An extrusion coating molding device for a double-layer insulated electric wire

Abstract

The application relates to the technical field of electric wire and cable manufacturing, and discloses an extrusion coating forming device for double-layer insulated electric wires, which comprises two extruders, the two extruders are respectively used for injecting inner layer coating material and outer layer coating material, the top of each of the two extruders is communicated with a feeding hopper, and the discharging end of each of the two extruders is communicated with a discharging pipe; a machine head shell is provided with two feeding holes which are respectively communicated with the two discharging pipes, and a hollow sleeve is axially slidably inserted into the machine head shell. By arranging a tension sensing assembly and a linear cylinder outside the machine head, the hollow sleeve inside is driven to axially translate by an external yoke, the flow hole and the feeding hole are instantaneously dislocated to close the flow channel, and the defects that the built-in gear and spring of the built-in mechanical linkage valve of the machine head in the prior art are prone to thermal recession, are carbonized and are stuck and dead under the extremely harsh melt working conditions of high temperature and high pressure and the high maintenance cost are solved.

Description

Technical Field

[0001] This invention relates to the field of wire and cable manufacturing technology, specifically to an extrusion coating molding device for double-insulated wires. Background Technology

[0002] In the production of double-insulated wires, two plastics with different properties are typically extruded onto the conductor surface using an extrusion coating molding device. Due to the differences in the physical properties of the inner and outer insulation materials, existing equipment still has many technical shortcomings in terms of temperature control, flow channel interception, and material supply in actual production operations.

[0003] Dual-layer co-extrusion die heads need to process two materials with significantly different melting points simultaneously. To achieve segmented temperature control, traditional equipment often employs a dual-heating-chamber metal sleeve structure. However, due to the excellent thermal conductivity of the metal body, heat conduction inevitably occurs between the high-temperature and low-temperature zones connected by solid metal components. This physical phenomenon can easily lead to carbonization of the material in the low-temperature zone due to excessive heat absorption, or hardening of the material in the high-temperature zone due to heat loss, making it difficult to maintain a stable dual-layer extrusion environment.

[0004] During production, if the power cord breaks unexpectedly or the machine is temporarily stopped, the material needs to be quickly cut off to prevent filament pulling and tailing at the discharge port. To address this, some existing technologies incorporate a mechanical linkage valve inside the extruder head, using a cable to open internal guide wheels and transmission components to control the flow channel opening and closing. However, the extruder head operates under harsh conditions of high temperature and pressure for extended periods. Placing transmission components such as gears, racks, and springs directly near the melt chamber can easily lead to thermal degradation of these mechanical structures. Furthermore, rubber material that lingers in gaps and dead zones is prone to carbonization, causing internal mechanical structures to jam or even seize, increasing equipment maintenance costs and reducing operational reliability.

[0005] Furthermore, during continuous operation, plastic granules in the feed hopper of extrusion equipment are prone to bridging and clogging, and engineering plastics often require drying and dehumidification before extrusion. Conventional methods for preventing hopper clogging typically involve adding an independent motor for mechanical stirring, or suspending an adjusting rod inside the hopper and using the rotation of the main screw to agitate it. Using an independent motor inevitably increases the equipment's energy consumption and manufacturing costs; while using the main screw for direct friction agitation results in continuous rigid metal friction, which can easily damage the main screw over long-term operation, and the generated metal debris, if mixed into the flow channel, can damage the insulation performance of electrical wires. Simultaneously, existing production lines typically require an additional independent hot air dryer for dehumidification and drying of the material, failing to achieve comprehensive utilization of the equipment's internal energy. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an extrusion coating molding apparatus for double-layer insulated wires, which solves the problems mentioned in the background section.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: an extrusion coating molding device for double-layer insulated wires, comprising: two extruders, the two extruders being used to inject inner coating material and outer coating material respectively, the top of the two extruders being connected to a feed hopper, and the discharge end of the two extruders being connected to a discharge pipe;

[0008] The machine head housing has two feed holes that are respectively connected to the two discharge pipes. A hollow sleeve is slidably inserted into the machine head housing along the axial direction. The side wall of the hollow sleeve has two flow holes that are respectively engaged with the two feed holes.

