# Need help with Homework

Discussion in 'General Off-Topic Chat' started by Youkai, Sep 27, 2010.

# Need help with Homework

1,486 Views
1. ### YoukaiDemon

Member
6
Jul 1, 2004
Germany , NRW
Well I am in "trade school ?" (dunno if this really is the correct translation)
and yeah I missed some days because I was ill and now I just have no clue how to solve my homework -.-V

Hope anyone here knows how this works

1. A Column Drill has a turning frequenz transformation Ratio of 3:1 and 5:3. Calculate the frequenz when it turns with 1250 1/min

2. The Work spindle at a milling machine get its power over a "teilübersetzung?" 2:3 3:4 and 4:5. How big is the complete "übersetzung?" (not the same übersetzung as translation)

3. what polishing frequenz do you get if the frequenz of the motor running at 1440 1/min runs over two "teilübersetzung" of 1:3 and 1,5:4 ?

4. a double "übersetzter" belt drive has two "teilübersetzung" in the same size of 2,25:1. research the "teilübersetzung"

Well ok translation sucks bad i think oO
still hope someone has an idea what I am talking about (i have none XD)

------------------sample pics---------------------------

2. ### VehoThe man who cried "Ni".

Former Staff
17
Apr 4, 2006
Zagreb
It's called gear ratio, I think. Multiply all the transformation ratios (gear ratios) and you get the total gear ratio. Then divide the frequency/speed of the drive with the gear ratio and you get the speed of the end element. So if the motor speed is 2000 1/min, and the gear ratio is 2:1, then the frequency of the working spindle is 1000 1/min.

So,
1) 250 1/min
2) 2:5
3) 11520 1/min
4) 5.0625:1

I think If the Übersetsungsratio is the reduction ratio, then you multiply the drive speed with the ratio to get the end speed. Gear ratio is 1/(reduction ratio). In that case,

1) 6250 (that's a bit much)
3) 180 (that's a little small).

But I think it's the gear ratio.

Banned
0
May 21, 2009
Virginia
Looks dull.

4. ### YoukaiDemon

Member
6
Jul 1, 2004
Germany , NRW
Hmm the second one sounds correct ...

just found these two pics i think they might help me ... i will try to confirm your solutions

--------------------

man I have not the slightest clue -.-V

5. ### VehoThe man who cried "Ni".

Former Staff
17
Apr 4, 2006
Zagreb
According to those pics you found,

i = Übersetzung = n1/n2 ;

That means n2 = n1/i

And that's the first set of solutions. The pics confirms: i>1, Übersetzung ins Langsame; if i is greater than 1, the end frequency is lower than the initial frequency.

6. ### YoukaiDemon

Member
6
Jul 1, 2004
Germany , NRW
yes it was correct only the 4 was wrong

should have been like this :

iges = 2,25:1
i1=i2
i1= iges
i1= 1,5:1 =i2

man if that would be just all i might be able to understand our teacher allways shouting at us how easy it is -.-V but we have to know way more than just this ...
we are as well calculating longitudinal strength of different metals and such ...

I think i will try to get a befriended private tutor to help me (if he is able to) else i need to hope for my best chance a Math and Physics teacher who is in the same sports club as i am
// my main problem really is to understand which value is what
like whats n1 n2 n3 ....
its my luck we are allowed to use the book in the class tests but as long as i miss out which value has what sign i am done for ...

P.S. there were only like 3 ppl in the class who had done the homework because noone was able to ! (and somere just slacked off)
he still was mad at me only having the solutions -.-V

7. ### VehoThe man who cried "Ni".

Former Staff
17
Apr 4, 2006
Zagreb
I see. I misunderstood the question, I thought each segment was 2.25:1, not the Gesamtübersetzung. Yeah, iges = i1*i2, and if i1=i2, then iges = i12, and i1 = i2 = ?iges

Well at least you had more homework done than most of your class
And good luck with your classes

8. ### YoukaiDemon

Member
6
Jul 1, 2004
Germany , NRW
yeah thanks but i REALLY hope that we do not need this for our final exams ...

i can't understand why we need to learn something like this even thaught our only job is to make stuff out of the drawings and material we get ...
everything else is done by engeners and whatever there is ... (if i would want to become one i would need like 2-3 years for technician and than again some years so why learn something like this now -.-)

9. ### VehoThe man who cried "Ni".

Former Staff
17
Apr 4, 2006
Zagreb
Knowing how your tools work is always useful

10. ### FAST6191Techromancer

Reporter
21
Nov 21, 2005
I thought you are training to be a fabricator?
Gearing comes in when you are setting spin speeds- high spins speeds will kill cutting tips/edges faster than you care to know and too much heat can easily destroy qualities imparted on a material and cause issues and on the other hand too slow a speed will mean it takes ages (or you get a bad finish) for no real gain. I am sure we have all snapped a drill bit (thinking pillar drill here) by being overeager with things and if you are either on piecework (paid every 200 parts you make or something like that) or you repeatedly hold up something mission critical because you are heavy handed with the machinery and you will find yourself looking for a new job in fairly short order.
Similarly the engineering drawing/diagram you get will probably (not always and definitely not if you are playing with some of the more exotic materials) just say this needs a chamfered edge at given dimensions and leave it up to you how you get there.

They will probably set it up in a few lessons to apply torque and spin speed (a minor twist on conservation of energy and/or pressure equations and maybe efficiency and rotation direction as well) and a bit after that will cover all the various tooling types/materials (Schnellarbeitsstahl and things like it if my search engine has not failed me) and cooling methods (air, water, oil). Learning about gear ratios is fairly fundamental to that and a lot of people I have seen with problems at that level have a fairly weak feeling for the ideas behind gear ratios.

Similarly if I am playing engineer I will certainly have a chat with some fabricators (and ultimately those that have to repair it) before I set about designing/re engineering/building something- most engineers* can weld and machine stuff but knowing temperatures/currents and gas mixtures that work for given materials and similar things for everything else by heart is not necessarily a required skill (the theory behind it all and being able to discern what is necessary given some tables/books certainly but I would not drop an engineer into a machine shop and expect them to immediately replace a good machinist).
Likewise (although if you want to stay on the best side of your foreman I would not make it a habit) no good engineer will turn away useful input from the machinists/fabricators (especially if you are doing batch work and it ups time or drops yields).

*I know engineer means something slightly different in Germany versus a lot of the rest Europe (Canada probably providing the best equivalent) but my example should still hold.

11. ### tenshinonekoGBAtemp Regular

Member
1
Feb 14, 2009
OMG that sounds so difficult T_T good luck with it =3

12. ### YoukaiDemon

Member
6
Jul 1, 2004
Germany , NRW
@Fast6191

Well the best explanation for my job would be

I get a technical drawing from an engeneer that exactly shows me what metal i need and how the final product has to look like.
Than i get the Metal put it on the machine and calculate the speed via a very simple formula
Vc=d*pi*n
with d beeing the "durchmesser" diameter of the used tool
and Vc is written in our "holy bible" XD
thats more or less ALL i need.

And yeah Schnellarbeiststahl (HSS) was used for many tools before and many drills are still made out of it even thaught for future use I think this will vanish. (we use Hardmetall tools nowadays)

We even learn how many newton makes 1mm² steel/copper/aluminium ....... to chance shape / burst ... and I really do not need something like this cuz the engeneers have to calculate that stuff and tell me what i should use.

@tenshinoneko
yeah doesn't only sound difficult it is difficult for many ppl ... well for veho it seems to be a pice of cake but yeah not everyone can be smart as him