JP5406701B2 - Rigid core for tire vulcanization - Google Patents

Rigid core for tire vulcanization Download PDF

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JP5406701B2
JP5406701B2 JP2009294398A JP2009294398A JP5406701B2 JP 5406701 B2 JP5406701 B2 JP 5406701B2 JP 2009294398 A JP2009294398 A JP 2009294398A JP 2009294398 A JP2009294398 A JP 2009294398A JP 5406701 B2 JP5406701 B2 JP 5406701B2
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tire
core
tread
circumferential
core segment
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昌也 角田
章夫 袴田
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Sumitomo Rubber Industries Ltd
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Description

本発明は、トレッド成形部の肉厚を減じて熱伝導を改善しながら該トレッド成形部の変形を抑制しうるタイヤ加硫用の剛性中子に関する。   The present invention relates to a rigid core for tire vulcanization that can suppress deformation of the tread molded part while reducing the thickness of the tread molded part to improve heat conduction.

近年、タイヤの形成精度を高めかつタイヤ内の残留歪みを低減させるため、図9（Ａ）に示すように、加硫済みタイヤのタイヤ内面形状に相当する外面形状を有する剛性中子ａを用い、この剛性中子ａ上に、インナーライナ、カーカスプライ、ベルトプライ、サイドウォールゴム、トレッドゴム等のタイヤ構成部材を順次貼り付けて未加硫タイヤｔを形成するとともに、この未加硫タイヤｔを剛性中子ａごと加硫金型ｂ内に投入し、内型である剛性中子ａと外型である加硫金型ｂとの間でタイヤを加硫成形する方法が提案されている。   In recent years, a rigid core a having an outer surface shape corresponding to the tire inner surface shape of a vulcanized tire is used as shown in FIG. A tire component such as an inner liner, a carcass ply, a belt ply, a sidewall rubber, and a tread rubber is sequentially pasted on the rigid core a to form an unvulcanized tire t, and the unvulcanized tire t Is introduced into the vulcanization mold b together with the rigid core a, and the tire is vulcanized and molded between the rigid core a as the inner mold and the vulcanization mold b as the outer mold. .

この剛性中子ａでは、図9（Ｂ）に示すように、加硫成形後にタイヤから分解して取り外せるように、タイヤ周方向に分割される複数の中子セグメントｃから形成される。詳しくは、周方向両端の分割面が、半径方向内方に向かって周方向巾が減じる向きに傾斜する第１の中子セグメントｃ１と、この第１の中子セグメントｃ１とは周方向に交互に配されしかも周方向両端の分割面が、半径方向内方に向かって周方向巾が増す向きに傾斜する第２の中子セグメントｃ２とから構成される。そして、第２の中子セグメントｃ２から順次半径方向内方に一つずつ移動させて取り出すことで、剛性中子ａを分解して加硫済みタイヤから取り外すことができる。   As shown in FIG. 9B, the rigid core a is formed of a plurality of core segments c divided in the tire circumferential direction so as to be disassembled and removed from the tire after vulcanization molding. Specifically, the first core segment c1 in which the dividing surfaces at both ends in the circumferential direction are inclined in the direction in which the circumferential width decreases toward the inner side in the radial direction, and the first core segment c1 are alternately arranged in the circumferential direction. Further, the dividing surfaces at both ends in the circumferential direction are configured by second core segments c2 which are inclined in the direction in which the circumferential width increases inward in the radial direction. Then, the rigid core a can be disassembled and removed from the vulcanized tire by sequentially moving from the second core segment c2 one by one inward in the radial direction.

他方、加硫金型ｂのトレッド形成モールドｂ１を閉める際、トレッド溝形成用の溝成形突条ｄが先ず未加硫タイヤｔの表面に当たるが、前記剛性中子ａを用いた加硫成形においては、加硫金型ｂが閉じた時の加硫金型ｂと剛性中子ａとの間の内容積は、未加硫タイヤｔの体積と実質的に一致するように構成されている。そのため、金型閉にて溝成形突条ｄが未加硫タイヤｔ内に埋入する際、ゴムが逃げる十分なスペースが形成されず、剛性中子ａのトレッド成形部ａ１に大きな圧力が作用し、前記トレッド成形部ａ１が、半径方向内側に撓んで塑性変形を起こすという傾向がある。特に近年、剛性中子ａ内に設けるヒータからの熱伝達を改善して加硫を効率よく行うために、トレッド成形部ａ１の肉厚を減じることが望まれているが、係る場合には、前記トレッド成形部ａ１の塑性変形はより顕著となる。   On the other hand, when the tread forming mold b1 of the vulcanization mold b is closed, the groove forming protrusion d for forming the tread groove first hits the surface of the unvulcanized tire t. In vulcanization molding using the rigid core a, The internal volume between the vulcanization mold b and the rigid core a when the vulcanization mold b is closed is configured to substantially match the volume of the unvulcanized tire t. Therefore, when the groove forming protrusion d is embedded in the unvulcanized tire t when the mold is closed, a sufficient space for the rubber to escape is not formed, and a large pressure acts on the tread forming portion a1 of the rigid core a. However, the tread molding part a1 tends to bend inward in the radial direction and cause plastic deformation. Particularly in recent years, in order to improve heat transfer from the heater provided in the rigid core a and efficiently perform vulcanization, it is desired to reduce the thickness of the tread molding part a1, The plastic deformation of the tread molding part a1 becomes more remarkable.

