JP5918035B2 - Tire durability test method and test apparatus - Google Patents

Description

  The present invention relates to a tire durability test method and a test apparatus. More specifically, the present invention relates to a tire durability test method for running a tire and a tire testing apparatus in order to evaluate the durability of the tire.

  As a method for evaluating the durability of a heavy duty tire, a bench test in which the tire is driven by a driving drum is employed. The endurance test on the tire bead is performed, for example, in a state where a load higher than the maximum load specified by JATMA is applied. In this test, the durability of the test tire is evaluated based on the running time until the bead is damaged.

  On the other hand, in recent heavy-duty tires, the durability of the beads is improved. Therefore, in the above test method, the durability evaluation time is prolonged. In order to solve such a problem, Japanese Patent Application Laid-Open No. 2009-29180 proposes a test method in which a bead of a test tire is run in a state where the temperature is raised under a certain condition. By increasing the temperature of the bead, it aims to promote the deterioration of the bead during the test.

  In this test method, a test rim equipped with a heater is used. This heater is fixed to the bead seat surface of the rim. As this heater, a film-like heating element is employed. A temperature sensor is attached to the heater itself. A control unit is provided for adjusting the heat generation power supplied to the heater so that the temperature detected by the temperature sensor becomes a predetermined value.

  However, the heater is fixed to the bead seat surface of the rim. For this reason, the position of the heater relative to the test tire cannot be adjusted. The heated part of the tire cannot be adjusted to accommodate the test purpose. The lead wire for the heater passes from between the bead of the tire and the bead seat surface of the rim from the heater, or is guided to the outside through a through hole formed in the bead seat portion of the rim. The lead wire for the temperature sensor is also led from the temperature sensor to the outside through the same route as the lead wire. Therefore, there is a risk of tire air leakage along the wiring. There is also a risk that the lead wire will break when assembling the rim. In JP 2009-29180 A, a combined rim is proposed in order to avoid the air leakage. In this case, it is necessary to manufacture a special rim, and a commercially available rim cannot be adopted.

JP 2009-29180 A

  The present invention has been made in view of the present situation, and is capable of adjusting a heated portion of a tire so as to be adapted to a test purpose, and can easily assemble a rim, and tire durability. The purpose is to provide a test method.

The tire testing apparatus according to the present invention includes:
A rim support device that rotatably supports a test rim on which a test tire is mounted;
A driving drum for rotating the test tire;
A heater,
A heater support device for supporting the heater in a state independent of the rotating rim and the tire, and a temperature sensor attached to the rim from the outside;
The heater support device is configured to be able to adjust the position of the heater.

  Preferably, the heater position adjustment direction by the heater support device has at least a radial component and an axial component of the test tire.

  Preferably, the test apparatus includes a temperature control device that adjusts the heat generation level of the heater based on the temperature detected by the temperature sensor so that the detected temperature falls within a predetermined range.

  Preferably, a plurality of the temperature sensors are attached at intervals in the radial direction of the rim, and the temperature control device is configured to switch the temperature sensors to be temperature controlled. Note that the phrase “with an interval in the radial direction” is not intended to be limited to being attached along a virtual line in the radial direction. As long as it is spaced in the radial direction, it may be spaced in the circumferential direction.

  Preferably, the predetermined range of the detection temperature is 100 ° C. or more and 150 ° or less.

  Preferably, the detection end of the temperature sensor is attached in a state of being inserted into a recess formed in the outer peripheral surface of the rim.

The tire durability test method according to the present invention includes:
A test method in which a test tire is rotated,
A running step of rotating the test tire assembled with the rim;
A heating step of heating a heating target part of the rim corresponding to the test target part in the rotating test tire with a heater,
The heater is installed in an independent state from the rotating rim and tire, and the position of the heater can be adjusted so as to correspond to the heating target portion.

  Preferably, in the heating step, the temperature of the heating target part is controlled to be within a predetermined range.

  Preferably, the predetermined range of the temperature is 100 ° C. or more and 150 ° or less.

  According to the tire durability test method and test apparatus according to the present invention, it is possible to adjust the heated part of the tire, so that it is possible to reproduce the damaged part of the tire in the market, the damage form, and the like.

