The formation of the excess length of the optical cable mainly comes from the secondary coating and the cabling process, which together determine the size of the excess length of the optical cable. The secondary coating process is the most important process for adjusting the excess length and excess length of the optical cable. It can achieve the purpose of adjusting the excess length by adjusting other process parameters.

There are many factors that affect Yu Chang, and they are both independent and interconnected. In the second set of production, each link affects the size of the excess length to varying degrees. To sum up, the following aspects have an impact on the excess length.

The effect of pay-off tension on the excess length is that the greater the tension, the greater the degree of stretching of the optical fiber, the greater the negative excess length relative to the bundled tube in the hot water tank section, and the smaller the final excess length. Therefore, in production, due to the instability of the pay-off frame or the excessive pay-off force, the remaining length of the bundle tube will be unstable, resulting in a large difference in the length of each optical fiber in the bundle tube. Some devices are active pay-off and some are passive pay-off, but the unstable tension has an impact on the excess length of the optical fiber, and the passive pay-off has a greater impact.

The excess length tension is one of the most common process parameters for adjusting excess length in our daily production, and its adjustment is more sensitive to changes in excess length. When the tension of the excess length is increased, the excess length of the bundle tube becomes smaller, on the contrary, the excess length of the bundle becomes larger when the tension is adjusted. Adjusting the excess length tension is an easy-to-control adjustment method. It also has a stable measurement and is easy to adjust, but its adjustment range is not very large, and the excess length can only be adjusted in a small range.

The temperature of the hot water tank is also the main process parameter for adjusting the excess length of the bundle tube. Under the condition that other parameters are stable and unchanged, the general temperature increases and the excess length becomes larger, and vice versa. Generally, the temperature of hot water is higher than 45°C. Since the crystallization temperature of PBT is generally higher than 45~50°C, if the temperature of hot water is too low, poor crystallization of PBT will affect the performance of the bundle tube, and the bundle tube will shrink very much later. big. The temperature difference between hot water and cold water is the final determination of the excess length of the bundled tube. Generally, the greater the temperature difference, the greater the shrinkage of the bundled tube and the greater the excess length, and vice versa.

The performance of the ointment is also an important factor affecting the stability of the excess length. In our daily production, we often look at the stability of the ointment liquid level between the extruder head and the hot water tank to judge the stability of the remaining length of the bundle. The viscosity of the ointment is an important factor in determining the size of the excess length.

The viscosity of the fiber paste is inversely proportional to its heating temperature. When the temperature increases, the viscosity of the fiber paste decreases, and the viscosity of the fiber paste has a large influence on the remaining length of the bundle. When the viscosity of the fiber paste reaches a certain level, the excess length of the bundled tube cannot be controlled, and the excess length of each optical fiber in the bundled tube may vary greatly. In the production process, the chemical bond of the fiber paste is broken when it is subjected to shearing force, and the viscosity is greatly reduced. The fiber paste has good fluidity and meets the production requirements. When the shear force is withdrawn, after a certain period of time, the chemical bond will be restored, and the viscosity of the fiber paste will not flow out of the bundle tube. This property of the fiber paste is called thixotropy. In this way, the viscosity of the fiber paste is small during the production of the bundle tube, the optical fiber can move freely, and the excess length of the optical fiber is easy to control. If the viscosity is too high, the movement of the fiber is difficult, and the excess length of the fiber is difficult to control. Common fiber pastes on the market include unigel., DAE and Han paste, etc. They all have different viscosities and different product models to meet the requirements of different equipment and different types of products. Some equipments have a production speed of 400m/min, so there are special requirements for the viscosity of the fiber paste.

The mold oil needle and fiber guide of the fiber paste extrusion also have a certain influence on the excess length of the bundle tube. The size of the oil needle or fiber guide needle directly affects the extrusion stability of the fiber paste. The extrusion stability of the fiber paste determines the motion trajectory of the optical fiber, so generally the extrusion of the fiber paste is unstable, which means that the excess length of each fiber is very different. The configuration of the appropriate mold is also the main aspect that determines the quality of the remaining length of the bundle. The mold configuration is unreasonable, and a large amount of air will be wrapped in the bundle when two sets are used, so that there are many vacuum bubbles on the surface of the bundle, and the bundle is placed for a period of time. The bubbles did not disappear, indicating that the air was involved in the unstable liquid level of the ointment.

In the process of cabling, the formation of excess length mainly comes from the relative length of the bundle tube and the optical cable. It can be seen from formula 1 that after the structure of the optical cable is fixed, the remaining length is determined by the twist angle between the bundle tube and the filler core when the cable is formed. Generally, the larger the twist angle, the larger the remaining length. It can be seen from formula 2 that the factor determining the twist angle is the cable pitch. The smaller the pitch, the greater the twist angle and the greater the excess length. Stranding is also an important source of excess length. Some companies deliberately form zero excess length during the production of the second set, the purpose is to use the cable to form the excess length is enough.

The formation process of the excess length of the optical cable

With the long-term development of optical cables, the production process of optical cables has become very mature, and various materials are mainly on the research of very cutting-edge optical communication systems. At this stage, there are few articles on the basic technology of traditional optical cable production. This article will discuss the most important process parameter of conventional optical cables - the excess length of the optical cable. The excess length of the optical cable is the most critical process parameter in the production process of the optical cable, and it is also the process parameter with the most influencing factors. It is an important process index to determine the various properties of the optical cable.