JP4279966B2 - Venthole opening / closing valve and molding die having the same - Google Patents

Description

【００３４】
以上、本発明の特に好ましい実施形態について詳述したが、本発明は図示の実施形態に限定されることなく、例えば成形金型として、タイヤ赤道面と平行な割面を有する上下のモールドのみからなる所謂２ピースモールドタイプの金型として構成することもできるなど種々の態様に変形して実施しうる。又ベントホール開閉弁は、タイヤ以外の他のゴム製品の成形金型にも好適に採用できる。
【００３５】
【発明の効果】
本願発明のベントホール開閉弁は、叙上の如く構成しているため、弁座と弁体との間でのゴム噛込みの発生、および微粒子体のベントホール内への浸入や目づまり等の発生を効果的に抑制でき、開閉動作の安定性や信頼性を高めるとともに、メンテナンスの頻度を著減しうる。
【図面の簡単な説明】
【図１】本発明の一実施例の成形金型の断面図である。
【図２】それに取付くベントホール開閉弁の一例を示す断面図である。
【図３】ベントホール開閉弁の作用を説明する開放状態の断面図である。
【図４】ベントホール開閉弁の作用を説明する閉止状態の断面図である。
【図５】従来の開閉弁の一例を示す断面図である。
【図６】従来の開閉弁の他の例を示す断面図である。
【符号の説明】
４ 取付け孔
５ ベントホール開閉弁
６ ベント基体
６Ｓ 内端面
７ 導孔
７Ａ 主導孔部
９ 弁体
１０ バネ体
１１ ベントホール
１２ 弁座
１２Ｅ 弁座外周縁
１３ 弁孔
１４ 弁座面
１５ ゴム溜め部
１５Ｓ 傾斜面
Ｓ 金型内面
Ｒ 成形室[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vent hole opening / closing valve that can be suitably used for vulcanization molding of rubber products such as tires, enhances the reliability of the opening / closing operation, and facilitates maintenance of the molding die, and a molding die including the vent hole opening / closing valve. .
[0002]
[Prior art]
When a tire is vulcanized using a molding die, the air trapped between the inner surface of the die and the tire raw cover (sometimes referred to as residual air) is efficiently exhausted in order to form the tire shape accurately. Therefore, a large number of vent holes are provided on the inner surface of the molding die.
[0003]
The vent hole of this tire molding die is usually a small-diameter hole that penetrates the die body. However, while the vent hole exhausts residual air, the rubber also flows into the vent hole, so that a large number of spews (columnar beams) are formed in a bristle shape on the molded tire surface. . In addition, spew has been conventionally cut short by a trimming device using a cutter in order to significantly impair the appearance of the tire. However, this trimming operation requires a great deal of labor and time, and the equipment cost of the trimming device. In addition, the maintenance cost and the like are also required, which causes an increase in manufacturing cost.
[0004]
[Problems to be solved by the invention]
Therefore, in recent years, an on-off valve that exhausts residual air but can prevent rubber from flowing into the vent hole and eliminates spew cutting work has been proposed. For example, FIG. An on-off valve having the structure shown in the drawing and an on-off valve having the structure shown in FIG. 6 as disclosed in US Pat. No. 4,759,701 are widely known.
[0005]
The former is provided with a cone-shaped valve seat b facing the molding chamber a. Normally, the valve body c protrudes toward the molding chamber a to open the valve hole b1, and exhausts residual air. Further, when the tire raw cover is brought into close contact with the inner surface of the mold by exhaust, the tire raw cover itself pushes up the valve body c, so that the valve hole b1 is automatically closed and the rubber flows into the vent hole d. Be blocked.
[0006]
However, in this structure, when the valve hole b1 is closed, the rubber bites in a thin film between the valve seat b and the valve body c, so that maintenance for cleaning the on-off valve is frequently required. Moreover, the inner surface of the mold is periodically cleaned by so-called shot blasting or the like, but since the valve hole b1 is opened at this time, the cleaning fine particles (for example, a polishing material such as a plastic grid) are vented. There is a problem that it enters the hole d and induces a malfunction of the spring mechanism e.
[0007]
On the other hand, the latter includes a flat valve seat b facing rearward, and normally, the disc-shaped valve body c is pressed against the valve seat b to close the valve hole b1. The valve hole b1 is electrically connected to the molding chamber a through a small communication hole f. And at the time of shaping | molding, the residual air is exhausted by pushing up the said valve body c by the internal pressure rise, and opening the valve hole b1.
