JP2001047440A - Method for vulcanizing and molding tire and heater of vulcanizing mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a molding accuracy and to shorten a vulcanizing time by heating an inner mold in which a rubber material is arranged on a periphery and the material to a temperature lower than a vulcanizing temperature of the material prior to starting of vulcanizing and molding. SOLUTION: In the vulcanizing mold for vulcanizing and molding a rubber material r arranged in an inner mold in a cavity partitioned by the high rigidity inner mold a for specifying an inner surface of a tire and an outer mold for specifying an outer surface of the tire, a support 3 of the mold a is provided at a front end of a rotary shaft 2, the support 3 is formed in a substantially cylindrical state as a whole, and a plurality of holes 4, 5 are formed as a heating medium passage in its peripheral wall. Openable and closable housing 6 surrounding the support 3 and the mold a is provided. An inside heating means for heating the mold a on the support 3 from an inner peripheral side is provided to communicate with a central channel, and an outside heating means for heating the mold a and the material r from an outer peripheral side is provided in communication with the housing 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of disposing a rigid inner mold for defining an inner surface of a tire and an outer mold for defining an outer surface of the tire in a cavity defined on the inner mold. The present invention relates to a method of vulcanizing a tire by vulcanizing and molding a rubber material, and a vulcanizing mold used for the method, particularly a heating device for an inner mold.

[0002]

2. Description of the Related Art Conventional vulcanization molding methods of this type include:
For example, it is disclosed in JP-A-62-270308. As shown in FIG. 4, which is a cross-sectional view of a main part of a vulcanizing mold, a retractable rigid core mold a including a plurality of rigid segments for molding an inner surface of a tire, and a sidewall portion of the tire. Two side split molds b for molding
b and a method of manufacturing a rubber tire for imparting a final shape cross-sectional dimension to a tire in a rigid mold having an outer peripheral crown split mold c divided into a plurality of segments for forming an outer portion of a tire tread portion. First, the tire material is placed on the assembled rigid core mold a, and then the outer crown split mold c is slid in a state where the cross sections of the adjacent segments are perfectly fitted to each other. And closing the respective segments of the two side split molds b and the outer crown split mold c while sliding in a state where the surfaces contacting with the side split molds b are in perfect contact with each other. Since all members of the mold involved in the final geometric shape are rigid, the geometric shape of the mold is smaller than that of a tire manufactured by a conventional molding method using a flexible film as a vulcanizing inner mold. High accuracy It is that it can be molded Vulcanization excellent tire.

[0003]

However, according to the prior art, the rigid core die a with the tire material disposed therein has a room temperature (2) which is much lower than a predetermined vulcanization molding temperature.
0 to 30 ° C.) and is in a state of being thermally shrunk as compared with vulcanization molding. Therefore, at the start of vulcanization using this core die a as an inner die, each side split die b, b When the outer mold composed of the outer peripheral crown split mold c is previously heated to a predetermined vulcanization molding temperature of about 180 ° C., it is defined as shown by clamping the inner mold and the outer mold. Cavity C
A volume becomes larger than the predetermined volume at the time of vulcanization molding,
Therefore, at the beginning of the vulcanization, the core mold a as the inner mold is used.
The upper predetermined volume of the tire material is not pressed against the inner surface of the outer mold with a required force, and in order to realize it, the core mold a is heated to a predetermined vulcanization molding temperature, and as expected. A time delay until thermal expansion is inevitable.

Therefore, during this time delay, the tire material on the core mold a is heated from the outer mold side to start vulcanization,
Since the vulcanization and curing proceeds from the outer surface side of the tire material before it is completely adhered to the inner surface of the outer mold as the molding surface, the core mold a is heated to a predetermined vulcanization molding temperature. By the time the tire material is pressed against the molding surface with the required force, the tire material has already transitioned from the plastic deformation region to the elastic deformation region. When the vulcanization mold is opened after finishing, the tread surface of the product tire, especially having complex irregularities, will return to the shape before elastic deformation, which allows the tread surface etc. to accurately match the molding surface There is a serious problem in terms of molding accuracy that a molding defect that is not formed according to the following occurs.

[0005] Therefore, the applicant of the present invention has previously described the vulcanization molding method of a tire and the heating of a vulcanization mold which prevent the occurrence of the above-mentioned improper molding while maintaining the advantages of vulcanization molding using an inner mold made of a rigid material. The apparatus has been previously proposed as Japanese Patent Application No. 10-262443.

