JPH0820026A - Mold for molding tire - Google Patents

Abstract

PURPOSE:To provide a mold for tire molding of good hardness of pieces, good durability and simple maintenance. CONSTITUTION:A plurality of pieces 10 are fitted on a holder sector 20 to constitute a segment 5. The pieces 10 are disposed adjoiningly in a manner that respective adjoining faces 12 of the pieces are brought into contact one another. The hardness of corners 11e formed by molded faces 11 and the adjoining faces 12 is controlled to be within the range of HV140-4000.

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, more specifically, it has excellent durability and maintainability,
The present invention relates to a tire molding die that can mold a tire having high dimensional accuracy and a good appearance.

[0002]

2. Description of the Related Art A conventional tire molding die is shown in FIG.
0 (a) vertical split mold, and FIG. 20 (b)
A mold of a radial division type as shown in is known, and in such a mold, gas such as air trapped between the mold and the unvulcanized rubber during tire vulcanization molding. A large number of small holes, called vent holes, that communicate with the inside and outside of the mold have been formed in order to discharge the gas to the outside of the mold.
However, the work of drilling such a vent hole requires skill, and since the number of drilled holes is large, the number of man-hours is also large.
There is a problem that the manufacturing efficiency of the mold is not sufficient. In addition, the vent holes generate hairy rubber called spew on the molded tire surface, which must be removed, and even if removed, traces are likely to remain on the tire surface. May damage the appearance of the tire,
There was a problem of impairing the initial running characteristics of the tire. Furthermore, when tire molding is repeated using the mold as described above, the spew is cut and remains in the vent hole, or the vent hole may be clogged due to accumulation of dirt such as rubber, It is necessary to clean the mold regularly (every hundreds to thousands of moldings), and this cleaning must be done manually with a drill etc. for all vent holes, which makes maintenance of the mold complicated. There was a problem that was.

To address such a problem, Japanese Patent Laid-Open No. 4-22
3108 and Japanese Unexamined Patent Publication No. 5-220753, a tread molding unit 1 for imparting a tread pattern to a tire is formed into a plurality of pieces by using a segment type tire molding die as shown in FIG. 20 (b). The number of vent holes can be reduced by dividing and holding by the holder 2 and appropriately controlling the adjoining distance between the pieces 1 in the mold assembly to provide an air vent gap for preventing the discharge of the rubber component. It is disclosed that it can be eliminated. It is also described that the division of the piece 1 to provide the air vent gap can be applied to a mold as shown in FIG. 20 (a).

[0004]

However, even in a mold in which the above-mentioned pieces are divided and arranged adjacent to each other,
When a tire is molded hundreds to thousands of times like a normal tire molding die, rubber is adhered to the die surface, vent holes, and air bleeding gaps between pieces, and the appearance of the resulting tire is impaired. In order to reduce the air bleeding effect, it is necessary to regularly clean the mold every several hundred to several thousand shots. Generally, the tire mold is cleaned by blast cleaning in which powder such as glass beads and iron powder is sprayed on the mold, but in the piece split mold, the rubber component that has entered the air vent gap is used. To remove dirt such as
It was necessary to remove each piece from the holder and perform blasting.

By the way, in the above-mentioned piece-dividing mold, since the pieces are made of an aluminum alloy, the hardness is not sufficient and the wear resistance is poor. Therefore, these pieces are plastically deformed by the blast cleaning, and as shown in FIG. As shown in a) to (c), a corner portion 1 formed by the molding surface 1a of the piece 1 and the adjacent surface 1b.
There is a problem in that a dripping phenomenon occurs in c, and the bleeding phenomenon narrows or blocks the air bleeding gap t provided between the pieces 1 to impair the air bleeding effect, making tire molding impossible. Further, when the pieces 1 having the meat dripping as described above are assembled into the holder 2, these meat sloping portions become an obstacle, and it becomes difficult to assemble a plurality of pieces 1 with a predetermined dimension, and the pieces 1 are arranged in an annular shape. If the tire is then molded, the roundness of the obtained tire is reduced. Further, the dripping of the pieces 1 causes an unnecessary contact between the pieces 1 when the pieces 1 are arranged adjacent to each other and assembled in the holder, which causes a problem that the pieces 1 are damaged.

Further, as shown in FIGS. 21 (a) to 21 (c), when meat dripping occurs on the piece 1, conventionally, it is necessary to manually remove the meat dripping, which is complicated. Further, even if the meat dripping is removed in this way, the flesh dripping newly generated in the removed portion by the blast cleaning of the piece 1 is increased every blast cleaning. Therefore, if these gradually increasing meat drips are to be removed sequentially, FIG.
As shown in (d), a relatively large notch portion 1d is formed between the pieces 1 or at the end of the piece 1, and if tire molding is performed in this state, the notch portion 1d (and the increased gap t) is There is a problem in that it is transferred as a thick line on the surface and impairs the appearance of the obtained tire. On the other hand, in order to avoid such a sagging phenomenon, it is possible to make a piece by using a high-strength type aluminum alloy (aluminum alloy obtained by hardening by solution treatment and aging treatment) as a mold material, Tire molding temperature is about 170 ℃
And is almost the same as the aging temperature of the aluminum alloy,
There is a problem that the aluminum alloy is over-aged during tire molding, which not only decreases the hardness but also changes the dimensions with time, which makes it difficult to adjust the dimensions between the pieces.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to form a tire having excellent hardness and durability and easy maintenance. It is to provide the mold. Another object of the present invention is to provide a tire-molding die capable of molding a tire having a high roundness and a good appearance.

