Mold structure for preventing gas backflow in injection molding process and injection mold

Abstract

The utility model discloses a mould structure and injection mould for preventing gas backflow in the injection molding process, including upper mould core, lower mould core and pouring system, the upper mould core and lower mould core butt joint with each other and enclose to form the cavity of injection mould product, the pouring system is used for injecting molten plastics into the cavity, and the pouring system is used for pouring the molten plastics into the injection mould product. After cooling, forming a mold product; the upper mold core is provided with a first groove, the lower mold core is provided with a second groove, and the first groove and the second groove are in butt joint with each other to define a runner system, so that molten plastic flows in the runner system and is injected into a cavity; and an air blowing assembly is further arranged in the runner system, and the air blowing assembly is used for conducting air blowing operation on the mold product which is not completely cooled, so that a plastic product with the hollow interior is formed. In conclusion, the blow molding operation can be smoothly carried out in the injection molding process, so that the hollow design is formed in the thin plastic product, the injection molding raw materials are saved, and the production cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of an air blowing process of an injection mold, in particular to a mold structure and an injection mold for preventing gas backflow during the injection molding process. Background Art

[0002] Traditional injection blow molding is a method in which the bottom-closed parison is first formed by an injection molding machine, and then the parison is moved into a blow molding mold and compressed air is blown into it to form the product. The products produced by this method are accurate in size and high in precision because the mouth is injection molded, and no trimming is required; there is no cut-off mouth at the bottom, so the strength is also good, and a bottle with excellent appearance can be obtained. In addition, there is less material loss, which is suitable for mass production of the same product. However, the equipment cost is high, and it is suitable for manufacturing narrow-mouth bottles, factory-mouth bottles for medicines, etc.

[0003] Injection molding is the process of heating and melting plastic particles, injecting them into the mold for filling, and then solidifying them through cooling. Blow molding is the process of placing heated plastic particles into a mold, and then using compressed air to blow them into an air-tight cavity, while keeping them in a certain shape and size.

[0004] Due to the differences in principles and processes, the products produced by injection molding and blow molding are also very different. Injection molding can produce various shapes, not only thin-walled utensils, but also complex plastic products such as plastic gears and electrical housings. The products produced by blow molding are mainly some thin-walled containers, such as bottles, barrels, faucets, etc.

[0005] A Chinese patent document with the announcement number CN219748891U discloses a new blow molding mold, including a molding mold, the number of the molding molds is two, a molding cavity is opened on one side of the molding mold, and a cooling mechanism is arranged on the top of the molding mold; the cooling mechanism includes a cooling cavity, the cooling cavity is arranged inside the molding mold, the top of the molding mold is fixedly connected with a liquid storage tank, one side of the liquid storage tank is fixedly connected with a connecting pipe, and one end of the connecting pipe is fixedly connected with a control valve. The new blow molding mold is provided with a cooling mechanism, two molding molds are molded together, and then blow molding is performed. After the blow molding is completed, the control valve is opened so that the coolant in the liquid storage tank enters the cooling cavity. The molding mold is made of heat-conducting material. At this time, the coolant will cool the blow molded part, thereby achieving the effect of cooling the blow molded part, thereby increasing the processing efficiency.

[0006] Directly performing blow molding during the injection molding process to produce injection molded products with an internal hollow design is a current research focus in the industry. However, blowing directly into the injection molding cavity can easily blow the molten plastic back into the nozzle or barrel of the casting system, affecting subsequent injection molding operations. Utility Model Content

[0007] The utility model aims to overcome the above-mentioned shortcomings and provide a technical solution that can solve the above-mentioned problems.

[0008] The utility model provides a mold structure for preventing gas backflow during an injection molding process, comprising an upper mold core, a lower mold core and a pouring system, wherein the upper mold core and the lower mold core are butted against each other to form a mold cavity for an injection mold product after being enclosed, and the pouring system is used to inject molten plastic into the mold cavity to form a mold product after being cooled; the upper mold core is provided with a first groove, and the lower mold core is provided with a second groove, the first groove and the second groove are butted against each other to form a flow channel system, so that the molten plastic can flow in the flow channel system and then be injected into the mold cavity; a blowing component is also provided in the flow channel system, and the blowing component is used to perform a blowing operation on the mold product that has not been completely cooled to form a plastic product with a hollow interior.

