How to easily weld a profile pipe
Profile pipes today are used in a variety of designs. This is explained by their greater rigidity, the presence of flat surfaces, simpler mates with each other than with traditional round parts.
Welding profile pipes, despite the prevailing opinion, is simple. At the same time, they can be welded by any known technologies - electric arc, gas, contact welding with any arrangement of elements - at an angle, butt, overlap. In this case, take into account the wall thickness of the pipes, which is different for electric-welded (up to 5 mm), hot-rolled (up to 14), cold-rolled (up to 12). The latter affects the choice of welding mode, the diameter of the electrodes.
When welding, it is important to choose the right electrode. It depends on the wall thickness of the pipes to be welded. For 4-mm, which are often used in practice in the manufacture of structures, thin electrodes with a diameter of 2 ... 3 mm are suitable without any special requirements for them. Welding is carried out with a small current - 50 ... 60A, using, as a rule, an inverter.
The ends of the pipes are cleaned before welding, if necessary, degreased. If the walls are thin, then they are connected without first arranging the chamfers - they provide a thin gap. At any joint, welding is carried out without rotating the structure.
When welding profile pipes end-to-end, first they make tacks in the corners. After adjusting the joints, the seam is welded around the perimeter. If the blanks are thin-walled, then the seam is formed in one pass; if thick-walled - for a few.
Often carry out welding of profile pipes with argon. It is effective in connecting thin-walled elements, which are the walls of pipes. Performing it, it is required: to clean the joints, if necessary - degrease; choose a tungsten electrode. For wall thicknesses up to 2 mm, a non-consumable 1 mm diameter is used; for thicker - 1.6 mm.
After picking up the filler wire, which should be from the same material from which the pipes to be welded are made. Its diameter is 1 ... 1.5 mm for parts with a wall thickness of 1 mm; 2 ... 2.5 mm - with 2 mm or more.
When welding, the electrode is held closer to the seam - there is a dependence - the smaller this distance, the better the boiling process. The movement of the electrode and the additive must be carried out strictly along the seam and not go beyond the area of the protective gas. The wire is fed smoothly into the welding zone.
At the end of the welding process, the current is lowered without removing the non-consumable electrode from the weld pool. First, they turn off the electricity and only after 10 ... 15 seconds the gas supply. This allows the electrode to cool smoothly, to avoid the formation of oxidative reactions on it, which makes its service life longer.
For welding profile pipes using current of direct polarity, its value is 50 ... 120A. Gas is consumed per minute no more than 12 liters.
Gas welding of profile pipes does not require electricity. Use a mixture of oxygen and acetylene. In the process, the welding zone is heated and filler material is fed into it - the latter is melted and fills the gap between the elements.
Pipes are prepared for gas welding in the usual manner; chamfers are made on the edges with a wall thickness of more than 4 mm. The process itself is performed from left to right or vice versa. The first option is preferable because of the better heating of the welding zone; in addition, it is clearly visible by the welder; Differs in greater productivity, lower consumption of the gas mixture. The second method is used more often when welding thin-walled pipes.
With any welding method, the best quality of the seam is obtained with the lower location of the parts to be welded. Therefore, structures from profile pipes need to be turned when performing work.