JPH1058554A - Method for molding tread ring and apparatus used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve higher order component of a lateral force variation and to improve high speed durability by winding organic fiber cords on an outer periphery of an unvulcanized green belt layer at a specific angle to a circumferential direction to form a green belt, and winding green tread rubber on an outer periphery of a belt band body. SOLUTION: A plurality of belt plies 6a, 6b are wound by altering directions of organic fiber cords to form a green belt layer 6. A green band 7 is formed by spirally winding band-like plies embedded in topping rubber at an angle of 0 to 5 deg. in a circumferential direction of a tire. The band 7 is formed on an outer periphery of the layer 6 to integrate the both, and the end of the layer 6 is bent radially inward together with the band 7. Then, a length Le of circulation of the end of a length of an inner peripheral surface of the belt layer circulated in one circle via an axial edge of the layer 6 is reduced shorter than a length Lc of a circumference at a center circulated in one cycle via an axial center, and tread rubber is laminated on its outer peripheral surface to be integrated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a belt forming drum having segments whose circumferential arrangement is substantially non-uniform to improve the higher-order component of uniformity, and to improve vibration and vibration based on resonance during running. The present invention relates to a method for forming a tread ring for a raw tire capable of forming a tire capable of suppressing noise and an apparatus used therefor.

[0002]

2. Description of the Related Art In a radial tire, a belt layer is disposed between a tread rubber and a carcass. In order to prevent lifting of the belt layer due to high-speed rotation, particularly at the edge, and to improve high-speed durability, A band is provided on the outer peripheral surface of the belt layer. In the tire forming step, such a belt layer and a band in a tire are formed in advance as an annular tread ring in which an unvulcanized green belt layer and a green band are wound together with a tread rubber and integrated.

In order to form such a tread ring, a belt forming drum having a plurality of radially movable segments whose outer surface forms a belt forming surface and which are arranged side by side in the circumferential direction is used for forming the tread ring. A raw belt ply, a raw band, and tread rubber are wound on the surface and integrated.

The tread ring is formed by inflating a raw tire body on a tire forming apparatus and pressing an outer peripheral surface thereof against an inner peripheral surface of a raw belt layer of the tread ring to form a raw tire. As shown in FIG. 15, the vulcanization mold MC is finished by inserting it into a molding cavity and vulcanizing and molding. The tire T has a smaller diameter at the end than at the center, and the belt layer 6F and the band 7F are similarly curved along the tire outer peripheral surface. Accordingly, the molding cavity surface of the vulcanizing mold for molding the molding is also curved Mp.

[0005] On the other hand, in order to simplify and facilitate the winding of the belt ply and to improve the productivity, the tread ring is formed into a straight cylindrical shape. In a green tire having a tread ring to be used, an end portion of the green tire, that is, a shoulder portion precedes an inner cavity surface, that is, a mold surface, by expansion, that is, shaping during vulcanization molding in a vulcanization mold. Easy to touch. As a result, the amount of rubber movement at the end becomes large, and even when the tire is rotated at high speed by use of the tire, the band tension at the shoulder tends to be not sufficiently large, preventing the lifting prevention effect, It also impairs the uniformity of the tire.

In addition, the uniformity of the tire includes the fourth-order to higher-order components in addition to the first-order component generated for each revolution, and when any one of these higher-order components is large, it is in the vehicle interior. It resonates with a high-frequency resonance point of the vehicle body such as a muffled sound and resonates with the vehicle, thereby impairing comfort. Therefore,
Improvements in tire uniformity are desired, and in particular, improvements in high-order RFV (lateral force variation) are required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of forming a tread ring and a device used for the same, which can improve the high-order component of RFV and improve the running comfort while improving the high-speed durability of the tire.

