Mold for forming a tire and method of tire production

Abstract

The present application provides a tire molding mold (1) and a tire production method using the mold, the tire molding mold (1) is equipped with an annular tread molding portion (20), the tread molding portion (20) is configured to open and close when a plurality of segments (21) move in the radial direction, and has a plurality of design surface segmented mold portions (23, 24), the plurality of design surface segmented mold portions (23, 24) are each equipped with a tread design surface (20c) for molding a tread (2c) of a tire (2), are arranged side by side in the circumferential direction of the segment (21), and are configured to rotate around a rotatable shaft (26) parallel to the axis of the tread molding portion (20) when the tread molding portion (20) is opened after the tire (2) has undergone vulcanization molding.

Description

Technical Field

[0001] This disclosure relates to molds for forming tires and tire production methods. Background Technology

[0002] In conventional molds for forming tires used in the vulcanization molding of unvulcanized raw tires to produce tires, it is known that the annular tread forming part (tread mold) for forming the tire tread is divided into multiple segments arranged circumferentially and is configured to open and close by moving each of the segments radially (see, for example, Patent Documents 1 to 3).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2000-326332

[0006] Patent Document 2: Japanese Patent Application Publication No. 2000-334740

[0007] Patent Document 3: Japanese Patent Application Publication No. 2009-149079 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In the conventional molds used to form tires described above, the tread design surface oriented radially inward toward each segment is typically provided with protrusions, such as ribs or blades, that project radially inward from the tread design surface in order to form a tread pattern with concave and convex shapes, which are formed, for example, by grooves and sipes on the tread of the formed tire.

[0010] However, in tire designs with protrusions, when the tire is demolded from the tread forming section by moving the segments radially outward after vulcanization, the protrusions, especially those at the circumferential ends of the segments, result in high undercut resistance. Therefore, in cases such as tires with complex tread patterns, this excessive undercut resistance can lead to defects such as permanent deformation and protrusion breakage in the tire tread after demolding.

[0011] This disclosure was made in view of the above-mentioned problems, and the purpose of this disclosure is to provide a mold for forming a tire and a tire production method that can reduce the undercut resistance of the tread caused by protrusions during tire demolding.

[0012] Solution for solving the problem

[0013] The present disclosure discloses a mold for forming a tire, which is used to vulcanize an unvulcanized raw tire into a tire. The mold includes: an annular tread forming portion divided into a plurality of circumferentially arranged segments and configured to open and close by radially moving each of the segments, wherein each of the segments includes: a plurality of design surface dividing mold portions, each of the plurality of design surface dividing mold portions including a tread design surface for forming the tread of the tire, the plurality of design surface dividing mold portions being arranged circumferentially in the segment, and the plurality of design surface dividing mold portions being configured to rotate about a rotatable axis parallel to the axis of the tread forming portion when the tread forming portion is opened after the tire vulcanization is completed.

[0014] In an embodiment, the mold for forming a tire disclosed herein may be constructed such that each segment includes a retainer that is driven radially outward by a container when the tread forming portion is opened, and each of the plurality of design surface segmenting mold portions is supported by the rotatable shaft in a manner that allows it to rotate relative to the retainer.

[0015] In an embodiment, the mold for forming a tire disclosed herein can be configured such that the mold includes two design surface segmentation mold portions, wherein a rotatable shaft corresponding to one of the design surface segmentation mold portions is arranged on one circumferential end side of the retainer, and a rotatable shaft corresponding to the other of the design surface segmentation mold portions is arranged on the other circumferential end side of the retainer.

[0016] In an embodiment, the mold for forming a tire disclosed herein can be constructed in such a way that the design surface dividing mold portion includes a back plate portion and a pair of side plate portions and is supported at the back plate portion by the rotatable shaft, the pair of side plate portions extending radially inward from both ends of the axial direction of the back plate portion.

[0017] In an embodiment, the mold for forming a tire disclosed herein may be configured such that a spring member is attached between the design surface segmentation mold portion corresponding to the spring member and the retainer to hold the design surface segmentation mold portion corresponding to the spring member in a predetermined position, and when the tread forming portion is opened, the spring member elastically deforms to allow the design surface segmentation mold portion to rotate relative to the retainer.