[0008]
However, in this structure, since the volume in the communication hole f is very small, the timing of closing the valve hole b1 becomes severe, and the closing timing is delayed and the rubber engagement between the valve seat b and the valve element c is delayed. It tends to occur. In addition, since the valve body c has a disk shape, it is difficult to move in parallel up and down, and therefore the valve operation tends to be unstable, such as variations in the opening and closing timing, and it tends to further promote the occurrence of the rubber biting. . In addition, this structure prevents the fine particles from entering the vent hole d during shot blasting because the valve hole b1 is normally closed, but the fine particles stay in the communication hole f and become clogged. There is a problem that it is easy to cause. Therefore, the maintenance frequency for removing the rubber bites and the clogging of the fine particles is still high.
[0009]
Therefore, the present invention can effectively suppress the occurrence of rubber biting between the valve seat and the valve body and the entry of fine particles into the vent hole, clogging, etc. The purpose of the present invention is to provide a vent hole opening / closing valve that can improve reliability and reduce the frequency of maintenance, and a molding die including the vent hole opening / closing valve.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the first invention of the present application is a vent hole opening / closing valve for forming a vent hole in a molding chamber surrounded by a mold inner surface,
In a mounting hole provided in the mold and communicating with the molding chamber from the outside of the mold, a valve hole is provided at a position where the inner end surface can be fitted with the inner surface of the mold aligned and communicated with the inside and outside and away from the inner end surface. A tubular vent base having a guide hole with an enclosed valve seat facing backwards;
A spherical valve body that is disposed in the guide hole and can open and close the guide hole by contacting and separating from the valve seat;
The spring body is arranged in the guide hole and urges the valve body toward the valve seat at the inner end and the rear end is supported by the vent base,
The valve seat has a valve seat surface inclined rearward from the valve hole toward the outer periphery of the valve seat, and the guide hole has a maximum diameter at the inner end surface and is reduced in diameter toward the valve hole. It is characterized in that a reservoir is provided.
[0011]
The vent base has an outer diameter D0 of 1.5 to 4.0 mm, and the guide hole has an inner diameter Dd of the leading hole portion behind the valve seat surface of 0.4 to 0 of the outer diameter D0 of the vent base. It is preferable that the maximum diameter Db of the inner end face of the guide hole is 0.6 to 2.0 mm, and the inner diameter Da of the valve hole is 0.5 to 0.8 times the maximum diameter Db. .
[0012]
The rubber reservoir portion has a length H of 0.5 to 5.0 mm, and an angle θ1 with respect to the guide hole center line of the inclined surface of the rubber reservoir portion is 5 ° to 70 °. The guide hole center of the valve seat surface The angle θ2 with respect to the line is preferably 15 ° to 75 °.
[0013]
According to a second aspect of the present invention, there is provided a molding die comprising the vent hole opening / closing valve according to the first aspect, wherein the mounting hole is formed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the vent hole opening / closing valve according to the first invention of the present application will be described with reference to the drawings together with an embodiment of the molding die according to the second invention. FIG. 1 illustrates a case where the molding die 1 of the present application is a tire die for vulcanizing a tire.
[0015]
In the drawing, a molding die 1 is a so-called split mold type die that can be divided into a plurality of pieces in the circumferential direction in this example, and is divided into upper and lower side molds 2U and 2L for forming sidewalls in the circumferential direction. A molding chamber R surrounded by the mold inner surface S is formed by contacting the split surfaces of the upper and lower side molds 2U, 2L and the segment 3 with a plurality of segments 3 for forming a tread.
[0016]
The molding chamber R has a contour shape substantially equal to the tire contour shape, and is formed of a tread molding surface portion S1, a sidewall molding surface portion S2, and a bead molding surface portion S3.
[0017]
The molding die 1 is formed with mounting holes 4 that lead from the outside of the mold to the molding chamber R, and vent hole opening / closing valves 5 (hereinafter referred to as opening / closing valves 5) are mounted in the mounting holes 4 respectively. It is done. The attachment hole 4 is a straight hole formed substantially at right angles to the mold inner surface S, and is formed so as to open at the mold inner surface S including at least the tread molding surface portion S1.
[0018]
Next, as shown in FIG. 2, the on-off valve 5 is arranged in a tubular vent base 6 fitted in the mounting hole 4 and a guide hole 7 which is open at both ends, which is the center hole. It comprises a valve body 9 that opens and closes and a spring body 10 that urges the valve body 9 to close.
[0019]
The vent base 6 is fixed to be substantially flush with its inner end surface 6S aligned with the inner surface S of the mold, and thus the guide hole 7 opens at the inner surface S of the mold and is attached to the rear thereof. A vent hole 11 is formed in cooperation with the hole 4 so that the residual air in the molding chamber R can be exhausted to the outside of the mold.
