JP6766615B2 - Manufacturing method of core member - Google Patents

Description

The present invention relates to a method for manufacturing a tire core member. More specifically, the present invention relates to a method for manufacturing a core member obtained by winding a bead wire.

The tire has a core to fit on the rim. Generally, the core is formed from a core member around which a bead wire is wound. As such a core member, a member whose bottom surface is inclined with respect to the axial direction may be used. In a core member with an inclined bottom surface, the bead wire to be wound is likely to be unwound.

For example, Japanese Patent Application Laid-Open No. 2013-78902, Japanese Patent Application Laid-Open No. 2014-83768, and Japanese Patent Application Laid-Open No. 2015-196243 disclose a method for molding a core member. In these molding methods, unwinding of the core member having an inclined bottom surface can be reduced.

JP 2013-78902 JP-A-2014-83768 JP 2015-196243

The tilt angle of the bottom surface of the core member depends on the tire specifications. In particular, a core member having a large inclination angle of the bottom surface is liable to collapse. It is not easy to reduce the unwinding while supporting the molding of various core members having different inclination angles of the bottom surface.

An object of the present invention is to provide a method for manufacturing a core member capable of suppressing unwinding.

The method for manufacturing a tire core member according to the present invention is a method for manufacturing a core member whose bottom surface is inclined with respect to the axial direction. This method includes an ascending winding process in which the bead wire is wound so as to be inclined from the inside to the outside in the radial direction from one axial direction to the other, and an inward winding process in which the bead wire is inclined from the outside to the inward in the radial direction from the other in the axial direction. It is provided with a down winding step in which the bead wire is wound. The downward tension applied to the bead wire in the down winding step is smaller than the up tension applied to the bead wire in the up winding step.

Preferably, the downward pressing force with which the tension roller is pressed against the bead wire in the downward winding step is smaller than the upward pressing force with which the tension roller is pressed against the bead wire in the upward winding step.

Preferably, the inclination angle θ of the bottom surface of the core member with respect to the axial direction is 18 degrees or more.

The method for manufacturing a tire according to the present invention includes a core member forming step of forming a core member, a preforming step of combining members forming each part including the core member to form a low cover, and vulcanization of the low cover. It is equipped with a vulcanization process to obtain tires.
In the core member forming step, the bottom surface of the core member is formed so as to be inclined with respect to the axial direction. The core member forming step includes an ascending winding step in which the bead wire is wound so as to be inclined from the inner side to the outer side in the radial direction from one axial direction to the other, and the outer side to the inner side in the radial direction from the other axial direction. It is provided with a down winding step in which the bead wire is wound so as to be inclined in a direction. The downward tension applied to the bead wire in the down winding step is smaller than the up tension applied to the bead wire in the up winding step.

The core member manufacturing apparatus according to the present invention includes a disk-shaped bead former having a groove on its outer circumference, a feeder for supplying the bead wire wound in the groove, and a bead wire wound in the groove. It is equipped with a tension applying machine that applies tension. The bottom surface of the groove extends from one axial direction to the other in a radial direction from the inside to the outside. The feeder has a function of moving the position for supplying the bead wire in the axial direction when the bead wire is wound around the groove. In the tension applying machine, the tension when the position where the bead wire is supplied moves from one axial direction to the other, and the tension when the position where the bead wire is supplied moves from the other axial direction to one side. It has a function to make it larger.

In the method for manufacturing a core member according to the present invention, the downward tension is smaller than the upward tension when the bead wire is wound. In the down winding process, the bead wire is easily wound in a predetermined winding position. In this method, the arrangement of the bead wire windings is suppressed from being disturbed. This method can suppress the unwinding of the core member.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire manufactured by the manufacturing method according to the present invention. FIG. 2 is a conceptual diagram of a core member manufacturing apparatus used in the manufacturing method according to the present invention. FIG. 3 is an explanatory diagram of a bead former of the manufacturing apparatus of FIG. FIG. 4 is a cross-sectional view showing a core member wound around the beadformer of FIG. 3 together with a part of the beadformer. 5 (a) is an explanatory view of the core member winding process by the bead former of FIG. 3, and FIG. 5 (b) is another explanatory view of the core member winding process of FIG. 5 (c). Is still another explanatory view of the winding process of this core member.

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

FIG. 1 shows a part of a tire 2 manufactured by the manufacturing method according to the present invention. In FIG. 1, the vertical direction is the radial direction of the tire 2, the left-right 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. This tire 2 is a pneumatic tire. This tire 2 is a tubeless type. The tire 2 is mounted on a truck, a bus, or the like.

