JP3484350B2 - Tire manufacturing method and heating device used therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire manufacturing method capable of shortening the vulcanization time by utilizing preheating by induction heating, and a heating device used therefor.

[0002]

2. Description of the Related Art Generally, for vulcanizing a tire, as shown in FIG. 8, an outer mold a having a tire molding cavity a1 and a bladder for pressing a raw tire t on the inner peripheral surface of the tire molding cavity a1. b) is used to heat the raw tire from inside and outside by a uniform amount of heat conducted from a heater h incorporated in the outer mold a and a heat medium such as steam e filled in the bladder b. To be done.

However, in the tire structure, as is well known, the thickness varies depending on the tread portion, sidewall portion, bead portion and the like. Therefore, in the conventional method, particularly in the tread portion or bead portion having a large thickness. Since a lot of heating time is required, there is a problem that the vulcanization time of the tire as a whole is lengthened. Further, at this time, the vulcanization degree becomes non-uniform due to over-vulcanization in the side wall portion having a small thickness, and the tire performance may be deteriorated.

Incidentally, for example, Japanese Patent Application Laid-Open No. 8-335496 proposes to heat the raw tire by microwaves (300 MHz to 30 GHz) utilizing the action of so-called electromagnetic waves prior to the main vulcanization. As described in the above-mentioned publication, microwave heating causes a rapid temperature rise and is extremely difficult to control. Moreover, the end portions of metal materials such as steel cords and bead wires, which are tire constituent members, are excessively heated and abnormally rise in temperature. There is also a problem.

Therefore, the present invention is based on the use of induction heating in a frequency range lower than the microwave heating, and is based on the fact that a temperature adjusting means made of a conductive material is provided on a part of the tire surface, and tires having different thicknesses are provided. Each part can be quickly preheated while easily controlling it with the required temperature distribution, which makes it possible to vulcanize the entire tire at a uniform temperature in the main vulcanization, which results in a wide vulcanization time. An object of the present invention is to provide a tire manufacturing method capable of achieving shortening and a heating device used therefor.

[0006]

In order to achieve the above object, the invention of claim 1 of the present application is to preheat a toroidal raw tire having a conductive reinforcing member made of a conductive material prior to main heating. A method of manufacturing a tire, wherein a conductive wire surrounds a raw tire with a heating coil portion that spirals around a bead bottom portion and a tread portion, and includes an outer surface and a lumen surface of the raw tire. It is characterized in that temperature adjusting means made of a conductive material is provided on at least a part of the tire surface, and the heating coil is energized to preheat the raw tire by induction heating of the conductive material by electromagnetic induction.

In the invention of the tire manufacturing method of claim 2, the temperature adjusting means is in the form of a sheet, and the temperature rise is slow in the tire surface of the tread portion or the bead portion so as to uniformly heat the raw tire. It is characterized by being attached to. The variation in temperature rise is caused by a difference in volume of the conductive material included in the conductive reinforcing member and a difference in distance between the heating coil portion and the conductive reinforcing member.

In the invention of the tire manufacturing method of claim 3, the temperature of at least a part of the outer surface of the tire is measured during preheating.

Further, the invention of the tire manufacturing method of claim 4 is characterized in that the heating coil portion and the green tire are relatively rotated.

A fifth aspect of the present invention is the heating device according to the first aspect, characterized in that the heating coil portion can be divided in the axial direction.

Further, in the invention of the tire heating apparatus according to claim 6, the heating coil portion has a length surrounding a part or all of the raw tire.

Further, the invention of the tire heating apparatus according to claim 7 is characterized in that it has a rotating means for relatively rotating the heating coil portion and the green tire.

As is well known, "induction heating" means that when a magnetic material or a conductive material is placed in a high frequency magnetic field, heat is generated in an extremely short time due to hysteresis loss and Joule heat due to eddy current. It means that the metal is directly heated by utilizing the heat generated by the induction action.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a model of a heating device 1 for a tire. The heating device 1 includes a conductive wire 2
Is equipped with a heating coil portion 3 that spirals around the bead bottom portion 34A of the raw tire 31 and the tread portion 32, and the heating coil portion 3 is supplied with electricity from a high frequency power source 4 connected to the conductive wire 2. High frequency magnetic flux G oriented in the tire circumferential direction
Is generated, and the electromagnetic induction effect of this causes induction heating of the raw tire 31 arranged in the magnetic field.

