Will include a heated to a temperature is needed should be according to the condition on site, the size of the heated parts, quantity and requirements.
General heating method are: solid fuel heating, heating, hot dip - oxygen
Acetylene flame heating, burner, heating, electric heating, etc.
If conditions permit, can be in special furnace (
Such as flame furnace and salt bath furnace, resistance furnace and electric furnace)
In the heat.
When the site condition does not allow, can build by laying bricks or stones a simple stove, using solid fuels such as wood, coke, heated.
If conditions permit, can also be used for spray combustion gas, liquid fuel.
Hot dip heating are usually only used in smaller coupling (
Inside diameter under 100 mm)
, the method is simple, uniform heating.
Oxygen -
Acetylene flame heating method used for the heating part of the small or large parts of the local, the method is simple, but it requires a skilled technology, to prevent overheating and burning of parts.
For large coupling, many sets of oxygen - may be adopted
Acetylene flame heating and heating burner joint use, the effect is very good.
Although electric heating method is a better heating method, but need special equipment, limits its use in the installation site, but the electric induction heating method, still can consider to choose.
In the installation site of electric induction heating is selected for use in large and medium-sized coupling induction coil zhongtong working frequency (
50Hz)
, low voltage and high current.
In the same condition and the same material, the current frequency f and the current one is inversely proportional to the depth of the delta.
Now hope that the delta is big, so there is no using the intermediate frequency (
500～10000Hz)
And the high frequency (
105～106Hz)
Work, and use frequency (
50Hz)
。
Low voltage, high current can make alternating eddy current and hysteresis loss increase, fever.
Usually use the voltage of 380 v and 220 v.
When using a 220 v voltage, as long as shown below, to coil around the workpiece surface, around to get some secret, not around, but around the multilayer (
Series winding direction between the layers should instead, bringing the total magnetic supposed to)
, in order to reduce the distance between the coils and enhance the heating rate and uniformity.
Coil circle number according to the requirements of the magnetic field intensity H, by formula H = 4 PI WI (
Cylindrical spiral inductor coils)
Find out.
According to the construction experience, regardless of size of the coupling, 1 per 1 v voltage.
3 m, 38 ㎜ 2 wires, so as to heat coupling with 220 v voltage, with 38 ㎜ 2 wires around 300 m.
