The welding of rotary kiln's barrel

The welding of rotary kiln's barrel is generally divided into manual welding and automatic welding. In welding Process, rotary kiln's barrel need to be moved.

When using manual welding weld the rotary kiln's barrel, if the weld seam has a certain length, we should stop welding. When using auxiliary transmission to move rotary kiln shell, if the kiln shell rotates a certain angle, stop turning and continue welding. Keep repeating until the welding end.

Submerged arc welding. Starting to rotate the kiln when the auxiliary transmission speed is similar with automatic welding machine.
1.The manual welding method is descrided as followed.
1.1Prepared work
1.1.1 Cleaning the paint, rust with a wire brush or angle grinder which is less than 30mm from welding interface on the cylinder. 1.1.2 Establish the contact between the drive signal welding operation platform and driving means rotating the kiln. 1.1.3 cleaning up each roller surface before welding clean and lubricate all roller bearing

1.2 Welding process
1.2.1 Spot welding: welding is distributed on the interface 8-12 decile point, the length of the solder joint is 150-200mm, weld height of about 5mm.
1.2.2Spot welding should be on one side of blunt edge groove or one side of slope. If opening single V groove in the outer cylinder,spot welding should be in the cylinder body. When using X groove, if the large groove is on the inside of the cylinder, spot welding should be on the outside.
If large groove is outside in the kiln , it should be welded in the cylinder. Checking welds after spot, if there is defection, it should be cleaned up to have a new welding.
1.2.3If using X groove when welding, and the groove is on the outside of a large cylinder, spot-welded should be carried out in kiln cylinder body.The distribution of solder joints, length and order is as above. Welding from the outside from the kiln shell welding,Φ4mm electrode as the base on the a first layer, and using Φ5-6mm welding rod on the another layer.It is best to use flat position welding, which is easy to grasp, visual quality is also good. R otating kiln one time after welding 0.5-1m. Then continue to do the welding. When welding on forth of the cylinder circumference, turn the barrel 180°, then continue to do the welding. All external cylinder is welded, do the internal re-welding. At this point you can remove all of the groups of bolts, lap board, which are all cleaned up at the same time.
1.2.4Gouging:In the cylinder, Using carbon arc gouging to clean the drug skin scum(which is produced in spot-weld and the first series bottoming), then do the welding.

1.3Welding precautions
1.3.1 Doing the welding from the end of the kiln to the other end,intermediate welding shold not cross the interface. Each weld should be welded layer by layer, namely doing a layer of solder and then finishing the second solder layer;
1.3.2Each arcing point should be staggered, should not overlap;
1.3.3 The welding interface must be dry. We will not do the welding when the weather is rainy and windy.
1.3.4 Using 3-50 times magnifying glass to check if welds and the cylinder body have cracks, which should be removed and re-welding if founded by people.
1.3.5 After each welding, layer coating must be clean, if not,the next layer welding slag will happen, then affecting the quality of welding.

1.4 welding quality
1.4.1 Appearance:
1.4.1.1Weld surface should be smooth as fine scaly, weld size deviation is 0-3mm;
1.4.1.2No undercut, slag, porosity, craters and other phenomena, undercut ≯0.5mm, continuous length ≯100mm.
1.4.2 Using X-ray to do the fluoroscopy of the inherent quality of:
1.4.2.1Cracks, lack of fusion is not allowed;
1.4.2.2Dense linear pores or slag is not allowed
1.4.2.3Not allowed to have a mesh pores or cellular phenomenon;
1.4.2.4Weld root depth must not exceed 10% of the wall thickness.

2. Welding quality inspection and requirements
2.1 Visual inspection
Whether welding is smooth, the contact point have punch, the actual size of the weld should meets the design requirements. Whether the weld surface have craters, biting flesh, pores, slag, we should clear if the above phenomena exist.Welding surface and district should not have cracks. The deep of undercut should be not more than 0.5mm. Undercut continuous length is not greater than 100mm, the total length should not more than 10% of the weld length. Weld height: external cylinder is not greater than 3mm, internal burning zone is not greater than 0.5mm, other areas should not larger than 1.5mm, the weld should not be lower than the lowest point of the cylinder surface.

2.2 Weld testing and inspection
2.2.1 When using ultrasonic testing, the weld should be checked one by one, whose length is 25% of weld length, reaching JB1152 secondary standard. If there is doubt in the ultrasonic flaw detection, you must check it with ray film.
2.2.2 When using X-ray to do examination, each weld should be checked, whose length is 15% of the length of the weld. We should check again at the intersection. The qualificaton should reach to grade three in GB3323.
2.2.3 When the inspection is unqualified, we should check the length of the weld that is twice as much as than before. If it is not qualified again, 100 percent inspection of the welds should be done.
2.2.4 Repairing any part of the weld should not exceed two times.