なお下記の特許文献１には、金型閉時の圧力増加を抑制するため、各中子セグメントｃを半径方向に分割した熱膨張率の異なる少なくとも２つのセグメント体にて構成するとともに、この２つのセグメント体の熱膨張率の比（大／小）を３以上に設定することが提案されている。しかし、この提案では、セグメント体の個数が増えてしまい、剛性中子ａを分解してタイヤから取り外す手間が増加する。又内部にヒータ収容用の腔部を設けた中空な剛性中子ａへの採用は難しい。   In Patent Document 1 below, in order to suppress an increase in pressure when the mold is closed, each core segment c is composed of at least two segment bodies having different thermal expansion coefficients divided in the radial direction. It has been proposed to set the ratio (large / small) of the thermal expansion coefficients of two segment bodies to 3 or more. However, in this proposal, the number of segment bodies increases, and the effort to disassemble and remove the rigid core a from the tire increases. Moreover, it is difficult to employ the hollow rigid core a having a heater accommodating cavity therein.

特開２００６−２６４０１８号公報JP 2006-264018 A

このような状況に鑑み本発明者が研究した結果、前記塑性変形は、主に、前記第２の中子セグメントｃ２に発生することが判明した。その原因は明らかではないが、有限要素法を用いてコンピュータ解析を行ったところ、加硫成型時、各中子セグメントｃの外面にほぼ均一な圧力が作用するものの、構造上の影響により前記第２の中子セグメントｃ２の側に応力が集中する傾向があり、その結果、図５（Ｂ）に示すように、第２の中子セグメントｃ２に塑性変形が発生することが判明した。   As a result of research conducted by the present inventors in view of such circumstances, it has been found that the plastic deformation mainly occurs in the second core segment c2. The cause is not clear, but when a computer analysis was performed using the finite element method, a substantially uniform pressure was applied to the outer surface of each core segment c during vulcanization molding. It has been found that the stress tends to concentrate on the side of the second core segment c2, and as a result, as shown in FIG. 5B, plastic deformation occurs in the second core segment c2.

そして又、第２の中子セグメントｃ２のトレッド成形部の周方向の端部に、周方向巾が減じる向きにへこむ凹み部を設け、特に変形しやすいタイヤ赤道側で受圧面積を減じて圧力負担を軽減することにより、第２の中子セグメントｃ２の側への応力集中を緩和でき、塑性変形を抑制しうることを見出し得た。   In addition, a concave portion that is recessed in the direction in which the circumferential width is reduced is provided at the circumferential end of the tread molding portion of the second core segment c2, and the pressure load is reduced by reducing the pressure receiving area on the tire equator side, which is particularly easily deformed. It was found that the stress concentration on the second core segment c2 side can be alleviated and the plastic deformation can be suppressed by reducing.

すなわち本発明は、第２の中子セグメントのトレッド成形部の周方向の端部に、かつトレッド端縁間に、周方向巾が減じる向きにへこむ凹み部を形成し、かつ第１の中子セグメントのトレッド成形部の周方向の端部に、前記凹み部と嵌り合う嵌合凸部を形成することを基本として、トレッド成形部の肉厚を減じて熱伝導を改善しながら、前記第２の中子セグメントのトレッド成形部に生じる塑性変形を抑制でき、空気入りタイヤを高品質で形成しうるタイヤ加硫用の剛性中子を提供することを目的としている。   That is, the present invention forms a recessed portion that dents in the direction in which the circumferential width decreases in the circumferential end of the tread forming portion of the second core segment and between the tread edges, and the first core On the basis of forming a fitting convex part that fits into the concave part at the circumferential end of the tread molded part of the segment, the thickness of the tread molded part is reduced and the heat conduction is improved. An object of the present invention is to provide a rigid core for tire vulcanization that can suppress plastic deformation occurring in a tread molding portion of a core segment and can form a pneumatic tire with high quality.