[0008]

SUMMARY OF THE INVENTION The present invention, which is the basis of the method of forming a tread ring, is directed to an enlarged and reduced diameter formed by a plurality of segments which are juxtaposed in a circumferential direction and are radially movable back and forth. Using a belt forming drum having a possible belt forming surface, forming a tread ring for a green tire by forming an unvulcanized green belt layer, a green band, and green tread rubber in an annular shape. A belt forming step of winding a plurality of belt plies of a high elasticity cord on the belt forming surface connecting the outer surfaces of the segments through the gap to form a raw belt layer; and The inner peripheral surface of the belt layer which makes one round through the edge of the raw belt layer by winding the organic fiber cord around the outer peripheral surface at an angle of 0 to 5 ° with respect to the circumferential direction to form a raw band. A center convex drum-shaped belt band in which the end circumference length Le is smaller than the center circumference length Lc that makes one round through the center part, and the length in the circumferential direction between the center lines of the segments is not uniform. Forming a tread ring by forming a tread ring by forming a tread ring by winding a raw tread rubber around an outer peripheral surface of a belt / band body and integrating them. Is the way.

By having a band, the high-speed performance of the tire can be improved, and by bending the tread ring, the uniformity of the tire is improved, and by making the center lines of the segments of the belt forming drum non-uniform, The higher-order RFV component can be improved and the driving comfort can be enhanced.

The present invention, which is the basis of a tread ring forming apparatus, has a belt forming surface which can be expanded and contracted and formed by a plurality of segments which are juxtaposed in a circumferential direction with a gap therebetween and are movable in a radial direction. An unvulcanized green belt layer using a belt forming drum, a green band, and a tread ring forming apparatus for forming a tread ring for a green tire obtained by laminating green tread rubber in an annular shape, wherein the belt forming The outer surface of the segment of the drum is a straight line parallel to the central axis in a cross section including the center axis of the belt forming drum, and the outer surface of the segment is a cross section perpendicular to the axis in an expanded state. The outer surface has a substantially arc shape having a radius substantially equal to the radius of the belt forming surface connecting the outer surface via the gap, and a circumferential arc length of the outer surface of the segment. When, in total a drum circumferential length M of the chord length C of the gap between the outer surface of the segment,
A drum end orbit length Me that makes one turn through the axial end of the belt forming drum is smaller than a drum center orbit length Mc that makes one turn through the axial center portion of the belt forming drum,
Moreover, the circumferential arc length S of the outer surface of the segment,
A tread ring forming apparatus characterized in that the length between the center lines of the segments is made non-uniform by using a plurality of types of belt forming surface forming elements that are the chord length C of the gap between the outer surfaces. It is.

[0011] Since the outer surface of the segment is a straight line parallel to the central axis in a cross section including the central axis of the belt forming drum, the raw belt layer can be stuck in a straight cylindrical shape to improve the formability. With the winding of the raw band, the raw belt layer can be curved together with the raw band so as to have a small end portion, thereby improving the uniformity of the tire. In addition, it is possible to make the interval between the center lines of the segments non-uniform with the winding of the raw band, reduce the high-order component of RFV, and improve the comfort in high-speed running.

Further, in the device invention, the segment may be:
It includes a segment whose axial length is longer than the belt ply and a plurality of different types of short segments having different short segments, and includes those in which the long segments are randomly arranged in the circumferential direction.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a step of forming a tread ring in which a raw belt layer, a raw band and a tread rubber layer are integrated by using a belt forming drum in a radial tire forming step. Is the same as the conventionally known radial tire molding process.

The method of the present invention includes a belt forming step, a band forming step, and a tread rubber attaching step, and the belt layer, band, and tread rubber used in each step are:
An unvulcanized green belt layer, green band, green tread rubber are used.

The tread ring 2 is used to form a raw tire 5 before vulcanization molding by combining with a raw tire body 4 having a carcass 3 as shown in FIG.

In the belt forming step, as shown in FIG. 2, a plurality of belt plies, in this example, two belt plies 6a and 6b are wound in different cord directions to form a raw belt layer 6. . The cord is 10 in the tire circumferential direction.
A highly elastic inorganic or organic fiber cord, such as steel, aromatic polyamide, or polyester, which is inclined at ４０40 ° is used.

