JPH08309878A - Manufacture of solid tire - Google Patents

Abstract

PURPOSE: To shorten the vulcanization time and to improve the durability of a tire. CONSTITUTION: The rubber of the abraded tread surface of a used solid tire is cut off and buffed to form a core tire 6 having a tread buff surface 7. Besides, tread rubber 10 for forming a tread surface 4A is bonded to the tread buff surface 7 to be integrated by vulcanization, and the height TB in the radial direction between the smallest diameter position of the tread buff surface 7 and the bead bottom external edge E which is positioned at the external end in the tire axis direction in the bead bottom surface 2A of a vulcanized tire is made 75-95% of the height TH in the radial direction between the largest diameter position of the tread surface of the vulcanized tire and the bead bottom external edge E.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a solid pneumatic tire having excellent durability, which can be economically produced by vulcanization in a short time.

[0002]

2. Description of the Related Art A so-called pneumatic type solid tire mounted on a forklift truck or the like used for transportation in factories, warehouses, construction sites, etc. is subject to a large load and is easily damaged. For this reason, this type of solid tire is required to have various characteristics such as cut resistance and wear resistance as well as enhanced fitting force with the rim. In order to satisfy these requirements, conventionally, as shown in FIG. Part a
There is known a two-layer structure in which a short fiber cord-reinforced rubber or a hard rubber is used for the tread portion b and a rubber containing a so-called tread rubber having excellent abrasion resistance and crack resistance is used.

Since such a solid tire is heavy and solid, it has a high rolling resistance, and its reduction is required. In addition, since it has a larger rubber volume than a pneumatic tire of the same size, it is vulcanized. There is a problem that the time is long.

To solve the problem of increasing the vulcanization time, Japanese Patent Laid-Open No. 3-288631 discloses a method in which a waste tire is buffed, a rubber material is attached to the buff portion, and vulcanization is performed. This shows that the vulcanization time is shortened.

[0005]

However, it has been found that the one in which the rubber material is previously attached to the buff portion and vulcanized cannot sufficiently reduce the vulcanization time because the temperature of the attached rubber material is normal temperature. . Another problem is that the molding process for sticking the rubber material takes time, resulting in a decrease in productivity.

In order to solve such a problem of productivity deterioration, Japanese Patent Application Laid-Open No. 3-290234 discloses that a tire inner side or outer side is mounted in a mold and a rubber material is press-fitted into the mold. Shows a method capable of shortening the vulcanization time and increasing the productivity. This is JP-A-7-
It is also shown in Japanese Patent No. 32814.

By adopting such a method, the vulcanization time can be shortened and the productivity can be improved, but the position of the adhesive interface between the rubber material to be press-fitted and the tire member already vulcanized and molded is
Since the ratio to the cross-sectional height of the finished tire is not clearly defined, the adhesive interface is located near 60% of the cross-sectional height of the running solid tire where heat is most generated, and peeling damage occurs at this adhesive interface. Is often caused.

As a result of repeated research to solve this problem relating to durability, a reduced diameter used solid tire having a tire sectional height of 75% or more is used, and the height after buffing is 75%. By the above, it was found that the adhesive interface can be brought to a low temperature region where heat generation is relatively small and durability can be improved.

Further, in the tire having improved durability as described above, the tread rubber formed into a sheet shape which is wound around the tread buff surface and joined and integrated by vulcanization has a tread pattern formed by the pattern portion of the mold. When the rubber is molded, poor rubber flow is likely to occur.Therefore, the tread rubber is not molded in the molding process and injected into the mold via pressure to vulcanize, preventing appearance defects and We have also found that it is desirable in terms of simplification.

According to the present invention, a tread rubber is bonded and integrated by vulcanization to a tread buff surface of a core tire formed from a used solid tire having a reduced diameter, and a radial height TB of the tread buff surface is measured in a radial direction of the vulcanized tire. Height TH
It is an object of the present invention to provide a solid tire manufacturing method capable of shortening the vulcanization time, improving the productivity, and improving the durability on the basis of 75% or more.

[0011]

The present invention is directed to a bead bottom surface of a bead portion, a bead side surface of the bead portion extending radially outward from both sides of the bead bottom surface, and a sidewall portion extending radially outward from the bead side surface. A method for producing a solid tire having a reference tire outer surface consisting of a sidewall side surface and a tread surface of a tread portion that joins the outer end of the solid tire, the used solid tire having a reduced diameter. To prepare a core tire having a tread buff surface by removing the rubber on the worn tread surface of this used solid tire and buffing by removing the sidewall side surface, and, on the tread buff surface, the tread surface. A solid tire having a standard tire outer surface is manufactured by joining and integrating the tread rubber for forming by vulcanization. In addition, the radial height TB between the minimum diameter position of the tread buff surface and the bead bottom outer edge located at the tire axial outer end at the bead bottom surface of the vulcanized tire is defined as the tread surface of the vulcanized tire. Maximum diameter position,
75% of the radial height TH between the outer edge of the bead bottom
Above and above 95%.

