Wear-Protected Rolling Roller Surface for Grip Without Strip Contamination
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Solution Overview
Problem
Existing roll coatings in rolling mills face challenges in achieving optimal gripping conditions while minimizing strip contamination, particularly in high-strength steel materials, due to increased wettability issues and strip contamination during cold rolling processes.
Innovation Solution
A wear protection layer with defined topography and hardness characteristics, applied using PVD or HVOF processes, is applied to at least some areas of the roller surface, enhancing gripping conditions and reducing strip contamination by incorporating lubrication pockets and optimizing surface roughness parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a metallic protective layer (e.g., hard chrome plating) is applied to improve wear protection, then service life is extended, but strip cleanliness deteriorates due to increased contamination tendency
Solution Approach 1:
The patent applies a wear protection layer with specific local topography characteristics (Spk > 1.20 μm and Svk > 1.20 μm) to the roller surface. This localized surface structure creates gripping peaks and lubrication valleys that simultaneously provide wear resistance and prevent strip contamination, resolving the contradiction between extended service life and maintained strip cleanliness.
Solution Approach 2:
The wear protection layer is designed with a specific topography featuring peaks and valleys (lubrication pockets). This porous-like surface structure allows lubrication emulsion to be retained in the valleys while peaks provide gripping, thereby reducing strip contamination while maintaining wear protection and extending service life.
2Duration of action of stationary object
If high grinding roughness is applied to extend rolling service life, then service life is improved, but strip cleanliness deteriorates due to greater tendency toward contamination
Solution Approach 1:
The patent specifies precise topography parameters (Spk > 1.20 μm and Svk > 1.20 μm) for the wear protection layer surface. By controlling these specific parameters, the solution achieves optimal gripping conditions and lubrication retention that extend service life while preventing strip contamination, unlike conventional high roughness approaches.
Solution Approach 2:
The solution combines a wear protection layer with specific topography characteristics, creating a composite surface structure that integrates wear resistance with contamination prevention. This composite approach allows the layer to provide both protective functions simultaneously, resolving the contradiction between service life and strip cleanliness.
3Force
If the roll roughness is set too high to improve gripping conditions, then gripping condition is improved, but strip cleanliness deteriorates due to contamination
Solution Approach 1:
The wear protection layer creates localized gripping peaks (Spk > 1.20 μm) and lubrication valleys (Svk > 1.20 μm) on the roller surface. The peaks provide the necessary gripping force while the valleys retain lubrication to prevent contamination, resolving the contradiction between gripping condition and strip cleanliness through differentiated local surface properties.
Solution Approach 2:
The wear protection layer with specific topography acts as an intermediary between the roller and the strip. It provides gripping peaks for force transmission while retaining lubrication in valleys, thereby mediating the interaction to achieve both good gripping conditions and strip cleanliness simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the coefficient of friction, reduces strip contamination, and enhances the rolling process by allowing higher rolling forces, increased service life, and energy efficiency, while maintaining dimensional accuracy and reducing material defects.
Implementation Method 1
This can be done in certain areas if necessary, with at least 20%, 30%, 40%, in particular at least 50%, 60%, preferably at least 70%, or 80% of the roller's total outer surface being covered with a wear-resistant coating. This can also be completely covered, i.e., the entire outer surface of the roller, with a wear-resistant coating... The wear-resistant layer (2) can be applied either by PVD...
Implementation Method 2
WO 2021/148690 A1 discloses, for example, a roller having a sprayed-on wear protection layer based on a tungsten carbide alloy... As an alternative to the high-velocity flame spraying, also known as HVOF, DE 40 06 550 C1 discloses a process for the wear-resistant finishing of a working surface of rolls and rollers... The wear-resistant layer (2) can be applied either by PVD... or by HVOF...
Implementation Method 3
Friction is required for the gripping condition so that the strip material is gripped by the roll at the entrance to the roll gap and driven between the rolls... The solution improves the coefficient of friction, reduces strip contamination...
Data Source
Figure 1~2
AI summary
The invention relates to a roller (1) with a wear protection layer (2) applied at least in some areas and having a minimum hardness of 700 HV0.01 and a corresponding use.