JPS649899B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding green sand cores of complex shapes.

From the viewpoints of foundry sand management, post-processing of molds, and circulation of foundry sand, it is desirable that the core be molded using the same green sand as the main mold. Although attempts have been made to do so,
Green sand has poor fluidity and filling properties, making it difficult to mold cores with complex shapes.

The present invention has been made in view of the above circumstances, and embodiments of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, a vertically split core has a horizontally T-shaped cavity 1, and the upper end 2, lower end 3, and right end 4 of the cavity 1 reach the upper surface, lower surface, and right side surface, respectively. Green sand S is introduced into the cavity 1 of the box 5 by blowing with compressed air, charging by gravity, or charging while giving vibration to the core box 5.
Then, from the upper end 2, lower end 3, and right end 4, a rod member 6 whose tip is approximately in the shape of an inverted cone,
Insert 7 and 8 simultaneously or sequentially to make green sand S.
is compressed and hardened. In this case, when the rod members 6, 7, and 8 fill the green sand S into the cavity 1 by blowing, the total volume of the portions inserted into the cavity 1 is 10 to 10% of the volume of the cavity 1. It is desirable that the amount is 30%, and when the sieving method is used, it is desirable that the amount is 25 to 50%. If the lower limit of this range is not reached, the green sand S will not be able to harden to every corner, and if the upper limit is exceeded, the green sand S will be compressed too much and the molded core will have reduced air permeability and will collapse. Sexuality becomes worse. After the green sand S is compressed and hardened in this manner, the rod members 6, 7, and 8 are pulled out and the core box 5 is opened to obtain a hollow core. This core is compression hardened from the surface to the inside and has the necessary strength and surface stability, so it is easy to handle, and since it is hollow, it has good degassing and collapsibility.

In the above embodiment, the green sand S is compressed and hardened simply by inserting the rod members 6, 7, and 8, but the following method may be used. That is, as shown in FIGS. 2 and 3, auxiliary cavities 9 and 1 whose internal dimensions are the same as those of the upper end 2, lower end 3, and right end 4 are provided on the upper surface, lower surface, and right side surface of the core box 5.
Auxiliary members 12, 13, 14 having 0,11,
The auxiliary cavities 9, 10, 11 are connected to the upper end 2, the lower end 3,
These cavities 1, 9, 10, and 11 are filled with green sand S in the same manner as in the previous embodiment, and then the rod members 15 to 20 are inserted as in the previous embodiment. Raw sand S in cavity 1
while compressing the pressing members 21, 22, 23 and the pressing parts 18a, 1 of the rod members 18, 19, 20.
9a, 20a are fitted into the auxiliary cavities 9, 10, 11 of the auxiliary members 12, 13, 14.
Push green sand S in 0 and 11 into cavity 1.

The core formed in this manner also has extremely high hardness at the upper end, lower end, and right end. Furthermore, the rod members 6, 7, 8, 15, 16, 17, 18, 1
Although 9 and 20 are straight, they may also be formed into a stepped or tapered shape that corresponds to the cavity of the core box.

As is clear from the above description, the present invention compresses and hardens the green sand by inserting rod members of a predetermined thickness from at least two directions with different center lines into the cavity of a core box filled with green sand. Because of this, the molded core has good shape retention and is convenient to handle.Moreover, since it is hollow, it has very good disintegration after pouring, and has good gas release. Coupled with the advantage that cores can be provided at low cost because no labor is required for molding, this method will greatly contribute to the development of the industry as a core molding method that solves the problems of the conventional green sand core molding method. There is something big.

[Brief explanation of drawings]

1 to 3 are longitudinal sectional views of various embodiments. 1: Hollow, 5: Core box, 6-8: Rod member, 9-
11: Auxiliary cavity, 12-14: Auxiliary member, 15-
17: Bar member, 18-20: Bar member, 18a-2
0a: Pressing part, 21-23: Pressing member.

Claims (1)

[Claims] 1. After filling green sand into the cavity of a core box having a cavity opening on at least three sides, a rod member whose tip end is approximately in the shape of an inverted cone is inserted from each opening. A method for making a core, characterized in that the green sand is compressed and hardened by 10 to 50%, and then the rod member is extracted from the hardened green sand. 2. After filling green sand into the cavity of a core box having a cavity opening on at least three sides, from the opening,
A rod member whose tip end is approximately in the shape of an inverted cone is inserted to compress the green sand by 10 to 50%, and the green sand is pushed in from the insertion position of the rod member via a pressing means to compress and harden the entire green sand. . A method for making a core mold, characterized in that the rod member and the pressing means are then separated from the hardened green sand.