FIG. 1 is a front view schematically showing an example of a test apparatus used for executing a tire durability test method according to an embodiment of the present invention. FIG. 2 is a front view showing an example of a heating mechanism of the test tire in the test apparatus of FIG. 1 together with the test tire. FIG. 3 is a side view taken along line III-III showing an example of the arrangement of the heaters in the heating mechanism of FIG. FIG. 4 is an enlarged partial cross-sectional view showing a portion IV in FIG.

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

  FIG. 1 schematically shows a test apparatus 1 used for execution of a tire durability test method according to this embodiment. FIG. 2 shows a heating mechanism 2 of a test tire (hereinafter also simply referred to as a tire) 10 in the test apparatus 1. The test apparatus 1 includes a test rim 11 on which a tire 10 is mounted, a rim support device 3 that rotatably supports the rim 11, and a drive drum 4 that rotationally drives the test tire 10. . The drive drum 4 is rotated by an electric motor (not shown). The drive drum 4 can be rotated and can be decelerated and stopped by its own brake mechanism.

  The rim 11 is rotatably supported by the rotation shaft 5 of the rim support device 3. The rotating shaft 5 is rotated by an electric motor (not shown). Therefore, the tire 10 can be rotated without using the drive drum 4. The rim support device 3 can make the rotating shaft 5 freely rotatable and can be restrained (brake applied). Thereby, the tire 10 can be decelerated and stopped. The rim support device 3 can separate and approach the tire 10 with respect to the drive drum 4. The tire 10 attached to the rim 11 is pressed by the drive drum 4 under a predetermined load. The tire 10 is rotationally driven by the drive drum 4 in this state.

  The heating mechanism 2 shown in FIG. 2 includes a heater 6, a heater support device 7, a temperature sensor 8, and a temperature control device 9 that controls the heating temperature. The heater support device 7 is attached to a non-rotating main body portion (rim support main body) 13 of the rim support device 3. The rim support body 13 is attached to a gantry (not shown) of the test apparatus 1. An electric motor that rotationally drives the rotary shaft 5 of the rim support device 3 may be accommodated inside the rim support body 13. A slip ring 14 is attached to the rotating shaft 5. In FIG. 2, the rim support device 3 and its rotation shaft 5 can rotate about its own axis, but the rim support body 13 and the slip ring 14 are not rotated.

  As shown in FIG. 3, a plurality of heaters 6 are used. In the present embodiment, seven heaters 6 are employed, but the number is not limited to seven. A single heater may be attached. The shape of the heater is not limited to that shown in FIG. For example, an annular heater may be used. In the present embodiment, as the heater, a far-infrared heater (such as an Infrastein heater) widely used in the field of low / medium temperature heating is used. Each heater 6 is connected to the rim support body 13 by a heater support arm 15. As will be described later, the heater support arm 15 allows the position of each heater 6 to be adjusted with respect to the tire 10 and the rim 11. The plurality of heaters 6 are arranged substantially concentrically with the rim 11 to be heated. Even when the tire 10 and the rim 11 are rotating, since the heater 6 is fixed, the heating target portion of the rim 11 including the rim flange 12 is heated uniformly in the circumferential direction.

  As described above, the heater support arm 15 can adjust the position of each heater 6 with respect to the tire 10 and the rim 11. The direction of adjusting the position of the heater 6 has at least a radial component and an axial component of the tire 10 and the rim 11.

  As shown in FIG. 4, the heater support arm 15 includes a sliding arm portion 16 to which the heater 6 is attached, and a swing arm portion 17 that is swingably attached to the rim support body 13 side. Yes.

  The sliding arm portion 16 and the swing arm portion 17 are connected to each other in a partially overlapping state. The sliding arm portion 16 is slidable with respect to the swing arm portion 17 in an adjustment direction (arrow A in the figure) including the radial direction component and the axial direction component of the rim 11. A guide (not shown) is formed so that the sliding arm portion 16 can slide in the adjusting direction. A long hole 18 is formed in one of the sliding arm 16 and the swinging arm 17 along the sliding direction. The sliding arm portion 16 is fixed to the swing arm portion 17 at an arbitrary position by the bolt 19 and the nut 20 inserted through the long hole 18. As a result, each heater 6 can be adjusted to any position in the direction in which the radial direction and the axial direction are combined with respect to the rim 11.

