Research on technical problems after steel barrel seam welding machine transformation
Xin Qiaojuan
Editor's note: Recently, there have been several units of colleagues calling to inquire about the steel barrel barrel seam welder after the transformation (with a width of 4mm). During the welding process, the ends of the barrel are often cracked or the welding is not firm. And so on. In view of the commonality of this issue, it is discussed here and I hope that it will be helpful to everyone.
In recent years, especially after joining the WTO. The expansion of foreign trade and the introduction of foreign advanced technology and equipment have enabled China's barrel industry to develop rapidly. For the seam welding of steel barrels, the FN-150-5 seam welder produced by Shanghai Electric Welder Factory has been used for decades. The welding is carried out with lap welding and the width of the lap is 12mm. Now, this phenomenon is gradually changing.
At the beginning of the reform and opening up, several barrel production lines and several automatic seam welders from the US Carando Company were introduced in China. When the imported seam welder welds the steel barrel, the width of the edge is only 2~3mm, after welding. Not only the appearance of the steel barrel is beautiful and beautiful, but also helps to ensure the quality of the steel drum, and also saves raw materials. Although this welder has so many benefits, it is very expensive. Most of the barrel companies can only be sighed. At this time, the people of insight in China are optimistic about this business opportunity, decided to develop and manufacture the welding electric control box, through technical transformation, so that most of the barrel seam welding machine can achieve the desire of seam welding 4mm without spending too much money. . Until recently, with the fierce competition in the market and the expansion of foreign trade. Our steel drums also carry goods across the sea, in order to close the gap with foreign counterparts, forcing us to improve our steel drum packaging process as soon as possible, the improvement of steel barrel welding process is one of them.
The following is a discussion of some practical problems that occur during the welding process of the steel seam in the seam welder.
1. When the barrel is seamed and welded, the ends of the barrel are cracked, and some even have a leak of 1OOmm long.
2. There is no damage to the flanges at both ends of the barrel, but the ring ribs are cracked after the expansion.
3. There are flying thorns after welding, which affects the appearance quality of the steel drum and the intrinsic quality of the fully open barrel.
The above three problems are problems that many barrel companies often encounter in production practice. To this end, we have conducted careful research on the basis of full practice.
First, the influence of welding process parameters on the quality of barrel seam welding
The welding principle of the steel barrel body is resistance welding. Welding is to melt the steel sheet by welding heat and then press it together. Welding heat Q = I2Rt, where: Q - generated heat; I - welding current; R - resistance between electrodes; t - energization time.
It can be seen from the formula that the factors affecting the welding quality of the barrel include the welding current, the resistance between the electrodes, and the energization time, and the resistance of the electrode is determined by the electrode pressure; the welding current has a direct relationship with the grid voltage; Determine the welding speed of the barrel. Therefore, under normal circumstances, the process parameters (see Table 1) that reflect the quality of the barrel weld are: welding current, electrode pressure, welding speed, welding time and rest time.
1. Welding current The source of heat required for seam welding to form a nugget is as described above, which is the heat generated by the current passing through the welding zone. Under the other conditions, the welding current determines the nugget penetration and the amount of overlap. When welding steel drums, the average penetration rate of the nugget is 30-70% of the thickness of the steel plate. 45 to 50% is the best. In order to obtain the hermetic weld seam nugget overlap should not be 15-20%.
When the welding current exceeds a certain value, continuing to increase the current can only increase the penetration rate and the amount of overlap of the nugget without increasing the joint strength, which is uneconomical. If the current is too large, defects such as excessive barrel indentation and burnt through the barrel weld will occur.
2, electrode pressure
The electrode pressure during the seam welding of the barrel has a significant effect on the total resistance R between the two electrodes. As the electrode pressure increases, R decreases significantly. At this time, although the welding current is slightly increased, it does not affect the reduction of the welding heat due to the decrease in R. Therefore, the welding strength always decreases as the electrode pressure increases. Increasing the electrode pressure, increasing the welding current or prolonging the welding time can compensate for the effect of the resistance reduction. Thereby keeping the welding strength constant. The use of such welding conditions is advantageous for improving the stability of the welding strength. If the electrode pressure is too small, it will cause splashing and will also reduce the welding strength. At the same time, the electrode pressure is too high, which will make the barrel body indentation too deep, and accelerate the deformation and loss of the welding roller (welding wheel). If the pressure is insufficient, the shrinkage hole is likely to occur, and the contact resistance is too large, so that the welding roller is burnt and the service life is shortened.
