JP4814362B2 - Mold for tire - Google Patents

Description

  The present invention relates to a mold for a tire. Specifically, the present invention relates to a mold having a plurality of segments.

  A mold is used in the tire vulcanization process. In the vulcanization process, the raw cover obtained by preforming is put into a mold. The raw cover is heated while being pressurized in a cavity surrounded by the mold and the bladder. The rubber composition of the raw cover flows in the cavity by pressurization and heating. The rubber causes a crosslinking reaction by heating, and a tire is obtained.

  Molds are roughly classified into split molds and two-piece molds. In recent years, the split mold has been mainly used from the viewpoint that the degree of freedom of the tread pattern is high. The split mold includes a plurality of tread segments. FIG. 11 is a front view showing a conventional segment 2. The segment 2 includes two main mountains 6 and a large number of minor mountains 8 on the cavity surface 4. In a plan view, the segment 2 has an arc shape. A large number of segments 2 are arranged to form a ring-shaped cavity. The surface 10 of the segment 2 that contacts the adjacent segment 2 is referred to as a “divided surface”. The dividing surface 10 extends along the axial direction of the tire.

  The tire obtained by the mold having the segment 2 includes a main groove and a sub groove. The main groove has a shape obtained by inverting the shape of the main mountain 6. The main groove extends in the circumferential direction of the tire. The minor groove has a shape in which the shape of the minor mountain 8 is reversed. The main groove and the sub-groove contribute to drainage when the tire travels on a wet road surface. In particular, since the main groove extends in the circumferential direction, it greatly contributes to draining water backward.

  An example of a mold having a segment is disclosed in Japanese Patent Laid-Open No. 9-99435.

JP-A-9-99435

  In the vulcanization process, pressure is applied to the dividing surface 10 of the segment 2. This pressure causes compressive deformation of the dividing surface 10. By repeatedly using the mold, the clearance between the segment 2 and the other segment 2 grows. The mold having a large clearance causes burrs on the tire. The burrs exist along the dividing surface 10.

  FIG. 12 shows a part of the tire 14 having the burr 12. Since the dividing surface 10 extends in the axial direction, the burr 12 also extends in the axial direction. The burr 12 crosses the main groove 16. The burr 12 closes the main groove 16. The burr 12 inhibits drainage by the main groove 16. This burr 12 may impair the silence of the tire 14. Further, the burr 12 may become a starting point of a crack. The burr 12 impairs the quality of the tire 14.

  An object of the present invention is to provide a mold from which a high-quality tire can be obtained.

  The tire mold according to the present invention includes a plurality of segments for forming a tread surface of a tire. These segments are arranged along the circumferential direction. Each segment has a main mountain for forming a main groove of the tire on its cavity surface. This main mountain extends substantially in the circumferential direction. The segment has a split surface that abuts another adjacent segment. In the main mountain, the dividing surface has a step.

  Preferably, the width of the step is 1 mm or more and 50 mm or less. Preferably, the angle of the surface forming the step with respect to the circumferential direction is 45 ° or less. Preferably, this mold does not have a dividing surface that divides the main mountain.

The tire manufacturing method according to the present invention includes:
(1) A process in which a raw cover is obtained by preforming,
(2) It has a plurality of segments for forming the tread surface of the tire, these segments are arranged along the circumferential direction, and each segment forms a main groove for forming the main groove of the tire on its cavity surface. The main mountain extends substantially in the circumferential direction, the segment has a split surface that abuts another adjacent segment, and the split surface is a step in the main mountain. A process in which a raw cover is put into a mold having
And (3) a step in which the raw cover is pressurized and heated in the mold.

  In the mold according to the present invention, the burr does not block the main groove. Tires obtained with this mold are of high quality.

