown), it is possible to reproduce the temperature of the actual tire in use, and a heater (not shown) is also attached to the polishing body 2. Thus, the actual temperature condition of the road surface can be reproduced.

In conducting the test using the wear test apparatus 1 described above, first, as shown in FIG. 3, a sample specimen 20 formed in an endless annular shape is wound between a pair of specimen rollers 4. At the same time, the sample specimen 20 and the abrasive body 2 are moved in the circumferential direction, for example, with arrows in the figure, based on the application of rotational driving force by a motor or the like to each of the specimen roller 4 and the abrasive body roller 3. Run as shown.
Here, in this test, in order to measure the wear of the sample specimen 20 with a high correlation with the tire at the time of actual load rolling, for example, the traveling speed V1 of the sample specimen 20 is set to the counterclockwise of the polishing body 2. By making the relative difference with respect to the traveling speed V2, the slippage between the sample specimen 20 and the polishing body 2 is caused between them in the mutual contact posture described later.
The wear test apparatus 1 is used to perform the wear test while the relative speed of the sample specimen 20 with respect to the abrasive body 2 is 0, that is, the sample specimen 20 and the abrasive body 2 are run at a constant speed. It is also possible.

  Thereafter, the pair of specimen rollers 4 together with the sample specimen 20 are lowered as shown by the white arrows in the figure to approach the abrasive body 2 and, as shown in FIG. The flat surface portion is brought into contact with the flat surface portion on the outer peripheral side of the polishing body 2 over a predetermined length, and is pressed with a required force under the action of the pressing means 5.

  At this time, in the contact portion of the sample specimen 20 on the side of one specimen roller 4a located on the right side in the drawing with the abrasive body 2, the actual shear stress state in the circumferential direction in the stepping area of the tire ground contact surface Further, in the flat surface contact portion between the pair of specimen rollers 4a and 4b, the state of the shear stress in the region immediately below the load that is pushed and deformed by the action of the contact pressure on the tire contact surface is shown in FIG. Then, at the contact portion on the other specimen roller 4b side located on the left side, the shear stress in the kick-out area can be reproduced with high correlation.

  Here, in the middle of the test, for example, when 5 minutes have elapsed from the start of the test, by changing the pressing force of the sample specimen 20 to the polishing body 2 or the traveling speed V1 of the sample specimen 20, It is also possible to reproduce the shear stress as shown by the broken line in FIG.

  When a plurality of three component force sensors are provided in the circumferential direction of the polishing body 2, the pressing force of the sample specimen 20 on the polishing body 2 from these sensors, and the circumferential direction of the polishing body 2 and Based on the respective measured values of the shearing force in the width direction, in the drawing, to the contact portion of the sample specimen 20 with the polishing body 2 from the right specimen roller 4a side to the left specimen roller 4b side. The pressing force of the sample specimen 20 to the polishing body 2 is such that the circumferential shear stress of FIG. 1 has a waveform corresponding to the circumferential shear stress that the actual tire contact surface receives from the road surface as shown in FIG. By controlling the traveling speeds of the sample specimen 20 and the abrasive body 2, the wear of the tire can be predicted with higher accuracy.

An example of such a control method is shown in the flowchart of FIG.
In the control method shown in FIG. 7, first, whether or not the measured value of the pressing force of the sample specimen 20 falls within a preset range, and if the measured value of the pressing force is out of this range, The pressing force by the pressing means 5 is adjusted.
On the other hand, if the measured value of the pressing force is within the set range, then, it is examined whether or not the measured value of the shearing force in the circumferential direction of the polishing body 2 falls within the preset range. When the measured value of the shear force in the direction is out of this range, the relative value of the traveling speed V1 of the sample specimen 20 with respect to the traveling speed V2 of the polishing body 2 is adjusted.

  As a result, the pressing force of the sample specimen 20 on the polishing body 2 and the shearing force in the circumferential direction of the polishing body 2 can be controlled as expected. In the actual rolling load of the tire, the circumferential shear stress state in the contact surface can be faithfully reproduced.

  By the way, in the abrasion test apparatus 1 shown in FIG. 3, an angle applying means that enables the pair of specimen rollers 4 to rotate around a vertical axis with respect to the flat surface on the outer peripheral side of the abrasive body 2, more specifically, for example, It is preferable to provide an angle applying means (not shown) for rotating the cylinder 7 to which the frame 6 supporting the pair of specimen rollers 4 is attached around the shaft member 8 inside the cylinder 7. Since the wear test can be performed in a state where a predetermined angle is given to the running direction of the sample specimen 20 with respect to the running direction of the polishing body 2 by means, a slip angle is given by the wear test apparatus 1. Thus, it is possible to predict the wear of an actual tire that performs load rolling in a state with high accuracy with high accuracy.

In this case, a plurality of three-component force sensors provided in the circumferential direction of the polishing body 2, the pressing force of the sample specimen 20 on the polishing body 2, the traveling speed of each of the sample specimen 20 and the polishing body 2, and In order to control each angle of the traveling direction of the sample specimen 20 with respect to the traveling direction of the polishing body 2, for example, as illustrated in FIG. 8, first, as in the method illustrated in FIG. Each of the measured value and the measurement value of the shearing force in the circumferential direction of the polishing body 2 is examined to determine whether or not it falls within a preset range. If these measured values are both within the set range, then, It is examined whether or not the measured value of the shearing force in the width direction of the polishing body 2 is within the set range.
When the measured value of the shear force in the width direction is out of the set range, the angle of the sample specimen 20 with respect to the polishing body 2 is adjusted.

  By using such a control method, the actual tires faithfully reproduce the circumferential and width direction shear stress state and the contact pressure state in the contact surface when a slip force is applied and a lateral force is applied. be able to.

DESCRIPTION OF SYMBOLS 1 Abrasion test apparatus 2 Abrasive body 2a Rubber member 2b Polishing cloth 3 Abrasive body roller 4 Specimen roller 5 Pressing means 6 Frame 7 Cylindrical body 7a Top wall 8 Shaft member 9 Coil spring 10 Cam 20 Sample specimen V1 Sample specimen running Speed V2 Abrasive speed

Claims (3)

An endless annular polishing body and a pair of polishing body rollers around which the polishing body is wound and at least one of which is rotationally driven are provided, and a sample specimen made of an elastic material is placed on the outer peripheral surface of the polishing body. A wear test device that presses and measures the amount of wear of a sample specimen,
A sample specimen formed in an endless annular shape is directly or indirectly wound, and a pair of specimen rollers, at least one of which is rotationally driven. A wear test apparatus comprising a flat surface portion on the side facing each other and a pressing means for separating and approaching the pair of specimen rollers with respect to the polishing body.   A three-component force sensor that measures component forces in three directions in a circumferential direction and a width direction of the polishing body and a direction orthogonal to the outer peripheral surface of the polishing body is attached to a plurality of locations in the circumferential direction of the polishing body. Item 2. The wear test apparatus according to Item 1.   The wear test apparatus according to claim 1 or 2, further comprising roller displacement means for bringing the pair of specimen rollers apart from each other and causing proximity displacement.

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