JPH0289555A - Low pressure casting apparatus - Google Patents

Abstract

PURPOSE:To fill up clean molten metal in cavity and to obtain a high quality casting by arranging a molten metal holding chamber and a molten metal supplemental chamber in a die and communicating the molten metal holding chamber with the molten metal supplemental chamber through a filter. CONSTITUTION:The molten metal 34 is once supplied into the molten metal supplemental chamber 20 from a killing furnace 70 and sent into the molten metal holding chamber 18 through the filter 28. In the case oxide mixes in the molten metal 34, the oxide is intercepted with the filter 28 and does not flow into the molten metal holding chamber 18. By this method, casting failure including slag, etc., caused by filling up the molten metal containing the oxide is prevented and always the high quality casting can be formed. Further, after supplying the molten metal 34 from the killing furnace 70 into the molten metal supplemental chamber 20, a low pressure casting apparatus 10 can be immediately driven and the supplemental working time of the molten metal 34 is shortened and efficient casting can be executed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a low-pressure casting apparatus, and more particularly, a method for keeping the molten metal warm in order to press the molten metal into a cavity for a cast product defined in a mold. A molten metal holding chamber for storing molten metal and a molten metal replenishment chamber for replenishing the molten metal from the outside are provided, and each chamber is connected through a filter to prevent oxidation that is likely to be mixed in the molten metal supplied to the molten metal replenishment chamber. The present invention relates to a low-pressure casting apparatus that prevents objects from entering the molten metal holding chamber because they are blocked by the filter, thereby making it possible to obtain high-quality cast products without casting defects.

[Background of the Invention] In general, low-pressure casting machines are widely used when mass producing automobile parts made of cast products. The low-pressure casting machine includes, for example, a molten metal holding furnace that holds the molten metal under pressure, a mold that is placed on the molten metal holding furnace and defines a cavity and a sprue, and a mold that is placed on the molten metal holding furnace to form a cavity and a sprue from the molten metal holding furnace through the sprue. Contains a connecting thread.

Therefore, in this type of low-pressure casting machine, first, the inside of the molten metal holding furnace is pressurized to a predetermined pressure, and the pressurized molten metal rises in the stoke and fills the cavity through the sprue.

Next, after the pressurized state is maintained for a predetermined period of time so that the molten metal falls to a predetermined temperature, the pressurized state is released and the molds are separated to obtain a product.

In this case, a predetermined amount of molten metal is stored in the molten metal holding furnace, and as the above-described casting process is continued, the molten metal in the molten metal holding furnace decreases. For this reason, molten metal is usually replenished into the molten metal holding furnace from a calming furnace or the like, but in many cases, oxides are mixed in the molten metal.

However, when the oxide enters the molten metal holding furnace in this way, the oxide fills the cavity in the mold together with the molten metal, causing casting defects such as slag. Therefore, each time the molten metal is replenished into the molten metal holding furnace, oxide removal work must be performed, which places an excessive burden on the operator and requires a considerable amount of time to replenish the molten metal. The inconvenience of not being able to carry out the process has been pointed out.

Furthermore, heating means such as heaters are installed in the molten metal holding furnace to maintain the molten metal at a predetermined temperature, and if the aforementioned oxide removal work is performed frequently, the risk of damaging the heating means increases. Resulting in.

[Object of the Invention] The present invention has been made to overcome the above-mentioned disadvantages, and includes a molten metal holding chamber for pressurizing molten metal into a cavity in a mold via a stalk in a molten metal holding furnace; a molten metal replenishment chamber for replenishing the molten metal, and communicates the molten metal holding chamber and the molten metal replenishment chamber via a filter,
This makes it possible to prevent oxides from entering the molten metal holding chamber through the filter even if oxides are present in the molten metal supplied to the molten metal replenishment chamber from a calming furnace or the like. It is possible to obtain a cast product of excellent quality without casting defects such as cracks, and it is not necessary to perform oxide removal work every time molten metal is replenished, so the molten metal replenishment work can be easily and quickly performed at once. The purpose of the present invention is to provide a low-pressure casting device that can

[Means for achieving the object] In order to achieve the above object, the present invention defines a molten metal holding furnace that heats and holds molten metal, and a casting cavity that communicates with the inside of the molten metal holding furnace via a stalk. The molten metal holding furnace is equipped with a molten metal holding chamber in which the end of the stalk is immersed in the molten metal, and a molten metal replenishment chamber in which new molten metal is supplied from the outside. The present invention is characterized in that a filter member is provided to introduce the new molten metal into the holding chamber and to prevent oxides and the like from entering.

