JP2001179849A - Apparatus and method for manufacturing pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop an apparatus and a method for manufacturing a pneumatic tire for providing the tire having excellent uniformity by suppressing the unevenness of the circumferential thickness of a side tread by primary shaping (radial expansion). SOLUTION: The apparatus for manufacturing the pneumatic tire comprises an extrusion molding machine having a pair of molding rolls 1, 2 for forming a rubber 4 for a side tread by extruding a rubber 3 fed from a rubber kneading step. In this case, the rolls 1, 2 each has a truncated conical shape substantially gradually increasing in the diameter of the roll from one of the ends 1a, 2a toward one of the other ends 1b, 2b. The rolls 1, 2 are oppositely disposed at a predetermined interval at the ends 1a, 2a and the other ends 1b, 2b. The rubber 3 is rotated so as to be extruded in one direction. Thus, the rubber 4 for the side tread bend at a predetermined curvature is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for manufacturing a pneumatic tire, and more particularly, to extruding rubber sent from a rubber kneading step to form a rubber for a side tread. The present invention relates to improvement of a forming roll provided in an extruder.

[0002]

2. Description of the Related Art A rubber 106 used for a side tread of a tire is usually formed by an extruder using a die, a pair of cylindrical forming rolls 101 having the same roll diameter R as shown in FIG. The green case 105 (FIG. 4 (a)) is formed by extruding with a member 102, and pasted on a forming drum 103 together with other members such as an inner liner and a carcass ply 104 to form a green case 105 (FIG. 4A). As shown in b), a post-process such as primary shaping for radial expansion is generally performed.

[0003] Therefore, the side tread rubber 106
Is uniformly affixed in a cylindrical shape on the forming drum 103, but is unevenly stretched by radial expansion by primary shaping. As a result, the thickness (weight) of the rubber on the circumference is reduced. Variations are likely to occur,
It is not preferable because it causes deterioration of the uniformity of the tire.

In recent years, so-called high-flat tires having a low flatness ratio (ratio of a cross-sectional height to a cross-sectional width of a tire) of 45 or less have recently become a rare case in which a new vehicle is mounted in order to improve driving stability of the vehicle. , Repair tires are also increasing their market share, but with a relatively low cross-sectional height, the rigidity in the vertical direction tends to increase, However, this is particularly problematic because it greatly deteriorates the uniformity of the tire.

[0005] The inventors of the present invention have conducted studies to improve the uniformity of the tire by making the thickness of the side tread rubber uniform on the periphery after the primary shaping. .

That is, unlike the conventional tire manufacturing method shown in FIGS. 4 (a) and 4 (b), primary shaping is not performed after the side tread rubber is affixed in a cylindrical shape on a forming drum. After the primary shaping, the rubber for the side tread is stuck on the side peripheral surface of the green case.
It has been found that the side tread is not stretched unevenly by the radial expansion by the next shaping, the uniformity of the thickness (weight) of the rubber can be maintained on the circumference, and the uniformity of the tire can be improved.

However, the rubber for the side tread is
When pasting on the side peripheral surface of the green case after the next shaping, the side tread rubber formed by extruding straight by a conventional manufacturing method of extruding with a pair of cylindrical rolls having the same roll diameter is used to form a perforated disk. It is extremely difficult to apply the adhesive uniformly along the curvature of the side peripheral surface.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to extrude rubber sent from a rubber kneading process with a forming roll having an appropriate shape, so that the rubber is adhered to a side peripheral surface of a green case after primary shaping. An object of the present invention is to provide a manufacturing apparatus and a manufacturing method of a pneumatic tire excellent in tire uniformity by forming a rubber for a side tread curved at a predetermined curvature so that the tire can be easily attached.

[0009]

In order to achieve the above object, a pneumatic tire manufacturing apparatus according to the present invention comprises a pair of pneumatic tires for extruding rubber sent from a rubber kneading step to form side tread rubber. An extruder having a forming roll having a frusto-conical shape in which the roll diameter substantially increases from one end to the other end. Are arranged so as to face each other at a predetermined interval, and are rotated so that the rubber is extruded in one direction, thereby forming a side tread rubber curved at a predetermined curvature.

