WO2012132226A1

WO2012132226A1 - Wear test apparatus

Info

Publication number: WO2012132226A1
Application number: PCT/JP2012/001349
Authority: WO
Inventors: 智史柴田
Original assignee: 株式会社ブリヂストン
Priority date: 2011-03-28
Filing date: 2012-02-28
Publication date: 2012-10-04
Also published as: JP2012202926A

Abstract

A wear test apparatus (1) comprises: an abrasive body (2) having an endless ring shape; a pair of abrasive body rollers (3) where the abrasive body (2) is wound, at least one half of the pair being capable of rotational driving; a test piece (20) formed of an elastic material; and a test piece holding medium (4) capable of moving the test piece (20) away from or toward a flat surface portion at an outer circumferential side of the abrasive body (2), the test piece (20) being pressed at the flat surface portion of the abrasive body (2) to measure an abrasion loss of the test piece (20). A reciprocating driving means (5) displaces the test piece (20) in parallel with the flat surface portion and toward a front side or a rear side in a driving direction of the flat surface portion which presses the test piece (20) of the abrasive body (2) wound around the abrasive body roller (3) which is rotationally driven.

Description

Abrasion test equipment

The present invention wears a tread rubber test piece by pressing a test piece made of an elastic material such as a rubber material constituting a tread portion of the tire onto a flat surface of an abrasive body that is relatively displaced with respect to the test piece. The present invention relates to a wear test apparatus that measures the quantity with a high correlation with an actual tire. Specifically, in the wear test, the circumferential direction and the width direction within the contact surface during load rolling of the actual tire. The present invention proposes a technique capable of faithfully reproducing the shear stress state and the ground 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 on the tread contact surface of the 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. In addition, it is an object of the present invention to provide a wear test apparatus that can faithfully reproduce the ground contact pressure condition 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 the position 101b immediately below the load, increases in the opposite direction toward the kicking position 101c, and reaches the kicking position 101c. On the other hand, slip occurs between the road surface 110 and a large shear stress acts instantaneously. On the other hand, release of the tread block from the ground contact surface causes the circumferential shear stress to rapidly decrease.
Here, in the pneumatic tire, since the tread contact surface is pushed and deformed by the action of the contact pressure, the tread block is substantially parallel to the road surface between the stepping position 101a and the kicking position 101c. Will come into contact.

Therefore, in the abrasion test using the test piece of the tread rubber material, the degree of wear of the tread ground contact surface of the tire that rolls on the road surface is actually reproduced by faithfully reproducing the shear stress state shown in FIG. It was thought that it was possible to predict accurately with high correlation with the tires.

Based on such knowledge, the wear test apparatus of the present invention comprises an endless annular abrasive body, a pair of abrasive rollers around which the abrasive body is wound and at least one of which can be rotationally driven, and an elastic material. A test piece holding means for holding the test piece and separating and approaching the test piece with respect to the flat surface portion on the outer peripheral side of the polishing body, and pressing the test piece against the flat surface portion of the polishing body Measuring the amount of wear of the test piece, the front side of the flat surface portion in the running direction of the flat surface portion pressing the test piece of the abrasive body wound around the abrasive roller that is rotationally driven around the test piece, and A reciprocating drive means for providing a displacement parallel to the flat surface portion to the rear side is provided.

Here, the reciprocating drive means is not only for displacement of the test piece in the running direction of the flat surface portion but also in parallel to the flat surface portion in a direction perpendicular to the running direction of the flat surface portion. It is preferable to make it possible to make a large displacement.

Preferably, a three-component force sensor for measuring forces in three directions in the circumferential direction and width direction of the polishing body and in a direction perpendicular to the outer peripheral surface of the polishing body is attached to a plurality of locations in the circumferential direction of the polishing body. For example, based on the measurement value by the three-component force sensor, the rotational speed of the polishing body roller, the pressing force of the test piece against the flat surface portion of the polishing body by the test piece holding means, and the test piece by the reciprocating drive means Control means for feedback control of the displacement speed is provided.

