A twin-screw extruder pressure stabilizing device

Abstract

A twin-screw extruder pressure stabilization device, the pressure stabilization system includes a pressure sensor, a shaft section pressure regulator, an air hole pressure regulator, and a gas pressure accumulator. The present invention uses two pressure stabilization methods: an air hole pressure regulator and an shaft section pressure regulator. The air hole pressure regulator plus the gas reservoir are used to stabilize the internal pressure of the screw extruder. The shaft section pressure regulator is used to change the pressure environment inside the screw extruder, greatly changing the internal and external pressure difference to adapt to different materials. The two pressure stabilizers cooperate with each other to achieve the purpose of stabilizing the pressure system of the twin-screw extruder. The two pressure stabilization methods are controlled by a single-chip microcomputer, which can realize the control of the pressure values ​​at different stages in the barrel respectively, thereby achieving the purpose of stabilizing the dynamic pressure.

Description

Technical Field

[0001] The invention belongs to the field of twin-screw extrusion equipment, and in particular relates to a twin-screw extruder pressure stabilizing device, which can realize dynamic pressure control during the twin-screw extrusion process. Background Art

[0002] During the extrusion process in a twin-screw extruder, the material undergoes multiple stages, including material conveying, melting, solution conveying, mixing, and extrusion. Each stage has its own performance requirements. Under natural conditions, the pressure within the barrel gradually increases from the inlet due to screw rotation and forward material movement. However, the pressure required for each extrusion stage varies, and a simple linear pressure increase is insufficient. Consequently, various mechanical pressure-building mechanisms have emerged.

[0003] Among existing mechanical pressure-building structures, the most typical is reverse screw pressure-building. This pressure-building method not only increases the pressure at the front end of the reverse screw, but also increases the residence time of the material in the extruder, improving the performance of the extruded material. It is a commonly used pressure-building method in twin-screw extruders. However, current pressure-building methods are mechanical and uncontrollable, leading to many problems.

[0004] The basis of reverse thread pressure building is to hinder the material's forward route, forcing the material to flow back, thereby increasing the pressure value in the front section of the reverse thread. This passive pressure building method will undoubtedly lead to overall fluctuations in the pressure in the barrel. Local bubbles or insufficient feed in the barrel will also lead to a decrease in pressure building capacity when passing through the reverse thread. In addition, temperature fluctuations in the barrel will cause the viscosity of the material to decrease, thereby reducing the pressure building capacity of the reverse thread, and many other pressure fluctuation factors.

[0005] This irregular pressure fluctuation has three main effects on the twin-screw extruder: First, the fluctuating pressure value cannot fully meet the pressure requirements of the melting section, for example. Too high or too low pressure will cause the physical properties of the extruded material to fail to meet the requirements. Second, the constantly changing pressure will reduce the fatigue strength of the bearings. Third, it will cause tooth grinding between the two screws. Some twin-screw extruders use a bearing assembly method with a flexible bearing on one side and a large end bearing on the other side. Changing pressure will cause changing deformation. When one side of the flexible bearing is subjected to excessive pressure, the excessive deformation will cause tooth grinding.

[0006] The current pressure regulation method is the pressure regulating valve, which comes in three types: axial, radial, and rotary. Axial pressure regulating valves use a movable slider to adjust the gap between the twin screws and the barrel to control pressure. Radial pressure regulating valves use radial movement of the shaft to change the internal volume to control pressure. Rotary pressure regulating valves have a rotatable slider at the intersection of the two screws and the upper barrel wall. The slider is controlled by a handle on top to adjust the material flow rate and achieve pressure control.

[0007] Another method is indirect pressure regulation, which focuses on feed and temperature control, reducing external system fluctuations and indirectly improving pressure stability within the barrel. However, this control method, unlike direct control, has drawbacks such as low effectiveness and slow response.

[0008] Therefore, designing a device that can maintain a steady state of pressure in the barrel by real-time detection of the pressure values ​​at different stages of the twin-screw extruder will be expected to effectively solve the current problems in pressure control in the plastic production industry, optimize the physical properties of the extruded materials, and extend the service life of the twin-screw extruder. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a twin-screw extruder pressure stabilizing device with two pressure regulating modes, which can detect pressure changes in each stage and adjust the pressure.

