JPH03148302A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve uniformity and riding comfortableness by using a semi- vulcanized or vulcanized tread rubber member on its outer surface of which tread groove is previously formed, and interposing a cushion rubber layer between the thread rubber member and a tire base member. CONSTITUTION:A pneumatic tire 1 is formed by vulcanizing and integrating a raw tire member formed by laminating a reinforcing layer 3 and a rubber member 4 on a tire base member 2 in a vulcanizing metal mold. A cushion rubber layer 5 is interposed between the tire base member 2 and the reinforcing layer 3. The tire base member 2, is provided with a tread bottom portion 11 through a side wall portion 10 extending to an externally radial direction from a bead portion 9 in which a bead core portion 8 is embedded. Further, the tread bottom portion 10 is formed by connecting a pair of right and left semi- annular tire pieces 12A, 12B by the end portion 13a of a protruding piece 13. The tread rubber member 4 has its tread face on which a tread groove G is previously formed and is formed as a semi-vulcanized or vulcanized rubber sheet member.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention improves the uniformity of a cast tire in which tread rubber is formed on the outside of a tire base made of a polymeric material, and reduces vibrations, lateral vibrations, etc. Reduce ride comfort,
This invention relates to a pneumatic tire that can improve handling stability and extend the life of the tire.

[Conventional technology]

In recent years, pneumatic tires whose bead, sidewall, and tread parts are cast-molded using polymeric materials have become inexpensive and suitable for relatively low-speed vehicles such as agricultural machines, motocross motorcycles, and all-wheel drive vehicles. These tires are now being used as tires, and even in such tires, the tread part has a reinforcing layer using reinforcing cords, etc., and tread rubber with recessed tread grooves. is often provided.

On the other hand, such Toretsu I-rubber T has conventionally been manufactured by wrapping a raw rubber sheet C of a strap through a reinforcing b on the outside of the tire base a, as shown in FIGS. 7(a) to (c), for example. After that,
Reinforcement N! by vulcanization in the vulcanization mold! The tread grooves g are formed by integrating them into the tire base a with Jb, and the tread grooves g are patterned convex portions d provided in the 7w1 sulfur special mold.
A recess is formed by pushing the raw rice into the five raw rice sheets C.

[Problem to be solved by the invention]

However, in a conventional tire in which an unvulcanized raw rubber sheet C is used and tread grooves are formed at the same time during vulcanization molding, the entire tire base a is damaged due to the pushing pressure of the pattern convex portions d. It is easy to distort and deform, and it lacks roundness, impairing the tire shape, and especially the reinforcement under the tread groove. b. The tire base a was deformed in a wavy manner, and the tread gob thickness under the tread groove, that is, the sub-tread gauge thickness, etc., was made non-uniform, resulting in a significant decrease in uniformity. As a result, the tire's radial runout (RRO), radial force variation (RFV), and lateral runout (LRO)
, worsens the lateral force variation (LFV) and induces longitudinal vibrations and shaking when driving, greatly reducing ride comfort and steering stability.

Furthermore, due to the non-uniformity of the gauge thickness, cracks, peeling, etc. occur in the trend rubber, shortening its life and impairing its durability.

The present invention is based on the use of a semi-vulcanized or already vulcanized tread rubber body with tread grooves pre-formed on the outer surface, which increases uniformity, improves ride comfort and handling stability, and extends life. The purpose is to move pneumatic tires that can measure the

[Means to solve the problem]

In order to solve the above problems, the pneumatic tire of the present invention includes one bead portion in which a bead core is embedded, a sidewall portion continuous to the bead portion, and an overhang piece continuous to the sidewall portion, and is made of a polymer. a tire base consisting of a pair of semi-annular tire pieces integrally molded from a material and capable of forming a tread bottom by joining the overhanging pieces to each other, the tire base having a buffed outer surface in the tire radial direction of the tread bottom; and the tread. A cushion rubber layer made of unvulcanized rubber is placed on the outer surface of the bottom via an adhesive, a reinforcing layer made of reinforcing braai in which reinforcing cords are arranged in parallel and placed on the outer surface of the cushion rubber layer, and a semi-vulcanized or A green tire body made of already vulcanized rubber and having tread grooves formed on its outer surface and a tread rubber body overlaid on the reinforcing layer is vulcanized and integrated in a vulcanization mold.

