Method for manufacturing tire vulcuring mold

Abstract

Provided is a method for manufacturing a tire vulcanization mold capable of manufacturing a pneumatic tire having an arbitrary sipe shape. The method for manufacturing a tire vulcanization mold comprises: a first step of manufacturing a sipe molded part (7) for forming a sipe in a tread surface by metal modeling based on 3D printing; a step in which the sipe molded article (7) manufactured in the first step is disposed in a first mold (83) for molding a vulcanization mold (sector mold (5)) for forming a tread surface in an embedded state; and a step in which a metal material is introduced into the first mold (83) to mold a vulcanization mold (sector mold (5)) in which the sipe molded article (7) is embedded.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a tire vulcanization mold. Background Art

[0002] A pneumatic tire is manufactured by vulcanizing a green tire in a vulcanization mold. A sipe molding piece for forming the sipes is used in a tire vulcanization mold for manufacturing a tire having sipes on the tread surface. The sipe molding piece is a member different from the mold body of the tire vulcanization mold. For example, Patent Document 1 discloses an example of a sipe molding piece.

[0003] [Prior technical literature]

[0004] [Patent Literature]

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 10-58458 Summary of the invention

[0006] Problems to be solved by the invention

[0007] As described in Patent Document 1, sipe forming parts are often manufactured by sheet metal processing. However, when the thickness of the sipe varies in the sipe depth direction in the design of the sipe, or when the sipe is bent on the tread surface, it is difficult to make the thickness of the sipe forming part into an intended shape by sheet metal processing. Therefore, it is difficult to manufacture a pneumatic tire having an arbitrary sipe shape.

[0008] The present disclosure provides a method for manufacturing a tire vulcanization mold capable of manufacturing a pneumatic tire having an arbitrary sipe shape.

[0009] Solutions to Solve Problems

[0010] The manufacturing method of the tire vulcanization mold disclosed in the present invention includes: a first step of making a sipe forming part for forming a sipe on a tread surface by metal molding based on 3D printing; a step of arranging the sipe forming part made in the first step in a buried state in a first mold for molding a vulcanization mold, the vulcanization mold being used to form the tread surface; and a step of pouring metal material into the first mold to mold the vulcanization mold in a state in which the sipe forming part is buried. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a cross-sectional view showing a tire vulcanization mold according to the first embodiment.

[0012] Figure 2 It is a cross-sectional view of a tire vulcanization mold.

[0013] Figure 3 is a schematic partial top view of a tire tread.

[0014] Figure 4 This is a diagram showing an example of a sipe formed part.

[0015] Figures 5A to 5C The following are schematic cross-sectional views sequentially showing the manufacturing steps of a tire vulcanization mold.

[0016] Figures 6A to 6C The following are schematic cross-sectional views sequentially showing the manufacturing steps of a tire vulcanization mold.

[0017] Figures 7A-7B The following are schematic cross-sectional views sequentially showing the manufacturing steps of a tire vulcanization mold.

[0018] Figure 8 It is a figure which shows the sipe forming part of a modification.

[0019] Description of reference numerals:

[0020] 7: Slot forming parts

[0021] 7C: Thick wall area

[0022] 7D: Thin-walled area

[0023] 7E: Surface

[0024] 71: The first plate-shaped part

[0025] 72: Second plate-shaped part

[0026] 83: First Model

[0027] RD: radial tire

[0028] RD1: Tire radial outer side

[0029] RD2: radial inner side of the tire

[0030] T1: Tread surface

[0031] T4: Slot

[0032] T41: First groove area

[0033] T42: Second groove area

[0034] T43: Bend. DETAILED DESCRIPTION

[0035] Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. Figure 1 It is a cross-sectional view showing a tire vulcanization mold according to the first embodiment. Figure 2 This is a cross-sectional view of a tire vulcanization mold ( Figure 3 (sectional view of part II-II). Figure 3is a schematic partial top view of a tire tread.