It is to be noted that the reason why the diameter of the forming roll is gradually increased substantially from one end to the other end is as follows.
This is because, in addition to the case where the contour of the surface of the forming roll when the forming roll is cut along a plane including the axis thereof is a straight line, the case where the contour is a curved shape having a somewhat convex curvature is also included.

The forming roll has a ratio of the roll diameter of the other end to the roll diameter of the other end of 1.05 or more, and the roll diameter of the other end to the roll diameter of the one end. It is preferable to form a side tread rubber having a thickness that varies in the width direction by increasing the ratio of the tires to a smaller or larger tire size and / or changing the roll interval in the axial direction.

Further, in the method for manufacturing a pneumatic tire according to the present invention, a step of forming a green case on a forming drum and performing a primary shaping, and a step of substantially reducing a roll diameter from one end to the other end. Has a truncated cone shape that gradually increases,
By rotating a pair of forming rolls in which one end portion and another end portion are arranged to face each other at a predetermined interval so that the rubber sent from the rubber kneading process is extruded in one direction, Affixing the formed side tread rubber having a curvature of a predetermined curvature to the side surface of the green case after the primary shaping, and assembling the BT band composed of the belt and the top tread formed in advance on the BT drum with the green case. And performing a secondary shaping to form a green tire.

In addition, the side tread rubber preferably has a curvature having a curvature corresponding to the side peripheral surface of the green case after the primary shaping.

[0014]

Next, a pneumatic tire according to the present invention will be described with reference to the drawings. FIG. 1 shows a typical forming roll provided in an extruder which is a part of a pneumatic tire manufacturing apparatus according to the present invention.
(A) shows a state in which the side tread rubber is extruded by the forming roll.

The forming rolls 1 and 2 shown in FIG. 1 extrude the rubber 3 sent from the rubber kneading step to form the side tread rubber 4.
Are arranged in pairs vertically.

The main feature of the present invention is to optimize the shape and arrangement of the forming rolls 1 and 2. More specifically, the forming rolls 1 and 2 are connected to one end 1a and one end 1a, respectively. The forming rolls 1 and 2 have one end portions 1a and 2a and the other end portions 1b and 2a. 2b are arranged facing each other at a predetermined interval.

By rotating the forming rolls 1 and 2 so that the rubber 3 sent from the rubber kneading step is extruded in one direction, the side tread rubber 4 curved at a predetermined curvature is formed. By adopting this configuration, the side tread rubber 4 is
It can be smoothly applied to the side peripheral surface 6 of the green case 5 after the next shaping, and as a result, the uniformity of the tire can be significantly improved.

Each forming roll 1 or 2 has one end portion.
Roll diameter R of 1a or 2a_1aOr R _2aAgainst other end
Roll diameter R of 1b or 2b_1bOr R_2bRatio X of 1.05
It is preferable that it is above. The ratio X is less than 1.05
And depending on the tire size, rubber 4 for side tread
With the peripheral surface 6 of the green case 5 after the primary shaping.
It may be difficult to paste in accordance with the curvature of
Because there is.

[0019] In FIG. 1, for convenience of explanation, one end portion 1a of the forming roll 1, roll diameter R _1a of 2a, the other end portion 1b for R _2a, 2b roll diameter R _1b of, R _2b Are greatly exaggerated. Although the gap between the molding rolls 1 and 2 is not shown in FIG. 1, a predetermined gap is actually provided corresponding to the thickness of the rubber to be extruded.

Further, the roll diameter R of one end 1a, 2a
Roll diameter R _1b of the other end 1b, 2b relative to _1a , R _2a
It is preferable that the ratio X of R _2b be large as the tire size is small. In other words, the smaller the tire size, the smaller the radius of curvature of the side peripheral surface of the green case after the primary shaping. Therefore, it is necessary to form a rubber for the side tread curved with a correspondingly large curvature. This is because it is useful to increase the ratio X.

In addition, when it is necessary to make the rubber thickness of the side tread different in the tire radial direction, by changing the axial distance between the forming rolls 1 and 2, the side tread having a different thickness in the width direction is provided. What is necessary is just to form a rubber for use and affix it to the side peripheral surface of the green case subjected to primary shaping.

The method of manufacturing a pneumatic tire according to the present invention is performed by using the manufacturing apparatus having the above-described structure. Specifically, first, an inner liner, a carcass ply, or the like is attached to a forming drum. After enlarging the forming drum, a bead ring and a bead filer are attached, and the end of the carcass ply is turned back to form the green case 5 and perform primary shaping.