[0008]

As a result of intensive studies 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. The present invention has been completed. Therefore, the tire molding die of the present invention is a tire molding provided with a plurality of annular pieces as a whole that impart a tread pattern to a product tire and a holder that can be mounted adjacent to each other in the circumferential direction. In the mold, the piece has a molding surface that imparts a part of the tread pattern, an adjacent surface that abuts or approaches the other piece, and a back surface that abuts or approaches the holder. An air bleeding gap is provided between the adjacent surfaces of the two pieces, and the Vickers hardness of the corner formed by the molding surface of the piece and the adjacent surface is HV1.
It is 40-4000.

[0009]

In the tire molding die of the present invention, the hardness of the corner formed by the molding surface of the piece and the adjacent surface is HV140-4.
Controlled to 000. Accordingly, the hardness and wear resistance of the corners are good, the degree of plastic deformation of the corners during the blast cleaning of the mold is extremely small, and the phenomenon of the sagging of the corners can be avoided. Therefore, in the tire mold of the present invention, the air vent gap provided between the adjacent surfaces of the piece is not blocked, and the durability of repeated use and cleaning is excellent. Further, since the corners do not sag, the arrangement position of the piece does not change due to sagging when the piece is arranged adjacent to the holder, and good dimensional accuracy can be maintained, so the roundness of the obtained tire can be maintained. Does not decrease.

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

In the tire molding die of the present invention, the Vickers hardness of the corner portion formed by the molding surface and the adjacent surface is HV140 to 4000, preferably HV1.
90 to 1000. The hardness of this corner is HV140-
To obtain 4000, the piece itself may be manufactured using a material having such hardness, but the material is not limited to this, and heat treatment such as quenching is applied only to the corner portion, or the corner portion is The above hardness can also be satisfied by subjecting only to the surface treatment to provide a high hardness layer.
If the hardness of the corners is less than HV140, meat dripping occurs and progresses during blast cleaning, which is not preferable. If the molding surface of the piece is less than HV140, roughening of the molding surface may occur during blast cleaning to impair the appearance. Therefore, it is more preferable to control the molding surface to be HV140 or more.

Further, in order to almost completely avoid the above-mentioned sagging phenomenon, HV190 or more may be set, but considering the workability of the piece, the hardness of the piece itself is preferably HV430 or less. However, after processing the piece, the hardness is HV300-400 by quenching (this is effective only for iron alloys), plating, surface treatment such as CVD.
It can be easily increased to zero. In the case of blasting with a normal tire molding die, HV
About 1000 is enough, and from this point, partial quenching (HV300 to 550) and Cr plating (HV100
The hardness range can be easily adjusted by applying (about 0). Further, it is possible to increase the HV to 1000 or more by these surface treatments, but such an excessive surface treatment is economically useless. In addition, the above-mentioned corner is about 0.05 ~
By chamfering with 0.2 mm, it is possible to further suppress the sagging of the corner portion at the time of blast cleaning, and this effect becomes more remarkable especially in the case of HV 190 or less. The chamfering may be performed in the state of the R surface or the C surface, but it is preferable that the chamfering is performed in the R surface shape with a radius of curvature of 0.05 to 0.2 mm.

The piece-making material satisfying the above hardness range is not particularly limited, and examples thereof include iron alloys, copper alloys, nickel alloys, and the like.
Iron-based alloys are preferred because of their low reactivity with rubber components, and among the iron-based alloys, spheroidal graphite cast steel and carbon steel cast steel are especially preferable in view of castability and strength for precisely casting a molding surface. preferable. Further, as a copper alloy, a BeCu alloy (especially 2-3% by weight of Be and 0.5-1.0% by weight).
The Cu alloy containing Co) is excellent in castability, hardness and thermal conductivity, but has high reactivity with a rubber component. Therefore, when this alloy is used, Ni and / or C is formed on the alloy surface.
It is necessary to perform r plating. When carbon steel cast steel is used, S30C containing 0.4 to 0.5% by weight of carbon is taken into consideration in consideration of castability (lowering of melting point) and improvement of hardness.
A composition equivalent to S55C is preferable, but N
It is more preferable to use a material containing a hardenability improving component such as i, Cr, or Mo.

By the way, a bone portion or a thin blade-shaped blade portion existing on the molding surface of the above-mentioned piece, that is, a convex portion for molding a tread groove of a tire, is conventionally cast by an aluminum casting, or a steel plate is made of aluminum by the blade portion. It was buried in an aluminum alloy piece ground by being cast in a casting. The reason for this is that the hardness of the aluminum alloy is not sufficient, so that even if the blade portion is integrally cast from the piece material, bending and damage will occur. Further, it is hard to say that the bonding strength is sufficient even in the blade portion that is cast around as described above,
In combination with the insufficient strength of the aluminum alloy itself, when such a blade portion exists in the vicinity of a few mm from the end face of the sector or when straddling between pieces, the blade portion is deformed, There was a problem of 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 sector end surface.
As described above, the pieces are separated from each other, or the pieces are divided by a curved line so that the blade portion does not straddle the pieces. Therefore, there are many restrictions in manufacturing the blade portions. Incidentally, conventionally, as a method other than the above-mentioned cast doll, an electric discharge machining method (hereinafter,
It is called "EDM". Although a blade portion is also provided by fitting a steel plate into the molding surface of the piece prepared by (4) or the like, there is a problem that not only the number of steps is required but also the joint strength is insufficient. Further, even the EDM itself requires a long processing time, which 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 this material is used to form the blade portion. It can be cast and the blade part can be formed integrally with the piece fabric. Since this blade portion is formed integrally with the piece fabric, it has good strength, and since it can be cast, there is almost no restriction on the position or the like at which the blade portion is provided. Therefore, the degree of freedom in designing the tire molding die is improved, and a process such as EDM that requires a long time is not necessary and the blade portion can be manufactured in a short time.

