Vibration control of looms

[sac79]

We need to reduce vibrations transferred from rapier loom to the building structure and also have to ensure that the machine vibrations do not increase. Kindly suggest any solution/s. Thanks in advance.

 

[rb1957]

vibration isolators ?

I assume your loom is sitting on several legs, fixed to the biulding floor. if you add isolators under the legs, i think you'll need to add structure to the connect the legs together (ie to recreate the loadpath that the floor is providing now).

 

[drawoh]

sac79,

The obvious thing to do is to mount your loom on anti-vibration mounts.

The non-obvious point is that mounting your loom on flexible mounts, as rb1957 notes, is not absolutely simple. My experience at a similar task was quite different, but still very weird.

Re-mounting your loom is a design job for someone who understands structures, vibrations, and how you loom works.

JHG

 

[Tmoose]

Transmitted vibration will be less thru isolation mounts, but Almost by definition an isolation mounted machine will have higher vibration than a rigidly mounted one, unless resonance was involved when rigidly mounted.
More vibration info is needed, re: amplitude and frequency. It would be a shame to re-engineer a machine that just needed the loom rotating frame balanced.

Or are reciprocating motions involved?
Again, detailed vibration analysis often can easily cut out 90% of the trial and error.

An analogy would be shooting at a target I know is somewhere in a dark room, without night vision goggles, unless you are Clarisse Starling.

Dan T

 

[unclesyd]

Here are links to the three approaches we used to isolate blower fans, spinning machines, and other textile machinery.
We used lead, and composite pads where for a certain range of vibrations. The Lord product was used on the high speed machines. Nearly all the air movers, around 100, were isolated with the Firestone product.

http://www.marsmetal.com/sheet-lead/vibration-damp/

http://www.lord.com/

http://www.firestoneindustrial.com/north_america/

One thing we finally started doing was to put the machinery on isolated bases, either by pouring in place or cutting out a base from monolithic floor, This method was retrofitted if if the slab was at least 6" thick under the machine.

 

[FeX32]

If I read you correctly, the easiest solution would be one that does not incur modification of existing structures.
Thus, a tunned vibration absorber (TVA) could be simply designed and mounted on top of the rapier loom.
Here is a start:

http://hpgavin.pratt.duke.edu/TunedVibrationAbsorber.pdf

Fe

 

[MikeHalloran]

I looked it up. A rapier loom lacks a shuttle, but instead transfers fill thread across the width of the machine by means of one or two rapiers, or swordlike probes. I'd guess there's a fair amount of reciprocating mass.

I'm guessing that mounting the machines on mounts that are very loose in the transverse direction, even on rollers or something like a porch glider, would allow the entire machine to move and react to the excitation from the rapiers.

The traditional solution, for arrays of looms, is to drive them all at slightly different speeds, e.g. by lineshafts with pulleys of differing diameters or with specially wound electric motors that are not all synchronous at the same line frequency, so that destructive reinforcement of vibration forces among the looms is made less likely.



Mike Halloran
Pembroke Pines, FL, USA

 

[zekeman]

This is way too complex to get an easy solution here.

The transverse oscillating masses preclude any of the solutions suggested so far, except for Mike's suggestion of phasing if applicable.As a followup thought, maybe phasing the mass motions of several machines to oppose each other may be possible, or mounting the machines at different orientations.

Perhaps, the manufacturer of the loom could offer some recommendations, or a skilled vibration consultant could be called in.

 

[FeX32]

I'm surprised that such a large machine is not balanced to begin with.
Large moving masses indicates non-optimal design. (unless there is something i don't know..)

Also looks like someone else has a patent related:

http://patents.justia.com/1998/05799706.html

Fe

 

[FeX32]

Also found here:

http://www.google.com/patents?id=cL...&resnum=1&ved=0CCkQ6AEwAA#v=onepage&q&f=false

Fe

 

[rb1957]

maybe it was but isn't now (wear and tear, "somebody" did something, ...)

 

[unclesyd]

A lot of the design parameters depend on when the machine was designed and built. Once you built it you went with what you had.
It wasn't until the advent of the computer age that any work went into lowering of the noise and vibration levels on textile machinery. Early on it was very hard to even to get some idea of the vibration spectrum let alone figure out what to do with it. A few things the early designers did accomplish was some reduction by decoupling the drives, splitting up long drive shafts, making the frame from ductile iron, to name a few.
Probably it was the formation of OSHA that drove a change in mind set of the designers, it certainly wasn't for worker comfort. There was no problem in replacing a machine operator if they had to leave for medical reasons.
One big thing about textile machinery is it was designed for a certain speed which was usually double or tripled on the floor.
We tried mass dampeners on several of our machines with no discernible decrease in the vibration levels, i was told the machine frames were too flexible for it to work.
On some machines we used DC drive where we could slightly change the speed to eliminate synchronicity between the machines. A standard measurement for through the floor measurements was a petri dish filled with water where you looked for a standing wave.

You have never witnessed vibration and noise if you didn't visit and old textile mill using overhead belt drives.