Thermocouple welding method

Thermocouple is one of the most commonly used temperature detecting element in industry. Its advantage is:

1) measuring accuracy is high. Because of thermocouple direct contact with the object being measured, not affected by intermediate medium.

2. Wide measuring range. The commonly used thermocouple from - 50 ~ + 1600 ℃ can renew edge measurement, some special thermocouple minimum measurable to - 269℃（ Such as gold iron nickel chrome) , up to + 2800 ℃ ( Such as tungsten - Rhenium) 。

3. Simple structure, easy to use. Thermocouple is usually composed of two different kinds of metal wire, but is not limited by the size and the beginning of, outside has protective casing, which are very convenient. But thermocouple welding method has a lot of kinds, don't know if you know how many kinds of, let me to introduce the five kinds of welding methods

1, arc welding,

arc welding can be divided into a tributary of the welding and welding of two kinds of communication.

dc welding, thermocouple to connect power anode, carbon rod ( The spectrum) Connect power anode, carbon and heat the top electrode momentary contact arc starting, after waiting for measuring end fused spherical carbon rod quickly left. This kind of welding method is simple, easy to operate, measuring end not defiled, used in welding metal thermocouple.

ac welding is suitable for the welding metal thermocouple. Will measure carefully before welding, 25 A 30 mm oxide was removed, and then to the top of the two electrodes and qi, and ground into twist shape. During welding, at the top of the hot electrode dipped in flux, under arc melting 3 - in a flame of fire 5 s, after waiting for spherical quickly remove and clear away residue on the solder joint. This method is simple in equipment, easy operation, but the thermocouple near the welding points and electrode carburizing defiled.

2, argon arc welding

by dc argon arc welding device, welding torch, welding power source, the high frequency oscillator butt welding power source, such as clamping apparatus of five parts. During welding, using cerium - out of welding gun nozzle Tungsten wire as cathode, is fixed on the fixture welding thermocouple as the anode. When will pilot arc by high frequency, high voltage between the two poles, adopts thyristor voltage regulation, control arc intensity, make the cerium - under argon protection Tungsten arc discharge and the welding between the thermocouple, using arc produced by high temperature melt end of thermocouple wire into small balls. Aim to facilitate the thermocouple with electrodes, work fixture and welding torch can be horizontal and vertical direction in space. Within the welding torch is equipped with 1 mm in diameter and 1. Cerium - 5 mm Tungsten electrodes, is for the use of the different diameter thermocouple welding.

3, welding the

when the welding is used, should first will heat the top electrode heating and dipped in flux ( Such as nickel and chromium - Nickel silicon coupling flux is mixture of sodium tetraborate and quartz sand each half) , and then put the hot electrode acetylene or oxyhydrogen flame, after being fused spherical out quickly, immediately into the hot water wash away residue of welding point. This method is simple, widely used. Suitable for inexpensive welding metal thermocouple.

4, carbon powder welding

carbon powder welding device is similar to arc welding, the difference is the power of a highly is the carbon rods, but containing powdered carbon graphite crucible, other are soldered thermocouple. When welding, the hot electrode inserted into graphite powder, welding is good after a few seconds. This kind of welding method is arc welding is convenient, but easy cause thermal electrode brittle fracture. The method is suitable for inexpensive welding metal thermocouple.

5, brine welding

in the beaker in sodium chloride solution, in water solution into the platinum wire and electrode, and hot electrode as the other. Welding, the solutions of thermocouple at the top with a little contact, connected to the power supply, after waiting for striking power off quickly. This welding method used to welding thin diameter 0. 03mm- 0. 3 mm thermocouple.