Next, one end 1a, 2a is connected to the other end 1a.
b, 2b, the diameter of the roll substantially increases gradually, and a pair of one end portions 1a, 2a and the other end portions 1b, 2b are opposed to each other at a predetermined interval. The molding rolls 1 and 2 are transferred to the rubber 3 sent from the rubber kneading process.
Is rotated so as to be extruded in one direction, so that a side tread rubber 4 having a predetermined curvature formed at a predetermined peripheral surface of the green case 5 (see FIG. 2C).
, And a BT band formed of a belt and a top tread formed in advance on the BT drum and fitted to the green case 5.

Incidentally, the side tread rubber 4 has a curvature having a curvature corresponding to the side peripheral surface 6 of the green case 5 after the primary shaping, so that the side tread rubber 4 is uniformly and smoothly attached to the green case 5. It is preferable in that it can be performed.

Then, after performing a secondary shaping to form a green tire, a pneumatic tire is manufactured by performing a post-process such as vulcanization molding.

The above is only an example of the embodiment of the present invention, and various changes can be made within the scope of the claims.

[0027]

EXAMPLES Next, a pneumatic tire was trial-produced by a manufacturing apparatus and a manufacturing method according to the present invention, and a test for evaluating the uniformity of the tire was performed. This will be described below.

Example 1 The tire of Example 1 has a tire size of 245 / 45ZR.
17 is a pneumatic radial tire for a passenger car, wherein the roll diameters R _1a and R _2a of one end 1a and 2a of the forming rolls 1 and ₂ are both 300 mm, and the other ends 1b and 2 are
b, the roll diameters R _1b and R _2b are both 360 mm, the ratio X (R _1b / R _1a , R _2b / R _2a ) is both 1.2, and the side tread rubber 4 is formed by these forming rolls. And green case 5 after primary shaping
On the side peripheral surface 6. The structure and manufacturing method of the other tires were the same as those of a normal pneumatic radial tire for a passenger car. For comparison, as shown in FIG. 3, a cylindrical forming roll having the same roll diameter (30 mm) at one end and the other end (the ratio X
= 1.0) to form a side tread rubber 106 and affix it onto a forming drum 103 to form a green case 1
A pneumatic tire (Comparative Example 1) having the same size and structure as the tire of Example 1 was also manufactured by the conventional manufacturing method in which primary shaping was performed after performing the primary shaping.

Example 2 The tire of Example 2 is a pneumatic radial tire for small trucks having a tire size of 7.50R16, and has a roll diameter R at one end 1a, 2a of the forming rolls 1, 2. _1a and R _2a are both 200 mm, and the other ends 1b and 2
b, the roll diameters R _1b and R _2b are both 400 mm, the ratio X (R _1b / R _1a , R _2b / R _2a ) is both 2.0, and the side tread rubber 4 is formed by these forming rolls. And green case 5 after primary shaping
On the side peripheral surface 6. The structure and manufacturing method of the other tires were the same as those of a normal pneumatic radial tire for a passenger car. For comparison, as shown in FIG. 3, a cylindrical forming roll having the same roll diameter (30 mm) at one end and the other end (the ratio X
= 1.0) to form a side tread rubber 106 and affix it onto a forming drum 103 to form a green case 1
A pneumatic tire (Comparative Example 2) having the same size and structure as the tire of Example 2 was also manufactured by a conventional manufacturing method in which primary shaping was performed after performing the primary shaping.

Example 3 The tire of Example 3 is a pneumatic radial tire for trucks and buses having a tire size of 11R22.5,
Roll diameter R of one end 1a, 2a of forming rolls 1, 2
_1a and R _2a are both 300 mm, and the other ends 1b and 2b
Both the roll diameters R _1b and R _2b are 390 mm, their ratio X (R _1b / R _1a , R _2b / R _2a ) is both 1.3, and the side tread rubber 4 is formed by these forming rolls. Green case 5 after forming and primary shaping
On the side peripheral surface 6. The structure and manufacturing method of the other tires were the same as those of a normal pneumatic radial tire for a passenger car. For comparison, as shown in FIG. 3, a cylindrical forming roll having the same roll diameter (30 mm) at one end and the other end (the ratio X
= 1.0) to form a side tread rubber 106 and affix it onto a forming drum 103 to form a green case 1
A pneumatic tire (Comparative Example 3) having the same size and structure as the tire of Example 3 was also manufactured by a conventional manufacturing method in which primary shaping was performed after performing the primary shaping.

