Where to start 2

[bluesman0007]

Can anyone help me get started finding the horsepower required to move a rolling bolster weighing 100,000lbs. It will be a servo motor driving a speed reducer with output to a gear that will drive a live shaft which will in turn drive the rear wheels on the bolster. I know my speeds, gear ratios etc. but I'm not sure where to look to find the answer for myself. Thanks in advance



SolidWorks 2006 SP4.1
Windows XP Pro, Pentium4 3.00GHz
1.5 GB RAM, Matrox P650
Logitech Marble Mouse, CadMan

 

[berkshire]

bluesman0007 (Mechanical)
One horsepower = 33,000 foot pounds per minute.
If you have the weight and the speeds the rest should be easy.
B.E.

 

[bluesman0007]

berkshire (Aeronautics)

Thanks I'll give that a try.

SolidWorks 2006 SP4.1
Windows XP Pro, Pentium4 3.00GHz
1.5 GB RAM, Matrox P650
Logitech Marble Mouse, CadMan

 

[handleman]

There are a couple of missing pieces of information. The first is required acceleration. That's where your real HP requirment is. HP requred for constant velocity is zero if you ignore frictional losses. Speaking of frictional losses, that's the second piece of information you need. If you can somehow figure up your frictional losses and you know your required acceleration then you can calculate the horsepower requirement.

You mentioned using a servomotor. If your bolster really weighs 100,000lbs you will likely have inertia matching problems. Check out

http://www.manufacturingcenter.com/tooling/archives/0798/798tchup.asp

I would stronly advise bringing in a servomotor distributor/manufaturer at this point to look at your application. Of course, it would be nice to use the same people you intend to buy the system from. They will look at your desired motion profile and all the loads you have in your system and put that information into sizing software to select the best system for you.

 

[bluesman0007]

Thanks handleman,

It will indeed reach the 100,000lbs with the die in place. I think the suggestion of bringing in a servo person is a good idea. I also was wondering if some physical simulation cosmos works or something similar might help. I know getting this load started and stopped is going to be a challenge. We are keeping the speed down at this point, at full speed I would like to achieve approx. 45" per minute. Thanks for the link I will look it over and see if I can absorb a little more knowledge.

Dennis

SolidWorks 2006 SP4.1
Windows XP Pro, Pentium4 3.00GHz
1.5 GB RAM, Matrox P650
Logitech Marble Mouse, CadMan

 

[tygerdawg]

Websearch & download "Smart Motion Cheat Sheet" in PDF format. Also use SEW-Eurodrive's PTPilot sizing application for their gearmotors. It has a few different default motion models that you may be able to use to get some sort of answer.

It's all about load mass, torque required to overcome friction after a dead stop, and torque required to accelerate or decelerate.

Depending upon accelerations, you may be surprised at how little horsepower you need to drive this load.

TygerDawg

 

[handleman]

Servos are a bit more complicated than straight induction motors due to the feedback loops. As the ratio of load inertia to motor inertia increases positioning accuracy decreases. I know just enough about this stuff to know that I need someone who does it every day to get in on the project early.

 

[bluesman0007]

handleman & tygerdawg,

Thank you both for a lot of good information. If nothing else I will have some good questions to ask the servo guy when he shows up. Maybe even be able to check his work.

Dennis

SolidWorks 2006 SP4.1
Windows XP Pro, Pentium4 3.00GHz
1.5 GB RAM, Matrox P650
Logitech Marble Mouse, CadMan