JPH0732814A - Manufacture of solid tire - Google Patents

Abstract

PURPOSE:To improve the circularity and W of a tire, compared with those of the base rubber layer formed with a conventional coil structure, by previously forming the base rubber layer into a ring-shaped structure, arranging a tread rubber layer radially outside of the ring-shaped structure and then vulcanizing these into one unit. CONSTITUTION:A solid tire 1 has a base rubber layer formed of reinforcing rubber or hard rubber covered with short fiber cords and arranged radially most-inside and a tread rubber layer 3 arranged radially outside. In this case, when the tire 1 is manufactured, the base rubber layer 2 is previously formed in a ring-shaped structure 5 by compression molding or vulcanization molding of sheet or block shaped rubber B in both special upper and lower molds d1, d2. The tread rubber layer 3 is arranged radially outside of the ring-shaped structure 5 to form a raw rubber tire. Then, the ring-shaped structure 5 and the tread rubber layer 3 are A vulcanized in a vulcanizing mold into one unit to complete a tire product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid tire manufacturing method capable of efficiently producing a highly uniform solid tire.

[0002]

2. Description of the Related Art Generally, solid tires have a load bearing capacity,
In addition to being required to have excellent performance such as low heat generation and uniformity of durability, low selling price is also an important factor, and cost reduction is required. On the other hand, the pneumatic solid tire has a base portion a as shown in FIG.
A reinforcing rubber or a hard rubber having a high compression elastic modulus by mixing a predetermined amount of short fiber cord is used for the tread portion b.
There is known a two-layer structure using a rubber having a JIS A hardness of 60 to 70 ° and being softer than the base portion a. Further, in recent years, as a base portion a, as shown in FIG. 6, after rubber with fibers is applied to a crusher roll, it is rolled into a sheet shape, for example, a sheet s having a thickness of 5 mm in a calendering process and wound on a forming homer. A coil is used.

Similarly, the tread portion b has a thickness of 5 mm, for example.
The rolled sheet-like body s is molded on a molding home using a coil-shaped body wound on the base rubber layer a as shown in FIG. 7, and this is pressed in a mold. It is integrally vulcanized, and after vulcanization it is finished to a specified size.

[0004]

However, in such a coil shape, a step t occurs at the beginning and end of the sheet when the sheet is wound around the homer.
In addition, a tire is formed by rolling a rubber sheet of the tread portion b on a base rubber made of a coil body having the step t to form a raw tire and vulcanizing the tire. Means that the step difference t of the base rubber having high hardness remains, and the vertical rigidity of the tire is partially different. Tires with uneven rigidity like this
When traveling, there is a problem that the vibration of the car becomes severe.

The tread rubber portion b is also formed by winding a sheet-like body into a coil and then moving it into a mold to heat it.
In the conventional method of integrally vulcanizing by applying pressure, it takes time and effort to wind the sheet-shaped body and form the coil-shaped body, which impairs productivity. Moreover, the scorch of the rolled sheet s is present in the coil-shaped body and induces delamination, thereby lowering its durability. Furthermore, the green tire molded as described above is put into a predetermined mold and is vulcanized by the vulcanization heat and pressure transmitted from the mold, but it is heated from the bladder inside the tire like a pneumatic tire. It is impossible to do because it is a solid tire. Therefore, there is a problem that vulcanization for a long time is required, the rotating efficiency of the mold is poor, and the productivity is low. In order to shorten the vulcanization time, it is possible to further raise the preheating temperature in the preheat treatment that is performed prior to vulcanization of the sheet-shaped material, but raising the preheating temperature above the current temperature causes deterioration of the rubber. The above high preheating temperature cannot be applied, and therefore the vulcanization time cannot be shortened.

[0006] The present invention provides a method for producing a solid tire which can prevent vibration from occurring during running by shortening the vulcanization time during production by increasing the productivity by uniformly and uniformly producing the tire. Has an aim.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a base rubber layer made of a reinforcing rubber or hard rubber which is located on the innermost side in the radial direction of a tire and is reinforced with short fiber cords, and a tread rubber which is located on the outer side in the radial direction. A method for producing a solid tire comprising a layer, wherein the base rubber layer is a sheet-shaped or block-shaped reinforcing rubber or hard rubber previously compression-molded or vulcanized in a base-rubber molding die. It is a molded ring-shaped body, a tread rubber layer is arranged on the outside in the radial direction to form a raw tire, and the completed tire is formed by vulcanizing and integrating the ring-shaped body and the tread rubber layer in a vulcanization mold. And a method for manufacturing a solid tire.

