A super smooth self-cleaning type iron-fluorine dragon inlaying mouth mould for low smoke halogen-free B1 grade cable material extrusion

Abstract

The application discloses a super-smooth self-cleaning type Teflon inlaid orifice die for low-smoke halogen-free B1 grade cable material extrusion, which comprises a metal base body, a tapered flow channel is formed in the center of the metal base body, a polytetrafluoroethylene lining is closely inlaid on the inner wall of the tapered flow channel, and a smooth extrusion flow channel is formed on the inner surface of the polytetrafluoroethylene lining; a flange connecting part is arranged at one end of the metal base body, the other end is an extrusion end, the end surface of the polytetrafluoroethylene lining is flush with the extrusion end surface of the metal base body; and at least two installation through holes are uniformly formed on the metal base body in the circumferential direction. The polytetrafluoroethylene lining is nested on the inner wall of the tapered flow channel of the metal base body, thereby greatly reducing the friction resistance between the melt and the inner wall of the orifice die, effectively eliminating the defects of cable surface frosted, pinhole and pitting, and significantly improving the surface finish of the cable; meanwhile, the shear stress of the melt extrusion can be effectively reduced, decomposition of the B1 grade cable material during high-speed extrusion is avoided, and the application is convenient for promotion and implementation.

Description

Technical Field

[0001] This invention relates to the field of cable extrusion die technology, and in particular to an ultra-smooth, self-cleaning Teflon insert die for extruding low-smoke, halogen-free B1 grade cable material. Background Technology

[0002] In existing technologies, the die is a core component of the cable extrusion production line, directly determining the surface quality, dimensional accuracy, and production efficiency of the cable sheath or insulation layer. In the extrusion production of low-smoke halogen-free B1 grade cable materials, the performance of the die is particularly important, directly affecting the cable's combustion performance and appearance quality. While commonly used stainless steel dies possess high strength and hardness, capable of withstanding high extrusion pressures, they have some shortcomings in the extrusion production of low-smoke halogen-free B1 grade cable materials. Stainless steel has high surface energy and lacks self-lubricating properties. When B1 grade cable materials (high-filling, high-viscosity) flow within the die, the frictional resistance with the die wall is high, easily leading to stagnation, material adhesion, and shear overheating. This results in localized melt decomposition and bubble precipitation, directly causing surface defects such as roughness, pinholes, pitting, and streaks, which are major sources of quality defects on the production floor. Uneven melt flow also results in poor cable surface finish, failing to meet the appearance requirements of high-end products. Furthermore, the high friction of the stainless steel die wall generates extremely high shear stress. Flame-retardant fillers such as aluminum hydroxide or magnesium hydroxide and the matrix resin in B1 grade cable materials are prone to shear overheating and decomposition under high shear, resulting not only in bubbles and scorching but also in damage to the material's flame-retardant and mechanical properties, leading to substandard B1 grade flammability. During high-speed extrusion, shear heat increases exponentially, further amplifying defects and making stable high-speed production impossible. Therefore, to comprehensively improve the surface quality, production efficiency, and product performance stability of low-smoke halogen-free B1 grade cable material extrusion dies, improvements are urgently needed to enhance the product quality and market competitiveness of cable manufacturers. Summary of the Invention

[0003] In order to solve the technical problems in the prior art, the stainless steel die used for extruding low-smoke halogen-free B1 grade cable material has high surface friction, which easily leads to appearance defects such as sanding, pinholes, and pitting. The high shear stress also aggravates the degradation and performance deterioration of B1 grade cable material, making it impossible to achieve stable and high-speed production. This application proposes an ultra-smooth self-cleaning Teflon-insulated die for extruding low-smoke halogen-free B1 grade cable material.

[0004] This application adopts the following solution: a super-smooth, self-cleaning Teflon-insulated die for extruding low-smoke, halogen-free B1 grade cable material, comprising a metal substrate, a conical flow channel formed at the center of the metal substrate, a polytetrafluoroethylene (PTFE) liner inserted into the inner wall of the conical flow channel, and a smooth extrusion channel coaxial with the conical flow channel formed on the inner surface of the PTFE liner; a flange connection is provided at one end of the metal substrate for fixed connection with the extruder head, and the other end of the metal substrate is the extrusion end, with the end face of the PTFE liner flush with the extrusion end face of the metal substrate; at least two mounting through holes are uniformly formed along the circumferential direction on the metal substrate, the mounting through holes penetrating the flange connection for fixing the die to the extruder head by bolts.

