JPH02223430A - Manufacture of tire - Google Patents

Abstract

PURPOSE:To simplify a molding mold and casting operation, by a method wherein a tire main body is formed of a pair of annular tires which comes to a break at a tread part. CONSTITUTION:A tread part 4 is provided through a side wall part 7 extending outward in a radial direction from a bead part 6 into which a bead core 5 is built, since the wall part 7 comes to a break at the tread port 4, a semi- annular tire 3 which is in a form obtained by dividing a tire main body 2 by the tread part 4 is formed by making use of a heat melting machine. A broken part 9 is melted by a hot plate, by approaching a pair of the semi-annular tires 3 in a space between the broken parts 9 of the tread part 4 through the hot plate further. Joining is performed and a desired tire is obtained by a method wherein the hot plate is taken out and the pair of the semi-annular tires 3 is pressed against the melted part by approaching the pair of the semi- annular tires 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a tire that can be manufactured easily and at a low price.

[Conventional technology]

Tires intended for off-road driving, such as tires for agricultural use, motocross tires for motorcycles, and tires for all-wheel drive off-road vehicles, generally contain waves within the cavity formed between the outer mold and the inner mold. It is formed by curing a polymeric material.

[Problem to be solved by the invention]

However, tires are annular with a U-shaped cross section with an opening facing inward, and therefore the mold used in the heat melting machine to cast the tire has a complicated structure, and the molding process is time-consuming. The cost will be high.

In order to simplify the mold, it is possible to divide the tire into multiple parts and glue them together, or to form the divided surfaces of the tire into eye jacks and fit them together, but the former method has a low bonding force and reduces the strength of the tire. In the latter case,
The structure of the mold becomes complicated, making it impossible to reduce costs.

The present invention is based on forming a pair of semi-annular tires using a heat melting machine, and heating and welding the joint using a hot plate, which allows the tires to be formed easily and accurately, reducing costs. The present invention aims to provide a tire manufacturing method that can solve the above-mentioned problems.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the tire manufacturing method of the present invention, the tread portion is formed through a sidewall portion extending radially outward from the bead portion in which the bead core is embedded. A semi-annular tire having a shape in which the tire main body is divided at the tread portion is formed by providing a tread portion and discontinuing at the tread portion using a heat melting machine, and the pair of semi-annular tires are formed between the discontinuous portion of the tread portion. By bringing them close together via a hot plate, the broken part is melted by the hot plate, and then the hot plate is removed, and a pair of semi-annular tires are brought close together and the melted part is pressed to join them.

[Effect]

Since the tire body is formed by a pair of semi-annular tires that are discontinued at the tread portion, it is easier to mold the semi-annular tire and the molding cost can be reduced compared to the case where the tire body is integrally molded.

Further, since the pair of semi-annular tires are brought close to each other via a hot plate, melted at the discontinuous portion, and then pressed together, they are joined at the discontinuous portion, so that a homogeneous joint can be easily achieved.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In the figure, the tire manufacturing method of the present invention involves manufacturing a tire body 2 by joining a pair of semi-annular tires 3.3 that are separated by a tread portion 4.

The tire body 2 is provided with a tread portion 4 via a sidewall portion 7 extending radially outward from a bead portion 6 in which a bead core 5 is embedded. Further, the tire body 2 is composed of a pair of semi-annular tires 3.3 having a discontinuous portion 9 in the tread portion 4 by dividing the tire body 2 at the tread portion 4 along a plane along the latitude line of the tire.

In this embodiment, the discontinuous portion 9 is provided on the tire equator C, and the tread surface of the tread portion 4 is provided with tread grooves 21 in the semi-annular tire 3.

Therefore, in this embodiment, the pair of semi-annular tires 3.3 are formed to have the same or symmetrical shape.

The semi-annular tire 3 is cast-molded using a heat melting machine W. As shown in FIG. 3, the heat melting machine W has a semicircular tire 3 between a fixed outer mold I3 and a movable inner mold 14.
A semi-annular tire 3 is formed by injecting a heat-melting polymeric material into the cavity 15 through an injection port 16 communicating with the cavity 15 and cooling it. Also semi-circular tire 3
Since the discontinuous portion 9 is formed in the tread portion 4, the structure of the outer and inner molds 14 can be simplified compared to the case where the tire body 2 is formed as one piece, and the manufacturing cost of the mold can be reduced.