In the present embodiment, the heating device 1 is used for preheating the toroidal raw tire 31 having the conductive reinforcing member 30 prior to the vulcanization heating in the mold which is the main heating.

The raw tire 31 is, as shown in FIG.
The tread portion 32, a pair of sidewall portions 33 extending inward in the tire radial direction from both ends of the tread portion 32, and a bead portion 34 located at an inner end of the tread portion 32 and reinforced by a bead core 35 are provided. A carcass 36 is bridged between the bead portions 34, 34, and a breaker 37 is arranged outside the carcass 36 and inside the tread portion 32.

The bead core 35 has a ring shape formed by winding a steel bead wire in a plurality of layers.
A taped type that uses a strip in which eight bead wires are arranged side by side or a single wind type that continuously winds one bead wire is used.

The breaker 37 is composed of two or more breaker plies in which steel breaker cords are arranged at an angle of 70 ° or less with respect to the tire equator. In this example, the breaker cords and the bead wires are used to conduct electricity. Of the conductive reinforcing member 30.

In the carcass 36, the carcass cords are arranged at an angle of 70 to 90 ° with respect to the tire equator.
It consists of more than one carcass ply. In this example, the carcass cord is exemplified by a non-conductive material which is an organic fiber cord such as nylon, polyester, rayon or the like, but when a steel cord is used, the conductive reinforcing member 30 can be configured.

Therefore, the conductive reinforcing member 30 is embedded in at least the tread portion 32 and the bead portion 34, which have a large thickness and require a long heating time.

The heating device 1 will be described in detail. As shown in FIGS. 2 and 3, the heating device 1 includes upper and lower support plates 6U and 6L which are held so as to move toward and away from each other, and the upper support plate 6U. Upper coil portion 7U and the lower support plate 6
The heating coil portion 3 is composed of a lower coil portion 7L attached to L, and a connecting means 9 capable of electrically connecting the upper and lower coil portions 7U and 7L.

In this example, the lower support plate 6L is the leg piece 1
The upper support plate 6U is horizontally supported at the upper end, and the upper support plate 6U has a hinge-like pivotal attachment 11 attached to one side edge of the lower support plate 6L, and has a small gap g and faces in parallel with each other at a close position Y1. When,
For example, a separated position Y2 that stands up and separates from the lower support plate 6L.
Is rotatably supported around the pivot point 11A.
It is also possible to use an elevating tool instead of the pivotal attachment 11 to support the upper support plate 6U so that it can be moved vertically up and down. At this time, as the elevating tool, for example, a ball screw mechanism, a rack
Well-known structures such as a pinion mechanism and a link mechanism can be adopted.

The upper and lower support plates 6U and 6L are respectively
A disc-shaped inner support plate piece 1 by providing an annular hole 12 therethrough.
3 and the outer support plate piece 14 on the outer side thereof, and the annular hole 12 forms a housing portion for housing the raw tire 31 in a lateral direction. Therefore, the inner peripheral edge 12i of the annular hole 12
Is smaller than the inner diameter of the bead formed by the bead bottom portion 34A, and the diameter of the outer peripheral edge 12o of the annular hole 12 is
The diameter is larger than the tire outer diameter formed by the tread portion 32. The inner support plate piece 13 and the outer support plate piece 14 are integrally connected by a plurality of connecting members 15. The connecting member 15 arranged on the upper support plate 6U has a U-shape having an upper joint 16U that passes through the upper side of the annular hole 12 and crosses the annular hole 12, and is arranged on the lower support plate 6L. The connecting member 15 to be connected passes through the lower side of the annular hole 12 and the annular hole 12
Is formed in a U shape having a lower joint portion 16L that traverses.

The upper coil portion 7U is composed of a plurality of upper semi-circular arc lines which are conductive wires extending in a semi-circular arc shape from the outer peripheral edge of the inner support plate piece 13 to the inner peripheral edge of the outer support plate piece 14. The upper half-circular arc line 17U is formed of 17U, and is arranged with a substantially constant interval over the entire circumference of the annular hole 12 in this example.

The lower coil portion 7L is also formed by a plurality of lower half arc lines 17L having substantially the same structure as the upper coil portion 7U. Therefore, the plurality of upper half-arc lines 17U and the lower half-arc lines 17L cooperate with each other to form the heating coil portion 3 that spirally circulates around the raw tire 31, and in the present example, the heating coil portion 3 over the entire periphery of the raw tire 31. While being formed, the heating coil portion 3 is configured to open the tire storage space H provided between the upper half arc line 17U and the lower half arc line 17L, that is, between the upper and lower coil portions 7U and 7L. .

