JPH0456708B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a manufacturing method, and more particularly to a casting method in which a molten metal is partially forcedly cooled to promote solidification of the molten metal to efficiently obtain a high-quality casting free of casting defects. [Prior Art] In order to manufacture reliable aluminum alloy castings and the like without casting defects, it is desirable that the molten metal solidify quickly and that the molten metal solidify directionally. Conventionally, mainly in gravity casting methods and low-pressure casting methods, solidification of molten metal has been promoted by cooling the mold with water or air. However, in this case, it is necessary to adjust the mold temperature relatively strictly to prevent poor flow during pouring due to overcooling of the mold, but the mold temperature fluctuates periodically with the casting cycle. Therefore, relatively sophisticated control technology is required to control the temperature of the mold. Therefore, in order to prevent poor water flow, the mold temperature is usually maintained at a high level, resulting in slow solidification. Furthermore, since a cooling means is incorporated into the mold, the mold structure becomes complicated and the cost of the mold increases. In addition, in order to eliminate casting defects, the installation location, shape, capacity, etc. of the feeder are selected and set empirically in order to perform directional solidification. but,
Due to the shape constraints of the casting, there are limits to the selection and setting of the installation location, shape, capacity, etc. of the feeder, and it is often impossible to achieve good directional solidification using the feeder alone. Therefore, the present applicant proposed a direct cooling method for casting, which promotes directional solidification by providing an extra wall in the casting during casting and forcing the extra wall to cool. Public bulletin). This direct cooling casting method has the advantageous effects of promoting directional solidification, improving the quality of the casting, and shortening the casting cycle. [Problems to be solved by the invention] However, in the above direct cooling casting method,
Since extra thickness is provided in the casting for forced cooling, there are problems in that the yield of the casting is poor and it takes time to remove the extra thickness after casting. [Means for Solving the Problems] The above problems are solved by the casting method of the present invention described below. That is, the forced cooling casting method of the present invention involves pouring molten metal into a product cavity defined by a mold,
This is a casting method in which the molten metal is forcibly cooled during the solidification process, in which a heating and cooling member that penetrates the mold and also serves as an extrusion pin is installed in the area where the molten metal is desired to solidify quickly, before or during filling with the molten metal. The heating/cooling member is heated, the heating/cooling member is cooled after filling is completed, and the product is pushed out by operating the heating/cooling member after the molten metal has solidified. In the present invention, both a sand mold and a metal mold can be used as the mold, and both can be used together for the upper mold and the lower mold. Furthermore, when using a self-hardening mold, either an organic self-hardening mold or an inorganic self-hardening mold can be used. The heating and cooling member may be any material as long as it does not dissolve in the molten metal, but it is particularly desirable to use a material with good thermal conductivity, such as copper alloy.Heating and cooling members usually consist of a head and a shaft, and the head is connected to the shaft. It is said that the diameter is larger than that of the The cross-sectional shape of the heating/cooling member may be, for example, circular or square, and may have any shape. Further, the heating and cooling member is provided so as to pass through the mold (lower mold) and the surface plate and extend outside the mold. As the mounting structure for this heating and cooling member, for example, the structures shown in FIG. 2 and FIGS. 4 to 8 can be considered. The heating and cooling member shown in Fig. 2 is a general one.
If the spring 14 is attached as shown in FIG. 4, the urging force of the spring 14 will return it to its original position. Further, as shown in FIG. 5, a weight 15 may be provided in place of the spring 14, and the spring 14 may be returned to its original position by its own weight. The structure shown in FIG. 6 is effective when a large contact area with the product cavity cannot be secured.
Figures 7 and 8 show the spring 1, respectively, so that it can automatically return to its original position in the case of Figure 6.
4. A weight 15 was attached. Note that it may be returned to the original position by external force. [Function] According to the casting method of the present invention, the heating/cooling member is provided to penetrate the mold, and one end of the heating/cooling member is extended outside the mold, thereby making it possible to directly heat or cool the heating/cooling member. Ta. As a result, since the heating and cooling member is heated before or during filling with molten metal, the running performance of the molten metal is improved. and,
Once the product cavity is sufficiently filled with the molten metal, the heating and cooling member is cooled using a cooling medium such as water. Then, the heat of the molten metal is absorbed by the heating/cooling member, and as long as the heating/cooling member continues to be cooled, the heat continues to be removed. Therefore, the portion of the molten metal that is in contact with the heating/cooling member is forcibly cooled, and directional solidification is promoted around this portion. [Example] Next, an example of the present invention will be described with reference to the drawings. This example shows an example of casting an aluminum alloy cylinder head. Here, FIG. 1 is a sectional view showing the casting process of the casting method according to the embodiment of the present invention, and FIG.
FIG. 3 is a schematic diagram illustrating the state of directional solidification of the casting method according to the embodiment of the present invention. In FIG. 1, 1 is an upper mold made of an organic self-hardening material, and 2 is a lower mold made of a metal mold. A mold 3 is formed by the upper mold 1, the lower mold 2, and a core (not shown), and this mold 3 defines a product cavity 4 of the cylinder head. This mold 3 is fixed on a surface plate 5, and a copper alloy heating and cooling member 6 (only three are visible in Fig. ) is attached. As shown in FIG. 2, the heating/cooling member 6 has a head portion that contacts the molten metal and has a larger diameter than the shaft portion so as not to drop downward. The surface plate 5 is movably placed on a moving roller 7, and a heating burner 9, a water cooling nozzle 10, and a hydraulic cylinder are installed at a predetermined interval on the bottom of a frame 8 to which the moving roller 7 is attached. A push-out plate 12 driven by 11 is attached. A cylinder head was cast using the above mold 3 in the following manner. First, approximately 100 μm of graphite coating is applied to the lower mold 2. Then, before pouring the molten metal, the heating and cooling member 6 is
As shown, preheat to approximately 500°C using heating burner 9. At this time, the temperature of the mold 3 is approximately 80°C. Subsequently, the surface plate 5 on which the mold 3 is placed is moved on the moving rollers 7 and fixed at the position shown in FIG. 1b. Here, in the product cavity 4 of the mold 3, JIS
Melted aluminum alloy 13 equivalent to AC4B at 700℃
I adjusted the temperature and poured hot water. Molten metal 1 in product cavity 4
3 was completed, water was injected from the water cooling nozzle 10 onto the shaft portion of the heating/cooling member 6 provided on the lower mold 2 protruding from the surface plate 5. ^1.0m3 /
After cooling with water for 4 minutes at a rate of h, the injection is stopped. Next, the surface plate 5 is moved on the moving roller 7,
Fix it in the position shown in Figure 1c. Here, the casting rough material was taken out from the mold 3 by activating the hydraulic cylinder 11 and pushing the extrusion plate 12 upward. When casting the cylinder head, the time required for the aluminum alloy to start forming binary eutectic formation was measured at three points A, B, and C shown in FIG. The measurement results are shown in Table 1 together with the conventional example (one without forced cooling).

