JP3102991B2 - Tire mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire molding die, and more particularly, to a tire having excellent durability and maintainability.
The present invention relates to a tire molding die capable of molding a tire having high dimensional accuracy and good appearance.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional tire molding die.
FIG. 20 (b) shows a vertically divided mold as shown in FIG.
There is known a mold of a split type in a radial direction as shown in the following. In such a mold, a gas such as air sealed between the mold and unvulcanized rubber at the time of tire vulcanization molding is used. A large number of small holes, called vent holes, communicating with the inside and outside of the mold have been formed in order to discharge the outside of the mold.
However, the work of drilling such a vent hole requires skill, and the number of drilling holes increases the number of man-hours.
There was a problem that the manufacturing efficiency of the mold was not sufficient. In addition, the vent hole generates hairy rubber called spew on the surface of the formed tire, and it must be removed. Even if it is removed, a trace is likely to remain on the tire surface, and this trace is likely to remain. Damage the appearance of the tire,
There is a problem that the initial running characteristics of the tire are impaired. Further, if the tire is repeatedly molded using the above-described mold, the spew is cut and remains in the vent hole, or the dirt such as rubber accumulates, and the vent hole may be clogged. It is necessary to clean the mold periodically (every hundred to several thousand moldings), and this cleaning must be performed manually using a drill or the like for all vent holes, and the maintenance of the mold is complicated. There was a problem that is.

To solve such a problem, Japanese Patent Laid-Open Publication No.
Japanese Patent Application Laid-Open No. 3108 and Japanese Patent Application Laid-Open No. Hei 5-220753 disclose a tread forming part 1 for applying a tread pattern to a tire using a segment type tire forming die as shown in FIG. The number of vent holes can be reduced or maintained by dividing and holding by the holder 2 and properly controlling the adjacent distance between the pieces 1 at the time of the mold assembly and providing an air vent space for preventing discharge of rubber. It is disclosed that it can be eliminated. It is also described that dividing the piece 1 to provide the air vent clearance is applicable to a mold as shown in FIG.

[0004]

However, even in the above-described mold in which pieces are divided and arranged adjacent to each other,
Like a normal tire molding die, if the tire is molded hundreds to thousands of times, the rubber component adheres to the mold surface, vent holes, air vent gaps between the pieces, and the resulting tire appearance is impaired or In addition, it is necessary to periodically clean the mold every several hundred to several thousand shots because the air bleeding effect is reduced. Generally, the cleaning of the mold for tire molding is performed by blast cleaning in which powder such as glass beads and iron powder is blown into the mold. To remove dirt such as
It was necessary to remove each piece from the holder and perform blasting.

[0005] In the above-mentioned piece-parting mold, since the pieces are made of an aluminum alloy, they are not sufficiently hard and have poor abrasion resistance. Therefore, these pieces are plastically deformed by the blast cleaning, and FIG. As shown in a) to (c), a corner 1 formed by the molding surface 1a of the piece 1 and the adjacent surface 1b
At c, a sagging phenomenon occurs, and due to the sagging phenomenon, there is a problem that the air vent gap t provided between the pieces 1 is narrowed or closed, and the air vent effect is impaired, and tire molding cannot be performed. In addition, when the pieces 1 having sagging as described above are incorporated into the holder 2, these sagging portions become an obstacle, and it becomes difficult to incorporate a plurality of pieces 1 with a predetermined dimension. Then, when the tire is molded, the roundness of the obtained tire is reduced. Furthermore, the sagging of the pieces 1 causes unnecessary contact between the pieces when the plurality of pieces 1 are arranged adjacent to each other and incorporated into the holder, and there is a problem that the pieces 1 may be damaged.

In addition, as shown in FIGS. 21A to 21C, when sagging occurs in the piece 1, it has conventionally been necessary to remove the sagging manually, which has been complicated. Furthermore, even if the dripping is removed in this way, the dripping newly generated in the removed portion by periodically blast-cleaning the piece 1 increases with each blast cleaning. Therefore, if these progressively thicker sags are to be sequentially removed, FIG.
As shown in (d), a relatively large cutout portion 1d is formed between the pieces 1 and at the end of the piece 1, and if the tire is formed in this state, the cutout portion 1d (and the enlarged gap t) becomes larger. There is a problem that the surface is transferred as a thick line on the surface and the appearance of the obtained tire is impaired. On the other hand, in order to avoid such sagging phenomenon, it is conceivable to produce a piece using a high-strength type aluminum alloy (an aluminum alloy obtained by solution treatment and hardening by aging treatment) as a mold material. Tire molding temperature is about 170 ° C
And almost coincides with the aging temperature of the aluminum alloy.
There is a problem that the aluminum alloy is overaged during tire molding, not only the hardness is reduced, but also the dimensions change with time, and it is difficult to adjust the dimensions between the pieces.

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 provide a tire for tires which has excellent hardness and good durability and can be easily maintained. To provide a mold. Another object of the present invention is to provide a tire molding die capable of molding a tire having high roundness and good appearance.

[0008]

Means for Solving the Problems As a result of diligent research to achieve the above object, the present inventor has found that the above object can be achieved by controlling the hardness of at least a specific corner of a piece within a certain range. Thus, the present invention has been completed. Therefore, the tire molding die of the present invention provides a tread pattern to a product tire, and includes a plurality of generally annular pieces, and a holder for mounting these pieces adjacent to each other in a circumferential direction. In the mold, the piece has a molding surface that provides a part of the tread pattern, an adjacent surface that abuts or approaches another piece, and a back surface that abuts or approaches the holder, A gap for air release is provided between adjacent surfaces, and the Vickers hardness of a corner formed between the molding surface of the piece and the adjacent surface is HV1.
40 to 4000.

[0009]

In the tire molding die of the present invention, the hardness of the corner formed between the molding surface of the piece and the adjacent surface is HV140-4.
000. Therefore, the hardness and wear resistance of the corners are good, and the degree of plastic deformation of the corners during blast cleaning of the mold is extremely small, so that the corners can be prevented from sagging. Therefore, the tire molding die of the present invention does not block the air vent gap provided between the adjacent surfaces of the pieces, and is excellent in durability such as repeated use and cleaning. In addition, since the corners do not sag, the arrangement position of the pieces does not change due to sagging when placing the pieces adjacent to the holder, and good dimensional accuracy can be maintained. Is not reduced.