The tire 2 includes a bead 4, a sidewall 6, a clinch 8, a carcass 10, an inner liner 12, and a filler 14. The bead 4 includes a core 16, a first apex 18, and a second apex 20. The core 16 is ring-shaped and includes a wound bead wire 22. The bead wire 22 includes a non-stretchable wire. In the core 16, the bead wire 22 is spirally wound.

The straight line Lα in FIG. 1 is a straight line extending along the bottom surface 16a of the core 16. The straight line L1 represents a straight line extending in the axial direction. The double-headed arrow α represents the angle at which the straight line Lα and the straight line L1 intersect. This angle α is referred to as the inclination angle of the core 16. A plurality of cross sections 24 of the wound bead wire 22 are arranged along the straight line Lα. A plurality of rows in which the cross sections 24 are arranged are stacked. The rows of the cross sections 24 are inclined at an inclination angle α. This inclination angle α is usually set to 15 ° or more for tubeless type heavy-duty tires. In this tire 2, the inclination angle α is 20 °.

The manufacturing method of the tire 2 includes a preforming step and a vulcanization step. This preforming step includes a core member forming step of forming the core member 25 (see FIG. 4). This preforming step involves forming each member forming each part of the tire, such as the core member 25, the first apex member, the second apex member, the sidewall member, the clinch member, the carcass member, and the inner liner member. I have. In the preforming step, each of these members is combined to form a low cover. In the vulcanization step, the low cover is pressurized and heated in the mold. Through this vulcanization step, the tire 2 is obtained from the low cover.

FIG. 2 shows a manufacturing apparatus 26 for the core member 25 used in the core member forming step. The manufacturing device 26 includes a reel 28, a storage device 30, a heater 32, an extruder 34 as a coating device, a tension applying machine 36, a feeder 38, and a bead former 40. The manufacturing device 26 includes a control device (not shown). This control device has a function of controlling the reel 28, the storage device 30, the heater 32, the extruder 34, the tension applying machine 36, the feeder 38, and the bead former 40.

The wire body 42 is wound around the reel 16. A typical material for the wire body 42 is steel. In this manufacturing apparatus 26, the outer peripheral surface of the wire body 42 is coated with the rubber composition to form the bead wire 22. The method for manufacturing the core member 25 includes a feeding step, a preheating step, a coating step, and a winding step.

The reel 28 of FIG. 2 is rotated around its axis by a rotation axis in the feeding process. The wire body 42 is unwound from the reel 28. The unwound wire body 42 is sent to the storage device 30. The storage device 30 has a buffer function for adjusting the amount of the wire main body 42 sent to the heater 32 and the amount of the wire main body 42 sent from the reel 28. The wire body 42 is sent to the heater 32 via the storage device 30.

In the preheating step, the heater 32 heats the wire body 42. The wire body 42 is preheated. The wire body 42 is sent to the extruder 34.

In the coating step, the outer peripheral surface of the wire body 42 is coated with the rubber composition. In the coating step, the rubber composition is charged into the extruder 34. The extruder 34 coats the outer peripheral surface of the wire body 42 with the rubber composition. The coated rubber composition forms a coating layer on the outer peripheral surface of the bead wire 22. The bead wire 22 is composed of a wire body 42 and a coating layer. The bead wire 22 is sent to the feeder 38.

In the winding process, the tension applying machine 36 applies tension to the bead wire 22. In this manufacturing apparatus 26, the tension roller 36a of the tension applying machine 36 is pressed against the bead wire 22. The tension roller 36a is pressed in a direction perpendicular to the axis of the bead wire 22. The tension roller 36a is pressed between the coating device 4 and the supply device 38. As a result, tension is applied to the bead wire 22. This tension acts in the axial direction of the bead wire 22. The supply device 38 adjusts the supply position of the bead wire 22 with respect to the bead former 40. The bead former 40 rotates, and the bead wire 22 is wound around the bead former 40. The control device controls the tension applying machine 36, the supply device 38, and the bead former 40.

The alternate long and short dash line Ax in FIG. 3 represents the rotation axis of the bead former 40. The arrow Q indicates the rotation direction of the bead former 40. The double-headed arrow Mx represents the moving direction of the supply device 38. The feeding device 38 is movable in parallel with the rotation axis Ax of the bead former 40. The bead former 40 has a disk-like shape. A groove 44 is formed on the outer peripheral surface of the bead former 40. As the bead former 40 rotates, the bead wire 22 to which tension is applied is wound around the groove 44.