3, welding time and rest time
When the barrel is seam welded, the size of the nugget is mainly controlled by the welding time, and the amount of overlap is controlled by the cooling time. At lower welding speeds, the ratio of welding to rest time is 1.25:1 to 2:1, and satisfactory results are obtained. When the welding speed increases, the joint spacing increases. In order to obtain the same amount of welds, the ratio must be increased. For this reason, the ratio of welding to rest time should be 3:1 at higher welding speeds. Or higher.
4, welding speed
The welding speed of the barrel body has a direct relationship with the thickness and material of the barrel material. The welding parameters of the special steel plate produced by different manufacturers are different during welding. We will not list them here. In short, the welding speed determines the contact area between the welding wheel (welding wheel) of the barrel seam welder and the barrel body, and the contact time between the welding wheel and the heating part (the weld edge), when the welding speed increases In order to obtain sufficient heat, the welding current must be increased. Excessive welding speed will cause the surface of the barrel to burn out and the electrode to adhere. Therefore, even if the barrel seam welder has enough external cooling water, the welding speed should not be too large and should be limited.
Second, the influence of the mechanical part of the welder and the front of the barrel on the welding quality of the barrel
The first three phenomena are produced. In addition to the influence of the welding process parameters, the adjustment of the welding machine itself has a great relationship. Because in general, the electrode pressure and the welding speed are infrequently changed parameters when welding the barrel, and this parameter changes unless the material thickness of the welded barrel body changes greatly. When the material thickness of the welded barrel is 1.2 or 1.0, the electrode pressure and the welding speed may not be changed, and the welding quality of the barrel body is not affected. However, if the bucket holder is too high or too low, the electrode pressure during the barrel welding is directly changed. If the tray is too high, the electrode pressure is increased, and the welded barrel has a significant indentation. As we talked about earlier, as the electrode pressure increases, R decreases significantly. At this time, the welding heat generated by the welding will be reduced by the decrease of the electrode resistance R, and the welding strength will also decrease as the electrode pressure increases. Therefore, the leakage or burring is broken; if the bucket frame is too low, the electrode pressure is reduced, and the welded barrel body will produce a distinct peach plough, that is, the barrel weld is too high outside, not an arc. At this time, the electrode pressure decreases and R increases significantly. At this time, the welding heat generated by the welding will increase due to the increase of the electrode resistance R, which may cause burn-through or splashing, which may easily cause leakage or burring.
After checking the height of the complete barrel seam welding machine support rack, the level should be adjusted, and the parallelism of the pallet barrel should be adjusted with the spirit level to the level. If the height of the two ends is uneven, the welding strength of the welded end of the barrel may be different due to the difference in the electrode pressure, so that it leaks or ruptures.
Secondly, it is to check whether the seam welder head is normal, sometimes there will be a lower head swing or the upper head will cause the lubricating oil to dry due to poor long-term lubrication, so that the upper head cannot be moved down to the position required by the process. These are the main factors affecting the barrel welding, we have encountered in production
Third, check whether the air pressure is correct, and whether the air pipe or air valve has air leakage.
Fourth, check whether the size of the two sides of the barrel body spot welding is correct. If the process stipulates that the barrel side is 4mm, there should be no excessive error at both ends, otherwise it will cause leakage at one end of the barrel after welding.
Third, the easiest way to solve the problem
In the previous section, we theoretically analyzed the causes of leakage after the steel barrel body was welded. However, in general, except for equipment, most of them are human factors. Therefore, when solving the problem, first check the width of the body of the barrel. If the width of the barrel is suitable, the simplest method is to adjust the welding speed to the lowest, and weld it. For each barrel, increase the welding according to the welding current. The current is not until the current does not fly, and the welded barrel will not be full. At this point, if you want to increase the welding speed, you should increase the welding current accordingly, and the two are complementary. But because many operators are trying to speed up the work. The welding speed is increased blindly, and the welding specification of the control box is out of adjustment, thus causing leakage or cracking of the barrel after welding.
The table is a set of process parameters in the production of a barrel company, for reference only. Because of the accuracy of the welding machine, the modification method, the accuracy of the controller, the working environment during welding, the raw materials used, the proficiency of the operator, etc., the parameters of the barrel welding will be affected.
According to past practical experience, in the general production process, the welding speed and electrode pressure are infrequently changed. When the material variation range is small, they are a fixed value. However, the welding current can be a parameter that changes frequently. It not only changes with the thickness and material of the welding material, but also changes with the voltage of the grid.
Makeup Brush Travel Set,Custom Makeup Brushes,Oval Makeup Brush Set,7Pcs Brush Set
DONGGUAN YACAI COSMETICS CO.,LTD. , http://www.yacaicosmetic.com