[Embodiments] Next, preferred embodiments of the low-pressure casting apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

In FIGS. 1 and 2, reference numeral 10 indicates a low-pressure casting apparatus according to this embodiment. The apparatus 10 is substantially composed of a molten metal holding furnace 12 and a mold 14. The molten metal holding furnace 12 includes a casing 16, and the casing 16 defines a molten metal holding chamber 18 with a relatively large capacity and a molten metal replenishment chamber 20 with a relatively small capacity. Openings 22a and 22b are defined in the side wall of the casing 16 to open the molten metal holding chamber 18 and the molten metal replenishment chamber 20 to the outside, respectively, and the openings 22a and 22b each have lids 24a and 24b. It is constructed so that it can be opened and closed freely. Furthermore, the casing 16
A passage 26 is formed on the lower side of the partition wall 16a between the molten metal holding chamber 18 and the molten metal replenishment chamber 20, and a filter 28 is attached to the wall surface of the partition wall 16a on the molten metal replenishment chamber 20 side. In this case, the filter 28 is formed of, for example, porous ceramics or a stainless steel plate having a plurality of pores. That is, the filter 28
As long as it has the function of allowing the molten metal (described later) to pass therethrough while blocking the passage of oxides mixed in the molten metal, various other types may be used.

As shown in FIG. 2, one end of a replenishment stalk 30 enters the molten metal replenishment chamber 20 with an inclination in the vertical direction, and the other end of the replenishment stalk 30 exposed to the outside has an opening/closing lid 3.
2 is provided. Further, a plurality of heaters 36a and 36b are arranged in the molten metal holding chamber 18 and the molten metal replenishment chamber 20 to maintain the molten metal 34 stored therein at a predetermined temperature.

Next, a furnace lid 38 is mounted on the upper part of the casing 16, and the first and second beds 46a and 46b are placed at one end of the furnace lid 38, that is, located above the molten metal holding chamber 18, so that the first and second beds 46a and 46b overlap. will be published. These beds 46a, 46b hold the stalks 48a, 48b, and the stalks 48a, 48b penetrate the furnace lid 38 and have their ends immersed in the molten metal 34 in the molten metal holding chamber 18. A lower mold 50 constituting the mold 14 is placed on the bed 46b,
An upper mold 52 is disposed above the lower mold 50 and is movable via a lifting means (not shown). In addition, bed 4
Four side molds 54a to 54d are arranged on the upper mold 6b so as to be movable back and forth, and these side molds 54a to 54d and the lower mold 50
and the upper mold 52 define a cavity 56 that exhibits the desired casting shape, and this cavity 56 is connected to the stalk 48.
a, 48b via sprues 58a, 58b.

On the other hand, a degassing means 60 is mounted on the furnace lid 38, and a rod 62 extends from the degassing means 60 into the molten metal replenishment chamber 20. This rod 62 is immersed in the molten metal 34, and its tip is immersed in the molten metal 34. A rotating blade 64 is provided in the section. The degassing means 60 is provided with a passage (not shown) that communicates with the molten metal replenishment chamber 20, and this passage communicates with an inert gas supply device (not shown).

In FIG. 2, reference numeral 70 indicates a sedation furnace, and a molten metal 34 is stored in a casing 72 constituting this sedation furnace 70, and a supply pipe 74 whose one end is immersed in the molten metal 34 is The other end is engageable with the supply stalk 30. Further, the sedation furnace 70 is equipped with a degassing means 76 having the same configuration as the degassing means 60 described above.

The low-pressure casting apparatus according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, the upper mold 52 and the side molds 54a to 5 are attached to the lower mold 50.
4d is closely displaced to close the mold 14 to form the cavity 5.
6. Next, for example, pressurized gas is introduced into the molten metal holding chamber 18 through a passage (not shown) provided in the furnace cover 38, and the molten metal 34 stored in the molten metal holding chamber 18 is heated.
Pressure is applied to the surface of the molten metal.

Therefore, the pressurized molten metal 34 is moved to the stalk 48a,
48b, and is filled and pressurized into the cavity 56 through the sprues 58a and 58b. After cooling for a predetermined period of time, the mold 14 is opened and the cast product solidified in the cavity 56 is released, and then a new cast product is cast as described above.

As described above, as the casting operation continues through the low-pressure casting apparatus 10, the molten metal 3 stored in the molten metal holding chamber 18
4 decreases, and it becomes necessary to replenish the molten metal holding chamber 18 with new molten metal 34.

Therefore, the opening/closing lid 32 that closes the replenishment stalk 30 is opened, and the supply pipe 74 of the sedation furnace 70 is engaged with the replenishment stalk 30. Next, the sedation furnace 70 is driven to transfer the molten metal 34 stored in the casing 72 to the supply pipe 74.
From there, the molten metal is supplied into the replenishment chamber 20 via the replenishment stalk 30. At that time, the rotating blade 64 that constitutes the degassing means 60
is rotated under the driving action of a drive source (not shown) to agitate the molten metal 34 in which the rotary blade 64 is immersed, and an inert gas is supplied into the molten metal 34 from an inert gas supply device, so that the molten metal 34 is cause the gas to float upwards.