The upper half arc line 17U and the lower half arc line 1
As shown in FIG. 5, each end of 7L has the support plate 6U,
The connection means 9 protruding from 6L to the side of the small gap g enables ON / OFF connection.

The connecting means 9 is fixed to one support plate in this example, that is, the upper support plate 6U in this example, and has a spherical convex terminal portion 19A swelling at the inner end of the first connecting plate. It is composed of a terminal fitting 19 and a second terminal fitting 20 arranged on the other support plate 6L. The second terminal fitting 20 has a spherical receiving surface that can be engaged with the convex terminal portion 19A at an inner end of a body portion 20B that is slidably held by a bearing hole 21 provided in the support plate 6L. The recessed terminal portion 20A has a recessed terminal portion 20A.

Therefore, at the separated position Y2, the terminal fittings 19 and 20 are separated from each other to be in the OFF state, while at the adjacent position Y1, the convex terminal portion 19A and the concave terminal portion 20A are engaged and pressed against each other. Then, it is automatically connected to the ON state.

Further, as shown in FIG. 4, the lower joint 16 is formed.
The central portion 23 of L extends across the tire storage space H, and in this example, a ring-shaped tray 24 placed on the central portion 23 is used to load the raw tire 31 into the tire storage space H. It is held at the central height position. The tray 24 is a sidewall portion 33 of the raw tire 31.
A receiving portion 24A for receiving the outer surface is provided.

Here, at least the support plates 6U, 6
L, the connecting member 15, the pivotal attachment 11 and the tray 24,
It is necessary to use a non-conductive material such as synthetic resin so as not to affect the electromagnetic induction effect of the heating coil section 3. In addition, the upper and lower support plates 6U and 6L have a proximity position Y.
In order to perform the positioning of No. 1, it is preferable to dispose positioning means (not shown) using, for example, a positioning pin or a spacer for holding the small gap g.

Next, a tire manufacturing method using the heating device 1 will be described. This manufacturing method includes a preliminary heating step of preheating the raw tire 31 by induction heating prior to the main heating. In this preliminary heating step, first, a tire storage space that is opened and closed by moving the upper support plate 6U closer to and further away from the tire storage space. The raw tire 31 is put into H.

At the proximity position Y1 where the tire storage space H is closed, the terminal fittings 19 in the connecting means 9 are
20 is connected to the ON state, so that the heating coil portion 3 in which the conductive wire spirally circulates through the bead bottom portion 34A and the tread portion 2 can be attached to the raw tire 31.

After that, the high frequency power source 4 is operated to energize the heatable coil portion 3, and the high frequency magnetic flux G in the tire circumferential direction generated by this induction heating (self-heating) of the conductive reinforcing member 30 in the raw tire 31. ) At least, the thick tread portion 32 and the bead portion 34 are effectively heated from the inside thereof.

At this time, the tread portion 32 and the bead portion 3
4 in order to raise the temperature while controlling the temperature of each unit 32 and 34 to the temperature required by each unit,
In order to make the temperatures in 2 and 34 uniform, the tire surface S
Among them, the temperature adjusting means 25 made of a conductive material is arranged in a range where the temperature rise is slow. The “tire surface S” means a surface including an outer surface S1 and a lumen surface S2 of the raw tire 31, as shown in FIG.

The temperature adjusting means 25 has a thickness of 0.
The sheet-like body 26 made of, for example, iron having a thickness of 1 mm or less is
It is suitable from the viewpoint of handleability, and is wound around a part of the tire surface S substantially continuously in the circumferential direction. The temperature adjusting means 25 compensates for insufficient heating by the conductive reinforcing member 30 by self-heating due to induction heating, while heating from the tire surface side to achieve uniform internal temperature.

The temperature adjusting means 25 generally has a tread portion 32 having a rubber volume larger than that of the bead portion 34.
In addition, it is attached to the outer surface S1 side which is a large distance from the conductive reinforcing member 30 which is the breaker 37. However, depending on various conditions such as the structural condition of the conductive reinforcing member 30, the bead portion 34 or both of them may be attached. It can also be placed in.

The high frequency power source 4 used for induction heating
Usually, the frequency is in the range of 50 Hz to 1 MHz, but if the frequency is high, the so-called skin effect becomes large and temperature unevenness is strong, and therefore, in this example, 1 KHz to 50 MHz.
It is preferably used in a low frequency range of 0 KHz, for example, about 25 KHz.

