阅读说明：本技术 轮胎硫化模具用通气套管及轮胎硫化模具 (Ventilation sleeve for tire vulcanization mold and tire vulcanization mold ) 是由 小原将明 于 2019-06-14 设计创作，主要内容包括：本发明涉及一种轮胎硫化模具用通气套管及使用了该轮胎硫化模具用通气套管的轮胎硫化模具。技术问题：防止在混合了无机配合剂的轮胎的硫化成型中,通风突出物在铝制模具的通风孔内断裂而阻塞。解决方案：一种对混合了无机配合剂的轮胎进行硫化成型的模具,模具由铝构成,埋设的通气套管由不锈钢或者含有15质量百分比以上铬的金属构成。(The present invention relates to a vent tube for a tire vulcanizing mold and a tire vulcanizing mold using the vent tube for a tire vulcanizing mold. The technical problem is as follows: the vent protrusions are prevented from being broken and blocked in the vent holes of the aluminum mold in vulcanization molding of the tire mixed with the inorganic compounding agent. The solution is as follows: a mold for vulcanization molding of a tire mixed with an inorganic compounding agent, wherein the mold is made of aluminum, and a ventilation sleeve embedded therein is made of stainless steel or a metal containing chromium in an amount of 15 mass% or more.)

1. A mold for vulcanization molding of a tire mixed with an inorganic compounding agent, characterized in that,

the mold is made of aluminum, and the embedded vent bushing is made of stainless steel or metal containing more than 15 mass% of chromium.

2. The mold according to claim 1,

the roughness (Ra) of the inner surface of the ventilation part of the ventilation sleeve is more than 0.5 and less than 5.0.

3. The mold according to claim 1 or 2,

the total length (c) of the ventilation sleeve is more than 10 times of the diameter (a) of the ventilation part.

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

the total length (c) of the ventilation cannula is 20 to 40 times the wall thickness ((b-a)/2) of the ventilation cannula.

5. The mold according to any one of claims 1 to 4,

the vent sleeve is tapered toward the outer surface of the mold.

6. The mold according to any one of claims 1 to 5,

the vent sleeve is a stepped vent sleeve having a large diameter portion.

7. The mold according to claim 6,

the actual contact surface length (e) of the vent bushing at the large diameter portion with the mold inner surface is about 2 times or more the vent bushing outer diameter (b).

8. The mold according to claim 6 or 7,

the actual contact surface length (e) of the vent bushing at the large diameter portion and the inner surface of the mold satisfies a x pi x 20 ≦ b x pi x e (ratio of the outer periphery to the inner periphery of the vent bushing).

9. The mold according to claim 5,

the vent tube is manufactured by drawing.

10. A detergent for cleaning a mold having an aluminum inner surface for vulcanization molding of a tire mixed with an inorganic compounding agent, wherein the detergent is a resin bead.

11. The detergent according to claim 10,

the detergent is composed of melamine resin or beads coated with melamine resin.

12. A method for cleaning a mold having an aluminum inner surface, which is obtained by vulcanizing a tire mixed with an inorganic compounding agent, characterized by using the detergent according to claim 10 or 11.

Technical Field

The present invention relates to a vent tube for a tire vulcanizing mold and a tire vulcanizing mold using the vent tube for a tire vulcanizing mold.

Background

In a tire vulcanizing mold used in a tire vulcanizing process, a plurality of fine vent holes called vent holes are provided in order to discharge air accumulated between an inner surface of the mold and a green tire to the outside of the mold during vulcanization molding. In this vulcanization step, the green tire is heated in the mold at a high temperature, and the green tire having low rigidity is expanded toward the inner surface of the mold by pressurization of the bladder. Therefore, when the green tire is vulcanized and molded, a part of the inflated green tire enters the vent hole. Therefore, a thread-like protrusion called a vent protrusion is formed on the surface of the tire released from the mold after vulcanization molding. The ventilation protrusions are trimmed from the surface of the tire in a subsequent process.

