Gas-assisted molding plastic injection mold and use method thereof

Abstract

The invention discloses a gas-assisted molding plastic injection mold and a use method, and relates to the technical field of injection molds. The mold comprises a static mold, a movable mold, a cavity, an injection molding pipe and a nitrogen pipeline, the static mold is sequentially provided with a bottom mold frame, a flat cable plastic frame, a heat insulation positioning frame and a top mold frame from outside to inside, an electric flat cable is installed on the flat cable plastic frame, an electric heating module is installed on the outer side of the bottom mold frame, and a heating module is arranged in the heat insulation positioning frame. The heating surface of the heating module is coated with a heat-conducting silicone grease layer and directly faces the unit heat absorption area on the top mold frame, and a ceramic heat insulation plate is embedded in the top mold frame. During use, the mold is firstly closed, molten plastic raw materials are injected, then the unit heat absorption area is pertinently heated through the electric heating module and the heating module, heat preservation is conducted through the ceramic heat insulation plate, then high-pressure gas is injected to assist filling and pressure maintaining, and a product is taken out after cooling and mold opening are conducted after exhausting. Accurate heating and efficient heat insulation are achieved, and the problems that a traditional mold is unbalanced in gas distribution, poor in melt state and fluctuating in temperature are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of injection molding, in particular to a gas-assisted forming plastic injection mold and a use method thereof. BACKGROUND

[0002] In the field of gas-assisted forming plastic injection, traditional molds and processes have long faced three major technical problems, which have seriously restricted product quality and application range.

[0003] First, the problem of uneven gas distribution caused by uneven product wall thickness is prominent: traditional gas-assisted injection molds lack targeted temperature control mechanisms. When there is a difference in product wall thickness, high-pressure gas is easy to quickly penetrate in the thin-walled area, while the thick-walled area has a fast cooling speed of the melt and a decrease in flowability, which makes it difficult for the gas to fully push the melt to fill, resulting in local structural defects and insufficient density, and ultimately a significant decrease in the mechanical properties of the product, making it difficult to apply to scenarios requiring strength.

[0004] Second, the rough heating method leads to poor melt state: existing molds mostly use overall heating mode, which cannot accurately supplement heat according to the forming needs of different areas of the product, resulting in uneven temperature distribution of the melt at different positions in the cavity, poor flowability of the melt in the thick-walled area, large filling resistance, and rapid cooling of the melt in the thin-walled area, which further aggravates the forming defects.

[0005] Third, poor heat insulation effect of the mold causes temperature fluctuations: the heat insulation structure of the traditional mold is simple, and heat is easily lost quickly through the mold body, making it difficult to maintain a stable temperature in the cavity, and the cooling speed of the melt is inconsistent, which can cause the product to shrink and deform, and the size precision to deviate, etc. At the same time, temperature fluctuations also affect the interaction between high-pressure gas and melt, reducing filling uniformity, and ultimately affecting the appearance quality and use reliability of the product.

[0006] These problems have long plagued the industry, and there is an urgent need for a mold and process solution that combines precise heating, efficient heat insulation, and gas-assisted cooperation to solve them. SUMMARY

[0007] To solve the above technical problems, the present application is realized by the following technical solutions: The application provides a plastic injection mold for gas-assisted forming, comprising a static mold, a dynamic mold, a mold cavity between the static mold and the dynamic mold, an injection tube matched with the mold cavity, and a nitrogen tube connected with the tube head of the injection tube. The static mold is sequentially provided with a bottom mold frame, a wire arranging and molding frame, a heat insulation positioning frame and a top mold frame from outside to inside. The wire arranging and molding frame is embedded with electric wires on the side facing the bottom mold frame, and the bottom mold frame is provided with an electric heating module electrically connected with the electric wires on the outside. The heat insulation positioning frame is embedded with a plurality of heating modules electrically connected with the electric wires, the heating surfaces of the heating modules face the top mold frame, and the heating surfaces of the heating modules are coated with a heat-conducting silicone grease layer in contact with the top mold frame. The top mold frame is embedded with a plurality of ceramic heat insulation plates on the side facing the heat insulation positioning frame, the plate blocks of the top mold frame between two adjacent ceramic heat insulation plates form a unit heat absorption area, and the heating surface of one heating module is right in the middle of one unit heat absorption area.

