Thick-walled 'exotic' alloy tubes bent correctly

A novel metal 'springback' laser measurement, in-process correction system ensures tubing in thick-walled 'exotic' alloys are bent correctly first-time in all-electric tube bending machines.

A novel laser measurement system, developed by Unison, avoids costly scrap when forming precision bends on exotic alloy tubes and pipes.

A user of a Unison tube bender fitted with the laser system reported being able to bend thick-wall, 2.5in (64mm) inside diameter (ID) Inconel piping precisely in one operation The user said it had no longer any worries over errors caused by the material's 'springback' characteristics.

'Super' alloys such as Inconel are very hard and difficult to bend.

This 2.5in diameter pipe required bending torques of around 66,000Nm.

The torque required is equivalent to the torque levels required to bend 6in mild steel tubing.

The cost of the 2.5in thick wall tubing in this application is currently around US$2,500/ft (say about EUR 8000/m).

So any scrap is expensive.

After trials, the user decided the best way to employ the new system was to ignore the usual process of making sample bends to determine a batch of tubing's fixed and proportional springback characteristics.

Instead, the company simply made the programmed bend.

Then, while the part was still on the tube bender, the laser system automatically took over and corrected as required - so eliminating scrap.

Unison's 'Breeze Angle-Sure' laser system works by monitoring changes in the reflection distance of two laser beams.

In operation it takes a reference measurement from the straight edge of the tubing.

Then, after the bend is made, the system automatically commands the clamping die to move away - allowing the material to spring to its natural position - and takes a second measurement from which the actual bend angle is calculated.

Any difference to the programmed bend is displayed, along with a simple selection button that commands the machine to automatically re-grip the tube and apply an additional force to achieve the required angle.

* All-electric tube bending - the laser measurement system is an option for Unison's all-electric tube benders.

Whereas most tube benders today are powered hydraulically, and need to be carefully set up for each bending task by a skilled fitter, Unison's machines employ electric servo motors to control the bending process.

This provides very precise bending under software control, allowing each operation to be configured automatically from downloaded design data, and replicated precisely again and again as required.

The technology is ideal for small batch production environments.

Energy saving is a further advantage of Unison's all-electric machines as they only consume a significant amount of energy when actually performing a bend.

A hydraulic bender, by contrast, typically consumes energy continually, as the system's fluid has to be maintained at pressure.

As a result, all-electric operation can reduce power consumption substantially.

In the bending example discussed here, this large (6in/150mm diameter) all-electric Unison tube bending machine drew only up to 14 to 15A/phase peak for a few seconds, during the bend and correction operations, before returning to a standby state drawing around 2 to 3A/phase.

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