阅读说明：本技术 轮胎用的成形模具的制造方法 (Method for manufacturing tire molding die ) 是由 石原泰之 于 2017-11-15 设计创作，主要内容包括：在通过铸造来制造轮胎用的成形模具时,能够简单地抑制成形模具的铸件产生铸造缺陷,从而提高成形模具的制造效率。成形模具利用沿轮胎宽度方向配置的成形部来成形轮胎。使成形模具的铸件(4)的与轮胎宽度方向对应的宽度方向与铅垂方向一致。使冒口(21)与铸件(4)的位于成形部的背面侧的背面部(4B)的局部连接。在铸件(4)的背面部(4B)的冒口(21)以外的部分配置冷铁(73)。(When a forming mold for a tire is manufactured by casting, casting defects of a casting of the forming mold can be easily suppressed, and manufacturing efficiency of the forming mold can be improved. The forming mold forms a tire by using a forming portion arranged in the tire width direction. The width direction of the casting (4) of the forming die corresponding to the width direction of the tire is made to coincide with the vertical direction. A riser (21) is connected to a part of a back surface section (4B) of the casting (4) located on the back surface side of the molding section. A chill (73) is disposed in a portion of the back surface (4B) of the casting (4) other than the riser (21).)

1. A method for manufacturing a tire molding die for molding a tire by a molding portion arranged in a tire width direction, wherein the tire molding die is manufactured by casting,

a width direction of a casting of a forming mold corresponding to a tire width direction is aligned with a vertical direction, a riser is connected to a part of a back surface portion of the casting located on a back surface side of a forming portion, and a chill is disposed in a portion other than the riser of the back surface portion.

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

chills are disposed at the upper end and the lower end of a casting of a forming die.

3. The manufacturing method of a forming mold for a tire according to claim 1 or 2, wherein,

the riser body is connected to the back surface of the casting by a connecting portion of the riser which is thinner than the riser body.

4. The method for manufacturing a tire forming mold according to any one of claims 1 to 3, wherein,

a metal flask and a reservoir part having a riser having a lower thermal conductivity than the flask are provided on the back surface side of a casting,

the riser of the storage part is connected with a part of the back part,

the portion of the flask in contact with the back surface portion was used as a chill.

5. The method for manufacturing a tire forming mold according to any one of claims 1 to 4, wherein,

molten metal is poured from the feeder head to cast a casting of a mold, and bubbles in the molten metal are floated in the feeder head and separated from the molten metal.

6. The method for manufacturing a tire forming mold according to any one of claims 1 to 5, wherein,

casting a casting of a ring-shaped forming mold, and sequentially separating and connecting a plurality of risers in a circumferential direction of the casting to a back surface portion of the casting, thereby forming a portion having the plurality of solidified risers and a ring-shaped member of the casting of the forming mold,

after the diameter or roundness of the casting of the forming die is corrected by an external force applied to the ring-shaped member, the portions of the plurality of risers are removed from the ring-shaped member.

Technical Field

The present invention relates to a method for manufacturing a tire mold for manufacturing a mold by casting.

Background

In a tire forming mold, a forming portion for forming a tire has a complicated shape, and a separately manufactured plate-like member (e.g., a sipe or a blade) may be fixed to the forming portion. Therefore, a casting method is widely used for manufacturing the forming mold. In particular, when a gypsum mold is used, dimensional accuracy can be improved even in the case of a casting of a metal having a relatively high melting point (for example, an aluminum alloy). In addition, in the gypsum mold, cutting and assembling can be easily performed, and fixing (embedding) of the plate-like member can be easily performed (japanese cast metal み). By using a rubber mold, a complicated shape of the plaster mold can be easily formed.

However, in the gypsum mold, solidification of the molten metal is delayed on the gypsum mold side due to the heat conduction property, and casting defects (shrinkage cavities and the like) may occur in the casting of the forming mold. In contrast, conventionally, chill and a riser are used to suppress the occurrence of casting defects. For example, the chiller is disposed on the lower side or the upper side of the gypsum mold, and the feeder is disposed on the opposite side of the chiller. By solidifying the molten metal from the chill to the feeder head, the generation of a closed space on the plaster mold side is suppressed, and casting defects are reduced. In addition, the following low-pressure casting mold is known: a mold for molding and vulcanizing a tire is cast by filling a molten metal into a mold from below by the pressure of a gas (see patent document 1).

In the conventional low-pressure casting mold described in patent document 1, the molten metal is gradually solidified while being pushed up by the lift pipe. However, in the low-pressure casting, since a path from a riser in a riser to an upper end portion of a casting becomes long, it is difficult to control a solidification direction of the molten metal. Further, since the portion of the mold other than the casting is solidified first, there is a fear that the local replenishment of the molten metal to the casting is hindered. When a casting defect occurs, a countermeasure against the defect (discarding and repairing of a casting, etc.) is necessary, and the manufacturing efficiency of the mold is lowered. Therefore, from the viewpoint of manufacturing efficiency, it is also desired to be able to easily suppress the occurrence of casting defects.

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 improve the manufacturing efficiency of a forming mold by simply suppressing the occurrence of casting defects in a casting of the forming mold when manufacturing the forming mold for a tire by casting.

