Rubber friction test method and rubber friction test device

Abstract

To allow for quickly heating a test road surface to a desired temperature.SOLUTION: A rubber friction test method is provided, comprising bringing a heat transfer member 24 provided with a heating unit 20 into contact with a test road surface 1, heating the test road surface 1 by making the heating unit 20 generate heat while being deformed along the test road surface 1, and sliding a rubber test piece 2 on the heated test road surface 1 to measure a friction coefficient between the test road surface 1 and the rubber test piece 2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a rubber friction testing method and a rubber friction testing device. [Background technology]

[0002] In order to evaluate the frictional properties of rubber materials used in rubber products such as tires, rubber friction tests are conducted using a testing machine installed indoors in which a rubber test piece is pressed and slid on a test surface formed from aggregate, resin, etc. (see Patent Documents 1 and 2).

[0003] Incidentally, when evaluating the frictional characteristics of a rubber material that is highly temperature-dependent, a rubber friction test may be performed on a test road surface that has been heated to a predetermined temperature by a heater.

[0004] However, in tests using test roads with large irregularities, such as asphalt roads, if a heater is buried inside the road taking into account the strength of the test road surface, the distance (thickness) from the heater to the surface of the test road becomes large, and it takes a long time to heat up to the desired temperature.

[0005] It is also possible to heat the surface of the test road by covering it with a heated metal plate, but because the test road surface is uneven, the heat from the metal plate is difficult to transfer to the test road surface due to the space created between the metal plate and the test road surface, and it takes a long time to heat it to the desired temperature. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2005-233797 [Patent Document 2] Patent Publication No. 2017-58244 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a rubber friction testing method and a rubber friction testing device that can heat the test road surface to a desired temperature in a short period of time. [Means for solving the problem]

[0008] The rubber friction testing method of this embodiment is a rubber friction testing method in which a test road surface is heated by a heating unit arranged opposite the test road surface, and a rubber test piece is slid across the heated test road surface to measure the friction coefficient between the test road surface and the rubber test piece, in which a heat transfer member provided on the heating unit is brought into contact with the test road surface and deformed along the test road surface, and the heating unit is caused to generate heat to heat the test road surface.

[0009] In addition, the rubber friction testing device of this embodiment is a friction testing device that includes a test road surface, a heating unit that is arranged opposite the test road surface and heats the test road surface, a holder that holds a rubber test piece and presses it against the test road surface, and a measuring unit that slides the rubber test piece on the heated test road surface to measure the friction coefficient between the test road surface and the rubber test piece, and the heating unit includes a heat transfer member that is in contact with the test road surface and is arranged to be deformable along the test road surface, and transfers heat to the test road surface via the heat transfer member. Effect of the Invention

[0010] In the above-mentioned rubber friction testing method and rubber friction testing device, the heat of the heating section can be efficiently transferred to the test road surface by a heat transfer member that is in contact with the test road surface and is deformable along the test road surface, and the test road surface can be heated to the desired temperature in a short period of time. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a rubber friction test device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a state in which a test road surface is being heated by a heating unit in the rubber friction test device of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is merely an example, and any appropriate modification that does not deviate from the gist of the present invention is included in the scope of the present invention.

[0013] The rubber friction testing device 10 of this embodiment shown in Figure 1 comprises a test road surface 1 simulating an actual road surface, a holder 3 for holding a rubber test piece 2, a loading device 4 for pressing the rubber test piece 2 against the test road surface 1, a driving device 5 for moving the rubber test piece 2 relative to the test road surface 1, a load sensor 6 for measuring the load acting on the rubber test piece 2, a control device 7 for controlling operations required for the test, a heating unit 20, and a temperature sensor 30 for measuring the temperature of the test road surface 1.