[0005] In some feasible embodiments, the cone angle of the conical flow channel is 15°-30°, the thickness of the polytetrafluoroethylene liner is 3mm-8mm, and the inner surface roughness Ra of the polytetrafluoroethylene liner is ≤0.2μm. Specifically, the cone angle is the full included angle between the two generatrices of the conical flow channel.

[0006] In some feasible embodiments, an annular dovetail groove is formed on the inner wall of the conical flow channel, and an annular protrusion adapted to the annular dovetail groove is formed on the outer surface of the polytetrafluoroethylene liner. The annular protrusion is embedded in the annular dovetail groove to achieve axial and circumferential fixation between the polytetrafluoroethylene liner and the metal substrate.

[0007] In some feasible embodiments, the number of annular dovetail grooves is 2-3, which are evenly distributed along the axial direction of the conical flow channel, and the distance between two adjacent annular dovetail grooves is 10mm-20mm.

[0008] In some feasible embodiments, an annular temperature control channel is provided inside the metal substrate, the annular temperature control channel is arranged around the conical flow channel, and an inlet and an outlet communicating with the annular temperature control channel are provided on the side wall of the metal substrate for introducing a heat-conducting medium to control the working temperature of the die.

[0009] In some feasible embodiments, the cross-section of the annular temperature control channel is circular or rectangular, and the distance between the annular temperature control channel and the inner wall of the conical flow channel is 5mm-10mm.

[0010] In some feasible embodiments, an annular venting groove is formed on the extruded end face of the metal matrix. The annular venting groove is coaxial with the inner hole of the polytetrafluoroethylene liner. The depth of the annular venting groove is 0.1mm-0.3mm and the width is 1mm-3mm.

[0011] In some feasible embodiments, the metal substrate is made of stainless steel or mold steel, and the polytetrafluoroethylene liner is made of filled modified polytetrafluoroethylene.

[0012] In some feasible embodiments, the polytetrafluoroethylene liner is fixed in the conical flow channel of the metal substrate by a hot-pressing embedding process, and the bonding strength between the polytetrafluoroethylene liner and the metal substrate is ≥5MPa.

[0013] In some feasible embodiments, the filled modified polytetrafluoroethylene comprises, by weight, the following components: 70-85 parts polytetrafluoroethylene resin, 10-20 parts reinforcing filler, 3-8 parts solid lubricant, and 0.5-2 parts antioxidant; the reinforcing filler is a mixture of glass fiber and carbon fiber, with a weight ratio of glass fiber to carbon fiber of 1:1; the solid lubricant is a mixture of graphite and molybdenum disulfide, with a weight ratio of graphite to molybdenum disulfide of 2:1; and the antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0014] Compared with the prior art, this application has the following beneficial effects:

[0015] This application provides an ultra-smooth, self-cleaning Teflon-inserted die for extruding low-smoke halogen-free B1 grade cable material. It includes a metal substrate, a conical flow channel at the center of the metal substrate, and a polytetrafluoroethylene (PTFE) liner tightly embedded in the inner wall of the conical flow channel. The inner surface of the PTFE liner forms a smooth extrusion channel. The low-smoke halogen-free B1 grade cable material melt enters from the large end of the conical flow channel along the extrusion direction, passes through the smooth extrusion channel of the PTFE liner, and is extruded from the small end. This invention, by embedding a PTFE liner in the inner wall of the conical flow channel of the metal substrate, utilizes the extremely low surface energy and excellent self-lubricating properties of PTFE to significantly reduce the frictional resistance between the melt and the inner wall of the die. This avoids material buildup, stagnation, and shear overheating at the die, fundamentally eliminating surface abrasion, pinholes, and pitting defects caused by uneven melt flow and localized overheating, significantly improving the surface finish of the cable. Meanwhile, the low-friction properties of PTFE effectively reduce the shear stress during melt extrusion, preventing decomposition and bubble formation caused by shear overheating during high-speed extrusion of B1-grade cable materials. This ensures that the melt is fully and uniformly plasticized within the die, achieving a 15%-30% speed increase without sacrificing surface quality, thus improving production efficiency. Furthermore, the low-friction, highly smooth flow channel makes the melt extrusion pressure more stable, significantly reducing fluctuations. This effectively controls the cable's outer diameter tolerance, wall thickness uniformity, and eccentricity, improving product qualification rates. PTFE's excellent high and low temperature stability also prevents the decomposition of the B1-grade cable material's matrix resin and flame retardant due to localized overheating of the die, ensuring that the material's flame retardant and mechanical properties remain unaffected, meeting B1-grade flammability standards. It boasts advantages such as simple structure, convenient processing, long service life, low implementation cost, and ease of promotion and implementation. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural schematic diagram of an ultra-smooth, self-cleaning Teflon-inserted die for extruding low-smoke, halogen-free B1 grade cable material, provided in an embodiment of the present invention.