Means for solving the problems

The present invention relates to a method for manufacturing a tire molding die for molding a tire by using a molding portion arranged in a tire width direction, the method including manufacturing the tire molding die by casting. A width direction of a casting of a forming mold corresponding to a tire width direction is aligned with a vertical direction, a riser is connected to a part of a back surface portion of the casting located on a back surface side of a forming portion, and a chill is disposed in a portion other than the riser of the back surface portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, when a mold for a tire is manufactured by casting, casting defects in a casting of the mold can be easily suppressed, and the manufacturing efficiency of the mold can be improved.

Drawings

Fig. 1 is a plan view of a forming die according to embodiment 1.

Fig. 2 is a sectional view of the molding die of embodiment 1.

Fig. 3 is a perspective view showing a casting of the forming die of embodiment 1.

Fig. 4 is a perspective view showing a casting device of a forming die according to embodiment 1.

Fig. 5 is a perspective view showing a casting device of a forming die according to embodiment 1.

Fig. 6 is a perspective view showing a casting device of a forming die according to embodiment 1.

Fig. 7 is a perspective view showing a casting device of a forming die according to embodiment 1.

Fig. 8 is a perspective view showing a casting device of a forming die according to embodiment 1.

Fig. 9 is a sectional view showing a casting apparatus of a forming die according to embodiment 1.

Fig. 10 is a partial cross-sectional view showing a casting apparatus including a reservoir portion having a riser.

Fig. 11 is a perspective view showing molten metal in the casting apparatus according to embodiment 1.

Fig. 12 is a perspective view showing a cast body according to embodiment 1.

Fig. 13 is a perspective view showing a cast body according to embodiment 1.

Fig. 14 is a perspective view showing an example of a conventional cast body.

Fig. 15 is a perspective view showing a cast body according to embodiment 2.

Fig. 16 is a perspective view showing molten metal in the casting apparatus according to embodiment 2.

Fig. 17 is a perspective view showing a casting of the forming die of embodiment 3.

Fig. 18 is a perspective view showing a cast body according to embodiment 3.

Fig. 19 is a perspective view showing an example of a conventional cast body.

Detailed Description

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

In the method of manufacturing a mold according to the present embodiment, the mold is manufactured by casting, and the mold having a shape corresponding to the shape of the tire is formed. The molding die is a vulcanization die for a tire, and is used at the time of molding (vulcanization) of the tire. The tire is vulcanized while being molded by the molding die.

(embodiment 1)

Fig. 1 is a plan view of a forming die 1 according to embodiment 1, showing the forming die 1 as viewed from the outer side in the width direction of a tire 2. Fig. 2 is a sectional view of the forming die 1 of embodiment 1, showing the forming die 1 taken along line X1-X1 of fig. 1. In fig. 1 and 2, a tire 2 formed by a forming mold 1 is schematically shown by a chain line.

As shown in the drawing, the molding die 1 is an annular outer die for molding the outer surface of the tire 2, and is provided in a molding device (vulcanizing device) of the tire 2. The forming mold 1 surrounds a ring-shaped tire 2 and forms a tread portion 2A of the tire 2.

Regarding the directions of the forming mold 1 and the tire 2, the width direction of the forming mold 1 (mold width direction W1) coincides with the width direction of the tire 2 (tire width direction W2). The radial direction (mold radial direction K1) of the molding die 1 coincides with the radial direction (tire radial direction K2) of the tire 2, and the circumferential direction (die circumferential direction S1) of the molding die 1 coincides with the circumferential direction (tire circumferential direction S2) of the tire 2.

The forming mold 1 includes a plurality of (here, 9) divided molds 3 arranged in this order along the tire circumferential direction S2 (mold circumferential direction S1). The plurality of split molds 3 are segments split in the mold circumferential direction S1, and are tread molds that form the tread portion 2A of the tire 2. The forming mold 1 includes a forming portion 3A formed on the tire 2 side and a back surface portion 3B formed on the back surface side in each divided mold 3. The rear surface portion 3B is located on the opposite side (outside in the tire radial direction K2 (mold radial direction K1)) of the molding portion 3A in the molding die 1 and the split die 3.

When forming the tire 2, the plurality of split molds 3 are combined into a ring shape with their ends in contact with each other, and surround the tire 2. In this state, the molding die 1 and the molding section 3A are arranged along the tire width direction W2 (die width direction W1). The forming mold 1 is in contact with the tire 2 (tread portion 2A) at a forming portion 3A of the split mold 3, and the tire 2 is formed by the forming portion 3A. The forming portion 3A forms a recess (e.g., groove, sipe) in the tread portion 2A of the tire 2 by the plurality of protrusions 3C.

Fig. 3 is a perspective view showing a casting 4 of the forming die 1 according to embodiment 1.

As shown in the drawing, the forming die 1 is a die made by casting a metal (e.g., an aluminum alloy), and is made of a casting 4. The casting 4 is a product portion to be a casting body of the forming die 1, and is formed by casting. The plurality of split molds 3 are formed by, for example, splitting the annular casting 4 in the circumferential direction S4 (the mold circumferential direction S1). Thus, the casting 4 of the forming mold 1 is a raw material (mold raw material) of the forming mold 1 and the split molds 3, and includes a plurality of split molds 3. The casting 4 is formed in an annular shape corresponding to the annular forming die 1.