上記課題を解決するために、本願請求項１の発明は、タイヤトレッドの内表面を形成するトレッド成形部と、そのタイヤ軸方向両端から半径方向内方にのびかつタイヤサイドウォールの内表面を形成する一対のサイドウォール成形部と、各前記サイドウォール成形部の半径方向内端に連なりかつタイヤビードの内表面を形成するビード成形部とを有するトロイド状の中空な中子本体を具えるタイヤ加硫用の剛性中子であって、
前記中子本体は、タイヤ周方向に分割される複数の中子セグメントからなり、
かつ前記複数の中子セグメントは、周方向巾が大、かつ周方向両端の分割面を、半径方向内方に向かって周方向巾が減じる向きに傾斜する内向き傾斜面とした第１の中子セグメントと、
前記第１の中子セグメントとは周方向に交互に配され、しかも周方向巾が小、かつ周方向両端の分割面を、半径方向内方に向かって周方向巾が増す向きに傾斜するとともに前記内向き傾斜面と突き合わされる外向き傾斜面とした第２の中子セグメントとからなるとともに、
前記第２の中子セグメントは、そのトレッド成形部の少なくとも一方の周方向の端部に、かつトレッド端縁間に、周方向巾が減じる向きにへこむ凹み部が形成され、かつ前記第１の中子セグメントは、そのトレッド成形部の周方向の端部に、前記凹み部と嵌り合う嵌合凸部が形成されることを特徴としている。 In order to solve the above-mentioned problems, the invention of claim 1 of the present application forms a tread molding portion that forms the inner surface of the tire tread, and forms the inner surface of the tire sidewall extending radially inward from both ends in the tire axial direction. A tire core including a toroidal hollow core body having a pair of sidewall molding portions and a bead molding portion that is connected to a radially inner end of each of the sidewall molding portions and forms an inner surface of the tire bead. A rigid core for sulfur,
The core body consists of a plurality of core segments divided in the tire circumferential direction,
In addition, the plurality of core segments have a first circumferential center having a large circumferential width, and split surfaces at both circumferential ends are inwardly inclined surfaces that incline in a direction in which the circumferential width decreases toward the inside in the radial direction. Child segments,
The first core segments are alternately arranged in the circumferential direction, have a small circumferential width, and incline the dividing surfaces at both ends in the circumferential direction so that the circumferential width increases inward in the radial direction. A second core segment that is an outwardly inclined surface that faces the inwardly inclined surface, and
The second core segment has a recess that is recessed in a direction in which a circumferential width is reduced, at a circumferential end of at least one of the tread molding portions, and between the tread edges. The core segment is characterized in that a fitting convex portion that fits into the concave portion is formed at an end portion in a circumferential direction of the tread molding portion.

又請求項２の発明では、前記第２の中子セグメントのトレッド成形部におけるトレッド端縁側の周方向端を通るタイヤ軸方向線を基準線としたとき、前記凹み部は、前記基準線からの周方向の凹み量が最大となる最大凹み部分が、タイヤ赤道上に位置することを特徴としている。   In the invention of claim 2, when the tire axial direction line passing through the circumferential end on the tread edge side in the tread forming portion of the second core segment is used as a reference line, the recessed portion is separated from the reference line. The maximum dent portion where the dent amount in the circumferential direction is maximum is located on the tire equator.

又請求項３の発明では、前記凹み部は、前記凹み量の最大値Ｌ１max を、前記トレッド成形部の軸方向巾Ｗの５〜５０％としたことを特徴としている。   According to a third aspect of the present invention, the concave portion has a maximum value L1max of the concave amount of 5 to 50% of an axial width W of the tread molded portion.

又請求項４の発明では、前記凹み部は、タイヤ赤道上に中心を有する凹円弧部を含む湾曲形状をなすことを特徴としている。   According to a fourth aspect of the present invention, the concave portion has a curved shape including a concave arc portion having a center on the tire equator.

又請求項５の発明では、前記凹み部は、タイヤ赤道上に頂部を有する略三角形状をなすことを特徴としている。   According to a fifth aspect of the present invention, the concave portion has a substantially triangular shape having a top on the tire equator.

本発明は叙上の如く、分割面を内向き傾斜面とした第１の中子セグメントと、分割面を外向き傾斜面とした第２の中子セグメントとから構成される中子本体において、第２の中子セグメントのトレッド成形部の周方向の端部に、かつトレッド端縁間に、周方向巾が減じる向きにへこむ凹み部を形成し、かつ第１の中子セグメントのトレッド成形部の周方向の端部に、前記凹み部と嵌り合う嵌合凸部を形成している。   As described above, the present invention provides a core body composed of a first core segment having a dividing surface as an inwardly inclined surface and a second core segment having a dividing surface as an outwardly inclined surface, Formed in the circumferential end of the tread forming portion of the second core segment and between the tread edges is a recess recessed in a direction in which the circumferential width is reduced, and the tread forming portion of the first core segment The fitting convex part which fits into the said recessed part is formed in the edge part of this circumferential direction.

