阅读说明：本技术 轮胎硫化模具以及充气轮胎的制造方法 (Tire vulcanization mold and method for manufacturing pneumatic tire ) 是由 小原将明 于 2019-05-17 设计创作，主要内容包括：技术问题：抑制在具备排气孔塞的轮胎硫化模具中发生夹胶。解决方案：轮胎硫化模具(10)具备：成型面(17),其对设置于型腔(16)的充气轮胎(1)的轮胎表面进行成型；凹部(22),其设置于成型面(17)；以及排气孔塞(25),其设置于凹部(22)。排气孔塞(25)具备：壳体(30),其为圆筒状,并在内部具有排气通路(26)；阀杆(40),其插入壳体(30),并对壳体(30)的所述排气通路(26)进行开闭；以及施力部件(27),其对阀杆(40)朝向型腔(16)侧施力。凹部(22)具备狭小部(23A、23B、24A),所述狭小部(23A、23B、24A)具有与排气孔塞(25)的壳体(30)的外径(D)大致相等的宽度(W),排气孔塞(25)配置于狭小部(24A)。(The technical problem is as follows: the occurrence of rubber entrapment in a tire vulcanization mold provided with a vent plug is suppressed. The solution is as follows: a tire vulcanization mold (10) is provided with: a molding surface (17) that molds the tire surface of the pneumatic tire (1) provided in the cavity (16); a recess (22) provided in the molding surface (17); and a vent plug (25) provided in the recess (22). The exhaust hole plug (25) is provided with: a cylindrical housing (30) having an exhaust passage (26) therein; a valve rod (40) which is inserted into the housing (30) and opens and closes the exhaust passage (26) of the housing (30); and an urging member (27) that urges the valve rod (40) toward the cavity (16). The recess (22) is provided with narrow sections (23A, 23B, 24A), the narrow sections (23A, 23B, 24A) have a width (W) substantially equal to the outer diameter (D) of the housing (30) of the vent plug (25), and the vent plug (25) is disposed in the narrow section (24A).)

1. A tire vulcanizing mold is provided with:

A molding surface for molding a tire surface of the pneumatic tire provided in the cavity;

A concave portion provided on the molding surface; and

A vent plug provided in the recess,

The exhaust hole plug is provided with:

A cylindrical housing having an exhaust passage therein;

A valve rod inserted into the housing and opening and closing the exhaust passage of the housing; and

A biasing member that biases the valve stem toward the cavity side,

The recess portion includes a narrow portion having a width substantially equal to an outer diameter of the casing of the exhaust plug,

The vent hole plug is arranged on the narrow part.

2. The tire curing mold of claim 1,

The width of the narrow portion of the recess is 0.5 times or more and 1.5 times or less the outer diameter of the housing of the exhaust hole plug.

3. The tire curing mold of claim 2,

The width of the narrow portion of the recess is 1 to 1.5 times the outer diameter of the casing of the exhaust hole plug.

4. The tire vulcanizing mold according to any one of claims 1 to 3,

The recess is frame-shaped surrounding at least one closed area.

5. The tire curing mold of claim 4,

the recess has a corner portion which is formed,

The narrow portion provided with the exhaust hole plug is provided at the corner portion of the recess.

6. a method of manufacturing a pneumatic tire, comprising: a step of placing a green tire in the tire vulcanizing mold according to any one of claims 1 to 5, and vulcanizing the green tire by applying heat and pressure.

Technical Field

the present invention relates to a tire vulcanizing mold and a method of manufacturing a pneumatic tire.

Background

As a tire vulcanizing mold, a structure is known in which a vent hole is formed in a molding surface on which a tire surface is molded, and a vent plug is fitted into the vent hole. During vulcanization molding, air interposed between the molding surface and the tire surface is allowed to escape from the vent plug.

As a vent plug, a spring vent is known which has: a cylindrical housing having an exhaust passage therein; a valve rod inserted into the housing and having a valve element for opening and closing the exhaust passage at an end portion on the molding surface side; and a biasing unit that biases the stem toward the molding surface (see, for example, patent document 1). The spring vent is opened by the biasing means by biasing the valve stem toward the molding surface, and closed by the tire surface pressing the valve stem during vulcanization molding.

Disclosure of Invention

Technical problem to be solved

In a tire vulcanizing mold provided with a spring vent, the following problems occur: when vulcanization molding is performed, before the spring vent is brought into a closed state, rubber flows into the vent passage of the spring vent, and the rubber remains in the vent passage of the spring vent, which is a problem called rubber entrapment.

