H273 HF ERW Tube Mill

H273 HF ERW Tube Mill – Direct Forming to Square Technology
This H273 HF ERW tube mill is equipped with advanced Direct Forming to Square (DFS) technology.
The strip is formed directly into square or rectangular sections during the forming and sizing stages, eliminating the conventional “round-to-square” secondary deformation process. This significantly reduces internal stress and improves dimensional accuracy, corner sharpness, and product stability.
In the square/rectangular forming and sizing section, the mill adopts a universal roll design. Different square and rectangular sizes can be produced by roll position adjustment only, without changing the rolls, which greatly reduces changeover time, roll inventory cost, and downtime. This design is especially suitable for flexible production with multiple sizes and small to medium batch orders.
In the round pipe forming section, different round diameters require corresponding forming rolls due to the specific forming angles and welding seam geometry. Therefore, round pipe rolls need to be changed when the round diameter is changed. After welding, the round pipe is directly formed into square or rectangular profiles in the sizing section.
I. What is 273
H273 refers to:
Maximum forming specifications: □273 mm square/rectangular tubes
Typically corresponds to the forming range of φ219–φ273 round tubes → square/rectangular tubes
In the industry:
H273 belongs to medium-to-large welded pipe production lines
It demands high forming force, frame rigidity, shaft diameter, and roller profile precision
👉 This is not achievable with small-scale equipment.
II. What is “New Direct Forming to Square”
1️⃣ Traditional Process (Comparison)
Traditional method involves
Steel strip → Forming into round (full set of round tube rolls)→ Welding→ Round tube sizing→ Switching to a set of square forming rolls→Square/rectangular tube.
❌ Drawbacks:
Frequent roll changes
High spare roll costs
Slow specification changeovers
Low automation level
2️⃣ New Direct Forming to Square (DFS)
New Direct Forming to Square refers to:
Forming steel strip directly into “square/rectangular tube logic” within the forming zone, rather than round-to-square conversion
Core concept:
Reduce secondary deformation from round to square
Lower internal stress
Reduce the number of roll sleeves
III. What does “No Roll Change Across the Entire Line” Mean?
⚠️ This is the most critical—and most easily misunderstood—statement
Correct interpretation:
Within the “forming zone + welding zone + square sizing zone,”
a single set of rolls can cover multiple square/rectangular specifications without frequent changes
It typically implies:
Forming stands utilize:
Shared-type roll design
Large adjustment range structure
Achieving different specifications through:
Vertical/horizontal adjustment
Variation in reduction ratio
Roll gap changes
✅ Advantages:
Fast specification changeover (10–30 minutes)
High automation level
Ideal for high-volume multi-specification orders
❌ Drawbacks:
Complex roll profile design
Extremely high frame rigidity requirements
Large shaft diameters required (H273 typically ≥ φ110–130 mm)
IV. What does “partial roll change for round tubes” mean?
This phrasing is actually professional and straightforward, which is a definite plus.
Explanation:
When round tube specifications change (e.g., φ114 → φ165 → φ219)
The front section forming the round tube still requires corresponding roll changes
This is dictated by physical laws, not technological limitations.
Why must rolls be changed for round tubes?
Round tubes:
Forming angles
Edge wrap angles
Weld closure positions are all highly dependent on diameter
A single roll profile cannot “universally accommodate all diameters”
👉 Therefore:
Round → Weld → Direct Square Forming
Only the “square forming zone” can operate without changing rolls
The round forming zone must change rolls — This is a professional judgment
V. The True Technical Meaning of the Entire Statement (Engineering Summary)
Let me rephrase it using engineering terminology:
This H273 high-frequency welded pipe mill employs a new-generation direct square forming process:
The forming and square/rectangular sizing zones utilize a shared-type roll structure, enabling multi-specification square/rectangular tube production without roll changes—specification switching is achieved solely through position adjustment;
The round tube forming section still configures corresponding rolls for different round tube diameters; changing round tube specifications requires replacing round tube rolls.
— This is a fully professional, well-founded statement.
VI. Which customers is this solution suitable for?
✅ Highly suitable for:
Primarily producing square and rectangular tubes
Multiple specifications, small batches
Seeking rapid changeovers
High automation requirements
⚠️ Less suitable for:
Producing only a single specification in ultra-large volumes
Extreme requirements for limit wall thickness/high-strength steel (e.g., Q690+ thick-walled)