この凹み部は、トレッド成形部において最も変形しやすいタイヤ赤道側での受圧面積を減じて圧力負担を軽減することができる。その結果、第２の中子セグメントｃ２の側への応力集中を緩和でき、トレッド成形部の肉厚を減じて熱伝導を改善しながら、第２の中子セグメントのトレッド成形部に生じる塑性変形を抑制しうる。   The recessed portion can reduce the pressure receiving area on the tire equator side that is most easily deformed in the tread molding portion, thereby reducing the pressure load. As a result, the stress concentration on the second core segment c2 side can be alleviated, and the plastic deformation that occurs in the tread molded portion of the second core segment while reducing the wall thickness of the tread molded portion and improving the heat conduction. Can be suppressed.

本発明の剛性中子の一実施例を示す子午断面図である。It is meridional sectional drawing which shows one Example of the rigid core of this invention. 中子本体の側面図である。It is a side view of a core main body. 中子本体の斜視図である。It is a perspective view of a core main body. 中子本体のトレッド成形部の外表面の一部を平面に展開した展開図である。It is the expanded view which expand | deployed a part of outer surface of the tread molding part of a core main body on the plane. （Ａ）、（Ｂ）は本発品と従来品との塑性変形状態を荷重シミュレーションによって示す斜視図である。(A), (B) is a perspective view which shows the plastic deformation state of this product and a conventional product by load simulation. 中子本体の分解方法を説明する側面図である。It is a side view explaining the decomposition | disassembly method of a core main body. （Ａ）〜（D）は、凹み部の他の実施例を示す展開図である。(A)-(D) are expanded views which show the other Example of a dent part. （Ａ）、（B）は、凹み部のさらに他の実施例を示す展開図である。(A), (B) is an expanded view which shows other Example of a dent part. （Ａ）、（Ｂ）は従来の剛性中子を説明する断面図、及び側面図である。(A), (B) is sectional drawing explaining the conventional rigid core, and a side view.

以下、本発明の実施の形態について、詳細に説明する。
図１に示すように、本実施形態のタイヤ加硫用の剛性中子１は、空気入りタイヤＴのタイヤトレッドＴ２の内表面を形成するトレッド成形部２と、そのタイヤ軸方向両端から半径方向内方にのびかつタイヤサイドウォールＴ３の内表面を形成する一対のサイドウォール成形部３と、各前記サイドウォール成形部３の半径方向内端に連なりかつタイヤビードＴ４の内表面を形成するビード成形部４とを有するトロイド状の中空の中子本体５を具える。 Hereinafter, embodiments of the present invention will be described in detail.
As shown in FIG. 1, a rigid core 1 for tire vulcanization according to this embodiment includes a tread molding portion 2 that forms an inner surface of a tire tread T2 of a pneumatic tire T, and radial directions from both ends in the tire axial direction. A pair of sidewall molding portions 3 extending inward and forming the inner surface of the tire sidewall T3, and bead molding that is connected to the radially inner end of each sidewall molding portion 3 and forms the inner surface of the tire bead T4 A toroidal hollow core body 5 having a portion 4.

この中子本体５は、例えばアルミ合金等の熱伝導に優れる金属材料を用いて形成される剛体であって、その外表面上で、タイヤ構成部材である例えばインナーライナゴム、カーカスプライ、ベルトプライ、サイドウォールゴム、トレッドゴム等を順次貼り付けることにより、未加硫タイヤＴが形成される。又この未加硫タイヤＴを前記剛性中子１ごと加硫金型内に投入することにより、内型である剛性中子１と外型である加硫金型との間で、タイヤの加硫成形が行われる。従って前記中子本体５では、その外周面は、製品タイヤの内腔面（内表面）に合った形状にて形成されるとともに、その内部には加硫用のヒータｅを収容するための腔部Ｈが形成される。   The core body 5 is a rigid body formed of a metal material that is excellent in heat conduction, such as an aluminum alloy, and has tire components such as an inner liner rubber, a carcass ply, and a belt ply on its outer surface. Then, the unvulcanized tire T is formed by sequentially attaching the sidewall rubber, the tread rubber, and the like. Further, by introducing the unvulcanized tire T together with the rigid core 1 into the vulcanization mold, the tire is vulcanized between the rigid core 1 as the inner mold and the vulcanization mold as the outer mold. Sulfur molding is performed. Accordingly, in the core body 5, the outer peripheral surface is formed in a shape that matches the inner cavity surface (inner surface) of the product tire, and a cavity for accommodating the vulcanizing heater e therein. Part H is formed.

又前記中子本体５は、図２、３に示すように、分割面Ｓによってタイヤ周方向に分割される複数の中子セグメント６からなるとともに、この複数の中子セグメント６は、周方向に交互に配される第１、第２の中子セグメント６Ａ、６Ｂから構成される。なお各中子セグメント６は、その内孔８に配される内リング２０によって半径方向内方への移動が阻止されトロイド状に保持される。   2 and 3, the core body 5 includes a plurality of core segments 6 that are divided in the tire circumferential direction by the dividing surface S. The plurality of core segments 6 are arranged in the circumferential direction. The first and second core segments 6A and 6B are alternately arranged. Each core segment 6 is held in a toroidal shape by being prevented from moving radially inward by an inner ring 20 disposed in the inner hole 8 thereof.