The present invention addresses the problem of providing a tire vulcanization mold that can suppress the occurrence of trapping in a tire vulcanization mold provided with a spring vent, and a method for manufacturing a pneumatic tire.

(II) technical scheme

A tire vulcanization mold according to one aspect of the present invention includes: a molding surface for molding a tire surface of the pneumatic tire provided in the cavity; a concave portion provided on the molding surface; and a vent plug provided in the recess, the vent plug including: a cylindrical housing having an exhaust passage therein; a valve rod inserted into the housing and opening and closing the exhaust passage of the housing; and a biasing member that biases the valve rod toward the cavity side, wherein the recessed portion includes a narrow portion having a width substantially equal to an outer diameter of the housing of the exhaust hole plug, and the exhaust hole plug is disposed in the narrow portion.

According to this configuration, since the vent plug is provided in the narrow portion of the concave portion into which the unvulcanized rubber is hard to flow in the initial stage at the time of vulcanization molding, the unvulcanized rubber comes into contact with the valve stem from the cavity side at the time of vulcanization molding. Therefore, the unvulcanized rubber can be prevented from flowing into the exhaust passage of the exhaust hole plug in a state where the valve rod of the exhaust hole plug does not close the exhaust passage of the housing, and the occurrence of the rubber inclusion at the time of vulcanization molding of the tire can be prevented.

Further, a width of the narrow portion of the concave portion may be 0.5 times or more and 1.5 times or less an outer diameter of the case of the exhaust plug.

With this configuration, the above invention can be suitably implemented.

The width of the narrow portion of the recess may be 1 to 1.5 times the outer diameter of the casing of the vent plug.

When the width of the narrow portion of the recessed portion is smaller than the outer diameter of the casing of the vent plug, a part of the convex portion formed on the pneumatic tire by the narrow portion of the recessed portion of the tire vulcanizing mold is formed so as to bulge in accordance with the outer shape of the vent plug, and the appearance quality of the pneumatic tire is deteriorated. Therefore, by setting the width of the narrow portion of the recessed portion in an appropriate range, deterioration in the appearance quality of the tire can be suppressed.

The recess may be frame-shaped so as to surround at least one closed region.

The recess may have a corner portion, and the narrow portion provided with the exhaust hole plug may be provided at the corner portion of the recess.

Since the unvulcanized rubber during vulcanization molding flows so as to spread toward the corners of the recessed portion, the narrow portion of the vent plug is disposed at the corner of the recessed portion, and thus the air accumulated in the recessed portion of the tire vulcanization mold can be effectively discharged to the outside of the tire vulcanization mold.

A method of manufacturing a pneumatic tire according to another aspect of the present invention includes: and a step of setting a green tire in the tire vulcanizing mold, and vulcanizing the green tire by heating and pressurizing the green tire.

according to the tire manufacturing method, the occurrence of rubber entrapment in a tire vulcanization mold provided with the vent plug can be suppressed.

(III) advantageous effects

According to the present invention, the occurrence of trapping can be suppressed in a tire vulcanizing mold provided with a spring vent.

Drawings

Fig. 1 is a sectional view showing a schematic structure of a tire vulcanizing mold according to an embodiment of the present invention.

Fig. 2 is a diagram schematically showing marks formed on a sidewall portion of a tire by the tire vulcanizing mold.

Fig. 3 is a view showing a molding surface of the tire vulcanizing mold viewed in the X direction of fig. 1.

Fig. 4 is a sectional view taken along line IV-IV of fig. 3.

Fig. 5 is a cross-sectional view similar to fig. 4 showing the flow of unvulcanized rubber during vulcanization molding.

FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 3, showing the flow of unvulcanized rubber during vulcanization molding.

Description of the reference numerals

1-a pneumatic tire; 2-a tread portion; 3-sidewall portions; 4-bead portion; 5-marking; 5 a-a marker body; 5 b-a convex part; 10-tyre vulcanization mould; 11-a segment mould; 12. 13-side plate; 14. 15-bead ring; 16-a mold cavity; 17-forming surface; 18-a vent hole; 20-mark forming part; 21-marking a molding surface; 22-a recess; 23A, 23B-grooves (narrow portions); 23C-23H-grooves; 24A-corner (narrow); 24B-24H-corner; 25-spring vent; 26-an exhaust passage; 27-coil spring (urging member); 30-a housing; 31-an outer peripheral portion; 32-inner peripheral portion; 33-a conical surface; 34-a reduced diameter portion; 40-a valve stem; 41-valve core; 42-shaft portion; 43-a stop; 44-side face parts; 46-a large diameter portion; 50-unvulcanized rubber.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. The following description is merely exemplary in nature and is not intended to limit the present invention, its applications, or uses. The drawings are schematic, and the ratio of the dimensions and the like are different from those in reality.