[0010] According to the twin-screw extruder pressure stabilizing device provided by the present invention, the technical solution adopted is as follows:

[0011] The equipment consists of a controller, a control display screen, a screw, a barrel, and also includes a pressure sensor, a shaft section pressure regulator, an air hole pressure regulator, and a gas pressure accumulator; the pressure sensor is embedded in the barrel; the shaft section pressure regulator is installed in the smooth section of the screw with an interference fit; the air hole pressure regulator has an opening on the barrel; the gas pressure accumulator is welded to the upper end of the barrel and is connected to the air hole pressure regulator.

[0012] The pressure regulating device includes two pressure regulating modes: a pore pressure regulator for stabilizing the internal pressure of the screw extruder, and a shaft pressure regulator for changing the pressure environment inside the screw extruder, significantly changing the internal and external pressure difference to adapt to different materials. The controller is electrically connected to the controllable display device.

[0013] The screw extruder pressure stabilizing device provided by the present invention also adopts the following auxiliary technical solutions:

[0014] The shaft section pressure regulator includes a reverse shaft section, an electromagnet, a stop keyway, and a movable key; the reverse shaft section is installed on the smooth section of the screw; the electromagnet is welded on the barrel opposite to the stop keyway; the stop keyway is composed of two parts, namely the keyways opened by the reverse shaft section and the smooth section of the screw, and the movable key is placed in the stop keyway.

[0015] The air hole pressure regulator includes a gas retention area and an adjustable pressure valve; the gas retention area is a cavity in the barrel and is placed below the flow air hole; the adjustable pressure valve is tightly connected above the flow air hole and is electrically connected to the controller, and the controller sets the passing pressure of the adjustable pressure valve.

[0016] The gas pressure accumulator comprises an airway, a pressure tank and a gas baffle; the airway connects the pressure tank and the air pore pressure regulator; the gas baffle is placed at the connection between each pressure tank and the airway.

[0017] The pressure sensor is a contact pressure sensor, which is embedded in the inner side of the barrel, and the outer surface of the pressure sensor is aligned with the surface of the barrel.

[0018] A keyway is provided on the inner side of the reverse shaft section for the movable key to be inserted into; the movable key is controlled by an electromagnet.

[0019] The flow holes are opened at the upper section of the barrel at each processing stage, the upper section partially extends out of the barrel, and the diameter of the lower section opening is larger than that of the upper section opening.

[0020] The adjustable pressure valve is placed at the upper end of the flow hole and needs to be sealed.

[0021] The air channel is connected to the outside of the air flow hole in a sealed manner, and both sides have channels for exhausting air to the outside.

[0022] The twin-screw extruder pressure stabilizing device provided by the present invention has the following advantages compared with the prior art:

[0023] 1. The twin-screw extruder pressure stabilizing device of the present invention can actively and directly regulate the pressure, and has a faster response and a larger pressure adjustable range than the traditional pressure regulation. The present invention fundamentally changes the internal pressure regulation method, making the working pressure of the twin-screw extruder more stable. Compared with the traditional pressure regulation method of the pressure regulating valve, the function of the pressure regulating valve is only to slightly change the working parameters of the twin-screw extruder and adjust the change value of its internal pressure to adapt to the extrusion of different materials. The present invention can be run in parallel with the pressure regulating valve, or run alone, and can realize pressure regulation directly in the process of work. The main work done is not to change the working parameters of the twin-screw extruder, but to perform pressure regulation and stabilize pressure fluctuations in the process of work, so as to improve the working performance of the twin-screw extruder and optimize the physical properties of the extruded material.

