JPH0443001B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a solid tire with improved riding comfort and rim slip resistance. [Background Art] Generally, solid tires, especially pneumatic solid tires that are mounted on rims and have the outer circumferential shape of a pneumatic tire, are used as tires for industrial vehicles such as forklifts at relatively low speeds and under high load conditions, and sometimes Since it is used for driving on rough roads strewn with nails, wood chips, rocks, etc., it is required to have various properties such as wear resistance and cut resistance, and to be firmly attached to the rim. Therefore, we use treaded rubber with excellent abrasion resistance and cut resistance on the contact surface side of the tire, and on the inside, we use base rubber with high compressive elasticity to increase the fitting pressure with the rim. The required properties have been shared by different rubbers. Conventionally, hard rubber mixed with a predetermined amount of short fiber cords obtained by cutting tire fabric made of organic fibers such as nylon or polyester into short lengths is often used as the base rubber. By using a large amount of this base rubber at a height ranging from 40 to 60% of the cross-sectional height of the tire, the tire base is strengthened and rim slips are prevented. However, in recent years, even in solid tires, there has been a demand for tires with good cushioning, flexibility, and a comfortable ride from the driver's health perspective. The tire has a three-layer structure with a soft rubber with good cushioning properties, and a rubber with excellent cut resistance and abrasion resistance, which improves the ride comfort of the tire. It is planned. However, as mentioned above, when the volume of the base decreases, the base portion becomes more easily deformed, which causes a new problem in that the fitting pressure between the tire and the rim decreases, causing rim slip. [Object of the Invention] The present invention is based on the fact that a cord reinforcing layer made of, for example, tire carcass cord, that is, tire fabric, is provided on the outer circumferential surface of a base rubber. The object of the present invention is to provide a solid tire that can maintain a high joint force and solve the above problems. [Disclosure of the Invention] The present invention provides a pneumatic type solid tire that is fitted onto a rim having a flange and has the outer peripheral shape of a pneumatic tire, in which a hard rubber having short fiber cords mixed in the rubber is used, and the flange of the rim is A cord made of a base rubber whose thickness is greater than the height of the base rubber, and plies arranged on the outer peripheral surface of the base rubber and made of tire fabric coated with rubber using organic fibers, which are laminated in the circumferential direction of the tire. The tread rubber includes a reinforcing layer and a tread rubber disposed on the outer circumferential surface of the cord reinforcing layer, and the tread rubber includes cushion rubber surrounding the outer circumferential surface of the cord reinforcing layer, and cap rubber disposed on the outer circumferential surface and forming the ground contact surface of the tire. This is a pneumatic type solid tire, which is composed of two layers, and is characterized in that the cushion rubber is a rubber whose hardness is lower than that of the cap rubber. An embodiment of the present invention will be described below based on the drawings. In the figure, a pneumatic type solid tire (hereinafter referred to as a solid tire) 1 has a flange 7
The solid tire 1 is fitted onto a rim 6 having an outer peripheral shape of a pneumatic tire, and the solid tire 1 includes a base rubber 4 fitted to the rim 6, a cord reinforcing layer 3 disposed on the outer peripheral surface of the rubber base 4, It is a three-layer body consisting of a tread rubber 5 disposed on its outer circumference, and the tread rubber 5 is formed as a two-layer body consisting of a cushion rubber 5B and a cap rubber 5A on its outer circumference. The base rubber 4 is an organic fiber cord for tires, a short fiber cord obtained by cutting tire fabric into a length of 5 to 30 mm, preferably 5 to 10 mm.
We use hard rubber with a JIS hardness of 75 degrees or higher, which is reinforced by mixing 30 to 40 percent by weight into the rubber. For example, a carcass cord can be used as the tire fabric, and the short fiber cord is an organic fiber such as nylon or polyester. By using a rubber composition mixed with these short fiber cords for the base rubber 4, the base rubber 4
The rigidity and compression modulus of the rim 6 are improved, the fitting pressure with the rim 6 is increased, and the high fitting pressure is maintained for a long time. Furthermore, the thickness T of the base rubber 4 is greater than the height H of the flange 7 of the rim 6, and the cross-sectional height of the tire is
