Bladder vulcanization molding mold

Abstract

The present invention addresses the problem of providing a bladder vulcanization molding die capable of supporting a core to which high pressure is applied, and capable of uniformly and quickly raising the temperature of each part of a bladder to the vulcanization temperature without unevenness, thereby shortening the vulcanization time uniformly as a whole. [Solution] This bladder vulcanization molding mold comprises a pair of upper and lower molds 10, 20 and a core 30, each equipped with steam chambers 10a, 20a, 30a for circulating steam for heating the mold within its wall thickness, and the lower mold 20 is equipped with a core support seat 22 in its lower half for supporting the core 30 from below, and by pressing injection molding rubber through the upper mold 10, a bladder is vulcanized and molded in the molding space S between the inner surfaces of the pair of upper and lower molds and the outer surface of the core, and the lower mold 20 is equipped with an extended steam hole 20b extending from the steam chamber 20a toward the lower end of the molding space S.

Description

[Technical Field]

[0001] This invention relates to a bladder vulcanization molding mold. [Background technology]

[0002] A bladder is a rubber-like member used to vulcanize a green tire (raw tire) inserted into a mold during tire vulcanization molding. Steam is supplied to the green tire placed in the mold through the bladder to simultaneously apply pressure and heat, thereby molding and vulcanizing the green tire. An example of a mold used to mold such green tires is described in Patent Document 1 below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-314398 Summary of the Invention [Problem to be solved by the invention]

[0004] Among molds for vulcanizing bladders, molds that utilize injection molding, in particular, generally consist of a pair of upper and lower dies and a core inserted therein, with the rubber for injection molding being pressed into the upper die, and the bladder being vulcanized and molded in the molding space between the inner surfaces of the upper and lower dies and the outer surface of the core. In this case, to mold a bladder that is particularly large and thin, it is necessary to inject the rubber into the mold at a fairly high pressure, which results in considerable pressure being applied to the core placed in the mold, and so the core has traditionally been supported from below by the lower die. Due to these circumstances, there is a problem that the lower mold, which is subjected to high pressure, is prone to damage and deformation, and in order to solve this problem, the part of the lower mold that is subjected to high pressure has been made thicker or replaced with a high-strength material. However, if the lower mold is made thicker than the upper mold or if parts of it are replaced with high-strength materials, the rate at which the temperature rises to the vulcanization temperature during vulcanization molding of the bladder becomes slower around the molding space of the lower mold, resulting in uneven vulcanization of the rubber and longer time to complete vulcanization depending on the parts that rise slowly. Patent Document 1 discloses a method for manufacturing a tire vulcanization bladder and a mold for use therewith, which can shorten the vulcanization time and improve the physical properties after vulcanization. According to this mold, first heating sections (6) and (7) are installed in the upper mold (1), first heating sections (6) and (7) are installed in the lower mold (2), and first heating section (8) is installed in the core (3). When vulcanizing the tire vulcanization bladder (X), the temperature of the first heating section (7) closest to the thick section (X2) is set higher than the temperatures of the remaining first heating sections (6) and (8). This configuration accelerates the vulcanization of the thick section (X2) of the tire vulcanization bladder, thereby shortening the vulcanization time in the thick section (X2) and enabling the overall vulcanization time to be shortened. Furthermore, since the vulcanization of the thick portion (X2) of the tire vulcanization bladder can be accelerated, the thick portion and the thin portion can be vulcanized to the same degree, which has the effect of making the physical properties of the bladder after vulcanization more uniform than before. However, the invention of Patent Document 1 has a drawback in that the temperature of the steam supplied to the first heating section (7) itself needs to be higher than the temperature of the steam supplied to the other first heating sections (6) and (8), and therefore two types of steam need to be prepared.

