JPH1177700A - Hollow molding method and molded product - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To fix a core made of a low melting point metal in advance in a cavity of a mold, and to fill the space between the core and the mold with a resin, thereby forming a low melting point metal core and a resin. A hollow molding method in which a low-melting-point metal core is melted and removed in a short time from a molded product obtained by integrating the above. A core is hollowed, and a liquid having a temperature higher than the melting point of a low-melting metal and lower than the softening temperature of a resin is also introduced into the core to melt and remove the core. Further, a liquid having a temperature lower than the softening temperature of the resin is circulated inside the core to melt and remove the core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method and a molded product for molding a bent or complicated part having a space inside therein, which cannot be molded by a molding method using a moving piece provided in a mold. Related to

[0002]

2. Description of the Related Art When molding a part having a space inside with a resin, a solid core made of a low-melting metal in advance is fixed in a cavity of a mold, and is inserted between the core and the mold. A molded product in which a low-melting-point metal core and resin are integrated by filling the resin, and when removing the low-melting-point metal core from the integrated molded product, a molded product in which the core and resin are integrated. Was immersed in a liquid having a temperature higher than the melting point of the low-melting metal and lower than the softening temperature of the resin to melt and remove the low-melting metal.

[0003]

In the above prior art, since the core made of low melting point metal is solid, the capacity is large.
There is a problem that it takes a long time to melt and remove the core.

An object of the present invention is to provide a molding method for melting and removing a core in a short time when a resin having a shape having a space inside is molded using a core, and a molded article by this method, for example, a water treatment pipe. , Artificial heart pump parts, and automobile engine intake system parts.

[0005]

A core made of a low-melting metal in advance is fixed in a cavity of a mold, and a resin is filled between the core and the mold, thereby forming a core made of a low-melting metal and a resin. When the low-melting-point metal core is removed from the molded article integrating the core, the amount of heat energy required for heating and melting the core is reduced by providing a cavity inside the core. further,
By circulating a liquid with a temperature higher than the melting point of the low-melting metal and lower than the softening temperature of the resin inside the core, heat is transferred directly from the liquid to the low-melting metal without passing through the resin molding, Circulating the liquid whose temperature has been reduced by the heat of the metal, circulating and replacing the liquid heated to a predetermined temperature, quickly raising the temperature of the low-melting-point metal core to above the melting point and removing it by melting. As a result, the low-melting-point metal core can be removed in a short time. In addition, a high-frequency induction heating coil is arranged around a molded product obtained by integrating a low-melting-point metal core and a resin, a high-frequency current is applied to the coil, and a molded product obtained by integrating the low-melting-point metal core and the resin. By applying an induced current to only the low melting point metal part and heating the low melting point metal part, the low melting point metal core can be removed in a shorter time.

Further, when a low melting point metal is used as the liquid used for the melting, the heat transfer coefficient increases, so that the low melting point metal core can be removed in a shorter time.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) An embodiment of the present invention will be described below. FIG.
As shown in FIG. 2, a mold 1 in which a cavity is dug into a core shape having an outer diameter of 40 mm and a mold 17 are combined as shown in FIG. 2, and the ratio of tin and bismuth is reduced to 0 from a gate portion 2 provided below the mold. .57: 0.43 mixed and alloyed, melting point 139 ° C
Was melted by heating at 200 ° C. to fill the cavity over 12 seconds. After maintaining this state for 15 seconds, the unsolidified low melting point metal was allowed to flow out by its own weight from the gate portion. As a result, the wall thickness shown in FIG.
A 3.6 mm hollow core 4 was obtained.

The low-melting metal outer diameter of 40 mm and the thickness of 2.9-
The hollow core 4 having a diameter of 3.6 mm is inserted into a mold 6 in which a hollow resin molded product shown in FIG.
And injection-molded using nylon 66 resin. FIG. 7 shows a molded product obtained by integrating the low-melting-point metal hollow core 4 and the hollow resin molded product 8. The molded article obtained by integrating the low-melting metal hollow core 4 and the hollow resin molded article 8 is immersed in ethylene glycol 9 heated to 160 ° C. as shown in FIG. 9, and ethylene glycol is spread inside the hollow core. The low-melting metal core was melted and removed. The time required for melting and removing the low-melting metal core was 110 seconds. By this process, a hollow resin molded product 8 having a predetermined size and shape shown in FIG. 10 was obtained.