[0006] This vulcanization method uses a rubber provided on an inner mold in a cavity defined by a high rigid inner mold that defines the inner surface of the tire and an outer mold that defines the outer surface of the tire. In vulcanizing the material, preferably, a cavity volume at the start of vulcanization is increased by heating and expanding an inner mold in which a rubber material is disposed on the peripheral surface in advance, so that a predetermined cavity volume at the time of vulcanization molding is obtained. The heating device is provided with a heating chamber for accommodating an inner mold having a rubber material disposed on a peripheral surface thereof, and a supply passage for flowing a heat medium into the inner mold in the heating chamber. A circulation path for the heat medium flowing out from the opposing surface of the inner mold is provided.

[0007] The present invention is a further improvement of such an invention based on the earlier proposal of the applicant, and is applicable not only to a high-rigidity inner mold but also to a rubber material disposed on the peripheral surface thereof. Further, by performing the preheating, higher molding accuracy is obtained, and at the same time, the vulcanization time is shortened.

[0008]

The method for vulcanizing and molding a tire according to the present invention is characterized in that, prior to the start of vulcanization, both an inner mold having a rubber material disposed on a peripheral surface and a rubber material are both used. And heating to a temperature lower than the vulcanization temperature of the rubber material.

According to this method, the cavity volume at the beginning of the vulcanization molding can be sufficiently brought close to the predetermined cavity volume at the time of the vulcanization molding by heating the inner mold. Can be sufficiently close to the design rubber volume for the above-mentioned predetermined cavity volume, so that the rubber material on the inner mold is quickly pressed against the inner surface of the outer mold with a large force when clamping the vulcanization mold. In this way, a smooth and excellent plastic flow of the rubber material can be brought about, thereby filling the mold cavity with the rubber material and the outer mold before the vulcanization of the rubber material proceeds. Since the gap can be sufficiently removed from the inner surface, the intended molding can always be performed accurately on the rubber material.

Further, in this molding method, prior to the start of the vulcanization, the inner mold having the rubber material disposed on the peripheral surface and the rubber material are subjected to the vulcanization of the rubber material or the deformation of the rubber material. By heating and expanding to a temperature at which there is no danger of vulcanization, the cavity volume and the rubber material volume at the start of vulcanization can be made closer to the predetermined cavity volume at the time of vulcanization molding and the designed rubber volume for it. preferable.

According to this, since the cavity volume at the start of vulcanization is reduced as compared with the prior art, the fluidity of the rubber material on the inner mold can be increased. The plastic flow of the rubber material at the time of clamping of the metal mold can be smoothened, and therefore, the molding accuracy of the rubber material can be further improved. Here, the heating temperature of the inner mold and the rubber material is preferably determined based on a difference between a predetermined cavity volume at the time of vulcanization molding and an actual cavity volume at room temperature, etc. The heating temperature is preferably in the range of 75 to 110 ° C.

By the way, the heating of the inner mold is performed by flowing a heat medium through a flow path provided therein, and the heating of the rubber material is performed by flowing the heat medium along the peripheral surface thereof. , It is possible to heat the inner mold and rubber material almost uniformly overall,
It is preferable to improve the uniformity of molding and vulcanization. Here, the uniformity of the heating is further improved when each of them is heated while rotating the inner mold together with the rubber material.

In the vulcanizing mold heating device of the present invention, a rotating shaft having a cylindrical inner mold supporting portion having a plurality of holes in a peripheral wall is provided at a tip portion and supported on a rotating shaft. A housing surrounding the inner mold is provided, and further enters the housing, engages with the inner mold support of the rotating shaft, and heat medium there.
For example, an inner heating means for supplying and circulating hot air is provided, and an outer heating means which is connected to the housing and which circulates hot air, for example, is provided on the outer peripheral side of the inner die on the rotating shaft. Here, the rotation axis can be either a horizontal axis or a vertical axis,
The housing is preferably an insulated housing.

In this apparatus, the hot air supplied to the inner mold support under the action of the inner heating means flows into the inner mold through the respective holes provided therein, is circulated therein, and is circulated there. By circulating the finished hot air through another hole of the inner mold support portion, the inner mold can be heated sufficiently uniformly at least in the width direction from the inner peripheral surface side. Here, by rotating the inner mold at a speed of, for example, about 3 to 10 rpm with a rotating shaft,
The inner mold can also be heated sufficiently uniformly in the circumferential direction.

