JPH071467A - Method and apparatus for removing metal core - Google Patents

Abstract

PURPOSE:To enhance the recovery rate of a molten metal obtained by melting a core and to suppress the air passing resistance of an obtained suction manifold low. CONSTITUTION:A suction manifold 2 including a core 1 to be melted and removed is positioned within the coil part 3 of the high frequency induction heating coil immersed in high temp. oil 7. In this state, a high frequency current is allowed to flow to the coil part 3 to melt and remove the core 1. At this time, ultrasonic vibration is applied to the oil 7 by ultrasonic vibrators 10, 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The method and apparatus for removing a metal core according to the present invention uses a metal core to manufacture an intake manifold made of synthetic resin for sending air into a cylinder of an automobile engine, for example. After that, the metal core is heated and melted to be used for removal.

[0002]

2. Description of the Related Art Conventionally, an intake manifold for sending air into a cylinder of an automobile engine has been manufactured by die-cast molding of an aluminum alloy.
In order to reduce the weight of automobiles, for example, JP-A-58-8205
As disclosed in Japanese Patent Publication No. 9, the intake manifold is manufactured by injection molding of synthetic resin.

On the other hand, since the intake manifold is hollow and its outer surface shape and inner surface shape are bent in a three-dimensional direction, it cannot be manufactured by an injection molding apparatus having a simple split mold which is usually used. . Therefore, when an intake manifold having a shape bent in the three-dimensional direction is manufactured by injection molding of synthetic resin, it is performed as follows.

That is, a core made of a low melting point metal (eg, melting point 150 ° C.) such as an alloy of Bi and Sn or an alloy of Bi, Sn and Pb is prepared prior to injection molding. To do. The outer surface shape of the core is made to match the inner surface shape of the synthetic resin intake manifold to be manufactured.

Then, with the core set in a molding die having an inner surface shape that matches the outer surface shape of the intake manifold to be manufactured, a synthetic resin having a melting point higher than that of the low melting point metal is placed in the molding die. For example, nylon 66 containing glass fibers (for example, melting point of 240 degrees or more) is injected and solidified in the space (cavity) between the inner surface of the mold and the outer surface of the core.

Although the temperature of the molten synthetic resin injected into the cavity is higher than the melting point of the low melting point metal constituting the core, it immediately contacts the core having a large heat capacity and good heat transfer property. Since the temperature lowers, a part of the core will not melt with the injection of the molten synthetic resin.

After the synthetic resin is poured into the mold and solidified, the mold is opened and the intake manifold is taken out. Since the intake manifold is bent in the three-dimensional direction, the core has the intake air. It is still contained in the manifold. Therefore, this core is melted and removed by high-frequency induction heating using a device as shown in FIG.

That is, the intake manifold 2 containing the core 1 taken out from the molding die is disclosed in Japanese Patent Laid-Open No. 4-282207.
Coil part 3 of high-frequency induction heating device as shown in Japanese Patent Publication
A high-frequency current is passed through the coil portion 3 in a state of being positioned inside. As a result, the alloy such as Bi—Sn forming the core 1 is heated to melt the core 1. The coil portion 3 is composed of a copper tube 4, and cooling water can freely flow inside. During operation of the high frequency induction heating device, cooling water is caused to flow in the copper tube 4 forming the coil portion 3 to prevent the temperature rise of the coil portion 3 itself.

The core is melted and removed by using the high-frequency induction heating device in the air, and the core 1 is enclosed in polyhydric alcohol such as polyethylene glycol or oil such as mineral oil. It is performed even when the coil portion 3 is immersed. The oil is heated to, for example, about 160 to 180 ° C. and has a high temperature. Like this, core 1
The melting and removing of the core is performed in high temperature oil by setting the non-oxidizing environment around the core 1 to prevent the molten metal formed by melting the core 1 from being oxidized and reusable This is to improve the metal recovery rate and the melting efficiency of the core 1.

[0010]

By the way, when the core 1 is melted and removed by using the high-frequency induction heating apparatus described above, there are the following problems to be solved.

That is, when the above-mentioned core 1 is melted and removed in the atmosphere, as shown in FIG. 3, a thin film-like residue 5 in which scales are inverted by a molten metal formed by melting the core 1 is formed. ,
5 occurs inside the synthetic resin intake manifold 2.
Even when the core 1 is melted and removed in high-temperature oil, a granular or lumpy residue due to the molten metal is left inside one intake manifold 2 inside the synthetic resin intake manifold 2. Occurrence of about 0.02-0.2g is unavoidable.

