In-cycle bend measurement eliminates scrap for tube workers

Unison has developed a laser measurement module for its all-electric tube bending machines that dynamically measures the accuracy of bend angles and automatically compensates for any errors. It allows manufacturers to bend tubing to the required angles without scrap - overcoming the common problem caused by variances in the 'spring back' characteristics of materials from different metal production batches with minor differences in grain and temper. The new module is targeted at manufacturers of precision and high-value tubular parts, such as those used in shipbuilding applications. The non-contact optical measurement system, the Breeze Angle-Sure, measures bend angles 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 system automatically calculates the required adjustment, taking into account the actual spring back characteristics of the tubing material from the first bend. It ensures that angles can be fabricated first time to accuracies of +/- 0.2 degrees, and can be fitted onto Unison's Breeze family of tube bending machines for tubing diameters of 3 inches/75 mm and above. Unison developed the Breeze Angle-Sure measurement system to support a recent order from a defence equipment contractor. This manufacturer typically produces precision tubular parts in single or very small batches just-in-time, to support ship production. As parts are often fabricated from exotic alloy tubing that can cost as much as $2000 per foot, the impact of scrap can be huge.