The project for end tube soldering
1、 Mechanical parts
A、First we fix housing in housing holder, optic fiber is affixed on fiber holder by adhesive tape.
B、Stop adjusting the electrode holder along Z and X axis direction until the position of the electrode is appropriate, then held by bolt.
C、 After one end of modulator is soldered, open electrode holder along Z axis and turn fiber holder 180 degrees along X axis, then close electrode holder to solder the other end of modulator. (If there is some shift of position during soldering, you can just adjust housing.)
2、 Power supply parts
A、The principle of soldering:
The power supply outputs current to heat the electrode and workpiece. As the workpiece temperature climbing to a certain value, the solder is pre-placed on the joint, and then the solder is melt and flows into the gap of joint with capillary action. The tin and plating layer will diffuse and compose each other. This forms a firm joint. In the whole process, there are many factors affecting the welding quality, such as the heating mode, heating duration, welding temperature, heating preservation time, the solder and flux to be used.
Considering the convenience and stability, the hot pressure ( reflow) welding power supply is suggested. The whole heating curve can be shown in Fig.1.
Fig.1 The chart of heating curve
The heating process includes five stages: temperature first up-sloop stage, pre-heating stage, welding temperature up-sloop, welding and cooling down. These keep the heating of the workpiece smoothly by adjustment of heating speed V1、V2 . At the same time, we can set the time of each stage to assure the welding quality.
B、 Composition
Power supply
The inverter similar as hot pressure welding is adopted. The inverting frequency is 1 kHz. The main parameters are as following:
Rated power: 7kVA or 4kVA
Duty cycle: 50%
Temperature setting range: 50～600℃
Error of temperature: ≤±5℃
Warm-up time: 0.1-10s
Heating-maintain time: 0.1-10s
Calefactive rapidity: 20－200℃/s
Temperature adjustment
Electrode (measurement with thermocuple)
The material of the electrode will be confirmed by the experiment. The titanium alloy or copper alloy is no bad material. The shape of electrode is designed basing on the workpiece. The thermocouple will be placed in the electrode forepart near the workpiece.
C、Performance and characteristic
Response rapidly, balanced temperature curve.
The controlling cycle is 1 ms with the 1 kHz invert frequency. It is the 1/20 of industry frequency welding power supply. The control precision is improved remarkably. It supplies the chance to controlling the temperature exactly.
The effect of the workpiece temperture rising is little, high welding quality.
The warm-up stage and heating-maintaining stage is divided in the heating process. So it ensures the heating balance and avoids the over-heating. It brings the high quality product.
Temperature display
The temperature of welding is real time displayed. As the temperature of the point detected by the thermocouple and welding point is different, the temperature adjustment part is included in this system to assure the veracity of the welding point temperature.
Electrode protection
The power supply in this project avoids the shortcoming of electrode abrasion brought by the over-heating. So it reduce the maintain time and extend the duration.