size rack-pignon

[bez]

Good morning, everyone!
I am new and I mean little mechanics because I usually do other things... so forgive my chestnuts and have patience :d

I have to design a system enlivened by a rack. the only two constraints I have are the speed of translation of the rack: v=100 mm/s
and the race that my enlivened object must do: l= 30 cm

I have done some accounts but I don't know if my approach is right.. could you give me a hand to verify its correctness and give me any advice?

what I thought is:
I choose a pinion with module m=1 and number of teeth z=70.
then the step is p= lazy* m = 3,14
primitive diameter d=70 mm
the rack has the same module, so if I want you to translate 30 cm the number of teeth that must have is 30 cm/3.14 mm = 96 teeth about ...

I calculated the transmission ratio as u= (2*pigreco) / (p*z) = 0.0286
then the speed at which the engine must turn: omega= u * v = 2,86 rad/min

What do you say? demolish me!! :

Thank you!

 

[bez]

I'm sorry! I'm wrong... speed is v= 100 mm/min

 

[Fulvio Romano]

Where we see a little...
- you did not show up in the specific area, as required by the forum rules
- you posted the same question in two different forums, as prohibited by the forum rules

[...] I mean little mechanics because I usually do something else.[...]

I have to design a system enlivened by a rack

but why do they design mechanics to those who do not mean mechanics? It's like I'm taking the car to fix it by fruiting it, or asking an engineer for medical or legal advice.

Well, shut down the parentheses, I try to answer your question.

you say the primitive diameter is 70mm. the speed of the rack is equal to the peripheral velocity of the primitive diameter. Why start talking about module and number of teeth at first?

If d=70, it means that c = 2pir = 219.8mm
If the wheel turns to n turns per minute and you want to get 100mm/min do 100/219.8 and get 0.45 turns per minute of the wheel, equal to 2.85 rad/min, more or less what you find, apart from rounding.

but this is not the speed of the engine, but that of the pinion. Find me on the market a motor that turns to 0.45rpm...

between the engine and the pinion, I would put a reducer that will carry the motor that will turn about to 3000rpm (depending on the motor) up to 0.45 with a rather short reduction ratio. I would tend to solve with endless screw reducer.

Finally a question.
Are you studended, it means that "I have to design" means "the professor wants to see the homework, so it is not necessary that it really works", or 'sta robba must run seriously?

 

[bez]

First of all I apologize for the various errors made both in the forum and in the presentation of the problem and thank you for the very exhaustive answer. .

In any case I said that the primitive diameter was 70 only because I have no idea where to start by taking care of engineering fabrics and not mechanical...so if she were so kind to suggest how to proceed without firing random numbers (as I obviously did) I would be very grateful.

As for his curiosity... the professor doesn't want to see the project. I have to make a dip coater because otherwise I can't continue with the project that has nothing to do with mechanics... they have put me to design it because buying one would cost too much... and who knows...maybe I learn something new that never hurts

Thank you.

 

[Fulvio Romano]

I have to make a dip coater because otherwise I cannot continue with the project that has nothing to do with mechanics... they have put me to design it because to buy one would cost too much

in 99.9% of cases, buying an object that works costs much less than designing it, making it build ad hoc, testing it, doing it again because it was not good, keeping it, etc.
if the translation mechanism of the electric gates costs too...have been put quite badly:smile:

I would start from the purchase of a gear motor. Note the output power and speed you should be able to choose one at the catalog. at this point, knowing the output speed of the motor axis (which will not be exactly the same as what you want) calculations the primitive diameter of the pinion. then buy pinion and rack, or make them build to design.

So, let's say, the opposite of what you followed. but mine is just a suggestion.

p.s.
What is a dip coating? I have some familiarity with such a process, probably the problems are completely different. I hope you're not thinking about creating a bridle of tension in this way...

p.p.s.
usually on the forums you give yourself some.

 

[bez]

ah perfect...somma for today is not reset one! will be better tomorrow!
a dip coater is a tool that allows you to make later dives of a substrate in a solution so as to get thin films of material on the substrate.
Thank you very much for the advice!