In the present invention, the hardness of the blade portion is preferably Vickers hardness and HV of 140 to 550. When the HV is less than 140, the strength is insufficient and the steel easily bends, and when the HV is more than 550, the toughness is insufficient and cracking is likely to occur, which is not preferable. In addition, when a thin portion such as a blade portion is applied to the above-mentioned corner portion of the piece, the blade portion and the like are easily worn by blast cleaning. Therefore, by locally quenching after casting, the HV300 to
It is preferably 550. As a material capable of soundly casting a blade portion having a plate thickness of about 0.5 mm, spheroidal graphite cast steel having the following composition is preferable. When casting the blade part using spheroidal graphite cast steel, HV55
It is necessary to prevent chilling so as not to exceed 0. For this purpose, the carbon content is 3.0 to 3.6% by weight, the silicon content is 2.0 to 2.8% by weight, and the graphite spheroidizing agent is used. (Mg) 0.0
A spheroidal graphite cast steel containing 4% by weight or less of copper or nickel that improves hardness and does not promote chilling is used as a basic component in which the chilling promoting component is reduced as much as possible by controlling it to 15 to 0.04% by weight. Is preferred. In order to further improve the hardness and the hardenability, it is preferable to contain molybdenum in an amount of 0.2 to 0.4% by weight together with nickel.

Next, as a material for manufacturing the holder, a material having a hardness of HV140 to 430 is preferable in order to prevent the holder from being damaged or worn when the pieces are attached and detached. Further, considering that the piece and the holder are heated during tire molding, the coefficient of thermal expansion of the holder is set to be equal to or less than the thermal expansion coefficient of the piece so that the mounted / fixed piece can be held by the holder during tire molding. Therefore, it is preferable to use a material having a small difference in thermal expansion coefficient from the piece-making material, because the material can adhere more firmly without generating a gap. This difference in coefficient of thermal expansion is about 200 ° C from room temperature
It is preferable to control to 5 × 10 ⁻⁶ / ° C. or less during the period.
By controlling the difference in coefficient of thermal expansion in this way, when arranging multiple 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 the pieces are mounted at room temperature. In addition, the roundness of the entire piece is maintained even during tire molding. Specifically, iron-based alloys, particularly spheroidal graphite cast steel, cast iron, and carbon steel cast steel can be preferably used as the holder manufacturing material.

Next, the air vent gap existing between the pieces will be described. This gap has a function of discharging the gas such as air trapped between the mold and the unvulcanized rubber to the outside of the mold during the tire vulcanization molding. In addition to the case where the pieces are intentionally provided, the case where the pieces necessarily exist between the pieces is included. For example, a molding surface is cast by producing a piece by precision casting using spheroidal graphite cast steel, and as shown in FIG. 17, a direction substantially perpendicular to the molding surface (center direction of the tire molding die) is set. When the adjacent surface of the piece is laterally machined by the outer peripheral teeth of the end mill 91 serving as a machining axis, it is usually Rz3 to 10
There is a gap defined by the machined surface roughness of about μm,
Even such a gap is sufficient.

This gap can also be created by cutting a part of the adjacent surface of the piece so as to penetrate from the molding surface to the back surface or providing a groove-like step. However, it is sufficient that the adjacent surface of one of the two adjacent 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 is more than μm, the height of the rubber component that comes out when the tire is molded becomes large, and the appearance of the product tire is impaired. Although it is also affected by the surface roughness of the adjacent surface of the piece, it is usually 3 μm in order to effectively release air.
The above groove depth is sufficient. However, the groove depth is 1
If the thickness is 0 μm or less, the rubber component that has penetrated into the step may be cleaved and left at the time of release, which may cause clogging. More preferably, it is 10 μm or more.

As another method for forming this gap,
There may be mentioned a method of cutting or blasting all or a part of the adjacent surfaces of the piece so as to have a ten-point average roughness Rz of 3 to 50 μm. According to this forming method, since the rubber component is difficult to insert into the gap, the rubber component will not be cut and remain in the gap, but depending on the material of the rubber component, dirt may be easily accumulated to close the gap. Therefore, it is preferable to roughen the entire adjacent surface of the piece as described above. Also in this case,
It suffices if either one of the two adjacent pieces is roughened, and it is not necessary that both are roughened. In addition, it is preferable to divide the pieces so that at least one such air bleeding gap is arranged in 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 penetrating in the circumferential direction (the direction in which the pieces are arranged adjacent to each other) is provided in the vicinity of the root of the bone part to adjoin It is also possible to add an air bleeding effect by communicating with.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail with reference to the accompanying drawings. (Embodiment 1) FIG. 1 is a perspective view partially showing an embodiment of a tire molding die of the present invention. FIG. 20 (b) is shown in FIG.
1 shows a part of a segment type mold, and a plurality of pieces 10 are attached to a holder sector 20 to form a segment 5. 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 shown by an arrow A in the figure to be mounted on the holder sector 20. belongs to. When mounting the piece 10 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
Although 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 done by counter boring the side surfaces of the piece 10 and the sector 20 and fixing them using bolts 60, washers 61, seats 62, and the like. In addition, when the seat 62 has elasticity, it can be used more preferably.

