JP7115078B2 - Rigid core for tire manufacturing and method of manufacturing tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rigid core for manufacturing a tire and a method of manufacturing a tire, and more particularly, the shift between segments constituting the rigid core and the deformation of the segments in the vulcanization process can be used to make the segments heavy and complex in structure. The present invention relates to a rigid core for tire manufacturing and a tire manufacturing method capable of avoiding and suppressing the above to manufacture a high-quality tire.

A pneumatic tire is manufactured by vulcanizing an unvulcanized green tire formed by laminating tire constituent members on the outer peripheral surface of a cylindrical forming drum. As one method of molding a green tire, a method of laminating tire constituent members on the outer peripheral surface of a rigid core having an outer peripheral surface shape corresponding to the tire inner peripheral surface shape of a finished tire is known (for example, Patent Document 1).

The rigid core is constructed by arranging and assembling a large number of arcuate segments in an annular shape when viewed from the side. A green tire formed on the outer peripheral surface of the rigid core is placed in a vulcanizing mold together with the rigid core and vulcanized under a predetermined temperature and pressure. In the vulcanization process of a green tire, the green tire and the rigid core are strongly pressed from the tire outer peripheral side, so that the boundaries between adjacent segments in the circumferential direction may be misaligned or the segments may be deformed. If such displacement or deformation of the segments occurs, there is a problem that the vulcanized tire is formed with a step or the like, and the appearance quality is deteriorated. By increasing the strength of the segment with a heavy and complex structure, it is possible to suppress displacement and deformation of the segment. However, when the segment has a heavy structure or a complicated structure, the handleability and the like deteriorate. Therefore, it is desirable to avoid making the segment heavy and have a complicated structure, and suppress displacement and deformation of the segment during the vulcanization process.

JP 2015-168173 A

It is an object of the present invention to manufacture high-quality tires by suppressing displacement between segments and deformation of segments that make up a rigid core during the vulcanization process while avoiding making the segments heavy and having a complicated structure. It is an object of the present invention to provide a rigid core for manufacturing a tire and a manufacturing method of the tire.

In order to achieve the above object, a rigid core for manufacturing a tire according to the present invention has a large number of arc-shaped segments in a side view, and these segments are arranged in a ring so that adjacent segments in the circumferential direction are connected to each other. In the rigid core for manufacturing a cylindrical tire, the plurality of segments are composed of small segments with relatively short outer arc lengths in side view and large segments with relatively long outer arc lengths. It consists of two types, the small segments and the large segments are alternately arranged in the circumferential direction, and the outer arc length of the large segment is 1.05 to 3 times the outer arc length of the small segment. Hereinafter, the small segment is characterized in that the arc length on the outer peripheral side is set to be 1 to 1.5 times the arc length on the inner peripheral side.

A method for manufacturing a tire according to the present invention includes forming a green tire on the outer peripheral surface of the above rigid core for tire manufacturing, placing the green tire together with the rigid core in a vulcanization mold, and vulcanizing the green tire. It is characterized by manufacturing a tire by vulcanizing .

According to the present invention, the rigid core is composed of two types, namely, a small segment having a relatively short outer arc length in side view and a large segment having a relatively long outer arc length. and large segments are arranged alternately one by one in the circumferential direction, the outer arc length of the large segment is 3 times or less than the outer arc length of the small segment, and the outer arc length of the small segment is the inner circumference arc length It is set to 0.6 times or more of the length. Therefore, even if the rigid core in which the segments adjacent to each other in the circumferential direction are connected is strongly pressed from the outer peripheral side in the vulcanization process, the pressing force is prevented from acting intensively on any one of the segments. Easy to spread widely. Along with this, in order to ensure the strength of the segments, it has become possible to suppress displacement between segments and deformation of segments during the vulcanization process without making the segments heavy or complicated in structure. Contributes to improved tire quality.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which illustrates embodiment of the rigid core for tire manufacture of this invention by the side view. FIG. 2 is an explanatory diagram illustrating an upper half of the rigid core of FIG. 1 in a cross-sectional view; FIG. 2 is an explanatory diagram illustrating a small segment and a large segment in FIG. 1 as viewed from the side; FIG. 3 is an explanatory diagram illustrating, in cross-sectional view, the upper half of a green tire in the middle of molding to which some tire constituent members are attached. It is explanatory drawing which illustrates the upper half of the shape|molded green tire by the cross-sectional view. FIG. 6 is an explanatory diagram illustrating a cross-sectional view of a vulcanizing device vulcanizing the green tire of FIG. 5 ; It is explanatory drawing which illustrates the upper half of the manufactured tire by the cross-sectional view. It is explanatory drawing which illustrates a part of rigid core pressed by a vulcanization process by the side view. FIG. 11 is an explanatory diagram illustrating another specification (specification 2) of the rigid core in a side view; It is explanatory drawing which illustrates another specification (specification 3) side view of a rigid core.