 

[sampom]

if you have to move 300mm the rack will be long at least 300mm (extension of a good 10% before and after start and end run), regardless of teeth and module (the latter obviously will be the same as the pinion).

if you consider a rotational speed of 1giro/min the pinion will have primitive circumference of 100mm, then øp=31.83mm. with this data choose m and z according to the "standard" module tables, following the formula øp=m*z. the modules are 1 - 1.5 - 2 - 2.5 - 3 - 4 - 5 ...
Of course you will have to approximate and, considering that module 1 you said (so small, sure? What do you have to translate? that "object" you attached to the rack?), you get out a 32 tooth wheel. half z=16 (do not descend under 12/13) so the rotation will be 2gir/min.

the problem, as mentioned by lightning, will be in the motorization. because motors with such a high ratio (it is spoken of 1:700 with motor 4poli at 1400 turns) are "particular" and expensive and the endless lives (the cheapest but with the worst yield) do not arrive; we are at the max around 1:100.
You should interpose a further reduction with a chain transmission for example, to further reduce a 1:7.
you can also put the engine at 900 rpm and, if you don't have a particularly heavy use, go down again with our teeth until around z10...
the use; remember that to dimensional the gear motor (power/coppia) and the pinion (choice of the module) you need to know that load you have to translate and in what conditions.

at the end as said, if there is something on the market beautiful and ready will certainly be cheaper and functional from immediately :biggrin:.

greetings
Mar

 

[bez]

Thank you very much... I have only a few questions arising from my ignorance in this matter.. .
you wrote that if I consider a rotational speed of 1giro/min the pinion will have primitive circumference of 100mm, then øp=31.83mm. I didn't understand why... Sorry :
and the standard modules tables where they are located?

I have not written anything about the weight that must be made to the rack because it is in order to say so much of the etti...no stratospheric in short.. .

Thank you very much again for availability!

 

[meccanicamg]

if you do a search you will find my answer with attached image of the cinematism of the racket lazy with the formulas attached

However it should be dimensioned all not only at speed but also at resistance and fatigue as well as wear regarding pinion and rack and everything.

 

[bez]

grazie!

 

[sampom]

you wrote that if I consider a rotational speed of 1giro/min the pinion will have primitive circumference of 100mm, then øp=31.83mm. I didn't understand why... Sorry :
and the standard modules tables where they are located?

It's arithmetic snitch. . You say you have a speed of 100mm/min, so 1giro/min will be 100mm, right? a round is a circumference, the diameter is equal to circumference/pi, and how much does 100/3.141592... ?:smile:

I told you the modules.
otherwise you find them in mechanics manuals, in catalogues (try clavals), on the net.. or ask a supplier of technical articles, which you will also need to do for the search for motorization.

greetings
Mar

 

[bez]

learning everything in one day was so heavy that I had a fever! ahahah!
cmq thanks a thousand guys... now I have the clearest ideas! even though....something tells me that I will tartase you again!

 

[Focus]

the problem, as mentioned by lightning, will be in the motorization. because motors with such a high ratio (it is spoken of 1:700 with motor 4poli at 1400 turns) are "particular" and expensive and the endless lives (the cheapest but with the worst yield) do not arrive; we are at the max around 1:100.

greetings
Mar

the "double" vf/vf or vf/w series of bonfiglioli arrives well beyond 1:100, they are reduced with very low yield but in some cases they can return useful.

Hi.

 

[bez]

if you have to move 300mm the rack will be long at least 300mm (extension of a good 10% before and after start and end run), regardless of teeth and module (the latter obviously will be the same as the pinion).

if you consider a rotational speed of 1giro/min the pinion will have primitive circumference of 100mm, then øp=31.83mm. with this data choose m and z according to the "standard" module tables, following the formula øp=m*z. the modules are 1 - 1.5 - 2 - 2.5 - 3 - 4 - 5 ...
Of course you will have to approximate and, considering that module 1 you said (so small, sure? What do you have to translate? that "object" you attached to the rack?), you get out a 32 tooth wheel. half z=16 (do not descend under 12/13) so the rotation will be 2gir/min.

the problem, as mentioned by lightning, will be in the motorization. because motors with such a high ratio (it is spoken of 1:700 with motor 4poli at 1400 turns) are "particular" and expensive and the endless lives (the cheapest but with the worst yield) do not arrive; we are at the max around 1:100.
You should interpose a further reduction with a chain transmission for example, to further reduce a 1:7.
you can also put the engine at 900 rpm and, if you don't have a particularly heavy use, go down again with our teeth until around z10...
the use; remember that to dimensional the gear motor (power/coppia) and the pinion (choice of the module) you need to know that load you have to translate and in what conditions.

at the end as said, if there is something on the market beautiful and ready will certainly be cheaper and functional from immediately :biggrin:.

greetings
Mar

Hi.
I've been following your advice and I've been making some calculations. Does it make sense to consider maybe a rotation speed of the pinion at least 4 rpm? because so I can decrease the reduction report a bit, but from what you wrote, it seems to me that it is not a good idea....

