TPT May 2009

I nspection, M easuring, T esting & M arking

the process when a mandrel fault occurs allows removal of the defective part, and prevents production of additional scrap material or possible collateral damage to equipment. Figure 3 shows a production log file from the monitor indicating a mandrel fault during the first bend in a four bend part, and subsequent recovery to steady, stable production after repairs. In monitoring the mandrel pull force through every bend cycle without adding time or processing steps, the PVM2000-MB™ mandrel bend monitor provides an alert to potential issues before they become real problems. This pro-active system measures the process variance on a machine for every cycle of production, detecting problems at source, often well before they become quality issues. Early detection of a degrading process reduces scrap, and saves unnecessary downtime and machine repair. OES Inc – Canada Fax : +1 519 652 3795 Email : oes@oes-inc.com Website : www.oes-qualityassurance.com

 Figure 3 – A production log file from the monitor indicating a mandrel fault

in order to find the true ‘pulse’ of the process, which in mandrel bending exhaust tubing is detection of the pull force during the bend cycle. Strategic placement of a piezoelectric sensor captures representative force feedback while remaining completely clear of the business end of the machine. Figures 1 and 2 show the pull force captured during normal operation and then when a typical process variance was induced to demonstrate the effect on the force involved; there is loss of lubrication (figure 1) and misalignment in the setup (figure 2). An effective process variation monitoring system comprises 3 elements: a sensor, an intelligent control module and a user interface. The PVM2000-MB™

mandrel bend monitor from OES utilizes a piezoelectric strain sensor mounted on the mandrel rod housing. This provides input to the control module in the electrical cabinet connected to a touchscreen 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 touchscreen. If a bend is within tolerance it passes and the process continues. If it is outside of tolerance the process variance is indicated and the process can be interrupted as required. The PVM bend monitor will catch a broken mandrel due to sudden excessive tension or as a result of a fatigue break. Stopping

 Figure 4 – The PVM2000-MB™ mandrel bend monitor from OES

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tube bending machines tube end forming machines automation systems tube cutting machines tube cleaning systems

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