[0008]

The base rubber layer uses a ring-shaped body obtained by previously compression-molding or vulcanizing a short-fiber-containing rubber composition or hard rubber composition processed into a sheet or block in a base rubber molding die. To manufacture. Therefore, as shown in FIGS. 6 and 7, unlike the one manufactured by the conventional method using the coil body formed by winding the sheet s in a coil shape, a step is not generated at the beginning and the end of winding, The uniformity of the completed solid tire is enhanced, and the roundness of the tire is improved by about 5% as compared with the conventional method shown in FIG.

Further, since the tread rubber layer is formed by pressurizing and injecting the rubber composition into the vulcanization mold outside the radial direction of the ring-shaped body, as shown in FIG. Molding is easier and can be shortened by at least 20 to 30% for vulcanization molding, which improves the working rotation efficiency of the mold and reduces manufacturing costs, and also reduces thermal expansion during vulcanization and trim. It can prevent appearance defects such as cracks and improve the appearance.

By deforming the annular body in the radial direction of the tire and reducing the risk of bubbles occurring in the tread rubber layer, the tire is highly uniform and uniform, that is, the rigidity is uniform on the circumference of the tire. Solid tires can be provided. Therefore, by using the manufacturing method according to the present invention, the solid tire can greatly reduce vibration during running.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. A solid tire 1 manufactured by the manufacturing method of the present invention includes a base rubber layer 2 located on the innermost side in the tire radial direction and a tread rubber layer 3 located on the outer side in the radial direction as shown in FIG.

The base rubber layer 2 is a reinforcing rubber or a hard rubber reinforced with short fiber cords and having a high compression elastic modulus, which is previously formed into a sheet shape or a block shape as shown in FIG. It is formed by using a raw ring-shaped body 5 or a vulcanized ring-shaped body 5 which has been charged into d2 and compression-molded by a base rubber molding die which is molded by pressing the upper die d1.

As the short fiber cord, polyester,
In addition to organic fiber cords such as nylon and rayon, inorganic fiber cords such as glass and steel, preferably 10 mm
The following pieces are used. In order to reduce the product cost, a case material used for a pneumatic tire or a case material collected from a waste tire may be cut into a predetermined length with a crusher mill or the like.

The thickness TB of the base rubber layer 2 is in the range of 20 to 70%, preferably 25 to 45% of the tire cross section height TH. If the value is less than 20%, the fitting pressure with the rim cannot be maintained, while if it exceeds 70%, the cushioning property is significantly deteriorated. The short fiber cord is mixed in an amount of 40 parts by weight or less, preferably 5 to 35 parts by weight, based on 100 parts by weight of rubber.

The tread rubber layer 3 uses a rubber having a JISA hardness of, for example, 50 to 70 degrees, and has a rubber composition excellent in abrasion resistance, crack resistance and grip, such as natural rubber, isoprene rubber and styrene. A so-called tread rubber compound in which a predetermined amount of carbon is compounded in a diene rubber such as butadiene rubber is used. If the JIS A hardness is less than 50HS, the abrasion resistance is poor and the JIS hardness is 70HS.
If it exceeds, the grip performance will deteriorate. The thickness TC of the tread rubber layer 3 is in the range of 30 to 80% of the tire cross-section height TH. The thickness TC of the tread rubber layer 3 correlates with the service life of the solid tire 1 due to wear and increases the thickness. And the service life can be extended.

Next, a method for producing a solid tire (hereinafter referred to as a production method) will be described. As the base rubber layer 2, a preliminarily molded annular body 5 is used. The ring-shaped body 5 is made of, for example, a rubber composition for a base rubber, and, if necessary, rubber mixed with short fibers as described above is used as a block B in each cross-sectional shape.
As shown in FIG. 2, this is formed into a lower mold d2 of a base rubber molding die, and a ring-shaped body 5 as shown in FIG. To do.

The ring-shaped body 5 is set in a molding space 11 of a vulcanizing mold 10 as shown in FIG. 1, for example, and a rubber composition for forming the tread rubber layer 3 is injected into the molding space 11 to produce a raw material. The tire is molded.