The casting 4 of the molding die 1 has a molding portion 4A corresponding to the molding portion 3A of the molding die 1 (divided die 3) and a back surface portion 4B located on the back surface side of the molding portion 3A (molding portion 4A). The forming portion 4A is an inner peripheral portion of the casting 4, and is formed in an annular shape in an inner portion of the casting 4 in the radial direction K4 (the mold radial direction K1). The back surface portion 4B is an outer peripheral portion of the casting 4 located on the opposite side of the forming portion 4A, and is formed in a ring shape on an outer portion of the casting 4 in the radial direction K4. The back surface portion 4B is a portion corresponding to the back surface portion 3B of the molding die 1, and is formed on the opposite side (back surface side) of the molded portion 3A (molded portion 4A) from the cast 4.

The width direction W4 of the casting 4 is a direction corresponding to the mold width direction W1 and the tire width direction W2, and the circumferential direction S4 of the casting 4 is a direction corresponding to the mold circumferential direction S1 and the tire circumferential direction S2. The radial direction K4 of the casting 4 corresponds to the mold radial direction K1 and the tire radial direction K2. The casting 4 of the mold 1 is cast by the casting device of the mold 1 and is integrated with other parts (a riser part and the like). When the casting 4 is cast, the width direction W4 of the casting 4 is arranged along the vertical direction.

Fig. 4 to 8 are perspective views showing a casting device 10 of a forming die 1 according to embodiment 1. Fig. 4 shows the entire casting apparatus 10 after disassembly, and fig. 5 to 8 show a state in which the respective parts of the casting apparatus 10 are combined in order.

As shown in the drawing, the casting apparatus 10 forms an annular cast body 5 (see fig. 4) including a cast 4 of the forming mold 1 and a plurality of bellmouths 20 by casting (here, gravity casting). The plurality of riser portions 20 are portions of respective solidified risers, are formed in sequence along the circumferential direction S4 of the casting 4, and are connected to the back surface portion 4B of the casting 4.

The casting apparatus 10 includes a disk-shaped table 30, a disk-shaped flat plate 31, a plurality of heat insulators 32, an annular mold 40, a plurality of riser storage portions 50, a disk-shaped upper plate 33, a plurality of gate members 60, and an annular flask 70. The flat plate 31 (see fig. 5) is disposed in the center of the table 30 and held by the table 30. The plurality of heat insulators 32 are disposed around the flat plate 31 on the upper surface portion of the table 30. The plurality of heat insulators 32 are disposed at equal intervals along the outer periphery of the flat plate 31. The mold 40 is placed on the flat plate 31 and disposed in the center of the table 30. The plurality of gate members 60 extend upward from the heat insulator 32 and are arranged so as to surround the mold 40.

The storage sections 50 (see fig. 6) of the plurality of risers are placed on the heat insulator 32 and arranged around the mold 40. The plurality of storage sections 50 are disposed at positions separated from the mold 40, and surround the mold 40 outside the mold 40. The 8 reservoirs 50 are arranged at equal intervals along the outer periphery of the mold 40, and the gate members 60 are housed in the 4 reservoirs 50. The reservoir portions 50 that house the gate members 60 and the reservoir portions 50 that do not house the gate members 60 are alternately arranged along the outer peripheral portion of the mold 40. The outer periphery of the mold 40 is a mold part 41 for molding the molding part 4A of the casting 4, and the reservoir 50 faces the mold part 41 of the mold 40.

The flask 70 (see fig. 4) has a plurality of opposing portions 71 that face the mold portions 41 of the mold 40, and a plurality of protruding portions 72 that protrude from the opposing portions 71 toward the opposite side of the mold 40. The facing portions 71 and the projections 72 are alternately formed, and the plurality of projections 72 project radially. The flask 70 (see fig. 7) is placed on the table 30 and surrounds the mold 40 and the plurality of reservoirs 50. The entirety of the mold 40 and the lower portion of the reservoir 50 are housed inside the sand box 70.

The plurality of reservoir portions 50 are respectively disposed inside the protruding portions 72 of the flask 70, and are held by the protruding portions 72. The opposing portions 71 of the sand box 70 are located between adjacent reservoirs 50. The opposing portion 71 of the flask 70 and the portion of the reservoir 50 on the mold 40 side form an annular wall portion continuous along the outer peripheral portion (mold portion 41) of the mold 40, and face the mold portion 41 of the mold 40. The upper plate 33 (see fig. 8) is placed on the mold 40 and the flask 70, and contacts the upper end of the mold 40 and the opposing portion 71 of the flask 70.

Fig. 9 is a sectional view of the casting apparatus 10 of the forming die 1 according to embodiment 1, and shows the casting apparatus 10 taken along line X2-X2 in fig. 8. In fig. 9, the gate member 60 is schematically shown by a chain line.

