Production method of parallel unit high-speed parallel transmission symmetrical cable

Abstract

The invention belongs to the technical field of cables, and mainly relates to a production method of a parallel unit high-speed parallel transmission symmetrical cable, which comprises the following steps of: polishing the surfaces of two inner conductors; a cavity segmented continuous injection molding process is adopted, a layer of insulating medium material is injected on the surfaces of the two inner conductors at the same time, and an insulating wire core is obtained; penetrating the insulating wire core into the flat copper pipe; the flat copper pipe is pulled out through an inner hole of a flat hole mold, so that the flat copper pipe and the insulated wire core are tightly attached to form a whole, and a semi-finished product is obtained; and sequentially carrying out a first buffer strip winding process, a filling process, a second buffer strip winding process, a tubular weaving process and a sheath forming process on the surface of the semi-finished product to obtain the parallel unit high-speed parallel transmission symmetric cable. The matched flat copper pipe is sleeved outside the flat insulated wire, so that the stress deformation is reduced, the electromagnetic field distribution between the two inner conductors is uniform, the transmission signal quality is improved, and the transmission bandwidth is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of cables, and mainly relates to a production method of a high-speed parallel transmission symmetrical cable for parallel units. Background Art

[0002] The existing high-speed parallel transmission symmetrical cables (hereinafter referred to as "high-speed cables") on the domestic market are implemented in accordance with the GB / T31834 standard. The structure of most of its basic transmission units is "parallel wire pairs". From the cross-section of the parallel wire pairs, the structure is two insulated single wires arranged in parallel, with a metal shielding layer wrapped outside, which conforms to the definition of 3.1 parallel wire pairs in GB / T 31834-2015 "High-speed Parallel Cables for Digital Communications up to 20 GHz".

[0003] For the high-speed cables with the above structure in the current market, when the length is 5 meters, the highest mature data transmission bandwidth of each unit can reach 112 Gbps; for shorter lengths such as 2 meters or 1 meter, the highest mature data transmission bandwidth of each unit can reach 224 Gbps.

[0004] However, for the requirements of the next-generation higher transmission bandwidth, such as a transmission bandwidth of up to 336 Gbps or 448 Gbps per unit, this structure can no longer meet the requirements. The reason is that the two insulated single wires are in the same shield, and in addition, the external shield adopts a "wrapping" process method to tightly wrap the two insulated single wires together. Since the contact between the two insulating layers of the parallel wire pair is circular-round contact, the contact point is very small and is easily deformed by force, resulting in the deformation of the cross-sectional shape of the insulation, changing from an ideal circular shape to an elliptical shape, and finally leading to an uneven electromagnetic field distribution between the two conductors, a decline in the transmission signal quality, and an inability to increase the transmission bandwidth.

[0005] In the existing process technology, the "wrapping" method of the shield outer conductor of the parallel wire pair is either by spiral winding (similar to winding electrical tape on the outer surface of the wire) or by parallel longitudinal wrapping (for example, the patent document with the authorization announcement number CN209433905U), and they are wrapped together. Since the shield outer conductor is completely tightly wrapped and attached to the insulated wire core, and the insulated wire core with a circular cross-section is easily deformed by external forces, the shape of the shield outer conductor is completely determined by the insulated wire core to be wrapped, and it cannot reach an ideal, smooth, seamless and continuous state by itself.

[0006] In addition, the insulated wires in the existing pair of parallel wires are formed by the cable extrusion process. After the insulating material flows out of the die orifice of the extrusion die, it moves horizontally at high speed in the air. In this way, before the insulating material is completely cooled and solidified, it is affected by the downward gravity, the horizontal wind resistance in the air when the wire core moves horizontally, and the complex fluid resistance in the cooling water when the wire core moves horizontally. Eventually, the outer diameter of the insulated wire core fluctuates greatly. For example, the outer diameter fluctuation range of a wire core with an outer diameter of 1.7 mm reaches ±0.05 mm. There is also the problem of conductor eccentricity caused by the downward flow of the uncooled and solidified insulating plastic.

[0007] The seemingly negligible effects mentioned above, when superimposed, ultimately result in the inability to increase the transmission bandwidth of the cable. Summary of the Invention

[0008] The present invention provides a production method for a parallel unit high-speed parallel transmission symmetric cable to solve the problem that the transmission bandwidth of the cable in the prior art cannot be increased.

