A high-pressure jet combined with negative pressure cavity rapid injection mold and method

Abstract

This invention discloses a rapid injection mold and method using a high-pressure jet combined with a negative pressure cavity, comprising a nozzle, an upper mold, and a lower mold. The nozzle includes a carbon steel outer cavity wall and a ventilated steel inner cavity wall arranged sequentially from the outside to the inside, forming a high-pressure cavity between the carbon steel outer cavity wall and the ventilated steel inner cavity wall. A gas injection port is provided on the carbon steel outer cavity wall, through which high-pressure gas is injected and transmitted through micropores in the ventilated steel inner cavity wall to the slurry cavity formed by the ventilated steel inner cavity wall. A nozzle is also coaxially arranged on the ventilated steel inner cavity wall and the carbon steel outer cavity wall, communicating with the slurry cavity and being sealed to the upper mold, forming a mold cavity between the upper mold and the lower mold. A negative pressure cavity is provided on the working surface of the lower mold, and the negative pressure of the negative pressure cavity can be transmitted to the mold cavity. The high-pressure and negative pressure difference between the upper and lower molds enables rapid injection molding of high-viscosity slurry.

Description

Technical Field

[0001] This invention belongs to the field of mold making, specifically relating to a rapid injection mold and method using high-pressure jet combined with negative pressure cavity. Background Technology

[0002] To address the environmental problems caused by plastic products, researchers have developed various biodegradable green materials. Starch is an extremely abundant biomass raw material in nature, inexpensive, readily available, and renewable. Developing starch-based biomass green materials has significant market value and social benefits. However, the processing and molding of natural polymer materials is difficult and inefficient, severely limiting their industrial production and application. Starch molecules have a large mass, long chains, and numerous hydrogen bonds, resulting in high viscosity under low water or anhydrous conditions. This high viscosity makes it difficult for the slurry to flow smoothly under mechanical extrusion, hindering starch injection molding. Therefore, achieving rapid delivery of hot-melt starch-based biomass materials is a crucial problem that urgently needs to be solved in their injection molding process. Summary of the Invention

[0003] Because starch has a relatively low pyrolysis temperature, it is difficult to reduce the viscosity of hot-melt starch slurry by increasing the temperature, thus giving it a high-viscosity characteristic. To address the problem of slurry transport difficulties during injection molding of hot-melt starch-based biodegradable materials, which makes them unsuitable for the process requirements of existing injection molding machines and hinders rapid injection molding, this invention patent specifically discloses a high-pressure jet combined with a negative pressure cavity rapid injection nozzle. This nozzle is suitable for the high-viscosity characteristics of low-water starch-based biomass slurries, significantly improving the production efficiency of hot-melt starch-based biomass material products, and has good practical utility and engineering application value.

[0004] To achieve the above objectives and solve the above-mentioned main technical problems, the present invention is implemented through the following specific technical solutions:

[0005] This invention discloses a rapid injection mold with a high-pressure jet combined with a negative pressure cavity, comprising a nozzle, an upper mold, and a lower mold. The nozzle includes a carbon steel outer cavity wall and a ventilated steel inner cavity wall arranged sequentially from the outside to the inside, forming a high-pressure cavity between the carbon steel outer cavity wall and the ventilated steel inner cavity wall. A gas injection port is provided on the carbon steel outer cavity wall, through which high-pressure gas is injected and transmitted through micropores in the ventilated steel inner cavity wall to the slurry cavity formed by the ventilated steel inner cavity wall. A nozzle is also provided coaxially on the ventilated steel inner cavity wall and the carbon steel outer cavity wall, which communicates with the slurry cavity and is sealed to the upper mold, forming a mold cavity between the upper mold and the lower mold. A negative pressure cavity is provided on the working surface of the lower mold, through which negative pressure can be transmitted to the mold cavity.