FIG. 4 shows a core member 25 formed by winding the bead wire 22. The outer peripheral surface 44a of the groove 44 is inclined from the inner side to the outer side in the radial direction from one axial direction to the other. The double-headed arrow θ in FIG. 4 represents the inclination angle of the outer peripheral surface 44a. This inclination angle θ is also the inclination angle of the bottom surface of the core member 25. The bead wire 22 is wound along the outer peripheral surface 44a of the groove 44. As a result, the core member 25 having an inclination angle θ is formed.

FIG. 5A shows a state in which the bead wire 22 is wound around the groove 44. In FIG. 5A, the bead wire 22 is wound along the outer peripheral surface 44a. The bead wire 22 is wound, and the cross sections 24a to 24b are arranged in order in a direction inclined from the inner side to the outer side in the radial direction from one axial direction to the other.

FIG. 5B shows another aspect in which the bead wire 22 is wound around the groove 44. The cross sections 24a to 24c are arranged in order in a direction inclined from the inner side to the outer side in the radial direction from one axial direction to the other. The cross section 24d is arranged on the outer side in the radial direction of the cross section 24c. The cross sections 24d to 24e are arranged outside the first step of the cross sections 24a to 24c. The cross sections 24d to 24e are arranged in order in a direction inclined from the outer side to the inner side in the radial direction from the other side in the axial direction to the other side.

FIG. 5C shows yet another aspect in which the bead wire 22 is wound around the groove 44. The cross sections 24d to 24f are arranged in order in a direction inclined from the outer side to the inner side in the radial direction from the other side in the axial direction toward one side. The cross section 24g is arranged on the outer side in the radial direction of the cross section 24f. The cross sections 24g to 24h are arranged outside the second stage of the cross sections 24d to 24f. The cross sections 24g to 24h are arranged in order in a direction inclined from the inner side to the outer side in the radial direction from one axial direction to the other.

In this winding process, the control device controls the axial position of the feeder 38. The bead wire 22 is arranged at the position of the cross section 24a. The control device sets the tension roller 36a of the tension applying machine 36 to the pressing force F1. The tension applying machine 36 presses the tension roller 36a against the bead wire 22 with the pressing force F1. The pressing force F1 applies tension T1 to the bead wire 22. The control device rotates the bead former 40. The bead wire 22 is wound by this rotation.

When the bead wire 22 is wound around, the control device moves the position of the feeder 38 from one axial direction to the other at a predetermined pitch. At the position where the supply device 38 has moved, the bead former 40 is rotated and the bead wire 22 is further wound. The cross section 24 is arranged adjacent to the other axial direction of the cross section 24a.

The control device further moves the feeder 38 at a predetermined pitch from one axial direction to the other. The bead wire 22 is wound in a direction inclined from the inside to the outside in the radial direction from one axial direction to the other. In this way, the cross sections 24a to 24c are sequentially arranged in a direction inclined from the inner side to the outer side in the radial direction from one axial direction to the other.

Further, the bead wire 22 is wound around the outside of the cross section 24a to the outside of the cross section 24c. The feeder 38 and the bead former 40 wind the bead wire 22 around the outside in the radial direction of the cross section 24c. The cross section 24d is arranged on the outer side in the radial direction of the cross section 24c. When the bead wire 22 is wound around the position of the cross section 24d, the control device moves the feeder 38 from the other in the axial direction toward one at a predetermined pitch. The control device changes the pressing force F1 of the tension roller 36a to the pressing force F2. This pressing force F2 is smaller than the pressing force F1. The pressing force F2 applies tension T2 to the bead wire 22. This tension T2 is smaller than the tension T1.

The bead wire 22 is wound and the cross section 24 is arranged adjacent to one of the axial directions of the cross section 24d. The feeder 38 is moved at a predetermined pitch from the other in the axial direction toward one. The bead former 40 is rotated, and the bead wire 22 is wound in a direction inclined from the outside to the inside in the radial direction from the other in the axial direction to one. The cross sections 24d to 24f are arranged in order so as to be inclined from the outer side to the inner side in the radial direction from the other side in the axial direction toward one side. After winding the bead wire 22 around the position of the cross section 24f, the control device returns the tension T2 of the bead wire 22 to the tension T1 by the tension applying machine 36.

