Analysis of material and process problems affecting the quality of steel drums (2)

Second, the decoiling and sheet blanking process problems

The opening balance of sheets should be said to be the first level of production of steel barrels, and its impact is from beginning to end.

1, the material warping uneven

In the open-booking leveling, if the sheet material is not flat and warped, the result is the same as the raw material mentioned in the previous section, which will affect the subsequent process.

In general, the quality of raw material steel plate can be easily realized in this decoiling leveling process. For example, in the normal decoiling leveling, the equipment has been adjusted as usual, but the steel plate found in the production did not meet the leveling process requirements, and the plate has warpage phenomenon, which indicates that the material may have high hardness, high rigidity or thickness all. Therefore, when this happens, the material can be tested for some necessary immediately, and the material that is actually unqualified can be prevented from entering the production process in time.

2, barrel body size over tolerance

At present, many unrolling leveling processes are linked with blanking and are produced as a single process. The quality of the blanking process directly affects the quality of the downstream production process.

When the barrel blanking size is too bad, it can cause a variety of defective products. If the parallelogram material, the trapezoidal material, the width is too big or too small, the length is too big or too small, the influence of various situations on the downstream process is different.

Parallelogram material will lead to misalignment in seam welding, forming a trapezoidal notch after flanging, lack of flanging at the notch, and will result in insufficient curling material in the beading process, insufficient number of crimped layers, and hollow edge In other situations, it is inevitable that leaks will be caused.

The trapezoidal material may cause two kinds of results. One is that after the seam welding, there is a misalignment, which belongs to the same position and wrong side; the other is that the diameters of the two ends of the barrel after the seam welding are inconsistent. The effect of misalignment of the trapezoidal material on the subsequent process production is similar to that of the parallelogram material. The case of inconsistent diameters has a serious effect on the quality of the process. When the diameter is small, the top of the reel and the top of the bottom of the barrel are too tight, and it may be difficult to fit into place. As a result, there is a curling gap; when the diameter is large, the reel is sealed. The top of the barrel and the barrel flange are too loose and there will be curling gaps. Therefore, the direct influence of the trapezoidal material is the quality of the crimping process and it is easy to cause leakage.

Barrel material length and width of the excess, from the impact of the finished product size of the steel drum, the weight becomes waste, can not be put into the production of the next process. It causes barrel body shape size deviations mainly due to barrel height deviation and diameter deviation. If the barrel height deviation is too large, the waste will be caused by the strict positioning of the coil packaging and process equipment. When the height of the barrel is extremely high, the barrel body may be deformed due to the pressure of the assembly disk, and the barrel may appear at the bulge. The octagonal deformation zone causes unsatisfactory appearance; when the height of the barrel is extremely low, the assembly platen cannot be put in place, gaps appear in the assembly hem, and part of the burring material may be added to the barrel body material, so that the curling cannot be achieved. The number of layers required is extremely prone to leakage. The diameter of the barrel is too large. In the assembly, the clearance between the bottom of the barrel and the top of the barrel is too large. More voids may be formed in the curl. When the diameter is too small, the fitting may have an interference, which may cause the flange to crack, and the barrel may also appear. If the body is out of shape or does not fit properly, leakage and appearance quality problems will occur.

Third, the welding edge processing technology

The traditional welding edge treatment is a edging process. In recent years, there have been new processing methods. For example, the edge milling process, no matter how it is handled, its purpose is nothing more than two: First, remove the oil at the welding edge lap joint, Rust is not conducive to the welding of dirt; Second, reduce the thickness of the weld edge, so that the weld edge and other parts as much as possible to form the same thickness and strength.

The quality of the welding edge treatment process has a great impact on the final quality of the steel drum in the traditional barrel production and cannot be ignored. The general problems are mainly due to incomplete dirt treatment, excessive thickness, and welding edge burns.

1, welding edge processing is not clean

The welding edge is not clean, and the presence of rust or oil stains is extremely unfavorable to the seam welding process of the barrel body. Due to poor conductivity and increased resistance, the welding edge material burns and burns due to excessive heat. Impurities affect the weld seal and weld strength. Poor seam welding causes leakage more than this.

2, the thickness of the poor

When the material at the edge-welding section is too thick, the thickness at the weld seam after seam welding will also be thicker. It is generally required that the thickness of the weld be not more than 1.2 times the thickness of the single layer material itself. If it exceeds this value, it will be thicker.

Too thick weld seam, in the seam sealing process, the flanging material of this part is far beyond the normal range. If the crimping roller groove is set according to the normal material thickness, too much material in the seam welding can not be installed in the roller groove. The crimping quality problems such as convex nozzles occur; if the crimping roller groove is set according to the material thickness of the seam welding area, curling gaps will occur in other normal parts, resulting in a wide range of leakage, so the welding edge treatment is too thick to be directly Affect the quality of the drum seal.

When the welding edge treatment is too thin, that is, the thickness of the welding seam after welding is lower than the normal material thickness, the first effect is the weak strength at the seam welding position, which is easily broken during the expansion type process and flanging process, and is also a steel drum. The weakest part in use; In addition, during the crimping process, there will be gaps in the bead due to less material at the edge of the weld seam, which will cause leakage.

3, welding edge burn

After welding and adding impurities so that the resistance is too large, the material in the part will become brittle, cracking or cracking may occur during the flange-turning process, and the molding may be difficult to form due to brittleness during crimping. Leakage is also more common.

Fourth, barrel welding process problems

The traditional barrel welding process occupies the majority of the barreling enterprises in China. It is generally carried out by spot welding and seam welding. The automatic steel tank seam welder can directly seam weld. The main quality problems of welding are: positioning error, perforation, false welding, scorching and so on.

1, take over the positioning of the poor

Positioning overshoot is the oversize of the seam welding edge, that is, the edge is too wide, too narrow, and one side is narrow.

When the overlap is too wide, the diameter of the barrel will become smaller, which will cause difficulties in the subsequent process, and may cause cracks during the process of die edge-turning; the die will expand during the expansion process; the edge-sealing process With the bottom of the bucket with full interference, can not be in place, resulting in curling gap.

When the overhang is too narrow, the diameter of the barrel body will become larger. In the process of the die edge flanging, the size of the flanging may not meet the requirements, which may affect the lack of hemming material in the hemming process and the number of layers may not reach the standard or appear. Gap; In the process of expansion type, the height of the ribs will not meet the requirement. In the process of crimping the closure, the loosening of the ribs and the bottom of the bucket will produce a seam.

2, weld perforation

If there is a perforation in the seam welding position, the seam welding will directly produce leakage. This is a waste product of this process, and can only be repaired by means of repair welding or the like, and can only be treated as a defective product after repair. If the perforation is in the flanging area, the repair requirement is high, otherwise the subsequent process will be affected, and it will not be repaired.

3, seam welding false welding

Fake welding is most dangerous because it is sometimes difficult to find. Some false welds have leaks in the leak detection test, and some false welds do not leak at the time. However, when the steel drum is in use, it is easy to cause leakage through collisions. Because false welds are not welded or not completely welded, the weld strength is of course not*, and it is also prone to problems in subsequent processes, such as cracking when flanging, and cracking when bulging, which can be detected in time. However, if you leave the fake steel drums out of the factory, the hidden danger is quite serious.

4, the site of the burnt

The burning of the weld seam can cause the material in the weld to harden and become brittle. It is easy to crack at the stress concentration during the process of flaring and bulging of the back channel, and it is also hard and brittle during the seam sealing process. Difficult to form, in addition to the problem of cracks can also make the curling site difficult to repair the leakage problem.