Fig. 1 is a cross-sectional view showing a schematic structure of a tire vulcanizing mold 10 according to an embodiment of the present invention, and shows only one side in a tire radial direction (the right side in fig. 1). In fig. 1, the pneumatic tire 1 vulcanized and molded in the tire vulcanizing mold 10 is collectively shown by a virtual line (two-dot chain line). The pneumatic tire 1 is manufactured by placing a green tire in a tire vulcanizing mold 10 with a tire axis directed in the vertical direction, and vulcanizing and molding the green tire.

As shown in fig. 1, the tire vulcanizing mold 10 has: the tire vulcanizing mold 10 is a so-called segmented mold in which an annular segment mold 11, a pair of upper and lower side plates 12 and 13 located on the inner diameter side thereof, and a pair of upper and lower bead rings 14 and 15 located on the inner diameter side thereof define a cavity 16 for vulcanizing and molding the pneumatic tire 1 inside these components.

The inner wall surfaces of the segment mold 11, the side plates 12, 13, and the bead rings 14, 15 defining the cavity 16 constitute molding surfaces 17 for vulcanization molding of the tread portion 2, the sidewall portion 3, and the bead portion 4 of the pneumatic tire 1, respectively.

Further, the side plates 12 and 13 are formed with vent holes 18 that penetrate from the molding surface 17 to the outside of the tire vulcanizing mold 10 along the surface perpendicular direction. A spring vent 25 (vent plug) is fitted into the vent hole 18 at the end on the cavity 16 side.

on the molding surface 17 of the side plates 12, 13, a mark molding portion 20 for vulcanization molding the mark 5 on the side wall portion 3 of the pneumatic tire 1 is formed. The air vent 18 is formed in a recess 22 of a mark forming portion 20 described later, and exhausts air accumulated in the recess 22 to the outside of the tire vulcanizing mold 10 during vulcanization molding.

Fig. 2 is a perspective view of the mark 5 molded in the sidewall portion 3 of the pneumatic tire 1 by the tire vulcanizing mold 10 of the present embodiment.

Referring to fig. 2, the mark 5 of the present embodiment has a shape corresponding to an uppercase letter "T". Specifically, the mark 5 includes: a mark body 5a indicating "T" characters, and a convex portion 5b provided to protrude from the outer surface of the sidewall portion 3 so as to trim the mark body 5 a. Here, the mark 5 may be any one of characters, figures, or symbols, or a combination thereof. For example, the letter denoted by the symbol 5 is not limited to the capital letter "T".

Fig. 3 is a view showing the mark forming portion 20 formed on the forming surface 17 of the side plate 12 as viewed in the X direction of fig. 1.

As shown in fig. 3, the mark forming section 20 includes: a mark forming surface 21 indicating a character "T", and a recessed portion 22 recessed in the forming surface 17 of the tire vulcanizing mold 10 so as to trim the mark forming surface 21. That is, the recess 22 is in a frame shape surrounding the mark forming surface 21 as a closed region. The mark forming surface 21 of the mark forming portion 20 forms the mark main body 5a (shown in fig. 2) of the mark 5 on the sidewall portion 3 of the pneumatic tire 1 during vulcanization forming, and the concave portion 22 of the mark forming portion 20 forms the convex portion 5b (shown in fig. 2) of the mark 5 on the sidewall portion 3 of the pneumatic tire 1 during vulcanization forming.

The recess 22 has: a plurality of (eight in the present embodiment) concave grooves 23A to 23H recessed from the molding surface 17 of the tire vulcanizing mold 10 and extending substantially linearly, and a plurality of (eight in the present embodiment) corner portions 24A to 24H curved and continuous with two of the concave grooves 23A to 23H. The concave grooves 23A to 23H of the present embodiment have the same width in the direction in which the concave grooves 23A to 23H extend, respectively. Among the concave grooves 23A to 23H in the present embodiment, the widths of the concave grooves 23A and 23B are smaller than the widths of the concave grooves 23C to 23H. Specifically, the concave grooves 23A and 23B are narrow portions having a width W substantially equal to the outer diameter D of the housing 30 of the spring vent 25. Therefore, the corner portion 24A where the two grooves 23A, 23B are connected in a curved manner is also a narrow portion. That is, the recess 22 of the present embodiment includes a narrow portion including the concave grooves 23A and 23B and the corner portion 24A.

as described above, the vent hole 18 is provided in the concave portion 22 of the tire vulcanizing mold 10. Specifically, the exhaust hole 18 is provided in a corner portion 24A as a narrow portion of the recess 22. That is, the spring vent 25 fitted into the vent hole 18 is disposed at the corner 24A, which is a narrow portion, of the recess 22 of the tire vulcanizing mold 10.