[0009] To solve the above problems, the present invention adopts the following technical solutions: A production method for a parallel unit high-speed parallel transmission symmetric cable includes the following steps: Step 1: Polish the surfaces of two inner conductors. Step 2: Adopt a cavity segmented continuous injection molding process to simultaneously inject a layer of insulating dielectric material on the surfaces of the two inner conductors to obtain an insulated wire core. Step 3: Insert the insulated wire core into the inside of a flat copper tube. Step 4: Pull out the flat copper tube with the insulated wire core inserted through the inner hole of a flat hole die, so that the flat copper tube is closely attached to the insulated wire core inside it to form an integral body and obtain a semi-finished product. Step 5: Successively perform the first winding buffer tape process, filling process, second winding buffer tape process, tubular braiding process, and sheath forming process on the surface of the semi-finished product to obtain a parallel unit high-speed parallel transmission symmetric cable.

[0010] It has the following beneficial effects: The structure of the insulated conductor is a single flat insulated wire. Inside this flat insulated wire, there are two parallel inner conductors. The two inner conductors and the flat insulated wire are formed in one step to become an integral structure. A flat copper tube that matches the outer contour of the flat insulated wire is sleeved outside the flat insulated wire, reducing stress deformation. As a result, the electromagnetic field distribution between the two inner conductors is uniform, improving the transmission signal quality and thus increasing the transmission bandwidth. At the same time, the flat copper tube itself has shape plasticity, is smooth and seamless and continuous, approaching an ideal state, which is beneficial to increasing the transmission bandwidth. And through the cavity segmented continuous injection molding process, the problem of the inner conductor being eccentric due to the downward flow of the insulating dielectric material is eliminated, and at the same time, the outer diameter fluctuation of the insulated conductor is reduced, so that the electromagnetic field distribution between the two inner conductors is uniform, improving the signal transmission quality, and further increasing the transmission bandwidth.

[0011] Further, the surfaces of the two inner conductors are polished using a diamond wire drawing die, and the surface roughness (Sq) of the inner conductors is not greater than 0.2 um. The inner conductors are silver-plated copper wires, where the thickness of the silver plating layer is not less than 1 um, and the outer diameter fluctuation of the silver-plated copper wires is ±0.001 mm.

[0012] It has the following beneficial effects: Surface polishing makes the silver-plated copper surface reach a mirror effect. When observed under a 200-fold microscope, there are no any protrusions or indentations, no any impurities, and the silver layer is continuous without pinholes, copper leakage, etc. Using the polished silver-plated copper as the inner conductor can ensure that in the case of high frequencies, when the current flows on the silver layer on the surface of the silver-plated copper due to the skin effect, because the resistivity of silver is the lowest and the surface roughness is low, the effective resistance is relatively low, and the loss of the signal is small, so as to achieve a higher transmission bandwidth.

[0013] Further, the insulating dielectric material is one of low-density microporous PTFE, plastic resin with a lotus root-shaped cross-section, low-density foamed plastic resin, and plastic resin with an outer serrated cross-section.

[0014] It has the following beneficial effects: It can ensure that the dielectric loss is reduced to the lowest level, so as to achieve a higher transmission bandwidth.

[0015] Further, before the insulated conductor is inserted into the flat copper tube, a low-density resin tape is used to evenly wind around the surface of the insulated conductor, and then it is inserted into the flat copper tube.

[0016] It has the following beneficial effects: The resin tape serves as a buffer layer between the outer surface of the insulated wire core and the inner surface of the flat copper tube. The low-density resin tape can deform prior to the relatively hard integrally formed insulated wire core when the flat copper tube is drawn and reduced in diameter to squeeze the internal space, thereby filling the space between the outer contour surface of the insulated wire core and the inner surface of the flat copper tube. This ensures that the insulated wire core is not damaged by extrusion deformation and also enables close contact between the insulated wire core and the flat copper tube, forming an integral whole.

[0017] Further, in step three, the gap between the inner cavity of the flat copper tube and the insulated wire core is not less than 0.2 mm. The wall thickness of the flat copper tube is not less than 0.05 mm and not greater than 0.25 mm, and the thickness fluctuation is ±0.005 mm.

[0018] It has the following beneficial effects: The flat copper tube can be a preformed seamless flat copper tube, or the longitudinal seam of the copper tube can be welded while wrapping the insulated wire core with copper tape on the production line to form a longitudinally seam-welded flat copper tube. The length of the flat copper tube obtained by on-site longitudinal seam welding is not limited by the increasing penetration difficulty with the increase in length, and longer shielded semi-finished products can be made. The flat copper tube has the advantages of seamless, non-overlapping, and excellent continuity, which can greatly improve the transmission bandwidth of the cable.

