PFFC - January 2008 - (Page 42) TECHNICAL REPORT ROLL ALIGNMENT The views and opinions expressed in Technical Reports are those of the author(s), not those of the editors of PFFC. Please address comments to author(s). Parallel Protocol oll alignment is a requirement for every converting process that produces some sort of web, film, or coating. When a machine is first installed, each roller should be measured to be tram (horizontal) and level (vertical) with the machine. Components and parts of a machine can shift outside the original specified tolerances over time. Many converting processes run at extremely high speeds, to 5,000 fpm, making roll alignment even more crucial. Any misalignment can lead to a variety of different operating issues. Tracking, tension, and coating problems are just a few of the many issues that can lead to unplanned downtime. There are several methods available for checking roller parallelism. The most common measurement is by optical means, otherwise known as theodolites. For theodolites, line of sight is required and the measurement can take place only on one plane at a time. Since many parts of machinery are not accessible due to encased or hard-to-reach rolls, traditional optical means cannot carry out an entire measurement. Due to such limitations, a complete survey of roller alignment has been difficult to achieve and very time-consuming for customers. R Inertial Roll Alignment Technology A new technology designated PARALIGN has been developed for measuring roller parallelism simultaneously in the tram and level position. This system uses inertial technology to achieve a roll alignment survey of an entire process. It uses three ring laser gyroscopes to measure a roll’s relative position in space regardless of line-of-sight issues or subjective readings. The software is capable of producing a complete graphical and numerical assessment of an entire machine in a fraction of the time it normally would take for an optical team. The unit is approximately the size of a loaf of bread and weighs about 20 lbs. It is a completely self-contained system that has no mechanical moving parts inside. Figure 1 shows the approximate location of the three ring laser gyroscopes in the system. The three positions are called roll, pitch, and yaw and are arranged perpendicular to each other. Each gyroscope is capable of detecting even the smallest of spatial movements. Figure 2 represents the anatomy of a ring laser gyroscope in which two HeNe lasers are emitted in opposite directions between three mirrors. Figure 1. Transparent image of the inertial roll alignment technology depicting the location of the three ring laser gyroscopes. Figure 2. Ring laser gyroscope. Direction of Rotation Mirror Power Cathode Cavity with HeNe laser Housing Three built-in high-precision laser gyroscopes—arranged perpendicular to each other—detect even the smallest of spatial movements. Anode Semitransparent mirror Detector (photo diode) Mirror 42 | JANUARY 2008 WWW.PFFC-ONLINE.COM http://WWW.PFFC-ONLINE.COM
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