[0009] The tension sensing component is located outside the inlet end of the machine head housing and includes a floor frame, a movable pulley, a swing arm, and an absolute angle encoder. The absolute angle encoder is mounted on the floor frame via a support, and the central axis of the absolute angle encoder is connected to the left end of the swing arm. The movable pulley is used for the power supply line to pass through and bear the tension of the wire. The absolute angle encoder is used to detect the rotation angle of the swing arm.

[0010] The misaligned flow interception assembly includes a linear cylinder and a shift fork disposed outside the machine head housing. The output end of the linear cylinder is connected to one end of the hollow sleeve through the shift fork. The linear cylinder is controlled by the signal fed back by the absolute angle encoder and is used to drive the hollow sleeve to slide axially, so that the two flow holes are misaligned with the two feed holes to close the flow channel.

[0011] The thermal isolation and waste heat recovery assembly includes a thermal isolation flange and a collection hood disposed in the middle section of the head housing. The thermal isolation flange is provided with an inward air inlet, and the collection hood is disposed outside the thermal isolation flange. Pneumatic vibrators are fixed to the outside of both feed hoppers, and micro fluidized beds are provided on the bottom inner walls of both feed hoppers. The exhaust end of the collection hood is connected to the air inlet end of a diversion valve. The two air outlets of the diversion valve are respectively connected to a first air guide pipe and a second air guide pipe. The first air guide pipe is connected to the pneumatic vibrator, and the second air guide pipe is connected to the micro fluidized bed.

[0012] Preferably, the tension sensing component further includes a fixed pulley and a bracket. Two parallel fixed pulleys are rotatably mounted on the floor frame, and a vertically arranged guide groove is provided on the bracket. A strip-shaped window is provided in the middle of the swing arm. The movable pulley is positioned below the two fixed pulleys. The end of the central shaft of the movable pulley passes through the strip-shaped window and has an end slider at its end. The end slider is slidably fitted into the guide groove.

[0013] Preferably, a counterweight is suspended at the end of the swing arm away from the absolute angle encoder; the two fixed pulleys and the movable pulley are arranged in a U-shape so that the power supply line passes around them in sequence.

[0014] Preferably, the die head housing is divided into two independent extrusion areas along the axial direction by the heat-insulating flange. The interior of the hollow sleeve is interconnected, and two conical cavities are sequentially processed along the direction of wire travel. The two conical cavities are connected by a passage hole. The two flow holes are respectively connected to the large-diameter ends of the two conical cavities. The diameter of the outlet end of the conical cavity near the wire exit end is larger than the diameter of the outlet end of the conical cavity near the wire inlet end. The outlet end of the conical cavity near the wire exit end is connected to a forming channel.

[0015] Preferably, a core tube is fixedly inserted into the hollow sleeve on one side of the inlet end. The core tube has a micro-hole through which the power supply wire passes, and the micro-hole is configured to form a gap seal with the wire. The tip of the outlet end of the core tube extends to the center of the conical cavity near the inlet end.

[0016] Preferably, the end of the hollow sleeve away from the discharge pipe extends out to the outside of the machine head housing, and a groove is formed around the surface of the extended end. The upper end of the shift fork is directly inserted into the groove. The linear cylinder is horizontally fixedly installed below the machine head housing, and the lower end of the shift fork is rigidly fixed to the output shaft of the linear cylinder.

[0017] Preferably, three air inlets are provided, and the three air inlets are evenly distributed on the bottom outer wall of the thermal insulation flange; the thermal insulation flange has an inner air passage and an outer air passage inside, the central air inlet is connected to the inner air passage, and the air outlet of the inner air passage extends toward the outer wall of the hollow sleeve; the air inlets on both sides are connected to the outer air passage, and the outer air passage has a groove-shaped structure and is distributed on the two side end faces of the thermal insulation flange.

