JP6825268B2 - Tire vulcanization method - Google Patents

Description

The present invention relates to a method for vulcanizing a tire.

The tire is obtained by vulcanizing a low cover (raw tire) in the vulcanization process. In the vulcanization step, the low cover is vulcanized in the cavity formed by the cavity surface of the mold and the bladder. In this vulcanization step, if air remains between the bladder and the low cover, bears or the like are generated on the tire surface. This residual air impairs the appearance quality of the tire.

Japanese Unexamined Patent Publication No. 2016-16642 discloses a vulcanization step in which the adhesion between the bladder and the low cover is improved. In this vulcanization step, a bladder receiving surface is formed on the bead ring of the mold. A stepped surface is provided on the bladder receiving surface. An air suction hole is provided on this stepped surface. In this vulcanization step, as the bladder expands, the residual air between the bladder and the low cover is sucked through the suction holes. In this vulcanization step, it is suppressed that air remains between the bladder and the low cover.

Japanese Unexamined Patent Publication No. 2016-16642

In the vulcanization step of JP-A-2016-16642, it is necessary to prepare a mold having a bead receiving surface provided with a step. In this vulcanization step, it is necessary to suck air from the suction holes.

An object of the present invention is to provide a method for vulcanizing a tire that can reduce residual air easily and without lowering productivity.

In the tire vulcanization method according to the present invention, the low cover is vulcanized in a mold to obtain a tire. This vulcanization method includes a charging step of charging the low cover into the mold and a shaping step of shaping the low cover with a bladder. In the loading step, the paddle is locked to the bead portion of the low cover, and the low cover is set in the mold. In the shaping step, the bladder expands with the paddle locked to the bead portion of the low cover. After the bladder comes into contact with the low cover, the paddle is removed from the low cover.

In the shaping step, when the low cover is locked to the paddle, the height from the lower clamp end to the upper clamp end of the bladder is defined as Hb, and the height from the lower clamp end of the bladder to the bead portion of the low cover. Let the height of be Hr. At this time, preferably, the difference Hs obtained by subtracting the height Hr from this height Hb is 0 (mm) or more and 10 (mm) or less.

Preferably, the paddle includes a main body extending in the vertical direction and a tip portion extending downward from the tip of the main body so as to be inclined from the inside to the outside in the radial direction. The bending angle between the main body and the tip portion is 90 (°) or more and 150 (°) or less.

Preferably, the length of the tip portion is 5 (mm) or more and 10 (mm) or less.

Preferably, the thickness of the tip portion is 2 (mm) or more.

In the tire vulcanization method according to the present invention, a conventional mold can be used as it is. This vulcanization method can reduce the residual air without providing a special residual air suction step. This vulcanization method can easily reduce residual air without lowering productivity.

FIG. 1 is a conceptual diagram showing a vulcanizer for a tire vulcanization method according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of the vulcanizer of FIG. FIG. 3 is a conceptual diagram showing the loader of the vulcanizer of FIG. FIG. 4 is a partially enlarged view of the paddle of the loader of FIG. 5 (a) is an explanatory view of a tire vulcanization method according to the present invention, FIG. 5 (b) is another explanatory view of a tire vulcanization method according to the present invention, and FIG. 5 (c) is an explanatory view. It is still another explanatory view of the tire vulcanization method which concerns on this invention.

Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

FIG. 1 shows a low cover 4 that is vulcanized and molded together with a tire vulcanizer 2. The vulcanizer 2 includes a mold 6, a bladder 8, an upper plate 10, a lower plate 12, a tread sector 14, an actuator 16, an upper platen plate 18, a lower platen plate 20, and an elevating table 22. A side elevating portion 24, an upper clamp ring 26, a lower clamp ring 28, a center post 30, and a clamp ring elevating portion 32 are provided. The vulcanization device 2 further includes a loader 40 shown in FIG. 3, a press table and a control device (not shown). The left-right direction of FIG. 1 is the radial direction of the low cover 4, the vertical direction is the vertical direction of the brewer 2, and the axial direction of the low cover 4, and the direction perpendicular to the paper surface is the circumferential direction of the low cover 4.

The mold 6 includes a large number of segments 34 as tread segments, a pair of upper and lower side plates 36, and a pair of upper and lower bead rings 38. A large number of segments 34 are arranged in the circumferential direction to form a ring shape. The shape of each side plate 36 is a ring shape. The shape of each bead ring 28 is a ring shape. The upper side plate 36 and the upper bead ring 38 are attached to the upper plate 10. The lower side plate 36 and the lower bead ring 38 are attached to the lower plate 12. The large number of segments 24, a pair of side plates 36, and a pair of bead rings 38 form a cavity surface of the mold 6.