[0006] The nozzle of this invention is encased in carbon steel. Gas is injected into the cavity via an external pressure pump and pressure valve, forming a high-pressure cavity. A permeable steel material separates the high-pressure cavity from the slurry cavity, transmitting high pressure through micropores within the permeable steel. This allows for uniform high-pressure transmission while the slurry flows freely within the extrusion cavity, preventing overflow and keeping the high-pressure cavity clean. A sealing ring maintains a high-pressure sealed structure between the injection nozzle and the mold. The negative pressure cavity of the lower mold is connected to an external vacuum pump, creating a negative pressure state in the interconnected cavity through evacuation. After the upper and lower molds are closed, the negative pressure is transmitted to the mold cavity through the microporous structure of the permeable steel, forming a negative pressure cavity. The significant pressure difference between the high-pressure injection nozzle and the negative pressure cavity propels the high-viscosity starch slurry into the mold cavity rapidly. The material is then rapidly cooled and molded using a cooling system, and high-pressure gas is blown in through a permeable steel insert to achieve rapid demolding. Ultimately, this process enables the rapid molding of hot-melt starch-based biomass materials, producing hot-melt starch biomass injection-molded products.

[0007] As a further technical solution, a screw is provided inside the slurry cavity, and the rotational speed of the screw is controllable.

[0008] As a further technical solution, a cooling system is also provided on the upper and lower molds.

[0009] As a further technical solution, a flow channel is provided on the upper mold, and the flow channel is connected to the nozzle.

[0010] As a further technical solution, a groove is provided on the working surface of the lower mold. The groove and the inlaid ventilated steel together form a cavity. The cavity is used to connect an external vacuum pump, and the cavity is made into a negative pressure cavity by evacuating the vacuum.

[0011] As a further technical solution, a conical sealing ring is used between the nozzle and the mold to maintain a high-pressure state in the biomass material molding cavity.

[0012] As a further technical solution, the gas injection port is connected to a pressure pump and a pressure valve.

[0013] Secondly, the present invention also includes a method for rapidly molding hot-melt starch-based biomass materials using a high-pressure jet combined with a negative pressure cavity, as follows:

[0014] An external pressure pump injects gas into the cavity through a pressure valve, forming a high-pressure cavity. The high pressure is transmitted through the micropores in the inner wall of the breathable steel cavity to the slurry cavity. The slurry can flow freely in the slurry cavity without overflowing into the high-pressure cavity, keeping the high-pressure cavity clean.

[0015] The lower mold negative pressure cavity is connected to an external vacuum pump, which creates a negative pressure state in the cavity by drawing a vacuum; after the upper and lower molds are closed, the negative pressure is transmitted to the mold cavity, forming a negative pressure state;

[0016] The huge pressure difference between the high-pressure injection nozzle and the negative pressure cavity propels the high-viscosity starch slurry into the mold cavity rapidly. After that, it is quickly cooled and shaped by the cooling system. High-pressure gas is blown into the mold cavity again to achieve rapid demolding. Finally, the rapid molding of hot melt starch-based biomass material is achieved, and hot melt starch biomass injection molded products are produced.

[0017] As a further technical solution, different slurry rheological properties can be satisfied by controlling the temperature of the high-viscosity starch slurry, the pressure difference between the high-pressure cavity and the negative-pressure cavity, and the shear rate of the hot-melt starch.

[0018] The beneficial effects of this invention are as follows:

[0019] After studying the traditional injection molding process, this invention overcomes the limitations of existing injection molding processes and nozzles in meeting the requirements of hot-melt starch-based biomass material injection molding. It innovatively designs a rapid injection mold combining high-pressure jet and a negative pressure cavity. This rapid injection mold effectively solves the problem of difficult slurry delivery caused by the high viscosity characteristics during the injection molding of hot-melt starch-based biodegradable materials. It increases the injection molding efficiency of starch-based biomass materials by more than 20 times, reducing the injection time per product from 2 minutes to 5 seconds. Furthermore, the nozzle of this invention can flexibly adjust the pressure difference between high and negative pressure according to different temperatures and shear rates to meet the rheological characteristics of hot-melt starch slurries with varying viscosities.

