光纤拉丝塔

In order to meet the huge demand for optical fiber for telecommunications applications, many companies have had to build new plants and install new fiber facilities all around the world. Today, the optical fiber manufacturing process is quite similar across all the manufacturers.

However, obtaining optical fiber with the very best properties and performance levels, and with a long working life, requires a certain know-how that has remained a secret. Subsequently, the performance levels of measurement instrument, along with process control, are critical to insuring that producers’ quality standards are met.
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光纤拉丝塔是怎么构成的？

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光纤由多层纯玻璃圆柱体（称为预制棒）制成。 巨大的预制棒（一般周长20厘米，高2m）垂直放置在拉丝塔的顶部，由于最终的玻璃光纤是通过“拉”成熔融态的流体而获得，因此通常称为拉丝塔。

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业内常见的拉丝塔高度在 30 至 45 米之间，从塔的顶部到底部需要各种类型的设备来制造和控制拉丝过程。 在拉丝塔顶部，预制棒的底座在加热炉中加热成流动的熔融状态，熔融态的石英流体通过重力逐渐下垂变细，拉出最初的玻璃光纤。 当光纤拉制开始时，充满氦气的冷却管会降低涂覆前的光纤温度。 涂覆过程可以通过一个或两个步骤完成，并且需要使用固化炉以确保涂层在光纤与滑轮接触之前固化。 现在越来越多的制造商使用高强度 UV LED（不是白炽灯）来固化涂层，以减少电力消耗并减少拉丝塔的空间要求。

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拉丝过程的控制

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All along the draw tower, various measurement instruments provide all of the relevant parameters needed to optimize the process:

- Diameter measurements of the bare fiber (top) and of the coated fiber (bottom).
- Position of the fiber (X-Y) and, more globally, alignment of the devices all along the draw tower.
- Drawing tension measurement to adjust the speed and temperature of the drawing process.
- Internal defect detection inside the glass, but also inside the coating layers, to prevent the optical fiber from having inadequate performance levels.
- Lump & Neckdown detection after the second coating layer.

Digital inputs and outputs, analog outputs (voltage or current), RS232, and a field bus are used to connect these devices to the tower PLC for loop requirements and measurement analysis. Globally, these specific instruments provide control capability to maintain, record and analyze product and tower parameters. Because production is 24/7 almost all year round, these devices need to be very reliable. Since increased drawing speed is an essential factor in improving the productivity of production plants, high-speed and high-accuracy performance of the devices are essential to insure complete in-line certification of the fiber.