[0008] As a preferred technical scheme of the injection mold, the dynamic mold is provided with an injection port matched with the mold cavity, and the front end nozzle of the injection tube is matched and installed at the injection port.

[0009] As a preferred technical scheme of the injection mold, the bottom mold frame is provided with a wire harness through slot, and the electric wires comprise an external connecting wire penetrating through the wire harness through slot, and the external connecting wire is provided with a wire plug at one end, and the wire plug is electrically connected with the electric heating module.

[0010] As a preferred technical scheme of the injection mold, the wire arranging and molding frame is provided with a wire slot on the side facing the bottom mold frame, and the electric wires are embedded and installed at the wire slot.

[0011] As a preferred technical scheme of the injection mold, the electrode column is provided with a plurality of pairs of electrode columns, the wire arranging and molding frame is provided with column holes matched with the electrode columns, the heating module is provided with electric contact points aligned with the column holes on the side facing the wire arranging and molding frame, and one end of the electrode column penetrates through the column hole and abuts against the electric contact point of the heating module.

[0012] As a preferred technical scheme of the injection mold, the cross section of the ceramic heat insulation plate is in isosceles trapezoidal structure, the top mold frame is provided with a plurality of heat insulation grooves, and the ceramic heat insulation plate is embedded and installed at the heat insulation groove.

[0013] As a preferred technical scheme of the injection mold, the heat insulation groove is provided with a high-temperature-resistant rubber pad on the inner wall, and the ceramic heat insulation plate is in extrusion contact with the high-temperature-resistant rubber pad.

[0014] The application provides a use method of the plastic injection mold for gas-assisted forming. Link one, start the mold control system, perform the mold closing operation, accurately close the static mold and the dynamic mold, and form a sealed mold cavity.

[0015] Link two, inject a certain amount of molten plastic raw materials into the mold cavity through the injection tube, and ensure that the raw materials meet the capacity requirements of the mold cavity.

[0016] Step three, start the electric heating module, supply power to the heating module through the electric wire, and start the heating program.

[0017] Step four, the heating module conducts heat to the corresponding unit heat absorption area through the heat-conducting silicone grease layer, and implements targeted heating.

[0018] Step five, use the ceramic heat insulation plate to block heat dissipation and maintain the temperature stability of the unit heat absorption area to optimize the melt state.

[0019] Step six, open the nitrogen pipeline, inject high-pressure gas into the cavity to assist filling, maintain the high-pressure gas pressure state, cooperate with the heating module to regulate the temperature, and ensure that the product is fully formed.

[0020] Step seven, after reaching the preset time, close the nitrogen pipeline and perform the exhaust operation on the cavity to release the pressure in the cavity.

[0021] Step eight, turn off the electric heating module to stop heating, let the product cool naturally in the cavity, and start the mold opening mechanism to separate the static mold and the dynamic mold when the product is cooled to an appropriate temperature.

[0022] Compared with the existing technology, the beneficial effects of the present application are: The present application implements targeted heating for the product thickness difference area through the precise layout of "one heating module corresponding to one unit heat absorption area", cooperates with high-pressure gas assisted filling, avoids gas distribution imbalance, ensures that the thick wall area is fully formed, and reduces the problem of local unformed.

[0023] The present application makes the plastic melt uniformly fill the cavity through the synergistic effect of temperature regulation and high-pressure gas pressure maintenance, reduces internal stress and structural defects, and significantly improves the mechanical properties of the product. At the same time, the ceramic heat insulation plate effectively blocks heat dissipation, the heat-conducting silicone grease layer improves the heat conduction efficiency of the heating module and the top die frame, and the temperature of the unit heat absorption area is double-protected to be constant, which optimizes the melt flowability and state and avoids the forming defects caused by temperature fluctuations. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is the overall structure schematic diagram of the mold of the present application.