[0024] 2. The twin-screw extruder pressure stabilizing device of the present invention is combined with dual control methods, and has a large pressure regulation range and more precise regulation control. The appropriate regulation method can be selected according to different working conditions. The present invention adopts two pressure regulation methods, and the two pressure regulation methods are responsible for different tasks. The shaft section pressure regulation is mainly used for the pressure changes required for changes in the working environment. When different mixtures are added, the required working pressure and working temperature are different. The working pressure of the melt mixing section is adjusted by enabling and suppressing the reverse shaft end. The pore pressure regulating device is mainly used for regulating pressure fluctuations. Under the same working conditions, due to the influence of internal reactions and various external factors, the pressure is always fluctuating. The pressure regulating valve is set by the controller to control the steady state of pressure in the barrel.

[0025] 3. The twin-screw extruder pressure stabilizing device of the present invention has a sealed barrel, which ensures that the internal environment of the barrel is sealed and improves its stability. Traditional pressure regulating methods all require a window to be opened on the barrel to connect the corresponding control elements, and the clamping plates, spheres, etc. used for control have a certain amount of clearance fit with the barrel, making it difficult for the internal environment of the barrel to be sealed and greatly affected by external factors. Both pressure regulating methods used in the present invention will not affect the sealing of the barrel. The control mode of the shaft section pressure regulating device is electromagnetic force control, which is directly controlled by the electromagnet outside the barrel, and the pore pressure regulating device is arranged on the upper end of the barrel and has a smaller opening. There is a certain amount of gap between it and the material, which can form high-pressure air to separate the outside of the barrel and the material, and can also prevent the material from overflowing.

[0026] 4. The gas pressure storage system of the twin-screw extruder pressure stabilization device of the present invention fully utilizes the exhaust gas generated by the system and uses self-exhausted gas for pressure regulation. Generally, a twin-screw extruder produces more gas in the melting stage, and there may be insufficient pressure or gas shortage in the other two processing stages. This system will store the gas in the melting stage and can adjust the pressure in the gas storage tank to supply it to the conveying stage and expansion stage when needed, so as to ensure that the overall gas pressure remains stable during the three-stage process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of the twin-screw extruder equipment in the present invention.

[0028] Figure 2 It is a schematic diagram of the air hole pressure regulator in the present invention.

[0029] Figure 3 It is a schematic diagram of the shaft section voltage regulator of the present invention.

[0030] Figure 4 It is a schematic diagram of the gas pressure accumulator in the present invention. DETAILED DESCRIPTION

[0031] According to the present invention, a twin-screw extruder pressure stabilization device comprises a controller, a control display, a screw, and a barrel. The pressure stabilization system includes a pressure sensor, a shaft pressure regulator, a vent pressure regulator, and a gas pressure accumulator. The controller is electrically connected to the controller display, the detector, and the pressure regulator. The vent pressure regulator and the shaft pressure regulator are two types of pressure regulators. The vent pressure regulator and the shaft pressure regulator are used to stabilize the internal pressure of the screw extruder. The shaft pressure regulator is used to change the pressure environment inside the screw extruder, significantly changing the internal and external pressure difference to accommodate different materials.

[0032] Furthermore, the shaft section voltage regulator includes a reverse shaft section, an electromagnet, a stop keyway, and a movable key. The electromagnet is electrically connected to a controller, which controls whether the electromagnet is energized. A keyway is defined within the reverse shaft section, allowing the movable key to engage when the electromagnet is energized. The movable key is controlled by the electromagnet to control whether the reverse shaft section is in operation. Multiple reverse shaft sections can be installed for each stage, each controlled by an electromagnet at a different angle.

[0033] Furthermore, the adjustable pressure valve is electrically connected to a controller, which sets the pressure through which the valve passes. The air flow holes are opened at each processing stage of the barrel. The upper section extends beyond the barrel, while the lower section has a larger diameter. The large-diameter cavity at the lower end is used to store high-pressure gas. The adjustable pressure valve is positioned above the air flow hole and can regulate the flow pressure. The pressure sensor is a contact-type pressure sensor embedded in the barrel, with its outer surface aligned with the barrel surface.