The piece 10 forms a tread pattern for the entire tire with all the pieces, and a convex pattern (bone portion and blade portion) for forming the tread pattern on the tire is formed on the molding surface 11 of the piece 10. (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 the present embodiment, S, M and L are arranged.
8 pieces (8 pieces) of the pieces 10 having three kinds of pitches are arranged vertically in two stages. The numbers shown at the upper and lower edges of the holder sector 20 represent the column numbers of the pieces 10.

These pieces 10 are cast by molding the molding surface 11 by a precision casting method such as a ceramics molding method. Distortion (twisting) of the molding surface 11 during this casting
Is controlled to 0.15 mm or less, preferably 0.1 mm or less. Next, the distortion of the molding surface 11 is maintained by machining the other surface (adjacent surface 12 etc.) with the main part of the molding surface 11 of each piece as a reference, and finally each piece is assembled in the holder. However, it is possible to obtain a tire molding die having a circularity of 0.15 mm or less, preferably 0.1 mm or less. The piece-adjacent surface 12 is machined by a flat surface or a curved surface oriented in the central axis direction of the tire molding die (the center direction of the obtained tire) with the machining axis having an angle corresponding to the pitch dimension of the piece. At this time, the piece adjacent surface 12
Is curved, it is preferable that the processing axis is oriented horizontally toward the center of the tire mold and the processing is performed while keeping the above angle constant. As a concrete processing example of the piece adjoining surface 12, an NC milling cutter is used, the piece is fixed by facing the piece forming surface 11 with an angle according to the pitch dimension of the piece, and fixing the Z axis. X,
It is possible to exemplify controlling the Y axis and performing side surface processing by the outer peripheral teeth of the end mill. Note that the software design for such processing can be easily performed.

The piece 10 obtained by processing as described above
By using, it becomes difficult for rattling between the adjacent surfaces 12 and unnecessary gaps between the adjacent surfaces 12 when the piece 10 is mounted on the holder sector 20. Also, with this, the piece 10
When the hardness is HV140 or more, defects such as galling (damage) between the pieces are less likely to occur, and it becomes possible to easily obtain a piece having excellent wearability. Furthermore, by performing the above-described curved surface processing on the piece arranged on the end surface of the holder sector, the same effect can be obtained when the mold is clamped during tire molding. The other portion (back surface or the like) of the piece 10 is machined by using a lathe, a milling machine or the like so as to match the size of the portion held by the lathe-machined holder sector 20. If the piece 10 is processed as described above,
0.15 mm even when 100 to 200 pieces 10 are mounted on 7 to 8 holder sectors 20 and a mold is assembled.
The roundness of can be secured.

Referring to FIG. 1, the pieces 10 are arranged adjacent to each other by abutting their adjacent surfaces 12 with each other. However, the air bleeding gap during tire vulcanization molding is part of the adjacent surfaces 12. Can be provided by penetrating from the molding surface 11 to the back surface 13 and typically cutting or grinding about 0.02 mm. Alternatively, piece 10
0.02 mm between each other (between some of the adjacent surfaces 12)
An air vent gap can also be provided by inserting a spacer of a certain degree. It is also possible to impart an air bleeding effect by processing a part or the whole of the adjacent surface 12 into a state having a processed surface roughness of 10-point average roughness Rz of 3 to 50 μm. When the size of the air bleeding gap is small, the desired air bleeding 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 air bleeding gap as described above is arranged in a portion forming a land area in a tread portion of a product tire.

In the present embodiment, the molding surface 1 of the piece 10
The hardness of the corner portion 11e formed by 1 and the adjacent surface 12 is HV14.
It is controlled within the range of 0 to 550. However, piece 1
All of 0 may be configured to satisfy this hardness range. In order to realize this hardness, it is possible to exemplify that the material of the piece 10 is spheroidal graphite cast steel, carbon steel cast steel, BeCu alloy, or the like. Further, in the iron-based alloy, the hardness can be further improved by quenching the corner portion 11e. For example, the piece 10 is made of spheroidal graphite cast steel, and the corners 11e are hardened at 800 to 900 ° C., so that the hardness of the corners 11e is HV400 to HV5.
It can be improved to 50. Further, in the present invention, since it is sufficient that the corner portion 11e has a predetermined hardness, the hardness of the corner portion 11e can be increased to HV by making the piece 10 from an aluminum alloy and subjecting the piece 10 to a surface treatment such as hard alumite.
It may be about 1000.

As described above, the mold of this embodiment has the corner portion 1
Since the hardness of 1e is large and the abrasion resistance is excellent, even if the 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 avoid blocking the air vent gap provided between the adjacent surfaces 12 by blast cleaning, and the mold has excellent durability against repeated use. Also, piece 1
Since 0 does not sag and does not easily plastically deform, 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, meat dripping can be more favorably avoided, the durability of the mold can be further improved, and the dimension at the time of the adjacent arrangement described above. 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 this holder sector 20 is HV140-
430 is preferable, and the hardness of the holder sector 2 is controlled when the piece 10 is mounted / removed by controlling the hardness within this range.
It is possible to avoid the zero from being damaged or worn. Further, considering that the piece 10 and the holder sector 20 are heated to about 170 ° C. at the time of tire formation, a material having a small difference in thermal expansion coefficient from the material for making the piece 10 is preferable, and the difference in thermal expansion coefficient between them is at room temperature. It is preferable that the temperature is 5 × 10 ⁻⁶ / ° C. or less between the temperature and about 200 ° C. By controlling the difference in the coefficient of thermal expansion in this way, when the plurality of pieces 10 are arranged adjacent to each other, it is possible to save the trouble of adjusting the dimension of the holder sector 20 in consideration of the amount of thermal expansion of the pieces 10. As a material for manufacturing the holder sector 20, specifically, an iron-based alloy, particularly spheroidal graphite cast steel or 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 reduce the thermal conductivity with the piece 10. Although the holder sector 20 can be made lighter by partially removing the holder sector 20, it is necessary to be careful not to reduce the thermal conductivity. From this point of view, it is preferable to insert an aluminum alloy or fill oil with a structure that absorbs the difference in thermal expansion between the thinned portions.