[0020] Furthermore, the injection nozzle features a clever design with carbon steel encasing a breathable steel core and a high-pressure cavity. This design allows for uniform high-pressure transmission while the slurry flows freely within the extrusion cavity, preventing overflow and keeping the high-pressure cavity clean, thus extending the nozzle's lifespan. The lower mold employs a continuous cavity. During the injection molding stage, this cavity is under negative pressure, facilitating a significant pressure difference with the upper mold to propel the slurry into shape. After mold opening, the continuous cavity in the lower mold returns to high pressure, enabling rapid demolding of the high-viscosity starch-based biomass material. Attached Figure Description

[0021] Figure 1 It is a cross-sectional design drawing of a high-pressure jet combined with a negative pressure cavity for rapid injection molding nozzles and molds;

[0022] Figure 2 This is a schematic diagram of breathable steel;

[0023] Figure 3 This is a schematic diagram of the upper and lower molds;

[0024] In the diagram: 1. Pressure valve; 2. Carbon steel outer cavity wall; 3. Ventilated steel inner cavity wall; 4. Screw; 5. Ventilated steel boss; 6. Continuous negative pressure cavity; 7. Lower mold; 8. Injection cavity; 9. Upper mold; 10. Conical sealing ring; 11. High-pressure cavity; 12. Slurry cavity; 13. Cooling system; 14. Continuous demolding cavity; 15. Hot melt starch biomass injection molded product. Detailed Implementation

[0025] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] Based on the rheological properties of hot-melt starch-based biomass materials and their temperature-pressure synergistic transport mechanism, this invention innovatively proposes a novel injection nozzle that combines high-pressure jet and negative pressure cavity, suitable for the rheological characteristics of hot-melt starch-based biomass materials. By utilizing the pressure difference at a specific temperature, high-viscosity slurry is rapidly injected into the molding die, solving the problem of rapid transport of high-viscosity hot-melt starch slurry during injection molding. This greatly improves the production efficiency of starch-based biomass materials and reduces their production energy consumption.

[0028] The present invention will now be described in detail with reference to the accompanying drawings:

[0029] The high-pressure jet combined with negative pressure cavity rapid injection mold proposed in this embodiment is as follows: Figure 1 , Figure 3As shown, the injection mold includes a nozzle, an upper mold, and a lower mold. The nozzle comprises a carbon steel outer cavity wall and a permeable steel inner cavity wall arranged sequentially from the outside to the inside. A high-pressure cavity is formed between the carbon steel outer cavity wall and the permeable steel inner cavity wall. A gas injection port is provided on the carbon steel outer cavity wall, through which high-pressure gas is injected and transmitted through micropores in the permeable steel inner cavity wall to the slurry cavity formed by the permeable steel inner cavity wall. A coaxial nozzle is also provided on the permeable steel inner cavity wall and the carbon steel outer cavity wall. This nozzle communicates with the slurry cavity and is sealed to the upper mold, forming a mold cavity between the upper and lower molds. A negative pressure cavity is provided on the working surface of the lower mold, and the negative pressure of the negative pressure cavity can be transmitted to the mold cavity. The nozzle of this injection mold uses carbon steel to encase permeable steel, forming a high-pressure cavity in the middle. The permeability of the permeable steel is utilized to transmit high pressure to the slurry cavity, thereby creating a high-pressure environment in the upper mold portion of the injection nozzle.

[0030] Specifically, the aforementioned nozzle includes a pressure valve 1, a carbon steel outer cavity wall 2, a breathable steel inner cavity wall 3, a screw 4, and a high-pressure cavity 11 formed between the carbon steel outer cavity wall and the breathable steel inner cavity wall. The pressure valve 1 is installed on the carbon steel outer cavity wall 2 and is connected to a pressure pump. The outermost part of the injection nozzle is wrapped with the carbon steel outer cavity wall 2. Gas is injected into the cavity through the pressure valve 1 via the external pressure pump to form the high-pressure cavity 11. The high-pressure cavity 11 is separated from the slurry cavity by the breathable steel inner cavity wall 3. High pressure is transmitted through the micropores in the breathable steel to the slurry cavity. While uniformly transmitting high pressure, the slurry can also flow freely in the extrusion cavity without overflowing into the high-pressure cavity.

[0031] Furthermore, the nozzle head is conical, and a conical mounting hole is provided in the upper mold. The nozzle head is installed in the mounting hole, and a conical sealing ring 10 is used between the injection nozzle and the mold to keep the biomass material molding cavity under high pressure.

[0032] Furthermore, the high-pressure jet combined with negative pressure cavity rapid injection mold is divided into an upper injection mold 9 and a lower injection mold 7. During the injection molding process, the upper injection mold is in a high-pressure state and the lower injection mold is in a negative pressure state. After the upper and lower molds are closed, the high-viscosity hot melt starch slurry is pushed by the huge pressure difference to achieve rapid injection molding.