Hereinafter, a rigid core for manufacturing a tire and a method for manufacturing a tire according to the present invention will be described based on embodiments shown in the drawings.

The embodiment of the rigid core 1 of the invention illustrated in FIGS. 1-3 has a number of arcuate segments 2, 3 in side view. A large number of segments 2 and 3 constituting the rigid core 1 are of two types, a small segment 2 and a large segment 3, and are rigid bodies made of metal or the like.

The rigid core 1 has an outer peripheral surface shape corresponding to the tire inner peripheral surface shape of the vulcanized tire 15 to be manufactured. That is, the outer peripheral surface of the rigid core 1 is formed in substantially the same shape as the inner peripheral surface of the completed tire 15 to be manufactured. Therefore, as illustrated in FIG. 2, the outer peripheral surface of the rigid core 1 has a profile in which the peripheral length changes depending on the position of the rigid core 1 in the width direction. In general, the profile of the rigid core 1 is such that the central portion in the width direction of the rigid core 1 protrudes further to the outer peripheral side than both end portions.

The small segment 2 has a fan shape with an outer arc length of So and an inner arc length of Si when viewed from the side. The large segment 3 is fan-shaped with an outer arc length of Lo and an inner arc length of Li when viewed from the side. The outer arc length So of the small segment 2 is relatively short, and the outer arc length Lo of the large segment 3 is relatively long (So<Lo).

A cylindrical rigid core 1 is constructed by alternately arranging small segments 2 and large segments 3 one by one in the circumferential direction and connecting the segments 2 and 3 adjacent in the circumferential direction. That is, the rigid core 1 has the same number of small segments 2 and large segments 3 . The number of small segments 2 and large segments 3 is, for example, 3 to 6 each. Circumferentially adjacent segments 2 and 3 are connected by abutting their opposing circumferential end surfaces 2a and 3a.

A support shaft 5 radially extending from a central shaft 4 disposed at the center of the cylinder shaft of the rigid core 1 is connected to the inner peripheral surfaces of the respective segments 2 and 3 . The support shaft 5 and the central shaft 4 are connected via a boss 4a. Each support shaft 5 is detachable from the segments 2 and 3 and the central shaft 4, and can be divided into a plurality of structures or can be folded. A dashed line CL in the drawing indicates the position of the cylinder axis of the rigid core 1 .

In this embodiment, a disk-shaped side plate 5a is attached to the central portion of both side surfaces of the rigid core 1. As shown in FIG. The outer edge portion of each side plate 5a engages the inner arc portion of each segment 2, 3 assembled in an annular fashion. A through hole is formed in the central portion of the side plate 5a, and the central shaft 4 is inserted through this through hole. 1, 9, and 10, the side plate 5a is indicated by a chain double-dashed line in order to clarify the internal structure of the rigid core 1. As shown in FIG.

The outer arc length Lo of the large segment 3 is set to be less than or equal to three times the outer arc length So of the small segment 2 . That is, it is set to (Lo/So)≦3. Further, the outer arc length So of the small segment 2 is set to be 0.6 times or more the inner circumference arc length Si of the small segment 2 . That is, it is set to (So/Si)≧0.6.