As shown in the drawing, the casting apparatus 10 includes a lower plate 34 composed of a table 30 and a flat plate 31. The flat plate 31 is accommodated in the recess 35 of the table 30, and the upper surface portion of the flat plate 31 and the upper surface portion of the table 30 are continuous. The upper plate 33 is disposed above the lower plate 34, and the upper plate 33 and the lower plate 34 face each other in the vertical direction. The mold 40 is a mold member for forming the forming portion 4A of the casting 4 by the mold portion 41. The mold 40 is a plaster mold made of plaster, and is disposed inside the flask 70 and the reservoir 50 of the plurality of risers 21. The mold part 41 of the mold 40 is formed in a shape corresponding to the shape of the tire 2 (tread part 2A) molded by the molding die 1, and is provided on the outer periphery of the mold 40.

The mold 40, the opposing portion 71 of the flask 70, and the portion of the reservoir 50 on the mold 40 side are disposed between the lower plate 34 and the upper plate 33. The casting space 11 for the casting 4 is formed by the mold 40, the opposing portion 71 of the flask 70, the reservoir portion 50, the lower plate 34, and the upper plate 33. The casting space 11 is a space for casting the casting 4 of the forming mold 1, and is formed in a ring shape in the casting device 10. The upper end of the casting space 11 is divided by an upper plate 33, and the lower end of the casting space 11 is divided by a lower plate 34. The inner periphery of the casting space 11 is defined by the mold 40 (mold portion 41), and the outer periphery of the casting space 11 is defined by the opposing portion 71 of the flask 70 and the reservoir 50.

When casting the casting 4 of the forming mold 1, a part of the plurality of reservoir portions 50 is used as a molten metal pouring portion (pouring portion) and the molten metal is poured into the casting space 11. The molten metal injection portion is a reservoir portion 50 that receives a tubular gate member 60. The molten metal is injected into the reservoir 50 through the gate member 60 and is stored in the reservoir 50. Further, the molten metal is poured from the reservoir 50 into the casting space 11, and is filled in the casting space 11. In the reservoir 50 not housing the gate member 60, the molten metal is poured from the casting space 11 into the reservoir 50 and is stored in the reservoir 50. The molten metal in the plurality of reservoirs 50 serves as risers 21 with respect to the casting space 11 and the casting 4. The plurality of risers 21 are arranged in sequence in the circumferential direction S4 of the casting 4 and are separated from each other in the circumferential direction S4 of the casting 4. Here, the 8 risers 21 are arranged at equal intervals along the circumferential direction S4 of the casting 4 (the circumferential direction of the casting space 11).

The plurality of heat insulators 32 are sheet members having heat insulating properties, and are respectively provided between the storage portion 50 and the lower plate 34 (here, the table 30). The storage section 50 is a hollow feeder unit for storing the feeder 21, and replenishes the molten metal in the feeder 21 to the casting space 11. The reservoir 50 has a cylindrical housing 51 for housing the feeder head 21, and a supply portion 52 located between the housing 51 and the casting space 11. The housing portion 51 is disposed upward from the lower plate 34 and protrudes upward relative to the supply portion 52. The supply unit 52 connects the housing unit 51 to the casting space 11, and supplies the feeder head 21 in the housing unit 51 to the casting space 11. The molten metal in the riser 21 is supplied to the casting space 11 through the supply portion 52.

The space in the housing portion 51 is a housing space 53 (storage space) for housing the feeder head 21, and the space in the supply portion 52 is a supply passage 54 (replenishment passage) for the feeder head 21. The supply passage 54 is located between the housing space 53 of the riser 21 and the casting space 11, and opens toward the housing space 53 and the casting space 11. The riser 21 is supplied from the storage space 53 to the casting space 11 through the supply passage 54.

Among the risers 21 stored in the storage section 50, the riser 21 in the storage section 51 (storage space 53) is a main body of the riser 21 (riser main body 22), and the riser 21 in the supply section 52 (supply passage 54) is a connecting section 23 of the riser 21. The supply passage 54 and the connection portion 23 are formed in the radial direction K4 of the casting 4. In the storage section 50, the connecting section 23 is located between the feeder head main body 22 and the casting space 11, connects the feeder head main body 22 and the casting space 11, and replenishes the feeder head 21 (molten metal) of the feeder head main body 22 to the casting space 11.

Fig. 10 is a partial cross-sectional view of the casting apparatus 10 including the reservoir 50 of the feeder 21, and shows the casting apparatus 10 taken along line X3-X3 of fig. 9.

As shown in the drawing, the supply passage 54 in the supply portion 52 is narrower than the housing space 53 in the housing portion 51 when viewed in a horizontal cross section, and gradually narrows from the housing space 53 toward the casting space 11. By making the supply passage 54 thinner (narrower) than the housing space 53, the connecting portion 23 of the riser 21 is made thinner (narrower) than the riser main body 22.