As the belt plies 6a and 6b, well-known belt plies in which cords are arranged in parallel and which are obliquely cut and sequentially connected at non-cut parallel edges are used, and the ends of the belt plies are oblique. Is the hypotenuse along the code of

The belt plies 6a and 6b are wound around the belt forming surface 11 of the belt forming drum 10 so as to form a straight cylindrical raw belt layer 6 in this embodiment. To this end, the belt forming surface 11 is
In a cross section including the central axis 10X, the outer surface 14a of the segment 14 forming a straight line parallel to the central axis 10X is formed.
The cross section is a straight line composed of a straight line Y.

Further, a belt band body 8 shown in FIG. 3 is arranged on the outer peripheral surface of the green belt layer 6 by a green band forming step to form a belt band body 8. Further, the tread ring 2 is formed on the outer peripheral surface so that the tread rubber 9 is arranged and integrated in a tread rubber attaching step. FIG. 3 shows a state where the diameter of the belt forming surface 11 is reduced and the tread ring 2 is removed.

The raw band 7 is preferably made of a low elastic modulus organic fiber cord such as a nylon cord having good heat shrinkage. One or a plurality of cords are embedded in a topping rubber, and a band-like ply 7a is placed in the tire circumferential direction. It is formed by spirally winding at an angle of about 5 °. If it exceeds 5 °, the tightening force on the belt layer decreases.

The belt-like ply 7a may be wound once over the entire width of the outer peripheral surface of the raw belt layer 6, may be wound a plurality of times, may be applied only to the end, or the end may be added to the full-width wound body. It can also be formed. Further, only the cord can be wound.

By forming the raw band 7 on the outer peripheral surface of the raw belt layer 6 and integrating them, the end of the raw belt layer 6 is bent radially inward together with the raw band 7,
The end circumference length Le, which is the length of the inner peripheral surface of the belt layer that makes one round through the axial edge of the raw belt layer 6, is changed to the center circumference that makes one round through the tire equator, that is, the center part in the axial direction. Lc, and the belt / band body is a convex drum-shaped drum.

Further, the tread ring 2 in which the tread rubber 9 is adhered to the outer peripheral surface of the tread rubber 9 has a drum shape.
Also, as shown in FIG. 3, the tread ring 2 removed from the belt forming drum 10 by reducing the diameter of the belt forming surface 11 can be used as a tire forming device (not shown) while holding the outer peripheral surface.
The green tire body 4 illustrated in FIG. 1 is molded by pressing and integrating the outer circumferential surface of the green tire body 4 by swelling.

The raw tire 5 is loaded into a vulcanizing mold MC and vulcanized and molded as shown in FIG.
Becomes The belt band body 8 of the tread ring 2
Considering the expansion deformation in the vulcanizing mold MC, the dimensions of each part, so that the expected finished shape after the deformation,
The degree of curvature is set. Moreover, the deformation rate in the vulcanizing mold is
The central part of the raw belt layer 6 in comparison with the finished shape,
Set so that no significant difference occurs at the ends.

For this purpose, the belt band body 8 is
In a cross section including the center axis 10X of the belt forming drum 10, the raw belt layer 6 passes through the end of the inner peripheral surface of the belt layer 1
The end circumference length Le around which the belt is circulated is smaller than the finished end circumference length Lfe of the inner peripheral surface of the finished belt layer 6F of the finished tire T. Also, the central orbital length Lc that makes one revolution through the central portion of the inner peripheral surface of the belt layer 6 of the raw belt layer 6 is:
It is set to be smaller than the finished center circumference length Lfc at the center of the inner peripheral surface of the finished belt layer 6F.

Further, in order to reduce the high-order component of the RFV, the distance Q (shown in FIGS. 5 and 12) between the center lines 14X of the segments 14 forming the belt forming surface 11 is made non-uniform. . As a result, like the pitch variation method in the tread pattern,
Eliminating and dispersing the concentration in specific higher order components can improve the higher order components of the RFV.

