JP2015141017A - Tire testing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a testing method that can create a condition of breaker edge looseness in a testing device having a rotatable drum.SOLUTION: A testing method to be implemented by using a testing device 36 having a support 40 for supporting a tire 2 and a drum 42 for rotationally driving this tire 2 comprises (1) an adjusting step of adjusting the inner pressure P and the camber angle CA of the tire 2 (STEP 2), (2) a grounding step of imposing a load F on this tire 2 by bringing the tire 2 into contact with a driving surface 46 (STEP 3) and (3) a driving step of driving the tire 2 while increasing the speed stepwise (STEP 4).

Description

  The present invention relates to a tire testing method. Specifically, the present invention relates to a test method for confirming the durability of a tire.

  A tire as an evaluation target may be mounted on an actual vehicle to check the durability of the tire. In this case, after running a specified distance, a sample is taken from the tire, and the physical properties of this sample are evaluated. In this test method, since the time required for the evaluation is long, development based on the evaluation result cannot be promptly advanced. In addition, the development cost is significant.

  From the viewpoint of shortening the evaluation time and reducing the cost, there is a test method for evaluating the durability of a tire on a table using a rotatable drum. An example of this test method is disclosed in Japanese Patent Application Laid-Open No. 2004-132847.

JP 2004-132847 A

  The tire includes a breaker on the radially inner side of the tread. The breaker is laminated with the carcass. The breaker consists of an inner layer and an outer layer. Each of the inner layer and the outer layer is composed of a large number of cords arranged in parallel and a topping rubber.

  A tire in a running state is repeatedly deformed. The end of the breaker is located near the end of the tread. Distortion tends to concentrate on the edge of the breaker. Moreover, the deformation causes heat generation. Therefore, at the end of the breaker, the breaker cord may be peeled off from the rubber around it. This damage accompanied by peeling is also referred to as breaker edge loose (BEL).

  In some cases, the above-described BEL may be reproduced using a rotatable drum. However, it takes a considerable amount of time to generate BEL simply by running a tire on a drum. Further, when deterioration is promoted by heating or the like, damage other than BEL occurs. It is not easy to generate BEL in a short time.

  An object of the present invention is to provide a test method capable of generating a breaker edge loose in a short time in a test apparatus having a rotatable drum.

The tire test method according to the present invention is performed using a test apparatus including a support portion that supports a tire and a drum that rotationally drives the tire. This test method is
(1) An adjusting step for adjusting the internal pressure P and the camber angle CA of the tire,
(2) It includes a grounding step of bringing the tire into contact with the running surface and applying a load F to the tire, and (3) a running step of running the tire while gradually increasing the speed. In this test method, the temperature of the atmosphere in which the traveling process is performed is 20 ° C. or higher and 30 ° C. or lower. This travel process is
(3) -1 preliminary step of preliminarily driving the tire at a speed _{V w,}
(3) -2 The first step of traveling the speed _{V w} of said tire by increasing the speed _{V 1} at this speed _{V 1,}
(3) -3 second step and (3) the speed _{V 1} is raised to a speed _{V 2} is caused to travel the tire at this speed _{V 2} -4 stepwise increasing the speed from the speed _{V 2} by 10 km / h However, an acceleration step of running the tire is included. In this test method, the internal pressure P is 100% to 120% of the standard internal pressure of the tire. The absolute value of the camber angle CA is not less than 2 ° and not more than 4 °. The load F is 60% or more and 90% or less of the standard load of the tire. The speed _Vw is not less than 60% and not more than 90% of the speed V1. Travel time _{t w} of the tire according to the speed _{V w} is 10 minutes or less than 5 minutes. The running time t _{1 of the} tire at the speed V ₁ is not less than 10 minutes and not more than 30 minutes. The difference between the speed _{V 2} and the speed _{V 1} was equal to or less than 10 km / h or more 30 km / h. Travel time _{t 2} of the tire according to the speed _{V 2} is 30 minutes or less than 10 minutes. In the promoting step, the travel time t _i of the tire by the speed which is increased stepwise is 10 minutes. When the speed symbol of the tire is V range than the velocity V ₁ of the said tire in the first step is set to 80% to 90% of the speed represented by the speed symbol of the tire. When the speed symbol of the tire is less than H range, the speed V ₁ of the said tire in the first step is set equal to the speed represented by the speed symbol of the tire.