 

[sampom]

the series "double" vf/vf or vf/w of the bonfiglioli arrives well beyond 1:100, they are reduced with very low yield but in some cases they can return useful.ciao

Yes, but they are much "big" than it can serve you.
In fact, in the sizes in question you get to max. I=70.

Hi.
I've been following your advice and I've been making some calculations. Does it make sense to consider maybe a rotation speed of the pinion at least 4 rpm? because so I can decrease the reduction report a bit, but from what you wrote, it seems to me that it is not a good idea....

for what is said above the situation is even worse; with ratio 1:70 and engine from 900giri arrives at a speed of 12.8giri/min to the pinion. then said lazy should have circonf. of 100/12.8=7.81mm.. definitely improbable.
you will be obliged, as I told you, to add a further reduction (type chain transmission) that leads to having the turns you need.

Really,
if you are looking for commercial solutions already ready, you will definitely agree.
otherwise you must "design" another kind of transmission that is not with pinion and rack.
maybe a linear motor, screw and bolt etc. etc.

If you better explain the application and maybe place a graphic scheme with the data of the forces in play you could help in the "configuration".

greetings
Mar

 

[bez]

a dip coater is a tool made like this:


is used to dive later than the substrate into the becker containing a solution to create polymer films.

the important thing is that the rod parallel to the table of support beams to constant speed otherwise the deposition of the film is not homogeneous.
speeds above or equal to 200 mm/min give non homogeneous films and this I know because in university there is a dip coater, but it is high one and a half meter and heavy mooolto... I have to make it quite small because, since the solution used is toxic) you have to work under hood.. .

the only forces in play are the weight of the rod parallel to the countertop and the weight of a support for the test to dive that is fixed to such rod...

I assure you that I would prefer to buy one! but I can't... I have received orders from above: ( looking on google I found that in many have made it we say homemade (so it can't be so intrusible as what)... but obviously they don't say how

Thank you so much!

 

[bez]

before lazy and racket I had also thought of an endless screw system.. .
but apart from the fact that having never seen a pipe of these things I can not see it well as it is clear to me the functioning of the pinion.. .
In fact, if I think I use an endless screw, I don't understand how I can spin it... like the engine attack?

cmq apart from my infinite ignorance. Is that a better idea?

 

[Fulvio Romano]

cmq apart from my infinite ignorance. Is that a better idea?

to do something like this, I would use a double screw-shaped system, so avoid the reverse of the engine.
In practice you have a screw with two helical grooves moved by a motor. on the screw flows a sleeve, as for the screws recirculation of spheres. when the pigeon arrives at an end, it passes from one groove to another, wintering the bike. so the 'thing' goes up and down, but the motor turns at constant speed.

Now I don't have time to look around, I see if I find anything tomorrow. However it is a very common method, also used in toys. maybe someone does before me and post some drawings/photos?

 

[sampom]

a dip coater is a tool made like this:

. What a dip coater I knew. I just thought of something "more industrial."
yours is a "game" for which you need to change the type of search; I'd turn to the electric scooters. The single-phase power supply is also more suitable for a bench/workshop tool.
do a research and try to hear these producers:http://www.brevettirf.com/italian/motori_universali_d.60.php?iexpand1=13http://www.elleemmesas.it/realizzazioni.asp?t=elettrodomesticialso require a solution that includes the electronic control part with speed regulation etc.

it is not my field, in fact so far I was talking about industrial applications with motorizations decidedly too big for your case (although the smaller ones).
ask also for all full transmission, those use special ingranaggeria also in plastics that can do to your case.. I don't know all the products in that sector.

do not go crazy in projects and calculations, at least those parts you find usable commercial.

greetings
Marco:smile:

 

[Fulvio Romano]

see here:http://www.cad3d.it/forum1/showthread.php?t=6565find the tree I said, but I don't know where to buy it.
here instead you can find engines, motors and servants that I think can suit you, and they really cost little:http://www.robot-italy.com/index.php?cpath=8