Next, an apparatus for forming a tread ring of the present invention used in such a method will be described. The device 1
As shown in FIGS. 2 to 5, comprising a belt forming drum 10;
The belt forming drum 10 is mounted on a boss 21 fitted on a rotating shaft 20 by means of an expanding / reducing means 23 provided on the belt forming surface 1.
1, for example, 5 to 32 central axes 10X
, And in this example, twelve segments 14 are provided. As a result, the segments 14 are arranged side by side with a gap g in the circumferential direction, and the outer surface 14a forms the belt forming surface 11 that continues through the gap g. Thus, the outer surface 14a of the segment 14 and the gap g are both formed on the belt forming surface 1
1 is formed.

The expanding / contracting means 23 is fixed to the boss 21 via a fixing table, and is provided on the upper surface of a concentric annular mounting frame 24 spaced apart from the boss 21 by a linear actuator such as a hydraulic cylinder. 25, and a support plate 27 for mounting the segment 14, for example, at its rod end.
(As long as the support plate 27 can be moved in the radial direction, various types of linear actuators such as those using a link and those using screws) can be used.

As a result, the segment 14 can move in the radial direction as the linear actuator 25 expands and contracts. Support plate 2
7, the guide shafts 29, 29 extending from the support plate 27,
The rotation is stopped by loosely fitting the mounting frame 24 so as to be able to slide.

The guide shaft 29 has a flange 30 at its protruding end projecting downward from the mounting frame 24 to prevent it from falling off. For example, a horseshoe-shaped spacer 32 is provided between the upper surface of the flange 30 and the lower surface of the mounting frame 23. Intervene. Therefore, the linear actuator 25
As the guide shaft 29 rises, the spacer 32 is pressed between the mounting frame 24 and the flange 30, whereby the rising position of the support plate 27, that is, the segment 14 can be defined. Various spacers 32 having different thicknesses depending on the tire can be prepared.

As described above, the segment 14 is provided with the diameter increasing / reducing means 2.
As shown in FIG. 2, the belt forming surface 11 is moved outward in the radial direction by elongation of the belt forming surface 3 to form the belt forming surface 11 in an enlarged state. Diameter. Further, the diameter increasing / reducing means 23 may be formed at equal intervals in the circumferential direction or at irregular intervals.

Further, as shown in FIGS. 2 to 5 (only the arrangement of the segments 14... Is illustrated), the segment 14 is a long piece extending in the direction of the central axis 10X of the belt forming drum 10. The outer surface 14a forms a straight line Y parallel to the central axis 10X in a cross section including the central axis 10X of the belt forming drum 10.

The outer surface 14a of the segment 14 is shown in FIG.
As shown in the figure, in the cross section perpendicular to the axis in the expanded state, the outer surface 14a is formed in a substantially arc shape having a radius substantially equal to the radius R of the belt forming surface 11 formed by connecting the outer surfaces 14a via the gap g. The term “substantially” means that the radius length is adjusted according to the tire according to the thickness of the spacer 32, and includes a radius equal to the extent that the radius differs depending on the adjusted length, and an arc thereof.

Further, the segments 14 are segments 14A whose axial length is longer than the belt plies 6a, 6b.
And a plurality of different types of long and short segments 14B and 14C, which are shorter than that. In this example, the three types of long and short segments 14 are randomly arranged in the circumferential direction. In this example, the outer surface 14a of each segment 14 is a rectangle having the same circumferential arc length S, and the circumferential pitch P between the center lines 14X of the segments 14 (see FIG. 5) are arranged at the same position (360 ° / 12 = 30 °).

In the length between the same points on the circumference, the chord length between the same points is naturally smaller than the circumference, and therefore, the circumferential arc length S of the outer surface 14a of the segment 14 in the circumferential direction.
It is clear that, as the length occupied by the gap g increases, the drum circumference M decreases as the length of the drum circumference M, which is the sum of the chord length C of the gap g between the outer surfaces of the segments. It is.

