A production method of a high-speed parallel transmission symmetric cable with parallel units

Abstract

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, comprising the following steps: polishing the surfaces of two inner conductors; adopting a cavity segmented continuous injection molding process to simultaneously inject an insulating dielectric material on the surfaces of the two inner conductors to obtain insulated wire cores; threading the insulated wire cores into the interior of flat copper tubes; pulling the flat copper tubes out through the inner holes of a flat hole die so that the flat copper tubes are closely attached to the insulated wire cores to form an integral body, obtaining semi-finished products; successively performing a first winding buffer tape process, a filling process, a second winding buffer tape process, a tubular braiding process, and a sheath forming process on the surfaces of the semi-finished products to obtain a high-speed parallel transmission symmetrical cable for parallel units. A flat copper tube that fits is sleeved outside the flat insulated wire, reducing force-induced deformation, thereby making the electromagnetic field distribution between the two inner conductors uniform, improving the transmission signal quality, and thus increasing the transmission bandwidth.

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 with 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 uses 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 ultimately leading to uneven electromagnetic field distribution between the two conductors, a decline in the quality of the transmitted signal, and an inability to increase the transmission bandwidth.

[0005] In the existing process technology, the "wrapping" method of the shielded 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 shielded 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 shielded 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 insulating wires in the existing parallel wire pairs 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 air resistance when the wire core moves horizontally in the air, and the complex fluid resistance when the wire core moves horizontally in the cooling water. Eventually, the outer diameter of the insulated wire core fluctuates greatly. For example, the outer diameter of a wire core with an outer diameter of 1.7 mm fluctuates in the range of ±0.05 mm. There is also a problem of conductor eccentricity caused by the downward flow of the uncooled and solidified insulating plastic.

[0007] These seemingly minor and negligible effects, 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 symmetrical 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:

[0010] A production method for a parallel unit high-speed parallel transmission symmetrical cable includes the following steps:

[0011] Step 1: Polish the surfaces of two inner conductors.

[0012] 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.

[0013] Step 3: Insert the insulated wire core into the inside of a flat copper tube.

[0014] Step 4: Pull out the flat copper tube into which the insulated wire core has been 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 a semi-finished product is obtained.

[0015] 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 symmetrical cable.

[0016] It has the following beneficial effects: The structure of the insulated wire core is a single flat insulated wire, which contains two parallel inner conductors inside. The two inner conductors and the flat insulated wire are formed integrally in one step to form a whole structure. A flat copper tube that fits 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 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 continuously, 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 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 is uniform, improving the signal transmission quality and further increasing the transmission bandwidth.

[0017] 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;

[0018] 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.

[0019] 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 frequency, when the current flows on the silver layer on the surface of the silver-plated copper due to the skin effect, due to the lowest resistivity of silver and low surface roughness, the effective resistance is relatively low, and the loss of the signal is small, so as to achieve a higher transmission bandwidth.

[0020] 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.

[0021] 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.

[0022] Further, before the insulated wire core is inserted into the flat copper tube, a low-density resin tape is used to wind evenly on the surface of the insulated wire core, and then it is inserted into the flat copper tube.

[0023] 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, thus filling the space between the outer contour surface of the insulated wire core and the inner surface of the flat copper tube, preventing the insulated wire core from being squeezed and deformed, and enabling the insulated wire core and the flat copper tube to be in close contact to form a whole.

[0024] 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;

[0025] 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.

[0026] 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.

[0027] Further, in step four, the outer diameter fluctuation in the width direction of the flat copper tube after being drawn and shaped by the flat hole die is ±0.01 mm.

[0028] 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.

[0029] Further, in step five, a concentric active tape feeding 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;

[0030] The shielding rate of the buffer tape on the surface of the insulated wire core should be not less than 90% and not more than 100%, and the outer diameter fluctuation of the semi-finished product after winding the buffer tape is ±0.06 mm;

[0031] 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%.

