The material hardness of the wire drawing wheel directly affects the fineness of the metal surface texture, processing efficiency, and equipment wear and tear. When adjusting, it is necessary to comprehensively match based on the processing material, target surface effect, and equipment performance. The following are the key adjustment strategies:
1. Matching material hardness with processing scenarios
High hardness wheel (Shore hardness 80-95A)
Applicable scenarios: Coarse drawing of hard metals such as stainless steel and titanium alloys (Ra 3.2-6.3 μ m), or working conditions that require rapid removal of oxide layers and welding scars.
Advantages: Strong cutting force, high wear resistance, but requires high pressure (15-20N/cm 2) to avoid slipping.
Medium hardness wheel (Shore hardness 60-75A)
Applicable scenarios: Fine drawing of soft metals such as aluminum alloy and brass (Ra 0.8-1.6 μ m), or processing of complex curved surfaces.
Advantages: Moderate elasticity, can reduce surface scratches, recommended pressure of 8-12N/cm 2.
Soft wheel (Shore hardness 40-55A)
Applicable scenarios: Mirror wire drawing pretreatment (Ra below 0.4 μ m) or ultra-thin sheet metal processing (thickness<0.5mm).
Advantages: High adhesion, avoiding material deformation, requiring low-speed (5-10m/min) operation.
2. Dynamic hardness adjustment technology
Temperature compensation method:
By using the built-in temperature control module in the device, the working temperature of the wire drawing wheel is stabilized at 25-40 ℃. For example, when the nylon wheel is heated to 35 ℃, its hardness decreases by about 10%, which can be temporarily adapted for soft metal processing.
Composite wheel layered design:
Adopting a "hard core+soft surface" structure (such as polyurethane wrapped steel core), the surface is deformed by 5-15% by adjusting the pressure, indirectly changing the effective contact hardness and adapting to multi material mixed line production.
Sand belt/wire drawing wheel combination process:
After rough machining of the hard wheel, switching to a soft wheel and overlaying it with a # 800 mesh or more sand belt for precision repair can achieve a "soft landing" of hardness without replacing the wheel body.
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3. Parameter linkage optimization
Pressure hardness formula:
The relationship between hardness (H) and theoretical pressure (P) is:
P=k×H
one point two
P=k×H
one point two
(k is the material coefficient, 0.8 for stainless steel and 0.5 for aluminum alloy)
For example, when processing stainless steel, if the hardness of the drawing wheel is 80A, the pressure must be ≥ 15.3N/cm 2.
Speed matching rule:
For every 10A increase in hardness, the line speed needs to be reduced by 20% -30%. The recommended speed for hard wheels (90A) is 8-12m/min, while for soft wheels (50A) it can be increased to 18-25m/min.
4. Verification and maintenance
Reverse roughness verification:
After processing, measure the Ra value. If it is 10% higher than the target value, increase the hardness or pressure; If there are burn marks, reduce the hardness and increase cooling.
Wear warning:
The lifespan of hard wheels is about 200-300 hours, while that of soft wheels is about 80-150 hours. The diameter change of the wheel body can be monitored by a laser thickness gauge, and replacement is required if the wear exceeds 5%.
Case: When processing magnesium alloy shells at a certain 3C accessory factory, the original 75A wire drawing wheel caused edge cracking. After adjusting to 50A soft wheel and reducing the pressure to 6N/cm 2, the cracking rate decreased from 12% to 0.3%, and the uniformity of the drawn texture increased by 40%.