By setting the range of (Lo/So) and the range of (So/Si) in this way, the balance between the sizes of the small segment 2 and the large segment 3 and the inclination angles of the circumferential end faces 2a and 3a in contact with each other can be adjusted. in the desired state. (Lo/So) is, for example, 1.05 or more, and (So/Si) is, for example, 1.5 or less.

Next, a procedure for manufacturing a tire using this rigid core 1 will be described.

By alternately arranging the separated small segments 2 and large segments 3 one by one in the circumferential direction and connecting the segments 2 and 3 adjacent in the circumferential direction, the cylinder illustrated in FIGS. construct a rigid core 1 of shape. Predetermined tire constituent members (inner liner 8, carcass layer 10, etc.) are sequentially adhered to the outer peripheral surface of the rigid core 1 as shown in FIG. Specifically, the inner liner 8 and the carcass layer 10 are sequentially laminated and adhered to the outer peripheral surface of the rigid core 1 to form each of them into a cylindrical shape. Ring-shaped bead members 9 are arranged on the carcass layers 10 on both side surfaces in the width direction of the rigid core 1, and the carcass layers 10 are folded around the bead cores 9a of the respective bead members 9.例文帳に追加In addition, unvulcanized side rubbers 12 are laminated and attached to both ends of the carcass layer 10 in the width direction. If necessary, other tire constituent members are also attached.

Next, a cylindrical belt layer 11 is formed on the outer peripheral surface of the cylindrical carcass layer 10 attached to the outer peripheral side of the rigid core 1 . The belt layer 11 has a large number of reinforcing cords arranged at a predetermined inclination angle with respect to the tire circumferential direction and coated with unvulcanized rubber.

Next, necessary tire constituent members such as the belt reinforcing layer and the unvulcanized tread rubber 13 are attached to the outer peripheral surface of the belt layer 11 in sequence. In this manner, a green tire 14 is formed on the outer peripheral surface of the rigid core 1, as illustrated in FIG.

Next, as illustrated in FIG. 6, the green tire 14 is placed together with the rigid core 1 in the vulcanization mold 7 installed in the vulcanization device 6, and the vulcanization mold 7 is closed. In this embodiment, the vulcanizing mold 7 is composed of a plurality of circularly arranged sector molds 7a, an annular upper side mold 7b and an annular lower side mold 7c. A vulcanized tire 15 illustrated in FIG. 7 is completed by vulcanizing the green tire 14 under predetermined conditions inside the closed vulcanizing mold 7 . After the vulcanized tire 15 is removed from the vulcanizing mold 7, the rigid core 1 is disassembled and separated from the tire 15. - 特許庁

In the vulcanization process of the green tire 14, as illustrated in FIG. 8, the rigid core 1 is strongly pressed together with the green tire 14 from the tire outer peripheral side. Each small segment 2 is pressed with a pressing force Fs from the outer peripheral side, and each large segment 3 is pressed with a pressing force Fb from the outer peripheral side. Circumferentially adjacent segments 2 and 3 are in contact with each other at their circumferential end surfaces 2a and 3a, so that force acts therebetween.

When the rigid core 1 has two types of segments, the small segment 2 and the large segment 3, the large segment 3 has a larger pressing force receiving area than the small segment 2, and therefore receives a larger pressing force Fb. Become. Therefore, the small segment 2 tends to receive a large pressure from the adjacent large segment 3 . Along with this, the boundary surfaces (circumferential end surfaces 2a and 3a) between the small segment 2 and the large segment 3 are likely to be radially displaced, and the small segment 2 is more likely to deform than the large segment 3. Become.

In the present invention, the outer arc length Lo of the large segment 3 is three times or less the outer arc length So of the small segment 2, and the outer arc length So of the small segment 2 is 0.6 times the inner arc length Si. set to more than double. Therefore, even if the rigid core 1 is strongly pressed from the outer peripheral side in the vulcanization process, it is possible to prevent the pressing force from acting intensively on one of the segments 2 and 3. It makes it easier to distribute the pressure widely.