The axial length of the belt ply 6
In this example including three different types of long and short segments, ie, a segment 14A longer than the segments 14a and 6b and segments 14B and 14C shorter than the segment 14A, the length range of the shortest segment 14C shown in FIG. That is, the end f
In the range between C, the raw belt layer 6 and the raw band 7 go around the outer surface 14a of all the segments 14A to 14C and the small gap g. On the other hand, as shown in FIG. 9, in the range between the longest segments 14A, which directly face each other in a range that extends beyond the discontinuous end f of the short segments 14B and (14C) in the axial direction, for example, as shown in FIG. The long gap g2 formed by skipping one of the short segments 14B and 14C (or skipping a plurality of short segments when sandwiching the plurality of short segments) forms the outer surface 14a, 1
4a.

Although not shown, even when the intermediate-length segment 14B sandwiches the shortest segment 14C between other segments, the segment f of the shortest segment 14C extends outward in the axial direction. A long gap g3 is formed in the range in which the segment 1 having the intermediate length is formed.
A longer gap g is formed between the longest segments 14A sandwiching the intermediate segment 4B.
It goes without saying that B is formed in a range beyond B in the axial direction.

As described above, the circumferential arc lengths S of the segments 14 are the same, and the circumferential pitch P between the center lines 14X of the segments 14 is the same (360 ° / 12 = 30). Despite the arrangement in (°), for example, three kinds of short and long segments 14 are randomly arranged in the circumferential direction, so that the chord length becomes smaller than the arc length. Since the gap g is longer at the end, the drum end circumference length Me is smaller than the drum intermediate circumference length Mc.

Further, in this embodiment, the segment 14 has a configuration in which the three types of long and short segments 14 are randomly arranged in the circumferential direction. As a result, the arc length S in the circumferential direction of the outer surface 14a of the segment is obtained. And the gap g between its outer surfaces
There are a plurality of types of the belt forming surface forming element a having a chord length C, and the length Q between the center lines 14X of the segments 14 is not uniform.

Here, in the present specification, "a plurality of types of belt forming surface forming elements a" means "the circumferential arc length S of the outer surface 14a of the segment forming the belt forming surface forming elements a, It means that one or both of the lengths of the gap g and the chord length C of the gap g are different in a plurality of types over the entire circumference of the belt forming surface 11.
By including 4A to 14C, a plurality of types can be included by changing the position in the width direction of the belt layer, that is, the position in the length direction of the segment.

Therefore, as in this example, each segment 14
Are the same (360 ° / 12 = 30 °) regardless of the same circumferential arc length S and the same circumferential pitch P between the center lines 14X of the segments 14. Since the three types of long and short segments 14 are arranged at random in the circumferential direction, as described above, the segments 14 are adjacent to each other in the central portion to produce a small gap g. At the end of the longest segment 14A, a long gap g is created by skipping one of the shorter segments, and the chord length C of the gap g changes in the longitudinal direction. There are a plurality of types of molding surface forming elements a. "

Further, in the present specification, "the distance Q between the center lines 14X of the segments is non-uniform" means that, as is clear from the above description, the circumferential arc length S of each segment 14 and the Even when the angular circumferential pitches P between the center lines 14X of the segments 14 are the same, the circumferential arc length S of the outer surface 14a of the segment, which is the belt forming surface forming element a, is equal to the circumferential arc length S. The center line 14 of the segment 14 with the chord length C of the gap g between its outer surfaces
The distance Q of the sum between X is made non-uniform, including the change in the length direction of the segments, by arranging the segments 14 of a plurality of lengths at random in the circumferential direction.

In the case shown in FIG. 5, the distance Q is the distance Q1 in the length range of the shortest segment 14C at the center. That is, the shortest segment 14C forms only the distance Q1 over the entire circumference.

