JP2016153219A - Method and apparatus for producing tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent forming defects during vulcanization by preventing the rubber biting into between the molds.SOLUTION: The method for producing a tire comprises a vulcanization step for vulcanizing a green tire 1L in a vulcanization mold 17 in which, by assembling a first mold 17A and a second mold 17B, a border line 18 between the first mold 17A and the second mold 17B appears on a tire forming surface 17S, and the method further comprises a recess forming step for forming a recess 21 at the portion facing the border line 18 on an outer surface 19 of the green tire 1L before inserting the green tire 1L into the vulcanization mold 17.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a tire manufacturing method and manufacturing apparatus that can prevent molding defects during vulcanization.

  Conventionally, a tire is manufactured by vulcanizing and molding a raw tire in a vulcanization mold having a tire molding surface. The vulcanization mold is divided into a plurality of molds in order to facilitate the insertion and removal of green tires. By assembling this mold, a tire molding surface for vulcanizing the green tire is formed. A boundary line between the molds is formed on the tire molding surface.

JP 2012-158064 A

  When a plurality of molds are assembled at the time of inserting the raw tire into the vulcanization mold, so-called rubber biting is easily generated in which a part of the outer surface of the raw tire facing the boundary line is sandwiched between the molds. The rubber sandwiched between the molds remains in the mold as burnt rubber even after the raw tire is vulcanized. Since the burnt rubber adheres to the tire to be vulcanized and molded next, there is a problem in that molding defects are caused.

  The present invention has been devised in view of the actual situation as described above, and provides a tire manufacturing method and a manufacturing apparatus capable of preventing rubber biting between molds and preventing molding defects during vulcanization. Is the main purpose.

  According to a first aspect of the present invention, a raw tire is a vulcanization mold in which a boundary line between the first mold and the second mold appears on a tire molding surface by assembling the first mold and the second mold. A method of manufacturing a tire including a vulcanizing step of vulcanizing, wherein a recess is formed in a portion facing the boundary line on an outer surface of the raw tire before inserting the raw tire into the vulcanization mold It includes a forming step.

  In the tire manufacturing method according to the present invention, the first mold is a tread mold for forming a tread portion of the tire, and the second mold is a side mold for forming a sidewall portion of the tire. Is desirable.

  In the tire manufacturing method according to the present invention, it is preferable that the recess forming step includes a cutting step of forming the recess by cutting an outer surface of the green tire.

  In the tire manufacturing method according to the present invention, it is desirable that the recess forming step includes a pressing step of forming the recess by pressing an outer surface of the green tire.

  In the tire manufacturing method according to the present invention, it is preferable that the pressing step is performed by pressing a rotatable roller against an outer surface of the green tire.

  In the tire manufacturing method according to the present invention, it is desirable that the roller is heated.

  According to a second aspect of the present invention, a raw tire is a vulcanization mold in which a boundary line between the first mold and the second mold appears on a tire molding surface by assembling the first mold and the second mold. An apparatus for manufacturing a tire including a vulcanizing apparatus for vulcanizing, the apparatus including a recess forming apparatus that forms a recess in a portion facing the boundary line on the outer surface of the green tire.

  In the tire manufacturing apparatus according to the present invention, the first mold is a tread mold for forming a tread portion of the tire, and the second mold is a side mold for forming a sidewall portion of the tire. Is desirable.

  In the tire manufacturing apparatus according to the present invention, it is preferable that the recess forming device includes a pressing device that forms the recess by pressing an outer surface of the green tire.

  In the tire manufacturing apparatus according to the present invention, it is preferable that the pressing device includes pressing means pressed against an outer surface of the green tire.

  The tire manufacturing apparatus according to the present invention preferably includes a heating unit that heats the pressing unit.

  In the tire manufacturing apparatus according to the present invention, it is preferable that the pressing device includes a vibrating unit that vibrates the pressing unit.

  In the tire manufacturing apparatus according to the present invention, it is desirable that the excitation means vibrate the pressing means so as to include a vibration component in an axial direction of the raw tire.

  In the tire manufacturing apparatus according to the present invention, it is desirable that the excitation means vibrate the pressing means at a frequency of 5 Hz or more.

  In the tire manufacturing apparatus according to the present invention, it is desirable that the pressing means is a rotatable roller.