In the present embodiment, the piece 10 and the holder sector 20 are positioned 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 upper and lower two stages, and three plate-shaped stoppers 30 are provided at predetermined positions of these circumferential grooves 22. Has 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 pin hole 14 has a diameter slightly smaller than the width of the circumferential groove 22. Positioning pin 15 having
Is inserted to form a convex portion.

When mounting the piece 10 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, but the height H of the positioning pin 15 and the height of the stopper 30 are set. By adjusting the relationship with I as shown in FIGS. 5 (a) to 5 (c), the predetermined piece 10 (S, M, L) can be moved to the predetermined stopper of the circumferential groove 22. 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 modes of FIGS. 5 (a), (b), and (c), respectively). It shall be.). That is, for example, in FIG. 4, the first to third rows of pieces S, S, and M are distinguished by which circumferential groove 22 guides the pin 15. Further, pieces having the same circumferential groove 22 to be guided, for example, the pieces in the first row, the fourth row, and the seventh row 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 groove depth G,
Various positioning patterns can be adopted by appropriately changing the height H of the stopper and the height I of the pin. As described above, in this embodiment, the corner portion 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 pieces 10 can be easily and accurately mounted on the sectors 20 during mold assembly such as after cleaning. .

Next, a modified example of the piece 10 is shown in FIG. In the same figure, in this piece 10a, the back surface 13a, 13b, and 13c are cut, and according to this example, the portion where the piece and the sector 20 slide when the piece is mounted on the sector 20 is cut. It is possible to reduce the number, and it becomes easier to attach / detach the piece. However, if the areas of the relief surfaces 13a, 13b, etc. due to cutting are made too large, the heat transfer efficiency between the piece and the sector 20 decreases, so the area of these relief surfaces 13a, etc. It is preferable to control the area to be half or less of the area of the back surface 13 when it is in complete contact with the entire holding surface 21. In addition, a groove 16 which is an example of a guide is provided on the back surface of the piece 10a, and the rail 40 is provided in the groove 16 when the mold is released.
Is guided and each piece 10a is moved to the rail 40 so as to be in a state of connecting beads, it is convenient that the detached pieces 10a do not fall apart. In this case, the groove 16
It is preferable that the cross sectional shape of the rail 40 has a shape having an undercut as shown in FIG. As a guide,
It does not necessarily have to be a groove, but may be a hole. Furthermore, when the rail 40 is made of a soft metal wire, for example, a copper rod, the rail 40 is changed from the state shown in FIG. 8 (a) to the state shown in FIG. 8 (b) when the piece 10a is blast cleaned. By curving, 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, piece 1
It is also possible to exemplify a method in which a wire 41 longer than the total length of 0a is prepared and the pieces 10a are interconnected by the wire 41 (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 the piece 10b used for this segment. In the following description, the same members as those described above will be designated by the same reference numerals, and the description thereof will be omitted. Further, the corner portion 11e and the sector 20 of the piece 10b satisfy the above-mentioned differences in hardness and thermal expansion coefficient. Although the mold shown in this embodiment is also the above-mentioned segment type mold, the holder plate 50, 50 is used to hold the piece 10b in the sector 20 from above and below 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 upper and lower two stages, and the bonding strength of the contact surfaces 19 above and below the piece 10b can be increased. Step 11 of piece 10b
By fitting the holder plate 50 into a, the piece 10b can be pressed in the direction indicated by the arrow D in the figure,
The mounting strength of the piece 10b can be further improved. Further, in the mold of the present embodiment, the loading / unloading direction of the piece 10b is the radial direction shown by the arrow B in the figure. 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, by changing the shape and position of the convex portion 17 and the shape and position of the concave portion 24, the specific piece 10b is attached to the specific position of the sector 20. This is done with certainty. In the present embodiment, unlike the first embodiment, it is not necessary to sequentially arrange the pieces in the circumferential direction, and therefore 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 the 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 pieces in the seventh row can be exchanged. Furthermore, in the present embodiment, the ratio of sliding between the piece 10 and the sector 20 is low, so that the mountability is even better. In addition, in the present embodiment, FIG.
In the state in which the pieces are not fixed as shown in (3), all the pieces 10b in the segment can be attached and detached at the same time, so that the workability of releasing the mold can be improved. Furthermore, by providing a groove on the back surface of the piece 10b and inserting the rail into this groove, it is possible to avoid the pieces 10b from becoming disjointed during mounting and removal (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 is controlled as described above, it is possible to avoid the meat sagging phenomenon, the mold life is excellent, and the obtained tire has a perfect circle. It is also excellent. Next, a modification of this embodiment is shown in FIG. Also in the example shown in the drawing, the back surface of the piece 10 is fixed to the sector 20 by using the holder plate 50.
With this configuration, the sliding surface can be made smaller,
The mold structure can also be simple. Further, by providing the hollow portion 100 inside the sector 20 and enclosing oil or the like in the hollow portion 100, the weight is reduced to the extent that the heat transfer property is not significantly deteriorated.

