JP2017047579A - Manufacturing method for tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a tire that can inhibit uneven wear of a core member while preventing the member from losing a shape.SOLUTION: A manufacturing method for a core member 2 comprises a coating step, a removing step and a winding step. When the number of outer loops 4 forming an outer surface of the core member 2 of loops is set to Lo, the number of the outer loops 4 having coating layers 12 formed therein is set to Loc, the number of inner loops 6 surrounded with the outer loops 4 is set to Li and the number of the inner loops 6 having coating layers 12 formed therein is set to Lic in a cross section perpendicular to a circumference direction of the core member 2, the core member 2 satisfies the following relational expression: Loc/Lo>Lic/Li, and is vulcanized to form a core of a tire.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a tire manufacturing method. Specifically, the present invention relates to a method for manufacturing a core member that forms a core of a tire.

  The tire has a bead. This bead has a ring-shaped core. The tire is fitted to the rim by the core. Some cores are formed by winding a non-stretchable wire in the circumferential direction. In the cross section perpendicular to the circumferential direction of the core, the cross sections of the wires are arranged in the axial direction and the radial direction. In the present invention, such a core structure is referred to as a strand structure.

  This core is obtained by vulcanizing the core member. In this core member manufacturing method, a rubber coating layer is formed on the outer peripheral surface of the wire. The core member is obtained by winding this wire. This rubber coating layer suppresses deformation of the wound core member.

  In the tire manufacturing method, this core member is combined with members constituting other parts to form a raw cover (raw tire). This raw cover is vulcanized to obtain a tire.

  JP 2012-214191 A describes a core member having a strand structure. In this core member, a rubber coating layer is formed on the wire located in the inner region of the core member. The rubber coating layer is not formed on the wire surface located on the outermost side of the core member. This core member prevents the deformation of the shape without reducing the adhesive force with the members constituting the other parts.

JP 2012-214191 A

  The supple deformation of the tire core contributes to the supple deformation of the bead. The flexible deformation of the bead contributes to improvement of tire uniformity. Further, the core is deformed in this manner, whereby the core is dispersed in the circumferential direction. From these viewpoints, the core is preferably deformed to some extent with respect to the external force. Thereby, the uniformity can be improved. Thereby, suppression of uneven wear of the tread can be achieved.

  As described above, the core member is formed by winding the wire on which the rubber coating layer is formed in order to prevent the core member from being deformed. A core obtained from such a core member is difficult to deform. This core is not easily deformed by an external force. Tires using this core have room for improvement from the viewpoint of uniformity. This tire has room for improvement from the viewpoint of suppressing uneven wear.

  An object of the present invention is to provide a method for manufacturing a tire in which uneven wear is suppressed while suppressing deformation of the core member.

The manufacturing method of the core member according to the present invention includes:
A coating process in which a coating layer is formed by forming a coating layer on the outer peripheral surface of the wire;
A removal step in which a part of the coating layer of the coating wire is removed to obtain a wire member;
The wire member is wound to form a plurality of loops that circulate in the circumferential direction to obtain a core member made of a bundle of the loops.
In the cross section perpendicular to the circumferential direction of the core member, the number of outer loops forming the outer surface of the core member among the loops is Lo, the number of outer loops on which the coating layer is formed is Loc, When the number of inner loops surrounded by the outer loop is Li and the number of inner loops on which the coating layer is formed is Lic, the core member satisfies the following relational expression. The core member is vulcanized to form the tire core.
Loc / Lo> Lic / Li

  Preferably, the ratio of Loc to Lo of the outer loop is 0.6 or more.

  Preferably, the ratio of Lic to Li in the inner loop is 0.3 or less.

Preferably, the ratio of Loc to Lo of the outer loop and the ratio of Lic to Li of the inner loop satisfy the following relational expression.
(Loc / Lo) / (Lic / Li) ≧ 2

  Preferably, in the removing step, the thickness tc of the coating layer is gradually reduced toward the end of the coating layer at the end of the coating layer of the wire member.

  Preferably, in the winding step, the positions of the ends of the coating layers of the adjacent loops are shifted in the circumferential direction, and the wire member is wound.

Preferably, the bundle of loops of the core member is divided into an upper loop positioned on the radially outer side and a lower loop positioned on the radially inner side. The number of upper loops is Lu, the number of upper loops on which the coating layer is formed is Luc, the number of lower loops is Ld, and the number of lower loops on which the coating layer is formed is Ldc. And At this time, the following relational expression is satisfied.
Ldc / Ld> Luc / Lu

  Preferably, in this manufacturing method, all of the outer loops are provided with the coating layer. All of the inner loops do not include the coating layer.

