JP2010227965A - Method for controlling solidification of casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling the solidification of a casting by which the heat extraction speed of a chiller can be reduced without reducing the size of the chiller, and also, the heat extraction speed of the chiller can be reduced without pasting a heat insulating material. <P>SOLUTION: In the method for controlling the solidification of a casting using a chiller, a part or the whole of a surface in contact with a molten metal, of the chiller 1 is provided with a recessed shape 2, and the solidification of the molten metal in the recessed shape 2 is delayed. The pitch of the recessed shape 2 is 1 to 4 mm, the depth thereof is preferably 0.5 to 1.0 times the pitch, and it is preferable that a material having a thermal conductivity lower than that of the chiller 1 is arranged at the inside of the recessed shape 2, and that the thermal conductivity of the material having a low thermal conductivity is lower by 20 to 320 W/(m×K) than that of the chiller. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for controlling solidification of a casting. More specifically, the present invention can reduce the heat removal rate of the cooling metal without reducing the size of the cooling metal, and can be cooled without attaching a heat insulating material. The present invention relates to a solidification control method for a casting that can reduce the heat removal rate of gold.

  There are various casting methods, but the mold material is sand mold cured with resin, ceramic mold cured with ethyl silicate or colloidal silica, gypsum mold mixed with various refractory materials, Alternatively, a metal material such as steel is often used. In these castings, a cooling metal is often used for the purpose of improving the mechanical properties of the product part of the casting and directional solidification of the molten metal to prevent the occurrence of shrinkage defects.

  For example, Patent Documents 1 and 2 disclose techniques for utilizing the entire molten metal contact surface of the cooling metal for casting solidification / cooling promotion. Patent Document 3 discloses a technique that allows a heat extraction rate to be arbitrarily adjusted even by using a cooling metal having a large heat capacity by attaching a heat insulating material to a part of the cooling metal. ing. Patent Documents 4 and 5 disclose techniques for increasing the heat capacity and heat removal rate of cooling metal.

JP 2007-275973 A JP 2004-17145 A JP 2007-144480 A JP 2006-205228 A JP 2001-179392 A

  However, the methods described in Patent Documents 1, 2, 4, and 5 have the inconvenience that the size of the cooling metal must be reduced when it is desired to suppress the solidification and cooling of the casting. Further, in the method described in Patent Document 3, the heat insulating material must be prepared and affixed every time it is cast, and the heat insulating material becomes disposable, which is disadvantageous in terms of manufacturing cost. As described above, in the conventional cooling metal improvement technology, there are some problems when controlling the heat extraction effect of the cooling metal (heat extraction rate and heat extraction capacity from the molten metal). .

  Therefore, an object of the present invention is to provide a technique capable of reducing the heat removal rate of the cooling metal without reducing the size of the cooling metal. Another object of the present invention is to provide a technique capable of reducing the heat removal rate of the cooling metal without attaching a disposable heat insulating material.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the above-mentioned problems can be solved by setting the cooling metal to the following configuration, and has completed the present invention.

  That is, the solidification control method for a casting according to the present invention is a method for solidification control of a casting using a cooling metal, wherein a concave shape is provided on a part or all of the molten metal contact surface of the cooling metal, and the solidification of the molten metal in the concave shape is delayed. It is characterized by. Accordingly, it is possible to intentionally delay the solidification of the molten metal in the portion and promote the intentional solidification from the product portion to the hot metal side (hereinafter referred to as “directional solidification of the casting”).

  In the present invention, the concave pitch is preferably 1 to 4 mm, and the depth is preferably 0.5 to 1.0 times the pitch. By setting it as such a structure, the balance of the heat conduction characteristic of a cooling metal and the penetration | invasion to the concave shape of a molten metal can be aimed at. Moreover, it is preferable to arrange | position the material whose heat conductivity is lower than the said cooling metal in the said concave shape. Thereby, it becomes possible to adjust the melt solidification speed at the time of casting. Furthermore, the thermal conductivity of the material having low thermal conductivity is preferably 20 to 320 W / (m · K) lower than that of the cooling metal. Thereby, the said effect can be acquired favorably.

  The casting solidification control method of the present invention can be suitably applied to casting of a tire molding die. Since the mold for molding a tire cast by applying the solidification control method for casting according to the present invention does not cause shrinkage defects, it is possible to manufacture a tire having excellent quality.

