An electromagnetic heating device and a twin-screw extruder

Abstract

This utility model discloses an electromagnetic heating device and a twin-screw extruder, belonging to the technical field of twin-screw extruders. It includes: a heating body comprising a rectangular frame and heating units; the rectangular frame includes a U-shaped shell and a sealing shell, with the sealing shell detachably connected to the open end of the U-shaped shell; heating units are respectively disposed in the U-shaped shell and the sealing shell for electromagnetic heating; each heating unit includes first electromagnetic heating elements respectively disposed on both sides and in the middle of the U-shaped shell, and a second electromagnetic heating element disposed in the sealing shell; multiple first electromagnetic heating elements are connected in series via wires and electrically in parallel with the second electromagnetic heating elements. This utility model can perform targeted heating, achieving uniform heating.

Description

Technical Field

[0001] This utility model relates to the field of twin-screw extruder technology, and in particular to an electromagnetic heating device and a twin-screw extruder. Background Technology

[0002] Twin-screw extruders were developed based on single-screw extruders. Due to their excellent feeding performance, mixing and plasticizing performance, venting performance, and extrusion stability, they are now widely used in the molding and processing of extruded products.

[0003] Traditional twin-screw extruders typically use resistance heating for the barrel. This method has several significant technical drawbacks: First, resistance heating has low thermal efficiency, resulting in substantial heat loss during heat conduction and energy waste. Second, due to the complex structure of the barrel, especially I-shaped barrels, traditional heating methods struggle to achieve uniform heating, leading to uneven material heating and impacting product quality. Third, resistance heating suffers from poor temperature control precision, making it difficult to meet the requirements of precision extrusion processes. Utility Model Content

[0004] In view of this, it is necessary to provide an electromagnetic heating device and a twin-screw extruder to solve the problems of low heating efficiency and uneven heating in existing twin-screw extruders.

[0005] In a first aspect, this utility model provides an electromagnetic heating device, comprising: The heating body includes a rectangular frame and heating units. The rectangular frame includes a U-shaped shell and a sealing shell, with the sealing shell detachably connected to the open end of the U-shaped shell. The heating units are respectively disposed in the U-shaped shell and the sealing shell for electromagnetic heating. Each heating unit includes a first electromagnetic heating element disposed on both sides and the middle of the U-shaped shell, and a second electromagnetic heating element disposed in the sealing shell. Multiple first electromagnetic heating elements are connected in series via wires and electrically connected in parallel with the second electromagnetic heating element. The control component includes a controller for regulating the heating units and a heat sink. The controller is connected to the side of the rectangular frame, and the heat sink is embedded in the controller. The controller is connected to the first and second electromagnetic heating elements and can issue control signals to drive them to start and stop independently.

[0006] Preferably, there are multiple heating bodies and multiple control components; the control components are disposed one-to-one on the heating body or multiple control components are integrated in a control cabinet.

[0007] Preferably, one end of the U-shaped housing is provided with a detachable end cap, which can enclose the U-shaped housing to shield multiple first electromagnetic heating elements; the sealing housing and the U-shaped housing are connected by a snap fastener to control the opening and closing of the space located in the middle of the rectangular frame.

[0008] Preferably, the U-shaped shell is made of mica material, and the wall thickness of the U-shaped shell on the side closer to the center of the rectangular frame is less than the wall thickness of the side of the U-shaped shell on the side farther away from the center of the rectangular frame; the inner wall of the U-shaped shell is provided with a radiation shielding layer, which is positioned relative to the heating unit.

[0009] Preferably, both the U-shaped shell and the sealing shell are provided with heat insulation cotton, the first electromagnetic heating element is disposed in the heat insulation cotton of the U-shaped shell, and the second electromagnetic heating element is disposed in the heat insulation cotton of the sealing shell.

[0010] Preferably, the controller includes a housing for encapsulating electronic components and a connecting bracket. The housing is connected to the U-shaped housing via the connecting bracket. The housing has multiple heat dissipation holes arranged in an array. The connecting bracket has open sides to form a perforated structure that facilitates heat dissipation.

[0011] Preferably, the radiator is an air-cooled radiator or a water-cooled radiator.

[0012] Preferably, the radiator is an air-cooled radiator, and the outer shell between the connecting brackets is recessed inward to form an installation space for the air-cooled radiator. Multiple heat sinks are spaced apart in the installation space around the air-cooled radiator.

