JP3070693B2 - Manufacturing method of core made of low melting point alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a core made of a low melting point alloy, and more particularly to, for example, molding an intake pipe through which air for feeding into an automobile engine is formed with synthetic resin. And a method for producing a core made of a low melting point alloy.

[0002]

2. Description of the Related Art Air to be supplied to an automobile engine is taken from an air cleaner, passes through a duct and an intake pipe, and is supplied with gasoline supplied by a fuel injection device or a carburetor provided at a downstream end of the intake pipe. After being mixed, it passes through an intake manifold and is fed into a cylinder of an automobile engine.

Conventionally, the intake pipe has been made by die-casting of an aluminum alloy. However, in order to reduce the weight of automobiles in recent years, for example, Japanese Patent Application Laid-Open No. 58-82059.
As disclosed in Japanese Unexamined Patent Publication, the production by injection molding of a synthetic resin has been proposed. On the other hand, since the intake pipe is hollow and the outer surface shape and the inner surface shape are bent in a three-dimensional direction, it cannot be manufactured by an injection molding apparatus having a simple split mold as generally used. Therefore, when an intake pipe having a shape bent in a three-dimensional direction is manufactured by injection molding of a synthetic resin, it is performed as follows.

First, prior to injection molding, a hollow core made of a low melting point alloy (for example, having a melting point of 130 ° C. to 150 ° C.) such as an alloy of Bi and Sn or an alloy of Bi, Sn and Pb is used. prepare. The outer surface shape of the core matches the inner surface shape of the synthetic resin intake pipe to be manufactured. As a method of manufacturing the core, for example, there is a method shown in FIGS.

First, a sand mold 1 for a core bent in a three-dimensional direction.
And two sand molds 3 and 5 for the outer mold are made in accordance with a conventional method. Next, after the three-dimensional core sand mold 1 is placed in the two outer mold sand molds 3 and 5, both ends of the core sand mold 1 are fixed.
Then, the melted low melting point alloy is injected into a gap (cavity) 7 between the wall surfaces 4, 6 of the two outer mold sand molds 3, 5 and the wall surface 2 of the three-dimensional core sand mold 1, A low melting point alloy layer 8 is formed around the wall 2 of the three-dimensional core sand mold 1.

Thereafter, the sand molds 1, 3, and 5 are broken, and the hollow core is taken out. Next, in a state where the hollow core thus formed is disposed in a mold having an inner surface shape that matches the outer surface shape of the intake pipe to be formed, the inside of this mold is lower than the low melting point alloy. Synthetic resin having a high melting point, for example, nylon 66 containing glass fiber (for example, having a melting point of 240 ° C.)
Above) and solidified in the gap (cavity) between the inner surface of the mold and the outer surface of the core. Although the temperature of the molten synthetic resin injected into the cavity is higher than the melting point of the low melting point alloy constituting the core, the temperature is immediately increased by contacting the core with a large heat capacity and good heat transfer. Since the core is lowered, a part of the core does not melt with the injection of the molten synthetic resin.

After the synthetic resin in the mold has solidified, the mold is opened and the intake pipe is taken out. Since the intake pipe is bent in a three-dimensional direction, the core is built in the intake pipe. It is in the state of being left. Therefore, in order to take out the core, the synthetic resin and the core taken out of the molding die are subjected to a temperature T higher than the melting point of the low melting point alloy and lower than the melting point of the synthetic resin (for example, 150 ° C <T <240 ° C). ) To melt the core made of a low melting point alloy and remove the synthetic resin intake pipe from the inside.

As a result, an intake pipe made of synthetic resin whose outer surface shape matches the inner surface shape of the mold and whose inner surface shape matches the outer surface shape of the core is obtained.

[0009]

However, the low melting point alloy forming the core in the above-mentioned conventional method is, for example, Bi57.
Since the specific gravity is larger than the specific gravity of the core sand mold 1 such as -Sn43 (specific gravity: 8.56), the core shown in FIG. 9 cannot be formed. That is, there were the following problems in the manufacturing process.

That is, as shown in FIG. 10, when the molten low melting point alloy is cast into the gap (cavity) 7, the specific gravity of the low melting point alloy is larger than the specific gravity of the core sand mold 1, and therefore, as shown by arrows. Flows into the lower side of the three-dimensional core sand mold 1 and the core sand mold 1 is lifted up as shown by the arrow. As a result, the formed low melting point alloy layer 8 has an uneven thickness shape in which the upper part is thin and the lower part is thick.

As described above, when the intake pipe is formed using the uneven core, the product follows the core. For this reason, pressure resistance and heat resistance are poor, which is not preferable. In addition, large uneven thickness can not be used as a product,
There was a problem that the yield was poor and the productivity was lacking. The present invention has been made to solve such a conventional problem, and an object thereof is to provide a method of manufacturing a low-melting-point alloy core that can prevent uneven thickness of a low-melting-point alloy layer. It is in.

