JP4561367B2 - Pneumatic tire testing method and testing apparatus - Google Patents

Description

The present invention relates to a test method and a test apparatus for a pneumatic tire, and more particularly, a pneumatic tire that can efficiently reproduce the occurrence of wire breakage and groove cracks in a tread belt layer that occurs in the market and can evaluate the durability of the tire. The present invention relates to a tire test method and a test apparatus.

  Conventionally, heavy-duty tires used in high-speed continuously traveling vehicles such as trucks and trailers have a problem that wire breaks and groove cracks in the tread belt layer are more likely to occur than other tires.

  This is because the belt layer has high bending rigidity in the tire width direction, and when a part of the tire tread rides on the step, the contact pressure on the upper road surface of the step is likely to be significantly higher than the lower road surface side. This is because large strain is generated at the groove bottom of the tread groove near the step. The tread may be grounded only on the upper road surface, and may not be grounded on the lower road surface, and may float in the air.

  In order to evaluate the durability of the tire against wire breakage or groove cracks in the belt layer of such a tread, the evaluation was performed by running a part of the tread of the tire mounted on the actual vehicle on a step. However, even if tires of the same specification are used, it is difficult to generate wire breaks and groove cracks that occur in the market. Also, depending on the skill of the test driver, etc. Due to the large variation, it was difficult to compare tires with different specifications. Furthermore, this method has a problem that it is necessary to evaluate a large number of tires in order to improve the evaluation accuracy, which is time consuming and expensive and is not efficient.

  As an evaluation device that reproduces cracks and chips generated in the thin ribs provided on the shoulder of a pneumatic tire, the test tire is run on the base in a circular path, and projections are placed on the circular path. And what makes a test tire get on is proposed (refer patent document 1).

However, this device is a device that only reproduces cracks and the like due to repeated curbstones and overhangs on the market, and because it has a structure in which the tire jumps when it rides on the protrusion, the wire of the belt layer generated in the market Folds and groove cracks could not be reproduced.
Japanese Utility Model Publication No. 7-36038

  An object of the present invention is to provide a test method and a test apparatus for a pneumatic tire that can efficiently reproduce the occurrence of wire breakage and groove cracks in a tread belt layer generated in the market and can evaluate the durability of the tire. .

  In order to achieve the above object, a test method for a pneumatic tire according to the present invention is a test road having an extended step, and the step is positioned within the tread width of a test tire that is assembled with a rim to have a predetermined internal pressure. It arrange | positions so that a predetermined load may be loaded, a tread may be grounded at least to the upper stage side road surface of the said test road, and it may roll in the extending direction of the said level | step difference.

  The pneumatic tire testing device of the present invention includes a tire holding device that holds a rim-assembled test tire in a rollable manner, and a test road having an extended step, and the tire holding device and the test At least one of the road is movable in the direction in which the tread of the test tire held by the tire holding device is brought into contact with the test road, the load can be applied in this direction, and the tire is moved in the tire width direction. The contact position of the test tire can be adjusted, and at least one of the tire holding device and the test road can be moved in the extending direction of the step.

  According to the test method for a pneumatic tire of the present invention, a test tire having a predetermined internal pressure by assembling a rim on a test road having an extended step is arranged so that the step is positioned within the tread width. Since the tread is grounded on at least the upper road surface of the test road under a predetermined load and rolled in the extending direction of the step, the ground pressure of the tread grounded on the upper road surface is lower than that of the lower road surface. Thus, a large strain is generated at the bottom of the tread groove located in the vicinity of the step, and a state in which a wire breakage or a groove crack in the belt layer is likely to occur can be constantly created.

  As a result, it is possible to efficiently reproduce the occurrence of wire breakage and groove cracks in the belt layer generated in the market.

  In addition, since the degree of wire breakage and groove cracks that have occurred can be ascertained, it is possible to perform comparative evaluation on wire breakage and groove cracks in a belt layer of a tire having different specifications, and the durability of the tire can be evaluated.

  According to the pneumatic tire testing device of the present invention, the tire holding device includes a tire holding device that holds the rim-assembled test tire in a rollable manner, and a test road having an extended step, the tire holding device and the test road, At least one of the tires can be moved in the direction in which the tread of the test tire held by the tire holding device is brought into contact with the test road, so that a load can be applied in this direction, and the test tire is grounded by moving in the tire width direction. Since the position can be adjusted, the tread of the test tire is placed at a predetermined position, grounded to at least the upper road surface of the test road, loaded with a predetermined load, and the bottom of the tread groove located near the step In this portion, a state in which wire breakage or groove cracking of the belt layer is likely to occur can be constantly created.

  Furthermore, since at least one of the tire holding device and the test road can be moved in the extending direction of the step, the test tire can be rolled in the extending direction of the step while being grounded on the test road.

  This structure makes it possible to carry out the test methods described above, efficiently reproduce the occurrence of broken wire and groove cracks in the belt layer on the market, and enable comparative evaluation of tires with different specifications, and evaluate tire durability. it can.