  According to the present invention, the heat removal rate of the cooling metal can be reduced without reducing the size of the cooling metal, and the heat removal rate of the cooling gold can be reduced without attaching a heat insulating material. It is possible to provide a method for controlling the solidification of a casting that can be performed. As a result, it is possible to cast a casting having no shrinkage defect, particularly a tire molding die.

It is a perspective view which shows one suitable example of the cooling metal which concerns on this invention. It is an expanded sectional view of the contact part of a cooling metal and a molten metal. (A) And (b) is a schematic diagram showing the equal solidification time curved surface in the casting method in the conventional method and this invention, respectively. (A)-(c) is a perspective view which shows the other suitable example of the cooling metal which concerns on this invention, respectively. (A)-(d) is a perspective view of a suitable example at the time of arrange | positioning the material whose heat conductivity is lower than gold | metal | money, respectively, in a concave shape. (A) And (b) is the perspective view and half sectional view of the cast frame used for the Example. 1 is a half sectional view of a casting frame used in Example 1. FIG. It is a half sectional view of the casting frame used in Example 2. It is a half sectional view of the cast frame used for the comparative example 1. 6 is a half sectional view of a cast frame used in Comparative Example 2. FIG.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
The solidification control method for a casting according to the present invention is characterized in that, in the solidification control method for a casting using a cooling metal, a concave shape is provided on a part or all of the molten metal contact surface of the cooling metal, and the solidification of the molten metal in the concave shape is delayed. It is what. FIG. 1 is a perspective view of an example of a cooling metal according to the present invention, and has a concave shape 2 on the top of the cooling metal 1. FIG. 2 is a cross-sectional view at the time of contact between the cooling metal and the molten metal. By providing the concave shape 2 on the molten metal contact surface side of the cooling metal 1 where the molten metal 3 cannot enter at the time of casting, the molten metal 3 and the cooling metal 1 are in line contact, and intentionally delays the solidification of the molten metal at the site, It becomes possible to promote the directional solidification of the casting.

  FIG. 3 is a cross-sectional view of a casting that represents an iso-solid time curve of a conventional casting method (FIG. 3 (a)) and a casting method (FIG. 3 (b)) to which the solidification control method of the present invention is applied. FIG. Here, the uniform solidification time curved surface refers to a curved surface that completes solidification in the same time in the cooling process of the casting. 3A and 3B, the casting frame 4 is used as a cooling metal, the heat insulating material 9 is attached to the inner surface of the upper mold 8, and the casting is cast using the mold 7. As shown in FIG. 3 (a), when the conventional casting frame 4 is cast by using a metal member, the molten metal solidification on the casting frame 4 side is too fast, and the isosolid time curved surface 5 is not connected to the feeder 6. A space may be formed. A shrinkage defect will occur in this closed space. Therefore, until now, in order to suppress the shrinkage defect, it has been necessary to take measures to delay the solidification of the molten metal by attaching a heat insulating material to the upper part of the casting frame.

  However, in the present invention, by using the cooling metal 1 according to the present invention as the casting frame 4, it is possible to delay the solidification of the molten metal on the upper side of the casting frame without attaching a heat insulating material to the casting frame 4. did. As a result, a closed space in which the isosolid time curved surface 5 is not connected to the hot water 6 is not formed, and shrinkage defect generation can be effectively prevented (FIG. 3B).

  Further, in the case of conventional casting using a method in which the casting frame itself is used as a cooling metal, there is a trouble that a heat insulating material must be partially pasted on the molten metal contact surface. Furthermore, it has a demerit in the material cost of discarding the heat insulating material at every casting. However, according to the present invention, these problems can be easily solved.

  The concave shape 2 of the cooling metal 1 shown in FIG. 1 has a structure in which V grooves are continuous. However, in the present invention, as shown in FIG. The cooling metal 101 which has may be sufficient. Further, as shown in FIG. 4B, a chill metal 201 having a diamond cut shape as the concave shape 202, and a chill metal 301 having an embossed shape as the concave shape 302 as shown in FIG. 4C. May be. Furthermore, the cooling metal of the type which the part to which the concave shape 2 of the cooling metal 1 is given, and the part which is not given may isolate | separate, and it assembles at the time of use.