The upper plate 33, the lower plate 34, and the sand box 70 (see fig. 9) are made of metal (e.g., steel or cast iron) and used as chills 36, 37, and 73, respectively. Specifically, the upper plate 33 is a chill 36 (1 st chill) on the upper end side that cools the upper end portion of the casting 4, and the lower plate 34 is a chill 37 (2 nd chill) on the lower end side that cools the lower end portion of the casting 4. The facing portion 71 of the flask 70 is a chill 73 (No. 3 chill) on the back surface side where the back surface portion 4B of the casting 4 is cooled, and is disposed between the two chills 36 and 37. When casting the casting 4 of the mold 1, chills 36 and 37 are provided at the upper end and the lower end of the casting space 11, and the chills 36 and 37 are disposed at the upper end and the lower end of the casting 4. Further, chill 73 is provided on the back surface of casting space 11, and chill 73 is disposed in a part of back surface 4B of cast 4.

The upper end and the lower end of the casting space 11 correspond to the upper end and the lower end of the casting 4, respectively, and the rear surface of the casting space 11 corresponds to the rear surface 4B of the casting 4. The metal chills 36, 37, 73 are exposed to the casting space 11 and come into contact with the molten metal. The casting 4 of the forming mold 1 is cast while adjusting the solidification (cooling) of the molten metal in the casting space 11 by the chills 36, 37, 73. The upper end portion of casting 4 is formed by chill 36 (upper plate 33), and the lower end portion of casting 4 is formed by chill 37 (lower plate 34). The forming portion 4A of the casting 4 is formed by the mold portion 41 of the mold 40, and the back surface portion 4B of the casting 4 is formed by the chill 73 (the opposing portion 71 of the flask 70) and the reservoir 50. The reservoir 50 is formed of a material (e.g., sand, ceramic) having a lower thermal conductivity than the upper plate 33, the lower plate 34, and the sand box 70.

The metal flask 70 and the reservoir 50 having a lower thermal conductivity than the flask 70 are disposed on the back surface side of the casting space 11 and on the back surface 4B side of the casting 4. When casting the casting 4, the riser 21 of the stock unit 50 is supplied to a part of the back surface portion of the casting space 11 and is connected to a part of the back surface portion 4B of the casting 4. The portion of the flask 70 that contacts the back surface portion 4B is used as the chill 73, and the portion of the back surface portion 4B that contacts the flask 70 is molded by the flask 70. The portion of the flask 70 that contacts the back face portion 4B is the opposing portion 71 of the flask 70. The opposing portions 71 (chills 73) and the storage portions 50 (risers 21) are alternately arranged along the back surface portion 4B. The chills 73 are respectively disposed between the two risers 21 (connecting portions 23), and the risers 21 are respectively disposed between the two chills 73.

When the casting 4 of the forming mold 1 is cast, the casting space 11 of the casting 4 is formed in the casting apparatus 10 by aligning the width direction W4 of the casting 4 with the vertical direction. The reservoir 50 of the feeder 21 is connected only to a part of the back surface of the casting space 11, and the feeder 21 is connected only to a part of the back surface 4B of the casting 4. In the storage section 50, the riser 21 of the riser body 22 is supplied toward the casting space 11 by the connecting section 23 which is thinner than the riser body 22, and the riser 21 and the riser body 22 are connected to the back surface section 4B of the casting 4. A chill 73 (the opposing portion 71 of the flask 70) is provided in a portion of the casting space 11 other than the reservoir 50 on the back side, and the chill 73 is disposed in a portion of the casting 4 other than the riser 21 in the back side 4B. Accordingly, chill 73 is disposed in the rear surface portion 4B except for the connection portion 23. In back surface portion 4B, chill 73 is disposed in a part other than riser 21 and connecting portion 23.

The molten metal is poured into the reservoir 50 (the receiving portion 51) through the gate member 60, and is poured from the reservoir 50 into the casting space 11. The molten metal is poured into the receiving portion 51 (receiving space 53) and is poured into the casting space 11 through the supply portion 52 (supply passage 54). The gate member 60 is a supply pipe of molten metal stored in the storage portion 51, and is disposed along the vertical direction. An upper end 61 of the gate member 60 is located at an upper end of the receiving portion 51, and a lower end 62 of the gate member 60 is located at a lower end of the receiving portion 51.

The molten metal is poured into the upper end portion 61 of the gate member 60 and is supplied into the reservoir portion 50 from the lower end portion 62 of the gate member 60. The lower end 62 of the gate member 60 is bent toward the opposite side of the casting space 11 (casting 4) and is arranged along the wall surface of the housing 51. The molten metal is supplied along the wall surface of the housing portion 51 by the lower end portion 62 of the gate member 60, and flows along the wall surface of the housing portion 51.

Fig. 11 is a perspective view showing molten metal in the casting apparatus 10 according to embodiment 1, and shows a riser 21 and a part of the molten metal in the casting space 11.

As shown in the drawing, in the reservoir 50 that houses the gate member 60, the molten metal flows along the wall surface of the housing 51, and a vortex of the molten metal is generated in the riser body 22 in the housing 51 (see arrow F). Thereby, bubbles in the molten metal are floated in the riser 21 and separated from the molten metal.

When the molten metal is injected, gas (air or the like) is entrained in the molten metal, and bubbles are generated in the molten metal. In the molten metal, buoyancy acts on the bubbles. Further, the vortex applies a centrifugal force to the molten metal and also applies a force (centripetal force) toward the center of the vortex to the bubbles. The bubbles move by the vortex while moving toward the center portion of the vortex. The central part of the vortex is a stagnant part of the molten metal, and the bubbles are concentrated in the central part of the vortex. In the central part of the vortex, the bubbles float up in the molten metal, separating from the molten metal.

