ERW Tube Mill Machine

Shijiazhuang Faith Machinery Co., Ltd. presents its latest electric resistance welding (ERW) tube mill machines, engineered for efficient production of medium‑diameter carbon steel and alloy tubes. Geared toward manufacturers in automotive, hydraulic, and construction applications, these ERW lines combine precise forming, induction heating, and comprehensive inspection to deliver tubes that meet stringent mechanical and dimensional requirements. This detailed overview examines the machine architecture, welding process, control features, and maintenance considerations.

1. Coil Preparation and Decoiling
ERW production begins with a decoiler assembly that feeds strip into the mill at speeds up to 100 meters per minute. The pay‑off carriage automatically compensates for the decreasing coil diameter, maintaining constant strip tension through a magnetic particle brake and load cell system. A leveller section immediately downstream uses segmented rolls and a pre‑tension zone to flatten the strip, removing camber and edge waves that could compromise forming accuracy.

2. Forming Section
The core of the ERW mill consists of a series of forming stands that shape the strip from flat to a cylindrical tube blank. Shijiazhuang Faith Machinery Co., Ltd. employs precision‑machined roll stands with integrated laser alignment systems. Roll gaps are automatically adjusted based on feedback from laser micrometers measuring tube outer diameter every few centimeters. This closed‑loop control maintains wall thickness tolerance within ±0.05 mm and roundness within 0.5% of nominal diameter.

3. Induction Welding Head
The induction coil assembly generates high‑frequency currents—typically in the 200 kHz to 400 kHz range—that heat the strip edges to welding temperature in less than a second. An adjacent forging roll immediately applies pressure to join the edges. The coil’s water‑cooled copper windings are housed in a vibration‑damped frame to minimize electromagnetic interference and prolong coil life. Welding parameters, including current amplitude and frequency, are stored in the PLC recipe and adjusted automatically when switching between tube sizes from 10 mm to 76 mm outer diameter.

4. Weld Bead Conditioning and Cooling
After induction welding, the tube passes through a scarfing unit that removes the weld flash to produce a smooth exterior surface. A downstream cooling station sprays deionized water from adjustable nozzles to control quenching rate, which influences weld microstructure and mechanical properties. For applications requiring enhanced hardness, the system can be configured with a press‑quench module that cools the weld more aggressively under pressure.

5. Inline Inspection Systems
To ensure weld integrity and dimensional compliance, each ERW line is fitted with multiple inspection stations. Surface cameras capture high‑resolution images of the weld seam for detecting laps, wrinkles, or incomplete fusion. Simultaneously, an ultrasonic testing (UT) station performs volumetric analysis using phased‑array probes, identifying internal defects such as voids or cracks. A PLC‑controlled diverter then rejects any substandard sections, routing them to a scrap conveyor without interrupting the main flow.

6. Sizing, Stretch Forming, and Cut‑Off
Following inspection, the tube enters a sizing module with smoothing rolls that correct any residual distortion, achieving ovality below 0.5%. A stretch‑forming unit applies controlled tension to improve straightness and cohesiveness of the weld. Finally, a flying cutoff saw synchronized to line speed produces clean ends ready for threading, flaring, or other downstream processes. Cut‑off lengths are programmable from 0.5 meters to 6 meters, and scrap collection conveyors minimize floor clutter.

7. Control and Data Management
An Allen‑Bradley PLC network manages all line components, while an intuitive HMI provides access to recipes, alarms, and process data. Key metrics—strip speed, weld current and voltage, temperature, and inspection results—are logged in an SQL database. This data can be exported for integration with customer ERP or quality management systems, enabling traceability from raw coil to finished tube.

8. Maintenance Strategy
To maximize uptime, Shijiazhuang Faith Machinery Co., Ltd. recommends a maintenance plan that includes periodic coil replacement checks, induction coil inspections, roll bearing lubrication, and safety sensor calibrations. Critical spares—such as induction coil assemblies, forging roll jackets, and ultrasonic probe elements—are stocked locally by authorized distributors. Remote diagnostic capability allows service technicians to monitor machine health and recommend interventions before unscheduled stops occur.

With its emphasis on precise forming, responsive welding controls, and thorough inspection, the new ERW tube mill machines from Shijiazhuang Faith Machinery Co., Ltd. offer a dependable solution for producing carbon steel tubes that satisfy demanding industry standards, including API 5L, ASTM A513, and EN 10305. Continuous data logging and advanced control strategies help fabricators maintain consistent quality, improve yield, and adapt quickly to changing production requirements.