[0005] Therefore, the present invention aims to solve the above-mentioned conventional problems that arise when bladders are vulcanized by injection molding, and to provide a bladder vulcanization mold that can adequately support a core that is subjected to high pressure, and that can quickly and uniformly raise the temperature of each part of the bladder to the vulcanization temperature without unevenness, thereby shortening the vulcanization time overall. [Means for solving the problem]

[0006] In order to solve the above problems, the bladder vulcanization mold of the present invention comprises a pair of upper and lower dies 10, 20 for molding the outer surface shape of the bladder, and a core 30 disposed within the pair of upper and lower dies 10, 20 for molding the inner surface shape of the bladder. The upper die 10, the lower die 20, and the core 30 are each provided with steam chambers 10a, 20a, 30a for circulating steam for heating the mold within their respective walls. The lower die 20 is provided with a core receiving seat 22 in its lower half for supporting the core 30 from below. The bladder vulcanization mold is designed so that a bladder is vulcanized and molded in a molding space S between the inner surfaces of the pair of upper and lower dies 10, 20 and the outer surface of the core 30 by press-fitting injection molding rubber through the upper die 10. The lower mold 20 is first characterized in that it is provided with an extended steam hole 20b extending from the steam chamber 20a toward the lower end of the molding space S. In addition to the first feature, the bladder vulcanization molding mold of the present invention has a second feature in that the extended steam holes 20b are arranged at equal intervals in the annular steam chamber 20a provided in the lower mold 20. In addition to the first and second features, the bladder vulcanization molding mold of the present invention has a third feature in that the upper half of the lower mold 20 is configured as the molding section 21 and the lower half is configured as the core receiving seat 22, and the molding section 21 defines a molding space S between it and the core 30 and also defines a steam chamber 20a within the wall thickness. In addition to the third feature, the bladder vulcanization molding mold of the present invention has a fourth feature in that the core receiving seat 22 provided in the lower half of the lower mold 20 is configured as a separate member from the molding section 21 that constitutes the upper half of the lower mold 20 and is connected to it in an exchangeable manner. In addition to the fourth feature, the bladder vulcanization molding mold of the present invention has a fifth feature in that the core receiving seat portion 22 of the lower mold 20 is made of a higher strength material than the molding portion 21. [Effects of the Invention]

[0007] The mold for vulcanizing a bladder according to claim 1 includes a pair of upper and lower molds 10, 20 for molding the outer surface shape of the bladder, and a core 30 disposed within the pair of upper and lower molds 10, 20 for molding the inner surface shape of the bladder. The upper mold 10, the lower mold 20, and the core 30 of the pair of upper and lower molds are each equipped with steam chambers 10a, 20a, and 30a for circulating steam for heating the mold within their respective walls. The lower mold 20 is equipped in its lower half with a core support seat 22 for supporting the core 30 from below. A bladder can be obtained by press-fitting injection molding rubber through the upper mold 10 and vulcanizing it in the molding space S between the inner surfaces of the pair of upper and lower molds 10, 20 and the outer surface of the core 30. According to the bladder vulcanization mold of claim 1, an extended steam hole 20b is provided that extends from the steam chamber 20a of the lower mold 20 toward the lower end of the molding space S. Therefore, when the mold is heated, part of the steam circulating in the steam chamber 20a of the lower mold 20 enters the extended steam hole 20b and directly heats the lower mold 20 around the extended steam hole 20b, eliminating the tendency for the temperature of the lower mold 20 to rise slowly near the lower end of the molding space S. Therefore, the temperature of the entire rubber pressed into the molding space S can be raised uniformly and quickly, making it possible to efficiently obtain a bladder that is in a good cross-linked state with no unevenness overall.

[0008] Furthermore, with the bladder vulcanization mold described in claim 2, in addition to the advantageous effects of the configuration described in claim 1, the extended steam holes 20b are arranged at equal intervals in the annular steam chamber 20a of the lower mold 20. Therefore, when the mold is heated, steam also enters the extended steam holes 20b arranged at equal intervals in the annular steam chamber 20a, directly heating the areas around each extended steam hole 20b. This eliminates the delay in temperature rise of the lower mold 20 near the bottom end of the molding space S over the entire annular area. This results in a more uniform temperature rise of the rubber in the molding space S, enabling the bladder to be vulcanized at a more uniform temperature and for a more uniform period of time, without unevenness.