Hereinafter, the tire molding die of the present invention will be described in detail. The tire molding die according to the present invention includes a plurality of pieces that are annular as a whole, that is, an annular shape that matches the shape of the tire, and a holder to which these pieces can be mounted adjacent to each other. The shape of the holder may be an annular shape, or may be a sector shape obtained by dividing the ring at a predetermined interval. The piece has a molding surface that gives a part of the tread pattern to the tire, an adjacent surface that abuts or approaches another piece, and a back surface that abuts or approaches the holder.

[0011] In the tire molding die of the present invention, the Vickers hardness of the corner formed between the molding surface and the adjacent surface is HV140-4000, preferably HV1.
90-1000. The hardness of this corner is HV140 ~
In order to obtain 4000, the piece itself may be manufactured using a material having such hardness, but the present invention is not limited to this, and heat treatment such as quenching is performed only on the corners, The hardness can be satisfied by providing a high hardness layer by performing a surface treatment only on the surface.
If the hardness of the corners is less than HV140, the sagging occurs and proceeds during blast cleaning, which is not preferable. If the molding surface of the piece is less than HV140, the surface of the molding may be roughened during blast cleaning and the appearance may be impaired. Therefore, it is more preferable to control the piece molding surface to HV140 or more.

The above-mentioned sagging phenomenon can be almost completely avoided by setting the HV to HV 190 or more. However, considering the workability of the piece, the hardness of the piece itself is preferably set to HV 430 or less. However, after the piece is processed, the hardness is increased to HV300 to 400 by performing surface treatment such as quenching (this is effective only for an iron-based alloy), plating, and CVD.
It can be easily improved to zero. In the case of blast processing in a normal tire molding die, HV
About 1000 is sufficient, and from this point, partial quenching (HV300 to 550) and Cr plating (HV100
(Approximately 0) can be easily adjusted to the above hardness range. In addition, it is possible to increase the HV to 1000 or more by these surface treatments, but such excessive surface treatment is economically useless. In addition, about 0.05-
By chamfering with 0.2 mm, the corners can be further prevented from sagging during blast cleaning, and this effect is particularly remarkable when the HV is 190 or less. This chamfering process may be chamfered in the state of the R surface or the C surface, but it is preferable that the chamfering process is performed in an R surface shape with a curvature radius of 0.05 to 0.2 mm.

The material for the piece that satisfies the above hardness range is not particularly limited, and examples thereof include an iron alloy, a copper alloy, and a nickel alloy.
Iron-based alloys are preferred because of their low reactivity with the rubber component, and among iron-based alloys, spheroidal graphite cast steel and carbon steel cast steel are particularly preferable in consideration of castability and strength for precisely casting a molding surface. preferable. As the copper alloy, a BeCu alloy (particularly, 2 to 3% by weight of Be and 0.5 to 1.0% by weight)
Cu alloy containing Co) is excellent in castability, hardness and thermal conductivity, but is highly reactive with the rubber component. Therefore, when this alloy is used, Ni and / or C
r plating is required. In the case of using carbon steel cast steel, considering castability (low melting point) and improvement in hardness, S30C containing 0.4 to 0.5% by weight of carbon is used.
Preferably, the composition is equivalent to S55C.
It is more preferable to use one containing a hardenability improving component such as i, Cr, or Mo.

[0014] By the way, the bone portion and the thin blade-shaped blade portion existing on the molding surface of the piece, that is, the convex portion for forming the tread groove of the tire, are conventionally cast by an aluminum casting or the steel plate is formed by an aluminum blade. It was buried in an aluminum alloy piece ground by casting. The reason for this is that, since the hardness of the aluminum alloy is not sufficient, even if the blade portion is integrally cast from the piece ground, bending or breakage occurs. In addition, it is difficult to say that the bonding strength is sufficient even with the blade portion that is cast as described above,
Along with the fact that the strength of the aluminum alloy itself is not sufficient, when such a blade part exists in the vicinity of several mm from the end face of the sector or when straddling between pieces, the blade part is deformed, There was a problem that the cast aluminum was missing from the cast aluminum casting. Conventionally, in order to avoid such a problem, the position of the blade is changed to 3 mm from the end face of the sector.
The pieces are separated as described above, or the pieces are divided along a curve so that the blade portions do not straddle between the pieces, and there are many restrictions in producing the blade portions. In addition, conventionally, as a method other than the above-mentioned cast-in, the electric discharge machining method (hereinafter, referred to as “hereinafter”)
It is called "EDM". ), Etc., the blade portion is provided by inserting a steel plate into the molding surface of the piece. However, not only the number of steps is increased, but also the bonding strength is insufficient. Also, the EDM itself requires a long time for processing, and is economically disadvantageous.

As described above, in the prior art, various restrictions were imposed on the production of the blade portion. However, according to the present invention, the hardness of the piece production material is controlled, and the blade portion is formed using this material. Casting can be performed, and the blade portion can be formed integrally with the piece base. Since the blade portion is formed integrally with the piece base, the strength is good, and since it can be cast, there is almost no restriction on the position where the blade portion is provided. Therefore, the degree of freedom in designing the mold for tire molding is improved, and a step that requires a long time such as EDM is not required, and the blade portion can be manufactured in a short time.

In the present invention, the hardness of the blade portion is preferably HV of 140 to 550 in Vickers hardness. If the HV is less than 140, the material is easily bent due to insufficient strength, and if it exceeds 550, the toughness is insufficient and the material tends to be chipped. In the case where a thin portion such as a blade portion is applied to the corner portion of the piece, the blade portion or the like is easily worn by blast cleaning.
It is preferably 550. Spheroidal graphite cast steel having the following composition is preferable as a material capable of soundly casting a blade portion having a plate thickness of about 0.5 mm. When casting the blade portion using spheroidal graphite cast steel, HV55
It is necessary to prevent chilling so as not to exceed 0. For this purpose, a carbon content of 3.0 to 3.6% by weight, a silicon content of 2.0 to 2.8% by weight, a graphite spheroidizing agent (Mg) 0.0
A spheroidal graphite cast steel containing 4% or less by weight of copper or nickel which does not promote the chilling and which contains copper or nickel which does not promote the chilling is used as the basic component in which the chilling promoting component is reduced as much as possible by controlling to 15 to 0.04 wt% Is preferred. In order to further improve the hardness and the hardenability, it is preferable to contain molybdenum together with nickel in an amount of 0.2 to 0.4% by weight.

