JPH0462820B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a vertical casting method, and particularly to a vertical casting method that advantageously removes metal oxides, non-metallic inclusions, etc. in molten metal flowing into a casting cavity of a mold. The present invention relates to a method that allows casting products of excellent quality to be cast with good workability by removing the metal.

(Background technology/problems to be solved) Traditionally, when casting products such as cast iron products, an upper mold and a lower mold are used as molds.
A horizontal casting method has been adopted in which a specified amount of molten metal is introduced into a casting cavity formed by stacking them one on top of the other, but in recent years, this method has become particularly popular when casting a large number of cast products such as elbows. An effective method for this purpose is the vertical casting method, known as the so-called disamatic molding method.
Vertical molds are stacked horizontally to form a predetermined casting cavity between the molds, while molten metal poured from above is guided into the casting cavity to form the desired cast product. The method is receiving attention.

More specifically, in such a vertical casting method, first, molding sand 4 supplied from a sand hopper 2 is compressed in a molding chamber 8 of a molding machine 6, as shown in FIGS. A high-density mold 10 is formed. In addition,
This mold 10 is generally shaped so that casting cavities 12 for producing a predetermined cast product are formed on both sides thereof, and as shown in FIG. 1c, these molds 10 are stacked horizontally. By doing so, the adjacent mold 1
A predetermined casting cavity 12 is formed between 0 and 10. In other words, mold 1
The molds 10 are stacked horizontally so that the mating surfaces (parting lines) of 0 are substantially vertical, and a predetermined casting cavity 12 is formed between them.
0 are successively stacked on top of each other, casting cavities 1 are formed on both sides of one mold 10, respectively.
2 and 12 are formed. Then, the molten metal 16 in the ladle 14 is poured from above into the casting cavity 12 formed between the molds 10, 10, and the desired cast products 18 are successively cast. .

By the way, in such a vertical casting method, the molten metal 16 is poured from above into the molten metal passage formed on the mating surfaces of the mold 10.
Since it is caused to fall and is guided into the casting cavity 12, it is likely that various foreign substances, such as slag and foundry sand, will be dragged in, thereby degrading the quality of the product or deteriorating the product yield. There are inherent problems such as nuisance.

However, in the case of the conventional horizontal casting method, it is relatively difficult to remove such foreign substances, such as metal oxides and non-metallic inclusions, by applying various measures inside the mold. Although easy, in the case of the above-mentioned vertical casting method, it was extremely difficult to take such removal measures and clean the molten metal.
In order to modify the molten metal to be poured, it is not possible to carry out an in-mold inoculation or in-mold graphite spheroidization method in which an inoculant or a graphite spheroidizing agent is placed in the mold and brought into contact with the molten metal. , is said to be extremely difficult.

On the other hand, the present inventor previously disclosed in Japanese Patent Application No. 60-59073 and No. 60-71845 that a ceramic porous body having a three-dimensional network skeleton structure having continuous pores was used, and the poured molten metal was They have proposed an instant inoculation casting method or an instant spheroidization treatment method in a mold, in which the material is inoculated with an inoculant or a graphite spheroidizing agent and then introduced into a casting cavity through the ceramic porous body. By using the ceramic porous body disclosed therein and setting it in the molten metal passage in the mold in the above-mentioned vertical casting method to allow the molten metal to pass through, it is possible to prevent the contamination of foreign substances such as slag and sand, and furthermore This effectively prevents contamination of undissolved inoculant and graphite nodularizing agent.

However, when such a porous ceramic body having a three-dimensional network skeleton structure having continuous pores is set in a molten metal passage formed on the mating surfaces of horizontally superimposed molds so as to partition the passage, such Since the ceramic porous body has a porous structure on its entire surface and therefore has a jagged, uneven surface, when the ceramic porous body is fitted into the recess of the molten metal passage of the mold, it is necessary to configure the mold. Therefore, it is necessary to pay close attention to the setting of such porous ceramic bodies. This is because the foundry sand dropped during setting of the ceramic porous body is directly introduced into the casting cavity along with the molten metal, significantly reducing the quality of the resulting cast product.