  Preferably, the test method of the tire is configured such that when the temperature of the bead portion of the tire exceeds 90 ° C. before the speed is increased in the running step, the bead portion is increased before the speed is increased. Is further cooled to bring the temperature of the bead portion to less than 90 ° C.

  In the tire testing method according to the present invention, the tire is caused to travel while the speed is increased stepwise while the camber angle CA is applied to the tire. In this test method, the speed profile, the camber angle CA, the internal pressure P of the tire, and the load F applied to the tire are appropriately adjusted in the traveling process. According to this test method, the breaker edge loose can be generated in a short time. This test method can contribute to rapid development of tires and reduction of development costs.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire used in a test method according to an embodiment of the present invention. FIG. 2 is a conceptual diagram showing a test apparatus for testing the tire of FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a flowchart showing a test method using the test apparatus of FIG. FIG. 5 is a flowchart showing a running process included in the test method of FIG.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 shows a pneumatic tire 2. In FIG. 1, the vertical direction is the radial direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. In FIG. 1, an alternate long and short dash line CL represents the equator plane of the tire 2. The shape of the tire 2 is symmetrical with respect to the equator plane except for the tread pattern.

  The tire 2 is incorporated in the rim 4. The rim 4 is a regular rim. The tire 2 is filled with air. The internal pressure of the tire 2 is a normal internal pressure. In the present invention, the size and angle of each member of the tire 2 are measured in a state where the tire 2 is incorporated in a regular rim and the tire 2 is filled with air so as to have a regular internal pressure. At the time of measurement, no load is applied to the tire 2. In the present specification, the normal rim means a rim defined in a standard on which the tire 2 depends. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In the present specification, the normal internal pressure means an internal pressure defined in a standard on which the tire 2 relies. “Maximum air pressure” in JATMA standard, “Maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in TRA standard, and “INFLATION PRESSURE” in ETRTO standard are normal internal pressures. In this specification, the normal load means a load defined in a standard on which the tire depends. “Maximum value” published in “Maximum load capacity” in the JATMA standard, “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, and “LOAD CAPACITY” in the ETRTO standard are normal loads.

  The tire 2 includes a tread 6, a sidewall 8, a clinch 10, a bead 12, a carcass 14, a breaker 16, an inner liner 18 and a cushion layer 20. The tire 2 is a tubeless type. The tire 2 is mounted on a passenger car.

  The tread 6 has a shape protruding outward in the radial direction. The tread 6 forms a tread surface 22 that contacts the road surface. For the tread 6, a crosslinked rubber in consideration of wear resistance, heat resistance, and grip properties is used.

  The sidewall 8 extends substantially inward in the radial direction from the end of the tread 6. For the sidewall 8, a crosslinked rubber in consideration of cut resistance and weather resistance is used.

  The clinch 10 is located substantially inside the sidewall 8 in the radial direction. The clinch 10 contacts the flange 24 of the rim 4. For the clinch 10, a crosslinked rubber in consideration of wear resistance is used.

  The bead 12 is located inside the clinch 10 in the axial direction. The bead 12 includes a core 26 and an apex 28 that extends radially outward from the core 26. The core 26 has a ring shape and includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 28 is tapered outward in the radial direction. The apex 28 is made of a highly hard crosslinked rubber.

  The carcass 14 includes a carcass ply 30. The carcass ply 30 is bridged between the beads 12 on both sides. Although not shown, the carcass ply 30 includes a large number of cords arranged in parallel and a topping rubber. The cord is made of organic fiber. In the tire 2, the carcass 14 has a radial structure.

  The breaker 16 is located inside the tread 6 in the radial direction. The breaker 16 is laminated with the carcass 14. The breaker 16 includes an inner layer 32 and an outer layer 34. Although not shown, each of the inner layer 32 and the outer layer 34 is composed of a large number of cords arranged in parallel and a topping rubber. Each cord is inclined with respect to the equator plane. The absolute value of the tilt angle is usually 10 ° to 35 °. The inclination direction of the cord of the inner layer 32 with respect to the equator plane is opposite to the inclination direction of the cord of the outer layer 34 with respect to the equator plane. A preferred material for the cord is steel. An organic fiber may be used for this cord.