It forms in 15-50% of TH. However, if the base rubber height T is as low as 15 to 30% of the tire cross-sectional height TH, the base rubber 4 is likely to deform in the tire radial direction when high torque is applied to the tire, which may cause rim slip. be. In order to prevent this deformation, a cord reinforcing layer 3 is provided on the outer peripheral surface of the base rubber 4. This cord reinforcing layer 3 is made of a tire fabric for a tire carcass in which long cords made of organic fibers such as nylon, polyester, rayon, aromatic polyamide, etc. are arranged in parallel and have a 30% modulus of 40 to 150 kg/ cm ² rubber coated ply, the cord is wrapped circumferentially one or more times, preferably continuously, parallel to or at a shallow angle to the tire equator. Become. Note that plies having one circumferential length may be sequentially laminated multiple times in the circumferential direction. Also, the thickness TC of the cord reinforcement layer 3 is the tire cross-sectional height.
It should be 10-20% of TH. By providing the cord reinforcing layer 3 in which the tire fabric made of organic fibers is wrapped around the outside of the base rubber 4 in this way, the tire fabric made of organic fibers is thermally contracted due to the heat generated during driving, and the cord reinforcing layer 3 presses the base rubber 4 toward the rim 6, and the rim 6 and the base rubber 4 can be firmly tightened. The tread rubber 5 has both sides in the axial direction of the tire radially inward, covers both sides of the cord reinforcing layer 3, and covers both sides of the base rubber 4. This base rubber 5 is formed as a two-layer body consisting of a cushion rubber 5B with excellent cushioning properties on the inside in the direction of the tire half shape, and a cap rubber 5A made of cut-resistant and abrasion-resistant rubber disposed on the outer peripheral surface of the cushion rubber 5B. . The cushion rubber 5B is a soft rubber with a JIS hardness of 40 to 65 degrees, and its thickness TB is the tire cross-sectional height TH.
The range shall be 25% to 50%. Also, as a soft rubber,
A rubber compound in which 30 to 50 PHR of carbon black is blended with natural rubber or butadiene rubber is preferably used. The cap rubber 5A uses rubber with a JIS hardness of about 60 to 75 degrees, and has improved wear resistance and cut resistance. If the JIS hardness is less than 60 degrees, the cut resistance and abrasion resistance will be poor, and if the JIS hardness exceeds 75 degrees, the grip performance will deteriorate. In this way, the cushion rubber 5B has a lower hardness than the cap rubber 5A, and has improved cushioning properties and ride comfort. [Effects of the Invention] As described above, the solid tire of the present invention is constructed by using a cord reinforcing layer laminated with one or more plies made by coating tire fabric with rubber on the outer peripheral surface of the base rubber. The rubber can be firmly tightened, preventing rim slippage due to long-term driving, and the rim and base rubber can be firmly tightened by utilizing the heat contraction of the organic fiber cord that normally occurs due to heat generated during driving. Cushion rubber with excellent cushioning properties is arranged on the outer circumferential surface of the cord reinforcing layer, thereby providing a solid tire with good riding comfort and excellent rim slip resistance. [Example] A solid tire with a tire size of 7.00-12 was used as the first
An experimental product and a comparative product were manufactured according to the specifications shown in the table, and the rim fitting force was measured. The results are shown in the table. From the table, it is clear that the rim fitting force of the example products of the present invention is improved. 【table】

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the right half of an embodiment of the solid tire of the present invention. 1...Solid tire, 3...Cord reinforcement layer,
4...Base rubber, 5...Tread rubber, 5a...
...Cap rubber, 5B...Cushion rubber.

Claims (1)

[Scope of Claims] 1. A pneumatic solid tire that is fitted onto a rim with a flange and has the outer circumferential shape of a pneumatic tire, using hard rubber in which short fiber cords are mixed into the rubber, and the height of the flange of the rim. A cord reinforcing layer consisting of a thicker base rubber, and plies arranged on the outer circumferential surface of the base rubber and made of tire fabric coated with rubber using organic fibers and laminated in the circumferential direction of the tire. and a tread rubber disposed on the outer circumferential surface of the cord reinforcing layer, the tread rubber comprising cushion rubber surrounding the outer circumferential surface of the cord reinforcing layer, and cap rubber disposed on the outer circumferential surface and forming the contact surface of the tire. A pneumatic type solid tire consisting of two layers, and characterized in that the cushion rubber uses rubber whose hardness is lower than that of the cap rubber.