[0017] Figure 2 This is a cross-sectional structural schematic diagram of an ultra-smooth, self-cleaning Teflon-inserted die for extruding low-smoke, halogen-free B1 grade cable material, provided in an embodiment of the present invention.

[0018] 1-Metal matrix; 2-Conical flow channel; 3-PTFE liner; 4-Smooth extrusion flow channel; 5-Flange connection; 6-Extrusion end; 7-Mounting through hole; 8-Annular dovetail groove; 9-Annular protrusion; 10-Annular temperature control channel; 11-Liquid inlet; 12-Liquid outlet; 13-Annular venting groove. Detailed Implementation

[0019] The technical solution of the present invention will now be clearly and completely described through specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1 and Figure 2 This application provides an ultra-slippery, self-cleaning Teflon-inserted die for extruding low-smoke halogen-free B1 grade cable material, comprising a metal substrate 1. The metal substrate 1 is made of 304 stainless steel or Cr12MoV die steel, possessing high strength, hardness, and corrosion resistance, and capable of withstanding the high temperature and pressure during extrusion. A conical flow channel 2 is formed at the center of the metal substrate 1, with the larger end of the conical flow channel 2 serving as the feed end and the smaller end as the discharge end. The cone angle of the conical flow channel 2 is 15°-30°, preferably 20°. This cone angle design allows the low-smoke halogen-free B1 grade cable material melt to transition smoothly within the flow channel, avoiding the generation of eddies and stagnation.

[0021] In this embodiment, a polytetrafluoroethylene (PTFE) liner 3 is tightly embedded in the inner wall of the conical flow channel 2. The inner surface of the PTFE liner 3 forms a smooth extrusion channel 4 coaxial with the conical flow channel 2. The thickness of the PTFE liner 3 is 3mm-8mm, preferably 5mm, which ensures sufficient structural strength without affecting the overall heat dissipation performance of the die. The inner surface of the PTFE liner 3 is precision polished, with a roughness Ra≤0.2μm, further reducing the frictional resistance between the melt and the inner wall of the flow channel.

[0022] Furthermore, the PTFE liner 3 is divided into a feed section liner and a discharge section liner along the axial direction, and the two sections are connected by a stepped surface fit. The inner wall of the conical flow channel 2 of the metal matrix 1 is provided with corresponding positioning steps that mate with the two liner sections. The length of the feed section liner accounts for 60%-70% of the total liner length, and the length of the discharge section liner accounts for 30%-40% of the total liner length. The discharge end of the discharge section liner is flush with the discharge end face of the metal matrix 1. The feed section liner and the discharge section liner are respectively embedded in the corresponding positioning steps of the metal matrix 1 using an interference fit. A gap of 0.05mm-0.1mm is provided between the mating step surfaces of the two liner sections to compensate for thermal expansion. The discharge section is the part with the fastest melt flow rate and the most severe erosion, and it is also the part most prone to wear. With the segmented structure, when the discharge section liner wears out, only the discharge section liner can be replaced, eliminating the need to replace the entire PTFE liner and further reducing maintenance costs. At the same time, the segmented structure reduces the processing difficulty of long liners, facilitating liner installation and removal.

[0023] In this embodiment, a flange connection 5 is provided at one end of the metal substrate 1 for fixed connection with the extruder head. The outer diameter of the flange connection 5 is larger than the outer diameter of the main body of the metal substrate 1, forming a stepped structure for easy positioning and installation. The other end of the metal substrate 1 is the extrusion end 6. The end face of the polytetrafluoroethylene liner 3 is flush with the extrusion end face of the metal substrate 1 to prevent the melt from accumulating and sticking at the extrusion end.

[0024] In this embodiment, at least two mounting through holes 7 are evenly provided along the circumferential direction on the metal substrate 1. In this embodiment, there are two. The mounting through holes 7 penetrate the flange connection part 5 and are used to fix the die to the extruder head by bolts. The number of mounting through holes 7 can be adjusted according to the size of the die and the extrusion pressure, and is generally 2-4.

