JP2018047585A - Tire production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire production method restraining productivity deterioration and improving uniformity.SOLUTION: In an objective tire production method, a preliminary molding process includes a conveyance process and a coalescence process. In the conveyance process, a conveyor 8 conveys a tread molding 46 outside a carcass molding 44 in a radial direction. In the coalescence process, a tread molding 46 in which the conveyor 8 holds is stuck on the outer peripheral surface of a carcass molding 44 to form a low cover. The segment of the conveyor 8 comprises a clamp surface contacting the outer peripheral surface of the tread molding. The clamp surface is formed from at least two or more area surfaces whose curvature radiuses are different from each other in a cross section perpendicular to an axial direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a tire excellent in uniformity.

  Japanese Patent Application Laid-Open No. 7-52277 discloses a transport device for transporting a ring-shaped tread ring in a tire preforming process. The transport device includes a plurality of segments that hold the outer peripheral surface of the tread ring. The circumferential length and the axial width of the segment are set to a predetermined size. By holding the tread ring in this segment, it is possible to prevent the displacement from occurring when the tread ring and the carcass ply member are combined.

Japanese Patent Laid-Open No. 7-52277

  It is desirable that the segment of such a transport device includes a contact surface having a shape close to the outer peripheral surface shape of the tread ring. By holding the outer peripheral surface of the tread ring with a segment having such a contact surface, deformation of the tread ring can be suppressed. By using such a segment, the uniformity of the tire can be improved. However, when such a segment is used, it is necessary to replace the segment in accordance with the outer diameter of the tire. Since this segment requires positional accuracy in the circumferential direction, the axial direction, and the radial direction, it is not easy to replace the segment. In particular, in a mixed flow production line in which various types of tires are produced, such segment replacement tends to impair productivity.

  An object of the present invention is to provide a tire manufacturing method that improves uniformity while suppressing a decrease in productivity.

The method for manufacturing a tire according to the present invention includes a preforming step in which a raw cover that is vulcanized to obtain a tire is formed.
The preforming step is
(1) A carcass molded body in which a carcass member and a bead member are bonded to each other and a tread molded body in which a tread member is formed in a ring shape are prepared, and a conveying device is provided on the outer peripheral surface of the tread molded body. And (2) the tread molded body held by the transport device is bonded to the outer peripheral surface of the carcass molded body. And a coalescing step for forming the raw cover.
The said conveying apparatus is provided with the flame | frame provided with opening and the several segment located in the said opening. The plurality of segments are arranged in the circumferential direction of the outer peripheral surface of the tread molded body and are movable in the radial direction of the outer peripheral surface. Each segment includes a clamp surface that contacts the outer peripheral surface of the tread compact. The clamp surface is formed of at least two or more region surfaces having different radii of curvature in a cross section perpendicular to the axial direction.

  Preferably, in the clamp surface, the radius of curvature of one region surface located on the circumferential center side is made smaller than the radius of curvature of another region surface located on the circumferential end side adjacent to the one region surface. ing. The one area plane is located radially outward from the other area plane.

  Preferably, the outer diameter of the tire is 230 (mm) or more and 395 (mm) or less.

  The transport device for a tread molded body according to the present invention is a device for transporting a tread molded body in which a tread member made of unvulcanized rubber is formed into a ring shape. The transport device includes a frame having an opening and a plurality of segments positioned in the opening. The plurality of segments are arranged in the circumferential direction of the outer peripheral surface of the tread molded body and are movable in the radial direction. Each segment includes a clamp surface that contacts the outer peripheral surface of the tread compact. The clamp surface is formed of at least two or more region surfaces having different radii of curvature in a cross section perpendicular to the axial direction.

  Preferably, in the clamp surface, the radius of curvature of one region surface located on the circumferential center side is made smaller than the radius of curvature of another region surface located on the circumferential end side adjacent to the one region surface. ing. The one area plane is located radially outward from the other area plane.

  Preferably, the centers of the curvature radii of the two or more region surfaces are located on a radial straight line along which the segment moves.

