| 摘要 |
Tension in a moving web is measured by subjecting the web to an ultrasonic pulse train and measuring the time interval for the resultant transverse waves in the web to proceed a known distance past a point upstream (or downstream). The composite web plus wave velocity is calculated and the web travel time is added (or subtracted) to obtain wave velocity which is related to tension in accordance with the equation T=a2w/gc, where T=web tension, a=wave velocity, w=mass per unit area and gc=lb mass ft/lb force sec2 conversion factor. |