The tire manufacturing method according to the present invention includes:
A core member forming step for obtaining a core member that is vulcanized to form a core;
A preforming step in which a raw cover is formed by laminating the core member and other constituent members;
A vulcanization molding step in which the raw cover is vulcanized with a mold to obtain a tire.
The core member forming step includes
A coating process in which a coating layer is obtained by forming a coating layer on the outer peripheral surface of the wire;
A removal step in which a part of the coating layer of the coating wire is removed to obtain a wire member,
A plurality of loops made of the wire member wound around the wire member to form a core member made of a bundle of the loops.
In the cross section perpendicular to the circumferential direction of the core member, Lo is the number of outer loops constituting the outer surface of the core member, and Lo is the number of outer loops on which the coating layer is formed. When the number of inner loops surrounded by Li is Li and the number of inner loops on which the coating layer is formed is Lic among the inner loops, the following relational expression is satisfied.
Loc / Lo> Lic / Li

The manufacturing equipment for the core member according to the present invention includes a coating apparatus for forming a coating wire by forming a coating layer on the outer peripheral surface of the wire, and a removal for removing a part of the coating layer of the coating wire to form a wire member. A device and a control device.
The said control apparatus is equipped with the function which controls the range which removes the said coating layer of the said coating wire with the said removal apparatus with the position in the core member formed by the said wire member being wound.

The tire core according to the present invention includes a bundle of a plurality of loops. The bundle is formed by winding a wire in the circumferential direction. In the cross section perpendicular to the circumferential direction of the core, the number of outer loops forming the outer surface of the core among the loops is Lo, and the number of outer loops having a coating layer formed on the outer peripheral surface of the wires is Loc. The number of inner loops surrounded by outer loops is Li, and the number of inner loops in which a coating layer is formed on the outer peripheral surface of the wire is Lic. At this time, the core satisfies the following relational expression.
Loc / Lo> Lic / Li

The tire according to the present invention includes a tread, a pair of sidewalls, a pair of beads, and a carcass. The tread includes a tread surface that contacts the road surface. Each sidewall extends substantially inward in the radial direction from the end of the tread. Each bead is located radially inside the sidewall. The carcass is stretched between one bead and the other bead along the inside of the tread and the sidewall. The bead includes a core. The core includes a bundle composed of a plurality of loops. The bundle is formed by winding a wire in the circumferential direction. In the cross section perpendicular to the circumferential direction, the number of outer loops forming the outer surface of the core among the loops is Lo, the number of outer loops having a coating layer formed on the outer peripheral surface of the wire is Loc, The number of inner loops surrounded by outer loops is Li, and the number of inner loops having a coating layer formed on the outer peripheral surface of the wire is Lic. At this time, the tire satisfies the following relational expression.
Loc / Lo> Lic / Li

  In the tire manufacturing method according to the present invention, the outer loop of the core member includes a coating layer. Due to this outer loop, the core member is prevented from being deformed. In the inner loop, the ratio of the coating layer is reduced, so that the core obtained from the core member can be easily deformed. The core is deformed to facilitate movement. Thereby, the uniformity of the tire is improved. Uneven wear of the tire is suppressed.

FIG. 1 is a side view of a core member manufactured by the core member manufacturing method according to the present invention. FIG. 2 is a cross-sectional view of the core member taken along line II-II in FIG. FIG. 3 is a conceptual diagram showing manufacturing equipment used in the method for manufacturing a core member according to an embodiment of the present invention. FIG. 4 is a flowchart of the manufacturing method of the core member of FIG. FIG. 5 is an explanatory diagram of a removal process of the manufacturing method of the core member by the manufacturing facility of FIG. FIG. 6A is an explanatory diagram of a winding process of the manufacturing method of the core member by the manufacturing facility of FIG. 3, and FIG. 6B is another explanatory diagram of this winding process, and FIG. These are other explanatory drawings of this winding process. FIG. 7 is still another explanatory view of the winding process of the method of manufacturing the wire member by the manufacturing facility of FIG. FIG. 8 is a flowchart of a tire manufacturing method according to an embodiment of the present invention. FIG. 9 (a) is an explanatory view showing the state of the vulcanization step of the tire manufacturing method according to one embodiment of the present invention, and FIG. 9 (b) shows another state of the vulcanization step. FIG. FIG. 10A is an explanatory view showing a wire member from which the coating layer has been removed by the manufacturing equipment of FIG. 3, and FIG. 9B is another wire from which the coating layer has been removed by the manufacturing equipment of FIG. It is explanatory drawing in which the member was shown. FIG. 11 is a cross-sectional view of a core member according to another embodiment of the present invention.