[0012]

A method of manufacturing a core made of a low melting point alloy according to the present invention comprises disposing a three-dimensionally shaped core sand mold in a plurality of outer mold sand molds, and simultaneously forming a three-dimensional core sand mold. Low melting between the wall of the mold sand mold and the upper side of the three-dimensional core sand mold wall
After fixing via an independent spacing adjuster made of a metal material having a melting point higher than that of the point alloy , a plurality of outer mold sand mold walls and the periphery of the three-dimensional core sand mold are fixed. into the gap between, injecting a low melting point alloy dissolved, uniformly low melting point alloy layer of thickness in the walls around the core sand-type three-dimensional shape, the inside this
It is formed in a state in which the spacing adjuster is embedded .

[0013]

In the present invention, first, a three-dimensional core sand mold is placed on the outer mold sand mold serving as the lower mold. The upper part of the original core sand mold is made of a metal material with a higher melting point than the low melting point alloy.
The melted low melting point alloy was injected into the gap (cavity) between the outer mold sand mold wall surface and the three-dimensional core sand mold wall surface, and then fixed. The gap is adjusted by the gap adjuster to prevent the three-dimensional core sand mold from rising upward with the molten low melting point alloy cast into the gap (cavity). (Cavity), and a low-melting alloy layer with a uniform thickness around the wall of the three-dimensional core sand mold .
The space adjuster is formed in this state in a buried state .

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show a case where an example of a method of manufacturing a core made of a low melting point alloy is applied to an intake pipe. First, the core sand mold 20 and the two outer mold sand molds 30 and 32 that are bent in the three-dimensional direction are formed in a conventional manner.

Here, the core sand mold 20 bent in the three-dimensional direction is formed so that the outer surface shape matches the inner surface shape of the intake pipe, as in the conventional sand mold for the core, and the upper side thereof. A plurality of interval adjusters 40 made of aluminum keren are attached to the wall surface 21 of the first embodiment. The spacing adjuster 40 made of aluminum kelen is, for example, shown in FIG.
As shown in FIG. 5 to FIG. 5, a disk 42 is fixed to both ends of a rod 41 in a parallel and vertical manner so that the rod 41 is located at the center of the disk 42. Incidentally, here, a rod 41 having a diameter of 2 mm, a height of 5 mm, and a disk 42 having a diameter of 10 mm was used.

The outer mold dies 30 and 32 have, in the same manner as the conventional outer molds, molding surfaces formed on the wall surfaces 31 and 33 so as to conform to the outer shape of the intake pipe. In addition, sand mold for outer mold 3
At 0 and 32, notches are formed to protrude both ends 22, 23 of the core sand mold 20. Next, the three-dimensional core sand mold 20 to which a plurality of interval adjusters 40 are attached on the upper side is placed on the outer mold sand mold 30 which is a lower mold.

Then, an outer mold sand mold 32 serving as an upper mold is attached from above. Then, sand molds 30, 32 for both outer molds
Ends 22 of the core sand mold 20 protruding from the notch
23 is fixed. Thus, between the wall surface 21 of the core sand mold 20 and the wall surfaces 31 and 33 of both outer mold sand molds 30 and 32,
A gap (cavity) 50 is formed.

Thereafter, the molten low melting point alloy (Bi57-Sn) was poured through a gate provided in one of the outer mold sand molds 30, 32.
43) Inject 51. At this time, a gap (cavity) 5
Since the molten low-melting point alloy cast in 0 has a higher specific gravity than the core sand mold 20, it flows in from below the three-dimensional core sand mold 20 and moves the three-dimensional core sand mold 20 upward. Try to make them rise. However, between the three-dimensional core sand mold 20 and the wall 31 of the outer sand mold 30 which is the upper mold, a metal material having a melting point higher than that of the low melting point alloy is used.
Since the standing space adjuster 40 is fixed, buoyancy applied to the three-dimensional core sand mold 20 is prevented, and the three-dimensional core sand mold 20 is held at a predetermined position in the gap (cavity) 50. can do.

Therefore, when the molten low melting point alloy cast in the gap (cavity) 50 is solidified, the low melting point alloy layer 52 having a uniform thickness is formed around the wall surface 21 of the three-dimensional core sand mold 20. However , a plurality of space adjusters 40 are embedded in this.
It is formed in the state where it was. Then, sand molds 30, 32 for both outer molds
And the low-melting-point alloy layer 5 having a uniform thickness around the wall 21.
Take out the three-dimensional core sand mold 20 on which 2 is formed. Then, the three-dimensional core sand mold 20 can be broken to obtain a hollow core.

