Method for manufacturing tire vulcanization mold
By employing 3D printing for metal shaping to create complex sipe molds, the method addresses the challenges of producing tires with intricate sipe shapes, resulting in improved accuracy and versatility in tire vulcanization molds.
Patent Information
- Application Number
- JP2023150504
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-09-15
- Publication Date
- 2025-03-28
AI Technical Summary
Existing methods for manufacturing tire vulcanization molds struggle to produce tires with complex sipe shapes due to difficulties in achieving the intended thickness and shape of sipe molding materials during sheet metal processing.
The method involves using a 3D printer for metal shaping to produce sipogenic molds with complex sipe shapes, which are then integrated into the tire vulcanization mold, allowing for the precise formation of sipes during the vulcanization process.
This approach enables the manufacture of tire vulcanization molds that can produce tires with arbitrary sipe shapes, overcoming the limitations of traditional sheet metal processing and improving the accuracy and complexity of sipe designs.
Smart Images
Figure 2025043160000001_ABST
Abstract
Description
[Technical field]
[0001] The present disclosure relates to a method for manufacturing a tire curing mold. [Background technology]
[0002] Pneumatic tires are manufactured by vulcanizing raw tires in a vulcanization mold. In a tire vulcanization mold for manufacturing a tire having sipes on the tread surface, a sipe molding material for forming the sipes is used separately from the mold body. For example, Patent Document 1 discloses an example of a sipe molding material. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-58458 Summary of the Invention [Problem to be solved by the invention]
[0004] As described in Patent Document 1, sipe molded materials are often produced by sheet metal processing. However, when the thickness of the sipe changes in the depth direction in the design of the sipe, or when the sipe is bent on the tread surface, it is difficult to form the thickness of the sipe molded material into the intended shape by sheet metal processing. Therefore, it is difficult to manufacture a pneumatic tire with an arbitrary sipe shape.
[0005] The present disclosure provides a method for manufacturing a tire vulcanizing mold capable of manufacturing a pneumatic tire having any sipe shape. [Means for solving the problem]
[0006] The manufacturing method of the disclosed tire vulcanizing mold includes the steps of: producing a sipe molding material for forming sipes on a tread surface by metal molding using a 3D printer; placing the sipe molding material produced in the producing step in an embedded state in a first mold for molding a vulcanizing mold for forming the tread surface; and pouring a metal material into the first mold to mold the vulcanizing mold with the sipe molding material embedded therein. [Brief description of the drawings]
[0007] [Figure 1] FIG. 1 is a cross-sectional view showing a tire vulcanizing mold according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a tire vulcanizing mold. [Diagram 3] FIG. 2 is a schematic partial plan view of a tire tread. [Figure 4] FIG. 2 is a diagram showing an example of a sipe molding material 7. [Diagram 5] 5A to 5C are schematic cross-sectional views sequentially showing the manufacturing process of a tire vulcanizing mold. [Figure 6] 6A to 6C are schematic cross-sectional views sequentially showing the manufacturing process of a tire vulcanizing mold. [Figure 7] 7A and 7B are schematic cross-sectional views sequentially showing the manufacturing process of a tire vulcanizing mold. [Figure 8] 11 is a diagram showing a modified example of a sipe molding material 107. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0008] Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing a tire vulcanizing mold according to the first embodiment. Fig. 2 is a cross-sectional view of the tire vulcanizing mold (a cross-sectional view of the II-II portion in Fig. 3). Fig. 3 is a schematic partial plan view of a tire tread.
[0009] As shown in FIG. 1, the tire curing mold molds the outer surface of the pneumatic tire T. The tire curing mold has an upper side mold 1 and a lower side mold 3 that are paired vertically, an upper bead ring 2 and a lower bead ring 4 that are paired vertically, and a plurality of sectors 5 arranged in the tire circumferential direction. The sectors 5 are molds for molding the tread surface T1 of the pneumatic tire T. The plurality of sectors 5 are displaceable in the tire radial direction RD, and move to the tire radial outer side RD1 when the mold opens. The upper side mold 1 and the upper bead ring 2 are configured to be movable in the up-down direction (AD) relative to the lower side mold 3 and the lower bead ring 4, and move upward (AD1) when the mold opens. The up-down direction (AD) coincides with the tire axial direction AD. One side in the tire axial direction AD is the upper side (AD1), and the other side in the tire axial direction AD is the lower side (AD2).
