JP2002225039A - Method for removing metal core and apparatus adapted thereto - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for removing a metal core, not requiring a washing process or the like for a molded article and capable of easily obtaining a desired molded article by a lost core molding method. SOLUTION: The molded article M, in which the metal core C comprising a metal with a low melting point is enclosed, is arranged in a booth 11 held to an atmosphere, which is heated to a state capable of liquating out the metal with the low melting point, along with an induction heater 12 and the metal with the low melting point is melted and removed while supplying hot air to the surface of the molded article M from a hot air nozzle 13 so as to prevent the adhesion of the molten metal with the low melting point to the surface of the molded article M.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a metal core and an apparatus therefor, and is particularly useful when applied to a step of eluting a low melting point metal core in a lost core molding method.

[0002]

2. Description of the Related Art A lost core molding method using a metal core is known as a method for injection molding a molded article such as plastic. In this case, the metal core is formed of a low-melting-point metal. For example, after a plastic molded product is molded in a state in which the metal core is wrapped by injection molding, the plastic core is melted and removed from the molded product. That is, a metal core having a low melting point integrated with a molded article is immersed in a liquid heating medium, and heated and melted by the liquid heating medium and induction heating means. Also,
A method of heating and melting a metal core in air (normal temperature) using, for example, an induction heating device is also used.

[0003] Among the conventional techniques relating to such heat melting,
An apparatus for immersing a metal core in a liquid heating medium for removal will be described with reference to FIG. 2 together with a removal method using the same. As shown in FIG. 2A, the molded article M before the metal core C is melted and removed is injection-molded so as to enclose the metal core C forming the hollow portion. It is immersed in the liquid heating medium 2 in the heating oil tank 1 shown in b). Here, the heating oil tank 1 is provided with a heating means (not shown) on the outer wall and has a heat retaining property, and has a temperature slightly higher than the melting point of the metal core C by the heating means on the outer wall. Liquid heating medium 2 such as polyethylene glycol
And an induction heating coil 4 connected to a high-frequency power supply 3 outside the tank is provided as induction heating means. The induction heating coil 4 is fixed by a holder (not shown) with the central axis being in the vertical direction. In the vicinity of the bottom of the side wall of the heating oil tank 1, a pipe 5 penetrates watertightly. The pipe 5 has a nozzle 6 extending obliquely upward at a tip end extending below the induction heating coil 4 and a gas supply source (not shown) such as air or nitrogen gas installed outside the tank.
Connected to In FIG. 2B, reference symbol A denotes a core metal that has been melted and collected at the bottom of the heating oil tank 1.

[0004] In removing the metal core C from the molded product M, the molded product M is heated by a liquid heating method such that the inside of the induction heating coil 4 and one opening end face the nozzle 6 at a predetermined interval. Immerse in the medium 2. At this time, the nozzle 6 is at a position deviated from immediately below the opening end so that the falling core metal does not fall. And
The metal core C is heated by the heat of the liquid heating medium 2 and the electromagnetic induction effect due to energization of the induction heating coil 4, and the metal core C is melted out of the molded product M. Next, when most of the metal core C is melted and removed, a gas is injected from the nozzle 6 to the molded article M while performing the above-described heating.

[0005] This gas becomes bubbles and passes through the inside of the molded article M and floats. Thereby, in the heating oil tank 1, the liquid heating medium 2 is directed upward in the molded article M,
Around that time, a downward flow of the liquid heating medium 2 is generated, and the liquid heating medium 2 is forced to flow in the molded article M. Thus, the core metal a in the form of a thin film remaining on the inner surface of the molded article M is efficiently heated and melted by the flowing liquid heating medium 2, and is quickly removed by the flow. .

[0006]

In the method of removing the metal core C using the liquid heating medium as described above, the metal core C integrated with the molded article M is immersed in the liquid heating medium 2 and melted. Since it is removed, the liquid heating medium adheres to the surface of the molded article M, and it is necessary to clean and remove the liquid heating medium. For this reason, the number of removal steps increases by one, and the steps become more complicated. Further, when the metal core is heated and melted by using the induction heating device, there arises a problem that the molten metal adheres again to the surface of the molded product.

In view of the above prior art, the present invention provides a method and an apparatus for removing a metal core which can easily obtain a desired molded article by a lost core molding method without requiring a step of washing the molded article. The purpose is to provide.

