It is difficult to imagine the construction industry or engineering without welding. It is divided into two types: direct and alternating current.
The use of direct current provides a better weld. This is explained by the absence of zero current values, which means that the arc burning becomes more stable, spatter from the burning electrode decreases, the penetration of the metal is deeper, the strength characteristics of the weld are improved.
In addition, with materials such as cast iron, high alloy steels, alloys based on nickel and copper, titanium, DC welding can only be used.
To convert an alternating current having a frequency of 50 Hz to direct, a welding rectifier is used. It uses semiconductor valves and special control devices in a transformer. There are various types of such products. Each of them has in its design a rectifier block, ballasts for protective and measuring equipment and a power transformer.
A welding rectifier is used for manual arc welding, when the electrodes are melted, and pulse-arc, in which the pulse helps to separate a drop of metal from the wire electrode.
For the convenience of mechanical welding, a special rectifier welding transformer type VD was created, which has a remote mode switch. Such converters are characterized by basic technical solutions:
- in one range, the current control for welding is smooth;
- magnetic wedge movable shunt, horizontal design, provides mechanical adjustment of the weld, has a simple design;
- transformer windings are made of copper;
- no movable windings;
- air cooling;
- ignition is easy, the arc burns steadily;
- insulation class - N;
- current connectors are safe and quickly open;
- in installation conditions, this type of welding rectifier is easy to move.
Sometimes at home there is a need to perform welding work. In this situation, there are two options - buy a ready-made machine or make a welding rectifier yourself.
The main element of a home-made rectifier is a transformer designed to convert AC voltage to the network and ensure the necessary size and quality of the welded current. It can be connected to a network with a voltage of 220 V, and at the output it should provide 40-70 V.
Next, to the terminals of the transformer, you need to solder the network wire of about 2.5 square millimeters in diameter and about 5 meters long, for convenient movement of the welding machine. The wire is best used in double insulation.
The next step is the preparation of cables for welding. For this purpose, it is better to use soft wires with rubber insulation, at least two meters long. At the end of one cable we fasten the “mass” clothespin (sometimes you can use a car “cigarette lighter”), on the other cable there is an electrode holder.
Now the welding rectifier needs to be assembled. It depends on how convenient the device will be during operation. During operation, it will heat up, which means that the case must be made with ventilation holes. For ease of transportation, we attach handles to the case and install wheels. You can install additional elements in the form of hooks, washers, corners for laying wires and cables.