Wire Coating Through a Drawing Die for Uniform Layer Thickness
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Solution Overview
Problem
Existing methods for applying coating layers to wires result in insufficient uniformity and quality due to lateral deflection of wires during coating, leading to radially and axially varying layer thicknesses and defects, and often use harmful solvents that affect health and economic efficiency.
Innovation Solution
A method and apparatus where a wire is drawn through a coating chamber with a pressurized, thermally liquefied coating agent acting as a lubricant and forming tool, allowing for solvent-free or low-solvent polymers like polyethylene waxes or polyurethanes to be applied uniformly, with a drawing tool reducing the wire's cross-section and ensuring a stable coating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a stripping nozzle with a hole larger than the wire diameter is used to strip excess coating, then the coating process can be performed, but the wire laterally deflects during transport through the nozzle resulting in radially and axially varying layer thicknesses and layer defects
Solution Approach 1:
Instead of using a stripping nozzle that removes excess coating from the outside, the invention inverts the approach by using a drawing die that forms the coating from the inside during the drawing process. The coating material is introduced into the drawing die where it is distributed uniformly onto the wire surface as the wire passes through, eliminating the lateral deflection problem associated with external stripping nozzles.
Solution Approach 2:
The invention introduces a coating material as an intermediary substance that is distributed within the drawing die. This coating material acts as a mediator between the wire and the drawing die, ensuring uniform coating application while the wire is being drawn. The coating material fills the space between the wire and the die wall, preventing direct contact and lateral deflection.
2Ease of manufacture
If solvent-based organic resin is used for coating, then the coating can be applied to the wire, but harmful solvent vapors are released affecting health protection and economic efficiency
Solution Approach 1:
The invention changes the fundamental parameter of the coating material from solvent-based organic resin to water-based or solvent-free alternatives. This parameter change eliminates the release of harmful solvent vapors while maintaining the coating application process. The water-based or solvent-free coating materials provide the necessary coating properties without the harmful byproducts.
Solution Approach 2:
The invention converts the potential harm of solvent-based coatings into a benefit by eliminating solvents entirely or replacing them with water-based systems. This transformation removes the harmful vapor release issue while maintaining effective coating application, turning a harmful process into an environmentally friendly and health-safe process.
3Productivity
If thermoplastic materials are applied in melted form by extruder, then coating can be achieved, but additional equipment and process steps are required including wiping nozzles and after-treatment
Solution Approach 1:
The invention merges the coating application function with the existing drawing die and drawing process. Instead of using separate extruder and wiping nozzle equipment, the coating material is introduced and distributed within the drawing die itself, combining multiple functions into a single integrated component. This eliminates the need for additional equipment while maintaining coating capability.
Solution Approach 2:
The drawing die is given multiple functions: it performs the traditional wire drawing function while simultaneously serving as the coating application device. The drawing die distributes the coating material onto the wire surface during the drawing process, making the equipment universal and eliminating the need for separate coating equipment.
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 achieves high-quality, uniformly thick coatings with improved adherence and increased productivity, eliminating harmful solvent vapors and enabling faster coating processes while providing excellent insulation properties for copper wires and versatile shape transformations for aluminum wires.
Implementation Method 1
a pressurized coating agent being liquefied or softened by a thermal exposure
Implementation Method 2
the coating agent serves as a lubricant between the drawing tool and a surface of the substrate
Implementation Method 3
The substrate provided with the coating layer is expediently cooled after leaving the coating chamber. The coating layer may be brought into contact with a cooling medium in a conventional manner, for example, by using water as a cooling medium.
Data Source
AI summary
Subject matter of the present invention is a method of applying coating layers (9) to a substrate (1, 11, 21, 31), wherein the substrate (1, 11, 21, 31) is drawn through a coating chamber (2) containing a pressurized coating agent (3) being liquefied or softened by means of a thermal exposure, wherein the substrate (1, 11, 21, 31) is drawn through a drawing tool (8), wherein the coating agent (3) serves as a lubricant between the drawing tool (8) and a surface of the substrate (8) and wherein at the same time the coating layer (9) is applied to the surface of the substrate (8). Subject matter of the invention is also a corresponding apparatus for applying a coating layer (9) to a substrate (1, 11, 21, 31). By means of the invention coating layers can be applied to a substrate in an efficient and economical way.