Project Background and Core Process Requirements

WONDERY recently delivered an RJ3-45-9 pit-type electric resistance quenching furnace to a client in Vietnam (Mia Nguyen). The client specializes in the high-temperature heat treatment of shafts and rods, requiring exceptional stability at the 850 ℃ normal operating temperature and high structural integrity for heavy workpiece loading.

Technical Solutions and Parameterized Evidence

1. High-Strength Furnace Structure for Long-Term Service

To withstand the impact of hoisting heavy shafts, WONDERY reinforced the structural design:

Frame Construction: The furnace shell is welded from 10#~12# channel steel and 4-14mm high-quality steel plates, ensuring the frame remains rigid and deformation-free under high-temperature cycling.

Load Support: The furnace bottom is constructed with heavy-duty refractory bricks, providing both weight-bearing capacity and thermal insulation for the foundation.

2. Advanced Insulation System and Thermal Efficiency

To minimize energy loss at the 950 ℃ rated temperature, a multi-layer composite insulation structure was implemented:

Core Material: High-quality zirconium-aluminum refractory fiber blocks from Shandong Luyang, featuring a maximum temperature resistance of 1260 ℃.

Density and Thickness: The fiber blocks undergo secondary pre-compression, achieving a total insulation thickness of 325 mm (including ≥300 mm fiber blocks and a 25 mm back-up layer).

Environmental Impact: The exterior wall temperature rise is strictly controlled within ≤45 ℃, significantly improving the shop floor environment.

3. Reliable Heating Elements and Installation

Element Material: Utilizes 0Cr25AL5 high-resistance alloy, processed into corrugated strips and installed around the furnace perimeter for uniform radiant heating.

Anti-Short Circuit Design: Resistance strips are secured with specialized high-alumina ceramic screws and washers. This eliminates the risk of thermal short circuits between the elements and the fiber wall while simplifying maintenance.

4. Intelligent Temperature Control and Safety Interlocks

Control Accuracy: Features a Japanese Shimaden intelligent PID controller paired with a thyristor triggering mechanism, achieving a control accuracy of ±1 ℃ at the measuring point.

HMI: Equipped with a 10.1-inch industrial touchscreen, supporting real-time process recording, historical data retrieval, and multi-level over-temperature alarms.

Safety Logic: Integrated interlocks automatically cut off power to heating elements and fans when the furnace lid is opened, complemented by limit switches to prevent operational accidents.

Delivery Specifications and Key Parameters

Effective Working Dimensions: Ø 700 × 900 mm.

Rated Heating Power: 45 kW (1-100% adjustable).

Sealing Method: Employs a sand-seal structure between the furnace lid and body to prevent heat escape.