JCOE Press Tonnage Calculations refer to determining the hydraulic press force (in tons or kN) required for the progressive J-C-O forming steps in LSAW pipe production. JCOE uses a large single hydraulic press for incremental bending of steel plates.
scirp.org
Why Tonnage Matters in JCOE
- The press must deliver enough force for elastic-plastic bending across multiple steps (typically 15–25 circumferential strokes per pipe half).
- Key variables: Plate thickness (t), pipe diameter (OD → affects curvature/radius), material yield strength (σ_y or tensile strength σ_b), plate width/length (forming length), tool geometry (upper punch radius, lower die spacing), and step width.
- JCOE advantage: Step-by-step forming distributes force, requiring lower peak tonnage per stroke than UOE (full U or O in one go). This allows thicker walls with a given press.
botopsteelpipes.com
General Calculation ApproachExact formulas are proprietary (e.g., SMS Group’s ShapeBase software uses semi-analytical moment/curvature models with iterative elastic-plastic simulation). However, engineers use these approximations based on plate bending theory:
- Basic Press Brake-Style Formula (adapted for JCO incremental steps):
P (kN)≈K×σb×t2×LVP \ (kN) \approx \frac{K \times \sigma_b \times t^2 \times L}{V}
P \ (kN) \approx \frac{K \times \sigma_b \times t^2 \times L}{V}- (P): Bending force (kN)
- (K): Coefficient (1.0–1.42 for air bending; higher for bottoming)
-
σb\sigma_b
\sigma_b: Tensile strength (MPa, e.g., 450–600+ for carbon steel)
- (t): Thickness (mm)
- (L): Bend length (plate width, in m)
- (V): Effective die opening or step width (mm)
Convert to metric tons: Divide kN by 9.81.
vistmac.com - For JCO Incremental Steps:
- Force per step is lower because only a portion of the plate is bent at a time.
- Typical stroke calculation involves moment distribution between lower dies and upper tool.
- Software iterates based on previous steps’ contours, springback, and target curvature.
Rough Examples for Your Specs (5–18 mm thickness, 457–1800 mm OD):
- For 18 mm thick plate (API 5L-grade carbon steel, ~550 MPa tensile): Peak forces often range 10,000–50,000 kN (≈1,000–5,100 tons) per stroke, depending on step width and diameter.
huaxisteels.com
- Modern JCO presses: 10,000–60,000+ tons capacity (e.g., 36,000 kN / ~3,670 tons for mid-size lines; up to 100,000 kN for heavy-wall).
vistmac.com
- Thicker walls or larger diameters increase tonnage needs quadratically with thickness (
t2t^2
t^2).
Real-World Press Capacities:
- SMS/Haeusler JCO lines: Often 20,000–60,000 tons for 16–64″ pipes up to 45–60 mm thick.
sms-group.com
- Chinese lines: 10,000–100,000 kN common for your range.
sinobender.com
Comparison: JCOE Press Tonnage vs 3-Roll Bending
|
Aspect
|
JCOE (Press)
|
3-Roll Rolling Machine
|
|---|---|---|
|
Force Application
|
High concentrated force per incremental step
|
Distributed across rolls (lower peak per area)
|
|
Tonnage Required
|
Higher press capacity (10k–60k+ tons)
|
Lower (rolls handle via hydraulic adjustment)
|
|
For 5–18 mm
|
Overkill but precise
|
Sufficient and more efficient
|
|
Thick Walls (>25 mm)
|
Much better (lower force per step)
|
Limited
|
|
Productivity
|
Medium (multiple strokes)
|
Higher (continuous)
|
Practical Insights for Your Project
- For 5–18 mm thickness, a 3-Roll + expander line usually needs far less “press-style” tonnage investment and offers faster diameter changes.
- JCOE shines when you need maximum uniformity or plan thicker future pipes. Press tonnage scales with
t2t^2
t^2, so 18 mm requires significantly more force than 10 mm.
- Always use supplier simulation software (e.g., SMS ShapeBase) for accurate values — they factor in real material properties, springback, and multi-step history