[0019] Further, in step four, the outer diameter fluctuation in the width direction of the flat copper tube after drawing and sizing through the flat-hole die is ±0.01 mm.

[0020] It has the following beneficial effects: The small outer diameter fluctuation in the width direction of the flat copper tube results in extremely low reflection, reduced loss, and reduced signal distortion of the basic transmission unit, improving the transmission bandwidth of the cable.

[0021] Further, in step five, a concentric active tape-releasing constant-tension wrapping machine is used for the first winding buffer tape process and the second winding buffer tape process. During the winding process, the insulated wire core does not rotate, and the buffer tape rotates actively to wrap it. The shielding rate of the buffer tape on the surface of the insulated wire core should be not less than 90% and not greater than 100%, and the outer diameter fluctuation of the semi-finished product after winding the buffer tape is ±0.06 mm. The buffer tape is a semi-conductive foamed PP tape added with carbon black powder. The thickness of the buffer tape is 0.1 mm - 0.3 mm, the bandwidth is 3 mm - 7 mm, the surface resistivity of the semi-conductive foamed PP tape is less than 1500 Ω, the volume resistivity is less than 100 kΩ·cm, and the foaming degree is 50% to 70%.

[0022] It has the following beneficial effects: Based on the principle of a flat surface and minimal gaps after wrapping with the buffer tape, the buffer tape is tightly wrapped on the surface of the flat copper tube, capable of forming good buffer protection.

[0023] Further, in step five, dry cotton yarn is filled.

[0024] It has the following beneficial effects: The filled cotton yarn makes the positions of the basic transmission units relatively fixed, and it will not easily displace and cause frictional collision damage, so that the outer peripheral circular contour after cabling is more round.

[0025] Further, in step five, the tubular braiding process is to evenly braid and sleeve the tinned alloy wire on the outer surface of the semi-finished product, and the braiding density is not less than 80%; The tinned alloy wire is a tinned copper-clad aluminum-magnesium alloy wire.

[0026] It has the following beneficial effects: The tension of the wire during winding and unwinding during braiding, and the tension of the braiding wire should be as small as possible, so as to reduce the physical damage to the basic transmission unit, and then improve the transmission bandwidth of the cable.

[0027] Further, in the sheath forming process, the sheath is obtained by the tubular extrusion process, and the material of the sheath is one of polyvinyl chloride (PVC), low-smoke and halogen-free polyolefin (LSZH), and cross-linked polyolefin (XLZH).

[0028] It has the following beneficial effects: The sheath is obtained by the tubular extrusion process, which reduces the extrusion of the sheath on the cabled semi-finished product, reduces the damage to the basic transmission unit during the sheath process, and then improves the transmission bandwidth of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] By referring to the accompanying drawings and reading the following detailed description, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become easy to understand. In the drawings, several embodiments of the present invention are shown in an exemplary rather than restrictive manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein: Figure 1 is a flow block diagram of the present invention; Figure 2 is a schematic diagram of the injection molding of the insulated wire core; Figure 3 is a schematic diagram of the structure of the first insulated wire core; Figure 4 is a schematic diagram of the structure of the second insulated wire core; Figure 5 is a schematic diagram of the structure of the third insulated wire core; Figure 6 is a schematic diagram of the structure of the fourth insulated wire core; Figure 7 is a schematic diagram of the structure of the insulated wire core before shielding and shaping; Figure 8 is a schematic diagram of the structure of the insulated wire core during shielding and shaping; Figure 9Schematic diagram of the structure after shaping the insulation core shielding; Figure 10 Cross-sectional view of the cable; Figure 11 is Figure 10 Enlarged view of part A in

[0030] Explanation of reference numerals: 1. Inner conductor; 2. Insulation layer; 3. Insulation compensation layer; 4. Shielding layer; 5. Gap; 6. Flat hole die; 7. Semi-finished product; 8. First buffer layer; 9. Filling layer; 10. Second buffer layer; 11. Braided layer; 12. Protective layer; 13. First injection port; 14. Second injection port; 15. Third injection port; 16. Fourth injection port; 17. Injection mold; 18. Injection mold cavity. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0032] The following specifically introduces various non-limiting implementation manners of the present invention. The number of any element in the drawings is for illustration rather than limitation, and any naming is only for distinction and does not have any limiting meaning. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0033] As Figure 1 shown, a production method of a parallel unit high-speed parallel transmission symmetrical cable sequentially passes through the inner conductor 1 polishing process, injection molding process, insulation compensation winding process, shielding pipe threading process, shielding shaping process, first buffer winding process, filling process, second buffer winding process, braiding process, and sheath forming process to prepare a parallel unit high-speed parallel transmission symmetrical cable.