[0013] Preferably, the heating body further includes a temperature sensing unit, which includes a temperature sensor and a temperature sensing hole. The temperature sensing hole is opened on the sealing shell and the U-shaped shell, and the temperature sensor passes through the temperature sensing hole and is positioned relative to the heating unit.

[0014] Secondly, this utility model provides a twin-screw extruder, comprising: an electromagnetic heating device and a barrel for extruding raw materials, wherein a rectangular frame is fitted onto the barrel, the barrel has an I-shaped cross-section, and the bottom of the barrel is positioned relative to the second electromagnetic heating element.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows: (1) The electromagnetic heating device and twin-screw extruder of this utility model are provided with a rectangular frame, which is composed of a U-shaped shell and a sealing shell that are detachably connected. The sealing shell and the open end of the U-shaped shell are detachably connected, which can seal the open end of the U-shaped shell to form a completely closed heating space. The detachable connection between the U-shaped shell and the sealing shell allows the heating area to be freely adjusted to meet the heating requirements of different materials.

[0016] (2) The present invention provides an electromagnetic heating device and a twin-screw extruder, which are equipped with heating units. The heating units are respectively disposed in a U-shaped shell and a sealing shell, thereby heating the heating space through electromagnetic action. The heating unit includes a first electromagnetic heating element and a second electromagnetic heating element. Multiple first electromagnetic heating elements are respectively disposed on both sides and the middle of the U-shaped shell, and the second electromagnetic heating element is disposed in the sealing shell. Multiple first electromagnetic heating elements are connected in series with wires and electrically connected in parallel with the second electromagnetic heating element. The first electromagnetic heating elements are distributed on both sides and the middle of the U-shaped shell to form multiple independent heating areas, and a stable current is maintained by series connection. The second electromagnetic heating elements are centrally disposed in the sealing shell and are connected in parallel to the main circuit to achieve independent power adjustment. The second electromagnetic heating element can independently enhance the heating of the bottom of the heating space and maintain the reference heating amount of the first electromagnetic heating element, thereby achieving adaptive heating to the shape of the barrel. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 is a schematic diagram of the overall structure of this utility model; Figure 2 This is a disassembled structural diagram of the rectangular frame of this utility model; Figure 3 This is a schematic diagram of the connection structure between the U-shaped shell and the first electromagnetic heating element in this utility model; Figure 4 This is a schematic diagram of the connection structure between the sealing shell and the second electromagnetic heating element in this utility model; Figure 5 This is a schematic diagram of the control component in this utility model; Figure 6 This is a schematic diagram of the structure of the heating body and the barrel in this utility model.

[0018] In the figure, 100 is the heating body; 110 is the rectangular frame; 111 is the U-shaped shell; 111a is the end cap; 112 is the sealing shell; 113 is the snap fastener; 120 is the heating unit; 121 is the first electromagnetic heating element; 122 is the second electromagnetic heating element; 130 is the temperature sensing unit; and 131 is the temperature sensing hole. 200. Control component; 210. Controller; 211. Exterior casing; 212. Connecting bracket; 220. Heat sink; 300. Machine barrel. Detailed Implementation

[0019] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0020] This embodiment describes an electromagnetic heating device and a twin-screw extruder, relating to the field of twin-screw extruder technology. It utilizes electromagnetic induction to heat the twin-screw extruder, achieving high heating efficiency. Furthermore, by systematically arranging the positions and power of the electromagnetic heating elements, targeted heating of the I-beam barrel 300 can be achieved, resulting in uniform heating.

[0021] Please see Figures 1 to 6 This embodiment of an electromagnetic heating device includes a rectangular frame 110 and a heating unit 120. The rectangular frame 110 is composed of a U-shaped shell 111 and a sealing shell 112 detachably connected. The sealing shell 112 is detachably connected to the open end of the U-shaped shell 111, allowing the open end of the U-shaped shell 111 to be sealed, forming a completely closed heating space. The detachable connection between the U-shaped shell 111 and the sealing shell 112 allows for free adjustment of the heating area to meet the heating requirements of different materials.