FIG. 1 is a plan view illustrating a part of a tire mold according to an embodiment of the present invention. FIG. 2 is a schematic perspective view showing a segment of the mold of FIG. FIG. 3 is an enlarged front view showing a segment of the mold of FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a cross-sectional perspective view showing a part of the tire obtained by the mold of FIG. FIG. 6 is an enlarged view showing a part of the segment of FIG. FIG. 7 is an enlarged view showing a part of the segment of FIG. FIG. 8 is a front view showing a segment of a tire mold according to another embodiment of the present invention. FIG. 9 is a front view showing a segment of a tire mold according to still another embodiment of the present invention. FIG. 10 is a front view showing a segment of a tire mold according to still another embodiment of the present invention. FIG. 11 is a front view showing a segment of a conventional tire mold. FIG. 12 is a cross-sectional perspective view showing a part of the tire obtained by the mold of FIG.

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

  The mold 16 shown in FIG. 1 includes a large number of tread segments 18, a pair of upper and lower side plates 20, and a pair of upper and lower bead rings 22. The planar shape of each segment 18 is substantially arcuate. A large number of segments 18 are arranged in a ring shape. As shown in FIG. 2, the mold 16 includes nine segments 18. Each side plate 20 is substantially ring-shaped. Each bead ring 22 is substantially ring-shaped. This mold 16 is a so-called “split mold”.

  In FIG. 3, an arrow X indicates the circumferential direction of the mold 16, and an arrow Y indicates the axial direction of the mold 16. As shown in FIGS. 3 and 4, the segment 18 includes an upper main mountain 26 and a lower main mountain 28 on the cavity surface 24 thereof. The upper main mountain 26 and the lower main mountain 28 each extend in the circumferential direction (left-right direction in FIG. 3). The segment 18 further includes a number of secondary mountains 30 on its cavity surface 24. As is clear from FIG. 4, the upper main mountain 26, the lower main mountain 28, and the secondary mountain 30 protrude from the base surface 32.

  As shown in FIG. 3, the segment 18 includes a left dividing surface 34 and a right dividing surface 36. When the mold 16 is tightened, the left dividing surface 34 comes into contact with the right dividing surface 36 of another segment 18 (not shown) located on the left side of the segment 18. When the mold 16 is tightened, the right split surface 36 abuts the left split surface 34 of another segment 18 (not shown) located on the right side of the segment 18.

  The left split surface 34 has a first surface 38, a second surface 40, a third surface 42, a fourth surface 44 and a fifth surface 46. The first surface 38, the third surface 42, and the fifth surface 46 each extend in the axial direction. The second surface 40 and the fourth surface 44 each extend in the circumferential direction. The right split surface 36 has a sixth surface 48, a seventh surface 50, an eighth surface 52, a ninth surface 54 and a tenth surface 56. The sixth surface 48, the eighth surface 52, and the tenth surface 56 each extend in the axial direction. The seventh surface 50 and the ninth surface 54 extend in the circumferential direction.

  When the mold 16 is tightened, the first surface 38 contacts the sixth surface 48 of the other segment 18, the second surface 40 contacts the seventh surface 50 of the other segment 18, and the third surface 42 The fourth surface 44 is in contact with the ninth surface 54 of the other segment 18, the fifth surface 46 is in contact with the tenth surface 56 of the other segment 18, and the sixth surface 56 is in contact with the tenth surface 56 of the other segment 18. The surface 48 contacts the first surface 38 of the other segment 18, the seventh surface 50 contacts the second surface 40 of the other segment 18, and the eighth surface 52 contacts the third surface 42 of the other segment 18. The ninth surface 54 contacts the fourth surface 44 of the other segment 18, and the tenth surface 56 contacts the fifth surface 46 of the other segment 18.

  The second surface 40 is located between the first surface 38 and the third surface 42. The second surface 40 forms a step between the first surface 38 and the third surface 42. The fourth surface 44 is located between the third surface 42 and the fifth surface 46. The fourth surface 44 forms a step between the third surface 42 and the fifth surface 46. The seventh surface 50 is located between the sixth surface 48 and the eighth surface 52. A step is formed between the sixth surface 48 and the eighth surface 52 by the seventh surface 50. The ninth surface 54 is located between the eighth surface 52 and the tenth surface 56. The ninth surface 54 forms a step between the eighth surface 52 and the tenth surface 56.

