Analysis of Quality Issues in Drum Delta (4)

Seven, the impact of seam welding quality (three) - off welding

For the solution of the problem of the above-mentioned weld bulge, some manufacturers use the method of seam welding less than the head, and as a result, the deficiencies in the desoldering of the weld seam less than the head are generated. As shown in Fig.14, it is a schematic view of the weld seam where the seam is less than the weld seam.

The seam profile of the seam that is less than the first seam is similar to that shown in Figure 9-2. A double edge appears at the bead of the barrel. So there was leakage and sometimes a direct leak. In the actual operation of seam welding, the wheel is lifted when the barrel has not yet finished. This is caused by the interruption of soldering. Therefore, to solve this problem is not difficult, as long as the operator pays more attention, that is, as far as possible when the weld seam reaches the end of the barrel, then leave the weld wheel. Of course, using a fully automatic welding machine does not have this problem.

VIII. Effect of Seam Weld Quality (4) - Embrittlement of Welds

In mass production, where the raw materials are good, flanging cracks sometimes occur, and some cracks follow the direction of the weld. There is a vertical weld seam in the direction of the production crack. The results after crimping are similar to those in Figs. 1 and 10-2. This quality problem is also generally influenced by the quality of seam welding.

There are generally four reasons for weld brittle fracture:

(1) The power-on time is too long, the overheating occurs, and the grain boundaries melt. The improvement measures are: adjusting the specification parameters;

(2) Insufficient electrode pressure or pressure increase is not timely. The pressure of the welding machine should be checked and repaired;

(3) The energization time is short, the cooling rate is too large, and there is a quench crack. Select the appropriate welding cycle form;

(4) Poor surface cleaning or splashing. Barrel surface cleaning should be strengthened.

According to the survey, many domestic manufacturers of semi-automatic seam welding machine are used outside the cooling method is the cooling method, some internal and external full jaw type, and some internal cooling type, for the internal cooling welding method, due to cooling water circulating inside the welding wheel, so generally No excessive cooling will occur. The use of external cooling welding. It is easy to produce excessive quenching cracks. This is the main reason for the embrittlement of the weld.

For quenching cracks. The welding outside cooling method should be cancelled. Strengthen the cooling water flow rate and flow rate of the internal cooling to meet the cooling requirements and avoid quenching of the weld seam.

Nine, the impact of quality seal - the tongue and squeeze

As shown in Fig. 15, triangular tongues often appear in the steel drum bead. The occurrence of this condition, in addition to the effect of having a thick weld seam, the crimp quality also has a great influence on it. The size of the groove shape of the hemming roller is designed according to the thickness of the steel plate and the number and shape of the hemming layers. In general, it is calculated as a seven-layer circular curl. Roller groove depth and groove width. It must be guaranteed that seven layers of material can be rolled. If the roller groove is too large, the curl must be loose and not compact. If the curling size is too large, it may cause the full circle to leak. When the roller groove size is too small, the seven-layer curling material can not fit in the groove. Spills, spills appeared on the tongue.

Due to the thicker material of the weld in the triangle area. 1.2-1.5 times the thickness of raw materials. If the roll groove is slightly smaller outside the triangular area, there will be excess iron tongues in the curl of the triangle area. The iron tongue phenomenon not only affects the aesthetic appearance of the steel drum. The hem is also often squeezed and leak quality problems occur, as shown in Fig. 16 as squeezing.

In order to prevent the occurrence of iron tongues, the size of the rolling groove of the hemming roller must take into account the curling thickness of the normal material and the thickness of the hemming of the triangle area; it is necessary to prevent the curling of the triangle area from causing the appearance of iron tongues and crushing. To make the curl outside the triangle not too loose and leaking. On the other hand, the solution to this problem is also to reduce the weld thickness.

X. Remedial measures for seepage in the triangular zone

There are many situations affecting the quality of steel triangles, but the most common ones are the above nine. Others have analyzed this one by one in this paper. For steel drums that have already caused leakage in the triangle, they have been improved to reduce losses. The pass rate generally has the following solutions.

(A), once again with the scroll wheel

Regardless of the number of causes of leakage, but since leakage has already occurred, most of the reasons for this are gaps (not including crimping), so lower the lowest point of the roller. Or press the platen a little tighter. Or change the wheel with a smaller roller groove, and then place the leaking steel drum on the coil packaging machine and roll it again* to make the curling tighter. Experience tells us that under normal circumstances, there is 50% of the leaking barrel. Can achieve no leakage.

(b) Using solder tin

In order to allow the leaked steel drums to enter the ranks of qualified products, it is ideal to use tin brazing to make up the leakage. It is not only difficult to repair but also not deformed around the repair welding site.

(c) Patching with trapping glue

In recent years, there have been many new types of trapping rubber that can be used to repair steel drums, but it is prudent to be careful. Some trapping glue is not resistant to high temperatures. The baking in the far-infrared paint drying oven melts and flows away, and some are not resistant to corrosion, and leakage may occur when certain chemical products are contained.

(four) gas welding trap

Gas welding trapping is the use of more traditional methods, trapping effect is better. Generally, leakage will not occur after mending leakage. However, due to the large heat-affected zone of gas welding, it is easy to cause large-area deformation and make up, which affects the appearance quality and generally can only be sold at a reduced price.

(E) TIG welding leakage

At present, many companies have started using argon-arc welding to compensate for leakage. The effect is very good. After repair welding, the steel drum can be completely sold as a genuine product. The quality of its sealing and the quality of its appearance are not different from those of a qualified steel drum.