Brass-Plated Steel Wire Drawing with Variable Friction Dies
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Solution Overview
Problem
Conventional methods for forming a noncrystalline portion on brass-plated steel wires to enhance adhesion with rubber suffer from frequent wire breaking and reduced die service life, leading to productivity issues and require elaborate equipment.
Innovation Solution
A wire drawing apparatus with specific friction coefficients for dies, ranging from 0.12 to 0.41, is used to create a noncrystalline surface layer on brass-plated steel wires, optimizing the drawing process to prevent wire breaking and extend die life while ensuring adequate adhesion with rubber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the concentration of lubricative contents is lowered to form a heavy-worked layer, then adhesion performance is improved, but wire breaking occurs frequently and die service life is reduced
Solution Approach 1:
The invention applies different friction coefficients to different positions in the drawing process. The most downstream die uses a high friction coefficient (0.15-0.35) to create the noncrystalline surface layer for adhesion, while anterior dies use low friction coefficients (0.05-0.12) to reduce wire breaking and extend die life. This local differentiation resolves the contradiction between improving adhesion and maintaining productivity.
Solution Approach 2:
The drawing process is segmented into multiple stages with different friction characteristics. The final drawing stage (most downstream die) is separated from anterior drawing stages, allowing independent optimization of friction coefficients for each stage. This segmentation enables the high friction needed for surface modification without subjecting the entire wire path to high friction, thus preventing wire breaking.
2Reliability
If plasma CVD is used to form a noncrystalline brass plating layer, then adhesion performance is improved, but equipment complexity increases
Solution Approach 1:
The invention replaces the plasma CVD process (a complex chemical vapor deposition system) with a mechanical drawing process using a die with controlled friction coefficient. The mechanical friction during drawing naturally creates the noncrystalline surface layer through heavy working, eliminating the need for elaborate plasma equipment while achieving the same adhesion improvement.
3Manufacturing precision
If high friction coefficient is applied in final drawing, then noncrystalline surface layer is formed, but wire breaking and die wear increase
Solution Approach 1:
The anterior dies with low friction coefficients perform preliminary drawing to reduce wire breaking and extend die life before the final drawing stage. This preliminary action prepares the wire for the high-friction final drawing by reducing residual stresses and ensuring proper lubrication, allowing the most downstream die to apply high friction without causing excessive wire breaking or die wear.
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
The method effectively forms a noncrystalline surface layer with high lattice defect density, enhancing initial adhesion performance without compromising productivity or die service life, and further controls wire breaking by adjusting friction coefficients within optimal ranges.
Implementation Method 1
the friction coefficient of at least one of a most downstream die, a second most downstream die, and a third most downstream die is 0.12 to 0.41
Implementation Method 2
a noncrystalline portion consisting of crystal grains of 20 nm or less in grain size is formed on the surface side of the crystalline portion of the brass plating layer
Data Source
AI summary
A wire drawing apparatus (10) is used in a final drawing process to ensure adequate initial performance of adhesion between brass-plated steel wire and rubber without a drop in productivity. At least one of the die (14z) disposed in the most downstream position, the die (14y) disposed in the second most downstream position, and the die (14x) disposed in the third most downstream position is a drawing die having a friction coefficient μ of 0.12 to 0.41 with the brass-plated steel wire. The other dies (14) are drawing dies each having a friction coefficient μ of 0.1 or below. By using these drawing dies, brass-plated steel wire (13) is drawn, and a noncrystalline portion of high lattice defect density is formed on the surface of the crystalline portion of the brass-plating layer of the brass-plated steel wire (13).