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

  FIG. 1 shows a core member 2 manufactured by the manufacturing method according to the present invention. The core member 2 has a ring shape. The core member 2 is vulcanized to form the core of the tire T. A point Po in FIG. 1 represents the center position of the core member 2. The alternate long and short dash line L1 is a straight line extending in the radial direction of the core member 2 through the point Po. The diameter of the core member 2 is measured along this straight line L1.

  FIG. 2 shows a cross section taken along line II-II in FIG. This cross section is a cross section perpendicular to the circumferential direction of the core member 2. The vertical direction in FIG. 2 is the radial direction. The core member 2 includes a plurality of outer loops 4 and a plurality of inner loops 6. The outer loop 4 forms the outer surface of the core member 2. The inner loop 6 is located inside the core member 2 and is surrounded by the outer loop 4.

  The core member 2 is formed by winding a single wire member 8 in the circumferential direction. In the present invention, one round of the wire member 8 wound from one end to the one end is referred to as one loop. Further, one round of the one loop that is wound from the position reaching this one end to the position reaching this one end is called another one loop. In the present invention, a plurality of loops (the outer loop 4 and the inner loop 6) are formed from the continuous wire member 8 by winding the wire member 8 in this manner. A plurality of outer loops 4 and a plurality of inner loops 6 are formed by winding the wire member 8. In the cross section of the core member 2, a plurality of wire members 8 are inclined in the axial direction and arranged at substantially equal intervals, and a plurality of wire members 8 are also inclined in the radial direction and arranged at substantially equal intervals. The cross-sectional shape of the core member 2 is a substantially hexagonal shape. The core member 2 has a strand structure formed by winding the wire member 8. Here, the core member 2 is formed from one wire member 8, but may be formed by winding a plurality of wire members.

  The outer loop 4 is formed by coating the outer peripheral surface of the non-stretchable wire 10 with a coating layer 12. The wire 10 is typically a steel wire. This inner loop 6 is formed of this wire 10. The wire 10 of the inner loop 6 is not covered with the coating layer 12. The coating layer 12 is made of unvulcanized rubber. This core member forms the core of the tire 2 through a preforming step and a vulcanizing step described later.

  A two-dot chain line L2 in FIG. 2 represents a boundary line between the third outer loop 4 and the inner loop 6 and the fourth outer loop 4 and the inner loop 6 from the radially inner side. The core member 2 has loops in six stages, from the first outer loop 4 on the radially inner side to the sixth outer loop 4 on the radially outer side. This line L2 indicates the boundary between the upper loop located on the radially outer side and the lower loop located on the radially inner side. The upper loop includes an outer loop 4 and an inner loop 6 that are located radially outward from the line L2. The lower loop includes an outer loop 4 and an inner loop 6 that are located radially inward from the line L2.

  In the present invention, the boundary line between the upper loop and the lower loop is determined as follows. The number of loops that are overlapped in the radial direction of the core member 2 is N. This N is an integer of 3 or more. When N is an odd number of 3 or more, the first loop from the radially inner side to the (((N−1) / 2) +1) th stage is defined as a lower loop, and (((N−1) / 2) +2 ) Set the upper loop from the stage to the Nth stage. When N is an even number of 4 or more, the first loop from the radially inner stage to the (N / 2) th stage is the lower loop, and the (N / 2 + 1) th stage to the Nth stage is the upper loop.

  The bead member manufacturing facility 14 shown in FIG. 3 includes a reel 16, a heater 18, an extruder 20 as a coating device, a removing device 22, a pull roll 24, and a winding former 26. The bead member manufacturing facility 14 includes a control device (not shown). This control device controls the reel 16, the heater 18, the extruder 20, the removing device 22, the pull roll 24, and the winding former 26.

  A wire 10 is wound around the reel 16. In this bead member manufacturing equipment 14, the outer peripheral surface of the wire 10 is coated with rubber to form a coating wire 28. In this bead member manufacturing equipment 14, a part of the coating of the coating wire 28 is removed to form the wire member 8. In the bead member manufacturing equipment 14, the wire member 8 is wound to form the core member 2.

  FIG. 4 shows a method for manufacturing the core member 2. The manufacturing method of the core member 2 includes a feeding process, a preheating process, a coating process, a removing process, a winding process, and a removing process.

