مقدمة
ال six‑high cold rolling mill flatness control technology largely determines the final quality of cold‑rolled strip steel. بجانب, cold‑rolled strip serves many core industries such as automobile manufacturing, home appliances and chemical production. Today’s market sets stricter requirements for strip thickness and flatness. لذلك, engineers focus heavily on flatness adjustment and uniform inter‑roll contact pressure. This article analyzes an innovative roll profile configuration for the six‑high mill. بالإضافة إلى, it applies 3D finite‑element simulation to reveal links between strip flatness parameters and inter‑roll pressure. It delivers practical technical support for cold‑rolling process upgrading.
1. Mainstream Six‑High Cold Rolling Mill Types & Research Background
في الوقت الحالي, domestic continuous cold rolling lines mainly adopt two typical six‑high mill series. One is the Continuously Variable Crown (رمز التحقق من البطاقة) type. The other is the Universal Crown Mill (UCM) type. The CVC mill relies on axial shifting of intermediate rolls with special profiles to realize flatness control. في أثناء, the UCM mill moves intermediate rolls on one side. This action eliminates harmful contact zones and improves bending‑roll adjustment capacity.
علاوة على ذلك, the UCMW mill supports both intermediate‑roll and work‑roll shifting. It delivers better flatness performance, especially for edge‑drop control of silicon steel and other special strips. لهذا السبب, it becomes a hot research subject in recent years.
Past studies on UCMW mills mostly cover strip crown, edge drop and inter‑roll pressure analysis. Many research teams optimize end‑section roll profiles and improve pressure uniformity. One new patent puts forward a combined roll setup: variable‑contact backup rolls, single‑taper intermediate rolls and single‑taper work rolls. This paper carries out deep analysis based on this patented solution.
2. Build Finite‑Element Model for Six‑High Cold Rolling Mill Roll System
Researchers use Abaqus software to build a 3D integrated simulation model. The model couples roll‑system elastic deformation and strip plastic deformation. Every parameter and simplification follows real‑world production conditions closely.
2.1 Innovative Roll Profile Design with Unified Trigonometric Functions
لفات احتياطية, intermediate rolls and work rolls all adopt trigonometric‑form curves. This method unifies roll‑profile design and improves coordination among all rolls.
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Backup roll: It uses symmetric profiles stacked by basic curve, variable‑contact curve and chamfer curve. It evens inter‑roll pressure and maintains stable flatness performance over long service cycles.
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Intermediate roll: It applies an asymmetric profile mixed with basic curve and flatness‑control curve. It strengthens adjustment effects particularly for strip crown.
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Work roll: It carries asymmetric profiles made of basic curve plus edge‑drop control curve. It acts directly on strip edges and greatly boosts edge‑drop control results.
2.2 Key Parameters and Model Simplification
Simulation parameters copy actual operating data. The strip measures 1200 mm in width and 2.4 mm in thickness and uses elastic‑plastic material properties. Rolls follow elastic‑body assumptions to calculate elastic bending and elastic flattening. The total rolling force equals 13000 kN. Bending‑roll force ranges from 0 kN to 300 kN for both work rolls and intermediate rolls.
فضلاً عن ذلك, developers take advantage of geometric symmetry. They only simulate half of the full roll set. This setup balances computing speed and calculation accuracy. Engineers apply varied meshing: sparse meshes for central roll‑barrel zones and dense meshes for contact regions. Dense meshes guarantee reliable output for critical contact areas.
Teams also define clear shifting reference positions. Sw = 0 means strip edges align with starting points of work‑roll edge‑drop curves. Si = 0 means strip edges match starting points of intermediate‑roll flatness curves. Negative‑shift status happens when strip sections enter these control curves. Positive‑shift status occurs under opposite conditions.
3. Strip Flatness Analysis: Precise Adjustment for Crown and Edge Drop
Crown and edge drop represent core flatness indicators. This research applies C₄₀ for crown calculation and E₁₀₀ for edge‑drop calculation. It quantifies influences caused by work‑roll shifting, intermediate‑roll shifting and bending‑roll force.
3.1 Work‑roll Shifting: Core Measure for Edge‑drop Control
Work‑roll shifting creates obvious non‑linear impacts on strip flatness. Positive work‑roll shifting increases both strip crown and edge drop. At +80 mm shift value, crown rises by 7.7 % and edge‑drop value grows by 25.6 %. على العكس تماما, negative shifting brings roll‑end profiles into strip‑edge zones. It restrains crown and edge‑drop defects effectively. At ‑80 mm shift value, crown drops by 88.5 % and edge‑drop value falls by 91.2 %. لهذا السبب, negative work‑roll shifting serves as the primary method to realize fine edge‑drop control.
