JPH0230360A - Production of cast iron product - Google Patents

Abstract

PURPOSE:To obtain a cast iron product, the desired surface of which is deeply chilled at constant depth, by setting flat plate-like graphite-made chiller at adjoining position of flat surface in a product to be produced with shell mold type casting mold to an inserting core type and pouring molten cast iron containing the specific ratio of carbon. CONSTITUTION:In the shell mold type casting mold composing of an upper mold 1 and a lower mold 2, tappet-shaped casting molten metal space 3 and a sprue 4 are formed and further, the flat plate-shaped graphite-made chiller 5 (the dot line in the figure is the part corresponding to the flat lower surface 8 in the space 3) is set. Then, the casting mold composing of the above constitution is used and the molten cast iron containing of 3.0-3.7% C is poured into the space 3. By this method, the cast iron product, which the above flat surface 8 is chilled, is obtd. As the above method uses the graphite-made chiller and high carbon molten cast iron, the desired surface in the casting product can be deeply chilled at constant depth. Further, carbonization into the product caused by the chiller and welding between the chiller and the product can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a casting method in which a product is chilled by placing a chiller in a mold.

[Prior Art] There are two methods of imparting wear resistance to a part of the surface of a cast article by chill-hardening it at the same time as casting. When using a chiller (for example, Utility Model Act 53-249
No. 63, Japanese Unexamined Patent Publication No. 48-83033M>.

In the former case, as shown in FIG. 2, a mold 7 having a pouring space 3 is placed on a surface plate 6, and the flat bottom surface 8 of the product is poured into the surface plate 6 by pouring the metal from the sprue 4. Cool rapidly to chill.

In the latter case, a chiller is placed in the area to be chill-hardened, and the material is rapidly cooled and chilled with the chiller.

[Problems to be Solved by the Invention] When the surface plate is made of iron-based material, the chill depth may be shallow, the depth may vary, or the product and the surface plate may be welded together. In addition, it is heavy and has poor workability.

There are also surface plates made of graphite, and since graphite has a high thermal conductivity and a great cooling effect, there is no problem with how to insert the chill, but since the surface plates are large, using expensive graphite will increase manufacturing costs. .

When using a cold metal, if it is made of iron, the depth of the chill may be shallow, the depth may vary, or the product and the cold metal may weld. In addition, it is heavy and has poor workability.

In addition, even in the case of a graphite cooling metal, there is a risk that it may be damaged during demolding or the product may be affected by carburization, so it is recommended to insert a steel washer between the molten metal and the cooling metal. This method is expensive, and fishing is no longer done by boat.

Therefore, an object of the present invention is to provide a manufacturing method that can consistently increase the chill depth of a cast iron article and reduce costs.

[Means for Solving the Problems] In order to solve the above problems, according to the present invention, a flat graphite chiller is placed in a shell mold mold at a position adjacent to a flat surface of an article to be manufactured. A method for producing a cast iron article is provided, characterized in that said flat surface is chilled by placing it in a nested manner and pouring molten cast iron containing 3.0 to 3.7% carbon. Ru.

[Function] The desired surface of the product is deeply and uniformly chilled by the graphite chiller, but since cast iron with a high carbon content of 3.0 to 3.7% is used as the molten metal, the product is chilled by the chiller. It is possible to avoid harms such as not being able to obtain the desired chilled structure due to carburization.

Furthermore, since a flat, nested chiller is used, both the material cost and manufacturing cost of the chiller can be reduced.

Furthermore, if a shell mold is used, the mold becomes porous and easily disintegrates after solidification, so the chilled mold can be taken out and used repeatedly without damaging it.

[Example] Hereinafter, an example of the present invention using a chiller made of graphite will be described together with a comparative example using a chiller made of cast iron and steel.

In order to manufacture tappets used in internal combustion engines, the first
As shown in the figure, a tappet-shaped casting space 3 (height 70 m5
, a diameter of 25 m on the lower surface and a sprue 4, and a vertical 20 m
A flat plate chiller 5 (see FIG. 3; the dotted line corresponds to the flat lower surface 8 of the casting space) was placed.

Three types of chilled metal molds 5 were prepared: one made of graphite, one made of cast iron, and one made of steel, and four molds with Nα1 to 4 were manufactured for each mold. There are 12 casting spaces 3 (2 rows x 6
Individual. See Figure 3. ) established.

For such a mold, C: 3.4%, Si: 2.2
%, Hn: 0.7%, Cr: 0.7%, and Fe: the remainder. The results of measuring the chill depth of the flat surface 8) are shown in FIGS. 4 to 7.

As can be seen from this result, when a cast iron chiller is used, the chill depth may become extremely shallow, and the depth varies widely. In the case of steel, it is as deep and consistent as graphite, but in about 10% of cases the product and the cold metal were welded together. Approximately 10% of cast iron was also welded. In the case of graphite, the chill structure was formed consistently and deeply, and there was no welding.

[Effects of the Invention] As described above, according to the present invention, since a chilled graphite metal and a high carbon molten cast iron are used, a desired surface of a cast product can be uniformly and deeply chilled, and This prevents carburization of the product by the cold metal and welding of the cold metal and the product.

In addition, since the chiller is relatively small and has a simple flat plate shape, manufacturing costs can be reduced, and it is relatively lightweight, making it easy to work with.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing the method of the present invention, Fig. 2 is a longitudinal sectional view showing the conventional method, Fig. 3 is a perspective view showing a chiller, and Figs. 4 to 7 are , is a graph showing the results of a comparative test of chill depth. Explanation of symbols 1...Upper mold, 2...Lower mold, 3...Pouring space, 5.
...Cold metal, 8...Flat bottom surface

Claims (1)

[Claims] A flat graphite chiller is nested in the shell mold adjacent to the flat surface of the article to be manufactured, and molten cast iron containing 3.0 to 3.7% carbon is poured into the shell mold. A method for manufacturing a cast iron article, characterized in that the flat surface is chilled by pouring the metal.