JP2019077079A - Green tire manufacturing method - Google Patents

Abstract

To provide a pneumatic tire manufacturing method by which appearance performance is improved by suppressing an air reservoir based on occurrence of wrinkles when folding back a protruding portion of a second ply.SOLUTION: There is provided a green tire manufacturing method. The green tire manufacturing method comprises a step of forming a first cylindrical ply 22 on a molding drum 15, a step of arranging a bead member 23 on an outer peripheral surface of the first cylindrical ply 22, a step of forming a second cylindrical ply on the first cylindrical ply 22, and a step of folding back a protruding portion of the first cylindrical ply 22 around the bead member 23. A pneumatic tire obtained by vulcanization-molding a green tire produced by a manufacturing method comprising the step of forming the second cylindrical ply including a winding stage where an inner peripheral surface and an outer end side of the second cylindrical ply are separated from a first surface part, and a bending stage where a side part to be separated therefrom is folded onto a first surface part side; and in which an outside face made of bead apex rubber 25 includes the first surface part that inclines from an apex.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method of manufacturing a green tire for a pneumatic tire.

  There is known a pneumatic tire comprising a first ply disposed inward and outward in a tire radial direction, a carcass including a second ply, and a bead apex rubber disposed radially outward of a bead core.

  A green tire of such a pneumatic tire is conventionally manufactured as follows, for example, using a cylindrical forming drum a as shown in FIG. First, a sheet-like first ply b is wound on a forming drum a to form a tubular first ply b1. Next, the bead core c and the bead apex rubber d are disposed on the outer peripheral surface of the cylindrical first ply b1. At this time, the cylindrical first ply b1 is formed so as to include the protruding portion e at the tire axial direction outer side from the bead core c. Next, the bead apex rubber d is bent inward in the axial direction. Thereby, the outer surface d1 of the bead apex rubber d is inclined radially inward toward the axially outer end portion of the bead apex rubber d from the top portion f where the height from the outer peripheral surface of the cylindrical first ply b1 is maximum. It is formed to include the first surface portion g.

  Next, the sheet-like second ply h is wound around the tubular first ply b1 to form the tubular second ply h1. The cylindrical second ply h1 is formed with a side portion i separated from the first surface portion g. Then, the protruding portion e of the cylindrical first ply b1 is folded back around the bead core c and is bonded to the side portion i of the cylindrical second ply h1.

  However, in the above-described method of manufacturing a green tire, since the side portion i is movable in the step of folding back the protruding portion e, the side portion i and the protruding portion e are not adhered with high accuracy, and both portions i, An eaves of air is formed on the e. For this reason, the pneumatic tire molded by vulcanizing the green tire manufactured by the above-described manufacturing method has a problem that the appearance performance tends to deteriorate.

JP, 2017-56680, A

  The present invention has been made in view of the above-described actual situation, and it is a main object of the present invention to provide a method of manufacturing a green tire having an improved appearance performance of a pneumatic tire based on the improvement of the manufacturing method. And

  The present invention comprises a carcass extending from the tread portion to the bead core of the bead portion through the sidewall portion, and a bead apex rubber extending outward from the bead core in the tire radial direction, the carcass comprising a first ply radially inward of the tire A method of manufacturing a green tire of a pneumatic tire including a second ply in the radial direction of the tire, comprising: winding a sheet-like first ply on a forming drum to form a tubular first ply And disposing a bead member having the bead core and the bead apex rubber on the outer peripheral surface of the cylindrical first ply, winding a sheet-like second ply on the cylindrical first ply, and forming a cylindrical shape. After the step of forming the second ply and the step of forming the cylindrical second ply, the axial direction of the tire from the bead core in the cylindrical first ply Includes the step of folding back the side protruding portion around the bead member, and in the step of arranging the bead member, the outer surface of the bead apex rubber is at a maximum height from the outer peripheral surface of the cylindrical first ply And the step of forming the cylindrical second ply, wherein the sheet-like second ply is wound in the step of forming the cylindrical second ply. A winding step in which the inner peripheral surface and the outer end side of the cylindrical second ply are separated from the first surface portion by turning, and a bending step in which the separated side portion is bent toward the first surface portion at the top portion And.