The molten metal is poured into the casting space 11 by removing bubbles from the molten metal (see fig. 9) and pouring the molten metal into the casting space 11 from the feeder head 21. Further, the casting space 11 is filled with molten metal, and the riser 21 is stored in the storage section 50. The molten metal in the casting space 11 is cooled by the chills 36, 37, 73 and gradually solidifies. At this time, the molten metal is replenished from the riser 21 to the casting space 11. The molten metal in the casting space 11 is solidified to cast the casting 4 of the forming mold 1. The riser 21 of the reservoir 50 is solidified, and the solidified riser 20 is formed in the reservoir 50.

The solidification of the molten metal is started not from the mold 40 side but from the chills 36, 37, 73 due to the heat conduction characteristics of the gypsum mold 40. On the back surface portion 4B side of the casting 4, the molten metal is solidified from the chill 73 toward the mold 40. With this, the solidification of the molten metal proceeds in the thickness direction of the casting 4, and the molten metal solidifies from the back surface portion 4B of the casting 4 to the forming portion 4A. At this time, the molten metal in the riser 21 is replenished from the rear surface portion 4B side, so that the molten metal is smoothly supplied to the casting space 11 by solidification of the molten metal. Further, the path from the feeder head 21 to the forming section 4A is shorter than conventional, and the molten metal in the feeder head 21 can be reliably replenished. Thereby suppressing the generation of casting defects (e.g., shrinkage cavities) in the casting 4. The solidification of the molten metal proceeds from the position of the chill 73 in the circumferential direction S4 of the casting 4, thereby also shortening the solidification time of the molten metal.

The solidification of the molten metal proceeds from the chills 36, 37 in the width direction W4 of the casting 4 on the upper end side and the lower end side of the casting 4. Thereby, the solidification of the molten metal proceeds along the mold portion 41 of the mold 40 in addition to the solidification of the molten metal from the rear surface portion 4B side. Therefore, the generation of casting defects is suppressed while shortening the solidification time of the molten metal. After solidification of the molten metal in the casting apparatus 10 is completed, the casting apparatus 10 is disassembled, and the cast body 5 is taken out.

Fig. 12 and 13 are perspective views showing the cast body 5 according to embodiment 1. Fig. 12 shows the cast body 5 as viewed from the upper end portion side of the feeder head 20, and fig. 13 shows the cast body 5 as viewed from the lower end portion side of the feeder head 20.

As shown in the drawing, when the casting 4 of the mold 1 is cast, the annular casting 4 is cast, and the plurality of risers 21 are sequentially separated in the circumferential direction S4 of the casting 4 and connected to the back surface portion 4B of the casting 4. Thereby forming the cast body 5. The cast body 5 is an annular member 5A, and has a portion (riser portion 20) having a plurality of solidified risers 21 and the casting 4 of the forming die 1. The plurality of riser parts 20 project radially outward in the radial direction K4 of the casting 4.

After the annular member 5A (cast body 5) is formed, an external force is applied to the annular member 5A, and the shape of the casting 4 of the forming die 1 is corrected by the external force. Here, the casting 4 is deformed by an external force applied to the annular member 5A, and the diameter or roundness of the casting 4 is corrected. For example, an external force in the radial direction K4 is applied to the casting 4 by the straightening device to change the diameter or roundness of the casting 4. Thereby, the diameter or roundness of the casting 4 is corrected to a value within a predetermined allowable range. The correction device is, for example, an expansion device (dilator, etc.), a compression device, or a compression device.

An external force in the radial direction K4 is applied to the casting 4 by a straightening device (expanding device) to expand the casting 4 (wholly or partially) and increase the diameter of the casting 4. Further, an external force in the radial direction K4 is applied to the casting 4 by a straightening device (compression device) to compress the casting 4 (wholly or partially) and reduce the diameter of the casting 4. This corrects the diameter or roundness of the casting 4.

When the casting 4 is corrected, the annular casting 4 is reinforced by the plurality of flash portions 20. Therefore, the casting 4 is accurately corrected while maintaining the shape of the forming portion 4A of the casting 4. Further, the end portions (upper end portion, lower end portion) in the width direction W4 of the casting 4 are suppressed from spreading outward in the radial direction K4 with respect to the central portion in the width direction W4 of the casting 4, and the entire casting 4 is accurately corrected. After the casting 4 is corrected, the plurality of flash portions 20 are removed from the annular member 5A by cutting the flash portions 20, etc., to produce the casting 4 of the forming die 1. Next, a plurality of divided molds 3 of the molding die 1 are formed from the casting 4 (see fig. 1).

Fig. 14 is a perspective view showing an example of conventional cast bodies 100 and 101, and shows two cast bodies 100 and 101 of a casting 4 including a forming die 1.