[0010] 1, the bladder 6 is diagrammatically shown by a dashed line. The bladder 6 is configured to include a toroidal rubber elastic body that can expand and contract, and is disposed on the inner surface side of the pneumatic tire T. The bladder 6 is inflated by the supply of pressurized gas to pressurize the pneumatic tire T from the inside.
[0011] Hereinafter, a sector 5, which is a mold for molding the tread surface T1 (i.e., the design surface of the tread) of a pneumatic tire T, will be described. As shown in FIG. 2, the sector 5 has a mold body 50 for forming the tread surface T1, and a sipe molding material 7 for forming sipes T4 (see FIG. 3) on the tread surface T1. A plurality of sipe molding materials 7 are cast-into the mold body 50. Cast-in generally refers to pouring molten metal around a different material to obtain a casting integrated with the main body, and here refers to pouring molten metal using the sipe molding material 7 as an insert to obtain a sector 5 in which the sipe molding material 7 is integrated into the mold body 50.
[0012] The mold body 50 is made of a soft metal such as aluminum (including aluminum alloy). The mold body 50 has a tread molding surface 50A for molding the tread surface T1. The tread molding surface 50A is provided with ribs 51 for molding main grooves T2 (see FIG. 3, i.e., circumferential grooves) on the tread surface T1. The ribs 51 are convex and extend in the tire circumferential direction protruding from the tread molding surface 50A, and are formed integrally with the mold body 50. The ribs 51 define the tread, and lands T3 (see FIG. 3) are formed.
[0013] The sipe molding material 7 is made of a material different from that of the mold body 50, and is preferably made of an iron-based metal from the viewpoint of strength, etc. The sipe molding material 7 is preferably made of stainless steel. The sipes T4 (see FIG. 3) are provided on the tread surface T1 and may have various shapes. The sipes T4 (see FIG. 3) are grooves having a width of, for example, 1.5 mm or less. The sipes T4 (see FIG. 3) may extend in the tire circumferential direction CD or in the tire axial direction AD.
[0014] As shown in Fig. 3, the tread surface T1 has a plurality of main grooves T2, lands T3 that are defined by the main grooves T2 and extend in the tire circumferential direction CD, and a plurality of sipes T4 that are formed on the lands T3 and extend in the tire axial direction AD. The sipe molding material 7 in the first embodiment is for forming the sipes T4. In Fig. 2 and Fig. 3, the tire equatorial plane CL is indicated by a dashed line.
[0015] FIG. 4 is a diagram showing an example of the sipe molding material 7. The sipe molding material 7 has a molding portion 7A that protrudes from the mold body 50 to mold the sipe T4 (see FIG. 3), and an embedded portion 7B that is embedded in the mold body 50. In order to easily distinguish between them in the drawing, the embedded portion 7B is hatched in FIG. 4. As shown in FIG. 4, the sipe molding material 7 has a thick portion 7C that is disposed on the shallow side of the sipe T4, and a thin portion 7D that molds the deep side of the sipe T4. The thick portion 7C is a portion that is thicker (has a larger dimension (width) in the sipe width direction) than the thin portion 7D. The thick portion 7C and the thin portion 7D are formed as straight lines in a cross section in the sipe width direction, and have a constant dimension (width) in the sipe width direction. The thick portion 7C and the thin portion 7D are connected by a curved surface 7E that is convex toward the tire radial inner side RD2 in a cross section in the sipe width direction. This makes it possible to avoid concentration of strain compared to when the thick portion 7C and the thin portion 7D of the sipe molding material 7 are connected by a flat surface, thereby making it possible to improve the strength of the sipe molding material 7.
[0016] As shown in FIG. 3, the sipe T4 has a sipe shape that appears on the tread surface T1 in a plan view, in which three straight line portions are connected via two bent portions T43, and the sipe T4 has a first sipe portion T41 and a second sipe portion T42. The second sipe portion T42 is connected to the first sipe portion T41 via the bent portion T43. The bent portion T43 may be a curved portion or a bent portion. In response to the sipe shape shown in FIG. 3, as shown in FIG. 4, the sipe molding material 7 has a first plate-shaped portion 71 that molds the first sipe portion T41 in the sipe T4, a second plate-shaped portion 72 that molds the second sipe portion T42 in the sipe T4, and a bent molding portion 73 that molds the 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.
[0017] 4, the dimension D1 of the sipe molding material 7 in the sipe width direction is, for example, 0.6 mm or more and 1.5 mm or less. The dimension D2 of the constant-thickness thin portion 7D of the sipe molding material 7 in the sipe depth direction is, for example, 6.0 mm or more and 6.5 mm or less. The radius of curvature of the curved surface 7E is, for example, 0.5 mm or more and 1.0 mm or less.