[0034] In this embodiment, the inner conductor 1 polishing process: First, the surface of the silver-plated copper wire is polished using a high-precision diamond wire drawing die, so that the surface of the silver-plated copper wire reaches a mirror effect. Under a 200-fold microscope, there are no any protrusions and indentations, no any impurities, the silver layer is continuous without pinholes, copper leakage, etc., the surface roughness (Sq) is not greater than 0.2 um, and the silver layer thickness is not less than 1 um. Silver-plated copper wires of different specifications are selected for different specifications of cables, and the outer diameter fluctuation of the silver-plated copper wire should be controlled within ±0.001 mm.

[0035] The main functions of the inner conductor 1 polishing are as follows: Reducing contact resistance: By removing impurities such as the oxide layer, dirt, and burrs on the surface of the inner conductor 1, the surface of the inner conductor 1 becomes smoother and flatter, enabling better contact with other components during connection, increasing the contact area, thus reducing the contact resistance. This results in less signal loss, facilitating the achievement of higher transmission bandwidths. This helps reduce power loss at the connection, improve the conduction efficiency, and avoid excessive heat generation due to excessive contact resistance, which could pose a safety hazard.

[0036] Improving appearance quality: Giving the surface of the inner conductor 1 good gloss and smoothness, enhancing the overall aesthetic appearance of the inner conductor 1. In some application scenarios with high appearance requirements, such as high-end electronic devices and precision instruments, the polished wire can meet the refined requirements of the product.

[0037] Enhancing corrosion resistance: After removing the surface impurities of the inner conductor 1, the protective coating on the surface of the inner conductor 1 can adhere better, forming a more uniform and dense protective film, thus effectively isolating corrosive media such as air and moisture, improving the corrosion resistance of the inner conductor 1, and extending its service life.

[0038] Reducing the influence of skin effect: Although the influence of polishing on the skin effect is relatively small, a smooth surface can make the current distribution on the surface of the inner conductor 1 more uniform, which to some extent helps reduce the current concentration phenomenon caused by the skin effect, making the wire perform more stably when transmitting high-frequency currents.

[0039] Using a silver-plated copper wire with a mirror effect after polishing as the inner conductor 1 can ensure that in the case of high frequencies, when the current flows through the silver layer on the surface of the silver-plated copper wire due to the skin effect, because the resistivity of silver is the lowest and the surface roughness is low, the effective resistance is relatively low, resulting in less signal loss, facilitating the achievement of higher transmission bandwidths.

[0040] Among them, the skin effect refers to the phenomenon that when an alternating current passes through the inner conductor 1, the current will concentrate in the area near the surface of the inner conductor 1, while the current density inside the inner conductor 1 is relatively small. The alternating current will generate an alternating magnetic field in the inner conductor 1. According to Lenz's law, an induced electromotive force and induced current will be generated inside the inner conductor 1. The directions of these induced currents are opposite to the direction of the original current inside the cross-section of the inner conductor 1 and thus cancel each other out. At the surface of the inner conductor 1, due to the existence of the conductor boundary, they cannot be completely cancelled, resulting in a more concentrated current distribution on the surface of the inner conductor 1.

[0041] In this embodiment, the injection molding process: In this embodiment, due to the small cross-sectional area of the insulation injection molding of the parallel unit high-speed parallel transmission symmetrical cable, the cross-section is usually 1 mm thick and 2 mm wide, and the length requirement is relatively long, up to 10 meters at most and about 1 meter at least, resulting in an injection molding aspect ratio as high as 1:10000, and the injection molding difficulty is very high. Due to the high aspect ratio and the long flow distance of the plastic, a cavity segmented continuous injection molding process is carried out.

[0042] As Figure 2 shown, first perform injection molding at the first injection port 13, control the amount of plastic injected, so that the plastic fills the first injection port 13 and the second injection port 14, as Figure 2 shown in section a in.

[0043] While maintaining pressure at the first injection port 13 but not injecting plastic, start injecting the same plastic material at the two second injection ports 14, so that the material at the second injection ports 14 flows into the injection mold cavity 18 from the second injection ports 14, and at the same time, it is integrated with the plastic flowing from the first injection port 13 at the second injection ports 14 to form an integral body.

[0044] Repeat the above steps to complete the injection molding work at the third injection port 15 and the fourth injection port 16.