As shown in the drawing, in one casting 100 (see a in fig. 14), a plurality of columnar feeder heads 103 are formed at the upper end portion of the casting 4 by solidification of the plurality of feeder heads 102. In the other casting 101 (see B in fig. 14), one annular riser 105 is formed at the upper end of the casting 4 by solidification of one riser 104. In the conventional castings 100, 101, the risers 102, 104 are connected to the upper end of the casting 4, and the path from the risers 102, 104 to the lower end of the casting 4 is long. Therefore, casting defects may occur, and the solidification time of the molten metal may be prolonged.

In contrast, in the cast product 5 (see fig. 12) according to embodiment 1, the casting defect in the casting 4 of the forming die 1 can be easily suppressed, and the manufacturing efficiency of the forming die 1 can be improved. In addition, the quality of the casting 4 can be improved, and the solidification time of the molten metal can be shortened as compared with the conventional case. By using a part of the flask 70 as the chill 73, solidification of the molten metal can be easily adjusted. Since the thermal conductivity of the reservoir 50 is lower than that of the flask 70, solidification of the feeder head 21 is suppressed, and the molten metal in the feeder head 21 can be smoothly replenished. By separating the bubbles in the riser 21, the occurrence of casting defects (bubble defects) can be easily suppressed.

By making the connecting portion 23 of the riser 21 thinner than the riser main body 22, it is possible to suppress the flow of bubbles from the riser 21, and more reliably separate bubbles in the riser 21. Further, a vortex is easily generated in the riser body 22, and separation of bubbles can be performed more reliably in the center of the vortex. Since the connecting portion 23 has a small volume, the amount of the riser 21 can be reduced. By separating the riser part 20 from the casting 4 at the position of the connecting part 23, the riser part 20 can be easily removed.

Next, other embodiments will be explained. In the following other embodiments, the same matters as those in embodiment 1 are omitted, and matters different from embodiment 1 are described.

(embodiment 2)

Fig. 15 is a perspective view showing the cast body 6 according to embodiment 2, and shows the cast body 6 in the same manner as fig. 12. Fig. 16 is a perspective view showing molten metal in the casting apparatus 10 according to embodiment 2, and shows a local portion of the molten metal in the casting space 11 and the riser 21, similarly to fig. 11.

As shown in the drawing, in the supply portion 52 of the reservoir portion 50, the supply passage 54 and the connection portion 23 are inclined with respect to the radial direction K4 of the casting 4. The connecting portions 23 of the plurality of risers 21 are inclined to the same side in the circumferential direction S4 of the casting 4 with respect to the radial direction K4 of the casting 4. This makes it easier to generate a vortex in the riser body 22, and thus more reliably separates bubbles.

(embodiment 3)

Fig. 17 is a perspective view showing a casting 7 of the forming die 1 according to embodiment 3. Fig. 18 is a perspective view showing a cast body 8 according to embodiment 3.

As shown in the drawing, the casting 7 is a casting of one split mold 3 of a plurality of split molds 3 (see fig. 1) of the forming mold 1. Therefore, the forming die 1 is a split die 3 here. The casting 7 of the molding die 1 (divided die 3) has a molding portion 7A and a back surface portion 7B, and is formed in a block shape. The shaped portion 7A of the casting 7 corresponds to the shaped portion 4A of the casting 4, and the back surface portion 7B of the casting 7 corresponds to the back surface portion 4B of the casting 4. One riser 21 is connected to a part of the back surface portion 7B, and chill is disposed in a portion of the back surface portion 7B other than the riser 21. The flasks are arranged along both side surfaces of the casting 7, the back surface portion 7B, and the reservoir 50.

Fig. 19 is a perspective view showing an example of conventional cast bodies 110 and 111, and shows two cast bodies 110 and 111 of the casting 7 including the forming die 1.

As shown in the drawing, in one casting 110 (see a in fig. 19), a columnar riser 113 is formed at the upper end of the casting 7 by solidification of the riser 112. In the other casting 111 (see B in fig. 19), a plate-like riser 115 is formed at the upper end of the casting 7 by solidification of the riser 114. In the cast body 8 of the casting 7 according to embodiment 3, the occurrence of casting defects can be easily suppressed as compared with the conventional cast bodies 110 and 111.

The above description has been made of an example in which the castings 4, 7 are cast by gravity casting, but the castings 4, 7 may be cast by low-pressure casting. In the low-pressure casting, the cast bodies 5, 6, 8 are formed in a shape upside down with respect to the shape shown in fig. 12, 15, and 18. Molten metal is poured from the respective feeder heads 21. A dam runner (runner) may be connected to the lower portion of the casting 4 independently of the riser 21, and the molten metal may be poured from the runner into the casting space 11 and the reservoir 50.

(casting test of casting)

In order to confirm the effect of the present invention, a test was performed to cast the casting 4 of the mold 1 by the above-described manufacturing method. The test conditions are as follows.

Shape of the casting 4: annular shape of a casting comprising 9 divided moulds 3

Size of casting 4: inside diameter (phi 600mm), width (300mm), minimum wall thickness (50mm)

Material of the mold 40: non-foamed gypsum (Noritake Co., Ltd., product name: G-6, manufactured by Ltd.)