Although liquid polyurethane, polyisoprene, polyester elastomer, etc. are used as the polymer material, polyester elastomer, which has excellent properties such as hardness and tensile strength after curing, can be suitably employed.

And a pair of semi-annular tires 3.3 formed in this way
The tire body 3 consists of: (1) a pair of semi-annular tires 3.3 that can be moved toward and away from each other;
Using a pair of holding molds 25A and 25B, the interrupted portion 9 is
．． Holding step to support 9 facing each other (Figure 4)
; ■ Contact and separation surfaces 253.25 of the holding near molds 25A and 25B
Insert the hot plate H into the gap d between 3 and the holding mold 25A.
, 25B close to each other, the semi-circular tire 3.3
is brought close to between the discontinuous portions 9.9 via a hot plate H, thereby melting the discontinuous portions 9 (fourth melting step).
- 5); ■ During the melting, an inner surface support step of supporting at least the inner surface in the vicinity of the discontinuous portion 9 using a support tool 26 (FIG. 5); ■ After the melting, the hot plate H is moved to the contact/separation surface 25S. It is formed through a joining step (FIGS. 5 and 6) in which the molten parts are pressed and joined together by taking them out from the gap d between them, moving the holding molds 25A and 25B, and bringing the contact/separation surfaces 253 closer together. .

As shown in FIG. 4, the holding molds 25A and 25B are formed on the opposing inner surfaces of the base body 27, which are supported so as to be able to move toward and away from each other.
A recess 29 that matches the shape of the outer peripheral surface of the semi-annular tire 3 is provided, and by fitting the semi-annular tire 3 into the recess 29, the semi-annular tire 3 is held with the interrupted portion 9 positioned on the contact/separation surface 25S. I can do it. Note that the discontinuous portion 9 is the contact/separation surface 2
A melt is formed by substantially protruding from 5S.

Further, in this example, one holding mold 25A is fixedly supported on, for example, a base (not shown), and the other holding mold 25B is fixedly supported on the base or the like through appropriate guide means. The holding molds 25A and 25B are attached so as to be movable in parallel in the direction and to be detachable, and the holding molds 25A and 25B can be relatively moved toward and away from each other due to the parallel motion.

Further, the base body 27 has a storage section 30 for storing a hot plate formed by cutting out the upper part of the contact/separation surface 25S, and the hot plate H is held in the radial direction by a support means 31 provided on the outer peripheral surface of the holding mold 25A. and is supported movably in the tire axial direction.

Therefore, the hot plate H is moved by the support means 31 as follows.
It is inserted into the gap d from the storage section 30.

In this example, as shown in FIG. 8, the hot plate H is made up of fan-shaped hot plate pieces H1-, which are obtained by dividing, for example, eight parts into eight parts of an annular plate-like body having a radius that can cover the end face of the discontinuous part 9. At the end of insertion into d, each end is brought into contact at a position overlapping with the end face of the discontinuous part 9, and continues in an annular shape.

In addition to heating the hot plate H from the surface in advance with a burner or the like, the temperature can be increased by installing an electric heating tool inside the hot plate H and energizing it.

Therefore, the holding molds 25A and 25B are brought close to each other at the discontinuous portion 9.
By bringing the hot plate 9 into contact with the hot plate H, the broken portion 9 is uniformly melted by the heating of the hot plate.

Further, during the melting, the inner surface near the interrupted portion 9 is supported by the support tool 26.

In this example, the support 26 is made of an airtight rubber-like sheet material, and is formed by a plader whose diameter expands radially outward in a toroidal shape when filled with internal pressure, and both ends of the plader are formed with an inner hole. It is attached to the outer circumferential surface of the cylindrical pedestal 33. The pedestal 33 is also provided with air inlets 35 on its outer circumferential surface that communicate with the inner holes. Therefore, the diameter of the support 26 is expanded by the air pressure filled from the injection port 35, so that it bulges out along the inner surface of the semi-annular tire 3, and presses the semi-annular tire 3 almost uniformly against the holding molds 25A, 25B. and retain its shape.

