JP2000246420A - Casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the formation with a metal having desirable composition in a specifying range of a cast product. SOLUTION: In a casting method for pouring the molten metals having different compositions into a single cavity 14 from different compositions into a single cavity 14 from different runners 22, 24 in a mold 10, the cavity 14 provided with chambers 14d at the down side, chamber 14u at the upper side and contracting parts 14f between both chambers, is formed, and after filling portions from the chambers 14d at the down sides to the contracting parts 14f in the cavity 14 with a prescribed molten metal, the molten metal having the different composition is poured with the chamber 14u at the upper side. In this way, in the chamber 14d at the down side in the cavity 14, the mixture of both molten metals is scarcely developed by function the contracting parts 14f.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method for injecting molten metals having different compositions from separate runners of a mold into a single cavity.

[0002]

2. Description of the Related Art A related casting method is described in Japanese Patent Application Laid-Open No. 6-238423, and FIG. 4 is a schematic cross-sectional view of a mold used in this casting method. In the cavity 2 of the mold 1, four runners 3, 4,
5, 6 are connected, of which two runners 3, 4
Communicates with the first gate 7a via the first pool 7b. The remaining two runners 5, 6 communicate with the second gate 8a via the second pool 8b. As shown in FIG. 3, the cavity 2 has a substantially flat central portion and slightly elevated left and right ends. Runners 3, 4, 5, and 6 are connected near the central portion and at the left and right ends. ing.

In the casting method, a melt A having a composition excellent in formability and weldability is injected from a first gate 7a, and a melt B having a composition excellent in strength is injected from a second gate 8a. Thus, separate runners 3, 4, from the left and right gates 7a, 8a.
Since the melts having different compositions are injected into the cavity 2 through the parts 5 and 6, it is possible to integrally mold cast products having different compositions at the right end and the left end of the product.

[0004]

However, as described above, the cavity 2 of the mold 1 used in the casting method is as follows.
The central part is almost flat and the left and right ends are slightly higher. Further, there is nothing in the cavity 2 that suppresses the flow of the molten metal in the left-right direction. Therefore, the first gate 7 on the left side
a flows through the runners 3 and 4 from the left to the right of the cavity 2, and flows from the second gate 8a on the right side into the runners 5 and 5.
6 flows from right to left of the cavity 2. Therefore, the two types of molten metal injected into the cavity 2 are mixed in a wide range, and it is difficult to form a predetermined portion with a metal having a desired composition. In particular,
When it is desired to form a narrow area of a casting with a metal having a desired composition, it is impossible to prevent the molten metal poured into the narrow area from being mixed with the molten metal in other parts by the above-described casting method. Further, it is impossible to fill a lower portion of the mold with a molten metal having a low specific gravity and hold the molten metal at that position.

[0005] Therefore, claims 1 and 2 of the present invention.
The object of the invention described in (1) is to make it possible to form a specific range of a casting with a metal having a desired composition by making it difficult for molten metals having different compositions to mix.

[0006]

The above object is achieved by a casting method according to the present invention. According to the invention, the cavity of the mold comprises a lower chamber and an upper chamber,
And a throttle section between the two rooms. For this reason, after filling the space from the lower chamber of the cavity to the narrowed portion with a predetermined molten metal and then injecting a molten metal of another composition into the upper chamber, the molten metal of another composition is formed by the function of the narrowed portion. It becomes difficult to enter the lower chamber, and a mixed layer of both molten metals is formed near the boundary between the narrowed portion and the upper chamber. That is, the molten metal hardly mixes in the lower chamber of the cavity due to the function of the throttle portion. Therefore, even if the lower chamber of the cavity is sufficiently smaller than the upper chamber, a predetermined molten metal can be held in the lower chamber. Also,
Even if the room below the cavity is filled with the molten metal having a low specific gravity, the function of the narrowing portion can prevent the rising of the molten metal to some extent. That is, it becomes possible to mold a specific range of a casting with a metal having a desired composition.

[0007] The above-mentioned problem is solved by a casting method according to the present invention. According to the present invention, since the cavity is formed by the vanishing model, when the molten metal is injected into the cavity, the vanishing model becomes a resistance and the flow speed of the molten metal becomes slow. For this reason, when pouring a molten metal of another composition into the upper room, it becomes more difficult for the molten metal of the other composition and the predetermined molten metal previously poured to be further mixed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A casting method according to one embodiment of the present invention will be described below with reference to FIGS. In the present embodiment, the present invention is utilized when manufacturing a press die in a full molding method using a disappearing model, and FIG. 1 is a longitudinal sectional view of a main part of a sand mold 10 used in the present embodiment. FIG. 2 shows a vertical sectional view of the press die W. As shown in FIG.

