JP2010149401A - Vulcanizing mold of tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit rubber from biting in between segments of a tread mold. <P>SOLUTION: A flabellate segment 9 in which a tread mold 4 is partitioned by a mold parting plane K consists of: a main segment, which has a guiding surface inclining in separating direction from the mold parting plane K toward both circumferential outer ends in radial outside direction; and a secondary segment, being supported reciprocally movable relative to the main segment in and out in radial direction along the guiding surface and possessed of the mold parting plane K, too. When the segment 9 moves from the mold open state Y1 to the mold closed state Y2, secondary segments 21, 21 which adjoin circumferentially each other shut off in advance of the mold closed state Y2 abutting in between mold parting planes K, K while the secondary segment 21 is relatively traveling from a relatively advanced position Z1 where its inner peripheral surface 21S projects in radial inner direction beyond the inner peripheral surface 20S of main segment 20 to a reference position Z0 where the inner peripheries 21S, 20S fall substantially flush with each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mold in which a tread mold for forming a tread is formed by a plurality of segments divided in the circumferential direction, and can suppress the biting of rubber between the segments and improve the quality of the vulcanized tire. This relates to the vulcanization mold.

  Conventionally, as shown in FIGS. 8A and 8B, as a tire vulcanization mold, an upper side mold a for molding one sidewall outer surface of the tire t and another sidewall outer surface are molded. A lower side mold b, and an annular tread mold c for forming the outer surface of the tread, and the tread mold c is divided in the circumferential direction by a dividing surface ck extending radially from the tire core and radially inward and outward. One constituted by a plurality of movable segments c1 is widely known.

  In this vulcanization mold, after the green tire t is put into the cavity h, the mold is closed, and then the inside of the green tire t is pressurized and expanded using a rubber bladder d or the like, and the green tire t Is vulcanized by pressing the outer surface ts against the mold surface s. In this case, since the segment c1 is closed before the raw tire t expands, the problem of biting rubber between the segments c1 and c1 does not particularly occur.

  On the other hand, in recent years, as a method of manufacturing a pneumatic tire with high dimensional accuracy, tire constituent members are sequentially pasted around a rigid core that defines the inner surface shape of the tire, and a product that is close to the final shape of the product tire is produced. There has been proposed a method in which, after forming a tire, the raw tire is put into a mold together with a core and vulcanized.

  However, in this method, since the green tire t is formed in advance in a shape close to the final shape of the product tire, when the mold is closed, the segment c1 is in contact with the outer surface ts of the green tire t while being in contact with the split surface ck, Match ck together. Therefore, the rubber bites between the segments, which causes the problem of deteriorating the appearance quality and uniformity of the vulcanized tire.

  Accordingly, the present invention provides each segment as a guide surface of a segment main portion which is composed of a segment main portion and segment sub-portions on both outer sides in the circumferential direction, and is inclined in a direction away from the mold dividing surface toward the radially outer side. As a basic rule, the segment sub-parts are moved relative to each other, and when the diameter is reduced, the segment sub-parts can be brought into contact with each other prior to the mold closed state, and also in vulcanization molding using a core. An object of the present invention is to provide a tire vulcanization mold that can suppress the biting of rubber between segments and improve the appearance quality and uniformity of a vulcanized tire.

In order to achieve the above object, the invention of claim 1 of the present application has an upper side mold having a side molding surface for molding one sidewall outer surface of the tire, and a side molding surface for molding the other sidewall outer surface. A tire vulcanization mold comprising a lower side mold and an annular tread mold having a tread molding surface for molding the outer surface of the tread,
The tread mold is composed of fan-shaped N segments with a central angle θ divided in the circumferential direction by a mold dividing surface extending radially from the tire axis in the radial direction,
The segment includes the mold open state in which the mold dividing surfaces of adjacent segments in the circumferential direction are spaced apart from each other, the mold dividing surfaces are abutted with each other, and the inner peripheral surfaces of the segments are connected to each other to form the tread molding. Between the mold closed state forming the surface, the diameter can be expanded and contracted radially inward and outward along the mold moving direction line X which is a bisector of the central angle θ,
The segment is
At both outer ends in the circumferential direction, there are guide surfaces that are inclined at an angle α with respect to the mold dividing surface and away from the mold dividing surface toward the outside in the radial direction, and the mold moving direction line X A segment main part that can move in diameter inward and outward along the radial direction,
From the segment main part, the segment main part is held so as to be movable forward and backward in the radial direction along the guide surface relative to the segment main part. As
The segment sub-portion has a reference position where the inner peripheral surface thereof is substantially flush with the inner peripheral surface of the segment main portion, and the inner peripheral surface of the segment sub-portion is more than the inner peripheral surface of the segment main portion. Projecting back and forth between a relative forward position projecting radially inward and the mold dividing surface projecting outward in the circumferential direction from the mold dividing surface of the segment sub-portion at the reference position;
Moreover, when the segment moves from the mold open state to the mold closed state, the segment sub-portion moves from the relative advance position to the reference position, and precedes the mold closed state, and is adjacent to the circumferential direction. The matching segment sub-parts are characterized by closing the mold dividing surfaces against each other.