  Preferably, the transport device includes a spacer that is detachably attached to the clamp surface. The spacer includes an inner surface facing inward in the radial direction and an outer surface facing outward in the radial direction. In the cross section perpendicular to the axial direction, the inner surface is formed with a radius of curvature of the other region surface. In a state where the spacer is attached to the clamp surface, the other area surface and the inner surface are located on the same arc.

  In the tire manufacturing method according to the present invention, the outer peripheral surface of the tread molded body is clamped at a region surface close to the shape of the outer peripheral surface of the tread molded body among the region surfaces having different curvature radii of the clamp surface. This manufacturing method suppresses deformation of the tread molded body due to the contact of the segments. By using this tread molded body, the uniformity of the tire can be improved.

FIG. 1 is a conceptual diagram showing a molding apparatus for a tire manufacturing method according to an embodiment of the present invention. FIG. 2 is a conceptual diagram showing a conveying device of the molding apparatus of FIG. FIG. 3 is an explanatory view showing a clamp of the transport device of FIG. FIG. 4 is an explanatory view showing a clamp of another conveying apparatus of the molding apparatus of FIG.

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

  FIG. 1 shows a pneumatic tire molding apparatus 2. The molding device 2 includes a first molding device 4, a second molding device 6, and a transport device 8.

  The first molding device 4 includes a gantry 14, a first drum 16, and a pair of bead receiving portions 18. Although not shown, the first molding device 4 includes a bladder between the pair of bead receiving portions 18 in the axial direction. The bladder can expand radially outward and contract radially inward. The gantry 14 supports the first drum 16. The shape of the first drum 16 is a cylindrical shape. The axial length of the first drum 16 is extendable. Each of the pair of bead receiving portions 18 has a ring shape. The distance between the pair of bead receiving portions 18 in the axial direction can be changed. The first drum 16 and the pair of bead receiving portions 18 are rotatable about the axis of the first drum 16 as a rotation axis.

  The second molding device 6 includes a gantry 22 and a second drum 24. The gantry 22 supports the second drum 24. The shape of the second drum 24 is a cylindrical shape. The second drum 24 is rotatable about its axis as a rotation axis. The outer peripheral surface of the second drum 24 can be expanded and contracted in the radial direction.

  The transport device 8 includes a rail 26, a moving table 28, an annular frame 30, and a plurality of clamps 32. The rail 26 extends from the first molding device 4 to the second molding device 6. The movable table 28 is movable along the rail 26. The annular frame 30 is placed and fixed on the movable table 28. The annular frame 30 is movable along the rail 26 between a position disposed on the radially outer side of the first drum 16 and a position disposed on the radially outer side of the second drum 24.

  As shown in FIG. 2, the annular frame 30 has an opening 31 penetrating in the axial direction. The sectional shape of the opening 31 perpendicular to the axial direction is a circle. The axis of the opening 31 coincides with the axis of the first drum 16 and the axis of the second drum 24. The circumferential direction of the opening 31 is parallel to the circumferential direction of the first drum 16 and the circumferential direction of the second drum 24. In the following description, unless otherwise specified, the circumferential direction, the axial direction, and the radial direction represent the circumferential direction, the axial direction, and the radial direction of the opening 31.

  A plurality of clamps 32 are arranged on the inner peripheral surface of the opening 31. The plurality of clamps 32 are arranged at equal intervals along the circumferential direction. In the transport device 8, a clamp 32 is attached to the inner peripheral surface of the opening 31. The plurality of clamps 32 are integrally rotatable about the axis of the opening 31 as a rotation axis.

  Each clamp 32 includes a body 34 and a segment 36. A dashed-dotted line Lr in FIG. 2 represents a straight line extending through the center of the opening 31. The straight line Lr is a straight line in the radial direction of the opening 31. The segment 36 can move along the straight line Lr with respect to the main body 34. In other words, the segment 36 can move in the radial direction of the opening 31.

  The plurality of segments 36 can be enlarged and reduced in diameter in the radial direction at the same movement distance. In other words, the segments 36 can move in the radial direction while being arranged on the circumference of the concentric circle of the opening 31. The segment 36 includes a clamping surface 38 that faces radially inward.