  In addition, it is desirable that the concave shape 2 engraved in the cooling metal 1 is the maximum in a range where the molten metal does not enter during casting. The concave shape 2 should be appropriately set according to the temperature of the cooling metal 1, the wettability with the molten metal, the molten metal temperature, the flow velocity of the molten metal, the molten metal pressure after the completion of casting, the molten metal material, and the like. Therefore, although it cannot be generally stated, it is desirable that the pitch W of the concave shape 2 is 1 to 4 mm, and the depth D of the concave shape 2 is 0.5 W to 1.0 W. When the pitch W of the concave shape 2 is less than 1 mm, or when the depth D of the concave shape 2 is less than 0.5 W, it is difficult to ensure sufficient heat conduction characteristics of the cooling metal. On the other hand, when the pitch W of the concave shape 2 exceeds 4 mm, or when the depth D of the concave shape 2 exceeds 1.0 W, the molten metal may enter the concave shape 2 during casting.

  Furthermore, the basic shape of the cooling metal is determined, and usually a hexahedron (cuboid) shape is often used. For this reason, there are six surfaces on the chilled gold surface. Common cooling metal is often used in such a way that one of these surfaces is in contact with the molten metal, but the heat conductivity of all six surfaces is almost equal, so the heat removal effect is subtly The only way to make adjustments was to change the size (dimensions and weight) of the chiller itself.

  On the other hand, if different concave shape distributions (pitch, depth) are given to all six surfaces of the chill metal, it is possible to select six types of extraction by simply selecting the molten metal contact surface with one chill metal. It can also be changed to thermal conditions. A normal casting manufacturer has to prepare a wide variety of cooling metal, and there is a trouble that a large number of cooling metals must be selected and used for each property to be cast. Has the effect of reducing this effort.

  Moreover, in this invention, it is preferable to arrange | position the material whose heat conductivity is lower than a cooling gold | metal | money in a concave shape. It is possible to adjust the molten metal solidification rate at the time of casting by arranging a material having a heat conductivity lower than that of gold cooled to a concave shape as a heat insulating material (refractory material), and obtaining the effect of the present invention well. Can do. The material having low thermal conductivity preferably has a thermal conductivity of 20 W / (m · K) to 320 W / (m · K) lower than that of the cooled gold. By setting it within the above range, shrinkage defect can be satisfactorily suppressed.

  FIGS. 5A to 5D are perspective views in the case where a material having a lower thermal conductivity than the cooled gold is disposed in the concave shape. Examples of a method for disposing a material having a lower thermal conductivity than cooling gold in the concave shape portion include a method for fitting a material having a low thermal conductivity, a method for applying the material, and the like. As a structure, for example, FIG. 5A is a structure having a concave shape 402 of a round spot facing, and a material having a lower thermal conductivity than that of the cooling gold 401 is disposed therein, and FIG. Has a concave shape 502 of a round left counterbore, and a structure in which a cooled material having a lower thermal conductivity than that of the gold 501 is disposed therein. Further, as shown in FIG. 5C, the structure has a concave shape 602 of a wedge groove, and a cooled material having a lower thermal conductivity than that of the gold 601 is arranged, as shown in FIG. A structure in which the wedge-shaped groove 702 has a concave shape 702 and a material having a lower thermal conductivity than the cooled gold 701 is disposed there.

  As a material having low thermal conductivity, for example, various ceramic powders such as silica, alumina, mullite and the like mixed with ethyl silicate, colloidal silica, and water glass may be applied. There may be. In addition, since it is desirable that the cooling metal can be repeatedly used, a coating material having high wear resistance is more preferable.

  The casting solidification control method of the present invention can be suitably applied to casting of a tire molding die. By applying the casting solidification control method of the present invention, it is possible to cast a tire molding die having no shrinkage defect. As a result, a good quality tire can be manufactured.

  The solidification control method for a casting according to the present invention is characterized in that, in the solidification control method for a casting using a cooling metal, a concave shape is provided on a part or all of the molten metal contact surface of the cooling metal, and the solidification of the molten metal in the concave shape is delayed. In addition, processes such as a casting process can be appropriately performed according to a known method.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Manufacturing method of casting>
In the mold of the type shown in FIG. 6A having the cast iron casting frame 10, the cast iron surface plate 11, the heat insulating sleeve 12, the heat insulating board 13, and the gate 14, the cast iron casting frame 10 and the cast iron surface plate 11 are provided. As a cooling metal, an aluminum alloy ring tire mold ring casting was cast. Cast iron has a thermal conductivity of 33 W / (m · K), a specific heat of 670 J / kg · K, and a density of 7.2 g / cm ³ .

