JP2001334531A - Method for manufacturing tire mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a tire mold, using a casting mold directly manufactured without requiring a process of master model, rubber mold and casting mold reveral. SOLUTION: In the method for manufacturing the tire mold, a gypsum casting mold is manufactured by processing a gypsum material from which combined water is removed by drying up to at least a gypsum hemihydrate (CaSO4.1/2H2 O) state to be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a tire mold for use in manufacturing a tire.

[0002]

2. Description of the Related Art Conventionally, tire molding dies are often manufactured by casting. This is because the design of a tire molding die (tire) is complicated and often has a shape having many sharp corners and thin projections called blades.

[0003] There are roughly two types of tire molding dies.
There are different types of mold splitting methods. One is a vertically integrated type, which is divided into 7 to 11 in the circumferential direction. The other is a method in which the upper and lower parts are not divided in the circumferential direction but in the central axis direction (direction perpendicular to the tire radial direction). This is a method in which the upper and lower parts are divided into two parts.

[0004] In general, a tire design often constitutes 360 ° by combining a plurality of types of "pitch" designs in which a basic design shape is enlarged or reduced in the circumferential direction. This is a technique for preventing noise generation due to tire resonance.

FIG. 2 is a schematic view showing a method of manufacturing a conventional upper and lower split type tire molding die. Master model 3 (Fig. 2) made of easy-to-process materials such as gypsum and resin
(A)), a rubber mold 4 is inverted (FIG. 2 (b)), and then inverted into a mold 5 made of a material such as gypsum (FIG. 2).
(C)). The mold 5 is dried (fired) for one round (360
2), and the mold 5 is assembled in a ring shape (FIG. 2 (e)). Next, the mold 5 is surrounded by a casting frame 7, and the molten alloy 8 is poured between the casting frames 7 and cast (FIG. 2).
(F)) After that, the casting 11 is processed into a predetermined outer peripheral shape (FIG. 2 (g)), and the tire molding die 12 is produced. The tire molding die 12 is used after performing upper and lower mold matching (FIG. 2 (h)). It should be noted that basically the same steps are used in the case of manufacturing a vertically integrated tire molding die.

[0006]

SUMMARY OF THE INVENTION In the above-described method for manufacturing a tire molding die by casting, basically, 360
It is sufficient to make all prototypes for ° °, for example,
In order to perform fine design processing, unless the processing feed amount and processing speed are slowed down, problems such as breakage of a processing tool are likely to occur, and therefore, there is a problem that processing time is required. This depends on the strength characteristics of the material used for the master model, but in order to use it as a master model, at least the strength characteristics that can withstand the subsequent rubber inversion process are necessary, Has limitations.

In addition, there is a problem that the number of rubber molds that are inverted from the master model increases, and the manufacturing cost increases. For this reason, usually the size of the master model and
The most efficient manufacturing method will be designed in view of the number of copies in the mold (the number of assembled molds).

However, even in the case described above, there are cases where it is necessary to produce a master model for the entire circumference due to restrictions on the design of the tire, and also when producing a prototype, There is a problem that unless a costly method such as a master model, a rubber mold, a mold inversion, and a mold assembly is used and a costly method is adopted, a desired tire mold cannot be produced.

In order to address these problems, a method of directly manufacturing a tire molding die from a material such as iron or aluminum by machining is also partially adopted. However, as described above, it is difficult to fabricate a semiconductor device having a complicated shape such as a blade shape or the like.

On the other hand, a method of reducing the number of steps such as master model-rubber mold-inversion of a mold and directly machining a gypsum material to produce a mold can be considered.
Normally, a mold made of gypsum material, the gypsum hemihydrate _{(CaSO 4 · 1 / 2H 2} O) state of powder as a raw material, various additives, and used as blended with refractory material, to which water (H ₂ O) is mixed and pulverized and hydrated to produce a cured product. Plaster state at this stage, gypsum CaSO ₄ crystal water H ₂ O to 1 molecule has two molecules bound (CaSO ₄
2H ₂ O), with free water H ₂ O around it. If the gypsum material in this state is machined as it is, there is a problem that the gypsum dust generated by the processing is re-pulverized by the free water and adheres to the surface of the mold to give a rough appearance. Furthermore, gypsum obtained by drying and removing only free water in a mold is completely dihydrate gypsum (CaS
O ₄ · 2H ₂ O), which is the highest strength as a gypsum material and has a problem that it cannot be applied to fine design processing because of its high machining resistance.

