Dish Flanging Machine (for sheet-metal tank & pressure-vessel heads)

Definition
A dish flanging machine forms the knuckle radius and straight flange on pre-dished blanks (tank/pressure-vessel heads). It cold- or hot-rolls the rim of the dish while the work rotates, producing torispherical, elliptical, hemispherical and custom heads with controlled flange height (Hf) and knuckle radius (Rk).

Machine architecture

• Rotary table (C-axis): clamps and rotates the dish; heavy worm/servo drive with speed control.
• Forming unit: a hardened forming roll against a support/back-up roll. The head moves on CNC axes (typ. X radial, Y vertical, Z axial/slide; A tilt) to track the programmed radius.
• Drives: hydraulic or electro-servo for force, with closed-loop pressure/position control.
• CNC/PLC: recipe parameters for diameter, thickness, material, Rk, Hf, feed/speed, max thinning, passes.

Process (cold or hot)

1. Load pre-dished blank onto table and clamp.
2. Set Rk and Hf; define feed per rev and target thinning limit (e.g., ≤8–12%).
3. Rotate table; forming roll feeds radially/vertically to bend the rim.
4. Multiple passes refine flange height and roundness; springback compensation applied.
5. Beading/edge-trimming (optional) → finished head.

Typical capability (varies by model)

• Diameter: Ø500–10,000 mm
• Thickness: 2–50+ mm (cold up to ~25–30 mm carbon steel; thicker/higher-strength often hot)
• Knuckle radius: Rk ≈ 0.06–0.2 × D (ASME/EN head styles)
• Flange height: 20–250 mm+
• Accuracy: flange height ±1–2 mm; ovality ≤0.5–1.0%; thinning controlled by pass strategy.

Tooling

• Interchangeable hardened rollers (different nose radii for Rk, straightening, beading).
• For hot work: heat shields/water-cooled rolls; pyrometer for rim temperature (typ. 650–850 °C depending on grade).

Advantages vs. press/spinning

• One setup, repeatable geometry and concentricity to the dish.
• Lower tooling cost than dedicated dies; fast changeover via CNC recipes.
• Handles heavy-gauge heads where spinning is impractical.

Applications
Pressure-vessel heads (torispherical/elliptical), storage tanks, boilers, cookware, sinks, architectural bowls.

Selection checklist

• Max diameter/thickness and material grades (S275–P355, stainless, duplex, Al).
• Cold vs hot capability; table load (kN) and torque.
• Number of CNC axes and programmable thinning/pass control.
• Clamping/centering system, safety guarding, edge-trimming or beading options, data logging.

Quality & safety notes

• Monitor wall thinning; use multi-pass schedules and proper lubrication.
• Check flange height uniformity and Rk with templates or CMM.
• Guard pinch points around rolls; use foot pedals with two-hand/hold-to-run modes