The bladder 8 is filled with a medium for heating and pressurization to make it expandable, and the medium is discharged to make it shrinkable. FIG. 1 shows an inflated bladder 8. The bladder 8 is in contact with the inner surface 4a of the low cover 4. The bladder 8 expands along the shape of the low cover 4.

The upper plate 10 is supported by the side elevating portion 24 so as to be movable in the vertical direction with respect to the elevating table 22. Since the upper side plate 36 is attached to the upper plate 10, the upper side plate 26 is movable in the vertical direction. A lower side plate 36 is attached to the lower plate 12.

The actuator 16 is attached to the upper platen board 18. The upper platen board 18 is attached to the lift 22. The lower plate 12 is attached to the lower platen plate 20. The lower platen plate 20 is fixed to a press table (not shown). The upper platen plate 18 is made movable in the vertical direction by a press table (not shown).

As shown in FIG. 2, the upper clamp ring 26 clamps the upper end of the bladder 8. Point P1 in FIG. 2 represents the upper clamp end. The upper clamp end P1 is specified at a position where the outer surface 26a (virtual extension surface) of the upper clamp ring 26 and the plada 8 intersect. The upper clamp end P1 is specified as a midpoint in the thickness direction of the plada 8. The lower clamp ring 28 clamps the lower end of the bladder 8. The point P2 represents the lower clamp end. The lower clamp end P2 is specified as a midpoint in the thickness direction of the lower clamp ring 28 at a position where the outer surface 28a (virtual extension surface) of the lower clamp ring 28 and the plada 8 intersect.

The upper clamp ring 26 is supported by the center post 30. The center post 30 is attached to the clamp ring elevating part 32. The clamp ring elevating portion 32 supports the center post 30 so as to be movable in the vertical direction with respect to the lower platen plate 20. The lower clamp ring 28 is supported by the lower plate 12. Although not shown, the lower clamp ring 28 may be made movable in the vertical direction with respect to the lower plate 12.

The loader 40 of FIG. 3 includes a support shaft 42, a first arm 44, a second arm 46, a paddle elevating portion 48, a paddle expansion / contraction diameter portion 50, and a plurality of paddles 52. One end of the first arm 44 is supported by a support shaft 42. The other end of the first arm 44 is rotatable around the support shaft 42 as a rotation shaft. One end of the second arm 46 is pivotally attached to the other end of the first arm. The other end of the second arm 46 is rotatable around the other end of the first arm as a rotation axis. This rotation axis is parallel to the rotation axis of the support shaft 42. A paddle elevating portion 48 is attached to the other end of the second arm 46. The paddle elevating portion 48 supports the paddle expansion / contraction diameter portion 50 so as to be movable in the vertical direction. A plurality of paddles 52 are attached to the paddle expansion / contraction diameter portion 50. The plurality of paddles 52 are arranged in the circumferential direction with the paddle expansion / contraction diameter portion 50 as the center position. The plurality of paddles 52 can be enlarged and reduced in diameter by the paddle expansion / contraction diameter portion 50 in a direction orthogonal to the arranged circumferential direction.

FIG. 4 shows a partially enlarged view of the paddle 52. The paddle 52 includes a main body 54 and a tip portion 56. The main body 54 extends in the vertical direction. The tip portion 56 extends downward from the lower end of the main body 54 so as to be inclined from the inside to the outside in the radial direction. The shape of the paddle 52 is, for example, a plate. In the plate-shaped main body 54, the tangential direction in the circumferential direction in which they are arranged is the width direction, and the radial direction is the thickness direction. The shape of the paddle 52 may be rod-shaped.

The double-headed arrow Lt in FIG. 4 represents the length of the tip portion 56. This length Lt is measured as the distance from the lower end of the main body 54 to the tip of the tip 56. The double-headed arrow Tt represents the thickness of the tip 56. This thickness Tt is the thickness of the plate-shaped tip portion 56. The double-headed arrow θt represents the bending angle between the main body 54 and the tip portion 56.

The control device controls the side elevating part 24, the clamp ring elevating part 32, the press table, and the loader 40. This control device further controls a device that supplies and discharges a medium that expands and contracts the bladder 8.

A method for manufacturing a tire using the vulcanizer 2 will be described. This manufacturing method includes a preforming step and a vulcanization step. In this preforming step, the unvulcanized rubber members forming each part of the tire are bonded together to form the low cover 4. In the vulcanization step, this low cover is vulcanized in the mold 6. Through this vulcanization step, a tire is obtained from the low cover 4. This vulcanization step includes a charging step, a shaping step, a mold closing step, a pressure heating step, a mold opening step, and a taking out step.

