What Spec of Motor do i Need 1

[gooseygumdrops]

Good evening all,
i am involved in an organisation that build attractions for various events.
we are construction something bespoke that rotates around with a weight of around 3 tone. we are happy with the construction of the movement and everything to go with it. all i could do with advise on is the selection of a suitible motor and gear box.
we wish to stop the movement at various points around the 360 degrees and then reversing. if you imaging a swing going back and forth higher and higher aroungnthe circle of movement and then every so often completing a 360 dergree movement. any advise? if you need more info please ask. we are going to need to purchase something in the next few weeks so as to hit our deadline

 

[flexoprinting]

Holy smokes! There are so many details left out to answer a question like yours but your really going to need the advice of an Engineer on site.

Chuck

 

[gooseygumdrops]

What details do you require. We have no real limitations other than. Price. So we can have ac or dc. Can you please inform me of what info I need to specify. As although it may not help here. It may in the future

 

[electricpete]

i am involved in an organisation that build attractions for various events.

Glad to hear it. I'm not trying to be a stickler, but are you involved in engineering? That is the target membership for the forum.

Since you are a first time poster, I'll mention site policies:
faq731-376

These fora are provided by Eng-Tips.com solely for the discussion of engineering topics of a professional nature. Subscribed members of this forum community should use these fora to increase their productivity and knowledge. They should also use this platform to share relevant field experiences within this community.

These fora should not be used to bypass your own in-depth research on the issues that affect you, nor is it intended to be a substitute for appropriate professional assistance within your field or geographical region.

In other words the site is more for engineers than do it yourselfers asking help from engineers. I'm not passing any judgements but I tend to agree with flexoprinting that your original post and initial response does nothing to create any impression other than DIYer looking for an engineer to spoonfeed him a solution.


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(2B)+(2B)' ?

 

[gooseygumdrops]

Thank you for pointing it out to me. I am an electrical engineer with more than 10 years experience. Although I am not ashamed to admit I have no knowledge of the selection and difference between the range of gearbox's on the market and thought this was the sort of place I could get helpful advise for a project my 'charitable' organisation are trying to complete. I have no knowledge of how to work out torques and such am at a loss as what to purchase. Wiring the plc and sorting the programming. Not a problem. But the actual physics of it I would appreciate some advise. As I said in my first post any more info and I will let you know. This does not mean I don't know. Simply dont have any specs for voltage, current, physical size. To a certain extent speed but we will need to keep it in a range that we can aquire a vsd for. I'm not trying to be difficult in fact quite the opposite. I don't want to add limitations and make it harder for someone to give me advise

So again if anyone is out there and wants to give this so called 'diy'er some much needed advise, i and the organisation I am involved would be very grateful

Good evening

 

[Skogsgurra]

OK, I give you good advice: Go buy a standard induction motor with something like 10 Hp output. Add a vector mode VFD with four quadrant ability. Then buy a transmission with, perhaps, a 100:1 ratio - or thereabouts.

That would probably fit most attractions except for the wildest ones. But will it be of any use for you? I really doubt it.

Tell us about the mechanics. What is the movement going to be? Masses involved? Speed and acceleration. Things like that.

It is nice that you are trying to be nice. But asking for help without revealing what the help is for is not nice.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[gooseygumdrops]

Thank you for you reply

If you where to imagine a 3 M disc spinning around its centre at around 10 to 15 RPM. with the disc weighing 3tone balanced around the disc. The disc is vertical mounted so the shaft running horizontally. As I said we will be programming this to go clock wise then anti clockwise end around twice a minute completing a 360 movement. So we want to make sure the gear box is man enough to stop the moment and reverse. We will slow it down to a stop and reverse with the use of VSD and some limit switches set around the outside of the moving circle to a fixed mounting. As I said I don't know how to work out the torque and inertia needed to start the movement and stop/ slow down

Regards matt

 

[Skogsgurra]

OK, so I was in the right ball park with the gear. 1500 RPM divided into 100 is actually 15 RPM. So you can go from 0 to 15 RPM with no sweat.

If the disk is balanced, you do not need much power to make it rotate. But you need torque to accelerate/decelarate it. Since a 100:1 gear reduces moment of inertia 100 times squared, or 10 000 times, I think that 10 HP will be ample. It depends on what acceleration you want. Not much, I suppose. And probably with an S-ramp. That is available in most standard VFD:s.



Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[ScottyUK]

Have you considered a hydraulic motor? This sounds perfect for a Hagglunds drive. Pricey! Or a cyclodrive with an ac vector drive on the input?

