阅读说明：本技术 轮胎用模具的制造方法 (Method for manufacturing tire mold ) 是由 石原泰之 于 2019-09-03 设计创作，主要内容包括：本发明容易地形成能形成狭缝排气口的多个模具片,提高轮胎用模具的制造效率。模具片以在彼此的狭缝形成部之间形成有狭缝排气口的状态利用成形部成形轮胎。利用模具坯料(30)形成多个模具片。在模具坯料(30)的背面部(31)侧,沿着多个模具片的分割位置形成多个比狭缝排气口宽的分割槽(33)。在多个分割槽(33)的底部利用激光来切断模具坯料(30),从而分割多个模具片且在多个模具片的成形部侧形成狭缝形成部。(The invention easily forms a plurality of mold pieces capable of forming slit exhaust ports, and improves the manufacturing efficiency of a tire mold. The mold pieces mold a tire with a molding section in a state where a slit vent is formed between the slit forming sections. A plurality of die segments are formed from a die blank (30). A plurality of dividing grooves (33) wider than the slit exhaust port are formed along the dividing positions of the plurality of die pieces on the back surface portion (31) side of the die material (30). A die blank (30) is cut by a laser beam at the bottom of the plurality of dividing grooves (33), thereby dividing the plurality of die pieces and forming slit forming portions on the forming portion side of the plurality of die pieces.)

1. A method of manufacturing a mold for a tire, in which a plurality of mold pieces for molding a tire by a molding section in a state in which a slit exhaust port is formed between slit forming sections are formed by using a mold material, wherein,

the method for manufacturing the tire mold comprises the following steps:

forming a plurality of dividing grooves wider than the slit exhaust port along dividing positions of the plurality of die pieces on a back surface side of the die blank; and

the die material is cut by a laser beam at the bottom of the plurality of dividing grooves, thereby dividing the plurality of die pieces and forming slit forming portions on the molding portion side of the plurality of die pieces.

2. The method for manufacturing a mold for a tire according to claim 1,

the plurality of die pieces are combined so that a maintaining member for maintaining the width of the slit vent is sandwiched between the adjacent die pieces.

3. The method for manufacturing a mold for a tire according to claim 2,

a plurality of blind holes are formed at intervals along the dividing positions of the plurality of die pieces on the back side of the die blank,

dividing grooves are formed along the dividing positions of the plurality of die pieces in a manner of passing through the plurality of blind holes,

cutting the die blank at the bottoms of the plurality of dividing grooves by laser to form accommodating portions in the blind hole portions of the plurality of divided die pieces,

the retaining member is received in the receiving portion while being sandwiched between the adjacent die pieces.

4. The method for manufacturing a mold for a tire according to claim 2,

cutting the die blank with a laser beam at the bottoms of the plurality of dividing grooves to form accommodating portions in the dividing groove portions of the divided die pieces,

the retaining member is received in the receiving portion while being sandwiched between the adjacent die pieces.

5. The manufacturing method of a mold for a tire according to any one of claims 2 to 4,

the adjustment member is sandwiched between the adjacent die pieces together with the holding member, and the width of the slit vent is adjusted by the adjustment member.

6. The manufacturing method of a mold for a tire according to any one of claims 2 to 5,

the dimension of the retaining member in the width direction of the slit exhaust port is increased or decreased, thereby changing the width of the slit exhaust port.

7. The manufacturing method of a mold for a tire according to any one of claims 2 to 6,

a holding member having a thermal expansion coefficient different from that of the mold pieces is sandwiched between the adjacent mold pieces.

Technical Field

The present invention relates to a method for manufacturing a tire mold having a plurality of mold pieces.

Background

In a tire mold having a plurality of mold pieces, the plurality of mold pieces are combined into a ring shape, and a tire is molded by the plurality of mold pieces. The tire is vulcanized in a state of being pressed against the plurality of mold pieces. At this time, air may be trapped between the tire and the mold piece. In particular, in the case of a mold piece for molding a tread portion of a tire, since a closed space is formed between the mold piece and the tire by a projection of the mold piece corresponding to a groove of the tire, air entrapment is likely to occur.

