I want to measure dynamic thread tension on an industrial sewing machine
without affecting the thread tension.
Is there a strain or tension gauge that can act as a spring as well? The
notion being to replace a tension spring on the machine with the gauge,
adjust the gauge spring for proper thread tension and then the gauge could
provide dynamic tension readings as the machine operates.
Any thoughts appreciated!
That's pretty much how a strain gauge works. A calibrated 'spring'
deforms a known amount under a given tension. The sensor is actually
measuring the deformation of the spring.
Most strain gauges don't have a broad range of travel, so the spring
must be pretty stiff. If this isn't possible, then some sort of cam or
lever arrangement can translate a small amount of beam travel into the
required distance. Or some other position sensing can be used with a
more flexible spring.
One thing you may need to consider is the dynamic characteristics of the
system. If the tension being measured changes rapidly, the added mass of
a position sensing system, or beam, strain gauge and cam system may be
too high to follow the thread accurately. The readings will lag the
actual thread tension. Worse yet, the sensor mass may adversely affect
the thread tension and break it.
Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com
Or, use the existing spring and just put an instrument on the fixed end
where it's mounted.
That way the mass will not affect the dynamic movement, the spring will be
the original so no changes to that, and the force the spring exerts on the
mount will be very close to the force the spring exerts on the thread.
done with a tool called a Tentelometer. I don't know if they are still in
business, but you can google for them. Their gauges are pricey , but they do
measure dynamic tension. I still have one and it'll cost you at least an arm
if you are interested. This gauge is not the kind of thing that you would
want to leave connected all day and it doesn't provide feedback to control
tension, it just measures it.
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