  Further, the invention according to claim 2 is characterized in that the angle α is larger than 0.5 times the central angle θ.

  According to a third aspect of the present invention, the segment has a biasing means for biasing the segment sub-portion radially inward.

  The invention of claim 4 is characterized in that the angle α is 60 ° or less.

  As described above, according to the present invention, a plurality of fan-shaped segments having a central angle θ for forming a tread mold are respectively provided along a central segment main part and guide surfaces provided at both ends in the circumferential direction of the segment main part. Segment sub-parts that can move relative to each other. Then, when the segment sub-portion moves forward and backward in the radial direction along the guide surface by inclining the guide surface in the direction away from the mold dividing surface toward the radially outer side, It is possible to move the mold dividing surface which is the circumferential outer end surface of the portion inward and outward in the circumferential direction.

  Accordingly, the diameter of the segment main portion expands / contracts radially inward / outward along the mold moving direction line X, which is a bisector of the central angle θ, and the direction of the segment subportion along the guide surface moves inward / outward in the radial direction. When the segment moves from the mold open state to the mold closed state by combining the relative advance and retreat movements, the mold division of the segment sub-parts adjacent to each other in the circumferential direction precedes the mold closed state. It is possible to close the surfaces by abutting each other. As a result, even in vulcanization molding using a core, the biting of rubber between segments can be suppressed, and the appearance quality and uniformity of the vulcanized tire can be improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a mold open state Y1 of a vulcanization mold 1 for a tire according to the present invention, and FIG. 2 is a cross-sectional view showing a mold closed state Y2.

  1 and 2, a tire vulcanization mold 1 includes an upper side mold 2 having a side molding surface 2S that can mold one sidewall outer surface of a tire T, and a side that can mold the other sidewall outer surface. A lower side mold 3 having a molding surface 3S and an annular tread mold 4 having a tread molding surface 4S for molding a tread outer surface are provided.

  The upper and lower side molds 2 and 3 are attached to a top plate 5 and a base plate 6, respectively. In the present example, the top plate 5 is attached to a lifting platform 7 of a press machine, for example, a known lifting means such as a cylinder. (Not shown) is supported so as to be movable up and down so as to be separated from the lifting platform 7 and the like. In this example, the base plate 6 is supported by, for example, a table base 8 of a press machine. For example, a heating platen plate (not shown) with a built-in heater is attached to the lift table 7 and the table table 8 to supply vulcanization heat to the vulcanization mold 1.

  Next, as shown in FIG. 3, the tread mold 4 includes fan-shaped N segments 9 having a central angle θ divided in the circumferential direction by a mold dividing surface K extending radially from the tire shaft core i in the radial direction. Consists of Each of the segments 9 is held by an expansion / contraction diameter means 10 (shown in FIG. 1), and a mold that forms a bisector of the central angle θ between the mold open state Y1 and the mold closed state Y2. The diameter can be expanded and contracted radially inward and outward along the movement direction line X. The mold open state Y1 is a diameter-expanded state in which the mold dividing surfaces K and K of the segments 9 adjacent in the circumferential direction are separated from each other, and at this time, the raw tire T is inserted into the mold, or The vulcanized tire T is removed from the mold. The mold closed state Y2 is a reduced diameter state in which the mold dividing surfaces K and K are abutted with each other, and the inner peripheral surfaces 9S of the segments 9 are connected to each other to form the tread molding surface 4S. In this state, the tire T is vulcanized. The division number N of the segment 9 is not particularly restricted, but is generally 8-12.