3.2 Intermediate‑roll Shifting: Supplementary Tool for Crown Adjustment
Intermediate‑roll shifting shares similar changing trends but focuses on different targets. Positive intermediate‑roll shifting enlarges crown and edge‑drop values. At +40 mm shift value, crown increases by 20.4 % and edge‑drop value rises by 13.4 %. Its profile mainly affects the strip central zone. Thus it produces stronger crown adjustment yet weaker edge‑drop adjustment compared with work rolls.
When intermediate‑rolls shift to ‑40 mm, crown decreases by 40.7 % and edge‑drop value decreases by 12.1 %. Operators can combine intermediate‑roll negative shifting with work‑roll shifting. This joint strategy optimizes crown and edge‑drop performance together.
3.3 Bending‑roll Force: Differentiated Flatness Adjustment Capacity
Bending‑roll force delivers auxiliary flatness control. لكن, work rolls and intermediate rolls show huge gaps in adjustment capacity.
Work‑roll bending produces powerful effects. As bending‑roll force rises from 0 kN to 300 kN, strip crown falls from 30.5 μm to 24.6 μm (‑19.3 %). Edge‑drop value falls from 31.1 μm to 19.5 μm (‑37.3 %). It works especially well for edge‑drop improvement.
By contrast, intermediate‑roll bending shows limited performance. Within the same force interval, crown only drops 6.6 % and edge‑drop value only drops 9.3 %. Its adjustment capacity reaches merely one‑quarter to one‑third of work‑roll bending. في الإنتاج الفعلي, workers take work‑roll bending as major means and use intermediate‑roll bending for minor fine‑tuning.
4. Inter‑Roll Contact Pressure Analysis: Prioritize Pressure Uniformity
The UCMW mill structure easily triggers uneven inter‑roll contact pressure. Uneven pressure shortens roll service life and hurts strip flatness quality. This study adopts two evaluation indexes: peak pressure (p_max) and non‑uniformity coefficient α. Here α = (p_max‑p_avg)/p_max, and p_avg stands for average contact pressure.
4.1 Work‑roll Shifting brings Limited Influence over Pressure Distribution
Pressure peaks always appear at contact edges between backup rolls and intermediate rolls. Work‑roll shifting hardly changes this pressure field. In the contact zone between intermediate rolls and work rolls, pressure peaks concentrate at strip‑edge locations. Positive work‑roll shifting reduces pressure values on the right side, yet peak pressure stays almost unchanged. The non‑uniformity coefficient only drops by 0.03. So work‑roll shifting can barely improve overall pressure uniformity.
4.2 Intermediate‑roll Shifting Greatly Improves Pressure Uniformity
Intermediate‑roll shifting generates far more obvious effects. The pressure distribution between backup rolls and intermediate rolls remains stable. في المقابل, the contact zone between intermediate rolls and work rolls sees remarkable changes. As intermediate‑rolls shift toward positive direction, pressure values drop on the left side and rise slightly in central zones. Both peak pressure and non‑uniformity coefficient decrease, with α dropping roughly by 0.11. This measure avoids sharp local pressure spikes and effectively protects roll surfaces from damage.
5. Research Conclusions & Practical Application Value
Based on simulation results of this new six‑high mill roll‑profile scheme, we draw several key conclusions for cold‑rolling process optimization.
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Work‑roll shifting, intermediate‑roll shifting and work‑roll bending act as major flatness‑control tools. Operators apply intermediate‑roll bending only for auxiliary fine‑tuning. Coordinated operation achieves precise flatness regulation.
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Negative‑shift modes deliver strong suppression for strip crown and edge‑drop defects. Negative work‑roll shifting dominates edge‑drop control. Negative intermediate‑roll shifting shows advantages in crown adjustment.
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Work‑roll bending provides 3‑4 times larger adjustment capacity than intermediate‑roll bending. Production teams should prioritize work‑roll‑bending parameters for flatness correction.
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This roll‑profile setup prevents severe pressure spikes for backup rolls. Intermediate‑roll shifting further evens pressure between intermediate rolls and work rolls. It extends roll service cycles and lowers equipment‑replacement costs.
Steel plants can adopt this combined control strategy: negative work‑roll shifting plus negative intermediate‑roll shifting plus work‑roll bending. This solution precisely manages strip crown and edge‑drop values. في نفس الوقت, intermediate‑roll shifting optimizes inter‑roll pressure distribution. It lifts finished‑strip quality and cuts roll‑wear loss. في المستقبل, further development of finite‑element simulation will support more accurate roll‑profile design and parameter setting. It pushes domestic steel manufacturing toward higher quality, higher efficiency and lower‑energy consumption.