FIG. 5A shows a state in which the low cover 4 is set in the mold 6 by the loader 40 in this loading step. The low cover 4 includes a tread portion 58, a pair of sidewall portions 60, and a pair of bead portions 62. The tread portion 58 is located on the outer side in the radial direction. Each sidewall portion 60 extends radially inward from the axial end of the tread portion 58. Each bead portion 62 extends further inward in the radial direction from the radial inner end of the sidewall portion 60. A circular hole 64 is formed by the radial inner end of the bead portion 62.

In FIG. 5A, the paddle 52 locks the bead portion 62 of the low cover 4. The low cover 4 is hung on the paddle 52. The loader 40 sets the low cover 4 at a predetermined position on the mold 2. In FIG. 5A, the bladder 8 is contracted. The upper clamp ring 26 is arranged at a predetermined height by the center post 30 and the clamp ring elevating portion 32. As a result, the upper clamp end P1 of the bladder 8 is arranged at a predetermined height.

The double-headed arrow Hb in FIG. 5A represents the height in the vertical direction from the lower clamp end P2 of the bladder 8 to the upper clamp end P1. The double-headed arrow Hr represents the height from the lower clamp end P2 of the bladder 8 to the uppermost end of the bead portion 62 of the low cover 4 in the vertical direction. The double-headed arrow Hs represents the difference between the height Hb minus the height Hr. The heights Hb, Hr, and difference Hs are measured as linear distances in the vertical direction.

FIG. 5B shows a state in which the contracted bladder 8 is expanded in the shaping step. In FIG. 5B, the bladder 8 is in contact with the inner surface 4a of the low cover 4 in a state where the paddle 52 is locked to the low cover 4. In FIG. 5B, the loader 40 holds the low cover 4 in the same predetermined position as in FIG. 5A. The upper clamp ring 26 holds the upper clamp end P1 of the bladder 8 at the same predetermined height as in FIG. 5A.

FIG. 5C shows a state in which the paddle 52 is removed from the low cover 4 in the shaping step. In FIG. 5C, the bladder 8 is in contact with the entire inner surface 4a of the low cover 4. In FIG. 5 (c), the upper clamp ring 26 holds the upper clamp end P1 of the bladder 8 at the same predetermined height as in FIG. 5 (a).

This vulcanization step will be described with reference to FIGS. 5 (a) to 5 (c). First, in the charging process, the low cover 4 is prepared. The mold 6 is in an open state. Although not shown, the segment 34 and the side plate 36 and bead ring 38 arranged above are in predetermined retracted positions. The upper clamp ring 26 is lowered as it approaches the lower clamp ring 28.

In the loading step, the paddle 52 of the loader 40 is locked to the bead portion 62 of the low cover 4. For example, the paddle 52 is reduced in diameter by the paddle expansion / contraction diameter portion 50. The reduced diameter paddle 52 is inserted into the inside of the low cover 4 through the hole 64 of the low cover 4 by the first arm 44, the second arm 46, and the paddle elevating portion 48. After insertion, the paddle 52 is expanded in diameter by the paddle expansion / contraction diameter portion 50. Due to this diameter increase, the paddle 52 is locked to the bead portion 62. The loader 40 sets the low cover 4 at a predetermined position on the mold 2. The upper clamp ring 26 is arranged at a predetermined height by the center post 30 and the clamp ring elevating portion 32. At this time, the bladder 8 is contracting. In this way, the low cover 4, the bladder 8 and the paddle 52 are brought into the state shown in FIG. 5 (a).

In the shaping step after the charging step, the medium is supplied to the bladder 8 in the state of FIG. 5A. The bladder 8 expands. The bladder 8 comes into contact with the inner surface 4a of the low cover 4. The bladder 8 expands along the inner surface 4a. At this time, since the paddle 52 is locked to the bead portion 62 of the low cover 4, a gap is formed between the bladder 8 and the inner surface 4a of the low cover 4 around the bead portion 62. The bladder 8 and the inner surface 4a are in contact with each other except around the bead portion 62 to which the paddle 52 is locked. In this way, the state shown in FIG. 5 (b) is obtained.

In the state of FIG. 5B, the paddle 52 is removed from the low cover 4. The paddle 52 is reduced in diameter by the paddle expansion / contraction diameter portion 50. The reduced diameter paddle 52 is pulled upward from the hole 64 of the low cover 4 by the paddle elevating portion 48. The pulled out paddle 52 is moved to a predetermined retracted position by the first arm 44, the second arm 46, and the paddle elevating portion 48. Around the bead portion 62 from which the paddle 52 has been removed, the bladder 8 comes into contact with the inner surface 4a of the low cover 4. The bladder 8 and the entire inner surface 4a come into contact with each other and come into close contact with each other. In this way, the state shown in FIG. 5 (c) is obtained.