[0018] Preferably, the collecting hood is a semi-annular hollow shell, which is fastened and wrapped around the upper outer ring of the thermal isolation flange to collect the airflow discharged from the inner air duct and the outer air duct.

[0019] Preferably, the exhaust end of the top of the collection hood is connected to the inlet end of the diversion valve, the diversion valve is an asymmetric proportional regulating valve, the main outlet end of the diversion valve is connected to the first air guide pipe, and the bypass throttling outlet end of the diversion valve is connected to the second air guide pipe.

[0020] Preferably, the first air guide pipe is connected to the air inlet of the pneumatic vibrator, and is used to drive the pneumatic vibrator to apply mechanical vibration to the outer wall of the feed hopper using airflow; the micro fluidized bed is a permeable plate with micropores on its surface, and is laid in the lower half of the inner wall of the feed hopper; the second air guide pipe passes through the wall of the feed hopper and is connected to the micro fluidized bed, and is used to blow airflow from bottom to top into the interior of the feed hopper.

[0021] This invention provides an extrusion coating molding apparatus for double-insulated wires. It has the following beneficial effects:

[0022] 1. This invention solves the problems of the built-in mechanical linkage valve in the die head under the extremely harsh conditions of high temperature and high pressure melt, where the built-in gears and springs are prone to thermal decay, jamming and seizing by carbonized rubber, and extremely high maintenance costs. It moves all mechanical sensing and execution components out of the high-temperature danger zone and uses a simple thick-walled metal sleeve for pure physical interception. This not only achieves millisecond-level response speed and avoids wire breakage and dragging, but also extends the overall service life of the equipment and achieves extremely high system reliability.

[0023] 2. This invention creates a dynamic air curtain bridging structure by adding a thermal isolation flange between the two extrusion zones and introducing ambient temperature gas in two separate streams to flush the outer wall of the hollow sleeve and the side end face of the flange. This solves the problem of thermal bridging caused by the connection of solid metal parts in the dual heating chambers, which easily leads to overheating in the low-temperature zone causing the material to scorch or cooling in the high-temperature zone causing the material to harden. The flowing air curtain not only significantly reduces the solid heat transfer cross-sectional area of ​​the metal, but also actively carries away the overflow heat that is trying to be transferred from the high-temperature zone to the low-temperature zone, ensuring that two engineering plastics with a large temperature difference can achieve absolutely independent and precise temperature control co-extrusion within one die head.

[0024] 3. This invention distributes the waste heat gas collected at the machine head through an asymmetric diversion valve. High-pressure airflow drives a pneumatic vibrator to strike the outer wall of the hopper, while low-pressure hot airflow is introduced into the bottom micro fluidized bed to blow the material upwards. This solves the problems of mechanical anti-clogging structures, which either require an external motor to increase energy consumption or rely on friction from the main screw to easily generate metal debris that contaminates the wire insulation and requires the purchase of an independent dryer. The gas-solid linkage structure achieves safe anti-clogging with no rigid friction and converts the exhaust gas pressure from the machine head into bridge breaking power and waste heat into a dehumidification heat source. Without adding any additional external kinetic or thermal energy equipment, it achieves efficient closed-loop energy recovery within the equipment. Attached Figure Description

[0025] Figure 1 This is a right-side perspective view of the present invention;

[0026] Figure 2 This is a front view of the present invention;

[0027] Figure 3 A schematic diagram illustrating the structure of the tension sensing component of the present invention is provided.

[0028] Figure 4 This is a left perspective view of the present invention;

[0029] Figure 5 This is a schematic diagram illustrating the structure of the head housing of the present invention;

[0030] Figure 6 This is a schematic diagram illustrating the installation structure of the thermal isolation flange of the present invention;

[0031] Figure 7 A schematic diagram illustrating the internal structure of the hollow sleeve of this invention;

[0032] Figure 8 A schematic diagram illustrating the gas passage structure on the thermal isolation flange of this invention;

[0033] Figure 9 A schematic diagram of the micro fluidized bed structure of the present invention is shown.