The holder is preferably made of a material having a hardness of HV140 to 430 in order to prevent the holder from being damaged or worn when the pieces are attached or detached. Further, considering that the piece and the holder are heated at the time of forming the tire, by setting the coefficient of thermal expansion of the holder to be equal to or less than the coefficient of thermal expansion of the piece, the mounted and fixed piece can be held at the time of forming the tire. It is preferable to use a material having a small difference in the coefficient of thermal expansion from the material for forming the piece, since it can be more firmly adhered to the piece forming material. This difference in thermal expansion coefficient is approximately 200 ° C. from room temperature.
It is preferable to control the temperature to 5 × 10 ⁻⁶ / ° C. or less until this time.
By controlling the thermal expansion coefficient difference in this way, when arranging a plurality of pieces adjacent to each other, it is possible to save the trouble of adjusting the holder dimensions in consideration of the thermal expansion of the pieces, and when mounting at normal temperature. The roundness of the whole piece is maintained even when the tire is molded. Specifically, iron-based alloys, in particular, spheroidal graphite cast steel, cast iron, and carbon steel cast steel can be preferably used as the holder-forming material.

Next, a description will be given of the air vent gap existing between the pieces. This gap serves to discharge a gas such as air sealed between the mold and the unvulcanized rubber at the time of tire vulcanization molding to the outside of the mold. Not only intentionally provided but also inevitably present between the pieces. For example, a molding surface is cast by manufacturing a piece by a precision casting method using spheroidal graphite cast steel, and as shown in FIG. 17, a direction substantially perpendicular to the molding surface (the center direction of the tire molding die) is set. When the adjacent surface of the piece is laterally machined by the peripheral teeth of the end mill 91 serving as the machining axis, usually Rz 3 to 10
There is a gap defined by the surface roughness of about μm,
Such a gap is sufficient.

This gap can also be created by cutting a part of the adjacent surface of the piece from the molding surface to the back surface or by providing a groove-shaped step. However, in two adjacent pieces, it is sufficient that the adjacent surface of one of the pieces is processed as described above, and the adjacent surfaces of both pieces need not necessarily be processed. The groove depth of this step is preferably 50 μm or less.
If it exceeds μm, the height of the rubber component at the time of molding the tire increases, which is not preferable because the appearance of the product tire is impaired. In addition, it is affected by the surface roughness of the adjacent surface of the piece, but usually 3 μm
The above groove depth is sufficient. However, when the groove depth is 1
If the thickness is 0 μm or less, clogging may occur due to the rubber component that has penetrated into the step being cut off and remaining during release. More preferably, the thickness is 10 μm or more.

As another method of forming the gap,
A method of cutting or blasting all or a part of the adjacent surface of the piece into a state having a processed surface roughness of about 10 to 10 μm average roughness Rz 3 to 50 μm can be given. According to this forming method, since the rubber component is hard to be inserted into the gap, the rubber component is not cut and remains in the gap. However, depending on the material of the rubber component, dirt is accumulated and the gap is easily closed. Therefore, it is preferable to roughen the entire adjacent surface of the piece as described above. Also in this case,
It is sufficient if one of the two adjacent pieces is roughened, and it is not always necessary that both are roughened. In addition, it is preferable to divide the pieces so that at least one such air vent gap is disposed at a portion forming a land area in the tread portion of the tire. Furthermore, if there is a land area that cannot be divided in design on the molding surface of the piece, a small hole that penetrates in the circumferential direction (the direction in which the pieces are arranged adjacently) is provided near the base of the bone, and the adjacent land area is formed. It is also possible to provide an air venting effect by communicating with.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings. (Embodiment 1) FIG. 1 is a perspective view partially showing an embodiment of a tire molding die according to the present invention. FIG. 20 (b)
A plurality of pieces 10 are mounted on a holder sector 20 to constitute a segment 5 as shown in FIG. In this embodiment, while sliding the back surface 13 of the piece 10 and the holding surface 21 of the holder 20 (see FIG. 2), the piece 10 is moved in the circumferential direction indicated by the arrow A in the figure to be mounted on the holder sector 20. belongs to. When the piece 10 is mounted on the holder sector 20, it is preferable to provide a gap of about 0.02 mm between the back surface 13 of the piece and the holding surface 21 of the holder sector from the viewpoint of improving the detachability. For example, when the piece 10 and the holder sector 20 are made of the same material, this gap can be secured by providing a temperature difference of about 20 ° C. Also, the holder sector 2 of the piece 10
The method of fixing to 0 is not particularly limited.
As shown in (a) to (c), at both ends of the segment 5,
This can be performed by counterbore processing the side surfaces of the piece 10 and the sector 20 and fixing them using bolts 60, washers 61, seats 62 and the like. When the seat 62 has elasticity, it can be used more preferably.

The above-mentioned piece 10 forms a tread pattern of the whole tire with all the pieces, and a convex pattern (bone portion and blade portion) for forming a tread pattern on the tire is formed on a molding surface 11 thereof. (Not shown). In addition, pieces with different pattern pitches are often arranged adjacent to each other in order to prevent vibration and noise of the tire during traveling. In this embodiment, S, M, L
Pieces 10 having three types of pitches are arranged in two rows of eight rows (eight pieces). The numbers shown at the upper edge and the lower edge of the holder sector 20 represent the row numbers of the pieces 10.

These pieces 10 are cast by casting a molding surface 11 by a precision casting method such as a ceramic molding method. During the casting, distortion (twisting) of the molding surface 11
Is controlled to 0.15 mm or less, preferably 0.1 mm or less. Next, the other surface (the adjacent surface 12 and the like) is machined with reference to the main part of the molding surface 11 of each piece to maintain the distortion of the molding surface 11, and finally the pieces are assembled into the holder. However, a tire molding die having a roundness of 0.15 mm or less, preferably about 0.1 mm or less can be obtained. The processing of the piece adjacent surface 12 is performed by a flat surface or a curved surface whose processing axis is oriented at an angle corresponding to the pitch dimension of the piece in the central axis direction of the tire molding die (the central direction of the obtained tire). At this time, the piece adjacent surface 12
When is a curved surface, it is preferable that the processing axis is oriented in the direction of the center of the tire mold so as to be horizontal, and that the processing is performed while keeping the above-mentioned angle constant. As a specific processing example of the piece adjacent surface 12, using an NC milling machine, the piece is fixed at an angle corresponding to the pitch dimension of the piece facing the piece forming surface 11, and the Z axis is kept constant. X,
It can be exemplified that the Y-axis is controlled and side processing is performed by the outer peripheral teeth of the end mill. Note that software design for such processing can be easily performed.

