compaction using motor

Thread Starter

subakumaran

Joined Jan 16, 2014
1
Hello friends ...... i 'm new to this forum ......... i've doubts regarding certain specifications of motors and controllers for my project ........
i would like to operate a 12 V motor for providing a compaction force of around 2500- 3000 newton ......... this force is used to compress waste .................by coupling a ram with the motor the compaction action can be achieved ..........
what power and torque rating motor should i select ???????
thank u :)
 

R!f@@

Joined Apr 2, 2009
9,918
12V to compact waste ?

What are the motor specs?
Oh wait ! U want us to specify motor type.

What types of waste by the way ?
 

GetDeviceInfo

Joined Jun 7, 2009
2,192
Hello friends ...... i 'm new to this forum ......... i've doubts regarding certain specifications of motors and controllers for my project ........
i would like to operate a 12 V motor for providing a compaction force of around 2500- 3000 newton ......... this force is used to compress waste .................by coupling a ram with the motor the compaction action can be achieved ..........
what power and torque rating motor should i select ???????
thank u :)
Motors are typically given in watts. You've given us newtons, which, if we convert to watts, require some unknown units. You must provide those units as part of your design consideration.
 

GopherT

Joined Nov 23, 2012
8,009
Motors are typically given in watts. You've given us newtons, which, if we convert to watts, require some unknown units. You must provide those units as part of your design consideration.
For example, in what time frame do you want to complete a compaction cycle? Gear ratios will play a key role here. Therefore, you need to share if you expect a direct drive mechanism (not recommended) or a highly geared system.

That being the case, What type and size of gearbox will fit into the space you have?
 

mcgyvr

Joined Oct 15, 2009
5,394
ah the old.. I want to build something that requires engineering.. Out to the internet to find a sucker to do it for me..

I wonder just how many products that come out of India/China,etc... that were internet "designed" by someone on this board or similar.

The question cannot be answered without more details.. "mechanical" aspects come into play too..
 

Bernard

Joined Aug 7, 2008
5,784
Example: Linear actuator, 24 in stroke, 1000 lb [ about 4500 N ], .55 in/ sec. under load, 1 in/sec no load, PM motor, 12 V, 2 A no load, 24 A loaded, US $ 283. Or, 18 in, 665 lb, 24 V, .5 to 5A, US $ 45. # 5-1785, www.surpluscenter.com
 

BillB3857

Joined Feb 28, 2009
2,570
Or run a hydraulic pump with your motor and a hydraulic ram to do the compacting. Such units are common for snow plow up/down, left/right control.
 

StewB

Joined Jan 3, 2014
17
Hello friends ...... i 'm new to this forum ......... i've doubts regarding certain specifications of motors and controllers for my project ........
i would like to operate a 12 V motor for providing a compaction force of around 2500- 3000 newton ......... this force is used to compress waste .................by coupling a ram with the motor the compaction action can be achieved ..........
what power and torque rating motor should i select ???????
thank u :)
So Power = Work_done / Time

Work_done = force * distance

So Power = (force * distance) / time

You require a force of 3000N delivered by your ram
Let's assume you have a waste hopper that has a ram that travels 1m
Let's assume you want your ram to travel this distance in 5 seconds

The power needed is = (3000 * 1) / 5 = 600Nm/sec = 600 watts

Low HP motors have efficiencies of 80% so real power = 600/0.8 = 750 watts

You'll need more power than this due to reactive power requirements.
Small motors like this will have power factors of about 80%.

So apparent power rating = 750/0.8 = ~950W
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
The Nook ball screw jacks I have used start at 1/4ton and go to 100 tons.
Only a relatively small motor is needed.
The site has all the design software for sizing once the tonnage is known.
Max.
 

GetDeviceInfo

Joined Jun 7, 2009
2,192
Piece of test equip where I do some work was worked on by the local PLC tech. During the weekend a crew of electricians cycled the source, and this equipment energized. The result was two 3" screws being bent, and the test fixtures, consisting of 2" welded steel bridges being destroyed. Fantastic forces. This equipment is pretty well a trash compactor now.

Personally, I like the hydraulics for it's flexibility.
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
Starter motors for car engines are in the ~3KW area of power. They only draw high amperage when fully loaded by the compression of the engine. Only a fraction of the power at lower duty.
The down side is they operate in a run away condition when lightly loaded.
Being a series wound motor they should never be ran without a load of some kind.
Max.
 

StewB

Joined Jan 3, 2014
17
No **** ???

3KW ??? Really ?

Got to get me one of those..!


cc_per_cubic_meter = 1000000
secs_per_min = 60
Assume Engine cylinder capacity = 1000 cc
Assume engine Compression_ratio = 0.1
Engine_cranking_revs = 300 rpm (bit high, maybe 200 rpm would do)
seconds_per_rev = 0.2 secs

Atmosperic_pressure = 100000 Nm-2
γ = Adiabatc_Index_diatom = 1.4 (aka 7/5)

So:

P = 100000 Nm-2
V1 = 0.001 m3
V2 = 0.0001 m3
γ = 1.4

k = Diatomic_gas_constant = P*V1^γ = 6.309573445
ie k = 6.309573445

W = work done per rev = -k*((V2_^(1-γ))-(V1_^(1-γ)))/(1-γ) = 378 Nm
(adiabatic compression)

power to crank = W/seconds_per_rev = 1890 Watts

Add in loss due to bearing friction, prolly get you to 2.5kw. Make the engine cc bigger, you're looking at 3kw
 

Richie121

Joined Jan 12, 2014
27
The problem is a common one. You actually need the lowest force to start off, but the highest force to finish, thefore constant force of a linear screw is not the best option. Incorporating a cam action in your design will produce faster results and a more eaven loading on the power source.
One of the easiest to control for packing waste is to use compressed air and air rams as the power. You only need a relatively small motor or dedicated fridge compressor to provide 5 Bar of pressure... that's 75 psi and use 12v solenoid valves to switch it to one side of a ram for compressing or the other side for opening. Use a restrictor in the lines and it won't do it too violently. 75 psi over a 12" ram will provide (113x75) 8475 lbs of force or 3.8 metric tonnes of force.
You then have to work out you cam profile and area you are working on to calculate the real force supplied - but you get the idea.

I have seen these units where the compressor is outside, and only a pipe is indoors to the compactor which is almost silent in operation.

Be aware you have to have doors on these units connected to safety interlocks so nobody gets squished. It should only operate with both doors closed.
 

shortbus

Joined Sep 30, 2009
10,045
The down side is they operate in a run away condition when lightly loaded.
Being a series wound motor they should never be ran without a load of some kind.
Max.
Been a while since you changed a starter motor?:) Since some time in the 1980s, they went to PM motors.
 
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