[0025] Figure 2 It is Figure 1 The structure schematic diagram of the local enlargement of A in the middle.

[0026] Figure 3 It is Figure 2 The structure schematic diagram of the local enlargement of B in the middle.

[0027] Figure 4 It is the component disassembly structure schematic diagram of the mold of the present application.

[0028] Figure 5 As Figure 4 Structure schematic diagram of local amplification at C.

[0029] Figure 6 As Figure 4 Structure schematic diagram of local amplification at D.

[0030] Figure 7 As Figure 4 Structure schematic diagram of local amplification at E.

[0031] Wherein: 1 - static die, 101 - bottom die frame, 1011 - wire harness through slot, 102 - electric wire, 1021 - external wire, 1022 - electrode column, 1023 - wire harness plug, 103 - wire harness plastic frame, 1031 - wire slot, 1032 - column hole, 104 - heat insulation positioning frame, 1041 - heating module, 1042 - heat-conducting silicone layer, 1043 - electrical contact point, 105 - top die frame, 1051 - heat insulation groove, 1052 - high-temperature-resistant rubber pad; 2 - moving die, 201 - injection port; 3 - cavity; 4 - injection tube; 5 - nitrogen pipeline; 6 - ceramic heat insulation plate; 7 - electric heating module; M - unit heat absorption area. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0033] Example one, a gas-assisted forming plastic injection mold is designed in the present application, the mold mainly consists of static die 1, moving die 2, cavity 3, injection tube 4, nitrogen pipeline 5 and matching heating, heat insulation components, the details of each structure are as follows: In combination with Figure 1 , Figure 4 The static die 1 is assembled from outside to inside in turn by the bottom die frame 101, the wire harness plastic frame 103, the heat insulation positioning frame 104 and the top die frame 105, and each component cooperates to realize the functions of heating, heat insulation and circuit conduction.

[0034] In combination with Figure 1 , Figure 4 , Figure 5 The bottom die frame 101 is provided with a wire harness through slot 1011 for penetrating the external wire 1021 of the electric wire 102. The electric heating module 7 is installed on the outside of the bottom die frame 101, and the electric heating module 7 is electrically connected with the wire harness plug 1023 of the electric wire 102 to provide power input for overall heating.

[0035] In combination with Figure 4 , Figure 6The wire slot 1031 is arranged on one side of the wire plastic frame 103 facing the bottom mold frame 101, and the wire slot 1031 is used for embedding and installing the electric wire 102. The wire plastic frame 103 is provided with a column hole 1032 matched with the electrode column 1022, and the column hole 1032 provides a channel for the electric connection of the electrode column 1022 and the heating module 1041.

[0036] In combination Figure 1 , Figure 3 , Figure 4 , Figure 5 , Figure 6 The electric wire 102 is embedded and installed in the wire slot 1031 of the wire plastic frame 103, and the electric wire 102 includes an external connecting wire 1021, a plurality of pairs of electrode columns 1022, and a wire plug 1023. The external connecting wire 1021 penetrates through the wire harness through slot 1011 of the bottom mold frame 101, the wire plug 1023 is exposed outside the bottom mold frame 101 and connected with the electric heating module 7. One end of the electrode column 1022 penetrates through the column hole 1032 of the wire plastic frame 103, and abuts against and is in conduction with the electric contact point 1043 of the heating module 1041.

[0037] In combination Figure 2 , Figure 3 , Figure 4 The heat insulation positioning frame 104 is embedded with a plurality of heating modules 1041, and the heating modules 1041 are electrically connected with the electric wire 102. The heating surface of the heating module 1041 faces the top mold frame 105, and the heating surface is coated with a heat-conducting silicone grease layer 1042, which is in close contact with the top mold frame 105, thereby improving the heat conduction efficiency. The heating module 1041 is provided with an electric contact point 1043 on one side facing the wire plastic frame 103, which cooperates with the electrode column 1022 to realize electrical connection.