The piece 10 obtained by processing as described above
When the pieces 10 are used, when the piece 10 is mounted on the holder sector 20, rattling between the adjacent surfaces 12 and unnecessary gaps between the adjacent surfaces 12 are less likely to occur. Also, with this, piece 10
By making the hardness of HV140 or more, defects such as galling (breakage) between the pieces are less likely to occur, and it is possible to easily obtain a piece having excellent wearability. Further, by applying the above-described curved surface processing to the piece disposed on the end face of the holder sector, the same effect can be obtained at the time of mold clamping during tire molding. The other portion (the back surface, etc.) of the piece 10 is machined using a lathe, a milling machine, or the like so as to match the dimensions of the part held by the holder sector 20 that has been machined. As described above, if the piece 10 is processed,
Even when 100 to 200 pieces 10 are mounted on 7 to 8 holder sectors 20 to form a mold, 0.15 mm
Roundness can be secured.

Referring to FIG. 1, pieces 10 are arranged adjacent to each other by their adjacent surfaces 12 abutting on each other. Can be provided by penetrating from the molding surface 11 to the back surface 13 and typically cutting or grinding by about 0.02 mm. Alternatively, piece 10
0.02 mm between each other (between a part of adjacent surfaces 12)
By inserting a spacer of a certain degree, a clearance for air release can be provided. Further, it is also possible to impart an air bleeding effect by processing a part or the whole of the adjacent surface 12 to a state having a processed surface roughness of about 10 to 10 μm average roughness Rz3 to 50 μm. When the size of the air vent gap is small, the desired air vent effect can be obtained by reducing the pressure from the back surface 13 side of the piece 10. It is preferable that at least one gap for air bleeding as described above is arranged at a portion where a land area is formed in a tread portion of a product tire.

In this embodiment, the molding surface 1 of the piece 10
1 and the adjacent face 12 have a hardness of HV14
It is controlled within the range of 0 to 550. However, piece 1
0 may be configured to satisfy this hardness range. In order to achieve this hardness, the material of the piece 10 may be exemplified by spheroidal graphite cast steel, carbon steel cast steel, a BeCu alloy, or the like. In the case of iron-based alloys, the hardness can be further improved by quenching the corners 11e. For example, the piece 10 is made of spheroidal graphite cast steel, and the corners 11e are quenched at 800 to 900 ° C. so that the hardness of the corners 11e is HV400 to HV5.
To 50. In the present invention, it is sufficient that the corners 11e have a predetermined hardness. Therefore, the piece 10 is made of an aluminum alloy and subjected to a surface treatment such as hard alumite to increase the hardness of the corners 11e by HV.
It may be about 1000.

As described above, the mold of the present embodiment has the corner 1
Since the hardness of 1e is high and the wear resistance is excellent, even if blast cleaning is repeated, as shown in FIGS.
e is less likely to sag. Therefore, in the mold of the present embodiment, it is possible to prevent the gap for the air vent provided between the adjacent surfaces 12 from being closed by the blast cleaning, and this mold has excellent durability against repeated use. Also, piece 1
Since 0 does not sag and is not easily plastically deformed, the dimensional accuracy when the piece 10 is arranged adjacent to the holder sector 20 is excellent, and the roundness of the obtained tire can be improved. Furthermore,
By chamfering the corner portion 11e by about 0.05 to 0.2 mm, sagging can be more favorably avoided, the durability of the mold can be further improved, and the dimension at the time of the above-mentioned adjacent arrangement is improved. The accuracy can be further improved, and the roundness of the tire can be further improved.

Next, the material of the holder sector 20 will be described. The hardness of the holder sector 20 is from HV140 to
430 is preferable, and by controlling the hardness within this range, the holder sector 2 can be used when attaching and detaching the piece 10.
0 can be prevented from being damaged or worn. Considering that the piece 10 and the holder sector 20 are heated to about 170 ° C. during tire molding, a material having a small difference in thermal expansion coefficient from the material of the piece 10 is preferable. It is preferable that the temperature be 5 × 10 ⁻⁶ / ° C. or less from the temperature up to about 200 ° C. By controlling the thermal expansion coefficient difference in this manner, when a plurality of pieces 10 are arranged adjacent to each other, it is possible to save the trouble of adjusting the dimensions of the holder sector 20 in consideration of the thermal expansion of the pieces 10. As a material for forming the holder sector 20, specifically, an iron-based alloy, in particular, a spheroidal graphite cast steel or a carbon steel cast steel can be preferably used. Further, the holding surface 21 of the holder sector 20 is preferably processed to have a surface roughness Rz of 10 μm or less so as not to lower the thermal conductivity with the piece 10. Although the holder sector 20 can be made light by partially hollowing out the holder sector 20, it is necessary to pay attention so as not to reduce the thermal conductivity. From this point of view, it is preferable to insert an aluminum alloy in a lightened portion with a structure that absorbs a difference in thermal expansion or to encapsulate oil.

In the present embodiment, the positioning of the piece 10 and the holder sector 20 is performed as described below. First, on the holding surface 21 of the holder sector 20, three circumferential grooves 22 extending in the circumferential direction A are formed in three steps at upper and lower stages, and a plate-like stopper 30 is provided at a predetermined position of these circumferential grooves 22. Have been. On the other hand, as shown in FIG. 2, a pin hole 14 is formed in the back surface 13 of the piece 10 so as to match the position of the circumferential groove 22, and the diameter of the pin hole 14 is slightly smaller than the width of the circumferential groove 22. Positioning pin 15 having
Is inserted to form a convex portion.

When the piece 10 is mounted on the sector 20, the positioning pin 15 of the piece 10 is moved in the circumferential direction while being guided by the circumferential groove 22, and the height H of the positioning pin 15 and the height of the stopper 30 are adjusted. 5 (a) to 5 (c), the predetermined piece 10 (S, M, L) can be moved to the predetermined position of the peripheral groove 22 by the predetermined stopper. 30 and a predetermined position (1 to
8) (see FIG. 4. In FIG. 4, the symbols a, b, and c attached to the stopper and the pin correspond to the embodiments of FIGS. 5 (a), (b), and (c), respectively. It shall be.). That is, for example, in FIG. 4, the pieces S, S, and M in the first to third rows are distinguished by which circumferential groove 22 guides the pin 15. Also, pieces in the first row, the fourth row, and the seventh row, for example, in which the circumferential grooves 22 to be guided are the same, are distinguished by the relationship between H and I as shown in FIG.
Each piece will stop at a predetermined position. As described above, in the present embodiment, the number of the grooves 22, the depth G of the grooves,
By appropriately changing the height H of the stopper and the height I of the pin, various positioning patterns can be adopted. As described above, in the present embodiment, the corner 1
1e can be prevented from sagging, and the arrangement order of the pieces 10 to be mounted on the sectors 20 can be prevented from being erroneously recognized, and the mounting of the pieces 10 on the sectors 20 can be simply and accurately performed at the time of the mold assembly after washing or the like. .

