Discussion on the influence of raw steel plate on the quality of steel drum

Discussion on the influence of raw steel plate on the quality of steel drum

Xin Qiaojuan

With the rapid development of the commodity economy and the increasing living standards of the people, the role of product packaging is becoming more and more important. As an important metal packaging container, steel drums have become more and more widely used. In order to meet the requirements of steel drums for various product packaging, especially to meet the requirements for the quality of steel drums for dangerous goods, food, medicine, military and other products, it is necessary to improve the quality of steel drums to ensure that steel drums are packaged and in circulation. It can resist the damage of steel drums by the harmful factors in the external environment and various mechanical, climatic, biological, chemical and other environmental conditions, protect the quality of the contents, and reach the consumers in good condition. To improve the quality of steel drums, it must be taken from every process of producing steel drums. The quality of raw steel plates of steel drums is the primary factor affecting the quality of steel drums. Below we briefly analyze the impact of steel drum raw materials on the various processes of steel drum production.

The raw material steel plates used for the production of steel drums can be roughly divided into three types: one is ordinary carbon steel thin steel sheet (hot rolled thin steel sheet); the other is high quality carbon steel thin steel sheet (cold rolled thin steel sheet); the third is galvanized thin Steel plate. Although these three materials have many differences in their properties, their main chemical composition is consistent. The chemical elements that affect the performance of the steel sheet are mainly carbon C, sulfur S, phosphorus P, etc. Of course, these elements will also directly affect the quality of the steel drum. In addition, the factors affecting the quality of the steel drum are the surface quality of the steel plate, such as the flatness, uniformity, oil stain, rust, scale and so on. Below we analyze the impact of the above items on the quality of steel drums according to the production process of steel drums.

First, the impact on the processing of steel drum top cover

1. Blanking and pre-rolling of the drum lid.

1 The effect of carbon content on the shape of the lid. If the amount of carbon, sulfur and phosphorus is too high, the plasticity of the steel sheet will decrease, the hardness and brittleness will increase correspondingly, and the drawing performance will be lowered. When the lid is stamped, it will produce a size that has not been drawn to the process requirements, and the steel plate will be cracked at the rounded corner of the lid. Even if it is pulled to size without breaking, there are already microcracks. This is a potential factor affecting the quality of the steel drum. It may leak when it is transported or contained in the contents, as long as it falls or collides. Furthermore, due to the increased hardness, the resilience of the steel plate is enhanced, and it is easy to rebound after pre-rolling.

2 The influence of the surface quality of the steel plate on the forming of the lid. If the surface of the steel plate is uneven or uneven, the gap between the molds is constant during the press forming, and the steel plate enters the mold, which may cause burrs, tears, wavy flange edges and convexities due to different gap sizes. Ears and so on. Sometimes it is possible to get into the mold (because the gap is too small), damage the mold, and affect the normal production of the lid. Due to the unevenness of the surface of the steel sheet or the uneven thickness, there has been a problem in the blanking of the lid of the barrel. If it is flown into the next process, the lug is compacted due to the large amount of material when pre-crimping. The part with less lug is not necessarily rolled up. The quality of the steel drum is not guaranteed with such a lid.

2. Processing and forming of steel barrel mouth

The barrel form of the steel drum is divided into small open steel drums, medium open steel drums, straight open steel drums and open neck steel drums according to the type of steel drums. We only talk about the opening of small open steel drums and medium open steel drums.

1 small opening steel drum. The mouth of the small open steel drum is composed of an injection port and a vent. It is processed by pressing the coil on the lid of the barrel by mechanical engagement. Its processing steps are: punching and cuffing; second, the screw ring is locked. If the chemical composition of the material contains carbon and sulfur, the amount of phosphorus exceeds the standard, the punching performance of the material decreases. When the punching edge and the spiral ring are locked, the edge of the punching hole will be cracked, causing leakage of the barrel mouth; The surface of the steel plate is uneven or thin and uneven, and burrs are easily generated when punching. When the spiral ring is locked, the sealing is not strict due to uneven thickness, thereby causing leakage.

2 open steel drums. The middle open steel drum has only one barrel opening on the top of the barrel, and the barrel opening diameter is larger than 70 mm, but smaller than the top diameter of the barrel. The processing method of the barrel mouth is generally formed by punching and flanging, and then performing secondary cuffing. If the content of carbon, sulfur and phosphorus in the steel plate is too high, cracks will occur when the punching is turned over, and the crack will extend when the second flange is performed; if the surface of the steel plate is uneven or uneven, the gap is due to the gap. A burr is generated due to uneven size, and microcracks are liable to occur when flanging. These microcracks will increase when they are double-flanged.

Second, the impact on the barrel processing

There are many processes in the barrel processing. Below we analyze one by one:

1. The impact on the barrel blanking process. The barrel blanking is mainly the size required for the process of cutting the steel sheet under the action of shearing force. It requires the flat steel plate to be cut, no sag angle and curl angle, and accurate size.

1 If the carbon, sulfur and phosphorus content of the steel plate exceeds the standard, the plasticity of the material is lowered, and the collapse angle is easily formed during the shearing, and the barrel material with the collapse angle is easy to be rolled when fed to the edger in the next process. The barrel behind the roll corner is likely to cause waste and defective products in the subsequent processing steps;

2 If the surface is not flat, it is difficult to ensure the machining accuracy of the size when cutting.

2. The impact on the barrel grinding process. The edging of the barrel body is to feed the two sides of the cut barrel body by the conveyor chain into the edging machine equipped with the upper and lower grinding wheels, and sanding the upper and lower grinding wheels to eliminate the surface. The thickness of oil stains, scales and their out-of-tolerance parts is conducive to the welding of the next process.