Further, in a general method of casting a blade in a tire molding die, since the strength of the casting of an aluminum alloy or the like is insufficient, the blade plate thickness is 0.2 to 0.2 mm. Since it is as thin as about 2.0 mm and the height (depth) of the blade is as high (deep) as 5 to 20 mm, it takes a long time to form a groove having the shape by machining, The tool is easily damaged, and in some cases, the entire shape cannot be machined.

FIG. 5 is a schematic diagram for explaining a conventional method of blade encasing in a tire molding die. The blade cast-in portion 15 is implanted in the rubber mold 4 (FIG. 5).
(C)) Then, at the time of reversal to the mold 5 (FIG. 5 (d)), the blade 14 is embraced by the mold side and is released from the rubber mold 4. Therefore, the blade cast-in portion 15
However, if the rubber mold 4 has an excessively undercut shape or the area is too large compared to the molding surface, the mold 5 is removed from the rubber mold 4 (FIG. 5D). In addition, a problem that the mold 5 is damaged or the blade 14 remains on the rubber mold 4 side is likely to occur. further,
The cast-in portion 15 of the blade has an important role in determining the falling-off strength and the bending deformation strength of the blade in the tire molding die 12, and there is a demand in terms of strength that it is desired to set the blade as large as possible. Despite the existence,
Due to the above-mentioned restrictions, there is a problem that the strength characteristics of the tire mold must be sacrificed.

[0013] Ordinary tire molding dies are often used with a smooth property with an average surface roughness of about 30 μm or less. For the purpose of improving the air discharge characteristics in the mold for the mold and improving the initial performance of the tire, part or all of the surface of the mold for the tire molding is intentionally set to 100 to 100%.
There is also an application in which the material is used after being roughened to about 200 μm. In the conventional method for manufacturing a tire molding die described above, the surface properties of a predetermined portion on the master model surface are changed, or blasting, chemical etching, metal powder or ceramic powder spraying are performed on the tire molding die. The method has been adopted. However, when the skin is roughened on the surface of the master model, when the rubber mold-mold reversal is repeated, the finely rough state changes, or a part that is inconsistent with the rough state at the mold joining surface during the assembly of the mold. There is a problem that appears, and when the skin becomes rough in the process after the manufacture of the tire mold, it is necessary to mask other parts, which is extremely difficult in terms of both skills and number of steps. Has to be performed.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to directly mold a mold without requiring a master model-rubber mold-mold inversion step. An object of the present invention is to provide a method for manufacturing a tire molding die using the mold.

[0015]

Means for Solving the Problems According to the present invention, there is provided a method for manufacturing a tire molding die, comprising drying water of crystallization at least to a state of hemihydrate gypsum (CaSO ₄ .1 / 2H ₂ O). Process the removed gypsum material to make a plaster mold,
There is provided a method for producing a tire molding die, characterized by using the gypsum mold.

In the present invention, it is preferable to subject the gypsum material to processing in advance to obtain a profile surface shape.

Further, in the present invention, it is preferable that the blade is installed after the gypsum mold is provided with a groove having a blade installation shape, and that the blade is cast in the tire molding die. It is preferable that the above-mentioned portion having the surface shape of the tire molding die is fitted into the gypsum mold, and that the portion having the surface shape be cast in the tire molding die.

Furthermore, in the present invention, it is preferable that the gypsum mold is formed in an integral shape that is not divided for one circumference of the tire, and it is preferable that the surface of the gypsum mold is roughened.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following embodiments, and does not depart from the spirit of the present invention. It should be understood that design changes, improvements, and the like can be made as appropriate based on ordinary knowledge of those skilled in the art.

The morphological change of gypsum due to drying starts with gypsum dihydrate (CaSO ₄ .2H ₂ O) + free water (H ₂ O), and then gypsum (Ca ₂ O 4) obtained by drying and removing free water at about 100 ° C.
SO ₄ · 2H ₂ O), hemihydrate gypsum crystal water and partially dried off at about _{120 ℃ (CaSO 4 · 1 /} 2H 2 O), further, III type anhydrous gypsum which all the crystal water is removed at about 180 ° C. (Ca
SO ₄ III). In the present invention, a gypsum mold is produced by processing a gypsum material from which crystallization water has been dried and removed to at least a state of hemihydrate gypsum (CaSO ₄ .1 / 2H ₂ O), and the gypsum mold is used for tire molding. Mold (hereinafter, "mold"
That. ) Is manufactured. What can be machined is
Although this is a state after gypsum, it is difficult to increase the processing efficiency because gypsum has the maximum strength characteristics. Therefore, according to the present invention in which a mold is processed using a gypsum material in a dry state after at least gypsum, it is possible to increase the processing speed of the mold to twice or more the processing speed of the master model.

