Analysis on the current situation and development

2022-08-24
  • Detail

Analysis on the current situation and development trend of coil packaging technology

1 preface

coil packaging is an important protective measure for coil storage and transportation. The traditional steel coil packaging is manual operation. Poor packaging quality, low production efficiency and high labor intensity are the fatal weaknesses of this backward packaging technology. In particular, with the improvement of rolling speed, the capacity of the new cold rolling production line is in the megaton level, and the inefficient manual packaging can not meet the production requirements at all. Iron and steel enterprises in industrialized countries attach great importance to coil packaging, raise it to the height of "ensuring safe storage and transportation and improving product grade", develop complete coil packaging technology and equipment, and basically realize the automation of coil packaging. In China, because many steel enterprises did not have cold rolling plants before, they often ignored the last process of products - packaging in the new cold rolling project, mistakenly thinking that China's labor force is cheap. Jinan experimental machine factory looks forward to 2017, and it can only use manual packaging. This incorrect understanding leads to the low level of coil packaging technology in many cold rolling projects under construction in China. The design idea of "emphasizing the main and neglecting the auxiliary" sets a "bottleneck" for the formation of capacity after the project is put into operation

2 Effect of steel coil packaging on cold rolling production efficiency and product quality

the usual supply state of cold rolled sheet (including electrical steel plate, stainless steel plate, color plate and galvanized plate, etc.) is either the sheet cut according to a certain specification, or the rolled strip (collectively referred to as plate and strip). In recent years, due to the change of steel sales channels, the original mode of pressure detection end users who can finally complete C10, C15, C20, C25, C30, C35, C40, C45, C50, C55, C60, C65, C70, C75, C80, C85, C90, C95, c10019 grade concrete is changed from the mode of purchasing directly from the steel plant to the mode of purchasing through the steel market (steel distribution center). In this way, The plates required by users can be cut in the steel distribution center, and steel mills can meet most of the requirements as long as they provide steel coils. The direct benefit of this change is to reduce product specifications and improve production efficiency. It is because of the increase of strip that the steel coil packaging accounts for an increasing proportion of the whole steel packaging. Therefore, it is very important to study the impact of steel coil packaging on the production efficiency and product quality of cold rolling

according to the process flow of cold rolling production, packaging belongs to the last process of finishing workshop (or "post-treatment workshop"), and the most common is located behind the "rewinding and Slitting unit". If it is manual packaging, there is a packaging work area, and if it is mechanical packaging, there is a packaging unit. As we all know, the production of cold rolled sheet is a very fast and highly automated production process. Therefore, all the supporting equipment, whether the main machine or auxiliary machine, on the premise of ensuring quality, meeting the requirements of production speed has become the most important parameter of process design

taking the cold rolling project with an annual output of 1.3 million tons as an example, the speed calculation results meeting this production requirement are given

output 1.3 million T/year

annual pure working time 6600h (three shift continuous working system)

coil weight 3 - 15 T

average coil weight 5 T

number of circumferential strapping 3 ~ 5

number of eyelet strapping 4 ~ 6

production speed 1 523 minutes/roll

from the above calculation, the required steel coil packaging speed per hour shall not be less than 40 rolls. If mechanized packaging is adopted, 2 sets of packaging units (at present, the maximum production capacity of the packaging unit is 24 rolls/hour) can meet the beat requirements. For the fully automatic packaging unit, each unit only needs to be equipped with 2 ~ 3 workers per shift, a total of 4 ~ 6 workers; For semi-automatic packaging units, each unit is equipped with 7 ~ 8 workers per shift, a total of 14 ~ 16 workers

if manual packaging is adopted, the packaging time of each roll is calculated by 15 points, and at least 10 groups of packaging stations need to be set, with at least 4 workers for each shift, a total of 40 workers

simply looking at the above data, it seems that we can draw a conclusion that although manual packaging takes a long time, as long as more stations and more workers are set, the production pace requirements can also be met. This is one of the reasons why many domestic decision makers of cold rolling projects consider manual packaging. In fact, the calculation premise of the above data is problematic, because it is invalid to set 10 groups of packaging stations in the manual packaging area. The reason for the invalidity is that manual packaging requires the cooperation of the crown block in the workshop, and the crown block cannot hoist the steel coils at these 10 stations at the same time. Moreover, the crown block in the workshop is not designed for packaging needs. Therefore, it is certain that it is impossible for manual packaging to meet such production rhythm requirements without adding special hoisting equipment (one for each station)

in fact, as long as the manual packaging is completed with the help of the crown block in the workshop (even if there is only one station), the burden of the crown block will be increased, and logistics congestion will often occur, resulting in the steel coil after the production line can not be packaged in time and stay in the production area; The packaged finished roll cannot be warehoused and delivered in time. Therefore, the backward packaging technology of manual packaging will become the "bottleneck" that restricts the cold rolling enterprises from improving production efficiency

manual packaging not only affects production efficiency, but also affects packaging quality, thus affecting product quality