Fig. 4 is a cross-sectional view taken along line IV-IV of fig. 3, and shows a longitudinal section of the vent hole 18 formed in the corner portion 24A of the recess 22 and the spring vent 25 fitted in the vent hole 18. Further, the exhaust hole 18 is formed in such a manner that the center axis coincides with the groove center in the grooves 23A, 23B. For convenience of explanation, the direction of the vent hole 18 extending from the molding surface 17 in the direction perpendicular to the surface thereof is referred to as the vertical direction, the cavity 16 side is referred to as the lower side, and the opposite side is referred to as the upper side.

As shown in fig. 4, the spring vent 25 has: a cylindrical housing 30 defining an exhaust passage 26 therein, a valve rod 40 inserted into the housing 30, and a coil spring (urging member) 27 urging the valve rod 40 toward the cavity 16 side.

The housing 30 is fitted into the exhaust hole 18 and held at the outer peripheral portion 31. The housing 30 has an inner peripheral portion 32 penetrating in the axial direction thereof, and the exhaust passage 26 is formed by the inner peripheral portion 32. A tapered surface 33 having a diameter that increases conically downward is formed at an opening portion located at the lower end of the inner peripheral portion 32, and a reduced-diameter portion 34 having a diameter that decreases upward is formed.

The valve stem 40 has: a valve body 41 located at the lower end portion, a shaft portion 42 extending upward from the upper end portion thereof, and a stopper 43 located at the upper end portion. The valve body 41 is formed in a truncated cone shape having a diameter expanding downward, and the side surface portion 44 extends parallel to the tapered surface 33 of the housing 30.

A large diameter portion 46 having a larger outer diameter than the upper portion is formed at the lower portion of the shaft portion 42. Around the shaft portion 42, a coil spring 27 is elastically provided between the large diameter portion 46 and the reduced diameter portion 34 of the inner peripheral portion 32. The stopper 43 is located above the reduced diameter portion 34, and has an outer diameter larger than the inner diameter of the reduced diameter portion 34. At the stopper 43, the valve rod 40 is moved downward by the reduced diameter portion 34, and is prevented from coming out to the cavity 16 side.

When the valve stem 40 is pushed upward against the biasing force of the coil spring 27 by the flow of rubber of the green tire that is vulcanization molded, the side surface portion 44 of the valve body 41 abuts against the mutually facing surfaces of the tapered surfaces 33 of the housing 30, and a seal portion that closes the exhaust passage 26 is formed therebetween.

In a state where the valve body 41 is in contact with the tapered surface 33, the stem top surface 45 at the lower end of the stem 40 and the case top surface 35 at the lower end of the case 30 are flush with each other, and a seal portion is formed between the stem top surface and the valve body 41 over the entire range in the vertical direction of the tapered surface 33.

As shown in fig. 3 and 4, the width W of the grooves 23A and 23B as the narrow portions is substantially equal to the outer diameter D of the housing 30 of the spring vent 25. Specifically, the width W of the concave grooves 23A, 23B of the concave portion 22 is set to be 0.5 times or more and 1.5 times or less of the outer diameter D of the housing 30. Further, if the appearance performance of the mark 5 (shown in fig. 1) formed on the sidewall portion 3 of the pneumatic tire 1 is taken into consideration, the width W of the grooves 23A, 23B of the recessed portion 22 is preferably set to be 1 time or more and 1.5 times or less the outer diameter D of the housing 30.

The length L in the direction in which the recessed grooves 23A and 23B as the narrow portions extend (extending direction) is preferably 5 times or more the outer diameter D of the housing 30.

(flow of unvulcanized rubber during vulcanization Molding)

Next, the flow of the unvulcanized rubber during vulcanization molding will be described with reference to fig. 3, 5, and 6. FIG. 5 is a cross-sectional view similar to FIG. 3 showing the flow of unvulcanized rubber during vulcanization molding. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 3, showing the flow of the unvulcanized rubber during vulcanization molding. For convenience of explanation, the direction extending from the molding surface 17 of the exhaust hole 18 in the direction perpendicular to the surface thereof is referred to as the vertical direction, the side of the cavity 16 (shown in fig. 1) is referred to as the lower side, and the opposite side is referred to as the upper side.

Referring to fig. 5 and 6, the unvulcanized rubber 50 during vulcanization molding first comes into contact with the molding surface 17 from the cavity 16 side and then flows into the recess 22.

