Submerged Arc Overlay Welding Device for Roller Press Extrusion Rollers

Literature Overview

This paper by Wang Yinjun, Huang Quanxin, Huang Xiang, Jiang Sheming, and Zhang Qifu, published in Casting Technology (Vol. 40, No. 2, 2019, pp. 210-212), presents a specialized submerged arc overlay welding (SAW) device developed for the continuous surface overlay welding of roller press extrusion rollers. The device was developed collaboratively by the National Engineering Laboratory for Advanced Metal Coatings at the Central Iron and Steel Research Institute and the Technical Center of Shanghai Meishan Iron and Steel Co., Ltd. The device integrates heating, overlay welding, heat preservation, and continuous slag removal functions into a single automated system, enabling efficient and high-quality overlay welding of large-diameter roller press rollers used in mining and metallurgical applications.

Technical Background and Application Requirements

Roller press extrusion rollers are critical components in mineral processing and metallurgical operations, where they are used to compress and shape material streams. These rollers are subjected to severe abrasive wear, impact loading, and thermal cycling during service, necessitating periodic overlay welding to restore dimensions and extend service life. The traditional approach to roller overlay welding involves manual or semi-automated welding processes that are labor-intensive, time-consuming, and prone to quality variability.

The development of a specialized automated SAW device addresses several key requirements:

The automated nature of the device enables continuous production operation with minimal downtime, which is critical for maintaining production schedules in mining and metallurgical operations where roller press availability directly impacts throughput.

Device Structure and Functional Components

The submerged arc overlay welding device consists of several integrated functional modules that work together to provide a complete welding solution:

Heating Module

The heating module provides preheating of the roller surface prior to welding. Preheating is essential for reducing thermal stresses, preventing cold cracking, and ensuring proper weld metal solidification. The heating system typically uses induction heating or gas heating to achieve uniform temperature distribution across the roller surface.

Typical preheating parameters include:

• Preheat temperature: 200-400°C (depending on roller material)
• Heating rate: 50-100°C/h
• Temperature uniformity: ±20°C across the welding zone
• Holding time: 30-60 minutes at target temperature

Overlay Welding Module

The welding module is the core component of the device and includes the wire feeder, torch assembly, flux hopper, and travel mechanism. The submerged arc welding process provides high deposition rates, deep penetration, and excellent weld quality with minimal spatter.

Key welding parameters for roller overlay welding:

• Welding current: 600-1000 A
• Arc voltage: 28-38 V
• Travel speed: 200-500 mm/min
• Wire diameter: 1.6-2.4 mm
• Flux type: Rutile or basic flux
• Wire feed speed: 20-40 m/min

Heat Preservation Module

The heat preservation module maintains the roller at an elevated temperature after welding to control cooling rates and prevent cracking. This is achieved through insulated covers or heated blankets that enclose the welded area.

Heat preservation parameters:

• Post-weld temperature: 300-500°C
• Cooling rate: 50-100°C/h
• Duration: Until temperature drops below 150°C
• Insulation material: Ceramic fiber or refractory blanket

Slag Removal Module

The continuous slag removal module is a distinctive feature of this device that eliminates the need for manual slag removal between weld passes. The module uses mechanical scrapers or vibratory mechanisms to remove solidified slag from the weld surface, preparing it for the next pass.

Slag removal specifications:

• Removal timing: Immediately after slag solidification
• Removal method: Mechanical scraping or vibration
• Surface preparation: Clean, slag-free surface for next pass
• Cycle time: Synchronized with welding travel speed

Process Flow and Operational Sequence

The automated welding process follows a systematic sequence that ensures consistent quality and efficiency:

1. Roller positioning: The roller is mounted on the device with proper alignment and clamping.
2. Surface preparation: The roller surface is cleaned and prepared for welding.
3. Preheating: The roller is heated to the target preheat temperature.
4. Welding initiation: The torch is positioned and the welding process begins.
5. Continuous welding: Multiple passes are deposited with automatic slag removal between passes.
6. Heat preservation: The welded roller is maintained at elevated temperature for controlled cooling.
7. Cooling and inspection: The roller is cooled to room temperature and inspected for quality.

The entire process is controlled by an automated system that monitors and adjusts welding parameters in real-time to maintain consistent weld quality. The system includes sensors for temperature, travel speed, wire feed rate, and arc voltage, with feedback control to maintain the desired parameters.

Quality Control and Performance Results

The device has been successfully applied to the continuous submerged arc overlay welding of roller press extrusion rollers in mining and metallurgical industries. The quality results demonstrate the effectiveness of the automated approach:

The successful application of this device in industrial settings demonstrates the practical viability of automated SAW for roller overlay welding.