  The swing arm portion 17 is attached to the rim support main body 13 with bolts 21 so that the tip side of the swing arm portion 17 can be separated and approached to the rim 11. When the bolt 21 is loosened, the swing arm portion 17 can swing in the direction in which the swing arm portion 17 moves away from the rim 11 (arrow B in the figure). In this way, the swing arm portion 17 can be adjusted and fixed at an arbitrary inclined position with respect to the rim support body 13 by the bolt 21. As a result, each heater 6 can be adjusted to a position at an arbitrary distance from the rim 11.

  With the above-described position adjustment mechanism, the heater 6 can sufficiently cover the range of the region to be heated from the radially outer end of the rim flange 12 to the radially inner end of the bead seat portion 22 of the rim 11. In addition, this position adjustment mechanism can easily cope with changes in the size of the test tire and the size of the rim. The heating target parts in the present embodiment correspond to the parts of the beads 23 that are highly likely to cause various bead damages. An example of the structure of the bead 23 of the tire 10 will be described below before the description of the portion to be heated.

  The bead 23 includes a core 24, an apex 25 that extends radially outward from the core 24, and a packing rubber 26 that extends radially outward from the apex 25. The core 24 has a ring shape. The core 24 includes a plurality of non-stretchable wires (typically steel wires). The apex 25 is tapered outward in the radial direction. The apex 25 is made of a highly hard crosslinked rubber. The packing rubber 26 is tapered outward in the radial direction. The packing rubber 26 is soft. The packing rubber 26 relieves stress concentration at the end of the folded portion 27 a of the carcass ply 27.

  The reinforcing layer (filler) 28 is wound around the core 42. The reinforcing layer 28 is laminated on the carcass ply 27. The reinforcing layer 28 includes a large number of cords arranged in parallel and a topping rubber. Each cord is made of steel. This reinforcing layer 28 is also called a steel filler. The reinforcing layer 28 contributes to the durability of the tire 2. The cover rubber 29 is located outside the packing rubber 26 in the axial direction. The cover rubber 29 is laminated on the carcass ply 27. An end portion (PE in FIG. 4) of the folded portion 27 a of the carcass ply 27 is covered with a cover rubber 29. The cover rubber 29 reduces the stress concentration on the end of the folded portion 27a of the carcass ply 27. One end of the reinforcing layer 28 is also covered with a cover rubber 29. The cover rubber 29 relieves stress concentration at one end.

  Below, the heating object site | part in the said bead 23 is illustrated. The assumed damage form and the site where this damage is likely to occur are shown in correspondence. This part is a part to be heated. In addition, what is actually heated by the heater 6 is a rim portion corresponding to the heating target portion. This is also called a “heating target part”.

  As one of the heating target portions, an end portion (also referred to as a ply edge) PE of the folded portion 27a of the carcass ply 27 can be cited. In the vicinity of the ply edge PE, destruction is likely to occur depending on conditions. This damage is also called PTL (Ply Turn Up Looseness). As a second part to be heated, an end portion (also referred to as a filler edge) FE of the reinforcing layer 28 is cited. In the vicinity of the filler edge FE, cracks are likely to occur at the winding end 28 of the filler 28 depending on conditions. This damage is also called FEL (Filler Edge Looseness). As a third heating target part, there is a part (bead seat part) BS where the bead 23 and the rim flange 12 are in contact with each other and air-sealed. In this bead sheet portion BS, the folded portion 27a of the carcass ply 27 may come off from the core 24 of the bead 23 depending on conditions, and a burst may be generated from the bead 23 portion. This damage is also called a blow-through.

  The ply edge PE, filler edge FE, and bead sheet portion BS are all continuously present in the circumferential direction. With respect to the rim 11 and the tire 10 that rotate together, any of the above-mentioned parts PE, FE, and BS are uniformly heated without leakage by the fixed heater 6.