Specifically, in the initial stage at the time of vulcanization molding, the unvulcanized rubber 50 flows into the grooves 23C to 23H in the concave portion 22. In other words, in the initial stage of vulcanization molding, the unvulcanized rubber 50 flows into the recess 22 in a narrow portion, i.e., a portion other than the grooves 23A and 23B, into which the unvulcanized rubber 50 is difficult to flow.

Further, the grooves 23A and 23B as the narrow portions make it difficult for the flow of the unvulcanized rubber 50 (see the two-dot chain line arrow G in the figure) from the grooves 23C to 23H to the spring release member 25 to reach the spring release member 25.

thereafter, as shown in fig. 5, the unvulcanized rubber 50 flows from the cavity 16 (shown in fig. 3) side toward the spring vent 25 (see arrow a in fig. 5). That is, the unvulcanized rubber 50 abuts the valve stem 40 of the spring vent 25 from the cavity 16 (shown in fig. 3) side, thereby pushing up the valve stem 40 and bringing the spring vent 25 into the closed state.

At this time, as shown in fig. 6, the unvulcanized rubber 50 flowing into the groove 23B as the narrow portion of the recess 22 flows from the corner portion 24B side to the corner portion 24A side as the narrow portion. Therefore, the air accumulated in the recess 22 flows from the corner 24B side to the corner 24A side (see the two-dot chain line in the figure). In this cross section, the spring vent 25 is disposed at the corner 24A, and the air flowing toward the corner 24A in the groove 23B is discharged from the spring vent 25 disposed at the corner 24A to the outside of the tire vulcanizing mold 10 through the vent hole 18.

According to the tire vulcanizing mold 10 described above, since the spring vent 25 is provided in the corner portion 24A, which is a narrow portion in the recess 22 into which the unvulcanized rubber 50 is hard to flow in the initial stage of vulcanization molding, the unvulcanized rubber 50 is in contact with the valve stem 40 from the cavity 16 side during vulcanization molding. Therefore, the unvulcanized rubber 50 can be suppressed from flowing into the exhaust passage 26 of the spring vent 25 in a state where the valve stem 40 of the spring vent 25 does not close the exhaust passage 26 of the housing 30, and the occurrence of the trapping at the time of vulcanization molding of the pneumatic tire 1 can be suppressed.

When the width W of the concave grooves 23A and 23B as the narrow portions of the concave portion 22 is smaller than the outer diameter D of the housing 30 of the spring vent 25, a bulging portion 5c (see fig. 2) is formed on the convex portion 5B of the mark 5 so as to correspond to the outer shape of the spring vent 25, and the appearance quality of the tire is deteriorated. Therefore, by setting the width W of the concave grooves 23A, 23B as the narrow portions of the concave portion 22 to an appropriate range (1 time or more and 1.5 times or less the outer diameter D of the housing 30), deterioration of the appearance quality of the pneumatic tire 1 can be suppressed.

Further, since the unvulcanized rubber 50 during vulcanization molding is likely to accumulate in the corner portion 24A, the air accumulated in the recess 22 of the tire vulcanizing mold 10 can be efficiently discharged to the outside of the tire vulcanizing mold 10 by disposing the spring vent 25 in the corner portion 24A, which is a narrow portion, of the recess 22.

In the present embodiment, the description has been given of the single groove 23B extending in the tire circumferential direction, but the present invention is not limited thereto, and the groove 23A as the narrow portion has the same configuration.

While the present invention has been described with reference to the specific embodiments, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention.

In the above embodiment, the recessed portion 22 is used to form the mark 5 in the side wall portion 3 of the pneumatic tire 1, but is not limited thereto, and may be used to form a stone ejector in the tread portion 2, for example.

In the above embodiment, the entire recess 22 is formed of the narrow portion, but the present invention is not limited thereto, and a part of the recess 22 may be the narrow portion, and the spring vent 25 may be disposed in the narrow portion.

in the above embodiment, a part of the recess 22 is formed by the narrow portion, but the present invention is not limited thereto, and the entire recess 22 may be formed by the narrow portion.

In the above embodiment, the spring vent 25 is disposed at the corner portion 24A, but is not limited thereto, and may be disposed at a middle portion of the concave groove 23A or a middle portion of the concave groove 23B.

In the above embodiment, the number of the spring release members 25 is not limited to one, and may be two or more.

The biasing member of the spring release member 25 is not limited to a coil spring, and may have another structure such as a belleville spring or a plate spring.

The tire vulcanizing mold 10 is not limited to the segment mold, and may be a so-called two-half mold.