It is important for motorists and homeowners to have a device for welding metal parts on hand. Industrial in the distribution network is not cheap - from 3 000 rubles. Self-assembled microwave welding will completely replace it.
We will talk about how to do this later.
The main element of the welding machine
The basis of the homemade product will be a transformer from an old microwave oven.
He provided magnetron power in it and generated up to 4 kilowatts due to the high transformation ratio. In large furnaces, its power is 700-800 watts. The unit created on it will be able to connect thin metal.
You will need:
- Transformer (if you need an aggregate of greater power, you will need two).
- Platform for installation.
- Large section copper wire.
- Long lever.
- Clamp.
- Cable and insulation.
- Electrodes
- Chisel or hacksaw.
- Amperevoltmeter.
Microwave disassembly
The electromagnetic emitter and inverter in it required a high voltage. Therefore, in the converter there are fewer turns on the primary winding and more on the secondary. On the latter, a voltage of 2 kilovolts is formed, which then increases with the help of a doubler.
To make a spot welding machine from a transformer:
- Carefully remove it by removing the case and disconnecting the mounts.
- We remove the secondary winding without damaging the primary.
- Shunts limiting the current strength are removed.
- We wound two or three turns of a new winding with a stranded wire with a cross section of 1 cm or assembled into a bundle of several thin to the same diameter.
So that the thick insulation does not impede the winding operation, we remove it and wrap it with tape from the fabric. In order that the resistance does not increase and the current strength does not decrease, the wire should be minimally short.
Alteration
The converted converter will give the desired output voltage and current up to 1,000 amperes, which will allow micro-spot welding of thin sheet metal.
For a more powerful unit, you will need two modernized, as described above, parts tied sequentially in a chain. Such a welding machine will be able to weld five-millimeter metal fragments.
The identical windings of both converters and their correct combination will allow to avoid the formation of an antiphase, as well as a short circuit!
Check accuracy of assembly, mark conclusions. The serial connection is shown in the diagram.
Measure the values of the “sparks” with an ammeter.
If the source devices had a power of 0.5 kilowatts, then at the input voltage they gave 2 kilovolts at the output and 250 amperes. In a pair, the latter will increase to 500. In order not to create interruptions in the power network, it should be no higher than 2,000 amperes.
The same process occurs during welding. But because of the increasing resistance, when the ends of the secondary winding with a large cross section are connected to the electrodes, significant losses are created.
Electrode preparation
Use copper rods or soldering tips for them.
Their diameters strictly correspond to the cross-section of the wires, which should be as short as possible in order to avoid power losses. It is more efficient to solder electrodes to reduce resistance at the crimp site at the contacts.
To make them interchangeable, do not solder the connections between the wire and the tip. Screw them together by drilling holes of the same size. Nuts and bolts are best used copper, having less resistance.
Control
It is enough to make a switch and levers, providing a sufficient fit of the parts to be welded. To increase the pressing force, supplement the mechanism with screws. For convenience, equip the pressure arm with a length of 60 cm with a durable rubber ring. It will ease the load, and the elastic will fix it.
For work in the home workshop, this is usually enough. So that when pressed, the device does not move along the desktop, its platform is fixed with a clamp.
The switch is connected to the primary winding so that additional resistance and overheating on the contacts do not appear. Place it for convenience on the upper arm.
Attention! The equipment should be turned on only with compressed electrodes, otherwise strong sparking will occur and contacts will burn out!
During operation of the transformer installation, the wires and lugs heat up. Therefore, think about how to arrange their cooling. A household fan is suitable. And when working periodically take breaks.
Work principles
They are almost no different from processes when using a welding machine for industrial production. After compressing the workpieces and touching the electrodes, voltage is applied, and an electric arc arises at the welding site. Her plasma melts metal, connecting parts.
At the place of bonding, a residual voltage is kept for some time, which can be reduced by not immediately disconnecting the contacts after the end of the process.
Using the above recommendations, you can assemble an apparatus for arc welding on your own.
As you can see, with the necessary skills, the availability of source elements and tools, it is quite possible to make a welder yourself. He will be a great help in the household and save your money.