Injection molding device

An injection molding device configured for manufacturing a foil decorated molding, includes a channel defined in the mold, and a thermal medium source connected to the channel of the mold for inputting thermal medium into the mold via the channel to press the foil.

Relevant subject matter is disclosed in the co-pending U.S. patent application Ser. No. 11/956,347, and entitled “METHOD FOR ELONGATING FOIL;” application Ser. No. 11/956,348, and entitled “METHOD FOR MANUFACTURING A FOIL DECORATED MOLDING;” application Ser. No. 11/956,349, and entitled “VALVE DEVICE OF INJECTION MOLDING DEVICE;” application Ser. No. 11/956,350, and entitled “INJECTION MOLDING DEVICE”), which are filed on the same date Dec. 14, 2007.

BACKGROUND

1. Field of the Invention

The present invention relates to injection molding devices, and particularly to an injection molding device for manufacturing a foil decorated molding efficiently.

2. Description of Related Art

Conventionally, various kinds of methods for manufacturing a foil decorated molding, which is molded by an injection molding process and has a transfer layer removed from a substrate foil of a transfer foil and placed on the surface of the molding after the transfer foil is inserted into cavities in an injection mold, have been known in the art. Since the use of the method requires an alignment of the transfer foil along a cavity-forming face of the mold, the transfer foil is preheated before the injection molding process so as to be easily aligned along the cavity-forming face of the mold where the cavity-forming face thereof is greatly recessed or projected from a parting face of the mold.

A traditional injection molding method includes transferring a heater between the male mold and the female mold to heat the foil before matched molds, and removing the heater after the foil being heated. However, because of the heater, a transport that transferring the heater is need, which leads to an increase of a cost and a volume of the injection mold.

What is needed is to provide an injection molding device in which a depth and an angle range that the foil can be extended are enhanced.

SUMMARY

In one embodiment, an injection molding device configured for manufacturing a foil decorated molding, includes a channel defined in the mold, and a thermal medium container connected to the channel of the mold for inputting thermal medium into the mold via the channel to press the foil.

Other advantages and novel features of the present invention will become more apparent from the following detailed description of an embodiment when taken in conjunction with the accompanying drawings, in which:

DETAILED DESCRIPTION

Referring toFIG. 1, an injection molding device for transferring a foil100in accordance with an embodiment of the present invention includes a transport10, a mold including a male mold20and a female mold30, a plurality of pressing members40, and a thermal medium source90.

The male mold20forms a projecting part21protruding toward the female mold30. A plurality of air discharging holes23is defined in the male mold20round the projecting part21and extending from a side, facing the female mold30, of the male mold20to an opposite side of the male mold20. A pressure release valve80is connected to each air discharging hole23. The pressure release valve80is adjustable according as the pressure when molding. A plurality of receiving slots25are defined in the male mold20in vicinity of edges of the male mold20. A plurality of hermetic rings27is received in the corresponding receiving slots25.

Referring toFIG. 2, the female mold30defines a cavity31therein. The cavity31includes a bottom surface A3, a first side surface A1extending from an edge of the bottom surface A3and a second side surface A2extending from an opposite edge of the bottom surface A3to a surface that faces the male mold20, with an opening formed on the corresponding surface of the female mold30. A length of the opening of the cavity31is L. A plurality of air discharging holes32is defined in the male mold20and extending from a side, facing the male mold20, of the female mold30to an opposite side of the female mold30. At least two of the air discharging holes32extends from the bottom surface A3of the cavity31to the corresponding side of the female mold30opposing to the male mold20. Each air discharging hole32is connected to a vacuum-pump at the side of the female mold30opposing to the male mold20. A plurality of hermetic rings33is attached to the female mold30adjacent to an edge of the female mold30.

Referring also toFIGS. 3 and 4, the male mold20defines a plurality of channels29therein extending from a side, facing the female mold30, of the projecting part21to a side of the male mold20opposing to the female mold30. Each channel29includes a bell-mouthed recessed portion291defined in the projecting part21with a large end thereof in the surface facing the female mold30, of the projecting part21, a conduit295defined in the male mold20communicating with a small end of the recessed portion291, and an L-shaped slender duct296with one end communicating with the conduit295and the other end passing through the surface opposing to the female mold30, of the male mold20. A block298protrudes in from one end opposing to the recessed portion291, of the conduit295. One end of a pipe91is connected to the end opposing to the female mold30, of each slender duct296, and the other end of the pipe91is connected to the thermal medium source90. A through hole is defined in the block298.

A plug70is attached in each channel29. The plug70includes a taper-shaped obturating portion71for obturating the recessed portion291of the channel29, and a pole73extending from a small end of the obturating portion71. The pole73extends through the through hole of the block298. A fastening member75is fixed to a distal end of the pole73. A resilient member79, such as a spring, fits about the pole73and is resiliently located between the block298and the fastening member75.

The thermal medium source90has thermal medium contained therein, such as thermal liquid or high-pressure gas. In this embodiment, the thermal medium is thermal high-pressure gas. The thermal medium is capably being heated by an electric heater or an infrared ray heater (IR heater).

The transport10includes two transporting rollers13and two guiding rollers15positioned at two opposite ends of the mold respectively, for transporting the foil100into the mold. The foil100includes a base layer, and a printed layer attached to the base layer and having printed patterns or characters.

Referring also toFIGS. 5 and 6, the foil100is transmitted into the mold and between the male and female mold20,30. The male and female mold20,30are pressing member locked together to form a molding space among the inner surface of the cavity31of the female mold30, the projecting portion21of the male mold20, and parts round the projecting portion21round the projecting portion21. The pressing members40are received in the corresponding receiving slots25, and press the corresponding hermetic rings27,33to airproof the molding space. The molding space is separated to a first airproof space adjacent to the female mold30and a second airproof space adjacent to the male mold20by the foil100. A vacuum is connected to the air discharging holes32of the female mold30to vacuumize the first airproof space, thus the foil100is absorbed to toward the first airproof space. The pressure release valve80is shut, and the value of the pressure release valve80is predetermined according to the molding condition. The thermal medium source90inputs heated gas to the channels29via the pipes91. The plugs70are driven by the heated gas to move toward the female mold30, therefore the channels29are open. The heated gas is blown into the second airproof to press the foil100to cling to the inner surface of the cavity31of the female mold30. The foil100is intenerated by the heated gas to cling to the inner surface of the cavity31easily.

Referring also toFIG. 7, molten resin is injected through an injection opening defined in the male mold20into the molding space. The molten resin presses the plugs70into the corresponding channels29against resistance of the corresponding resilient members79. The heated gas in the second airproof space is leaked out via the air discharging holes23of the male mold20when the pressure in the molding space is larger than the predetermined value of the pressure release valve80. The molten resin is cooled to form a mold body. The mold is open, with the male mold20being separated from the female mold30. The base layer of the foil100is released from the mold body. Thus, the printed layer of the foil100is attached to a surface of the mold body.

In this embodiment, the injection molding device is used for elongating the foil100between the male and female mold20,30by exhausting air from the cavity31via the air discharge holes32of the female mold30and pressurizing the foil100via the heated gas. For example, a length of the first side surface A1is a1, a length of the second side surface A2is a2, and a length of the bottom surface A3is a3, when the first, second, and bottom surface A1, A2, A3of the cavity31and the length L accord with an expressions of a1+a2+a3>=(1+20%)*L, the foil100is capably of being elongated for suiting the cavity31of the female mold30.