In recent years, for the purpose of low fuel consumption and reinforcing rubber layers, an inorganic compounding agent has been mixed in tires.

However, when a green tire mixed with an inorganic compounding agent is vulcanized by a general aluminum vulcanization mold, the vent protrusions are broken in the vent holes and clogged in the vent holes in the vulcanization process. Further, in the case of a green tire mixed with an inorganic compounding agent, vulcanization needs to be performed at a relatively low temperature, so that the curing of the green tire becomes slow, and as a result, the green tire enters the deep portion of the vent hole and breaks, and is clogged.

Further, when a vulcanizing mold made of aluminum is used for manufacturing a tire mixed with an inorganic compounding agent, there is a problem that the vulcanized rubber adheres to the inner surface of the mold and remains, and it is difficult to clean the mold completely.

If the vent protrusion is blocked in the vent hole and a part of the vulcanized rubber remains on the inner surface of the mold in this way, it is difficult to discharge air to the outside of the mold in the next tire vulcanization step, resulting in a tire molding defect. In addition, there is a problem that cleaning the inside of the mold takes time and reduces the manufacturing efficiency of the tire.

Disclosure of Invention

Technical problem to be solved

The present inventors have conducted extensive studies on the technical problems that vent protrusions are clogged in vent holes of an aluminum mold and it is difficult to clean and completely remove vulcanized rubber from the mold in vulcanization molding of a tire mixed with an inorganic compounding agent, and as a result, they have found that the problem of clogging due to breakage of vent protrusions in vent holes can be solved by using a sleeve made of stainless steel or a metal containing 15 mass% or more of chromium in the vent holes of an aluminum vulcanization mold for manufacturing a tire mixed with an inorganic compounding agent, and have completed the present invention.

Further, it was found that the interior of an aluminum mold after the vulcanization step can be cleaned with melamine resin beads to remove vulcanized rubber, and reattachment can be suppressed, and the present invention was completed.

(II) technical scheme

That is, in a first aspect, the present invention provides a mold for vulcanization molding of a tire mixed with an inorganic compounding agent, wherein at least an inner surface of the mold is made of aluminum, and the vent tube is made of stainless steel or a metal containing 15 mass% or more of chromium.

In addition, the present invention provides, in a second aspect, a detergent and a cleaning method for a vulcanization mold for a tire, which contains an inorganic compound using melamine resin beads.

(III) advantageous effects

According to the mold of the present invention, when manufacturing a tire with an inorganic compound having a low fuel consumption and a reinforced rubber layer, breakage of the vent protrusions during vulcanization can be suppressed, and the tire can be manufactured efficiently.

Further, since the remaining green tire can be easily removed from the mold after vulcanization molding, the tire can be efficiently manufactured.

Drawings

Figure 1 is a top perspective view of a vent sleeve for one embodiment of the mold of the present invention.

Figure 2 is an upper perspective view of a vent sleeve for another embodiment of the mold of the present invention.

Detailed Description

The invention provides a mold for vulcanization molding of a tire mixed with an inorganic compounding agent, characterized in that at least the inner surface of the mold is made of aluminum, and at least the inner surface of a vent part of a vent tube embedded in the mold is made of stainless steel or a metal containing 15 mass% or more of chromium.

The present invention solves the problems of breakage of ventilation protrusions and retention of a green tire in a mold, which are specifically caused when a tire mixed with an inorganic compounding agent is manufactured, by a vulcanization mold made of aluminum and a ventilation sleeve made of stainless steel or metal containing chromium in an amount of 15 mass% or more embedded in the vulcanization mold.

In the present specification, the inorganic compounding agent refers to an inorganic substance such as silica mixed for the purpose of improving the performance of the tire.