前記第１の中子セグメント６Ａは、周方向巾が大であり、かつ周方向両端の分割面Ｓを、半径方向内方に向かって周方向巾が減じる向きに傾斜する内向き傾斜面７Ａとしている。又前記第２の中子セグメント６Ｂは、周方向巾が小であり、かつ周方向両端の分割面Ｓを、半径方向内方に向かって周方向巾が増す向きに傾斜するとともに前記内向き傾斜面７Ａと突き合わされる外向き傾斜面７Ｂとしている。   The first core segment 6A has a large circumferential width, and the split surfaces S at both ends in the circumferential direction are inwardly inclined surfaces 7A that incline in a direction in which the circumferential width decreases toward the inside in the radial direction. Yes. The second core segment 6B has a small circumferential width, and the dividing surfaces S at both ends in the circumferential direction are inclined in the direction of increasing the circumferential width inward in the radial direction and the inward inclination. An outwardly inclined surface 7B that is abutted against the surface 7A is used.

そして本実施形態の中子本体５では、図４にトレッド成形部２の外表面を平面に展開して示すように、第２の中子セグメント６Ｂのトレッド成形部２は、その少なくとも一方の周方向の端部Ａｅに、かつトレッド端縁Ｔｅ，Ｔｅ間に、周方向巾が減じる向きにへこむ凹み部１０を具える。本例では両側の周方向の端部Ａｅ、Ａｅに、それぞれ凹み部１０が配される場合が示される。又前記第１の中子セグメント６Ａのトレッド成形部２の周方向の端部には、前記凹み部１０と嵌り合う嵌合凸部１１が形成される。   In the core body 5 of the present embodiment, as shown in FIG. 4, the outer surface of the tread molding portion 2 is developed in a plane, and the tread molding portion 2 of the second core segment 6B has at least one circumference thereof. A dent 10 is provided at the end Ae in the direction and between the tread edges Te and Te so as to dent in the direction in which the circumferential width decreases. In this example, the case where the recessed part 10 is each distribute | arranged to the edge parts Ae and Ae of the circumferential direction of both sides is shown. A fitting convex portion 11 that fits with the concave portion 10 is formed at an end portion in the circumferential direction of the tread molding portion 2 of the first core segment 6A.

前記凹み部１０では、前記第２の中子セグメント６Ｂのトレッド成形部２におけるトレッド端縁Ｔｅ側の周方向端Ｐを通るタイヤ軸方向線を基準線Ｘｐとしたとき、この基準線Ｘｐからの周方向の凹み量Ｌ１が最大となる最大凹み部分１０Ａが、トレッド中央領域内に位置することが好ましい。本例では、前記最大凹み部分１０Ａが、タイヤ赤道Ｃ上に位置するより好ましい場合が示されている。なおトレッド中央領域とは、タイヤ赤道Ｃを中心とした、トレッド成形部２の軸方向巾Ｗの１／２の巾領域を意味する。又前記軸方向巾Ｗとは、図１に示すようにトレッド成形部２の内周面２ｓにおける最大巾として定義される。又前記トレッド端縁Ｔｅも、前記トレッド成形部２の内周面２ｓのタイヤ軸方向外端縁として定義される。   When the tire axial direction line passing through the circumferential end P on the tread edge Te side in the tread forming portion 2 of the second core segment 6B is defined as the reference line Xp, It is preferable that the largest recessed portion 10A where the circumferential recessed amount L1 is maximum is located in the tread central region. In this example, the case where the said largest dent part 10A is more preferable located on the tire equator C is shown. The tread central region means a width region that is ½ of the axial width W of the tread molded portion 2 with the tire equator C as the center. The axial width W is defined as the maximum width on the inner peripheral surface 2s of the tread molded portion 2 as shown in FIG. The tread edge Te is also defined as an outer edge in the tire axial direction of the inner peripheral surface 2s of the tread molded part 2.

又前記凹み部１０は、本例の如く、タイヤ赤道Ｃ上に中心を有する凹円弧部１３ａを含む滑らかな湾曲形状に形成されるのが好ましい。本例では、前記凹み部１０が、凹円弧部１３ａの軸方向両端に、該凹円弧部１３ａと前記基準線Ｘｐとを滑らかに継ぐ凸円弧部１３ｂを設けた片側略Ｓ状の湾曲形状に形成されたものが例示される。なお前記凹円弧部１３ａ及び／又は凸円弧部１３ｂは、単一円弧で形成しうる他、複数の曲率半径の円弧を組み合わせて形成することができ、又その一部を直線にて形成することもできる。   Moreover, it is preferable that the said recessed part 10 is formed in the smooth curve shape containing the concave circular arc part 13a which has a center on the tire equator C like this example. In this example, the concave portion 10 has a substantially S-shaped curved shape on one side provided with a convex arc portion 13b smoothly connecting the concave arc portion 13a and the reference line Xp at both axial ends of the concave arc portion 13a. What is formed is exemplified. The concave arc portion 13a and / or the convex arc portion 13b can be formed as a single arc, or can be formed by combining arcs having a plurality of curvature radii, and a part thereof can be formed as a straight line. You can also.