In a conventional method of manufacturing a mold through a prototype-rubber mold-mould reversal step, when a portion required for a mold is collected from a rubber mold, usually about 30 to 50% of a material of a gypsum material is used. Loss occurs. However, according to the present invention, it is possible to produce a mold using only the minimum necessary gypsum material. Furthermore, since the number of times of the reversal step is small, and since the mold is manufactured by processing the gypsum material in a state where the drying has already been completed and the dimensional variation has been reduced, there is an advantage that the dimensional accuracy of the mold is also improved. .

Since the morphological change between hemihydrate gypsum and type III anhydrous gypsum is reversible due to moisture in the atmosphere, it is dried on type III anhydrous gypsum, cooled to room temperature and left in the atmosphere. By doing so, it will quickly return to the hemihydrate gypsum state. Therefore, even when machining the mold in the state between hemihydrate gypsum and type III anhydrous gypsum, since this phenomenon occurs, it is unclear which state the crystallization water state of gypsum at the time of processing is exactly It is difficult. However, if machining is performed on the gypsum material in which the crystal water has been dried and removed to at least the state of hemihydrate gypsum, there is no problem,
A gypsum material in which the amount of crystallization water is intermediate between hemihydrate gypsum and type III anhydrous gypsum may be used.

Further, in the conventional method, although a rubber mold is used in the intermediate step of inversion, it is not possible to cope with a so-called undercut shape in which a draft angle is extremely reversed in a mold shape. According to this, if the shape is within the range that can be machined, it is possible to cope with a fine tire design having an undercut shape.

On the other hand, from the viewpoint of the construction period, in the conventional method, the steps of forming a prototype, reversing a rubber mold, reversing a mold, drying a mold, and assembling a mold must be performed in series from the time an order is received. Although there is a limit to the shortening of the construction period, according to the present invention, the gypsum material is pre-molded
Since it can be dried and stocked, it is possible to carry out the mold processing immediately, which greatly shortens the construction period. Therefore, the method for manufacturing a tire molding die of the present invention is an epoch-making manufacturing method having four advantages of cost reduction, improvement of dimensional accuracy, expansion of the shape limit, and shortening of the construction period.

[0025] Note that, although the description has been given mainly of a gypsum material as an example of a material constituting the mold, the present invention does not exclude the use of other materials. For example, a calcium silicate material, an ethyl silicate material, etc. A material having heat resistance at the time of alloy casting, such as a ceramic mold material using a system binder, or plasticity capable of being machined may be used.

Further, in the present invention, it is preferable that the gypsum material is previously processed to have a profile surface shape. FIG.
FIG. 3 is a schematic diagram showing a gypsum material in a state where a profile surface shape is created in advance. As described above, since a basic shape such as a profile surface shape is already applied to the gypsum material 1, the machining distance of the mold can be minimized. Can be reduced and the construction period can be shortened.

At this time, as a method of giving a basic shape such as a profile surface shape to a gypsum material serving as a mold, for example, duplication from a rubber mold or a resin mold, processing by a scraping method (sweep method), or the like Can be mentioned. When replicating from a rubber mold or resin mold, a master model for producing the rubber mold or resin mold is required as in the conventional method. Unlike the conventional method, it is possible to cope with the production of a mold having the above-mentioned design, which brings about a total merit. Further, if there is no undercut shape in the basic shape, it is possible to directly produce a mold of a gypsum material for producing a mold from a resin or the like.

FIG. 3 shows a scraping method (sweep method).
FIG. 2 is a schematic diagram illustrating a method for processing a gypsum material according to the present invention. As shown in FIG. 3, the scraping method (sweep method) is a thin plate gauge having a sectional shape of a basic shape material (a sectional shape gauge 1).
This is a method in which a gypsum-like gypsum is appropriately placed in a rotating body shape formed by turning 6), and a gauge is turned, placed, and turned repeatedly to form a material shape. This method
Sectional shape gauge 16 of basic shape material and rotating shaft 1
Since it is sufficient to have the surface plate 18 with 7, it is simpler than a method of copying from a rubber mold or a resin mold.

