Double-injection molding system

Abstract

The invention discloses a double-injection molding system which is mainly characterized in that a material quantity control device is arranged between each injection device and a feeding device, each injection device is provided with an injection pipe provided with an injection port and a needle valve unit arranged in the injection pipe, each material quantity control device is provided with a control unit and a stop unit, and the needle valve unit is provided with a needle valve. The needle valve unit and the stopping unit are respectively controlled by the control unit, and after the screw rod of the feeding device mixes the material and the supercritical fluid into a mixture, the stopping unit and the needle valve unit are linked through the control unit so as to control the communication state between the feeding device and the ejection pipe and control the blocking degree of the ejection opening; therefore, the feeding amount and the ejection amount of the mixture are controlled, the defect of incomplete filling caused by uneven discharging is avoided, and the subsequent forming quality and the yield are effectively improved.

Description

Technical Field

[0001] This invention relates to an injection molding system, and more specifically to a dual-injection injection molding system. Background Technology

[0002] Two-shot injection molding is a common and mature process technology that can injection mold two different materials into a single object, thereby producing plastic products with different colors, materials, or textures. It can not only mold relatively complex and more functional products, but also be used to injection mold individual objects, thereby improving processing efficiency. Compared with single-shot injection molding, it can reduce processing steps, save time and costs in subsequent assembly, and reduce waste rate in the production process, thus improving production efficiency and economic benefits. Therefore, it is widely used in various fields, such as electronic products, automotive parts, medical devices, sports equipment, and various daily necessities.

[0003] The existing dual-injection molding system includes two injection devices, and a feeding device and a clamping device connected to multiple injection devices respectively. The feeding device has a feeding pipe, a hopper and a supply unit connected to the feeding pipe, and a screw installed in the feeding pipe. Each injection device has an injection pipe with an inlet and an outlet, and a propulsion unit installed in the injection pipe. The clamping device has an upper mold and a lower mold arranged in a corresponding manner, and a top mold unit connected to the lower mold. The upper mold is connected to the outlet of each injection device. When the top mold unit pushes the lower mold toward the upper mold, the upper mold and the lower mold are tightly closed to form a molding space.

[0004] Continuing from the previous description, when using the dual-injection molding system, the material stored in the hopper is first introduced into the feed pipe, and at the same time, a foaming agent is introduced into the feed pipe through the supply unit. During the rotation of the screw, the material and the foaming agent are fully mixed into a mixture, and the mixture is pushed by the screw into the injection pipes of multiple injection devices. At the same time, the top mold unit pushes the lower mold towards the upper mold, so that the upper mold and the lower mold close together to form the molding space. Then, the mixture is squeezed by the propulsion unit and injected into the molding space, thereby forming an object.

[0005] However, in actual use, it was found that the screw has multiple threads on its surface, which rotate to propel the mixture forward. Therefore, these threads must extend continuously and helically along the surface of the screw. As a result, when viewed from the end face, the left and right sides of the same thread are not in the same position, resulting in a front-to-back difference. This leads to different feed amounts on the left and right sides of the screw thread, with the front side carrying less mixture than the rear side. Consequently, the amount of mixture received by the multiple injection units varies, resulting in uneven discharge and incomplete filling. This increases the defect rate of subsequent injection molding. Furthermore, the connection channel between the multiple injection units and the clamping device is bent, which makes it easier for the mixture to experience pressure changes during transport, preventing it from entering the molding space evenly. This results in relatively unstable molding quality, which needs improvement. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a dual-injection molding system that can precisely control the feeding of the mixture and the subsequent injection volume, effectively avoiding defects such as uneven discharge and incomplete filling, thereby improving the subsequent molding quality and yield.

[0007] Therefore, the dual-injection molding system of the present invention includes two independent injection devices, a feeding device connecting multiple injection devices, and a clamping device connecting multiple injection devices, with a material quantity control device provided between each injection device and the feeding device; wherein, the feeding device has a hopper for storing material, a supply unit for supplying supercritical fluid, a feed pipe connecting the hopper and the supply unit respectively, and a screw disposed in the feed pipe; furthermore, each injection device has an injection pipe having an inlet and an outlet, and a... The needle valve unit is movable within the injection tube, and the injection tube is arranged in a straight line. Each material quantity control device has a control unit and a stop unit. Thus, after the material and the supercritical fluid are uniformly mixed into a mixture by the rotation of the screw, the control unit of each material quantity control device drives its linked stop unit, thereby controlling the feeding operation of the mixture through the feed tube into multiple injection tubes. After the multiple injection tubes are filled with sufficient mixture, the needle valve unit controls the amount of mixture ejected through the injection outlet.