In order to prevent the air from being sealed, the tire mold generally includes an air vent (air vent) for venting air. However, when the air discharge portion is an air vent hole, rubber enters the air vent hole, and thus elongated rubber (bead) is formed in the tire. Therefore, conventionally, a method of manufacturing a tire vulcanization mold is known in which air is discharged from a gap (slit vent) formed between opposing portions of a plurality of flaps (mold pieces) instead of the vent hole (see patent document 1).

In the conventional method for manufacturing a mold for tire vulcanization molding described in patent document 1, a tread ring is cut by a wire electric discharge machine to divide a plurality of mold pieces. The opposing portion of the die piece is formed into a shape (e.g., a curved surface shape) that can be formed by the movement of the wire. Therefore, in order to form the opposing portion of the die piece into a shape suitable for the discharge of air (for example, a shape having a discharge groove for air), it is necessary to process the opposing portion of the die piece again by a processing machine, which takes labor and time in forming the die piece. In addition, since the machining allowance of the die piece is increased, the blank of the die piece is wasted more.

In recent years, in order to further improve the performance of a tire, the tread pattern of the tire has become complicated, and for example, a curved groove having a large inclination with respect to the tire circumferential direction or the tire width direction is used. In such a tire, pattern deviation may easily occur in the opposing portions of the mold pieces, and variation may occur in the width of the slit exhaust port. Therefore, the time and labor required for forming the mold piece are increased, and the efficiency of manufacturing the tire mold is also lowered.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 5-220753

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to easily form a plurality of mold pieces capable of forming slit vents, thereby improving the manufacturing efficiency of a tire mold.

Means for solving the problems

The present invention provides a method for manufacturing a tire mold, in which a plurality of mold pieces are formed by a mold blank, and a tire is molded by a molding section in a state where a slit vent is formed between slit forming sections of the plurality of mold pieces. The method for manufacturing the tire mold comprises the following steps: forming a plurality of dividing grooves wider than the slit exhaust port along dividing positions of the plurality of die pieces on a back surface side of the die blank; and cutting the die blank by a laser at the bottoms of the plurality of dividing grooves to divide the plurality of die pieces and form slit forming portions on the molding portions of the plurality of die pieces.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a plurality of mold pieces capable of forming slit vents can be easily formed, and the manufacturing efficiency of a tire mold can be improved.

Drawings

Fig. 1 is a perspective view showing a tire mold according to embodiment 1.

Fig. 2 is a perspective view showing a mold half according to embodiment 1.

Fig. 3 is a perspective view showing the mold half of embodiment 1 disassembled.

Fig. 4 is a perspective view showing a die piece according to embodiment 1.

Fig. 5 is a perspective view showing a plurality of die segments provided in the die set of embodiment 1.

Fig. 6 is a perspective view showing a manufacturing process of a tire mold according to embodiment 1.

Fig. 7 is a perspective view showing a manufacturing process of the tire mold according to embodiment 1.

Fig. 8 is a perspective view showing a manufacturing process of a tire mold according to embodiment 1.

Fig. 9 is a perspective view showing a manufacturing process of a tire mold according to embodiment 1.

Fig. 10 is a perspective view showing a manufacturing process of a tire mold according to embodiment 1.

Fig. 11 is a perspective view showing a manufacturing process of a tire mold according to embodiment 1.

Fig. 12 is a perspective view showing a manufacturing process of a tire mold according to embodiment 1.

Fig. 13 is a perspective view showing a manufacturing process of a tire mold according to embodiment 1.

Fig. 14 is a perspective view showing a mold half according to embodiment 2.

Fig. 15 is a perspective view showing the mold half of embodiment 2 disassembled.

Fig. 16 is a perspective view showing a die piece according to embodiment 2.

Fig. 17 is a perspective view showing a plurality of die segments provided in the die set of embodiment 2.

Fig. 18 is a perspective view showing a manufacturing process of a tire mold according to embodiment 2.

Fig. 19 is a perspective view showing a manufacturing process of the tire mold according to embodiment 2.

Fig. 20 is a perspective view showing a manufacturing process of the tire mold according to embodiment 2.

