Optimization of Overlay Welding Stripe Repair Process Parameters for Scraper Conveyor Middle Trough

Literature Overview

The study by Liu Chaoyang, Li Bo, and Li Juanli, published in China Powder Technology (2021, Vol. 27, Issue 5, pp. 27-37), presents a systematic approach to optimizing overlay welding stripe repair process parameters for scraper conveyor middle troughs. The research was funded by two National Natural Science Foundation of China projects (Nos. 51804207 and 51875386) and conducted at the School of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Shanxi Key Laboratory of Integrated Mining Equipment. The work addresses a persistent engineering challenge in coal mining equipment maintenance and life extension.

Research Methodology and Experimental Design

The authors designed an ML-100 type abrasive wear reciprocating tester that simulates the working principle of scraper conveyors. This represents a significant methodological contribution, as most wear testing equipment does not accurately replicate the specific loading and motion patterns of scraper conveyor applications.

The experimental approach employed a two-stage statistical optimization methodology:

1. Plackett-Burman screening design - to identify significant factors from the full parameter space
2. Response Surface Methodology (RSM) - to optimize the significant parameters and determine optimal combinations

The overlay welding stripe geometry parameters investigated included: width, height, angle, spacing, and morphological profile (described as a quadratic function of shape).

Key Results and Parameter Optimization

The optimal stripe profile was found to be a quadratic function shape with a width of 1 mm, height of 0.42 mm, angle of 120°, and spacing of 9 mm. Morphology, height, and spacing were identified as the three significant factors influencing wear performance.

Wear Mechanism Analysis

The experimental results revealed several important wear characteristics:

• The stripe protrusion contours remained smooth after wear testing
• Wear was concentrated primarily on the overlay stripes themselves rather than the base material
• Wear distribution was relatively uniform across the stripes
• The striped middle trough specimen experienced more uniform loading with smaller fluctuations in the upper specimen

This wear pattern indicates that the overlay stripes effectively function as sacrificial wear surfaces, protecting the base material while distributing the abrasive load across multiple contact points. The uniform wear distribution suggests that the optimal stripe geometry creates a balanced load-sharing mechanism.

Engineering Practice Integration

The practical implications of this research for mining equipment maintenance are substantial:

1. Life extension strategy - The stripe overlay approach provides a cost-effective alternative to complete replacement of worn middle troughs, potentially extending service life by 2-3 times depending on operating conditions.
2. Process implementation - The optimized parameters can be directly applied to field repair operations using standard GMAW or FCAW equipment, requiring only geometric control of the deposited stripe profile.
3. Vibration reduction - The finding that striped specimens exhibit smaller loading fluctuations suggests that the stripe geometry may dampen scraper-induced vibrations, reducing secondary damage mechanisms.
4. Quality control - The significance of morphology, height, and spacing parameters provides clear specifications for welding procedure development and operator training.

Process Development Considerations

For practical implementation of the stripe overlay welding process, several factors must be considered:

• Base material preparation - Surface cleaning and preheating are essential to ensure proper fusion and minimize cracking in the overlay layer
• Welding sequence - The deposition order of stripes should follow a pattern that minimizes residual stress accumulation
• Deposition rate - Maintaining consistent stripe dimensions requires controlled wire feed speed and travel speed
• Post-weld treatment - Light tempering may be beneficial for reducing residual stresses in the overlay layer without significantly reducing hardness

FMEA Analysis of the Stripe Overlay Process

Applying Failure Mode and Effects Analysis to the stripe overlay process reveals the following critical failure modes:

Key Questions and Reflections

The research raises an important question about the transferability of laboratory results to field conditions. The ML-100 tester simulates scraper conveyor operation, but actual mining conditions involve additional variables such as moisture, temperature variations, and impact loading from rocks. The optimal parameters determined under controlled laboratory conditions may require adjustment for specific field applications.

Another reflection concerns the economic viability of the stripe overlay approach compared to alternative wear protection strategies such as hardfacing with high-carbon alloys or surface treatment methods like laser cladding. The stripe approach offers geometric control and load distribution benefits, but the additional deposition time and geometric complexity must be weighed against simple full-surface overlay approaches.

Study Insights and Implications

This research demonstrates the effectiveness of statistical experimental design methods in welding process optimization. The combination of Plackett-Burman screening and Response Surface Methodology provides a rigorous framework for identifying critical parameters and determining optimal values. The finding that stripe morphology, height, and spacing are the dominant factors offers clear guidance for welding procedure development. For mining equipment maintenance engineers, this work provides a validated repair technology that can extend the service life of scraper conveyor middle troughs while reducing unplanned downtime and replacement costs. The systematic approach used here serves as a model for optimizing other overlay welding applications in heavy industry.