[0032] It has the following beneficial effects: After the buffer strip is wrapped, based on the principle of a flat surface and the smallest gap, the buffer strip is tightly wrapped on the surface of the flat copper tube, and good buffer protection can be formed.

[0033] Further, in step five, dry cotton yarn is filled.

[0034] It has the following beneficial effects: The filled cotton yarn makes the positions of the basic transmission units relatively fixed, and they will not easily shift and cause frictional collision damage, so that the outer peripheral circular contour after cabling is more round.

[0035] 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%;

[0036] The tinned alloy wire is a tinned copper-clad aluminum-magnesium alloy wire.

[0037] It has the following beneficial effects: The tension of the wire during pay-off and take-up 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.

[0038] Further, 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 halogen-free polyolefin (LSZH), and cross-linked polyolefin (XLZH).

[0039] It has the following beneficial effects: The sheath is obtained by a 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

[0040] 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 easily understood. 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, where:

[0041] Figure 1 is a flow block diagram of the present invention;

[0042] Figure 2 is a schematic diagram of insulating wire core injection molding;

[0043] Figure 3 is a schematic diagram of the structure of the first insulating wire core;

[0044] Figure 4 is a schematic diagram of the structure of the second insulating wire core;

[0045] Figure 5It is a schematic structural diagram of the third insulating core;

[0046] Figure 6 It is a schematic structural diagram of the fourth insulating core;

[0047] Figure 7 It is a schematic structural diagram before the shielding shaping of the insulating core;

[0048] Figure 8 It is a schematic structural diagram during the shielding shaping of the insulating core;

[0049] Figure 9 It is a schematic structural diagram after the shielding shaping of the insulating core;

[0050] Figure 10 It is a cross-sectional view of the cable;

[0051] Figure 11 It is Figure 10 An enlarged view of area A in

[0052] Description of the reference numerals:

[0053] 1. Inner conductor; 2. Insulating 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. Specific embodiments

[0054] 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 shall fall within the protection scope of the present invention.

[0055] Next, various non-limiting embodiments of the present invention will be specifically introduced. The quantity of any element in the drawings is for illustration rather than limitation, and any naming is only for distinction without any limiting meaning. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0056] Such as Figure 1As shown in the figure, a production method of a parallel unit high-speed parallel transmission symmetrical cable is provided. The parallel unit high-speed parallel transmission symmetrical cable is prepared by successively passing through an inner conductor 1 polishing process, an injection molding process, an insulation compensation winding process, a shielding pipe threading process, a shielding shaping process, a first buffer winding process, a filling process, a second buffer winding process, a braiding process, and a sheath shaping process.

[0057] In this embodiment, the inner conductor 1 polishing process:

[0058] First, the surface of the silver-plated copper wire is polished with a high-precision diamond wire drawing die to make the surface of the silver-plated copper wire reach a mirror effect. Under a 200-fold microscope, there are no any protrusions, depressions, or 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 cables, and the outer diameter fluctuation of the silver-plated copper wire should be controlled within ±0.001 mm.

[0059] The inner conductor 1 polishing mainly has the following functions:

[0060] Reduce 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, thereby reducing the contact resistance. This results in less signal loss, facilitating the achievement of a higher transmission bandwidth. This helps to reduce the power loss at the connection, improve the conductivity efficiency, and avoid excessive heat generation due to too large contact resistance, which may cause safety hazards.

[0061] Improve appearance quality: Make the surface of the inner conductor 1 have good gloss and smoothness, enhancing the overall aesthetics 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.

[0062] Improve corrosion resistance: After removing the impurities on the surface of the inner conductor 1, the protective coating on the surface of the inner conductor 1 can better adhere, forming a more uniform and dense protective film, thereby effectively isolating corrosive media such as air and moisture, improving the corrosion resistance of the inner conductor 1, and extending its service life.

