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Replace traditional toggle lever with magnetic cylinders

  1. Mar 29, 2013 #1
    Hi there,
    Currently I'm working on a complicated project. I work for a packaging machinery company.

    The machine I'm currently working on has a critical section which you would call the 'the heart'.
    Here we move a 800KG (1700 Pounds) bed up and down by 50mm (2 inches). On the bottom of this bed we have four points of lifting attached to 4 levers. These levers are then attached to a crankshaft by means of connecting rods. This system is patented and proven since the 60s.

    We'd like to replace this system by using magnetic pressure on these four points.

    My main question, are there magnetic coils already in the industry than can lift this weight?. Also what would be the response time generally ?.

  2. jcsd
  3. Mar 29, 2013 #2


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    The weight of your 'heart' is not a problem.
    What matters is how much space there is for the electromagnets with their power and cooling lines and how short the cycle time is expected to be.
    What benefits do you hope to get from this design change? Eliminate lubrication requirements, reliability, flexibility?
  4. Mar 29, 2013 #3
    No issues, eliminate moving parts

    This machine section we're building has a life expectancy of around 50 years, with minimum maintenance such as oil changes. Our competitors make the same unit and have a life of around 100 to 120 years. We even checked the pins suspending the top bed of a 87 year old machine, not a scratch. We'd like to achieve the same.
    This change will have minimum friction, very less noise, electrically controlled movement of the bed increasing precision. Space is not an issue.
    Power consumption , cooling requirements etc are not an issue since this will just be a prototype. I now assume electromagnets are not available for this requirement. I f we had to custom build these magnets, what formulas could we use to determine electrical and mechanical requirements ?

    Here's a link of the existing design - http://www.google.co.in/patents?id=mmplAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false

    Part 22 of FIG 1 is the massive bed we're trying to move vertically with electromagnets.
  5. Mar 29, 2013 #4


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    The concern re space, power and cooling was because the coils are not small and if the press is to cycle at a decent clip, there will be some heating as the magnets are turned on and off multiple times per minute.
    The improvements sought seem quite realistic, although the 'electrically controlled movement of the bed' aspect is an expensive item. It is a lot cheaper to just size the magnets to push or pull the heart with a certain force, essentially give it a shove, than it is to modulate that force over time to precisely control the movement of the heart. That is more a linear motor action than just an impulse, so control circuitry and sensors will be needed, which introduces potential sources of failure. I don't know of such setups having anywhere close to the 50-100 year longevity you are seeking without periodic maintenance.
  6. Mar 30, 2013 #5

    Is there any way we could custom build the magnets, using set formulas for current and force ?
  7. Mar 30, 2013 #6


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    You can build your own magnets and you have lots of design freedom. Simplest is probably to just pull the heart against its die by having the levers serve as cores pulled into electromagnetic coils, but there are lots of other approaches. The specifics depend on how often the system cycles and how much control you want over the force with which the heart meets the die. Do note that introducing controls requires adding sensors, which reduces reliability and increases cost.
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