Comparative Example 1 A comparative example of the present invention will be described below. A mold 1 and a mold 2 with a cavity dug in the shape of a core with an outer diameter of 40 mm are combined, and the ratio of tin and bismuth is mixed at a ratio of 0.57: 0.43 from the gate provided at the lower part of the mold. The melted low melting point metal having a melting point of 139 ° C. was heated to 200 ° C. and dissolved therein, and the cavity was filled in the cavity for 12 seconds. This state was maintained for 80 seconds to solidify the low-melting-point metal to obtain a solid core 5 shown in FIG. This core is set in the mold shown in FIG. 5 and injection molded using nylon 66 resin. The molded product obtained by integrating the low-melting-point metal core and the resin was immersed in ethylene glycol 9 heated to 160 ° C. as shown in FIG. 11 to start melting and removing the low-melting-point metal core 5. However, before the low-melting metal solid core 5 was melted away, the hollow resin molded product 8 began to deform.

(Embodiment 2) An embodiment of the present invention will be described below. A mold 1 in which a cavity is dug into a core shape having an outer diameter of 40 mm shown in FIG. 1 and a mold 17 are combined as shown in FIG.
The bismuth ratio was mixed at 0.57: 0.43, and the alloyed low-melting point metal having a melting point of 139 ° C. was heated to 200 ° C. and melted to fill the cavity over 12 seconds. After maintaining this state for 15 seconds, the unsolidified low melting point metal was allowed to flow out by its own weight from the gate portion. As a result, a hollow core 4 having a wall thickness of 2.9 to 3.6 mm as shown in FIG. 3 was obtained.

The low melting point metal outer diameter of 40 mm and the thickness of 2.9 to
The hollow core 4 having a diameter of 3.6 mm is inserted into a mold 6 in which a hollow resin molded product shown in FIG.
And injection-molded using nylon 66 resin. FIG. 7 shows a molded product obtained by integrating the low-melting-point metal hollow core 4 and the hollow resin molded product 8. A molded product obtained by integrating the low-melting metal core 4 and the hollow resin molded product 8 is shown in FIG.
As shown in FIG. 2, a nozzle 11 that is immersed in ethylene glycol 9 heated to 160 ° C. and ejects ethylene glycol heated to 160 ° C. by a pump at the lower end of the hollow core 4 made of low melting metal is provided. Ethylene glycol was circulated through the circulation oil pipe 12 inside the hollow core made of metal to melt and remove the hollow core 4 made of low melting point metal. The time required for melting and removing the low melting point metal core 4 was 56 seconds. By this process, a hollow resin molded product 8 having a predetermined size and shape shown in FIG. 10 was obtained.

(Embodiment 3) An embodiment of the present invention will be described below. A mold 1 in which a cavity is dug into a core shape having an outer diameter of 40 mm shown in FIG. 1 and a mold 17 are combined as shown in FIG.
The bismuth ratio was mixed at 0.57: 0.43, and the alloyed low melting point metal having a melting point of 139 ° C. was heated to 200 ° C. and melted to fill the cavity for 12 seconds. After maintaining this state for 15 seconds, the unsolidified low melting point metal was allowed to flow out by its own weight from the gate portion. As a result, a hollow core 4 having a wall thickness of 2.9 to 3.6 mm as shown in FIG. 3 was obtained.

The low-melting metal outer diameter of 40 mm and the thickness of 2.9-
The hollow core 4 having a diameter of 3.6 mm is inserted into a mold 6 in which a hollow resin molded product shown in FIG.
And injection-molded using nylon 66 resin. FIG. 7 shows a molded product obtained by integrating the low-melting-point metal hollow core 4 and the hollow resin molded product 8. As shown in FIG. 13, a low-melting-point metal circulating pipe 15 for circulating the low-melting-point metal is provided at the upper and lower ends of the molded article obtained by integrating the low-melting-point metal hollow core 4 and the hollow resin molded article 8 with a fluororubber packing 14.
And the inside of the low-melting-point metal hollow core 4
The low melting point metal heated and melted at 0 ° C. was circulated to melt and remove the low melting point metal hollow core 4. The time required for melting and removing the low-melting metal hollow core 4 was 50 seconds. By this process, a hollow resin molded product 8 having a predetermined size and shape shown in FIG. 10 was obtained.

(Embodiment 4) An embodiment of the present invention will be described below. A mold 1 in which a cavity is dug into a core shape having an outer diameter of 40 mm shown in FIG. 1 and a mold 17 are combined as shown in FIG.
The bismuth ratio was mixed at 0.57: 0.43, and the alloyed low-melting point metal having a melting point of 139 ° C. was heated to 200 ° C. and melted to fill the cavity over 12 seconds. After maintaining this state for 15 seconds, the unsolidified low melting point metal was allowed to flow out by its own weight from the gate portion. As a result, a hollow core 4 having a wall thickness of 2.9 to 3.6 mm as shown in FIG. 3 was obtained.