[0036] like Figure 1 As shown, the tire vulcanization mold is used to mold the outer surface of the pneumatic tire T. The tire vulcanization mold has an upper side mold 1 and a lower side mold 3 that are paired up and down, an upper bead ring 2 and a lower bead ring 4 that are paired up and down, and a plurality of fan-shaped molds 5 arranged along the tire circumference. The fan-shaped mold 5 is a mold for molding the tread surface T1 of the pneumatic tire T. The plurality of fan-shaped molds 5 can expand and contract along the tire radial direction RD, and move to the radial outer side RD1 of the tire when the mold is opened. The upper side mold 1 and the upper bead ring 2 are configured to be able to move relatively in the up and down direction (AD) relative to the lower side mold 3 and the lower bead ring 4, and move upward (AD1) when the mold is opened. The up and down direction (AD) is consistent with the tire axial direction AD. One side of the tire axial direction AD is the top (AD1), and the other side of the tire axial direction AD becomes the bottom (AD2).

[0037] exist Figure 1 In the figure, the airbag 6 is schematically shown by a dashed line. The airbag 6 includes a rubber elastic body configured in a ring shape that can expand and contract, is arranged on the inner surface side of the pneumatic tire T, and is inflated by the supply of pressurized gas, thereby pressurizing the pneumatic tire T from the inside.

[0038] Next, the sector-shaped mold 5 as a mold for molding the tread surface T1 (i.e., the appearance surface of the tread) of the pneumatic tire T will be described. Figure 2 As shown in FIG. 1 , the sector mold 5 includes a mold body 50 for forming a tread surface T1 and a mold body 50 for forming a sipe T4 (see FIG. 1 ) on the tread surface T1. Figure 3 ) of the knife groove forming part 7. A plurality of knife groove forming parts 7 are core-casted in the mold body 50. The so-called core-casting generally refers to a casting product obtained by flowing molten metal around a dissimilar material to be integrated with the main body. Here, it means that the knife groove forming part 7 is used as an insert and the molten metal is flowed into the fan-shaped mold 5, thereby obtaining the knife groove forming part 7 integrated with the mold body 50.

[0039] The mold body 50 is made of a soft metal such as aluminum (including aluminum alloy). The mold body 50 includes a tread molding surface 50A for molding the tread surface T1. The tread molding surface 50A is provided with a main groove T2 (see FIG. 1 ) for molding the main groove T2 on the tread surface T1. Figure 3 The rib 51 is a rib 51 that protrudes from the tread molding surface 50A and extends in the tire circumferential direction, and is integrally formed with the mold body 50. The tread is divided by the rib 51 to form a tire T3 (see Figure 3 ).

[0040] The sipe forming part 7 is made of a material different from that of the die main body 50, and is preferably made of an iron-based metal from the viewpoint of strength. The sipe forming part 7 is preferably made of stainless steel. Figure 3 ) is provided on the tread surface T1 and can be provided in various shapes. Figure 3 ) is, for example, a groove with a width of 1.5 mm or less. Sipe T4 (see Figure 3 ) can extend along the tire circumferential direction CD or along the tire axial direction AD.

[0041] like Figure 3 As shown in FIG. 1 , the tread surface T1 has a plurality of main grooves T2, lands T3 extending in the tire circumferential direction CD and divided by the main grooves T2, and a plurality of sipes T4 formed in lands T3 and extending in the tire axial direction AD. The sipe forming member 7 in the first embodiment is used to form the sipes T4. Figure 2 and Figure 3 In FIG. 8 , the tire equatorial plane CL is shown by a dashed line.