  In FIG. 3, the segment 36 is shown with a portion of the body 34. FIG. 3 shows the segment 36 as viewed in the axial direction. In FIG. 3, the segment 36 has a shape that is line-symmetric with respect to the straight line Lr. The clamp surface 38 includes a clamp surface 38a as a region surface, a pair of clamp surfaces 38b as another region surface, and a pair of clamp surfaces 38c as another region surface. The clamp surface 38a is located inside the segment 36 in the circumferential direction. The pair of clamp surfaces 38b is adjacent to the outer side in the circumferential direction of the clamp surface 38b. The pair of clamp surfaces 38c is adjacent to the outer side in the circumferential direction of the clamp surface 38b.

  The symbol Ca in FIG. 3 represents the arc of the contour of the clamp surface 38a. The arrow Ra represents the radius of curvature of the clamp surface 38a. A point Pa represents the center of the arc Ca. Reference numeral Cb represents an arc of the contour of the clamp surface 38b. The arrow Rb represents the radius of curvature of the clamp surface 3b. Point Pb represents the center of arc Cb. Symbol Cc represents an arc of the contour of the clamp surface 38c. The arrow Rc represents the radius of curvature of the clamp surface 38c. Point Pc represents the center of arc Cc. In FIG. 3, for convenience of explanation, the radii of curvature Ra, Rb, and Rc are shown smaller than actual ones.

  The curvature radius Ra of the clamp surface 38a is smaller than the curvature radius Rb. The clamp surface 38a is formed radially outward from the arc Cb. This curvature radius Rb is smaller than the curvature radius Rc. The clamp surface 38b is formed radially outward from the arc Cc. The center Pa of the arc Ca, the center Pb of the arc Cb, and the center Pc of the arc Cc are located on the straight line Lr.

  A tire manufacturing method using the molding apparatus 2 will be described. This tire manufacturing method includes a preforming step and a vulcanizing step. The preforming process includes a first forming process, a second forming process, a conveying process, and a coalescing process. In this pre-molding step, the raw cover is molded by combining the members that form each part of the tire.

  In the first molding step, a carcass ply member, a bead member, and the like are wound around the outer periphery of the first drum 16 and the bead receiving portion 18 shown in FIG. A cylindrical carcass molded body 44 is formed from the carcass ply member, the bead member and the like wound in this manner. The axial direction, the circumferential direction, and the radial direction of the carcass molded body 44 coincide with each of the first drums 16.

  In the second molding step, a tread member, a belt member, a band member and the like are wound around the outer periphery of the second drum 24. A cylindrical tread molded body 46 is formed from the tread member, belt member, band member and the like wound in this manner. The axial direction, the circumferential direction, and the radial direction of the tread compact 46 coincide with each of the second drums 24.

  In the conveying step, a carcass molded body 44 and a tread molded body 46 are prepared. The conveying device 8 moves toward the second molding device 6. The conveying device 8 positions the segment 36 on the outer side in the radial direction of the tread molded body 46. The segment 36 moves inward in the radial direction and comes into contact with the outer peripheral surface of the tread molded body 46. The transport device 8 holds the tread molded body 46 with the clamp 32. The diameter of the second drum 24 is reduced, and the second drum 24 is separated from the inner peripheral surface of the tread molded body 46. The conveying device 8 conveys the tread molded body 46 to the outside in the radial direction of the carcass molded body 44.

  In the coalescing step, although not shown, the bladder of the first molding device 4 expands to expand the carcass molded body 44 in a toroid shape. A tread molded body 46 is pressure-bonded to the outer peripheral surface of the carcass molded body 44. After this crimping, the segment 36 moves radially outward. The clamp surface 38 is separated from the outer peripheral surface of the tread molded body 46. In this way, the transport device 8 releases the clamp of the tread molded body 46. The transport device 8 moves to a retracted position away from the tread molded body 46. The tread molded body 46 is further pressure-bonded to the outer peripheral surface of the carcass molded body 46 by a stitcher (not shown). In this way, a raw cover is obtained.

  In the vulcanization process, this raw cover is prepared. This raw cover is vulcanized with a mold. A tire is obtained from the raw cover through this vulcanization. The carcass ply member, bead member, belt member, band member, and tread member described above are vulcanized to form the carcass, bead, belt, band, and tread of the tire.

