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

Second, the sheet unwinding leveling and cutting process problems

The unwinding level of the sheet should be said to be the first level of steel barrel production, and its impact is from beginning to end.

1. Sheet warpage is uneven

In the unwinding leveling, if the sheet material is not flat, the warpage is uneven, and the result is the same as the raw material in the previous section, which will affect the subsequent process.

In general, the quality of the raw steel sheet can be easily understood in this unwinding process. For example, in the normal unwinding leveling, the equipment has been adjusted as usual, but the steel plate is not found to meet the leveling process requirements, and the sheet has warpage, which indicates that the material may have high hardness, rigidity or thickness. All. Therefore, when this happens, the material can be immediately tested for some necessary conditions, and the materials that are indeed unqualified can be prevented from entering the production process in time.

2, the size of the barrel body is out of tolerance

At present, many unwinding and leveling processes are connected with the blanking and are produced as one process. The quality of the blanking process directly affects the quality of the downstream production process.

When the size of the barrel is too large, it can cause various non-conforming products. For example, parallelograms, trapezoids, widths are too large or too small, lengths are too large or too small, and the effects of various conditions on the downstream process are different.

Parallel quadrilateral material will cause misalignment in the seam welding, and a trapezoidal gap will be formed after the flange is formed. The size of the flange at the gap is insufficient, which will result in insufficient curling material in the crimping process, insufficient number of crimping layers, and hollow edge. In other cases, it is inevitable that leakage will be rejected.

The trapezoidal material may cause two kinds of results. One is that the seam is misaligned after seam welding, which belongs to the same position. The other is that the diameters of the two ends of the barrel are inconsistent after seam welding. The effect of the offset of the trapezoidal material on the production of the subsequent process is similar to that of the parallelogram. However, the influence of the inconsistent diameter on the quality of the process is also serious. When the diameter is small, the tightness of the package is too tight with the top of the barrel, which may cause difficulty in fitting the position, so that the crimping gap occurs; when the diameter is large, the winding is in the middle. The top of the barrel is too loosely fitted with the flange of the barrel, and a curling gap is also generated. Therefore, the direct influence of the trapezoidal material is the quality of the crimping process, which is highly prone to leakage.

The difference in length and width of the barrel body affects the finished product size of the steel drum, and the waste becomes a waste product, which cannot be put into production in the subsequent process. It causes the deviation of the shape and size of the barrel body mainly including the barrel height deviation and the diameter deviation. When the height deviation of the barrel body is too large, it will cause waste in the case of strict positioning of the package and the process equipment. When the height of the barrel is too high, the barrel body may be deformed due to the pressure of the assembly disc, and the barrel may appear at the expansion point. The octagonal deformation zone causes the appearance to be unqualified; when the height of the barrel is extremely low, the assembly platen cannot be in place, and a gap occurs in the assembly curling edge, which may add part of the flange material to the barrel body material, thereby making the curling edge unreachable. The number of layers required is extremely prone to leakage. The diameter of the barrel body is too large, and the gap between the bottom of the barrel and the top of the barrel is too large in the assembly, and there may be more gaps in the curling edge; if the diameter is too small, the assembly may be over-filled, which may cause cracks in the flange, and may also appear in the barrel. Leakage and appearance quality problems will occur if the body is deformed or not fit.

Third, the welding edge treatment process problems

The traditional edge welding process is the edging process. In recent years, new process methods have emerged, such as milling edge technology. No matter how to deal with it, the purpose is nothing more than two: First, remove the oil from the weld edge joint, Rust and the like are 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 problem of the welding edge treatment process has a great influence on the final quality of the steel drum in the traditional barrel production, which is insignificant. Common problems mainly include incomplete treatment of dirt, excessive thickness, and burnt joints.

1, the welding edge is not clean

The welding edge is not clean, the presence of rust or oil, etc., is extremely unfavorable to the seam welding process of the barrel. Due to poor conductivity, the resistance increases, causing the welding edge material to burn and burn through due to excessive heat. Impurities affect its weld tightness and weld strength. The cause of leakage due to poor seam welding is mostly here.

2, thickness is too bad

When the material of the weld edge treatment is too thick, the thickness of the weld at the seam weld will be thicker. Generally, the thickness of the weld should not be greater than 1.2 times the thickness of the single-layer material itself. If it exceeds this value, it will be thicker.

Too thick welds, during the crimping process, the flanging material of this part is far beyond the normal range. If the crimping roll groove is set according to the normal material thickness, the material of the seam welding is too much to make the roll groove not fit. There is a curling quality problem such as a protruding nozzle; if the crimping roller groove is set according to the material thickness of the seam welded portion, the curling gap occurs in other normal portions, resulting in a wide range of leakage, so the welding edge treatment is too thick and will be directly Affect the quality of the sealing of the steel drum.

When the welding edge is too thin, that is, the thickness of the seam weld after welding is lower than the thickness of the normal material, the first effect is that the strength of the seam weld is weak, and it is easily broken during the expansion process and the 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 in the beading portion of the weld, resulting in leakage.

3, welding edge burns

If the welding edge is added with impurities, the resistance will be too large, and the material will become brittle. The cracking or cracking may occur during the flanging process. When crimping, it may be difficult to form due to brittleness. Leakage is also more common.

Fourth, the barrel welding process problem

The traditional barrel welding process accounts for the majority of the barrel making enterprises in China. Generally, spot welding is first performed and then seam welding is performed. The fully automatic steel barrel seam welder can directly perform seam welding. The main process quality problems of welding are: positioning over tolerance, perforation, false welding, charring, etc.

1, the edge positioning is out of tolerance

The positioning error is the difference in the size of the seam welding edge, that is, the edge is too wide, too narrow, one side wide and one side narrow.

When the edge is too wide, the diameter of the barrel will become smaller, which will cause difficulties in the subsequent process. Cracks may occur during the process of mold burring; the mold will also rupture during the bulging process; With the bottom cover of the bucket, it is fully engrossed and cannot be in place, resulting in a curling gap.

When the edge is too narrow, the diameter of the barrel will become larger. In the process of the mold flanging process, the size of the flange may not be met, which may affect the insufficient material of the crimping process and the number of layers may not reach the standard or appear. The gap; the height of the ribs in the bulging process will not meet the requirements; the lap seam sealing process will be too loose with the bottom of the barrel, and a curling gap will also occur.

2, weld seam perforation

When the seam welding part has perforation, the seam welding directly causes leakage. This is the waste of the process, and can only be repaired by means of repair welding, etc., and can only be treated as a defective product after repair. If the perforation is in the cuffed part, the repairing requirements are high, otherwise it will affect the subsequent process and cannot be repaired seriously.

3. False welding of seam welding parts

The situation of false welding is the most dangerous because it is sometimes difficult to find. Some fake welds have leaks in the leak test. Some false welds do not leak at the time, but when the steel drum is in use, it is easy to leak. Since the false welding is not welded or not completely welded, the welding strength is of course unreliable, and problems are easily caused in subsequent processes, such as cracking when flanging, and cracking when expanding, which can be found in time. However, if the steel barrel of the fake welding is left out, the hidden danger is quite serious.

4, the weld is burnt

The scorch of the weld bead can cause the material of the weld to be hardened and brittle, and it is easy to generate cracks in the stress concentration during the process of the flanging and expansion of the back channel, and it is also brittle and hard during the sealing process. It is difficult to form, and the problem of cracking can also cause leakage problems that are difficult to repair in the curled portion.