Material of casting 4 (molten metal): aluminum alloy (AC 7A: JIS specification) (4% Mg, 0.2% Si)

The sand box 70: ring flask made of spheroidal graphite cast iron, height (300mm), wall thickness (30mm to 50mm) material of lower plate 34 (table 30, flat plate 31): steel for general Structure (SS 400: JIS Standard)

Material of the upper plate 33: steel materials for general structural use (SS 400: JIS specification),

material of the reservoir 50: heat insulating material (ceramic fiber molding)

Temperature of molten metal: 670 deg.C

(embodiment 1)

In embodiment 1 (see fig. 12), 8 risers 21 are arranged at equal intervals in the circumferential direction S4 of the casting 4 to form the casting 5. The diameter of the riser body 22 is phi 100mm, and the height of the riser body 22 is 600 mm. The height of connecting portion 23 of riser 21 was 270mm, and the width of the portion of connecting portion 23 connected to back surface portion 4B was 30 mm. A reservoir 50 (width (110mm)) is disposed around the riser 21. The temperature of the flask 70, the lower plate 34 and the upper plate 33 before the molten metal is poured is room temperature (about 30 ℃). Molten metal is poured into the dam-type runner to cast a casting 4. The amount of molten metal injected was 7kg per second (7 kg/sec). In the casting 4 of example 1, shrinkage cavities and bubble defects were hardly generated in the casting 4, and generation of casting defects was suppressed. In addition, the quality of the casting 4 is judged to be good.

(comparative example 1)

Comparative example 1 (see fig. 14 a) is a comparative test with respect to example 1. The 8 risers 102 are arranged at equal intervals at the upper end of the casting 4 to form a casting 100. The diameter of the riser 102 is 90mm and the height of the riser 102 is 300 mm. Other conditions are the same as those of example 1. In the casting 4 of comparative example 1, although the blister defects were relatively small, a large number of shrinkage cavities were generated in the forming portion 4A of the casting 4. In addition, the quality of the casting 4 is determined to be poor. On the other hand, even if the material of the upper plate 33 was changed to a heat insulating material (calcium silicate plate), no change was found in the casting defect even if the flask was preheated to 250 ℃.

(embodiment 2)

In example 2 (see fig. 11), molten metal is poured from the riser 21, and bubbles are separated from the molten metal by eddy currents in the riser 21. The riser 21 into which the molten metal is injected is a riser 21 that houses the 4 reservoirs 50 of the gate member 60. The amount of molten metal poured (the total value at 4) was 16kg per second (16 kg/sec). Other conditions are the same as those of example 1. In the casting 4 of example 2, the occurrence of casting defects (shrinkage cavity, bubble defects) was suppressed and the quality was judged to be good, as in the casting 4 of example 1. In addition, the generation of bubble defects is more reliably suppressed.

(comparative example 2)

Comparative example 2 (see fig. 14 a) is a comparative test with respect to example 2. As compared with comparative example 1, the molten metal was poured from the locations of 4 risers 102, thereby forming a cast body 100. The amount of molten metal poured (the total value at 4) was 16kg per second (16 kg/sec). In the casting 4 of comparative example 2, a large number of shrinkage cavities were generated in the forming portion 4A of the casting 4, as in the casting 4 of comparative example 1. Further, a large number of bubble defects (phi 0.3mm to phi 5mm) were generated in the forming portion 4A of the casting 4, and the quality of the casting 4 was determined to be poor.

(embodiment 3)

In embodiment 3 (see fig. 12), an external force is applied to the annular member 5A (cast body 5) formed in embodiment 2 to correct the diameter of the casting 4. The casting 4 is corrected in a state where the plurality of riser portions 20 are connected to the casting 4. Further, a force in the outer side of the radial direction K4 was applied to the end portions (upper end portion and lower end portion) of the casting 4, and the diameter of the central portion of the casting 4 was increased by approximately 0.4 mm. After the casting 4 is corrected, the plurality of flash portions 20 are removed. In the casting 4 of embodiment 3, the amount of change in the radius of the end portion is 0.07mm larger than the amount of change in the radius of the central portion. As a result, the difference between the two variations is within the allowable range.

(comparative example 3)

Comparative example 3 (see fig. 12) is a comparative test with respect to example 3. After removing the plurality of flash portions 20 from the ring-shaped member 5A formed in embodiment 2, the central portion of the casting 4 is increased in diameter by about 0.4mm as in embodiment 3. In the casting 4 of comparative example 3, the amount of change in the radius of the end portion was 0.21mm larger than the amount of change in the radius of the central portion. As a result, the difference between the two variation amounts is a value outside the allowable range.

Description of the reference numerals

1 … forming die, 2 … tire, 3 … split die, 4 … casting, 5 … casting, 6 … casting, 7 … casting, 8 … casting, 10 … casting device, 11 … casting space, 20 … riser part, 21 … riser, 22 … riser body, 23 … connecting part, 30 … table, 31 … flat plate, 32 … insulator, 33 … upper plate, 34 … lower plate, 35 … recess, 36 … chill, 37 … chill, 40 … mold, 41 … mold part, 50 … reservoir, 51 … receiver, 52 … feeder, 53 … receiver space, 54 … feeder passage, 60 … gate member, 61 … upper end, 62 … lower end, 70 … sand box, 72 71 … phase, 72 … protrusion, 73 chill, 73 ….