The sand mold 10 is manufactured in the following procedure. First, a vanishing model 20 having the same shape as the press die W is manufactured using a vanishing material such as styrene foam. In addition,
The vanishing model 20 functions to form the cavity 14 in the sand mold 10. Here, as shown in FIG. 2, the press die W is provided with a cutting edge Ws for cutting a plate-shaped work at an upper edge of the die main body Wm. A relatively thin narrowed portion Wf is formed between the narrowed portion Wf and the portion Ws. The cutting edge portion Ws and the drawn portion Wf are formed of hard spheroidal graphite cast iron that can be hardened, and the main part of the mold body Wm is formed of gray cast iron that is easy to cut. The mold body Wm near the drawn portion wf is a mixed layer of spheroidal graphite cast iron and gray cast iron.

The vanishing model 20 is provided with a cutting edge forming part 20s, a drawing forming part 20f and a main body forming part 20m like the press die W, and the vanishing model 20 is housed in the casting frame 12 in a state where it is turned upside down. Is done. A lower weir 21 made of a vanishing material is connected to the cutting edge forming part 20s of the vanishing model 20. The lower weir 21 is a cutting edge forming part 20 of the vanishing model 20.
s are arranged in a predetermined number in a well-balanced manner so that the molten metal can be uniformly injected from below into the lower chamber 14d of the cavity 14 formed by s. Further, each lower weir 21 is also connected from below to an FCD runner 22 made of a vanishing material.

An upper weir 23 made of a vanishing material is connected to the main body forming portion 20m of the vanishing model 20. The upper weir 23
Are arranged in a predetermined number in a well-balanced manner so that the molten metal can be evenly injected from above into the upper chamber 14u of the cavity 14 formed by the main body forming portion 20m of the disappearing model 20. Further, an FC runner 24 also made of a vanishing material is connected to each upper weir 23 from above.

In this manner, the upper and lower weirs 2 are attached to the vanishing model 20.
When the runners 22, 24 and the runners 22, 24 are set, a mold wash is applied to the disappearing model 20, etc. Then, after the mold wash is dried, the disappearing model 20 and the like are stored in the casting flask 12 and sand-filling is performed. Here, FCD runway 22
Is connected to an FCD gate 26 in the form of a pipe.
4 is also connected to an FC gate 27 in the form of a pipe. Note that sanding is performed while repeatedly applying vibration so that the sand around the disappearance model 20 and the like is evenly filled. In this way, the sand mold 10 is formed by the sand filling, and the portion of the disappearing model 20 becomes the cavity 14 for forming the product. The draw forming part 20 of the disappearing model 20
The upper chamber 14u and the lower chamber 14 of the cavity 14 depend on f.
A narrowed portion 14f is formed between the aperture portion d.

When the sand mold 10 is formed, a first weir 31 is set on the FCD gate 26 of the sand mold 10.
Further, a second weir 33 is set on the FC gate 27 of the sand mold 10. The first weir 31 is a container that stores the FCD melt that is the material of the cutting edge Ws of the press die W and injects the melt into the sand mold 10, and includes a first stopper 32 that opens and closes the FCD gate 26. . The second weir 33 is a container that stores the molten FC that is the material of the die body Wm of the press die W and injects the molten molten metal into the sand mold 10.
7 is provided with a second stopper 34 for opening and closing.

When the first weir 31 and the second weir 33 are set on the sand mold 10, the FCD melt is supplied to the first weir 31 and the FC melt is supplied to the second weir 33 to wait for casting. become. The FCD melt is a spheroidal graphite cast iron melt, and its component is T.M. C3.0-4.0%, Si1.5-2.0
%, Mn 0.5-1.0%, Ni 0.2-0.5%, Cu 0.4-0.6
%, Mo 0.2 to 0.5%, and Mg 0.01 to 0.05%. Also,
FC melt is a gray cast iron melt, and its component is T.M. C
3.0%, Si 1.6% and Mn 0.8%. The weight of the melt is about 0.2 g / cm ³ heavier in the FC melt than in the FCD melt.

When the FCD molten metal and the FC molten metal are supplied to the first weir 31 and the second weir 33, respectively, and the preparation for casting is completed, the first stopper 32 of the first weir 31 is opened and a slightly lighter FCD melt is produced. It is poured into the sand mold 10 from the FCD gate 26. The FCD melt injected from the FCD gate 26 melts the FCD runner 22 and the lower weir 21 made of the vanishing material, and is guided to the cavity 14 formed by the vanishing model 20. Then, the FCD molten metal guided to the cavity 14 melts the disappearance model 20 from below, and
Rises in the lower room 14d. In this way, as shown in FIG.
When it exceeds 4f, the first stopper 32 is closed.