  The inner liner 18 is located inside the carcass 14. The inner liner 18 is joined to the inner surface of the carcass 14. For the inner liner 18, a crosslinked rubber in consideration of air shielding is used.

  The cushion layer 20 is laminated with the carcass 14 near the end of the breaker 16. The cushion layer 20 is made of a soft crosslinked rubber.

  In the tire 2 in the running state, deformation and restoration are repeated. Thereby, the tire 2 may be damaged. Examples of this damage include wear, beadleous, bead burst, tread loose case and breaker edge loose. Wear is the wear and abrasion of the tread 6. In the present invention, attrition is represented as “TW”. Beadleose is the separation of the wire forming the core 26 of the bead 12 from the rubber around it. In the present invention, beadling is represented as “BL”. The bead burst is a crack in the bead 12 portion of the tire 2. In the present invention, the bead burst is represented as “BB”. In the tread loose case, peeling occurs between the tread 6 and the breaker 16. In the present invention, the tread loose case is represented as “TLC”. Breaker edge loose is the separation of the cord from the rubber around it at the end of the breaker 16. In the present invention, the breaker edge loose is represented as “BEL”. In particular, the BEL generated in the inner layer 32 of the breaker 16 is referred to as “1st BEL”. The BEL generated in the outer layer 34 is referred to as “2nd BEL”. The test method of the present invention is for reproducing the breaker edge loose “BEL” among these damages.

  FIG. 2 schematically shows a part of the test apparatus 36 for executing the test method of the present invention. The device 36 includes a test rim 38 to which the tire 2 is mounted, a support portion 40 that supports the rim 38, and a drum 42 that rotationally drives the tire 2. The rim 38 is equivalent to the rim 4 described above.

  The rim 38 is rotatably supported by the rotation shaft 44 of the support portion 40. The support portion 40 is located on the outer side in the radial direction of the drum 42. The support unit 40 includes a rotation drive device and a brake mechanism (not shown). The support portion 40 is configured to be able to rotate the rotational shaft 44, to be driven to rotate without depending on the drum 42, and to be restrained (to apply a brake). As a result, the rim 38 can be accelerated, decelerated, and stopped. The drum 42 is rotated by an electric motor (not shown). The outer peripheral surface of the drum 42 forms a running surface 46. The traveling surface 46 corresponds to a road surface. The speed of the tire 2 running on the running surface 46 is adjusted by controlling the rotation of the rotating shaft 44 and the drum 42. From the viewpoint of easy reproduction of the state of the tire 2 traveling on the road surface, the outer diameter of the drum 42 is preferably 1.5 m or more, and preferably 2.0 m or less. More preferably, the outer diameter of the drum 42 is 1.707 m.

  In this device 36, the support portion 40 can move the tire 2 up and down by a lifting device such as a fluid pressure cylinder (not shown). As a result, the tire 2 can move away from and approach the drum 42. In this device 36, the vertical movement of the tire 2 is achieved by the support portion 40 moving the tire 2 in the left-right direction. The tire 2 mounted on the rim 38 is pressed against the drum 42 by the lifting device while a predetermined load is applied. The tire 2 can be rotationally driven by the drum 42 in this state.

  FIG. 3 shows a state where the tire 2 is in contact with the running surface 46. The left side in the drawing corresponds to the vehicle body side (inside (IN)) when the tire 2 is mounted on the vehicle body of a four-wheeled vehicle. The right side corresponds to the outside (OUT). In FIG. 3, what is indicated by a symbol CA is a camber angle. The camber angle CA is represented by an angle formed by the equator plane of the tire 2 (a one-dot chain line indicated by reference sign CL in FIG. 3) with respect to the straight line VL. The straight line VL is a straight line perpendicular to the traveling surface 46. As illustrated, the equatorial plane CL is inclined to the left side of the straight line VL. In the present invention, the camber angle CA in this case is indicated by a negative value. This camber angle CA is referred to as a negative camber angle. Although not shown, the equator plane CL may be tilted to the right of the straight line VL. In the present invention, the camber angle CA in this case is indicated by a positive value. This camber angle CA is referred to as a positive camber angle. In this device 36, the camber angle CA is adjusted by adjusting the direction of the support portion 40.