  The tire manufacturing method according to the first aspect of the present invention is a vulcanization mold in which a boundary line between the first mold and the second mold appears on the tire molding surface by assembling the first mold and the second mold. A vulcanization process for vulcanizing raw tires is included.

  The manufacturing method includes a recess forming step of forming a recess in a portion facing the boundary line on the outer surface of the green tire before inserting the green tire into the vulcanization mold. Such a recess allows the raw tire and the boundary line to be spaced apart when the raw tire is inserted into the vulcanization mold. Thereby, since the rubber bite between the first mold and the second mold can be prevented, molding defects during vulcanization can be prevented.

  The tire manufacturing apparatus according to the second aspect of the present invention is a vulcanization mold in which a boundary line between the first mold and the second mold appears on the tire molding surface by assembling the first mold and the second mold. It includes a vulcanizer for vulcanizing raw tires.

  The manufacturing apparatus includes a recess forming device that forms a recess in a portion facing the boundary line on the outer surface of the green tire before the green tire is inserted into the vulcanization mold. Such a recess allows the raw tire and the boundary line to be spaced apart when the raw tire is inserted into the vulcanization mold. Thereby, since the rubber bite between the first mold and the second mold can be prevented, molding defects during vulcanization can be prevented.

It is sectional drawing which shows the tire manufactured by the manufacturing method of the tire of this embodiment. It is sectional drawing explaining an example of a green tire formation process. It is sectional drawing explaining an example of a vulcanization | cure process. It is a fragmentary sectional view of a green tire explaining an example of a crevice formation process. It is a perspective view which shows an example of a recessed part formation apparatus. It is a side view of the press apparatus of FIG. It is a perspective view which shows another example of a recessed part formation apparatus. It is a side view of the press apparatus of FIG.

Hereinafter, an embodiment of the first invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a tire manufactured by the tire manufacturing method of the present embodiment (hereinafter, simply referred to as “manufacturing method”). The tire 1 of the present embodiment is configured as a radial tire for passenger cars. The tire 1 is not limited to a radial tire for passenger cars.

  The tire 1 includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6 and inside the tread portion 2, and the carcass. 6 and an inner liner 9 disposed on the inner side.

  The carcass 6 is composed of one carcass ply 6A. In the carcass ply 6A, carcass cords are arranged at an angle of 75 ° to 90 ° with respect to the tire equator C, for example. The carcass ply 6A of the present embodiment extends from the tread portion 2 through the pair of sidewall portions 3 and 3 to the bead portions 4 and 4 in a toroidal shape. In the carcass ply 6 </ b> A of the present embodiment, the inner end 6 e in the tire radial direction terminates without being wound up by the bead portion 4. For the carcass cord, for example, an organic fiber cord such as polyester or a steel cord is employed.

  The bead core 5 includes an inner core 5A disposed on the inner end 6e side of the carcass ply 6A and an outer core 5B. The inner core 5A is disposed on the inner surface of the carcass ply 6A in the tire axial direction. The outer core 5B is disposed on the outer surface of the carcass ply 6A in the tire axial direction. The inner core 5A and the outer core 5B are formed by winding one bead wire 5c in a spiral shape in the tire circumferential direction.

  Further, an inner apex rubber 8i is disposed on the inner surface of the inner core 5A in the tire axial direction. Further, an outer apex rubber 8o is disposed on the outer surface of the outer core 5B in the tire axial direction. These apex rubbers 8i and 8o are made of hard rubber.

  The belt layer 7 is composed of two belt plies 7A and 7B. The belt cords 7A and 7B have belt cords arranged at a small angle of 10 ° to 40 ° with respect to the tire equator C, for example. The belt plies 7A and 7B are overlapped in a direction in which the belt cords cross each other in the tire radial direction. For example, steel cords and organic fiber cords such as aramid are used for the belt cords.

  The inner liner 9 is disposed in substantially the entire area of the lumen surface 14 across the pair of bead portions 4 and 4 in a toroidal shape. The inner liner 9 is made of air-impermeable butyl rubber.

Next, the manufacturing method of this embodiment is demonstrated.
The manufacturing method according to the present embodiment includes a raw tire forming process in which a tire constituent member is attached to form a raw tire, and a vulcanizing process in which the raw tire is vulcanized.