  The second surface 40 is at a position corresponding to the upper main mountain 26. The left dividing surface 34 has a step formed by the second surface 40 in the upper main mountain 26. In other words, the left dividing surface 34 does not divide the upper main mountain 26.

  The fourth surface 44 is at a position corresponding to the lower main mountain 28. The left dividing surface 34 has a step formed by the fourth surface 44 in the lower main mountain 28. In other words, the left dividing surface 34 does not divide the lower main mountain 28.

  The seventh surface 50 is at a position corresponding to the upper main mountain 26. The right split surface 36 has a step formed by the seventh surface 50 in the upper main mountain 26. In other words, the right split surface 36 does not divide the upper main mountain 26.

  The ninth surface 54 is at a position corresponding to the lower main mountain 28. The right split surface 36 has a step formed by the ninth surface 54 in the lower main mountain 28. In other words, the right split surface 36 does not divide the lower main mountain 28. The mold 16 does not have any split surfaces that divide the main mountains 26 and 28. Some division surfaces may divide the main mountain.

  By clamping the mold 16, pressure is applied to the left split surface 34. The direction of this pressure is mainly in the circumferential direction. As described above, the first surface 38, the third surface 42, and the fifth surface 46 extend in the axial direction. Accordingly, a large pressure is applied to the first surface 38, the third surface 42, and the fifth surface 46. Since the second surface 40 and the fourth surface 44 extend in the circumferential direction, no great pressure is applied. By repeatedly using the mold 16, the first surface 38, the third surface 42, and the fifth surface 46 undergo compression deformation.

  By clamping the mold 16, pressure is applied to the right split surface 36. The direction of this pressure is mainly in the circumferential direction. The sixth surface 48, the eighth surface 52, and the tenth surface 56 extend in the axial direction as described above. Accordingly, a large pressure is applied to the sixth surface 48, the eighth surface 52 and the tenth surface 56. Since the seventh surface 50 and the ninth surface 54 extend in the circumferential direction, no great pressure is applied. By repeatedly using the mold 16, the sixth surface 48, the eighth surface 52, and the tenth surface 56 cause compression deformation.

  When the mold 16 having undergone compressive deformation is tightened, the clearance between the first surface 38 and the sixth surface 48 is large, the clearance between the third surface 42 and the eighth surface 52 is large, and the fifth surface 46 and the tenth surface. The clearance with the surface 56 is large. Large burrs are generated on the surface of the tire obtained by the mold 16 at positions corresponding to these clearances.

  A part of the tire 58 obtained with the mold 16 in which the compression deformation has occurred is shown in FIG. FIG. 5 shows a main groove 60, a burr 62a, and another burr 62b. The burr 62 a is formed by a clearance between the first surface 38 (see FIG. 3) and the sixth surface 48. The burr 62 b is formed by the clearance between the third surface 42 and the eighth surface 52. The main groove 60 is formed by the upper main mountain 26. Since the upper main mountain 26 has a step formed by the second surface 40 and the seventh surface 50, the burr 62a and the burr 62b are displaced in the circumferential direction as shown in FIG. Although not shown, the tire 58 also includes a main groove formed by the lower main mountain 28. In this main groove, the burr formed by the clearance between the third surface 42 and the eighth surface 52 and the burr formed by the clearance between the fifth surface 46 and the tenth surface 56 are shifted in the circumferential direction. .

  Since the burr 62a and the burr 62b are displaced from each other, the burr 62 does not form a partition. The burr 62 does not close the main groove 60. In the main groove 60, water smoothly flows backward. The tire 58 is excellent in drainage. The burr 62 that does not form a partition does not hinder the quietness of the tire 58. Further, the burr 62 is unlikely to become a starting point of a crack.