  In this example, the raw tire T is put into a mold together with the core 15 and vulcanized and molded. As shown in FIGS. 1 and 2, the core 15 receives its bead side portion. It is supported by the upper and lower holding rings 16U, 16L.

  In this example, the expansion / contraction diameter means 10 includes N tread sectors 11 to which the segments 9 are attached, and an outer ring 12 that moves the tread sectors 11 inward and outward in the radial direction. The tread sector 11 is a block body that is supported on the base plate 6 so as to be able to expand and contract in the radial direction along the mold movement direction line X. The segment 9 is attached to the inner surface in the radial direction. . The outer surface 11S in the radial direction of the tread sector 11 is inclined outward in the radial direction toward the lower side, and the outer surfaces 11S cooperate with each other to form one smooth cone surface 13.

  The outer ring 12 has an annular shape that is concentric with the tire axis i. The upper end of the outer ring 12 is supported by the lifting platform 7 and the like, and the lower end side and the inner peripheral surface thereof are engaged with the cone surface 13. A cone surface 14 is formed. Therefore, the expansion / contraction diameter means 10 converts the vertical movement of the outer ring 12 by the lifting platform 7 into expansion / contraction diameter movement inward and outward in the radial direction of the tread sector 11 when the cone surfaces 13 and 14 are engaged with each other. sell.

  And in this invention, the said segment 9 is divided | segmented and comprised in the segment main part 20 of the circumferential direction center, and a pair of segment subparts 21 and 21 distribute | arranged to the both outer sides of the circumferential direction.

  The segment main portion 20 is fixed to the tread sector 11 so that it can move in a radially expanding and contracting direction along the mold movement direction line X together with the tread sector 11. Further, as shown in FIG. 4, the segment main portion 20 is separated from the mold dividing surface K toward the outer side in the radial direction at an angle α with respect to the mold dividing surface K at both outer circumferential ends. A guide surface 22 is provided which is inclined in the direction (the direction of the inclination may be referred to as + inclination). In this example, a case is shown in which the guide surface 22 includes radially parallel inner and outer guide surface portions 22a and 22b and stepped stopper portions 22c arranged therebetween. Further, in this example, the segment main portion 20 is provided with a flange-like protruding portion 20a that extends outward in the circumferential direction beyond the guide surface 22 at the outer circumferential end portion thereof.

  Next, the segment sub-portion 21 is supported by the segment main portion 20 so as to be capable of moving back and forth in the radial direction along the guide surface 22. Specifically, the segment sub-portion 21 has a circumferential outer end surface 21So formed as the mold dividing surface K, and the circumferential inner end surface 21Si is guided by the guide surface 22 with the same slope. The moving surface 24 is formed. The guide surface 22 and the sliding surface 24 are connected so as to be smoothly slidable through a linear bearing (not shown) such as an LM guide.

  The segment sub-portion 21 has a reference position Z0 where the inner peripheral surface 21S is substantially flush with the inner peripheral surface 20S of the segment main portion 20, and the inner peripheral surface 21S of the segment sub-portion 21. It moves forward and backward in the radial direction along the guide surface 22 between the relative advance position Z1 protruding radially inward from the inner peripheral surface 20S of the segment main portion 20.

  The sliding surface 24 is formed with a stepped contact portion 24c that can contact the stopper portion 22c of the guide surface 22, and is a relative movement limit position in the radially inward direction of the segment sub-portion 21. The forward movement position Z1 is restricted. The segment 9 is provided with a biasing means 25 for biasing the segment sub-portion 21 radially inward. As this urging means 25, for example, an elastic body such as a spring or a cylinder can be suitably used. In this example, a case where a coil spring 25A is used is exemplified. This coil spring 25A is provided between the outer peripheral surface of the segment sub-part 21 and the projecting part 20a of the segment main part 20, and urges the segment sub-part 21 radially inward. It is also possible to support the coil spring 25 </ b> A between the inner peripheral surface of the tread sector 11 and the outer peripheral surface of the segment sub-portion 21 without forming the protruding portion 20 a on the segment main portion 20.

  Here, since the guide surface 22 has the + inclination, the position P1 of the mold dividing surface K of the segment sub-portion 21 at the relative advance position Z1 is the position of the mold dividing surface K at the reference position Z0. It can inevitably protrude outward in the circumferential direction as compared with P0. In the present invention, by utilizing this outward protrusion in the circumferential direction, the mold dividing surfaces K and K can be brought into contact with each other prior to the mold closed state Y2.