[0034] The components include: 1. Extruder; 2. Floor frame; 3. Fixed pulley; 4. Support; 5. Movable pulley; 6. Absolute angle encoder; 7. Swing arm; 8. Strip window; 9. Counterweight; 10. Guide groove; 11. End slider; 12. Discharge pipe; 13. Die head housing; 14. Feed hole; 15. Hollow sleeve; 16. Slot; 17. Flow hole; 18. Conical cavity; 19. Passage hole; 20. Forming channel; 21. Die core tube; 22. Thermal insulation flange; 23. Air inlet; 24. Inner air passage; 25. Outer air passage; 26. Collection hood; 27. Diverter valve; 28. First air guide pipe; 29. ​​Pneumatic vibrator; 30. Second air guide pipe; 31. Feed hopper; 32. Miniature fluidized bed; 33. Linear cylinder; 34. Shift fork. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Please see the appendix Figure 1 - Appendix Figure 2 This invention provides an extrusion coating molding device for double-layer insulated wires. The main structure includes two extruders 1 and a die head housing 13 disposed on one side of the two extruders 1. The two extruders 1 are respectively configured to inject inner coating material and outer coating material into the die head housing 13. The top of the two extruders 1 is connected to a feed hopper 31, and the discharge end of the two extruders 1 is connected to a discharge pipe 12. The die head housing 13 is made of high-temperature resistant alloy steel to withstand the high pressure environment inside during extrusion operation.

[0037] Please see the appendix Figure 3 - Appendix Figure 4A tension sensing component is installed on the outside of the inlet end of the machine head housing 13. This component includes a floor frame 2, a movable pulley 5, a swing arm 7, and an absolute angle encoder 6. Two parallel fixed pulleys 3 are rotatably mounted on the floor frame 2. A bracket 4 is fixed to the side of the floor frame 2, and a vertically arranged guide groove 10 is opened on the bracket 4. A strip window 8 is opened in the middle of the swing arm 7, and the left end of the swing arm 7 is rigidly connected to the central shaft of the absolute angle encoder 6. The absolute angle encoder 6 is mounted on the floor frame 2 through a support, and the swing arm 7 is away from the absolute angle encoder. One end of the 6 is suspended by a counterweight 9. The movable pulley 5 is positioned below the two fixed pulleys 3. It is used to allow the power supply line to pass through in a U-shape and bear the upward tension of the wire. The end of the central shaft of the movable pulley 5 passes through the strip window 8 and is equipped with an end slider 11. The end slider 11 is slidably fitted into the guide groove 10. During the wire traction process, the cooperation between the end slider 11 and the guide groove 10 restricts the movable pulley 5 to only make vertical lifting and lowering movements. The central shaft of the movable pulley 5 slides horizontally along the strip window 8, thereby eliminating the motion interference between linear lifting and lowering and the arc rotation of the swing arm 7.

[0038] Please see the appendix Figure 4 and attached Figure 6 A misaligned flow-cutting assembly, including a linear cylinder 33 and a shift fork 34, is fixedly mounted on the frame below the machine head housing 13. The hollow sleeve 15 extends out of the discharge pipe 12 to the outside of the machine head housing 13, and a groove 16 is machined around the surface of the extended end. The lower end of the shift fork 34 is fixed to the output shaft of the linear cylinder 33, and the upper end of the shift fork 34 is directly inserted into the groove 16. The linear cylinder 33 establishes an electrical signal connection with the absolute angle encoder 6. This structure moves the power actuation component out of the high temperature and high pressure melt area, ensuring the reliability of the mechanical structure.