C Effect] The green tire body of the pneumatic tire constructed in this way has an unvulcanized layer between the tire base made of a polymeric material and the semi-vulcanized or already vulcanized tread rubber body. Due to the presence of the cushion rubber layer and reinforcing layer, they can be fused together by vulcanization within the mold.

In addition, since the tread rubber body has tread grooves formed in advance on its outer surface, uneven pressure is not applied to the green tire during vulcanization molding, and therefore the tread gauge thickness is uniform and the tire is The shape can be maintained with high accuracy, the uniformity can be greatly improved, and the durability can be increased.

〔Example〕

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

FIG. 1 shows an embodiment of the pneumatic tire of the present invention,
Moreover, FIGS. 2 to 6 show the manufacturing process.

In FIG. 1, a pneumatic tire l has a green tire body 6 in which a reinforcing layer 3 and a tread rubber body 4 are stacked on a tire base 2.
are vulcanized and integrated using a vulcanization mold, and five layers 5 are interposed between the tire base 2 and the reinforcement M3.

The tire base 2 is provided with a thin tread bottom 11 for forming a tread portion via a sidewall portion lO extending radially outward from a bead portion 9 in which a bead core 8 is embedded. In addition, in this example, the tire base 2 includes a pair of left and right semi-annular tire pieces 12A and 12B that are discontinued near the tire equator in the tread bottom 11.
It is formed by joining the tips 13a, 13a of the forming overhang piece 13.

In this embodiment, the tip portions 13a, 13a are formed with a pair of left and right tire pieces 12A, 12B, and the tire pieces 12A, 128 are formed using, for example, a mold 15 shown in FIG. molded. Molding mold 1
5, tire pieces 12A and IB are formed by injecting a polymeric material from an injection port 19 into a hole pit 18 formed between an outer mold 16 and a movable inner mold 17. .

During casting, the bead core 8 coated with a vulcanized adhesive is placed on the bead portion 9 using an appropriate rubber spacer or the like. Further, as the polymer material, liquid polyurethane,
Although polyisoprene, polyester elastomer, etc. can be used, polyester elastomer is preferably used because it has excellent properties such as hardness and tensile strength after curing.

The tire pieces 12A, 12B formed in this way are combined with the tip portions 13a, 133 as described above, and then the joined portions are thermally welded. For thermal welding, high frequency welding a20 having an upper electrode 21 and a lower electrode 22, as shown in FIG. 4, can be suitably used. In addition to high-frequency welding, various methods may be used, such as using an electron beam or adhesive, or by melting the abutted tips 13a with a hot plate and pressing them together. Can be joined.

In addition, the outer surface in the tire radial direction of the tread bottom 11 formed by joining the overhanging pieces 13 and 13 to each other is buffed to improve the adhesion to the cushion rubber layer 5, which will be described later. At the same time, adhesive is applied. Note that various adhesives can be used as long as they bond between the polymeric material and the rubber during vulcanization; for example, isocyanate-based vulcanization adhesives, halogenated rubber-based vulcanization adhesives, etc. ,
It is also preferable to apply multiple coats.

Further, as described above, the cushion rubber ms, the reinforcing layer 3, and the tread rubber body 4 are sequentially placed on the outer surface of the tread bottom 11 to form the green tire body 6.

The cushion rubber layer 5 is relatively soft, for example JI
SAf2 degree 20-40 degree, PL Sabb 0.5-2
It consists of an unvulcanized rubber sheet of about M size.

The reinforcement M3 consists of at least one layer, in this example, one layer of reinforcing ply 3a, and in this example, the reinforcing ply 3a is a rubberized body or more, for example, 10 reinforcing cords are arranged in the tire circumferential direction. The reinforcing cord is formed by continuous spiral winding at an angle of 0 to 5 degrees, and the reinforcing cord is covered with an unvulcanized topping rubber. Note that the cushion rubber layer 5 may be made thick and a reinforcing cord may be embedded in the cushion rubber layer 5. In addition, the reinforcing cord may be wrapped continuously from one end of the ply to the other end, or it may be wrapped continuously from one end of the ply to the other end. Furthermore, the reinforcing layer 3 is made by embedding reinforcing cords in parallel at an angle of about 0 to 30" with respect to the tire equator in the topping rubber. It is also possible to wrap a band-like body into a cylindrical shape by overlapping its ends.