In the mold closing step after the shaping step, in the state of FIG. 5C, the segment 34 in the retracted position and the upper side plate 36 and the bead ring 38 move to a predetermined position above the low cover 4. To do. In this way, the state shown in FIG. 1 is obtained. From the state shown in FIG. 1, the mold 6 is closed, and the segment 34, the pair of side plates 36, the bead ring 38, and the bladder 8 form the cavity of the mold 6. The low cover 4 is housed in the mold 6.

In the pressurizing and heating step after the mold closing step, the low cover 4 in the mold is pressurized and heated. The low cover 4 is vulcanized. Through this vulcanization, a tire is formed from the low cover 4. In the mold opening process, the mold 6 is opened. In the taking-out process, the tire is taken out from the opened mold 6.

In this shaping step, the bladder 8 is expanded to the low cover 4 with the paddle 52 locked to the bead portion 62. The expanded bladder 8 is in contact with the inner surface 4a of the low cover 4. The paddle 52 forms a gap around the bead portion 62. Air between the bladder 8 and the low cover 4 is discharged from this gap. The bladder 8 and the inner surface 4a can be in close contact with each other. In this vulcanization step, residual air between the bladder 8 and the low cover 4 is suppressed. In this vulcanization step, the generation of bares is suppressed.

In this shaping step, a gap is formed by the paddle 52 locked to the low cover 4. The paddle 52 is locked to the low cover 4 in the loading process in order to set the low cover 4 in the mold 6. In this shaping step, a gap for discharging air is formed between the bladder 8 and the low cover 4 without adding a special device or the like to the conventional vulcanization device. In this vulcanization process, residual air between the bladder 8 and the low cover 4 is easily suppressed without modifying the equipment.

In this shaping step, residual air is discharged by changing the timing of removing the paddle 52. In this vulcanization step, a special air bleeding step is not required in order to suppress the generation of residual air. No special air bleeding process time is required. In this vulcanization step, the low cover can be vulcanized and molded in the same cycle time as the conventional vulcanization step. In this vulcanization method, the generation of bears is suppressed without impairing productivity.

In this shopping step, when the height Hb of the upper clamp end P1 is too low with respect to the height Hr of the bead portion 62, the paddle 52 is radially outside before the radial outer portion of the inner surface 4a of the low cover 4. The bladder 8 and the inner surface 4a can come into contact with each other at the portion. Such contact hinders the discharge of air radially outside the contact portion. From this point of view, the difference Hs obtained by subtracting the height Hr from the height Hb is preferably 0 (mm) or more.

On the other hand, when the height Hb is too high with respect to the height Hr, the plada 8 protrudes greatly above and outside the low cover 4. The bladder 8 is deformed by the pressurization and heating of the vulcanization step, and the surface of the bladder 8 is liable to be broken or wrinkled. So-called plastic wrinkles such as folds and wrinkles cause wrinkles on the surface of the tire. From this point of view, this difference Hs is preferably 10 (mm) or less.

The paddle 52 having a small bending angle θ between the main body 54 and the tip portion 56 can be easily removed from the low cover 8 in a state where the bladder 8 is inflated (see FIG. 5B) without damaging the bladder 8. From this point of view, the bending angle θ is preferably 150 (°) or less. On the other hand, the paddle 52 having a large bending angle can be easily removed from the low cover 8 in a state where the bladder 8 is inflated without damaging the low cover 4. From this point of view, the bending angle θ is preferably 90 (°) or more.

The paddle 52 having a long tip portion 56 having a long length Lt forms a large gap between the expanding bladder 8 and the low cover 4. The paddle 52 is excellent in air discharge. From this point of view, this length Lt is preferably 5 (mm) or more. On the other hand, the paddle 52 having a small length Lt can easily be attached to the low cover 4 in a state where the bladder 8 is inflated (see FIG. 5 (b)) without damaging the bladder 8 and without damaging the low cover 4. Can be removed. From this point of view, this length Lt is. It is preferably 10 (mm) or less.

The paddle 52 having a large tip portion 56 having a large thickness Tt is excellent in discharge of residual air in the shaping process. From this point of view, the thickness Tt of the tip portion 56 is preferably 2 (mm) or more. There is no particular upper limit to this thickness Tt, but practically, this thickness Tt is preferably 10 (mm) or less.

Hereinafter, the effects of the present invention will be clarified by Examples, but the present invention should not be construed in a limited manner based on the description of these Examples.