[0039] Please see the appendix Figure 5 and attached Figure 7The head housing 13 has two feed holes 14, each connected to one of the two discharge pipes 12. A hollow sleeve 15 is slidably inserted into the inner hole of the head housing 13 along the axial direction. The hollow sleeve 15 is made of nitrided steel and has extremely high surface hardness and wear resistance. The side wall of the hollow sleeve 15 has two flow holes 17, each cooperating with one of the two feed holes 14. The interior of the hollow sleeve 15 has two conical cavities 18 machined sequentially along the direction of the wire travel. The two conical cavities 18 are connected by a passage hole 19. The two flow holes 17 are connected to the large-diameter ends of the two conical cavities 18, forming a pressure equalization and diversion structure to ensure coverage. The material is uniformly extruded into the wire. The diameter of the outlet end of the conical cavity 18 near the outlet end is larger than that of the outlet end of the conical cavity 18 near the inlet end, in order to accommodate the overall wire diameter after the addition of the outer layer material. Its outlet end is connected to the forming channel 20. The hollow sleeve 15 is located on the side of the inlet end and a core tube 21 is fixedly inserted inside. The tip of the outlet end of the core tube 21 extends to the center of the conical cavity 18 near the inlet end. The core tube 21 has micro-holes through which the power supply wire passes. These micro-holes form a gap seal with the wire, and the flow viscosity of the polymer melt generates physical resistance to prevent high-pressure material from overflowing to the inlet end.

[0040] Please see the appendix Figure 6 and attached Figure 8 The extrusion head housing 13 is divided into two independent extrusion areas along the axial direction by the thermal isolation flange 22. The bottom outer wall of the thermal isolation flange 22 has three air inlets 23 evenly distributed. The interior of the thermal isolation flange 22 is machined with an inner air passage 24 and an outer air passage 25. The central air inlet 23 is connected to the inner air passage 24. The outlet opening of the inner air passage 24 extends towards the outer wall of the hollow sleeve 15. The air inlets 23 on both sides are connected to the outer air passage 25. The outer air passage 25 has a groove-shaped structure and is distributed on the two side end faces of the thermal isolation flange 22. This groove-shaped cutting structure reduces the solid heat transfer cross-sectional area on both sides of the flange. The collection cover 26 is a semi-annular hollow sheet metal shell that is fastened and wrapped around the upper outer ring of the thermal isolation flange 22. The air inlet 23 is connected to room temperature gas. The airflow washes the outer wall of the hollow sleeve 15 and the end face of the thermal isolation flange 22, absorbing and blocking the heat conducted from the high temperature area to the low temperature area. Then the airflow rises and converges into the collection cover 26.

[0041] Please see the appendix Figure 1 and attached Figure 9The exhaust end of the top of the collection hood 26 is connected to the inlet end of the diversion valve 27. The diversion valve 27 is an asymmetric proportional regulating valve. The main outlet end of the diversion valve 27 is connected to the first air guide pipe 28, and the bypass throttling outlet end is connected to the second air guide pipe 30. Both feed hoppers 31 are externally connected to pneumatic vibrators 29 via flanges. A micro fluidized bed 32 is provided in the interlayer of the bottom inner wall of the feed hopper 31. The micro fluidized bed 32 is made of stainless steel sintered permeable plate material to ensure uniform pore size distribution and high temperature resistance. The first air guide pipe 28 is connected to the air inlet of the pneumatic vibrator 29, and the second air guide pipe 30 passes through the wall of the feed hopper 31 and is connected to the micro fluidized bed 32. The hot air with residual pressure discharged from the collection hood 26 is distributed at the diversion valve 27. The high-pressure air enters the pneumatic vibrator 29 to generate mechanical impact force, which breaks the bridging and agglomeration of the material in the feed hopper 31. The low-pressure hot air after throttling and depressurization enters the micro fluidized bed 32 and penetrates the material from bottom to top, using residual heat to dehumidify the plastic particles.

