Bladder manufacturing apparatus and method for manufacturing a bladder using the same

Abstract

To provide bladder manufacturing equipment and manufacturing methods that enable easy cutting of cup sections.SOLUTION: A bladder manufacturing apparatus 1 includes an outer mold 2, cores 3, and an injection head 4. Injection head 4d has injection holes 4a for injecting uncured material into the molding space between outer mold 2 and core 3. The injection head 4 has a convex surface for molding a concave cup portion B2 between the core 3 and itself. In a cross section including the axis centerline Bc of the bladder in the closed state of the outer mold 2, the space between the convex surface and the core 3 includes a thin-walled forming section with a minimum gap of 5 mm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a bladder manufacturing apparatus and a method for manufacturing a bladder using the same.

Background Art

[0002] The following Patent Document 1 describes a bladder vulcanization molding die for manufacturing a bladder. The bladder is obtained by press-fitting rubber for injection molding into the bladder vulcanization molding die and vulcanizing and molding it. This bladder vulcanization molding die includes a die for molding the outer surface shape of the bladder and a core disposed in the die for molding the inner surface shape of the bladder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The bladder molded by the die has a cup portion that is concave on its axial center line. In recent years, there has been a case where the bladder is used after cutting the cup portion to form an opening, but there has been a problem that a lot of labor is required to perform this cutting process accurately.

[0005] The present invention has been devised in view of the above actual situation, and the main object is to provide a bladder manufacturing apparatus capable of easily cutting a cup portion and a method for manufacturing a bladder using the same.

Means for Solving the Problems

[0006] The present invention relates to a bladder manufacturing apparatus for manufacturing a bladder, including an outer mold that can be opened and closed vertically to form the outer surface of the bladder, a core disposed inside the outer mold for forming the inner surface of the bladder, and an injection head attached to the outer mold and having an injection hole for injecting an uncured material into the molding space between the outer mold and the core. The injection head includes a convex surface for forming a concave cup portion located on the axial center line of the bladder between the injection head and the core. In a cross section including the axial center line of the bladder in the closed state of the outer mold, the space between the convex surface and the core includes a thin-wall forming portion with a minimum gap of 5 mm or less.

[0007] In the bladder manufacturing apparatus according to the present invention, it is desirable that the thin-wall forming portion is formed at a position where the cup portion of the molded bladder is to be cut.

[0008] In the bladder manufacturing apparatus according to the present invention, it is desirable that the outer diameter of the convex surface of the injection head gradually increases toward the upstream side in the supply direction of the uncured material from the injection hole, and the thin-wall forming portion is formed at a position where the outer diameter of the convex surface is maximum.

[0009] In the bladder manufacturing apparatus according to the present invention, it is desirable that the injection head includes a tip portion forming the convex surface and a neck portion located upstream in the supply direction of the uncured material of the tip portion, and the neck portion is formed to have a smaller diameter than the tip portion so as to be continuous with the tip portion via a step.

[0010] In the bladder manufacturing apparatus according to the present invention, it is desirable that a plurality of through holes extending in the supply direction of the uncured material are formed in the injection head, and each of the through holes has one end opening at the convex surface and the other end communicating with the molding space between the neck portion and the core.

[0011] In the bladder manufacturing apparatus according to the present invention, it is desirable that the through holes are formed at equal intervals around the injection hole.

[0012] It is desirable that the minimum diameter of the through hole of the bladder manufacturing apparatus according to the present invention is 1.5 to 5.0 mm.

[0013] It is desirable that the injection head of the bladder manufacturing apparatus according to the present invention is detachable from the outer mold.

[0014] The present invention is a method for manufacturing a bladder using the bladder manufacturing apparatus according to any one of claims 1 to 8, including a step of molding a bladder using the bladder manufacturing apparatus, a step of opening the outer mold and removing the bladder from the core, and a step of cutting the cup portion at the thin-walled portion formed at the thin-walled forming portion of the removed bladder.

[0015] It is desirable that the cutting step of the bladder manufacturing method according to the present invention is performed without using a cutting tool.