Next, the second stopper 34 of the second weir 33
Is opened, and the FC melt is injected into the sand mold 10 from the FC gate 27. The molten FC injected from the FC gate 27 melts the FC runner 24 and the upper weir 23 made of the vanishing material, and the vanishing model 2
0 is guided by the cavity 14 formed. Then, the molten FC introduced into the cavity 14 melts the disappearance model 20 from the upper side while the upper room 1 of the cavity 14 is melted.
4u. At this time, the FC melt disappears
Since zero is melted and supplied to the cavity 14, the vanishing model 20 becomes a resistance, and the flow rate of the FC melt becomes small.

Further, the upper chamber 14 of the cavity 14
Since there is a throttle 14f between u and the lower room 14d,
Even if the molten FC is injected into the upper chamber 14u, its narrowed portion 14f
Makes it difficult for the molten FC to enter the lower room 14d. In addition, the FCD molten metal in the lower room 14d having a small specific gravity is hardly lifted by the function of the narrowed portion 14f. Therefore, a mixed layer of the molten FC and the molten FCD is formed near the boundary between the narrowed portion 14f and the upper chamber 14d. That is, due to the function of the throttle portion 14f, the two molten metals hardly mix in the lower chamber 14d of the cavity 14. Also,
As described above, since the flow rate of the FC melt becomes smaller,
The mixed layer of the melt and the FCD melt is also relatively thin.

When a predetermined amount of the molten FC is poured into the sand mold 10 as described above, the cavity 14 is filled with the molten cast iron, and the molten cast iron is formed from above with a layer of the molten FC and the molten FC and the molten FCD. It is divided into three layers: a mixed layer and a layer of molten FCD. When the injection of the molten metal is completed and the molten metal in the sand mold 10 solidifies, the sand mold 10 is dismantled and the press die casting inside is taken out. As described above, the molten cast iron in the cavity 14 is a layer of the molten FC, a mixed layer of the molten FC and the molten FCD,
Since the FCD molten metal is divided into three layers, the press die casting is also composed of three layers of a gray cast iron layer, a mixed layer of gray cast iron and spheroidal graphite cast iron, and a spheroidal graphite cast iron layer from above.

Here, in the casting method according to the present embodiment, the vanishing model 20 is turned upside down to form the cutting edge forming portion 20s.
Is disposed on the lower side and the main body forming portion 20m is disposed on the upper side, so that burnt debris of the vanishing model 20 floats on the side of the main body forming portion 20m. For this reason, casting defects are less likely to occur in the cutting edge portion Ws of the press die W that requires strength. After removing the sand, the surface of the press die casting thus cast is cut to finish the press die W.

As described above, according to the casting method according to the present embodiment, the upper chamber 14u and the lower chamber 14d of the cavity 14 are provided.
Between the lower chamber 14d of the cavity 14 and the narrower portion 14f with the FCD molten metal, and then inject the molten FC into the upper chamber 14u, so that the narrower portion 14f and the upper chamber 14d are formed. A mixed layer of the FC molten metal and the FCD molten metal is formed in the vicinity of the boundary between the two and the molten metal is hardly mixed in the lower room 14d. For this reason, even if the lower room 14d of the cavity 14 is sufficiently smaller than the upper room 14u, the FCD molten metal can be held in the lower room 14d. That is, it becomes possible to mold a specific range of a casting with a metal having a desired composition.

In the casting method according to the present embodiment, an example is shown in which the FCD molten metal having a small specific gravity is injected into the lower chamber 14d of the cavity 14, and the FC molten metal having a relatively large specific gravity is injected into the upper chamber 14u. Naturally, it is also possible to inject a predetermined molten metal having a large specific gravity into the lower room 14d and to inject a molten metal having another specific composition having a small specific gravity into the upper room 14u. Further, in the casting method according to the present embodiment, an example in which the press die W is cast has been described, but an object other than the press die can be cast.

[0022]

According to the present invention, the molten metal is hardly mixed in the room located below the narrowed portion of the cavity, so that a specific range of the cast product can be formed with a metal having a desired composition. And the application range of the cast product is widened.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a main part of a sand mold used in a casting method according to one embodiment of the present invention.

FIG. 2 is a vertical sectional view of a mold formed by a casting method according to one embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing an intermediate step of a casting method according to one embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a mold used in a conventional casting method.

[Explanation of symbols]

 W Press mold 10 Sand mold (mold) 12 Cast frame (mold) 14 Cavity 14u Upper room (upper room) 14d Lower room (lower room) 14f Restriction unit 20 Elimination model 22 FCD runner 24 FC runner 26 FCD Gate 27 FC Gate

Claims (2)

[Claims] 1. A casting method for injecting molten metals having different compositions into separate cavities from separate runners of a mold, comprising: a lower chamber, an upper chamber, and a cavity having a constricted portion between the two chambers. A casting method characterized by forming and filling a predetermined molten metal from the lower chamber to the narrowed portion in the cavity, and then injecting a molten metal of another composition into the upper chamber. 2. The casting method according to claim 1, wherein the cavity is formed using a vanishing model.