  FIG. 2 is a cross-sectional view illustrating an example of a green tire forming process. In the raw tire forming process of the present embodiment, the rigid core 16 is used. The outer surface of the rigid core 16 substantially matches the shape of the lumen surface 14 (shown in FIG. 1) of the tire 1. Therefore, the outer surface of the rigid core 16 is configured as a tire molding surface 16 </ b> S for forming the lumen surface 14 of the tire 1.

  For the raw tire forming step, various known methods using the rigid core 16 can be appropriately employed. In this embodiment, the inner liner 9, the carcass ply 6A, the inner core 5A, the outer core 5B, the inner apex rubber 8i, the outer apex rubber 8o, the belt plies 7A and 7B, the side wall rubber 11 and the tread rubber 12 are formed. By sequentially attaching the members for the purpose to the tire molding surface 16S of the rigid core 16, the unvulcanized raw tire 1L is formed. Here, “unvulcanized” includes all aspects that have not reached complete vulcanization, and a so-called semi-vulcanized state is included in this “unvulcanized”.

  FIG. 3 is a cross-sectional view illustrating an example of a vulcanization process. In the vulcanization process of the present embodiment, a vulcanization mold 17 for vulcanizing the raw tire 1L is used. The vulcanization mold 17 of the present embodiment includes a first mold 17A and a second mold 17B.

  The first mold 17A of the present embodiment is configured as a tread mold for molding the tread portion 2 (shown in FIG. 1) of the tire 1. The first mold 17A is provided with a groove forming portion 17t that forms a groove of the tread portion 2.

  The second mold 17 </ b> B of the present embodiment is configured as a side mold for molding the sidewall portion 3 (shown in FIG. 1) of the tire 1. The second mold 17B is provided on both sides in the tire axial direction.

  The tire molding surface 17S for molding the outer surface 19 of the tire 1 is formed by assembling the first mold 17A and the pair of second molds 17B and 17B. A boundary line 18 between the first mold 17A and the second mold 17B appears on the tire molding surface 17S. The boundary line 18 of the present embodiment is formed near the buttress portion 13 (shown in FIG. 1) of the tire 1 and is continuous in the tire circumferential direction. In the present embodiment, since the pair of second molds 17B and 17B are provided, boundary lines 18 are formed on both sides of the tire molding surface 17S in the tire axial direction.

  In the vulcanization step, first, the green tire 1L is inserted into the vulcanization mold 17 together with the rigid core 16. When the green tire 1L is inserted into the vulcanization mold, the first mold 17A and the pair of second molds 17B and 17B are assembled.

  The assembly of the vulcanization mold 17 of the present embodiment is similar to the conventional case in that the tire molding surface 17S of the lower second mold 17B (not shown) and the tire molding surface 17S of the upper second mold 17B are It abuts on the outer surface 19 of the raw tire 1L. At this time, the tire molding surface 17S of the first mold 17A is disposed away from the outer surface 19 of the raw tire 1L in the tire radial direction.

  Next, the first mold 17A is moved inward in the tire radial direction to bring the tire molding surface 17S into contact with the outer surface 19 of the raw tire 1L. Accordingly, the first mold 17A and the pair of second molds 17B and 17B are closed, and the raw tire 1L is inserted into the vulcanization mold 17 together with the rigid core 16. At this time, the groove forming portion 17t of the first mold 17A bites into the tread rubber 12 of the raw tire 1L.

  Next, after the green tire 1L is inserted into the vulcanization mold 17, the rigid core 16 is heated. Thereby, the rigid core 16 and the vulcanization mold 17 heated in advance can cooperate to vulcanize and mold the raw tire 1L. The outer surface 19 of the green tire 1L is molded along the tire molding surface 17S of the vulcanizing mold 17 by the rubber flow of the tread rubber 12 during thermal vulcanization and thermal expansion.

  After the vulcanization molding, the tire 1 and the rigid core 16 are taken out from the vulcanization mold 17. Then, the tire 1 shown in FIG. 1 can be manufactured by removing the rigid core 16 from the inner cavity of the tire 1.