Effect of the Invention

[0016] By adopting the above configuration, the bladder manufacturing apparatus of the present invention and the bladder manufacturing method using the same can manufacture a bladder capable of easily cutting the cup portion of the bladder.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Best Mode for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a bladder manufacturing apparatus (hereinafter, may be simply referred to as "apparatus") 1 according to the present embodiment. In the apparatus 1 of the present embodiment, a bladder B (shown in FIG. 2) for vulcanizing and molding a pneumatic tire (not shown) is manufactured. Note that the apparatus 1 of the present invention is not limited to manufacturing the bladder B as described above.

[0019] FIG. 2 is a longitudinal sectional view of the bladder B manufactured by the apparatus 1 cut along its axis center line Bc. As shown in FIG. 2, the bladder B has a rubber balloon shape with a circular inlet B1. For example, a fluid (not shown) such as steam for bulging the bladder B after manufacturing flows into the inlet B1. The bladder B includes, for example, an outer surface Ba and an inner surface Bb opposite to the outer surface Ba. In the bladder B of the present embodiment, the outer surface Ba and the inner surface Bb are formed to be continuous at the inlet B1.

[0020] Further, in the present embodiment, the bladder B includes a concave cup portion B2 located on the axis center line Bc of the bladder B and a main portion B3 extending from the cup portion B2 to the outside of the axis center line Bc and continuous with the inlet B1. In this way, in the present embodiment, the cup portion B2 is spaced apart from the inlet B1 in the direction of the axis center line Bc. The axis center line Bc of the bladder B is, in this specification, a straight line passing through the center of the inlet B1. The bladder B is cut between the cup portion B2 and the main portion B3 as will be described later. The cut bladder B has, for example, its main portion B3 attached to a center post type vulcanizer (not shown) of a well-known structure.

[0021] In this embodiment, the main part B3 of the bladder B is continuous with the cup part B2 and extends in the direction of the axial center line Bc, and includes a thick part 5a having the maximum thickness among the main part B3 and a medium-thick part 5b having a thickness smaller than that of the thick part 5a. The medium-thick part 5b extends, for example, from the thick part 5a to the outside of the axial center line Bc and includes a maximum diameter part 5e where the bladder B has the maximum diameter.

[0022] Such a bladder B is formed by vulcanizing and molding an uncured material G. As the uncured material G, for example, a well-known unvulcanized rubber material composed of a mixture of synthetic rubber, carbon black, etc. is preferably used.

[0023] As shown in FIG. 1, in this embodiment, the apparatus 1 includes an outer mold 2 for molding the outer surface Ba of the bladder B, a core 3 for molding the inner surface Bb of the bladder B, and an injection head 4 having an injection hole 4a for injecting the uncured material G. In the apparatus 1 of this embodiment, the bladder B is manufactured such that the cup part B2 is located above the inlet B1. In the apparatus 1 of this embodiment, the axial center line Bc coincides with the vertical direction.

[0024] The outer mold 2 of this embodiment includes a first mold 6 capable of molding the upper side of the bladder B and a second mold 7 capable of molding the lower side of the bladder B. The first mold 6 and the second mold 7 are held so as to be vertically openable and closable by an opening and closing device (not shown) having a well-known structure.

[0025] The injection head 4 is attached to the first mold 6 of this embodiment. In this embodiment, the first mold 6 includes a base part 11 having a positioning part 6a for positioning the injection head 4 and a lid part 12 disposed above the base part 11. In this embodiment, the positioning part 6a is formed as a hole part 13a penetrating the base part 11 vertically. The first mold 6 detachably holds the injection head 4 with a well-known fastening tool such as a bolt or a screw, for example.

[0026] The lid portion 12 is provided with, for example, a supply channel 12a for supplying the uncured material G to the injection head 4 attached to the base portion 11. Since the lid portion 12 has a well-known structure in this embodiment, a detailed description thereof will be omitted.

