Zhuojin Pipe Fitting Co., LtdTubular Welding Wire Submerged Arc Overlay Application in Nonwoven Fabric Industry
Literature Overview
The paper by Pang Ming and Fu Wenlong (1998) presents an application of tubular wire submerged arc overlay welding (SAW) technology to the repair and hardfacing of hot calender rollers in nonwoven fabric manufacturing equipment. This work originated from the Shanghai Textile Machinery Research Institute and Shanghai Dayang Welding Technology Engineering Company, representing a cross-industry technology transfer from heavy steel processing to textile machinery. The publication appeared in the journal "Industrial Textiles" (Vol. 16, No. 5, pp. 32-33), and is classified under TG455 (welding technology).
Core Technical Concept
The fundamental premise is that tubular wire submerged arc overlay welding, a mature hardfacing technology in steel and rolling mill industries, can be adapted for nonwoven fabric equipment rollers. In nonwoven fabric production, hot calender rollers serve as critical forming surfaces where fiber webs are pressed, bonded, and textured at elevated temperatures. The roller surface experiences continuous contact stress, thermal cycling, and abrasive wear from fiber particles, leading to premature surface degradation and dimensional deviation.
Process Parameters and Configuration
| Parameter | Typical Range | Function |
|---|---|---|
| Tubular wire diameter | 4.0-5.0 mm | Filler supply and shielding gas delivery |
| Shielding gas | CO2 or Ar/CO2 mix | Arc stability and oxide protection |
| Welding current | 400-600 A | Penetration depth control |
| Travel speed | 300-600 mm/min | Layer thickness and dilution |
| Wire feed speed | 200-400 m/h | Deposition rate |
| Preheat temperature | 150-250 °C | Residual stress reduction |
| Number of passes | 1-3 | Overlay thickness 1-3 mm |
Key Technical Points
- Tubular wire design allows internal shielding gas delivery through the hollow core, providing superior arc stability and consistent deposition compared to solid wire SAW in overlay applications.
- The flux coating on tubular wire provides additional deoxidation and alloying elements (Cr, Mo, V, W, C) essential for wear-resistant surface hardening.
- Roller repair involves removing the damaged surface layer through grinding or machining, followed by multi-pass overlay to restore dimensional accuracy and surface hardness.
- Post-weld stress relief at 550-650 °C for 2 hours per 25 mm of roller diameter is critical to prevent overlay delamination during subsequent service.
Engineering Practice Integration
In nonwoven fabric production, the hot calender roller operates at 150-250 °C with continuous contact pressure of 0.5-2.0 MPa. Traditional repair methods involved complete roller replacement or simple welding with solid wire, which often resulted in excessive dilution, soft surface layers, and short service life. The tubular wire SAW approach offers:
- Cost reduction: Overlay repair extends roller life by 3-5 times compared to simple machining and re-hardening, reducing replacement frequency from every 6 months to 2-3 years.
- Quality improvement: Consistent overlay hardness of 45-55 HRC provides uniform surface properties across the roller width, eliminating the hardness gradient issues common with manual welding methods.
- Dimensional control: The semi-automated tubular wire SAW process achieves overlay thickness uniformity within ±0.1 mm across the roller face, critical for fabric thickness control in nonwoven production.
Defect Analysis and Countermeasures
| Defect Type | Root Cause | Prevention/Correction |
|---|---|---|
| Overlay cracking | High carbon equivalent, insufficient preheat | Preheat to 200 °C, post-weld stress relief |
| Poor fusion | Surface contamination, insufficient current | Clean base to bare metal, increase current 10% |
| Porosity | Gas entrapment, flux moisture | Dry flux storage, control wire feed speed |
| Excessive dilution | Too high travel speed or current | Reduce current by 50-100 A, optimize speed |
| Hardness below specification | High dilution, inadequate alloy content | Use higher-alloy wire, reduce dilution rate |
Study Insights and Reflections
This 1998 publication represents an early example of technology transfer from capital equipment manufacturing to textile machinery. The core insight is that overlay welding is not limited to heavy industry applications; any rotating surface component experiencing abrasive contact, thermal cycling, and dimensional wear can benefit from hardfacing technology. The tubular wire SAW process, with its combination of high deposition rate, consistent shielding, and alloy control, is particularly suited for cylindrical roller repair where surface quality and dimensional accuracy are paramount.
The paper's practical value lies in demonstrating that mature welding technologies can be adapted across industries with minimal process modification. For engineers working on roller repair today, this historical reference validates the approach and provides baseline parameters that remain relevant, though modern wire compositions and automated systems have further improved the technology. The key lesson is that process selection should be driven by component function and failure mode analysis rather than industry convention.