  The temperature sensor 8 is attached from the outside of the rim in order to detect the temperature of the heating target portion of the rim 11. The temperature sensor 8 is attached to a plurality of locations at intervals in the radial direction of the rim 11. Of course, the mounting positions of the plurality of sensors 8 do not have to be arranged on the same virtual straight line in the radial direction. It may be at the position. The mounting position of the temperature sensor 8 is a portion on the rim 11 where the heater 6 can irradiate far infrared rays, and a portion on the rim 6 corresponding to a portion where a damage form assumed on the bead 23 may occur. . The example of the damaged form and the site where this damage can occur are as described above. That is, PTL at the ply edge PE, FEL at the filler edge FE, and blow-by at the bead sheet portion BS.

  A thermocouple can be adopted as the temperature sensor 8. Sensors other than thermocouples can also be employed. The detection end of the temperature sensor 8 is inserted into a small recess (mounting hole) 30 formed on the outer peripheral surface of the rim 11. The detection end is fixed with resin or the like in a state of being inserted into the mounting hole 30. The temperature sensor 8 may be fixed to the outer surface of the rim 11. Among the plurality of temperature sensors 8, a sensor 8 at a position corresponding to the heating target portion is appropriately selected and becomes a control target. In this case, the “heating target portion” is a portion (a portion corresponding to PE, FE, BS) that is likely to generate a damage form to be reproduced in the test.

  As shown in FIG. 2, the lead wire 31 that connects the temperature sensor 8 and the temperature control device 9 is wired from the temperature sensor 8 to the terminal 32 that is fixed to the outer surface of the rim through the outside of the rim 11. From the non-rotating portion of the snap ring 14 to the temperature control device 9. A lead wire (not shown) that connects the heater 6 and the temperature control device 9 is also wired from the heater 6 to the temperature control device 9 through the outside of the rim 11. Therefore, there is no possibility that the lead wire 31 causes air leakage of the tire 10.

  In the present embodiment, three temperature sensors 8 are used, but the number is not limited. The number of temperature sensors 8 may be determined according to a location where an assumed damage form is likely to occur. A single temperature sensor may be used. This single temperature sensor may be fixed to one location of the rim 11. This single temperature sensor may be capable of being attached and changed at a predetermined plurality of locations or at a plurality of arbitrary locations. That is, it may be possible to adjust the mounting position of a single temperature sensor.

  The heater 6 is aligned with a predetermined heating target part (part corresponding to the PE, FE, BS). In the temperature control device 9, one of the temperature sensors 8 attached to the predetermined heating target portion is selected as a control target among the plurality of temperature sensors 8. The temperature control device 9 adjusts the amount of heat generated supplied to the heater 6 so that the temperature detected by the temperature sensor 8 to be controlled falls within a predetermined temperature range.

  The said predetermined temperature range shall be 100 degreeC or more and 150 degrees C or less. If it is less than 100 degreeC, generation | occurrence | production of any damage will become difficult. Further, the effect of shortening the generation of PTL and FEL is reduced. On the other hand, if the temperature exceeds 150 ° C., the occurrence time of any damage is advanced. As a result, the difference in the durability performance of the tire becomes small, and the performance evaluation becomes difficult.

  From the above viewpoint, even within the above-described range of 100 ° C. or more and 150 ° C. or less, temperature ranges suitable for the blow-through of the bead sheet portion, PTL and FEL are set. 120 ° C. or higher and 150 ° C. or lower is preferable for blow-through of the bead sheet portion. For PTL and FEL, both 100 ° C. and 120 ° C. are preferable. The temperature range corresponding to the damage form to be reproduced is set in the temperature control device 9. The appropriate set temperature range described above is a temperature range in which the target damage form can be reproduced while shortening the evaluation time, and can be grasped by a preliminary experiment. In this preliminary experiment, the temperature of the part to be heated is variously changed and set, and the relationship between the temperature, the form of damage at the part, and the time until the damage occurs is grasped.