As described above, according to the present embodiment, the three-dimensional core sand mold 20 is provided in the two outer mold sand molds 30 and 32.
And the upper surface of the wall surface 31 of the sand mold for outer mold 30 on the upper side and the upper surface of the wall surface 21 of the sand mold for core core 20 in the three-dimensional shape are lowered.
After fixing via an independent spacing adjuster 40 made of a metal material having a melting point higher than that of the melting point alloy, the walls 31 and 33 of the plurality of sand dies 30 and 32 and the three-dimensional core are formed. The melted low melting point alloy is injected into the gap 50 between the wall surface 21 of the sand mold 20 and the wall surface 21 of the three-dimensional core sand mold 20.
A plurality of low-melting alloy layers 52 of uniform thickness around the
Since the spacers 40 are formed in a state where they are buried, a core having a uniform thickness is obtained, and the moldability is improved.
By freely controlling the size of the spacing adjuster 40, there is an advantage that a product of an arbitrary thickness can be manufactured.

In the present invention, the spacing adjuster 40 includes:
In the above embodiment, aluminum-made kelen was used. However, as long as the melting point is 140 ° C. or more, not only aluminum but also iron-based, copper-based, and non-ferrous-based (for example, bismuth,
Tin) metals or alloys thereof are preferred.

Further, in the case where the iron-based spacing adjuster 40 is used in a buried state, after the injection molding, when the low-melting alloy core is melted in the air, oil, high frequency, or the like, The temperature of the interval adjuster 40 made of iron or the like rises faster than that of the core made of the low melting point alloy, and the heat causes the low melting point alloy to elute in a short time. Also, an interval adjuster 40 having a melting point of 140 ° C. or more, such as an iron-based material.
Can be reused because it does not melt and does not change the composition of the low melting point alloy. .

FIGS. 6 and 7 show a modification of the spacing adjuster 40. FIG. 6 shows a box having a cross section of 10 mm in length and width and 5 mm in height, and FIG. A 10 mm corrugated plate is shown. In the above embodiment, the case where the spacing adjuster 40 is fixed to the core sand mold 20 has been described, but the spacing adjuster 40 is fixed to the wall surface 31 of the outer mold sand mold 30.
May be fixed. Although the intake pipe has been described as a three-dimensional synthetic resin product, the present invention is not limited to this.
The present invention can be applied to any object having a three-dimensional bending that cannot be simply formed by ordinary injection molding.

[0024]

As described above, according to the present invention, when manufacturing a core made of a low melting point alloy which is bent in three dimensions,
Between the sand mold for core and the sand mold for outer mold .
By inserting an independent spacing adjuster made of a high metal material, the low melting point alloy cast into the gap (cavity) flows below the core sand mold and tries to lift the core sand mold. And a uniform low-melting alloy layer around the core sand mold, and a plurality of spacing adjusters embedded in it.
Since it can be formed in the installed state , the core sand mold
Eccentricity can be prevented, and a spacing adjuster is used when the core is melted.
It can be easily collected and reused .

Accordingly, a hollow core having a uniform thickness is obtained, and the productivity is improved. Further, a three-dimensional synthetic resin product having excellent pressure resistance and heat resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a method for manufacturing a core made of a low melting point alloy according to one embodiment of the present invention.

FIG. 2 is a sectional view showing a main part in FIG.

FIG. 3 is a perspective view of an interval adjuster used in FIG. 1;

FIG. 4 is a plan view of the spacing adjuster used in FIG.

FIG. 5 is a side view of the spacing adjuster used in FIG.

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

FIG. 7 is a perspective view showing a modified example of the spacing adjuster.

FIG. 8 is an explanatory view showing a method for manufacturing a conventional core made of a low melting point alloy.

FIG. 9 is a sectional view of a main part of a core made of a low melting point alloy assumed in FIG. 8;

FIG. 10 is a cross-sectional view of a main part showing the flow of a procedure amendment melting point alloy generated in FIG. 8;

[Explanation of symbols]

 Reference Signs List 20 three-dimensional core sand mold 21 wall surface 30, 32 sand mold for outer die 31, 33 wall surface 40 spacing adjuster 50 gap 52 low melting point alloy layer

Continuation of the front page (51) Int.Cl. ⁷ identification code FI // B29L 23:00 (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 33/00-33/76 B29C 45/00- 45/84

Claims (1)

(57) [Claims] 1. A plurality of outer mold sand molds (30, 32),
The three-dimensional core sand mold (20) is arranged, and the upper wall of the outer mold sand mold (30) and the upper wall of the three-dimensional core sand mold (20) are disposed. Low melting point
After fixing via an independent spacing adjuster (40) made of a metal material having a melting point higher than that of the alloy , a plurality of sand molds (30, 32) for the outer mold (30, 32) and the three-dimensional shape with the wall (31, 33). The melted low melting point alloy is injected into the gap (50) between the core sand mold (20) and the periphery thereof, and the wall thickness (21) of the three-dimensional core sand mold (20) is uniform around the wall (21). A low melting point alloy layer (52), and the spacing adjuster (40) embedded therein.
A method for producing a core made of a low-melting-point alloy, wherein the core is formed in a state where the core is formed.