Mandrel benders are designed to bend tube to a tight radius with little to no change in the shape of the tube. Typically a mandrel bender is needed when bending thin wall tubing to a radius much tighter than the material can bend without collapsing or distorting. Often this is a highly automated process using robotic and CNC bending machines to produce high volumes of complex tubes, each one formed to precise specifications without human intervention (except perhaps loading and unloading the tube).

Unseen, unknown, and unresolved process issues in mandrel bending lead to premature tool wear, unexpected equipment damage, and costly downtime. Even worse are undetected mandrel faults or poor quality parts being produced and shipped without any realization of a quality issues.

For this reason, process variation monitoring is a necessary practice to detect quality issues such as loss of lubrication, galling, tube slippage or misalignment, out-of-spec material, or a change in material hardness.

World-leading tube bending and endforming technology specialists, AddisonMckee, immediately recognized the potential for this technology within the industry and the value of this system to their customers.  With an industry-wide reputation for reliability, repeatability and high precision, AddisonMckee has invested considerable time and effort investigating how it can raise the bar further on finished component quality via the implementation of a monitoring process designed to highlight even small variations in mandrel performance.  To that end, AddisonMcKee offers the PVM2000-MB as an option on their line of mandrel bending equipment.

How It Works

Process monitoring for mandrel bending involves sensing the pull or tension force on the mandrel rod during every bend cycle. Pull force (or lack of) on the mandrel rod is representative of the stress on the mandrel links that retain the articulating mandrel ball assembly. A change in this pull force or stress on the mandrel that exceeds the normal control limits is a direct indicator of process variance and degradation.

The set up of any process variation monitoring system comprises 3 elements; the sensor, an intelligent control module and a user interface. The PVM2000-MB utilizes a Piezo electric strain sensor mounted on the mandrel rod housing providing input to a control module in the electrical cabinet connected to a touch screen for the operator interface. The control module analyzes the relative pull forces on each production bend cycle relative to a learned reference and programmable tolerances, displaying the results on the Operator Touch Screen. If a bend is within tolerance it passes and the process continues. If it is outside of tolerances the process variance is indicated and the process can be interrupted as required.