[0063] Reduce the influence of skin effect: Although the polishing has a relatively small impact on the skin effect, the smooth surface can make the current distribution on the surface of the inner conductor 1 more uniform, which helps to reduce the current concentration phenomenon caused by the skin effect to a certain extent, making the wire more stable in performance when transmitting high-frequency current.

[0064] Using a silver-plated copper wire with a mirror finish after polishing as the inner conductor 1 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 wire due to the skin effect, since the resistivity of silver is the lowest and the surface roughness is low, the effective resistance is relatively low, and the signal loss is small, so as to achieve a higher transmission bandwidth.

[0065] 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, and 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 an 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. Due to the existence of the conductor boundary on the surface of the inner conductor 1, they cannot be completely cancelled, resulting in a more concentrated distribution of current on the surface of the inner conductor 1.

[0066] In this embodiment, the injection molding process:

[0067] In this embodiment, due to the small cross-sectional area of the insulation injection molding of the high-speed parallel transmission symmetrical cable of the parallel unit, usually the cross-section is 1 mm thick, 2 mm wide, and the length requirement is relatively long, up to 10 meters at the longest and about 1 meter at the shortest, resulting in an injection molding length-to-diameter ratio as high as 1:10000, and the injection molding difficulty is very high. Due to the high length-to-diameter ratio and the long flow distance of the plastic, a cavity segmented continuous injection molding process is carried out.

[0068] 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.

[0069] 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 merges with the plastic flowing from the first injection port 13 at the second injection ports 14 to form a whole.

[0070] Repeat the above steps to complete the injection molding work at the third injection port 15 and the fourth injection port 16.

[0071] 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 so that the plastic solidifies.

[0072] 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 is obtained (as Figure 3As shown, compared with the traditional continuous extrusion process, the dimensional error and eccentricity error are reduced by more than 10 times.

[0073] By expanding the above segmented continuous injection molding method, parallel unit high-speed parallel transmission symmetrical cable insulation injection molded products with a length of more than one hundred meters can be obtained. Multiple insulated cores can also be injection molded simultaneously to obtain insulated products of multiple parallel unit high-speed parallel transmission symmetrical cables.

[0074] In other embodiments, a double-conductor integrated vertical PTFE extrusion process for cable insulation (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.

[0075] In other embodiments, a double-conductor integrated vertical fluororesin lotus root-shaped cable insulation extrusion process (insulation average density is about 1.0 g / cm³) is adopted, and the insulation cross-section is similar to the lotus root cross-section shape (as Figure 5 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.

[0076] In other embodiments, a double-conductor integrated vertical polyethylene lotus root-shaped cable insulation extrusion process (insulation average density is about 0.4 g / cm³) is adopted, the insulation concentricity is not less than 94%, and the insulation cross-section is similar to the lotus root cross-section shape (as Figure 5 shown), 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.

[0077] In other embodiments, a PTFE microporous tape winding insulation forming process (insulation density is about 1.0 g / cm³) is adopted, and the insulation cross-section is microporous (as Figure 4 shown), the insulation concentricity is not less than 96%, 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.

[0078] 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, and ultra-high purity polypropylene. The insulation cross-section is gear-shaped (as Figure 6 shown), the insulation concentricity is not less than 97%, the outer diameter fluctuation in the insulation outer width direction should meet ±0.01 mm, and the spacing fluctuation between the two inner conductors 1 should meet ±0.01 mm.

[0079] One of low-density microporous PTFE, low-density lotus-shaped fluororesin, and low-density lotus-shaped polyethylene is used as the insulating dielectric material, and is injection-molded onto the surface of the double inner conductor 1 through a cavity segmented continuous injection molding process to form the insulating layer 2, thereby obtaining an insulated wire core, which can ensure that the dielectric loss is minimized to achieve a higher transmission bandwidth.

[0080] In this embodiment, the insulating compensation winding process:

[0081] A low-density resin tape, preferably a low-density microporous PTFE tape, is evenly wound around the integrally formed insulated wire core to form the insulating 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: to serve as a buffer layer between the outer surface of the insulated wire core and the inner surface of the flat copper tube.

