JP6825899B2 - How to make a pneumatic tire - Google Patents

Description

The present invention relates to a method for manufacturing a pneumatic tire.

An inner liner is provided on the innermost side of the pneumatic tire. The inner liner comprises a butyl layer for preventing air permeation and a squeegee layer for adhering the butyl layer and carcass ply (see, for example, Patent Document 1).

In the production of a pneumatic tire, as shown in FIG. 5, a rubber chafer 113 is first attached on a molded drum, and a butyl layer 131 and a squeegee layer 130 are laminated on the rubber chafer 113. At this time, as shown in FIG. 5, the widthwise end portion of the butyl layer 131 is sandwiched between the rubber chafer 113 and the squeegee layer 130. Then, since the widthwise end portion of the butyl layer forms the step 140, air remains in the vicinity of the widthwise end portion of the butyl layer 131.

By the way, Patent Document 2 describes that the end portion of the inner liner in the tire circumferential direction is inclined. Further, Patent Document 3 describes that the boundary between the inner liner and the side sheet is inclined.

Japanese Unexamined Patent Publication No. 2007-229941 JP-A-2010-167829 JP-A-2009-202471

Therefore, the present invention provides a method for manufacturing a pneumatic tire, which comprises a step of sandwiching the widthwise end portion of the butyl layer between a rubber chafer and a squeegee layer, and does not easily leave air in the vicinity of the widthwise end portion of the butyl layer. That is the issue.

The method for producing a pneumatic tire of the present embodiment includes a step of laminating a butyl layer and a squeegee layer on a rubber chafer and sandwiching a widthwise end portion of the butyl layer between the rubber chafer and the squeegee layer. A method for manufacturing a pneumatic tire, in which, before the step, the widthwise ends of the butyl layer and the squeegee layer are 20 ° or more and 35 ° or less with respect to the surfaces of the butyl layer and the squeegee layer. In the step, the overlapping width of the rubber chafer and the butyl layer is set to 5 mm or more and 20 mm or less, and in the step, from the widthwise end of the butyl layer to the widthwise end of the squeegee layer. The distance is 5 mm or more and 20 mm or less .

According to the present embodiment, the widthwise ends of the butyl layer and the squeegee layer are inclined to be 20 ° or more and 35 ° or less with respect to the surfaces of the butyl layer and the squeegee layer, so that these ends form a step. It is difficult for air to remain in the vicinity of the widthwise end of the butyl layer.

A half cross-sectional view of the pneumatic tire of this embodiment. The cross-sectional view which shows the rough manufacturing method of the pneumatic tire of this embodiment. FIG. 3 is an axial sectional view of the molded drum D showing how to attach the tire constituent members in the primary molding of the present embodiment. FIG. 3 is an axial sectional view of a molded drum D showing a method of attaching the squeegee layer 30 and the butyl layer 31 to the rubber chafer 13 in the present embodiment. FIG. 3 is an axial sectional view of a molded drum showing how to attach the squeegee layer 130 and the butyl layer 131 to the rubber chafer 113 in the conventional method for manufacturing a pneumatic tire.

This embodiment will be described with reference to the drawings. It should be noted that the present embodiment is merely an example, and those which have been appropriately modified without departing from the spirit of the present invention shall be included in the scope of the present invention. Further, for convenience of explanation, the drawings may be drawn with exaggerated length, shape, etc., or may be drawn schematically. However, such drawings are merely examples and do not limit the interpretation of the present invention.

First, the structure of the pneumatic tire manufactured by the present embodiment will be described. As shown in FIG. 1, the pneumatic tire manufactured by the present embodiment is composed of a bead core in which a bundled steel wire is coated with rubber and a rubber bead filler provided on the outer side of the bead core in the tire radial direction. Beads 10 are provided on both sides in the tire width direction. The carcass ply 11 wraps the beads 10 on both sides in the tire width direction and forms the skeleton of the pneumatic tire between these beads. A belt layer composed of one or a plurality of belts 12 having a steel cord coated with rubber is provided on the outer side of the carcass ply 11 in the tire radial direction. Further, a tread rubber 14 having a ground contact surface is provided on the outer side in the radial direction of the tire. Further, on both sides in the width direction of the belt 12, lower belt pads 15 are provided between the carcass ply 11 and the belt 12. In addition, sidewall rubbers 16 are provided on both sides of the carcass ply 11 in the tire width direction. An inner liner 17 is provided inside the carcass. The inner liner 17 includes a butyl layer 31 inside the tire and a squeegee layer 30 on the carcass ply 11 side. The butyl layer 31 is a layer for preventing the permeation of air, and the squeegee layer 30 is a layer for adhering the butyl layer 31 and the carcass ply 11.