[0014] The test road surface 1 is formed to simulate an actual road surface such as an asphalt road surface. The test road surface 1 is formed by bonding aggregate 1a actually used on roads or hard aggregate 1a having properties equivalent thereto with an adhesive (see FIG. 2). Alternatively, the test road surface 1 is formed by cutting out a road surface from an actual road and processing it for measurement. The method of forming the test road surface 1 may be other than the above and is not particularly limited. The surface of the test road surface 1 is generally flat, but there are irregularities due to the aggregate 1a.

[0015] The rubber test piece 2 is made of vulcanized rubber and has a flat surface that is pressed against the test road surface 1. In the example of Fig. 1, the rubber test piece 2 has a perfect rectangular parallelepiped shape, and its upper surface is adhered to a plate-shaped holder 3. Therefore, the lower surface of the rubber test piece 2 that faces the test road surface 1 becomes the flat surface that is pressed against the test road surface 1.

[0016] The holder 3 is connected to a loading device 4. The loading device 4 is configured to be able to reciprocate the holder 3 in the Z direction (the up and down direction in FIG. 1) perpendicular to the test road surface 1. By appropriately setting the position of the holder 3 (the distance between the holder 3 and the test road surface 1), the load in the Z direction input to the rubber test piece 2 can be adjusted, and the rubber test piece 2 can be pressed against the test road surface 1 under predetermined pressure conditions. The loading device 4 is configured by a servo motor, but other actuator mechanisms may also be used.

[0017] The driving device 5 is configured to reciprocate a table 8 supporting the load device 4 along the X direction (left and right direction in FIG. 1). The movement of this table 8 moves the holder 3, and the rubber test piece 2 can be moved while sliding on the test road surface 1. The actuator 9 is configured to reciprocate the table 8 along the Y direction (direction perpendicular to the paper surface of FIG. 1) perpendicular to both the X direction and the Z direction. The actuator 9 is used to align the rubber test piece 2 with the test road surface 1 in the Y direction. In this embodiment, the driving device 5 and the actuator 9 are each configured by a servo motor, but are not limited to this.

[0018] The load sensor 6 can measure three load components in total, a vertical component and two horizontal components, and can measure the load in the Z direction (vertical force), the load in the X direction (front-rear force), and the load in the Y direction (lateral force) acting on the rubber test piece 2. The load sensor 6 is formed of, for example, a load cell. In this embodiment, the load sensor 6 is attached to the upper side of the holder 3 (the side opposite to the rubber test piece 2).

[0019] The control device 7 includes a calculation unit 7a that performs calculations required for measuring the friction coefficient, an operation control unit 7b that controls the operation of the load device 4, the drive device 5, a heating drive unit 25 described later, and the like, an input unit 7c that receives input from a test operator, and a display unit 7d that displays various information related to the operation and settings of the rubber friction test device 10 on a screen. The measurement value by the load sensor 6 is sent to the control device 7, and the calculation unit 7a calculates the friction coefficient based on the measurement value. In other words, in this embodiment, the load sensor 6 and the control device 7 realize a measurement unit that measures the friction coefficient between the test road surface 1 and the rubber test piece 2.

[0020] The heating unit 20 is disposed opposite the test road surface 1 as shown in FIG. 2 and heats the test road surface 1 before measuring the coefficient of friction between the test road surface 1 and the rubber test piece 2 .

[0021] Specifically, the heating section 20 comprises a heater section 22, a heat transfer member 24 and a heating drive section 25, and the heating drive section 25 presses the heater section 22 in a heated state against the test road surface 1 with the heat transfer member 24 sandwiched therebetween, thereby transferring heat generated in the heater section 22 to the test road surface 1 via the heat transfer member 24, thereby heating the surface of the test road surface 1 to a predetermined temperature.

[0022] The heater unit 22 is a flat plate-shaped heating element having a heater and the like, and is disposed so as to face the test road surface 1 in the Z direction. One surface of the heater unit 22 is provided with a sheet-shaped heat transfer member 24 that contacts the test road surface 1.