このような凹み部１０は、トレッド成形部２において最も変形しやすいタイヤ赤道Ｃ側での受圧面積を減じて圧力負担を軽減することができる。その結果、加硫成型時に生じる第２の中子セグメント６Ｂへの応力集中を緩和しうる。従って、前記トレッド成形部の肉厚Ｊ（図１に示す。）を減じて熱伝導を改善しながら、第２の中子セグメント６Ｂに生じる塑性変形を抑制することが可能となり、空気入りタイヤの品質向上を達成しうる。   Such a recessed portion 10 can reduce the pressure load by reducing the pressure receiving area on the tire equator C side that is most easily deformed in the tread molding portion 2. As a result, stress concentration on the second core segment 6B that occurs during vulcanization molding can be reduced. Accordingly, it is possible to suppress the plastic deformation generated in the second core segment 6B while reducing the thickness J (shown in FIG. 1) of the tread molded portion to improve the heat conduction, and the pneumatic tire Quality improvement can be achieved.

なお図５（Ａ）、（Ｂ）に、有限要素法を用いた、コンピュータによる荷重シミュレーションの結果を示す。同図には、半径方向の変形量が１００倍に拡大して示されている。前記凹み部１０を設けた第２の中子セグメント６Ｂ（図５（Ａ）に示す）は、凹み部１０を設けない従来の第２の中子セグメント６Ｂ（図５（Ｂ）に示す）に比して、半径方向内方への変形が大幅に抑制されているのが確認できる。   5A and 5B show the results of a computer load simulation using the finite element method. In the figure, the amount of deformation in the radial direction is shown enlarged 100 times. The second core segment 6B (shown in FIG. 5A) provided with the recessed portion 10 is replaced with the conventional second core segment 6B (shown in FIG. 5B) not provided with the recessed portion 10. In comparison, it can be confirmed that the deformation inward in the radial direction is greatly suppressed.

なお前記凹み部１０の凹み量Ｌ１の最大値Ｌ１max が過小であると、上記効果が充分に発揮されず、逆に大きすぎても、前記第２の中子セグメント６Ｂの剛性が低下して塑性変形しやすくなる。このような観点から前記凹み量Ｌ１の最大値Ｌ１max は、トレッド成形部２の前記軸方向巾Ｗの５〜５０％の範囲が好ましい。   If the maximum value L1max of the dent amount L1 of the dent part 10 is too small, the above effect cannot be exhibited sufficiently, and conversely, if it is too large, the rigidity of the second core segment 6B is reduced and plasticity is increased. It becomes easy to deform. From such a viewpoint, the maximum value L1max of the dent amount L1 is preferably in the range of 5 to 50% of the axial width W of the tread molded part 2.

又前記中子本体５は、第２の中子セグメント６Ｂから順次半径方向内方に一つずつ移動させることで、その内孔８側から分解して取り外すことができる。このとき、図６に示すように、第１の中子セグメント６Ａにおけるトレッド成形部２の周方向両端部Ｂｅ、Ｂｅ間の周方向の直線距離の最大値Ｌ２は、前記内孔８の直径Ｄより小であることが、中子本体５を分解して取り外す上で必要である。   The core body 5 can be disassembled and removed from the inner hole 8 side by moving one by one in the radial direction sequentially from the second core segment 6B. At this time, as shown in FIG. 6, the maximum value L2 of the circumferential linear distance between the circumferential end portions Be and Be of the tread molding portion 2 in the first core segment 6A is the diameter D of the inner hole 8. A smaller size is necessary for disassembling and removing the core body 5.