  As shown in FIG. 4, the test method of the present invention includes a preparation step (STEP 1), an adjustment step (STEP 2), a grounding step (STEP 3), and a traveling step (STEP 4). These steps are performed as follows using the tire 2 and the device 36 described above.

  In the preparation step (STEP 1), the tire 2 is mounted on the rim 38. The rim 38 is attached to the rotation shaft 44 of the support portion 40. In the adjustment step (STEP 2), the inside of the tire 2 is filled with air, and the internal pressure P of the tire 2 is adjusted. The direction of the support part 40 is adjusted, and the camber angle CA of the tire 2 is adjusted. In the ground contact step (STEP 3), the tire 2 is brought into contact with the running surface 46 of the drum 42. Thereby, a load F is applied to the tire 2. The load F is adjusted by adjusting the position of the rotating shaft 44 with respect to the traveling surface 46.

  In the traveling process (STEP 4), the tire 2 is caused to travel on the traveling surface 46 of the drum 42 while gradually increasing the speed. This traveling is continued until the tire 2 is confirmed to be damaged. In the present invention, the time required from the start of the traveling process (STEP 4) to the end of the process in which damage is confirmed is set as the time required for the test.

In the running process of the test method (STEP4), as shown in Figure 5, the tire 2 is caused to first preliminarily run at a speed _{V w} (STEP4a). Next, the speed _{V w} is raised to a speed _{V 1,} the tire 2 is caused to travel at this speed _{V 1} (STEP4b). Then, the speed _{V 1} is raised to speed _{V 2,} the tire 2 is caused to travel at this speed _{V 2} (STEP4c). Thereafter, while stepwise increasing the speed from the speed _{V 2,} the running of the tire 2 is continued (STEP4d). In the present invention, the step of preliminarily running the tire 2 at the speed _Vw is referred to as a preliminary step. Increase the speed V _w to the speed V _1, the step of moving the tire 2 at this speed V ₁ was referred to as a first step. An increased speed V ₁ to velocity V _2, the step of moving the tire 2 at this speed V ₂ is referred to as a second step. Step of running the tire 2 while stepwise increasing the speed from the speed V ₂ is referred to as promoting step. The running process (STEP 4) of this test method includes a preliminary process (STEP 4a), a first process (STEP 4b), a second process (STEP 4c), and an acceleration process (STEP 4d). In this test method, the profile of the traveling speed of the tire 2 in the traveling process (STEP 4) is configured by these processes.

As described above, in the preliminary step (STEP 4a), the tire 2 is caused to preliminarily run at a speed _{V w.} In this preliminary step (STEP 4a), the speed _{V w} is 60% to 90% of the velocity _{V 1.} By ratio velocity _{V 1} of the speed _{V w} is set to 60% or more, the speed _{V w} may contribute to the development of BEL. By setting this ratio to 90% or less, occurrence of damage other than BEL is suppressed.

In this preliminary step (STEP 4a), running time _{t w} of the tire 2 by the speed _{V w} is not more than 10 minutes or more 5 minutes. By this time t _w is set to 5 minutes or more, the speed V _w may effectively contribute to the generation of BEL. By setting this time _tw to 10 minutes or less, the occurrence of damage other than BEL is effectively suppressed.

As described above, in the first step (STEP 4b), the speed _{V w} is raised to a speed _{V 1,} the tire 2 is caused to travel at this speed _{V 1.} In the first step (STEP 4b), the speed V ₁ is set based on the speed symbol of the tire 2. This speed symbol is a symbol representing the maximum speed that can be traveled in a state in which the tire 2 is loaded under a specified condition with the mass indicated by the road index defined in the JATMA standard. This road index is an index that is defined in the JATMA standard and represents the maximum mass that is allowed to be loaded on the tire 2 under specified conditions.

In this test method, when the speed symbol of the tire 2 is not less than the V range, the speed V ₁ of the tire 2 in the first step (STEP 4b) is not less than 80% of the speed V _s represented by the speed symbol of the tire 2 90 % Or less. By the ratio of the velocity _{V 1} with respect to the velocity _{V s} is set to 80% or more, the speed _{V 1} is may contribute to the development of BEL. By setting this ratio to 90% or less, occurrence of damage other than BEL is suppressed.