  By the way, the raw tire 1L includes a large amount of air between the tire constituent members. For this reason, the outer surface 19 outer diameter of the green tire 1L is larger than the outer diameter of the vulcanized tire 1 (shown in FIG. 1). Therefore, when the first mold 17A and the pair of second molds 17B and 17B are assembled when the raw tire 1L is inserted into the vulcanization mold 17, the outer surface 19 of the raw tire 1L facing the boundary line 18 is formed. So-called rubber biting that is partially sandwiched between the molds 17A and 17B is likely to occur.

  The rubber sandwiched between the first mold 17A and the second mold 17B remains in the molds 17A and 17B as burnt rubber even after the raw tire 1L is vulcanized. Such burnt rubber adheres to the tire that is then vulcanized. Therefore, there is a problem in that a tire is poorly formed and productivity is lowered.

  In the manufacturing method of the present embodiment, before inserting the raw tire 1L into the vulcanization mold 17, the recess 21 is formed in a portion P1 (shown in FIG. 2) facing the boundary line 18 on the outer surface 19 of the raw tire 1L. A recess forming step is performed. Here, the portion P1 facing the boundary line 18 on the outer surface 19 of the raw tire 1L is defined as the boundary line 18 of the vulcanization mold 17 and the outer surface 19 of the raw tire 1L when the recess 21 is not formed. It is an area including the place where it abuts. Since there is a pair of boundary lines 18 corresponding to the pair of second molds 17B, 17B, there is also a pair of portions P1. FIG. 4 is a partial cross-sectional view of a green tire for explaining an example of the recess forming step.

  In the recess forming step, after the raw tire 1L is inserted into the vulcanization mold 17, the tire axial distance between the pair of portions P1 (shown in FIG. 2) facing the boundary line 18 on the outer surface 19 of the raw tire 1L. However, the recess 21 is formed so as to be smaller than the interval in the tire axial direction of the tire molding surface 17S in the vicinity of the pair of boundary lines 18.

  In this embodiment, since the boundary line 18 is formed continuously in the tire circumferential direction, it is desirable that the recess 21 is also formed continuously in the tire circumferential direction. Moreover, the recessed part 21 of this embodiment is provided in the both sides of a tire axial direction, respectively. Although the recessed part 21 of this embodiment is formed in the cross-sectional triangle shape, it is not necessarily limited to such an aspect.

  In the recess forming process of the present embodiment, the outer surface 19 of the raw tire 1L is cut to form the recess 21 (cutting process). For cutting the recess 21, for example, a tire groover (not shown) for carving a groove of the tire 1 can be used. By using such a tire groover, the recess 21 can be easily formed in the raw tire 1L.

  By forming such a recess 21 in the raw tire 1L, after the raw tire 1L is inserted into the vulcanization mold 17, the raw tire 1L and the boundary line 18 can be arranged apart from each other. Thereby, the rubber biting between the first mold 17A and the second mold 17B can be prevented.

  Even if the concave portion 21 is formed in the raw tire 1L, the tire 1 along the tire molding surface 17S of the vulcanization mold 17 is caused by the rubber flow of the tread rubber 12 and the like during the vulcanization and the thermal expansion of the rubber. The outer surface 19 is molded. For this reason, the molding defect of the tire 1 does not occur. In addition, after the first mold 17A and the pair of second molds 17B and 17B are assembled, the gap formed in the boundary lines 18 and 18 is very small (for example, about 1 μm to 40 μm). For this reason, even when the outer surface 19 of the green tire 1L faces the boundary line 18 during vulcanization, rubber can be prevented from entering between the first mold 17A and the second mold 17B. Accordingly, no burnt rubber remains in the molds 17A and 17B.

  Further, after the raw tire 1L is inserted into the vulcanization mold 17 (shown in FIG. 3), the shortest distance L1 with the boundary line 18 of the vulcanization mold 17 is 1.0 mm to 3.0 mm. The recess 21 of the raw tire 1L is preferably formed. When the shortest distance L1 is less than 1.0 mm, there is a possibility that the rubber biting between the first mold 17A and the second mold 17B cannot be sufficiently prevented. On the contrary, if the shortest distance L1 exceeds 3.0 mm, the rubber volume of the raw tire 1L is greatly reduced, and there is a possibility that molding defects may occur. From such a viewpoint, the shortest distance L1 is preferably 1.5 mm or more, and preferably 2.5 mm or less.