[0022] Heating units 120 are respectively disposed in the U-shaped shell 111 and the sealing shell 112, thereby heating the heating space through electromagnetic action. Each heating unit 120 includes a first electromagnetic heating element 121 and a second electromagnetic heating element 122. Multiple first electromagnetic heating elements 121 are respectively disposed on both sides and in the middle of the U-shaped shell 111, while the second electromagnetic heating elements 122 are disposed in the sealing shell 112. The multiple first electromagnetic heating elements 121 are connected in series with wires and electrically in parallel with the second electromagnetic heating elements 122. The first electromagnetic heating elements 121 are distributed on both sides and in the middle of the U-shaped shell 111, forming multiple independent heating areas, and a stable current is maintained through the series connection. The second electromagnetic heating elements 122 are centrally disposed in the sealing shell 112. In a preferred embodiment, their total power is equal to the sum of all the first electromagnetic heating elements 121, and independent power regulation is achieved by connecting them in parallel to the main circuit. The second electromagnetic heating element 122 can independently enhance the heating of the bottom of the heating space while maintaining the reference heating amount of the first electromagnetic heating element 121, thereby achieving adaptive heating for the shape of the barrel 300.

[0023] The control component 200 includes a controller 210 and a heat sink 220. The controller 210 is connected to the side of the rectangular frame 110, and the heat sink 220 is embedded within it. The controller 210 can adjust the heating unit 120 as needed to control the heating intensity. The heat sink 220 is tightly attached to the housing of the controller 210 via thermally conductive silicone grease, using the housing's own thermal conduction path to dissipate heat to the external environment. The controller 210 is connected to the first electromagnetic heating element 121 and the second electromagnetic heating element 122, and can send control signals to drive their independent start and stop.

[0024] It should be noted that electromagnetic heating elements refer to heating components composed of electromagnetic coils and magnetic cores. Specifically, high-frequency copper tubes can be wound into flat coil structures and embedded in the housing to form a surface heat source.

[0025] The first electromagnetic heating element 121, connected in series, forms an independent circuit, and the second electromagnetic heating element 122 forms an independent circuit. Each circuit has an independent switching system, allowing both circuits to operate independently or in parallel, sharing a single power supply. The first electromagnetic heating element 121 can heat the sides and top of the base cylinder 300, while the second electromagnetic heating element 122 can heat the bottom of the base cylinder 300.

[0026] By making the first electromagnetic heating element 121 and the second electromagnetic heating element 121 into independent circuits and configuring an independent switching system for each circuit, the system can achieve independent control of the heating elements. The two sets of electromagnetic heating elements can operate at different times and different power levels, enhancing the flexibility of the heating process.

[0027] For example, when only the top and sides of the base cylinder need to be heated, the first electromagnetic heating element 121 can be activated alone; if only the bottom of the base cylinder 300 needs to be heated, only the second electromagnetic heating element 122 can be activated, thereby achieving precise control and energy saving.

[0028] The two circuits are connected in parallel and share a single power source, which minimizes power consumption. At the same time, through precise circuit design, it ensures that the two heating elements can work in coordination, avoiding unnecessary power loss.

[0029] When both sets of heating elements work simultaneously, large-area heating can be achieved, which is suitable for occasions requiring high heating. When only partial heating is needed, the corresponding heating element can be started independently by controlling the switch to reduce power consumption.

[0030] The first electromagnetic heating element 121 mainly heats the sides and top of the base cylinder 300, while the second electromagnetic heating element 122 mainly heats the bottom of the base cylinder 300. Because the heating areas are different, each electromagnetic heating element can precisely heat a specific area, avoiding overheating or heat waste that may occur with traditional heating methods.

[0031] The control component 200 refers to the circuit system integrating a temperature feedback module. Specifically, it can be a combination of a PID controller 210 and an IGBT drive module, which can regulate the high-frequency copper tube. The eddy currents generated by the electromagnetic induction of the high-frequency copper tube directly act on the metal layer of the barrel 300, improving the heat conversion efficiency by about 40%. The separate combination of the U-shaped shell 111 and the sealing shell 112 allows the heating unit 120 to be maintained and replaced without disassembling the entire machine, reducing downtime by more than 70%.