[0009] Furthermore, according to the bladder vulcanization molding mold described in claim 3, in addition to the advantageous effects of the configuration described in claim 1 or 2, the upper half of the lower mold 20 is configured as a political and economic section 21 and the lower half is configured as a core receiving seat section 22, and the molding section 21 forms a molding space S between the core 30 and the molding section 21, and also forms a steam chamber 20a within the wall thickness. Therefore, the lower mold 20 can perform the function of reliably obtaining a molding space S between the upper mold 10 and the core 30 through the molding portion 21 formed in its upper half, and can perform the function of reliably supporting the core 30 through the core receiving seat portion 22 formed in its lower half.

[0010] Furthermore, according to the bladder vulcanization molding mold described in claim 4, in addition to the advantageous effects of the configuration described in claim 3, the core receiving seat portion 22 provided in the lower half of the lower mold 20 is configured as a separate member from the molding portion 21 constituting the upper half of the lower mold 20 and is joined together in an exchangeable manner. Therefore, the molding portion 21 in the upper half of the lower mold 20 and the core receiving seat 22 in the lower half can each be made of a material suited to its function. By making the two separate components, there is an advantage that if the easily breakable core receiving seat 22 is damaged, only one of them can be replaced.

[0011] Furthermore, according to the bladder vulcanization molding mold described in claim 5, in addition to the advantageous effects of the configuration described in claim 4, the core receiving seat portion 22 of the lower mold 20 is made of a higher strength material than the molding portion 21, which increases the durability of the core receiving seat portion 22 against breakage, deformation, and wear, thereby reducing the number of times the core receiving seat portion 22 needs to be replaced. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an overall cross-sectional view of a bladder vulcanization molding mold according to an embodiment of the present invention. [Figure 2] 1 is an exploded cross-sectional view of a bladder vulcanization molding mold according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] A bladder is a rubber balloon-like component used in the vulcanization molding of tires. A green tire (raw tire) before tire molding is inserted into the inside of a tire molding mold, and high-temperature steam is supplied from the inside of the bladder to expand it and press it against the inside of the green tire. This molds the inside of the tire and vulcanizes the green tire.

[0014] Referring to the drawings, the bladder vulcanization mold according to the embodiment of the present invention comprises a pair of upper and lower dies 10 and 20 that form the outer surface shape of the bladder, and a core 30 that is placed within the pair of upper and lower dies 10 and 20 and forms the inner surface shape of the bladder. The upper die 10 is provided with a rubber press-fitting hole 11 into which rubber for injection molding is press-fitted. The lower die 20 also plays a role in supporting the core 30.

[0015] The upper mold 10 and the lower mold 20 are provided with steam chambers 10a and 20a, respectively. High-temperature steam of, for example, about 170° C. to 200° C. is introduced into the steam chambers 10a and 20a, and the upper mold 10 and the lower mold 20 are heated. The core 30 is also provided with a steam chamber 30a, into which high-temperature steam is introduced to heat the core 30.

[0016] The rubber press-in hole 11 of the upper mold 10 is configured so that pre-vulcanized rubber, which is made into a soft viscous material by mixing raw materials such as synthetic rubber and carbon black, can be injected at a high pressure of 700 to 1000 kg / cm2.

[0017] The lower mold 20 comprises a molding portion 21 constituting its upper half and a core receiving seat portion 22 constituting its lower half. The molding section 21 is a mold section that defines a molding space S between itself and the core 30. The molding section 21 is configured with a molding surface 21a for molding the outer shape of the bladder. The core seat 22 is a mold part that supports the core 30 and receives the injection pressure of the rubber. A molding surface that corresponds to the molding surface 21a is partially formed on the core seat 22. The molding portion 21 and the core receiving seat 22 are connected to each other by a connecting means such as a bolt (not shown) so that they can be attached and detached freely. In other words, the core receiving seat 22 can be connected to the lower mold 20 so that it can be replaced freely.

