How to calculate force for problem attached. 4

[ISBind]

Hiii

I need to calculate force required(F1) to pull the plate out with block leaving behind on Floor(to eventually calculate motor HP).

If
W1 is Weight of block
W2 is weight of plate
Cf1 is Coefficient of friction between block and plate
Cf2 is coefficient of friction between plate and floor

Anyone contribute anything on this will be really helpful.


Regards

 

[IRstuff]

I suggest that you provide some more detail, as it smells suspiciously like a homework problem.

TTFN
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[ISBind]

Sure IRstuff

We manufacture machinery used in Hard coke oven plant.

and this plate carry compressed cake which is placed inside coke oven and after that plate is pulled outside leaving cake inside coke oven.

We wanted to calculate motor required to pull this plate outside and also chain that be used for same and hence wanted to know force required.

I hope detail will be sufficient if need any other detail please let me know

Regards

 

[LittleInch]

Is this any more simple than ((W1 x g) X Cf1) + (((W1+W2)x g) X Cf2) ?? with weight in kg and G = 9.81

With the Cf, there will be a static value and a kinetic or moving value which is normally a bit lower than the static one

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[rb1957]

ask a magician how he can remove the table cloth form under the dinner settings. you want to pull really hard on the plate so that the inertia of the body overcomes the friction from the plate ... tricky.

only slightly more seriously ('cause i think the above idea could lead somewhere), can you incline the plate? how do other people do this?

Quando Omni Flunkus Moritati

 

[Tmoose]

I'm not sure I'd trust any Cfs unless they were derived empirically from actual measurements of the actual situation, at which point I'd know how much force is required anyway. Then I'd throw a "safety" factor of 3 or more at it anyway just for the day after " ♫ Someone left the cake out in the rain ♫ ."

Some types of motors pull REALLY hard when started from zero rpm, and some don't. I'm guessing you have a gear reduction and maybe a clutch in there somewhere too.

 

[ISBind]

above mentioned system is already implemented.

What we do is we stop the block by structure whose wheels rests on plate.
when plate is pulled structure stops the block from moving along the plate. while structure rolls on plate

We cannt incline the plate due to various constraint.

As the cake is too big(34 tonne) so cannt think of pulling it hard too.

We wanted to calculate force. i hope calculation mentioned by LittleInch will help.

regards

 

[ISBind]

tmoose There will be gearbox after motor.

 

[ISBind]

Thanks everyone for their comments

I will make my calculation as instructed by LittleInch

If someone have anything to add please let me know, that will be really helpful.

 

[rb1957]

i have a feeling that the force is only part of the solution, I think how quickly it is applied is critical to success (remember my party trick analogy).

with LI's calc, one of the Ws is the plate, negligible compared to the weight of the body? but when you pull the plate, what stops the body from moving? how'll the body react when it has a force of Cf*W applied to it? I guess part of the problem is to get the body slipping on the plate very quickly 'cause once the body is sliiping there is much less friction force going into the body, limiting the impulse/work on the body.

Quando Omni Flunkus Moritati

 

[IRstuff]

This does presume that your "structure" must likewise resist the force W1 x g) X Cf1, since that's where it'll be manifested, and it's what keeps the cake from going with the plate. The structure won't have to resist the force required to overcome the friction from the bottom of the plate, since that's the oven itself.

TTFN
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[rb1957]

'cept that the "structure" is on wheels ? maybe it's chocked somewhere ??

Quando Omni Flunkus Moritati

 

[IRstuff]

I think the structure is free-floating on the plate, but is stationary relative to the oven. So the mass of the structure should also be included in the above equations.

TTFN
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[dhengr]

ISBind:
I would look long and hard at what you have been using, what has been working. The equipment for the coke oven industry has been around for a long time, is tough as hell, with design factors of safety of 3, 4 or 5, due to wear and tear. This is because any failures cause a real mess in the process, the working environment is absolutely awful in terms of heat, abrasive/hard materials being handled, difficult and lack of maintenance, etc. etc. I don’t know that I would try to reinvent the wheel on this type of equipment, rather try to improve the details which are causing any problems. A slight change in chain size or motor size may not be a great savings, and may just add to inventory complexity at the plant. I would assume that coef. of friction can vary all over the place, as a function of the coking coal used, the coke turned out, and mostly how clean the running tracks, guides, wheels, your bottom plate, etc. between each application of the plate pulling operation. I would think that getting a handle on these values might req’r. some testing at each plant and with each different piece of equipment. What sizes of motors, chains, etc. are being used now and how long do they last. Then what can I do with my design to clean tracks, guides, wheels, etc. to minimize the grinding friction of clogged guide ways, so they work better?

 

[Bobfromoh]

I would like to add that the friction values might be hard
to determine. I used to work in the heat treating /material handling
business. Hot metal can be very "sticky"

 

[ISBind]

Hello everyone

Said "structure" will be locked by hydraulic cylinder from sides

That way structure will stop the Coal Block from moving where as its wheel will allow it to move with plate

 

[rb1957]

then it should be as "easy" as LI posted above ... once you have good data for the range of Cf

Quando Omni Flunkus Moritati

 

[catia2014]

For a specific detailed answer, you need to provide the following information:
The weight of the plate= Wp
The weight of the block= Wb
The material of the floor=Mf
The material of the plate= Mp
The material of the block= Mb
Then anyone can calculate the static coefficient of frictions called U1 and U2, put all of that in the following formula to obtain the Required Force:
(Wp+Wb)*U1+Wb*U2= RF

 

[rb1957]

"Then anyone can calculate the static coefficient of frictions called U1 and U2" ... aye, there's the rub ...

Quando Omni Flunkus Moritati

 

[johnbridge231]

Do you have the friction factors available?

Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis

http://www.engissol.com/cross-section-analysis-design.html