Bolt welding of "160000t carbon calcining kiln and rotary kiln" of jinal

 

The corrugated anchor pin assembly is composed of five parts: corrugated anchor pin, nut 1 (M12 blind hole), washer, screw (M12) and nut 2 (M12). The outer diameter of the nut 2 is φ 22mm, and the nut 2 and the screw are welded on the inner wall of the furnace (referred to as the welding of the nut assembly), as shown in Figure 5. Although the nut assembly is made of heat-resistant stainless steel, the furnace wall is made of low-carbon steel, so when welding, the molten pool shall also be protected. The easiest way is to spray arc striking agent on the welding surface of nut 2. Before welding, screw the screw into the nut and align the end faces of the two parts, so that the two parts can be welded on the inner wall of the furnace at the same time. After welding, assemble the corrugated anchor pin weldment to fix the refractory.

 

 

 

a. Schematic diagram of component transverse welding

 

 

 

b. Photo after transverse welding

 

Figures a and b show the transverse welding of the nut assembly on the inner wall of the furnace. The nut assembly welded around the furnace wall should be evenly distributed, so there are various directions when welding the nut assembly: flat welding, transverse welding, overhead welding, etc., which belong to all position welding. Transverse welding and overhead welding are two difficult welding positions in nut assembly welding. For the transverse welding, based on the original transverse welding process, it is adjusted according to the specific situation of the nut assembly, as follows:

 

Welding current: 2100A, welding time: 0.8s, lifting height: 3mm, extension length: 3mm

 

Stud welding machine: rst-3150-3, rst-2500-3.

 

Through test welding, visual inspection of weld, 30 ° bending test and tensile test, formal welding shall be carried out after qualification. Four welders of the construction company worked day and night, completed the welding of more than 60000 nut components in only 20 days, gained time, ensured the progress of the project, and won the praise of users.

 

In the inspection and statistics of the transverse welding quality of about 20000 nut assemblies, the qualified rate of one-time welding is 93%. The weld appearance defects are mainly discontinuity or concave holes. These defects can be repaired by hand. The mechanical properties of the repaired joint can also meet the requirements of the standard. The main reason for the above defects is related to the welder's operation technology. When the welding pin is horizontally welded, the molten metal accumulates more in the weld pool. At the moment when the welding pin is inserted into the weld pool, sparks are splashed everywhere, and the hand holding the gun is easy to vibrate. As long as the welding gun moves a little or the porcelain ring is not flattened, and there is a little air gap, a large amount of molten metal will be sprayed out, which will make the weld crater. On the other hand, due to the frequent up and down movement of the welding position, it is very difficult for the hand-held welding gun to always be on the same horizontal line with the welding position, and it is very easy to tilt up and down, so that there is a gap between the porcelain ring and the workpiece, resulting in liquid spraying, resulting in concave holes. As long as these problems are overcome, the qualification rate of primary welding can be greatly improved. In fact, there is a big difference in the qualification rate of the first welding among the four welders, which fully shows that the operation technology of the welder has an important impact on the quality of the transverse welding of the nut assembly. Therefore, strengthening the training of welders is an important link to improve the quality of transverse welding.

 

The overhead welding of the nut assembly is another difficulty in the bolt welding project of the furnace. According to the characteristics of the overhead welding and the actual situation of the nut assembly, the original overhead welding process is adjusted. The welding parameters are as follows:

 

Welding current 2400A; welding time 0.7s; lifting height 2.5mm; extension length 3mm.

 

According to the quality inspection and statistics of overhead welding of more than 10000 nut components, the first pass rate is 91-95%, among which the unqualified items are only appearance defects. After manual repair welding, the mechanical properties meet the standard requirements, which shows that the welding process is reasonable.

 

Chengdu star provides welding technology in the anchor pin welding of "160000 tons of carbon calcining kiln and rotary kiln" of jinal. Welding machines are purchased with new machines and leased with welding machines to comprehensively solve engineering construction problems.