[0082] 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 close contact between the insulated wire core and the flat copper tube to form a whole, thereby obtaining the semi-finished product 7.

[0083] The density of the low-density resin tape is lower than that of the insulated wire core to be wound, and the winding shielding rate should be not less than 90% and not more than 100%, with the principle of a flat surface and the smallest gap after wrapping. Concentric winding is adopted, and the outer diameter fluctuation of the semi-finished product 7 after winding compensation should meet ±0.04 mm.

[0084] In other embodiments, if the surface of the integrally formed insulated wire core is soft enough by itself, that is, there are enough voids inside its surface, the insulating compensation winding process is not required, and the flat copper tube can be directly sleeved on the insulated wire core.

[0085] In this embodiment, the shielding tube-passing process:

[0086] The shielding tube-passing process refers to passing the insulated wire core into the inner cavity of a flat copper tube slightly larger than its outer contour size. 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 penetration operation can be achieved without for 30 meters. For passing through 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.

[0087] 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.

[0088] 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 the insulating wire core is wrapped with copper tape on the production line to form a longitudinally 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 of length, and longer semi-finished products 7 can be made.

[0089] The flat copper tube has the advantages of seamless, non-overlapping, and excellent continuity, which can greatly improve the transmission bandwidth of the cable.

[0090] In this embodiment, the shielding shaping process:

[0091] As Figures 7 - 9 shown, the semi-finished product 7 with the insulating wire core inserted is pulled out through the inner hole of a refined flat hole die 6, so that the shape and size of the flat copper tube meet the design requirements, and the flat copper tube is closely attached to the insulating wire core inside it to form an integral body.

[0092] The flat copper tube after drawing and shaping with the flat hole die 6 has excellent consistency in shape and size. The outer diameter fluctuation in the width direction should meet ±0.01 mm, resulting in extremely low reflection, reduced loss, and reduced signal distortion of the transmission unit, and improving the transmission bandwidth of the cable.

[0093] In this embodiment, the first buffer wrapping process:

[0094] The first buffer wrapping is carried out by a concentric active tape feeding constant tension wrapping machine. During the wrapping process, the semi-finished product 7 does not rotate, and the buffer tape actively rotates and wraps on the surface of the flat copper tube as the first buffer layer 8. The tension during the buffer tape wrapping process is set according to 30% to 70% of the average breaking force of the buffer tape, so that the buffer tape can be closely wrapped on 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.

[0095] In this embodiment, the buffer tape is wrapped with a semi-conductive foamed PP tape added with carbon black powder. 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 specifications of the cable, 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%.

[0096] The filling process of this embodiment:

[0097] 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 be easily displaced to cause frictional collision damage, and the outer circumferential contour after cabling will be more round.

[0098] 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 and wear resistance, good chemical stability, is not easily affected by moisture, and has a light weight.

[0099] 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 performance, high strength and good insulation performance, does not burn, and can withstand high temperatures without deformation.

[0100] 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 flames.

[0101] 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 buffering 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.

[0102] In the filling process of other embodiments, a rubber can be added onto the first buffer layer 8 as the filling layer 9. The rubber has good elasticity, flexibility and corrosion resistance, can adapt to the bending and stretching of the cable under different environments, and has good insulation performance.

[0103] The selection of the cable filling material 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.

[0104] In this embodiment, the second buffer wrapping process:

[0105] The second buffer wrapping is carried out by using exactly the 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, and the material properties of the semi-conductive foamed PP tape are the same as those of the material used in the first buffer wrapping.

[0106] In this embodiment, the braiding process:

[0107] The braiding uses the tubular braiding process method of traditional conventional cables, and the low-cost tin-plated copper-clad aluminum-magnesium alloy wire is evenly braided and sleeved on the outer surface of the semi-finished product 7 completed by the second buffer wrapping as the braided layer 11 of the cable. The braiding density is not less than 80%. The tension of the wire during pay-off and take-up and the tension of the braiding wire 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.