In this test method, when the speed symbol of the tire 2 is equal to or lower than the H range, the speed V ₁ of the tire 2 in the first step (STEP 4b) is set to be equal to the speed V _s represented by the speed symbol of the tire 2. The Thereby, the speed V ₁ contributes to the generation of BEL, and the occurrence of damage other than BEL is suppressed.

In the first step (STEP 4b), travel time _{t 1} of the tire 2 by the speed _{V 1} was 30 minutes or less than 10 minutes. By setting the time t ₁ to 10 minutes or more, the speed V ₁ can effectively contribute to the generation of BEL. By the time t ₁ is set to 30 minutes or less, the occurrence of damage to the non-BEL is effectively suppressed.

In the second step (STEP4c), speed of the tire 2 is increased from the speed _{V 1} to velocity _{V 2.} Specifically, in the second step (STEP 4c), the difference (V ₂ −V ₁ ) between the speed V ₂ and the speed V ₁ is 10 km / h or more and 30 km / h or less. By this difference is set to more than 10 km / h, the speed _{V 2} may contribute to the development of BEL. By setting this difference to 30 km / h or less, the occurrence of damage other than BEL is suppressed.

In the second step (STEP4c), travel time _{t 2} of the tire 2 by the speed _{V 2} is less than 30 minutes 10 minutes. By setting the time t ₂ to 10 minutes or more, the speed V ₂ can effectively contribute to the generation of BEL. By the time t ₂ is set to less than 30 minutes, the occurrence of damage to the non-BEL is effectively suppressed.

In promoting step (STEP4d), speed of the tire 2 is increased stepwise from the speed _{V 2.} In the present invention, the speed that is increased stepwise in the acceleration step (STEP 4d) is referred to as a step speed ΔV. In this promotion step (STEP 4d), when the speed is further increased from the speed V ₂ to obtain the speed V ₃ , a speed obtained by adding the step speed ΔV to the speed V ₂ is set as the speed V ₃ . If the velocity V ₄ is further increased the speed from the speed V _3, the rate of addition of the step rate ΔV in the speed V ₃ is set as the speed V _4. In other words, the promoting step (STEP4d) is the third step and the speed V of the tire 2 by increasing the velocity _{V 3} to the speed _{V 4} for raising the speed _{V 2} to velocity _{V 3} moving the tire 2 at a velocity _{V 3 4} and 4th process made to drive | work. That is, this promotion step (STEP 4d) includes an _n-th step of increasing the speed V _n-1 to the speed V _n and causing the tire 2 to travel at the speed V _n . Then, the difference between the velocity _{V n} and the velocity _{V n-1} in the promoting step _{(STEP4d) (V n -V n} -1) is a step speed [Delta] V. Here, n is an integer of 3 or more.

In the promoting step (STEP4d), the tire 2 while raising the stepwise speed from the speed _{V 2} by 10 km / h is allowed to run. In other words, in this promotion step (STEP 4d), the step speed ΔV is 10 km / h. This step speed ΔV contributes to the generation of BEL and suppresses the occurrence of damage other than BEL.

In this promotion step (STEP 4d), the running time t _i of the tire 2 at a speed increased stepwise (for example, the speed V ₃ and the speed V ₄ described above) is 10 minutes. By this travel time t _i is set to 10 minutes, with the step velocity ΔV to effectively contribute to the generation of BEL, the occurrence of damage to the non-BEL is effectively suppressed.

In this test method, the internal pressure P of the tire 2 is less than 120% to 100% more than standard inner pressure _{P s} of the tire 2. By ratio standard internal pressure P _s of the internal pressure P is set to 100% or more, the occurrence of damage to the non-BEL is effectively suppressed. By setting this ratio to 120% or less, the internal pressure P can effectively contribute to the generation of BEL. In this test method, the standard internal pressure P _s is the normal internal pressure that is above.

In this test method, a load F of the tire 2 is 60% to 90% of the standard load F _s of the tire 2. By ratio standard load F _s of the load F is set to 60% or more, the load F can effectively contribute to the generation of BEL. By setting this ratio to 90% or less, the occurrence of damage other than BEL is effectively suppressed. In this test method, the standard load F _s is the normal load previously described.

  In this test method, the absolute value of the camber angle CA of the tire 2 is not less than 2 ° and not more than 4 °. By setting the absolute value of the camber angle CA to 2 ° or more, the camber angle CA can effectively contribute to the generation of BEL. By setting the absolute value of the camber angle CA to 4 ° or less, the occurrence of damage other than BEL is effectively suppressed.