[0023] The heat transfer member 24 has the flexibility to deform in accordance with the unevenness formed by the aggregate 1a on the surface of the test road surface 1 when it is sandwiched between the test road surface 1 and the heater section 22 when the heating section 20 heats the test road surface 1.

[0024] The heat transfer member 24 is preferably made of a resin composition having appropriate flexibility, thermal conductivity, and heat resistance, such as silicone resin or acrylic resin. The heat transfer member 24 may be made of a resin composition such as silicone resin or acrylic resin to which a heat stabilizer is added to improve heat resistance, or a filler may be added.

[0025] The hardness of the heat transfer member 24 is preferably a penetration of 40 according to JIS K 2220. When the penetration is 40 or more, the heat transfer member 24 is easily deformed along the irregularities formed on the surface of the test road surface 1, and the contact area of ​​the heat transfer member 24 with the test road surface 1 can be increased, and the proportion of air with low thermal conductivity between the test road surface 1 and the heat transfer member 24 can be reduced, thereby increasing the rate at which heat is transferred from the heating unit 20 to the test road surface 1. There is no particular upper limit to the penetration of the heat transfer member 24, but a penetration of 80 or less is preferable from the viewpoint of ease of handling.

[0026] The thermal conductivity of the heat transfer member 24 is preferably higher than that of the aggregate 1a constituting the test road surface 1. For example, the thermal conductivity of the heat transfer member 24, as measured by the hot-wire method in accordance with JIS R 2616, is preferably 1 W / m K or more and 5 W / m K or less.

[0027] The heat-resistant temperature of the heat transfer member 24 is preferably, for example, 100° C. or higher. In this specification, the term "heat-resistant temperature" means a temperature at which the physical properties of the material are not substantially impaired even when the material is exposed to the temperature, and may be a continuous use temperature (long-term heat-resistant temperature) or a short-term heat-resistant temperature. The short-term heat-resistant temperature may be the melting point in the case of a crystalline organic material, or the glass transition temperature in the case of a non-crystalline organic material.

[0028] The thickness of the heat transfer member 24 is preferably equal to or greater than the maximum height of the unevenness formed on the surface of the test road surface 1. By making the thickness of the heat transfer member 24 equal to or greater than the maximum height of the unevenness formed on the surface of the test road surface 1, the proportion of air with low thermal conductivity between the test road surface 1 and the heat transfer member 24 can be reduced, and the contact area of ​​the heat transfer member 24 with the test road surface 1 can be increased to reduce the thermal resistance between the heat transfer member 24 and the test road surface 1, and the heat of the heater unit 22 can be efficiently transferred to the test road surface 1. In addition, in order to reduce the thermal resistance of the heat transfer member 24 itself, the thickness of the heat transfer member 24 is preferably equal to or greater than 1 mm and equal to or less than 3 mm.

[0029] Furthermore, the heat transfer member 24 adheres to the heater section 22 when pressed against the heater section 22 due to the properties of the material of the heat transfer member 24, without being coated with, provided with, or impregnated with an adhesive, but it is preferable that the heat transfer member 24 has the property (self-adhesiveness) of being able to be peeled off without transferring to the heater section 22 when peeled off.

[0030] The heating drive unit 25 is configured to be able to move the heating unit 20 back and forth along the X and Z directions. The heating drive unit 25 adjusts the position of the heating unit 20 in the X direction so that the heat transfer member 24 faces the test road surface 1 in the Z direction, and then appropriately sets the position of the heat transfer member 24 in the Z direction, thereby adjusting the Z-direction load input to the heat transfer member 24 and pressing the heat transfer member 24 against the test road surface 1 under a predetermined pressure condition.

[0031] In the rubber friction testing device 10, first, as shown in Fig. 2, the driving device 5 moves the table 8 to one side in the X direction, and then the heating driving unit 25 positions the heating unit 20 so as to face the test road surface 1 in the Z direction. Then, while causing the heater unit 22 to generate heat, the heating driving unit 25 presses the heat transfer member 24 against the upper surface of the test road surface 1, deforming the heat transfer member 24 so as to conform to the unevenness formed on the surface of the test road surface 1. In this way, the heat generated by the heater unit 22 is transferred to the test road surface 1 via the heat transfer member 24, and the test road surface 1 is heated.