The low-melting metal outer diameter of 40 mm and the thickness of 2.9-
The hollow core 4 having a diameter of 3.6 mm is inserted into a mold 6 in which a hollow resin molded product shown in FIG.
And injection-molded using nylon 66 resin. FIG. 7 shows a molded product obtained by integrating the low-melting-point metal hollow core 4 and the hollow resin molded product 8. As shown in FIG. 14, a high-frequency induction heating coil 16 is arranged around the molded product obtained by integrating the low-melting-point metal hollow core 4 and the hollow resin molded product 8, and immersed in ethylene glycol 9 heated to 160 ° C. 13kHz, 160V, 1 for high frequency induction heating coil
A low-melting-point metal hollow core 4 was melted and removed by applying a high-frequency current of 60 A for 30 seconds. The time required for melting and removing the low-melting metal hollow core 4 was 45 seconds. By this process, the hollow resin molded product 8 having a predetermined size and shape shown in FIG.
I got

(Embodiment 5) An embodiment of the present invention will be described below. A mold 1 in which a cavity is dug into a core shape having an outer diameter of 40 mm shown in FIG. 1 and a mold 17 are combined as shown in FIG.
The bismuth ratio was mixed at 0.57: 0.43, and the alloyed low-melting point metal having a melting point of 139 ° C. was heated to 200 ° C. and melted to fill the cavity over 12 seconds. After maintaining this state for 15 seconds, the unsolidified low melting point metal was allowed to flow out by its own weight from the gate portion. As a result, a hollow core 4 having a wall thickness of 2.9 to 3.6 mm as shown in FIG. 3 was obtained.

The low melting point metal outer diameter of 40 mm and the thickness of 2.9 to
The hollow core 4 having a diameter of 3.6 mm is inserted into a mold 6 in which a hollow resin molded product shown in FIG.
And injection-molded using nylon 66 resin. FIG. 7 shows a molded product obtained by integrating the low-melting-point metal hollow core 4 and the hollow resin molded product 8. As shown in FIG. 15, a high-frequency induction heating coil 16 is arranged around a molded product obtained by integrating the low-melting-point metal hollow core 4 and the hollow resin molded product 8, and immersed in ethylene glycol 9 heated to 160 ° C. Nozzle 1 for ejecting ethylene glycol 9 heated to 160 ° C. by pump at the lower end of hollow core 4 made of low melting point metal
1 and circulate the ethylene glycol 9 through the circulating oil pipe 12, and in parallel thereto, apply a high-frequency current of 13 kHz, 160 V, 160 A to the high-frequency induction heating coil 16 for 30 seconds, and supply the low-melting metal hollow core 4. Was melted off. The time required for melting and removing the low-melting-point metal hollow core 4 was 32 seconds. By this process, a hollow resin molded product 8 having a predetermined size and shape shown in FIG. 10 was obtained.

[0018]

According to the present invention, a core made of a low-melting metal in advance is fixed in a cavity of a mold, and a molded product obtained by integrating a core made of a low-melting metal and a resin is manufactured. When the core is removed and a component having a space inside is formed of resin, there is an effect that the low-melting metal core is melted and removed in a short time.

[Brief description of the drawings]

FIG. 1 is a bird's-eye view of a mold for molding a low-melting-point metal core according to the present invention.

FIG. 2 is a bird's-eye view of a mold combined to form a low-melting-point metal core according to the present invention.

FIG. 3 is a bird's-eye view of a low-melting-point metal hollow core according to the present invention.

FIG. 4 is a bird's-eye view of a solid core made of a low melting point metal according to a comparative example.

FIG. 5 is a bird's-eye view of a mold for integrally molding a hollow core made of a low-melting metal and a hollow resin molded product according to the present invention.

FIG. 6 is a bird's-eye view showing a state in which the low-melting-point metal hollow core is set in a mold for integrally molding the low-melting-point metal hollow core and the hollow resin molded product according to the present invention.

FIG. 7 is a bird's-eye view of a molded product obtained by integrating a low-melting-point metal hollow core and a hollow resin molded product according to the present invention.

8 is a cross-sectional view taken along the line AA 'of the molded product obtained by integrating the low-melting-point metal hollow core and the hollow resin molded product of FIG. 7 according to the present invention.

FIG. 9 is a bird's-eye view of an apparatus for removing a low-melting-point metal hollow core from a molded product obtained by integrating a low-melting-point metal hollow core and a hollow resin molded product according to the first embodiment of the present invention.