次に、図７（Ａ）〜（Ｄ）、８（Ａ）、（Ｂ）に、前記凹み部１０の他の実施例を示す。図７（Ａ）は、凹み部１０が、タイヤ赤道Ｃ上に凹み量Ｌ１が最大となる頂部Ｑ１（最大凹み部分１０Ａに相当する。）を有する略三角形状をなす場合が示される。又図７（Ｂ）、（Ｃ）は、凹み部１０が、タイヤ赤道Ｃ上に、凹み量Ｌ１が最大となる軸方向の横辺Ｑ２（最大凹み部分１０Ａに相当する。）を有する矩形状、及び台形状をなす場合が示される。又図７（Ｄ）は、凹み部１０が、タイヤ赤道Ｃ上に、凹み量Ｌ１が最大となる軸方向の横辺Ｑ２（最大凹み部分１０Ａに相当する。）を有する階段状をなす場合が示される。又図８（Ａ）は、凹み部１０が、タイヤ赤道Ｃの両側に、凹み量Ｌ１が最大となる軸方向の横辺Ｑ３、Ｑ３（最大凹み部分１０Ａに相当する。）を有する場合が示されている。又図８（B）は、周方向の端部Ａｅに、例えば略三角形状をなす複数（例えば2つ）の凹み部１０が形成された場合が示されており、本例では、各凹み部１０の最大凹み部分１０Ａは、トレッド中央領域に位置している。   Next, FIGS. 7 (A) to (D), 8 (A), and (B) show another embodiment of the recess 10. FIG. 7A shows a case where the recess 10 has a substantially triangular shape having a peak Q1 (corresponding to the maximum recess 10A) on the tire equator C where the recess L1 is maximum. 7B and 7C, the recess 10 has a rectangular shape on the tire equator C having an axial lateral side Q2 (corresponding to the maximum recess 10A) where the recess amount L1 is maximum. And a trapezoidal shape are shown. In FIG. 7D, the recess 10 may have a stepped shape on the tire equator C having an axial lateral side Q2 (corresponding to the maximum recess 10A) where the recess L1 is maximum. Indicated. FIG. 8A shows a case where the dent portion 10 has lateral sides Q3 and Q3 (corresponding to the maximum dent portion 10A) on both sides of the tire equator C in the axial direction where the dent amount L1 is maximum. Has been. FIG. 8B shows a case where a plurality of (for example, two) recesses 10 having a substantially triangular shape, for example, are formed at the circumferential end Ae. In this example, each recess The ten largest recessed portions 10A are located in the tread central region.

これらは何れも、タイヤ赤道Ｃ側での受圧面積を減じて圧力負担を軽減することができ、加硫時における第２の中子セグメント６Ｂの変形を低減することができる。なお嵌合凸部１１は、各凹み部１０に嵌り合う形状に形成される。   All of these can reduce the pressure load by reducing the pressure receiving area on the tire equator C side, and can reduce the deformation of the second core segment 6B during vulcanization. The fitting convex portion 11 is formed in a shape that fits into each of the concave portions 10.

なお前記中子本体５では、前記第２の中子セグメント６Ｂのトレッド成形部２の一方の周方向の端部Ｂｅのみに凹み部１０を形成し、他方の周方向の端部Ｂｅを従来と同様、前記基準線Ｘｐに沿う軸方向線にて終端させることもできる。また凹み部１０はタイヤ赤道Ｃを中心とした対称形状に、あるいはタイヤ赤道Ｃを中心とした対称位置に形成するのが好ましい。   In the core body 5, the recessed portion 10 is formed only in one circumferential end Be of the tread molding portion 2 of the second core segment 6B, and the other circumferential end Be is compared with the conventional one. Similarly, it can be terminated at an axial line along the reference line Xp. The recess 10 is preferably formed in a symmetrical shape with the tire equator C as the center, or in a symmetrical position with the tire equator C as the center.

以上、本発明の特に好ましい実施形態について詳述したが、本発明は図示の実施形態に限定されることなく、種々の態様に変形して実施しうる。   As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

本発明の効果を確認するため、図２に示す構造をなす中子セグメントを用いた中子本体を表１の仕様で試作した。そしてこの中子本体を用いて空気入りタイヤを１０回形成し、その後、第２の中子セグメントにおけるトレッド成形部のタイヤ赤道上での塑性変形量を測定した。各中子本体とも、凹み部以外は実質的に同仕様である。
なお中子本体は、アルミニューム合金展伸材（５０００系合金）を用い、
トレッド成形部における厚さ： １８．１ｍｍ、
第２の中子セグメントにおけるトレッド成形部の軸方向巾Ｗ：１６２ｍｍ
第２の中子セグメントにおけるトレッド成形部の周方向巾（基準線Ｘｐ、Ｘｐ間の距離）：１２２ｍｍ
としている。 In order to confirm the effect of the present invention, a core body using a core segment having the structure shown in FIG. A pneumatic tire was formed 10 times using this core body, and then the amount of plastic deformation on the tire equator of the tread molded portion in the second core segment was measured. Each core body has substantially the same specifications except for the recess.
The core body uses an aluminum alloy wrought material (5000 series alloy),
Thickness in the tread molding part: 18.1 mm,
Axial width W of the tread molding part in the second core segment W: 162 mm
Circumferential width of the tread molding portion in the second core segment (distance between the reference lines Xp and Xp): 122 mm
It is said.

Figure 0005406701
Figure 0005406701

表に示すように実施例のものは、第２の中子セグメントにおけるトレッド成形部の塑性変形を大幅に抑制しうるのが確認できる。   As shown in the table, it can be confirmed that in the example, the plastic deformation of the tread molded portion in the second core segment can be significantly suppressed.