[0025] In this embodiment, to prevent axial and circumferential loosening of the PTFE liner 3 under high temperature and pressure, annular dovetail grooves 8 are formed on the inner wall of the conical flow channel 2. Correspondingly, annular protrusions 9 are formed on the outer surface of the PTFE liner 3 to match the annular dovetail grooves 8. The annular protrusions 9 are embedded in the annular dovetail grooves 8, achieving reliable fixation between the PTFE liner 3 and the metal substrate 1. There are 2-3 annular dovetail grooves 8, evenly distributed along the axial direction of the conical flow channel 2, with a spacing of 10mm-20mm between adjacent annular dovetail grooves 8. In this embodiment, there are two annular dovetail grooves 8, located near the feed end and in the middle of the conical flow channel 2, respectively.

[0026] In this embodiment, to precisely control the working temperature of the die and avoid local overheating leading to the decomposition of B1 grade cable material, an annular temperature control channel 10 is provided inside the metal substrate 1, surrounding the conical flow channel 2. An inlet 11 and an outlet 12, communicating with the annular temperature control channel 10, are provided on the side wall of the metal substrate 1 for introducing heat transfer media such as heat transfer oil or water. The cross-section of the annular temperature control channel 10 is circular or rectangular; in this embodiment, it is circular with a diameter of 6 mm. The distance between the annular temperature control channel 10 and the inner wall of the conical flow channel 2 is 5 mm-10 mm, preferably 7 mm, ensuring good heat conduction without affecting the structural strength of the metal substrate 1. This invention controls the temperature and flow rate of the heat transfer medium through a temperature control system, precisely controlling the working temperature of the die within ±5℃, ensuring that the B1 grade cable material is extruded within the optimal temperature range.

[0027] In this embodiment, an annular venting groove 13 is formed on the end face of the extrusion end 6 of the metal substrate 1. The annular venting groove 13 is coaxial with the inner hole of the polytetrafluoroethylene liner 3. The depth of the annular venting groove 13 is 0.1mm-0.3mm, and the width is 1mm-3mm. In this embodiment, the depth is 0.2mm and the width is 2mm. The annular venting groove 13 can timely discharge the small amount of gas generated during the molten extrusion process, preventing the gas from being trapped in the molten material and forming bubbles and pinholes, thereby further improving the surface quality of the cable.

[0028] In actual implementation, several inclined anti-reverse teeth are evenly distributed on the two inner sidewalls of the annular dovetail groove 8. The inclination direction of the anti-reverse teeth faces the feed end of the conical flow channel 2, with a tooth height of 0.3mm-0.5mm, a tooth pitch of 2mm-3mm, and an inclination angle of 30°-45°. Correspondingly, on the two outer sidewalls of the annular protrusion 9 of the PTFE liner 3, meshing teeth adapted to the anti-reverse teeth are molded. The PTFE liner 3 is embedded in the conical flow channel 2 of the metal substrate 1 using a hot molding process. During the molding process, it is ensured that the PTFE material fully fills all gaps in the annular dovetail groove 8, so that the anti-reverse teeth and the meshing teeth form a tight mechanical engagement. The structure with anti-reverse teeth improves the axial anti-detachment capability by more than 3 times and can withstand higher extrusion pressure. When the PTFE liner undergoes slight axial deformation due to thermal expansion, the meshing action of the anti-reverse teeth can effectively limit the liner from moving towards the discharge end, ensuring the long-term stability of the flow channel dimensions.

[0029] In this embodiment, the PTFE liner 3 is made of filled modified PTFE. The filled modified PTFE, by weight, comprises the following components: 70-85 parts PTFE resin, 10-20 parts reinforcing filler, 3-8 parts solid lubricant, and 0.5-2 parts antioxidant. The reinforcing filler is a mixture of glass fiber and carbon fiber, with a weight ratio of glass fiber to carbon fiber of 1:1. The solid lubricant is a mixture of graphite and molybdenum disulfide, with a weight ratio of graphite to molybdenum disulfide of 2:1. The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. The filled modified PTFE not only retains its original low friction, self-lubricating, and high / low temperature resistance properties, but also significantly improves its wear resistance and compressive strength, increasing its service life by 2-3 times compared to pure PTFE.