  In the method of manufacturing a green tire according to the present invention, it is preferable that the bending step bends the side portion with an elastically deformable bladder.

  In the method of manufacturing a green tire according to the present invention, it is preferable that the bending step bends the side portion with a stitch roller.

  According to the method of manufacturing a green tire of the present invention, after the side portion of the tubular second ply separated from the outer surface of the bead apex rubber is bent and pressed against the outer surface, the protruding portion of the tubular first ply from the bead core is Turn around at the turn of the part. As a result, the side portion of the cylindrical second ply and the protruding portion of the cylindrical first ply are adhered to each other with high precision without causing wrinkles and the like. Thereby, the appearance performance of the pneumatic tire can be improved.

It is sectional drawing of the pneumatic tire manufactured with the manufacturing method of one Embodiment of this invention. It is an explanatory view explaining a process of a manufacturing method concerning one embodiment of the present invention. It is an enlarged view of bead apex rubber. It is explanatory drawing explaining the process of the manufacturing method which concerns on other embodiment of this invention. (A), (b) is explanatory drawing explaining the press means of other embodiment. It is an explanatory view explaining a process of arranging a bead member of other embodiments. It is explanatory drawing explaining the process of arrange | positioning the bead member of other embodiment. It is explanatory drawing explaining the process of the conventional manufacturing method of a green tire.

Hereinafter, an embodiment of the present invention will be described based on the drawings.
FIG. 1 shows a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 manufactured by the method of manufacturing a green tire (unvulcanized tire) of the present invention, more specifically, a tire 1 for a motorcycle. FIG. The present invention is not limited to a motorcycle, and is applied to, for example, a method of manufacturing a green tire 10 of a pneumatic tire 1 for a passenger car, heavy load, and the like.

  As shown in FIG. 1, the tire 1 of the present embodiment is disposed on the carcass 6 from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4 and on the radially outer side of the carcass 6. A tread reinforcement layer 7 and a bead apex rubber 8 are included.

  The carcass 6 of the present embodiment is formed of a first ply 6A on the inner side in the tire radial direction, and a second ply 6B disposed on the outer side in the tire radial direction than the first ply 6A. Each of the plies 6A and 6B is formed by arranging carcass cords at an angle of, for example, 75 to 90 ° with respect to the tire equator C. The first ply 6A of the present embodiment is connected to both ends of the toroidal main body portion 6a extending between the bead cores 5 and 5 and the main body portion 6a, and is a folded back portion 6b which is bent outward from the tire axial direction And. The second ply 6B of the present embodiment is formed as a toroidal main body 6c extending between the bead cores 5,5. An inner end 6 d of the second ply 6 B in the tire radial direction is sandwiched between the folded portion 6 b and the bead apex rubber 8. As a result, since a force (frictional force) in the opposite direction in the tire radial direction acts on the folded back portion 6b and the second ply 6B, so-called blow through is greatly suppressed in each of the plies 6A and 6B.

  In the present embodiment, the outer end 6 e in the tire radial direction of the folded back portion 6 b is located further outward in the tire radial direction than the tread end Te. In the present embodiment, the inner end 6 d of the second ply 6 B is located on the outer surface 5 a of the bead core 5 in the tire radial direction.

  The tread reinforcing layer 7 of the present embodiment is formed of a reinforcing cord ply. In the present embodiment, the reinforcing cord ply is formed of one belt ply 7A. The tread reinforcing layer 7 is not limited to such an aspect, and may be formed of, for example, two or more belt plies, and is disposed radially outward in addition to the belt plies. It may be formed including one or more band plies (not shown).

  In the belt ply 7A, in the present embodiment, the belt cords are arranged at an angle of 10 to 35 ° with respect to the tire equator C. Both ends 7e of the belt ply 7A are located, for example, on the axially outer side and on the radially outer side of the outer end 6e of the folded portion 6b of the first ply 6A. Thus, the blow through of the first ply 6A is more effectively suppressed.