  Further, after the raw tire 1L is inserted into the vulcanizing mold 17 (shown in FIG. 3), the width W1 of the recess 21 of the raw tire 1L is preferably set to 4.0 mm to 12.0 mm. If the width W1 is 4.0 mm or less, rubber engagement between the first mold 17A and the second mold 17B may not be sufficiently prevented. Conversely, if the width W1 exceeds 12.0 mm, the rubber volume of the raw tire 1L may be greatly reduced. From such a viewpoint, the width W1 is preferably 5.0 mm or more, and preferably 11.0 mm or less.

  Although the aspect in which the cutting process which cuts the outer surface 19 of raw tire 1L was illustrated in the recessed part formation process of this embodiment was illustrated, it is not necessarily limited to such an aspect. For example, the outer surface 19 of the raw tire 1L may be pressed to form the recess 21 (pressing step).

  FIG. 5 shows an example of a recess forming apparatus M1 that performs the recess forming step. The recess forming device M1 includes a pressing device M10 that performs the pressing step. The pressing device 10 includes a pressing unit 26 pressed against the outer surface of the raw tire 1L, an arm 31 that supports the pressing unit 26, and a driving unit (not shown) that presses the pressing unit 26 against the outer surface of the raw tire 1L via the arm. )).

  FIG. 6 is a side view of the pressing means 26. The pressing means 26 according to the embodiment includes a base portion 27, a pair of support pieces 28 and 28, and a roller 29. The base 27 is formed in a substantially rectangular plate shape in plan view. The base 27 is supported by the arm 31 and driving means (not shown) so as to be movable with respect to the raw tire 1L. The pair of support pieces 28, 28 are fixed so as to protrude from one surface of the base portion 27. The pair of support pieces 28 and 28 are spaced apart from each other in the length direction of the base portion 27 (in this embodiment, the vertical direction).

  The roller 29 is formed in a disk shape. The roller 29 is rotatably supported by a support shaft 33 extending between the pair of support pieces 28. As shown in FIG. 6, a molding surface 29 s for forming the recess 21 is formed on the outer peripheral surface of the roller 29. The molding surface 29s of the present embodiment is inclined with respect to the axial center direction of the roller 29 so that the concave portion 21 (shown in FIG. 4) as described above is formed.

  In the pressing step, first, the molding surface 29s of the roller 29 is pressed against a portion P1 (shown in FIG. 2) facing the boundary line 18 on the outer surface 19 of the raw tire 1L. Then, the raw tire 1L is rotated in the tire circumferential direction. In the present embodiment, the rotation of the raw tire 1L is performed through gripping means (not shown) fixed to the rigid core 16.

  The rotation of the raw tire 1L in the tire circumferential direction causes the roller 29 to roll on the outer surface 19 of the raw tire 1L. By the rolling of the roller 29, a portion P1 (shown in FIG. 2) facing the boundary line 18 on the outer surface 19 of the raw tire 1L is continuously pressed in the tire circumferential direction. Thereby, the recess 21 is formed in the raw tire 1L.

  In order to effectively form such a recess 21, it is desirable that the roller 29 is heated. Thereby, the part pressed against the roller 29 in the raw tire 1 </ b> L is softened by the heat of the roller 29, and the recess 21 can be efficiently formed.

  The heating means for heating the roller 29 can be adopted as appropriate. In the present embodiment, the roller 29 is heated via the pair of support pieces 28 and 28 and the support shaft 33 by a heater (not shown) embedded in the pair of support pieces 28 and 28. The roller 29 may be heated by a heater (not shown) embedded in the roller 29. The temperature of the roller 29 can be set as appropriate, but is preferably set to 45 ° C. to 55 ° C. (50 ° C. in the present embodiment), for example.

  The force (pressing force) for pressing the molding surface 29s of the roller 29 against the raw tire 1L can be appropriately set depending on the structure of the tire 1 and the hardness of the unvulcanized rubber of the raw tire 1L. For example, when the raw tire 1L is a radial tire for a passenger car, the pressing force is desirably set to about 150N to 300N (230N in this embodiment).