[0018] A part of the core receiving seat 22 of the lower mold 20 has a core support surface 22a. The core support surface 22a is a support surface that directly contacts a part of the core 30 from below and supports the core 30. In other words, this surface contacts from below and supports the core 30 that is pressed by the unvulcanized rubber that is pressed into the rubber press-fitting hole 11 at high pressure and attempts to retreat. In this embodiment, in addition to the surface perpendicular to the direction in which the rubber for injection molding is pressed into the core support surface 22a, a tapered receiving surface 22b is provided on part of the core support surface 22a. The tapered receiving surface 22b is formed in a state inclined with respect to the surface perpendicular to the direction in which the rubber for injection molding is pressed into the core support surface 22a, more specifically in a state inclined in a cone shape. The tapered receiving surface 22b is formed by utilizing a through hole 23 that receives a supply / discharge path connecting protrusion 32 of the core 30, which will be described later. The material of the core seat 22 can be different from that of the molding portion 21, and a high-strength material that is resistant to breakage, deformation, and wear, such as chromium molybdenum steel, can be used.

[0019] The core 30 is composed of an inner surface molding portion 31 for vulcanizing and molding the inner surface of the bladder, and an inlet / outlet path connecting protrusion 32 that forms a connection path for supplying and exhausting steam and air to the core 30. The supply / discharge path connecting protrusion 32 is provided with a steam connection path 30b and an air connection path 30c. High-temperature steam for vulcanization supplied from the outside passes through one steam connection path 30b to the steam chamber 30a and is then discharged from the steam chamber 30a to the outside through the other steam connection path 30b. Air is also sent through the air connection path 30c, and is sprayed from the core 30 side onto the molded bladder to remove it from the mold.

[0020] The core 30 has a direct contact portion 33 at the bottom of its inner surface molding portion 31 that comes into direct contact with the lower die 20. The direct contact portion 33 is a portion that comes into direct contact with the core support surface 22a of the core receiving seat 22 of the lower die 20. The direct contact portion 33 is provided with a tapered protrusion 33a in addition to a portion that contacts the surface of the core support surface 22a that is perpendicular to the direction in which the injection molding rubber is pressed in. Tapered protrusion 33a is configured as a cylindrical protrusion whose outer surface is tapered toward the tip, and this outer surface is adapted to fit exactly into tapered receiving surface 22b of core receiving seat 22. In addition, the cylindrical hole of tapered protrusion 33a is adapted to fit externally onto supply / discharge path connecting protrusion 32 of core 30. By providing tapered protrusion 33a on direct contact portion 33 and tapered receiving surface 22b on core receiving seat 22, the area of ​​the contact surface between lower die 20 and core 30 can be made sufficiently large, reducing or dispersing the pressure per unit area acting between lower die 20 and core 30 and reducing damage or deformation to both. Furthermore, tapered receiving surface 22b of core receiving seat 22 allows tapered protrusion 33a of direct contact portion 33 of core 30 to fit into each other, thereby enabling core 30 to be stably received and supported, and allowing core 30 to be supported in an even more stable state even against the high pressure caused by injecting rubber for injection molding. The tapered receiving surface 22 b and the tapered protrusion 33 a are configured by effectively utilizing the supply / discharge path connecting protrusion 32 provided on the core 30 and the through hole 23 provided in the lower mold 20 .

[0021] The material of the core 30 may be structural rolled steel, carbon steel, or carbon steel casting such as SC450. The direct contact portion 33 of the core 30 can be made of the same material as the core seat 22, such as chrome molybdenum steel, which has high hardness and strength and is less likely to deform under pressure.