(Solution Means) Here, the present invention has been made to solve the above-mentioned problems, and its feature is that vertical molds are superimposed on each other in the horizontal direction, and there is a gap between the molds. While forming a predetermined casting cavity, a ceramic porous body having a three-dimensional network skeleton structure having continuous pores is used to guide the molten metal poured from above into the casting cavity to form the desired cast product. ,
While housed in a bottomed cylinder that covers at least its sides and has a molten metal passage hole at the bottom, the molten metal is set in a molten metal passage formed on the mating surfaces of the mold so as to partition it, and the poured molten metal is The molten metal is guided into the casting cavity by passing through the ceramic porous body.

That is, in the present invention, a ceramic porous body with a three-dimensional network skeleton structure having continuous pores is not directly set in the molten metal passage of a mold, but such a ceramic porous body is housed in a bottomed cylinder. In other words, the jagged uneven portion of the circumferential surface of the porous ceramic body is covered with a cylinder with a bottom, and the mold is set through the smooth surface of the cylinder with a bottom so that it does not come into contact with the mold surface. This makes it possible to effectively prevent molding sand from being scraped off during setting.

(Specific Description/Examples of Configuration) Hereinafter, the configuration of the present invention will be explained in more detail with reference to the embodiments shown in the drawings.

First, FIG. 2 is a partial front view of the casting cavity forming side of a vertical mold 20 for casting a large number of elbows at once, which is molded by a conventional method. There is a sprue forming recess 22 for forming a sprue that opens upward and receives a predetermined molten metal poured from above.
A runner forming recess 24 is provided following the sprue forming recess 22 to form a runner for guiding the molten metal to be poured. A large number of casting cavity forming recesses 26 are formed which are connected to the recesses 24 and are used to form the intended casting product (elbow).

As is well known, such a mold 20 has a sprue forming recess 22 and a runner forming recess 24.
and another mold 20 that cooperates with the casting cavity forming recess 26 to form a predetermined sprue, runner, and casting cavity, as shown in FIG. , a sprue, a runner, and a casting cavity are respectively formed in the mating surfaces of the recesses 22, 24, and 26. Furthermore, due to this overlapping, a mating surface (parting line) 28 is formed in a substantially vertical direction. Note that the sprues, runners, and casting cavities are usually formed on both sides of the mold 20, as shown in FIG. 1C.

In addition, in such a mold structure, the bottom of the sprue forming recess 22, in other words, the runner forming recess 2
A circumferentially extending shell receiving recess 30 located near the connection to each mold 2
0. A bottomed cylindrical shell 36 containing a predetermined ceramic porous body 32 and having a molten metal passage hole 34 at the bottom is fitted into the shell accommodating recess 30 to form a molten metal passage as shown in FIG. It has come to be possible to set the rules by dividing the

By the way, the ceramic porous body 32 accommodated in such a shell 36 is as shown in FIG.
It consists of a three-dimensional network skeleton structure with continuous pores, such as cordierite, alumina,
Alternatively, it is a ceramic foam composed mainly of SiC, etc., with a high porosity (for example, about 80 to 90%) and continuous pores like a sponge, and has a jagged shape on its entire surface. It is something. This ceramic porous body 32
In addition to the disk-like or cylindrical shape shown in the drawings, it can be used in various shapes such as rectangular (rectangular parallelepiped) and polygonal shapes.

In addition, since the shell 36 that accommodates the ceramic porous body 32 is in contact with the molten metal that is being poured, it should be made of a material that has excellent fire resistance and does not adversely affect the quality of the molten metal. A material with a smooth surface, such as a shell molded product or a ceramic product, is preferably used. The shell 36 has a cylindrical shape with a bottom and is formed at a height that covers at least the side surfaces of the ceramic porous body 32 to be accommodated. The inner surface has a shape in which the gap between the porous ceramic bodies 32 is reduced as much as possible, and a groove is provided at the bottom of the porous ceramic body 32 so that the molten metal that has passed through the porous ceramic body 32 is guided to the casting cavity side below. , a molten metal through hole 34 of a predetermined size is formed.

As described above, the shell 36 housing the ceramic porous body 32 separates the molten metal passages (gates and runners) formed by overlapping the molds 20, 20, and It is fitted into the shell receiving recess 30 of the mold 20 and set. Therefore, in this setting work, the ceramic porous body 3
2 does not come into contact with the mold 20 (more specifically, the shell housing recess 30), the molding sand is scraped off from the mold 20 on the jagged surface of the ceramic porous body 32. Such problems never occur. Further, the shell 36 containing the ceramic porous body 32 is loaded into the core 38 using, for example, a normal core loading device used in the conventional vertical casting method, as shown in FIG.
At the same time, it can be easily loaded between the molds 20, 20, thereby making it possible to automate the loading.