  This test method is carried out indoors with the apparatus 36 shown in FIG. 2 installed in a test room. In this test method, the temperature of the atmosphere in which the traveling process (STEP 4) is performed is 20 ° C. or higher and 30 ° C. or lower. By setting the atmospheric temperature to 20 ° C. or higher, generation of BEL is promoted. This ambient temperature can contribute to shortening the required time. By setting the atmospheric temperature to 30 ° C. or lower, the occurrence of damage other than BEL is suppressed.

  As described above, in this test method, the tire 2 is caused to travel while the speed is increased stepwise in a state where the camber angle CA is given to the tire 2. In this test method, the speed profile, the camber angle CA, the internal pressure P of the tire 2 and the load F applied to the tire 2 are adjusted appropriately. According to this test method, BEL can be generated in a short time. This test method is effective for reproducing BEL. This test method can contribute to rapid development of the tire 2 and reduction of development cost.

  The tire 2 is heated by running. The heat promotes deterioration of the tire 2. In the tire 2 in the running state, the deformation of the bead 12 is large. Large deformations cause a great deal of heat. For this reason, deterioration of the bead 12 progresses more than expected, and damages other than “BEL” such as bead burst and beadleose may occur. Therefore, in this test method, when the temperature of the bead 12 portion of the tire 2 exceeds 90 ° C. before the speed is increased in the running process (STEP 4), the bead 12 portion is increased before the speed is increased. It is preferable to further include a cooling step of cooling to bring the temperature of the portion of the bead 12 to less than 90 ° C. Thereby, generation | occurrence | production of damages other than BEL is suppressed effectively. From this viewpoint, in this test method, it is preferable that the bead 12 is cooled by blowing cold air in the above-described cooling step. The temperature of the cold air is preferably 20 ° C. or less. This cooling step is particularly effective when the temperature of the portion of the bead 12 exceeds 90 ° C. in the preliminary step (STEP 4a).

In this test method, the ground contact area of the tire 2, the internal pressure of the tire 2 and the standard pressure P _S, the ground contact area in the state of the camber angle CA is 0 °, obtained when applying the standard load F _S in the tire 2 It is preferably 60% or more and 90% or less (hereinafter referred to as the reference area). In the test method in which the ratio of the reference area to the ground contact area (hereinafter referred to as area ratio) is in the above-described range, generation of BEL is promoted. According to this test method, BEL can be generated in a short time.

  In this test method, the cord of the inner layer 32 forming a part of the breaker 16 is configured to extend from the IN side to the OUT side and in the rotational direction in a state where the test rim 38 is mounted. The tire 2 may be used, or the tire 2 configured such that the cord of the inner layer 32 extends from the OUT side to the IN side and extends in the rotation direction may be used. From the standpoint of being effective in reproducing BEL, a tire 2 is used in which the cord of the inner layer 32 extends from the IN side to the OUT side and extends in the rotational direction when mounted on the rim 38. It is preferred that This is because when the tire 2 is configured so that the cord of the inner layer 32 extends from the OUT side to the IN side and extends in the rotational direction in a state where the outer layer 34 is attached to the rim 38. This is because stress concentrates at the edge and TLC is likely to occur in addition to BEL.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
Using the tire shown in FIG. 1 (tire size = 225 / 45ZR17), the test rim (rim size = 17-7.5J), and the test apparatus shown in FIG. 2 (drum diameter = 1.707 m), The test of Example 1 was conducted under the conditions shown in Table 1 below. In the breaker of the first embodiment, the inner layer cord extends from the IN side toward the OUT side and in the rotational direction.

In Example 1, "LOAD CAPACITY" is a standard load _{F S} in ETRTO standards. This standard load _{F S} was 6.58kN. "INFLATION PRESSURE" in the same standard is a standard internal pressure P _S. This standard internal pressure _{P S} was 290kPa. Since the speed symbol is “ZR”, the speed V _S represented by the speed symbol of this tire was 300 km / h.

  The time required from the start of the running process to the occurrence of damage to the tire and the type of damage that occurred were confirmed. When the breaker edge loose (BEL) was confirmed, the size of the BEL was also measured. The results are shown in Table 1 below. In this Example 1, the required time was 90 minutes. BEL was confirmed in the inner layer of the breaker. This is represented by “1st” in the table. The size of 1st BEL was 25 mm. In Example 1, no damage other than BEL was confirmed.

