JPH05301230A - Method for heating solid tire having double-layered structure - Google Patents

Abstract

PURPOSE:To enhance the productivity at the time of preheating by covering the layer having a high loss factor easy to collectively receive microwave of a solid tire having a double-layered structure different in loss factor at each layer with a microwave reflecting member to irradiate the same with a microwave to achieve a uniform temp. rise. CONSTITUTION:An applicator 3 is irradiated with the microwave from a microwave generator 1 through a waveguide 2 and the solid tire 5 having a double- layered structure placed on a rotary support stand 4 is preheated. A microwave reflecting member 6 is provided to the outer peripheral surface of the solid tire 5 and the microwave is not directly applied to the outermost layer of the solid tire opposed to the reflecting member 6. Therefore, by forming the outermost layer as a layer having a high loss factor, the microwave wave applied to the outermost layer can be reduced as compared with the other layers and the solid tire 5 having a double layered structure can be uniformly preheated and the productivity at the time of preheating can be enhanced to a large extent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a microwave heating method for a solid tire having a multi-layer structure having a different loss coefficient for each layer.

[0002]

2. Description of the Related Art Conventionally, as a tire used for a special vehicle such as a forklift truck, there has been known a solid tire having a multi-layer structure in which rubber layers having different characteristics are laminated in a circumferential direction. When vulcanizing a thick-walled tire such as this multi-layer solid tire, when vulcanizing the tire at room temperature, in the heat conduction method from the surface, the central part where temperature rise is most difficult reaches the optimum vulcanized state. At times, there was a problem that the outer surface part was over-vulcanized. Therefore, before the vulcanization operation, a preheating operation is employed in which the tire is stored in a relatively low temperature greenhouse for a long time and the temperature inside the tire is raised on average.

Usually, this preheating operation requires a long time, and the storage space of the greenhouse is enormous. Therefore, the heat capacity of the greenhouse is large, and the heat dissipation to the outside air is also large, resulting in the problem that the heating efficiency has to remain at a low level. In order to solve this problem, for example, in Japanese Patent Publication No. 57-42501,
A method utilizing microwave heating has been disclosed in order to reduce the preheating time of the tire.

[0004]

The normal preheating operation by microwave heating is a solid tire having a multi-layer structure, and when the loss coefficient of each layer is different, the loss coefficient is proportional to the amount of heat generated. The microwave power is concentrated in the layer having a high loss coefficient, and it is difficult to uniformly raise the temperature of the entire solid tire, which causes a problem that an optimum preheating temperature cannot be obtained. It is also possible to separately heat each layer of a solid tire having a multi-layer structure with different loss factors and then form a solid tire having a multi-layer structure, but heat transfer to other layers that does not preheat during tire forming However, there is a problem that the preheating effect is deteriorated, and if the multi-layered rubber is to be preheated at the same time, a microwave heating device corresponding to the number is required.

The object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a microwave heating method for a solid tire having a multi-layer structure, which enables uniform preheating even for a solid tire having a multi-layer structure having a different loss coefficient for each layer.

[0006]

A microwave heating method for a solid tire having a multi-layer structure according to the present invention is a microwave heating method for a solid tire having a multi-layer structure having a different loss coefficient for each layer. It is characterized in that a layer having a loss coefficient is covered with a microwave reflecting member and is irradiated with microwaves.

[0007]

In the above structure, by placing a microwave reflecting member, such as a metal plate, for reflecting microwaves on a layer having a high loss coefficient where microwave power is easily concentrated, and by eliminating the concentration of microwaves on this layer, It is possible to make the temperatures of the high loss coefficient layer and other layers substantially the same without heating only the high loss coefficient layer, and it is possible to uniformly heat the multi-layer structure solid tire. Regarding the position of covering the layer of high loss coefficient with the microwave reflecting member, needless to say, even if it is a part, it is effective, but the microwave reflecting member is used as the ground contact surface of the multilayer solid tire. It is preferable to provide it on the entire outer periphery of the outermost layer having a high loss coefficient, since a large proportion of the surface irradiated with microwaves can be easily covered.

[0008]

FIG. 1 is a diagram showing an example of a state in which the microwave heating method for a solid tire having a multilayer structure of the present invention is carried out. In FIG. 1, 1 is a microwave generator for generating microwaves, 2 is a waveguide for transmitting microwaves generated from the microwave generator 1, and 3 is an application forming a chamber for preheating. Applicator 3
A rotary type pedestal made of polypropylene, which is preferably a microwave transmitting material, provided therein, 5 is an unvulcanized multi-layered solid tire placed on the pedestal 4 to be preheated,
Reference numeral 6 denotes a microwave reflecting member made of a cylindrical metal plate provided on the outer peripheral surface forming the ground contact surface of the multilayer solid tire 5.
Is a stirrer (rotary blade reflector) for stirring and uniforming the electric field in the applicator 3.

In the state shown in FIG. 1, the microwave generated by the microwave generator 1 is applied to the inside of the applicator 3 through the waveguide 2 so that the compound placed on the rotating support base 4 is moved. Preheating of the layered solid tire 5 can be performed. At this time, in the present invention, since the microwave reflecting member 6 is provided, the outer peripheral surface of the solid tire 5 having a multilayer structure which opposes the microwave reflecting member 6 is not irradiated with the linear microwave. Therefore, by forming this portion as a layer having a high loss coefficient, the microwave radiated to the layer having a high loss coefficient can be reduced as compared with other layers, and as a result, uniform preheating of the multilayer solid tire 5 is performed. be able to.