[0042] During normal extrusion operation, the tension of the wire causes the movable pulley 5 to rise, pulling the swing arm 7 to remain horizontal. The absolute angle encoder 6 outputs a normal position signal, and the linear cylinder 33 pushes the hollow sleeve 15, aligning the flow hole 17 with the feed hole 14. The material smoothly enters the conical cavity 18 to complete the double-layer coating. The gas in the air passage continuously blocks heat conduction and transports the heat it carries to the feed hopper 31 to assist production. When the wire breaks and the tension disappears, the counterweight 9 pulls the swing arm 7 downward. The absolute angle encoder 6 detects the sudden change in angle and sends a signal. The control system triggers the linear cylinder 33 to retract, and the hollow sleeve 15 is pulled axially through the shift fork 34. The two flow holes 17 are simultaneously deviated from the feed hole 14. The solid side wall of the hollow sleeve 15 blocks the lower port of the feed hole 14, thereby cutting off the supply of high-pressure melt at the flow channel level. The components of the system rely on mechanical transmission and air distribution to form a linkage, and complete the coating, temperature control, drying and flow interception actions in an integrated manner.

[0043] Working principle: During equipment startup and heat management, an external air source introduces ambient temperature gas into the three air inlets 23 at the bottom of the heat-insulating flange 22. Gas entering the central air inlet 23 flows out along the inner air passage 24, directly scouring the outer wall of the hollow sleeve 15. Gas entering the two side air inlets 23 flows along the outer air passage 25, passing through the grooved structure on the side end face of the heat-insulating flange 22. During the flow, the gas absorbs the heat conducted from the two side casings 13 to the center, cutting off the solid heat conduction path between the high-temperature zone and the low-temperature zone, maintaining the independent set temperature on both sides of the casing 13. After absorbing heat, the gas temperature rises and floats upward, converging... The airflow, carrying residual heat and pressure, is collected in the collection hood 26 at the top of the heat-insulating flange 22. It then exits from the collection hood 26 and enters the diversion valve 27 for proportional distribution. The diversion valve 27 distributes the high-pressure airflow to the first air guide pipe 28, driving the pneumatic vibrator 29 to generate continuous mechanical vibration. This vibration is transmitted to the outer wall of the feed hopper 31, disrupting the bridging structure of the plastic material. The diversion valve 27 distributes the throttled and depressurized hot airflow to the second air guide pipe 30. The hot airflow enters the jacket at the bottom of the feed hopper 31, passes through the micropores of the micro fluidized bed 32 from bottom to top, and is dispersed and blown into the interior of the material. The recovered waste heat is used to heat and dry the material in the feed hopper 31.

[0044] During normal extrusion operation, the traction device drives the cable forward. The cable, in a U-shape, passes sequentially around two fixed pulleys 3 on the floor frame 2 and a movable pulley 5 below. The cable is taut, applying an upward lifting tension to the movable pulley 5. This tension overcomes the weight of the counterweight 9, keeping the swing arm 7 within the horizontally set working range. During this process, the end slider 11 slides up and down within the guide groove 10 of the bracket 4, restricting the vertical lifting of the movable pulley 5. Simultaneously, the central axis of the movable pulley 5 slides horizontally within the strip window 8 of the swing arm 7, eliminating mechanical motion interference. The absolute angle encoder 6 detects that the swing arm 7 is within the normal angle range and outputs a normal operation signal. The linear cylinder 33 remains extended according to system instructions, and the fork 3... 4 and the slot 16 position the hollow sleeve 15, so that the two flow holes 17 on the side wall of the hollow sleeve 15 are aligned with the two feed holes 14 on the die head shell 13 respectively. The two extruders 1 press the molten inner layer material and outer layer material into the feed hole 14 through the discharge pipe 12, and then enter the hollow sleeve 15 through the flow holes 17. The material flows along the two conical cavities 18 inside the hollow sleeve 15 and the pressure is homogenized. The wire passes through the micro hole of the die core tube 21 and enters the conical cavity 18. The micro hole of the die core tube 21 and the wire form a gap seal. The high pressure material is blocked from flowing back to the wire end by the physical barrier of the melt viscosity. The wire passes through the two conical cavities 18 and the passage hole 19 in sequence to complete the concentric coating of the double layer material. Finally, it is continuously extruded by the forming channel 20.