[0018] The tire manufacturing method disclosed herein is a tire manufacturing method that produces tires by vulcanizing an unvulcanized raw tire using a mold for forming a tire. The mold includes an annular tread forming portion, which is divided into a plurality of circumferentially arranged segments and configured to open and close by radially moving each of the segments. When the tread forming portion is opened by radially moving each of the segments outward, the tire is demolded from the tread forming portion while each of the plurality of design surfaces of the mold portions arranged circumferentially in the segments rotates about a rotatable axis parallel to the axis of the tread forming portion.

[0019] The effects of the invention

[0020] This disclosure provides a mold for forming a tire and a tire production method that can reduce the undercut resistance of the tread caused by protrusions during tire demolding. Attached Figure Description

[0021] In the attached diagram:

[0022] Figure 1 It is a cross-sectional view of a mold for forming a tire according to an embodiment of the present disclosure, shown in a front view;

[0023] Figure 2 It is shown in the plan view. Figure 1 The figure shows a cross-sectional view of the tread forming part.

[0024] Figure 3 The diagram shown in the front view depicts the opening of the mold used to form the tire. Figure 1 The diagram shows a cross-sectional view of a mold used to form a tire.

[0025] Figure 4 The diagram shows the tread forming section when opened. Figure 1 The figure shows a cross-sectional view of the tread forming part.

[0026] Figure 5 It is shown in the front view. Figure 1 The diagram shows an enlarged cross-sectional view of the main structure of the mold used to form the tire;

[0027] Figure 6 It is in the plan view Figure 5 The diagram shows a segmented cross-sectional view.

[0028] Figure 7 It's a diagram. Figure 6 The diagram shows a detailed cross-sectional view of the spring component; and

[0029] Figure 8 The tire demolding process shown in the plan view Figure 5The diagram shows a cross-sectional view of one segment. Detailed Implementation

[0030] By way of example, a mold for forming a tire and a tire production method according to embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. In this regard, common components and parts appearing in the drawings have the same reference numerals.

[0031] According to the embodiments of this disclosure Figure 1 The mold 1 shown in the middle diagram is used to form a raw tire 2 from an unvulcanized (pre-vulcanized) synthetic rubber-based raw tire into a predetermined shape while the raw tire is vulcanized.

[0032] In this respect, tire 2 is a hollow tire based on synthetic rubber, which includes a pair of sidewalls 2a, 2b and a tread 2c, and is configured to provide space inside tire 2 for filling with a gas such as air or nitrogen.

[0033] The mold 1 used to form a tire includes a sidewall forming part 10 and a tread forming part 20.

[0034] For example, the sidewall forming part 10 may include an annular lower sidewall forming part 11 fixed to the top surface of the lower container 3 and an annular upper sidewall forming part 12 fixed to the bottom surface of the upper container 4.

[0035] The sidewall forming section 10 can arrange (accommodate) the annular tire 2 or a green tire between the lower sidewall forming section 11 and the upper sidewall forming section 12, with the orientation such that the central axis of the green tire is coaxial with the central axis O of the sidewall forming section 10. The lower sidewall forming section 11 includes a lower sidewall design surface 11a, which is annular around the central axis O and oriented upward. The lower sidewall forming section 11 can form one side of the tire 2 or green tire (in) through the lower sidewall design surface 11a. Figure 1 The outer surface of the tire sidewall 2a (oriented downwards) is also included. Similarly, the upper tire sidewall forming portion 12 includes an upper tire sidewall design surface 12a, which is annular around the central axis O and oriented downwards. Figure 1 The outer surface of sidewall 2b (oriented upwards). Figure 3 As shown, by moving the upper container 4 upward relative to the lower container 3 (in the direction in which the upper container 4 and the lower container 3 move away from each other along the central axis of the tire 2), the sidewall forming section 10 opens, and the tire 2 is demolded from the sidewall forming section 10. By moving the upper container 4 downward as shown... Figure 1 The upper container 4 is initially positioned such that the sidewall forming section 10 in the open configuration is closed to allow the formation of the tire 2 or a green tire.

[0036] In this regard, the configuration of the sidewall forming part 10 can be appropriately modified, and examples of such modifications include opening the configuration of the sidewall forming part 10 by moving the lower container 3 downward relative to the upper container 4.

