JPH0938764A - Method for removing resin core and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time for removing resins and to shorten casting cycle time by forcibly heating a resin core by a high-temp. gas after solidification of molten metal to melt or gasify the resin cores, then removing the resin core from a casting. SOLUTION: The gas is sent by a blasting means and is heated to a high temp. by a heater 6. The heated gas is supplied from a gas supply port 7 to the resin core 4. The resin core 4 consists of a copolymer, such as ethyelene, and is forcibly melted or gasified by the high-temp. gas. The melt or gas is discharged from a discharge port 8 to a circulating passage 15 and is separated to the resin and the gas by a filter 14. The resin is recycled as another resin core and the gas is heated again by the heater 6 and is sent to the resin core 4. Since the casting 3 cools rapidly, the resin core 4 is removed and thereafter, the gas which is not heated is put from a gas source into the circulating passage 15 and the cooling is executed after the temp. of the gas supplied to the molds 1, 2 is lowered. As a result, the casting cycle time is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing a resin core from a casting when a metal casting is cast using a resin core (hereinafter referred to as a resin core). .

[0002]

2. Description of the Related Art A method for casting a metal (for example, aluminum alloy) casting using a resin core is as follows.
It is known from Japanese Patent Application No. 6-91345. In the conventional casting method using a resin core, the resin core is made of a thermoplastic resin material that is melted or gasified by the residual heat of the cast product. The core body portion is covered with a heat-resistant protective layer such as silicon. After casting, after casting, the core body portion of the core is melted or gasified by residual heat of the cast product to deform and remove the core. In this case, since the core body portion is covered with the heat resistant protective layer of silicon and hermetically sealed, the molten portion on the inner side does not adhere to the cast product.

[0003]

However, the conventional casting method using a resin core has the following problems. Since the residual heat of the cast product is used, the residual heat of the cast product also changes when the mold temperature changes in the early and late stages of continuous casting, and the timing of melting or gasification of the core body of the resin core It becomes difficult to specify the timing of pulling and removing. In addition, since the core has a heat-resistant protective layer of silicon as an outer layer, the timing of melting or gasification of the core body part changes depending on the thickness of the heat-resistant protective layer and the heat conduction characteristics, and the timing of core removal and removal. Becomes difficult to identify. It is an object of the present invention to provide a resin core removing method and device, in which the timing of melting or gasification of the resin core can be easily specified.

[0004]

The present invention to achieve the above object is as follows. (1) After the molten metal is solidified, a high temperature gas is supplied to the resin core to melt or gasify the resin, and the molten or gasified resin is removed to remove the resin core from the casting.
A method for removing a resin core, which comprises steps. (2) The method for removing a resin core according to (1), further including the step of cooling the cast product by lowering the temperature of the gas supplied into the mold after removing the resin core from the cast product. (3) The resin core removal method according to (1), wherein in the resin melting or gasifying step, the gas supply port is moved toward the resin core as the resin melting or gasification progresses. (4) The method for removing a resin core according to (1), wherein a non-oxidizing gas is used as a gas to be supplied. (5) A gas supply port for supplying gas to the resin core, an exhaust port for exhausting the gas touching the resin core and the molten or gasified resin, and a gas from the exhaust port is circulated to the gas supply port. Removal of resin core consisting of a circulation passage, a blowing means provided in the middle of the circulation passage, and a heater provided in a portion of the circulation passage between the gas supply port and the blowing means apparatus. (6) A filter for taking out only the molten resin from the mixture of the gas and the molten resin and discharging the molten resin to the outside of the circulation passage is provided in the portion of the circulation passage between the discharge port and the blower (5). ) A device for removing a resin core as described above. In any of the above methods (1) to (6), since a high temperature gas is supplied to the resin core and it is forcibly melted or gasified, it is not greatly affected by the residual heat of the cast product. , The timing of resin melting or gasification is easily specified.

[0005]

1 to 3 show a resin core removing apparatus according to an embodiment of the present invention. 1 to 3, a resin core 4 made of a thermoplastic resin is supported in molds 1 and 2 (one is a fixed mold and the other is a movable mold). A molten metal mold (for example, an aluminum alloy molten metal) is supplied to a cavity formed between the child 3 and solidified to cast a metal casting 3. After solidification of molten metal, cast product 3 (or cast product 3 and molds 1, 2)
A resin core removing device for removing the resin core from the base is provided, for example, in the skirting part 5.

