Understand the Entire Welded Pipe Process in 3 Minutes: 12-Step Process Disassembly of ZY Mill from Uncoiling to Flying Saw

Welded pipe production may seem complex, but it is actually a collaborative operation of a series of precision processes. The ZY series high-frequency welded pipe mill transforms steel strips into high-precision pipes through a 12-step standardized process, with each step containing hidden ingenuity. The following breaks down the core principles and key parameters of each link from raw materials to finished products.

1. Uncoiling: The "First Gate" to Unlock Raw Materials

Core Equipment: Pneumatic double-reel uncoiler
Working Principle: Fix the coiled steel strip (inner diameter φ508mm, outer diameter ≤φ1200-1800mm, coil weight ≤1.5-5 tons) through a pneumatic expansion reel, and control the uncoiling speed through pneumatic strength braking to avoid slack or tearing of the steel strip.
Key Details: The double-reel design supports manual 180° rotation for station replacement, reducing downtime for coil change by 50%, and is suitable for various raw materials such as hot-rolled/cold-rolled low-carbon steel and galvanized steel.

2. Material Storage Buffer: The "Reservoir" for Continuous Production

Two Forms Adapt to Different Needs:

• Vertical Hoop Cage (e.g., ZY20/32/45): 3.8-6-meter-long box, driven by a 3-4kw pinch motor, with a feeding speed of up to 200m/min, which can store a certain length of steel strip to cope with short shutdowns during uncoiling and coil changing.
• Horizontal Spiral Accumulator (e.g., ZY50/76/89): Diameter 4.2-5.0 meters, feeding speed 120-200m/min, caches steel strips through a spiral structure, suitable for continuous supply of large-width (60-320mm) and thick-walled (0.8-4.5mm) raw materials.

3. Shearing and Butt Welding: Removing Defects for Seamless Connection

Core Functions:
① Cut off the defective parts at the head, tail and middle of the steel coil to ensure the purity of raw materials;
② Cut the head and tail before welding to make the joint flat and aligned (manual seaming), laying the foundation for welding.
Parameter Highlights: The cutting thickness is 0.4-4.5mm (covering the whole series), the blade is made of T12A high-strength steel, and the 2-3 edge design prolongs the service life. Hydraulic/pneumatic shearing power is suitable for different steel strip thicknesses.

4. Leveling: A Key Step to "Flatten" the Steel Strip

Core Equipment: 7-roller leveling device
Working Principle: The lower roller is fixed, and the upper roller is adjusted in height through a handwheel screw. The unpowered roller group eliminates the rolling stress of the steel strip through multiple passes of rolling, making it enter the forming mill smoothly.
Why 7 Rollers: The multi-roller design can precisely control the deformation, avoiding wrinkling of thin steel strips (0.4mm) and bending of thick steel strips (4.5mm), laying the foundation for subsequent forming accuracy.

5. Rolling Forming: The Shaping Process of Steel Strip "Turning into Tubular"

Core Principle: Using the baseline horizontal roller forming principle, the rollers adopt a double-radius pass. Through the cooperation of horizontal rollers and vertical rollers, the flat steel strip is gradually rolled into a tubular shape.
Structural Details:

• Horizontal roller stands (7-8 stands): Gantry structure, divided into rough forming (4-5 stands) and finish forming (3 stands), with shaft diameter φ40-90mm (42CrMo material, quenched and tempered with high-frequency);
• Vertical roller stands (9 stands): Chute-type double guide rails, manually adjusting opening and closing and centering to avoid scratching the surface of the pipe blank;
• Overload protection: A buffer pad is set on the top of the horizontal roller bearing to automatically release force when foreign objects are stuck, protecting the equipment from damage.

6. High-Frequency Welding: The Core Process of "Fusing Seams"

Three Steps to Achieve Seamless Welding:
① Weld Seam Guiding: The upper and lower rollers clamp the pipe blank, and the middle guide blade calibrates the seam angle (adjusted by screws) to ensure edge alignment;
② High-Frequency Heating: Through 100-300kw solid-state high-frequency equipment, the metal at the seam is instantly melted (temperature reaches 1300-1500℃);
③ Extrusion Welding: Two-roller/three-roller extrusion rollers (side roller diameter φ25-50mm) apply pressure to squeeze out molten impurities, making the edges of the pipe blank fuse into one.

7. External Burr Removal: Making the Weld "Smooth as a Mirror"

Equipment Design: 1 stand with double tool holders (alternately usable), adjusting the height and lateral position of the tool through a handwheel, combined with a pneumatic fast feed and retract device, to efficiently remove external burrs generated during welding.
Detail Guarantee: The hardwood lower support (height adjustable) lifts the pipe blank to avoid shaking of the pipe during cutting and ensure the weld is flat.

8. Cooling: "Cooling and Shaping" the High-Temperature Pipe

Cooling Method: Combined spraying and overflow pool

• Sprinkler head: Adjustable metal pipes are installed in the middle of each section of the roller to accurately aim at the weld and roller system;
• Flow requirement: ≥10-15 tons/hour, quickly cooling the pipe temperature from above 800℃ to below 100℃ to avoid deformation during subsequent sizing.

9. Sizing: Precisely Controlling Pipe Dimensions

Core Function: Through the precision rolling of 6 horizontal rollers and 6 vertical rollers, the size of the formed pipe is calibrated to the target value (round pipe φ8-102mm, square pipe 10x10-80x80mm, etc.).
Accuracy Guarantee: The horizontal roller shaft diameter is φ40-90mm (same as the forming roller material), the upper roller is adjusted separately left and right, and the vertical roller is equipped with an up-down adjustment mechanism to ensure the pipe diameter tolerance is ≤±0.1mm.

10. Straightening: Making the Pipe "Stand Straight"

Two Devices Adapt to Needs:

• Turk Head (most models): Four-roller structure, which can adjust up and down, left and right, and rotate, straightening the straightness of the steel pipe and guiding the pipe into the flying saw accurately;
• Four Horizontal and Four Vertical Straightening (e.g., ZY16): 4 horizontal + 4 vertical roller combination, quickly straightening small-diameter (φ8-18mm) pipes without deformation.

11. Flying Saw Cutting: The "Fast Cutter" for Fixed-Length Cutting

Core Performance:

• Microcomputer sizing: Cutting accuracy ±3mm, fixed-length range 4-10m (ZY45 can reach 10m);
• Synchronous cutting: 11-15kw tracking motor drives the trolley, synchronized with the pipe speed (0-90m/min), 4-22kw sawing motor drives φ350-600mm saw blade, hot friction cutting without burrs;
• Quick reset: Instantly return after cutting to prepare for the next cutting, which is 30% more efficient than traditional sawing machines.

12. Run-Out Table: The "Last Leg" of Finished Product Conveying

Structural Design: Section steel welded bracket, the idler is 45# steel quenched and hard chrome plated (scratch-resistant), driven by a 3-5kw motor, the speed matches the production line, and smoothly conveys the finished pipe to the stacking area.

Summary: The Collaborative Logic of 12 Steps

From uncoiling to run-out, the ZY mill transforms steel strips into high-precision pipes through 12 steps in three stages: "raw material processing → shaping and welding → finishing and cutting". The core advantages lie in:

• Parameter matching of each link (e.g., material storage speed adapts to production speed, cooling flow matches welding heat);
• Modular design (such as different material storage forms and straightening devices) adapts to different pipe diameters and wall thickness requirements;
• Detail guarantees (such as overload protection and scratch-resistant idlers) improve equipment life and product quality.

What you can understand in 3 minutes is not only the process, but also the design logic of "precision, efficiency and reliability" of the ZY mill.