Further, the bead wire 22 is wound from the cross section 24d to the outside of the cross section 24f. The feeding device 38 and the bead former 40 wind the bead wire 22 around the outside in the radial direction of the cross section 24f. The cross section 24g is arranged on the outer side in the radial direction of the cross section 24f. When the bead wire 22 is wound around at a position having a cross section of 24 g, the control device moves the feeder 38 from one axial direction to the other at a predetermined pitch. The feeder 38 moves at a predetermined pitch from one axial direction to the other, and the bead wire 22 is wound so as to be inclined from the inner side to the outer side in the radial direction from one axial direction toward the other.

As shown in FIGS. 5 (a) to 5 (c), in this winding step, the cross section 24 is arranged in order in which the cross section is inclined from the inner side to the outer side in the radial direction from one axial direction to the other. It comprises a winding step and a downward winding step in which the cross section 24 is arranged in order from the other side in the axial direction to one side in the radial direction from the outside to the inside. The ascending winding process and the descending winding process are alternately repeated to form the core member 25.

In the down winding step shown in FIG. 5B, the bead wire 22 is wound in the order of the cross section 24d to the cross section 24e so as to be adjacent to the cross section 24 already arranged on the other side in the axial direction. In the down winding step, the cross sections 24 are arranged so as to be inclined inward from the outer side in the radial direction from the other side in the axial direction toward one side. As shown in FIG. 5B, the cross section 24 on one side in the axial direction abuts on the outer circumference of the cross section 24 adjacent to the other side, which is located inside the beadformer 40 in the radial direction. Therefore, in the down winding step, the cross section 24 wound on one side tends to interfere with the cross section 24 adjacent to the other side. Due to this interference, the cross section 24 wound on one side may be caught on the cross section 24 adjacent to the other side. This catch prevents the cross section 24 wound on one side from being arranged in a predetermined position. This catch causes a shift in the arrangement position of the cross section 24. This deviation of the arrangement position causes the core member 25 to collapse.

In this winding step, the tension T2 in the down winding step is smaller than the tension T1 in the up winding step. Since the tension T2 is small, the cross section 24 wound on one side is unlikely to be caught on the cross section 24 adjacent to the other side. The arrangement position of the cross section 24 is unlikely to shift. As a result, unwinding of the core member 25 is suppressed.

In the core member 25 having a large inclination angle θ, the arrangement position of the cross section 24 is likely to be displaced in the down winding process. This manufacturing method is suitable for manufacturing the core member 25 having a large inclination angle θ. From this point of view, the inclination angle θ of the core member 25 is preferably 16 degrees or more, and more preferably 18 degrees or more.

In this winding step, the tension T2 is made smaller than the tension T1 to suppress the unwinding of the core member 25. In this winding step, only the magnitude of the tension T1 and the magnitude of the tension T2 are different. Therefore, even in a core member having a different inclination angle θ and an inclination angle of the core member 25, the unwinding can be easily suppressed. This winding process can easily form various core members having different inclination angles.

Further, since the bead wire 22 includes a coating layer of a rubber composition, it is hard to slip between the cross sections 24. Therefore, in the down winding step, the cross section 24 wound on one side is likely to be caught on the cross section 24 adjacent to the other side. In this method of manufacturing the core member 25, since the tension T2 is small, the cross section 24 on one side is unlikely to be caught by the cross section 24 adjacent to the other side. This manufacturing method is suitable for winding a bead wire 22 having a coating layer.

In this winding step, the tension roller 36a of the tension applying machine 36 is pressed against the bead wire 22. The tension applying machine 36 can apply tension to the bead wire 22 and adjust the tension with a simple configuration. The tension applying machine 26 can be easily retrofitted to the conventional core member 25 manufacturing apparatus. Further, the tension roller 36a rotates and is pressed against the bead wire 22 without slipping. Since tension is generated by the tension roller 36a, damage to the bead wire 22 is suppressed.

The pressing forces F1 and F2 of the tension roller 36a are not particularly limited. The forces F1 and F2 are 0 (N) or more. The forces F1 and F2 may cause the bead wire 22 to generate a tension sufficient to be wound around the groove 44. On the other hand, if the pressing forces F1 and F2 are too large, the winding resistance becomes large. If the pressing forces F1 and F2 are too large, the bead wire 22 will be damaged. From these viewpoints, the pressing forces F1 and F2 are preferably 0.5 (N) or less. For example, the pressing force F1 in the ascending winding process is set to 0.2 (N) or more and 0.5 (N) or less. The pressing force F2 in the down winding process is 0 (N) or more and smaller than the pressing force F1. The difference between the pressing force F1 and the pressing force F2 is preferably 0.2 (N).