[0009] As a further solution of the utility model: an auxiliary structure is also provided in the runner system, and the auxiliary structure is located in the runner between the blowing assembly and the pouring system. The auxiliary structure is used to reduce the cross-sectional area of ​​the runner system, thereby reducing the wall thickness of the molten plastic at the auxiliary structure, so that it can be cooled quickly to form a plastic blockage to block the gas.

[0010] As a further solution of the utility model: the auxiliary structure is provided with a first protrusion and a second protrusion, the first protrusion is fixedly connected to the inside of the first groove, and the second protrusion is fixedly connected to the inside of the second groove; when the first groove and the second groove are coupled with each other to form a flow channel system, the first protrusion and the second protrusion are synchronously coupled with each other to form an auxiliary structure with a certain gap space.

[0011] As a further solution of the utility model: the runner system is provided with a first branch runner and a second branch runner, and the first branch runner and the second branch runner respectively inject molten plastic into the mold cavity from both ends; the auxiliary structure is provided with a first structure and a second structure, the first structure is located inside the first branch runner, thereby blocking the gas in the first branch runner; the second structure is located inside the second branch runner, thereby blocking the gas in the second branch runner.

[0012] As a further solution of the utility model: the runner system is also provided with a first gate and a second gate, the first gate and the second gate are respectively located at one end of the injection cavity where the first branch channel and the second branch channel connect to the injection cavity, and are used to inject molten plastic into the cavity; the blowing assembly is provided with a first air needle and a second air needle, the first air needle is located in the first branch channel close to the first gate, so that gas is injected into the uncooled plastic product through the first gate to form a plastic product with a hollow interior; the second air needle is located in the second branch channel close to the second gate, so that gas is injected into the uncooled plastic product through the second gate to form a plastic product with a hollow interior.

[0013] As a further solution of the utility model: the first gate and the second gate are respectively located in the middle of the injection cavity in the thickness direction, and air is blown from the middle of the mold product in the thickness direction to form a plastic product with a hollow interior.

[0014] As a further solution of the utility model: the flow channel system is further provided with a first cold material hole and a second cold material hole, the first cold material hole is located at the end of the first branch flow channel, and the second cold material hole is located at the end of the second branch flow channel.

[0015] The utility model also provides an injection mold, comprising any one of the above-mentioned mold structures for preventing gas backflow during the injection molding process, and also comprising a mold frame system, a cooling system and an ejection system.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] 1. By directly setting a blowing component inside the runner system, the mold product that has not been completely cooled can be blown, so that it can smoothly form a plastic product with a hollow interior, so that relatively thin plastic products can be injection molded. At the same time, the structure of the injection molding cavity is optimized so that it can adapt to different shapes, solving the problem that only thin-walled containers can be produced in blow molding production.

[0018] 2. An auxiliary structure is also set in the runner system to assist the runner system between the blowing component and the pouring system, so as to reduce the cross-sectional area of ​​the runner, help the molten plastic to cool quickly, and form a plastic blockage to block the gas, thereby avoiding the gas backflow during the blowing process, causing the molten plastic to flow back into the nozzle or barrel, affecting the subsequent injection molding operation.

[0019] Therefore, after the above-mentioned improvements, the utility model can provide a mold structure and an injection mold that prevent gas backflow during the injection molding process, so that the blow molding operation can be carried out smoothly during the injection molding process, thereby forming an internal hollow design in the thin plastic product, thereby saving injection molding raw materials and reducing production costs.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 It is a structural schematic diagram of the upper die core and the lower die core of the utility model being butted together;

[0023] Figure 2 It is a structural schematic diagram of the upper mold core of the utility model;

[0024] Figure 3 It is a structural schematic diagram of the lower die core of the utility model;

[0025] Figure 4 It is a structural schematic diagram of the flow channel system and auxiliary structure of the utility model;

[0026] Figure 5 It is a schematic diagram of the structure of the gap space of the utility model;

[0027] Figure 6 It is a structural schematic diagram of the plastic plugging part of the utility model.

