Galvanized barrel welding process conditions Xin Qiaojuan Mr. Chen: Hello! Some of the process methods for welding galvanized sheets are briefly described as follows: When galvanized sheets are welded, the cracks are most likely to occur. These you have already encountered in production. The reason for the crack is that the zinc remaining in the nugget and diffusing into the heat-affected zone causes the joint to be embrittled and caused by stress. The method to prevent cracks is to correctly select the process parameters. Tests have shown that the smaller the penetration rate (10~26%), the less crack defects. When the seam welding speed is high, the heat dissipation conditions are poor, the surface is overheated, and the penetration depth is large, and cracks are likely to occur. Generally, under the conditions of ensuring the diameter of the nugget and the strength of the joint, a small current, a low welding speed and a strong external water cooling should be used as much as possible. 1. Theoretical welding conditions for seam welding of low carbon steel sheets and galvanized steel sheets 1. Welding conditions for low carbon steel seam welding Note: b is the contact surface width between the welding wheel and the steel plate, and B is the thickness of the welding wheel during the seam welding. 2. Welding conditions for seam welding of hot-dip galvanized steel sheets (15~20μm) In order to ensure the size of the nugget and the strength of the solder joint, the soldering time and the welding current can complement each other within a certain range. In order to obtain a certain strength of the solder joint, high current and short time (strong condition, also known as strong specification) can be used, and small current and long time (weak condition, also called weak specification) can be used. For example, for low-carbon steel sheets, which we usually call cold-rolled steel sheets, both strong and weak specifications can be used; but for hot-dip galvanized sheets, it is necessary to use weak seams in order to prevent or produce cracks as little as possible. specification. 2. Actual welding conditions for seam welding of low carbon steel sheets and galvanized steel sheets The above parameters are some of the data I have summarized in the production practice. Due to different equipment, different precisions of the same equipment will produce different results, which will be adjusted according to the specific conditions in production. We use two seam welders in normal production here. The process parameters of the two seam welders are different, and the difference is large. This is mainly caused by the difference between the precision of the two welders and the precision of the control box. Third, the conclusion Although the welding machine is different and the welding parameters are different, according to the production experience, in general, welding hot-dip galvanized steel sheets requires small current and long-term weak welding specifications. If the same current is used to weld cold-rolled steel sheets and hot-dip galvanized steel sheets of the same thickness, the electrode pressure of the welded hot-dip galvanized sheet should be correspondingly larger (cold plate is 2.5~2.8KN; hot-dip galvanized sheet should be It reaches 2.8~3.0KN). The welding speed of the hot-dip galvanized sheet should be 2/3~3/5 times of the cold plate. Therefore, for a fully automatic welding machine, welding cold plate barrels of 720 / hour, then welding hot-dip galvanized sheet can only reach 430 ~ 480 / hour, generally 450 / hour. Flat Washers,Washers,Spring Washers ,Non-Standard Nuts XINXING FASTENERS MANUFACTURE CO.,LTD , https://www.hex-bolts.com
Galvanized barrel welding process conditions
Plate thickness mm
Welding wheel size
Mm
Electrode pressure
KN
Edge width
Mm
High speed welding
Minimum b
Standard b
Maximum B
Minimum
standard
Minimum b
Standard b
Welding current (KA)
Welding speed cm/min
Welding time week
Rest week
0.6
4.2
5.9
12
2.2
2.8
8
11
13.5
270
2
2
0.8
4.7
6.5
13
2.5
3.3
9
12
15.5
260
3
2
1.0
5.1
7.1
14
2.8
4.0
10
13
18.0
250
3
3
1.2
5.4
7.7
14
3.0
4.7
11
14
19.0
240
4
3
1.6
6.0
8.8
16
3.6
6.0
12
16
21.0
230
5
4
Plate thickness (mm)
Welding wheel width (mm)
Electrode pressure (KN)
Time (week)
Welding current (KA)
Welding speed cm/min
welding
Rest
0.6
4.5
3.7
3
2
16
250
0.8
5.0
4.0
3
2
17
250
1.0
5.0
4.3
3
2
18
250
1.2
5.5
4.5
4
2
19
230
1.6
6.5
5.0
4
1
twenty one
200
We talked about the theoretical welding conditions for seam welding of cold-rolled steel sheets and hot-dip galvanized steel sheets. The following are some of the specific parameters we have in actual production for your reference. The seam welding machine we used is the equipment of Shanghai Electric Welder Factory. After the welding machine is modified, the steel barrel body is welded with a rim size of 4mm and the welding wheel width is 20mm. Since we use a semi-automatic welding machine, we have a little welding process, but The purpose of spot welding is to locate and is superfluous to the imported fully automatic welder. Here we mainly look at the seam welding parameters.
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Material manufacturer
Material thickness mm
Welding current KA
Electrode pressure KN
Welding speed cm/min
Front section
Middle section
Rear section
Wuxi Changjiang Iron and Steel Group
1.0 (Grade A)
12.7
15.5
15.0
2.4
340
Tianjin Cold Rolling Steel Plant
1.0 (Grade A)
12.5
16.5
15.0
2.6
330
Shanghai Baoshan Iron and Steel Group
1.0 (Grade B)
12.9
16.9
14.8
2.8
335
?
Wuxi Changjiang Iron and Steel Group
1.2 (Grade A)
13.0
15.9
15.2
2.5
351
Tianjin Cold Rolling Steel Plant
1.2 (Grade A)
12.9
17.0
14.5
2.8
355
Shanghai Baoshan Iron and Steel Group
1.2 (Grade B)
13.2
17.3
15.0
3.0
348
Note: The above parameters are the process parameters of seam welded cold rolled low carbon steel.
Panzhihua Iron and Steel Group
1.2 hot galvanizing
12.5
16.5
14.0
3.0
258
Wuhan Iron and Steel Group
1.2 hot galvanizing
13.2
16.2
14.2
3.0
260
Shanghai Baoshan Iron and Steel Group
1.2 hot galvanizing
13.6
17.3
13.8
3.0
258
Note: The thickness of the zinc layer of the hot-dip galvanized sheet is 175 g/cm2.
I don't know if your company's barrel production line is equipped with an edger, because I once said in the article "The method of seam welding of galvanized barrels". When welding galvanized sheets, it is necessary to polish the welded parts. The upper part is to remove the surface zinc layer. Due to the low melting point of zinc, a copper-zinc alloy is formed with the brazing wheel during welding, which increases the surface resistance of the welding wheel and further increases the heat dissipation. The adhesion is more serious; and the superheating of the surface layer further strengthens the diffusion of zinc into the heat-affected zone, expanding the chance of crack formation. These "galvanized barrel seam welding process methods" are described in detail, I will not talk about it here. If your company has an edger, it is best to polish both ends of the barrel material. We usually grind (polish) twice. We have tried it without grinding it, but it has more leakage and can reach about 20%. However, if you increase the electrode pressure and welding current, it may be solved, but further testing is required.