[0008] As a further improvement of the present invention, each of the material quantity control devices has a metering unit connected to the control unit.

[0009] As a further improvement of the present invention, the clamping device is connected to an air inlet and outlet device to maintain a constant pressure and stable foaming in the molding space.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0011] This invention can adjust and precisely control the feeding operation of different injection devices and the injection volume of the mixture injected subsequently, effectively avoiding uneven material output and incomplete filling, thereby effectively improving the subsequent molding quality and yield. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a preferred embodiment of the present invention.

[0013] Figure 2-3 This is a schematic diagram of the feeding process in the preferred embodiment.

[0014] Figure 4-5 This is a schematic diagram of the stopped feeding in the preferred embodiment.

[0015] Figure 6 This is another schematic diagram of the preferred embodiment.

[0016] Figure 7 This is a schematic diagram of the injection process of the preferred embodiment.

[0017] Figure 8 This is a schematic diagram of the stopped injection of the preferred embodiment.

[0018] Symbol explanation:

[0019] (This invention)

[0020] 3: Dual-injection molding system

[0021] 31: Feeding device

[0022] 32: Injection device

[0023] 33: Clamping device

[0024] 34: Material quantity control device

[0025] 35: Intake and exhaust system

[0026] 311: Hopper

[0027] 312: Feed pipe

[0028] 313: Supply Unit

[0029] 314: Screw

[0030] 315: Feeding Channel

[0031] 321: Injection tube

[0032] 322: Feed inlet

[0033] 323: Ejection port

[0034] 324: Needle valve unit

[0035] 331: Upper mold

[0036] 332: Lower mold

[0037] 333: Top mold unit

[0038] 334: Forming Space

[0039] 341: Control Unit

[0040] 342: Stop unit

[0041] 343: Measuring Unit

[0042] A: Materials

[0043] B: Supercritical fluid

[0044] C: Mixture Detailed Implementation

[0045] The foregoing and other technical contents, features and effects of the present invention will become clear from the following detailed description of the preferred embodiments with reference to the accompanying drawings.

[0046] See Figure 1 , Figure 2 and Figure 6 As shown, in a preferred embodiment of the dual-injection molding system 3 of the present invention, the dual-injection molding system 3 includes a feeding device 31, two injection devices 32 respectively connected to the feeding device 31, and a clamping device 33 connected to a plurality of injection devices 32. The plurality of injection devices 32 are independently arranged, and a material quantity control device 34 is provided between each injection device 32 and the feeding device 31. In this embodiment, the clamping device 33 is connected to an air intake and exhaust device 35. The feeding device 31 has a hopper 311 storing a material A, a feed pipe 312 connected to the hopper 311, a supply unit 313 connected to the feed pipe 312, and a screw 314 installed in the feed pipe 312. A feed channel 315 is provided between the feed pipe 312 and each of the injection devices 32. The supply unit 313 is used to input a supercritical fluid B into the feed pipe 312 for use as a physical foaming agent.

[0047] See Figure 2 , Figure 3 and Figure 6As shown, each injection device 32 has a hollow injection tube 321, an inlet 322 connected to the feed channel 315, an injection outlet 323 formed in the injection tube 321, and a needle valve unit 324 installed in the injection tube 321. The injection tube 321 is arranged in a straight line. In addition, the clamping device 33 has an upper mold 331 connected to the injection outlet 323 of each injection device 32, a lower mold 332 corresponding to the upper mold 331, and a top mold unit 333 connected to the lower mold 332. The top mold unit 333 can push the lower mold 332 toward the upper mold 331 so that the upper mold 331 and the lower mold 332 are tightly closed to form a molding space 334. In this embodiment, the clamping device 33 is described as having two independent molding spaces 334. The multiple molding spaces 334 are preferably in the shape of a shoe body.

[0048] See Figure 2 and Figure 3 As shown, each of the material control devices 34 has a control unit 341, a stop unit 342 driven by the control unit 341, and a metering unit 343 connected to the control unit 341. The stop unit 342 is located between the feed port 322 and the feed channel 315 of the corresponding injection device 32. In this embodiment, the control unit 341 can control the stop unit 342 to extend and retract, so as to control the communication state between the feed channel 315 and the corresponding injection tube 3221 through the stop unit 342. In addition, the metering unit 343 is located in the injection tube 321 to detect the feed amount and injection amount of a mixture C.

