Gas Wiping Nozzle Lip Assembly for Stable Coating Weight
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Solution Overview
Problem
The existing gas wiping nozzles in continuous hot dip metal plating apparatuses face challenges in maintaining precise control over the flow of gas due to variations in the relative positional relationship between the lip parts, leading to unstable coating weights on steel strips, especially at higher conveyance speeds.
Innovation Solution
A method for manufacturing gas wiping nozzles that involves fitting projections and holes with specific dimensions and arrangements to restrict relative movement between the lip parts, ensuring the distance between these components satisfies the formula D≤0.25×B, where D is the distance between the projections and holes in the thickness direction and B is the slit gap, thereby stabilizing the coating weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional assembly methods using bolts and nuts are used to fasten lip parts, then the gas wiping nozzle can be manufactured and assembled, but the relative positional relationship between lip parts varies leading to unstable gas flow control
Solution Approach 1:
A positioning pin is introduced as an intermediary component between the first and second lip parts. The positioning pin fits into positioning holes in both lip parts, serving as a mediator that establishes and maintains the precise relative positional relationship between the lip parts, thereby resolving the positioning variability issue inherent in conventional bolt-and-nut assembly methods.
Solution Approach 2:
The invention changes the assembly parameter from using clearance-fit bolt holes (which allow positional variation) to using interference-fit or transition-fit positioning pin holes (which constrain position). By changing the dimensional relationship between the positioning pin and positioning holes, the system achieves precise and stable relative positioning of the lip parts.
2Reliability
If the distance between positioning features is increased to restrict relative movement, then gas flow control improves, but manufacturing complexity increases
Solution Approach 1:
The positioning function is segmented into multiple independent positioning holes distributed at different locations on the lip parts. By providing multiple positioning features rather than a single complex positioning mechanism, the system achieves reliable restriction of relative movement while keeping each individual positioning element simple and easy to manufacture.
Data Source
AI summary
A method for manufacturing a gas wiping nozzle provided with a pair of lip parts facing each other and a slit formed as a gas ejection port between the pair of lip parts and blowing gas from the slit against a steel strip pulled up from a plating bath to adjust a thickness of a molten metal film deposited on a surface of the steel strip, which method includes fitting fitting projections provided at one lip part with fitting holes provided at another slip part and fastening the pair of lip parts together in the fitted state, the fitting projections fitted with the fitting holes, two pairs of the fitting projections and the fitting holes provided separated by a distance in a width direction of the steel strip, relative movement between the pair of lip parts in a thickness direction of the steel strip restricted in the fitted state.