  As shown in FIG. 3, in the feeding process, the reel 16 is rotated about its axis. The wire 10 is fed out from the reel 16. The drawn wire 10 is sent to the heater 18.

  In the preheating step, the heater 18 heats the wire 10. The wire 10 is preheated. The wire 10 is sent to the extruder 20.

  In the coating process, the compound rubber is coated on the outer peripheral surface of the wire 10. In the coating process, the compounded rubber is kneaded while being heated. The kneaded compounded rubber is put into the extruder 20. The extruder 20 includes a base set in the cross-sectional shape of the coating wire 28. The compound rubber is coated on the outer peripheral surface of the wire 10 and extruded from the die. Thereby, the coating wire 28 is obtained from the wire 10. This coating wire 28 consists of the wire 10 and the coating layer 12 coat | covered by the outer peripheral surface of the wire 10 (refer FIG. 5). The coating layer 12 is made of compounded rubber. The coating wire 28 is sent to the removing device 22.

  As shown in FIG. 5A, the removing device 22 includes a die 30. In FIG. 5A, the die 30 is separated from the coating wire 28. The die 30 is in a retracted posture. In FIG. 5B, the die 30 is in contact with the wire 10 of the coating wire 28. The coating wire 28 is passed through the die 30 to remove the coating layer 12 on the outer peripheral surface. This die 30 is in the removal posture.

  In the removal process, the removal device 22 removes a part of the coating layer 12 according to an instruction from the control device. The control device distinguishes whether the portion of the coating wire 28 located in the removal device 22 is a portion constituting the outer loop 4 or a portion constituting the inner loop 6 of the core member 2. When the part which comprises the outer loop 4 is located in the removal apparatus 22, a control apparatus makes the dice | dies 30 of the removal apparatus 22 into a retracted posture. When the part which comprises the inner loop 6 is located in the removal apparatus 22, a control apparatus makes the dice | dies 30 a removal attitude | position. Thereby, the coating layer 12 is peeled from the outer peripheral surface of the coating wire 28. The compounded rubber of the coating layer 12 thus peeled off is sent to the extruder 20 and reused. A part of the coating layer 12 of the coating wire 28 is peeled off, and the wire member 8 is obtained. The wire member 8 is sent to the pull roll 24 and the winding former 26.

  In the winding process, the wire member 8 is wound around the winding former 26. The tension of the wire member 8 is adjusted by the pre-roll 24. The wire member 8 is wound around the winding former 26 while the tension is adjusted.

  As shown in FIG. 3, the winding former 26 has a cylindrical shape. The winding former 26 is rotatable about its axis. The winding former 26 is movable in the axial direction. A groove 32 for forming the outer shape of the core member 2 is formed on the outer periphery of the winding former 26 (see FIG. 7). The groove 32 has a shape along the outer surface shape facing inward in the radial direction of the core member 2.

  As shown in FIG. 6A, the wire member 8 is wound along the shape of the groove 32. At this time, the winding former 26 rotates while moving in the axial direction, and the wire member 8 is wound. The control device controls the rotational speed and the axial position of the winding former 26. The wire member 8 is wound, and the first-stage loop 4a, loop 4b, loop 4c, loop 4d, and loop 4e are sequentially formed. These loops 4 a to 4 e are the outer loops 4. These loops 4 a to 4 e are provided with a coating layer 12.

  As shown in FIG. 6B, the wire member 8 is further wound. The loop 4a to loop 4h form a first-stage loop. When the loop 4h is formed, a loop 4i is formed outside the loop 4h in the radial direction. The loop 4i is overlapped on the outer side in the radial direction of the loop 4h. These loops 4 h and 4 i are the outer loops 4. The loops 4 h and 4 i include a coating layer 12.

  In succession to the loop 4i, a loop 6a, a loop 6b, a loop 6c, a loop 6d, and a loop 6e are sequentially formed. The loop 6 a to the loop 6 e are the inner loop 6. The loops 6 a to 6 e do not include the coating layer 12.

  As shown in FIG. 6C, the wire member 8 is further wound. The loops 6a to 6g are sequentially formed. An outer loop 4j is formed continuously with the loop 6g. The inner loop 6 from the loop 6a to the loop 6g and the outer loops 4i and 4j at both ends in the axial direction form a second-stage loop.

  A loop 4k is formed outside the loop 4j in the radial direction. The loop 4k is overlapped on the outer side in the radial direction of the loop 4j. The loops 4j and 4k are the outer loops 4. The loops 4j and 4k are provided with a coating layer 12. Following this loop 4k, a loop 6h, a loop 6i, and a loop 6j are sequentially formed. Further, the wire member 8 is wound to sequentially form a plurality of outer loops 4 and a plurality of inner loops 6.