[0037] The tread forming portion 20 is annular and coaxial with the sidewall forming portion 10, and is arranged to be adjacent to the radially outer sides of the lower sidewall forming portion 11 and the upper sidewall forming portion 12. The inner peripheral surface of the tread forming portion 20, which is oriented radially inward, is the tread design surface 20a, which is the outer peripheral surface used to form the tread 2c of the tire 2.

[0038] like Figure 2 As shown, the tread forming portion 20 is divided into a plurality of segments 21 arranged circumferentially. Each of the segments 21 is arc-shaped in the plan view, and the segments 21 are arranged circumferentially to form the tread forming portion 20, which is an annular mold as a whole. In this embodiment, the tread forming portion 20 is divided into nine segments 21 having the same length in the circumferential direction. In this regard, the number of circumferential divisions of the tread forming portion 20 is preferably, but not limited to, 7 to 13, and can be appropriately varied.

[0039] like Figure 1 As shown, the outer peripheral surface of each segment 21, oriented radially outward, is fixed to the interior of the intermediate container 5 corresponding to each segment 21, and each segment 21 is driven by the intermediate container 5 to move radially about the axis of the tread forming part 20 (central axis O). By moving each segment 21 radially, the tread forming part 20 can be opened and closed.

[0040] More specifically, the outer peripheral surface of the intermediate container 5, oriented radially outward, is provided with a tapered surface 5a, which is inclined such that its outer diameter gradually decreases in the upward direction. An annular outer ring 6, arranged radially outward of the intermediate container 5, is fixed to the bottom surface of the upper container 4. The inner peripheral surface of the outer ring 6, oriented radially inward, is provided with a tapered surface 6a, which is inclined such that its outer diameter gradually decreases in the upward direction. For example, the outer ring 6 is connected to each intermediate container 5 by using a guide member (not shown) to allow the tapered surface 6a to slide along the tapered surface 5a of the intermediate container 5 in the vertical direction.

[0041] As the upper container 4 moves upward relative to the lower container 3, the outer ring 6 moves upward relative to each intermediate container 5, while the conical surface 6a slides along the conical surface 5a of the intermediate container 5. Therefore, as... Figure 3 As shown, each intermediate container 5 moves radially outward about the axis of the tread forming section 20. When each intermediate container 5 moves radially outward about the axis of the tread forming section 20, as... Figure 3 and Figure 4 As shown, each segment 21 is driven by the intermediate container 5 corresponding to each segment 21 and moves radially outward together with the intermediate container 5. Therefore, the tread forming section 20 opens to a position where the tread design surface 20a is separated from the tread 2c of the tire 2 or the green tire. In this respect, the tread forming section 20 can be configured such that, after the tread forming section 20 is opened as described above, the tread forming section 20, suspended by the outer ring 6, moves upward together with the upper container 4 to a position where the formed tire 2 can be removed (relative to...). Figure 3 (The position shown is above the position shown). When the upper container 4 moves down... Figure 1 In the initial position shown, the tread forming section 20 moves downwards to a position adjacent to the lower sidewall forming section 11. Subsequently, the outer ring 6 moves downwards relative to each intermediate container 5, and each intermediate container 5 moves radially inwards about the axis of the tread forming section 20. Therefore, as... Figure 1 and Figure 2 As shown, each segment 21 is driven by the intermediate container 5 corresponding to each segment 21 and moves radially inward together with the intermediate container 5, and the tread forming section 20 is closed to allow the formation of the tire 2 or the green tire.

[0042] As described above, in the mold 1 for forming a tire in this embodiment, the annular tread forming part 20 is divided into a plurality of segments 21 arranged circumferentially, and is configured to open and close by moving each segment 21 radially.

[0043] The opening and closing mechanism of the tread forming part 20 is not limited to the structure using the outer ring 6, but can adopt a variety of structures.

[0044] The mold 1 for forming a tire includes an air bladder 7, which is disposed inside the green tire and inflated by supplying pressurized steam. Furthermore, the mold 1 for forming the tire includes heaters (not shown) for heating the sidewall forming section 10 and the tread forming section 20. The position of the heaters can be appropriately determined.