[0038] In combination Figure 2 , Figure 4 , Figure 7 The top mold frame 105 is embedded and installed with a plurality of ceramic heat insulation plates 6 on one side facing the heat insulation positioning frame 104, and the top mold frame 105 is provided with a plurality of heat insulation grooves 1051, and the ceramic heat insulation plates 6 are embedded and installed in the heat insulation grooves 1051. The inner wall of the heat insulation groove 1051 is provided with a high-temperature-resistant rubber pad 1052, and the ceramic heat insulation plate 6 is in extrusion contact with the high-temperature-resistant rubber pad 1052 (the high-temperature-resistant rubber pad 1052 has a high thermal expansion coefficient, and after being heated, it enhances the fastening connection between the ceramic heat insulation plate 6 and the top mold frame 105, and avoids the micro-deformation of the top mold frame 105 under the action of high air pressure). The plate blocks of the top mold frame 105 between two adjacent ceramic heat insulation plates 6 form a unit heat absorption area M, and the heating surface of one heating module 1041 is opposite to the middle position of one unit heat absorption area M. The cross section of the ceramic heat insulation plate 6 is in isosceles trapezoidal structure, which is embedded in the heat insulation groove 1051 of the top mold frame 105, and is used for blocking the heat conduction of the unit heat absorption area M to the outside, thereby maintaining the temperature stability.

[0039] In combinationFigure 1 The moving mold 2 has an injection port 201 that communicates with the cavity 3. The injection port 201 is used to fit the front nozzle of the injection tube 4. The cavity 3 is located between the stationary mold 1 and the moving mold 2. It is a closed space for molding plastic raw materials. Molding is achieved by injecting raw materials through the injection tube 4 and injecting high-pressure gas through the nitrogen pipeline.

[0040] Combination Figure 1 The nozzle at the front end of the injection tube 4 is inserted into the injection port 201 of the moving mold 2, and is connected to the cavity 3 to inject molten plastic material into the cavity 3. The tube end of the injection tube 4 is also connected to the nitrogen pipeline 5 to provide a channel for high-pressure gas injection.

[0041] Example 2: The installation method of the plastic injection mold of the present invention is as follows: First, according to the product specifications, a suitable heat insulation groove 1051 is opened at the corresponding position on the top mold frame 105, and a high-temperature resistant rubber pad 1052 is installed on the inner wall of the heat insulation groove 1051 to ensure that the high-temperature resistant rubber pad 1052 fits tightly with the inner wall of the heat insulation groove 1051.

[0042] Second, the ceramic heat insulation plate 6 is embedded into the heat insulation groove 1051 of the top mold frame 105. The ceramic heat insulation plate 6 is initially fixed by the squeezing action of the high temperature resistant rubber pad 1052, so that a unit heat absorption area M of a preset size is formed between adjacent ceramic heat insulation plates 6 (the size of the unit heat absorption area M can be adjusted according to product requirements to achieve targeted heat compensation).

[0043] Third, embed the electrical flat cable 102 into the wire groove 1031 on the side of the flat cable frame 103 facing the bottom mold frame 101, ensuring that the electrode post 1022 of the electrical flat cable 102 is aligned with the post hole 1032 on the flat cable frame 103. At the same time, pass the external wire 1021 of the electrical flat cable 102 through the wire harness through groove 1011 of the bottom mold frame 101, so that the flat cable plug 1023 is exposed on the outside of the bottom mold frame 101. Install the heating module 7 on the outside of the bottom mold frame 101 and electrically connect the heating module 7 to the flat cable plug 1023 of the electrical flat cable 102.

[0044] Fourth, fit the assembled cable tray 102 plastic frame 103 with the bottom mold frame 101 to ensure that the cable tray 102 is securely embedded in the cable groove 1031 without any loosening or displacement.

[0045] Fifth, install the heating module 1041 inside the heat insulation positioning frame 104, ensuring that the electrical contact point 1043 of the heating module 1041 facing the cable frame 103 corresponds to the position of the post hole 1032 of the cable frame 103. Then, precisely align the heat insulation positioning frame 104 with the cable frame 103, so that one end of the electrode post 1022 passes through the post hole 1032 and abuts against the electrical contact point 1043 of the heating module 1041 to conduct electricity.