Next, a modified example of the piece 10 is shown in FIG. In this figure, in the piece 10a, portions of the back surfaces 13a, 13b and 13c are cut, and according to this example, when the piece is mounted on the sector 20, the portion where the piece and the sector 20 slide is removed. It is possible to reduce and reduce the attachment and detachment of the pieces. However, if the area of the relief surfaces 13a, 13b, etc., due to cutting is too large, the heat transfer efficiency between the piece and the sector 20 decreases, and the area of these relief surfaces 13a, etc. It is preferable to control it to be equal to or less than half of the area of the back surface 13 when it comes into complete contact with the entire holding surface 21. A groove 16 as an example of a guide is provided on the back surface of the piece 10a, and the rail 40 is inserted into the groove 16 when the mold is separated.
, And the pieces 10a are moved to the rails 40 so as to be connected in a daisy chain, so that the detached pieces 10a do not fall apart and are convenient. In this case, the groove 16
Is preferably shaped so as to have an undercut as shown in FIG. 7 so that the rail 40 does not come off the groove 16. In addition, as the above guide,
It is not necessary to be a groove, and a hole may be used. Further, if the rail 40 is made of a soft metal wire, for example, a rod made of copper, the rail 40 is changed from the state shown in FIG. 8A to the state shown in FIG. By bending, the molding surface 11 and the adjacent surface 12 of the piece 10a can be exposed, and the cleaning efficiency can be improved. As another method, a piece 1
A method of preparing a wire 41 longer than the total length of 0a and connecting the pieces 10a to each other with the wire 41 can also be exemplified (see FIG. 6).

(Embodiment 2) Another embodiment of the tire molding die of the present invention is shown in FIG. FIG. 9A is a perspective view of a segment similar to the segment 5 shown in the first embodiment.
(b) is a perspective view of a piece 10b used for this segment. In the following, members that are substantially the same as those described above are given the same reference numerals, and descriptions thereof are omitted. The corners 11e and the sectors 20 of the piece 10b satisfy the above differences in hardness and thermal expansion coefficient. The mold shown in the present embodiment is also a mold of the above segment type, but the holder 10 is used to embrace the piece 10b from above and below in the sector 20 by using the holder plates 50, 50 to improve the mounting strength of the piece 10b. . The use of such a holder plate 50
This is suitable for the case where the pieces 10b are arranged in two stages above and below, and can increase the bonding strength of the contact surface 19 above and below the piece 10b. Step 11 of piece 10b
By fitting the holder plate 50 into a, the piece 10b can be pressed in the direction shown by the arrow D in the drawing.
The mounting strength of the piece 10b can be further improved. Further, in the mold of the present embodiment, the mounting / removing direction of the piece 10b is set in the radial direction indicated by the arrow B in the drawing. A convex portion 17 having a predetermined shape is provided at a predetermined position on the back surface 13 of the piece 10b, and a concave portion 24 having a predetermined shape is provided at a predetermined position on the holding surface 21 of the sector 20. The adjacent surface 12 of the piece 10b is processed into a curved surface.

As shown in FIG. 10, in this embodiment, the specific piece 10b is mounted at a specific position of the sector 20 by changing the shape and position of the convex portion 17 and the shape and position of the concave portion 24. That is, the positioning is performed. In this embodiment, unlike the first embodiment, it is not necessary to arrange the pieces in the circumferential direction in order, so that it is not necessary to change the positioning pattern according to the arrangement order of the pieces. Therefore, it is sufficient to select the uneven shape and position corresponding to the type of the pattern pitch of the piece,
In FIG. 10, for example, the pieces in the second row and the seventh row can be replaced. Further, in the present embodiment, since the sliding ratio between the piece 10 and the sector 20 is low, the mounting property is further improved. In the present embodiment, FIG.
Since the pieces 10b in the segment can be simultaneously attached and detached in a state where the fixing is not performed as shown in (1), the workability of separating the mold can be improved. Furthermore, by providing a groove on the back surface of the piece 10b and inserting a rail into this groove, it is possible to avoid the pieces 10b from falling apart during attachment / detachment (see FIG. 6). Furthermore, in this embodiment,
Since the difference between the hardness of the corner portion 11e and the hardness of the sector 20 and the difference in the coefficient of thermal expansion are controlled as described above, the sagging phenomenon can be avoided, the mold life is excellent, and the perfect circle of the obtained tire is obtained. Also excellent. Next, a modification of the present embodiment is shown in FIG. Also in the example shown in the figure, the back surface of the piece 10 is fixed to the sector 20 using the holder plate 50.
With this configuration, the sliding surface can be reduced,
The mold structure can also be simple. Further, by providing a hollow portion 100 inside the sector 20 and sealing oil or the like into the hollow portion 100, the weight is reduced to such an extent that heat transferability is not significantly deteriorated.

(Embodiment 3) FIG. 11 is a perspective view showing another embodiment of a tire molding die according to the present invention.
Is a partial perspective view of a segment, and FIG. 11B is a perspective view of a piece 10c used for this segment. In addition, corner 1
The difference between 1e, the hardness of the sector 20, and the coefficient of thermal expansion is controlled as described above. The mold shown in the present embodiment is also a segment-type mold, but the direction in which the piece 10c is attached and detached is set in the axial direction (vertical direction) indicated by the arrow C in the figure. Therefore, the sliding ratio between the piece 10c and the sector 20 is low, and the mountability is good. Then, the piece 10c and the sector 20
Positioning is performed by appropriately selecting the height h and width x of the vertical groove 18 provided on the back surface 13 of the piece 10c, and the convex portion 25 fitted (guided and locked) into the groove 18. Will be

In this embodiment, since the hardness and the coefficient of thermal expansion of the corners 11e and the sectors 20 are controlled, the sagging phenomenon is extremely unlikely to occur during blast cleaning. The mold has excellent durability and the obtained tire has good roundness. In the present embodiment, FIG.
Since the pieces 10c in the segment can be simultaneously detached and attached in a state where the fixing is not performed as shown in (1), the workability of separating the mold can be improved. Furthermore, peace 1
By inserting the rail 40 into the groove 16 of 0c, the pieces 10c can be prevented from falling apart at the time of attachment / detachment. According to the present embodiment, by lifting both ends of the inserted rail 40 or removing the lower holder, the pieces 10c are simultaneously and instantaneously attached and detached while the sector 20 is attached to the tire vulcanization molding machine main body. Therefore, the desorption property is better than that of Example 2. In the present embodiment, the adjacent surface 12 of the piece 10c is flat, but may be curved.
Can also be divided into upper and lower stages.