Vulcanization mould

The mold for vulcanization molding of a tire mixed with an inorganic compounding agent of the present invention is an aluminum mold generally used in a tire vulcanization step. The mold may be formed of aluminum at least on the inner surface, or the entire mold may be formed of aluminum.

Venting cannula

The vent bushing used in the mold of the present invention will be described with reference to fig. 1. In fig. 1, when the upper surface of the vent tube (1) is embedded in a mold, an inner surface continuous with the inner surface of the mold is formed. In a preferred embodiment, the vent bushing is formed in a tapered cylindrical shape so that the vent bushing can be easily embedded from the inside into the vent hole provided in the wall surface of the mold. A vent part (10) for discharging air from the inside of the mold is provided at the center of the vent sleeve. In a preferred embodiment, the inner surface side of the mold of the vent portion is formed into a tapered shape whose inner diameter decreases toward the outside of the mold in order to promote the air discharge.

In the vent tube, at least the portion of the vent tube in contact with the green tire, that is, the upper surface and the inner surface of the vent portion are made of stainless steel, and in particular, the vent tube may be made of metal containing 15 mass% or more of chromium, or the vent tube may be made of stainless steel or metal containing 15 mass% or more of chromium as a whole. By making the portion of the green tire in contact with stainless steel or a metal containing 15 mass% or more of chromium, when the vulcanized tire is removed from the mold, the vent protrusion of the cured tire which has entered the vent portion is not broken and removed together with the tire, and the problem that the vent protrusion remains in the vent portion and interferes with the next tire vulcanization step is avoided. The vent protrusion removed integrally with the tire is trimmed from the surface of the tire in a subsequent process.

The inner surface roughness (Ra) of the vent portion of the mold or vent sleeve is preferably from about 0.5 to about 5.0, more preferably from about 0.5 to about 3.0, and most preferably about 2.0. If the inner surface roughness (Ra) of the vent part exceeds 5.0, the friction between the tire and the vent protrusion when the tire is removed from the mold increases, and therefore the vent protrusion may be broken and blocked in the vent part. On the other hand, when the inner surface roughness (Ra) is less than 0.5, the vulcanized rubber is likely to adhere to the inner surface and increase the friction, and therefore, the vent protrusions may be broken and may be clogged in the vent portion.

In another embodiment, the vent bushing used in the mold of the present invention can be a stepped vent bushing having a large diameter portion (11) as shown in fig. 2. The vent sleeve of the present embodiment is supported in contact with the inner surface of the hole formed in the vulcanization mold at the outer periphery of the large diameter portion. Since the contact area with the vulcanizing mold is smaller than that of the vent sleeve of the embodiment shown in fig. 1, the resistance when the vent sleeve is pressed into the mold is small, and the vent sleeve is easy to process.

The inner diameter (a) of the ventilation portion of the ventilation sleeve is preferably 1mm to 2mm from the viewpoint of facilitating trimming of the ventilation projection. If the inner diameter of the vent part is less than 1mm, the vent protrusion is too thin to be trimmed after the vulcanization step, and if it exceeds 2mm, the time required until the vulcanization of the tire material is completed becomes long, the length of the vent protrusion to be produced becomes long, and the vent part may be broken and clogged inside the vent part when the tire is removed from the mold.

The total length (c) of the venting cannula is greater than or equal to the length of the resulting venting protrusion. In the case where the total length of the vent tube is short with respect to the length of the vent protrusion to be generated, the front end of the vent protrusion is located outside the vent tube, and at this position, the protrusion internal pressure holding is released based on the size of the inner surface of the vent tube, and as a result, the diameter of the vent protrusion is enlarged. Further, the tip of the vent protrusion protruding to the outside of the vent tube due to the slight difference in resistance of the inner surface of the vent protrusion and the internal pressure received by the bladder is deformed spirally, and when the vulcanized tire is released from the mold, the vent protrusion cannot be moved back completely along the inside of the vent tube in conjunction with the tire, and thus the vent protrusion is broken. In order to secure the strength of the air vent tube, the total length (c) of the air vent tube is preferably 40 times or less, more preferably 30 times or less, of the wall thickness ((b-a)/2) of the air vent tube. If the total length (c) of the vent bushing exceeds 40 times the wall thickness ((b-a)/2) of the vent bushing, buckling occurs when the vent bushing is driven into a hole formed in a mold.