[0045] During the wire breakage feedback stage, when the wire breaks or the traction tension disappears abnormally, the movable pulley 5 loses the upward lifting force of the wire, and the gravity of the counterweight 9 instantly pulls the swing arm 7 to rotate downward around the central axis. The absolute angle encoder 6 detects the sudden change in the rotation angle of the swing arm 7 in real time and immediately sends an abnormal signal to the control system. After receiving the signal, the control system triggers the linear cylinder 33 to act. The output shaft of the linear cylinder 33 quickly retracts, driving the shift fork 34 to move towards the wire inlet. The shift fork 34 pulls the hollow sleeve 15 to move axially within the die head housing 13. The translation of the hollow sleeve 15 causes the two flow holes 17 on the side wall to simultaneously deviate from the position of the feed hole 14. The solid metal side wall of the hollow sleeve 15 moves to below the feed hole 14, sealing the flow path of the feed hole 14. This action directly cuts off the path of the high-pressure coated material into the conical cavity 18 from the physical structure level, stopping the extrusion action inside the die head housing 13 and preventing melt overflow and wire breakage tailing.

Claims

1. An extrusion coating molding apparatus for double-layer insulated wires, characterized in that, include: Two extruders (1) are used to inject inner coating material and outer coating material respectively. The top of the two extruders (1) is connected to a feed hopper (31), and the discharge end of the two extruders (1) is connected to a discharge pipe (12). The machine head housing (13) has two feed holes (14) that are respectively connected to the two discharge pipes (12). A hollow sleeve (15) is slidably inserted into the machine head housing (13) along the axial direction. The side wall of the hollow sleeve (15) has two flow holes (17) that are respectively matched with the two feed holes (14). The tension sensing component is located outside the inlet end of the machine head housing (13), including a floor frame (2), a movable pulley (5), a swing arm (7), and an absolute angle encoder (6). The absolute angle encoder (6) is mounted on the floor frame (2) by a support, and the central axis of the absolute angle encoder (6) is connected to the left end of the swing arm (7). The movable pulley (5) is used for the power supply line to pass through and bear the tension of the wire. The absolute angle encoder (6) is used to detect the rotation angle of the swing arm (7). The misaligned flow-stopping assembly includes a linear cylinder (33) and a shift fork (34) disposed outside the machine head housing (13). The output end of the linear cylinder (33) is connected to one end of the hollow sleeve (15) through the shift fork (34). The linear cylinder (33) is controlled by the signal fed back by the absolute angle encoder (6) to drive the hollow sleeve (15) to slide axially, so that the two flow holes (17) are misaligned with the two feed holes (14) to close the flow channel. The thermal isolation and waste heat recovery assembly includes a thermal isolation flange (22) and a collection hood (26) located in the middle section of the machine head housing (13). The thermal isolation flange (22) is provided with an air inlet (23) for inward ventilation. The collection hood (26) covers the outside of the thermal isolation flange (22). Pneumatic vibrators (29) are fixed to the outside of the two feed hoppers (31). The bottom inner wall of the two feed hoppers (31) is provided with a micro fluidized bed (32). The exhaust end of the collection hood (26) is connected to the air inlet end of the diversion valve (27). The two air outlets of the diversion valve (27) are respectively connected to the first air guide pipe (28) and the second air guide pipe (30). The first air guide pipe (28) is connected to the pneumatic vibrator (29), and the second air guide pipe (30) is connected to the micro fluidized bed (32).

2. The extrusion coating molding apparatus for double-layer insulated wires according to claim 1, characterized in that, The tension sensing component also includes a fixed pulley (3) and a bracket (4). Two fixed pulleys (3) are rotatably mounted on the floor frame (2) and are arranged in parallel. A vertically arranged guide groove (10) is provided on the bracket (4). A strip window (8) is provided in the middle of the swing arm (7). The movable pulley (5) is located below the two fixed pulleys (3). The end of the central axis of the movable pulley (5) passes through the strip window (8) and has an end slider (11) at its end. The end slider (11) is slidably fitted into the guide groove (10).