  In FIG. 3, what is indicated by an arrow W is the width of the step. The width W is preferably 1 mm or more and 50 mm or less. The tire 58 without the burr 62 that closes the main groove 60 can be obtained by the segment 18 having the width W of 1 mm or more. In this respect, the width W is more preferably 3 mm or more, and particularly preferably 5 mm or more. Manufacture of the segment 18 whose width W is 50 mm or less is easy. In this respect, the width W is more preferably 30 mm or less, and particularly preferably 20 mm or less.

  The second surface 40, the fourth surface 44, the seventh surface 50, and the ninth surface 54 extend in the circumferential direction as described above. The angles of these surfaces with respect to the circumferential direction are zero. These surfaces may be slightly inclined with respect to the circumferential direction. The angle of inclination is preferably 45 ° (degree) or less, more preferably 20 ° or less, and particularly preferably 10 ° or less. Ideally, the angle is zero.

  As shown in FIG. 6, bevels 64 a are formed at the corners between the first surface 38 and the second surface 40. As shown in FIG. 7, a chamfer 66 a is formed between the sixth surface 48 and the seventh surface 50. When the mold 16 is tightened, the bevel 64 a comes into contact with the chamfer 66 a of the other segment 18.

  As shown in FIG. 6, a chamfer 66 b is formed at the corner between the second surface 40 and the third surface 42. As shown in FIG. 7, a bevel 64 b is formed between the seventh surface 50 and the eighth surface 52. When the mold 16 is tightened, the chamfer 66b contacts the bevel 64b of the other segment 18.

  As shown in FIG. 6, a chamfer 66 c is formed at a corner between the third surface 42 and the fourth surface 44. As shown in FIG. 7, a bevel 64 c is formed between the eighth surface 52 and the ninth surface 54. When the mold 16 is tightened, the chamfer 66 c comes into contact with the bevel 64 c of the other segment 18.

  As shown in FIG. 6, a bevel 64 d is formed at a corner between the fourth surface 44 and the fifth surface 46. As shown in FIG. 7, a chamfer 66 d is formed between the ninth surface 54 and the tenth surface 56. When the mold 16 is tightened, the bevel 64 d comes into contact with the chamfer 66 d of the other segment 18.

  The chamfer 66 prevents the corners of the segment 18 from being damaged. From the viewpoint of preventing breakage, the width C of the chamfer 66 is preferably 1.0 mm or more, more preferably 2.0 mm or more, and particularly preferably 3.0 mm or more. From the viewpoint that the burr 62 that closes the main groove 60 is hardly generated, the width C is preferably 5.0 mm or less. Instead of the chamfer 66, a round chamfer (so-called round) may be formed. From the viewpoint of preventing corner breakage, the radius of the round chamfer is preferably 1.0 mm or more, more preferably 2.0 mm or more, and particularly preferably 3.0 mm or more. From the viewpoint that the burr 62 that closes the main groove 60 is hardly generated, the radius is preferably 5.0 mm or less.

  In the tire manufacturing method using this mold 16, a raw cover (unvulcanized tire) is obtained by preforming. This raw cover is put into the mold 16 in a state where the mold 16 is open and the bladder is contracted. The mold 16 is tightened and the bladder expands. The raw cover is pressed against the cavity surface 24 of the mold 16 by a bladder and pressurized. At the same time, the raw cover is heated. The rubber composition flows by pressurization and heating. The rubber causes a crosslinking reaction by heating, and the tire 58 is obtained. The process in which the raw cover is pressurized and heated is referred to as a vulcanization process. A core may be used instead of or together with the bladder.

  In the vulcanization process, two main grooves 60 (see FIG. 5) and a number of sub grooves are formed on the surface of the tire 58. One main groove 60 corresponds to the upper main mountain 26. The other main groove 60 corresponds to the lower main mountain 28. Each minor groove corresponds to the minor mountain 30. Further, on the surface of the tire 58, a burr 62a formed by a clearance between the first surface 38 and the sixth surface 48, a burr 62b formed by a clearance between the third surface 42 and the eighth surface 52, and a fifth surface. There is a burr 62 formed by the clearance between 46 and the tenth surface 56. As described above, these burrs 62 do not block the main groove 60. By this manufacturing method, the tire 2 excellent in quality is obtained.