[0045] like Figure 5 and Figure 6 As shown, in the mold 1 for forming a tire in this embodiment, each of the plurality of segments 21 constituting the tread forming section 20 includes a plurality of design surface dividing mold sections 23, 24, and each of the plurality of design surface dividing mold sections 23, 24 is arranged circumferentially in the segment 21. In this embodiment, each of the plurality of segments 21 includes two design surface dividing mold sections 23, 24.

[0046] In this embodiment, each segment 21 includes a retainer 22. Multiple design surface dividing mold portions 23, 24 are arranged radially inside the retainer 22.

[0047] The retainer 22 is a portion that is fixed to the intermediate container 5 and driven radially outward by the intermediate container 5 when the tread forming section 20 is opened. When the tread forming section 20 is closed, the retainer 22 is driven radially inward by the intermediate container 5. The retainer 22 can be formed, for example, by cutting a block of metal such as low-carbon steel.

[0048] In this embodiment, the retainer 22 is detachably fixed to the intermediate container 5. Therefore, various types of segments 21 with different shapes of the tread design surface 20a can be selectively attached to the intermediate container 5, and thus, the mold 1 for forming the tire is suitable for producing various types of tires 2 with different tread patterns.

[0049] The two design surface dividing mold portions 23 and 24 constitute the tread design surface 20a for forming the tread 2c of the tire 2. Each of the two design surface dividing mold portions 23 and 24 is arc-shaped in plan view, and the surfaces oriented radially inward toward the design surface dividing mold portions 23 and 24 constitute the circumferential dividing portion of the tread design surface 20a. The two design surface dividing mold portions 23 and 24 are in contact with each other at their circumferential end faces. In other words, the tread design surface 20a of the tread forming part 20 is divided circumferentially and provided on the design surface dividing mold portions 23 and 24 provided on each of the plurality of segments 21. Therefore, the tread forming part 20 is divided into 9 pieces in the circumferential direction, and the tread design surface 20a is divided into 18 pieces in the circumferential direction.

[0050] like Figure 5 As shown, each tread design surface 20a provided on the design surface segmentation mold portions 23 and 24 is provided with a plurality of protrusions 25, which protrude radially inward from the tread design surface 20a. The plurality of protrusions 25 are used to form grooves or slits, for example constituting a tread pattern, on the tread 2c of the tire 2 during vulcanization molding. The plurality of protrusions 25 can have various shapes or sizes (lengths) customized to the tread pattern, such as a plurality of protrusions 25 extending along the tire width direction and a plurality of protrusions 25 extending along the tire circumference.

[0051] Preferably, the design surface segmentation mold portions 23 and 24 are formed by casting a metal material with high thermal conductivity, such as aluminum alloy. In this case, for example, rib-shaped or leaf-shaped protrusions 25 made of steel can be provided by integrally forming the design surface segmentation mold portions 23 and 24 with the design surface segmentation mold portions 23 and 24 during casting.

[0052] Each of the design surface segmentation mold sections 23 and 24 is supported by a rotatable shaft 26 parallel to the axis (central axis O) of the tread forming section 20, in a manner that allows it to rotate relative to the retainer 22. When the tread forming section 20 is opened after the tire 2 has been vulcanized, each of the design surface segmentation mold sections 23 and 24 rotates relative to the retainer 22 about the rotatable shaft 26.

[0053] More specifically, each of the design surface segmentation mold sections 23 and 24 is supported by two rotatable shafts 26 parallel to the axis of the tread forming section 20, i.e., two rotatable shafts 26 arranged coaxially with each other along the width direction of the tire 2, in a manner that allows rotation relative to the retainer 22. Each of the design surface segmentation mold sections 23 and 24 is configured to rotate radially inward relative to the retainer 22 about the rotatable shaft 26 from a predetermined position. In this regard, the term "predetermined position" refers to a position in which each of the design surface segmentation mold sections 23 and 24 is in a posture in which the tread design surfaces 20a provided on the design surface segmentation mold sections 23 and 24 are continuously connected to each other in a circumferential arrangement. In the case shown, the rotatable shaft 26 is divided into two parts, one for supporting the upper part of the design surface segmentation mold sections 23 and 24 on the segment 21, and the other for supporting the lower part of the design surface segmentation mold sections 23 and 24 on the segment 21. However, instead of such a rotatable shaft 26, a rotatable shaft 26 that extends through the design surface to divide the mold sections 23, 24 can also be used.