Fig. 21 is a perspective view showing a manufacturing process of a tire mold according to embodiment 2.

Fig. 22 is a perspective view showing a manufacturing process of a tire mold according to embodiment 2.

Detailed Description

An embodiment of a method for manufacturing a tire mold according to the present invention will be described with reference to the drawings.

In the method of manufacturing a tire mold according to the present embodiment, a mold material is processed, and a plurality of mold pieces are manufactured from 1 mold material. The tire mold is a molding mold for molding a tire, and is used for vulcanization of the tire. The tire (green tire) is molded by a tire mold and vulcanized. Hereinafter, a plurality of embodiments of a method for manufacturing a tire mold will be described in order.

(embodiment 1)

Fig. 1 is a perspective view showing a tire mold 1 according to embodiment 1, and shows a structure of the tire mold 1 in a perspective view of the tire mold 1. Fig. 1 a shows the tire mold 1 in an open state, and fig. 1B shows the tire mold 1 in a closed state.

As shown in the drawing, the tire mold 1 is an annular outer mold for molding the outer surface of the tire, and is provided in a tire molding apparatus (tire vulcanizing apparatus). The tire mold 1 surrounds a ring-shaped tire and molds an outer circumferential portion including a tread portion of the tire. Regarding the direction of the tire mold 1, the width direction (mold width direction W) of the tire mold 1 coincides with the tire width direction, and the circumferential direction (mold circumferential direction S) of the tire mold 1 coincides with the tire circumferential direction. The radial direction of the tire mold 1 (mold radial direction) coincides with the tire radial direction.

The tire mold 1 has a plurality of mold segments 2 arranged annularly along the mold circumferential direction S, and a tire is molded by the plurality of mold segments 2. The plurality of mold segments 2 are divided molds, and are divided in the mold circumferential direction S of the tire mold 1. Further, the mold die 2 is a tread mold for molding a tread portion of a tire. In the molding of the tire, the plurality of mold halves 2 are moved in the radial direction of the mold in the tire molding apparatus, and combined in a ring shape to surround the tire.

Fig. 2 is a perspective view showing a mold half 2 according to embodiment 1, and shows the structure of the mold half 2 in a manner that the mold half 2 is seen through. Fig. 3 is a perspective view showing the mold half 2 of embodiment 1 disassembled.

As shown in the drawing, the mold half 2 includes: a plurality of mold pieces 10, the plurality of mold pieces 10 being located on an inner peripheral portion of the tire mold 1; and a holder 3 located at an outer peripheral portion of the tire mold 1. The plurality of mold pieces 10 are molding members for molding a tire, are attached to the mounting portion 3A of the holder 3, and are arranged in order in the mold circumferential direction S.

The holder 3 holds the plurality of mold pieces 10 in the mounting portion 3A located on the inner peripheral side of the tire mold 1. The plurality of die pieces 10 extend in the die width direction W and are arranged adjacent to each other in the die circumferential direction S. In addition, the plurality of die pieces 10 have slit vents 4 formed between adjacent die pieces 10 as gaps for air discharge. The slit exhaust port 4 is a slit-shaped air discharge portion (exhaust portion) that discharges air between the tire and the mold piece 10.

Fig. 4 is a perspective view showing the die piece 10 according to embodiment 1, and shows a part of the die piece 10 among the plurality of die pieces 10 provided in the die 2. Fig. 5 is a perspective view showing a plurality of die pieces 10 provided in the die set 2 of embodiment 1. Fig. 4 (a of fig. 4, B of fig. 4) and fig. 5 (a of fig. 5, B of fig. 5) each show a perspective view as viewed from the inner circumferential side and the outer circumferential side of the tire mold 1.

As shown in the drawing, the die piece 10 includes: a molding portion 11 located on a tire side (an inner circumferential side of the tire mold 1); a back surface portion 12 located on the holder 3 side (on the outer circumferential side of the tire mold 1); and two opposing portions 13, the two opposing portions 13 being located between the forming portion 11 and the back surface portion 12. The mold segment 10 molds a tire using the molding portion 11, and forms a concave portion (for example, a groove or a sipe) in the tire using the protrusion 14 provided in the molding portion 11. The back surface portion 12 is located on the opposite side (back surface side) of the die piece 10 from the molding portion 11, and is in contact with the mounting portion 3A (see fig. 3) of the holder 3. The facing portions 13 are side portions located on both sides of the die piece 10 in the die circumferential direction S. The plurality of die pieces 10 are arranged so that the opposing portions 13 face each other.

