balance of a pulley

[fagil90]

Good morning to all,

I find myself having to remake the pulley of a machine from scratch, that is new dimensioning and production. the dimensions I can calculate them with the formulas having at my disposal the flywheel and all the various turns per minute of all the organs of movement.

My questions are two:

- with the value I get of primitive diameter for the pulley, roasting for excess or defect? ?

First of all:

- Do I have to perform a static and dynamic balance?

Thank you all for your help.

 

[meccanicamg]

the balance you do if you turn to high regimes, at least statically

 

[Max-C]

- with the value I get of primitive diameter for the pulley, roasting for excess or defect? ?

I don't know how much your value is but I would choose the pulley with the highest primitive diameter close to the one you found.
if you want you can round it by default and check but I do not see the usefulness if not for particular reasons. . .

 

[MBT]

- with the value I get of primitive diameter for the pulley, roasting for excess or defect? ?

depends on whether, in doubt, you prefer a few more rounds per minute or a few turns per minute less...
unless everything is controlled by inverter and retroaction, which allows you some freedom

- Do I have to perform a static and dynamic balance?

and blessed by the signoor... and what do we know about what you need?
What mass does the pulley have?
How many trotterella turns?
if it swings because of lack of balance, what happens?

 

[fagil90]

starting from the fact that the pulley is only to be restored, that is, all the rest is already there. therefore I have to remake this pulley over the motor, which is on the regime of 1465-1480 g\min (the motor is a 75 kw). the diameter of the pulley should be around (use the conditional because I do not yet have certain data of the flywheel and of all the cinematism, I went to spans) 350 mm .

the mass of the pulley I do not know, as the old is not there, as well as and what are the effects of its rotation! I would take as reference other pulleys that I have already built, so with discharges and everything, I asked only if "basic" there is to make a balance or I realize only to assembly and final start!

 

[meccanicamg]

everything that rotates has an intrinsic eccentricity and therefore placed in rotation generates a vibration, stronger as the rotation regime increases as long as you reach the critical speed where the shaft oscillates at unmistressing and breaks....ergo must be balanced at the bench before you mount it.

 

[fagil90]

Ergo thing devo fare?

 

[pollo]

Ergo thing devo fare?

Ergo, check it out and see where you end up working. So, if you're troubled, otherwise leave it alone.
so find out if for a case like your you need verification and for next time do first

 

[fagil90]

That was the answer I was looking for. to know if I had already planned a reduction or increase in mass or to wait for some effects to assembly completed.

remains the fact that I am oriented to realize a pulley as symmetrical as possible, hoping it will affect positively. I never had any problems like this since I had the "copy" of the pulley to restore.

 

[pollo]

see without specific data we can not use the eyemeter, as much as it can apply.
the only possibility is to verify everything, and then see if you have to intervene further.
even if you realize that the verification was useless, you will actually need it for the next time.
Hi.

 

[fagil90]

specific data what are they? engine spins? transmission report? I have not specified them now because they are in the process of preventive work, but as soon as the commission leaves, I will have more precise data.

 

[fagil90]

I open the topic.

rotary pulley at 1700 g\min directly on the motor shaft.
the length of the shaft does not reach the length of the pulley so I have to download a little inside.

Can the draw or weight of the pulley make me trouble? ?

 

[meccanicamg]

I open the topic.

rotary pulley at 1700 g\min directly on the motor shaft.
the length of the shaft does not reach the length of the pulley so I have to download a little inside.

Can the draw or weight of the pulley make me trouble? ?

the tension of the belt creates a force on the pulley that makes the shaft sting slightly, so the bearing must support correctly otherwise the pulley turns flickering and creates vibration and premature wear of the components on the axis.

 

[fagil90]

so more than a different geometry of the pulley, do I have to look at the bearing how much load it holds? ?

 

[MBT]

Sure.
and you must also look that the protruding part of tree (where the pulley is attached) is sufficiently rigid!

 

[fagil90]

ok, calculate the straps pull and compare it with the dynamic load of the bearing (I opted for a adjustable roller since the pulley is over).

Sure.
and you must also look that the protruding part of tree (where the pulley is attached) is sufficiently rigid!

You mean I have to check it down? ? ?