Around the bead 10, a steel chafer 20 is provided so as to wrap the bead 10 from the outside of the carcass ply 11. A steel chafer pad 21 is provided at an end portion of the steel chafer 20 on the outer side in the tire width direction. Further, a flare tape 22 is provided near the end portion of the steel chafer 20 on the inner side in the tire width direction, and a part of the flare tape 22 is sandwiched between the steel chafer 20 and the carcass ply 11. Further, a rubber chafer 13 is provided from the lower end of the sidewall rubber 16 to the lower end of the inner liner 17 so as to wrap the bead 10 from the outside of the steel chafer 20. A chafer pad 23 is provided between the rubber chafer 13 and the steel chafer pad 21.

Next, a rough manufacturing method of the pneumatic tire shown in FIG. 1 will be described. The manufacturing process of pneumatic tires is roughly divided into primary molding, secondary molding and vulcanization molding. FIG. 2 shows a simplified method for manufacturing a pneumatic tire.

As shown in FIG. 2A, first, in the primary molding, a band body 19 composed of an inner liner 17, a carcass ply 11, a sidewall rubber 16 and the like is formed.

As shown in FIG. 3, first, the rubber chafer 13 and the sidewall rubber 16 are attached to both sides of the molded drum D in the axial direction (drum axial direction). Next, the inner liner 17 is attached to the central portion in the drum axial direction so as to overlap a part of the rubber chafer 13. Here, the butyl layer 31 and the squeegee layer 30 constituting the inner liner 17 may be attached to the molding drum D in order, or the butyl layer 31 and the squeegee layer 30 are integrated in advance to form the inner liner 17. After being formed, the inner liner 17 may be attached to the molded drum D. Next, the chafer pad 23 is attached to a place including the boundary between the rubber chafer 13 and the sidewall rubber 16. Next, the steel chafer 20 and the steel chafer pad 21 are attached to the locations from the inner liner 17 to the chafer pad 23. Next, the flare tape 22 is attached to a place including the boundary between the steel chafer 20 and the inner liner 17. Next, the carcass ply 11 is attached to the central portion in the drum axial direction. An insulation tape 24 is attached to a part of the carcass ply 11. Next, the lower belt pad 15 is attached to a place where the end portion of the belt 12 is arranged in the secondary molding. As described above, the band body 19 composed of the inner liner 17, the carcass ply 11, the sidewall rubber 16, and the like is completed.

After the band body 19 is formed, the beads 10 are set at two predetermined positions of the band body 19 as shown in FIGS. 2 (b) and 3. Next, as shown in FIG. 2C, the portion between the two beads 10 of the band body 19 is shaped in the outer diameter direction, and the portion outside the two beads 10 of the band body 19 is shaped. Each is turned up to wrap the bead 10. In FIG. 2C, the arrow S is the shaping direction, and the arrow T is the turn-up direction. The so-called green case 25 is a band body 19 shaped and turned up. When the green case 25 is completed, the primary molding is completed.

Next, secondary molding is performed in which the belt 12 and the tread rubber 14 are attached to the outer diameter portion of the green case 25. Prior to the secondary molding, the belt 12 and the tread rubber 14 are laminated in advance to complete the tread body 26. In the secondary molding, as shown in FIG. 2D, the tread body 26 is attached to the outer diameter portion of the green case 25. The raw tire 28 is a combination of the green case 25 and the tread body 26. The raw tire 28 is stitched to bleed air between the tire components, and the secondary molding is completed.

After the secondary molding is completed, vulcanization molding is performed. In vulcanization molding, the raw tire 28 is placed in a mold and held at a predetermined temperature for a predetermined time. When the vulcanization molding is completed, the pneumatic tire is completed.

Next, the structure of the inner liner 17 and the attachment of the inner liner 17 in the above primary molding will be described in detail.