The die piece 10 has a convex slit forming portion 15 and a concave accommodating portion 16 in the facing portion 13. The slit forming portion 15 is a portion of the die piece 10 where the slit vent 4 is to be formed, and is formed along the forming portion 11 at the opposing portion 13 of the die piece 10. The plurality of mold pieces 10 are arranged so that the slit forming portions 15 face each other, and the tire is molded by the molding portion 11 in a state where the slit exhaust port 4 (see fig. 2) is formed between the slit forming portions 15. The slit forming portions 15 of the adjacent die pieces 10 face each other with a gap (slit vent 4) formed therebetween, and the slit vent 4 is formed between the slit forming portions 15 of the adjacent die pieces 10.

The receiving portion 16 is a recess formed in the opposing portion 13 of the die piece 10, and receives a part of the retaining member 20. The maintaining member 20 is sandwiched between the facing portions 13 of the adjacent mold pieces 10, and maintains the width of the slit vents 4 (the interval between the adjacent slit forming portions 15). Here, the holding member 20 is a columnar member (e.g., a pin), and the inner surface of the housing portion 16 is formed as a concave arc surface corresponding to the outer peripheral shape of the holding member 20. The plurality of receiving portions 16 are formed at the facing portion 13 of the die piece 10 with a space therebetween, and the plurality of columnar holding members 20 are disposed in the receiving portions 16, respectively.

The receiving portion 16 is formed at a position closer to the back surface portion 12 than the slit forming portion 15 of the opposing portion 13 of the die piece 10, and opens into the back surface portion 12. The holding member 20 is accommodated in the accommodating portion 16 of the adjacent die piece 10, and is sandwiched between the portions of the adjacent die pieces 10 on the side of the slit forming portion 15 on the back surface portion 12 side. The adjacent die pieces 10 are positioned by the retaining member 20, so that the interval between the adjacent slit forming portions 15 is maintained. Thereby, the width of the slit exhaust port 4 is maintained at a predetermined width.

The tire mold 1 includes a plurality of mold pieces 10 in each of the plurality of mold halves 2. The plurality of mold pieces 10 are divided pieces, and are divided in the mold circumferential direction S of the tire mold 1. The facing portion 13 is a divided portion of the die piece 10. In the tire mold 1, the plurality of mold pieces 10 are arranged in a ring shape along the mold circumferential direction S. The following describes a method for manufacturing the tire mold 1.

Fig. 6 to 13 are perspective views showing a manufacturing process of the tire mold 1 according to embodiment 1. Fig. 6 (a of fig. 6, B of fig. 6) shows a perspective view of the tire mold 1 viewed from the inner circumferential side and the outer circumferential side.

As shown in the drawing, a die material 30 including a plurality of die pieces 10 is produced, and the die material 30 is divided into a plurality of die pieces 10. The tire mold 1 is manufactured by forming a plurality of mold pieces 10 from the mold material 30. The die blank 30 is a sheet material to be a blank of the plurality of die pieces 10, and includes a portion to be the plurality of die pieces 10 and a machining allowance of the die pieces 10. Here, the die material 30 is a metal casting. The mold material 30 is cast to form the molded portion 11 including the protrusion 14 of the plurality of mold pieces 10 (see fig. 6). Further, all the die pieces 10 included in 1 die 2 are formed from 1 die material 30. Thus, the die blank 30 is a die material.