１ 剛性中子
２ トレッド成形部
３ サイドウォール成形部
４ ビード成形部
５ 中子本体
６ 中子セグメント
６Ａ 第１の中子セグメント
６Ｂ 第２の中子セグメント
７Ａ 内向き傾斜面
７Ｂ 外向き傾斜面
１０ 凹み部
１１ 嵌合凸部
１３ａ 凹円弧部 DESCRIPTION OF SYMBOLS 1 Rigid core 2 Tread molding part 3 Side wall molding part 4 Bead molding part 5 Core main body 6 Core segment 6A First core segment 6B Second core segment 7A Inward inclined surface 7B Outward inclined surface 10 Concave part 11 Fitting convex part 13a Concave arc part

Claims (5)

タイヤトレッドの内表面を形成するトレッド成形部と、そのタイヤ軸方向両端から半径方向内方にのびかつタイヤサイドウォールの内表面を形成する一対のサイドウォール成形部と、各前記サイドウォール成形部の半径方向内端に連なりかつタイヤビードの内表面を形成するビード成形部とを有するトロイド状の中空な中子本体を具えるタイヤ加硫用の剛性中子であって、
前記中子本体は、タイヤ周方向に分割される複数の中子セグメントからなり、
かつ前記複数の中子セグメントは、周方向巾が大、かつ周方向両端の分割面を、半径方向内方に向かって周方向巾が減じる向きに傾斜する内向き傾斜面とした第１の中子セグメントと、
前記第１の中子セグメントとは周方向に交互に配され、しかも周方向巾が小、かつ周方向両端の分割面を、半径方向内方に向かって周方向巾が増す向きに傾斜するとともに前記内向き傾斜面と突き合わされる外向き傾斜面とした第２の中子セグメントとからなるとともに、
前記第２の中子セグメントは、そのトレッド成形部の少なくとも一方の周方向の端部に、かつトレッド端縁間に、周方向巾が減じる向きにへこむ凹み部が形成され、かつ前記第１の中子セグメントは、そのトレッド成形部の周方向の端部に、前記凹み部と嵌り合う嵌合凸部が形成されることを特徴とするタイヤ加硫用の剛性中子。 A tread molding portion that forms the inner surface of the tire tread, a pair of sidewall molding portions that extend radially inward from both ends in the tire axial direction and forms the inner surface of the tire sidewall, and each of the sidewall molding portions A rigid core for vulcanizing a tire comprising a toroidal hollow core body having a bead molding portion that is continuous with a radially inner end and forms an inner surface of a tire bead,
The core body consists of a plurality of core segments divided in the tire circumferential direction,
In addition, the plurality of core segments have a first circumferential center having a large circumferential width, and split surfaces at both circumferential ends are inwardly inclined surfaces that incline in a direction in which the circumferential width decreases toward the inside in the radial direction. Child segments,
The first core segments are alternately arranged in the circumferential direction, have a small circumferential width, and incline the dividing surfaces at both ends in the circumferential direction so that the circumferential width increases inward in the radial direction. A second core segment that is an outwardly inclined surface that faces the inwardly inclined surface, and
The second core segment has a recess that is recessed in a direction in which a circumferential width is reduced, at a circumferential end of at least one of the tread molding portions, and between the tread edges. The core segment is a rigid core for tire vulcanization, wherein a fitting convex portion that fits into the concave portion is formed at an end portion in a circumferential direction of the tread molded portion. 前記第２の中子セグメントのトレッド成形部におけるトレッド端縁側の周方向端を通るタイヤ軸方向線を基準線としたとき、前記凹み部は、前記基準線からの周方向の凹み量が最大となる最大凹み部分が、タイヤ赤道上に位置することを特徴とする請求項１記載のタイヤ加硫用の剛性中子。   When the tire axial direction line passing through the circumferential end on the tread edge side in the tread forming portion of the second core segment is a reference line, the recessed portion has a maximum amount of recessed in the circumferential direction from the reference line. The rigid core for tire vulcanization according to claim 1, wherein the largest recessed portion is located on the tire equator. 前記凹み部は、前記凹み量の最大値Ｌ１max を、前記トレッド成形部の軸方向巾Ｗの５〜５０％としたことを特徴とする請求項２記載のタイヤ加硫用の剛性中子。   The rigid core for tire vulcanization according to claim 2, wherein the dent portion has a maximum value L1max of the dent amount of 5 to 50% of an axial width W of the tread molded portion. 前記凹み部は、タイヤ赤道上に中心を有する凹円弧部を含む湾曲形状をなすことを特徴とする請求項１〜３の何れかに記載のタイヤ加硫用の剛性中子。   The rigid core for tire vulcanization according to any one of claims 1 to 3, wherein the concave portion has a curved shape including a concave arc portion having a center on the tire equator. 前記凹み部は、タイヤ赤道上に頂部を有する略三角形状をなすことを特徴とする請求項１〜３の何れかに記載のタイヤ加硫用の剛性中子。   The rigid core for tire vulcanization according to any one of claims 1 to 3, wherein the recess has a substantially triangular shape having a top on the tire equator.
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