JPS63215337A - Production of core - Google Patents

Abstract

PURPOSE:To easily provide a vent hole over the entire length of a core having an intricate shape to be molded of molding sand and to prevent a product defect which may arise from blowing out of gas by heating the core to burn away resin yarn in parallel with a core grid embedded in the core. CONSTITUTION:The core grid 2 and the resin yarn 3 consisting of a material such as vinyl resin which burns by heating to about 200-300 deg.C in parallel with the core grid are put into the center of the core 1 having the intricate shape and sand is packed into a mold at the time of molding. After the core 1 is removed from the mold, the core is heated to about 250 deg.C in an electric heating furnace, etc. Then, the internal resin yarn 3 is consumed by combustion to form a through-hole 4. The core grid 2 and the resin yarn 3 pass the holding end 1a of the core 1 and the through-hole 4 opens in the end 1a as well. A metallic pipe 9 is erected to a core print 8 provided on the upper part of a master mold 6 at the time of molding the upper casting mold 7 by using the master mold 6 in a metal flask 5. The master mold 6 and the core print 8 are then removed and the lower casting mold 7 ' and the core 1 are combined therewith so that the pipe 9 is communicated with the through hole 4. The gas is then discharged from the pipe 9 end by a suction device 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing cores used in light alloy sand castings in general, and particularly those having complex shapes.

[Conventional technology]

If the core has a complex shape and is surrounded by the molten metal, there is no place for the gas generated from the core to escape and it may blow out into the molten metal, causing product defects. Therefore, in order to prevent such gas from blowing out into the molten metal, a hole was drilled into the core, and this hole was communicated with a hole leading to the outside of the mold, allowing it to communicate with the outside air.

[Problem that the invention seeks to solve]

However, with this conventional technique of drilling holes into the core, it is not possible to drill holes throughout the core if the shape of the core is complex. As a result, the gas cannot completely escape from the mold.

Particularly, when a large amount of gas is generated from the core mold, a large amount of gas blows out into the molten metal, resulting in product defects.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a core, which eliminates the disadvantages of the conventional example and allows holes for gas insertion to be easily provided throughout the entire length of the core, even if the core has a complex shape. It is in.

[Means for solving problems]

In order to achieve the above object, the present invention embeds resin threads in advance parallel to the core metal in a complex-shaped core made of foundry sand, and heats the core to burn off the resin system. The gist of this is to form a through hole for degassing inside the core by doing so.

[Effect]

According to the present invention, since holes are not formed by drilling or the like from the outside, even if the core has a complicated shape,
Holes can be formed freely along its entire length. By providing complete holes in the core in this way, the gas generated from the core can completely escape to the outside of the mold.

〔Example〕

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

FIG. 1 is a partially cutaway front view showing the method for manufacturing a core according to the present invention, and FIG. 2 is a longitudinal sectional side view of the same. The core 1 uses foundry sand as a molding material.

This core 1 has a complicated shape, but during molding, the first
As shown in FIGS. 3 and 3, a core bar 2 and a resin thread 3 made of a material such as vinyl that burns when heated at about 200" to 300 DEG C. are placed in the center of the core 1 and parallel to it, and filled with sand. After the core 1 in which the metal core 2 and the resin thread 3 have been embedded in advance is removed from the mold during molding, it is heated to about 250° C. in, for example, an electric heating furnace.

Then, when the core 1 is heated, the resin thread 3 inside burns and disappears, and the through hole 4 is formed afterwards.

The core metal 2 and the resin thread 3 are held at the holding end 1a of the core 1.
The formed through hole 4 also opens at the end portion 1a.

Next, how to use the core 1 having such a through hole 4 will be explained.

As shown in FIG. 5, when molding the upper mold 7 using the main mold 6 in the metal frame 5, a core 8 is provided on the upper part of the main mold 6,
A metal pipe 9 is erected on this booklet 8 and its end is made to protrude outside the metal frame 5.

When the main mold 6 and the book block 8 are removed and the lower mold 7' and the core 1 are combined, the end 1a of the core 1 fits into the space where the book block 8 was, as shown in FIG. As shown in FIG. 2, the pipe 9 communicates with the through hole 4 at the center of the core 1.

If a suction device 10 is connected to the end of the pipe 9 and activated at the same time as casting starts, the gas generated from the core 1 will be forced through the route from the through hole 4 to the pipe 9 to the suction device 10. It escapes from the mold and is released into the atmosphere.

Note that the suction force of the suction device 10 may be such that a negative pressure sufficient to allow gas to flow out of the through hole 4 of the core 1 is sufficient.

〔Effect of the invention〕

As described above, the core manufacturing method of the present invention allows a through hole for degassing to be easily provided in the center of the core even if the core has a complex shape. In this way, a core having the desired through-holes can be obtained, and the gas generated from the core can be completely exhausted out of the mold using the through-holes.
To obtain a core in which there is no risk of gas blowing out into the molten product and resulting in a defective product even if the amount of gas generated is large.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing one step of the method for manufacturing a core of the present invention, FIG. 2 is a vertical side view of the same, and FIG. 3 is a partially cutaway front view of the completed core. FIG. 4 is a longitudinal sectional side view of the same as above, FIG. 5 is a longitudinal sectional front view of a mold using the core manufactured by the method of the present invention, and FIG. 6 is a longitudinal sectional front view showing the state in which the core manufactured by the method of the invention is used. It is a diagram. 1... Core 1a... End 2... Core metal 3... Resin thread 4... Through hole 5... Metal frame
6... Main mold 7.7'... Mold 8... Booklet 9... Pipe 10... Suction device applicant
Kobe Steel, Ltd. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] Resin threads are embedded in advance in parallel to the core metal in a complex-shaped core made of foundry sand, and the core is heated to burn and eliminate the resin threads to release gas inside the core. A method for manufacturing a core characterized by forming a through hole.