[0045] Before the plastic cools and solidifies, apply a tensile force to the inner conductors 1 exposed at both ends of the injection mold 17, so that the two inner conductors 1 remain straight and parallel. Then cool the injection mold 17 to make the plastic solidify.

[0046] After the plastic solidifies, open the mold and take out the wire core, and trim the residual plastic at the injection port. Then a high-precision insulated wire core (as Figure 3 shown) is obtained. Compared with the traditional continuous extrusion process, the dimensional error and eccentricity error are reduced by more than 10 times.

[0047] By expanding the above segmented continuous injection molding method, an insulated injection molding product of a parallel unit high-speed parallel transmission symmetrical cable with a length of up to hundreds of meters can be obtained. Multiple insulated wire cores can also be injection molded simultaneously to obtain insulated products of multiple parallel unit high-speed parallel transmission symmetrical cables.

[0048] In other embodiments, a double-conductor integrated vertical PTFE extrusion cable insulation process (insulation density is about 1.6 g / cm³) is adopted, and the insulation cross-section is microporous (as Figure 4 shown), the insulation concentricity is not less than 94%, the outer diameter fluctuation in the insulation width direction should meet ±0.02 mm, and the spacing fluctuation between the two inner conductors 1 should meet ±0.01 mm.

[0049] In other embodiments, a double-conductor integrated vertical fluororesin lotus root-shaped cable insulation extrusion process (average insulation density is about 1.0 g / cm³) is adopted, and the insulation cross-section is similar to the shape of a lotus root cross-section (as Figure 5As shown in the figure, the insulation concentricity is not less than 94%, the outer diameter fluctuation in the width direction of the insulation should meet ±0.02 mm, and the spacing fluctuation between the two inner conductors 1 should meet ±0.01 mm.

[0050] In other embodiments, a double-conductor integrated vertical polyethylene lotus root-shaped cable insulation extrusion process (with an average insulation density of about 0.4 g / cm³) is adopted. The insulation concentricity is not less than 94%, and the insulation cross-section is similar to the shape of a lotus root cross-section (as Figure 5 shown in the figure), the outer diameter fluctuation in the width direction of the insulation should meet ±0.02 mm, and the spacing fluctuation between the two inner conductors 1 should meet ±0.01 mm.

[0051] In other embodiments, a PTFE microporous tape winding insulation forming process (with an insulation density of about 1.0 g / cm³) is adopted. The insulation cross-section is microporous (as Figure 4 shown in the figure), the insulation concentricity is not less than 96%, the outer diameter fluctuation in the width direction of the insulation should meet ±0.02 mm, and the spacing fluctuation between the two inner conductors 1 should meet ±0.01 mm.

[0052] In other embodiments, a continuous injection molding integrated forming process is adopted. The injection molding materials can be ultra-high purity polyethylene, ultra-high purity fluororesin, or ultra-high purity polypropylene. The insulation cross-section is gear-shaped (as Figure 6 shown in the figure), the insulation concentricity is not less than 97%, the outer diameter fluctuation in the outer width direction of the insulation should meet ±0.01 mm, and the spacing fluctuation between the two inner conductors 1 should meet ±0.01 mm.

[0053] One of low-density microporous PTFE, low-density lotus root-shaped fluororesin, and low-density lotus root-shaped polyethylene is used as the insulation dielectric material, and is injection molded on the surface of the double inner conductors 1 through a cavity segmented continuous injection molding process to form the insulation layer 2, thereby obtaining the insulated wire core, which can ensure that the dielectric loss is reduced to the lowest level to achieve a higher transmission bandwidth.

[0054] In this embodiment, the insulation compensation winding process: A low-density resin tape is used, preferably a low-density microporous PTFE tape, and is evenly wound around the insulated wire core after integrated forming as the insulation compensation layer 3. Since a flat copper tube needs to be sleeved on the outer surface of the insulated wire core as the shielding layer 4, the purpose of using the resin tape to evenly wind around the insulated wire core is: as a buffer layer between the outer surface of the insulated wire core and the inner surface of the flat copper tube.

[0055] The low-density resin tape can deform prior to the relatively hard integrally formed insulated wire core when the flat copper tube is drawn and reduced in diameter to squeeze the internal space, thereby filling the space between the outer surface of the insulated wire core and the inner surface of the flat copper tube, so that the insulated wire core will not be damaged by extrusion deformation, and also enabling the insulated wire core and the flat copper tube to be in close contact to form a whole, thereby obtaining the semi-finished product 7.