Further, between the longest segments 14A, in the arrangement of FIG. 5, one shortest segment 14C or one intermediate length segment 14B is skipped, so that the chord length C2 due to the long gap g2 is reduced. , The shortest segment 14C which is larger than the central chord length C
Is a large distance Q2 outside the break fC or beyond the break fB of the middle segment 14B. Note that the axial range of the distance Q2 between the middle segment 14B and the shortest segment 14C is the cut end fC, but differs depending on whether it is the cut end fB.

As shown in FIG. 12, when the intermediate segment 14B is adjacent to the shortest segment 14C, it is located between the shortest segment 14C and the intermediate segment 14B, between the intermediate segments 14B, and between the intermediate segments 14B. Between the longest segment 14A or the longest segment 14A,
To Q4... Can be formed in various ranges in the axial direction.

As described above, “the segment center line 14X
The expression “the distance Q between them is not uniform” also includes a case where the distance Q is uneven at an axial position caused by the random arrangement of the long and short segments.

The belt forming surface 11 of the apparatus 1 has such a configuration. Therefore, first, the belt 32 is wound around the belt forming surface 11 having the desired size by selecting the spacer 32. In the belt forming step, the belt forming surface 11 is wound by not increasing the winding force. ,
As shown in FIGS. 7 and 10, the belt plies 6a and 6b are formed on the outer surface 14
A long gap g2 formed by breaking the short segments 14B and 14C in contact with a also passes through the entire surface in an arc shape and straddles between the outer surfaces 14a of the segments 14. As a result, the raw belt layer 6 has a straight cylindrical shape having substantially the same diameter at the middle and end positions in the length direction.

Next, in the band forming step, when the raw band 7 is formed by winding the organic fiber cord while applying tension at an angle of 0 to 5 ° with respect to the circumferential direction, the raw belt layer 6 7 tightened. As a result, as shown in FIGS. 8 and 11, the inner peripheral surface of the raw belt layer 6 is reduced in diameter so as to have the chord length C of the gap g within the range of the gap g. That is, the drum end orbit length Me passing through the axial end portion
Is generated along the drum forming surface 11 which is smaller than the drum center circling length Mc passing through the axial center portion of the belt forming drum.

That is, in the axially intermediate portion shown in FIGS.
The green belt layer 6 and the green band 7 circulate on the outer surfaces 14 a of all the segments 14. In contrast, FIGS.
At the end, as shown in FIG.
Segment 14A (14B) sandwiching (14C) in the circumferential direction
However, the short segments 14B, (14C) directly face each other within a range beyond the discontinuous ends fC, fB of the short segments 14B, (14C), and skip one short segment 14B (14C) (to sandwich a plurality of short segments). Due to the formation of the long gap g (sometimes a plurality of skips), the end circumference length Le of the inner circumferential surface of the belt layer is deformed to be smaller than the center circumference length Lc, and a drum-shaped belt band having a central convexity. The body 8 will be formed.

Furthermore, since the length between the center lines 14X of the segments 14 is not uniform, the periodicity of the length in the circumferential direction is reduced, thereby improving the high-order component of the RFV to reduce synchronous sound, vibration, and the like. It can be reduced.

FIGS. 13 and 14 show another example of the apparatus. In this example, the segment 14 changes the circumferential arc length S of the outer surface 14a by the arc length Se at the longitudinal edge.
Is smaller than the arc length Sc at the central portion, and has a substantially rhombic shape having a hypotenuse 14b that decreases the arc length S from the central portion toward both end edges. The segment 14 has two oblique sides 14b extending in the direction of the central axis 10X.
4c is connected via a triangular surface.

As a result of the outer surface 14a having a substantially rhombic shape, the gap g between the adjacent segments 14 is larger at the end than at the center, and the drum end circumference Me is larger than the drum center circumference Mc. Is also small.

Accordingly, in the band forming step, the drum end circling length Me passing through the axial end portion is made smaller than the drum center circling length Mc passing through the axial center portion of the belt forming drum. Cause deformation along the
By sticking the raw band 7, the end circumference length L of the inner peripheral surface of the belt layer passing through the end of the raw belt layer 6 together with the raw band 7
e is deformed to be smaller than the central orbital length Lc passing through the central portion, thereby forming a drum-shaped belt-and-belt body 8 having a convex shape.

