CLADDING TECHNOLOGY SHANXI CO., LTDCombined Roller Body Overlay Device for Mining Applications
Literature Overview
This 2005 research paper by Wang Yinyin from the Technical Center of Shanghai Meishan Co., Ltd. presents the development and application of a combined roller body overlay device for mining machinery. Published in the context of mining equipment technology, this work addresses the practical challenge of applying wear-resistant overlay cladding to cylindrical roller bodies used in conveyor systems, crushers, and screening equipment in mining operations.
Core Technical Analysis
Roller bodies in mining applications are subjected to severe abrasion from mineral particles, impact loading from falling materials, and corrosion from moisture and chemical contaminants. Conventional replacement strategies result in significant downtime and material waste. The combined roller body overlay device provides an in-situ or semi-in-situ solution for restoring worn rollers and enhancing new rollers with wear-resistant surfaces.
| Component | Function | Material Specification |
|---|---|---|
| Base roller shell | Structural support | Q345 or 16Mn steel |
| Transition layer | Metallurgical compatibility | Fe-2Cr-1Mo overlay wire |
| Wear-resistant layer | Abrasion resistance | Fe-5Cr-3Mo-2.5C hardfacing wire |
| Sealing layer | Corrosion protection | 304 stainless steel overlay |
| Fixing brackets | Device mounting | Carbon steel, machined |
| Welding power source | Energy input | Submerged arc or MIG/MAG |
The combined roller body overlay device integrates several functional elements:
- A rotating fixture that allows uniform circumferential cladding of the roller
- A multi-gun welding system for simultaneous longitudinal and circumferential deposition
- A flux or shielding gas delivery system for process protection
- A cooling system to manage thermal input and prevent distortion
- A positioning and alignment system for multi-pass overlay application
Process Design and Parameter Optimization
The overlay process for roller bodies requires careful parameter selection to achieve uniform coverage and acceptable mechanical properties. The following parameters are critical:
| Parameter | Typical Range | Optimization Criteria |
|---|---|---|
| Wire diameter | 1.6-2.4 mm | Balance between deposition rate and penetration |
| Welding current | 250-400 A | Sufficient penetration without excessive dilution |
| Arc voltage | 22-32 V | Stable arc, appropriate bead profile |
| Travel speed | 0.2-0.5 m/min | Uniform layer thickness |
| Overlap ratio | 50-70% | Complete coverage, no gaps |
| Interpass temperature | 80-150 °C | Prevent cracking, control residual stress |
| Number of passes | 3-6 | Achieve target thickness |
The multi-pass overlay strategy involves:
- First pass: Transition layer with lower carbon content for crack resistance
- Second pass: Intermediate layer with moderate hardness
- Subsequent passes: High-hardness wear-resistant overlay with controlled carbon content
- Final pass: Possible surface dressing for smoothness and dimensional accuracy
Defect Analysis and Quality Control
Quality control of roller body overlay cladding requires comprehensive inspection following relevant standards such as NB/T 47014 and JB/T 4730:
| Inspection Method | Acceptance Criteria | Application |
|---|---|---|
| Visual testing (VT) | No cracks, porosity, undercut | Surface inspection |
| Magnetic particle testing (MT) | No linear indications > 2 mm | Surface and near-surface defects |
| Ultrasonic testing (UT) | Bond strength verification | Interface inspection |
| Hardness testing | Uniform, within specification | Surface and cross-section |
| Wear testing | Sand rub or pin-on-disk | Performance verification |
| Impact testing | Adequate toughness | Sub-surface verification |
Common defects in roller body overlay cladding include:
- Cracking due to high residual stress in thick deposits
- Uneven thickness from improper travel speed control
- Porosity from inadequate shielding or flux coverage
- Lack of fusion from insufficient penetration
- Distortion from excessive thermal input
Engineering Practice and Performance Evaluation
Field trials of the combined roller body overlay device in mining operations have demonstrated significant improvements in service life compared to uncladded or conventionally cladded rollers:
| Application | Original Life | Cladded Life | Improvement Factor |
|---|---|---|---|
| Conveyor rollers (coal) | 6 months | 24 months | 4x |
| Crusher rollers (iron ore) | 3 months | 15 months | 5x |
| Screen rollers (aggregate) | 4 months | 18 months | 4.5x |
| Feeder rollers (ore) | 5 months | 20 months | 4x |
The economic benefits include:
- Reduced downtime for roller replacement
- Lower material consumption for new roller fabrication
- Extended maintenance intervals
- Improved operational safety through reduced unplanned stops
Study Insights and Reflections
This research represents a practical engineering solution to a common industrial problem. The combined roller body overlay device demonstrates how welding overlay technology can be adapted to cylindrical geometries through specialized equipment design. The approach is particularly valuable for large-diameter rollers where complete disassembly for conventional cladding is impractical.
From a metallurgical perspective, the multi-pass overlay strategy with transition layers ensures adequate bond strength and crack resistance. The device design allows for consistent process parameter control, which is essential for achieving uniform overlay properties around the entire roller circumference.
In conclusion, the combined roller body overlay device provides an effective, economical solution for extending the service life of mining equipment rollers, and its successful implementation demonstrates the versatility of weld overlay technology in addressing industrial wear challenges.