  Further, the rotational speed Va (shown in FIG. 5) of the raw tire 1L can be set as appropriate according to the structure of the tire 1 and the like. Note that if the rotational speed Va is low, it may take a long time to press the raw tire 1L. Conversely, if the rotational speed Va is high, the raw tire 1L cannot sufficiently follow the pressure of the roller 29, and the concave portion 21 may not be formed with high accuracy. From such a viewpoint, the rotation speed Va is desirably about 3 degrees / second to 8 degrees / second (5 degrees / second in the present embodiment).

  The driving means (not shown) for moving the pressing means 26 has the same dimensions as the outer surface 19 (shown in FIG. 2) of the raw tire 1L and the tire molding surface 17S (shown in FIG. 3) of the vulcanization mold 17. It is desirable to be automatically controlled based on this. Thereby, after the raw tire 1L is inserted into the vulcanization mold 17, the recess 21 that can separate the raw tire 1L and the boundary line 18 can be reliably formed. And since a recessed part formation process can be automated, manufacturing cost can be held down. The dimensions of the outer surface 19 of the raw tire 1L and the dimensions of the tire molding surface 17S of the vulcanization mold 17 are preferably measured in advance prior to the recess forming step.

  In the recessed portion forming step of the present embodiment, there has been exemplified an embodiment in which either the cutting step of cutting the outer surface 19 of the raw tire 1L or the pressing step of pressing the outer surface 19 of the raw tire 1L is performed. However, the present invention is not limited to such an embodiment. For example, both the cutting process and the pressing process may be performed. In addition, about the implementation order of a cutting process and a press process, it can set suitably. For example, the pressing process may be performed after the cutting process. Thereby, since the roller 29 is pressed after the outer surface 19 of the raw tire 1L is cut, the concave portion 21 can be formed more quickly. Further, since the cutting surface of the raw tire 1L is leveled by the roller 29, rubber biting between the first mold 17A and the second mold 17B can be effectively prevented.

  Although the manufacturing method of this embodiment illustrated the aspect in which a recessed part is formed in the outer surface 19 of the raw tire 1L formed in the rigid core 16, it is not necessarily limited to such an aspect. For example, an annular tire constituent member affixed to a cylindrical molding drum (not shown) is inflated on the outer surface of a raw tire (not shown) formed in a toroidal shape by a bladder (not shown). May be formed. Thereby, also in the manufacturing method of this embodiment, rubber biting between the first mold 17A and the second mold 17B can be prevented. In this embodiment, it is desirable that the recess 21 is formed in a state where the raw tire 1L is inflated.

  FIG. 7 shows a recess forming apparatus M1 that performs the recess forming step. FIG. 8 shows a pressing device M10 included in the recess forming device M1. As shown in FIGS. 7 and 8, the recess forming step may include a vibration step for vibrating the roller 29. In the process of forming the recess 21 on the outer surface 19 of the raw tire 1L in the recess forming process, the roller 29 vibrates to promote the formation of the recess 21. Thereby, the time which a recessed part formation process requires can be shortened, and the production efficiency of a tire improves.

  Hereinafter, a tire manufacturing apparatus according to an embodiment of the second invention will be described. The tire manufacturing apparatus includes a recess forming apparatus M1 shown in FIGS. The recess forming device M1 includes a pressing device M10 that performs the pressing step. The pressing device M10 includes a pressing unit 26 and the like. The pressing means 26 includes a base portion 27, a pair of support pieces 28 and 28, and a roller 29. The pressing device M10, the pressing means 26, the base 27, the support piece 28, the roller 29, etc. have already been described in the first invention.

  The pressing means 26 forms a recess 21 at a position facing the boundary line 18 on the outer surface 19 of the raw tire 1L. The recess 21 extends in the tire axial direction. Since the boundary line 18 between the first mold 17A and the second mold 17B is formed continuously in the tire circumferential direction, the recess 21 is desirably formed continuously in the tire circumferential direction. By forming the recess 21 by the pressing means 26, the raw tire 1 </ b> L and the boundary line 18 can be spaced apart when the raw tire 1 </ b> L is inserted into the vulcanization mold 17. Thereby, since the rubber bite between the first mold 17A and the second mold 17B can be prevented, molding defects during vulcanization can be prevented.