That is, by setting the small segment 2 and the large segment 3 to specifications that satisfy (Lo/So)≦3 and (So/Si)≧0.6, the balance between the sizes of the small segment 2 and the large segment 3 and The inclination angles of the circumferential end faces 2a and 3a in contact with each other are set to an appropriate state for suppressing displacement at the boundary surfaces of the respective segments 2 and 3 and deformation of the segments 2 and 3 during the vulcanization process. Therefore, in order to ensure the strength of the segments 2 and 3, the segments 2 and 3 do not have a heavy structure or a complicated structure. can be suppressed. As a result, in the manufactured tire 15, formation of a step or the like due to displacement at the interface between the segments 2 and 3 or deformation of the segments 2 and 3 is avoided, leading to improvement in tire quality.

If (Lo/So) is excessively large, the small segment 2 becomes relatively small, making it difficult to suppress the deformation of the small segment 3. Therefore, it is made 3 or less. On the other hand, if (Lo/So) becomes too small, the difference between the small segment 2 and the large segment 3 disappears, so it is preferably 1.05 or more. When (So/Si) becomes too small, the inclination of the circumferential end surfaces 2a and 3a where the small segment 2 and the large segment 3 contact is such that the large segment 3 covers the small segment 2 from the outer peripheral side of the rigid core 1. As a result, the pressing force tends to be concentrated on the small segment 2, so the value is set to 0.6 or more. On the other hand, when (So/Si) becomes excessively large, the length of the circumferential end faces 2a and 3a becomes longer and the pressure is increased to equalize the small segment 2 and the large segment 3 (circumferential end faces 2a and 3a). Since processing accuracy is required, it is preferable to set it to 1.5 or less.

Considering the ease of handling of the operation of annularly connecting the segments 2 and 3 and the operation of releasing the coupling of the annularly connected segments 2 and 3, the number of the small segments 2 and the number of the large segments 3 is 3, respectively. ~6 is preferred.

When manufacturing a tire by vulcanizing a green tire using a rigid core having two types of small segments and large segments, a tire is manufactured using the following three types of rigid cores, and then the deformation amount of the segment was measured. The rigid cores used were of three specifications illustrated in FIGS. The conditions were kept the same.

The measured deformation amount of the segment is the boundary surface (circumferential end face) at the widthwise central portion of each of the small segment and the large segment, and the radial displacement amount (inward deformation amount) at the circumferential central position. . Table 1 shows the measurement results. In Table 1, the amount of deformation at each position is shown as an index with the amount of deformation in the large segment being 100 as a reference. A smaller index value indicates a smaller deformation.

From the results in Table 1, specifications 1 and 2, which are set to (Lo/So) ≤ 3 and (So/Si) ≥ 0.6, are more effective in suppressing the deformation of small segments than specification 3. It turns out to be effective.

Reference Signs List 1 rigid core 2 small segment 2a circumferential end face 3 large segment 3a circumferential end face 4 center shaft 4a boss 5 support shaft 5a side plate 6 vulcanizing device 7a, 7b, 7c vulcanizing mold 8 inner liner 9 bead member 9a bead core 10 Carcass layer 11 Belt layer 12 Side rubber 13 Tread rubber 14 Green tire 15 Tire (vulcanized tire)

Claims (3)

A rigid core for manufacturing a cylindrical tire, which has a large number of arc-shaped segments when viewed from the side, and is configured by arranging these segments in a ring and connecting adjacent segments in the circumferential direction,
The large number of segments are composed of two types: small segments with relatively short outer arc lengths in side view and large segments with relatively long outer arc lengths. The outer arc length of the large segment is 1.05 times or more and 3 times or less than the outer arc length of the small segment, and the outer arc length of the small segment is the inner arc length of the small segment. A rigid core for manufacturing a tire, characterized in that it is set to be 1 to 1.5 times as long as the circumferential arc length. The rigid core for building a tire according to claim 1, wherein the numbers of said small segments and said large segments are respectively 3-6. A green tire is molded on the outer peripheral surface of the rigid core for tire manufacturing according to claim 1 or 2, and the green tire is placed in a vulcanizing mold together with the rigid core to vulcanize the green tire. A tire manufacturing method for manufacturing a tire by

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