Air Knife Pressure Control for Variable-Thickness Galvanized Strip
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Solution Overview
Problem
Existing methods for hot-dip galvanizing variable thickness steel strips face challenges in controlling the thickness of the coating uniformly across sections with continuous transitions, leading to inefficiencies and inconsistencies in the galvanization process.
Innovation Solution
A system comprising a steel strip thickness gauge, length measuring roller, hot-dip galvanizing apparatus, air knife, and control system is used to detect and adjust the thickness and length of the steel strip, and subsequently, the pressure of the air knife to maintain a uniform zinc coating thickness, by measuring and calculating deviations and adjusting the air knife pressure accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ultrasonic or eddy current gauges are used to measure coating thickness, then non-contact measurement is achieved, but the gauges cannot differentiate between galvanneal and liquid_applied polymer coatings, leading to measurement inaccuracy
Solution Approach 1:
The system uses optical detection to measure the reflectivity of light at specific wavelengths. Different coating materials (galvanneal vs. polymer) have different optical reflectivity characteristics. By analyzing the reflected light intensity at multiple wavelengths, the system can differentiate between coating types and accurately measure thickness for each specific coating material type.
2Device complexity
If a single fixed ultrasonic gauge frequency is used, then the measurement system is simple, but it cannot accurately measure coatings with varying thicknesses and material properties across the strip width
Solution Approach 1:
The system employs multiple ultrasonic transducers operating at different frequencies positioned across the strip width. The frequencies are dynamically selected based on the specific measurement location and coating conditions. This allows the system to adapt to varying thicknesses and material properties while maintaining measurement accuracy throughout the entire strip width.
Solution Approach 2:
The measurement system is divided into multiple independent measurement zones across the strip width, with dedicated transducers for each zone. Each transducer can be independently controlled and optimized for its specific measurement location, allowing accurate measurement of variable thickness coatings while maintaining overall system manageability.
3Device complexity
If manual inspection methods are used to verify coating thickness, then equipment complexity is low, but productivity is reduced due to production interruptions and labor requirements
Solution Approach 1:
The system performs automated real-time coating thickness measurement and quality verification during continuous production. The automated optical and ultrasonic sensors continuously monitor the coating process without requiring manual intervention, eliminating production interruptions while maintaining comprehensive quality control.
Solution Approach 2:
The measurement system operates continuously during the entire coating process, providing uninterrupted real-time feedback. This continuous monitoring enables immediate detection and correction of coating defects while maintaining production flow, thereby maximizing productivity without sacrificing quality assurance.
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
This approach ensures a uniform zinc coating thickness on variable thickness steel strips, simplifying the process and improving the consistency of the galvanization, thereby enhancing the quality of the coated steel strips.
Implementation Method 1
an ultrasonic gauge is used to measure the thickness of the galvanneal layer
Implementation Method 2
an eddy current gauge is used to measure the thickness of the galvanneal layer
Data Source
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AI summary
Disclosed are a system and method for controlling a thickness of a hot-dip galvanized coating on a strip material with a continuously varying thickness. The system comprises a steel strip thickness gauge (8), a length measuring roller (11), a hot-dip galvanizing apparatus, an air knife (5), a cold-state zinc coating measuring instrument (7), and a control system (10). In a forward movement direction of a steel strip (1), the steel strip thickness gauge (8) and the length measuring roller (11) are arranged before an inlet of the hot-dip galvanizing apparatus, and the air knife (5) and the cold-state zinc coating measuring instrument (7) are sequentially arranged behind an outlet of the hot-dip galvanizing apparatus. The steel strip thickness gauge (8) detects a thickness signal of the steel strip (1), the length measuring roller (11) detects a length signal of the steel strip (1), the cold-state zinc coating measuring instrument (7) detects a zinc coating thickness of the steel strip (1), and the steel strip thickness gauge (8), the length measuring roller (11) and the cold-state zinc coating measuring instrument (7) respectively send measurement data to the control system (10). The control system (10) predicts a thickness of the steel strip at the air knife (5) and adjusts a pressure of the air knife (5) according to the length signal and the thickness signal, and further adjusts the pressure of the air knife according to the zinc coating thickness.