(Embodiment 3) FIG. 11 is a perspective view showing another embodiment of the tire molding die of 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. Also, the corner 1
1e, the hardness of the sector 20 and the difference in the coefficient of thermal expansion are controlled as described above. The die shown in this embodiment is also a segment type die, but the piece 10c is attached and detached in the axial direction (vertical direction) shown 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
The positioning is performed by appropriately selecting the height h and the width x of the vertical groove 18 provided on the back surface 13 of the piece 10c and the convex portion 25 that is fitted (guided and locked) in the groove 18. Be seen.

In this embodiment, since the hardness of the corners 11e and the sector 20 and the coefficient of thermal expansion are controlled, it is extremely unlikely that the sagging phenomenon will occur during the blast cleaning. The mold has excellent durability, and the roundness of the obtained tire is also good. In addition, in the present embodiment, FIG.
In the state in which the pieces are not fixed as shown in (3), all the pieces 10c in the segment can be attached and detached at the same time, so that the workability of releasing the mold can be improved. Furthermore, piece 1
By inserting the rail 40 into the groove 16 of 0c, it is possible to prevent the pieces 10c from becoming disjointed during attachment / detachment. According to the present embodiment, the pieces 10c are simultaneously and instantly removed by lifting both ends of the inserted rail 40 or removing the lower holder while the sector 20 is still attached to the main body of the tire vulcanizer. Therefore, the desorption property is better than that of Example 2. Further, in the present embodiment, the adjacent surface 12 of the piece 10c is a flat surface, but can be a curved surface.
It is also possible to divide into two 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 a part of the mold by cutting it away, FIG.
(b) is a perspective view showing a piece 10d used in this mold. Also in this embodiment, the differences in hardness and thermal expansion coefficient between the corner portion 11e and the sector 20 are controlled as described above. Therefore, the die life is excellent, and the roundness of the obtained tire is also good. Further, the positioning mechanism of the mold of this embodiment is basically the same as that of the third embodiment. In addition, when the adjacent surface 12 of the piece 10d is curved, it is necessary to simultaneously remove and attach the pieces 10d for the entire circumference. Therefore, the holding surface 21 of the sector 20 and the back surface 1 of the piece 10d.
It is preferable to provide a draft in No. 3. However, if one of the adjacent surfaces of the pieces is a flat surface and the pieces are removed first, it is not necessary to remove and attach 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 cutting surface 13a is used to make the piece 10d.
If the wires 41 are connected to each other, the 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. Also, FIGS. 15 (a) and 15 (b)
FIG. 15 is a perspective view of the piece shown in FIG. 14. In FIG. 14, in this mold, similarly to the mold of the second embodiment, the holder plate 50 is used to hold the pieces 10e and 10f in the sector 20. In the figure, the illustrated arrows indicate the direction in which the pieces 10e and 10f are pressed by the sector 20. The corner 11e
The sector 20 satisfies the hardness range and the difference in thermal expansion coefficient described above. In addition, as shown in FIG.
A blade 70, which is an example of a convex portion for forming a tread groove in the tire, is 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.
3% by weight, Cu: 2% by weight, and the balance being Fe) are integrally cast from the molding surface 11 by a precision casting method (ceramics molding method) and have 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 separation, etc. is extremely low. Further, as described above, the hardness may be improved to HV 400 to 500 by, for example, quenching the corner portion of the portion that straddles the adjacent surface 12 of the blade 70.

When forming these blades 70,
Generally, it is better to avoid providing the piece at a position that straddles the adjacent surface 12 between the pieces, but 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 having a size of mm × height of 5 to 10 mm, if the width is 5 mm or more, the problem of strength does not occur, and the possibility of blade damage can be ignored. Therefore, there is almost no restriction on the position or the like at which the blade 70 is provided, and the mold of this embodiment can improve the degree of freedom in designing when the blade 70 is provided. The strain 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 method described above. In addition, the adjacent surface of the piece is also curved by the above-mentioned method, and the processed 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 either one of the adjacent surfaces. to be able to do,
There is a step.

Further, as shown in FIG. 15 (b), the piece 1
On the back surface 13 of 0e, a positioning pin 15 is provided as in the second embodiment.
Example 2 is provided in the die assembly after the die cleaning.
The positioning is done as follows. Further, the rear surface 13 of the piece 10e is provided with escape surfaces 13d to 13f to improve the attachment / detachability between the piece and the sector 20, and these escape surfaces also function as an air discharge path. As for the pieces arranged on the end faces of the sectors 20, it is preferable that the displacement 73 does not occur between the adjacent faces of the upper and lower pieces, as shown in FIG.
For this purpose, a smooth curved surface (preferably a flat surface) having no step may be formed by adjusting the position where the adjacent surface of the piece 10e or 10f is processed. By treating the end surface of the sector 20 as described above, it is possible to prevent the occurrence of galling (damage, etc.) on the piece adjoining surface when the entire sector is clamped. The pieces 10e and 10f described above
14 for each of the eight sectors 20 as shown in FIG.
When the pieces were mounted vertically, the roundness of the whole piece was 0.07 mm. Also, when the gap between the adjacent surfaces of the piece was measured using a gap gauge,
No gap having a size of more than 0.01 mm was formed except the portion where a step of 0.02 mm was provided and a slit-shaped air vent gap was provided.