1 If the amount of carbon, sulfur, and phosphorus in the steel sheet is too high, the hardness of the steel sheet increases, and the grinding force required for grinding increases, and the heat generated by the grinding increases. Due to the increase in grinding heat, burns (blue), oxidation, and bonding of sand (surface roughness) occur on the surface of the polished steel sheet. These are not conducive to barrel welding;

2 If the surface is uneven, the amount of grinding will be large when grinding, and the recessed area may not be ground. Therefore, oil stains, scales, and the like continue to exist, and when welding, defects such as surface burns are easily caused;

3 If the surface of the steel plate is oily, oxidized, etc., it is easy to produce soot and dust during grinding. It not only pollutes the environment, but also affects the health of employees.

3. The impact on the barrel rounding process. The barrel circle is a cylindrical barrel obtained by plastic deformation of the material under the action of the rounding machine after the edging. If the carbon content of the barrel steel plate is high, the plasticity will decrease, and the rebound amount will increase. Under the action of the same circular force, the barrel sheet material cannot reach the round shape of the process.

4. The effect on the spot welding and seam welding process of the barrel. The spot welding and seam welding process of the barrel body is to transfer the resistance heat and the electrode pressure to the barrel by the pair of electrodes, and then to be in a molten state, and then bonded together under the action of the electrode pressure.

1 If the amount of carbon, sulfur and phosphorus in the barrel sheet is high, the plastic deformation ability of the material decreases, the coefficient of linear expansion increases, and the plastic temperature zone becomes narrow. When welding, defects such as cracks and inclusions are prone to occur;

2 If there is scale on the surface, it is easy to make the electrode adhere to the surface of the plate during welding. During the heating and expansion of the barrel, deep craters may be formed. When the electrode is raised after welding, the weld may be torn due to adhesion. Affect the surface quality of the weldment;

3 If there is oil and impurities on the welding surface, when welding, pores and cracks will be generated, which will affect the airtightness of the welding. In addition, when oil and other impurities are welded, harmful gases and fumes are generated, which causes environmental pollution and endangers personal health.

5. The impact on the barrel flanging, pressing line and expansion process. For the process of flanging, pressing and expanding of the barrel, some barrel companies use one process; some enterprises use two processes; some enterprises also use three processes. Although the processing methods used by each company are different, the results are consistent. If the steel plate contains too much carbon, sulfur, and phosphorus, the plastic deformation ability of the material decreases and the toughness is poor. And its strength and hardness will increase, and the brittleness will also increase. Therefore, when the flange is turned, cracks appear on the edge of the flange, and some even have large cracks. Due to the increased hardness of the material, the rebound is severe, so the size after the flanging does not meet the process requirements; in the case of the pressing line and the expansion, due to the rebound problem, the small line and the barrel bar cannot be raised. In addition, since the material is brittle, it is easy to break or crack when it is pressed and expanded.

Third, the impact on the assembly process of steel drum

The assembly process of the steel drum is to assemble the processed barrel body, the top of the bucket and the cover by mechanical engagement. If the material used to process the steel drum contains too much carbon, sulfur, and phosphorus, the plasticity of the material is reduced, but the hardness and brittleness are improved. During the assembly of the steel drum, due to the gradual advancement of the forming roller, the bottom, the top and the barrel body are naturally bitten and wound together, and then pressed by two rollers to prevent leakage. However, as the hardness of the steel plate increases, the rebound amount increases, so that the formed steel drum is prone to rebound, which increases the curling gap, thereby causing leakage of the steel drum; in addition, since the material becomes brittle, in the roll During the process of the edge, cracks and fractures are prone to occur; if the surface of the steel plate is oily, rust, water or dust, a layer of sealant applied to the edge of the barrel during the sealing process cannot wet the entire edge of the barrel, and after curing There is no integral annular seal that will cause the steel drum to leak.

Fourth, the impact of steel drum coating process

The steel drum after processing is also painted. When painting, if the surface of the steel drum is oily, dusty or watery (not surface pretreated or surface pretreated but not cleaned), the surface of the coated steel drum will have exposed bottom, pitting, pinhole, Defects such as poor adhesion of paint film and peeling off of paint film; if the surface of steel drum is uneven, paint film blistering may occur on the surface of coated steel drum; if the surface of steel drum is oxide scale and rust, steel after coating In addition to forming pitting, the surface of the barrel is also very susceptible to rust. This is because the scale and rust on the surface of the steel drum form a micro-battery after it encounters water, thereby further corroding the surface of the steel drum.

Through the above analysis, we can understand that the quality of steel drum raw materials directly affects the quality of the steel drum itself. Therefore, in order to strengthen enterprise management and enhance the competitiveness of enterprises, steel drum enterprises are actively carrying out ISO9000 system certification. The ISO9000 standard has specific requirements for the entire production and operation process from the procurement of raw materials to the delivery of products. Therefore, in order to produce high-quality steel drums, it is necessary to pick up the raw materials for the production of steel drums.