  As shown in FIG. 7, the wire member 8 is wound to form the core member 2. The core member 2 is formed by superimposing first to sixth loops. The core member 2 is formed of an outer loop 4 that forms the outer surface of the core member 2, and an inner loop 6 that is surrounded by the outer loop 4.

  In the removal step, the core member 2 is removed from the winding former 26. The winding former 26 is reduced in diameter. The core member 2 is taken out from the groove 32.

  FIG. 8 shows a method for manufacturing the tire T according to the present invention. The manufacturing method of the tire T includes a member preparation process, a preforming process, and a vulcanization molding process.

  In the member preparation step, members constituting each part of the tire T are prepared. In addition to the core member 2 described above, members constituting each part of the tire T, such as a tread, a sidewall, a clinch, and a carcass, are prepared.

  In the pre-molding step, members constituting each part of the tire T are combined to obtain a raw cover (raw tire). The core member 2 constitutes a part of the raw cover.

  In the vulcanization molding process, this raw cover is put into a mold. The raw cover is vulcanized at a predetermined pressure and temperature. A tire T is obtained from this raw cover. The core of the tire T is formed from the core member 2.

  Although not shown, the tire T includes a tread, a pair of sidewalls, a pair of clinches, a pair of beads, a carcass, a belt, a band, and an inner liner. The tread forms a tread surface that contacts the road surface. Each sidewall extends substantially inward in the radial direction from the end of the tread. Each bead is located radially inside the sidewall. The carcass is stretched between both beads. The belt is positioned on the inner side in the radial direction of the tread and is laminated with the carcass. The band is laminated on the outer side in the radial direction of the belt. The inner liner is located inside the carcass and joined to the inner surface of the carcass.

  The bead includes a core and an apex that extends radially outward from the core. The core is ring-shaped and includes a wound wire 10. The apex tapers radially outward. Apex is made of a highly hard crosslinked rubber. The core includes a bundle made up of a plurality of outer loops 4 and inner loops 6.

  In the removal process of the core member 2, the coating layer 12 is not removed in the portion of the coating wire 28 constituting the outer loop 4. The outer loop 4 includes a coating layer 12. Due to the coating layer 12, the core member 2 is prevented from being deformed. In the manufacturing method of the tire T, handling of the core member 2 is facilitated. The core member 2 contributes to an improvement in the productivity of the tire T. The core member 2 contributes to improving the quality of the tire T.

  On the other hand, in this removal step, the coating layer 12 is removed from the portion of the coating wire 28 that constitutes the inner loop 6. The inner loop 6 of the core member 2 does not include the coating layer 12. Thereby, the core member 2 is deformed and easily moved. The tire T including the core formed from the core member 2 is easily deformed. The bead of the tire T can be deformed flexibly. The tire T is excellent in uniformity. In the tire T, uneven wear of the tread is suppressed.

  The core member 2 includes a bottom surface S that faces the seat surface of the rim and extends along the seat surface (see FIG. 2). The bottom surface S is formed by outer loops 4 arranged along the seat surface of the rim. The core formed from the core member 2 can be securely fitted to the rim seat. By providing this bottom surface S, it contributes to the improvement of the rigidity of the tire T. By providing the core made of the core member 2, the tire T is excellent in the above-mentioned uniformity and can contribute to the improvement of the rigidity of the tire T.

  Further, in the tire T, the mass of the coating layer 12 of the core member 2 is reduced. The mass of the core member 2 is reduced. The core member 2 also contributes to the weight reduction of the tire T.

  In the core member 2, not all the outer loops 4 are necessarily provided with the coating layer 12. It is only necessary that the deformation of the core member 2 can be suppressed, and a part of the outer loop 4 may not include the coating layer 12. The number of the outer loops 4 constituting the core member 2 is Lo, and the number of the outer loops 4 including the coating layer 12 is Loc. From the viewpoint of suppressing the deformation of the core member 2, the ratio of Loc to Lo (Loc / Lo) is preferably 0.6 or more, more preferably 0.8 or more, and particularly preferably. Is 0.9 or more.

  The core member 2 does not necessarily have to have the inner layer 6 removed from the coating layer 12. The core member 2 may include an inner loop 6 with a coating layer 12. Even the core formed from the core member 2 can be easily deformed. The number of the inner loops 6 constituting the core member 2 is Li, and the number of the inner loops 6 including the coating layer 12 is Lic. From the viewpoint of facilitating deformation of the core, the ratio of Lic to Li (Lic / Li) is preferably 0.3 or less, more preferably 0.2 or more, and particularly preferably 0.8. 1 or more.

