Welding method for measuring end of S-type platinum rhodium thermocouple

The S-type platinum rhodium thermocouple measures the processing quality, directly affecting the temperature measurement accuracy, measurement rate, and product cost of the platinum rhodium thermocouple. At the beginning, there were many processing methods for measuring S-type platinum rhodium thermocouples, and there were three important ones: one was arc welding; Secondly, active welding; The third is the insertion point welding. Let's introduce in detail the actual welding method for measuring S-type platinum rhodium thermocouples.

1. Electric arc welding machine

On a low-voltage DC power supply installation, one pole is connected to a coupling wire, and the other pole is connected to a carbon rod [or molybdenum rod]. The carbon rod collides with the double coupling wire, causing an arc and melting the coupling wire into a spherical shape. This method was applied earlier and is also very common. Its strengths: simple equipment, easy to operate by hand, strong melting point.

trouble:

① Welding points are easily contagious, and carbon rods and wires are prone to arcing, which can easily cause carbon particles to stick to the melting point.

② The size of the solder joint is difficult to control, and the arc welding time determines the size of the solder joint, because it is difficult to control the timing of manual arc welding, resulting in a large difference in melting point.

③ The amount of welding consumables is relatively large, and the required diameter of the welding spot ball is occasionally 2-5 times the diameter of the wire. Each pair of wires requires a double wire of 2.5-5mm or more, and the finer the wire, the longer the wire, resulting in a large amount of precious metal platinum rhodium wire burning.

2. Active welding is popular

From sending doll threads, welding, to threading quartz tubes, all are actively implemented by equipment on the production line. Its characteristics are:

① Equipment control is automated and welding efficiency is high.

② The solder joints are non infectious.

③ Welding pressure, time, and current can be set as needed, and actively controlled during equipment operation to ensure even and sturdy welding points.

④ The amount of welding consumables is relatively large. To ensure the success rate of machine spot welding, the amount of insertion and extraction of two pairs of wires is individually 4mm This equipment system requires a large one-time investment and is suitable for enterprises with a wide range of production and sales.

3. Interstitial welding is popular

Based on the special requirements of platinum rhodium wire welding technology and drawing on the advanced planning concept of precision spot welding machines at home and abroad, in recent years, we have introduced and developed common equipment for processing platinum rhodium thermocouple wires, including exchange type, energy storage type, and inverter type.