(Evaluation of Uniformity) The uniformity was measured by a uniformity measuring instrument and evaluated from the value of RFV. The evaluation results at that time are shown in Tables 1 to 3. Table 1 shows the evaluation results of Example 1 and Comparative Example 1 which are tires for passenger cars, Table 2 shows the evaluation results of Example 2 and Comparative Example 2 which are tires for light trucks, and Table 3 shows those for trucks and buses. The evaluation results of Example 3 and Comparative Example 3 which are tires are respectively shown, and the numerical values in Tables 1 to 3 are all shown as index ratios when Comparative Examples 1 to 3 are each set to 100. You can see that it is excellent in uniformity.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

From the evaluation results in Tables 1 to 3, Examples 1 to 3 are shown.
Are superior in uniformity to Comparative Examples 1 to 3, respectively.

[0036]

According to the present invention, it is possible to provide a pneumatic tire having excellent tire uniformity by suppressing the thickness of the side tread from becoming uneven on the periphery due to the primary shaping.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an arrangement of forming rolls 1 and 2 of an extruder which is a part of a pneumatic tire manufacturing apparatus according to the present invention.

2A is a diagram showing a state in which a side tread rubber 4 curved at a predetermined curvature is formed using the forming rolls 1 and 2 of FIG. 1, and FIG. It is a top view at the time of making the perforated disk 4 for side tread into a perforated disk shape, and (c) is a figure at the time of sticking the perforated disk 4 for side tread to the green case 5 which carried out primary shaping. is there.

FIG. 3 is a perspective view showing an arrangement state of forming rolls 101 and 102 of an extruder, which is a part of a conventional pneumatic tire manufacturing apparatus.

4A and 4B are views for explaining a conventional method of manufacturing a pneumatic tire. FIG. 4A shows a case where a green case 105 is formed by pasting a side tread rubber 106 on a forming drum 103 in a cylindrical shape. It shows the state,
(B) is a diagram showing a state when the green case 105 formed in (a) is subjected to primary shaping.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper forming roll 2 Lower forming roll 3 Rubber sent from rubber kneading process 4 Rubber for side tread 5 Green case 6 Side peripheral surface of green case 5

Claims (6)

[Claims] 1. A pneumatic tire manufacturing apparatus comprising: an extruder having a pair of forming rolls for extruding rubber sent from a rubber kneading step to form side tread rubber. Has a frusto-conical shape in which the roll diameter substantially gradually increases from one end to the other end.These forming rolls are arranged at predetermined intervals between one end and the other end. A pneumatic tire manufacturing apparatus characterized by forming a side tread rubber curved at a predetermined curvature by rotating the rubber so that the rubber is extruded in one direction. 2. The pneumatic tire manufacturing apparatus according to claim 1, wherein a ratio of a roll diameter of the other end to a roll diameter of the one end of the forming roll is 1.05 or more. 3. The pneumatic tire manufacturing apparatus according to claim 1, wherein the forming roll has a larger ratio of the roll diameter at one end to the roll diameter at the other end as the tire size is smaller. 4. A side tread rubber having a thickness different in a width direction by changing a roll interval in an axial direction of the forming roll.
The pneumatic tire manufacturing apparatus described in the above item. 5. A step of forming a green case on a forming drum and performing a first order, and having a truncated conical shape in which a roll diameter substantially gradually increases from one end to the other end. A pair of forming rolls, in which the ends of each other and the other ends are opposed to each other at a predetermined interval, are rotated so that the rubber sent from the rubber kneading process is extruded in one direction. Affixing the side tread rubber having the curvature of the predetermined curvature to the side surface of the green case after the primary shaping, and fitting a BT band composed of a belt and a top tread formed in advance on a BT drum to the green case; Performing a secondary shaping to form a green tire. A method for manufacturing a pneumatic tire, comprising: 6. The method for manufacturing a pneumatic tire according to claim 5, wherein the side tread rubber has a curvature having a curvature corresponding to a side peripheral surface of the green case after primary shaping.