(Embodiment 4) FIG. 12 shows another embodiment of the tire molding die of the present invention. The mold shown in this embodiment is a vertically divided mold as shown in FIG.
FIG. 2 (a) is a perspective view showing the mold with a part cut away, and FIG.
(b) is a perspective view showing a piece 10d used for this mold. Note that, also in the present embodiment, the difference between the hardness of the corner portion 11e and the hardness of the sector 20 and the difference in thermal expansion coefficient are controlled as described above. Therefore, the mold life is excellent, and the roundness of the obtained tire is also good. The positioning mechanism in the mold of the present embodiment is basically the same as that of the third embodiment. In the case where the adjacent surface 12 of the piece 10d is curved, the pieces 10d of the entire circumference need to be simultaneously attached and detached.
It is preferable to provide a draft in 3. However, if one of the adjacent surfaces of the pieces is made flat and the pieces are removed first, it is not necessary to attach and detach all the pieces at the same time. Further, as shown in FIG. 13, a cutting surface 13a is provided on the piece 10d, and the piece 10d is formed using the cutting surface 13a.
If they are connected to each other by the wire 41, attachment / detachment can be performed more easily. In this case, it is preferable to connect them in units of about 10 pieces.

(Embodiment 5) FIG. 14 shows another embodiment of the tire molding die of the present invention. FIGS. 15 (a) and (b)
FIG. 15 is a perspective view of the piece shown in FIG. 14. In FIG. 14, this mold employs a form in which the pieces 10e and 10f are held in the sector 20 by using the holder plate 50 as in the mold of the second embodiment. In the figure, the illustrated arrows indicate the direction in which the pieces 10e and 10f are pressed against the sector 20. The corner 11e
And the sector 20 satisfies the above-mentioned hardness range and thermal expansion coefficient difference. Also, as shown in FIG.
Blades 70 which are an example of convex portions for forming tread grooves in the tire are provided on the molding surfaces 11 of e and 10f. These blade portions 70 are made of spheroidal graphite cast steel (C: 3.4% by weight, Si: 2.4% by weight, Mg: 0.4% by weight).
It is integrally cast from the molding surface 11 by a precision casting method (ceramics molding method) using 3% by weight, Cu: 2% by weight, and the remainder Fe, and has a Vickers hardness HV of 250 (piece body is HV240). ) Is controlled.
Therefore, the strength of the blade 70 is good, and the possibility of breakage during tire molding, mold assembly, mold dispersion, and the like is extremely low. Further, as described above, for example, the hardness may be increased to HV 400 to 500 by quenching the corners of the portion straddling the adjacent surface 12 of the blade 70.

When these blades 70 are formed,
In general, it is better to avoid providing the piece at a position straddling the adjacent surface 12 between the pieces. However, in the present invention, since the strength of the blade 70 is good, the thickness is 0.4 to 1.0.
When forming a blade of mm × height 5 to 10 mm, if the width is 5 mm or more, there is no problem in strength, and the possibility of breakage of the blade can be ignored. Therefore, there is almost no restriction on the position where the blade 70 is provided, and according to the mold of the present embodiment, the degree of freedom in design when providing the blade 70 can be improved. The distortion of the tread portion on the molding surface of the piece is controlled to 0.05 mm or less, and the surfaces other than the molding surface are machined by the above-described method. The adjacent surface of the piece is also curved by the above-described method, and the surface roughness at that time is 3 μm, and a gap of 0.02 mm is formed only in a portion corresponding to the land area on one of the adjacent surfaces. to be able to do,
A step is provided.

Further, as shown in FIG.
The positioning pin 15 is provided on the back surface
Is provided, and when the mold is assembled after the mold cleaning, the second embodiment is used.
Positioning is performed as follows. In addition, relief surfaces 13d to 13f are provided on the back surface 13 of the piece 10e to improve the attachment / detachability between the piece and the sector 20, and these relief surfaces also function as air discharge paths. In addition, as for the pieces arranged on the end face of the sector 20, as shown in FIG. 15, it is preferable that the gap 73 does not occur on the adjacent faces of the upper and lower pieces,
For this purpose, a smooth curved surface (preferably a flat surface) having no step may be formed by adjusting the position at which the adjacent surface of the piece 10e or 10f is machined. By treating the end surface of the sector 20 as described above, it is possible to make it difficult to generate galling (breakage, etc.) on the piece adjacent surface when the entire sector is clamped. Pieces 10e and 10f described above
Are used for each of the 60 sectors, and as shown in FIG.
When mounted on the upper and lower sides, the roundness of the whole piece was 0.07 mm. Also, when the gap between pieces adjacent surfaces was measured using a gap gauge,
Except for the part where the step of 0.02 mm was provided and the slit-shaped air vent gap was provided, no gap having a size exceeding 0.01 mm was generated.

(Sag Resistance Test) (Examples 6 to 13, Comparative Examples 1 and 2) Various test pieces having a molding surface produced by a ceramic mold precision forging method and having the material and hardness shown in Table 1. Prepare
As shown in FIG. 16, blast cleaning was performed from the molding surface 11 side. At this time, in each piece, the adjacent surface 12 is set to Rz
The surface was processed so as to have a thickness of 5 μm, and the corner 11e was kept sharp while the other corner 11e ′ was chamfered with a radius of curvature of about 0.1 mm. Also,
Blast cleaning is performed by molding # 100 glass beads on molding surface 11.
The spraying was performed at a pressure of 4 kgf / cm ² for 10 minutes and 20 minutes from a position about 30 cm further away. After such blast cleaning, as shown in FIG. 16 (b), the plastic deformation amounts t ₁ and t ₂ of the corner 11e and the roughness of the molding surface were measured. Table 2 shows the obtained results. In addition,
The blast cleaning for 10 minutes and 20 minutes actually corresponds to about 50 and 100 cleaning times when calculated from the normal cleaning time and the piece area.