Hereinafter, a test method and a test apparatus for a pneumatic tire according to the present invention will be described based on the embodiments shown in the drawings. FIG. 5 illustrates a general outline of the test apparatus in a front view. In this figure, the test tire 1 is a rib pattern having ribs 1a and circumferential grooves 1b, and the symbol D indicates the tread groove depth. The test apparatus includes a tire holding device 6 and a test path 2 described below.

  The tire holding device 5 has a structure in which the test tire 1 having a predetermined internal pressure mounted on the rim 10 can be attached to the holding arm 7 so as to be able to roll. The holding arm 7 is attached to a support column 8 erected on the base 9 so as to be movable in the vertical direction, and has a structure that can be fixed at a predetermined height. The holding arm 7 is movable in the longitudinal direction of the arm, and by moving in the longitudinal direction, the contact position of the test tire 1 with respect to the test path 2 can be easily changed and arranged.

  A test road 2 is arranged below the test tire 1 attached to the holding arm 6, and has a flat upper stage road surface 4 and a lower stage side road surface 3, and a step 5 extends linearly. . The test path 2 has a cylindrical body whose outer peripheral surface is the test path 2 and is a kind of so-called drum testing machine. In FIG. 5, the symbol H indicates the height of the step. The upper stage road surface 4 is detachable, and the upper stage side road surface 4 having a step height H selected according to the test condition is mounted and fixed on the surface of the lower stage side road surface 3 so that the step height H can be changed. It has become.

  In carrying out the test, first, the test tire 1 and the test road 2 are set. The test tire 1 is positioned so as to be within the tread width when the step 5 of the test road 2 contacts the ground. Thereafter, the support pillar 8 is moved downward, the test tire 1 is grounded at least on the upper stage road surface 4, and the movement is stopped at a position where a predetermined load is applied, so that the height position of the test tire 1 is fixed. The load applied to the test tire 1 can be given by fixing the support column 8 and raising the test path 2, and at least one of the support column 8 and the test path 2 moves in a direction close to each other. What is necessary is just to give load.

  The test method of the present invention will be described with reference to FIGS. FIG. 1 shows a state in which the test tire 1 is held by the tire holding device 6 and the setting is completed in a plane direction. FIG. 2 shows an enlarged view of the ground contact state of the test tire 1 in FIG. 1 in the front direction. As shown in the figure, the tread of the test tire 1 is in a state where it is grounded only on the upper road surface 4 of the test road 2 and is not grounded on the lower road surface 3, and the upper road surface 4 is Only one end 1c of the tread in the tire width direction is grounded.

  In this state, the drum-shaped test path 2 is rotated by a drive motor (not shown) to roll the test tire 1 in the extending direction of the step 5.

  As shown in FIG. 2, the contact pressure of the tread that contacts the upper road surface 4 is significantly higher than that of the lower road surface 3, and the groove of the circumferential groove 1b located closest to the step 5 in the tire width direction. A large strain is generated at the bottom, and a state in which wire breakage and groove cracks of the belt layer are likely to occur can be created at this portion.

  For example, a standard maximum load is applied to the test tire 1 having five ribs 1a on the tread, and only one rib 1a serving as one end portion 1c of the tread is grounded on the upper stage road surface 4 so that the lower stage road surface 3 In this state, the grounded single rib 1a is loaded with a load five times the standard maximum load, and a large strain is generated at the groove bottom of the circumferential groove 1b adjacent to the rib 1a. be able to.

  As described above, according to the test method and test apparatus of the present invention, it is possible to constantly create a state in which the wire breakage or groove crack of the belt layer is likely to occur, and the wire breakage or groove of the belt layer generated in the market. It is possible to efficiently reproduce the occurrence of cracks. And the extent which generate | occur | produced can be grasped | ascertained.

  In this embodiment, the tire holding device 6 is fixed, and the test path 2 is rotated in a drum shape to move the test path 2 in the extending direction of the step 5, but the flat test path 2 is It may be fixed and the tire holding device 6 may be moved in the extending direction of the step 5.

  In this embodiment, the tread of the test tire 1 is grounded only on the upper road surface 4 of the test road 2 to generate a larger strain. However, the present invention is not limited to this. You may make it earth | ground.

  Further, only one end portion of the tread is grounded on the upper stage road surface 4 so as to generate a larger distortion. However, the present invention is not limited to this, and about half or more in the width direction of the tread or more is provided on the upper stage road surface 4. These conditions may be determined as appropriate according to the severity of the test conditions and the tread position to be evaluated.

  When the height of the step 5 on the test road 2 is 50% or more of the groove depth of the tread groove located closest to the step 5 in the tire width direction when the test tire 1 is brought into contact with the test road 2, Generation of wire breakage and groove cracks in the belt layer can be further promoted, and the test time can be greatly shortened.