Therefore, in this way, the shell 36 containing the predetermined ceramic porous body 32 is placed in the mold 2.
When a predetermined casting operation is performed in a state where the molten metal passage formed between 0 and 20 is partitioned and set, the molten metal poured from above flows from the sprue 22 into the molds 20 and 20. However, since the porous ceramic body 32 supported by the shell 36 is placed there, the porous ceramic body 3
2 and through the molten metal passages 34 in the bottom of the shell 36, and then through the runners 24 and into the respective casting cavities 26. Metal oxides and non-metallic inclusions such as slag and foundry sand are effectively filtered out by the filter effect of the ceramic porous body 32, and the cast cavity 26 is filled with cleaned molten metal. will be guided. Therefore, even without paying close attention to the pouring process of molten metal, the quality of the resulting cast products is significantly improved.
In addition, problems such as a decrease in product yield due to sand encroachment are also a problem.
It can be effectively suppressed.

Moreover, in the present invention, since the loading operation of the ceramic porous body 32 into the mold 20 is performed via the shell 36,
Dust removal from the mold 20 due to contact with such a jagged surface of the ceramic porous body 32 can be effectively prevented, and thereby,
The loading operation of the ceramic porous body 32 becomes extremely easy, and the reduction in product quality or yield caused by the entrainment of dropped foundry sand into the molten metal can be effectively eliminated. It is.

Further, as shown in FIG. 5, for example, an inoculant or a graphite nodularizing agent 40 is applied onto the ceramic porous body 32 set in the molten metal passage formed between the molds 20, 20. This makes it possible to modify the poured molten metal (molten cast iron) in an in-mold manner. That is, when manufacturing a desired cast product according to the vertical casting method, instant inoculation or instant spheroidization treatment can be performed within the mold. Then, while the molten metal poured in this way inoculates the inoculant 40,
It passes through the ceramic porous body 32, is introduced into the casting cavity 26 in an over-inoculated state, and is solidified, thereby fully exhibiting the effect of normal in-mold inoculation,
It is now possible to produce cast products with sound internal and external surfaces.For example, (a) the additive effect is achieved with approximately 1/3 of the amount added compared to ladle inoculation, and (b) the phenomenon in which the inoculation effect disappears over time. It exhibits characteristics such as the absence of

(Effects of the Invention) As is clear from the above description, the present invention provides a method for forming porous ceramics having a predetermined three-dimensional network skeleton structure between molds in a state where the ceramic porous body has a predetermined three-dimensional network skeleton structure and is accommodated in a bottomed cylindrical shell. By cleaning the poured molten metal, it reduces the need for careful cleaning work before pouring, and also removes slag and sand. Prevents the contamination of foreign substances such as
Furthermore, it enables unskilled workers to perform the pouring work, simplifies the automatic pouring device, and facilitates the work of setting the ceramic porous body, as well as automating the work. At the same time, the problem of sand removal during setting can be completely solved, and this is where the great industrial significance of the present invention lies.

[Brief explanation of the drawing]

Figures 1a, b, and c are cross-sectional explanatory views showing each step of the vertical casting method, and Figure 2 is a partial front view showing the cavity forming side of one of the molds used in the present invention. FIG. 3 is a view corresponding to the - cross section of FIG. 2 in a state in which such molds are stacked, and FIG. 4 is a perspective view showing the porous ceramic body and the shell that accommodates it taken out. , FIG. 5 is an enlarged explanatory view showing an example of a state in which an inoculant or a graphite spheroidizing agent is placed on a ceramic porous body in the present invention. 20: Mold, 22: Gate forming recess, 24:
Runway forming recess, 26: Casting cavity forming recess,
28: mating surface, 30: shell forming recess, 32:
Ceramic porous body, 34: Molten metal through hole, 36: Shell, 38: Core, 40: Inoculant/graphite spheroidizing agent.

Claims (1)

[Claims] 1 Overlap the vertical molds horizontally,
A predetermined casting cavity is formed between these molds, and molten metal poured from above is guided into the casting cavity to form the desired cast product. A ceramic porous body is housed in a bottomed cylinder that covers at least its side surfaces and has a molten metal passage at the bottom, and sets it in a molten metal passage formed on the mating surface of the mold so as to partition it, A vertical casting method characterized in that the poured molten metal passes through the ceramic porous body and is guided into the casting cavity.