One end of the resin core removing device is provided close to the resin core 4 (for example, connected to the skirting board 5).
A removal device body (hereinafter, simply referred to as a body) 9, a gas supply port 7 formed in the body 9 and opening toward the resin core 4 to supply a gas to the resin core 4, and a resin medium formed in the body 9 A discharge port 8 that is opened toward the child 4 and discharges the gas touching the resin core 4 and the molten or gasified resin, and a circulation passage 1 that circulates the gas from the discharge port 8 to the gas supply port 7.
5, blower means (for example, a fan) 13 provided in the middle of the circulation passage 15 for sending gas from the exhaust port 8 to the gas supply port 7 side, and blower means driving means for rotating and driving the blower means 13 (for example, The motor 12 and a heater (for example, an electric heater) 6 provided between the gas supply port 7 of the circulation passage 15 and the blowing means 13. The main body 9 is composed of a stationary portion 9a and a movable portion 9b, and the gas supply port 7, the heater 6, the blowing means 13, and the blowing means driving means 12 are provided on the movable portion 9b of the main body 9.

The resin core removing device further includes a circulation passage 1
5, a filter 14 provided between the discharge port 8 and the blower means 13 for taking out only the molten resin from the mixture of the gas and the molten resin and discharging it to the outside of the circulation passage 15, and the movable part 9b as the stationary part 9a. A cylinder (for example, an air cylinder) 10 that slides with respect to the resin core 4 to move the gas supply port 7 back and forth. In the resin core removing device, a gas supply pipe is further connected to the molten resin discharge passage connected to the circulation passage 15 or the circulation passage 15 itself via a valve 17, and the gas supply pipe is connected to a gas source (for example, Gas cylinder) 16. The valve 17 is normally in communication with the molten resin discharge side, and is switched to the gas source 16 side when supplying gas. The gas preferably comprises a non-oxidizing gas, and carbon dioxide is used as the non-oxidizing gas. However, it may be a non-oxidizing gas other than carbon dioxide, such as nitrogen gas.
Further, it is desirable that the resin core 4 has a recess 11 formed in a portion facing the gas supply port 7.

Next, a method for removing a resin core according to an embodiment of the present invention (which is also the operation of the above apparatus) will be described with reference to FIGS.
This will be described with reference to FIG. The method of removing the resin core according to the embodiment of the present invention is performed after the molten metal (for example, molten aluminum alloy) is solidified (the state shown in FIG. 1, but the resin core 4 and the casting 3 are placed in the molds 1 and 2). It may be outside the molds 1, 2),
A step of supplying a high temperature gas to the resin core 4 made of a thermoplastic resin (see FIG. 2) to melt or gasify the resin, and then discharging and removing the melted or gasified resin to form the resin core 4 Is removed from the cast product 3 (see FIG. 3). More specifically, gas blowing means 1
It is sent by 3 and heated by the heater 6 to form a gas of about 250 ° C. or higher, and this high temperature gas is supplied to the resin core 4 from the gas supply port 7. The resin core is made of, for example, polypropylene or a copolymer of propylene and ethylene, and the resin is forcibly melted or gasified by supplying a gas having a temperature higher than the melting point (about 250 ° C.) of these resins. It is desirable to provide the resin core 4 with the recess 11 in order to improve the contact of the gas with the resin. The melted or gasified resin is discharged from the discharge port 8 to the circulation passage 15, the resin and the gas are separated by the filter 14, the resin is discharged to the outside of the circulation passage 15 and recycled as another resin core, Is circulated as it is, heated again by the heater 6 and sent to the resin core 4 which is being melted or gasified. Since gas is circulated, it is excellent in terms of thermal economy and work environment. Further, the resin is also heated by the residual heat (residual heat) of the molds 1 and 2, but mainly because it is forcibly heated by the high temperature gas,
Regardless of the amount of heating from the molds 1 and 2, it is easy to identify the timing of melting or gasification. Further, since gas is used, even if the resin core 4 has a complicated shape, it can be easily removed.

In order to quickly remove the cast product 3 from the molds 1 and 2, it is desirable to cool the cast product 3 quickly. For that purpose, the resin core 4 is cast into the casting 3
Then, the heater 6 is immediately turned off, and the valve 17 is switched to put the unheated gas from the gas source 16 into the circulation passage 15 to lower the temperature of the gas supplied into the molds 1 and 2. The casting 3 is cooled. by this,
Regardless of using high temperature gas to remove the resin core 4,
It becomes possible not to prolong the casting cycle or to shorten it.