  5A, 5B, and 6 show the movement of the segment 9 when it moves from the mold open state Y1 to the mold closed state Y2.

  FIG. 5 (A) shows the mold open state Y1, and the segment main portion 20 moves in the diameter direction along the mold movement direction line X to the end position Q1 radially outward. In the mold open state Y1, the segment sub-part 21 is urged by the urging means 25 (not shown in FIG. 5A), and the stopper part 22c and the abutting part 24c abut against each other. Is held at the general forward position Z1. At this time, the adjacent mold dividing surfaces K and K are separated from each other.

  Further, when the segment main portion 20 moves radially inward along the mold movement direction line X, the adjacent mold dividing surfaces K and K gradually approach each other, and thereafter, FIG. As shown to B), it will be in the division surface closed state Za which the metal division surfaces K and K face each other and close. Thereafter, when the diameter-reduction movement further proceeds, the segment main portions 20 and 20 come closer to each other. Therefore, the segment sub-portion 21 is maintained along the guide surface 22 while maintaining the divided surface closed state Za. Move backward in the radial direction relative to.

  Then, when the diameter reduction movement further proceeds and the inner peripheral surface 20S of the segment main portion 20 reaches the tread outer surface of the tire T as shown in FIG. 6, the inner peripheral surface 21S of the segment sub-portion 21 is also the tread outer surface. Reach almost simultaneously. At this time, the segment 9 becomes a reference position Z0 where the inner peripheral surfaces 20S and 21S are substantially flush with each other, and forms a mold closed state Y2 that cooperates with each other to form a series of tread molding surfaces 4S. .

  Thus, in the tread mold 4 of the present embodiment, prior to the mold closed state Y2, the mold dividing surfaces K and K adjacent to each other in the circumferential direction can be brought into contact with each other before closing, so the core 15 is used. Also in the vulcanization molding which has been carried out, the biting of the rubber between the segments 9 and 9 can be suppressed, and the appearance quality and uniformity of the vulcanized tire can be improved.

  In order to perform the operation, the angle α of the guide surface 22 is set larger than 0.5 times the central angle θ. If the angle α is not more than 0.5 times the central angle θ, the split surface closed state Za cannot be achieved prior to the mold closed state Y2. If the difference (α−0.5θ) between the angle α and the value 0.5 times the central angle θ (0.5θ) is too small, the split surface closed state Za is close to the mold closed state Y2. Therefore, there is a risk of rubber biting due to variation in the shape of the raw tire. Therefore, the difference (α−0.5θ) is preferably 5 ° or more, and more preferably 15 ° or more. On the other hand, if the angle α is too large, the corner portion 20E (shown in FIG. 4) of the segment main portion 20 sandwiched between the inner peripheral surface 20S and the guide surface 22 becomes insufficient in strength and tends to damage the durability. It becomes. Therefore, the upper limit of the angle α is preferably 60 ° or less, and more preferably 50 ° or less.

  Further, the urging force F inward in the radial direction by the urging means 25 is larger than the embedding input F0 in which the radially inner end of the segment sub-part 21 can be embedded in the rubber of the raw tire. If the urging force F is equal to or less than the buried input F0, the segment sub-portion 21 is lifted outward in the radial direction by the internal pressure during vulcanization, which causes a problem that the appearance quality of the vulcanized tire is deteriorated. The biasing force F is smaller than the force F2 for closing the segment 9, that is, the force F2 for moving the segment main portion 20 radially inward by the expansion / contraction diameter means 10, and the biasing force F is equal to or greater than the force F2. In this case, the segment sub-part 21 cannot be moved forward and backward in the radial direction in conjunction with the diameter reduction of the segment main part 20.

  In the segment 9, the projection height H (shown in FIG. 4) at which the inner peripheral surface 21 </ b> S of the segment sub-portion 21 protrudes from the inner peripheral surface 20 </ b> S of the segment main portion 20 at the relative advance position Z <b> 1. It is preferable to set it below the maximum protrusion height of a tire groove forming rib (not shown) protruding on the tread molding surface 4S. If this maximum protrusion height is exceeded, the mold handling property tends to be reduced. It becomes. On the other hand, if the protrusion height H is too small, the split surface closed state Za occurs near the mold closed state Y2, which may cause rubber biting due to variations in the shape of the raw tire. Therefore, the protrusion height H is preferably about 5 to 10 mm. The segment 9 is preferably provided with stopper means for preventing the segment sub-part 21 from moving backward outward in the radial direction from the reference position Z0. In this example, the stopper means is composed of an outer peripheral surface of the segment sub-portion 21 and an inner peripheral surface of the overhang portion 20a, and both come into contact with each other at the reference position Z0. The backward movement from the reference position Z0 is prevented.

