I. Industry Insight: Strict Demands for Atmosphere Control and Temperature Uniformity in Precision Cold-Drawn Tubes

In the manufacturing supply chains of automotive fuel pipes, hydraulic cylinders, and high-pressure boiler lines composed of precision cold-drawn steel tubes (such as SAE 1008/1010 grades), work hardening stands out as a critical roadblock affecting subsequent bending, flaring, and machining operations. To eliminate residual micro-stresses and reconstitute raw material ductility, the steel pipes must undergo a precise bright annealing or normalizing treatment at high temperatures up to $950^{circ}text{C}$. However, conventional open-atmosphere furnaces prompt extreme superficial oxidation and decarburization at such thermal levels, compromising dimensional tolerances and increasing surface roughness far beyond premium industrial delivery grades.

WONDERY’s Support Roller Type Mesh Belt Bright Annealing Production Line represents the definitive engineering response to these thermal processing challenges. The system creates an air-tight, hermetically isolated thermal processing envelope filled with a cracked ammonia atmosphere ($text{H}_2text{ 75}% + text{N}_2text{ 25}%$) acting as a highly reducing protective barrier. By sustaining a structured 60-minute in-furnace transit time, the line guides the tube profiles through a strict "Heating-Holding-Dual Cooling" sequence under an oxygen-free envelope, ensuring the output tubes arrive at the unloading table completely clean, bright, and scales-free.

Following the successful commissioning of heavy-duty vertical Vacuum Pressure Impregnation systems for industrial motor insulation (referenced in the document named "260602VPI1500-3000 Semi-auto Vacuum Impregnation Equipment System.docx"), WONDERY has once again asserted its core competency in industrial fluid heating and metallurgy by delivering this continuous line stretching a total length of 36,825 mm (Model: WDL260608BR).

II. Technical Solutions and Full-Line Process Architecture

1. Continuous Modular Long-Axis Framework & Low-Stress Synchronous Drive Engineering

To orchestrate the continuous feeding profile of long-axis seamless steel pipes ($L = 6000text{ mm}$, diameter $Phi14 sim 38.1text{ mm}$), WONDERY divided the 36.8-meter line into five structurally interdependent modules engineered for low tensile deformation:

• Front Loading Roller Conveyor: Features a heavy structural steel welded entry bed measuring $6000 times 900 times 1020text{ mm}$ driven by a $0.55text{ kW}$ variable frequency gear motor setup. This section leads to an integrated $2000text{ mm}$ stainless steel preheating connector containing a ceramic fiber curtain air-lock door and an automatic gas ignition system to isolate the internal reduction atmosphere from atmospheric air.

• Low-Tension Support Roller Drive (Proprietary Technology): Standard mesh belt lines running continuously at $950^{circ}text{C}$ subject the conveyor belt to high mechanical tension, leading to thermal creep and frequent tearing. WONDERY eliminates this vulnerability via a synchronous idler support design. High-temperature SUS310 alloy rollers support the mesh belt across the heating chamber, while the lower return rollers use a core-type design paired with high-temperature KF bearing assemblies and aluminum alloy heat sinks. The mesh belt ($SUS314, 400 times 49000 times 2.0/3.0text{ mm}$) serves primarily as a material carrier rather than a tension element, as sprockets and chains drive every idler roller in unison. This minimizes the operating tension on the belt, heavily extending its operational lifespan.

2. Four-Zone Independent Low-Voltage Radiant Heating & Anti-Decarburization Refractory Insulation

• Squirrel Cage Radiant Tube Configuration: The main heating chamber spans a longitudinal distance of $6000text{ mm}$ with an allocated heating capacity of $130text{ kW}$ divided into 4 independent temperature control zones. The furnace contains 36 horizontal radiant tube shells ($Phi124 times 1050text{ mm}$ made of seamless SUS310) enclosing heavy 0Cr25Al5 heating elements supported by corundum insulators.

• Low-Voltage Power Supply Safety Distribution: The radiant tubes are powered by safe, low secondary voltage ($42text{ V}$) via 4 dry-type step-down transformers (380V/42V) mounted directly to the furnace exterior. This parallel low-voltage configuration reduces electrical fatigue on the resistance wires and allows operators to isolate and service a single radiant tube assembly without halting the continuous operation of the line.

• Anti-Carburization Brickwork & Forced Atmosphere Convection: The internal refractory lining incorporates LBK26 anti-carburization bricks bonded with high-purity silica sol, backed by structural insulation board, calcium silicate sheeting, and multi-layer Luyang cera blankets for a total insulation profile thickness of $400text{ mm}$. The roof houses 4 forced-convection atmosphere mixing blowers ($0.75text{ kW}$ motors with SUS310 blades and NSK bearings), ensuring a longitudinal temperature uniformity of $pm6^{circ}text{C}$ and a cross-sectional accuracy of $pm3^{circ}text{C}$.

3. Cascade Open-Jacket Liquid Chilling & Fail-Safe Digital Control Integration

• Dual-Stage Cooling Chambers: Directly following the heating zone, a $700text{ mm}$ slow-cooling chamber brings temperatures down progressively to prevent unexpected phase transformations in sensitive steel alloys. The pipe then travels through a $9000text{ mm}$ water-cooled section split into multiple zones using an open, self-pressurizing reflux jacket (Zone 1 uses a SUS310 liner, Zone 2 uses a SUS321 liner). Supported by a $15,000text{ L/h}$ industrial recirculating water setup, the cooling sector drops the pipe unloading temperature to $le120^{circ}text{C}$ before it reaches the final $7000text{ mm}$ discharge roller conveyor.

• Top-Tier Industrial Digital Control Center: Automated logic throughout the line is orchestrated by a Mitsubishi PLC paired with a 14-inch MCGS digital touchscreen interface. Precise thermal monitoring is managed by 5 Honeywell DC1040 PID controllers coupled with Shimax solid-state relays for thyristor voltage regulation, achieving a control resolution of $pm1^{circ}text{C}$.

• Fail-Safe Safety Interlocks & Gas Purging: The entire low-voltage distribution architecture relies on integrated Siemens air switches, contactors, and circuit breakers. The control cabinet features an automated emergency safety interlock: if factory power is suddenly cut, the system isolates the cracked ammonia gas line and injects a $6text{ m}^3$ reserve of high-pressure nitrogen to purge the furnace chambers, preventing flame flashback or explosive mixtures. Production logs (including temperature curves, speeds, and faults) are exported to Excel and retained on a dedicated PC for 6 months.