JP7210014B2 - casting method - Google Patents

Description

The present invention relates to a casting method using a fugitive pattern that generates combustible gas when heated.

A casting method using an extinguishable pattern that generates combustible gas when heated is disclosed, for example, in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 62-214848).
FIG. 8 shows a casting apparatus 10 shown in Patent Document 1. As shown in FIG.
Numeral 11 denotes a flask, and 12 denotes a cylindrical vent portion erected from the bottom to the top in the flask 11, and has a large number of vent ports 13 on the outer periphery. Reference numeral 14 denotes an extinguishable model made of foamed synthetic resin such as polystyrene foam, and 15 denotes a nonflammable filler such as sand. The erasable model 14 is placed in a state of being buried in the filling 15 . Reference numeral 16 denotes a runner having a sprue 17 at its upper portion, which is provided in contact with the erasable model 14 .

Molten metal is injected through runners 16 .
The molten metal heats the fugitive pattern 14, gasifies it, replaces the fugitive pattern 14, and is cast as a casting of a desired shape.
The gasified combustible gas 18 travels through the filling 15, enters the vent section 12 from the vent port 13, rises in the cylindrical vent section 12 as a thermal upward flow, and is exhausted. Then, it is ignited by the ignition device 19 and burned outside the vent section 12 . The gasified combustible gas is continuously sucked into the vent section 12 through the filling 15 by the suction force that rises as a thermal ascending air current in the vent section 12, burns efficiently, is rendered harmless, and is discharged. be.

JP-A-62-214848

The casting method using the evanescent pattern has the advantage that the casting mold can be easily manufactured and the casting can be performed at a low cost as compared with the shell mold method and the like.
However, when casting a plurality of castings in one flask, a plurality of fugitive patterns are placed in the flask, and a plurality of air vents are provided in the flask as appropriate. Casting is performed by arranging them, but a problem arises in that the dimensions, particularly the weight, of the obtained cast products vary.

The present invention has been made to solve the above problems, and its object is to provide a casting method capable of obtaining castings with little variation in weight even when casting a plurality of castings. is to provide

In order to achieve the above objects, the present invention has the following configurations.
That is, the casting method according to the present invention includes a container-shaped flask, and a plurality of vents which are arranged in the flask at required intervals in the circumferential direction and have vent openings at required height positions. A casting method using a casting apparatus equipped with an air section, wherein a plurality of fugitive patterns that generate combustible gas when heated are placed in the flask at required intervals in the vent section. a step of arranging the air vent at a position higher than a height position of at least the lower half of the dissipative model; a step of filling a nonflammable filler to a position higher than the air vent of the air vent, and a runner having a sprue and communicating with the extinguishable model to the part of the extinguishable model. a step of pouring molten metal, gasifying the fugitive pattern, and replacing the fugitive pattern with the molten metal; and a step of igniting and burning the combustible gas, wherein the vent opening is opened at a plurality of locations in the vertical direction in the vent portion, and the incombustible filling is filled in the flask. At that time, the nonflammable filling is also placed in the vent part to a position where the vent hole, among the plurality of vent holes, is located at a position lower than the height of at least the lower half of the extinguishable model. It is characterized by filling.

Further, the casting method according to the present invention includes a container-shaped flask, and a plurality of air vents arranged in the flask at required intervals in the circumferential direction and having vent openings at required height positions. A casting method using a casting apparatus equipped with a section, wherein a plurality of fugitive patterns that generate combustible gas when heated are placed in the flask at a required interval in the circumferential direction, in the vent section. a step of arranging an air vent at a position higher than a height position of at least the lower half of the extinguishable model; a step of filling a nonflammable filling to a position higher than the air vent of the air vent, and a runner having a sprue and communicating with the extinguishable model to melt into the part of the extinguishable model. a step of pouring in a metal, gasifying the fugitive pattern, and replacing the fugitive pattern with the molten metal; a step of igniting and burning combustible gas, wherein the fugitive pattern is placed in the flask so that the entire fugitive pattern is at a position lower than the vent of the vent section. , and the vent opening is opened at a plurality of locations in the vertical direction in the vent portion, and when the incombustible filling is filled in the flask, the incombustible filling is placed in a plurality of The air vent is also filled up to a position where the air vent located at a position lower than the height of the entire dissipative model is blocked.