The vulcanizing mold 10 includes a lower mold 13 and an upper mold 14 having a tire equator C of the solid tire 1 to be molded as a dividing surface.
And a mold body 15 in which a ring-shaped structure is formed by superposing the lower mold 13 and the upper mold 14 and in which the molding space 11 for molding the solid tire 1 is formed, and a tread on the mold body 15. The rubber composition 7 is connected to the mold body 15 via a pressure-feeding piece 17 through which the fluid rubber composition 7 forming the rubber layer 3 passes and which branches the flow of the composition. A pressure tool 19 for pressurizing

The molding space 11 has a molding surface 21 formed in substantially the same shape as the outer surface of the solid tire 1, and the ring-shaped body 5 forming the base rubber layer 2 is loaded on the radial center side thereof. An injection port 12 for guiding the rubber composition 7 into the molding space 11 is formed on the molding surface 21.

The pressurizing tool 19 is a plunger pump in this embodiment, and by pressing the rubber composition 7 filled in the cylinder 23, the rubber composition 7 is pressure-fed toward the distributor 16. It

As a result, the rubber composition 7 loaded in the molding space 11 contacts the ring-shaped body 5 evenly when it is loaded, so that the ring-shaped body 5 is radially oriented as shown in FIG. There is no significant deformation. Further, since the rubber composition 7 is in a more fluidized state, the tread rubber layer 3 formed by the rubber composition 7 is free of bubbles and the like, and the homogeneous solid tire 1 is completed.

Further, as described above, the rubber composition 7 flows into the molding space at a higher temperature than in the conventional method, so that the thermal expansion during vulcanization is small, the occurrence of trim cracks is reduced, the defect rate is reduced and the appearance is reduced. It is possible to improve.

The injection port may be formed with several small gaps in the circumferential direction, and a method of providing the injection port in the upper mold and press-fitting it into the molding space from above can be adopted, but it has been completed. In order to improve the uniformity and homogeneity of the tire, it is most preferable to provide an injection port on the tire equator C as shown in FIG. 1 and circulate endlessly.

[0024]

As described above, the method for producing a solid tire according to the present invention comprises a ring-shaped rubber composition for base rubber, which is sheet-shaped or block-shaped, which has been previously compression-molded or vulcanized by a base-rubber molding die. The base rubber layer is formed using a body and the tread rubber layer is a method of forming a finished tire by pressurizing and injecting a rubber composition to the outside of the annular body, so that the roundness of the tire is improved, In addition to providing a solid tire with high uniformity and homogeneity, the vulcanization time and molding time can be shortened, the operation of the vulcanization mold can be increased, the production cost can be reduced, and the internal temperature during molding becomes high. The thermal expansion during vulcanization is small and the risk of cracking is reduced and the appearance can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an example of a mold used in a manufacturing method of the present invention.

FIG. 2 is a cross-sectional view schematically showing a base rubber molding die.

FIG. 3 is a cross-sectional view showing a solid tire manufactured by the manufacturing method of the present invention.

FIG. 4 is a perspective view showing a ring-shaped body.

FIG. 5 is a cross-sectional view showing a solid tire manufactured by a conventional manufacturing method.

FIG. 6 is a cross-sectional view showing a method for manufacturing the base rubber layer.

FIG. 7 is a cross-sectional view showing a method for manufacturing the solid tire.

[Explanation of symbols]

 2 base rubber layer 3 tread rubber layer 5 ring-shaped body 7 rubber composition 10 vulcanizing mold 12 injection port 19 pressurizing tool 21A peripheral surface part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29K 105: 08 B29L 30:00

Claims (1)

[Claims] 1. A solid tire comprising a base rubber layer, which is located on the innermost side in the radial direction of the tire and is made of a reinforcing rubber or a hard rubber reinforced with short fiber cords, and a tread rubber layer, which is located on the outer side in the radial direction. In the method for producing a solid tire, the base rubber layer is a ring-shaped body obtained by previously compression-molding or vulcanizing the sheet-shaped or block-shaped reinforcing rubber or hard rubber in a base rubber molding die. A solid tire characterized by forming a green tire by arranging a tread rubber layer on the outer side in the radial direction, and forming a finished tire by vulcanizing and integrating the annular body and the tread rubber layer in a vulcanization mold. Manufacturing method.