the main index to evaluate the quality of steel coil packaging is the binding force (locking force) of circumferential strapping and eyelet strapping. With the improvement of the uncoiling capacity of the end user, the finished coil weight flows through the check valve, 5 μ As the high-pressure oil filter and servo valve become larger and larger, the binding force of steel coil packaging is also required to be larger and larger. Under the condition that the tensile strength of the strapping belt is the same, the binding force is determined by the baling head. According to the data, the maximum locking force of the latch type pneumatic baler (including imported products) commonly used in China is about 6000 ~ 8000n, and the maximum locking force of the fully automatic baler used abroad is 17, 000 ~ 20, 000n. The locking force of the pneumatic baling head is originally small, and it is also affected by factors such as gas source pressure and workers' operation. Therefore, it is inevitable that the locking force of the manually packed strapping is insufficient, which makes the steel coil packaging loose, resulting in the occurrence of problems such as packaging damage and loose packaging during the lifting process. This is the most important reason why the quality of domestic steel coil packaging is generally lower than that of foreign countries

3 technical status and development trend of coil packaging

the coil packaging technology of iron and steel enterprises in foreign developed countries has been quite mature. Major well-known enterprises have very strict requirements for the packaging of finished steel coils, and have formulated enterprise standards, and this standard, like other know how, is the secret of the enterprise. Steel coil packaging in iron and steel enterprises in industrialized countries is generally completed by highly automated packaging units, requiring few workers. Workers only do some auxiliary work, such as putting on inner and outer corner guards, pasting paper, and changing binding belts

in the research and development of steel coil packaging technology and equipment, like other metallurgical equipment, industrial developed countries are far ahead of China. The most representative companies are: Signode, a subsidiary of Illinois company in the United States, titanpack in Germany, itipack in Italy, etc. these companies have their own emphasis, and their products also have their own characteristics

signode is famous for its full-automatic baler. It also produces full-automatic baling heads and packaging materials for the full-automatic baler, such as special strapping belts, metal corner guards, side guards, latches, etc. The maximum locking force of its fully automatic baling head is 20, 000n, which is the highest index among similar products

titanpack is a professional manufacturer of fully automatic baling heads. Its products have complete specifications and superior performance. Many baling heads used in packaging equipment in the world are provided by the company, with a maximum locking force of 17, 000n

itipack is a company specializing in the design and manufacture of various steel packaging machinery, which uses the full-automatic baling head produced by titanpack. In terms of steel coil packaging, the company's full-automatic baling machine is mainly used for baling "bare coils" (steel coils without external packaging materials)

with the increasing requirements of steel coil packaging for locking force, the binding form of binding joint is also constantly improved. At present, there are three commonly used joint forms:

1) buckle type: the binding joint is combined with an iron buckle, which is mainly used for manual binding and full-automatic binding machine, with a binding force of 6000N

2) buckle free type: combine the strapping joints through stamping deformation (punching die buckle), which can be used for manual balers, with a combined force of 14000n

3) welding type: connect the strapping joints by spot welding, which is mainly used for automatic balers, with a bonding force of 20000n; It has become the development trend of steel coil packaging technology to adopt the form of button free or welded joints and a high degree of automation of the packaging unit

coil packaging in China started relatively late, and it has only been more than ten years since the first coil packaging unit introduced by Baosteel Phase II project was put into use. Although China's steel output has leapt to the first in the world, more than 200million tons/year, the proportion of cold-rolled sheet, especially high-quality sheet with high added value (automobile sheet, color sheet and electrical steel sheet, etc.) has been relatively low, and most of the new cold-rolled sheet production lines will be put into production by the end of the tenth five year plan, so the development of coil packaging technology and equipment in China has been relatively slow over the years. Among many iron and steel enterprises, only a few coil packaging units have been put into use, including two imported units from Baosteel; Two sets of silicon steel plants and one set of domestic units in the cold rolling plant of WISCO; Angang New Cold Rolling Plant 1 set of imported unit. It is understood that there will be about 10 coil packaging units under construction. It can be seen that the current situation of steel coil packaging technology in China's iron and steel enterprises is: the degree of mechanization is low, and all automatic Baling Equipment rely on imports

at present, the standard for coil packaging in China's iron and steel enterprises is "general provisions for inspection, packaging, marking and quality certificate of steel plates and strips" (GB/t247 - 1997). Because this standard is "General Provisions", it has no specific technical indicators and is not mandatory. The lack of advanced technical standards is also one of the important reasons for the backwardness of coil packaging technology in China

in recent years, the decision makers of China's iron and steel enterprises began to realize the importance of coil packaging to ensure safe storage and transportation, improve production efficiency and improve product grade through exchanges with foreign iron and steel enterprises. More and more enterprises have built the packaging unit as an important auxiliary process equipment in the new cold rolling production line, and the automation of the equipment has also been significantly improved

4 conclusion

high quality products should not only have first-class quality, but also have first-class packaging. First class packaging comes from first-class packaging technology and equipment. The backward packaging technology is not only inefficient, but also the packaging quality is difficult to meet the requirements of transportation and storage, and the appearance quality is even more unsatisfactory. In order to improve the quality of cold-rolled coil packaging in China and make it reach the international advanced level, advanced and automated packaging technology and equipment will be the inevitable choice for China's "self-made toys and teaching aids" steel enterprises

information source: Steel Information Alliance

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