[0032] Then, when the detected temperature of the temperature sensor 30 reaches a predetermined temperature, the heating drive unit 25 moves the heating unit 20 in the Z direction to separate the heat transfer member 24 from the test road surface 1, and also moves the heating unit 20 to the other side in the X direction (see Figure 1).

[0033] Then, as shown in Figure 1, the driving device 5 moves the table 8 to the other side in the X direction, and the holder 3 is positioned above the test road surface 1.Then, the flat surface of the rubber test piece 2 is pressed against the test road surface 1, and the load is measured when the rubber test piece 2 is moved in a straight line while sliding on the test road surface 1 heated to a predetermined temperature, and the static friction coefficient and kinetic friction coefficient friction between the test road surface 1 and the rubber test piece 2 are measured.

[0034] In the rubber friction test device 10, the pressure conditions of the heat transfer member 24 pressed against the test road surface 1, the pressure conditions of the rubber test piece 2 pressed against the test road surface 1, and conditions related to the linear movement such as the speed and path are controlled by the control device 7. In addition, the moving speed of the rubber test piece 2 is set so that the rubber test piece 2 slides at a uniform speed in a predetermined section.

[0035] In this embodiment, the heating part 20 is caused to generate heat to heat the test road surface 1 while the heat transfer member 24 is in contact with the test road surface 1 and deformed along the test road surface 1, so that even if the surface of the test road surface 1 is uneven, an air layer is unlikely to form between the heating part 20 and the test road surface 1, and the contact area with the heating part 20 can be increased. Therefore, the surface of the test road surface 1 can be heated to a desired temperature in a short time by a simple method without processing the test road surface 1.

[0036] In this embodiment, since the heat transfer member 24 has self-adhesive properties, the heat transfer member 24 can be arranged in close contact with the heater portion 22, and the heat transfer member 24 can be easily adhered to the test road surface 1, so that the heat from the heater portion 22 can be efficiently transferred to the test road surface 1. [Explanation of symbols]

[0037] 1... test road surface, 1a... aggregate, 2... rubber test piece, 3... holder, 4... loading device, 5... driving device, 6... load sensor, 7... control device, 7a... calculation unit, 7b... operation control unit, 7d... display unit, 10... rubber friction test device, 20... heating unit, 22... heater unit, 24... heat transfer member, 25... heating driving unit,

Claims

1. Heating the test road surface by a heating unit arranged opposite the test road surface; A rubber friction testing method in which a rubber test piece is slid on a heated test surface to measure a friction coefficient between the test surface and the rubber test piece, A rubber friction testing method in which a heat transfer member provided in the heating section is brought into contact with the test road surface and deformed along the test road surface, and the heating section is caused to generate heat to heat the test road surface.

2. 2. The rubber friction testing method according to claim 1, wherein the heat transfer member has a heat resistance temperature of 100° C. or higher.

3. 3. The rubber friction testing method according to claim 1, wherein the heat transfer member has self-adhesive properties.

4. The rubber friction testing method according to any one of claims 1 to 3, wherein the heat transfer member has a higher thermal conductivity than the aggregate constituting the test road surface.

5. The rubber friction testing method according to any one of claims 1 to 4, wherein the resin constituting the heat transfer member is either a silicone resin or an acrylic resin.

6. Test track and A heating unit disposed opposite the test road surface and heating the test road surface; A holder for holding a rubber test piece and pressing it against the test road surface; a measurement unit for measuring a coefficient of friction between the test surface and the rubber test piece by sliding the rubber test piece on the heated test surface, The heating section is provided with a heat transfer member that is in contact with the test road surface and is deformable along the test road surface, and the rubber friction testing device transfers heat to the test road surface via the heat transfer member.

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