[0018] In the first embodiment, the sipe molding material 7 is produced by metal modeling (also called metal additive manufacturing) using a 3D printer. Metal modeling refers to a technology for fusing and stacking metal powder layer by layer to produce a three-dimensional shape. Examples of metal modeling include SLS (Selective laser sintering) and SLM (Selective laser melting), in which metal powder is selectively sintered or melted on a support plate by irradiation with a laser beam, thereby forming a layer by layer according to the shape of the object to be molded.
[0019] 4, having a first plate-like portion 71 of constant thickness and a second plate-like portion 72 of constant thickness connected to the first plate-like portion 71 via a bent portion 73, is difficult to produce by sheet metal processing, but can be produced by metal molding with a 3D printer. Also, the sipe molded material 7 in which a thick portion 7C and a thin portion 7D are connected by a curved surface 7E is difficult to produce by sheet metal processing, but can be produced by metal molding with a 3D printer.
[0020] <Manufacturing method of tire curing mold> Next, a method for manufacturing a tire vulcanizing mold will be described. FIGS. 5A-C, 6A-C, and 7A-B are schematic cross-sectional views sequentially showing the manufacturing process of a tire vulcanizing mold. As shown in FIG. 5A, a master mold 80 having a tread pattern is manufactured. The master mold 80 has grooves (main groove T2, lateral grooves) other than the sipes T4, and is manufactured from a nonmetallic material such as gypsum. Next, as shown in FIG. 5A, a holding groove forming member 81 is attached to the position of the sipes in the master mold 80. Next, as shown in FIG. 5B, rubber is poured to manufacture a rubber mold 82. In the rubber mold 82, a groove for inserting a sipe molding material 7 described later is formed by the holding groove forming member 81. Next, as shown in FIG. 5C, the master mold 80 and the holding groove forming member 81 are removed from the rubber mold 82. In parallel with the process shown in FIG. 5A-FIG. 5C, the sipe molding material 7 is manufactured by metal molding using a 3D printer. Next, as shown in FIG. 6A, the sipe molding material 7 is inserted into the groove formed by the retaining groove forming member 81 in the rubber mold 82, and as shown in FIG. 6B, plaster is poured into the rubber mold 82 to produce a first mold 83 (made of a non-metal such as plaster) for molding a vulcanization mold (sector 5) for forming the tread surface T1. The sipe molding material 7 is placed in the first mold 83 in an embedded state. Next, when the production of the first mold 83 is completed, the rubber mold 82 is removed from the first mold 83 as shown in FIG. 6C. Next, as shown in FIG. 7A, a metal material such as aluminum is poured into the first mold 83 to mold a vulcanization mold (sector 5) in a state in which the sipe molding material 7 is embedded. Next, as shown in FIG. 7B, the first mold 83 is crushed and removed to obtain a vulcanization mold (sector 5) in which the sipe molding material 7 is cast.
[0021] [Variations] (A) In the above embodiment, as shown in Fig. 4, the thick portion 7C and the thin portion 7D are connected by a curved surface 7E that is convex toward the tire radially inner side RD2 in a cross section in the sipe width direction, but this is not limited to this. Fig. 8 is a diagram showing a modified sipe molding material 107. For example, as shown in Fig. 8, the sipe molding material 107 may have a thick portion 7C and a thin portion 7D, and the thick portion 7C and the thin portion 7D may be connected by a curved surface 7E that is concave toward the tire radially outer side RD1 in a cross section in the sipe width direction. The sipe molding material 107 shown in Fig. 8 forms a U-shaped sipe in a plan view.
[0022] (B) In the above embodiment, the thin portion 7D of the sipe molding material 7, 107 is formed as 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, the wall surface may have a curved surface, such as a so-called 3D sipe in which the shape of the sipe changes along the sipe depth. The shape of the sipes can be changed in various ways. For example, the shape of the sipes that appear on the tread surface T1 may be a shape in which straight lines are connected via bends, a shape in which a straight line and a curve are connected, a linear shape, or a wavy shape. In addition, in the above embodiment, the sipe shape in plan view does not change in the sipe depth direction, but the sipe shape in plan view may change in the sipe depth direction, which is called a 3D sipe.
[0023] (C) In the above embodiment, the sector 5 is exemplified as an example of a tire vulcanizing mold, but the present invention is not limited to a segmented mold having sectors 5, and can also be applied to a two-piece mold not using sectors 5.
