Hot-Dip Plating Support Roll Diameter Ratio and Axis Spacing
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Solution Overview
Problem
In continuous hot-dip plating, scratches and defects often occur on the surface of metal strips due to contact with support rolls, leading to non-uniform coating and reduced quality of the hot-dip steel sheet.
Innovation Solution
A continuous hot-dip plating machine is designed with specific dimensions for the support rolls, where the diameter of the first support roll, the diameter of the second support roll, and the vertical distance between their rotation axes satisfy certain conditions, preventing scratches and defects by optimizing the contact and alignment of the rolls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the metal strip is flattened using support rolls, then the uniformity of coating weight is improved, but scratches and defects occur on the surface of the metal strip
Solution Approach 1:
The patent applies parameter changes by precisely controlling the diameter ratio between the first and second support rolls (D1/D2 = 0.95-1.05) and adjusting the vertical distance L between their rotation axes. These parameter optimizations ensure that the rolls contact the metal strip at optimal points, achieving sufficient flattening for uniform coating weight while minimizing surface damage through reduced contact pressure and improved alignment.
Solution Approach 2:
The patent implements dynamics by making the vertical distance L between the rotation axes of the first and second support rolls adjustable. This allows the system to adapt to different metal strip thicknesses and coating requirements, optimizing the flattening effect while preventing excessive contact pressure that would cause scratches and defects.
2Shape
If the support rolls are used to flatten the metal strip, then the shape uniformity is improved, but the surface quality deteriorates due to dross adhesion and slip scratches
Solution Approach 1:
The patent applies parameter changes by optimizing the diameter ratio D1/D2 to be within 0.95-1.05 and controlling the vertical distance L between rotation axes. These parameter settings ensure that both support rolls contact the metal strip simultaneously and uniformly, achieving proper flattening while distributing contact pressure evenly to prevent dross adhesion and slip scratches.
Solution Approach 2:
The patent applies local quality by ensuring that the first and second support rolls have slightly different diameters (within 5% difference) to create optimized local contact zones on the metal strip surface. This local optimization allows each roll to contact the strip at the most favorable position, achieving uniform flattening while minimizing areas where dross could adhere or where slip scratches could occur.
Data Source
AI summary
A continuous hot-dip plating machine includes: a sink roll provided in a plating bath and configured to upwardly change a transfer direction of the steel strip; a first support roll provided in the plating bath and located above the sink roll, the first support roll being in contact with a first surface of the steel strip in contact with the sink roll; and a second support roll provided in the plating bath and located above the first support roll, the second support roll being in contact with a second surface of the steel strip opposite the first surface. A diameter of the first support roll, a diameter of the second support roll, and a vertical distance between a rotation axis of the first support roll and a rotation axis of the second support roll satisfy specific conditions.