[0046] Sixth, a thermally conductive silicone grease layer 1042 is uniformly coated on the heating surface of the heating module 1041, and then the top mold frame 105 is assembled with the heat insulation positioning frame 104 to ensure that the heating surface of each heating module 1041 is directly opposite the center of a unit heat absorption area M, and that the thermally conductive silicone grease layer 1042 is in close contact with the top mold frame 105.

[0047] Finally, check if the injection port 201 of the moving mold 2 is unobstructed. Insert the nozzle of the injection tube 4 into the injection port 201 of the moving mold 2 to ensure good communication between the injection tube 4 and the cavity 3. At the same time, connect the nitrogen line 5 to the end of the injection tube 4 to ensure that the connection is sealed and leak-free.

[0048] Then, the static mold 1 and the moving mold 2 are closed and debugged to ensure that the cavity 3 is well sealed after the mold is closed, the assembly gap of each component meets the requirements, the electrical connection is reliable, the pipeline is unobstructed, and the installation of the entire mold is completed.

[0049] Example 3: The method of using the plastic injection mold of the present invention is as follows: First, mold closing preparation: start the mold control system and perform the mold closing operation to make the stationary mold 1 and the moving mold 2 close precisely to form a closed cavity 3.

[0050] The second step is material injection: a certain amount of molten plastic material is injected into the cavity 3 through the injection tube 4 to ensure that the amount of material injected is appropriate for the capacity requirements of the cavity 3.

[0051] The third step is targeted heating: Before opening the nitrogen pipeline 5, the electric heating module 7 is activated, and power is supplied to the heating module 1041 through the power cable 102. The heating module 1041 starts working and provides targeted heating to its corresponding unit heat absorption zone M. At the same time, the ceramic heat insulation plates 6 on both sides of the unit heat absorption zone M prevent heat from being conducted outward, maintain the temperature stability of the unit heat absorption zone M, optimize the melt temperature distribution, and improve the melt fluidity.

[0052] Step 4, gas-assisted molding: After the melt reaches the preset flow state in the cavity 3, open the nitrogen pipeline 5 and inject high-pressure gas into the cavity 3. Use the gas pressure to assist the melt to fill the cavity 3 evenly and make up for the molding defects caused by uneven product wall thickness.

[0053] Step 5, Pressure Holding and Cooling: Maintain high-pressure gas for a period of time, coordinating with the temperature control of heating module 1041 to ensure the product is fully formed and improve its mechanical properties. Then, close nitrogen line 5 and perform venting operation in cavity 3 to release the pressure inside the cavity. Turn off heating module 7 to stop heating, allowing the product to cool naturally within cavity 3 or through the mold's built-in cooling structure.

[0054] Finally, after the product cools to a suitable temperature, the mold opening mechanism is activated to separate the stationary mold 1 from the moving mold 2. The molded product is then removed through the preset ejection structure or manually. After the product is removed, the cavity 3, injection pipe 4, nitrogen pipeline 5, and other pipelines are cleaned and tidied to remove any residual plastic debris or impurities, in preparation for the next injection molding.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gas-assisted forming plastic injection mold, comprising a static mold (1), a dynamic mold (2), a mold cavity (3) between the static mold (1) and the dynamic mold (2), and an injection tube (4) in communication with the mold cavity (3), wherein a tube head of the injection tube (4) is further connected with a nitrogen pipeline (5), and characterized in that: the static mold (1) is sequentially provided with a bottom mold frame (101), a wire arranging mold frame (103), a heat insulation positioning frame (104), and a top mold frame (105) from outside to inside; the wire arranging mold frame (103) is embeddedly provided with an electric wire (102) on a side facing the bottom mold frame (101), and the bottom mold frame (101) is externally provided with an electric heating module (7) electrically connected with the electric wire (102); the heat insulation positioning frame (104) is embeddedly provided with a plurality of heating modules (1041) electrically connected with the electric wire (102), a heating surface of the heating module (1041) faces the top mold frame (105), and the heating surface of the heating module (1041) is coated with a heat-conducting silicone grease layer (1042) in contact with the top mold frame (105); the top mold frame (105) is embeddedly provided with a plurality of ceramic heat insulation plates (6) on a side facing the heat insulation positioning frame (104), and a plate block of the top mold frame (105) between two adjacent ceramic heat insulation plates (6) forms a unit heat absorption area (M); and a heating surface of one heating module (1041) is opposite to a central position of one unit heat absorption area (M).