  In the core member 2, from the viewpoint of suppressing the deformation of the core member 2 and facilitating deformation of the core formed from the core member 2, the ratio of the outer loop 4 (Loc / Lo) is set to the inner loop 6. The ratio (Lic / Li) is larger. By increasing the difference between the ratio (Lic / Li) and the ratio (Loc / Lo), the core member 2 can be prevented from being deformed and the core can be easily deformed. From this viewpoint, the ratio of the ratio (Loc / Lo) to the ratio (Lic / Li) ((Loc / Lo) / (Lic / Li)) is preferably 2 or more, more preferably 5 or more. Particularly preferred is 10 or more. In the present invention, the ratio (Loc / Lo) and the ratio (Lic / Li) are determined by any one cross section perpendicular to the circumferential direction of the core member 2.

  The control device has a function of controlling the range in which the coating layer 12 of the wire member 8 is removed by using the removal device 22 and depending on the position wound around the core member 2. In the manufacturing method of the core member 2, in the removing step, the ratio (Loc / Lo) and the ratio (Lic / Li) can be easily adjusted by the control device. Moreover, in this manufacturing method, the position range provided with the coating layer 12 can be accurately adjusted by removing the coating layer 12 from the coating wire 28 with the removing device 22.

  2 is divided into an upper loop composed of the outer loop 4 and the inner loop 6 on the radially outer side, and a lower loop composed of the outer loop 4 and the inner loop 6 on the radially inner side. In the core member 2, the fourth to sixth stages are upper loops, and the first to third stages are lower loops. At this time, the number of upper loops is Lu, and the number of lower loops is Ld. Of the upper loops, the number of upper loops on which the coating layer 12 is formed is Luc, and among the lower loops, the number of lower loops on which the coating layer 12 is formed is Ldc. In the core member 2, the line L <b> 2 is also a boundary between the outer loop 4 that forms the outer surface facing inward in the radial direction and the other outer loop 4.

  FIG. 9 shows a state around the core member 2 of the raw cover that is vulcanized by a mold in the vulcanization process. FIG. 9A shows a state before being heated and pressurized. FIG. 9B shows a heated and pressurized state. As shown in FIG. 9A, the carcass member 34 is folded around the core member 2. By this folding, the carcass member 34 is formed with a main portion 34a extending from one core member 2 in the axial direction to the other core member 2 and a folding portion 34b that is folded back by the core member 2 and extends outward in the radial direction. Yes.

  As shown in FIG. 9B, the raw cover is pressurized and heated in the vulcanization process. Thereby, in the main portion 34a of the carcass member 34, a tension F is generated outward in the radial direction. As shown in FIG. 9B, the main portion 34 a is pulled outward in the radial direction by the tension F. The core member 2 is deformed by the carcass member 34. At this time, deformation is increased on the lower side of the core member 2. The core member 2 is easily deformed at the lower loop.

  In this core member 2, the ratio of Ldc in the lower loop in which the coating layer 12 is formed with respect to Ld in the lower loop (Ldc / Ld) is preferably the coating layer with respect to Lu in the upper loop. 12 is made larger than the Luc ratio (Luc / Lu) of the upper loop formed. Thereby, in the core member 2, the deformation | transformation of the part of a lower loop is suppressed. The core member 2 is further suppressed from being deformed in the vulcanization process. In the present invention, the ratio (Ldc / Ld) and the ratio (Ldc / Ld) are determined by an arbitrary cross section perpendicular to the circumferential direction of the core member 2.

  FIG. 10A shows a part of the wire member 8. FIG. 10A shows a boundary between a portion having the coating layer 12 and a portion not having the coating layer 12 in the wire member 8. In other words, FIG. 10A shows an end portion of the coating layer 12. In the wire member 8, the coating layer 12 is cut perpendicular to the longitudinal direction of the wire member 8. The thickness tc of the coating layer 12 is constant.

  FIG. 10B shows a part of another wire member 36. The core member 2 may be formed of a wire member 36 instead of the wire member 8. The thickness tc gradually decreases toward the end of the coating layer 12 at the end of the coating layer 12. In the core member 36, the occurrence of a step is suppressed at the end of the coating layer 12. In the core member 36, the occurrence of a gap between the loops is suppressed. Thereby, it contributes to suppression of the shape loss of the core member 2.

