Manufacturing of electrodes
Modern high-quality electrodes are produced on plants of the electrode or electrode in special workshops. Steel electrode wire for the manufacture of electrodes and the cut rule on the rods to length. Typically, the editing operation, and cutting combined in one right-chipping machine. The surface of the wire is carefully cleaned of rust and other contaminants. Components of the coating must be pre-crushed fine.
During the welding process in a short period of time from the coating components, refractory, and often very poorly soluble in the slag, the slag should be formed. Complete fusion and the formation of the desired composition of the slag in a time like this can happen only when there is a very fine grinding and thorough mixing of the components of coating.
Fragmentation of the components coming in large chunks, is made in two stages: coarse and fine crushing, or grinding. Coarse grinding is different crushers. Subtle grinding or milling of components, often produced in ball mills. Ground components of the ball mill is usually screened on sieves with a number of holes per 1 cm2 1600-3600. From prepared, milled and sifted ingredients produced obmazochnoy paste electrodes. Currently, there are two basic ways to produce smeared electrodes: 1) the dipping or dipping, and 2) crimping.
Paste for dipping should be roughly kneading until creamy state. First mix the dry ingredients, then mix them in a binder solution, usually sodium silicate solution. In the method of dipping the electrode rods are immersed in a bath of liquid obmazochnoy paste and slowly pull out of it, the rods are covered with a uniform layer of coating. The method is preserved only for dipping coatings unsuitable for the application of crimping, for thin coatings and small electrode workshops that do not have obmazochnoy presses.
A more sophisticated and prevalent in the modern factories of the electrode coating application method is carried out on special crimping presses the electrode operating at high pressures, 400-800 am. Obmazochnoy molding paste has the consistency of damp earth and under pressure in the hand stick together into a ball. Obmazochnoy paste periodically. Loaded into a cylinder press. Electrode rods are pushed through the die cylinder in the range of 200 to 600 pc. per minute and leave covered with a dense layer of coating is quite uniform thickness. Upon emerging from the press one end of the electrode holder is trimmed to capture. The modern news electrode provides a capacity of approximately 2,000 tons of electrodes per year in one shift.
Electrodes made dipping are pre-drying at temperatures up to 40-50 ° C Pre-drying is necessary to eliminate the cracking of coating layer, which can be obtained at too high a forced drying. Electrodes because of the small pressure-tested moisture content in the paste does not require pre-drying and immediately subjected to final drying. The final drying or calcination of the electrodes is intended to remove all moisture as possible from the pasta and add a layer coating the maximum mechanical strength due to chemical reactions between the glass and liquid components of the coating.
The final drying can be carried out forcefully, at high temperatures. For electrodes that do not contain organic matter, temperature calcination can be brought to the 300-400g, C, for coatings with organic substances - not more than 150-180g, C to avoid decomposition of organic matter. At the end of drying, the electrodes are in control and packaging. From each batch, a sample of electrodes for welding trial. The electrodes should be stored in a dry heated room in order to avoid damage to the electrodes.
See also:
Classification of covered electrodes
The composition of electrode coatings
Appointment of individual coating components SSSI-13
Manufacturing Electrodes
Welding Electrodes
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