In the preheating step, the surface temperature is measured by a non-contact temperature sensor 27 (shown in FIG. 1) such as an infrared temperature sensor, the preheating step is completed, or the output of the high frequency power source 4 is controlled. However, the heating temperature may be controlled by, for example, keeping the output of the high frequency power source 4 constant and controlling the operating time.

In this example, the heating coil section 3 is
Since the raw tire 31 has a length that surrounds the entire circumference, even when the raw tire 31 is fixed and held, it can be uniformly heated in the circumferential direction.

However, as shown in FIG. 7, the heating coil portion 3 is connected to a part of the raw tire 31, for example, one of the length in the circumferential direction.
It can be formed to have a length of about / 4, and in such a case, it is necessary to rotate the raw tire 31 relative to the heating coil portion 3. For that purpose, a rotating means (not shown) for rotatably holding the raw tire 31 around the tire axis using a bearing or the like is provided in, for example, the lower joint 16U or the tray 24 of the heating device 1. it can.

[0041]

Examples Tire size 195 / 65R15 shown in FIG.
A raw tire of a passenger car tire was manufactured as a prototype and preheated under the following conditions using the heating device shown in FIGS. Temperature control means: An iron sheet having a thickness of 0.1 mm is continuously attached to the outer surface S1 of the tread portion in the circumferential direction.・ Frequency of high frequency power supply: 25 KHz ・ Set temperature (tread part / bead part): 70 ° C / 70
° C

In a heating time of about 1 minute and 15 seconds, the tread portion and the bead portion could be uniformly heated to 70 ° C.

When this was vulcanized by main heating with a conventional vulcanizing mold, the standard vulcanizing time was 10 minutes, but a reduction of 75 seconds could be achieved.

[0044]

Since the present invention is constructed as described above,
Each part of the tire with different thickness can be quickly preheated while easily controlling with the required temperature distribution,
As a result, in the main vulcanization, the entire tire can be vulcanized at a uniform temperature, and the vulcanization time can be shortened.

[Brief description of drawings]

FIG. 1 is a schematic view showing a model of a heating device according to an embodiment of the present invention.

FIG. 2 is a perspective view specifically showing a heating device.

FIG. 3 is a sectional view thereof.

FIG. 4 is a cross-sectional view showing a mounted state of a raw tire.

FIG. 5 is a cross-sectional view showing an example of connecting means.

FIG. 6 is a cross-sectional view showing an example of a raw tire suitably used in the present invention.

FIG. 7 is a diagram showing another embodiment of the heating coil unit.

FIG. 8 is a sectional view illustrating a conventional technique.

[Explanation of symbols]

3 heating coil 25 Temperature control means 30 Conductive reinforcing member 31 raw tires 32 tread section 34A bead bottom S tire surface Outer surface of S1 green tire Lumen surface of S2 green tire

─────────────────────────────────────────────────── --Continued from the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 35/00-35/14 B29C 33/00-33/68

Claims (7)

(57) [Claims] 1. A method of manufacturing a tire in which a toroidal raw tire having a conductive reinforcing member made of a conductive material is preheated prior to main heating, wherein a conductive wire passes through a bead bottom portion and a tread portion. A heating coil portion that spirals around is mounted around the raw tire, and a temperature adjusting means made of a conductive material is disposed on at least a part of the tire surface including the outer surface and the inner surface of the raw tire, and the heating is performed. A method for manufacturing a tire, comprising preheating a green tire by energizing a coil portion and inductively heating the conductive material by an electromagnetic induction effect. 2. The temperature adjusting means is in the form of a sheet, and the temperature adjusting means is provided in a range where the temperature rise is slow in the tire surface of the tread portion or the bead portion so as to uniformly heat the raw tire. 1. The method for manufacturing a tire according to 1. 3. The method for manufacturing a tire according to claim 1, wherein the temperature of at least a part of the outer surface of the tire is measured during preheating. 4. The method of manufacturing a tire according to claim 1, 2 or 3, wherein the heating coil portion and the green tire are rotated relative to each other. 5. The heating device according to claim 1, wherein the heating coil portion is axially dividable. 6. The tire heating device according to claim 5, wherein the heating coil portion has a length that surrounds a part or the whole of the green tire. 7. The tire heating apparatus according to claim 5, further comprising a rotating means for relatively rotating the heating coil portion and the green tire.