[0108] In other embodiments, copper wire is used to braid on the outer surface of the semi-finished product 7. Copper wire has good electrical conductivity, thermal conductivity and ductility, can effectively shield electromagnetic interference, and at the same time has a certain mechanical strength to protect the inner core wire of the cable.

[0109] In other embodiments, steel wire is used to braid on the outer surface of the semi-finished product 7. Steel wire has high strength, can enhance the tensile performance of the cable and improve the mechanical protection ability of the cable.

[0110] In other embodiments, glass fiber is used to braid on the outer surface of the semi-finished product 7. Glass fiber has the characteristics of 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.

[0111] In other embodiments, synthetic fiber is used to braid on the outer surface of the semi-finished product 7. The synthetic fiber can be one of polyester fiber and nylon. The synthetic fiber has 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.

[0112] 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.

[0113] In this embodiment, the sheath forming process:

[0114] The sheath uses a traditional low-cost material such as one of polyvinyl chloride (PVC), low-smoke and halogen-free polyolefin (LSZH), and cross-linked polyolefin (XLZH). The sheath is obtained by a tubular extrusion process, and the above-mentioned one 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, and thus improve the transmission bandwidth of the cable.

[0115] Through the above steps, such as Figure 10 , Figure 11As shown in the figure, an insulating layer 2, an insulating 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.

[0116] The structure of the insulated wire core is a flat insulated wire. There are two parallel inner conductors 1 inside the flat insulated wire. The two inner conductors 1 and the flat insulated wire are integrally 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 force deformation, so that the electromagnetic field distribution between the two inner conductors 1 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, and is smooth, 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 eccentricity of the inner conductor 1 caused by the downward flow of the insulating dielectric material is eliminated, and at the same time, the fluctuation of the outer diameter 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 increased.

Claims

1. A production method of a high-speed parallel transmission symmetric cable with parallel units, characterized in that, It 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, thereby obtaining an insulated wire core; Step 3: Insert the insulated wire core into the interior of a flat copper tube; Step 4: Pull out the flat copper tube with the inserted insulated wire core 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, obtaining a semi-finished product; Step 5: Sequentially perform the first buffer tape winding process, filling process, second buffer tape winding process, tubular braiding process, and sheath forming process on the surface of the semi-finished product, thereby obtaining a parallel unit high-speed parallel transmission symmetrical cable.

2. The production method of a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that, The surfaces of the two inner conductors are polished using a diamond wire drawing die, and the surface roughness (Sq) of the inner conductor is not greater than 0.2 um; The inner conductor is a silver-plated copper wire, where the thickness of the silver plating layer is not less than 1 um, and the outer diameter fluctuation of the silver-plated copper wire is ±0.001 mm.

3. The production method of a high-speed parallel transmission symmetric cable with parallel units according to claim 1, characterized in that, 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.

4. The production method of a high-speed parallel transmission symmetric cable with parallel units according to claim 1, characterized in that, Before inserting the insulated wire core into the interior of the flat copper tube, use a low-density resin tape to evenly wind around the surface of the insulated wire core, and then insert it into the interior of the flat copper tube.

5. The production method of 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 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.

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

7. The production method of a parallel unit high-speed parallel transmission symmetric cable according to claim 1, characterized in that, In Step 5, a concentric active tape feeding constant tension wrapping machine is used for the first buffer tape winding process and the second buffer tape winding process. During the winding process, the insulated wire core does not rotate, and the buffer tape rotates actively for wrapping; 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 tape width 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%.

8. The production method of a parallel unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that, In Step 5, dry cotton yarn is filled.

9. The production method of 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 and sleeve a tinned alloy wire on the outer surface of the semi-finished product, where the braiding density is not less than 80%; The tinned alloy wire is a tinned copper-clad aluminum-magnesium alloy wire.

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

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