[0024] [1] As described above, the manufacturing method of the tire vulcanizing mold of the first embodiment may include the steps of producing the sipe molding material 7 for forming the sipes T4 on the tread surface T1 by metal molding using a 3D printer, placing the sipe molding material 7 produced in the producing step in an embedded state in a first mold 83 for molding a vulcanizing mold (sector 5) for forming the tread surface T1, and pouring metal material into the first mold 83 to mold the vulcanizing mold (sector 5) in a state in which the sipe molding material 7 is embedded. Since the sipe molding material 7 is produced by metal molding using a 3D printer, it is possible to produce sipe molding material 7 in shapes that would be difficult to produce using other methods such as sheet metal processing.As a result, it is possible to obtain a vulcanization mold (sector 5) capable of molding tires with any sipe shape.
[0025] [2] In the manufacturing method of the tire vulcanizing mold described in [1] above, the sipe molding material 7 may have a first plate-shaped portion 71 that molds the first sipe portion T41 in the sipe T4 and a second plate-shaped portion 72 that molds the second sipe portion T42 connected to the first sipe portion T41 via a bent portion T43 in the sipe T4, and the first plate-shaped portion 71 and the second plate-shaped portion 72 may have a constant thickness. The first plate-shaped portion 71 and the second plate-shaped portion 72, which are necessary to be able to mold the first sipe portion T41 and the second sipe portion T42, which are connected via the bent portion T43, are difficult to make uniform in thickness using sheet metal processing, but by metal molding using a 3D printer, it is possible to mold the first plate-shaped portion 71 of a constant thickness and the second plate-shaped portion 72 of a constant thickness.
[0026] [3] In the method for manufacturing a tire vulcanizing mold described in [1] or [2] above, the sipe molding material 7 may have a thick portion 7C arranged on the shallow side of the sipe T4 and a thin portion 7D that molds the deep side of the sipe T4, and the thick portion 7C and the thin portion 7D may be connected by a curved surface 7E that is convex toward the inner side RD2 of the tire radial direction or a curved surface 7E that is concave toward the outer side RD1 of the tire radial direction in a cross section in the sipe width direction. The curved surface 7E can improve the strength of the sipe molding material 7.
[0027] Although the embodiments of the present disclosure have been described above based on the drawings, the specific configurations should not be considered to be limited to these embodiments. The scope of the present disclosure is indicated not only by the description of the above-mentioned embodiments but also by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.
[0028] The structures employed in the above-described embodiments may be employed in any other embodiment. The specific configurations of the components are not limited to the above-described embodiments, and may be modified in various ways without departing from the spirit of the present disclosure.
[0029] For example, the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings, can be arbitrary, as long as the output of a previous process is not used in a subsequent process. Even if the flow in the claims, specifications, and drawings is described using "first," "next," and the like for convenience, this does not mean that it is essential to execute the processes in this order. [Explanation of symbols]
[0030] 7: Sipe molding material 7C: Thick part 7D: Thin area 7E: Curved surface 71: First plate-shaped part 72: Second plate-shaped part 83: Type 1 RD: Tire radial direction RD1: Tire radial outer side RD2: Tire radial inner side T1: Tread surface T4: Sipe T41: First sipe area T42: Second sipe area T43: Bent section
Claims
1. A step of producing a sipe molding material for forming a sipe on a tread surface by metal molding using a 3D printer; A step of placing the sipe molding material prepared in the preparing step in an embedded state in a first mold for molding a vulcanization mold for forming the tread surface; and pouring a metal material into the first mold to mold the vulcanization mold with the sipe molding material embedded therein.
2. 2. The method for manufacturing a tire vulcanizing mold according to claim 1, wherein the sipe molding material has a first plate-like portion that molds a first sipe portion in the sipe and a second plate-like portion that molds a second sipe portion in the sipe that is connected to the first sipe portion via a bent portion, and the first plate-like portion has a constant thickness, and the second plate-like portion has a constant thickness.
3. 3. The method for manufacturing a tire vulcanizing mold according to claim 1 or 2, wherein the sipe molding material has a thick portion disposed on a shallow side of the sipe and a thin portion molding a deep side of the sipe, and the thick portion and the thin portion are connected by a curved surface that is convex toward the inside in the tire radial direction or a curved surface that is concave toward the outside in the tire radial direction in a cross section in the sipe width direction.
Citation Information
Patent Citations
Aggregate, tire forming metal mold using aggregate, and manufacture thereof
JP1998058458A
Cited By
control device
CN122782948A