[0033] Furthermore, a cooling system 13 is provided on the upper injection mold 9 and the lower injection mold 7, wherein the cooling system 13 adopts water circulation cooling.

[0034] Furthermore, a conical sealing ring 10 maintains a high-pressure sealing structure between the injection nozzle and the upper injection mold. The working surface of the lower injection mold 7 is recessed to form a groove, which, together with the embedded ventilated steel boss 5, forms a connected negative pressure cavity 6. The connected negative pressure cavity is connected to an external vacuum pump, and by drawing a vacuum, the connected cavity is made into a negative pressure state. The negative pressure is transmitted to the mold cavity through the microporous structure in the ventilated steel boss 5, forming a negative pressure cavity. The huge pressure difference formed between the high-pressure injection nozzle and the negative pressure cavity drives the high-viscosity starch slurry to be injected rapidly into the mold cavity.

[0035] Among them, the carbon steel outer cavity wall 2 is made of high-quality carbon steel, such as No. 45 carbon steel, No. 60 carbon steel, 60Mn carbon steel, etc., but not limited to the above three types of carbon steel.

[0036] Furthermore, the wall thickness of the carbon steel outer cavity wall 2 is 3-6mm.

[0037] Furthermore, the ventilated steel inner wall 3 and the ventilated steel boss 5 are made of ventilated steel of models such as PM-35-7 and PM-35-25d, but are not limited to the above two ventilated steel models.

[0038] Furthermore, the wall thickness of the ventilated steel inner cavity wall 3 is 2-5mm, and the thickness of the ventilated steel boss 5 is 4-6mm.

[0039] Furthermore, the cavity thickness of the connected negative pressure cavity 6 is 3-6 mm.

[0040] Furthermore, temperature changes are dynamically and precisely controlled through temperature sensors and control programs, pressure changes are dynamically and precisely controlled through pressure sensors and control programs, and the shear rate of hot melt starch is controlled by controlling the screw speed.

[0041] Furthermore, hot-melt starch exhibits different rheological properties under different temperature, pressure, and shear rate conditions. Based on different temperatures and shear rates, the nozzle of this invention can adjust the pressure difference between high and negative pressure to meet different slurry rheological properties.

[0042] Furthermore, the method for rapid injection molding of hot-melt starch-based biomass materials based on the high-pressure jet combined with negative pressure cavity in this embodiment is as follows:

[0043] An external pressure pump injects gas into the cavity through a pressure valve, forming a high-pressure cavity. The high pressure is transmitted through the micropores in the inner wall of the breathable steel cavity to the slurry cavity. The slurry can flow freely in the slurry cavity without overflowing into the high-pressure cavity, keeping the high-pressure cavity clean.

[0044] The lower mold negative pressure cavity is connected to an external vacuum pump, which creates a negative pressure state in the cavity by drawing a vacuum; after the upper and lower molds are closed, the negative pressure is transmitted to the mold cavity, forming a negative pressure state;

[0045] The huge pressure difference between the high-pressure injection nozzle and the negative pressure cavity propels the high-viscosity starch slurry into the mold cavity rapidly. After that, it is quickly cooled and shaped by the cooling system. High-pressure gas is blown into the mold cavity again to achieve rapid demolding. Finally, the rapid molding of hot melt starch-based biomass material is achieved, and hot melt starch biomass injection molded products are produced.

[0046] As a further technical solution, different slurry rheological properties can be satisfied by controlling the temperature of the high-viscosity starch slurry, the pressure difference between the high-pressure cavity and the negative-pressure cavity, and the shear rate of the hot-melt starch.