[0020]
The guide hole 7 is provided with a valve seat 12 facing rearward at a position away from the inner end face 6S. The valve seat 12 is directed from the valve hole 13 having the smallest diameter toward the valve seat outer peripheral edge 12E. It has a cone-shaped valve seat surface 14 which is inclined rearward.
[0021]
In addition, a leading hole portion 7A that forms the main body of the guide hole 7 is connected to the rear side of the valve seat surface 14, and the maximum diameter of the inner end surface 6S is provided on the front side (inward side) of the valve seat surface 14. None A cone-shaped rubber reservoir 15 that is reduced in diameter toward the valve hole 13 is connected. In this example, the length H of the rubber reservoir 15, that is, the distance from the mold inner surface S to the valve hole 13, is in the range of 0.5 to 5.0 mm, and the inclination that forms the rubber reservoir 15. The surface 15S is inclined at an angle θ1 of 5 ° to 70 ° with respect to the guide hole center line.
[0022]
Next, the valve body 9 has a spherical shape, and its diameter DA is naturally smaller than the inner diameter Dd of the main hole portion 7A and larger than the inner diameter Da of the valve hole 13. As a result, the valve body 9 can smoothly move back and forth within the main hole 7A and can be seated in a stable posture with respect to the valve seat surface 14, thus ensuring a stable valve operation with uniform opening and closing timing. Is done. For stable seating, in this example, the angle θ2 of the valve seat surface 14 with respect to the guide hole center line is set to 15 ° to 75 °.
[0023]
In the closed state, the valve body 9 preferably has an inner end that does not protrude from the inner end face 6S in terms of tire appearance.
[0024]
The spring body 10 is a coil spring disposed in the main hole portion 7A. In this example, the spring body 10 urges the valve body 9 toward the valve seat 12 at the inner end thereof, and the rear end thereof is the vent base body 6. Supported by In this example, a narrowed portion 16 in which the inner diameter of the guide hole 7 is partially reduced by caulking the vent base 6 is integrally provided near the rear end of the vent base 6. The rear end of the spring body 10 is locked.
[0025]
However, in the on-off valve 5, the valve body 9 is urged by the spring body 10, and the valve hole 13 is normally closed. Further, at the time of molding, the tire raw cover T is pressed along the mold by the molding pressure, and immediately before the tire inner cover S is in close contact with the mold inner surface S, as shown in FIG. The residual air confined in is pushed up the valve body 9 against the urging force of the spring body 10 by increasing the air pressure, and exhausts the residual air to the outside.
[0026]
Further, as shown in FIG. 4, when the tire raw cover T comes into close contact with the inner surface S of the mold, the residual air is exhausted, so that the air pressure is lowered and the urging force by the spring body 10 is won, thereby the valve body. 9 is pushed down and the valve hole 13 is closed. In this state, the rubber is filled to some extent in the rubber reservoir 15 to form the spew 17, which is not longer than the length H, so that only a thin and short spew that does not require trimming remains in appearance. As a result, it is possible to obtain a product that is acceptable as a product.
[0027]
Further, since the valve body 9 has a spherical shape, the valve body 9 can be seated in a stable posture on the cone-shaped valve seat surface 14 and can be opened and closed at a constant timing with little error. On the other hand, in order to avoid both molding defects such as bear and rubber biting in the valve seat 12, the valve body 9 is closed after the rubber starts to enter the rubber reservoir 15 until it is completely filled. However, since the volume of the rubber reservoir 15 is relatively large, a time margin is created in the closing timing. Accordingly, it is possible to more reliably prevent rubber biting and improve the reliability of the opening / closing operation.
[0028]
Further, even when the mold 1 is cleaned by shot blasting or the like, the valve hole 13 is closed, so that the cleaning fine particles can be prevented from entering the inside. In addition, since the rubber reservoir 15 is formed with the inclined surface 15S having the angle θ1, the fine particle body sprayed on the rubber reservoir 15 can be easily dropped along the inclined surface 15S and can prevent clogging due to the retention. . Even if fine particles adhere to the inclined surface 15S due to the presence of an oil component or the like, it can be easily removed by air blow or the like.
[0029]
Here, in the on-off valve 5, from the viewpoints of exhaustability and strength, the outer diameter D0 of the vent base 6 is 1.5 to 4.0 mm, and the inner diameter Dd of the main hole portion 7A is the outer diameter D0. It is good to be 0.4 to 0.8 times.