 

[electricpete]

Unless I've missed it, you (op) have said not a thing about diameter or radius.

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(2B)+(2B)' ?

 

[electricpete]

Never mind 3 meters.

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(2B)+(2B)' ?

 

[LionelHutz]

Try Google searching for torque, angular acceleration and inertia. Once you calculate the required torque and know the rpm it's fairly trivial to ratio it through a gear box to get the torque the motor has to generate. Ask questions if you're hung-up on some part.

 

[Skogsgurra]

I did read Minnesota Mining and Manufacturing, too

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[krisys]

gooseygumdrops,

If you go this way you would end up in producing an experimental or study type project. The one you must have done during your college days. From the description, it appears to be an expensive equipment consisting of electrical, mechanical and control equipments. You must understand that this is not only the issue of motor, but the complete equipment as a package. You will be answerable to the management and the people who have generously donated the fund.

I could imagine this something like a roller coaster or a moving disc which would carry people (specifically children). Thus safety should be an important aspect of your task.

If you search in the web for the vendors who are supplying the equipments for the entertainment industry you should be able to get few suppliers. You prepare a high level specification (which is also called as functional specification)and send them requesting the technical proposal. They would provide you some details, which you should use to further detail your specification and narrow down the requirements.

Your functional specification may include the details of power supply available at site, Variable Speed Drive motor requirement, other controls, capacity etc. Also give a good introduction/background of the requirement.

Hope this would help you.

 

[electricpete]

I did read Minnesota Mining and Manufacturing, too

Yeah, that might have been what threw me.
Or maybe I was logically focusing on the area of the thread before people started guessing at horsepower
Or maybe it was the lack of pristine notation in using M vs m.
Or maybe just maybe I wasn’t paying close enough attention. Nah, that’d never happen

No complaints on my part. I was just wanting to make sure we keep on guard against giving advice to someone who’s in over his head. krisys’ post is a good followup in that regard.


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(2B)+(2B)' ?

 

[electricpete]

I was just wanting to make sure we keep on guard against giving advice to someone who’s in over his head.

That came out wrong. I meant we need to continue to be careful in our interaction with op because we don't know him well and for all we know it's possible he's in over his head (not that he is). I'll shut up now.

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(2B)+(2B)' ?

 

[electricpete]

if you imaging a swing going back and forth higher and higher aroungnthe circle of movement and then every so often completing a 360 dergree movement

That description seems to imply that gravity is important. If so, that is different than would be the case for a balanced disk rotating on its axis. You'd need to clarify which you're talking about.... you can't expect reliable advice from ambigious specs.

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(2B)+(2B)' ?

 

[Skogsgurra]

Yes, that's why I threw in my caveat "If the disk is balanced, you do not need much power to make it rotate"

My thinking is that you can start people in a direction that isn't completely wrong. They will then find out a lot of things by themselves. And sometimes they will fail completely. They learn from that, too. One lesson that they learn is to get a professional involved next time.

The risk that someone gets hurt is always there. Byt you cannot build and start using any such contraption just like that. There's always a certain amount of inspection and paper-signing involved to protect the public.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[gooseygumdrops]

Thank you all for you help and guidance. I am a lot closer to establishing what I need. To put your minds at ease here is a bit more info about our organisation. I am based in South Somerset and over November we compete in carnivals through our local towns raising money for charity and competing for cups and shields. Now this isn't like Notting hill or Rio or a village parade. These entries can be 100ft long 15ft high and 11ft wide. Members of the organisation ride on this entry dressed in a costume doing a routine that depicts the choosen idea for the year. Here is a link to some videos on YouTube. There are loads of others have a look. By the sounds of your answers I can see all of you being interested/impressed with what we pull off.

https://youtu.be/geP0HdVa-60

https://youtu.be/HS0oCInsWfY

https://youtu.be/CBYXXt8_LsA

https://youtu.be/J5cwJWw7guo

 

[JSPRINGS]

Simple answer would be a servo motor.

With this you can control direction of rotation, speed of rotation and position.
You can program this according to your requirement.

Please go through Seimens Servo motor series.

Other companies such as ABB, Philips also has these. Used especially in Industrial size robots.

To reduce load on the motor you can make a stage that can revolve on its axis, with the help of a shaft and ball bearing , balance on the middle of the structure, geared as like a circle (Imagine concentric circles).

The motor can be connected by gear to this gear that lines the stage. Hence the motor doesn't need to carry the weight.