  In the durability test, the test tire 10 is mounted on the rim support device 3. The tire 10 is pressed against the drive drum 4 by the rim support device 3. The heater 6 is aligned with the corresponding position of the damage form to be reproduced on the rim 11. Among the plurality of temperature sensors 8, the sensor 8 installed at the target damage form corresponding position is set as an object to be controlled by the temperature control device 9. The tire 10 is rotated by driving the driving drum 4. The heater 6 is activated. The temperature control device 9 performs on / off control, for example, so that the detected temperature of the temperature sensor 8 to be controlled falls within a range of 100 ° C. or more and 150 ° C. or less. The time from when the detected temperature reaches the predetermined temperature range until the occurrence of damage is measured and recorded. The durability of the tire 10 is evaluated by the length of this time. By this test method using the apparatus 1, it was possible to confirm the occurrence of the target damage form in a short time (range from about 70 hours to 160 hours). This time is about 1/5 to 1/4 when the test tire is not heated.

  In FIGS. 1 and 2, the heater 6 and the temperature sensor 8 are provided only on one side surface of the tire 10 and the rim 11 in the axial direction, but may be provided on both side surfaces. Further, in the embodiment of the test method described above, an example in which only the rim 11 corresponding to the bead 23 is heated and only the temperature of the rim 11 is detected has been described, but the present invention is not limited thereto. The tire portion radially outward from the rim flange 12 may be directly heated, and the temperature of this portion may be detected.

  The tire durability test method and test apparatus according to the present invention are particularly suitable for evaluating the durability of tire beads.

DESCRIPTION OF SYMBOLS 1 ... Test apparatus 2 ... Heating mechanism 3 ... Rim support apparatus 4 ... Drive drum 5 ... Rotating shaft (of support apparatus) 6 ... Heater 7 ... Heater support apparatus 8. ..Temperature sensor 9 ... Temperature control device 10 ... (Test sample) Tire 11 ... Rim 12 ... Rim flange 13 ... Rim support body 14 ... Slip ring 15 ... Heater support Arm 16 ... Sliding arm portion 17 ... Oscillating arm portion 18 ... Long hole 19, 21 ... Bolt 20 ... Nut 22 ... Bead seat portion 23 ... Bead 24 ... -Core 25 ... Apex 26 ... Packing rubber 27 ... Carcass ply 28 ... Reinforcement layer 29 ... Cover rubber 30 ... Mounting hole 31 ... Lead wire 32 ... Terminal BS ... Bead seat part FE Filler Edge PE · · · ply edge

Claims (9)

A rim support device that rotatably supports a test rim on which a test tire is mounted;
A driving drum for rotating the test tire;
A heater,
A heater support device for supporting the heater in a state independent of the rotating rim and the tire, and a temperature sensor attached to the rim from the outside;
A tire testing apparatus in which the heater support device is configured to be able to adjust the position of the heater.   The tire testing device according to claim 1, wherein the heater position adjustment direction of the heater includes at least a radial component and an axial component of the test tire.   The tire testing device according to claim 1, further comprising a temperature control device that adjusts a heat generation level of the heater based on a temperature detected by the temperature sensor so that the detected temperature falls within a predetermined range.   The tire according to claim 3, wherein a plurality of the temperature sensors are attached at intervals in the radial direction of the rim, and the temperature control device is configured to switch a temperature sensor to be temperature controlled. Test equipment. The tire testing apparatus according to claim 3 or 4, wherein the predetermined range of the detected temperature is 100 ° C or higher and 150 ° C or lower.   The tire testing device according to any one of claims 1 to 5, wherein the detection end of the temperature sensor is attached in a state of being inserted into a recess formed on the outer peripheral surface of the rim. A tire durability test method that is performed by rotating a test tire,
A running step of rotating the test tire assembled with the rim;
A heating step of heating a heating target part of the rim corresponding to the test target part in the rotating test tire with a heater,
A tire durability test method in which the heater is installed in a state independent of the rotating rim and the tire, and the position of the heater can be adjusted so as to correspond to the portion to be heated.   The tire durability test method according to claim 7, wherein, in the heating step, the temperature of the part to be heated is controlled to be within a predetermined range. The tire durability test method according to claim 8, wherein the predetermined range of the temperature is 100 ° C. or higher and 150 ° C. or lower.

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