[0027] The second mold 7 of this embodiment includes a holding portion 7a for holding the core 3. In this embodiment, the holding portion 7a is formed as a hole portion 13b that penetrates the second mold 7 vertically. Since the second mold 7 has a well-known structure in this embodiment, a detailed description thereof will be omitted.

[0028] The core 3 of this embodiment is disposed inside the outer mold 2. The core 3 is disposed, for example, so as to be covered by the base portion 11 of the first mold 6 and the second mold 7. Since the core 3 has a well-known structure in this embodiment, a detailed description thereof will be omitted.

[0029] FIG. 3 is a perspective view of the injection head 4. FIG. 4 is a longitudinal sectional view of the injection head 4. As shown in FIGS. 3 and 4, the injection head 4 of this embodiment includes, for example, a tip portion 15, a neck portion 16 connected to the tip portion 15, and a root portion 17 connected to the neck portion 16. The injection head 4 includes an injection channel 19 for supplying the uncured material G to the injection hole 4a. In this embodiment, the injection channel 19 extends from the tip portion 15 to the root portion 17. In this embodiment, the injection channel 19 extends vertically (shown in FIG. 1).

[0030] The tip portion 15 is formed, for example, in a hemispherical shape. The tip portion 15 of this embodiment includes a convex surface 20 for forming the cup portion B2 between the tip portion 15 and the core 3. The convex surface 20 is provided with, for example, an injection hole 4a. In this embodiment, the outer diameter of the convex surface 20 gradually increases toward the upstream side in the supply direction of the uncured material G from the injection hole 4a. In this embodiment, the injection hole 4a is provided at the most distal position of the convex surface 20.

[0031] The head portion 16 is arranged on the upstream side in the supply direction of the uncured material G in the injection flow path 19 with respect to the tip portion 15. The head portion 16 of the present embodiment is formed to have a smaller diameter than the tip portion 15 so as to be continuous with the tip portion 15 via a step. In other words, the tip portion 15 of the present embodiment includes a step surface 21 that extends from the outer end 20e of the convex surface 20 toward the head portion 16 (perpendicular to the axial center line Bc in the present embodiment).

[0032] The head portion 16 of the present embodiment includes a thick-walled forming surface 22 for forming the thick-walled portion 5a (shown in FIG. 2) of the main portion B3 of the bladder B between the core 3. The thick-walled forming surface 22 extends, for example, in the longitudinal direction of the thick-walled portion 5a (the supply direction of the uncured material G) and is continuous with the step surface 21.

[0033] The root portion 17 is arranged on the upstream side in the supply direction of the uncured material G in the injection flow path 19 with respect to the head portion 16. The root portion 17 of the present embodiment is embedded in the hole portion 13a (shown in FIG. 1) of the base portion 11. The root portion 17 has, for example, a contact surface 17a that contacts the lid portion 12. An acceptance hole 24 that is continuous with the supply flow path 12a of the lid portion 12 is provided in the contact surface 17a of the present embodiment. The acceptance hole 24 is located on the axial center line Bc in the present embodiment. Thereby, the injection flow path 19 of the present embodiment is located on the axial center line Bc.

[0034] Such an injection head 4 is preferably formed of, for example, a metal material, more preferably an iron-based metal, and even more preferably a carbon steel such as S45C.

[0035] As shown in FIG. 1, in such an apparatus 1, in the present embodiment, in the closed state of the outer mold 2, a molding space 25 in which the bladder B is molded is formed between the core 3, the outer mold 2, and the injection head 4. The uncured material G is injected into the molding space 25 from the injection hole 4a of the injection head 4. Thereby, the bladder B is formed in accordance with the shape of the molding space 25. The "closed state of the outer mold 2" is a state in which the first mold 6 and the second mold 7 are closed including the core 3 and the uncured material G is injected from the injection head 4, and is shown in FIG. 1.

[0036] FIG. 5 is an enlarged view of FIG. 1. FIG. 6 is a cross-sectional view taken along line A-A of FIG. 5. As shown in FIGS. 5 and 6, the molding space 25 includes a cup space portion 25a for molding the cup portion B2 of the bladder B and a main space portion 25b for molding the main portion B3 of the bladder B. The main space portion 25b is, for example, continuous with the cup space portion 25a and extends outside the axial center line Bc.