[0042] Figure 4 1 is a diagram showing an example of a sipe forming member 7. The sipe forming member 7 has a protruding portion from the die body 50 and is used to form the sipe T4 (see Figure 3 ) forming portion 7A, and the embedded portion 7B embedded in the mold body 50. In order to make them easy to distinguish in the drawings, Figure 4 The embedded portion 7B is shown with hatching. Figure 4 As shown, the sipe forming member 7 has a thick-walled portion 7C disposed on the shallow side of the sipe T4, and a thin-walled portion 7D on the deep side for forming the sipe T4. The thick-walled portion 7C is a portion having a thicker wall (larger dimension (width) in the sipe width direction) than the thin-walled portion 7D. The thick-walled portion 7C and the thin-walled portion 7D are formed into a plate-like shape having two straight lines parallel to each other in a cross section in the sipe width direction, and the dimension (width) in the sipe width direction is constant. The thick-walled portion 7C and the thin-walled portion 7D are connected by a curved surface 7E protruding toward the tire radial inner side RD2 in a cross section in the sipe width direction. Thus, compared with the case where the thick-walled portion 7C and the thin-walled portion 7D are connected by a plane in the sipe forming member 7, it is possible to avoid the concentration of deformation, and thus the strength of the sipe forming member 7 can be improved.

[0043] like Figure 3As shown in the figure, the sipe T4 presents a sipe shape on the tread surface T1 in a plan view as three straight line portions connected via two bends T43, and the sipe T4 has a first sipe portion T41 and a second sipe portion T42. The sipe shapes of the first sipe portion T41 and the second sipe portion T42 present on the tread surface T1 in a plan view are straight lines. The second sipe portion T42 is connected to the first sipe portion T41 via a bend T43. The bend T43 can be a curved portion or a bent portion. Figure 3 The shape of the knife groove shown corresponds to Figure 4 As shown in the figure, the sipe forming member 7 has a first plate-shaped portion 71 for forming a first sipe portion T41 in the sipe T4, a second plate-shaped portion 72 for forming a second sipe portion T42 in the sipe T4, and a bending forming portion 73 for forming a bent portion T43 in the sipe T4. The thickness of the first plate-shaped portion 71 is constant, and the thickness of the second plate-shaped portion 72 is constant. The thickness of the first plate-shaped portion 71 and the thickness of the second plate-shaped portion 72 may be the same or different.

[0044] like Figure 4 As shown in the figure, as an example, the dimension D1 of the sipe width direction of the sipe molded member 7 is 0.6 mm or more and 1.5 mm or less. As an example, the dimension D2 of the sipe depth direction of the thin-walled portion 7D with a constant thickness of the sipe molded member 7 is 6.0 mm or more and 6.5 mm or less. As an example, the radius of curvature of the curved surface 7E is 0.5 mm or more and 1.0 mm or less.

[0045] In the first embodiment, the knife groove forming part 7 is produced by metal molding (also called metal stacking molding) based on 3D printing. Metal molding refers to a technology that fuses and stacks metal powders in layers to produce a three-dimensional shape. Examples of metal molding include SLS (Selective laser sintering) and SLM (Selective laser melting), which selectively sinter or melt metal powders on a support plate by irradiating a laser beam, thereby molding layer by layer according to the shape of the object to be molded.

[0046] Figure 4 The slit molded part 7 shown has a first plate-shaped part 71 with a constant thickness and a second plate-shaped part 72 with a constant thickness connected to the first plate-shaped part 71 via a bending molding part 73. It is difficult to manufacture by sheet metal processing, but it can be manufactured by metal molding based on 3D printing. In addition, the slit molded part 7 formed by connecting the thick-walled part 7C and the thin-walled part 7D via a curved surface 7E is difficult to manufacture by sheet metal processing, but it can be manufactured by metal molding based on 3D printing.