[0030] In actual implementation, the preparation method of modified polytetrafluoroethylene includes the following steps: Step 101. Add polytetrafluoroethylene resin, reinforcing filler, solid lubricant and antioxidant to a high-speed mixer according to the weight parts, and mix for 10min-15min at room temperature and 1500r / min-2000r / min to obtain a uniform mixed powder;

[0031] Step 102. Add the mixed powder into a cylindrical mold and cold press it under a pressure of 20MPa-30MPa for 5min-10min to obtain a cylindrical blank;

[0032] Step 103. Place the cylindrical blank into a sintering furnace and heat it to 360℃-380℃ at a heating rate of 50℃ / h-100℃ / h, and hold it at that temperature for 2h-4h for sintering.

[0033] Step 104. Cool to room temperature at a cooling rate of 20℃ / h-50℃ / h to obtain filled modified polytetrafluoroethylene rods.

[0034] Furthermore, the preparation method of the polytetrafluoroethylene liner includes the following steps: Step 201. The filled modified polytetrafluoroethylene rods prepared above are processed by CNC lathe into a liner blank that matches the shape of the tapered flow channel 2 of the metal matrix 1, with an interference of 0.1mm-0.2mm reserved on the outer surface.

[0035] Step 202. Perform precision grinding and polishing on the inner surface of the lining blank to make its surface roughness Ra≤0.2μm, and obtain polytetrafluoroethylene lining 3.

[0036] Furthermore, the hot-pressing embedding method of polytetrafluoroethylene liner and metal substrate includes the following steps: Step 301. Sandblasting is performed on the inner wall of the conical flow channel 2 of the metal substrate 1 to make its surface roughness Ra reach 6.3μm-12.5μm, and then ultrasonic cleaning is performed with anhydrous ethanol for 10min-15min to remove surface oil and impurities, and then dried for later use.

[0037] Step 302. Place the metal substrate 1 in a box-type resistance furnace and heat it to 320℃-350℃, hold it at that temperature for 30min-60min, so that the metal substrate 1 is heated evenly.

[0038] Step 303. Quickly place the polytetrafluoroethylene liner 3 into the heated conical flow channel 2, apply an axial pressure of 5MPa-10MPa using a hydraulic press, and maintain it for 10min-15min to fully deform the polytetrafluoroethylene liner 3 and make it fit tightly against the inner wall of the conical flow channel 2, while making the annular protrusion 9 completely embedded in the annular dovetail groove 8.

[0039] Step 304. Allow the material to cool naturally to room temperature, remove excess flash, and obtain the finished die. At this point, the bond strength between the PTFE liner 3 and the metal substrate 1 is ≥5MPa.

[0040] During operation, the die of this invention is fixed to the extruder head via the flange connection 5 and the mounting through hole 7, and the piping of the temperature control system is connected. The low-smoke halogen-free B1 grade cable material melt is conveyed to the die head by the extruder screw, enters the conical flow channel 2 of the die, passes through the smooth extrusion flow channel 4 of the polytetrafluoroethylene (PTFE) liner 3, and is extruded from the extrusion end 6 to form a cable sheath or insulation layer. During the extrusion process, the extremely low surface energy and self-lubricating properties of the PTFE liner 3 significantly reduce the frictional resistance between the melt and the inner wall of the flow channel, avoiding melt adhesion, stagnation, and shear overheating, thus eliminating surface defects such as abrasion, pinholes, and pitting at the source. Simultaneously, the low friction characteristics reduce the shear stress of the melt, preventing the decomposition and performance degradation of the B1 grade cable material due to shear overheating, ensuring the flame retardant and mechanical properties of the cable. Furthermore, stable extrusion pressure and precise temperature control effectively improve the dimensional accuracy and wall thickness uniformity of the cable, significantly increasing the product qualification rate. Without sacrificing surface quality, the extrusion speed can be increased by 15%-30%, significantly improving production efficiency.