When forming the plurality of die pieces 10, first, the back surface portion 31 of the die material 30 is processed. The back surface portion 31 of the die material 30 is a portion corresponding to the back surface portion 12 of the plurality of die pieces 10, and is located on the opposite side (back surface side) of the die material 30 from the forming portion 11 (see fig. 7). The back surface portion 31 of the die material 30 is machined by machining, and the back surface portion 31 of the die material 30 is formed into a shape corresponding to the back surface portion 12 of the die piece 10. At this time, the back surface portion 31 of the die material 30 is formed into a shape that is a part of a cylindrical surface (a shape that is obtained by dividing the cylindrical surface in the circumferential direction). This forms back surface portion 31 of die material 30 into a curved surface having a predetermined curvature.

The die blank 30 is formed in a shape in which a plurality of die segments 10 are continuous. Next, a plurality of blind holes 32 are formed in the die material 30 on the back surface portion 31 side (see fig. 8). The blind hole 32 is a circular non-through hole for accommodating the holding member 20, and is not opened in the forming portion 11 but opened only in the back surface portion 31. The plurality of blind holes 32 are formed at intervals along the respective divided positions of the plurality of die pieces 10 in the die blank 30. The blind hole 32 is formed as a portion (divided position) where the center in the radial direction of the blind hole 32 is located between the adjacent die pieces 10.

Next, a plurality of dividing grooves 33 are formed in the die material 30 on the back surface portion 31 side (see fig. 9). The dividing groove 33 is a concave groove (recessed groove) formed at a dividing position of the plurality of die pieces 10, opens at the back surface portion 31, and is formed along the entire die width direction W of the die material 30. The dividing groove 33 does not penetrate the molding portion 11 of the die material 30, and the bottom of the dividing groove 33 is located between the back surface portion 31 of the die material 30 and the molding portion 11. The width of the dividing groove 33 is larger than the width of the slit exhaust port 4 and smaller than the diameter of the blind hole 32. The depth of the dividing groove 33 is larger than that of the blind hole 32.

Dividing grooves 33 wider than the slit vents 4 are formed along the dividing positions of the plurality of die pieces 10 in the die material 30. The plurality of dividing grooves 33 extend from one end of the die material 30 in the die width direction W to the other end of the die material 30 in the die width direction W, and are formed parallel to each other. Further, at each dividing position of the plurality of die pieces 10, a dividing groove 33 is formed along the dividing position so as to pass through the plurality of blind holes 32. The dividing groove 33 passes through the center of the blind hole 32 in the radial direction so that the center of the dividing groove 33 in the width direction coincides with the center of the blind hole 32 in the radial direction.

A plurality of dividing grooves 33 are formed in the die material 30 on the forming portion 11 side with the remaining portion 34 left. The remaining portion 34 of the die material 30 is an unprocessed portion remaining between the dividing groove 33 and the forming portion 11, and is located between the bottom of the dividing groove 33 and the forming portion 11. The thickness of the remaining portion 34 is smaller than the depth of the dividing groove 33. The entire portion of the die material 30 on the forming portion 11 side remains as a remaining portion 34 in the die material 30 at the entire divided position of the plurality of die pieces 10.

Next, the die material 30 is cut by a laser beam at the bottom of the plurality of dividing grooves 33 by a laser processing machine (laser cutter) (see fig. 10), and the die material 30 is divided in the die circumferential direction S at the laser cutting portion 35. The width of the dividing groove 33 is larger than the cutting width (the width of the laser cutting portion 35) of the die material 30 by laser cutting. The die material 30 is cut at the center of the dividing groove 33 in the width direction, and the die material 30 is cut along the dividing groove 33 at the bottom of the dividing groove 33. The die blank 30 is cut and divided at the dividing positions of the plurality of die pieces 10 by laser cutting. Further, the plurality of die pieces 10 are divided by laser cutting, and the slit forming portions 15 are formed on the forming portions 11 side of the plurality of die pieces 10.

The portion (residual portion 34) between the forming portion 11 of the die material 30 and the bottom of the dividing groove 33 is cut by laser cutting (see fig. 11). The dividing groove 33 includes a 1 st groove portion 33A and a 2 nd groove portion 33B. The 1 st groove portion 33A is a portion of the parting groove 33 on the back surface portion 31 side of the master blank 30. The 2 nd groove portion 33B is a portion on the bottom side of the dividing groove 33 (the molding portion 11 side of the die material 30), and is narrower than the 1 st groove portion 33A. The 1 st groove portion 33A and the 2 nd groove portion 33B are formed by, for example, cutting using an end mill or by electric discharge machining. When the 2 nd groove portion 33B cannot be formed by cutting, the 1 st groove portion 33A is formed by cutting and the 2 nd groove portion 33B is formed by electric discharge machining.