(Thickness 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 materials 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, the adjacent surface 12 is Rz
The surface was processed to have a thickness of 5 μm, and the corner portion 11e was left as an acute angle, while the other corner portion 11e ′ was chamfered with a radius of curvature of about 0.1 mm. Also,
For blast cleaning, mold # 100 glass beads on the molding surface 11
It was performed by injecting at a pressure of 4 kgf / cm ² for 10 minutes and 20 minutes from a position separated by about 30 cm. After such blast cleaning, as shown in FIG. 16B, the plastic deformation amounts t ₁ and t ₂ of the corner 11e and the roughness of the molding surface were measured. The obtained results are shown in Table 2. In addition,
The 10-minute and 20-minute blast cleanings are actually equivalent to about 50 and 100 cleanings when back calculated from the normal cleaning time and the piece area.

[0041]

[Table 1]

[0042]

[Table 2]

From Tables 1 and 2, in Comparative Examples 1 and 2 relating to the Al-based alloy, t ₁ was already 0.02 mm or more after 10 minutes of blast cleaning, which was 0.02 m.
This means that even if there is an air venting gap of m, this blast cleaning closes the air gap, and the air venting 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 sloping portion, which is troublesome. Further, the surface roughness of the molding surface 11 is Rz 20 or more, and such surface roughness is transferred to the product tire. On the other hand, in Examples 6 to 10, even in Example 6 in which the hardness is inferior, the amount of deformation t ₁ does not reach the degree of obstructing the air venting effect by slightly chamfering the corners. Further, in the examples in which HB exceeds 200, t ₁ is 0.01 or less even if the corners remain sharp, which does not adversely affect the air venting effect. Further, those having a chamfer of more than HV210 and those having a chamfer of more than HV320 (no chamfer) hardly cause deformation due to sagging. In addition, Example 11 other than iron-based alloy
Then, the same effect as in Example 9 is obtained by subjecting the BeCu alloy to solution treatment and age hardening treatment. On the other hand, in Example 13 obtained by subjecting FCD-400 of Example 6 to hard Cr plating, the hardness of the plated portion was HV900, and deformation due to blast cleaning hardly occurred. Further, the surface roughness of the molding surface 11 does not exceed Rz 15 μm in Examples 6 to 13, and particularly in the case where HV210 is exceeded, Rz is 10 μm or less, and good results are obtained.

(Rubber Hamming 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), and each piece was Table 3 on the adjacent surface 12
An air vent gap was provided under the conditions shown in. The obtained pieces (16 pieces) were mounted on a rubber vulcanization tester shown in FIG. Using this tester, vulcanization molding and blast cleaning were performed by the methods described below. At this time, the generation state of air pools (the degree of deterioration of the air bleeding effect due to the adhesion of dirt such as rubber) and the height at which the rubber is cut out were evaluated in the region 11R closed by the skeleton 72. 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 basically As a result, the outer peripheral teeth of the end mill 91 are subjected to side surface machining with Rz 1 μm, and the corners 11e and 11e ′ are approximately 0.0
It is chamfered to 5 mm.

[Method of Vulcanization Molding and Blast Cleaning] Each piece obtained as described above was put into a piece No. 18 is mounted on the vulcanization molding tester shown in FIG. 18, the heater 80 is operated, and the surface temperature of each piece is set to 17 via the base 81.
Heated to 0 ° C. Next, after bringing the unvulcanized rubber sheet 83 generally used for tire molding into contact with each piece,
The sheet 83 was uniformly pressed in the direction of arrow E so that the pressure was changed from normal pressure to 20 kg / cm ^{2 in} about 15 seconds, and was held for 10 minutes to perform molding. At this time, the back side of the piece was depressurized to 700 mmHg by a depressurizing hole (not shown) provided in the frame 84, if necessary. Molding was performed 10 times each depending on whether or not the pressure was reduced, and the initial air venting effect was evaluated. The obtained results are shown in Table 4. Next, each piece was detached from the vulcanization molding tester and blast-cleaned for about 10 minutes under the same conditions as in Examples 6 to 13. Then, each piece was mounted on the vulcanization molding tester again, and in principle, molding was performed up to 2000 times without depressurizing. Table 5 shows the obtained results.

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

[Table 5]

From Tables 3 and 4, in the initial state where the pieces are not soiled and the blast cleaning is not performed, when the substantial gap between the pieces exceeds about 50 μm, the protruding height of the rubber is increased. It can be seen that the state exceeds 0.5 mm. On the other hand, when the vent hole is provided as in the conventional technique, 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.,
If the actual gap between the pieces is less than 3 μm, the bone 7
Transfer defects are likely to occur near the root of No. 2. This means that the piece No. having the vent hole 85 is provided. The same applies to 15. However, when the pressure was reduced, the transferability was good in all cases. It was also found that the presence or absence of depressurization did not significantly affect the protruding height of the rubber.

Next, in order to confirm the influence of the molding conditions on the appearance of the rubber, in FIG. 18B, the speed at which the molding pressure is applied is reduced (0 to 20 kg / c in 30 seconds).
m ² ) Molded. As a result, the protruding height of the rubber is reduced by about 30% in all the pieces. In 8 and 9, the protruding height is 0.35 each
mm and 0.6 mm. On the other hand, the transferability (transferability of the root of the bone 72) generally tended to be slightly lowered. Therefore, it is possible to suppress the height of the rubber protrusion by changing the molding conditions including the material of the rubber, but by setting the air vent gap to 0.05 mm, the transferability is improved. Without decreasing, 0.
The protrusion height can be 5 mm or less.

