Chinese steel barrel industry manufacturing technology has experienced a revolution in the past decade or more. The sign is that the extensive application of triple-height round-rolling technology has led to a significant increase in the sealing strength of steel drums. Since "sealing strength" is the first of many technical performances of steel drums, triple-layer and seven-layer round crimps have to become the core technology of steel drum manufacturing. In the mid-1980s, faced with the serious threat of shipping major accidents caused by the leakage of steel drum packaging, the international IMO standard “International Maritime Dangerous Goods Transport Regulations†made the 20th revision to improve the drum sealing performance requirements. Advanced technology countries such as Germany and the United States have eliminated traditional double-five-layer steel barrel production processes and instead developed new three- and seven-layer circular crimp manufacturing technologies. The advent of this technology will increase the sealing strength of steel drums from Levels 3 and 4 of the International Code for the Transport of Dangerous Goods at Sea to Levels I and II, effectively reducing maritime safety accidents and influencing them. The wave of steel drum production technology revolution quickly spread to China's steel barrel manufacturing industry, triggering a qualitative leap in the nationwide production of double- and five-layer flat-rolled steel barrels for triple- and seven-layer round-rolling.
The three-fold seven-layer circular crimping technology reflected in the steel drum manufacturing process equipment changes as shown in the following table:
project
Two-fold and five-layer curling
Triple 7-layer round curl
Bottom cover pre-rolling machine
Bottom cover without pre-rolling process, no pre-rolling machine
Bottom cover with pre-rolling process, pre-roll (and glue sprayer)
Barrel forming machine
Bucket width is small
Large barrel fold width
Bottom cover composite die
Bottom cover blank size and fold width is small
Bottom cover blanking size and hemmed width
Crimping machine
Hemming wheel groove cross section is rectangular
Hemming wheel groove curve is round, involute or spiral
Steel drum
The steel drum has a double-sided five-story section (Figure 1)
The steel barrel cross-section is three-fold seven-layer circular (Figure 2)
The revision of China's national steel barrel standards reflects this technological progress. China's "steel drum" standard has four editions of "GB325-1964", "GB325-1984", "GB325-1991" and "GB/T325-2000". The "GB325-1991" version of the 1991 edition has been included in the structure of three-fold and seven-layer round curls. The tests for the seal strength of steel drums, including gas-tight test, hydraulic test, drop test, and stacking test, are completely equivalent to " International Maritime Dangerous Goods Regulations.
The steel barrel standards of the former Soviet Union “ГOCT†and “ГOCT 5044-1979†only included the structural form of a double-five flat-rolled edge and was not included in the structural form of a triple-seven-layered circular crimp; The test of seal strength was only included in the drop test, and the maximum drop test required by it was 1.2 meters, which was lower than the requirement of 1.8 meters of the International Maritime Dangerous Goods Transportation Regulations. Therefore, according to the Chinese steel drum standard "GB325-1991" or "GB/T325-2000" produced steel drums, the sealing strength will be higher.
The central technology for steel drum manufacturing:
Round seaming with three-fold & seven-layer
XI'AN MACHINERY RESEARCH INSTITUTE Jing zhiping The industrial technology for steel drum manufacturing in China experienced a revolution during recent more than ten years. Its marking is extensive applications of the round seaming with three-fold & seven-layer causes huge increase of sealing intensity For the steel drum. Because the "sealing intensity" is premier one of many technical function for steel drum, as a result the round seaming with three-fold & seven-layer becomes the central technology for steel drum manufacturing. During the middle period of 80's Of 20 centuries, in the face of serious threaten from leaking of the steel drum-packing causing again and again fearful accidents in sea transportation, international IMO standard“The international maritime gauge rule for dangerous goodsâ€was made with the 20th time of revises. It increased the request about sealing function of steel drums. Many countries have advanced technology for steel drum manufacturing such as Germany , America etc. eliminated in succession traditional production technology about the flat seaming with two-fold & five-layer, turned step to develop new technique: the round seaming with three-fold & seven-layer. The creation of this technique increased grade of Conditioning intensity for steel drums from third or four class to first or second class, prescribed by “The international maritime conveyance rule for dangerous goodsâ€, reduced the safe trouble in sea transportation effectively, and affect in the world is not trivial matter. This tidal Wave about technical revolution for steel drum production spread to Chinese steel drum manufacturing industry very quickly, caused nationally changing from the flat seaming with two-fold & five-layer to the round seaming with three-fold & seven-layer, produced the leaps of Technical quality for steel drums production.
The alteration of crafts and equip for the round seaming with three-fold & seven-layer is shown as watch below:
Item
Flat seaming with
Two-fold & five-layer
Round seaming with
Three-fold & seven-layer
Pre-curling
Machine
No pre-curling working procedure,
No pre-curling machine
Have pre-curling working procedure, have pre-curling(and gum-spraying) machine
Drum-body
Forming machine
Width of flanging for
Drum-body is less
Width of flanging for
Drum-body is big
Pressing die for caps & bottoms
Size of material cutting and width of flanging for caps & bottoms is less
Size of material cutting and width of flanging for caps & bottoms is big
Seaming machine
Section of trough form for seaming wheel is rectangle
Section curve of trough form for seaming wheel is rotundity, involute or spirality
Steel drum
Section of seaming for steel drum is rectangle with two-fold & five-layer
(chart 1)
Section of seaming for steel drum is rotundity with three-fold & seven-layer
(chart 2)
The Chinese national standard for steel drums is revised time after time, incarnating this technique progresses. The Chinese national standard "Steel drums" has four editions: "GB325-1964", "GB325-1984", "GB325-1991" and "GB /T325-2000》. Among them in the "GB325-1991" published in 1991 year, the structure of round seaming with three-fold and seven-layer was already listed in it. And in the "GB325-1991" the tested numerical Value such as the gas-sealing test, the hydraulic pressure test, the falling test and the piling up test, is equal completely to the prescript of《The international maritime gauger for dangerous goods》.
In the national standard for steel drums of former Soviet Union "ГOCT" and "ГOCT 5044-1979" was listed only in the structure of the flat seaming with two-fold & five-layer but no the the seaming with three- Fold & seven-layer, and in it was listed only the falling test for the drums testing of sealing intensity, but the requested falling test max. height is 1.2 m, it is lower than 1.8m that prescribed in "The international maritime dispenser rule For dangerous goods". As a result, if the steel drums produced according to Chinese national steel drum standard《GB325-1991》or《GB/T325-2000》, their sealing intensity will be higher.