[0047] <Method for manufacturing tire vulcanization mold>

[0048] Next, a method for manufacturing a tire vulcanization mold will be described. Figures 5A to 5C , Figures 6A to 6C and Figures 7A-7B Schematic cross-sectional views sequentially showing the manufacturing process of a tire vulcanization mold. Figure 5A As shown in FIG. 1 , a master mold 80 having a tread pattern is manufactured. The master mold 80 has grooves (main grooves T2 and transverse grooves) other than the sipe T4 and is manufactured from non-metallic materials such as gypsum. Figure 5A As shown in FIG. 8 , a retaining groove forming member 81 is attached to the position of the knife groove in the main mold 80. Next, as shown in FIG. Figure 5B As shown in FIG. 8 , rubber is poured in to make a rubber mold 82. A groove for inserting a sipe molding member 7 described later is formed in the rubber mold 82 by holding a groove forming member 81. Next, as shown in FIG. Figure 5C As shown in FIG. 8 , the main mold 80 and the retaining groove forming member 81 are removed from the rubber mold 82. Figure 5A to Figure 5C In parallel with the steps shown in FIG. 1 , the above-mentioned knife groove forming part 7 is produced by metal molding based on 3D printing. Next, as Fig. 6A As shown in the figure, the sipe forming member 7 is inserted into the groove formed by the retaining groove forming member 81 in the rubber mold 82, and Figure 6B As shown in FIG. 1 , plaster is poured into the rubber mold 82 to prepare a first mold 83 (a non-metallic product such as plaster) for forming a vulcanization mold (sector mold 5) for forming the tread surface T1. The sipe molding member 7 is embedded in the first mold 83. Next, when the first mold 83 is completed, as shown in FIG. Figure 6C As shown in FIG. 8 , the rubber mold 82 is removed from the first mold 83. Next, Fig. 7A As shown in FIG. 1 , a metal material such as aluminum is poured into the first mold 83 to form a vulcanization mold (sector mold 5) in which the knife groove molding part 7 is embedded. Figure 7B As shown, the first mold 83 is crushed and removed, thereby obtaining a vulcanization mold (sector mold 5) in which the sipe molded part 7 is core-cast.

[0049] [Modifications]

[0050] (A) In the above embodiment, if Figure 4 As shown in the figure, the thick-walled portion 7C and the thin-walled portion 7D are connected by the curved surface 7E convex toward the tire radial inner side RD2 in the cross section in the sipe width direction, but the present invention is not limited to this. Figure 8 1 is a diagram showing a modified example of a sipe forming member 107. For example, Figure 8As shown, the sipe molding member 107 has a thick portion 7C and a thin portion 7D, and the thick portion 7C and the thin portion 7D are connected by a curved surface 7E that is recessed toward the tire radial outer side RD1 in a cross section in the sipe width direction. Figure 8 The sipe forming member 107 shown forms a U-shaped sipe in a plan view.

[0051] (B) In the above embodiment, the thin-walled portion 7D of the sipe forming member 7, 107 is formed by a straight line in the cross section in the sipe width direction, but the wall surface is not limited to a straight line. For example, a curved surface such as a so-called 3D sipe in which the shape of the sipe changes along the sipe depth may be provided.

[0052] The shape of the sipes can be modified in various ways. For example, the sipes on the tread surface T1 may be straight lines connected via bending points, straight lines and curved lines, straight lines, or wavy lines.

[0053] Furthermore, in the above-described embodiment, the shape of the sipe in plan view does not change in the sipe depth direction, but the shape of the sipe in plan view may be a so-called 3D sipe in which the shape of the sipe changes in the sipe depth direction.

[0054] (C) In the above embodiment, the sector mold 5 is illustrated as an example of the tire vulcanization mold, but it is not limited to a segment mold having the sector mold 5 and can also be applied to a two-piece mold without the sector mold 5. [1]

[0056] As described above, the manufacturing method of the tire vulcanization mold of the first embodiment may also include: a first step of making a sipe forming part 7 for forming a sipe T4 on the tread surface T1 by metal molding based on 3D printing; a step of arranging the sipe forming part 7 made in the first step in an embedded state in a first mold 83 for molding a vulcanization mold (fan-shaped mold 5), which is used to form the tread surface T1; and a step of flowing metal material into the first mold 83 to mold the vulcanization mold (fan-shaped mold 5) in a state in which the sipe forming part 7 is embedded.