  As shown in FIG. 7, a cylinder 25B can be adopted as the urging means 25. In such a case, the forward / backward movement operation of the segment sub-portion 21 can be controlled more reliably and accurately.

  As described above, the particularly preferred embodiment of the present invention has been described in detail. However, the present invention is not limited to the vulcanization molding using the core, but can also be applied to the vulcanization molding using the bladder. Without being limited to the form, the present invention can be carried out by being modified into various modes.

It is a meridional section showing the mold open state of the vulcanization mold of the tire of the present invention. It is a meridional section showing a mold closed state of a vulcanization mold. It is sectional drawing at right angles to the tire axial center which shows the metal mold | die open state and metal mold | die closed state of a vulcanization mold. It is sectional drawing which expands and shows a segment. (A) is sectional drawing which shows the positional relationship of the segment main part and sub part in a metal mold | die closed state, (B) is the positional relationship (segment surface closed state) of the segment main part and sub part in the middle of diameter reduction. FIG. It is sectional drawing which shows the positional relationship of the segment main part and sub part in a metal mold | die closed state. It is sectional drawing which shows the other example of a biasing means. (A), (B) is a meridional sectional view showing a conventional vulcanization mold, and a sectional view perpendicular to the tire axis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Side mold 2S Upper side mold 2S Side molding surface 3 Lower side mold 3S Side molding surface 4 Tread mold 4S Tread molding surface 9 Segment 20 Segment main part 20S Inner peripheral surface 21 Segment sub part 21S Inner peripheral surface 22 Guide Surface 25 Biasing means i Tire axis K Mold split surface T Tire Y1 Mold open state Y2 Mold closed state Z0 Reference position Z1 Relative forward position

Claims (4)

An upper side mold having a side molding surface for molding one sidewall outer surface of the tire, a lower side mold having a side molding surface for molding the other sidewall outer surface, and a tread molding surface for molding the tread outer surface. A tire vulcanization mold comprising an annular tread mold,
The tread mold is composed of fan-shaped N segments with a central angle θ divided in the circumferential direction by a mold dividing surface extending radially from the tire axis in the radial direction,
The segment includes the mold open state in which the mold dividing surfaces of adjacent segments in the circumferential direction are spaced apart from each other, the mold dividing surfaces are abutted with each other, and the inner peripheral surfaces of the segments are connected to each other to form the tread molding. Between the mold closed state forming the surface, the diameter can be expanded and contracted radially inward and outward along the mold moving direction line X which is a bisector of the central angle θ,
The segment is
At both outer ends in the circumferential direction, there are guide surfaces that are inclined at an angle α with respect to the mold dividing surface and away from the mold dividing surface toward the outside in the radial direction, and the mold moving direction line X A segment main part that can move in diameter inward and outward along the radial direction,
From the segment main part, the segment main part is held so as to be movable forward and backward in the radial direction along the guide surface relative to the segment main part. As
The segment sub-portion has a reference position where the inner peripheral surface thereof is substantially flush with the inner peripheral surface of the segment main portion, and the inner peripheral surface of the segment sub-portion is more than the inner peripheral surface of the segment main portion. Projecting back and forth between a relative forward position projecting radially inward and the mold dividing surface projecting outward in the circumferential direction from the mold dividing surface of the segment sub-portion at the reference position;
Moreover, when the segment moves from the mold open state to the mold closed state, the segment sub-portion moves from the relative advance position to the reference position, and precedes the mold closed state, and is adjacent to the circumferential direction. A tire vulcanization mold characterized in that matching segment sub-parts close each other by abutting the mold division surfaces.   The tire vulcanization mold according to claim 1, wherein the angle α is larger than 0.5 times the central angle θ.   The tire vulcanization mold according to claim 1, wherein the segment has an urging means for urging the segment sub-portion radially inward.   The tire vulcanization mold according to claim 1, wherein the angle α is 60 ° or less.

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