  In the present embodiment, the pressing device M10 includes a heating unit (not shown) that heats the pressing unit 26. Examples of the heating means include a heater using electric energy as a heat source. The heating means is embedded in the support piece 28 or the roller 29, for example. The heat of the heating means is transmitted to the outer surface 19 of the raw tire 1L via the roller 29, and the rubber of the raw tire 1L is softened. Thereby, the roller 29 can be easily embedded in the rubber of the outer surface 19, and the recessed part 21 can be formed efficiently.

  The pressing device M10 shown in FIG. 7 is different from the pressing device M10 shown in FIG. 5 in that it includes a vibrating means 41 that vibrates the pressing means 26. The form of the vibration means 41 is not particularly limited. For example, an impulse hammer may be used, and an inertia shaker may be used. In the present embodiment, a so-called modal inertia shaker that vibrates a test article using the reaction force of the vibration of the inertia mass can be applied as the vibration means 41. A modal inertia shaker is preferable because it has high vibration reproducibility and can be easily mounted on the pressing device M10.

  The form in which the vibration means 41 is mounted is not particularly limited. In this embodiment, as shown in FIGS. 7 and 8, the vibration means 41 is mounted on the base 27, but the vibration means 41 may be directly mounted on the roller 29, and The vibration means 41 may be mounted.

  The vibration means 41 drives the roller 29 to vibrate. Thereby, the roller 29 is pressed against the outer surface 19 of the raw tire 1L while vibrating, and the formation of the recess 21 is promoted. Therefore, the time required for forming the recess 21 can be shortened, and the production efficiency of the pneumatic tire is improved.

  For example, the vibration means 41 drives and vibrates the roller 29 so as to include the amplitude component in the axial direction of the raw tire 1L. Thereby, it is possible to further reduce the time required for forming the recess 21.

  In the vibration of the roller 29 by the vibration means 41, it is desirable that the frequency and amplitude take into consideration the influence on the equipment (for example, loosening of bolts). The frequency by the vibration means 41 is preferably 5 Hz or more, for example. Thereby, it is possible to further reduce the time required for forming the recess 21.

  If the temperature of the roller 29 is too high, the rubber on the outer surface 19 against which the roller 29 is pressed is burned or peeled off. On the other hand, if the temperature of the roller 29 is too low, the time required for forming the recess 21 may not be sufficiently shortened. Accordingly, the temperature of the roller 29 is appropriately determined in consideration of the rubber state of the outer surface 19 where the recess 21 is formed and the time required for forming the recess 21. In the pressing device M10 shown in FIG. 7, it is possible to shorten the time required for forming the recess 21 while setting the temperature of the roller 29 lower than that of the pressing device M10 shown in FIG.

  Various waveforms can be applied to the vibration waveform of the excitation means 41. For example, the vibration wave of the vibration means 41 is not only a single frequency and single amplitude sine wave but also a random wave formed by combining a plurality of sine waves having different vibration frequencies and amplitudes, or in a short time. A shock wave that causes a specific waveform can be set as appropriate. Although any vibration wave is used, the time required for forming the recess 21 can be shortened, but the sine wave that is regular vibration can stably obtain the effect of the time reduction.

  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.

  For example, an annular or arcuate pressing tool may be applied to the pressing means 26 instead of the roller 29. When an annular pressing tool is applied, the time required for forming the recess 21 can be further shortened.

  Ten raw tires each having the basic structure shown in FIG. 2 were produced, and a vulcanizing step for vulcanizing the raw tires was carried out (Example 1, Example 2 and Comparative Example). In Example 1 and Example 2, before the green tire was inserted into the vulcanization mold, a recess forming step for forming a recess in a portion facing the boundary line on the outer surface of the green tire was performed. On the other hand, in the comparative example, the recess forming step was not performed.

  In the recessed portion forming step of Example 1, the pressing step for forming the recessed portion was performed by pressing the outer surface of the green tire. In the pressing step of Example 1, the pressing means shown in FIGS. 5 and 6 was used. In the recessed portion forming step of Example 2, the cutting step of forming the recessed portion was performed by cutting the outer surface of the raw tire. In the cutting process of Example 2, a tire groover (not shown) was used.