  The segment 36 of the transport device 8 includes clamp surfaces 38a, 38b and 38c having different radii of curvature. The clamp surface 38 a, 38 b, or 38 c having a shape closest to the outer diameter shape of the tread molded body 46 abuts on the tread molded body 46. The clamp surface 38 abuts while suppressing deformation of the tread molded body 46. The tread molded body 46 is made of unvulcanized rubber. The outer peripheral surface of the tread molded body 46 is easily deformed. This deformation affects the tire uniformity. The transport device 8 can contribute to improvement of tire uniformity.

  In this segment 36, the tread molded body 46 is clamped by the clamp surfaces 38a, 38b or 38c which are close to the shape of the outer peripheral surface of the tread molded body 46. Accordingly, a sufficient contact area is maintained on the clamp surface 38 in many tread molded bodies 46 having different outer diameters. The clamp 32 can stably hold the tread molded body 46 by suppressing the positional deviation.

  The tread molded body 46 is pressure-bonded to the carcass molded body 44 while the segment 36 suppresses deformation of the tread molded body 46. For this reason, positional deviation between the carcass molded body 44 and the tread molded body 46 is suppressed. Also from this point of view, the transport device 8 can contribute to improvement of tire uniformity.

  The segment 36 presses the tread molded body 46 to the carcass molded body 44 while suppressing the deformation of the tread molded body 46. Since the deformation of the tread molded body 46 is suppressed in the coalescing step, the formation of a gap between the carcass molded body 44 and the tread molded body 46 is suppressed. The conveying device 8 suppresses air from remaining between the carcass molded body 44 and the tread molded body 46.

  In this segment 36, the center Pa of the curvature radius Ra, the center Pb of the curvature radius Rb, and the center Pc of the curvature radius Rc are located on the straight line Lr. In other words, the center Pa, the center Pb, and the center Pc are located on a radial straight line along which the segment 36 moves. Thereby, the movement of the segment 36 does not shift the axis of the tread molded body 46 in many tread molded bodies 46 having different outer diameters. Thereby, the position shift with the carcass molded object 44 and the tread molded object 46 is suppressed. This conveying device 8 contributes to improvement of tire uniformity.

  In the transport device 8, the tread molded body 46 having a different outer diameter can be held without changing the segment 36. This conveying device 8 contributes to the improvement of productivity. This conveyance device 8 is suitable for a mixed flow production line in which tires having different outer diameters are produced.

  The outer diameter of the tire varies greatly depending on the application. However, the outer diameter of passenger car tires is in the range of approximately 230 (mm) to 395 (mm). This outer diameter range is relatively narrow. In this range, by using the clamp 32, a tire excellent in uniformity can be manufactured without changing the mold. The transport device 8 is particularly suitable for a method for manufacturing a tire for a passenger car.

  The segment 36 includes three area surfaces having different radii of curvature, such as clamp surfaces 38a, 38b, and 38c. The clamp according to the present invention is not limited to this. The clamp which concerns on this invention should just be provided with the area | region surface from which a curvature radius differs 2 or more. The clamp surface may include four or more region surfaces with different radii of curvature.

  4 (a) and 4 (b) show a clamp 50 of another conveying device 48 used in the manufacturing method according to the present invention. The transport device 48 includes a clamp 50 instead of the clamp 32 of the transport device 8. The transport device 48 has the same configuration as the transport device 8 except that the clamp 50 is provided. Here, regarding the transport device 48, a configuration different from the transport device 8 will be described, and a description of the same configuration as the transport device 8 will be omitted. Further, the same configuration as the transport device 8 will be described using the same reference numerals as those of the transport device 8.

  The clamp 50 includes a spacer 40 and a spacer 42 in addition to the main body 34 and the segment 36.

  FIG. 4A shows the spacer 40 together with a part of the main body 34 and the segment 36 as seen in the axial direction. The spacer 40 includes an inner side surface 40a facing inward and an outer side surface 40b facing outward in the radial direction. The contour of the inner surface 40a is formed by an arc having the same radius of curvature Rb as that of the clamp surface 38b. The contour of the outer side surface 40b is formed by an arc having the same curvature radius Ra as that of the clamp surface 38a.