[0037] In the cross-section including the axial center line Bc of the bladder B, the molding space 25 of the present embodiment includes a thin-wall forming portion 27 having a minimum gap d1 of 5 mm or less between the convex surface 20 and the core 3. The thin-wall forming portion 27 of the present embodiment is formed in an annular shape.

[0038] In the present embodiment, the thin-wall forming portion 27 is arranged to extend from the cup space portion 25a and be continuous with the main space portion 25b. The thin-wall forming portion 27 is formed at a position where the outer diameter of the convex surface 20 is maximum. The thin-wall forming portion 27 is formed at a planned cutting position K for cutting the cup portion B2. The thin-wall forming portion 27 of the present embodiment forms the thin-wall portion 5c (shown in FIG. 2) of the bladder B.

[0039] Since the minimum gap d1 of the thin-wall forming portion 27 is 5 mm or less, the bladder B can be easily cut at the thin-wall portion 5c. From such a viewpoint, the minimum gap d1 is preferably 1 mm or less, and more preferably 0.6 mm or less. If the minimum gap d1 is excessively small, it becomes difficult for the uncured material G to be injected from the cup space portion 25a to the main space portion 25b. Therefore, the minimum gap d1 is preferably, for example, 0.3 mm or more, and more preferably 0.5 mm or more.

[0040] As shown in FIGS. 3 and 4, the injection head 4 is formed with a plurality of through holes 30 extending in the supply direction. Each of the through holes 30 has one end 30a opening on the convex surface 20 and the other end 30b communicating with the molding space 25 between the neck portion 16 and the core 3. In other words, the other end 30b opens at the stepped surface 21 of the tip portion 15. Such through holes 30 form a flow path forming portion 32 of the molding space 25 for injecting the uncured material G from the cup space portion 25a to the main space portion 25b (shown in FIG. 5). The flow path forming portion 32 forms a small diameter portion 5d of the bladder B (shown in FIG. 2) continuous with the main portion B3.

[0041] The through holes 30 are formed, for example, at equal intervals around the injection holes 4a. Thereby, the above-described action is more effectively exerted. Considering the smooth injection of the uncured material G, it is desirable to provide 16 to 32 through holes 30.

[0042] As shown in FIG. 6, the portion having the minimum diameter (inner diameter) d2 of the through hole 30 is formed, for example, at the planned cutting position K (shown in FIG. 5). Such a minimum diameter d2 of the through hole 30 is preferably 1.5 to 5.0 mm. Since the minimum diameter d2 is 5.0 mm or less, the ease of cutting between the cup portion B2 and the main portion B3 is maintained. Since the minimum diameter d2 is 1.5 mm or more, the flow of the uncured material G becomes smooth. From such a viewpoint, the minimum diameter d2 is more preferably 2.0 mm or more, still more preferably 3.0 mm or more, further preferably 4.0 mm or less, and still more preferably 3.5 mm or less.

[0043] The through hole 30 has, for example, a circular cross section. The through hole 30 has an inner diameter gradually decreasing from the convex surface 20 toward the stepped surface 21 (shown in FIG. 4). In other words, the minimum diameter d2 is formed at the stepped surface 21. Such through holes 30 make it even easier to cut between the cup portion B2 and the main portion B3.

[0044] It is desirable that the sum (A1 + A2) of the opening area A1 at the minimum gap d1 of the thin-wall forming portion 27 and the total opening area A2 at the minimum diameter d2 of all the through-holes 30 is not less than the opening area A3 at the minimum diameter d4 of the injection flow path 19. Thereby, it is possible to suppress damage (for example, rubber burning) caused by the uncured material G staying in the cup space portion 25a. From such a viewpoint, it is more desirable that the sum (A1 + A2) is not less than 1.5 times the opening area A3.

