Laser measurement aids accurate bending of Inconel piping

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Unison's all-electric tube bender with laser measurement is enabling a manufacturer to save money by eliminating scrap when making precision bends in exotic alloy tubes and pipes.

A user of a Unison tube bender fitted with a laser measurement system is reporting significant success, including being able to bend thick-wall, 2.5inch (64mm) inside diameter Inconel piping precisely in one operation, without worrying about errors caused by the material's springback characteristics.

Super alloys such as Inconel are very hard and difficult to bend. For instance, this 2.5inch diameter pipe required bending torques of around 66,000Nm, which is similar to the torque required to bend 6inch mild steel tubing. The cost of the 2.5inch thick-wall tubing in this application is currently around $2500 per foot. If any scrap is produced during the bending of parts, the impact is typically measured in thousands of dollars.

After trials, the user decided the best way to employ the new system is to ignore the usual process of making sample bends to determine a batch of tubing's fixed and proportional springback characteristics, and to simply make the programmed bend. Then, while the part is still on the tube bender, the laser system automatically takes over and corrects as required - thereby eliminating scrap, as well as the time and materials costs associated with making trial bends.

Super alloy materials such as Inconel are often used in aerospace and defence applications, and in applications where strength, high-temperature performance, wear- and corrosion-resistance, and long lifetimes are crucial - such as power stations and oil platforms.

Laser measurement

Unison's new 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.

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 particularly suitable 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 (6inch diameter) all-electric Unison tube bending machine drew only up to 14-15A per phase peak for a few seconds, during the bend and correction operations, before returning to a standby state drawing around 2-3A per phase.

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