FIG. 10 shows a hollow resin molded article molded according to the present invention.

FIG. 11 is a bird's-eye view of an apparatus for removing a low-melting-point metal solid core from a molded product obtained by integrating a low-melting-point metal solid core and a hollow resin molded product according to Comparative Example 1.

FIG. 12 is a bird's-eye view of an apparatus for removing a low-melting-point metal hollow core from a molded product obtained by integrating a low-melting-point metal hollow core and a hollow resin molded product according to a second embodiment of the present invention.

FIG. 13 is a bird's-eye view of an apparatus for removing a low-melting-point metal hollow core from a molded product obtained by integrating a low-melting-point metal hollow core and a hollow resin molded product according to a third embodiment of the present invention.

FIG. 14 is a bird's-eye view of an apparatus for removing a low-melting-point metal hollow core from a molded product obtained by integrating a low-melting-point metal hollow core and a hollow resin molded product according to a fourth embodiment of the present invention.

FIG. 15 is a bird's-eye view of an apparatus for removing a low-melting-point metal hollow core from a molded product obtained by integrating a low-melting-point metal hollow core and a hollow resin molded product according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Core molding die, 2 ... Gate, 3 ... Core molding die cooling water inlet / outlet pipe, 4 ... Low melting metal hollow core, 5 ... Low melting metal solid core, 6 ... Hollow resin molding Mold, 7: hollow resin molded cavity, 8: hollow resin molded product, 9: ethylene glycol oil, 10: oil bath, 11: circulating oil nozzle, 12: circulating oil pipe, 13: molded product support, 14: fluorine Rubber packing, 15: low melting point metal circulation pipe, 16: high frequency induction heating coil, 17: core forming die.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29L 22:00

Claims (6)

[Claims] 1. A core made of a low-melting-point metal in advance is fixed in a cavity of a mold, and a resin is filled between the core and the mold to integrate the core with the low-melting-point metal and the resin. In a molding method for removing a low-melting-point metal core from a molded product to obtain a resin molded product, at least one core portion exposed from a molded product obtained by integrating a core and a resin into the core. A resin hollow molding method in which a core and a resin are integrally molded using a core having a connected cavity, and the core is melted and removed, and a resin hollow molded article molded by this molding method. 2. A core made of a low-melting-point metal in advance is fixed in a cavity of a mold, and a resin is filled between the core and the mold to integrate the core with the low-melting-point metal and the resin. In a molding method of removing a low-melting metal core from a molded product to obtain a resin molded product, a hole penetrating between at least two portions of a core portion exposed from a molded product obtained by integrating a core and a resin is formed. A resin hollow molding method in which a core and a resin are integrally molded using a core of the resin and the core is melted and removed, and a resin hollow molded article molded by this molding method. 3. When the low-melting-point metal core is removed from the molded article obtained by integrating the low-melting-point metal core and the resin according to the second aspect, the melting point temperature of the low-melting-point metal is removed inside the core. A resin hollow molding method for circulating a liquid having a temperature higher than the softening temperature of the resin to melt and remove the core, and a resin hollow molded article molded by the molding method. 4. The method according to claim 2, wherein when the low-melting-point metal core is removed from the molded article in which the low-melting-point metal core and the resin are integrated, the melting point of the low-melting-point metal is set inside the core. A resin hollow molding method for circulating an alloy liquid having a temperature higher than the softening temperature of the resin to melt and remove the core, and a resin hollow molded article molded by this molding method. 5. The method according to claim 1, wherein when removing the low-melting-point metal core from the molded article in which the low-melting-point metal core and the resin are integrated, the low-melting-point metal core and the resin are integrated. A high-frequency induction heating coil is arranged around the molded product, and the molded product and the coil are immersed in a liquid having a temperature higher than the melting point of the low-melting metal and lower than the softening temperature of the resin, and a high-frequency current is applied to the coil. A resin hollow molding method for melting and removing a core, and a resin hollow molded article molded by this molding method. 6. The method according to claim 2, wherein when removing the low-melting-point metal core from the molded article in which the low-melting-point metal core and the resin are integrated, the low-melting-point metal core and the resin are integrated. A high-frequency induction heating coil is arranged around the molded product, and the molded product and the coil are immersed in a liquid having a temperature higher than the melting point of the low-melting metal and lower than the softening temperature of the resin, and a high-frequency current is applied to the coil. At the same time, a resin hollow molding method for circulating a liquid having a temperature higher than the melting point of the low melting point metal and lower than the softening temperature of the resin inside the core to melt and remove the core, and the resin hollow molding formed by this molding method Goods.