Thermal Shrinkable Tube Is Used In Cable Assembly Of Optical Fiber Fusing Machine And Radio Frequency Coaxial Connector

- Apr 04, 2019-

Firstly, what is an optical fiber fusing machine? Fiber fusing machine is mainly used for the construction and maintenance of optical cable in optical communication. The general working principle is to use high voltage arc to melt the two optical fibers section while using high precision motion mechanism to push them smoothly so that the two optical fibers can be fused into one to realize the coupling of optical fibers mode field.

Next, we introduce how to use the optical fiber fusing machine.

1. Strip the optical cable and fix it on the disc frame. Common optical cables are layered stranded, skeleton and central bundle tube type. Different optical cables should adopt different stripping methods. After stripping, the optical cables should be fixed to the disc frame.

2. The stripped optical fibers are separately passed through the heat shrinkable tubes. Different bundles and different colors of optical fibers should be separated and passed through the heat-shrinkable tubes separately.

3. Open the power supply of the welder and select the appropriate welding mode. There are two kinds of power supply modes of optical fiber fusing machine: adapter and battery. Common types and specifications of optical fibers are: mm multimode optical fibers (ITU-TG.651), SM dispersion non-displacement single mode optical fibers (ITU-TG.652), DS dispersion displacement single mode optical fibers (ITU-TG.653), NZ non-zero dispersion displacement optical fibers (ITU-TG.655), Bi bending resistant optical fibers (ITU-TG.657), and so on. It is necessary to select the appropriate fusion mode according to the type of optical fibers.

4. Fabrication of optical fiber end face. The quality of end fabrication of optical fiber heat shrinkable tube will directly affect the quality of welding, so it is necessary to prepare qualified end facets before welding. A special stripping tool is used to strip the coating, and then clean linen or cotton stained with alcohol is used to rub it on the bare fibers several times. The cutting length of 0.25mm (outer coating) optical fibers is 8mm-16mm with a fine cutting fiber cutter. For 0.9mm (outer coating) optical fibers, the cutting length can only be 16mm.

5. Place optical fibers. Place the optical fibers in the V-groove of the fusing machine, carefully press the optical fibers pressure plate and the optical fibers fixture, and set the position of the optical fibers in the pressure plate according to the cutting length of the optical fibers, and put them into the windshield correctly.

6. Connect optical fibers. After pressing the splice key, the optical fibers move towards each other. During the process of moving, a short discharge cleans the surface of the optical fibers. When the gap between the ends of the optical fibers is suitable, the splicing machine stops moving toward each other, sets the initial gap, measures the splicing machine, and displays the cutting angle. After the initial clearance setting is completed, the core or cladding alignment is performed. Then the welder reduces the clearance (final clearance setting). The arc generated by high voltage discharge melts the left optical fiber into the right optical fiber. Finally, the microprocessor calculates the loss and displays the value on the display. If the estimated loss value is higher than expected, the discharge key can be pressed to discharge again, and the welder will still calculate the loss after discharge.

7. Remove the optical fiber and reinforce the optical fiber fusion joint with double-wall heat shrinkable tube of heater. Open the windshield, remove the optical fiber from the fusing machine, then move the heat shrinkable tube to the position of the fusing point, put it in the heater for heating, and remove the optical fiber from the heater after heating. When operating, do not touch the ceramic part of the heat shrinkable tube and heater because of the high temperature.

8. Fiber disc fixation. Connect the connected optical fiber disc to the optical fiber receiving disc, fix the optical fiber, receiving disc, connector box, terminal box and so on, and complete the operation.

Above is the application case of thermal shrinkable tube in optical fiber fusion machine. For the optical fiber industry, there is a thermal shrinkable tube for optical fiber joint. Later, we will introduce its specific application.

Today, we use the general method, steps, tools and inspection items of RF coaxial connectors to find out where to use thermal shrinkable double-walled tubes in the process of fitting flexible and semi-rigid RF connectors.

1. Mounting tools

1.1 Soft Cable Pressing Tool

The flexible cable clamp matched with the cable can be crimped with the diameter of 2.5-10.5 mm flexible cable. It is suitable for all kinds of RF coaxial connectors using the above cables.

1.2 Semi-rigid Cable Assembly Tool

Semi-rigid cable assembly tools are suitable for SMA RF coaxial connectors to install semi-rigid cables such as SFT-50-2 (RG405/U) and SFT-50-3 (RG402 high temperature shrinkable tube/U). Other types of RF coaxial connectors to install semi-rigid cables can refer to the above tools.

2. Installation methods and procedures

2.1 Installation Method of Soft Cable

Stripping: Stripping according to the size specified in the product drawings can be done with stripping clamp tool or blade, but the core wire, inner and outer insulation layer and shielding layer of the cable must not be damaged. At the same time, the hot shrinkable double-walled tube with adhesive should be prepared for reserve.

B. Welding inner conductor: Install wire clamp and sheath, and weld inner conductor to cable core with solder with melting point above + 125 degree C. Be careful not to burn the cable insulation.

C. External conductor crimping: clamp the clamp into six sides with clamps to make the shield of the cable in good contact with the external conductor.

D. Install the heat-shrinkable double-wall tube: blow the hot air evenly with a blower gun, and shrink the apparent heat-shrinkable double-wall tube.

2.2 Installation Method and Procedure of Semi-rigid Cable

A. Stripping: Stripping with lathe or special tools according to drawings and stripping dimensions.

B. Solder: Solder with a melting point of + 150 C should be used to weld external conductors and solder with a melting point of + 125 C to weld internal conductors.

3. Inspection items

Contact resistance, insulation resistance and dielectric withstand voltage test should be done to check whether there is leakage of bare wires. Thermal shrinkable double-wall pipe should be used to seal and protect the interface.