Hello
I would like to know if it is possible thanks to Solidworks to calculate the force needed to translate a door (2Tons) on a track thanks to 2x4 casters (directly welded on the top of the door). Because I have to use (and I can't change) a mechanical cylinder like a ball screw.
Is it possible to perform this calculation on Solidworks, and if not, how to do it "by hand"?
Thank you very much and have a good day to you!
http://fr.wikipedia.org/wiki/Résistance_au_roulement
Hello
you just have to know the rolling resistance coefficient of your two materials (rail and caster, if steel on steel, it's approximately 0.4) and multiply it by the weight of your door (2000X0.4=800daN) and you get the effort to be produced to set in motion. You then need to apply a small safety factor (1.1 to 1.2, or about 900daN) so that your cylinder is well sized.
Thank you so much for these leads!
I was just reading something about it. So I have to ask the supplier for this coefficient of resistance! Or I can also find it myself depending on the subject.
I saw that you also have to include the friction factor of the bearings?
I have a total of 8 casters, should I include this number in my calculation?!
Thanks again
No, the number of castors does not change anything.
I was telling you to apply a small safety coef to take into account the bearings and other efficiency ... which could alter the system.
This will only be an approximation, but it will be quite close to the truth.
Hello
In the case of castors, it is only the coefficient of friction of the bearings that must be taken into account. The coefficient of 0.4 would only be valid if the door moved on a flat footing.
Just imagine pushing a car, for example. The coefficient of rubbing tire on bitumen is close to 1 and a car easily weighs 1 ton. Moving the car sideways (pushed from the side) is impossible. On the other hand, pushing in the axis of the car (from the rear for example) is feasible because the friction is limited by the bearings.
For example, you can consult the following page to try to determine the coefficient of friction of your bearing (usually around 0.001).
http://medias.schaeffler.de/medias/fr!hp.tg.cat/tg_hr*ST4_102160011
This will give you a resistant torque at the level of the bearing. It must then be brought back to the equivalent force on the outer diameter of the wheel (obviously add a small coeff on it). If your door moves fast (but we can doubt it for a 2-ton door), you also have to add the effort necessary to start. The number of castors is indeed not important because the total effort will just be distributed equally among all the castors.