3. The extrusion coating molding apparatus for double-layer insulated wires according to claim 2, characterized in that, A counterweight (9) is suspended at the end of the swing arm (7) away from the absolute angle encoder (6); the two fixed pulleys (3) and the movable pulley (5) are arranged in a U-shape so that the power supply line passes around them in sequence.

4. The extrusion coating molding apparatus for double-layer insulated wires according to claim 1, characterized in that, The die head housing (13) is divided into two independent extrusion areas along the axial direction by the heat insulation flange (22). The interior of the hollow sleeve (15) is connected, and two conical cavities (18) are sequentially processed along the direction of wire travel. The two conical cavities (18) are connected by a passage hole (19). The two flow holes (17) are respectively connected to the large diameter ends of the two conical cavities (18). The diameter of the outlet end of the conical cavity (18) near the wire outlet end is larger than the diameter of the outlet end of the conical cavity (18) near the wire inlet end. The outlet end of the conical cavity (18) near the wire outlet end is connected to a forming channel (20).

5. The extrusion coating molding apparatus for double-layer insulated wires according to claim 4, characterized in that, The hollow sleeve (15) has a mold core tube (21) fixedly inserted inside on one side of the inlet end. The mold core tube (21) has a micro hole through which the power supply line passes, and the micro hole is configured to form a gap seal with the wire. The tip of the outlet end of the mold core tube (21) extends to the center of the conical cavity (18) near the inlet end.

6. The extrusion coating molding apparatus for double-layer insulated wires according to claim 1, characterized in that, The hollow sleeve (15) extends from the discharge pipe (12) to the outside of the machine head housing (13), and a groove (16) is provided around the surface of the extended end. The upper end of the shift fork (34) is directly inserted into the groove (16). The linear cylinder (33) is horizontally fixedly installed below the machine head housing (13), and the lower end of the shift fork (34) is rigidly fixed to the output shaft of the linear cylinder (33).

7. The extrusion coating molding apparatus for double-layer insulated wires according to claim 1, characterized in that, The air inlet (23) is provided in three parts, and the three air inlet (23) are evenly distributed on the bottom outer wall of the heat insulation flange (22). The heat insulation flange (22) has an inner air passage (24) and an outer air passage (25) inside. The central air inlet (23) is connected to the inner air passage (24), and the air outlet of the inner air passage (24) extends toward the outer wall of the hollow sleeve (15). The air inlet (23) located on both sides is connected to the outer air passage (25). The outer air passage (25) has a groove structure and is distributed on the two side end faces of the heat insulation flange (22).

8. The extrusion coating molding apparatus for double-layer insulated wires according to claim 7, characterized in that, The collection hood (26) is a semi-annular hollow shell. The collection hood (26) is fastened and wrapped around the upper outer ring of the thermal isolation flange (22) to collect the airflow discharged from the inner air passage (24) and the outer air passage (25).

9. The extrusion coating molding apparatus for double-layer insulated wires according to claim 8, characterized in that, The exhaust end of the top of the collection hood (26) is connected to the inlet end of the diversion valve (27). The diversion valve (27) is an asymmetric proportional regulating valve. The main outlet end of the diversion valve (27) is connected to the first air guide pipe (28), and the bypass throttling outlet end of the diversion valve (27) is connected to the second air guide pipe (30).

10. The extrusion coating molding apparatus for double-layer insulated wires according to claim 9, characterized in that, The first air guide pipe (28) is connected to the air inlet of the pneumatic vibrator (29) and is used to drive the pneumatic vibrator (29) to apply mechanical vibration to the outer wall of the feed hopper (31) by airflow; the micro fluidized bed (32) is a breathable plate with micropores on its surface and is laid in the lower half of the inner wall of the feed hopper (31). The second air guide pipe (30) passes through the wall of the feed hopper (31) and is connected to the micro fluidized bed (32) and is used to blow airflow from bottom to top into the interior of the feed hopper (31).

Images