  In the process of removing the core member 2, the ends of the wound outer layer 4 and inner layer 6 of the coating layer 12 are shifted in the circumferential direction from the ends of the adjacent outer layer 4 and inner layer 6 of the coating layer 12. Has been. Thereby, it is suppressed that the edge of the coating layer 12 concentrates on a specific location in the circumferential direction of the core member 2. The coating layer 12 suppresses the generation of steps. In the core member 36, the occurrence of a gap between the loops is suppressed. Thereby, it contributes to suppression of the shape loss of the core member 2. Moreover, it contributes to the improvement of the uniformity of the tire T.

  The core member 2 is divided into two equal parts by the one-dot chain line L1 in FIG. From the viewpoint of suppressing the deformation of the core member 2 and improving the uniformity of the tire T, it is preferable that the position of the end of the coating layer 12 is positioned without deviation in the circumferential direction. From this viewpoint, the number of ends of the coating layer 12 located on one side divided by the straight line L1 is N1, and the number of ends of the coating layer 12 located on the other side is N2. The ratio of N2 to N1 (N2 / N1) is preferably 1/3 or more. From the same viewpoint, the ratio (N2 / N1) is preferably 3 or less. The straight line L1 may be a straight line extending in the diametrical direction of the core member 2 through the point Po, and is in an arbitrary direction.

  FIG. 11 shows another core member 38 according to the present invention. Here, the core member 2 having a hexagonal cross-sectional shape has been described as an example, but the cross-sectional shape is not limited thereto. The present invention can be widely applied to a core having a strand structure in which cross sections of the wire are arranged in the axial direction and the radial direction. The manufacturing method according to the present invention is also suitable for manufacturing the core member 38. In the core member 38 of FIG. 11, the vertical direction is the radial direction of the core member 38, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction. Even in the core member 38, the uneven wear of the tread can be suppressed while suppressing the deformation of the shape like the core member 2 described above.

  In this specification, the normal rim means a rim defined in a standard on which the tire T depends. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In this specification, the normal internal pressure means an internal pressure defined in a standard on which the tire T depends. “Maximum air pressure” in JATMA standard, “maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in TRA standard, and “INFLATION PRESSURE” in ETRTO standard are normal internal pressures. In the present specification, the normal load means a load defined in a standard on which the tire T depends. “Maximum value” published in “Maximum load capacity” in JATMA standard, “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in TRA standard, and “LOAD CAPACITY” in ETRTO standard are normal loads.

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

[Example 1]
The core member shown in FIGS. 1 and 2 was manufactured using the core member manufacturing facility of FIG. A raw cover was obtained by combining this core member and other members constituting each part of the tire. The raw cover was vulcanized to obtain a tire. The tire size was 275 / 80R22.5.

[Comparative Example 1-3]
A tire was obtained in the same manner as in Example 1 except that the coating layers of the outer loop and the inner loop were changed as shown in Table 1.

[Uneven wear resistance]
Tires built in regular rims and brought to regular internal pressure were mounted on four vehicles. When these four vehicles were run, the occurrence of uneven wear such as tread shoulder wear and step wear was confirmed. The distance traveled until the tire was changed. The average mileage of the four vehicles was calculated. In this evaluation, the traveling distance of Comparative Example 1 is set to 100 and is displayed as an index. The larger this value, the better the uneven wear resistance.

[Bead durability]
A tire built in a regular rim and brought to regular internal pressure was run in a drum test. The tire was run on the drum at a speed of 20 (km / hr) with a longitudinal load of 2.0 times the normal load. The running time until the tire breaks is measured and displayed as an index with Comparative Example 1 as 100. A larger value is better.

[Tire mass]
The mass of the tire was measured. The mass of the tire is indicated by an index with Comparative Example 1 as 100. The larger the index, the greater the mass. A smaller index is preferred.

  As shown in Table 1, the tire manufactured by the manufacturing method of the example has a higher evaluation than the tire of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The method described above can be widely applied as a method for manufacturing a tire bead core.