[0030]
The maximum diameter Db of the guide hole 7 is preferably 0.6 to 2.0 mm, and the inner diameter Da of the valve hole 13 is preferably 0.5 to 0.8 times the maximum diameter Db. This is because if the maximum diameter Db is less than 0.6 mm, it is difficult to secure the volume of the rubber reservoir 15 and the fine particles tend to stay in the rubber reservoir 15. This is because it is too thick, resulting in a decrease in appearance and a decrease in tire ground contact. If the inner diameter Da is less than 0.5 × Db, it is difficult to ensure sufficient exhaustability. Conversely, if the inner diameter Da exceeds 0.8 × Db, the spew 17 becomes too thick, and the angle θ1 of the inclined surface 15S decreases, resulting in fine particles. The tendency of body retention and its removal become difficult. For the same reason, the angle θ1 is preferably 15 ° to 75 °.
[0031]
The length H of the rubber reservoir 15 is preferably 0.5 to 5.0 mm. When the length H is less than 0.5 mm, there is no time margin for the closing timing, and the rubber tends to get caught. Further, although the spew 17 is not longer than the length H, if the length H exceeds 5 mm, the spew 17 also tends to become longer, resulting in a deterioration in appearance.
[0032]
Table 1 discloses a preferred example of the dimensions of the on-off valve 5. In the table, L is the full length of the on-off valve 1 (shown in FIG. 2), and is generally 10 to 40 mm.
[0033]
[Table 1]

[0034]
As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, For example, as a molding die, it is only from the upper and lower molds which have a split surface parallel to a tire equator surface. The present invention can be carried out with various modifications such as a so-called two-piece mold. In addition, the vent hole opening / closing valve can be suitably employed in a molding die for rubber products other than tires.
[0035]
【The invention's effect】
Since the vent hole opening / closing valve of the present invention is configured as described above, the occurrence of rubber biting between the valve seat and the valve body, the entry of fine particles into the vent hole, clogging, etc. Generation can be effectively suppressed, the stability and reliability of the opening / closing operation can be improved, and the frequency of maintenance can be significantly reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a molding die according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an example of a vent hole opening / closing valve attached thereto.
FIG. 3 is a cross-sectional view in an open state for explaining the operation of the vent hole on-off valve.
FIG. 4 is a cross-sectional view in the closed state for explaining the operation of the vent hole on-off valve.
FIG. 5 is a cross-sectional view showing an example of a conventional on-off valve.
FIG. 6 is a cross-sectional view showing another example of a conventional on-off valve.
[Explanation of symbols]
4 Mounting hole 5 Vent hole opening / closing valve 6 Vent base 6S Inner end surface 7 Conducting hole 7A Leading hole 9 Valve body 10 Spring body 11 Vent hole 12 Valve seat 12E Valve seat outer peripheral edge 13 Valve hole 14 Valve seat surface 15 Rubber reservoir 15S Inclined surface S Inner surface R Molding chamber

Claims (4)

A vent hole opening / closing valve for forming a vent hole in the molding chamber surrounded by the inner surface of the mold,
In a mounting hole provided in the mold and communicating with the molding chamber from the outside of the mold, a valve hole is provided at a position where the inner end surface can be fitted with the inner surface of the mold aligned and communicated with the inside and outside and away from the inner end surface. A tubular vent base having a guide hole with an enclosed valve seat facing backwards;
A spherical valve body that is disposed in the guide hole and can open and close the guide hole by contacting and separating from the valve seat;
The spring body is arranged in the guide hole and urges the valve body toward the valve seat at the inner end and the rear end is supported by the vent base,
The valve seat has a valve seat surface inclined rearward from the valve hole toward the outer periphery of the valve seat, and the guide hole has a maximum diameter at the inner end surface and is reduced in diameter toward the valve hole. A vent hole opening / closing valve provided with a reservoir. The vent base has an outer diameter D0 of 1.5 to 4.0 mm, and the guide hole has an inner diameter Dd of a leading hole portion behind the valve seat surface, which is 0.4 to 0.00 mm of the outer diameter D0 of the vent base. The maximum diameter Db of the inner end surface of the guide hole is 0.6 to 2.0 mm, and the inner diameter Da of the valve hole is 0.5 to 0.8 times the maximum diameter Db. The vent hole opening / closing valve according to claim 1. The rubber reservoir portion has a length H of 0.5 to 5.0 mm, and an angle θ1 with respect to the guide hole center line of the inclined surface of the rubber reservoir portion is 5 ° to 70 °. The guide hole center line of the valve seat surface The vent hole opening / closing valve according to claim 1 or 2, wherein an angle θ2 with respect to the angle is 15 ° to 75 °. A molding die comprising the vent hole opening / closing valve according to any one of claims 1 to 3, wherein the mounting hole is formed.

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