JPH0380577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a casting method for manufacturing castings having through holes.

Conventional technology Conventionally, in order to cast a casting having a through hole, a punching pin is used in mold casting, a core is used in green sand casting, etc. In either case, a material is used in the part of the casting where the through hole is to be formed. The through hole was formed by placing materials and casting out the portion where the materials were placed.

However, such conventional methods have the following problems. In other words, in the case of mold casting, there is not only the problem of damage such as galling or bending of the casting pin when demolding the product, and deformation and cracking of the product, but also the problem that the tip of the casting pin during casting. There has been a problem in that casting defects such as shrinkage cavities occur due to the formation of heat spots.
Further, in the case of green sand casting, there were problems such as poor dust removal due to poor alignment between the core and the outer mold, and the problem that the cost required for molding the core could not be ignored.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional circumstances, and it is an object of the present invention to provide a draft casting method that can easily and inexpensively produce sound draft castings.

Structure of the Invention In other words, the casting direction of the present invention is such that the lower mold and the upper mold, which are combined with each other to form an outer mold, are each provided with ventilation holes leading to the cavity from outside the system, and the lower mold and the upper mold are combined. Fill the cavity of the outer mold with molten metal, and place the outer mold in such a position that the opening on the side of the lower mold vent cavity is located below the opening on the side of the upper mold vent cavity in the direction of gravity. Before the filled molten metal solidifies, gas is continuously blown into the molten metal from the lower mold vent and released from the upper mold vent, so that gas is poured into the molten metal from the lower mold vent into the upper mold. This method is characterized in that a blow-through path is formed that reaches the ventilation hole, and the molten metal in the cavity is solidified in this state, thereby forming the blow-through path into a cast hole.

Embodiments of the invention will be described below with reference to the drawings.

FIG. 1 shows a case in which the invention is implemented for mold casting. The lower mold 2 and upper mold 3 that are combined with each other to form the outer mold 1 are each provided with a lower mold ventilation hole 5 and an upper mold ventilation hole 6 that communicate with the cavity 4 from outside the system. A lower mold ventilation insert 7 such as a sintered vent is provided at the opening on the side of the cavity 4 of 5, and an upper mold ventilation insert 8 is provided at the opening on the cavity 4 side of the upper mold ventilation hole 6. Further, a recording pipe 9 is connected to the lower mold ventilation hole 5, and an exhaust pipe 10 is connected to the upper mold ventilation hole 6. In addition,
The axes of the lower mold ventilation hole 5 and the lower mold ventilation insert 7 and the upper mold ventilation hole 6 and the upper mold ventilation insert 8 are aligned in the same straight line A in the perpendicular direction to the unillustrated mating surfaces of the lower mold 2 and the upper mold 3. It is set up to match.

In the present invention, using such a mold, a casting having through holes is cast in the following manner.

First, lower mold 2 and upper mold 3 are combined to form outer mold 1.
The cavity 4 is filled with molten metal from a ladle or the like (not shown). Next, when the molten metal is completely filled, gas depending on the type of molten metal, such as air or inert gas, is continuously supplied from the air supply pipe 9 toward the cavity 4 through the lower mold vent. 5 and enters the molten metal 11 in the cavity 4 via the lower mold ventilation insert 7, reaches the upper mold ventilation insert 8, and is discharged to the outside through the exhaust pipe 10.
By continuously blowing the gas in this way, a blow-through path 12 is formed in the molten metal from the lower mold ventilation insert 7 to the upper mold ventilation insert 8. Therefore, if this state is maintained for a certain period of time, the molten metal will solidify except for the blow-through path 12, and a cast hole will be formed in the blow-through path 12. In addition,
If the gas supply pressure through the air pipe 9 is increased at the stage when the molten metal at the interface of the blow-through path 12 has formed a solidified layer of a certain thickness, the blow-through path, that is, the inner surface of the cast hole 12 can be forcibly cooled. The cooling efficiency can be further improved by this.

Other embodiments are shown in FIGS. 2 and 3. In this embodiment, a lower mold ventilation hole 4a and an upper mold ventilation hole 5a are formed on a mating surface 12 of a lower mold 2 and an upper mold 3 forming an outer mold 1.
The body is located on a straight line B that is inclined with respect to the vertical direction. Therefore, as shown in Fig. 3, when filling the cavity 4 with molten metal and blowing gas through the lower mold vent 4a, the outer mold 1 is placed in a position such that the direction of the straight line B coincides with the direction of gravity. The present invention can be carried out in the same manner as in the previous embodiment by blowing gas through the lower die vent hole 4a.

Effects of the Invention As described above, according to the present invention, by passing air through the molten metal filled in the cavity, a casting having a casting hole can be cast without using a casting pin or the like. As a result, the inside of the casting hole can be directly forcedly cooled, the bookbinding solidification time can be shortened, productivity can be improved, and a sound casting can be obtained. Furthermore, by changing the size and position of the ventilation insert, the size and position of the cast hole can be easily changed, providing a high degree of freedom. Furthermore, since materials such as casting pins for casting are not used, there is no loss due to galling or bending of these materials, and there are no product defects caused by these, and costs can be reduced.

[Brief explanation of drawings]

Fig. 1 is a partial cross-sectional view of a mold showing the state in which this invention is practiced, Fig. 2 is a cross-sectional view of another mold for carrying out this invention, and Fig. 3 is a partial cross-sectional view of a mold shown in Fig. 2. It is a sectional view showing a state in which the invention is implemented. 1...outer mold, 2...lower mold, 3...upper mold, 4...
Cavity, 5...Lower mold vent, 6...Upper mold vent, 11...Molten metal, 12...Blowout path.

Claims (1)

[Claims] 1. A lower mold and an upper mold that are combined together to form an outer mold are each provided with a ventilation hole leading to the cavity from outside the system, and molten metal is filled into the cavity of the outer mold that combines the lower mold and the upper mold. At the same time, the outer mold is placed in such a position that the opening on the side of the lower mold ventilation hole is located below the opening on the side of the upper mold ventilation hole in the direction of gravity. By continuously blowing gas into the molten metal from the lower mold vent and releasing it from the upper mold vent, a blow-through path is formed in the molten metal from the lower mold vent to the upper mold vent. 1. A cast-out casting method, characterized in that the blow-through path is formed into a cast-out hole by solidifying the molten metal in the cavity.