The segment 14 has an axial length,
By randomly changing the arc length Se at the edge, the arc length Sc at the center, the angle α with respect to the length direction of the hypotenuse 14b, and the arrangement order, the arc length of the outer surface of the segment in the circumferential direction is changed. The length between the center lines of the segments is made non-uniform by using a plurality of types of belt forming surface forming elements a which are S and the chord length C of the gap between the outer surfaces thereof. Further, the circumferential pitch P itself on the angle of the center line 14X of the segment can be random, and other specifications such as the length of the segment and the angle α are as follows.
Both can be the same or different. Further, the axial center position of the segment can be displaced with respect to the tire equator, and the segment can be formed in various other shapes such as a spindle shape and a crescent shape.

The tread ring 2 forms a raw tire 5 by being combined with the raw tire body 4 and is vulcanized and molded in a vulcanizing mold MC to become a finished tire T.
Also, in the raw tire 5, the end circumference length Le of the inner peripheral surface of the belt layer is small and the tread ring 2 has a drum shape. To prevent collision with the finished tire T
In the band 7, the lifting by the high-speed rotation is effectively suppressed, the high-speed durability of the tire is improved, and
By improving the higher order components of the FV, it is possible to improve running comfort.

[0056]

Concrete Examples Ten tires of the example shown in Table 1 having a tire size of 225 / 50R16 were manufactured, and the components of the comparative tires (ten tires) at each order of RFV were compared. Tire size 1
It was mounted on a 6 × 7 rim, filled with an internal pressure of 2.0 kgf / cm ² , applied a load of 471 kg, and measured according to JASO-C607 “Automobile Tire Uniformity Test Method”. The results are shown in FIG. 16 for the example tire and in FIG. 17 for the comparative example tire. It can be seen that the example tires are excellent.

[0057]

[Table 1]

In each of the tires, the carcass was a polyester cord (size 1670 dtex / 2, the number of folds 50/5 cm, 2 plies), the belt layer was a steel cord (size 1 × 3), and the number of inserts was 40/5 cm, Plies (cord angles + 0 °, + 24 °, −24 °) were commonly used.

[0059]

As described above, the method for forming a tread ring according to the present invention involves bending the tread ring.
By preventing lifting and making the centers of the segments non-uniform, high-order RFV components can be improved and the comfort of high-speed running can be enhanced.

The apparatus used for forming the tread ring of the present invention can adhere a green belt layer in a straight cylindrical shape, thereby improving the formability and winding the green band together with the green band. The belt layer is curved so as to have a small end, so that the tread ring can be formed into a convex middle drum shape, and the raw band is wound, and the center of the segments is made non-uniform, so that a high-order RFV component is formed. And improve discomfort during high-speed driving.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a raw tire.

FIG. 2 is a cross-sectional view including a central axis illustrating an example of the device invention in a state where the diameter of a segment is expanded.

FIG. 3 is a cross-sectional view including a central axis illustrating the apparatus of FIG. 2 together with the segment in a state where the segment is reduced in diameter.

FIG. 4 is a partial cross-sectional view illustrating a 1/4 circle range perpendicular to the axis of the apparatus of FIG. 2;

FIG. 5 is a perspective view illustrating a segment.

FIG. 6 is a cross-sectional view of a central portion of a segment in a 1/4 circle range.

FIG. 7 is a cross-sectional view showing a state where a raw belt layer is wound around the segment of FIG. 6;

8 is a cross-sectional view showing a state in which a raw band is wound around the outer peripheral surface of the raw belt layer of FIG.

FIG. 9 is an end view of a 1/4 circle area of an end of a segment.

FIG. 10 is an end view showing a state where a raw belt layer is wound around the segment of FIG. 9;

11 is an end view showing a state in which a raw band is wound around the outer peripheral surface of the raw belt layer of FIG.

FIG. 12 is a plan view showing another example of a segment.