According to the wear test apparatus of the present invention, the test piece is placed on the flat surface portion of the outer peripheral surface of the endless abrasive that is wound around the pair of abrasive rollers and can be driven in the circumferential direction by the test piece holding means. In the state where the test piece is pressed onto the polishing body, the test piece is directed toward the front side or the rear side in the traveling direction of the flat surface portion, for example, on the polishing body. By displacing at a required relative speed with respect to the traveling speed, and then separating the test piece from the outer peripheral surface of the polishing body, the pressing force of the test piece on the polishing body and the test piece of the polishing body Under the respective control of the relative displacement speed with respect to the flat surface portion, it is possible to faithfully reproduce the circumferential shear stress state on the ground contact surface between the actual tire stepping-in and the kicking-out as described above. Of the tire Worn can be predicted with a high accuracy.

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 test piece is worn on the outer peripheral surface of the polishing body is pressed against the test piece. Since the polishing body is carried forward in the traveling direction and can be easily removed by a brush or the like, the influence of the wear powder on the wear state of the test piece can be surely removed. .

Here, when the reciprocating drive means is configured to be able to displace the test piece in a direction perpendicular to the traveling direction of the flat surface portion, the slip angle is set with an actual tire. It is possible to faithfully reproduce the circumferential and width direction shear stress states and the contact pressure state in the contact surface when a lateral force is applied.

Here, when the three-component force sensor is attached to a plurality of locations in the circumferential direction of the polishing body, the stress in each direction that the test piece receives from the polishing body can be measured in real time, and such measurement values are used. In addition, by controlling the pressing force of the specimen against the abrasive body and the relative speed of the specimen against the abrasive body, circumferential shear stress is generated on the ground contact surface when the tire is rolling. A more faithful reproduction of the situation and changes to the test conditions as required.

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 shown in FIG. It is a schematic perspective view which expands and shows the reciprocating drive means of the apparatus shown in FIG. FIG. 4 is a view similar to FIG. 3 showing a use state of the apparatus shown in FIG. 3. It is a figure which shows typically the change of the circumferential direction shear stress of a test piece in the test which can be performed using the apparatus shown in FIG. It is a graph which shows the shearing stress at the time of changing the pressing force etc. of a test piece 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 shown in FIG. It is a flowchart which shows the other example of the control method in the abrasion test performed using the apparatus shown in 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). The test piece 20 made of rubber material or the like that forms the tread portion of the tire is held at the body roller 3 and the end portion on the polishing body 2 side, for example, and the test piece is against the flat surface portion on the outer peripheral side of the polishing body 2. Specimen holding means 4 for separating and approaching 20.

And here, the test piece 20 is wound around the abrasive body roller 3 that is rotationally driven, and for example, the flat surface portion on the test piece 20 side of the abrasive body 2 that runs in the direction indicated by the arrow A in the figure. A reciprocating drive means 5 is disposed on the front side or the rear side in the traveling direction so as to be displaced at a required speed in parallel with the flat surface portion.

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 based on JISK6264.

Here, when performing a wear test, which will be described later, in order to feedback control the pressing force of the test piece 20 to the polishing body 2, the circumferential direction and width of the polishing body 2 are provided at a plurality of locations in the circumferential direction of the polishing body 2. It is preferable to provide a three-component force sensor (not shown) that measures the force in the three directions in the direction and the direction orthogonal to the outer peripheral surface of the polishing body 2.
Such a three-component force sensor can be placed, for example, on the inner peripheral surface of the polishing body 2 or embedded in the polishing body 2, and each sensor uses, for example, a slip ring or the like. It is possible to connect to a measuring instrument (not shown) in a wired or wireless manner.

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.
Although not shown, the inner peripheral surface of the polishing body 2 is interposed between the pair of polishing body rollers 2 in order to suppress the bending or escape deformation of the polishing body 2 when the test piece 20 is pressed against the polishing body 2. It is also possible to provide one or a plurality of support rollers in contact with each other.

By the way, as the test piece holding means 4 for separating and approaching the test piece 20 with respect to the flat surface portion on the outer peripheral side of the polishing body 2, for example, a cam mechanism whose main part is illustrated in an enlarged sectional view in FIG. 4 is used. be able to.
That is, the illustrated test piece holding means 4 includes a sleeve 6 attached to a frame (not shown) and a shaft that holds the test piece 20 at one end portion (lower end portion in the drawing) and slides and displaces inside the sleeve 6. The plate 8 as a cam follower attached to the member 7 and the other end portion (upper end portion in the figure) of the shaft member 7 and the plate 8 is urged and supported in the separating direction with respect to the opening peripheral edge of the sleeve 6. The coil spring 9 includes a cam 10 which is provided in contact with the plate 8 and is driven to rotate.