By laser cutting the die material 30, the concave space forming portions 17 are formed in the division grooves 33 of the divided die pieces 10. The space forming portion 17 is formed at the opposing portion 13 of the die piece 10. The plurality of die pieces 10 form discharge spaces 18 for discharging air between the adjacent space forming portions 17. The slit forming portion 15 is a portion of the die material 30 that is cut by the laser beam (the laser-cut portion 35 of the remaining portion 34), and is formed between the forming portion 11 and the bottom of the dividing groove 33. Further, the slit forming portion 15 is formed along the surface of the forming portion 11 including the protrusion 14.

When the base end portion of the sipe blade is joined to the forming portion 11 side of the die material 30 by insert casting (japanese cast metal み) in the die casting when the die material 30 is cast, the entire base end portion of the sipe blade is positioned in the remaining portion 34 (slit forming portion 15) and the 2 nd groove portion 33B in the facing portion 13 of the die piece 10. That is, in the opposing portion 13 of the die piece 10, the width of the remaining portion 34 and the 2 nd groove portion 33B is larger than the length of the base end portion of the sipe blade. For example, when the length of the base end portion of the sipe blade is 5mm, the width of the residual portion 34 and the 2 nd groove portion 33B is 6mm to 7 mm. By so doing, the joining strength of the sipe blade can be ensured.

The thickness of the residual part 34 is a thickness that can be cut by a laser processing machine in one cutting, and is set in accordance with the width of the slit exhaust port 4. For example, when the width of the slit exhaust port 4 is 0.04mm to 0.06mm, the thickness of the residual portion 34 is about several mm. The blind hole 32 is formed shallower than the dividing groove 33 and has a larger diameter than the width of the dividing groove 33. The die material 30 is cut by a laser beam at the bottom of the dividing grooves 33, thereby dividing the blind hole 32. Thereby, the accommodating portion 16 is formed in the blind hole 32 portion of the plurality of divided die pieces 10. Thus, the receptacle 16 is part of the blind hole 32.

A part of the retaining member 20 is accommodated in the accommodating portion 16 of the die piece 10 by each accommodating portion 16 (see fig. 12) of the plurality of accommodating portions 16, and the retaining member 20 is fixed to the die piece 10 by a fixing means (e.g., brazing, bonding, adhesion, welding, bolts, pins). The holding member 20 is accommodated in the accommodating portion 16 of the adjacent mold piece 10, and the holding member 20 is sandwiched between the adjacent mold pieces 10 (see fig. 13). Thus, the plurality of die pieces 10 are combined in a state where the slit vents 4 are formed between the slit forming portions 15. Next, the plurality of mold pieces 10 are held by the holder 3 to form the mold half 2 (see fig. 2 and 3). The tire mold 1 is manufactured by forming all the mold halves 2 of the tire mold 1 in the same step (see fig. 1).

The width of the slit exhaust port 4 is maintained by the maintaining member 20 to be the same as the cutting width by the laser cutting. When the width of the slit exhaust port 4 is different from the cutting width by laser cutting, another holding member 20 having a different size is used. Thereby, the dimension of the retaining member 20 in the width direction of the slit exhaust port 4 is increased or decreased, and the width of the slit exhaust port 4 is changed. The slit exhaust port 4 has a width corresponding to the size of the retaining member 20 and is retained by the retaining member 20. The width of the slit exhaust port 4 is adjusted by changing the width of the slit exhaust port 4. In this state, the plurality of die pieces 10 are combined. When the width of the slit exhaust port 4 is 0.005mm to 0.05mm, the entry of rubber of the tire into the slit exhaust port 4 can be more reliably suppressed during the molding of the tire.