[0057] The sipe forming part 7 is produced by metal molding based on 3D printing, so that the sipe forming part 7 with a shape that is difficult to obtain by other methods such as sheet metal processing can be produced. As a result, a vulcanization mold (fan-shaped mold 5) that can mold a tire with an arbitrary sipe shape can be obtained. [2]

[0059] Based on the manufacturing method of the tire vulcanization mold described in the above [1], it can also be that the sipe forming part 7 has a first plate-like portion 71 and a second plate-like portion 72, the first plate-like portion 71 forms the first sipe portion T41 in the sipe T4, and the second plate-like portion 72 forms the second sipe portion T42 in the sipe T4 and is connected to the first sipe portion T41 via a bend T43, and the thickness of the first plate-like portion 71 and the second plate-like portion 72 are constant.

[0060] In order to be able to form the first knife groove part T41 and the second knife groove part T42 connected by the bend T43, it is difficult to make the thickness of the first plate-like part 71 and the second plate-like part 72 constant by sheet metal processing. However, if metal modeling is based on 3D printing, the first plate-like part 71 with constant thickness and the second plate-like part 72 with constant thickness can be formed. [3]

[0062] Based on the manufacturing method of the tire vulcanization mold described in [1] or [2] above, the sipe forming part 7 may include a thick-walled portion 7C arranged on the shallow side of the sipe T4, and a thin-walled portion 7D on the deep side for forming the sipe T4, and the thick-walled portion 7C and the thin-walled portion 7D are connected by a curved surface 7E that protrudes toward the tire radial inner side RD2 or a curved surface 7E that is recessed toward the tire radial outer side RD1 in a cross section in the sipe width direction.

[0063] The curved surface 7E can improve the strength of the sipe forming member 7 .

[0064] The embodiments of the present disclosure are described above based on the drawings, but it should be understood that the specific structure is not limited to these embodiments. The scope of the present disclosure is not shown only by the description of the above-mentioned embodiments but by the technical solutions, and further includes all changes within the meaning and scope equivalent to the technical solutions.

[0065] The structure adopted in each of the above-mentioned embodiments can be adopted in any other embodiment. The specific structure of each part is not limited to only the above-mentioned embodiment, and various modifications can be made within the scope not departing from the gist of the present disclosure.

[0066] For example, the execution order of each process such as actions, sequences, steps and stages in the device, system, program and method shown in the technical solution, specification and drawings is not limited to using the output of the previous process in the subsequent process, and can be implemented in any order. Even if the process in the technical solution, specification and drawings is described by using "first" or "next", it does not mean that it must be executed in this order.

Claims

1. A method for manufacturing a tire vulcanization mold, wherein: The manufacturing method of the tire vulcanization mold comprises: A first step of manufacturing a sipe forming member for forming a sipe on a tread surface by metal molding based on 3D printing; a step of arranging the sipe formed member produced in the first step in a buried state in a first mold for a molding vulcanization mold for forming the tread surface; and The step of pouring a metal material into the first die to mold the vulcanization die in a state in which the sipe molded part is embedded.

2. The method for manufacturing a tire vulcanization mold according to claim 1, wherein: The knife groove forming part has a first plate-shaped portion and a second plate-shaped portion, the first plate-shaped portion forming a first knife groove portion in the knife groove, the second plate-shaped portion forming a second knife groove portion in the knife groove connected to the first knife groove portion via a bend, the thickness of the first plate-shaped portion is constant, and the thickness of the second plate-shaped portion is constant.

3. The method for manufacturing a tire vulcanization mold according to claim 1 or 2, wherein: The sipe forming part has a thick-walled portion arranged on the shallow side of the sipe and a thin-walled portion forming the deep side of the sipe, and the thick-walled portion and the thin-walled portion are connected by a curved surface convex toward the radial inside of the tire or concave toward the radial outside of the tire on a cross section in the width direction of the sipe.

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