[0032] In some embodiments, please refer to Figure 2 and Figure 3 One end of the U-shaped housing 111 is provided with a detachable end cap 111a. The end cap 111a is an independent component that covers the open end of the U-shaped housing 111. Specifically, it can be detachably connected by using a metal plate and fastening bolts. The shielding function of the end cap 111a is achieved by completely covering the installation area of ​​the first electromagnetic heating element 121 when closed, preventing the intrusion of external foreign objects or accidental contact of live parts by operators.

[0033] Specifically, when the end cap 111a is connected to the U-shaped housing 111 via a snap-fit ​​or bolt, it forms a closed space to enclose the first electromagnetic heating element 121. When it is necessary to repair or replace the heating unit 120, only the end cap 111a needs to be removed to directly access the internal components without dismantling the entire housing structure. An elastic sealing strip can be provided on the edge of the end cap 111a to ensure that the interior of the housing is isolated from the external environment when closed.

[0034] Compared to existing technologies, traditional electromagnetic heating devices typically employ welded or one-piece molded housings, requiring the entire heating module to be disassembled for maintenance, leading to complex operations and compromising equipment sealing. The detachable design of the end cap 111a maintains the overall protective performance of the housing while enabling quick opening and closing of specific areas, significantly reducing the impact of maintenance operations on the stability of the heating system.

[0035] Please see Figures 2 to 4 The sealing shell 112 and the U-shaped shell 111 are connected by a latch 113. This latch connection refers to a mechanical locking structure that allows for detachable and fixed connection between the two components. Specifically, it can be achieved using a spring latch, a slotted engagement structure, or a rotating latch 113. The latch 113 structure allows for quick assembly and disassembly while ensuring the structural stability of the connection. The heating space in the middle of the rectangular frame 110 refers to the area enclosed by the U-shaped shell 111 and the sealing shell 112. This heating space is used to accommodate the workpiece to be heated, such as the barrel 300 of a twin-screw extruder. By controlling the opening and closing of this space, the contact relationship between the heating unit 120 and the workpiece can be adjusted, thereby optimizing heating efficiency.

[0036] Specifically, when maintenance of the heating unit 120 or adjustment of the workpiece position is required, the operator can manually unlock the latches to separate the sealing housing 112 from the U-shaped housing 111, completely opening the space in the middle of the rectangular frame 110. At this time, the heating unit 120 is exposed within the operable range, facilitating maintenance or replacement. After the operation is completed, the sealing housing 112 is re-secured by the latches, restoring the closed protection to the heating unit 120.

[0037] Compared to existing technologies, traditional electromagnetic heating devices mostly use bolt fixing or welding connections, which require specialized tools and are time-consuming to disassemble and assemble, making rapid maintenance impossible. In contrast, the locking connection allows for disassembly and assembly without auxiliary tools, and does not cause wear on the connecting parts during repeated opening and closing, thus solving the problem of low equipment maintenance efficiency.

[0038] In some embodiments, the U-shaped shell 111 is a shell made of mica mineral, specifically achieved by a lamination pressing process, and has the characteristics of high temperature resistance and excellent insulation performance.

[0039] The wall thickness of the U-shaped shell 111 on the side closer to the center of the rectangular frame 110 is less than the wall thickness of the side of the U-shaped shell 111 on the side farther from the center of the rectangular frame 110. Simply put, the shell thickness is smaller on the side closer to the heating area and larger on the side farther from the heating area. This can be achieved through molding or machining, adjusting the heat transfer efficiency by varying the thickness of different areas.

[0040] The base material, due to its high-temperature resistance, can withstand the high-temperature environment generated by electromagnetic heating, while its insulation properties can prevent the risk of current leakage. The shell wall thickness is reduced near the central space of the rectangular frame 110, which helps to reduce the thermal conduction resistance in this area and allows heat to be transferred to the heated parts more quickly; the shell wall thickness is increased further away from this area, which can enhance the structural strength and reduce external heat loss.

[0041] A radiation shielding layer is provided on the inner wall of the U-shaped housing 111, and the radiation shielding layer is positioned relative to the heating unit 120. The radiation shielding layer refers to a material layer with electromagnetic wave reflection or absorption function, which can be implemented by an aluminum foil composite layer or a metal coating layer. It is fixed to the inner wall surface of the U-shaped housing 111 by adhesive bonding or spraying to reduce the outward diffusion of electromagnetic radiation generated by the heating unit 120.

