Secrets of welding. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / welding equipment

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The old joke says that to cook lamb skewers, you need to have at least a rabbit. So it is in the case of electric arc joining of metals: in order to take the first steps towards the secrets of this technology, you will need a transformer, electrodes, and something without which, even if they are available, no welder can work - a shield with a light filter and an electrode holder. Finding most of these necessary things now is not a problem: industry and trade offer a large selection. But for their improvement, as practice shows, the field for creativity is wide. It is even possible to manufacture more convenient, home-made ones. And not only after mastering the technique and knowledge in this area, but also on the approaches to it, for example, the design of the electrode holder (we will talk about it below).

But before you purchase equipment, you need to learn practical information about its features and the relationship with the work that you have to do. And here it is not enough to have an idea that electric arc welding with stick electrodes is the connection of metal parts by translational heating of their junction to a liquid state due to the thermal energy of an electric arc discharge between opposite electric fields: a welded structure (mass) and electrodes. After all, the welding arc can have different power sources. For example, welding AC transformers or welding rectifiers and DC generators.

What is the difference here? And it is even within one of these varieties. For example, when using a DC arc power supply, two types of connection are distinguished: direct polarity and reverse. In the first case, the welding wire - "ground", which is connected to the "mass" - the welded structure, is fixed on the welding rectifier to the "plus" terminal, and the wire from the electrode holder - to the "minus" terminal. Such a connection and current of direct polarity are suitable for cutting metal and welding thick-walled parts that require a large amount of heat to warm them up. By changing the connection of the wires on the rectifier, we get the reverse polarity current used when welding thin-walled parts. The trick here is that at the negative pole (cathode) the temperature is lower than at the positive pole (anode), due to which the electrode melts faster, and the heating of the part is relatively reduced - the risk of burning through is also reduced.

And when working on AC welding transformers, there is neither direct nor reverse polarity of the welding current due to the periodic change in the welding circuit of the positive and negative poles; here are other features of the work.

A few practical recommendations so that the first steps in mastering electric welding are more successful.

The most acceptable electrodes for beginners are AC electrodes with a diameter of 3-4 mm. For the first test welds, it is better to use metal plates with a thickness of 4-6 mm. And from welding shields, I recommend it as the most convenient head shield in work. Its advantage over manual is that the free hand can hold the workpiece to be welded. For cleaning welds from slag, it is also useful to have a heavy chisel with a lever-handle. Finally, one of the most important details of successful work is the electrode holder. It needs special attention.

The fact is that there are many varieties of the design of electrode holders, both professional and home-made. And this is no coincidence, because many requirements are imposed on this simple tool, ranging from security to ease of use.

I want to offer readers my version of the holder, extremely simple in design and reliable, tested in practice and well-proven. It is distinguished by such qualities proven in operation as compactness and lightness, convenience in manipulating the hand during welding, the strength of the electrode in the holder, the possibility of simple and prompt replacement of the used cinder with a new electrode.

In order to make such an electric holder, it is enough to select suitable materials from the materials at hand and perform a number of simple operations (see fig.). You will need a metal corner 1 with shelves measuring 20x20 mm and 100 mm long. Stepping back from one of the ends of 10 mm, we drill a hole 2 with a diameter of 4,1 mm. It is necessary in order to be able to conveniently and quickly change the electrode: by inserting the bare end of the new one into this hole, we will push the cinder electrode out of the holder.

Rice. 1. Homemade electrode holder: A, B, C, D, D - the sequence of stages of its manufacture; 1 - corner; 2 - hole with a diameter of 4 for pushing out the cinder; 3 - areas of narrowing of the corner; 4 - electrode clamp; 5 - welding clamp seam; 6 - handle-insulator; 7 - welding wire; 8 - wire crimping tube; 9 - the place of welding of the end of the wire with the tube; 10 - tube seam, welding; 11 - electrode in working position

Stepping back from the same end 40 mm, arbitrarily narrow the remaining part of the corner 3. as shown in the figure. Next, from a segment of a reinforcing bar with a diameter of 6 mm and a length of 80 mm (or a spring wire of the same diameter), we will make a cranked clamp 4. Having set this spring at the level of the corner cut, we weld its shank in the center of the corner (welding seam 5 - on both sides of the shank). The handle of the holder and at the same time its insulator 6 will be a piece of durite or thick-walled rubber hose with a small inner diameter and a length of 150 mm. Having passed the welding wire 7 through it and having cleaned its end, we press it in, flattening a thin-walled steel pipe 8 of a suitable (small) diameter and 50 mm long. We weld the end of the wire 9 protruding from it for better contact to the tube, and put the latter on the narrowed part of the corner of the holder and also weld it with a U-shaped seam 10. It remains to push the insulator onto the corner, and the electrode holder is ready.

As practice has shown, such an electrode holder is convenient and even indispensable when welding in cramped conditions. Recall that when working with it, as with all similar open-type devices, it is necessary to take precautions and avoid short circuits, that is, long-term contact with the ground.

Author: S.A. Arkhipov

See other articles Section welding equipment.

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