And about Example 1, Example 2, and the comparative example, the presence or absence of the rubber | gum biting by which a part of outer surface of a green tire was pinched | interposed between molds was confirmed visually after the vulcanization process. The common specifications are as follows.
Tire size: 245 / 45R18
Example 1 and Example 2:
Minimum distance L1: 2.0mm
Recess width W1: 8.0 mm
Example 1:
Roller temperature: 50 ° C
Raw tire rotation speed: 3 rotations Raw tire rotation speed Va: 5degree / second
Pressure on raw tire: 230N

  As a result of the test, in Example 1 and Example 2, rubber biting did not occur in all the raw tires (10 in total). On the other hand, in the comparative example, rubber biting occurred in 10 of all the green tires (10 in total). Therefore, it was confirmed that Example 1 and Example 2 can prevent the rubber from being caught between the molds and can prevent molding defects during vulcanization.

  Moreover, the recessed part 21 was formed using the recessed part formation apparatus M1 which does not include the vibration means 41 shown in FIG. 5, and the recessed part formation apparatus M1 which includes the vibration means 41 shown in FIG. The temperatures of the rollers 29 were set to 50 ° C., and the time required for forming the recesses 21 was measured while changing the rotation speed of the raw tire 1L. In the recess forming apparatus M1 that does not include the vibration means 41, the time required for forming the recess 21 was 3 rotations at a rotational speed Va of 5 degrees / second, that is, 216 seconds. On the other hand, in the recess forming apparatus M1 including the vibrating means 41, the time required for forming the recess 21 was reduced to 2 rotations, that is, 40 seconds at the rotation speed Va of 9 degrees / second. From the above, it was confirmed that the time required for forming the recess 21 was shortened by the vibration means 41 and the production efficiency of the pneumatic tire was improved.

1L Raw Tire 17 Vulcanizing Mold 17A First Mold 17B Second Mold 18 Boundary Line 19 Outer Surface 21 Concave 26 Pressing Means 29 Roller 41 Exciting Means M1 Concave Forming Device M10 Pressing Device

Claims (16)

A vulcanization step of vulcanizing the raw tire with a vulcanization mold in which a boundary line between the first mold and the second mold appears on the tire molding surface by assembling the first mold and the second mold; A tire manufacturing method comprising:
A tire manufacturing method comprising: forming a recess in a portion facing the boundary line on the outer surface of the green tire before inserting the green tire into the vulcanization mold. The first mold is a tread mold for forming a tread portion of the tire,
The tire manufacturing method according to claim 1, wherein the second mold is a side mold that molds a sidewall portion of the tire.   The tire manufacturing method according to claim 1, wherein the recess forming step includes a cutting step of forming the recess by cutting an outer surface of the green tire.   The tire manufacturing method according to claim 1, wherein the recess forming step includes a pressing step of forming the recess by pressing an outer surface of the green tire.   The tire pressing method according to claim 4, wherein the pressing step is performed by pressing a rotatable roller against an outer surface of the green tire.   The tire manufacturing method according to claim 5, wherein the roller is heated.   The tire manufacturing method according to claim 5, wherein the recess forming step includes a vibration step for vibrating the roller. A vulcanizing device for vulcanizing a raw tire with a vulcanization mold in which a boundary line between the first mold and the second mold appears on a tire molding surface by assembling the first mold and the second mold. A tire manufacturing apparatus,
An apparatus for manufacturing a tire, comprising: a recess forming device that forms a recess in a portion facing the boundary line on the outer surface of the green tire. The first mold is a tread mold for forming a tread portion of the tire,
The tire manufacturing apparatus according to claim 8, wherein the second mold is a side mold that molds a sidewall portion of the tire.   The tire manufacturing apparatus according to claim 8, wherein the recess forming device includes a pressing device that forms the recess by pressing an outer surface of the green tire.   The tire manufacturing apparatus according to claim 10, wherein the pressing device includes pressing means pressed against an outer surface of the green tire.   The tire manufacturing apparatus according to claim 11, further comprising a heating unit that heats the pressing unit.   The tire manufacturing apparatus according to claim 11, wherein the pressing device includes a vibrating unit that vibrates the pressing unit.   14. The tire manufacturing apparatus according to claim 13, wherein the vibration means vibrates the pressing means so as to include a vibration component in an axial direction of the raw tire.   The tire manufacturing apparatus according to claim 13 or 14, wherein the vibration means vibrates the pressing means at a frequency of 5 Hz or more.   The tire manufacturing apparatus according to claim 11, wherein the pressing means is a rotatable roller.

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