The core tire is mounted on a vulcanizing mold having an inner cavity having a shape corresponding to the outer surface of the reference tire, and the tread rubber is injected into the mold under pressure and applied. It is desirable that the tread rubber be joined and integrated by vulcanization by being heated.

In the core tire, a used solid tire is buffed by removing the outer surface of the tire including the tread surface, and buffing is performed to form a tread buff surface, a sidewall buff surface, a bead side buff surface, and a bead bottom buff surface. At the same time, it is desirable that the tread rubber be joined and integrated with each buff surface by vulcanization.

[0014]

A tread rubber for forming a core tire having a tread buff surface by removing and buffing the worn tread surface rubber of a used solid tire having a reduced diameter, and for forming a tread surface on the tread buff surface. Are vulcanized and integrated. Therefore, it is possible to reuse the worn used tire, reduce the portion to be heated and vulcanized, shorten the vulcanization time, and improve the productivity.

The radial height TB of the tread buff surface is
After vulcanization 75% or more of the radial height TH of the tire and 9
Since the content is 5% or less, the adhesive interface between the tread rubber and the core tire can be brought to a low temperature region where heat generation is relatively small, peeling damage can be effectively prevented, and durability can be improved.

The radial height TB is 75% of the height TH.
If it is smaller than this, the adhesive interface between the tread rubber and the core tire comes to a high temperature range, peeling damage is likely to occur at the adhesive interface, and the amount of the tread rubber increases, which is not preferable for shortening the vulcanization time. The upper limit of the TB / TH ratio value is set to 0.95 in order to facilitate the formation of the tread pattern.

Since used tires are used as core tires, which are rubbers with low energy loss due to aging, heat generation can be suppressed, rolling resistance can be reduced, and riding comfort and handling can be reduced. It can improve stability.

Further, in the invention of claim 2, when the tread rubber is injected into the mold under pressure and heated to be integrally vulcanized with the core tire, the tread rubber is heated in advance. Therefore, the vulcanization time can be further shortened, the sheet-shaped tread rubber molding step can be eliminated, and the productivity can be improved.

Further, in the invention of claim 3, not only the tread buff surface but also the sidewall buff surface, the bead side buff surface and the bead bottom buff surface are formed on the core tire, and the tread rubber is bonded and integrated to each buff surface by vulcanization. When this is done, new rubber is attached to the outer surface of the bead portion, so that rim slip resistance can be maintained and the outer surface of the sidewall portion can be beautifully finished.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 2, the tread tire 1 manufactured by the manufacturing method of the present invention is located on the innermost side in the tire radial direction and has a bead bottom surface 2A of the bead portion 2 and radially outward from both sides of the bead bottom surface 2A. A base rubber layer 15 forming a bead side surface 2B of a bead portion 2 which extends, a side wall side surface 3A of a side wall portion 3 which is located radially outside thereof and extends radially outward from the bead side surface 2B.
Of the pneumatic type including an intermediate rubber layer 16 that forms a tread rubber layer 17 that forms a tread surface 4A of the tread portion 4 that is located on the outer side in the radial direction thereof and that joins the outer end of the sidewall side surface 3A. Tire outer surface 5
Have.

The base rubber layer 15 and the intermediate rubber layer 1
6 is a core tire 6 formed from a used solid tire having a reduced diameter.

The base rubber layer 15 is made of reinforcing rubber or hard rubber reinforced with short fiber cords and having a high compression modulus, and the intermediate rubber layer 16 forming the tread surface of the used solid tire has a JIS A hardness. Is, for example, 50
A rubber composition having excellent abrasion resistance, crack resistance, and grip performance, using a rubber of up to 70 degrees, was blended with a predetermined amount of carbon in a diene rubber such as natural rubber, isoprene rubber, or styrene-butadiene rubber. A so-called tread rubber compound is used.

For the tread rubber layer 17, the same tread rubber compound as the intermediate rubber layer 16 is used.

The worn tire tread surface rubber (intermediate rubber layer 16) of the used solid tire is removed by removing the height of the side wall side surface 3A and buffed to remove the core tire 6 having the tread buff surface 7. Form. Note that the method of removing rubber can employ so-called peeling, buffing, etc., in which rubber is cut using a blade, but in order to enhance the adhesiveness with the tread rubber layer 17, buffing is necessary at the end as described above. .

