OPGW optical cable fusion is a meticulous work, especially in the links of end face preparation, welding, fiber coiling, etc., requiring the operator to observe carefully, consider carefully, and operate in a standardized manner.
Concrete steps and practical tips.
1. Preparation of the end face: The preparation of the end face of the optical fiber includes stripping, cleaning and cutting. A qualified fiber end face is a necessary condition for fusion splicing, and the quality of the end face directly affects the quality of fusion splicing.
Stripping of the optical fiber coating surface layer: the stripping of the optical fiber coating surface layer must master the flat, stable, and fast three-word fiber stripping method. "Ping" means keeping the fiber flat. Pinch the optical fiber with the thumb and index finger of the left hand to make it horizontal. The exposed length is 5cm. The remaining fiber is naturally bent between the ring finger and the little finger to increase strength and prevent slipping. "Steady" means that the fiber stripping pliers should be held firmly. "Fast" means that the fiber should be stripped quickly. The fiber stripper should be perpendicular to the fiber, and the upper direction should be inclined at a certain angle. Then use the jaws to gently clamp the right hand of the fiber, and then forcefully push it out along the fiber axis. The whole process takes Natural and smooth, in one go.
Cleaning of bare fibers:
The cleaning of bare fiber should be done in the following two steps:
1) Observe whether the coating layer of the stripped part of the optical fiber is completely stripped off. If there is any residue, it should be stripped again. If there is a very small amount of coating layer that is not easy to peel off, you can use a cotton ball dipped in an appropriate amount of alcohol, and wipe it off gradually while dipping.
2) Tear the cotton into flat fan-shaped small pieces, dip in a little alcohol (it is better to pinch with two fingers without overflow), fold it into a "V" shape, clamp the stripped optical fiber, wipe along the optical fiber axis, and strive to Once successful, a piece of cotton should be replaced in time after 2-3 times of use, and different parts and layers of cotton should be used each time, so that the utilization rate of cotton can be improved, and the double pollution of the fiber probe can be prevented.
Cutting of bare fiber:
The cutting of bare fiber is the most critical part in the preparation of optical fiber end face. Precise and excellent cutting knife is the foundation, and strict and scientific operation specifications are the guarantee.
1) Choice of cutter: There are two kinds of cutters: manual (such as Japan CT-07 cutter) and electric (such as Ericsson FSU-925). The former is easy to operate and reliable in performance. With the improvement of the operator's level, the cutting efficiency and quality can be greatly improved, and the bare fiber is required to be shorter, but the cutter has higher requirements on the ambient temperature difference. The latter has higher cutting quality and is suitable for working in the field under cold conditions, but the operation is more complicated.
The working speed is constant, and the bare fiber is required to be longer. It is better for skilled operators to use manual cutters for fast optical cable splicing or emergency rescue at room temperature; on the contrary, for beginners or when working in colder conditions in the field, it is better to use electric cutters.
2) Operating norms: Operators should undergo special training to master the essentials of action and operating norms. First of all, clean the cutter and adjust the position of the cutter. The cutter should be placed stably. When cutting, the movement should be natural, steady, not heavy, and not urgent to avoid bad end faces such as broken fibers, bevels, burrs and cracks. In addition, learn to "play the piano", rationally allocate and use your right fingers, make them correspond to and coordinate with the specific parts of the incision, and improve the cutting speed and quality.
3) Beware of contamination on the end surface: the heat shrinkable sleeve should be inserted before stripping, and it is strictly forbidden to penetrate after the end surface is prepared. The time of cleaning, cutting and welding of bare fibers should be closely linked, and the interval should not be too long, especially the prepared end face, and should not be placed in the air. Handle with care when moving to prevent rubbing against other objects. During the splicing, the "V" groove, pressure plate and blade of the cutter should be cleaned according to the environment, and the end surface should not be polluted.
2. Optical fiber fusion splicing: Optical fiber fusion splicing is the central link of the splicing work, so high-performance fusion splicing machines and scientific operations during the fusion splicing process are very necessary.
Selection of fusion splicing machine:
According to the requirements of optical cable engineering, it should be equipped with fusion splicing equipment with suitable battery capacity and precision. According to experience, the Japanese FSM-30S arc welding machine has excellent performance, stable operation, high welding quality, and is equipped with a dustproof windproof cover and a large-capacity battery, which is suitable for various large and medium-sized optical cable projects. The Siemens X-76 fusion splicer is small in size, easy to operate, equipped with a simple cutter, the battery and the host are combined into one, easy to carry, the accuracy is slightly worse than the former, and the battery capacity is small, suitable for small and medium-sized optical cable projects.