2. The gas-assisted forming plastic injection mold according to claim 1, characterized in that: the dynamic mold (2) is provided with an injection port (201) in communication with the mold cavity (3), and a front end nozzle of the injection tube (4) is fitted and installed at a position of the injection port (201).

3. The gas-assisted forming plastic injection mold according to claim 1, characterized in that: the bottom mold frame (101) is provided with a wire harness through slot (1011), the electric wire (102) comprises an external connecting wire (1021) penetrating through the wire harness through slot (1011), one end of the external connecting wire (1021) is provided with a wire arranging plug (1023), and the wire arranging plug (1023) is electrically connected with the electric heating module (7).

4. The gas-assisted forming plastic injection mold according to claim 1, characterized in that: a wire slot (1031) is provided on a side of the wire arranging mold frame (103) facing the bottom mold frame (101), and the electric wire (102) is embeddedly installed at a position of the wire slot (1031).

5. The gas-assisted forming plastic injection mold according to claim 1, characterized in that: the electric wire (102) is provided with a plurality of pairs of electrode columns (1022), the wire arranging mold frame (103) is provided with column holes (1032) matched with the electrode columns (1022); the heating module (1041) is provided with electric contact points (1043) aligned with the column holes (1032) on a side facing the wire arranging mold frame (103); and one end of the electrode column (1022) penetrates through the column hole (1032) and abuts against the electric contact point (1043) of the heating module (1041). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6. The gas-assisted forming plastic injection mold of claim 1, wherein: The cross section of the ceramic heat insulation plate (6) is isosceles trapezoidal structure, the top die frame (105) is provided with a plurality of heat insulation grooves (1051), and the ceramic heat insulation plate (6) is embedded and installed at the position of the heat insulation groove (1051).

7. The gas-assisted forming plastic injection mold of claim 6, wherein: The inner wall of the heat insulation groove (1051) is provided with a high-temperature-resistant rubber pad (1052), and the ceramic heat insulation plate (6) is in extrusion contact with the high-temperature-resistant rubber pad (1052).

8. A method of using a gas assisted molding plastic injection mold, characterized in that, The gas-assisted forming plastic injection mold of any one of claims 1 to 7 comprises the following contents: Link one, start the mold control system and perform the mold closing operation to make the static mold (1) and the dynamic mold (2) accurately closed to form a closed cavity (3); Link two, inject a certain amount of molten plastic raw materials into the cavity (3) through the injection pipe (4) to ensure that the raw materials meet the capacity requirements of the cavity (3); Link three, start the electric heating module (7) and supply power to the heating module (1041) through the electric wire (102) to start the heating program; Link four, the heating module (1041) conducts heat to the corresponding unit heat absorption area (M) through the heat-conducting silicone grease layer (1042) to implement targeted heating; Link five, use the ceramic heat insulation plate (6) to block heat loss and maintain the temperature stability of the unit heat absorption area (M) to optimize the melt state; Link six, open the nitrogen gas pipeline (5) to inject high-pressure gas into the cavity (3) to assist filling, maintain the high-pressure gas pressure state, cooperate with the heating module (1041) to regulate the temperature, and ensure that the product is fully formed; Link seven, after reaching the preset time, close the nitrogen gas pipeline (5) to perform the exhaust operation on the cavity (3) to release the pressure in the cavity; Link eight, turn off the electric heating module (7) to stop heating, let the product naturally cool in the cavity (3), and when the product is cooled to an appropriate temperature, start the mold opening mechanism to separate the static mold (1) and the dynamic mold (2) and take out the formed product.

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