EP-4737092-A1 - DUAL-INJECTION MOLDING SYSTEM

Abstract

A dual-injection molding system (3) mainly includes a control device (34) disposed between a feeding device (31) and each injection device (32) . Each injection device (32) has an injection tube (321), an outlet gate (323), and a needle valve unit (324) disposed in the injection tube (321) . Each control device (34) has a control unit (341) and a stop unit (342). The stop unit (342) and the needle valve unit (324) are controlled by the control unit (341) . The feeding device (31) is adapted to obtain a mixture (C) by mixing a base material (A) with a supercritical fluid material (B) in a feeding tube (312). The stop unit (342) is actuated to regulate a communicating state between the feeding device (31) and each injection tube (321), and the needle valve unit (324) is actuated to adjust an open area at each outlet gate (323), thereby controlling a feeding quantity and an injection quantity of the mixture (C), preventing the unequal injection of the mixture (C), and increasing the injection forming quality and the yield rate.

Inventors

• HUANG, FONG-WU

Assignees

• Tien Kang Co., Ltd.

Dates

Publication Date

20260506

Application Date

20241030

Claims (3)

1. A dual - injection molding system (3) comprising a feeding device (31), two injection devices (32) respectively connected to said feeding device (31), and a mold device (33) connected to said two injection devices (32), wherein said feeding device (31) includes a first supply unit (311) filled with a base material (A), a feeding tube (312) connected to said first supply unit (311), a second supply unit (313) connected to said feeding tube (312), and a feeding screw (314) disposed in said feeding tube (312), each of said two injection devices (32) including an injection tube (321), an inlet gate (322) formed on said injection tube (321), and an outlet gate (323) formed on said injection tube (321), said mold device (33) including a first mold (331) connected to said outlet gate (323) of each injection device (32), a second mold (332) disposed in opposing relationship to said first mold (331), and a pushing unit (333) connected to said second mold (332), a cavity (334) being defined when said first mold (331) and said second mold (332) are engaged together; characterized in that a supercritical fluid material (B) is fed from said second supply unit (313) into said feeding tube (312) for being used as a physical foaming agent, said supercritical fluid material (B) and said base material (A) being mixed in said feeding tube (312) and stirred by said feeding screw (314) to become a mixture (C), a needle valve unit (324) being disposed in said injection tube (321) which is extended in a linear manner by which said mixture (C) is straightly injected to said cavity (334), and an injection quantity of said mixture (C) is controlled by moving said needle valve unit (324), a control device (34) being disposed between said feeding device (31) and each of said two injection devices (32), said control device (34) including a control unit (341) and a stop unit (342), a movement of said needle valve unit (324) and an extending/retracting operation of said stop unit (342) being respectively driven by said control unit (341), thereby subjecting said mixture (C) to a feeding operation and an injection operation under the control of said control unit (341) .
2. The system (3) according to claim 1, wherein said control device (34) includes a measuring unit (343) linked with said control unit (341) .
3. The system (3) according to claim 1, wherein said mold device (33) is connected to a supply-exhaust device (35), thereby maintaining constant pressure in said cavity (334) and allowing said mixture (C) to foam in said cavity (334) stably.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an injection molding system and relates particularly to a dual-injection molding system. 2. Description of the Related Art Dual - injection molding technology is a technology that is mature and commonly in use. The dual-injection molding technology is capable of manufacturing a single object through combining two different materials to thereby provide plastic products with multiple colors, materials or textures. The technology facilitates the production of complex products or products with multi - functions. In addition, the technology can be adapted to simultaneously manufacture two single objects to thereby increase the processing efficiency. The dual-injection molding technology also facilitates reduction in the processing procedures, in the subsequent assembling time and costs, and in the scrap rate when comparing with the single-injection molding technology, thereby improving the production efficiency and economic benefits. Therefore, the dual- injection molding technology is widely used in various fields , such as electronic products, automotive accessories, medical equipment, sports equipment, and different daily necessities. A conventional dual-injection molding system comprises two injection devices, a feeding device and a mold device respectively connected to the injection devices. The feeding device includes a feeding tube, a first supply unit and a second supply unit respectively connected to the feeding tube, and a feeding screw installed in the feeding tube. Each injection device includes an injection tube and a pressing unit installed in the injection tube. The injection tube is provided with an inlet gate and an outlet gate. The mold device includes a first mold and a second mold positioned in opposing relationship, and a pushing unit connected to the second mold. The first mold is connected to the outlet gate of each injection device. When the second mold is pushed by the pushing unit to be engaged with the first mold, a cavity is formed and defined. During an operation of the dual- injection molding system, a base material stored in the first supply unit is delivered into the feeding tube. Simultaneously, a foaming agent is also delivered from the second supply unit into the feeding tube. The base material and the foaming agent are stirred under a rotation of the feeding screw to provide a mixture. The mixture is then delivered into the injection tube of each injection device from the feeding tube. Meanwhile, the second mold is pushed by the pushing unit to thereby achieve a tight engagement between the second mold and the first mold and enclose the cavity. Afterward the mixture is pressed and injected to the cavity by the pressing unit to thereby form an object. In order to deliver the mixture into each injection device smoothly, a plurality of thread convolutions are spirally disposed on a surface of the feeding screw in a continuously spiral extension. However, from a front view of the feeding screw, the left side and the right side of the same thread convolution locate at different positions. The left side and the right side of the thread convolution will carry different quantities of the mixture. Accordingly, the injection devices receive different quantities of the mixture, and that results in the unequal injection of the mixture. Hence, the yield rate of the production is reduced caused by the unequal injection of the mixture. Meanwhile, a channel connected between the mold device and each injection device is extended in a non- linear manner, and that will result in pressure change of the mixture when the mixture is injected from the injection device to the mold device. Thus, the injection forming quality is unstable because the mixture cannot enter into the cavity evenly, and that requires to be improved. SUMMARY OF THE INVENTION The object of this invention is to provide a dual-injection molding system capable of precisely controlling a feeding operation and an injection operation of mixture, effectively preventing the unequal injection, and increasing the injection forming quality and the yield rate. The dual-injection molding system of this invention comprises a feeding device and a mold device, two independent injection devices connected between the feeding device and the mold device, and two control devices. Each control device is installed between the feeding device and one of the injection devices. The feeding device has a first supply unit adapted to supply a base material, a second supply unit adapted to supply a supercritical fluid material, a feeding tube connected to the first supply unit and the second supply unit respectively, and a feeding screw set within the feeding tube. Each injection device has an injection tube and a needle valve unit set within the injection tube. The injection tube is arranged in a linear manner and formed with an inlet gate and an outlet gate. Each control device