Then, the core tire 6 is mounted on a vulcanizing mold 9 having an inner cavity A having a shape corresponding to the reference tire outer surface 5 as shown in FIG. The radial height TB between the minimum diameter position of the tread buff surface 7 and the bead bottom outer edge E located at the tire axial outer end of the bead bottom surface 2A of the vulcanized tire is defined as the tread surface of the vulcanized tire. 75% or more and 95% or more of the radial height TH between the maximum diameter position and the bead bottom outer edge E
Hereinafter, in this example, it is set to 75%.

The radial height TB changes as the diameter between the bead bottom surfaces 2A is reduced by vulcanization. In FIG. 2, the radial height TB and the radial height TB of the core tire 6 before vulcanization are changed. For convenience, the height TH of the solid tire 1 obtained by sulfurization is shown in the same drawing.

A rubber paste is applied to the tread buff surface 7 to form the tread rubber layer 17 in the tread rubber 1.
The adhesive strength with 0 is improved.

The vulcanization mold 9 is composed of a lower mold 19 and an upper mold 20 having the tire equator of the solid tire 1 to be molded as a dividing surface.
The lower mold 19 and the upper mold 20 form a ring shape, and a mold body 21 in which the inner cavity A capable of molding the solid tire 1 is formed, and a fluid-like mold that forms the tread rubber layer 17 A pressure tool 24 is connected to the mold body 21 and presses the tread rubber 10 through a pressure-feeding piece 23 having a distributor 22 for passing the tread rubber 10 and branching the flow of the tread rubber 10. Get

An injection port 26 for guiding the tread rubber 10 to the inner cavity A is formed on the molding surface 25 of the inner cavity A, and the pressurizing tool 24 is a plunger pump in this embodiment. By pressing the tread rubber 10 filled in the cylinder 27, the tread rubber 10 is pressure-fed toward the distribution portion 22 and injected into the inner cavity A from the injection port 26.

The injected tread rubber 10 is preheated to 80 to 110 ° C., and further heating in the inner cavity A causes the tread buff surface 7 of the core tire 6 to be heated.
Then, a solid tire 1 is manufactured by vulcanization and joining with one body. Therefore, the vulcanization time can be greatly shortened, and the productivity can be improved in combination with the absence of the step of sticking the rubber material.

As the vulcanizing mold, as shown in FIG. 3, a solid tread rubber 10 may be press-fitted by lowering the upper mold 20 so as to be joined and integrated with the core tire 6 by vulcanization. It is also possible to use a so-called injection machine for injecting while kneading with a screw.

Further, as shown in FIG. 4, a used solid tire having a reduced diameter is buffed by removing the tire outer surface 5 including the tread surface thereof, and buffing the tread buff surface 7, sidewall buff surface 11, bead. It is also possible to form the core tire 6 having the side buff surface 12 and the bead bottom buff surface 13.

When the core tire 6 is mounted in the inner cavity A of the vulcanization mold 9, in order to hold the core tire 6, the molding surface 25 and the buff surfaces 11, 12, 13 are held.
The holding pins 29 ... Are provided at the position.

The holding pin 29 holds the sidewall buff surface 11 and the bead side buff surface 12 by a holding pin 29A.
... and a holding pin 29B that holds the bead bottom buff surface 13 ...
And

As shown in FIG. 5 (A), eight holding pins 29A project in a cylindrical shape from the molding surface 25 at substantially equal intervals in the circumferential direction, and the holding pins 29B are shown in FIG.
As shown in (B) and FIG. 5 (C), for example, eight pieces are provided at substantially equal intervals in the circumferential direction in the form of a convex arc that is long in the tire axial direction. Can be mounted easily and surely.

Further, the holding pins 29A and 29B and the core tire 6
The tightening margin (WP-WS) is set to 1 to 5 mm, more preferably 2 to 3 mm. When the tightening margin (WP-WS) is less than 1 mm, the core tire 6 is insufficiently held, and when the tightening margin (WP-WS) is greater than 5 mm, the amount by which the core tire 6 is pressed at the time of vulcanization becomes excessive, and the restoration after vulcanization is caused. Irregularities occur around the holding pins 29A and 29B, which hinders the appearance of the tire.

In this embodiment, the holding pins 29A, 29
The protrusion amount WP of B is 5 mm, and the distance WS between the core tire 6 and the molding surface 25 is 3 mm. Also holding pin 2
The diameter φ of 9A is set to 5 mm and the holding pin 29B
Has a radius of curvature R of 20 mm and a thickness T of 4 mm.