[0042] The setting of the radiation shielding layer relative to the heating unit 120 means that the position of the material layer corresponds to the area where the heating unit 120 is located. Specifically, this can be achieved by matching the coverage area of ​​the radiation shielding layer with the electromagnetic field distribution area of ​​the heating unit 120, so that the radiant heat is confined to a specific working area.

[0043] Specifically, inside the U-shaped shell 111 made of mica material, a radiation shielding layer extends longitudinally along the shell and covers the installation area corresponding to the first electromagnetic heating element 121. When the heating unit 120 is working, when the electromagnetic field acts on the radiation shielding layer, the material of this layer converts the radiant energy into heat energy and returns it to the heating area through reflection or absorption. By directionally arranging the radiation shielding layer, the integrity of the shell structure is maintained, and the electromagnetic energy is effectively utilized.

[0044] It should be noted that the structure of the sealing shell 112 is the same as that of the U-shaped shell 111. The same structure means that both the sealing shell 112 and the U-shaped shell 111 are made of mica material and the inner wall is thinner than the outer wall. At the same time, a radiation shielding layer is provided on the inner wall.

[0045] In some embodiments, both the U-shaped shell 111 and the sealing shell 112 are provided with heat insulation cotton, the first electromagnetic heating element 121 is disposed in the heat insulation cotton of the U-shaped shell 111, and the second electromagnetic heating element 122 is disposed in the heat insulation cotton of the sealing shell 112.

[0046] The insulation cotton is a fibrous material with heat-insulating properties, specifically made of glass fiber or ceramic fiber, used to wrap the electromagnetic heating element to reduce heat loss. The open end of the U-shaped shell 111 is connected to the sealing shell 112 via a latch to form a rectangular frame 110. The sealing shell 112 is a closed component that cooperates with the U-shaped shell 111, with the same structure and internal insulation cotton. The first electromagnetic heating element 121 refers to the coil assembly distributed on both sides and in the middle of the U-shaped shell 111, which forms a heating circuit through series connection of wires. The second electromagnetic heating element 122 refers to an independent coil assembly installed inside the sealing shell 112, whose heating power is the sum of the multiple first electromagnetic heating elements 121, and is connected to the circuit in parallel.

[0047] Specifically, the insulation cotton filling the U-shaped shell 111 and the sealed shell 112 completely encloses the electromagnetic heating element, confining the heat generated within the insulation cotton. Due to the low thermal conductivity of the insulation cotton, the heat is mainly transferred directionally to the central space of the rectangular frame 110, preventing loss to the external environment. The first electromagnetic heating element 121 forms a stable current loop after being connected in series, while the second electromagnetic heating element 122 operates independently in parallel. The two work together to achieve differentiated heating in different areas.

[0048] In some embodiments, please refer to Figure 5 and Figure 6 The controller 210 includes a housing 211 and a connecting bracket 212. The housing 211 encapsulates the electronic components within the controller 210, protecting them from external interference and influence. The housing 211 is connected to the U-shaped housing 111 via the connecting bracket 212, with both ends of the connecting bracket 212 connected to the housing 211 and the U-shaped housing 111 respectively via bolts. The connecting bracket 212 separates the housing 211 and the U-shaped housing 111, preventing heat conduction between them and hindering heat dissipation.

[0049] The outer casing 211 is provided with multiple heat dissipation holes arranged in a relative array. This arrangement of multiple heat dissipation holes in a relative array can effectively expand the heat dissipation area, form an air convection channel, and significantly enhance the natural heat dissipation capacity.

[0050] The open design on both sides of the connecting bracket forms a hollow structure, which further enhances the air circulation path, allowing the heat inside the controller to be quickly dissipated, thus preventing the electronic components from degrading or being damaged due to high temperatures.

[0051] By optimizing the structure (heat dissipation holes + hollow bracket), the internal temperature of the controller can be kept within a reasonable range, thereby reducing the thermal aging rate of components and improving the stability and service life of the entire control system.

[0052] The radiator 220 is an air-cooled radiator. The outer shell 211 between the connecting brackets 212 is recessed inward to form the installation space of the air-cooled radiator. Multiple heat sinks are arranged at intervals in the installation space around the air-cooled radiator.

