When fiber optic splicing is reinforced, usually only one optical fiber is placed in a single-core optical fiber heat shrink tube (except optical fiber ribbon cable). If multiple optical fibers are placed in a single-core optical fiber heat shrink tube, the advantage is that heat shrinkage The number of tubes will be greatly reduced, the cost will be reduced, the space in the joint box will be saved, the working time will be greatly shortened, and the power consumption of the welding machine will be saved.
The following focuses on analyzing the performance of the optical fiber after heat shrinkage.
1. The degree of optical fiber damage increases. From the above analysis, it can be seen that the difference between the optical fiber in the connector part and the optical fiber protected by the coating layer is: (1) The peeling off of the coating layer causes the surface of the optical fiber glass to be hardened. scratched by objects, the strength decreases; (2) retention in the air, causing micro-cracks on the surface of the optical fiber; (3) high temperature distribution gradient during hot melting, generating stress near the joint; 4) joints without coating layer Protection, very fragile.
Due to the characteristics of a single-core fiber heat-shrinkable tube, the pressure exerted on the fiber during heat shrinkage comes from around the fiber. If an optical fiber is placed in a single-core fiber heat-shrinkable tube, the fiber connector will The pressure comes from the melted hot-melt tube; if multiple optical fibers are placed in a single-core optical fiber heat-shrinkable tube, the multiple optical fiber connectors will inevitably squeeze each other during heat shrinkage, causing uneven stress on the optical fibers, resulting in the original very abnormal Increased damage to fragile fiber optic connectors.
Even if the optical fibers are arranged side by side in the single-core fiber heat-shrinkable tube before heat shrinking, the arrangement will be changed due to the heat shrinkage pressure during heat shrinkage, causing twisting, micro-bending, and damage. Ribbon optical fiber The heat shrink protection sleeve is mainly used for the bare fiber part of the ribbon fiber splice. It is composed of a transparent heat shrink tube, an elliptical hot melt tube and a semi-circular white ceramic reinforcement that is resistant to high and low temperature changes. The ribbon fiber heat shrink protection The bushings are divided into two types: single ceramic and double ceramic.
Due to the design of the reinforcement, the ribbon fiber heat shrinkable tube is different from the single core fiber heat shrinkable tube. During heat shrinkage, the pressure on the ribbon fiber mainly comes from the top and bottom of the fiber, and due to the ribbon shape The unique ribbon-joining process of optical fibers allows ribbon optical fibers to be arranged in a row, and the pressure between the optical fibers is very small and can be ignored.
Therefore, just because ribbon optical fiber can be heat-shrunk with multiple fibers in the same heat-shrinkable tube, it does not mean that a single-core optical fiber heat-shrinkable tube can also heat-shrink multiple optical fibers.
2. The filling and sealing effect is not good. In addition to increasing the mechanical strength of the optical fiber connector, the most important function of the heat shrinkable tube is to play a filling and sealing role to avoid residual bubbles in the protective tube and prevent Moisture intrusion, thereby maintaining the long-term stability of optical fiber transmission performance.
Place multiple optical fibers in a single-core optical fiber heat shrinkable tube. The gaps between the optical fibers and the optical fiber connectors cannot be completely melted by the heat-capacitance tube.filled, resulting in a small amount of air remaining in the heat shrink tube. The air will increase and deepen the micro-cracks on the surface of the bare optical fiber, accelerate the aging of the connector, shorten the service life, and affect the temperature characteristics of the optical fiber connector.
3. When multiple other optical fibers are heat-shrunk together, it cannot be fully guaranteed that uniform tension is applied to all optical fibers, nor can it be fully guaranteed that all optical fibers are in a straight line. Multiple optical fiber connectors are heat-shrunk together, making fiber coiling difficult. If the fiber is increased, it is easy to damage other optical fibers during fiber coiling.
In addition, when dealing with the failure of one of the core optical fibers, it also increases the risk of man-made failure of other optical fibers, making daily maintenance more difficult.
Therefore, placing multiple optical fibers in a single-core optical fiber heat shrink tube for heat shrinking can be convenient, but it must be completely ensured that the optical fibers do not squeeze each other and are not twisted. Make sure there are no residual bubbles in the heat shrink tube. It is very difficult to operate and poses hidden dangers to normal operation. It is not recommended to use it in optical cables.
Although it is not recommended to place multiple optical fibers in a single-core optical fiber heat-shrinkable tube for heat shrinkage, there is a heat-shrinkable tube "multi-core optical fiber heat-shrinkable reinforced tube" that can be used for multiple optical fibers, which ensures Heat shrinkable quality and easy to operate.
Multi-core optical fiber heat-shrinkable reinforced tubes. There are many heat-shrinkable plastic sub-tubes inside a large heat-shrinkable plastic sleeve. Each sub-tube hole can seal an optical fiber. Inside the large heat-shrinkable plastic tube A stainless steel wire is inserted into the center of the casing.
Changing the original single-core optical fiber heat-shrinkable reinforced tube to a multi-core optical fiber heat-shrinkable reinforced tube can double the capacity of each fiber tray, thereby reducing the size of the splice box, making Operation is more convenient.
In addition, if you really want to temporarily rush through and save time, it is recommended that the number of protected optical fibers in an ordinary single-core hot melt tube should not exceed 6 at a time. And each optical fiber should be even and equal in length.