  The bead apex rubber 8 of the present embodiment is continuous with the outer surface 5a of the bead core 5 in the tire radial direction and extends outward in the tire radial direction, and the main body 6a of the first ply 6A and the main body 6c of the second ply 6B. It is arranged between.

  The tire 1 of the present embodiment includes, in addition to the above-described tire constituent members, known inner liner rubber, chafer rubber, sidewall rubber, and the like.

  Next, a method for manufacturing such a green tire 10 before vulcanization of the tire 1 will be described. The manufacturing method of this embodiment includes a step S1 of forming a cylindrical first ply, a step S2 of arranging a bead member, a step S3 of forming a cylindrical second ply, and a step S4 of folding back the cylindrical first ply. And contains. As shown in FIG. 2, in each of the steps S1 to S4, in the present embodiment, a cylindrical forming drum 15 is used.

  The green tire 10 is expanded in a toroidal shape using, for example, a shaping drum after the step S4 of folding back, and a tread forming member (not shown) or the like constituting the tread portion 2 is joined to the expanded portion, It is vulcanized and molded. A conventional process is suitably adopted for the process after such a folding process S4, so the detailed description thereof is omitted.

  Further, prior to the step S1 of forming the cylindrical first ply, for example, a sheet-like rubber member forming a chafer which is a well-known tire constituting member and an inner liner rubber (not shown) is sequentially formed on the forming drum 15. It may be wound.

  As shown in FIG. 2, for example, the forming drum 15 is disposed on both sides of the central drum portion 15a and the central drum portion 15a, and the pair of side drum portions 15b and 15b have a circumferential length smaller than that of the central drum portion 15a. And In the forming drum 15, a step portion 15c is formed between the central drum portion 15a and the side drum portion 15b. The forming drum 15 is connected to, for example, a known electric motor (not shown) that can be driven and rotated about its axis. In the present specification, the axial direction of the forming drum 15 is referred to as "the drum axial direction", and the radial direction of the forming drum 15 is referred to as the "drum radial direction".

  The forming drum 15 is not limited to such an aspect, and may be of various aspects. The forming drum 15 may have, for example, a well-known structure including a central drum portion, side drum portions, and bead lock means (not shown). The bead lock means can hold the bead core from the inner side in the drum radial direction of the first ply by expanding the diameter. After the bead core is held by the bead lock means, the central drum portion is expanded in diameter by the expansion / contraction diameter means to form a stepped portion similar to the forming drum 15 of the present embodiment.

  In the step S1 of forming the cylindrical first ply of the present embodiment, the sheet-like first ply 21 is wound on the forming drum 15, and the cylindrical first ply 22 is formed. In the present embodiment, the cylindrical first ply 22 is continuous on both sides in the drum axial direction of the first main body portion 22a disposed on the central drum portion 15a and the first main body portion 22a, and is disposed on the side drum portion 15b. And a pair of outer portions 22b, 22b.

  Next, for example, both outer portions 22b and 22b are narrowed along the step 15c to a diameter smaller than the inner diameter of the bead core 5 using a known opening / closing means (not shown).

  Next, step S2 of arranging the bead member 23 is performed. In step S2 of arranging the bead member 23 of the present embodiment, for example, a well-known holding unit (not shown) is used to press the bead member 23 against the step portion 15c to be set. The bead member 23 of the present embodiment is formed by integrally joining the bead core 24 and the bead apex rubber 25.

  Next, in the present embodiment, the step of pressing the bead apex rubber 25 into contact with the first main portion 22 a of the cylindrical first ply 22 is performed. The pressing of the bead apex rubber 25 is performed, for example, by pressing means 16 provided on the outer side of the side drum portion 15 b. The pressing means 16 has, for example, an elastically deformable bladder 17 of a known structure, and a moving device (not shown) which can move the bladder 17 in the axial direction and radial direction of the forming drum 15.