  6B is a half sectional view showing the dimensions of the mold shown in FIG. 6A. The dimensions are D1 = 520 mm, D2 = 600 mm, D3 = 750 mm, D4 = 100 mm, W1 = 30 mm, W2 = 50 mm, W3 = 50 mm, W4 = 50 mm, H1 = 180 mm, H2 = 200 mm.

The aluminum alloy used is AC4C (Si: 7%, Mg: 0.4%, Fe: 0.3%: remaining Al), the preheating temperature of the cast iron casting frame 10 is 280 to 300 ° C, and the cast iron surface plate 11 The preheating temperature was 80 to 100 ° C., and Noritake dipsum G-1 foamed gypsum (dry mold density: 0.7 / cm ³ ) was used as the gypsum mold 15. The casting method was a one-point casting method by gravity casting, and the casting temperature was 680 to 690 ° C. These conditions are summarized in Table 1 below.

Example 1
As shown in FIG. 7, a concave shape 2 with V-grooves having a width of 68 mm, a pitch of 4 mm, and a depth of 2 mm was provided on the inner surface of the cast iron casting frame 10.

(Example 2)
As shown in FIG. 8, a V-groove concave shape 2 a having a width of 68 mm, a pitch of 4 mm, and a depth of 2 mm was provided in the upper part of the inner surface of the cast iron casting frame 10. The embossed concave shape 2b having a pitch of 4 mm and a depth of 2 mm was provided at the lower portion thereof at intervals of 8 mm, and the coating agent 16 was applied. As the coating agent 16, a slurry obtained by mixing colloidal silica with alumina and silica powder was applied to the concave shapes 2a and 2b of the casting frame and dried. The coating agents other than the concave shapes 2a and 2b on the inner surface of the cast iron casting frame 10 were wiped off before drying. The coating agent 16 has a thermal conductivity of 8.4 W / (m · K), a specific heat of 1260 J / kg · K, and a density of 0.2 g / cm ³ .

(Comparative Example 1)
As shown in FIG. 9, no concave shape is provided in the upper part of the inner surface of the cast iron casting frame 10, and no heat insulating material is attached to the inner surface of the cast iron casting frame 10.

(Comparative Example 2)
As shown in FIG. 10, a heat insulating material 9 having a thickness of 3 mm was attached to the upper part of the inner surface of the cast iron casting frame 10 over a width of 70 mm. The heat insulating material 9 has a thermal conductivity of 2.1 W / (m · K), a specific heat of 1050 J / kg · K, and a density of 0.8 g / cm ³ .

  The obtained aluminum alloy ring was visually observed to confirm the occurrence of shrinkage defect. The case where a shrinkage defect that can be visually confirmed occurred was evaluated as x, the case where a fine shrinkage defect that was difficult to visually confirm inside the casting was evaluated as △, and the case where no shrinkage defect occurred on the casting surface and inside was evaluated as ○. . The obtained results are shown in Table 2. Moreover, it was described in the same table also about the possibility of reuse of a cast frame or a heat insulating material.

  From Table 2, it was confirmed that the present invention has a shrinkage defect countermeasure effect equivalent to or higher than that of the prior art.

DESCRIPTION OF SYMBOLS 1, 101, 201, 301, 401, 501, 601, 701 Cooling metal 2, 102, 202, 302, 402, 502, 602, 702 Concave shape 3 Molten metal 4 Cast frame 5 Equivalent solidification time curved surface 6 Hot water 7 Mold 8 Upper mold 9 Thermal insulation material 10 Cast iron casting frame 11 Cast iron surface plate 12 Thermal insulation sleeve 13 Thermal insulation board 14 Cup gate 15 Plaster mold 16 Coating agent

Claims (5)

  A solidification control method for a casting using a cooling metal, wherein a concave shape is provided on a part or all of the molten metal contact surface of the cooling metal, and the solidification of the casting in the concave shape is delayed.   The casting solidification control method according to claim 1, wherein the pitch of the concave shape is 1 to 4 mm, and the depth is 0.5 to 1.0 times the pitch.   The solidification control method for a casting according to claim 1 or 2, wherein a material having a lower thermal conductivity than the cooling metal is disposed in the concave shape.   The method for controlling solidification of a casting according to claim 3, wherein the material having low thermal conductivity has a thermal conductivity of 20 to 320 W / (m · K) lower than that of the cooling metal.   A mold for molding a tire, which is cast using the solidification control method for a casting according to any one of claims 1 to 4.

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