[0054] The design surface dividing mold portion 23 arranged on one circumferential end of segment 21 is preferably configured to be supported on the retainer 22 by a rotatable shaft 26 at a position located on one circumferential end of segment 21 relative to the circumferential center of the design surface dividing mold portion 23. Similarly, the design surface dividing mold portion 24 arranged on the other circumferential end of segment 21 is preferably configured to be supported on the retainer 22 by a rotatable shaft 26 at a position located on the other circumferential end of segment 21 relative to the circumferential center of the design surface dividing mold portion 24.

[0055] In this embodiment, a rotatable shaft 26 corresponding to the design surface dividing mold portion 23 arranged at one circumferential end of segment 21 is arranged at one circumferential end of the retainer 22. A rotatable shaft 26 corresponding to the design surface dividing mold portion 24 arranged at the other circumferential end of segment 21 is arranged at the other circumferential end of the retainer 22. In other words, on one hand, at a position closer to the circumferential end of the retainer 22 than the circumferential center of the design surface dividing mold portion 23, the design surface dividing mold portion 23 is supported by the rotatable shaft 26 in a manner that allows it to rotate relative to the retainer 22. On the other hand, at a position closer to the circumferential end of the retainer 22 than the circumferential center of the design surface dividing mold portion 24, the design surface dividing mold portion 24 is supported by the rotatable shaft 26 in a manner that allows it to rotate relative to the retainer 22.

[0056] Furthermore, in this embodiment, the two design surface dividing mold portions 23 and 24 are formed to include corresponding back plate portions 23a and 24a and corresponding paired side plate portions 23b and 24b, which extend radially inward from both ends of the corresponding back plate portions 23a and 24a along the axis (central axis O). The two design surface dividing mold portions 23 and 24 are supported by rotatable shafts 26 at the corresponding back plate portions 23a and 24b.

[0057] like Figure 6 As shown, the pin member 27 is fixed to the design surface dividing mold parts 23 and 24 at a predetermined distance radially from the rotatable axis 26, and the movement of the pin member 27 is restricted by the slot 28 provided on the retaining member 22. Therefore, the rotation range of the design surface dividing mold parts 23 and 24 around the rotatable axis 26 is limited to a predetermined range. In this respect, the pin member 27 and the slot 28 may not be provided.

[0058] The tread forming section 20 can be configured to include a spring member 29, which is attached between the design surface dividing mold sections 23 and 24 corresponding to the spring member 29 and the retainer 22 to hold the design surface dividing mold sections 23 and 24 corresponding to the elastic member 29 in a predetermined position, and elastically deforms when the tread forming section 20 is opened to allow the design surface dividing mold sections 23 and 24 to rotate relative to the retainer 22. Figure 7As shown, in this embodiment, bolt 30 is fixed to the back side of the design surface dividing mold portions 23 and 24, and spring member 29 is arranged between the head 30a of bolt 30 arranged in the hole 22a provided in the retainer 22 and the bottom wall of the hole 22a of the retainer 22. Spring member 29 is a helical compression spring. Spring member 29 applies force to a portion of the design surface dividing mold portions 23 and 24 at a distance from the rotatable axis 26 in a direction that is directed toward the retainer 22. Therefore, spring member 29 holds the design surface dividing mold portions 23 and 24 in a predetermined position, and when the tread forming portion 20 is opened, spring member 29 elastically deforms (compressively deforms) between the head 30a of bolt 30 and the bottom wall of hole 22a to allow the design surface dividing mold portions 23 and 24 to rotate relative to the retainer 22.

[0059] Next, a method for producing a tire 2 having a predetermined shape by vulcanizing a raw tire using a mold 1 having the above-described structure for forming a tire will be described, that is, a tire production method as an embodiment of this disclosure.

[0060] First, the sidewall forming section 10 and the tread forming section 20 are opened to place the green tire inside the mold 1 used to form the tire. Then, the sidewall forming section 10 and the tread forming section 20 are closed.