  The spacer 40 is detachably attached to the clamp surface 38a. This attachment method is not particularly limited. For example, positioning is performed by inserting circumferential and axial positioning pins into the outer surface 40b and the clamp surface 38a. The spacer 40 is fixed to the segment 36 with screws. The outer surface 40b of the spacer 40 is in contact with the clamp surface 38a. At this time, the inner side surface 40a is located on the same arc Cb as the pair of clamp surfaces 38b. By attaching the spacer 40, a clamp surface 52 is formed from the inner side surface 40a and the pair of clamp surfaces 38b.

  FIG. 4B shows the spacer 42 together with the spacer 40 as seen in the axial direction. The spacer 42 includes an inner surface 42a facing inward and an outer surface 42b facing outward in the radial direction. The contour of the inner surface 42a is formed by an arc having the same curvature radius Rc as that of the clamp surface 48c. The contour of the outer side surface 42b is formed by an arc having the same radius of curvature Rb as that of the clamp surface 48b. The spacer 42 is detachably attached to the clamp surface 38b. This attachment method is the same as that of the spacer 40. The outer surface 42 b of the spacer 40 is in contact with the clamp surface 38 b and the inner surface 40 a of the spacer 40. At this time, the outer surface 42a is located on the same arc Cb as the pair of clamp surfaces 38c. By attaching the spacer 42, a clamp surface 54 is formed from the inner side surface 42a and the pair of clamp surfaces 38c.

  In FIG. 4B, the clamp surface 54 may be formed, and a spacer in which the spacer 40 and the spacer 42 are integrated may be used. The spacer 42 may be attached to the clamp 32 to which the spacer 40 is not attached.

  As shown in FIG. 4A, the clamp 50 can abut the tread molded body 46 with the clamp surface 52. The contact area of the clamp surface 52 is wider than the contact area of the pair of clamp surfaces 38b. The clamping surface 52 provides a further sufficient contact area. The deformation of the tread molded body 46 can be further reduced. Further, since the segment 36 suppresses the deformation of the tread molded body 46 and the tread molded body 46 is pressure-bonded to the carcass molded body 44, the positional deviation between the carcass molded body 44 and the tread molded body 46 is further suppressed. . By using the clamp 50, the transport device 48 can further contribute to the improvement of tire uniformity. Further, the remaining of air between the carcass molded body 44 and the tread molded body 46 is further suppressed.

  The spacer 40 is positioned and attached to the clamp surface 38. The clamp surface 38 is positioned with high accuracy in the circumferential direction, the axial direction, and the radial direction with respect to the tread molded body 46. Since the spacer 40 is attached to the clamp surface 38a, it can be easily positioned with high accuracy. This type change can be easily performed with high accuracy in a short time as compared with the type change of the main body 34 and the segment 36.

  The contact area of the clamp surface 54 shown in FIG. 4B is wider than the contact area of the pair of clamp surfaces 3c. Thereby, like the case where the spacer 40 is attached, it can further contribute to the improvement of the uniformity of the tire. Furthermore, the remaining of air between the carcass molded body 44 and the tread molded body 46 is further suppressed. In addition, since the spacer 42 is attached to the clamp surface 38b, this type change can be easily performed with high accuracy in a short time.

  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]
A raw cover was formed in the preforming step using the conveying device shown in FIGS. This segment had a clamping surface with three different radii of curvature. The curvature radius of one of the clamp surfaces was 340 (mm). The size of the tire obtained from this raw cover was “225 / 55R19”. Using this conveying device, 60 low covers were formed. These raw covers were vulcanized to obtain tires.

[Comparative Example 1]
A raw cover was formed in the same manner as in Example 1 except that the segment was provided with a clamping surface having a single radius of curvature, and the radius of curvature was 320 (mm). These raw covers were vulcanized to obtain tires.