[0047] This embodiment innovatively designs a rapid injection molding nozzle combining high-pressure jet and a negative pressure cavity. This rapid injection molding nozzle effectively solves the problem of difficult slurry delivery caused by the high viscosity characteristics during the injection molding of hot-melt starch-based biodegradable materials. It increases the injection molding efficiency of starch-based biomass materials by more than 20 times, reducing the injection time per item from 2 minutes to 5 seconds. Simultaneously, the nozzle can flexibly adjust the pressure difference between high and negative pressure to meet the rheological characteristics of hot-melt starch slurries of various viscosities, depending on different temperatures and shear rates. Furthermore, the injection molding nozzle's ingenious design, using carbon steel encased in breathable steel with a central high-pressure cavity, allows for uniform high-pressure transmission while the slurry flows freely within the extrusion cavity, preventing overflow and keeping the high-pressure cavity clean, thus extending the service life of the injection molding nozzle. The lower mold adopts a connected cavity. During the injection molding stage, the connected cavity is in a negative pressure state, which is conducive to forming a large pressure difference with the upper mold and pushing the slurry to be injected and molded. After the mold is opened, the connected cavity of the lower mold can be changed to high pressure, which is conducive to the rapid demolding of high-viscosity starch-based biomass materials after molding.

[0048] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

[0049] Finally, it should be noted that relational terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A rapid injection mold combining high-pressure jet and negative pressure cavity, characterized in that, The device includes a nozzle, an upper mold, and a lower mold. The nozzle comprises a carbon steel outer cavity wall and a permeable steel inner cavity wall arranged sequentially from the outside to the inside. A high-pressure cavity is formed between the carbon steel outer cavity wall and the permeable steel inner cavity wall. A gas injection port is provided on the carbon steel outer cavity wall, through which high-pressure gas is injected and transmitted through micropores in the permeable steel inner cavity wall to the slurry cavity formed by the permeable steel inner cavity wall. A nozzle is also provided on the permeable steel inner cavity wall and the carbon steel outer cavity wall, which is connected to the slurry cavity and sealed to the upper mold, forming a mold cavity between the upper mold and the lower mold. A groove is provided on the working surface of the lower mold, which, together with the embedded permeable steel, forms a negative pressure cavity. The negative pressure of the negative pressure cavity can be transmitted to the mold cavity. The high-pressure and negative pressure difference between the upper and lower molds enables rapid injection molding of high-viscosity slurry.

2. The rapid injection mold with high-pressure jet combined with negative pressure cavity as described in claim 1, characterized in that, A screw is provided inside the slurry cavity.

3. The rapid injection mold with high-pressure jet combined with negative pressure cavity as described in claim 1, characterized in that, Cooling systems are also provided on the upper and lower molds.

4. The rapid injection mold with high-pressure jet combined with negative pressure cavity as described in claim 1, characterized in that, The upper mold is provided with a flow channel, which is connected to the nozzle and the mold cavity.

5. The rapid injection mold with high-pressure jet combined with negative pressure cavity as described in claim 1, characterized in that, The negative pressure cavity is connected to a vacuum pump.

6. The rapid injection mold with high-pressure jet combined with negative pressure cavity as described in claim 1, characterized in that, There is a conical sealing ring between the nozzle and the mold.

7. The rapid injection mold with high-pressure jet combined with negative pressure cavity as described in claim 1, characterized in that, The gas injection port is connected to a pressure pump and a pressure valve.

8. A method for rapidly injection molding hot-melt starch-based biomass materials using a high-pressure jet combined with a negative pressure cavity as described in any one of claims 1-7, characterized in that, as follows: An external pressure pump injects gas into the cavity through a pressure valve, forming a high-pressure cavity; the high pressure is transmitted to the slurry cavity through the micropores in the inner wall of the breathable steel cavity. The slurry can flow freely within the slurry cavity without overflowing into the high-pressure cavity, thus keeping the high-pressure cavity clean. The lower mold negative pressure cavity is connected to an external vacuum pump, which creates a negative pressure state in the cavity by drawing a vacuum; after the upper and lower molds are closed, the negative pressure is transmitted to the mold cavity, forming a negative pressure state; The huge pressure difference between the high-pressure injection nozzle and the negative pressure cavity propels the high-viscosity starch slurry into the mold cavity rapidly. After that, it is quickly cooled and shaped by the cooling system. High-pressure gas is blown into the mold cavity again to achieve rapid demolding. Finally, the rapid molding of hot melt starch-based biomass material is achieved, and hot melt starch-based biomass injection molded products are produced.

9. The method for molding hot-melt starch-based biomass materials as described in claim 8, characterized in that, By controlling the temperature of the high-viscosity starch slurry, the pressure difference between the high-pressure cavity and the negative-pressure cavity, and the shear rate of the hot-melt starch, different slurry rheological properties can be satisfied.

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