compaction using motor

Discussion in 'The Projects Forum' started by subakumaran, Jan 16, 2014.

  1. subakumaran

    Thread Starter New Member

    Jan 16, 2014
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    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 :)
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    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 ?
     
  3. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    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.
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    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?
     
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    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..
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    I want you to design it so I can manufacture it in India.
    Get the point.
     
  7. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    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
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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  9. BillB3857

    Senior Member

    Feb 28, 2009
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    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.
     
  10. StewB

    New Member

    Jan 3, 2014
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    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
     
  11. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    So OP needs a 12V 1KW Motor.
    Fascinating.
     
  12. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    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.
     
  13. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    No **** ???

    3KW ??? Really ?

    Got to get me one of those..!
     
  14. MaxHeadRoom

    Expert

    Jul 18, 2013
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    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.
     
  15. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    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.
     
  16. MaxHeadRoom

    Expert

    Jul 18, 2013
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    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.
     
  17. StewB

    New Member

    Jan 3, 2014
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    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
     
  18. Richie121

    New Member

    Jan 12, 2014
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    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.
     
  19. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Been a while since you changed a starter motor?:) Since some time in the 1980s, they went to PM motors.
     
  20. inwo

    Well-Known Member

    Nov 7, 2013
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    And really nicely packaged 12v power units.

    Put one on my jet boat for trim.
     
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