The structure of the present invention that achieves the above object has the following features.

1) In a method of removing a metal core in which a molded product enclosing a metal core made of a low melting point metal is melted and removed by induction heating, the molding enclosing the metal core is formed. The product is heated in an atmosphere where the low-melting-point metal can be eluted, and the low-melting-point metal is supplied while supplying hot air to the surface of the molded product to prevent the molten low-melting-point metal from adhering to the surface of the molded product. Molten removal.

2) In a metal core removing device for disposing a molded product enclosing a metal core made of a low melting point metal in an induction heating device and melting and removing the low melting point metal, an induction heating device A booth that stores therein a molded product wrapping the metal core, and a hot air supply unit that supplies hot air so as to maintain a temperature inside the booth at a constant temperature at which a low melting point metal can be eluted, A hot air supply nozzle for supplying hot air flowing downward from above toward the surface of the molded article;

[0011]

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

FIG. 1 is an explanatory view conceptually showing an apparatus for removing a metal core according to an embodiment of the present invention. As shown in the figure, a molded product M enclosing a metal core C made of a low-melting metal is placed inside the booth 11 by an induction heating device 12.
And a hot air nozzle 13 for cleaning the metal. Here, the induction heating device 12 is disposed so as to surround the molded product M, and heats and melts the metal core M. The hot air nozzle 13 is provided with an induction heating device 12 so that the low-melting point metal can blow hot air flowing downward from above toward the surface of the molded product M so that the low-melting metal does not adhere to the surface of the molded product M. A plurality (six in the figure) is disposed in the booth 11 while keeping appropriate vertical intervals along the vertical direction.

A circulating hot air is supplied into the booth 11 and maintained at a constant temperature. As a result, the atmosphere is such that the low melting point metal can be melted. The hot air is obtained by heating the gas circulating between the booth 11 and the booth 11 via the pipe 15 by the driving of the blower motor 14 by the heating device 16. Further, the temperature is kept constant by controlling the heat input to the gas by the heating device 16.

Here, the inside of the booth 11 may be maintained at a temperature equal to or higher than the melting point of the low melting point metal as described above. In the case of °, the temperature in the booth 11 may be set to 200 °.

According to the present embodiment, the inside of the booth 11 is maintained at a temperature higher than the melting point of the low melting point metal. fall into. At this time, hot air is blown from the hot air nozzle 13 toward the surface of the molded article M. Therefore, the molten low melting point metal does not adhere to the surface of the molded article M.

[0016]

As described in detail with the above embodiments, according to the present invention, the metal core of the low melting point metal is melted and removed, and the hot air is blown toward the molded product. The molten metal can be prevented from adhering to the surface of the molded product, and the metal core can be satisfactorily melted and removed. At this time, the liquid heating medium is not used for melting the metal core as in the prior art, so that the liquid heating medium does not adhere to the surface of the molded product, and therefore, the liquid heating medium is washed and cleaned.
The step of removing can be omitted, and the operation can be shortened.

[Brief description of the drawings]

FIG. 1 is an explanatory view conceptually showing an apparatus for removing a metal core according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing a conventional technique, wherein FIG. 2A is an explanatory view showing a work of a metal core removing device, and FIG. 2B is an explanatory diagram conceptually showing a metal core removing device.

[Explanation of symbols]

 11 Booth 12 Induction Heating Device 13 Hot Air Nozzle 14 Blower Motor 15 Pipeline 16 Heating Device M Molded Product C Core

Claims (2)

[Claims] 1. A method for removing a metal core, wherein a molded product enclosing a metal core made of a low-melting metal is induction-heated to melt and remove the low-melting metal, the molding comprising the metal core. The product is heated in an atmosphere where the low-melting-point metal can be eluted, and the low-melting-point metal is supplied while supplying hot air to the surface of the molded product to prevent the molten low-melting-point metal from adhering to the surface of the molded product. A method for removing a metal core, which comprises melting and removing the core. 2. A metal core removing device for arranging a molded product enclosing a metal core made of a low melting point metal in an induction heating device and melting and removing the low melting point metal. A booth for accommodating a molded product wrapping the metal core therein, and a hot air supply means for supplying hot air so as to maintain a temperature inside the booth at a constant temperature at which a low melting point metal can be eluted, A metal core removing device, comprising: a hot air supply nozzle for supplying hot air flowing downward from above toward a surface of a molded product.