In the manufacturing apparatus 26, when the control device applies tension T1 to the bead wire 22 when the feeder 38 is moved from one axial direction to the other, and the feeder 38 is moved from the other axial direction to the other. Has a function of applying tension T2 to the bead wire 22. In this manufacturing method, the tension T1 when the position where the bead wire 22 is supplied moves from one axial direction to the other is the tension when the position where the bead wire 22 is supplied moves from the other axial direction to one side. It may be larger than T2, and this control device may not be used. For example, a mechanism may be provided in which the pressing force on which the tension roller 36a is pressed against the bead wire 22 changes depending on the axial movement direction of the feeder 38.

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

[Example]
The core member was manufactured using the manufacturing apparatus described in the embodiment. In this method of manufacturing the core member, the tension in the down winding process is smaller than the tension in the up winding process. The inclination angle θ of this core member was 20 degrees. Further, in this manufacturing method, the bead wire is wound at a higher speed than usual so that the winding collapse is likely to occur.

[Comparison example]
A bead member was manufactured in the same manner as in Example 1 except that the tension in the down winding step was made the same as the tension in the up winding step.

[Evaluation of unwinding]
The manufactured bead members were inspected for the occurrence of unwinding. The incidence of roll collapse was calculated. The evaluation results are shown in Table 1. This evaluation result is represented by an index with Example as 100. The larger this index, the smaller the incidence of unwinding. The smaller this index is, the more preferable it is.

As shown in Table 1, the production method of Examples has a higher evaluation than the production method of Comparative Examples. From this evaluation result, the superiority of the present invention is clear.

The method described above can be widely applied to the manufacture of a core member whose bottom surface is formed so as to be inclined with respect to the axial direction.

2 ... Tire 4 ... Bead 16 ... Core 22 ... Bead wire 24 ... Cross section 25 ... Core member 26 ... Manufacturing equipment 36 ... Tensioning machine 38 ... Feeding machine 40 ... bead former 42 ... wire body 44 ... groove

Claims (5)

It is a method of manufacturing a core member whose bottom surface is formed so as to be inclined with respect to the axial direction.
An ascending winding process in which the bead wire is wound so as to be inclined from the inside to the outside in the radial direction from one axial direction to the other.
It is provided with a down winding step in which the bead wire is wound so as to be inclined from the outside to the inside in the radial direction from the other in the axial direction to one.
The down tension applied to the bead wire in the down winding step is smaller than the up tension applied to the bead wire in the up winding step.
A method for manufacturing a tire core member. The manufacturing method according to claim 1, wherein the downward pressing force by which the tension roller is pressed against the bead wire in the downward winding step is smaller than the upward pressing force by which the tension roller is pressed against the bead wire in the upward winding step. The manufacturing method according to claim 1 or 2, wherein the inclination angle θ of the bottom surface of the core member with respect to the axial direction is 18 degrees or more. The core member forming process for forming the core member and
A pre-molding step in which members forming each part including the core member are combined to form a low cover, and
It is equipped with a vulcanization process in which the above low cover is vulcanized to obtain a tire.
In the core member forming step, the bottom surface of the core member is formed so as to be inclined with respect to the axial direction.
The core member forming step is an ascending winding step in which the bead wire is wound so as to be inclined from the inner side to the outer side in the radial direction from one axial direction to the other, and the outer side to the inner side in the radial direction from the other axial direction. It is equipped with a down winding process in which the bead wire is wound by inclining in the direction.
The down tension applied to the bead wire in the down winding step is smaller than the up tension applied to the bead wire in the up winding step.
Tire manufacturing method. A disk-shaped bead former having a groove on its outer circumference, a feeder for supplying the bead wire wound in the groove, and a tension applying machine for applying tension to the bead wire wound in the groove are provided. Ori,
The bottom surface of the groove extends from one axial direction to the other in a radial direction from the inside to the outside.
The feeder has a function of moving the position where the bead wire is supplied in the axial direction when the bead wire is wound around the groove.
The tension when the position where the bead wire is supplied moves from one axial direction to the other, and the tension when the position where the bead wire is supplied moves from the other axial direction to the other. A core member manufacturing device that has the function of making it larger.

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