[0061] Next, pressurized steam is supplied to the air bladder 7 disposed inside the green tire to inflate the air bladder 7. As a result, the sidewall of the green tire presses against the lower sidewall design surface 11a and the upper sidewall design surface 12a of the sidewall forming section 10, respectively, and the tread presses against the tread design surface 20a of the tread forming section 20. In this case, the sidewall forming section 10 and the tread forming section 20 are heated using a heater, and this heat causes the synthetic rubber constituting the green tire to vulcanize to form a tire 2 with a predetermined shape.

[0062] After the tire 2 is formed, the sidewall forming part 10 and the tread forming part 20 are opened to remove the formed tire 2.

[0063] After the tire 2 has been vulcanized, when each segment 21 is moved radially outward to open the tread forming section 20, the driving force required to resist the tight contact between the tread 2c of the tire 2 and the inner circumferential surface of the tread design surface 20a, and to resist the undercut resistance generated between the tread 2c of the tire 2 and the protrusion 25, is applied to each of the design surface dividing mold sections 23 and 24 via the retainer 22. At this time, each of the two design surface dividing mold sections 23 and 24 in each segment 21 is arranged on one side or the other side of the circumferential direction of the segment 21 or the retainer 22, offset from the circumferential center of the segment 21 or the retainer 22. Therefore, at the position offset from the circumferential center of the retainer 22, the driving force is applied to each of the design surface dividing mold sections 23 and 24. Therefore, when the tread forming section 20 is opened after the tire 2 has been vulcanized, as Figure 8 As shown, each of the design surface-splitting mold sections 23 and 24 is designed to rotate spontaneously (rocking motion) around the rotatable axis 26 in such a way that the end of the side adjacent to the circumferential center of the retainer 22 moves away from the retainer 22 in a radially inward direction.

[0064] As described above, in the tire production method using the mold 1 for forming a tire according to this embodiment, when the tread forming section 20 is opened after the tire 2 has been vulcanized, the tire 2 can be demolded from the tread forming section 20 if each of the design surface dividing mold sections 23 and 24 rotates about a rotatable axis 26 parallel to the axis of the tread forming section 20. Therefore, when the tire 2 is demolded from the tread forming section 20, each of the design surface dividing mold sections 23 and 24 rotates to allow the protrusion 25 to be in a position where the undercut resistance of the tread 2c of the tire 2 caused by the protrusion 25 is reduced. Therefore, the undercut resistance of the tread 2c caused by the protrusion 25 during tire demolding can be reduced.

[0065] Specifically, in this embodiment, a rotatable shaft 26 corresponding to the design surface dividing mold portion 23 arranged at one circumferential end of segment 21 is arranged at one circumferential end of retainer 22. A rotatable shaft 26 corresponding to the design surface dividing mold portion 24 arranged at the other circumferential end of segment 21 is arranged at the other circumferential end of retainer 22. Therefore, when tread forming portion 20 is opened, each of the design surface dividing mold portions 23 and 24 can rotate more reliably relative to retainer 22. Furthermore, each of the design surface dividing mold portions 23 and 24 can rotate in such a way that, at both circumferential ends of retainer 22 where particularly high undercut resistance is generated, the protrusion 25 is in a position where the undercut resistance of the tread 2c of tire 2 caused by the protrusion 25 is reduced. Therefore, the undercut resistance of tread 2c caused by the protrusion 25 during tire demolding can be reduced more effectively.

[0066] Therefore, the mold 1 or tire production method of this embodiment can suppress defects such as permanent deformation and breakage of protrusions 25 in the tread 2c formed by tire 2 due to excessive undercut resistance when tire 2 is demolded from tread forming part 20.

[0067] Furthermore, by rotating each of the design surface dividing mold sections 23 and 24, the tread 2c of the tire 2 gradually demolds from one circumferential end of each of the design surface dividing mold sections 23 and 24. Therefore, external air is gradually introduced between the tread design surface 20a and the tread 2c from both circumferential ends, allowing the tread 2c of the tire 2, which is in close contact with the tread design surface 20a, to more effectively peel off from the tread design surface 20a. Thus, the tire 2 can be demolded from the tread forming section 20 more easily.