As described above, the inner liner 17 is composed of a squeegee layer 30 and a butyl layer 31. As shown in FIG. 4, the widthwise ends of the squeegee layer 30 and the butyl layer 31 (the ends on the outer side in the drum axial direction in the primary molding and the ends on the inner diameter side in the completed pneumatic tire) There is a slope. In FIG. 4, as a preferred embodiment, the inclined surface 32 at the widthwise end of the squeegee layer 30 faces upward (the radial outside of the band 19), and the inclined surface 33 at the widthwise end of the butyl layer 31 faces downward (band). It faces the inside of the body 19 in the radial direction). However, when the inclined surface 32 at the widthwise end of the squeegee layer 30 faces upward, the inclined surface 33 at the widthwise end of the butyl layer 31 may also face upward. Further, the inclined surface 32 at the widthwise end of the squeegee layer 30 may face downward, and in that case, the inclined surface 33 at the widthwise end of the butyl layer 31 may face up or down. The angle θ1 of the inclined surface 32 of the squeegee layer 30 with respect to the surface 34 of the squeegee layer 30 is 20 ° or more and 35 ° or less. Further, the angle θ2 of the inclined surface 33 of the butyl layer 31 with respect to the surface 35 of the inclined surface 33 of the butyl layer 31 is also 20 ° or more and 35 ° or less.

These inclined surfaces 32 and 33 are formed before the primary molding. These inclined surfaces 32 and 33 may be formed by a base having the shape of the inclined surfaces 32 and 33 during extrusion molding of the squeegee layer 30 and the butyl layer 31. Further, these inclined surfaces 32 and 33 may be formed by extruding the squeegee layer 30 and the butyl layer 31 and then cutting the ends thereof.

In the primary molding, the butyl layer 31 and the squeegee layer 30 are laminated on the central portion in the drum axial direction including the inner portion in the drum axial direction of the rubber chafer 13. At this time, as shown in FIG. 4, the widthwise end portion of the squeegee layer 30 is arranged outside the widthwise end portion of the butyl layer 31 in the drum axial direction, and the squeegee layer 30 is arranged from above the butyl layer 31. Is pasted. Therefore, the widthwise end of the butyl layer 31 is sandwiched between the squeegee layer 30 and the rubber chafer 13.

Here, the butyl layer 31 and the rubber chafer 13 are attached so that the overlapping width L1 is 5 mm or more and 20 mm or less. Further, it is desirable that the butyl layer 31 is attached so that the distance L0 from the widthwise end to the squeegee layer 30 in the widthwise direction is 5 mm or more and 20 mm or less.

In addition, although each tire component (that is, inner liner 17, carcass ply 11, sidewall rubber 16, etc.) is drawn vertically separated in FIGS. 3 and 4, each tire component is drawn after the primary molding is performed. Is in close contact with the top and bottom.

Next, the action and effect of this embodiment will be described. In the present embodiment, since the inclined surface 33 with respect to the surface 35 of the butyl layer 31 is provided at the widthwise end portion of the butyl layer 31, when the butyl layer 31 is attached to the rubber chafer 13, the rubber chafer 13 and It is difficult to form a step due to the butyl layer 31. Therefore, even if the squeegee layer 30 is covered from above the widthwise end of the butyl layer 31, air is unlikely to remain in the vicinity of the widthwise end of the butyl layer 31.

Further, since the inclined surface 32 with respect to the surface 34 of the squeegee layer 30 is provided at the widthwise end portion of the squeegee layer 30, when the squeegee layer 30 is attached to the rubber chafer 13, the rubber chafer 13 and the squeegee layer 30 are attached. It is difficult to form a step due to. Therefore, even if the steel chafer 20 is put on the squeegee layer 30, air is unlikely to remain in the vicinity of the widthwise end portion of the squeegee layer 30.

Here, since the angle θ1 of the inclined surface 32 of the squeegee layer 30 with respect to the surface 34 of the squeegee layer 30 and the angle θ2 of the inclined surface 33 of the butyl layer 31 with respect to the surface 35 of the butyl layer 31 are 20 ° or more, the squeegee layer 30 and It is possible to prevent the butyl layer 31 (particularly the butyl layer 31) from becoming too thin near the end in the width direction so that air can easily permeate. Further, since the angle θ1 of the inclined surface 32 of the squeegee layer 30 with respect to the surface 34 of the squeegee layer 30 and the angle θ2 of the inclined surface 33 of the butyl layer 31 with respect to the surface 35 of the butyl layer 31 are 35 ° or less, the squeegee layer 30 and butyl It is possible to prevent the widthwise end of the layer 31 from forming a step.