[0049] See Figure 2 , Figure 3 and Figure 6 As shown, in use, the dual-injection molding system 3 first introduces material A into the feed pipe 312 via the hopper 311, while simultaneously introducing supercritical fluid B into the feed pipe 312 via the supply unit 313. During the rotation of the screw 314, material A and supercritical fluid B are uniformly mixed to form mixture C. Mixture C is propelled forward by the screw 314 towards multiple feed channels 315. At this time, the control unit 341 drives the stop unit 342 to shorten, thereby connecting the injection pipe 321 with the feed channels 315, allowing mixture C to enter the injection pipe 321 through the feed port 322. Simultaneously, the needle valve unit 324 seals the injection outlet 323, and the metering unit 343 detects the amount of mixture C entering the injection pipe 321 and transmits this information back to the control unit 341. (See reference...) Figure 4 and Figure 5As shown, when the injection tube 321 is filled with enough mixture C, the control unit 341 drives the stop unit 342 to extend, so that the injection tube 321 is not connected to the feed channel 315, thereby stopping the feeding operation of the mixture C.

[0050] See Figure 4 and Figure 7 As shown, the top mold unit 333 then pushes the lower mold 332, causing the lower mold 332 and the upper mold 331 to close together and form multiple molding spaces 334. Then, the control unit 341 drives the needle valve unit 324 to move away from the injection port 323, allowing the mixture C to enter the corresponding molding space 334 in a straight line through the injection port 323. This avoids obstruction of the mixture C during transport and ensures uniform transport pressure. Simultaneously, the metering unit 343 detects the injection volume of the mixture C into the molding space 334 and transmits this injection volume information back to the control unit 341. (See reference...) Figure 8 As shown, when the molding space 334 is filled with sufficient mixture C, the control unit 341 drives the needle valve unit 324 to block the injection outlet 323 to stop the injection of mixture C. Of course, the control unit 341 can also control the degree to which the needle valve unit 324 blocks the injection outlet 323 based on the injection volume information, thereby controlling the injection volume and injection speed of mixture C. This is to facilitate precise control and adjustment of the amount of mixture C injected by each injection device 32 into the clamping device 33, and to ensure that multiple molding spaces 334 receive sufficient amount of mixture C. It also solves the problem of uneven discharge and incomplete filling caused by the screw 314 during the feeding process.

[0051] Continuing from the previous description, the gas is extracted from the multiple molding spaces 334 by the intake and exhaust device 35, so that the mixture C in the multiple molding spaces 334 can be stably foamed and molded into different objects (not shown in the figure). This can effectively improve the molding quality and yield of the multiple objects. When the mixture C is not injected into the multiple molding spaces 334, the intake and exhaust device 35 will input gas into the multiple molding spaces 334 to maintain a constant pressure. Of course, the multiple injection devices 32 can also be filled with mixture C of different components according to the actual use, or the needle valve unit 324 can be linked by the control unit 341 to inject the filled mixture C into the corresponding molding space 334 at different times to improve the variability of use.

[0052] In summary, the dual-injection molding system of the present invention controls the corresponding stop unit and needle valve unit through the control unit of the material quantity control device. The stop unit controls the connection between the corresponding injection pipe and the feed pipe, and the needle valve unit seals the corresponding injection outlet to different degrees. This accurately controls and adjusts the feed and injection volume of the mixture to avoid uneven material output and incomplete filling, thereby effectively improving the subsequent molding quality and yield.

[0053] The above description is only for illustrating preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the specification of the present invention should still fall within the scope of the patent of the present invention.

Claims

1. A dual-injection molding system, comprising a feeding device, two injection devices respectively connected to the feeding device, and a clamping device connected to a plurality of the injection devices; wherein, The feeding device has a hopper for storing material, a feeding pipe connected to the hopper, a supply unit connected to the feeding pipe, and a screw disposed in the feeding pipe. Each injection device has an injection pipe, and an inlet and an outlet respectively opened in the injection pipe. The clamping device has an upper mold connected to the outlet of each injection device, a lower mold opposite to the upper mold, a top mold unit connected to the lower mold, and a molding space enclosed when the upper mold and the lower mold are closed. Its characteristic is that: The supply unit is used to input a supercritical fluid for use as a physical foaming agent, so that the supercritical fluid and the material are mixed by the screw in the feed pipe to form a mixture. In addition, each injection pipe is arranged in a straight line and is equipped with a needle valve unit to control the injection amount of the mixture being linearly delivered to the molding space. A material quantity control device is provided between each injection device and the feeding device. The material quantity control device has a control unit connected to the needle valve unit and a stop unit linked to the control unit to control the feeding and injection operations of the mixture.

2. The dual-injection molding system according to claim 1, characterized in that, Each of the material quantity control devices has a metering unit connected to the control unit.

3. The dual-injection molding system according to claim 1, characterized in that, The clamping device is connected to an air intake and exhaust device to maintain constant pressure and stable foaming within the molding space.

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