[0034] Furthermore, the gas pressure accumulator includes an airway, a pressure tank, and a gas baffle. The airway is connected to the outside of the flow vent and must be sealed to store the gas discharged by the vent pressure regulator. Both sides of the pressure tank have channels for venting gas to the outside, which can be used to discharge gas when the pressure in the pressure tank is too high.

[0035] See also Figures 1 to 4According to an embodiment of the twin-screw extruder pressure control device provided by the present invention, the device includes a pressure sensor 1, a controller display 2, a controller 3, a shaft section pressure regulator 4, a pore pressure regulator 5, a barrel 6, a screw 7, and a gas pressure accumulator 8. The pressure sensor 1 is installed inside the barrel 6, and the pressure sensor 1 is installed in each working stage of the twin-screw extruder. The external circuit is connected to the controller 3. The controller display 2 is placed on the controller 3 and installed as a whole on the barrel 6 of the twin-screw extruder. The shaft section pressure regulator 4 is installed on the screw 7. As part of the screw thread, the hole axis is an interference fit. The shaft section pressure regulator 4 is installed in each working stage of the twin-screw extruder. The pore pressure regulator 5 is an opening on the barrel 6 and is installed with related parts. The pore pressure regulator 5 is installed in each working stage of the twin-screw extruder. The screw 7 is installed inside the barrel 6. The gas pressure accumulator 8 is installed outside the barrel 6.

[0036] See also Figure 1 According to the above-mentioned embodiment of the present invention, the controller display screen 2 is used to realize human-computer interaction. The controller 3 can be controlled and set related parameters through the controller display screen 2. The controller 3 is the main control center of the present invention, which is used to control whether the shaft section pressure regulator 4, the air hole pressure regulator 5 and the gas pressure accumulator 8 are working. The pressure sensor 1 is used as detection information. When it detects that the pressure inside the barrel 6 reaches the set value, the relevant pressure regulator will be put into operation.

[0037] See also Figure 2 , according to the above-mentioned embodiment of the present invention. The shaft section pressure regulator 4 includes a reverse shaft section 41, an electromagnet 42, a stop keyway 43, a movable key 44 and a screw center shaft 45. A keyway is opened inside the reverse shaft section 41, and it is matched with the screw center shaft 45 as an interference hole shaft. When it is not working, it is driven to rotate by the pressure provided by the material and cannot change the pressure in the barrel. The screw center shaft 45 is a smooth section without threads of the screw 7. The electromagnet 42 is placed outside the barrel 6 and is connected to the barrel 6 by threads. The stop keyway 43 is a keyway opened on the screw center shaft 45. The movable key 44 is placed in the stop keyway 43 and continuously stays at the proximal end of the stop keyway 43 when it is not working.

[0038] See also Figure 2According to the above embodiment of the present invention. The electromagnet 42 controls the current through the controller 3 to control the magnetic force. The connection between the two is electrical. When the electromagnet 42 obtains the magnetic force, the movable key 44 is converted from the non-working state to the working state due to the attraction of the magnetic force, leaving the bottom of the proximal end of the stop key groove 43, sliding to the top of the distal end of the stop key groove 43 and embedding into the key of the reverse shaft segment 41. The reverse shaft segment 41 and the screw center shaft 45 are changed from interference fit to tight fit through the movable key 44, so that the reverse shaft segment 41 obtains the rotational power. Since it is a reverse thread, it can resist the forward movement of the material to complete the pressure building during active rotation, thereby achieving the purpose of increasing the pressure of the relevant shaft segments inside the barrel.

[0039] See also Figure 3 According to the above embodiment of the present invention, the air hole pressure regulator 5 includes a gas retention area 51, an adjustable pressure valve 52 and a circulation air hole 53. The material in the barrel 7 will continuously generate gas during the extrusion and melting process, and the gas will gather at the upper part of the barrel 7 to form the gas retention area 51. Since the gas is compressible and has a lower density than the material in liquid form, the high-pressure gas will continue to rise and gather in the cavity at the lower end of the circulation air hole 53 to form a high-pressure air mass. During the exhaust and pressure regulation process, the material will not leak out. The adjustable pressure valve 52 is electrically connected to the controller 3 to control the passing pressure of the pressure valve. When the pressure value of the high-pressure air mass in the cavity at the lower end of the circulation air hole 53 is greater than the set passing pressure, the accumulated gas will overflow. After a certain amount of gas is discharged, the pressure of the high-pressure air mass drops below the set pressure and the exhaust stops, so as to achieve the purpose of regulating the pressure value in the barrel.