Splicing procedure:
Before splicing, according to the material and type of the optical fiber, set the key parameters such as the optimal pre-melting main melting current and time, and the amount of fiber feeding. During the welding process, the "V" groove, electrode, objective lens, welding room, etc. of the welding machine should be cleaned in time, and there are no bubbles, too thin, too thick, virtual melting, separation and other bad phenomena in the welding at any time, and pay attention to the tracking and monitoring of the OTDR test instrument As a result, timely analyze the causes of the above undesirable phenomena and take corresponding improvement measures. If virtual fusion occurs many times, check whether the materials and models of the two optical fibers to be fused are matched, whether the cutter and the fusion splicer are polluted by dust, and check the oxidation status of the electrodes. If there is no problem, the fusion current should be increased appropriately.
3. Disk fiber: disk fiber is a technology and an art. The scientific fiber coiling method can make the optical fiber layout reasonable, the additional loss is small, can withstand the test of time and harsh environment, and can avoid the phenomenon of fiber breakage caused by extrusion.
Disc fiber rules:
1) Coil the fiber for the unit along the direction of the loose tube or the branching direction of the optical cable. The former is applicable to all splicing projects; the latter is only applicable to the end of the main optical cable and has one input and multiple outputs. Most of the branches are small logarithmic optical cables. The rule is to reel the fiber once after splicing and heat-shrinking one or more fibers in loose tubes, or fibers in a branched cable. The advantage is to avoid the confusion of optical fibers between loose tubes of optical fibers or between different branch optical cables, making it reasonable in layout, easy to reel, easy to dismantle, and easier to maintain in the future.
2) The heat-shrinkable tube placement unit in the reserved tray is used as the unit for fiber coiling. This rule is based on the number of heat-shrinkable tubes that can be placed in a small placement area in the reserved tray in the splice box. It avoids the unevenness of the same bundle of optical fibers caused by different placement positions, difficulty in coiling and fixing, and even sharp bends and small circles.
3) In special cases, such as optical splitters, add/drop pigtails, pigtails and other special devices in the splicing process, it is necessary to splice, heat shrink, and coil ordinary optical fibers first, and deal with the above situations in sequence, and often reel them for safety. operation to prevent the increase of additional losses caused by extrusion.
Disk fiber method:
1) First the middle and then both sides, that is, first place the heat-shrinkable sleeves in the fixing groove one by one, and then process the remaining fibers on both sides. Advantages: It is beneficial to protect the fiber joints and avoid possible damage caused by the fiber coil. This method is often used when the optical fiber reserved disk space is small and the optical fiber is not easy to coil and fix.
2) Coil the fiber from one end, fix the heat shrink tube, and then process the remaining fiber on the other side. Advantages: The position of the copper pipe can be flexibly selected according to the length of the remaining fiber on one side, which is convenient and fast, and can avoid sharp bends and small circles.
3) The treatment of special cases, such as when individual optical fibers are too long or too short, they can be placed at the end and coiled separately; when there are special optical devices, they can be processed in another coil, if they are co-coiled with ordinary optical fibers, It should be lightly placed on the ordinary optical fiber, and a buffer liner should be added between the two to prevent fiber breakage caused by extrusion, and the tail fiber of special optical devices should not be too long.
4) According to the actual situation, a variety of graphic disk fibers are used. According to the length of the remaining fiber and the size of the reserved space, it should be coiled naturally according to the trend, and do not pull it hard. It should be flexible to use circular, elliptical, "CC", "~" various patterns of coiled fiber (note that R≥4cm), as much as possible. Use the reserved space and effectively reduce the additional loss caused by the fiber coil.
4. Ensure the quality of fiber optic cable splicing:
Strengthening the monitoring of OTDR test instruments is of great significance to ensure the quality of optical fiber fusion, reduce the additional loss caused by the fiber coil and the damage to the optical fiber that may be caused by sealing the box. During the whole continuous work, the four monitoring procedures of OTDR test instruments must be strictly implemented:
1) Real-time tracking and monitoring of each core fiber during the fusion splicing process to check the quality of each splicing point;
2) After each fiber reel, carry out routine inspection on the reeled fiber to determine the additional loss caused by the reel;
3) Before sealing the splice box, conduct a unified measurement of all optical fibers to find out whether there is any missing measurement and whether the reserved space for optical fibers squeezes the optical fibers and connectors;
4) After sealing the box, perform final monitoring on all optical fibers to check whether the sealing box has damaged the optical fiber.
5. Conclusion: Optical fiber splicing is a meticulous work, especially in the aspects of end face preparation, welding, and fiber coiling, which require the operator to observe carefully, consider carefully, and operate in a standardized manner.
In short, it is necessary to cultivate a rigorous and meticulous work style, and be diligent in summarizing and thinking, in order to improve practical operation skills, reduce splicing loss, and comprehensively improve the quality of optical cable splicing.
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