Submerged Arc Surfacing Device for Roll Press Squeezing Rolls

Literature Overview

The 2019 paper by Wang Yinjun, Huang Quanxin, Huang Xiang, Jiang Sheming, and Zhang Qifu, published in Foundry Technology (Vol. 40, Issue 2, pp. 210-212), describes a specialized submerged arc surfacing device developed for the continuous surfacing of roll press squeezing rolls. The work was conducted jointly by the State Key Laboratory of Advanced Surface Engineering at the Institute of Metal Research, Chinese Academy of Sciences, and Shanghai Meishan Iron and Steel Co., Ltd. This represents a practical engineering solution for a common maintenance challenge in the mineral processing and metallurgical industries.

Application Background

Roll press squeezing rolls are used in:

Mineral processing: Iron ore pelletizing, coal briquetting, mineral concentration
Metallurgical industry: Steel rolling mills, plate mills, strip mills
Aggregate processing: Stone crushing and sizing operations

These rolls operate under extreme conditions:

Operating Condition	Typical Value
Compressive load	50-200 MN/m
Roll surface speed	1-5 m/s
Material temperature	Ambient to 300°C
Abrasion mechanism	High-pressure sliding abrasion
Service life (unsurfaced)	100-500 hours
Service life (surfaced)	500-2000+ hours

The surfacing layer must withstand:

Extreme contact stresses (Hertzian pressures exceeding 2 GPa)
Sliding abrasion against hard mineral particles
Thermal cycling from frictional heating
Impact loading from material feed variations

Device Architecture and Functionality

The specialized submerged arc surfacing device integrates multiple functions into a single system:

Core Components

Component	Function	Specification
Heating unit	Preheating and interpass temperature control	Induction or gas heating; 100-300°C range
Surfacing mechanism	Submerged arc welding execution	Multi-wire or single-wire SAW; adjustable travel speed
Insulation system	Post-weld thermal management	Insulating blankets; controlled cooling rate
Slag removal system	Continuous slag removal between passes	Mechanical or pneumatic; automated
Positioning system	Roll rotation and welding head tracking	Hydraulic or pneumatic; encoder-controlled

Process Integration

The device enables a fully integrated surfacing process:

Heating: Preheat the roll surface to the required temperature (typically 200-300°C for medium-carbon steel rolls) to prevent cold cracking and reduce residual stresses.
Surfacing: Execute multi-pass submerged arc welding with controlled heat input, travel speed, and current/voltage parameters.
Insulation: Apply thermal insulation after each pass to control the cooling rate and prevent excessive hardness in the heat-affected zone.
Slag removal: Automatically remove slag between passes to ensure clean surface preparation for the next layer.

Process Parameters

Typical process parameters for roll surfacing include:

Parameter	Value	Notes
Base metal	Q345, 40Cr, or similar medium-carbon steel	Roll shell material
Surfacing wire	High-carbon, high-chromium, or hardfacing alloy	Selected based on service conditions
Flux type	Submerged arc flux (rutile or basic type)	Provides protection and alloy addition
Current	500-1000 A	Depends on wire diameter and surfacing layer
Voltage	25-35 V	Arc stability and penetration control
Travel speed	100-300 mm/min	Deposition rate and bead geometry
Number of passes	3-8	Achieves required surfacing thickness
Surfacing thickness	3-15 mm	Depends on service life requirement

Quality Considerations

Common Defects and Countermeasures

Defect	Cause	Countermeasure
Cracking	Excessive heat input, inadequate preheating	Control heat input; increase preheat temperature
Porosity	Inadequate flux coverage, surface contamination	Ensure proper flux application; clean surface
Lack of fusion	Low current, excessive travel speed	Increase current; reduce travel speed
Excessive hardness	High cooling rate, unsuitable alloy composition	Apply insulation; select appropriate consumable
Delamination	Residual stress, thermal mismatch	Optimize surfacing sequence; apply stress relief

Inspection Requirements

Visual inspection: After each pass, verify bead geometry and absence of surface defects.
Ultrasonic testing: After surfacing is complete, verify absence of subsurface cracks and lack of fusion.
Hardness testing: Measure hardness profile through the surfacing layer and heat-affected zone.
Impact testing: Verify toughness of the heat-affected zone.
Dimensional verification: Confirm roll diameter and runout specifications.

Engineering Practice Integration

This device represents a significant advancement in roll surfacing technology, addressing several practical challenges:

Productivity: The integrated device enables continuous surfacing without manual intervention, significantly reducing production time.
Quality consistency: Automated control of process parameters ensures consistent surfacing quality across all rolls.
Operator safety: Reduced manual handling and exposure to welding hazards.
Flexibility: The device can be adapted for different roll diameters and surfacing requirements.

Critical Reflections

While the device offers clear advantages, several considerations remain for practical implementation:

Initial investment: The specialized device requires significant capital investment, which may be prohibitive for small operations.
Maintenance requirements: The integrated system requires regular maintenance to ensure reliable operation.
Training requirements: Operators must be trained in both the device operation and the underlying welding metallurgy.
Applicability limitations: The device is designed for cylindrical rolls; adaptation for other geometries may be required.

The development of this integrated surfacing device demonstrates the importance of combining welding technology with mechanical engineering to create practical solutions for industrial maintenance challenges. The successful application in mining and metallurgical industries validates the approach and provides a template for similar innovations in other heavy industry sectors.