FIG. 2 is a diagram showing in detail the relationship between the solid tire 5 having a multi-layer structure and the microwave reflecting member 6 in the state shown in FIG. 1, and FIG. 2 (a) is a perspective view thereof. (B)
FIG. 3 is a diagram showing a cross section taken along line AA in FIG.
In the present embodiment, the solid tire 5 having a multi-layer structure is composed of the outermost peripheral layer and unvulcanized rubber layers 5-1, 5-2, 5-3 having a three-layer structure, and the outermost peripheral layer 5-1 is the other layer. The layer having a higher loss coefficient than the layers 5-2 and 5-3. Also, each layer 5-1 to 5
As an example of a tire for a forklift truck as a specific example of No. 3, a rubber layer 5-1 is a top rubber having excellent wear resistance, a rubber layer 5-2 is a middle rubber that absorbs unevenness, and a rubber layer 5-3 is a special short. It is composed of fiber-containing base rubber.

FIG. 3 is a view showing an example of the microwave reflecting member 6 used in the present invention, and FIG. 3 (a) is used when the microwave reflecting member 6 is placed facing the tire ground contact surface of the outermost layer. 3B shows a cylindrical metal plate 6-1 and FIG. 3B shows a donut-shaped metal plate 6-1 used when the microwave reflecting member 6 is placed on the side surface of the layer having a high loss coefficient. The shape of the microwave reflecting member 6 basically determines the area to be shielded of the layer having a high loss coefficient by the ratio of the weight of each layer constituting the tire and the loss coefficient, and the shape thereof depends on the required area. , To set the area. Therefore, the shape of the microwave reflecting member 6 is not limited to the shape shown in FIG. 3, and any shape can be adopted according to the purpose, and the material of the microwave reflecting member 6 can also reflect microwaves. It goes without saying that it is not limited to metals.

An example in which preheating before vulcanization of a solid tire having a three-layer structure in which the outermost layer is a layer having a high loss factor in the state shown in FIG. 1 will be described below. First, when a tire was irradiated with microwaves for 10 minutes without placing a metal plate as the microwave reflecting member 6, a remarkable temperature rise was recognized in the outer layer having a high loss coefficient, as shown as a comparative example in Table 1 below. Despite this, the result was that the middle and inner layers hardly heated. On the other hand, when a cylindrical metal plate 6-1 was placed on the outer periphery of the tire outer layer to eliminate the concentration of microwave power to the outer layer having a high loss coefficient, as shown in Example 1 in Table 1, the microwave for 10 minutes was used. The results showed that the temperature rise of the outer layer was suppressed by the wave irradiation, and the temperatures of the inner layer and the inner layer were fairly equalized. Further, when a doughnut-shaped metal plate 6-2 was placed on the upper and lower sides of the cylindrical metal plate 6-1 to cover the layer having a higher loss coefficient, as shown in Example 2 of Table 1, the same 10 It was obtained that the temperature difference between the inner layer and the inner layer and the outer layer was further eliminated by the microwave irradiation for a minute, and the temperature could be raised almost uniformly. In Table 1, the position where the temperature was measured corresponds to the position indicated by the number in FIG. 2 (b).

[0013]

[Table 1]

The present invention is not limited to the above-mentioned embodiments, but various modifications and changes can be made. For example, in the above-mentioned embodiments, only one example of the apparatus for carrying out the present invention is shown, but any structure may be used as long as it can irradiate the unvulcanized tire with microwaves. At the same time, only an example of a multi-layer tire having a three-layer structure has been shown as an example of a tire, but it is clear that the present invention can be suitably applied to a tire having a structure other than three layers.

[0015]

As is apparent from the above description, according to the present invention, since the micro layer of the multi-layer structure solid tire having the high loss coefficient is covered with the reflecting member, for example, the micro area for one hour can be irradiated. As a result, it becomes possible to uniformly preheat to a preheating temperature that cannot be obtained by long-term storage in a greenhouse, and the following effects can be obtained. (1) A greenhouse is not needed for long-term storage, resulting in significant space and energy savings. (2) The productivity at the time of preheating can be significantly improved, and the energy efficiency can be significantly improved. (3) Since the preheating temperature can be increased, the time for main vulcanization can be greatly shortened, and the productivity during vulcanization can be greatly improved.
Energy efficiency can also be greatly improved. (4) Since the time for main vulcanization can be shortened, the point where the tire surface was over-vulcanized compared to the center of the tire where conventional vulcanization is most delayed is eliminated, and a more uniform degree of vulcanization is obtained. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a state in which a microwave heating method for a multi-layer structure solid tire of the present invention is carried out.

FIG. 2 is a diagram showing in detail the relationship between the multi-layer structure solid tire shown in FIG. 1 and a microwave reflecting member.

FIG. 3 is a diagram showing an example of a microwave reflecting member used in the present invention.

[Explanation of reference symbols] 1 microwave generator 2 waveguide 3 applicator 4 support 5 multi-layered solid tire 6 microwave reflection member 7 stirrer

Claims (2)

[Claims] 1. A microwave heating method for a solid tire having a multi-layer structure having a different loss coefficient for each layer, wherein a layer having a high loss coefficient in which microwaves are easily concentrated is covered with a microwave reflecting member. A method for heating a solid tire having a multi-layer structure, which comprises irradiating the solid tire. 2. The method for heating a solid tire having a multilayer structure according to claim 1, wherein the microwave reflecting member is provided on the entire outer periphery of the outermost layer having a high loss coefficient, which is the ground contact surface of the solid tire having a multilayer structure.