[0068] Furthermore, the mold 1 for forming the tire or the tire production method of this embodiment can reduce the undercut resistance of the tread 2c caused by the protrusion 25 when the tire 2 is demolded, and also allows the tread 2c of the tire 2, which is in close contact with the tread design surface 20a, to peel off more effectively from the tread design surface 20a. Therefore, the driving force applied to the segment 21 when the tire 2 is demolded can be reduced, and thus the entire production apparatus including the mold 1 for forming the tire can be miniaturized to reduce production costs.

[0069] Furthermore, the mold 1 or tire manufacturing method of this embodiment for forming the tire can reduce the undercut resistance of the tread 2c caused by the protrusion 25 when the tire 2 is demolded. Therefore, tires 2 with more complex tread patterns can be produced relatively easily. Thus, the production flexibility of tires 2 with complex tread patterns can be improved.

[0070] In the mold 1 for forming a tire according to this embodiment, a rotatable shaft 26 corresponding to the design surface dividing mold portion 23 arranged on one circumferential end of the segment 21 is arranged on one circumferential end of the retainer 22. A rotatable shaft 26 corresponding to the design surface dividing mold portion 24 arranged on the other circumferential end of the segment 21 is arranged on the other circumferential end of the retainer 22. The two design surface dividing mold portions 23 and 24 include corresponding back plate portions 23a and 24a and corresponding paired side plate portions 23b and 24b extending radially inward from both ends of the axial direction of the corresponding back plate portions 23a and 24a, and are supported by the rotatable shaft 26 at the corresponding back plate portions 23a and 24b. Therefore, when the two design surface dividing mold portions 23 and 24 are in a predetermined position, the circumferential end faces of the two design surface dividing mold portions 23 and 24 contact each other to suppress the generation of burrs in the tread 2c of the vulcanized tire 2. Furthermore, when segment 21 is moved radially outward to demold tire 2 from tread forming section 20, each of the design surface dividing mold sections 23 and 24 can rotate spontaneously relative to retainer 22.

[0071] Furthermore, in the mold 1 for forming a tire in this embodiment, the tread forming section 20 includes a spring member 29. The spring member 29 is attached between the design surface dividing mold sections 23 and 24 corresponding to the spring member 29 and the retainer 22 to hold the design surface dividing mold sections 23 and 24 corresponding to the elastic member 29 in a predetermined position. When the tread forming section 20 is opened, the spring member 29 elastically deforms to allow the design surface dividing mold sections 23 and 24 to rotate relative to the retainer 22. Therefore, it is ensured that each of the design surface dividing mold sections 23 and 24 is held in a predetermined position during the vulcanization molding of the raw tire, thereby improving the formability of the tire 2. In addition, when the tread forming section 20 is opened after the tire 2 has been vulcanized, each of the design surface dividing mold sections 23 and 24 can spontaneously rotate relative to the retainer 22 about the rotatable axis 26. Therefore, the undercut resistance of the tread 2c caused by the protrusion 25 during tire demolding can be reduced.

[0072] Example

[0073] As an example, a mold for forming a tire is used, which has the above-described structure, wherein:

[0074] The design of the face-splitting mold is made of aluminum alloy (AC4C) and the difference between the maximum and minimum inner diameters is 35mm;

[0075] The protrusion is made of stainless steel sheet (SUS304 H material) and is 0.3mm thick;

[0076] The retaining element is machined from low-carbon steel (S45C equivalent material);

[0077] When a 100kg load is applied, the spring component deforms by approximately 10mm;

[0078] When the segment moves 16 mm radially outward, each of the design surface segmenting mold sections rotates 5 degrees. The mold used to form a tire is used to form a tire with an inner diameter of 600 mm and a tire width of 255 mm, and the external force required for tire demolding (the driving force applied to the retaining member) is measured. Therefore, in comparison with a comparative example of a tire-forming mold having a non-rotating design surface segmenting mold section, it has been demonstrated that the example tire-forming mold can reduce the external force by approximately 30%.

[0079] Of course, this disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of this disclosure.

[0080] For example, in the above embodiment, each of the plurality of segments 21 includes two design surface dividing mold parts 23, 24; however, each of the plurality of segments 21 may include three or more design surface dividing mold parts.