In addition to metal fiber cords such as steel, the reinforcing cords include aromatic polyamide, polyester, rayon,
An organic fiber cord such as nylon can be used, and when a steel cord is used, it is preferable to plate it with brass or the like.

In addition, when the reinforcing cord is wound spirally, the tread can be effectively reinforced with a hoop effect while reducing the number of windings, suppressing an excessive increase in tread rigidity and improving riding comfort. sell.

Further, the reinforcing layer preferably has a right cylindrical shape centered on the tire axis in an inflated state with standard internal pressure applied. In this case, it is possible to reduce disturbances occurring in the spiral cord arrangement and improve uniformity.

The tread rubber body 4 is made of the same material as the trend rubber of ordinary tires, and the tread surface, which is the outer surface, has tread grooves G formed in advance and has a shape similar to the finished shape of the tread portion. It is molded as a semi-vulcanized or already vulcanized rubber sheet.

Such a green tire body 6 is placed in a vulcanization mold shown in FIG. 6 in a V1 manner and vulcanized.

The vulcanization mold holder includes a fixed mold 23 and a movable mold 24 that forms a cavity 25 in the shape of the outer surface of the tire by contacting the fixed mold 23. It is provided with a bladder 27 which pushes up the inner cavity of the green tire body 6 and presses the outer circumferential surface against the inner surface of the cavity 25 while heating it by expanding due to injection.

Therefore, the green tire 6 is vulcanized while pressing its outer peripheral surface into the cavity 25 due to the expansion of the bladder 27, and the tire base 2, cushion rubber Jf15, supplementary rubber 94M3, and trend rubber body 4 are integrated into a fused shape. A pneumatic tire l is formed.

In addition, the green tire body 6 has tread grooves G formed in the tread rubber body 4 in advance.
During vulcanization, uniform pressure acts on the tread surface, preventing deformation of the tire base 2, uneven tread gauge thickness, etc., and greatly improving uniformity. 7 [Effects of the Invention] As described above, the pneumatic tire of the present invention uses semi-vulcanized or already vulcanized rubber with tread grooves formed on the outer surface in advance as the tread rubber body. It is possible to maintain a high degree of uniformity during this process, improving ride comfort and S@I stability, as well as increasing tread durability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a sectional view illustrating a mold for casting a semi-annular tire, FIG. 3 is a sectional view illustrating a semi-annular tire, and FIG. The figure is a sectional view illustrating the tire base, FIG. 5 is an exploded sectional view illustrating the constituent members of the green tire body, FIG. 6 is a sectional view illustrating the molding state in the mold, and FIGS. B) is a cross-sectional view showing the prior art. 2-Tire base, 3----Reinforcement layer, 4-
) Red rubber body, 5-cushion 1 rubber layer, raw tire body, ? --111 vulcanization mold, -8---
-Bead core, 9- ・Bead part,
10---Sidewall part, 11-) Red bottom part, 12A, 12B---・Tire piece. Patent Applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent Attorney Tadashi Naemura 2 @ 2B Figure 3 2A 4 Figure 4 1 l l
-11' I1■

Claims (1)

[Scope of Claims] 1. A bead part in which a bead core is embedded, a sidewall part continuous to the bead part, and an overhang piece continuous to the sidewall part, integrally molded from a polymeric material, and the overhang part A tire base consisting of a pair of semi-annular tire pieces that can form a tread bottom by joining the pieces to each other, the outer surface of the tread bottom in the tire radial direction being buffed; a cushion rubber layer made of unvulcanized rubber, a reinforcing layer made of reinforcing ply in which reinforcing cords are arranged in parallel and arranged on the outer surface of the cushion rubber layer, and an outer surface made of semi-vulcanized or already vulcanized rubber; A pneumatic tire formed by vulcanizing and integrating a green tire body, which includes a tread rubber body overlaid on the reinforcing layer, with tread grooves formed therein, in a vulcanization mold. 2. The pneumatic tire according to claim 1, wherein the reinforcing layer is made of a reinforcing ply in which one or more reinforcing cords are continuously wound in a spiral shape.