Shanghai Daoqin Plastics Co., Ltd.

in cable production process in, usually using/adopting insulation or chemical foaming process. 20世纪80 year 代始, material foaming technology. more year and 完善, material foaming already development is full formed production process. as is types formed and can process, material foaming already by cable market full 接受, 并取代 chemical foaming process widely used in production. generally by using/adopting foaming insulation material polyethylene (PE) (PE) and fluorine plastics (FEP), can used for cable, data cable, cable and frequency cable and other. due to need to high foaming degree, material foaming production equipment formed and design need ratio chemical foaming more complex, need more long extrusion machine and gas injection system and other. material foaming main/primary advantages and chemical foaming comparison, material foaming can to foaming degree can obvious improve/increase. 以PE is 例: chemical foaming can to most high foaming degree is 50%, material foaming can to most high foaming degree is 80%. in production different cable product 时, generally to foaming degree different, 例如: for chemical foaming 而言, cable most high foaming degree is 40%; for material foaming 而言, cable most high foaming degree is 60%, data cable most high foaming degree is 65%, 迷你同轴 cable most high foaming degree is 72%～75%, cable most high foaming degree is 78%, frequency cable most high foaming degree is 80%. meanwhile, foaming degree improve/increase make material foaming process tool has more more advantages, 包括: improve/increase 信号 传输 speed degree and frequency rate, from 而进一步 improve/increase product property can; improve/increase production speed degree, decrease/reduce insulation material use amount and outer copper material weight, from 而进一步 reduce production cost. false separation use 实心, chemical foaming and material foaming production types commonly used cable （ according to France standards A2 type ） as comparison, from comprehensive material foaming main/primary advantages, table/sheet 1. types Common cable （如图1 示）拥 has lower property can: inner use copper 线φ3.3mm; retardant resistant is 75Ohms; insulation material is PE; suitable for φ80mm extrusion machine （便于 comparison production speed degree ）. from upper comparison can 看出, use material foaming process 时, can a large amount of insulation material and 屏蔽材 material, meanwhile improve/increase cable property can and production efficiency. material foaming basic principle material foaming key/critical is need will gas 体（ nitrogen gas ） through high pressure injection to extrusion machine in and plastics mixed and. therefore, extrusion screw design must need ensure gas and plastics can to most uniform mixed and 效果. used for material foaming extrusion screw, long ratio （L/D） is 32:1, gas injection in screw long degree 16D, from can by separation is 两 部 separation. 第一段16D long degree screw pressure shrink ratio is 2, its function is will polymer 熔化; 第二段 screw used for will gas and insulation material mixed and, separation screw design structure has reduce melt temperature degree, improve/increase melt viscosity. basic principle 如图2 示. PE insulation material screw extrusion to machine 头, in machine export 处暴露 to large gas pressure lower, 因而形 formed bubbles. if is use 泡-皮 di extrusion machine 头, insulation material will in injection molding parts mold export front 便暴露 to large gas pressure lower. 结果导致 gas 体于导体 and injection molding parts mold between by 释放, 沿 导体 surface formed long bubbles. need solution this issues, must use 三层共挤 machine 头, will thin 皮（ thick degree generally is 0.02～0.05mm）挤 to inner 层, anti gas 体沿 导体 surface 释放. using/adopting 皮-泡-皮共挤 insulation extrusion machine 组（如图3 示）. for/regarding inner thin selection, must need combined in high speed conditions lower formed thin requirements. LLDPE便 can meet/satisfy requirements. types inner thin large large improve/increase insulation 层 延伸 property can （ fracture 延伸）, ensure insulation can good viscous in upper. 图3 used for 三层共挤 extrusion machine material foaming production currently, outer market for/regarding data cable safety property requirements 越 越严格, very more standards requirements use fluorine plastics insulation material. Italy company in this 方面拥 has technology, 并一直 and material supply 商（如 DuPont and other ）紧密 combined as R&D new technology. 众 周知, through nitrogen gas and plastics good mixed combined 并维持 in most stability 状态, can to foaming degree high, fine uniform 效果. is, if in sleeve/set in high speed generate high pressure lower, mixed combined will to large difficult. usually φ60mm extrusion machine is to most high speed degree, must to high speed, this already non 常接近 extrusion machine speed 极限, speed and extrusion amount between already ultra- 出 线 property scope/range. extrusion machine in 此状态 lower long as, heavy effect/influence its stability property, but also in and screw generate high pressure, heavy effect/influence foaming 效果. for this issues, Italy company development fluorine plastics material foaming production 线（如图4 示）. material foaming production 线 主 extrusion machine 以φ80mm代替以 front φ60mm or φ65mm. φ80mm extrusion machine must large 约2/3 转 speed can to 同样 线 speed degree and amount, true positive to extrusion machine most 佳状态, in sleeve/set inner pressure in, make mixed combined more uniform, from to foaming uniform fine 腻 效果. 图4 fluorine plastics material foaming production generally more other supply use front electrical cable production 线 直径 is 300～350mm 牵引轮, Italy company in production in using/adopting more cooling 槽 直径 is 400mm 牵引轮. due to material foaming 芯线直径 ratio other 实芯直径 large, but also material foaming especially easy bending semi effect/influence, therefore generally CATV同轴 cable from 不允许 in full cooling front generate bending, make 进收线盘 for 线盘筒体直径也 has requirements. 当然, data due to small, speed degree fast, must need more cooling, if bending semi small, for property can generate significantly effect/influence, micro loss consumption increase. especially is will this strip/profile production also need 做5mm micro type 同轴, if small 于400mm 牵引轮根本无 method meet/satisfy requirements. therefore, design using/adopting relatively large 牵引轮 anti loss consumption increase and insulation loss bad.