The width of the slit exhaust port 4 can also be adjusted by an adjusting member (not shown). The adjustment member is sandwiched between the adjacent die pieces 10 together with the holding member 20, and the width of the slit vent 4 is adjusted by the adjustment member. The adjusting member is, for example, a plate-like member formed to have a predetermined thickness, and is sandwiched between the holding member 20 and the die piece 10. In this state, the holding member 20 is fixed to the die piece 10. The width of the slit exhaust port 4 can be changed in accordance with the thickness of the adjustment member. For example, it is assumed that the width of the slit exhaust port 4 is maintained at a cutting width (0.04mm) by laser cutting by a maintaining member 20 (dimension: 10 mm). When the width of the slit vent 4 is to be changed to 0.06mm, an adjustment member (thickness: 0.02mm) is sandwiched between the holding member 20 and the die piece 10.

As described above, when forming the die piece 10, the plurality of dividing grooves 33 are formed on the back surface portion 31 side of the die material 30, and the portion to be cut by laser cutting (remaining portion 34) can be made thin. Further, the die material 30 can be easily cut with a laser, and the slit forming portion 15 can be easily formed in the die piece 10. The laser cutting enables accurate division of the plurality of die pieces 10 and enables a cutting width of the die material 30 to be narrow. The machining allowance of the die piece 10 in the die material 30 can be reduced. Therefore, the plurality of mold pieces 10 can be easily formed, and the manufacturing efficiency of the tire mold 1 can be improved. The accuracy of the dimensions of the die piece 10 can be improved.

In the tire mold 1, the width of the slit exhaust port 4 can be easily maintained by the maintaining member 20, and the slit exhaust port 4 can be accurately formed. By accommodating the holding member 20 in the accommodating portion 16, the holding member 20 can be easily and accurately sandwiched between the adjacent die pieces 10. The housing portion 16 can be easily formed in the die piece 10 by laser cutting.

By increasing or decreasing the size of the retaining member 20, the width of the slit exhaust port 4 can be easily changed. The width of the slit exhaust port 4 can be easily adjusted by the adjusting member. Depending on the shape of the facing portion 13 of the die piece 10, the width of the slit vent 4 may vary depending on the change or adjustment of the width of the slit vent 4. In this case, the width of the slit exhaust port 4 is changed or adjusted based on the average value of the width in the slit exhaust port 4.

The width of the slit vent 4 may be adjusted by the difference in thermal expansion between the die piece 10 and the retaining member 20. In this case, the holding member 20 having a thermal expansion coefficient different from that of the mold pieces 10 is sandwiched between the adjacent mold pieces 10. At the time of tire vulcanization, the mold sheet 10 and the holding member 20 expand with a thermal expansion amount corresponding to the respective thermal expansion coefficients (for example, linear expansion coefficients) as they are heated. The width of the slit vent 4 at the time of tire vulcanization changes from the width before heating in accordance with the difference in thermal expansion amount between the mold sheet 10 and the holding member 20. Thereby, the width of the slit exhaust port 4 at the time of tire vulcanization is adjusted.

For example, the die piece 10 is made of an aluminum alloy (linear expansion coefficient: 23X 10)^－6(1/K)), and the holding member 20 (diameter: 10mm) is made of steel (linear expansion coefficient: 11X 10^－6(1/K)). The mold material 30 is processed at room temperature (25 ℃), and the mold sheet 10 and the holding member 20 are heated to the vulcanization temperature (160 ℃) during vulcanization of the tire. In this case, the thermal expansion amount difference is calculated from the equation ((23-11). times.10)^－6X (160-25) × 10), and the difference in thermal expansion amount between the mold sheet 10 and the holding member 20 was 0.016 mm. As a result, the width of the slit exhaust port 4 was narrowed by 0.016mm during vulcanization of the tire.

The holding member 20 may be formed in a shape other than a cylindrical shape (for example, a square column shape, a block shape, or a plate shape). The die material may be an annular material (e.g., an annular casting). The annular mold material is divided in the mold circumferential direction S to form all the mold pieces 10 of the tire mold 1.

(embodiment 2)

Next, a method of manufacturing the tire mold 1 according to embodiment 2 will be described. The method for manufacturing the tire mold 1 according to embodiment 2 is not described with the same items as those of the method for manufacturing the tire mold 1 according to embodiment 1. In addition, as for the configuration of embodiment 2, the same name as that of embodiment 1 is used for the configuration corresponding to embodiment 1.