In this apparatus, the external heating means
In the housing, the hot air is circulated around the inner mold and, eventually, the rubber material on the inner mold, and in conjunction with the rotation of the inner mold, the rubber material is also equally distributed in the width direction and the circumferential direction. Can be heated.

Accordingly, when the tire and the inner mold pre-heated in this way are applied to the pre-heated outer mold to vulcanize and mold the tire, high precision with no unevenness in any direction is obtained. And vulcanization time can be advantageously reduced by effectively preventing the occurrence of bears, burrs and the like.

Moreover, in this apparatus, the hot air supplied for heating is circulated and circulated in each of the inner heating means and the outer heating means, so that the residual heat of the hot air can be effectively reused.

[0018] In such an apparatus, preferably, a conical deflecting means is provided on the inner die supporting portion of the rotating shaft, which is located opposite to the heat medium supplied from the inner heating means. According to this, the deflecting means can diffuse the supplied heat medium sufficiently uniformly in the circumferential direction of the inner mold based on the shape of the heat medium, and further, the heat medium is transferred to the inner circumferential surface of the inner mold. , The inner mold can be more uniformly heated in both the circumferential direction and the width direction.

Preferably, a flow guide for the heat medium is provided in the housing along the outer peripheral surface of the inner mold, whereby the flow path of the heat medium to the rubber material is specified, and the heat medium flows smoothly. , Uniform heating of the rubber material in both the width direction and the circumferential direction is realized.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of a heating device according to the present invention. In the figure, reference numeral 1 denotes a motor, and 2 denotes a horizontal rotating shaft which is rotated by the motor 1.

At the tip of the rotary shaft 2, a support 3 of the inner mold a described in connection with FIG.
As is evident from the cross-sectional view of FIG. 2, the entire structure is substantially cylindrical and has a plurality of holes 4 and 5 as heat medium passages on the peripheral wall.

In this case, the inner cylinder supporting portion 3 and, consequently, the inner mold a disposed therein are surrounded, preferably under heat insulation.
An inner heating means 7 which contributes to heating of the inner mold a on the support portion 3 from the inner peripheral surface side thereof, and a similar inner mold a, and furthermore, on the peripheral surface thereof, while providing the housing 6 which can be freely opened and closed. Each of the outer heating means 8 which contributes to heating from the outer peripheral surface side of the disposed rubber material r is provided.

Here, the supply passage 9 for the heating medium, for example, the heated air, of the inner heating means 7 and its return passage 10 are each provided with a coupling 11 which can enter the housing.
Thus, it is possible to connect the inner cylinder supporting portion 3 to the shaft end on the open side, preferably in an airtight manner. By this connection, the supply flow path 9 supplies heated air into the support section 3 through the central flow path 12 of the coupling 8 as shown in FIG. Flows into the inner mold a through the hole 4 and is heated from the inner peripheral surface side.

On the other hand, the heated air which has finished heating the inner mold a and has absorbed the heat flows from the other hole 5 of the support part 3 to the annular flow path 10 via the peripheral flow path 13 of the coupling 8,
After heating again, it is reused for inner mold heating.

In the case where the inner mold is heated in this manner, more preferably, as shown in FIG.
Is provided with conical deflecting means 14 located opposite the central flow path 12, whereby the heating fluid from the central flow path 12 is sufficiently evenly distributed in the circumferential direction.
The smooth flow along the inner peripheral surface of the inner mold in the radial cross section as shown is ensured, and the uniformity of the heating of the inner mold a in the circumferential direction and the width direction is provided.

Here, each of the heated air supply flow path 14 and the return flow path 15 of the outer heating means 8 are separated from each other at the bottom of the housing 6 as shown in, for example, a longitudinal sectional view in FIG. Coupled with the housing 6
Inside, there is provided a flow guide 16 surrounding the inner mold a and, eventually, the rubber material r on the inner mold. The flow guide 16 here surrounds the rubber material r smoothly in the width direction and the circumferential direction at substantially equal intervals from the surface of the material, respectively, and heat air at two locations in the circumferential direction. It has an opening that allows the inflow and outflow of water.

