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Talking about the design and manufacture of optical fiber cables

Dec 29, 2017

Talking about the design and manufacture of optical fiber cables

  

I. Introduction

       The end of 2013, the Ministry of Industry and Information Technology to China Mobile, China Telecom, China Unicom officially released the fourth generation

China Mobile, China Telecom and China Unicom all obtained TD-LTE licenses for their mobile communications service licenses (ie 4G licenses), marking a formal entry into the 4G era for China's telecom industry.

       As the three major operators compete for market share, 4G-LTE base station construction scene in full swing, base station mode

Generally follow the 3G BBU (radio remote module) + RRU (baseband processing unit) building station mode, RRU and BBU need to use optical fiber connections, a BBU can support multiple RRU, can be a good solution to large venues and complex buildings Coverage, remote cable plays an important role in mobile communications.

 

Second, pull away the cable

       Because the BBU + RRU mode is generally used for short-range and indoor coverage scenarios, optical fiber cables may pass through corridors, indoor wiring ducts, shafts and the like, and air blow may also be used in some places. Therefore, this type of cable is different from ordinary optical cables and belongs to Special category of light friends, the general requirements of the cable light weight, small diameter, small bending radius, dry structure, flame retardant, tensile and so on. We generally call this type of optical cable to pull the cable away from the single-core flexible cable, Kevlar armor and halogen-free halogen sheath composition.

       Distant optical cable is usually all-dielectric form, that is, using non-metallic reinforcement. Because BBU + RRU remote base stations have a small requirement on the number of optical fiber cables, the combination method is flexible and flexible. In some scenarios, optical hybrid structures may also be used.

 

Third, pull away the cable processing technology

       1, single-core soft optical sub-unit process control

       Sub-unit single-core soft optical cable sheathing layer can be color or surface printing according to the need to be distinguished in the production process should pay special attention to the outer diameter of the optical fiber and sheath after the contraction control, after the contraction required to less than 3 ‰, so Selection of the sheathing material in the production process and the matching of the die size should be strictly controlled to ensure the normal use of the product and the subsequent processing and process control of the product.

       Single-core flexible cable before the sheath extrusion according to the design needs to consider Aramid wiring options around the tight sleeve optical fiber straight or spiral stranded around the package, the general requirements of aramid cloth evenly, aramid fiber release tension To be uniform 2-3N, for the helical twist around the package, the pitch is generally required to control between 500-600mm, to avoid uneven stretching during the tensile force, resulting in cable strain and strain of the cable exceeded. The tension of the single-core sleeve fiber should also be uniform and required to be controlled at 6-8N. Otherwise, the fiber strain will be uneven.

       2, dilate the structure into the cable process control

       For the difference between the process control of the cabled process control and that of the ordinary optical cable, generally, the optical fiber core or the sub-unit optical fiber cable is stranded around the non-metal center reinforcement (may not have the center reinforcement) In order to ensure the integrity and structural stability of the cable core, a helical twisted cable is generally adopted. The front cable core of the jacket usually encloses a water blocking tape or a polyester cable to protect the cable core so as to prevent the jacket material from being connected with the tight sleeve or the subunit structure , Affecting the use of stripping; Secondly, when the cable into the cable to pay attention to the tension of the cable core impact.

       3, pull the cable sheathing process control

       According to the environment and conditions of the cable being pulled away, the LSZH is generally adopted for the sheath, and other materials (polyurethane TPU) can be used according to the special requirements of users.


       Low-smoke halogen-free materials processing temperature should not be too high, the screw need to be dedicated low smoke halogen-free screw, the temperature is recommended as follows:

Heating zoneHeating Zone 1Heating Zone 2Heating Zone 3Heating Zone 4Heating Zone 5FlangeHeadDie mouth
Temperature ℃105125150150155160160165

       

 105 125 150 150 155 160 160 165


       In order to ensure the stability of the cable sheath wall thickness and outer diameter, the sheath extrusion die adopts a tube-pulling die, the dimensions of the die core and die sleeve should be strictly calculated, generally according to the requirements of the LZSH sheathing material Stretching than the performance control at 2.0 or so, and its tensile balance, the general requirements of about 1.05 control, in theory, the smaller the stretch ratio, the jacket surface is more bright and clean.


       Considering the post-shrinkage of the finished optical fiber cable, the tension of the control cable should be controlled to effectively reduce the post-shrinkage. The tension of the cable should be generally controlled at 30-40N. At the same time, it is necessary to ensure sufficient cooling and production line speed of the optical cable in the production process, Large, abnormal sound performance indicators.

 

Fourth, concluding remarks

       At present, with the widespread application of distributed base stations, there is an increasing demand for the optical fiber cable market. However, the environment in which it is used is very complicated. Therefore, due to the particularity of its structure, the theoretical design and test structure may be more Large differences, the need for continuous commissioning, the experimental data and the theory is relatively, adjust the design and calculation of the various parameters in order to sum up a set of theoretical design for their own.