Primetals Technologies’ stainless lines feature integrated rolling and processing, using additional lateral support rolls to ensure stable and controllable rolling, cleaning sections that ensure strip cleanliness prior to the annealing furnace and annealing and pickling sections using a tunnel type furnace and acid pickling.
Annealing and Pickling Section
The work-hardened strip requires annealing and surface scale removal. This is achieved with a tunnel type furnace and chemical pickling section. For hot band, Primetals Technologies also provides shot blast and scale breaker equipment between the furnace and pickle section to help with oxide removal.
- Annealing section with first stage, unfired pre-heat, for increased efficiency
- Air and water cooling
- Electrolytic and mixed acid pickling with additional brush scrubbers
- High-turbulence line tanks
- Brush and spray rinsing
- High-efficiency and low-NOx burners
- Maintained strip shape
- High maximum process speed
- Optimum pickling
Integrated Rolling and Processing
Primetals Technologies direct-rolling, annealing and pickling lines combine the traditionally separate processes of rolling, annealing and pickling, skin passing, and leveling into one integrated processing line.
- Annealing and pickling line
- Skin-pass mill and tension leveller
- Reduced yield loss due to less coil handling
- No leader strips required for cold rolling; no coil preparation line required
- Welds can be rolled for certain strip grades, further minimizing losses
- Reduced lead time from order to final product
- Less work in progress, lower inventory costs
- Operating cost savings from reduced labor and utility consumption
A key element of the integrated process is the in-line rolling mill. The 18 roll stand concept, recently redeveloped by Primetals Technologies to create the POWER X-HI mill, includes a number of unique features specially designed for these applications. Due to the high work-hardening characteristics of stainless steel, small work rolls are required to achieve the necessary reduction.
The technology uses additional lateral support rolls to ensure stable and controllable rolling. Lateral shifting of intermediate rolls and positive and negative bending of the intermediate rolls allows for shape correction. The mill is equipped with an automatic roll change car for work rolls and intermediate rolls enabling roll replacement while the
process section is operated.
- Multistand tandem six-high mill or eighteen-high mill with intermediate roll bending and shifting
- Hydraulic automatic gauge control at all stands
- Primetals Technologies patented quick roll change system
- Roll and strip lubrication and cooling via high-capacity mineral oil recirculation
- Accurate shape control
- Work rolls and intermediate rolls can be changed while process section is at full speed
Strip surface quality is an essential property of stainless flat products. Strip cleanliness prior to the annealing furnace is therefore essential. Primetals Technologies has designed an in-line degreasing section that ensures the highest product quality.
- A combination of spray, immersion and brush technologies
- Full „cleaning solution“ not merely a cleaning section
- Maximized operating efficiency
- Flexible and automatic set-up parameters to match product requirements
- Optimization of utility consumption
- Waste reduction
Primetals Technologies has vast experience in upgrading and modernization of processing lines. With a systematic approach, we work closely with our customers to develop a tailored modernization concept based on their individual needs taking all boundary conditions fully into account. The solution may be purely electrical, automated, mechanical or a combination. Based on the selected concept, the modernization can be carried out in several steps or during a plant shutdown. Primetals Technologies’ experience minimizes downtimes and ensures a fast start-up and top quality.
Fig.1- Tension reel and associate equipment
Fig.2- Entry section equipment
Fig.3- Direct Rolling and Annealing Line, LISCO, China
Primetals Technologies introduces its most advanced heavy-gauge laser welder performing welding and cutting using asolid laser source. This laser welder called LW21 is designed to provide a very high performance level for a wide range of grades including the stainless steel grades. Easy and low maintenance thanks to beam transmission via fiber optic cable making the troublesoom mirror reflected transmission are past history. Repeatable and constant cutting performance and high level of availability are achieved thanks to the choice of laser cutting. The other advantage of the latter is the compactness of the machine which enables an easy installation in existing lines with minimum field work.
In most cases the equipment comprises two-high mills with one work roll diameter. The equipment integrates positive and negative bending blocks, an automatic pass-line adjustment device, a quick automatic work roll change system, efﬁcient roll cleaning tools and high-performance automation.
Tension leveling stands include several six-high leveling cluster assemblies on which the strip is subjected to elasto-plastic deformation under controlled elongation to stretch the strip’s longitudinal structures to equal length and to eliminate residual crossbow and coilset. Tension leveler entry and exit tension bridles can be driven with different systems depending on application. It is often desirable to combine the skin-pass and tension leveler with an intermediate tension bridle in a versatile system to facilitate the production of different types of high-quality strip.
The scale breaker is composed of a stand, a dust collection system (wet or dry process) and entry and exit tension bridles with their respective drive systems. The strip in the stand is subjected to a series of alternating ﬂexions under tension on the work rolls. This results in an elongation of the strip and corrects ﬂatness defects. The scale breaker is also equipped with a quick work roll changing device which operates when the line is running, as well as a complete hooding of the stand to prevent pollution to the surroundings, and back-up rolls with built-in air blowing systems to prevent dust penetration.
Primetals Technologies innovative side trimmers dedicated to stainless steel applications are called ST21M or ST21H. Coming in turret or single head type, these machines can also feature several options, such as the Dynamic Width Adjustment (DWA) and/or the EdgeMon system. Our single-stand or turret or dual shifting scrap choppers SC21 are designed and manufactured to ensure the highest quality cutting and strongest availability. The pertinent choice of drum diameter and number of knives ensures the longest running time available in the market. Close association of side trimmer and SC21 scrap chopper is a guarantee for a best scrap disposal and lowest cobble ratio.
In the high-added-value stainless steel market, the SIAS automated surface inspection system is a key component of global equipment, essential to high quality and productivity. SIAS® can be applied to bright annealing lines and annealing and pickling lines as well as integrated stainless steel lines, skin-pass mills and tension levellers. SIAS® will alarm operators about all surface defects (harmful defects for the lines and/or unacceptable defects for required quality).
The TCOptimizer offers the means to secure the production by keeping an eye on all the signals of the whole metallurgical route (from casting to downstream process) and triggering just-in-time alarms against performance degradation regarding equipment conditions, process and product quality. It enable an automatic process follow up, a direct product quality estimation thanks to embedded metallurgical models and just in time alarms for immediate actions to reach final quality requirements.
Fig.1- Inline Skin Pass Mill
Fig.2- Medium tension leveler TL21M (wet process)
Fig.3 Scale breaker (Wet process)
Plant productivity and product quality are substantially depending on the quality of plant automation, process control, and available process optimization functions. To get the best performance out of a plant, Primetals Technologies provides add-on specific optimization solutions for further improvement of production efficiency and strip quality, besides standardized high performance automation system.
Throughput maximization with:
- OGO / Off Gauge Optimization for integrated rolling process
- SOS / Speed Optimization System for throughput optimization
- FRC / Flying Roll Change Stand during rolling
Excellent Strip quality with:
Baosteel Desheng, Fujian, China
Direct Rolling Annealing and Pickling Line
A 4 stand patented POWER X-HI tandem cold mill coupled with an annealing and pickling line including a skin pass mill. Two lines in one to decrease the operational cost and to produce top quality products.