The molten metal obtained by melting the core 1 is recovered and remanufactured as the core 1 again. Therefore, the residues 5 and 5 as described above may occur in the synthetic resin intake manifold 2. , Worsens the recovery rate of molten metal. Also, the above residue 5,
The presence of 5 increases the ventilation resistance of the synthetic resin intake manifold 2 and is not preferable. The method and apparatus for removing a metal core of the present invention have been conceived in view of the above circumstances.

[0013]

Among the methods and apparatuses for removing a metal core of the present invention, the method for removing a metal core is the same as the above-mentioned conventional removal method. After injection molding a tubular member made of synthetic resin around the core, the tubular member and the metal core are placed inside the coil portion of the high-frequency induction heating coil, and are heated together with the coil portion at a high temperature. The metal core is melted and removed from the inside of the tubular member by immersing it in oil and energizing the high frequency induction heating coil.

Particularly, in the method for removing a metal core of the present invention, ultrasonic vibration is applied to the oil when the metal core is melted by energizing the high frequency induction heating coil. It is characterized by item 1). Further, instead of applying ultrasonic vibration to the oil, or while applying ultrasonic vibration, the oil is agitated and fluidized (Claim 2), or the tubular member is vibrated (Claim 3). ) Can also be configured.

Further, in the apparatus for removing a metal core according to a fourth aspect, injection molding is performed around a storage tank storing high temperature oil and a metal core made of a low melting point alloy. The synthetic resin tubular member has a coil portion that can be inserted inside, and a high-frequency induction heating coil provided in the storage tank, and an ultrasonic vibration in the storage tank attached to the storage tank. And an ultrasonic transducer for imparting.

[0016]

With the method and apparatus for removing a metal core of the present invention configured as described above, when melting and removing the core, in addition to melting the core by high frequency induction heating and high temperature oil, The ultrasonic vibration applied to the oil in the storage tank separates and removes the molten metal generated by the melting of the core from the inner surface of the tubular member. Therefore, the core is completely melted and removed, and no residue is generated on the inner surface of the tubular member. The same applies to the case where the oil is agitated and fluidized (Claim 2) or the tubular member is vibrated (Claim 3) instead of or together with the ultrasonic vibration. As a result, the recovery rate of the molten metal generated by melting the core is improved, and the inner surface of the tubular member becomes smooth.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the outline of a metal core removing apparatus of the present invention. Inside the storage tank 6, for example, 160 to 1
The oil 7 heated to a temperature of 80 ° C. is stored. This oil 7
As such, polyhydric alcohols such as polyethylene glycol, mineral oil, synthetic oil, vegetable oil and the like can be used. To the bottom of the storage tank 6, one end of a discharge pipe 9 provided with an opening / closing valve 8 in the middle is connected. The discharge pipe 9 is for taking out the molten metal generated by melting the core 1 in order to manufacture the next core 1. Further, ultrasonic transducers 10 and 10 are provided on the inside (or the outer surface) of the storage tank 6,
Ultrasonic vibration can be freely applied to the oil 7 stored in. Further, although not shown in the drawing, a support base for supporting the intake manifold 2 containing the core 1 to be melted is provided at the center bottom of the storage tank 6.

The storage tank 6 is provided inside the closed tank 11. The closed tank 11 has a lid device (not shown), and the core 1 to be melted by opening the lid device.
The intake manifold 2 containing the above can be fed into the storage tank 6 in the closed tank 11 freely. Further, by closing the lid device, the sealed tank 11 can be sealed. Further, a condenser 12 is provided at the upper end of the closed tank 11, and the oil 7 evaporated when the core 1 is melted and removed is condensed and liquefied to be recovered. The oil 7 condensed and liquefied by the condenser 12 is sent to an oil storage tank (not shown).

Inside the storage tank 6, a coil portion 3 constituting a high-frequency induction heating device is located at an upper portion around the support table. This coil portion 3 is, like the conventional device described above, a copper tube 4 in which cooling water can freely flow inside.
It is composed by. Inside the coil portion 3, the intake manifold 2 supported by the upper surface of the support table and containing the core 1 to be melted can be inserted freely. As described above, as a means for allowing the intake manifold 2 to be inserted inside the coil part 3, for example, the coil part 3 can be moved up and down and the coil part 3 is lifted to the upper surface of the support base. Means for lowering the coil portion 3 after supporting the manifold 2 can be considered.

The operation of melting and removing the metal core 1 made of a low melting point alloy such as Bi-Sn alloy by using the metal core removing apparatus of the present invention configured as described above , As follows.

First, the lid device of the closed tank 11 is opened, and the intake manifold 2 containing the core 1 to be melted is supported on the upper surface of the support table through this opening to form a high frequency induction heating device. It is positioned inside the coil portion 3 to be used. When the intake manifold 2 is supported on the upper surface of the support and is inserted into the coil portion 3, the lid device is closed and the closed tank 11 is closed.