According to this, the heated air supplied into the housing through the feed passage 14 flows into the flow guide 16 through the inlet opening thereof, and flows under the guidance of the flow guide 16 to the rubber material. r flows while being heated from the outer peripheral surface side, and mostly flows out of the housing through the outlet opening of the flow guide 16 after substantially rounding the rubber material r. Thus, the rubber material r is sufficiently uniformly heated to the expected temperature in each of the width direction and the circumferential direction in combination with the rotational movement of the inner mold a.
After the heating of the rubber material r is completed, the heated air flowing out of the housing 6 to the annular flow path 15 is heated again and reused for preheating the rubber material r.

Therefore, in this case, the inner mold a is held by the inner heating means 7 while the inner mold a is rotating at a predetermined speed.
Is heated from the inner peripheral surface side, and the rubber material r is heated from the outer peripheral surface side in the housing by the outer heating means 8, so that both of them are brought to the expected temperature.
Heating can be performed sufficiently uniformly in each of the width direction and the circumferential direction. Therefore, when the inner mold a and the rubber material r are heated in this way before the start of the vulcanization molding, cooperation with the outer mold is performed. At the start of vulcanization molding under operation, the initial cavity volume is made sufficiently close to the predetermined cavity volume at the time of vulcanization molding, and the volume of the rubber material r is sufficiently adjusted to the design rubber volume corresponding to the predetermined cavity volume. You can get closer.

For this reason, at the time of vulcanization molding of a tire, the rubber material r is allowed to flow smoothly over the entire cavity under its pre-expanded volume and high fluidity to realize better molding accuracy. In addition, the vulcanization time can be advantageously shortened by the residual heat of the inner mold a and the rubber material r, and the molding state and the vulcanization state can be sufficiently reduced in both the width direction and the circumferential direction. It can be evened out.

[0030]

As is apparent from the above description, according to the present invention, in addition to preheating the inner mold,
By directly preheating the rubber material on the inner mold, the molding accuracy in vulcanizing the tire is greatly increased,
At the same time, the vulcanization time can be advantageously reduced. And this means that preheating of the inner mold and the rubber material is performed under the rotation of the inner mold to remove uneven heating in each direction,
This is more pronounced when the moldability and vulcanizability are made more uniform throughout the rubber material.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing a heating state of an inner mold.

FIG. 3 is a longitudinal sectional view showing a heating state of a rubber material.

FIG. 4 is a sectional view of a main part of a vulcanizing mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 2 Rotating shaft 3 Support part 4,5 hole 6 Housing 7 Inside heating means 8 Outside heating means 9,14 Supply flow path 10,15 Ring flow path 11 Coupling 12 Central flow path 13 Peripheral flow path 14 Deflection means 16 Flow guide a Inner mold r Rubber material

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F202 AH20 CA21 CB01 CU01 CU11 CY01 CY21 CY25 4F203 AH20 DA11 DB01 DC01 DC03 DH06 DL10 DL11 DM03 DW41

Claims (6)

[Claims] A rubber material disposed on an inner mold is vulcanized in a cavity defined by a high-rigid inner mold defining an inner surface of a tire and an outer mold defining an outer surface of the tire. In doing so, prior to the start of vulcanization molding, a vulcanization molding method for a tire, comprising heating an inner mold having a rubber material disposed on a peripheral surface thereof and each of the rubber materials. 2. The method according to claim 1, wherein the inner mold is heated by a heat medium flowing into a flow path formed in the inner mold, and the rubber material is formed by a heat medium flowing along a peripheral surface of the rubber material disposed on the inner mold. The tire vulcanization molding method according to claim 1, wherein the tire is heated. 3. The tire vulcanization molding method according to claim 1, wherein each of the inner mold and the rubber material is heated while rotating the inner mold. 4. A housing, wherein a rotating shaft having a cylindrical inner mold supporting portion having a plurality of holes in a peripheral wall is provided at a distal end portion, and a housing surrounding the inner mold supported on the rotating shaft is provided. The inner heating means which enters into the inner shaft and engages with the inner die support portion of the rotating shaft to supply and reflux the heat medium thereto, and the outer peripheral side of the inner die on the rotating shaft connected to the housing A heating device for a vulcanizing mold, which is provided with an outside heating means for circulating a heating medium. 5. The vulcanizing mold according to claim 5, wherein a conical deflecting means is provided on the inner mold supporting portion of the rotating shaft, which is located opposite to the heat medium supplied from the inner heating means. Heating equipment. 6. In the housing, along the outer peripheral surface of the inner mold,
The heating device for a vulcanizing mold according to claim 4 or 5, further comprising a flow guide for a heating medium.