  Before the next step was started after the end of each step, the temperature of the bead portion was measured. In Example 1, since the measured temperatures were all less than 90 ° C., the cooling step was not performed. This is indicated by “N” in the cooling column in the table. The temperature of the bead portion at the end of the test was 80 ° C. This is described in the temperature column at the end.

[Example 2-17 and Comparative Example 1-29]
The tests of Example 2-17 and Comparative Example 1-29 were carried out in the same manner as in Example 1 except that the conditions shown in Tables 1 to 8 below were used. In Examples 3 and 4 and Comparative Examples 4 and 5, the temperature of the bead portion exceeded 90 ° C. at the end of the preliminary process. For this reason, the cooling step was performed before entering the first step. This is represented by “Y” in the cooling column of the preliminary process in the table. In Comparative Example 13, the preliminary process was not performed. Comparative Example 27 is a conventional test method.

[Comprehensive evaluation]
“+2” when BEL occurs, “−2” when BEL does not occur, “−1” when damage other than BEL occurs, “+2” when the required time is less than 120 minutes, The test results of each example were quantified as “0” when the required time was 120 minutes and “−2” when the required time exceeded 120 minutes. Thereby, each example was evaluated comprehensively. The results are shown in Tables 1 to 8 below. The larger this value, the better.

  As shown in Tables 1 to 8, the test method of the example has a higher evaluation than the test method of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The test method described above can be applied to various tires.

2 ... tyre 4 ... rim 6 ... tread 8 ... side wall 10 ... clinch 12 ... bead 14 ... carcass 16 ... belt 18 ... inner liner 20 ... -Cushion layer 22 ... Tread surface 24 ... Flange 26 ... Core 28 ... Apex 30 ... Carcass ply 32 ... Inner layer 34 ... Outer layer 36 ... Device 38 .... Rim 40 ... Supporting part 42 ... Drum 44 ... Rotating shaft 46 ... Running surface

Claims (2)

A test method for a tire, which is performed using a test apparatus including a support portion that supports a tire and a drum that rotationally drives the tire,
An adjustment step of adjusting the internal pressure P and the camber angle CA of the tire;
Contacting the tire with the running surface and applying a load F to the tire;
A running step of running the tire while gradually increasing the speed,
The temperature of the atmosphere in which the traveling process is performed is 20 ° C. or higher and 30 ° C. or lower,
This traveling process
A preliminary step of preliminarily driving the tire at a speed V _w,
A first step of running the tire at this speed V ₁ by increasing the speed V _w to the speed V _1,
A second step for running the tire at this speed V ₂ increased the speed V ₁ to velocity V _2,
While raising the 10 km / h by stepwise speed from the speed V ₂ contains a promoting step for running the tire,
The internal pressure P is 100% to 120% of the standard internal pressure of the tire,
The absolute value of the camber angle CA is 2 ° or more and 4 ° or less,
The load F is 60% or more and 90% or less of the standard load of the tire,
The speed _{V w} is not more than 90% 60% of the speed V1,
Running time t _w of the tire by the speed V _w is less than or equal to 10 minutes or more 5 minutes,
Travel time _{t 1} of the tire according to the speed _{V 1} is not more than 30 minutes than 10 minutes,
The difference between the speed _{V 2} and the speed _{V 1} is not more than 10 km / h or more 30 km / h,
Travel time _{t 2} of the tire according to the speed _{V 2} is less than 30 minutes 10 minutes,
In the promoting step, the travel time t _i of the tire by the speed which is increased stepwise is 10 minutes,
When the tire speed symbol is V range or higher, the tire speed V ₁ in the first step is set to 80% or more and 90% of the speed represented by the tire speed symbol,
When the speed symbol of the tire is less than H range, the velocity V ₁ of the said tire in the first step is set equal to the speed represented by the speed symbol of the tire, the method of test tires.   When the temperature of the bead portion of the tire exceeds 90 ° C. before the speed is increased in the traveling process, the bead portion is cooled before the speed is increased. The tire test method according to claim 1, further comprising a cooling step of setting the temperature to less than 90 ° C.

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