Therefore, the gas stored in the molten metal replenishment chamber 20 is led out to the outside through the gap defined in the device 10.

Molten metal 3 supplied from the calming furnace 70 to the molten metal replenishment chamber 20
4 is introduced into the molten metal holding chamber 18 from the filter 28 through the passage 26 after being subjected to degassing treatment as described above. Then, a predetermined amount of molten metal 34 is placed in the molten metal holding chamber 18.
After the supply of molten metal 34 from the sedation furnace 70 is completed, the supply pipe 74 is separated from the supply stalk 30, and the opening/closing lid 32 is operated to close. As a result, a new casting process is performed by the low-pressure casting apparatus 10.

In this case, in this embodiment, the molten metal 34 is not directly supplied from the calming furnace 70 to the molten metal holding chamber 18, but the molten metal 34 is first supplied to the molten metal replenishment chamber 20, and the molten metal 34 is passed through the filter 28 to the molten metal. It is configured to be fed into the holding chamber 18. Therefore, if oxides are present in the molten metal 34 supplied from the calming furnace 70 into the molten metal replenishment chamber 20, the oxides will be blocked by the filter 28 and will not enter the molten metal holding chamber 18. Therefore, it is possible to prevent the molten metal 34 in the molten metal holding chamber 18 from being mixed with oxides and the cavity 56 being filled with the molten metal 34 containing the oxides, thereby preventing casting defects such as molding. This has the effect that high-quality cast products can always be molded through the low-pressure casting apparatus 10. Furthermore, after the molten metal 34 is supplied from the calming furnace 70 to the molten metal replenishment chamber 20, the low-pressure casting apparatus 10 can be driven immediately. As a result, compared to the conventional method in which oxides are removed every time the molten metal 34 is supplied, the time required for replenishing the molten metal 34 is drastically shortened, making it possible to carry out an extremely efficient casting process. You get the advantage of being able to do it.

Furthermore, in the low pressure casting apparatus IO, the casing 1
6 is provided with an opening 22b that communicates with the molten metal replenishment chamber 20, and this opening 22b is configured to be openable and closable by a lid 24b. Therefore, if the lid 24b is opened before the casting operation by the low-pressure casting device 10 or after the casting operation is finished, and the oxide present in the molten metal replenishment chamber 20 is removed, this oxide removal operation can be performed. There is no need to stop the casting operation at any time, resulting in an efficient effect.

Further, the casing 16 is provided with a lid 24a for opening and closing an opening 22a provided in the molten metal holding chamber 18. Therefore, it is also possible to remove oxides and the like from the molten metal 34 stored in the molten metal holding chamber 18 through this opening 22a.

[Effects of the Invention] As described above, according to the present invention, new molten metal is supplied from the molten metal holding chamber and the sedation furnace for supplying molten metal to the cavity defined in the mold via the stalk. The molten metal replenishment chamber is provided with a molten metal replenishment chamber, and the molten metal holding chamber and the molten metal replenishment chamber are configured to communicate with each other via a filter. Therefore, even if oxides are mixed in the molten metal supplied to the molten metal replenishment chamber, the oxides are blocked by the filter and will not enter the molten metal holding chamber. As a result, the cavity can be filled with clean molten metal free of oxides at all times, and a high-quality cast product without casting defects can be obtained. Moreover, unlike conventional methods that supply molten metal directly from the outside to the molten metal holding chamber,
There is no need to perform oxide removal work every time molten metal is replenished, and there is an advantage that efficiency of the entire casting process can be easily achieved. In addition, if at least the molten metal replenishment chamber is provided with an opening that can be opened and closed for removing oxides, and oxides are removed from this opening as necessary, oxide removal work can be done without interrupting casting work. Another advantage is that it can be carried out effectively.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective explanatory diagram of a low-pressure casting apparatus according to the present invention; FIG. 2 is a longitudinal cross-sectional view of the low-pressure casting apparatus.

Claims (4)

[Claims] (1) Consisting of a molten metal holding furnace that heats and holds molten metal, and a mold defining a cavity for a casting that communicates with the inside of the molten metal holding furnace via a stalk, the molten metal holding furnace has an end portion of the stalk. It is equipped with a molten metal holding chamber that is immersed in the molten metal and a molten metal replenishment chamber that replenishes new molten metal from the outside, and also introduces the new molten metal from the molten metal replenishment chamber into the molten metal holding chamber and prevents oxides etc. from entering. A low-pressure casting device characterized in that it is provided with a filter member. (2) The apparatus according to claim 1, characterized by having an opening that can be freely opened and closed to the outside through the lid body to communicate with the molten metal replenishment chamber and/or the molten metal holding chamber and perform the removal work of oxides, etc. Low pressure casting equipment. (3) The low-pressure casting apparatus according to claim 1, wherein the filter member is substantially made of porous ceramics. 4. The low pressure casting apparatus according to claim 1, wherein the filter member is substantially made of stainless steel having a plurality of pores.