According to this test piece holding means 4, the shaft member 7 together with the plate 8 spring-biased with respect to the sleeve 6 based on the rotation of the eccentric cam 10 driven to rotate around the axis is indicated by an arrow in the figure. As shown, the test piece 20 held on one end portion of the shaft member 7 is separated and moved closer to the polishing body 2 by being displaced vertically.
In place of the cam mechanism of the test piece holding means 4, although not shown, a ball screw or a rack and pinion can be used as the holding means 4 for controlling the raising and lowering of the test piece. , Larger displacement can be performed with higher 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.

The reciprocating drive means 5 is laid on a base 30 on which the apparatus 1 is installed, for example, as shown in a perspective view in FIG. 5, and extends in the traveling direction of the polishing body 2 or in a direction perpendicular to the traveling direction. A pair of fixed rails 5c and a plate running on the fixed rails 5c based on the application of a driving force by a servo motor or air pressure (not shown) and a plate laid on the plates and extending in a direction perpendicular to the fixed rails 5c. The movable rail member 5b composed of a pair of rails and a support shaft 5a that travels on the movable rail member 5b by applying the same driving force and grips the test piece holding means 4 can be configured.
In addition, although illustration is abbreviate | omitted, a reciprocating drive means can also be comprised only by a pair of fixed rail extended in the running direction of the grinding | polishing body 2 as mentioned above, and the support shaft which drive | works on the fixed rail.

The test piece 20 used in such an abrasion test apparatus 1 may be a rubber test piece prepared for testing in advance or a block test piece cut out from a tread portion of a tire. The dimension of the test piece 20 is 1 cm to 30 cm in the length (vertical direction) along the circumferential direction (left-right direction in FIG. 3) of the polishing body 2 in a state of being held by the test piece holding means 4. Further, the length (horizontal) along the width direction of the polishing body 2 (the front and back direction in FIG. 3) is set to 1 cm to 30 cm, and the direction orthogonal to the surface of the flat surface portion of the polishing body 2 (in FIG. 3). The thickness (height) in the direction along the (up and down direction) is preferably 3 mm to 30 mm, but it is also possible to use a test piece having a dimension outside these numerical ranges.

In order to perform a wear test with the wear test apparatus 1 described above, first, as shown in FIG. 3, for example, a test piece 20 formed in a rectangular parallelepiped shape is held on the lower end portion of the test piece holding means 4, and The endless annular polishing body 2 is caused to travel in the circumferential direction, for example, as indicated by an arrow A in the drawing based on the application of a rotational driving force by a motor or the like to the polishing body roller 3.

Then, as illustrated in FIG. 6, the abrasion test presses the test piece 20 against the flat surface portion on the outer peripheral side of the polishing body 2 with a required force based on the operation of the test piece holding means 4. With the test piece 20 pressed against the portion, the reciprocating drive means 5 causes the test piece 20 to be, for example, on the front side in the running direction of the flat surface portion at a required slip ratio with respect to the running speed of the polishing body 2. Then, based on the respective operations of the test piece holding means 4 and the reciprocating drive means 5, the test piece 20 is separated from the polishing body 2 and is displaced rearward in the running direction of the flat surface portion. The test piece 20 can be moved to the position at the start of the test.

Here, in the above-described wear test, the test piece 20 mainly adheres between the test piece 20 and the polishing body 2 as the flat surface portion of the polishing body 2 is pressed, as schematically shown in FIG. As a result, the circumferential shear stress gradually increases, but due to the displacement of the flat surface portion based on the reciprocating drive means 5 toward the front side in the traveling direction, the shear stress is once reduced and the specimen 20 is polished. After a large shearing stress is applied based on a decrease in the relative speed with respect to the body 2, slipping occurs between the test piece 20 and the abrasive body 2 due to the separation operation of the test piece 20 by the test piece holding means 4. Directional shear stress will drop rapidly.

That is, according to the above-described wear test performed using the wear test apparatus 1, the circumferential shear stress state at the ground contact surface of the actual tire as illustrated in FIG. As a result, tire wear can be predicted with high accuracy.