As a result, the support 26 is moved inward and outward in the radial direction of the discontinuous portion 9.9 caused by the deformation of the semi-annular tire, especially the pressure contact between the discontinuous portion 9.9 due to the approach of the holding molds 25A and 25B. It is possible to prevent bending deformation of the tire body 2, prevent joint misalignment, poor joint, etc., and improve the homogeneity of the tire body 2.

Further, after the hot plate H is taken out from the gap d and stored in the storage section 30, the contact/separation surface 253 is moved by the movement of the holding mold 25B.
．． 25S are brought close to each other, in this example, in contact with each other, and the melted portions of the discontinuous portions 9 melted by the hot plate H are pressed against each other to join them, thereby forming an integral tire body 2.

In this example, the diameter of the support 26 is expanded from the start of melting to the completion of joining, and the shape of the tire body 2 is maintained by supporting at least the inner surface near the discontinuous portion 9.

Further, as shown in FIG. 7, the tire body 2 is taken out from the holding fitting 25A by folding the support 27 by reducing the pressure and removing the holding fitting 25B.

Note that the discontinuous portion 9 is located at the tread groove portion 21 as shown in FIG.
In addition, as shown in FIG.
1 can be shifted to form the discontinuous portion 9, and in such a case, the area of the bonded surface increases and the strength of the bonded portion can be increased. Furthermore, the discontinuous part may be provided at a position away from the tire equator and formed by an asymmetric semi-annular tire,
The present invention can be modified in various ways depending on the use of the tire.

〔Effect of the invention〕

The present invention is a method of forming a semicircular tire in which the tire body is divided by the tread portion using a heat melting machine, and therefore a mold for cast molding can be easily formed. Mold work becomes easier.

In addition, since the discontinuous parts of a pair of semi-annular tires are melted by a hot plate interposed between the discontinuous parts and then the melted parts are pressed together, the joining process becomes simple, and these methods By combining these, we are able to provide tires at low prices.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a tire body manufactured using the method of the present invention, FIG. 2 is a cross-sectional view showing a semi-annular tire, and FIG. 3 is a mold for manufacturing the semi-annular tire. 4 to 7 are operational diagrams showing steps for forming the tire body, FIG. 8 is a route diagram showing a hot plate, and FIG. 9 is a sectional view showing another example of a discontinuous part. . 2.--Tire body, 3.--.Semi-circular tire, 4
-) Red part, 5- Bead core, 6--Bead part, 7- Side wall part, 9- Interrupted part, 2
5A, 25B--Holding mold, 253...-Contact/separation surface,
26-support, 29--recess, d--gap, W--thermal melter, H---hot plate.

Claims (1)

[Scope of Claims] 1. A tread part is provided through a sidewall part extending radially outward from a bead part in which a bead core is embedded, and the tire body is divided into halves at the tread part by discontinuing at the tread part. An annular tire is formed using a heat melting machine, and the pair of semi-annular tires are brought close to the discontinuous part of the tread portion via a hot plate, and after the discontinuous part is melted by the hot plate, the discontinuous part is melted by the hot plate. A method of manufacturing a tire by taking out a plate, bringing a pair of semi-annular tires close together and pressing the molten part to join them. 2. The pair of semi-annular tires are in contact with and separated from each other, and the discontinuous portion of the semi-annular tires is located on the contact/separation surface, and the recesses of the pair of holding molds have recesses that match the outer peripheral surface of the semi-annular tires. by inserting a hot plate into the gap between the contact and separation surfaces of the holding molds and bringing the holding molds close to each other, the pair of semi-annular tires are placed between the discontinuous portions of the tread portions through the hot plate. When melting the discontinuous part with the hot plate, at least the inner surface near the discontinuous part is supported using a support whose diameter expands radially outward, while the discontinuous part is melted by the hot plate. After that, the hot plate is taken out, and the holding mold is moved to reduce the gap and bring the contact/separation surfaces closer to each other, thereby bringing the pair of semi-annular tires closer together and pressing the molten part to join them. 1. The method for manufacturing a tire according to 1.