  As a result, as shown in FIG. 3, the first surface 26 and the second surface 27 are formed on the outer surface 25 a of the bead apex rubber 25. The first surface portion 26 is formed so as to be inclined inward in the radial direction from the top 25 h where the height from the outer peripheral surface 22 A of the cylindrical first ply 22 is maximum toward the drum axial direction outer end 25 e of the bead apex rubber 25 Be done. The second surface portion 27 is formed so as to be inclined radially inward from the top portion 25 h toward the drum axial direction inner end portion 25 i of the bead apex rubber 25. Thus, the bead apex rubber 25 is formed in a substantially triangular shape in the step of arranging the bead member 23.

  Next, as shown in FIG. 4, a step S3 of forming a cylindrical second ply is performed. Step S3 of forming the cylindrical second ply of the present embodiment includes a winding step S3a and a bending step S3b.

  In the winding step S3a of the present embodiment, the sheet-like second ply 28 is wound on the forming drum 15, and the cylindrical second ply 29 is formed. The cylindrical second ply 29 includes a second main body portion 29a disposed on the axial center side of the forming drum 15, and a pair of side portions 29b and 29b connected on both sides of the second main body portion 29a. In the second main body portion 29a, in the present embodiment, the inner peripheral surface 29A of the cylindrical second ply 29 is in contact with the cylindrical first ply 22 and the second surface portion 27. In the present embodiment, the side portion 29 b is a portion at which the outer end 29 e side of the inner circumferential surface 29 A is separated from the first surface portion 26.

  In the bending step S3b of this embodiment, the side portion 29b is bent inward in the radial direction of the forming drum 15 at the position of the top 25h. Thereby, the movement of the side portion 29b is suppressed. Such a bending step S3b is performed, for example, by the pressing means 16. In the present embodiment, the side portion 29 b is preferably pressed against the first surface portion 26 by the bladder 17. Thereby, the movement of the side portion 29b is further suppressed. Preferably, the bladder 17 is pressed radially inward of the forming drum 15 by pressing means 19 including, for example, a cylinder 19A with a rod.

  In the bending step S3b, in the present embodiment, the forming drum 15 is driven to rotate in the circumferential direction. Thereby, the side portion 29 b is bent inward in the drum radial direction over the entire circumference in the region pressed by the pressing means 16.

  Next, step S4 of folding back is performed. In the folding back step S4 of the present embodiment, a portion 22c of the cylindrical first ply 22 protruding outward from the bead core 24 in the drum axial direction is folded around the bead member 23. In the present embodiment, the protruding portion 22 c is folded outward in the radial direction of the forming drum 15 by the bladder 18 having a known structure provided in the side drum portion 15 b. In the folding step S4 of the present embodiment, the protruding portion 22c is attached onto the outer peripheral surface 29B of the cylindrical second ply 29 including the bead core 24 and the side portion 29b. In the present embodiment, in the bending step S3b, the side portion 29b is bent toward the first surface portion 26 and its movement is suppressed, so the protruding portion 22c and the side portion 29b are bonded without generating wrinkles or the like. . Therefore, the tire 1 manufactured using this embodiment has excellent appearance performance.

  As the bladders 17 and 18 used in the steps S3 and S4 of the present embodiment, for example, an elastic material made of synthetic rubber having high air impermeability such as butyl rubber is adopted. It is desirable that the bladders 17, 18 be made of thermoplastic urethane rubber, in particular, in order to effectively suppress the occurrence of wrinkles. The rubber thickness of such bladders 17 and 18 is preferably, for example, 1 to 3 mm. The insides of the bladders 17 and 18 are filled with, for example, pressurized air appropriately selected based on bending stress of the side portion 29 b of the second ply 28 and bending stress of the protruding portion 22 c of the cylindrical first ply 22. Ru.

  Fig.5 (a) is a front view for demonstrating the press means 16 of other embodiment. As shown in FIG. 5, the pressing means 16 of this embodiment comprises a rotatably supported stitch roller 30.