  The height of the step 5 is not less than the height of the test tire 1 when the tread of the test tire 1 is in contact with only the upper stage road surface 4 and is not in contact with the lower stage road surface 3 with a predetermined load applied. However, the test condition does not become severe depending on the height of the step 5.

  The number of steps 5 in the test path 2 is not limited to one, and may be plural as illustrated in FIG. 3, thereby enabling evaluation of a plurality of locations at the same time.

  In addition, the cross-sectional shape in the width direction of the step 5 is not limited to a shape in which the upper-side road surface 4 is horizontal and rectangular, but the shape in which the upper-side road surface 4 shown in FIG. Various other shapes can be employed depending on the test conditions, such as a shape in which the upper-stage road surface 4 is inclined as shown in FIG. 4B and a shape in which the upper-stage road surface 4 is protruded in a mountain shape as shown in FIG.

  The step 5 is not limited to a constant height in the extending direction, and may have a shape whose height changes continuously, and does not jump when the test tire 1 rolls. Shape can be adopted. The extended length is not limited to the one having no cut at all, and the cut length may be provided as long as it is shorter than the contact length of the test tire 1.

  The test road 2 can be tested by providing an inclined surface inclined in the tire width direction instead of the step 5, and the test tire 1 is grounded on the surface of a so-called wobbling drum whose longitudinal cross-sectional shape is a parallelogram. You may test by rolling in a state.

  Drum test with an outer diameter of 1707 mm, with a tire size of 11R22.5 14PR (standard maximum load 26.7 kN, standard maximum air pressure 700 kPa) and a rib pattern pneumatic tire with a groove depth D15 mm and a step on the drum surface The common condition is that only one rib at one end of the tread is grounded to the upper road surface of the step, the load load is the standard maximum load, the air pressure is the standard maximum air pressure, and the traveling speed is 45 km / h. And changing only the height H of the step and changing the value of H / D to four ways (Examples 1 to 4) as shown in Table 1, changing the ground contact state on the lower road surface of the tread, The travel distance until the wire breakage of the belt layer occurred was measured. In this measurement, the presence or absence of wire breakage was confirmed by X-ray inspection every 2,000 km traveling, and the results are shown in Table 1.

  In the test tire of the same specification, in the actual vehicle running test in the market, wire breakage of the belt layer at the tread end occurs at the time of running 80,000 km (comparative example).

In all of Examples 1 to 4, the wire breakage of the belt layer at the end of the tread can be reproduced. In the range of the step height tested, the condition becomes severer as the step height increases, and the wire breakage occurs. It was confirmed that the mileage could be shortened. In particular, in Examples 2 to 4, it was confirmed that the mileage could be significantly shortened compared to actual vehicle running tests in the market, and that wire breakage that occurred in the market could be efficiently reproduced to save time and cost. did it.
In the first embodiment, the travel distance is longer than that of the actual vehicle running test, but it is possible to reproduce wire breakage in the indoor test, and it is possible to continuously run unattended. Therefore, the test time and cost can be reduced compared to the actual vehicle running test. Is possible and efficient.

It is a top view which illustrates the state which is implementing the test method of the present invention. It is a front enlarged view which shows the grounding state of the test tire in FIG. It is a front view which shows another example of the test path which concerns on this invention. It is width direction sectional drawing which shows another example of the shape of the level | step difference of the test path which concerns on this invention. It is a front view which illustrates the test device of the present invention.

Explanation of symbols

1 Test Tire 1a Rib 1b Circumferential Groove 1c One End of Tread 2 Test Path
3 Lower road surface 4 Upper road surface 5 Step 6 Tire holding device 7 Holding arm 8 Support column 9 Base 10 Rim D Tread groove depth H Step height

Claims (6)

  A test road having an extended step and a rim assembled to a predetermined internal pressure is placed so that the step is positioned within the tread width, and a predetermined load is applied to test the tread. A test method for a pneumatic tire, which is brought into contact with at least an upper road surface of a road and rolls in the extending direction of the step.   The method for testing a pneumatic tire according to claim 1, wherein the height of the step is 50% or more of the groove depth of the tread groove located closest to the step in the tire width direction.   The test method for a pneumatic tire according to claim 1 or 2, wherein the tread of the test tire is grounded only on an upper road surface of the test road.   The method for testing a pneumatic tire according to any one of claims 1 to 3, wherein only one end portion in the tire width direction of the tread of the test tire is grounded on an upper stage side surface of the test road.   A tire holding device that holds a test tire assembled with a rim in a rollable manner and a test road having an extended step, and the tire holding device holds at least one of the tire holding device and the test road. The test tire tread can be moved in the direction in which the tread is brought into contact with the test road so that a load can be applied in the direction, and the test tire can be moved in the tire width direction to adjust the contact position of the test tire. A test apparatus for a pneumatic tire, wherein at least one of the apparatus and the test road is movable in an extending direction of the step. The pneumatic tire testing device according to claim 5, wherein the height of the step can be changed.

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