  FIG. 8 shows a segment 68 of a tire mold according to another embodiment of the present invention. The segment 68 includes an upper main mountain 72 and a lower main mountain 74 on its cavity surface 70. Each of the upper main mountain 72 and the lower main mountain 74 has a zigzag shape. Each of the upper main mountain 72 and the lower main mountain 74 extends substantially in the circumferential direction.

  The segment 68 includes a left dividing surface 76 and a right dividing surface 78. The left split surface 76 has a step at the upper main mountain 72. In other words, the left dividing surface 76 does not divide the upper main mountain 72. The left split surface 76 has a step at the lower main mountain 74. In other words, the left dividing surface 76 does not divide the lower main mountain 74. The right split surface 78 has a step at the upper main mountain 72. In other words, the right split surface 78 does not divide the upper main mountain 72. The right split surface 78 has a step at the lower main mountain 74. In other words, the right split surface 78 does not divide the lower main mountain 74. In the tire obtained by this mold, burrs for closing the main groove do not occur.

  Also in this segment 68, the width W of the step is preferably 1 mm or more and 50 mm or less. The width W is more preferably 3 mm or more, and particularly preferably 5 mm or more. The width W is more preferably 30 mm or less, and particularly preferably 20 mm or less.

  Also in this segment 68, the angle with respect to the circumferential direction of the surface 79 forming the step is preferably 45 ° or less, more preferably 20 ° or less, and particularly preferably 10 ° or less. Ideally, the angle is zero.

  Also in this segment 68, it is preferable that the corner is chamfered or rounded.

  FIG. 9 shows a segment 80 of a tire mold according to still another embodiment of the present invention. The segment 80 includes an upper main mountain 84, a lower main mountain 86, and a number of secondary mountains 88 on the cavity surface 82. Each of the upper main mountain 84 and the lower main mountain 86 extends in the circumferential direction.

  The segment 80 includes a left dividing surface 90 and a right dividing surface 92. The left dividing surface 90 has a step at the upper main mountain 84. In other words, the left dividing surface 90 does not divide the upper main mountain 84. The left dividing surface 90 has a step at the lower main mountain 86. In other words, the left dividing surface 90 does not divide the lower main mountain 86. The right split surface 92 has a step at the upper main mountain 84. In other words, the right split surface 92 does not divide the upper main mountain 84. The right split surface 92 has a step at the lower main mountain 86. In other words, the right split surface 92 does not divide the lower main mountain 86. In the tire obtained by this mold, burrs for closing the main groove do not occur.

  Also in this segment 80, the width W of the step is preferably 1 mm or more and 50 mm or less. The width W is more preferably 3 mm or more, and particularly preferably 5 mm or more. The width W is more preferably 30 mm or less, and particularly preferably 20 mm or less.

  Also in this segment 80, the angle with respect to the circumferential direction of the surface 94 forming the step is preferably 45 ° or less, more preferably 20 ° or less, and particularly preferably 10 ° or less. Ideally, the angle is zero.

  Also in this segment 80, it is preferable that the corner is chamfered or rounded.

  FIG. 10 shows a segment 96 of a tire mold according to still another embodiment of the present invention. The segment 96 includes an upper main mountain 100, a lower main mountain 102, and a number of secondary mountains 104 on the cavity surface 98. Each of the upper main mountain 100 and the lower main mountain 102 extends in the circumferential direction.

  The segment 96 includes a left dividing surface 106 and a right dividing surface 108. The left dividing surface 106 has a step in the upper main mountain 100. In other words, the left dividing surface 106 does not divide the upper main mountain 100. The left dividing surface 106 has a step in the lower main mountain 102. In other words, the left dividing surface 106 does not divide the lower main mountain 102. The right split surface 108 has a step in the upper main mountain 100. In other words, the right split surface 108 does not divide the upper main mountain 100. The right split surface 108 has a step in the lower main mountain 102. In other words, the right split surface 108 does not divide the lower main mountain 102. In the tire obtained by this mold, burrs for closing the main groove do not occur.

