Preheated Fastener Head Coating for Uniform Zinc Coverage
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Solution Overview
Problem
Steel nails often experience uneven zinc distribution during galvanization, leading to cosmetic corrosion, and conventional hot-dip galvanizing processes are inefficient, complex, and result in inconsistent quality and increased waste.
Innovation Solution
A method and apparatus for applying a corrosion-resistant coating using a molten or semi-molten metal spray to the heated head of fasteners, ensuring a continuous zinc layer without overheating, which includes preheating the fastener head and spraying it with zinc or its alloys using a wire arc sprayer, and optionally abrading the surface for better adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hot-dip galvanizing is used to coat steel nails with zinc, then corrosion protection is provided, but the zinc distribution becomes uneven and cosmetic corrosion occurs
Solution Approach 1:
The steel wire is pre-plated with zinc before nail formation, ensuring the shank has protective coating. Then the nail head is separately coated after formation to complete the corrosion protection system, addressing both uniformity and coverage issues
Solution Approach 2:
Different coating methods are applied to different parts of the nail: the shank receives pre-plating during wire processing, while the head receives post-formation coating, allowing each region to have optimized zinc distribution for its specific requirements
2Reliability
If hot-dip galvanizing batch process is used, then corrosion protection is achieved, but manufacturing efficiency decreases and operational complexity increases
Solution Approach 1:
The galvanizing process is segmented into two independent stages: pre-plating of steel wire (continuous process) and post-coating of formed nails (continuous process). This eliminates the need for batch processing and allows nails to be galvanized inline without stopping production
Solution Approach 2:
Both pre-plating and post-coating operations are implemented as continuous processes integrated into the nail manufacturing line, eliminating batch interruptions and maintaining continuous production flow for improved efficiency
3Reliability
If hot-dip galvanizing is used, then zinc coating is applied, but nails are heated to high temperatures causing weakening and bending
Solution Approach 1:
The wire is pre-plated with zinc before nail formation when the steel is more heat-tolerant, and the head is coated afterward with controlled heating, avoiding high-temperature exposure of the formed nail which prevents weakening and bending
Solution Approach 2:
The coating process parameters are optimized by applying heat locally and temporarily only to the nail head during post-coating, rather than heating the entire nail to high temperatures, thus maintaining nail strength while achieving corrosion protection
4Reliability
If hot-dip galvanizing batch process is used, then corrosion protection is provided, but quality inspection complexity increases
Solution Approach 1:
The continuous coating process produces consistent, uniform zinc layers on all nails without batch-to-batch variations, eliminating the need for extensive quality inspection of each batch and simplifying the inspection process to routine checks
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 method provides a consistent and thick zinc coating on the fastener heads, enhancing corrosion resistance without weakening the fasteners, reducing waste, and improving manufacturing efficiency by maintaining the strength and alignment of the nails.
Implementation Method 1
spraying the preheated area of the fastener with a molten or semi-molten metal
Implementation Method 2
The sprayed metal provides a sacrificial cathodic corrosion protection to the heated area of the fastener
Implementation Method 3
preheating an area of the fastener to be coated (such as the head of the fastener) to elevate a temperature of the area to be coated
Implementation Method 4
The sprayed metal provides a sacrificial cathodic corrosion protection to the heated area of the fastener
Data Source
AI summary
A method of applying a corrosion-resistant coating to a fastener that includes preheating an area of the fastener to be coated to elevate a temperature of the area and spraying the preheated area of the fastener with a molten or semi-molten metal. In one embodiment, a corrosion-resistant coating applicator includes a support structure, a rotatable slotted fastener conveyer supported by the support structure, a feeder configured to feed fasteners to the rotatable slotted fastener conveyer, a fastener aligner configured to make head portions of the fasteners aligned with each other, a heater configured to heat head portions of the fasteners as the fasteners are being conveyed by the slotted fastener conveyer, and a sprayer configured to apply a corrosion-resistant coating to the heated head portions of the fasteners being conveyed by the slotted fastener conveyer. The present disclosure also provides corrosion-resistant coated fasteners made using the coating methods and/or coating apparatus.