[0028] The reference numerals and names in the figures are as follows:

[0029] 10 upper mold core; 11 first groove; 20 lower mold core; 21 second groove; 30 runner system; 31 first branch runner; 32 second branch runner; 33 first gate; 34 second gate; 35 first cold material hole; 36 second cold material hole; 40 auxiliary structure; 41 gap space; 42 first protrusion; 43 second protrusion; 50 blowing assembly; 51 first air needle; 52 second air needle; 60 casting system; 61 nozzle; 70 plastic product; 71 internal hollow; 72 plastic plugging part; 73 sprue piece. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figures 1 to 6 In an embodiment of the utility model, a mold structure for preventing gas backflow during injection molding comprises an upper mold core 10, a lower mold core 20 and a pouring system 60. The upper mold core 10 and the lower mold core 20 are butted against each other to form a cavity of an injection mold product after being enclosed. The pouring system 60 is used to inject molten plastic into the cavity to form a mold product after cooling. The upper mold core 10 is provided with a first groove 11, and the lower mold core 20 is provided with a second groove 21. The first groove 11 and the second groove 21 are butted against each other to form a runner system 30, so that the molten plastic can flow in the runner system 30 and then be injected into the cavity. A blowing assembly 50 is also provided in the runner system 30. The blowing assembly 50 is used to perform a blowing operation on a mold product that has not been completely cooled to form a plastic product 70 with an internal hollow 71.

[0032] Specifically, the improved mold structure of the utility model can be used in an injection mold, including a mold structure, a mold frame system, a cooling system and an ejection system. In order to form an injection cavity, the cooperation of the upper mold core 10 and the lower mold core 20 is also required so that when the mold is closed, they can enclose and form a closed injection space. The corresponding molten liquid is poured into the injection space by the pouring system 60, and after cooling by the cooling system, the plastic product 70 is formed. The upper mold core 10 and the lower mold core 20 can be connected to the mold frame system and follow it to open or close the mold. The ejection system can eject the cooled plastic product 70, so that the injection cavity can be used for the next injection operation.

[0033] Secondly, in order to complete the production of the internal hollow 71 of the mold product, a blowing assembly 50 can also be provided, and the blowing assembly 50 is used to inject high-pressure nitrogen into the cavity, so that a hollow space is formed inside the mold product that has not been completely cooled and finalized, and the actual production of the corresponding designed product is realized. It can be understood that the blowing system can be connected to an external high-pressure nitrogen supply device through the mold frame system, so as to blow high-pressure nitrogen into the cavity.

[0034] like Figure 2 , Figure 3 and Figure 6 As shown, preferably, an auxiliary structure 40 is further provided in the runner system 30, and the auxiliary structure 40 is located in the runner between the blowing assembly 50 and the casting system 60. The auxiliary structure 40 is used to reduce the cross-sectional area of ​​the runner system 30, thereby reducing the wall thickness of the molten plastic at the auxiliary structure 40, so that it can be cooled quickly to form a plastic plugging portion 72 to block the gas.

[0035] Specifically, the auxiliary structure 40 is fixedly connected to the inside of the runner system 30, preferably fixedly connected to the side wall of the branch runner, and is used to reduce the cross-sectional area of ​​the runner, thereby correspondingly reducing the cross-sectional area of ​​the sprue piece 73 formed during the injection molding process, so that its thinner area can be cooled first, thereby cooling into a solid plastic plugging portion 72, and then blocking the high-pressure nitrogen blown into the blowing assembly 50, preventing the high-pressure gas from blowing the molten plastic that has not been completely cooled and shaped back into the nozzle 61 of the casting system 60, avoiding the problem of affecting production due to blocking the nozzle 61.

[0036] like Figures 3 to 5 As shown, preferably, the auxiliary structure 40 is provided with a first protrusion 42 and a second protrusion 43, the first protrusion 42 is fixedly connected to the inside of the first groove 11, and the second protrusion 43 is fixedly connected to the inside of the second groove 21; when the first groove 11 and the second groove 21 are aligned with each other to form the flow channel system 30, the first protrusion 42 and the second protrusion 43 are synchronously aligned with each other to form an auxiliary structure 40 with a certain gap space 41.