[0056] The density of the low-density resin tape is lower than that of the insulated wire core to be wrapped. The wrapping shielding rate should be not less than 90% and not more than 100%. After wrapping, the surface should be flat and the gap should be minimized. Concentric wrapping is adopted, and the outer diameter fluctuation of the semi-finished product 7 after wrapping compensation should meet ±0.04 mm.

[0057] In other embodiments, if the surface of the insulated wire core after integral molding is soft enough, that is, there are enough voids inside its surface, the insulation compensation wrapping process is not required, and the flat copper tube can be directly sleeved on the insulated wire core.

[0058] In this embodiment, the shielding tube threading process: The shielding tube threading process refers to threading the insulated wire core into the inner cavity of a flat copper tube whose outer contour size is slightly larger than that of the insulated wire core. At this time, there is a gap 5 between the inner cavity of the flat copper tube and the insulated wire core. Generally, the gap 5 between the inner cavity of the flat copper tube and the insulated wire core is not less than 0.2 mm, and auxiliary threading operation can be achieved for 30 meters. For threading a longer flat copper tube, the method of using a lead wire to assist can also be adopted to pull the insulated wire core into the inner cavity of the flat copper tube.

[0059] The outer contour of the flat copper tube is the same as that of the insulated wire core. The wall thickness of the flat copper tube is not less than 0.05 mm and not more than 0.25 mm, and the thickness fluctuation should meet ±0.005 mm.

[0060] The flat copper tube can be a preformed seamless flat copper tube, or the longitudinal seam of the flat copper tube can be welded while wrapping the insulated wire core with copper tape on the production line to form a longitudinally seam-welded flat copper tube. The length of the flat copper tube obtained by on-site longitudinal seam welding is not restricted by the increasing threading difficulty with the increase of length, and longer semi-finished products 7 can be made.

[0061] The flat copper tube has the advantages of seamless, non-overlapping, and excellent continuity, which can greatly improve the transmission bandwidth of the cable.

[0062] In this embodiment, the shielding shaping process: As Figures 7 - 9 shown, the semi-finished product 7 with the insulated wire core already threaded is pulled out through the inner hole of a refined flat-hole die 6, so that the outer shape and size of the flat copper tube meet the design requirements, and the flat copper tube is closely attached to the insulated wire core inside it to form an integral body.

[0063] The flat copper tube drawn and shaped by the flat-hole die 6 has excellent outer dimension consistency. The outer diameter fluctuation in the width direction should meet ±0.01 mm, which makes the reflection of the transmission unit extremely low, the loss reduced, the signal distortion decreased, and the transmission bandwidth of the cable increased.

[0064] In this embodiment, the first buffer wrapping process: For the first buffer winding, a concentric active tape - paying constant - tension winding machine is used. During the winding process, the semi - finished product 7 does not rotate, and the buffer tape rotates actively to wrap around the surface of the flat copper tube as the first buffer layer 8. The tension during the buffer - tape winding process is set at 30% to 70% of the average breaking force of the buffer tape, so that the buffer tape can be tightly wrapped around the surface of the semi - finished product 7 to form good buffer protection. The shielding rate of the buffer tape on the surface of the semi - finished product 7 should be not less than 90% and not more than 100%, with the principle of a flat surface and the smallest gap after wrapping. The outer - diameter fluctuation of the semi - finished product 7 after wrapping the buffer tape should meet ±0.06 mm.

[0065] In this embodiment, the buffer tape is made of a semi - conductive foamed PP tape added with carbon - black powder for wrapping. The thickness of the buffer tape can be selected from 0.1 mm to 0.3 mm according to the outer - diameter size of different - specification cables, the bandwidth can be selected from 3 mm to 7 mm. The surface resistivity of the semi - conductive foamed PP tape is less than 1500 Ω, the volume resistivity is less than 100 kΩ·cm, and the foaming degree is 50% to 70%.

[0066] The filling process of this embodiment: In the filling process, an appropriate amount of dry cotton yarn is added onto the first buffer layer 8 as the filling layer 9, so that the basic transmission units will not easily displace and cause frictional collision damage, and the outer - peripheral circular profile after cabling will be more round.

[0067] In the filling process of other embodiments, a polypropylene rope can be added onto the first buffer layer 8 as the filling layer 9. The polypropylene rope has high mechanical strength, wear resistance, good chemical stability, is not easily affected by moisture, and has a light weight.

[0068] In the filling process of other embodiments, a glass - fiber rope can be added onto the first buffer layer 8 as the filling layer 9. The glass - fiber rope has excellent high - temperature resistance, high strength, and good insulation performance, does not burn, and can withstand a relatively high temperature without deformation.