[RRO evaluation]
For these tires, RRO (radial run out) was measured. Specifically, RRO was measured on the outer peripheral surface of the tire using a non-contact laser measuring instrument. From the measured values, the average of each measured value and the standard deviation were obtained. In Table 1, the average value and the standard deviation are represented by an index with Comparative Example 1 being 100. The smaller the index of this average value, the smaller the average value of RRO. The average value index is preferably smaller. The smaller the standard deviation index, the smaller the variation in RRO. A smaller standard deviation index is preferred.

  As shown in Table 1, the manufacturing method of the example has a higher evaluation than the manufacturing method of the comparative example. From this evaluation result, it is clear that the difference between the radius of curvature of the clamp surface and the tire outer diameter affects the RRO. In addition, even in a clamp surface having three region surfaces with different curvature radii as shown in FIG. 3, a tire excellent in RRO can be obtained by reducing the difference between the radius of curvature of the region surface in contact with the tire outer diameter. It is clear that it can be produced. From this evaluation result, the superiority of the present invention is clear.

  The manufacturing method described above can be widely applied to tire manufacturing methods including a preforming step in which a tread molded body is pressure-bonded to the outer peripheral surface of a carcass molded body.

DESCRIPTION OF SYMBOLS 2 ... Molding device 4 ... 1st molding device 6 ... 2nd shaping | molding device 8, 48 ... Conveyance device 14 ... Mounting stand 16 ... 1st drum 18 ... Bead receiving part 22 ····························· 24 ··········································································································································· 38, 52, 54 ... Clamping surface 40, 42 ... Spacer 44 ... Carcass molding 46 ... Tread molding

Claims (7)

It has a preforming process to form a raw cover that can be vulcanized to obtain a tire,
The preforming step is
(1) A carcass molded body in which a carcass member and a bead member are bonded to form a cylinder, and a tread molded body in which a tread member is formed in a ring shape are prepared,
A transporting device that holds the outer peripheral surface of the tread molded body and transports the tread molded body radially outward of the carcass molded body; and (2) the transport to the outer peripheral surface of the carcass molded body. The tread molded body held by the apparatus is bonded to form the raw cover to form a coalescing step,
The conveying device includes a frame having an opening and a plurality of segments located in the opening, and the plurality of segments are arranged in the circumferential direction of the outer peripheral surface of the tread molded body and are arranged in the radial direction of the outer peripheral surface. Has been made movable,
Each segment has a clamping surface that contacts the outer peripheral surface of the tread molded body,
A method for manufacturing a tire, wherein the clamp surface is formed from at least two region surfaces having different curvature radii in a cross section perpendicular to the axial direction. In the clamp surface, the radius of curvature of one region surface located on the circumferential center side is made smaller than the radius of curvature of another region surface located on the circumferential end side adjacent to the one region surface,
The manufacturing method according to claim 1, wherein the one area surface is located radially outward from the other area surface.   The manufacturing method according to claim 1, wherein an outer diameter of the tire is 230 (mm) or more and 395 (mm) or less. A conveying device for conveying a tread molded body in which a tread member made of unvulcanized rubber is formed into a ring shape,
A frame having an opening, and a plurality of segments located in the opening, the plurality of segments being arranged in the circumferential direction of the outer peripheral surface of the tread molded body and being movable in the radial direction;
Each segment has a clamping surface that contacts the outer peripheral surface of the tread molded body,
The tread molded product conveying apparatus in which the clamp surface is formed of at least two or more region surfaces having different radii of curvature in a cross section perpendicular to the axial direction. In the clamp surface, the radius of curvature of one region surface located on the circumferential center side is made smaller than the radius of curvature of another region surface located on the circumferential end side adjacent to the one region surface,
The transport apparatus according to claim 4, wherein the one area surface is located radially outward from the other area surface.   The conveying apparatus according to claim 5 or 6, wherein a center of a radius of curvature of the two or more area surfaces is positioned on a radial straight line along which the segment moves. A spacer that is detachably attached to the clamp surface;
The spacer includes an inner surface facing inward in the radial direction and an outer surface facing outward in the radial direction;
In a cross section perpendicular to the axial direction, the inner surface is formed with a radius of curvature of the other region surface, and the other region surface and the inner surface are in a state where the spacer is attached to the clamp surface. The transport apparatus according to any one of claims 4 to 6, which is located on the same arc.

Images