Further, in the present invention, the blade is installed after the gypsum mold is provided with the blade-shaped groove, and
Preferably, the blade is cast in a tire mold during casting. FIG. 4 is a schematic diagram illustrating a method of installing a blade in a mold and casting the blade in a mold.
A groove 2 for embedding a blade in the surface of the mold 5 by the processing tool 20
1 illustrates a state in which the blade 14 is installed, and the blade 14 is cast in the mold 12 by casting. Therefore, there is an advantage that the blade insert shape can be set relatively freely since the blade embedding groove 21 is directly formed in the mold 5.

Further, since there is no restriction on the undercut shape with respect to the rubber mold of the conventional manufacturing method, it is possible to integrate the blades across the grooves, which was impossible with the conventional method.

In addition, the alignment of the blades extending between the grooves becomes higher, and the number of blades to be manufactured can be reduced.
Cost reduction becomes possible. Also, using the same blade, it is easier to adjust the molding surface height of the blade by changing only the processing groove depth on the mold side,
In other words, the degree of freedom for sharing the blade is increased. Therefore,
In the case of trial production and the like, a greater cost reduction effect can be exhibited.

Further, in the present invention, at least one part of the gypsum mold having the surface shape of the tire molding die is fitted into the gypsum mold, and the tire molding die is formed at the time of casting. It is preferable to cast-mold a portion having a surface shape. Therefore, for example, the blade molding surface portion shape has an undercut shape with respect to the mold,
This is effective when the blade cannot be directly implanted in the mold.

FIG. 6 is a schematic diagram for explaining a method of installing a blade having a flask shape in a mold and casting the blade in a mold. The concave portion 22 for embedding the blade is formed on the surface of the mold 5 by the processing tool 20. Processed (Fig. 6 (a))
Thereafter, the blade piece 23 is installed (FIG. 6B), and the state in which the blade 25 is cast in the mold 12 by casting is shown (FIGS. 6C and 6D). As described above, another small section (blade piece 23) having no undercut shape in the outer peripheral portion is prepared, and is set in the mold 5, so that the undercut such as a flask shape is formed inside the mold 5. Casting the blade 25 having a shape into the mold 12 can be easily realized.

In the case of producing a mold by inverting the mold from the rubber mold according to the conventional method, it is necessary to divide the mold into a plurality of pieces because an undercut occurs due to the tire design. On the other hand, in the present invention, it is preferable that the gypsum mold is formed in an integral shape that is not divided for one circumference of the tire (360 °). FIG. 7 is a schematic diagram for explaining a method of producing a mold having an integral shape. By processing the cylindrical gypsum material 26 (FIG. 7A) or the gypsum material 27 having a profile surface shape (FIG. 7B) in advance, an integrated ring-shaped mold 28 (FIG. 7C) Can be easily produced. Therefore, it is not necessary to cut the mold accurately at a predetermined angle, and it is not necessary to assemble the mold in a ring shape with the diameter and roundness strictly regulated. Further, at the mold joining portion, there is no need to join and fix the molds, and when a blade is present at the mold joining surface, it is not necessary to re-insert the blade after assembling the mold. Further, since there is no joint surface, dimensional defects such as burrs, shifts, and steps do not occur in the mold. Furthermore, the mold resistance to the solidification shrinkage of the molten metal during casting does not vary among individual molds, and therefore, it is possible to produce a mold having high roundness.

On the other hand, in the present invention, it is preferable to apply roughening to the surface of the gypsum mold. Therefore, in order to meet the objectives of creating design specificity, improving the air discharge characteristics in the mold during tire molding, and improving the initial performance of the tire, part or all of the mold surface is intentionally used. The degraded product can be easily manufactured.

For example, when it is desired to roughen only the profile surface, the surface properties can be easily recovered by processing only the entire surface of the mold and then polishing only the groove portion with a cotton swab or the like. This is because hemihydrate gypsum, type III anhydrous gypsum, or a gypsum material in between these have low strength properties, so that the above-described processing can be easily performed.