According to the present invention, when a plurality of extinguishable patterns are used, the movement path of the combustible gas between the vent of the vent section and each extinguishable pattern can be lengthened to reduce the difference. It is possible to reduce the time difference between the molten metal flowing into the part of the fugitive pattern and eliminate the difference in casting conditions, so that a cast product with little difference in weight can be obtained.

FIG. 1A is a plan view of a casting apparatus. FIG. 1B is a cross-sectional view of the casting apparatus. FIG. 2A is a plan view from a direction different from that of FIG. 1A. FIG. 2B is a cross-sectional view along line XX in FIG. 1A. FIG. 3A is a plan view of a casting apparatus based on conventional principles. FIG. 3B is a cross-sectional view thereof. FIG. 4A is a weight distribution map of castings obtained by a conventional method. FIG. 4B is a distribution chart of the weight of castings obtained by the method of the example. FIG. 5A is a plan view showing an example in which the vent section is filled with a filler. FIG. 5B is a cross-sectional view thereof. FIG. 6A is a plan view of still another example in which the vent section is filled with a filler. FIG. 6B is a cross-sectional view thereof. FIG. 7A is an explanatory diagram of a state in which the movable barrel is extended downward. FIG. 7B is an explanatory diagram showing a state in which the movable barrel is moved into the fixed barrel. It is an explanatory cross-sectional view of a conventional casting apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a casting apparatus 20 according to this embodiment. FIG. 1A is its plan view, and FIG. 1B is its cross-sectional view. 2A is a plan view seen from a different direction from FIG. 1, and FIG. 2B is a cross-sectional view in the X direction in FIG. 1A.
1 and 2 show a casting apparatus 20 for casting a plurality of (12) castings.

Reference numeral 22 denotes a container-shaped flask, and 24 denotes a cylindrical vent. The vent section 24 has vent holes 25 at a plurality of locations positioned in the vertical direction. The vent section 24 is arranged in the center of each side of the rectangular flask 22 in plan view, in close proximity to the inner wall of each side.
In this embodiment, the vent section 24 is provided so as to extend from the upper portion of the flask 22 to the middle portion of the flask 22 . The vent section 24 is supported on the flask 22 by a support section (not shown).
Although the configuration of the air vent 24 having the air vent 25 is not particularly limited, in the present embodiment, a plurality of ring-shaped members are vertically connected with a connecting member at predetermined intervals. It is Alternatively, the air vent 24 may be a simple pipe provided with a large number of through holes that serve as air vents.
The air vent 25 is formed in a size that does not allow passage of incombustible granular filler such as sand.

A runner 26 has a sprue 27 at the top and is arranged in the center of the flask 22 in the vertical direction. The runner 26 may be formed by a shell mold method, or may be formed by a fugitive material such as polystyrene foam.
A coating 28 that serves as a protective layer is formed on the inner wall of the runner 26 by a known technique.

An erasable model 30 made of foamed synthetic resin such as foamed polystyrene is placed in the flask 22 .
The extinguishable pattern 30 is placed on a nonflammable filling 32 such as sand filled in the bottom of the flask 22 . At that time, as shown in FIGS. 1 and 2 , the entire dissipative model 30 is positioned lower than the lowermost vent 25 of the vent section 24 . The dissipative model 30 is connected to the lower part of the runner 26 via its hot water pool portion 33 and connection portion 34 . A coating (not shown) serving as a protective layer is formed on the entire outer surface of the fugitive model 30 including the hot water pool 33 and the connecting portion 34 .

As shown in FIGS. 1A and 2A, the vanishing model 30 is formed into four blocks each having three model parts. That is, each block is composed of three models and one hot water reservoir 33 and one connection 34 connecting them. Each block is placed in the flask 22 so as to be positioned between the two vents 24 .

After placing the fugitive pattern 30 in the flask 22 as described above, the filler 32 is filled in the flask 22 so as to cover the fugitive pattern 30 and to be in contact with the outer peripheral surface of the vent section 24. . At that time, the filling material 32 is filled in the flask 22 to a position higher than the uppermost air vent 25 of the air vent 24 .
After setting the fugitive pattern 30 in the flask 22 as described above, molten metal is poured from the sprue 27 through the runner 26 into the fugitive pattern 30 .

