Pneumatic Sheet Metal Bending Machine with Adjustable Angle Stop

Small fabrication shops and college workshops bend thin sheet metal by hand on a bench brake — slow, tiring, and inconsistent from part to part, because the operator's feel decides the angle. Hydraulic press brakes solve the force problem but are far too expensive and complex for a teaching lab or a student project budget. Pneumatics sit in the middle: shop air at 6–8 bar is cheap, clean and safe, and a 63 mm bore cylinder produces roughly 2.5 kN of punch force (calculated design target), enough to air-bend 0.5–0.8 mm mild steel sheet up to 150 mm wide. This project is a working bench-top pneumatic bender: welded mild-steel frame, double-acting cylinder, 5/2 DCV solenoid valve for extend/retract, an FRL unit for conditioned air, and a 90° V-die with radiused punch. The adjustable angle stop — a sliding block on a graduated scale bar — is the project's signature: it converts stroke position into a repeatable bend angle, with a calibration procedure that compensates springback per material batch.

1. Shop air at 6–8 bar enters the FRL unit, which filters out moisture, regulates pressure to the set value (read on the 0–10 bar gauge) and mists lubricating oil into the airline.
2. The flat sheet blank is slid against the adjustable angle-stop bar, which locks the blank's edge position so every part starts from the same datum.
3. Pressing the push-button energizes the 5/2 DCV solenoid; the valve shifts and routes pressure to the cap end of the double-acting cylinder.
4. The cylinder rod drives the radiused V-punch down onto the sheet over the 90° V-die (20 mm opening), air-bending the metal until the punch reaches the preset stop position.
5. Releasing the button shifts the valve back; pressure goes to the rod end and the punch retracts, leaving the bend with its natural springback — compensated by the overbend set during calibration.
6. The operator checks the included angle with a protractor against the calibration chart, nudges the stop block if needed, and repeats — each cycle takes about 5–8 seconds including loading.

Tech stack:

• Pneumatics: 63 mm bore double-acting cylinder, 5/2 DCV solenoid valve, FRL unit, PU tubing with push-in fittings
• Tooling: 90° V-die (20 mm opening), radiused V-punch, mild-steel tool blocks
• Structure: welded mild-steel square-tube frame, bolted die bed, primer + enamel finish
• Measurement: graduated angle-stop scale (0–150°), 0–10 bar pressure gauge, protractor for calibration

• [Adjustable angle stop] A sliding stop block on a 0–150° graduated scale bar, locked with a wing nut — set the punch stop once for 90°, 120° or custom included angles and every blank bends the same without remarking.
• [Pneumatic drive] A 63 mm double-acting cylinder on 6–8 bar shop air replaces the hand lever — roughly 1.9 kN at 6 bar and 2.5 kN at 8 bar (calculated design targets), so repeat bends are effort-free.
• [5/2 DCV control] One solenoid directional valve handles extend and retract from a single push-button, with quick-exhaust ports fitted for a faster punch return.
• [FRL conditioning] Filter-regulator-lubricator with a 0–10 bar gauge — moisture-free, pressure-regulated, oil-misted air at a dial-set pressure, which is what keeps cylinder seals alive.
• [Interchangeable V-die tooling] A 90° V-die (20 mm opening) and matching radiused V-punch in bolted blocks — the tooling is a separate module, so different die angles can be added later.
• [Fabricated MS frame] Welded square-tube frame with a bolted die bed and painted finish — the cutting, welding, grinding and painting are fully examinable workshop work.
• [Springback calibration procedure] A buyer-run protractor-based procedure with a calibration chart: bend a coupon, measure, record the overbend offset, shift the stop block — repeatable angles from your own data.
• [Viva-ready documentation] Report, PPT and Q&A covering air-bending theory, the force calculation, die-opening selection rules, pneumatic circuit diagrams and safety.

• Welded mild-steel frame with bolted die bed and painted finish
• 63 mm double-acting pneumatic cylinder with V-punch assembly
• 5/2 DCV solenoid valve, FRL unit with 0–10 bar gauge, PU tubing and fittings
• 90° V-die block (20 mm opening) and adjustable angle-stop bar with graduated scale
• Pneumatic circuit diagram and fabrication drawings
• Springback calibration chart and step-by-step calibration procedure
• Project report PDF (background, theory, force calculation, methodology, results format)
• PPT presentation for final review
• Viva Q&A preparation document (air bending, pneumatics, die design, springback)