[Example 1]
Tires were produced by the vulcanization method according to the present invention using the vulcanization apparatus shown in FIG. In this shaping process, the bladder was inflated with the paddle locked to the bead portion of the low cover. The paddle was removed from the low cover after the bladder touched the low cover. At this time, the height Hb of the upper clamp end of the bladder 8, the height Hr of the bead portion of the low cover, and the difference Hs between the height Hb and the height Hs were as shown in Table 1. By this method, 8,500 tires were produced. The size of this tire was "195 / 55R16".

[Comparative Example 1]
In this shaping process, the bladder was inflated after the paddle was removed from the bead portion of the low cover. The height Hb, height Hr, and difference Hs were as shown in Table 1. As for other configurations, 4,500 tires were produced in the same manner as in Example 1.

[Comparative Example 2]
The height Hb, height Hr and difference Hs were as shown in Table 1. Tires were produced in the same manner as in Comparative Example 1 in other configurations.

[Defective rate]
The inner surface of the obtained tire was observed and inspected for the presence of bears. In addition, the surface around the bead was observed, and wrinkles due to brad dark wreath were inspected. The defective rate was calculated by dividing the number of tires with confirmed bears and wrinkles by the number of tires produced. The results are shown as an index in Table 1. This index is expressed with the defective rate of Comparative Example 1 as 100. The smaller the number, the smaller the defect rate. The smaller this value is, the more preferable this evaluation result is.

[Cycle time]
The cycle time of the shaping process was measured. Specifically, the time from the completion of the charging process to the start of the mold closing process was measured. The results are shown as an index in Table 1. This index is expressed with the cycle time of Comparative Example 1 as 100. The smaller the number, the shorter the cycle time of this index. The smaller this value is, the more preferable this evaluation result is.

As shown in Table 1, the tires of Example 1 have an extremely small defect rate as compared with the tires of Comparative Examples 1 and 2. Further, the cycle time of the shaping process is the same as that of Comparative Examples 1 and 2. In the vulcanization method according to the present invention, the generation of wrinkles around the bear and the bead portion is suppressed without providing a special step for discharging the residual air. The vulcanization method of the example has a higher evaluation than the vulcanization method of the comparative example. From this evaluation result, the superiority of the present invention is clear.

The method described above can be widely applied to a tire vulcanization method including a step of shaping a tire with a bladder.

2 ... Vulcanizer 4 ... Low cover 6 ... Mold 8 ... Prader 26 ... Upper clamp ring 28 ... Lower clamp ring 30 ... Center post 32 ... Clamp ring elevating Part 34 ・ ・ ・ Segment 36 ・ ・ ・ Side plate 38 ・ ・ ・ Bead ring 40 ・ ・ ・ Loader 48 ・ ・ ・ Paddle elevating part 50 ・ ・ ・ Paddle expansion / contraction diameter part 52 ・ ・ ・ Paddle 54 ・ ・ ・ Main body 56 ・・ ・ Tip 58 ・ ・ ・ Bead

Claims (4)

A vulcanization method in which the low cover is vulcanized in a mold to obtain a tire.
The loading process of loading the low cover into the mold and
The shaping process in which the above low cover is shaped with a bladder,
Is equipped with
In the loading process, the paddle is locked to the bead portion of the low cover, and the low cover is set in the mold.
In the shaping step, with the paddle locked to the bead portion of the low cover, the bladder expands, and after the bladder comes into contact with the low cover, the paddle is removed from the low cover .
The position where the outer surface of the upper clamp ring that clamps the upper end of the bladder and the bladder intersect is the upper clamp end, and the position where the outer surface of the lower clamp that clamps the lower end of the bladder intersects the bladder. The lower clamp end, the height from the lower clamp end to the upper clamp end of the bladder is Hb, the height from the lower clamp end of the bladder to the bead portion of the low cover is Hr, and the height from this height Hb is high. A method for vulcanizing a tire, wherein the difference obtained by subtracting the Hr is Hs, and the difference Hs is 0 (mm) or more and 10 (mm) or less when the paddle is removed from the low cover in the shaping step . The paddle has a main body extending in the vertical direction and a tip portion extending downward from the tip of the main body so as to incline from the inside to the outside in the radial direction.
The vulcanization method according to claim 1, wherein the bending angle between the main body and the tip portion is 90 ° or more and 150 ° or less. The vulcanization method according to claim 2, wherein the length of the tip portion is 5 (mm) or more and 10 (mm) or less. The vulcanization method according to claim 2 or 3, wherein the thickness of the tip portion is 2 (mm) or more.

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