By performing blast cleaning, A
L-alloy piece No. In Nos. 15 and 16, since the hardness was not sufficient, the molding surface 11 became considerably rougher than the initial state, but with 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 2000 times molding after the blast cleaning, the piece No. 1 was slightly clogged. Peace No. Gap of 2 (about 3μ
m) is considered to be the lower limit of the gap. Peace No. No problems occurred in 3 to 9. In addition, the piece No.
In No. 10, the rubber is easily broken and remains because the groove is slightly shallow, but this can be solved by chamfering the corners. Peace No. In No. 11, no problem occurs if vacuum molding is performed. On the other hand, the piece No. having the vent hole of the conventional technology is used. In No. 15, it was found that the height of the protruding rubber was too large, and therefore the rubber was likely to remain in the vent hole. In addition, the piece No. In No. 16, meat dripping occurred due to blast cleaning, the air bleeding effect was reduced, and clogging occurred.
It should be noted that even when the iron-based piece was molded 2000 times, the rubber stains adhered to the molding surface 11 and the skin became rough, but the stain could be removed by lightly performing blast cleaning after this. Also, the air venting effect was restored in all iron-based pieces. In addition, the Cr-plated piece No. In No. 12, the molding surface 11 was slightly roughened and soiled.

(Blade Strength Test) (Example 15) FCD-600 and FC of spheroidal graphite cast steel
A piece 10e shown in FIG. 15A was produced using D-800. Next, the 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 in the direction of the arrow in the drawing was applied to the blade 70, and the maximum stress at that time was measured. The maximum stress is d in the figure.
Was 5 mm or 0.5 mm, and the measurement was performed in two ways.

(Comparative Example 4) The body 10e was made of Al alloy (AC4C), the blade 70 was made of SUS304, and the cast hole depth was 4 mm and the locking hole φ1.
Example 1 except that 5 mm is provided and it is cast in the main body 10e.
The same operation as 5 was repeated. Comparing the obtained bending strength with that of Example 15, the product of FCD-600 of Example 15 was about 1.3 times that of Comparative Example 4, and the product of FCD-800 was about 1. It was eight times. When d was 0.5 mm, the flexural strength did not decrease in Example 15, but in Comparative Example 4, the Al alloy part broke first due to flexural stress, so the flexural strength decreased to about 1/2. As described above, in the piece according to Example 15 in which the blade 70 has a 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 is in a state of straddling between the pieces, there is relatively no problem, and it is possible to reduce design restrictions when the blade is provided.

The present invention has been described above with reference to the preferred embodiments, but the present invention is not limited to these embodiments.
Various modifications are possible within the scope of the present invention. For example, the molds of Examples 1 to 5 perform positioning with the holder 20, but such positioning is not an essential item of the present invention, and it is sufficient if only the hardness condition of the corner portion 11e is satisfied. Further, the molds shown in Examples 1 to 3 and 5 can also be applied to a vertically divided type. Furthermore, Examples 1 and 2
In the mold of (1), the pieces are arranged in upper and lower stages, but the pieces may be integrally formed in the upper and lower sides.

[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 which has excellent hardness of the piece and good durability and can be easily maintained. Further, according to the present invention, it is possible to provide a tire molding die capable of molding a tire having a high roundness and a good appearance.

[Brief description of drawings]

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

FIG. 2 is a perspective view of a piece used in the mold of FIG.

FIG. 3 is a perspective view and a partial 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 the relationship between the height of the stopper and the height of the pin.

FIG. 6 is a perspective view showing a modified example of the piece.

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

FIG. 8 is a schematic view showing a state where the pieces are connected in a beaded manner.

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 cross-sectional view showing another embodiment of the tire molding die of the present invention.

13 is a perspective view showing a modified example of the piece used in 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 in the mold shown in FIG.

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 tester.

FIG. 19 is an explanatory cross-sectional view showing a method for measuring bending strength.

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

FIG. 21 is a cross-sectional explanatory view showing a state of meat sagging.

22 is a perspective view showing a modified example of the tire molding die shown in FIG. 9. FIG.

[Explanation of symbols]

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

Claims (10)

[Claims] 1. A tire-molding mold comprising a plurality of generally annular pieces for imparting a tread pattern to a product tire, and a holder to which these pieces can be mounted adjacent to each other in the circumferential direction. , Having a molding surface that imparts a part of the tread pattern, an adjacent surface that abuts or approaches the other piece, and a back surface that abuts or approaches the holder, and between the adjacent surfaces of the pieces. A tire-molding die, which is provided with an air bleeding gap and has a Vickers hardness of HV140 to 4000 at a corner formed by the molding surface of the piece and an adjacent surface thereof. 2. The tire molding die according to claim 1, wherein the piece is made of an iron-based alloy or a copper-based alloy. 3. The tire molding die according to claim 1, wherein the piece is made of spheroidal graphite cast steel, carbon steel cast steel or beryllium copper alloy. 4. The whole or a part of the convex portion on the molding surface of the piece is cast.
The tire mold according to any one of 1 to 3. 5. The tire molding die according to claim 4, wherein the Vickers hardness of the cast projection is HV140 to 550. 6. The tire molding die according to claim 1, wherein the air bleeding gap is formed by concavities and convexities provided on the adjacent surface of at least one piece. 7. The tire mold according to claim 6, wherein the unevenness has a level difference of 3 to 50 μm. 8. The tire molding die according to claim 6, wherein the unevenness provided on the adjacent surface is formed by setting the ten-point average roughness of the adjacent surface to Rz3 to 50 μm. . 9. The chamfering processing is performed at a corner of the molding surface of the piece and the adjacent surface to be 0.05 to 0.2 mm, according to any one of claims 1 to 8. The tire molding die described. 10. The tire-molding die according to claim 1, wherein the holder is divided into a plurality of sectors.