[0045] Next, a method for manufacturing the bladder B using such an apparatus 1 will be described. FIG. 7 is a flowchart of the manufacturing method of the present embodiment. As shown in FIG. 7, the manufacturing method of the present embodiment includes a step S1 of forming the bladder B using the apparatus 1, a step S2 of opening the outer mold 2 and removing the bladder B from the core 3, and a step S3 of cutting the cup portion B2 at the thin-wall portion 5c of the removed bladder B. Among these, for the forming step S1 and the removing step S2, well-known methods are adopted, and thus detailed descriptions thereof are omitted. In the removing step S2 of the present embodiment, as shown in FIG. 8, in the open state where the first mold 6 and the second mold 7 are opened, the bladder B is held on the stepped surface 21 of the tip portion 15 of the injection head 4.

[0046] The thin-wall forming portion 27 of the molding space 25 is formed at a planned cutting position K (shown in FIG. 5) for cutting the cup portion B2. Further, the flow path forming portion 32 is also formed at the planned cutting position K. Thereby, in the cutting step S3 of the present embodiment, it can be performed without using a cutting tool. In the cutting step S3, for example, the thin-wall portion 5c and the small-diameter portion 5d are cut by the hand of an operator, and the cup portion B2 and the main portion B3 are separated. Thus, the bladder B manufactured by the apparatus 1 of the present embodiment can easily cut the cup portion B2.

[0047] As described above, the particularly preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the illustrated embodiments and can be implemented in various forms.

Description of Reference Numerals

[0048] 1 Bladder manufacturing apparatus 2 Outer Mold 3 Core 4 Injection Head 4a Injection Hole 14 Convex Surface 27 Thin-Wall Forming Portion 13 Molding Space B Bladder B2 Cup Portion Bc Axis Center Line G Uncured Material d1 Minimum Gap

Claims

1. A bladder manufacturing apparatus for manufacturing a bladder, comprising: an outer mold that can be opened and closed vertically to form the outer surface of the bladder; a core disposed inside the outer mold for forming the inner surface of the bladder; an injection head attached to the outer mold and having an injection hole for injecting an uncured material into the molding space between the outer mold and the core; the injection head includes a convex surface for forming a concave cup portion located on the axial center line of the bladder between the injection head and the core; in a cross section including the axial center line of the bladder in the closed state of the outer mold, the space between the convex surface and the core includes a thin-wall forming portion with a minimum gap of 5 mm or less; the injection head includes a tip portion forming the convex surface and a neck portion located upstream of the tip portion in the supply direction of the uncured material; the neck portion is formed with a smaller diameter than the tip portion so as to be continuous with the tip portion via a step; the injection head is formed with a plurality of through holes extending in the supply direction of the uncured material; each of the through holes has one end opening at the convex surface and the other end communicating with the molding space between the neck portion and the core; A bladder manufacturing apparatus.

2. The bladder manufacturing apparatus according to claim 1, wherein the thin-wall forming portion is formed at a position where the cup portion of the formed bladder is to be cut.

3. The convex surface of the injection head has an outer diameter that gradually increases toward the upstream side in the supply direction of the uncured material from the injection hole; The bladder manufacturing apparatus according to claim 1 or 2, wherein the thin-wall forming portion is formed at a position where the outer diameter of the convex surface is maximum.

4. The bladder manufacturing apparatus according to any one of claims 1 to 3, wherein the through holes are formed at equal intervals around the injection hole.

5. The bladder manufacturing apparatus according to any one of claims 1 to 4, wherein the minimum diameter of the through holes is 1.5 to 5.0 mm.

6. The bladder manufacturing apparatus according to any one of claims 1 to 5, wherein the injection head is detachable from the outer mold.

7. A method for manufacturing a bladder using the bladder manufacturing apparatus according to any one of claims 1 to 6, comprising: a step of forming a bladder using the bladder manufacturing apparatus; a step of opening the outer mold and removing the bladder from the core. A step of cutting the cup portion at the thin-walled portion formed in the thin-walled portion forming portion of the removed bladder, and the like. A method for manufacturing a bladder.

8. The method for manufacturing a bladder according to claim 7, wherein the cutting step is performed without using a cutting tool.

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