[0041]

[Table 1]

[0042]

[Table 2]

As can be seen from Tables 1 and 2, in Comparative Examples 1 and 2 relating to the Al-based alloy, t ₁ already became 0.02 mm or more after 10 minutes of blast cleaning.
Even if a gap for air release of m is provided, the gap is closed by the blast cleaning, which means that the air release effect is almost lost. In this case, in order to recover the air bleeding effect, it is necessary to perform processing such as grinding the sagged portion, which is troublesome. The surface roughness of the molding surface 11 is also Rz20 or more, and such surface roughness is transferred to a product tire. On the other hand, in Examples 6 to 10, even in Example 6, which is the lowest in hardness, by slightly chamfering the corners, the deformation amount t ₁ does not reach the extent that the air bleeding effect is hindered. Further, in the embodiment having an HB of more than 200, t ₁ is 0.01 or less even if the corner remains sharp, which is not a degree that adversely affects the air venting effect. Further, those with a chamfering exceeding HV210 and those exceeding HV320 (no chamfering) hardly deform due to sagging. Example 11 other than iron-based alloys
In this example, the same effect as that of the ninth embodiment is obtained by subjecting the BeCu alloy to solution treatment and age hardening. On the other hand, in Example 13 obtained by performing hard Cr plating on the FCD-400 of Example 6, the hardness of the plated portion was HV900, and the deformation due to blast cleaning hardly occurred. Further, the surface roughness of the molding surface 11 did not exceed Rz 15 μm in Examples 6 to 13, and particularly in the case of exceeding HV 210, it was Rz 10 μm or less, and good results were obtained.

(Rubber Removal Test) (Example 14 and Comparative Example 3) Pieces made of FCD-600 (spheroidal graphite cast steel) or 6061-T6 (Al alloy) were prepared (see FIG. 17). Table 3 on adjacent surface 12
A gap for air release was provided under the conditions shown in (1). Each of the obtained pieces (16 pieces) was mounted on a rubber vulcanizing tester shown in FIG. Using this tester, vulcanization molding and blast cleaning were performed by the following methods. At this time, the state of air trapping in the region 11R closed by the bone portion 72 (the degree of deterioration of the air venting effect due to the adhesion of dirt such as rubber) and the height of rubber rubbing were evaluated. As shown in FIG. 17, the piece used above has a bone portion 72 on the molding surface 11, and the adjacent surfaces 12L (left side toward the molding surface 11) and 12R (right side) are in principle Is cut at Rz 1 μm by side processing using the outer teeth of the end mill 91, and the corners 11e and 11e '
The chamfer of 5 mm is made.

[Method of Vulcanization Molding and Blast Cleaning] Each of the pieces obtained as described above was used as a piece No. The vulcanization molding tester shown in FIG. 18 is mounted in accordance with the above, the heater 80 is operated, and the surface temperature of each piece is set to 17 through the base 81.
Heated to 0 ° C. Next, after the unvulcanized rubber sheet 83 generally used for tire molding is brought into contact with each piece,
The sheet 83 was uniformly pressed in the direction of arrow E so that the pressure was changed from the normal pressure to 20 kg / cm ^{2 in} about 15 seconds, and the sheet 83 was held for 10 minutes to perform molding. At this time, the pressure on the back side of the piece was reduced to 700 mmHg by a pressure reducing hole (not shown) provided in the frame 84 as necessary. Molding was performed 10 times each in accordance with the presence or absence of reduced pressure, and the initial air release effect was evaluated. The obtained results are shown in Table 4. Next, each piece was detached from the vulcanization molding tester, and blasted for about 10 minutes under the same conditions as in Examples 6 to 13. Thereafter, each piece was mounted again on the vulcanization molding test machine, and molding was performed up to 2,000 times without pressure reduction in principle. Table 5 shows the obtained results.

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

[Table 5]

According to Tables 3 and 4, in the initial state where the pieces are not dirty and the blast cleaning is not performed, when the substantial gap between the pieces exceeds about 50 μm, the height at which the rubber comes out is reduced. It can be seen that the state exceeds 0.5 mm. On the other hand, when a vent hole is provided as in the prior art, the protrusion is about 10 mm, which impairs the appearance of the tire (see piece No. 15). Also, regarding the presence or absence of air pockets, etc., under molding conditions that do not decompress,
When the substantial gap between the pieces becomes about 3 μm or less, the bone 7
In the vicinity of the root of No. 2, a transfer problem is likely to occur. This means that the piece No. with the vent hole 85 is provided. 15 is the same. However, when the pressure was reduced, the transferability was good in any case. In addition, it was also found that the presence or absence of reduced pressure did not significantly affect the height at which the rubber came out.

Next, in order to confirm the influence of the molding conditions on the removal of the rubber, in FIG. 18B, the speed of applying the molding pressure was reduced (from 0 to 20 kg / c for 30 seconds).
m ² ) Molding was performed. As a result, in all the pieces, the protrusion height of the rubber is reduced by about 30%. In Nos. 8 and 9, the hammering height was 0.35 each.
mm and 0.6 mm. On the other hand, the transferability (the transferability of the root of the bone 72) generally tended to slightly decrease. Therefore, although it is possible to suppress the protrusion of the rubber by changing the molding conditions including the material of the rubber, it is possible to reduce the transferability by setting the air vent gap to 0.05 mm. Without lowering
It is possible to set the piercing height of 5 mm or less.

By performing blast cleaning, A
l alloy piece no. In the case of 15 and 16, the molding surface 11 was considerably roughened as compared with the initial state because the hardness was not enough. However, in the case of the iron-based piece having excellent hardness, the gloss of the skin of the molding surface 11 was slightly increased. Hardly changed.

As shown in Table 5, in the 2,000 times molding after the blast cleaning, the piece no. 1 was slightly clogged. Piece No. 2 gaps (about 3μ
m) is considered to be the lower limit of the gap. Piece No. No problems occurred for 3 to 9. In addition, the peace No.
In the case of No. 10, although the depth of the groove is slightly shallow, the rubber is easily cut and remains, but can be solved by chamfering the corner. Piece No. In the case of No. 11, no problem arises if vacuum forming is performed. On the other hand, in the case of the piece No. having the vent hole of the prior art. In the case of No. 15, it can be seen that the rubber is likely to remain in the vent hole because the rubber projection height is too large. In addition, the peace No. In No. 16, sagging occurred due to blast cleaning, and the air bleeding effect was reduced to cause clogging.
In addition, even if the iron-based piece was molded 2,000 times, the rubber surface stains adhered to the molding surface 11 and the skin became rough. However, the dirt could be removed by lightly blast cleaning. In addition, the air bleeding effect was restored in all the iron-based pieces. In addition, the piece No. In No. 12, roughening and dirt on the molding surface 11 were slightly generated.