  The stitch roller 30 of the present embodiment includes a truncated cone-shaped tapered portion 31. In the present embodiment, the tapered portion 31 desirably has a shape in which the outer peripheral surface 31 a is in contact with the side portion 29 b and presses the side portion 29 b against the first surface portion 26. In the present embodiment, the stitch roller 30 is formed to include the tapered portion 31 and a cylindrical portion 32 having a circumferential length smaller than that of the tapered portion 31. The stitch roller 30 is desirably held movably in the radial and axial directions of the forming drum 15 by a moving device of a known structure not shown.

  FIG. 5 (b) is a front view for explaining the stitch roller 30 of the other embodiment. As shown in FIG. 5B, the stitch roller 30 of this embodiment is formed to include a tapered portion 31 and a cylindrical portion 33 connected to the side of the tapered portion 31 having a smaller circumferential length. In the present embodiment, the outer peripheral surface 31 a of the tapered portion 31 contacts the side portion 29 b and presses the stitch roller 30 against the first surface portion 26. In addition, the outer peripheral surface 33 a of the cylindrical portion 33 contacts the cylindrical second ply 29 on the second surface 27 to suppress the floating of the cylindrical second ply 29 from the second surface 27.

  FIG. 6 is a front view showing a step S2 of arranging the bead member 23 of another embodiment. As shown in FIG. 6, in this embodiment, after the step S1 of forming the tubular first ply 22, the bead core 24 is bonded to the outer portion 22b along the step 15c. Next, bead apex rubber 25 is disposed on outer surface 24 a of bead core 24. In this case, for example, when the bead apex rubber 25 is disposed in a state of being turned to the forming drum 15 side, the step of pressing by the above-mentioned pressing means 16 is omitted.

  FIG. 7 is a front view showing a step S2 of arranging the bead member 23 according to still another embodiment. As shown in FIG. 7, in this embodiment, after bonding the bead core 24 to the outer portion 22 b, the long rubber strip 35 for forming the bead apex rubber 25 is used as the bead core 24 and the cylindrical first ply 22. Spirally wound around the outer peripheral surface 22A of Thereby, bead apex rubber 25 is formed.

  As mentioned above, although the especially preferable embodiment of this invention was explained in full detail, this invention can be deform | transformed into a various aspect, and can be implemented, without being limited to embodiment of illustration.

DESCRIPTION OF REFERENCE NUMERALS 10 green tire 15 forming drum 22 cylindrical first ply 22A outer peripheral surface 22c protruding portion 23 bead member 25 bead apex rubber 25a outer surface 25h top 26 first surface portion 29 cylindrical second ply 29A inner peripheral surface 29e outer end 29b side portion

Claims (3)

A carcass extending from the tread portion to the bead core of the bead portion through the sidewall portion, and a bead apex rubber extending outward from the bead core in the tire radial direction;
The carcass is a method of manufacturing a green tire of a pneumatic tire including a first ply radially inward of the tire and a second ply radially outward of the tire.
Winding a sheet-like first ply on a forming drum to form a tubular first ply;
Arranging a bead member having the bead core and the bead apex rubber on the outer peripheral surface of the cylindrical first ply;
Winding a sheet-like second ply on the cylindrical first ply to form a cylindrical second ply;
And, after the step of forming the cylindrical second ply, including the step of folding back the axially outward protruding portion from the bead core in the cylindrical first ply by winding around the bead member,
In the step of arranging the bead member, the outer surface of the bead apex rubber has a radius from the top where the height from the outer peripheral surface of the cylindrical first ply is maximum toward the axial outer end of the bead apex rubber. Including a first face that slopes inward,
In the step of forming the tubular second ply, a winding step in which the inner peripheral surface and the outer end side of the tubular second ply are separated from the first surface portion by winding the sheet-like second ply. And a bending step of bending the separated side portion toward the first surface portion at the position of the top portion.   The method according to claim 1, wherein in the bending step, the side portion is bent by an elastically deformable bladder.   The method for manufacturing a green tire according to claim 1, wherein in the bending step, the side portion is bent by a stitch roller.

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