Down time and through put is a big deal in any process, so any time you can measure without disassembly and incurring excessive down time it generates huge savings. American Industrial Metrology has developed and patented a process that does not require access to the roll surface to determine roll alignment.
This procedure was used in a Continuous Galvanizing line (CGL) recently to measure the rolls in the vertical furnace. The mill was experiencing as many as 15 strip breaks a month in the furnace area alone, all related to off tracking in the furnace. Using the AIM method there was no disassembly of the furnace, in fact the mill even kept heat in the furnace. A projected off tracking of as much as 3” to the drive side was predicted by the survey.
The survey took less than 10 hours to measure all of the 38 rolls. By exporting the data to AIM’s proprietary strip tracking worksheet, 2 rolls were identified as causing 80% of the tracking issues. These 2 rolls were adjusted according to the data. On startup the mill experienced almost no tracking issues in the furnace. The predicted off tracking of 0.5” was actually shown to be less in running conditions.
Subsequent fine tuning of additional rolls created a situation where the mill only experienced 2 strip breaks in the following months, unrelated to off tracking, but identified as weld related.
The mill has subsequently upgraded its drives and has been able to run at 500FPM as opposed to 350FPM and strip break incidents have been reduced further to 2 per year. This was achieved at minimal cost and resulted in a significant reduction in down time as well as a major increase in though put.
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