[0037] Specifically, the gap space 41 allows the molten plastic to pass through the auxiliary structure 40 and enter the injection cavity. When cooling, the molten plastic in the gap space 41 is relatively thin, so it can be cooled quickly, forming a solid plastic plugging portion 72 after cooling, thereby blocking the flow channel at the position of the auxiliary structure 40, so that it can block the gas blown out by the blowing component 50, and prevent the gas from flowing back during the blowing process, causing the molten plastic to flow back into the nozzle 61 or the barrel. The first protrusion 42 and the second protrusion 43 can be protrusions pre-set inside the flow channel of the upper mold core 10 and the lower mold core 20, or they can be replaceable protrusions fixed to the inside of the flow channel system 30.

[0038] like Figure 4 As shown, preferably, the runner system 30 is provided with a first branch channel 31 and a second branch channel 32, and the first branch channel 31 and the second branch channel 32 inject molten plastic into the cavity from both ends respectively; the auxiliary structure 40 is provided with a first structure and a second structure, the first structure is located inside the first branch channel 31, thereby blocking the gas in the first branch channel 31; the second structure is located inside the second branch channel 32, thereby blocking the gas in the second branch channel 32.

[0039] Specifically, in this embodiment, since the mold product presents a relatively long shape, it is preferred to inject the molten plastic from both sides, so two left and right runners can be set. Similarly, the auxiliary structure 40 also needs to be provided with a first structure and a second structure respectively, so that it can assist in blocking the left and right runners respectively, so that the high-pressure gas will not enter from the two runners, but blow the completely formed molten plastic back to the inside of the nozzle 61 of the casting system 60 to prevent the nozzle 61 from being blocked. It can be understood that in some other embodiments, or in the production of other mold products, when it is necessary to set up multiple runners, it is also necessary to set up multiple auxiliary structures 40 so that the auxiliary structure 40 can assist in blocking each runner to prevent the high-pressure gas from blowing the molten plastic back to the inside of the nozzle 61, causing blockage and other problems.

[0040] like Figure 4 As shown, preferably, the runner system 30 is further provided with a first gate 33 and a second gate 34, and the first gate 33 and the second gate 34 are respectively located at one end of the injection cavity connecting the first branch channel 31 and the second branch channel 32, and are used to inject molten plastic into the cavity; the blowing assembly 50 is provided with a first air needle 51 and a second air needle 52, and the first air needle 51 is located in the first branch channel 31 close to the first gate 33, so that gas is injected into the uncooled plastic product 70 through the first gate 33 to form a plastic product 70 with an internal hollow 71; the second air needle 52 is located in the second branch channel 32 close to the second gate 34, so that gas is injected into the uncooled plastic product 70 through the second gate 34 to form a plastic product 70 with an internal hollow 71.

[0041] Specifically, when the runner system 30 is provided with two branch runners, that is, when there are multiple gates, multiple air needles are also required to blow air to the gates of the branch runners respectively, so that the mold products that are not completely cooled and formed inside each gate can be blown out of the internal hollow structure 71 by high-pressure nitrogen. In order to improve the blowing effect of the air needle, it is preferred to set the air needle at a position closer to the gate.

[0042] In addition, preferably, the first gate 33 and the second gate 34 are respectively located in the middle of the thickness direction of the injection cavity, and air is blown from the middle of the thickness direction of the mold product to form a plastic product 70 with an internal hollow 71. Specifically, in order to achieve relatively uniform air blowing inside the mold product, especially to ensure that the side walls of the internal hollow 71 of the mold product have relatively the same wall thickness, it is preferred to set the gate in the middle of the thickness direction of the mold product, so as to facilitate the injection of molten plastic and facilitate the air needle to blow air inside the mold product through the gate.

[0043] The flow channel system 30 is further provided with a first cold material well 35 and a second cold material well 36 . The first cold material well 35 is located at the end of the first branch flow channel 31 , and the second cold material well 36 is located at the end of the second branch flow channel 32 .

[0044] Specifically, the cold slug hole is mainly used in the plastic injection molding mold to store the cold slug head generated during the injection interval. It is a structure that prevents the cold slug from entering the cavity and affecting the quality of the plastic part, and allows the molten plastic to smoothly fill the cavity. The cold slug hole is an existing structure in the prior art that is set at the end of the main channel or the branch channel for temporarily storing the front cold slug in the material flow.

