JPS63256255A - Insert core for pressure casting - Google Patents

Abstract

PURPOSE:To permit good casting without causing the failure of a core at the time of casting and to permit extremely easy removal of the core after the casting by constituting the core of a low melting alloy and covering the surface thereof with heat insulation. CONSTITUTION:The insert core 1 for pressure casting is constituted of the core body 2 made of the low melting alloy and the heat insulation covering 3. Any low melting alloy which has the m.p. lower than the temp. of the molten metal and sufficiently withstands the heat of the molten metal transmitted through the heat insulation covering is usable. A heat insulating material which has a high heat insulating effect, withstands the high temp. of the molten metal and does not adversely affect the product, for example, soot is adequate as the material of the covering 3. Even the product having an undercut shape and cavity shape has good run and the operation for removing the core is facilitated according to this insert core for pressure casting.

Description

[Detailed Description of the Invention] C. Industrial Application Field] The present invention relates to a placed core for pressure casting, particularly for use in forming an undercut shape or a hollow shape during pressure casting such as die casting. The present invention relates to a suitable pressure casting core.

[Prior Art] In general, when manufacturing various products by a casting method, a die-casting method is widely used as a pressure casting method due to its advantages in terms of improved productivity and the like. By the way, when manufacturing castings with complex cavities or undercuts in part of the product shape using the die casting method, it is not possible to use a drawn core as the core, and instead, a drawn core with good collapsibility is used. A sand core is used.

BACKGROUND ART Conventionally, as a collapsible sand core that forms an undercut portion or a cavity in a casting, a sand core made of molding sand hardened with a phenol resin or the like is generally used.

[Problems to be Solved by the Invention] This sand core is required to simultaneously have the contradictory functions of withstanding casting pressure and having good disintegration properties after casting. Collapsible sand cores do not have sufficient collapsibility to provide strength to withstand casting pressure, and if the core is particularly thick, it may be difficult to disintegrate it using vibration or sandblasting. , which was extremely time consuming and caused a decrease in productivity.

[Means for solving the problems] The pressure casting core of the present invention is made of a low melting point metal,
Moreover, the surface thereof is coated with a heat insulating coating.

[Function] The pressure casting core of the present invention is composed of a low melting point metal,
In addition, since its surface is coated with heat insulation, it can sufficiently withstand the casting pressure and the heat of the molten metal during casting, and after casting, the metal of the core can be easily melted and removed by heating from the outside.

In addition, the heat-insulating coating on the surface forms a heat-insulating layer between the core sand and the molten metal during casting. 8 It also works to prevent the temperature from dropping during thirst and improve the recovery from thirst.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the pressure casting core of the present invention.

As shown in the figure, the pressure casting core 1 of the present invention is composed of a core body 2 made of a low melting point metal and a heat insulating coating film 3.

The core body 2 may be composed of an ingot of a low melting point metal or alloy, but may be made of a low melting point metal or alloy and a ceramic 1a.
It may be configured by FRM with ia.

The low melting point metal or alloy is not particularly limited as long as it has a melting point lower than the temperature of the molten metal to be cast and can sufficiently withstand the heat of the molten metal transmitted through the heat insulating coating, but for example, For the core used for casting An or A1 alloy, Pb or an alloy is preferable.
It is difficult to wet the l1 or Aj2 alloy, and even if -PB were to mix into the molten metal during casting, it would not affect the casting because it would not alloy with AIl. In order to prevent this, a cooling means such as a water cooling pipe may be provided in the core body 2.

The ceramic fiber used in FRM is A11.
Examples include 20s-3i 02 type fibers and 5i-Ti-C-0 type fibers.

Core body 2 made of such a low melting point metal or alloy
The heat insulating material for the heat insulating coating l1j3 to be formed is not particularly limited as long as it has a high heat insulating effect, has heat resistance to withstand the high temperature of the molten metal, and does not have a negative effect on the product. ) is preferred. Also, for example, A1
Ceramic fibers such as 10s-3i 02 fibers may be attached using a suitable binder.

The coating layer of such a heat insulating material is provided on at least the surface of the core that may come into contact with the molten metal, and the thickness of the coating layer is:
It is determined as appropriate depending on the size, shape, etc. of the core, within a range that provides sufficient heat insulation and does not adversely affect costs or casting operations.

The core of the present invention can be manufactured by molding a low melting point metal or alloy together with ceramic fibers as necessary, or by casting a ceramic fiber molded body with a low melting point metal or alloy. After manufacturing, the core body can be easily manufactured by applying a mold release agent to the surface of the core body as necessary, and then forming a heat insulating coating film.

When coating soot as a heat-insulating coating, for example, a gas that generates a large amount of soot through combustion, such as acetylene gas, is injected together with a combustion auxiliary gas such as air using an injection nozzle toward the core surface. can be easily formed by adhering soot generated by gas combustion to the surface of the core. In this case, by adjusting the supply amount of the combustion auxiliary gas such as air, the amount of soot attached can be adjusted and a uniform coating film can be formed.

Although FIG. 1 shows a solid core body 2,
In the present invention, the core body 2 may be hollow as shown in FIG.

An experimental example will be explained below.

Experimental Example 1 PB and St-Ti-C-0 ceramics 1lllfa (product name TYRANNOFIBE
R) FRM is molded, and TiO is applied as a mold release agent to the surface of the FRM.
2 powder was applied, and acetylene was generated by gas combustion and applied thereon as a heat insulating agent.

The core obtained in this way was set in a mold, and the aluminum alloy JIS ADC12 was heated to a molten metal holding temperature of 68.
Die casting was carried out under the conditions of 0°C and a casting pressure of 400 kg/crn''.

After casting, the sprue was cut and the core was kept at 500°C in a furnace, and the core was completely melted and could be easily removed from the product. Further, when the product was cut and a cross section was observed, there was no abnormality in the undercut shape, and it was found to be completely formed.

[Effects of the Invention] As detailed above, the pressure casting core of the present invention is made of a low melting point metal, and its surface is coated with heat insulation, and the core is not heated during casting. Good casting can be performed without causing damage, and the core can be removed extremely easily after casting. Furthermore, the heat insulating coating layer forms a heat insulating layer between the molten metal and the core sand during casting, which prevents the core from lowering the temperature of the molten metal and improves the running of the molten metal.

Therefore, according to the pressure casting core of the present invention, even products with complex shapes such as undercut shapes and hollow shapes can be manufactured extremely efficiently with good runability. Moreover, the work of removing the core after casting is greatly simplified, and production efficiency is significantly improved.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing one embodiment of a pressure casting core according to the present invention. 1... Placed core, 2... Core body, 3... Heat insulating coating film.

Claims (4)

[Claims] (1) A pressure casting core made of a low melting point metal and having a heat insulating coating on its surface. (2) The pressure casting core according to claim 1, wherein the low melting point metal is FRM with ceramic fiber. (3) The pressure casting core according to claim 1 or 2, wherein the low melting point metal is Pb or a Pb alloy. (4) The pressure casting core according to any one of claims 1 to 3, wherein the heat insulating coating is soot.