The actual contact surface length (e) of the stepped vent sleeve with the mold is about 2 times or more, more preferably 3 times or more, the outer diameter (b) of the vent sleeve. This stabilizes the embedding direction of the vent tube, and can obtain a desired embedding angle and reduce machining errors, thereby minimizing transfer of the vent tube mark to the tire.

In the stepped vent tube, the actual contact surface length (e) satisfies an empirically obtained formula from the viewpoint of heat transfer from the vulcanization mold to the vent tube: a × pi × 20 ≦ b × pi × e (ratio of outer circumference to inner circumference of the ventilation tube). Thus, heat supply to the ventilation protrusions can be ensured, and the ventilation protrusions can be prevented from becoming long. However, if the actual contact surface length (e) is increased, the resistance when the vent bushing is pressed into the mold is also increased. The vent tube is embedded in the mold by impact or an additional pressing force on the upper surface, and if resistance during pressing increases, the upper surface deforms (only local diameter expansion near the upper surface). If the upper surface is deformed, it becomes difficult to embed the vent tube at a desired depth, and the quality of the mold is also deteriorated. Thus, the actual contact surface length (e) is preferably 40% or less of the total length (c) of the vent tube, and is preferably 15 times or less, more preferably 10 times or less of the vent tube wall thickness ((b-a)/2).

Examples of the structure satisfying these dimensional conditions include a stepped vent tube having a ratio of a to 1.2, b to 3.0, c to 25, d to 2.8, and e to 9.0.

By using the stepped vent bush satisfying the dimensional conditions, it is possible to solve two technical problems of workability to a mold and breakage of the vent protrusion, to generate a short vent protrusion, and to easily trim the vent protrusion from the tread surface of the tire after the vulcanization process.

The vent tube used in the present invention is made of stainless steel, preferably austenitic stainless steel, or a metal containing 15 mass% or more of chromium, and can be manufactured by drawing such as die forging or drawing. The vent tube produced by drawing is preferably such that the processing trace extends in the axial direction of the vent tube, and therefore resistance at the time of tire removal is small, and the adhesion to rubber is reduced as the content of chromium is increased, and breakage of vent protrusions is less likely to occur.

In another aspect, the present invention provides a detergent for a mold for vulcanization molding of a tire mixed with an inorganic compounding agent.

The present inventors have studied the problem of breakage of vent protrusions during vulcanization molding of a green tire mixed with an inorganic compounding agent, and have found that a part of vulcanized rubber remains on the inner surface of a mold even when the inside of the vulcanization molding mold is cleaned with glass beads.

The inventors of the present invention have tried various detergents to solve the above problems and found that: by using resin beads instead of glass beads, vulcanized rubber on the inner surface portion of the mold can be removed. The resin beads may be formed of a resin as a whole or may be coated with a resin on the bead surface, and preferably are formed of a melamine resin or beads coated with a melamine resin on the bead surface, and by using mixed beads having a particle diameter of 50 to 700 μm, more preferably 100 to 500 μm, both of the vulcanized rubber and the washing time can be compatible with the removal of fine particles.

The present invention also provides a method for cleaning a mold using the detergent, wherein the mold vulcanizes a tire mixed with an inorganic compounding agent and has an aluminum inner surface.

The vent bushing of the present invention can be used as a vent hole member of a vulcanization mold for a tire mixed with an inorganic compounding agent. The mold cleaning agent of the present invention can be used for cleaning a vulcanization mold of a tire mixed with an inorganic compounding agent.