By injecting the molten metal, the fugitive pattern 30 is thermally decomposed and gasified. The combustible gas gasified in this manner moves through the granular filler 32 and enters the cylindrical vent portion 24 through the vent port 25 . The combustible gas that has entered the vent section 24 rises in the vent section 24 due to the heat rise. Since the combustible gas rises in the venting part 24 due to the heat rise, the inside of the venting part 24 becomes negative pressure, a suction force is generated, and the combustible gas in the filling 32 is vented more and more due to the chimney effect. It will be sucked into the section 24 and heat up in the vent section 24 .
By igniting the combustible gas with an ignition device at the outlet of the vent section 24, the combustible gas is burned, rendered harmless, and discharged into the atmosphere.
Casting is thus completed.

In the present embodiment, as described above, the dissipative model 30 is buried in the filler 32 so as to be below the air vent 24 (specifically, the air vent 25).
By adopting the above-described configuration, in the present embodiment, even if casting is performed simultaneously in the same flask using a plurality of fugitive patterns, it is possible to reduce variations in the weight of the obtained castings. It has the effect of
The reason for this will be explained below.

1. Causes of Defects in Conventional Method A description will be given of a case in which casting is performed by a casting apparatus based on a conventional principle using the 12-cavity vanishable model 30 described in the present embodiment.
FIG. 3 shows a casting apparatus 20 according to conventional casting principles.
In this conventional casting apparatus 20, the vent section 24 is formed in a cylindrical shape extending from the top to the bottom of the flask 22, and the vent port 25 is used to efficiently suck the combustible gas from the fugitive model 30. , are provided at many locations over a wide range from the bottom to the top of the vent section 24 .
In the case of the conventional method using this conventional device, the erasable model 30 is placed at the same height position as the air vent 25 of the air vent 24 . Therefore, a large number of air vents 25 correspond to the entire side of the extinguishable model 30 .

In the case of this conventional device, as is clear from FIG. In 30c, the movement path of the combustible gas generated from the model 30a and the model 30c adjacent to the vent section 24 to the vent section 24 is short, and the combustible gas generated from the model 30b located in the center far from the vent section 24 is short. The path of movement of the gas to the vent section 24 becomes longer.

The inventors have found that different distances traveled in the combustible gas charge will result in different weight castings.
That is, when the movement path is short, the time it takes for the combustible gas to reach the vent section 24 is shortened, and the combustible gas is sucked that much faster. On the other hand, when the movement path becomes long, the suction of the combustible gas becomes slow.

If the combustible gas is sucked in quickly, the part of the fugitive pattern 30 quickly becomes negative pressure, and the molten metal is likely to flow in at a correspondingly higher pressure, the space swells, and the amount of injected molten metal increases.
On the other hand, if the suction of the combustible gas is delayed, the flow of the molten metal to the part of the fugitive pattern 30 is delayed, and the amount of injected molten metal tends to decrease.
As a result, the weight and dimensions of the castings tend to vary.

2. Principles of the present embodiment In the present embodiment, as described above, the dissipative model 30 is buried in the filling 32 so as to be below the air vent 24 (specifically, the air vent 25). are placed as follows.
As a result, in the present embodiment, the movement path of the combustible gas generated from the models 30a and 30c to the vent section 24 is longer than in the conventional case shown in FIG. Similarly, the movement path of the combustible gas generated from the model 30b located in the center to the vent section 24 is also longer than in the conventional case.

As a result, the difference between the time and pressure at which the molten metal flows into the models 30a and 30c and the time and pressure at which the molten metal flows into the model 30b is reduced, and variations in casting conditions are reduced. Reduced weight variation.
FIG. 4 shows a case where exactly the same fugitive model 30 is used and cast using the casting apparatus 20 of the present embodiment shown in FIG. FIG. 4A shows the weight distribution of the obtained cast product when casting (FIG. 4A: conventional example).
As shown in FIG. 4, the average weight of the obtained castings was almost the same, but the castings of the example were lighter in weight and the weight was cut off from the heavy side, resulting in a casting with less variation in weight. . The variation in the weight of the cast product is greater in the conventional example.

FIG. 5 shows another embodiment for carrying out the method of the invention.
In this embodiment, the conventional casting apparatus 20 shown in FIG. 3 can be used as it is.
In the present embodiment, when the incombustible filling 32 is filled into the flask 22 , among the plurality of air vents 25 in the air vent 24 , the air vents 25 are positioned lower than the height of the entire fugitive model 30 . The nonflammable filler 32 is also filled in the vent section 24 up to the position where the air port 25 is blocked (the shaded area in FIG. 5).
In addition, when filling the filler 32 in the vent section 24, after filling the filler 32 to a predetermined height, the upper part of the vent section 24 is closed with a lid (not shown), and then the flask is A filling 32 may be provided in 22 .
In this embodiment, the only air vents 25 that actually function are the air vents 25 located above the dissipative model 30, so that the same effects as in the above embodiment are obtained.