FIG. 13 is a plan view showing another example of the arrangement of segments.

FIG. 14 is an enlarged perspective view showing the segment.

FIG. 15 is a cross-sectional view illustrating vulcanization in a vulcanization mold.

FIG. 16 is a diagram illustrating components of each order of RFV of an example tire.

FIG. 17 is a diagram illustrating components of each order of RFV of a comparative example tire.

[Explanation of symbols]

 Reference Signs List 2 tread ring 4 raw tire main body 5 raw tire 6 raw belt layer 6a belt ply 6b belt ply 7 raw band 8 belt / band body 9 tread rubber 10 belt forming drum 10X central axis 11 belt forming surface 14 segment 14a outer surface 23 enlarging / reducing means

[Procedure amendment]

[Submission date] August 11, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0058

[Correction method] Change

[Correction contents]

In each of the tires, the carcass was a polyester cord (size 1670 dtex / 2), the number of folds was 50/5 cm, and two plies, and the belt layer was a steel cord (size 1 × 3) and the number of inserts was 40/5 cm . 2- ply ( cord angle + 24 °, -24 °)
One ply of nylon cord (cord angle 0 °) was commonly used.

Claims (5)

[Claims] An unvulcanized green sheet is formed by using a belt forming drum having a belt forming surface which can be enlarged and reduced in diameter and formed by a plurality of segments which are arranged side by side in a circumferential direction with a gap therebetween and are movable back and forth in a radial direction. A method for forming a tread ring for forming a tread ring for a green tire in which a belt layer, a green band, and a green tread rubber are annularly stacked, wherein the belt is formed by connecting outer surfaces of the segments through the gap. A belt forming step of winding a plurality of belt plies of a high elasticity cord on a surface to form a raw belt layer; To form a raw band, so that the end circumference length Le of the inner peripheral surface of the belt layer that makes one round through the end of the raw belt layer becomes the center circumference length Lc that makes one round through the center part. Smaller than A band forming process to form a belt-shaped belt-shaped belt with a convex center that makes the circumferential length between the center lines of the segments non-uniform, and a raw tread rubber wound around the outer peripheral surface of the band And forming a tread ring by forming the tread ring. 2. The tread ring according to claim 1, wherein said green band is formed by spirally winding a narrow band ply in which one or a plurality of organic fiber cords are embedded in topping rubber. Molding method. 3. The method according to claim 1, wherein the green belt layer has a right cylindrical shape. 4. An unvulcanized green belt using a belt-forming drum having a belt-forming surface which is formed by a plurality of segments which are juxtaposed in the circumferential direction with a gap in the circumferential direction and which are movable back and forth in the radial direction, and which have a belt-forming surface capable of expanding and contracting. A tread ring forming apparatus for forming a tread ring for a green tire formed by annularly stacking a layer, a raw band, and a raw tread rubber, wherein the belt forming drum segment has an outer surface formed by the belt forming. In a cross section including the center axis of the drum, a straight line parallel to the center axis is provided, and the outer surface of the segment is a belt forming surface that connects the outer surface of each segment through the gap in a cross section perpendicular to the axis in an expanded state. And a circular arc length S of the outer surface of the segment in the circumferential direction and a chord length C of the gap between the outer surfaces of the segments. In the drum circumference length M that is the sum, the drum end circumference length Me that makes one round through the axial end of the belt forming drum is changed by the drum center circumference that makes one round through the axial center part of the belt forming drum. Mc, and the arc length S in the circumferential direction of the outer surface of the segment,
A tread ring forming apparatus characterized in that the length between the center lines of the segments is made non-uniform by using a plurality of types of belt forming surface forming elements that are the chord length C of the gap between the outer surfaces. . 5. The segment includes a segment having an axial length longer than the belt ply and a plurality of different types of short segments having different short segments, and the long segments are randomly arranged in the circumferential direction. The tread ring forming apparatus according to claim 4, wherein a plurality of types of the belt forming surface forming elements are provided, and a length between center lines of the segments is made non-uniform.