〔Effect of the invention〕

As described above, the forced cooling casting method of the present invention provides the following effects. (b) Since the heating/cooling member is heated before or during filling with molten metal, the molten metal can easily circulate inside the product cavity, eliminating the problem of poor molten metal circulation, and solidifying by cooling the heating/cooling member after filling. can accelerate directional coagulation. Therefore, there are no casting defects such as shrinkage cavities,
A high quality casting (product) with excellent mechanical strength can be obtained. (b) Unlike the conventional direct cooling casting method, there is no need to provide extra wall for forced cooling in the casting, so the yield of the product (casting) is greatly improved. (c) An advantage of the conventional casting direct cooling method is that there is no need to remove the excess wall of the casting in the post-processing process, so the overall casting cycle can be shortened. (d) The mold temperature at the start of casting can be set at a lower temperature (below 150°C), improving dimensional accuracy.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the casting process of the casting method according to the embodiment of the present invention, Fig. 2 is an enlarged view of part A in Fig. 1, and Fig. 3 is the directivity of the casting method according to the embodiment of the present invention. A schematic configuration diagram explaining the state of solidification, FIG. 4 is a sectional view showing an embodiment of the mounting state of the heating and cooling member that can be used in the present invention, and FIG. 6 is a sectional view showing another embodiment of the mounting state of the cooling member that can be used in the present invention, and FIG. 7 is a sectional view showing another embodiment of the mounting state of the heating and cooling member that can be used in the present invention. FIG. 8 is a cross-sectional view showing another embodiment of the mounting state of the heating and cooling member that can be used in the present invention. FIG. . 1... Upper mold, 2... Lower mold, 3... Mold, 4...
Product cavity, 5... Surface plate, 6... Heating/cooling member, 7... Moving roller, 8... Frame, 9... Heating burner, 10... Water cooling nozzle, 11... Hydraulic cylinder, 12... Extrusion Plate, 13... Molten metal, 14...
Spring, 15... weight.

Claims (1)

[Scope of Claims] 1. A casting method in which molten metal is poured into a product cavity defined by a mold, and the molten metal is forcibly cooled during the solidification process, and the mold is penetrated at a portion where it is desired to accelerate the solidification of the molten metal. A heating and cooling member that also serves as an extrusion pin is installed, and the heating and cooling member is heated before or during filling with the molten metal, and is cooled after filling is completed, and after the molten metal has solidified, the heating and cooling member is heated. A casting method characterized by extruding the product by activating.