  Also in this segment 96, the width W of the step is preferably 1 mm or more and 50 mm or less. The width W is more preferably 3 mm or more, and particularly preferably 5 mm or more. The width W is more preferably 30 mm or less, and particularly preferably 20 mm or less.

  In this segment 96, the left split surface 106 includes two surfaces 110 that form a step. Each surface 110 is inclined inward in the axial direction toward the surface 112. The right split surface 108 includes two surfaces 114 that form a step. Each surface 114 is inclined inward in the axial direction toward the surface 116. The inclination angle θ of the inclination is preferably 45 ° or less, more preferably 20 ° or less, and particularly preferably 10 ° or less. Ideally, the angle is zero.

  Also in this segment 96, it is preferable that the corner is chamfered or rounded.

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

[Example 1]
A mold having the segments shown in FIG. 3 was prepared. The width W of the step on the dividing surface of this mold is 10 mm. The angle of the surface forming the step with respect to the circumferential direction is 0 °.

[Example 2-5]
A mold having a width W shown in Table 1 below was prepared.

[Example 6]
A mold having the segments shown in FIG. 10 was prepared. The width W of the step on the dividing surface of this mold is 10 mm. The angle θ of the surface forming the step with respect to the circumferential direction is 3 °.

[Example 7-8]
A mold having an angle θ shown in Table 1 below was prepared.

[Comparative example]
A mold having a divided surface with no step was prepared. This mold comprises the segments shown in FIG.

[Drainage]
The mold was opened and closed 1000 times. A low cover was put into this mold to obtain a tire. Water was injected into the main groove of this tire, and the drainage was visually determined. Rating was made according to the criteria.
A: Good B: Somewhat bad C: Bad

[Ease of production]
The ease of segment production was rated according to the following criteria.
A: Extremely easy B: Easy C: Difficult

  As shown in Table 1, a tire excellent in drainage is obtained with the mold of each example. From this evaluation result, the superiority of the present invention is clear.

  The mold according to the present invention is suitable for manufacturing various tires.

16 ... Mold 18, 68, 80, 96 ... Segment 26, 72, 84, 100 ... Upper main mountain 28, 74, 86, 102 ... Lower main mountain 30, 88, 104 ...・ Deputy mountain 34,76,90,106 ... Left side split surface 36,78,92,108 ... Right side split surface 38 ... First side 40 ... Second side 42 ... Third side 44: Fourth surface 46: Fifth surface 48 ... Sixth surface 50 ... Seventh surface 52 ... Eighth surface 54 ... Ninth surface 56 ... Tenth surface 58 ... Tire 60 ... Main groove 62 ... Burr 64 ... Bevel 66 ... Chamfer

Claims (5)

It has multiple segments to form the tread surface of the tire,
These segments are lined up along the circumferential direction,
Each segment has a main mountain for forming the main groove of the tire on its cavity surface,
The main mountain extends substantially in the circumferential direction,
The segment has a split surface that abuts another adjacent segment;
This dividing surface has a step in the tire width direction,
Tire mold this step is that is formed in the main mountain.   The mold according to claim 1, wherein a width of the step is 1 mm or more and 50 mm or less.   The mold according to claim 1 or 2, wherein an angle of a surface forming the step with respect to a circumferential direction is 45 ° or less. The mold according to any one of claims 1 to 3, wherein all the divided surfaces have steps in the tire width direction, and all the steps are formed in the main mountain . (1) A process in which a raw cover is obtained by preforming,
(2) It has a plurality of segments for forming the tread surface of the tire, these segments are arranged along the circumferential direction, and each segment forms a main groove for forming the main groove of the tire on its cavity surface. The main mountain extends substantially in the circumferential direction, and the segment has a split surface that comes into contact with another adjacent segment, and the split surface is the width direction of the tire. step has a step, the mold this step is that is formed in the main pile, the raw cover is put in,
And (3) The tire manufacturing method including the process by which this raw cover is pressurized and heated within a mold.

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