motor dimensioning and racking

[_Nick]

Bye to all,

I have seen that the subject has already been dealt with but in this case the problem is slightly different.
locate the engine and the reduction necessary to drag a load which is constantly in tension.
Let's imagine having a cart tied to the wall through an elastic band, and I have to move it away from the wall.

the resistant voltage is equal to: 10kn. (we can simplify it as a constant force)
the speed to which I have to move the carriage: 1m/min
length rack: 1 m
pinion diameter: 0.2m

I have already obtained results but I would like to compare them with you to understand whether they make sense or not.
Thank you.

 

[meccanicamg]

Hi.
You read the rules you agreed to? No.
Did you show up? No.
Write numbers and reasoning, then let's give you a few tips.

 

[_Nick]

Hi.

Yes, I read the rules.
no, not being there a special section.
Anyway, I'm a 32-year-old mechanical engineer, I worked first in the automotive industry and now in industrial automation.

for the problem I thought:
c_pignone=10kn×0,1m=1000n
ipotizzo transmission ratio =1/00
c_motor=1000/100=10nm
v=1/60=0,0167m/s
No.
n_motor=1.59×100=159rpm
p_motor=10×159/9,55=166,5w

very fast reasoning leaving friction and yields, can you go?

 

[TETRASTORE]

the calculations, neglecting the performance (variable according to the adopted reducer and the number of reductions), are correct; only two observations.
1) c_pignone must be expressed in nm and not nm (see correct calculations, I assume that it is a review).
2) you arbitrarily chose a 100/1 reduction ratio that involves a motor speed of 159 rpm; The standard motors have speeds above the calculated value, so you have to start with the type of engine you need, for example three-phase at 2, 4, 6, etc., poly or continuous current, etc., then, depending on the speed of the engine you can choose the reduction ratio.
If you, for example, adopt a four-pole three-phase motor with 1400 rpm, your relationship obviously should be 880/1 so you would need a combined gearbox.
another important fact that you will have to consider in the choice of the reducer, is the radial load, in your case 10 kn, value that you will have to compare with the admissible one on the exit shaft.

 

[meccanicamg]

Bye.
I'd say the data to use is this.you choose a base squirrel cage engine 1400rpm.
Industrial motors are 2-4-6-8 poly so they have basic rotation turns, variables with inverter if used.
it is wrong to assume a reduction report. a rotation regime is hypothesized near synchronism.

For example, you can mount a gear motor like that attached.

 

[meccanicamg]

Hi.

Yes, I read the rules.
no, not being there a special section.
Anyway, I'm a 32-year-old mechanical engineer, I worked first in the automotive industry and now in industrial automation.

for the problem I thought:
c_pignone=10kn×0,1m=1000n
ipotizzo transmission ratio =1/00
c_motor=1000/100=10nm
v=1/60=0,0167m/s
No.
n_motor=1.59×100=159rpm
p_motor=10×159/9,55=166,5w

very fast reasoning leaving friction and yields, can you go?

Look at the section to show up is qui....and anyway it is good also in your first request or comment post.

 

[meccanicamg]

I usually try to take the smallest possible motor with service factor the minimum indispensable. if the radial load is higher than the one that supports the reducer, I add a bearing in front of the pinion, thus dividing the load in half.
However a calculation should be made otherwise you can find the reducer who dies shortly and you do not understand why.

 

[_Nick]

thank you very much to both for the very useful suggestions.
then starting from the engine:
- in the hypothesis of a three-phase asynchronous motor 4 poles that turns @1400 rpm I would need a 880:1 reducer, ratio that would seem to be quite high
- Considering a 6-pole engine with a rotation system around 900 rpm the reduction ratio would fall to about 630, still quite high.
At this point I would be reduced the diameter of the pinion from 200 mm to 50 mm, in this way the ratio would pass to about 140, this ratio seems much more reasonable, correct?

 

[TETRASTORE]

At this point I would be reduced the diameter of the pinion from 200 mm to 50 mm, in this way the ratio would pass to about 140, this ratio seems much more reasonable, correct?

Yes, it is feasible only if the 50 mm sprocket is compatible with the diameter of the gear shaft chosen in the case of pinion with hole, if you have an integral pinion calettato in the gear shaft there are no problems.
carry, as an example, a selection of a standard three-stage axle motor, adopting a reduction ratio 249.36 and 3.61 rpm with 6-pole 0.25 kw motor and 90 mm sprocket.
the radial load admissible on the reducer is 1500 n applied on the half-carry of the output shaft, so you can not use the standard protruding shaft (with the embossed pinion) of the selected gearbox but you have to build a longer protruding shaft, to calettare in the hollow shaft, to be able to support it on the opposite side of the reducer.
other solution for fixing, is to autonomously support the shaft with pinion and mount the gearbox in a commuter position, contrasting the rotation with a bracket with antivibrating tile or a reaction arm.
Alternatively you can choose an orthogonal axle reducer with similar characteristics according to the encumbrance to be respected.
Obviously, if you further decrease the diameter of the pinion you can choose a lower reduction ratio. qui you can try to configure it.

 

[meccanicamg]

relationships around 300/600 for an endless screw maybe with pre-pair is normal.
an epicycloidal reducer at 4/5stadi also arrives at 6000 of reduction ratio.
Don't scare yourself.
Small sprocket... Huge force to the tooth....always if the tree lies in the hole... .
always pays attention to the feasibility of things.
high ratio...small power if performance is good. engine running at 1400rpm greater efficiency and less energy dissipation.

However... if you want to mount a torque engine i.e. a torque engine and you can delete the gearbox could be a new frontier.

 

[_Nick]

now I have a doubt: but once I move the car with the electric motor and arrive in the desired position, I interrupt the shift what happens at this moment? Does the engine remain in fire to counter the strong force? or is there any kind of blockade that prevents you from losing that particular position?

 

[meccanicamg]

If you want the axis to maintain the position you need to insert the negative brake of the engine.
If you have an encoder in the engine you can also pair the engine but you need the servoventilation otherwise burn the engine. However with fixed torque and zero turns you can not stay there for a long time and if you remove co4ente and the reducer is reversible it moves and you lose the position.

 

[TETRASTORE]

Does the engine remain in fire to counter the strong force? or is there any kind of blockade that prevents you from losing that particular position?

As an alternative to the brake, if there are no shocks or vibrations, you may use an endless screw reducer with pre-pair like that in the attached document (chosen here) which, being an endless screw reducer with a propeller angle of just over 4th, can be considered irreversible statically However, I repeat, in the absence of shocks and vibrations, otherwise you can apply a self-frenating motor.
the reducer in the document is provided for a 240 ratio as in your case and predisposed for iec 80 motor connection, but as a motor it is necessary to predict a power of 0.37 kw to 6 poles (in this configurator the manufacturer indicated only 4 pole engines).
I predicted a gearbox with reaction arm considering the shaft with pinion supported independently.

 

[_Nick]

As for the sizing of the pinion and rack, I have already seen some posts @meccanicamg on the subject, I guess most are of purchase once checked the imposed load resistance just provide pinion diameter and rack length, correct?

 

[meccanicamg]

As for the sizing of the pinion and rack, I have already seen some posts @meccanicamg on the subject, I guess most are of purchase once checked the imposed load resistance just provide pinion diameter and rack length, correct?

of course, once you have made the verification, take a catalog of standard products type claddings and choose from there the most suitable product.
the pinions are in the catalog with standard dimensions and the racks are sold at bars of 2 meters of length usually.