FIG. 6 shows yet another embodiment for implementing the method of the invention.
When filling the vent portion 24 with the filler 32, as described above, it is optimal for the vent port 25 to function only above the dissipative model 30. FIG.
However, depending on the shape and size of the fugitive model 30, as shown in FIG. The inside of the vent section 24 may also be filled up to the position (the shaded area in FIG. 6) that closes the vent port 25 at the bottom. That is, the air vent 25 on the upper side of the dissipative model 30 may be open.
Even in this case, the movement path of the combustible gas can be lengthened, so that variations in the weight of the casting can be reduced.

FIG. 7 is an explanatory diagram showing another embodiment of the vent section 24. As shown in FIG.
In the present embodiment, the vent portion 24 is composed of a fixed cylinder 24a fixed to the flask 22 by a support portion (not shown) and a movable cylinder 24b having an vent port 25. The movable cylinder 24b is It is provided so that it can move back and forth inside. Further, the movable barrel 24b can be fixed to the fixed barrel 24a by a screw 24c at an arbitrary moving position of the movable barrel 24b.
With the above configuration, the movable cylinder 24b can be adjusted so as to be positioned above the dissipative model 30 to be placed as shown in FIG. Alternatively, the movable cylinder 24b can be lowered to a position corresponding to the position of the upper half of the dissipative model 30 to be used, for example.

In each of the above-described embodiments, the case of using the 12-piece erasable model 30 has been described. be.

20 casting device 22 flask 24 vent 24a fixed cylinder 24b movable cylinder 24c screw 25 vent 26 runner 27 gate 28 coating mold 30 vanishing model 30a model 30b model 30c model 32 filler 33 hot water reservoir 34 connecting part 36 ignition device

Claims (2)

Casting using a casting apparatus comprising a container-shaped flask and a plurality of air vents arranged in the flask at required intervals in the circumferential direction and having air vents opened at required height positions a method,
In the flask, a plurality of fugitive patterns that generate combustible gas when heated are placed at required intervals in the circumferential direction, and the vent of the vent part is located at least in the lower half of the fugitive pattern. A step of arranging so as to be higher than the height position;
a step of filling the mold with a nonflammable filler covering the fugitive pattern and in contact with the air vent to a position higher than the air vent of the air vent;
Molten metal is poured into a portion of the fugitive pattern through a runner having a sprue and communicating with the fugitive pattern, gasifying the fugitive pattern, and replacing the fugitive pattern with the molten metal. process and
a step of igniting and burning a combustible gas that gasifies and enters from the vent port and rises in the vent portion due to a thermal ascending airflow ;
The vent openings are opened at a plurality of positions in the vertical direction in the vent section,
When filling the incombustible filling into the flask, the incombustible filling is placed in the vent at a position lower than the height of at least the lower half of the fugitive pattern among the plurality of vent holes. A casting method, characterized in that the inside of the vent section is also filled up to a position where the vent is closed. Casting using a casting apparatus comprising a container-shaped flask and a plurality of air vents arranged in the flask at required intervals in the circumferential direction and having air vents opened at required height positions a method,
In the flask, a plurality of fugitive patterns that generate combustible gas when heated are placed at required intervals in the circumferential direction, and the vent of the vent part is located at least in the lower half of the fugitive pattern. A step of arranging so as to be higher than the height position;
a step of filling the mold with a nonflammable filler covering the fugitive pattern and in contact with the air vent to a position higher than the air vent of the air vent;
Molten metal is poured into a portion of the fugitive pattern through a runner having a sprue and communicating with the fugitive pattern, gasifying the fugitive pattern, and replacing the fugitive pattern with the molten metal. process and
a step of igniting and burning a combustible gas that gasifies and enters from the vent port and rises in the vent portion due to a thermal ascending airflow;
The dissipative pattern is placed in the flask so that the entire dissipative pattern is positioned lower than the vent of the vent section,
The vent openings are opened at a plurality of positions in the vertical direction in the vent section,
When filling the incombustible filling into the flask, the incombustible filling is placed in the vent hole at a position lower than the height of the entire fugitive pattern among the plurality of vent holes. A casting method characterized in that the inside of the air vent is also filled up to a closed position.

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