[0037]

EXAMPLE Next, an example of the present invention will be described.
It goes without saying that the present invention is not limited to the following examples. (Example 1) Width 250mm, length 150mm, thickness 17
Eight pieces of gypsum material for mold of 0 mm were prepared, and 190 ° C. × 24
After drying for hours, the shape and dimensions are as shown in Tables 1 and 2 and FIG. 8 using a 5-axis NC machine.
A mold was produced by performing processing such that the mold becomes a circumference (360 °). After assembling it into a ring shape, a blade of the material and shape shown in Table 3 prepared in advance was placed on the corresponding portion of the mold, and fixed with quick plaster. Thereafter, secondary drying is performed at 180 ° C. until immediately before casting, and the molten AC4C alloy (680
C) to produce a mold shown in FIG. In addition, non-foamed gypsum (produced by Noritake Co., Ltd.) having a gypsum content ratio of 50 w / w% was used as a gypsum material for a mold at a water mixing ratio (water mixing amount / gypsum amount): 50 w / w%. For casting, AC4C (Si: 7%, Cu:
0.8%, Mg: 0.4%, residual Al) were used. The set shrinkage ratio is as follows: diameter: 10/1000, width: 11 /
1000, groove: 20/1000. It was confirmed that the mold produced in this way had a quality comparable to that of the conventional production method. Table 4 shows the dimensional characteristics of this mold.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

[0041]

[Table 4]

(Comparative Example 1) A mold similar to that in Example 1 was manufactured by a conventional manufacturing method (master model-rubber mold-mold inversion ...).
Produced by In addition, Chemwood material (synthetic resin material) is used for the master model material, FMC polysulfide rubber (manufactured by Smooth On) is used for the rubber mold material, and the number of master models is 3 blocks (each about 45 °),
The number of mold reproductions (the number of assembling) was 15 pieces / ring, the mold preparation conditions, the casting conditions, and the like were the same as in Example 1. Table 4 shows the dimensional characteristics of the mold thus manufactured.

Compared to the first embodiment, the dimensional variation increased by about 30%, and about 50% of the total cost of raw materials and man-hours was required in terms of handling costs. In addition, about 30% extra time was required for the construction period.

(Example 2) Instead of the gypsum material for molding used in Example 1, eight gypsum material for molding having a profile shape as shown in Fig. 9 was prepared in advance from the master model. Thereafter, a mold was manufactured in the same operation procedure as in Example 1. Table 4 shows the dimensional characteristics of the mold thus manufactured.

A mold having almost the same quality as in the case of Example 1 could be obtained. In addition, comparing only the number of steps of the mold processing, it was reduced by 50% as compared with the case of Example 1 (manufacturing of a master model for material production and man-hours for duplicating a plaster material for a mold having a profile shape) Since it took about 25% of the man-hour for the mold processing in Example 1, the substantial improvement was about 25%.)

Example 3 Instead of the blade used in Example 1, a flask-shaped blade 25 shown in FIG.
And, produced using this flask-shaped blade,
Using the blade piece 23 shown in FIG. 11, a mold was manufactured in the same operation procedure as in Example 1. As described above, even when the shape of the molding surface of the blade has an undercut shape with respect to the mold, a mold having the same quality as that of the conventional manufacturing method could be manufactured.

(Example 4) Instead of the gypsum material for casting mold used in Example 1, a ring-shaped gypsum material 33 having a profile surface shape as shown in FIG. 12 (b) was used. By processing the same design, an integral ring-shaped mold was produced. This ring-shaped gypsum material 33 was produced by turning a cylindrical gypsum material 32 (FIG. 12A) after removing crystallization water and drying. In addition, the blade was installed similarly to the case of Example 1, and the metal mold was produced by the same operation as Example 1 after that. Table 4 shows the dimensional characteristics of the manufactured mold.
Shown in

A mold having the best dimensional accuracy was able to be manufactured through all the examples. Although the number of manufacturing steps required no mold assembling step as compared with the first embodiment, the total number of steps was almost the same as that of the first embodiment because a step of lathing the ring-shaped gypsum material was added. Was.

