Causes and countermeasures of thin bucket bumps and dents
Text / Wang Ruibo
Recently, some users have reported that the steel drum with a thickness of 0.8mm is prone to dents after bumping. Is it related to the material of the steel plate? Which tests can be used to check the quality of the steel plate? For the user's questions, we can answer the following three aspects.
1. After the steel drum is thinned, the physical and mechanical properties of the material are reduced, which is easy to cause the dent after the bumping of the barrel.
The thinning of the steel drum makes the thickness of the steel drum material 1.0mm from the barrel of the original national standard GB/T 325-2000, 1.2mm at the top of the barrel, and thinner to 0.8mm of the current barrel and 1.0mm of the top of the barrel. This will reduce the physical and mechanical properties of the steel sheet by 20 to 30%, which inevitably causes dents after the steel barrel is bumped. However, we can strengthen the steel barrel strength (W ribs, wide corrugations, barrel bottom ring ribs, necking, etc.), laying rubber sheets at the production site, handling lightly during loading and unloading, and installing protective barrels during transportation to make steel The problem that the barrel is thinned and the dent is prone to be avoided.
Dent generated during production
Dent generated when the finished product is handled
Second, the material of the steel plate itself softens and easily causes the dent after the bumper
The physical and mechanical properties of the steel plate itself (such as: low carbon content, excessive annealing, low yield strength, low tensile strength, etc.) cause the material to "soften" and cannot meet the strength requirements of steel drum manufacturing. It is easy to have dents.
In the process of production and use of steel plates, if there is a “softening†phenomenon that cannot meet the quality performance requirements of steel drums, a qualified third party inspection may be entrusted as a basis for return or claim. This will ensure the quality of the steel plate and produce steel drums that meet the performance requirements.
Deformation at the burring during production
Negative pressure deformation during use of the finished product barrel
Third, the quality of the steel plate can be identified by the physical and chemical properties of the steel plate
In Q/SY 1200.3-2010 "Petrochemical product packaging specification Part 3: Lubricating oil, grease" (China National Petroleum Corporation corporate standards) "A.3.2 Materials" provisions, stipulates that "steel plate should comply with GB/T 912 , GB/T 2518, GB/T 11253 required for the manufacture of high-quality thin steel or hot-dip galvanized steel."
Steel plate material grades Q195 (Chinese standard GB11253), ST12 (German standard DIN1623), DC01 (EU standard EN10130, SPCC (Japanese standard JIS), are carbon structural steel cold-rolled steel sheets and steel strips (China). The delivery material grades indicate that SPCC, ST12, and DC01 should meet the physical and chemical performance indexes required by the material grade Q195 in the national standard GB11253-2007.
Fourth, improve the steel barrel structure, enhance the strength of the steel barrel
In order to enhance the strength of the steel barrel body and reduce the generation of dents, the original 6-way small corrugated structure design can be improved to 4 large corrugations. In order to verify the strength of the improved steel drum, a negative pressure comparison test was carried out on four large corrugations and the original six small corrugated steel drums. After vacuuming to -0.048 MPa, when four large corrugated steel drums were tapped by hand, pits with a diameter of about 130 mm were produced on the smooth surface between the two W ribs, and no pits were formed on the corrugated surface. After returning to normal pressure, The pits on the surface of the steel drum are automatically eliminated; 6 small corrugated steel drums are gently tapped by hand, and a concave surface having a diameter of about 230 mm is produced on the smooth surface between the two W bars, and the steel drum is severely deformed when the corrugated surface is struck.
4 large corrugated steel drum negative pressure test
6 small corrugated steel drum negative pressure test
The structural improvement of the four large corrugated steel drums makes the shape of the packaging steel drum more powerful, and has a visual impact effect, and also meets the requirements of the user for the packaging steel drum. Greatly improved the intrinsic quality and appearance of the packaging steel drum, making up for some defects of the original standard barrel shape.
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