Here, the abrasion test apparatus 1 is used to polish the test piece 20 in a state where the relative speed of the test piece 20 to the polishing body 2 is 0, that is, the test piece 20 is pressed against the flat surface portion of the polishing body 2. A wear test can also be performed by displacing the body 2 at a constant speed.
Moreover, in the case where the test piece 20 is pressed to the polishing body 2 a plurality of times in one test, the pressing force of the test piece 20 to the polishing body 2 or the test piece 20 By changing the relative speed with respect to the polishing body 2, it is possible to reproduce a shear stress as shown by a broken line in FIG.
Further, the traveling speed of the abrasive body 2 during the test is not particularly limited, but can be, for example, 0.1 km / h to 50 km / h, and in particular, 0.5 km / h to 35 km. It is preferable to set to / h in that a good wear characteristic evaluation by the wear test apparatus 1 becomes possible.

When a plurality of three component force sensors are provided in the circumferential direction of the polishing body 2, the pressing force of the test piece 20 from the sensors to the polishing body 2, and the circumferential direction and width of the polishing body 2 are provided. Based on the measured values of the direction shear force, the circumferential shear stress when the test piece 20 is pressed against the polishing body 2 is shown in FIG. By controlling the pressing force of the test piece 20 on the polishing body 2, the displacement speed of the test piece 20, and the running speed of the polishing body 2 so as to obtain a waveform corresponding to Can be predicted with accuracy.

An example of such a control method is shown in the flowchart of FIG.
In the control method shown in FIG. 9, first, it is examined whether or not the measured value of the pressing force of the test piece 20 falls within a preset range, and if the measured value of the pressing force is out of this range, the test is performed. The pressing force by the piece holding 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 directional shear force is out of this range, the relative value of the displacement speed of the test piece 20 based on the reciprocating drive means 5 with respect to the traveling speed of the polishing body 2 is adjusted.

As a result, the pressing force of the test piece 20 on the polishing body 2 and the circumferential shearing force of the test piece 20 can be controlled as expected. It is possible to faithfully reproduce the circumferential shear stress state in the ground contact surface at the time of load rolling of the tire.

By the way, as shown in FIG. 5, the reciprocating drive means 5 for causing the test piece 20 to directly move the test piece holding means 4 holding the test piece 20 in the traveling direction of the polishing body 2 is shown in FIG. It is preferable that the polishing body 2 can be displaced in a direction perpendicular to the traveling direction of the polishing body 2.
According to this, since the test piece 20 can be moved left and right in the direction orthogonal to the traveling direction of the polishing body 2 when pressed against the polishing body 2, a slip angle is given by the wear test apparatus 1. Thus, it is possible to predict the wear of an actual tire that is loaded and rolled in a hot state.

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 test piece 20 to the polishing body 2, the displacement speed of the test piece 20, the traveling speed of the polishing body 2, and In order to control each of the moving speeds of the test piece 20 in the direction orthogonal to the traveling direction of the polishing body 2, for example, as illustrated in FIG. 10, first, as in the method shown in FIG. It is examined whether or not the measured values of the pressing force of 20 and the shearing force in the circumferential direction of the polishing body 2 are within a preset range, and when these measured values are both within the set range. Next, 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 width direction shear force is out of the set range, the moving speed of the test piece 20 in the direction orthogonal to the traveling direction of 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 Wear test apparatus 2 Polishing body

2a Rubber member

2b Polishing cloth 3 Polishing body roller 4 Test piece holding means 5 Reciprocating drive means 5a Support shaft 5b Movable rail member 5c Fixed rail 6 Sleeve 7 Shaft member 8 Plate 9 Coil spring 10 Cam 20 Test Fragment

Claims

An endless annular abrasive body, a pair of abrasive rollers around which the abrasive body is wound and at least one of which can be driven to rotate, and a test piece made of an elastic material are held, and a flat surface portion on the outer peripheral side of the abrasive body A test piece holding means for separating and approaching the test piece, and pressing the test piece against the flat surface portion of the polishing body to measure the wear amount of the test piece,
A reciprocating movement of the abrasive body wound around the abrasive roller that is driven to rotate in parallel with the flat surface portion toward the front side and the rear side in the running direction of the flat surface portion that presses the test piece. A wear test apparatus provided with driving means.
The wear test apparatus according to claim 1, wherein the reciprocating drive means is configured to be capable of displacing the test piece in a direction perpendicular to the traveling direction of the flat surface portion in parallel with the flat surface portion.
A three-component force sensor for measuring forces in three directions in the circumferential direction and width direction of the polishing body and in a direction perpendicular to the outer peripheral surface of the polishing body is attached to a plurality of locations in the circumferential direction of the polishing body. The wear test apparatus according to 1 or 2.