[0040] See also Figure 4 , according to the above-mentioned embodiment of the present invention. The gas pressure accumulator includes an air channel 81, a pressure tank 82 and a gas baffle 83. The air channel 81 is seamlessly connected to the pore pressure regulator 5. The pressure tank 82 contains a pressure plate, which can control the gas storage pressure and is also connected to the air channel 81. The gas baffle is placed at the connection between the air channel and the outside and the pressure tank 82, and the flow of gas can be controlled by the controller 3. The pressure tank 82 is used to store the gas discharged from the barrel. The melting section generally produces high-pressure gas, which is stored in the pressure tank 82 through the air channel 81. The other two gas baffles 83 connected to the pressure tank 82 can be closed to prevent the gas from being discharged into the barrel uncontrollably. The pressure inside the barrel 7 can be stabilized by accumulating pressure. There is a channel leading to the outside at each of the left and right ends of the air channel 81, which is also controlled by the gas baffle 83 to prevent excessive gas in the pressure storage tank 82.

[0041] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A twin-screw extruder pressure stabilizing device, consisting of a controller, a control display, a screw, and a barrel, characterized in that: The pressure stabilizing device further includes a pressure sensor, a shaft section pressure regulator, an air hole pressure regulator, and a gas pressure accumulator; the pressure sensor is embedded in the barrel; the shaft section pressure regulator is installed on the smooth section of the screw with an interference fit; the air hole pressure regulator opens on the barrel; the gas pressure accumulator is welded to the upper end of the barrel and connected to the air hole pressure regulator; The shaft section pressure regulator includes a reverse shaft section, an electromagnet, a stop keyway, and a movable key; the reverse shaft section is installed on the smooth section of the screw; the electromagnet is welded on the barrel opposite to the stop keyway; the stop keyway is composed of two parts, namely the keyways opened by the reverse shaft section and the smooth section of the screw, and the movable key is placed in the stop keyway.

2. The twin-screw extruder pressure stabilizing device according to claim 1, characterized in that: The air hole pressure regulator includes a gas retention area and an adjustable pressure valve; the gas retention area is a cavity in the barrel and is placed below the circulation air hole; the adjustable pressure valve is tightly connected above the circulation air hole and is electrically connected to the controller, and the controller sets the passing pressure of the adjustable pressure valve.

3. The twin-screw extruder pressure stabilizing device according to claim 1, characterized in that: The gas pressure accumulator comprises an airway, a pressure tank and a gas baffle; the airway connects the pressure tank and the air pore pressure regulator; the gas baffle is placed at the connection between each pressure tank and the airway.

4. The twin-screw extruder pressure stabilizing device according to claim 1, characterized in that: The pressure sensor is a contact pressure sensor, which is embedded in the inner side of the barrel, and the outer surface of the pressure sensor is aligned with the surface of the barrel.

5. The twin-screw extruder pressure stabilizing device according to claim 1, characterized in that: A keyway is provided on the inner side of the reverse shaft section for the movable key to be inserted into; the movable key is controlled by an electromagnet.

6. The twin-screw extruder pressure stabilizing device according to claim 2, characterized in that: The flow holes are opened in the upper section of the barrel at each processing stage. The upper section extends out of the barrel, and the diameter of the lower section opening is larger than that of the upper section opening.

7. The twin-screw extruder pressure stabilizing device according to claim 2, characterized in that: The adjustable pressure valve is placed at the upper end of the flow hole and needs to be sealed.

8. The twin-screw extruder pressure stabilizing device according to claim 3, characterized in that: The air channel is connected to the outside of the circulation air hole in a sealed manner, and both sides have channels for exhausting air to the outside.

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