Fig. 14 is a perspective view showing the die 2 according to embodiment 2, and shows the structure of the die 2 in a manner that the die 2 is seen through. Fig. 15 is a perspective view of the mold half 2 of embodiment 2 shown disassembled. Fig. 16 is a perspective view showing the die piece 10 according to embodiment 2, and shows a part of the die pieces 10 among the plurality of die pieces 10 provided in the die cavity 2. Fig. 17 is a perspective view showing a plurality of die pieces 10 provided in the die set 2 of embodiment 2. Fig. 16 (a of fig. 16, B of fig. 16) and fig. 17 (a of fig. 17, B of fig. 17) each show a perspective view as viewed from the inner circumferential side and the outer circumferential side of the tire mold 1.

As shown in the drawing, the die piece 10 includes a slit forming portion 15 and a concave accommodating portion 19 in the facing portion 13 (see fig. 16). The accommodating portion 19 is formed in the opposing portion 13 of the die piece 10 in the entire die width direction W, and accommodates a part of the retaining member 40. Here, the holding member 40 is a plate-like member, and the surface of the housing portion 19 is formed as a flat surface corresponding to the surface shape of the holding member 40. Further, 1 accommodating portion 19 is formed on the rear surface portion 12 side of the opposing portion 13, and 1 plate-like holding member 40 is disposed in the accommodating portion 19.

Fig. 18 to 22 are perspective views showing a manufacturing process of the tire mold 1 according to embodiment 2. Fig. 21 (a of fig. 21, B of fig. 21) shows a perspective view seen from the inner circumferential side and the outer circumferential side of the tire mold 1.

As shown in the drawing, when forming a plurality of die pieces 10, first, rear surface portion 31 of die material 30 is processed (see fig. 18). Next, a plurality of dividing grooves 33 are formed in the die material 30 on the back surface portion 31 side. A plurality of dividing grooves 33 are formed along the dividing positions of the plurality of die pieces 10 in the die blank 30. Next, the die material 30 is cut by a laser beam at the bottom of the plurality of dividing grooves 33 (see fig. 19). The plurality of die pieces 10 are divided by laser cutting, and slit forming portions 15 are formed on the forming portions 11 side of the plurality of die pieces 10 (see a in fig. 20).

The die material 30 is cut with a laser beam at the bottom of the plurality of dividing grooves 33, thereby partially dividing the dividing grooves 33. Thereby, the housing portion 19 is formed in the divided groove 33 portion of the divided plurality of die pieces 10. Thus, the housing 19 is a part of the dividing groove 33. The holding member 40 has a plurality of discharge grooves 41 (see fig. 20B and 21) for discharging air. A part of the holding member 40 is accommodated in the accommodating portion 19 of the die piece 10, and the holding member 40 is fixed to the die piece 10. The holding member 40 is accommodated in the accommodating portion 19 of the adjacent die piece 10, and the holding member 40 is sandwiched between the adjacent die pieces 10 (see fig. 22). Thus, the plurality of die pieces 10 are combined in a state where the slit vents 4 are formed between the slit forming portions 15. Next, the plurality of mold pieces 10 are held by the holder 3 to form the mold half 2 (see fig. 14 and 15).

As described above, the housing portion 19 can be easily formed in the die piece 10 by laser cutting. Further, the division groove 33 is partially used as the housing portion 19, so that the forming efficiency of the die piece 10 can be improved.

Description of the reference numerals

1. A mold for a tire; 2. a mold half; 3. a holder; 4. a slit exhaust port; 10. a die piece; 11. a forming section; 12. a back portion; 13. a counterpart portion; 14. a protrusion; 15. a slit forming part; 16. an accommodating portion; 17. a space forming part; 18. a discharge space; 19. an accommodating portion; 20. a maintaining member; 30. a die blank; 31. a back portion; 32. blind holes; 33. dividing the groove; 34. a residual part; 35. a laser cutting section; 40. a maintaining member; 41. a discharge groove.