[0045] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A mold structure for preventing gas backflow during injection molding, characterized in that: The invention comprises an upper mold core (10), a lower mold core (20) and a casting system (60); the upper mold core (10) and the lower mold core (20) are butt-jointed with each other to form a mold cavity of an injection mold product; the casting system (60) is used to inject molten plastic into the mold cavity to form a mold product after cooling; the upper mold core (10) is provided with a first groove (11), and the lower mold core (20) is provided with a second groove (21); the first groove (11) and the second groove (21) are butt-jointed with each other to form a flow channel system (30) to allow molten plastic to flow in the flow channel system (30) and then be injected into the mold cavity; the flow channel system (30) is also provided with a blowing assembly (50); the blowing assembly (50) is used to blow air into the mold product that has not been completely cooled to form a plastic product (70) with a hollow interior (71).

2. A mold structure for preventing gas backflow during injection molding according to claim 1, characterized in that: The flow channel system (30) is further provided with an auxiliary structure (40), the auxiliary structure (40) being located in the flow channel between the blowing assembly (50) and the casting system (60), the auxiliary structure (40) being used to reduce the cross-sectional area of ​​the flow channel system (30), thereby reducing the wall thickness of the molten plastic at the auxiliary structure (40), allowing it to cool quickly, thereby forming a plastic plugging portion (72) that blocks the gas.

3. A mold structure for preventing gas backflow during injection molding according to claim 2, characterized in that: The auxiliary structure (40) is provided with a first protrusion (42) and a second protrusion (43); the first protrusion (42) is fixedly connected to the inside of the first groove (11), and the second protrusion (43) is fixedly connected to the inside of the second groove (21); when the first groove (11) and the second groove (21) are butted against each other to form a flow channel system (30), the first protrusion (42) and the second protrusion (43) are synchronously butted against each other to form an auxiliary structure (40) with a certain gap space (41).

4. A mold structure for preventing gas backflow during injection molding according to claim 2, characterized in that: The flow channel system (30) is provided with a first branch flow channel (31) and a second branch flow channel (32), and the first branch flow channel (31) and the second branch flow channel (32) respectively inject molten plastic into the mold cavity from two ends; the auxiliary structure (40) is provided with a first structure and a second structure, and the first structure is located inside the first branch flow channel (31) so as to block the gas in the first branch flow channel (31); the second structure is located inside the second branch flow channel (32) so as to block the gas in the second branch flow channel (32).

5. A mold structure for preventing gas backflow during injection molding according to claim 4, characterized in that: The runner system (30) is further provided with a first gate (33) and a second gate (34), the first gate (33) and the second gate (34) being respectively located at one end of the injection cavity where the first branch runner (31) and the second branch runner (32) communicate with each other, and being used to inject molten plastic into the cavity; the blowing assembly (50) is provided with a first air needle (51) and a second air needle (52), the first air needle (51) being located in the first branch runner (31) at a position close to the first gate (33), so that gas is injected into the uncooled plastic product (70) through the first gate (33), so that the plastic product (70) is formed to be hollow inside (71); the second air needle (52) being located in the second branch runner (32) at a position close to the second gate (34), so that gas is injected into the uncooled plastic product (70) through the second gate (34), so that the plastic product (70) is formed to be hollow inside (71).

6. A mold structure for preventing gas backflow during injection molding according to claim 5, characterized in that: The first gate (33) and the second gate (34) are respectively located in the middle of the injection cavity in the thickness direction, and air is blown from the middle of the mold product in the thickness direction to form a plastic product (70) with a hollow interior (71).

7. A mold structure for preventing gas backflow during injection molding according to claim 4, characterized in that: The flow channel system (30) is further provided with a first cold material hole (35) and a second cold material hole (36), wherein the first cold material hole (35) is located at the end of the first branch flow channel (31), and the second cold material hole (36) is located at the end of the second branch flow channel (32).

8. An injection mold, characterized in that: The invention comprises a mold structure for preventing gas backflow during injection molding according to any one of claims 1 to 7, and also comprises a mold frame system, a cooling system and an ejection system.

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