(Blade Strength Test) (Example 15) FCD-600 and FC of spheroidal graphite cast steel
A piece 10e shown in FIG. 15A was manufactured using D-800. Next, a test piece shown in FIG. 19 was cut out from the obtained piece. The blade 70 is formed by casting, and is made of the same FCD-600 or 800 as the main body 10e. The shape of the blade 70 is 0.5 mm in thickness × 6.0 mm in length (width) × 6 mm in height. The test piece was fixed to a pedestal 86 as shown in FIG. 19, a bending stress was applied to the blade 70 in the direction indicated by an arrow, and the maximum stress at that time was measured. The maximum stress is d in the figure.
Was set to 5 mm or 0.5 mm, and measurement was performed in two ways.

(Comparative Example 4) The material of the main body 10e was made of an Al alloy (AC4C), the blade 70 was made of SUS304, and the insert depth was 4 mm and the locking hole φ1.
Example 1 except that 5 mm was provided and the main body 10e was cast.
The same operation as in step 5 was repeated. Comparing the obtained flexural strength with that of Example 15, the one made of FCD-600 of Example 15 is about 1.3 times that of Comparative Example 4, and the one made of FCD-800 is about 1.3 times that of Comparative Example 4. It was eight times. When d is 0.5 mm, the bending strength does not decrease in Example 15, but in Comparative Example 4, since the Al alloy portion breaks first due to the bending stress, the bending strength decreases to about ２. As described above, in the piece according to Example 15 in which the blade 70 has the predetermined hardness and is cast, the blade 70 has basically the same strength as the material itself of the piece. Therefore, the strength of the blade 70 is good, and even if the blade 70 straddles the pieces, there is relatively no problem. When the blade is provided, the design restriction can be reduced.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to these embodiments.
Various modifications are possible within the scope of the present invention. For example, in the dies of Examples 1 to 5, positioning with the holder 20 is performed, but such positioning is not an essential matter of the present invention, and it is sufficient if the hardness of the corner 11e is satisfied. Further, the dies shown in Examples 1 to 3 and 5 can also be applied to a vertically divided type. Further, Examples 1 and 2
In this mold, the pieces are arranged vertically in two stages, but the pieces may be integrally formed vertically.

[0056]

As described above, according to the present invention,
Since the hardness of at least the specific corner portion of the piece is controlled within a certain range, it is possible to provide a tire molding die that has excellent hardness of the piece, good durability, and easy maintenance. Further, according to the present invention, it is possible to provide a tire molding die capable of molding a tire having high roundness and good appearance.

[Brief description of the drawings]

FIG. 1 is a perspective view partially showing an embodiment of a tire molding die according to the present invention.

FIG. 2 is a perspective view of a piece used for the mold of FIG. 1;

FIG. 3 is a perspective view and a partial cross-sectional view showing a fixed state of a piece and a sector.

FIG. 4 is a schematic diagram showing a positioning relationship between a piece and a sector.

FIG. 5 is an explanatory side view showing a relationship between a stopper height and a pin height.

FIG. 6 is a perspective view showing a modification of the piece.

FIG. 7 is a partial sectional view showing a shape of a groove.

FIG. 8 is a schematic diagram showing a daisy chain connection state of pieces.

FIG. 9 is a partial perspective view showing another embodiment of the tire molding die of the present invention.

FIG. 10 is a schematic diagram showing a positioning relationship between a piece and a sector.

FIG. 11 is a partial perspective view showing another embodiment of the tire molding die of the present invention.

FIG. 12 is a partial sectional view showing another embodiment of the tire molding die of the present invention.

FIG. 13 is a perspective view showing a modification of the piece used for the mold of FIG.

FIG. 14 is a partial side view showing another embodiment of the tire molding die of the present invention.

FIG. 15 is a perspective view showing a piece used for the mold shown in FIG. 14;

FIG. 16 is an explanatory diagram showing a state of blast cleaning.

FIG. 17 is a perspective view showing an example of a piece.

FIG. 18 is a side view and a sectional view of a vulcanization molding test machine.

FIG. 19 is an explanatory sectional view showing a method of measuring bending strength.

FIG. 20 is an exploded perspective view showing an example of a conventional tire molding die.

FIG. 21 is an explanatory cross-sectional view showing the manner of sagging.

FIG. 22 is a perspective view showing a modified example of the tire molding die shown in FIG.

[Explanation of symbols]

5 segments, 10, 10a, 10b, 10c, 10
d-piece, 13 back, 15 positioning pin, 16
Groove, 17 convex, 18 vertical groove, 20 holder sector, 2
1 holding surface, 22 circumferential grooves, 24 concave portions, 25 convex portions, 3
0 stopper, 40 rail, 41 wire, 50 holder stopper, 70 blade

Continuation of the front page (51) Int.Cl. ⁷ identification code FI B29K 105: 24 B29L 30:00 (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 33/00-33/76

Claims (10)

(57) [Claims] Claims: 1. A tire molding die provided with a plurality of pieces that form a ring as a whole and impart a tread pattern to a product tire, and a holder that can be mounted adjacent to the pieces in a circumferential direction. A molding surface that provides a part of the tread pattern, an adjacent surface that abuts or approaches another piece, and a back surface that abuts or approaches the holder, between the adjacent faces of the pieces. A tire molding die having an air vent gap, wherein a Vickers hardness of a corner formed between a molding surface and an adjacent surface of the piece is HV140 to 4000. 2. The tire molding die according to claim 1, wherein said piece is made of an iron-based alloy or a copper-based alloy. 3. The tire molding die according to claim 1, wherein said piece is made of spheroidal graphite cast steel, carbon steel cast steel or beryllium copper alloy. 4. The method according to claim 1, wherein all or a part of the convex portion on the molding surface of the piece is cast.
4. The tire molding die according to any one of Items 1 to 3. 5. The tire molding die according to claim 4, wherein the cast portion has a Vickers hardness of HV140 to 550. 6. The tire molding die according to claim 1, wherein the clearance for air bleeding comprises irregularities provided on an adjacent surface of at least one piece. 7. The tire molding die according to claim 6, wherein the step of the unevenness is 3 to 50 μm. 8. The tire molding die according to claim 6, wherein the irregularities provided on the adjacent surface are formed by setting the ten-point average roughness of the adjacent surface to Rz 3 to 50 μm. . 9. The method according to claim 1, wherein a corner formed between the molding surface and the adjacent surface of the piece is chamfered by 0.05 to 0.2 mm. The mold for molding a tire as described above. 10. The tire molding die according to claim 1, wherein the holder is divided into a plurality of sectors.