Example 5 Non-foamed gypsum (produced by Noritake Co., Ltd.) having a gypsum content ratio of 40 w / w% as a gypsum material for a mold was mixed with water at a water mixing ratio (water mixing amount / gypsum amount): 60 w.
/ W%, 8 mold plaster materials having a profile surface shape are duplicated from the master model in advance, and 8
Thereafter, a mold was manufactured in the same operation procedure as in Example 1. In addition, only the mold joining surface portion was lightly re-cut with a rotary tool again after assembling the mold, thereby alleviating the inconsistency of the surface roughness. The mold produced in this way has a surface roughness of 100 to 15 only in the grooves (bones of the mold) processed by the mold.
0 μm, other parts (parts not processed by mold)
That is, the profile surface had a surface roughness of 20 to 30 μm. When a tire was molded using this mold, it was possible to obtain a product in which only the groove portion was matte in appearance. In addition, the surface roughness of the mold in the case of the mold preparation conditions of Examples 1 to 4 is the mold processing surface part: 25
３０30 μm, unprocessed part of the mold: 15 to 25 μm, almost the same as the surface roughness of the master model.

[0050]

As described above, according to the method for manufacturing a tire molding die of the present invention, a mold is formed by machining a gypsum material in a predetermined dry state and having a predetermined shape in advance. Since it is manufactured, the steps of master model-rubber mold-mould reversal, which are required for manufacturing a conventional tire molding die, can be reduced. Therefore, it contributes to cost reduction of tire production. In addition, the method is applicable to the manufacture of a mold for forming a tire having a special structure such as an undercut, which has been difficult in the past.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a gypsum material in a state where a profile surface shape has been created in advance.

FIG. 2 is a schematic view showing a method for manufacturing a conventional tire-molding mold of a vertical split type.

FIG. 3 is a schematic diagram illustrating a method for processing a gypsum material by a scraping method (sweep method).

FIG. 4 is a schematic diagram illustrating a method of installing a blade in a mold and casting the blade in a mold according to the present invention.

FIG. 5 is a schematic diagram for explaining a conventional method of blade casting in a tire molding die.

FIG. 6 is a schematic diagram illustrating a method of installing a blade having a flask shape in a mold of the present invention and casting the blade into a mold.

FIG. 7 is a schematic diagram for explaining a method for producing an integrated mold.

FIG. 8 is a cross-sectional view showing a design shape and dimensions of a tire molding die.

FIG. 9 is a perspective view showing a gypsum material for a mold having a profile surface shape.

FIG. 10 is a perspective view showing a flask-shaped blade.

FIG. 11 is a sectional view showing a blade piece.

FIG. 12 is a schematic diagram illustrating a method for producing a ring-shaped gypsum material having a profile surface shape.

[Explanation of symbols]

1 ... gypsum material, 2 ... machined part, 3 ... master model,
4 ... Rubber mold, 5 ... Mold, 6 ... Joint, 7 ... Cast frame, 8 ... Molten alloy, 9 ... Backing material, 10 ... Stable plate, 11 ... Casting, 12
... Tire molding die, 14 ... Blade, 15 ... Blade cast-in part, 16 ... Cross-section gauge, 17 ... Rotating shaft, 18 ... Surface plate, 19 ... Gypsum slurry, 20 ... Working tool, 21 ... Blade installation Groove, 22: recess for burying blade, 23: blade piece, 24: gypsum, 25: flask-shaped blade, 26: cylindrical gypsum material, 27: gypsum material with profile surface shape, 28: integrated mold, 29
... Rib, 30 ... Lug, 31 ... Forming surface part, 32 ... Cylindrical plaster material, 33 ... Ring gypsum material.

Claims (6)

[Claims] 1. A method for manufacturing a tire molding die, comprising:
A gypsum mold prepared by processing a gypsum material from which crystallization water has been dried and removed to at least a state of hemihydrate gypsum (CaSO ₄ .1 / 2H ₂ O), and using the gypsum mold, Mold manufacturing method. 2. The method for producing a tire molding die according to claim 1, wherein the gypsum material is preliminarily processed to have a profile surface shape. 3. The method according to claim 1, wherein the blade is provided after the gypsum mold has a blade-shaped groove, and the blade is cast in the tire molding die.
Or the manufacturing method of the metal mold | die for tire molding of 2. 4. A state in which at least one part of the gypsum mold having the surface shape of the tire molding die is fitted into the gypsum mold, and the surface shape is formed on the tire molding die. The method according to claim 1, wherein a portion to be cast is cast. 5. The method for producing a tire molding die according to claim 1, wherein the gypsum mold is produced in an integral shape that is not divided for one circumference of the tire. 6. The method according to claim 1, wherein the surface of the gypsum mold is roughened.