2, 38 ... Core member 4 ... Outer loop 6 ... Inner loop 8, 36 ... Wire member 10 ... Wire 12 ... Coating layer 14 ... Bead member manufacturing equipment 16 ... Reel 18 ... heater 20 ... extruder 22 ... removal device 24 ... pull roll 26 ... winding former 28 ... coating wire 30 ... die 32 ... groove 34 ...・ Carcass members

Claims (12)

A coating process in which a coating layer is formed by forming a coating layer on the outer peripheral surface of the wire;
A removal step in which a part of the coating layer of the coating wire is removed to obtain a wire member;
The wire member is wound, a plurality of loops that make a round in the circumferential direction are formed, and a winding step in which a core member composed of a bundle of the loops is obtained is provided.
In the cross section perpendicular to the circumferential direction of the core member, the number of outer loops forming the outer surface of the core member among the loops is Lo, the number of outer loops on which the coating layer is formed is Loc, When the number of inner loops surrounded by the outer loop is Li and the number of inner loops on which the coating layer is formed is Lic, the following relational expression is satisfied, and the core of the tire is vulcanized The manufacturing method of the core member which forms.
Loc / Lo> Lic / Li   The core member manufacturing method according to claim 1, wherein a ratio of the Loc book to the Lo book of the outer loop is 0.6 or more.   The method for manufacturing a core member according to claim 1 or 2, wherein the ratio of the Lic book to the Li book of the inner loop is 0.3 or less. The method of manufacturing a core member according to any one of claims 1 to 3, wherein a ratio of Loc to Lo of the outer loop and a ratio of Lic to Li of the inner loop satisfy the following relational expression.
(Loc / Lo) / (Lic / Li) ≧ 2   5. The thickness tc of the coating layer is gradually reduced toward the end of the coating layer at the end of the coating layer of the wire member in the removing step. The manufacturing method of the core member.   The core member manufacturing method according to any one of claims 1 to 5, wherein, in the winding step, positions of ends of the coating layers of adjacent loops are shifted in the circumferential direction and the wire member is wound. . The core member loop bundle is divided into an upper loop positioned radially outward and a lower loop positioned radially inner, and the number of upper loops is Lu, and the upper loop on which the coating layer is formed The number of Lc is Luc, the number of lower loops is Ld, and the number of lower loops on which the coating layer is formed is Ldc. The manufacturing method of the core member of crab.
Ldc / Ld> Luc / Lu   The core member manufacturing method according to claim 1, wherein all of the outer loops include the coating layer, and all of the inner loops do not include the coating layer. A core member forming step for obtaining a core member that is vulcanized to form a core;
A preforming step in which a raw cover is formed by laminating the core member and other constituent members;
A vulcanization molding step in which the raw cover is vulcanized with a mold to obtain a tire,
The core member forming step includes
A coating process in which a coating layer is obtained by forming a coating layer on the outer peripheral surface of the wire;
A removal step in which a part of the coating layer of the coating wire is removed to obtain a wire member,
A plurality of loops made of the wire member wound around the wire member are formed, and a winding step in which a core member made of a bundle of the loops is obtained;
In the cross section perpendicular to the circumferential direction of the core member, Lo is the number of outer loops constituting the outer surface of the core member, and Lo is the number of outer loops on which the coating layer is formed. A tire manufacturing method that satisfies the following relational expression when the number of inner loops surrounded by Li is Li and the number of inner loops in which the coating layer is formed is Lic.
Loc / Lo> Lic / Li A coating apparatus for forming a coating wire by forming a coating layer on the outer peripheral surface of the wire;
A removal device for removing a part of the coating layer of the coating wire to form a wire member;
And a control device,
A manufacturing facility for a core member, which has a function of controlling a range in which the coating layer of the coating wire is removed by the removing device, depending on a position in the core member formed by winding the wire member. . It has a bundle of multiple loops,
The bundle is formed by winding the wire in the circumferential direction,
In the cross section perpendicular to the circumferential direction, the number of outer loops forming the outer surface of the core among the loops is Lo, the number of outer loops having a coating layer formed on the outer peripheral surface of the wires is Loc, When the number of inner loops surrounded by loops is Li and the number of inner loops having a coating layer formed on the outer peripheral surface of the wire is Lic, the tire bead core satisfying the following relational expression: .
Loc / Lo> Lic / Li It has a tread, a pair of sidewalls, a pair of beads and a carcass,
The tread has a tread surface that contacts the road surface,
Each sidewall extends radially inward from the end of the tread,
Each bead is located radially inside the sidewall,
The carcass is stretched between one bead and the other bead along the inside of the tread and the sidewall,
The bead has a core,
The core includes a bundle of a plurality of loops,
The bundle is formed by winding the wire in the circumferential direction,
In the cross section perpendicular to the circumferential direction, the number of outer loops forming the outer surface of the core among the loops is Lo, the number of outer loops having a coating layer formed on the outer peripheral surface of the wire is Loc, A tire that satisfies the following relational expression when the number of inner loops surrounded by outer loops is Li, and the number of inner loops having a coating layer formed on the outer peripheral surface of the wire is Lic.
Loc / Lo> Lic / Li

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