[0041] In summary, this invention discloses an ultra-smooth, self-cleaning Teflon-inserted die for extruding low-smoke, halogen-free B1 grade cable material, comprising a metal substrate, a conical flow channel at the center of the metal substrate, a polytetrafluoroethylene (PTFE) liner tightly inlaid on the inner wall of the conical flow channel, and a smooth extrusion flow channel formed on the inner surface of the PTFE liner; a flange connection is provided at one end of the metal substrate, and the other end is the extrusion end, with the end face of the PTFE liner flush with the extrusion end face of the metal substrate; at least two mounting through holes are uniformly formed along the circumferential direction on the metal substrate. This invention utilizes the extremely low surface energy and excellent self-lubricating properties of PTFE (polytetrafluoroethylene) to significantly reduce the frictional resistance between the melt and the inner wall of the die, thereby eliminating surface defects such as abrasion, pinholes, and pitting, and significantly improving the surface smoothness of the cable. Simultaneously, it effectively reduces the shear stress during melt extrusion, preventing the decomposition of B1 grade cable material during high-speed extrusion, achieving a 15%-30% speed increase and improving production efficiency. Furthermore, it stabilizes the extrusion pressure, improves the dimensional accuracy and wall thickness uniformity of the cable, and ensures that the flame retardant and mechanical properties of the material remain unaffected.

[0042] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A super-slippery self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material, comprising a metal substrate, characterized in that: The metal substrate has a conical flow channel at its center, and a polytetrafluoroethylene (PTFE) liner is interference-fitted into the inner wall of the conical flow channel. The inner surface of the PTFE liner forms a smooth extrusion channel coaxial with the conical flow channel. One end of the metal substrate is provided with a flange connection for fixed connection with the extruder head, and the other end of the metal substrate is the extrusion end. The end face of the PTFE liner is flush with the extrusion end face of the metal substrate. At least two mounting through holes are evenly provided on the metal substrate along the circumferential direction. The mounting through holes penetrate the flange connection for fixing the die to the extruder head with bolts.

2. The super-slippery self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material according to claim 1, characterized in that: The cone angle of the conical flow channel is 15°-30°, the thickness of the polytetrafluoroethylene liner is 3mm-8mm, and the inner surface roughness Ra of the polytetrafluoroethylene liner is ≤0.2μm.

3. The ultra-smooth, self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material according to claim 1, characterized in that: The inner wall of the conical flow channel is provided with an annular dovetail groove, and the outer surface of the polytetrafluoroethylene liner is provided with an annular protrusion that matches the annular dovetail groove. The annular protrusion is embedded in the annular dovetail groove to achieve axial and circumferential fixation between the polytetrafluoroethylene liner and the metal substrate.

4. The ultra-slippery self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material according to claim 3, characterized in that: The number of annular dovetail grooves is 2-3, which are evenly distributed along the axial direction of the conical flow channel, and the distance between two adjacent annular dovetail grooves is 10mm-20mm.

5. The ultra-slippery self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material according to claim 1, characterized in that: The metal substrate has an annular temperature control channel inside, which surrounds the conical flow channel. The side wall of the metal substrate has an inlet and an outlet that communicate with the annular temperature control channel, for introducing a heat-conducting medium to control the working temperature of the die.

6. The super-slippery self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material according to claim 5, characterized in that: The cross-section of the annular temperature control channel is circular or rectangular, and the distance between the annular temperature control channel and the inner wall of the conical flow channel is 5mm-10mm.

7. The ultra-smooth, self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material according to claim 1, characterized in that: An annular venting groove is formed on the extruded end face of the metal matrix. The annular venting groove is coaxial with the inner hole of the polytetrafluoroethylene liner. The depth of the annular venting groove is 0.1mm-0.3mm and the width is 1mm-3mm.

8. The ultra-slippery self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material according to claim 1, characterized in that: The metal substrate is made of stainless steel or mold steel, and the polytetrafluoroethylene liner is made of filled modified polytetrafluoroethylene.

9. The super-slippery self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material according to claim 1, characterized in that: The polytetrafluoroethylene (PTFE) liner is fixed within the tapered flow channel of the metal substrate by a hot-pressing embedding process, and the bonding strength between the PTFE liner and the metal substrate is ≥5 MPa.

10. The super-slippery self-cleaning Teflon insert die for extruding low-smoke halogen-free B1 grade cable material according to claim 8, characterized in that: The modified polytetrafluoroethylene (PTFE) comprises, by weight, the following components: 70-85 parts PTFE resin, 10-20 parts reinforcing filler, 3-8 parts solid lubricant, and 0.5-2 parts antioxidant; the reinforcing filler is a mixture of glass fiber and carbon fiber, with a weight ratio of glass fiber to carbon fiber of 1:1; the solid lubricant is a mixture of graphite and molybdenum disulfide, with a weight ratio of graphite to molybdenum disulfide of 2:1; and the antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

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