Then, a high-frequency current is passed through the coil portion 3 to heat the core 1. This heating in high temperature oil is the same as in the case of the conventional example described above. By heating the core 1, the core 1 is melted and flows into the oil 7 from the inside of the intake manifold 2.

If the core 1 is melted by about 90%,
While continuing high-frequency induction heating, the above ultrasonic transducer 1
Electricity is applied to 0 and 10 to apply vibration to the oil 7 in the storage tank 6. The duration of application of this ultrasonic vibration varies depending on the size and shape of the core 1 to be removed, but is, for example, 5 minutes or more when an intake manifold for a passenger car engine is manufactured.

As described above, by vibrating the oil 7 while performing high frequency induction heating in the oil 7 at high temperature, the core 1 in the intake manifold 2 is almost completely melted and removed. The above-mentioned residue does not occur.

The molten metal formed by melting the core 1 flows out from the inside of the intake manifold 2 into the oil 7 in the storage tank 6,
Collect at the bottom of the storage tank 6. This molten metal is discharged from the discharge pipe 9 by opening the open / close valve 7 after the completion of the melting and removing work of the core 1.
Take out through. Also, in melting and removing the core 1,
The oil 7 in the storage tank 6 gradually evaporates. Such evaporated oil 7 is collected by the condenser 12, condensed and liquefied by the condenser 12, and then sent to an oil storage tank (not shown).

As described above, in the present invention, in addition to the conventional high-frequency induction heating in high-temperature oil, ultrasonic vibration is added, and therefore the residue generated in the intake manifold 2 5 (Fig. 3) can be completely removed. Therefore, it is possible to recover almost all the molten metal produced by melting the core 1. Moreover, since the core 1 is melted in the oil 7, the molten metal is not oxidized. Further, since the residue 5 does not occur in the intake manifold 2, the ventilation resistance of the intake manifold 2 can be suppressed low.

In place of or in addition to applying ultrasonic vibration to the oil 7 by the ultrasonic vibrators 10 and 10, the oil 7 is agitated and fluidized, or the intake air is sucked. The same effect can be obtained by vibrating the manifold 2 itself. The oil 7 can be agitated and fluidized by, for example, providing an agitating blade constituting an agitating device in the oil 7 and rotating the agitating blade. or,
The intake manifold 2 itself can be vibrated by, for example, oscillating the support table.

In the above-described embodiments, the present invention has been described as applied to the case of manufacturing an intake manifold for an automobile engine, but the present invention is not limited to this. It can be widely applied to the production of other synthetic resin tubular members using a core made of a low melting point alloy.

[0029]

Since the method and apparatus for removing a metal core of the present invention are constructed and operate as described above, after the core is melted and removed, it is placed inside a tubular member made of synthetic resin such as an intake manifold. No residue is produced, and the molten metal formed by melting the core is almost completely removed. Moreover, the molten metal is not oxidized. Therefore, not only the recovery rate of the molten metal is improved, but also the property of the inner surface of the obtained tubular member is improved.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing the present invention.

FIG. 2 is a schematic perspective view showing a conventional example.

FIG. 3 is a view of an intake manifold on which a residue is attached, viewed from the end face side.

[Explanation of symbols]

 1 Core 2 Intake Manifold 3 Coil Part 4 Copper Tube 5 Residue 6 Reservoir 7 Oil 8 Open / Close Valve 9 Discharge Pipe 10 Ultrasonic Transducer 11 Sealed Tank 12 Condenser

Claims (4)

[Claims] 1. A synthetic resin tubular member is injection-molded around a metallic core made of a low melting point alloy, and the tubular member and metallic core are then placed inside a coil portion of a high frequency induction heating coil. The metal core is melted and removed from the inside of the tubular member by immersing it in high-temperature oil together with the coil portion and energizing the high-frequency induction heating coil in a state of being positioned at A method for removing a core made of metal, characterized in that ultrasonic vibration is applied to the oil when the core made of metal is melted by energizing the high frequency induction heating coil. . 2. The metal according to claim 1, wherein when the metal core is melted, the oil is agitated and flown instead of or while the ultrasonic vibration is applied to the oil. How to remove the core. 3. The metal core according to claim 1, wherein when the metal core is melted, the tubular member is vibrated instead of applying ultrasonic vibration to the oil or while applying ultrasonic vibration. How to remove a child. 4. A storage tank for storing high-temperature oil, and a tubular member made of synthetic resin injection-molded around a metal core made of a low melting point alloy, and a coil portion insertable inside the tubular member. A device for removing a metal core, comprising: a high-frequency induction heating coil provided in the storage tank; and an ultrasonic vibrator attached to the storage tank to apply ultrasonic vibration to the oil.