[0022] In the bladder vulcanization molding mold of the present invention configured as described above, an extended steam hole 20b is provided in the steam chamber 20a provided in the lower mold 20, extending from the steam chamber 20a toward the lower end of the molding space S. Specifically, the extended steam holes 20b are provided in a circular steam chamber 20a provided in the lower mold 20, and are arranged in a circular pattern at regular intervals. The extended steam hole 20b is configured to prevent the rate of temperature rise of the mold (mainly the lower mold 20) near the lower end of the molding space S from slowing down due to the influence of the core receiving seat 22 added to the lower half of the lower mold 20. By providing the extended steam hole 20b extending from the steam chamber 20a of the lower mold 20 toward the lower end of the molding space S, the steam from the steam chamber 20a also enters the extended steam hole 20b, additionally heating the area of ​​the lower mold 20 corresponding to the vicinity of the lower end of the molding space S. Therefore, the presence of the core receiving seat 22 eliminates the delay in temperature rise near the lower end of the molding space S, makes the crosslinking temperature of the entire rubber in the molding space S uniform, and achieves uniform, uniform, and good crosslinking without wasting time. Furthermore, by arranging the extended steam holes 20b in a circular pattern at regular intervals in the annular steam chamber 20a, it is possible to eliminate uneven temperature rise of the rubber around the annular area in the annular molding space S, and to efficiently obtain homogeneous, high-quality bladder rubber without uneven crosslinking.

[0023] In a bladder vulcanization mold having the above configuration, upper mold 10 is placed on the top, lower mold 20 is placed on the bottom, and core 30 is placed between them. When upper mold 10 and lower mold 20 are brought together, a molding space S is formed between the inner wall surfaces of upper mold 10 and lower mold 20 and the outer wall surface of core 30. When injection molding rubber is pressed into molding space S through rubber press-in hole 11, a bladder is molded in molding space S, and the rubber is vulcanized within molding space S by steam-heated upper mold 10, lower mold 20, and core 30. Once vulcanization is complete, upper mold 10 and lower mold 20 are separated, and the bladder is removed. [Industrial Applicability]

[0024] This invention can be used as a bladder vulcanization molding mold for diamond molding. [Explanation of symbols]

[0025] 10 Upper mold 10a Steam Room 11 Rubber press-fit hole 20 Lower mold 20a Steam Room 20b Extended steam hole 21 Molding section 21a Molding surface 22 Core receiving seat 22a Core support surface 22b Tapered bearing surface 23 Through hole 30 Core 30a Steam Room 30b Steam connection 30c air connection 31 Inner molding part 32 Convex part for connecting supply and exhaust channels 33 Direct contact part 33a Tapered protrusion S molding space

Claims

1. a mold for vulcanizing a bladder, comprising a pair of upper and lower dies for molding the outer surface shape of a bladder, and a core disposed within the pair of upper and lower dies for molding the inner surface shape of the bladder, wherein the upper and lower dies and the core of the pair of upper and lower dies are each provided with a steam chamber for circulating steam for heating the dies within a wall thickness thereof, and the lower die is provided with a core receiving seat in a lower half thereof for supporting the core from below, and wherein injection molding rubber is press-fitted through the upper die to vulcanize and mold a bladder in a molding space between the inner surfaces of the pair of upper and lower dies and the outer surface of the core, The lower mold is provided with an extended steam hole extending from the steam chamber toward the lower end of the molding space.

2. 2. The mold for vulcanizing and molding a bladder according to claim 1, wherein the extended steam holes are arranged at equal intervals in an annular steam chamber provided in the lower mold.

3. 3. A bladder vulcanization molding mold according to claim 1, wherein the upper half of the lower mold is configured as a molding section and the lower half is configured as a core receiving seat, and the molding section defines a molding space between the molding section and the core and a steam chamber within its wall thickness.

4. 4. The bladder vulcanization molding mold according to claim 3, wherein the core receiving seat provided in the lower half of the lower mold is formed as a separate member from the molding portion constituting the upper half of the lower mold and is connected to it in an exchangeable manner.

5. 5. The mold for vulcanizing and molding a bladder according to claim 4, wherein the core receiving seat of the lower mold is made of a material having higher strength than that of the molding portion.

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