[0069] In the filling process of other embodiments, an asbestos rope can be added onto the first buffer layer 8 as the filling layer 9. The asbestos rope has good high - temperature resistance, heat insulation, and insulation performance, strong chemical stability, and can effectively prevent the spread of heat and flame.

[0070] In the filling process of other embodiments, a foam plastic can be added onto the first buffer layer 8 as the filling layer 9. The foam plastic is light in weight and soft, has good buffer performance and insulation performance, can effectively reduce the weight and outer diameter of the cable, and can also play a certain role in sound insulation and heat insulation.

[0071] In the filling process of other embodiments, rubber can be added onto the first buffer layer 8 as the filling layer 9. Rubber has good elasticity, flexibility and corrosion resistance, can adapt to the bending and stretching of the cable in different environments, and has good insulation performance at the same time.

[0072] The selection of cable filling materials depends on factors such as the cable's usage environment, performance requirements, and cost. In practical applications, it is necessary to comprehensively consider according to specific situations and select appropriate filling materials to ensure the safe and reliable operation of the cable.

[0073] In this embodiment, the second buffer wrapping process: The second buffer wrapping is carried out using the exactly same process method as the first buffer wrapping. The buffer tape rotates actively to wrap around the surface of the filling layer 9 of the semi-finished product 7 as the second buffer layer 10. Among them, the second buffer wrapping process is completed synchronously with the filling process. Since the object to be wrapped in the second buffer wrapping has a larger outer diameter size than that in the first buffer wrapping, a semi-conductive foamed PP tape with a larger width and thickness than that in the first buffer wrapping should be selected for wrapping. The material properties of the semi-conductive foamed PP tape are the same as those of the material used in the first buffer wrapping.

[0074] In this embodiment, the braiding process: Braiding adopts the tubular braiding process method of traditional conventional cables. Low-cost tinned copper-clad aluminum-magnesium alloy wires are evenly braided around the outer surface of the semi-finished product 7 after the second buffer wrapping as the braided layer 11 of the cable. The braiding density is not less than 80%. The tension of winding and unwinding the wires during braiding, as well as the tension of the braiding wires, should be as small as possible to reduce the physical damage to the basic transmission unit and thus improve the transmission bandwidth of the cable.

[0075] In other embodiments, copper wires are braided on the outer surface of the semi-finished product 7. Copper wires have good electrical conductivity, thermal conductivity and ductility, can effectively shield electromagnetic interference, and at the same time have a certain mechanical strength to protect the inner core wires of the cable.

[0076] In other embodiments, steel wires are braided on the outer surface of the semi-finished product 7. Steel wires have high strength, can enhance the tensile performance of the cable and improve the mechanical protection ability of the cable.

[0077] In other embodiments, glass fibers are braided on the outer surface of the semi-finished product 7. Glass fibers have characteristics such as high temperature resistance, corrosion resistance and good insulation performance, can effectively protect the internal structure of the cable, and at the same time reduce the weight of the cable.

[0078] In other embodiments, synthetic fibers are braided on the outer surface of the semi-finished product 7. The synthetic fiber can be one of polyester fiber and nylon. Synthetic fibers have good wear resistance, flexibility and insulation, and can be used to make the braided layer 11 of the cable to play a role in protection and insulation.

[0079] In other embodiments, a layer of aluminum foil can be coated on the outer surface of the semi-finished product 7 before braiding to further compensate for the shielding density of the braiding, with the aluminum side of the aluminum foil facing outward. A conductor can also be added between the aluminum foil and the braided mesh as a ground wire for the later connection operation of the cable and the connector.

[0080] In this embodiment, the sheath forming process: The sheath is made of a traditional low-cost material such as polyvinyl chloride (PVC), low-smoke halogen-free polyolefin (LSZH), or cross-linked polyolefin (XLZH). The sheath is obtained by a tubular extrusion process, and the above-mentioned material is extruded onto the surface of the braided layer 11 as the protective layer 12, which can reduce the extrusion of the sheath on the semi-finished product 7 and reduce the damage to the basic transmission unit during the sheath forming process, thereby improving the transmission bandwidth of the cable.

[0081] Through the above steps, as Figure 10 , Figure 11 shown, an insulating layer 2, an insulation compensation layer 3, a shielding layer 4, a first buffer layer 8, a filling layer 9, a second buffer layer 10, a braided layer 11, and a protective layer 12 are sequentially formed on the surface of the inner conductor 1 from the inside to the outside.