[0053] It should be noted that both the U-shaped housing 111 and the outer shell 211 are equipped with aviation connectors. Aviation connectors are electrical connectors specifically designed for use in aerospace, military, industrial automation, rail transportation, and marine applications where high reliability, high safety, and complex, harsh environments are required. Aviation connectors are robust, provide reliable contact, and can withstand vibration, shock, temperature changes, and other harsh conditions, ensuring that the connection will not be accidentally broken or experience poor contact.

[0054] Aviation plugs typically have keyways, locating pins, or different models and specifications to prevent incorrect insertion. The first electromagnetic heating element 121, the second electromagnetic heating element 122, the power supply, and the controller 210 are connected by a cable, with aviation plugs connected to both ends of the cable to ensure the stability of the electrical connection.

[0055] In practical applications, there are multiple heating bodies 100 and multiple control components 200. Each control component 200 is either mounted on a heating body 100 or multiple control components are integrated into a control cabinet. In other words, multiple controllers 210 can be integrated together to uniformly control multiple barrels 300, thereby improving the integration level of the control system.

[0056] In some embodiments, the heating body 100 further includes a temperature sensing unit 130, which includes a temperature sensor and a temperature sensing hole 131. The temperature sensing hole 131 is formed on the sealing shell 112 and the U-shaped shell 111, and the temperature sensor passes through the temperature sensing hole 131 and is positioned relative to the heating unit 120. The temperature sensor can be implemented using a thermocouple or an infrared temperature measurement module, and its function is to provide a temperature feedback signal to the control component 200 to adjust the heating power. The temperature sensing hole 131 is a through hole formed on the surface of the shell for fixing the temperature sensor. The through hole can be formed by machining or molding, and its function is to directly position the temperature sensor near the heating unit 120 to improve temperature measurement accuracy.

[0057] Temperature sensors are installed in temperature sensing holes 131 on the surfaces of the sealing shell 112 and the U-shaped shell 111, directly facing the heating unit 120. During electromagnetic heating, the temperature sensors detect real-time temperature data of the heating area through the temperature sensing holes 131, either directly or non-contactly, and transmit the signal to the controller 210. The controller 210 dynamically adjusts the power output of the first electromagnetic heating element 121 and the second electromagnetic heating element 122 based on the received temperature data, thereby maintaining a uniform heating state for the material inside the barrel 300 and preventing explosions due to excessive temperature, thus avoiding safety hazards.

[0058] In some embodiments, please refer to Figure 5 The heat sink 220 can be an air-cooled heat sink or a water-cooled heat sink. The air-cooled heat sink and the water-cooled heat sink can dissipate heat from the high-power controller 210, so that the controller 210 can work normally.

[0059] In the specific implementation process, the air-cooled radiator 220 can be implemented using an axial fan or a centrifugal fan, while the water-cooled radiator 220 can be implemented using a copper tube circulating water circuit or a plate heat exchanger structure.

[0060] A twin-screw extruder in this embodiment includes: an electromagnetic heating device and a barrel 300 for extruding raw materials. A rectangular frame 110 is fitted onto the barrel 300. Two twin screws are provided at the bottom of the barrel 300. The position of the second electromagnetic heating element 122 corresponds to the bottom area of ​​the barrel 300, ensuring that the magnetic field generated by the second electromagnetic heating element 122 directly acts on the bottom of the barrel 300, thereby improving the local heating effect.

[0061] Specifically, the rectangular frame 110 of the electromagnetic heating device is fixed to the outer surface of the barrel 300 by a sleeve. Due to its complex structure, the bottom area of ​​the I-shaped barrel 300 is prone to uneven heat distribution. The second electromagnetic heating element 122 is concentrated in this area, directly heating the bottom of the barrel 300 through electromagnetic induction. A temperature sensor can be embedded in the recessed area at the bottom of the I-shaped barrel 300 to monitor the heating status in real time and feed it back to the controller 210.

[0062] Compared with existing technologies, when existing twin-screw extruders use resistance heating, heat needs to be transferred from the outside to the barrel 300 through thermal conduction. The bottom of the I-shaped barrel 300 has increased thermal resistance due to its complex structure. Electromagnetic heating acts directly on the surface of the barrel 300, and combined with the second electromagnetic heating element 122 for directional heating of the bottom, it effectively reduces heat loss.

[0063] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the present utility model.

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