In the resin melting or gasification process,
As the melting or gasification of the resin core 4 progresses, the gas supply port 7 is moved from the skirting part 5 toward the resin core 4.
This is performed by moving the movable part 9b of the main body 9 to the resin core 4 side by the cylinder 10. By moving the gas supply port 7 to the resin core 4 side, the distance between the resin and the gas supply port 7 is maintained substantially constant even if the resin is melted or gasified, and the gas supply port 7 directly goes to the discharge port 8. That is, the amount of flowing gas does not increase without coming into contact with the resin core 4. Therefore, the resin core can always be effectively and forcibly heated.

The gas supplied and circulated is a non-oxidizing gas,
For example, carbon dioxide gas is used. This prevents deterioration of the casting 3 due to oxidation of the casting 3 and oxidation of the resin (deterioration reduces the efficiency of resin recycling), regardless of the use of high-temperature gas for forced heating and removal of the resin core 4. .

[0012]

According to the method of the present invention, since the high temperature gas is supplied to melt and gasify the resin to remove it, the resin core can be forcibly heated, regardless of the residual heat of the die. The timing of melting and gasifying the resin can be almost specified, and the resin removal time can be shortened to shorten the casting cycle time. According to the method of claim 2, in addition to the effect of the method of claim 1, since a step of cooling the cast product by lowering the temperature of the supplied gas is provided, a high temperature gas is used for removing the resin core. However, the casting cycle time can be shortened.
According to the method of claim 3, in addition to the effect of the method of claim 1, the gas supply port is moved from the skirting board toward the resin core as the resin is melted or gasified. The amount of gas flowing from the gas supply port to the discharge port can be kept small without touching it, and the resin core can be removed efficiently. According to the method of claim 4, in addition to the effect of the method of claim 1, since the non-oxidizing gas is used as the gas, the oxidation of the cast product and the resin can be suppressed regardless of the removal by the high temperature gas. According to the apparatus of claim 5, since the gas supply port, the discharge port, the heater, the blowing means, and the circulation passage are provided, the resin core can be forcibly heated, and the resin is melted regardless of the residual heat of the mold. The timing of gasification can be almost specified, and the resin removal time can be shortened to shorten the casting cycle time. According to the apparatus of claim 6, in addition to the effect of the apparatus of claim 5, by providing a filter, the resin and the gas can be separated, the gas can be circulated and reused for removing the resin core, and in terms of thermal economy. Be advantageous

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a resin core removing apparatus according to an embodiment of the present invention (which is also an apparatus used directly for carrying out a method) before melting or gasifying the resin core.

FIG. 2 is a sectional view of the apparatus of FIG. 1 during melting or gasification of a resin core.

3 is a sectional view of the apparatus of FIG. 1 just before completion of melting or gasification of a resin core.

[Explanation of symbols]

 1, 2 Mold 3 Cast product 4 Resin core 5 Baseboard part 6 Heater 7 Gas supply port 8 Discharge port 9 Main body 9a Stationary part 9b Movable part 10 Cylinder 11 Recess 12 Air blower drive means 13 Air blower 14 Filter 15 Circulation Passage 16 Gas source 17 Valve

Claims (6)

[Claims] 1. A step of removing a resin core from a casting by supplying a high-temperature gas to the resin core after melting the molten metal to melt or gasify the resin and remove the molten or gasified resin. To remove the resin core. 2. The method for removing a resin core according to claim 1, further comprising the step of cooling the cast product by lowering the temperature of the gas supplied into the mold after removing the resin core from the cast product. 3. In the step of melting or gasifying the resin,
The method for removing a resin core according to claim 1, wherein the gas supply port is moved toward the resin core as the resin melts or gasifies. 4. The method for removing a resin core according to claim 1, wherein a non-oxidizing gas is used as the gas to be supplied. 5. A gas supply port for supplying a gas to the resin core, a discharge port for discharging the gas touching the resin core and the molten or gasified resin, and a gas supply port for discharging the gas from the discharge port. A resin core including: a circulation passage for circulating the circulation passage; and an air blower provided in the middle of the circulation passage, and a heater provided in a portion of the circulation passage between the gas supply port and the air blower. Removal device. 6. A filter for discharging only the molten resin from a mixture of gas and the molten resin and discharging the molten resin to the outside of the circulation passage is provided in a portion of the circulation passage between the discharge port and the blower. The resin core removing device according to claim 5.