[0082] The structure of the insulated wire core is 1 flat insulated wire, and there are two parallel inner conductors 1 inside the flat insulated wire. The two inner conductors 1 and the flat insulated wire are formed in one step to form an integral structure. A flat copper tube adapted to the outer contour of the flat insulated wire is sleeved outside the flat insulated wire, reducing the stress deformation, so that the electromagnetic field distribution between the two inner conductors 1 is uniform, improving the transmission signal quality and thus the transmission bandwidth; at the same time, the flat copper tube itself has shape plasticity, and is smooth and seamless continuous, approaching an ideal state, which is beneficial to improving the transmission bandwidth; and through the cavity segmented continuous injection molding process, the problem of the eccentricity of the inner conductor 1 caused by the downward flow of the insulating dielectric material is eliminated, and at the same time, the outer diameter fluctuation of the insulated wire core is reduced, so that the electromagnetic field distribution between the two inner conductors 1 is uniform, improving the signal transmission quality, and thus the transmission bandwidth can be improved.

Claims

1. A method for producing a parallel unit high-speed parallel transmission symmetrical cable, characterized in that: The following steps are involved: Step 1: polishing the surfaces of the two inner conductors; Step 2: Using a cavity segmented continuous injection molding process, a layer of insulating dielectric material is simultaneously injected on the surfaces of the two inner conductors to obtain an insulated wire core; Step 3: Insert the insulated wire core into the flat copper tube; Step 4: Pull the flat copper tube into which the insulating wire core has been inserted through the inner hole of a flat hole mold, so that the flat copper tube and the insulating wire core inside it are closely fitted to form a whole, thereby obtaining a semi-finished product; Step 5: The first buffer tape winding process, the filling process, the second buffer tape winding process, the tubular braiding process and the sheath molding process are sequentially performed on the surface of the semi-finished product to obtain a parallel unit high-speed parallel transmission symmetrical cable.

2. The method for producing a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: The two inner conductors are surface-polished using a diamond drawing die, and the surface roughness (Sq) of the inner conductors is no greater than 0.2 um; The inner conductor is a silver-plated copper wire, wherein the thickness of the plated silver layer is not less than 1 um, and the outer diameter fluctuation of the silver-plated copper wire is ±0.001 mm.

3. The method for producing a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: The insulating medium material is one of low-density microporous PTFE, plastic resin with a lotus-shaped cross section, low-density foamed plastic resin, and plastic resin with an external serrated cross section.

4. The method for producing a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: Before the insulating wire core is inserted into the flat copper tube, a low-density resin tape is used to evenly wrap the surface of the insulating wire core, and then the insulating wire core is inserted into the flat copper tube.

5. The method for producing a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: In step 3, the gap between the inner cavity of the flat copper tube and the insulating core is not less than 0.2 mm; The wall thickness of the flat copper tube is not less than 0.05 mm and not more than 0.25 mm, and the thickness fluctuation is ±0.005 mm.

6. The method for producing a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: In step 4, the outer diameter fluctuation in the width direction of the flat copper tube after drawing and shaping by the flat hole die is ±0.01mm.

7. The method for producing a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: In step 5, a concentric active unwinding constant tension wrapping machine is used to perform the first and second buffer tape wrapping processes. During the wrapping process, the insulated wire core does not rotate, but is actively wrapped by the buffer tape. The shielding rate of the buffer tape on the surface of the insulated wire core should be no less than 90% and no more than 100%, and the outer diameter fluctuation of the semi-finished product after the buffer tape is wound is ±0.06mm; The buffer tape is a semi-conductive foamed PP tape added with carbon black powder, the thickness of the buffer tape is 0.1mm-0.3mm, the width of the tape is 3mm-7mm, the surface resistivity of the semi-conductive foamed PP tape is less than 1500Ω, the volume resistivity is less than 100kΩ·cm, and the foaming degree is 50% to 70%.

8. The method for producing a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: In step five, the filling is dry cotton yarn.

9. The method for producing a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: In step 5, the tubular braiding process is to evenly braid the tinned alloy wire on the outer surface of the semi-finished product, wherein the braiding density is not less than 80%; The tinned alloy wire is a tinned copper-clad aluminum-magnesium alloy wire.

10. The method for producing a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: In the sheath forming process, the sheath is obtained by a tubular extrusion process, and the material of the sheath is one of polyvinyl chloride (PVC), low-smoke zero-halogen polyolefin (LSZH), and cross-linked polyolefin (XLZH).

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