[0081] Furthermore, in the above embodiment, each segment 21 is provided with a retainer 22, and the two design surface dividing mold parts 23, 24 are supported by a rotatable shaft 26 in a manner that allows them to rotate relative to the retainer 22. However, it is also possible to omit the retainer 22 and support the two design surface dividing mold parts 23, 24 on another component, such as the intermediate container 5, via the rotatable shaft 26.

[0082] Furthermore, in the above embodiment, the retainer 22 of segment 21 is fixed to the intermediate container 5. However, the retainer 22 can be integrated with the intermediate container 5.

[0083] List of reference numerals

[0084] 1. Mold used to form tires

[0085] 2 tires

[0086] 2a sidewall

[0087] 2b sidewall

[0088] 2c tread

[0089] 3 containers

[0090] 4. Container

[0091] 5 intermediate containers

[0092] 5a conical surface

[0093] 6 Outer Ring

[0094] 6a cone surface

[0095] 7 airbags

[0096] 10 Sidewall Molding Section

[0097] 11 Lower tire sidewall molding section

[0098] 11a Lower tire sidewall design

[0099] 12 Upper sidewall molding section

[0100] 12a Upper tire sidewall design

[0101] 20 Tread forming section

[0102] 20a tread design surface

[0103] 21 segments

[0104] 22 Retaining parts

[0105] 22a Hole

[0106] 23 Design of surface segmentation mold section

[0107] 23a Backplate

[0108] 23b Side Panel

[0109] 24-face segmented mold section

[0110] 24a Backplate

[0111] 24b Side panel

[0112] 25. Protrusion

[0113] 26 Rotatable shafts

[0114] 27 Pin Components

[0115] 28 seams

[0116] 29 Spring Components

[0117] 30 bolts

[0118] 30a head

[0119] O Central axis

Claims

1. A mold for forming a tire by vulcanizing an unvulcanized raw tire, the mold comprising: The annular tread forming section is divided into multiple circumferentially arranged segments and is configured to open and close by radially moving each of the segments, wherein... Each of the segments includes: A plurality of design surface segmentation molds, each of which includes a tread design surface for forming the tread of the tire, the plurality of design surface segmentation molds being arranged circumferentially in the segment, and the plurality of design surface segmentation molds being configured to rotate about a rotatable axis parallel to the axis of the tread forming portion when the tread forming portion is opened after the tire has been vulcanized.

2. The mold for forming a tire according to claim 1, wherein, Each of the segments includes: The retainer, when the tread forming section is opened, is driven radially outward by the container, and Each of the plurality of design surface segmentation mold sections is supported by the rotatable shaft in a manner that allows it to rotate relative to the retainer.

3. The mold for forming a tire according to claim 2, the mold comprising: The two design surface segmentation mold parts, wherein, A rotatable shaft corresponding to one of the design surface dividing mold parts is arranged on one circumferential end side of the retainer, and a rotatable shaft corresponding to the other of the design surface dividing mold parts is arranged on the other circumferential end side of the retainer.

4. The mold for forming a tire according to claim 3, wherein, The design surface segmentation mold includes a back plate and a pair of side plates, and is supported by the rotatable shaft at the back plate. The pair of side plates extend radially inward from both ends of the back plate in the axial direction.

5. The mold for forming a tire according to any one of claims 2 to 4, wherein, A spring member is attached between the design surface dividing mold portion corresponding to the spring member and the retainer to hold the design surface dividing mold portion corresponding to the spring member in a predetermined position, and when the tread forming portion is opened, the spring member elastically deforms to allow the design surface dividing mold portion to rotate relative to the retainer.

6. A tire manufacturing method for producing tires by vulcanizing an unvulcanized raw tire using a mold for forming a tire, said mold comprising an annular tread forming portion, said tread forming portion being divided into a plurality of circumferentially arranged segments and configured to open and close by radially moving each of said segments, wherein, When the tread forming part is opened by moving each of the segments radially outward, the tire is demolded from the tread forming part as each of the plurality of design surface dividing mold parts arranged circumferentially in the segments rotates about a rotatable axis parallel to the axis of the tread forming part.

Images