The distance WS is preferably 3 mm or more, more preferably 5 mm or more from the viewpoint of preventing the occurrence of a bare due to poor rubber flow.

[0039]

SPECIFIC EXAMPLES Solid tires were manufactured according to the specifications based on Table 1 (Examples 1 and 2 and Comparative Examples 1 to 4) and each performance was tested. The test method is as follows.

(1) Fitting force The peak value when the rim was pressed and fitted to the tire using the Amsler tester was adopted, and the peak value was expressed as an index with Comparative Example 3 being 100. The larger the value, the greater the fitting force.

(2) Rim slip resistance Each sample tire was mounted on a 1.5t forklift and 1t
The amount of slip between the rim and the tire was measured after the vehicle was turned in a figure 8 shape and traveled for 5 km.

(3) Drum damage test Each test tire was set on a rim of 5.00 s and 2180
The tires were pressed against the drum with a force of kgf and the tire damage was examined after running for 60 minutes at a speed of 15 km / h.

(4) Running test of actual vehicle Each test tire was mounted on a 1.5 ton forklift and 20,000
The wear condition of the tire after traveling for km was examined.

(5) Vulcanization time The time required for optimum vulcanization of each test tire is shown below.
The value is shown as an index when Comparative Example 3 is set to 100. The smaller the value, the shorter the vulcanization time.

(6) Rolling resistance Each sample tire was set on a rim of 5.00 s and 2180 kg.
The resistance value when the tire was pressed against the drum with the force of f and rotated at a speed of 15 km / h was shown as an index. Comparative Example 3 is 100
The smaller the value, the lower the rolling resistance.

[0046]

[Table 1]

As a result of the test, in the example, the vulcanization time was short, there was no problem in durability, and the rolling resistance was smaller than that of the comparative example 2 due to the large proportion of the core tire. Was confirmed.

[0048]

As described above, the solid tire manufacturing method of the present invention can shorten the vulcanization time, improve the productivity, and maintain the durability.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a solid tire manufactured by the manufacturing method of the present invention.

FIG. 3 is a cross-sectional view of a vulcanizing mold that schematically illustrates another embodiment of the present invention.

FIG. 4 is a sectional view showing another embodiment of the present invention.

5A and 5B are cross-sectional views showing holding pins for holding a core tire in a vulcanization mold, and FIG. 5C is a cross-sectional view taken along line XX of FIG.

FIG. 6 is a cross-sectional view showing a solid tire used in Comparative Example 2.

FIG. 7 is a cross-sectional view illustrating a solid tire.

[Explanation of symbols]

 2 bead part 2A bead bottom face 2B bead side face 3 side wall part 3A side wall side face 4 tread part 4A tread face 5 tire outer surface 6 core tire 7 tread buff face 9 vulcanization mold 10 tread rubber 11 side wall buff face 12 bead side buff face 13 Bead bottom buff surface A Lumen

Claims (3)

[Claims] 1. A bead bottom surface of a bead portion, a bead side surface of a bead portion that extends radially outward from both sides of the bead bottom surface, a sidewall side surface of a sidewall portion that extends radially outward from the bead side surface, and the outside thereof. A method for producing a solid tire having a standard tire outer surface consisting of a tread surface of a tread portion that joins the ends, a method for producing a solid tire having a reduced diameter, and preparing a used solid tire having a reduced diameter. The rubber on the worn tread surface of the tire is removed by buffing by removing the sidewall side surface to form a core tire having a tread buff surface, and the tread rubber for forming the tread surface is added to the tread buff surface. We manufacture solid tires that have a standard tire outer surface by being integrated by vulcanization, and The radial height TB between the minimum diameter position of the vulcanized surface and the bead bottom outer edge located at the tire axial outer end on the bead bottom surface of the vulcanized tire is defined as the tread surface maximum diameter position of the vulcanized tire. And a height TH in the radial direction between the outer edge of the bead bottom and 75% or more and 95% or less of the radial height TH. 2. The core tire is mounted on a vulcanizing mold having an inner cavity having a shape corresponding to the outer surface of the reference tire, and the tread rubber is injected into the mold under pressure. The method for producing a solid tire according to claim 1, wherein the tread rubber is joined and integrated by vulcanization by being heated. 3. The core tire, wherein the used solid tire is buffed by removing the outer surface of the tire including the tread surface, and buffing the tread buff surface, the sidewall buff surface, the bead side buff surface, and the bead bottom buff surface. The method for producing a solid tire according to claim 1 or 2, wherein the tread rubber is joined to and integrated with each buff surface by vulcanization while being formed.