Further, since the overlapping width L1 of the butyl layer 31 and the rubber chafer 13 is 5 mm or more, the butyl layer 31 and the rubber chafer 13 are sufficiently adhered to each other, and it is possible to prevent air from remaining between them. .. Further, since the overlapping width L1 of the butyl layer 31 and the rubber chafer 13 is 20 mm or less, the butyl layer 31 is rolled up around the bead 10 in the primary molding, which causes cracks in the rubber chafer 13. Can be prevented.

Further, if the distance L0 from the widthwise end of the butyl layer 31 to the widthwise end of the squeegee layer 30 is 5 mm or more, the rubber chafer 13 and the squeegee layer 30 can be reliably contacted, and the squeegee layer 30 and butyl It is possible to prevent air from remaining in the vicinity of the widthwise end of the layer 31. Further, if the distance L0 from the widthwise end of the butyl layer 31 to the widthwise end of the squeegee layer 30 is 20 mm or less, the widthwise length of the butyl layer 31 is not too short, and the butyl layer 31 is air. Can be prevented from penetrating.

In order to confirm the effect of this embodiment, the pneumatic tires of the comparative examples in Table 1 and the examples in Table 2 were evaluated. In Tables 1 and 2, L0 indicates the distance from the widthwise end of the butyl layer to the widthwise end of the squeegee layer, and L1 indicates the overlapping width of the rubber chafer and the butyl layer. Further, in Tables 1 and 2, θ indicates the angle formed by the inclined surface and the surface of the widthwise end portion of the butyl layer and the squeegee layer, and corresponds to θ1 and θ2 in the above embodiment. The pneumatic tire of the embodiment satisfies the configuration of the above embodiment, whereas the pneumatic tire of the comparative example does not satisfy any of the configurations.

The evaluation items were the rate of defective air entry and air permeability resistance. In the evaluation of the occurrence rate of air-filled defects, the evaluator manufactured 100 tires of size 11R22.5, observed the appearance, counted the number of tires for which appearance defects due to the remaining air were confirmed, and calculated the defect rate. .. The smaller the value, the lower the defective rate. In the evaluation of air permeability resistance, the evaluator assembled a tire of size 11R22.5 to a wheel of rim size 22.5 x 7.50 to set the internal pressure to 850 kPa, and measured the internal pressure after leaving it for 90 days to determine the internal pressure. The descent allowance was indexed. The larger the index, the more the internal pressure did not drop, and the inner liner prevented air permeation.

The results are shown in Tables 1 and 2, and it was confirmed that the pneumatic tire of the example had a lower occurrence rate of air injection defects than the pneumatic tire of the comparative example. It was also confirmed that the pneumatic tire of the example had good air permeability resistance.

10 ... bead, 11 ... carcass ply, 12 ... belt, 13 ... rubber chafer, 14 ... tread rubber, 15 ... underbelt pad, 16 ... sidewall rubber, 17 ... inner liner, 19 ... band body, 20 ... steel chain Fur, 21 ... Steel chafer pad, 22 ... Flare tape, 23 ... Chafer pad, 24 ... Insulation tape, 25 ... Green case, 26 ... Tread body, 28 ... Raw tire, 30 ... Squishy layer, 31 ... Butyl layer , 32 ... Inclined surface at the widthwise end of the squeegee layer, 33 ... Inclined surface at the widthwise end of the butyl layer, 34 ... Surface of the squeegee layer, 35 ... Surface of the butyl layer, 113 ... Rubber chafer, 130 ... Squeegee Layer, 131 ... Butyl layer, 140 ... Step

Claims (1)

In a method for manufacturing a pneumatic tire, which comprises a step of laminating a butyl layer and a squeegee layer on a rubber chafer and sandwiching a widthwise end portion of the butyl layer between the rubber chafer and the squeegee layer.
Prior to the step, the widthwise ends of the butyl layer and the squeegee layer are inclined to be 20 ° or more and 35 ° or less with respect to the surfaces of the butyl layer and the squeegee layer.
In the step, the overlapping width of the rubber chafer and the butyl layer is set to 5 mm or more and 20 mm or less .
A method for manufacturing a pneumatic tire in which the distance from the widthwise end of the butyl layer to the widthwise end of the squeegee layer is 5 mm or more and 20 mm or less in the step.

Images