Challenge Question: Vibrations that move material up instead of down!

I have a feeling this effect has to do with a "shaped" vibration cycle, where the downward movement of the vibrating plane is more abrupt (higher acceleration) than the upward part of the cycle. By this means, the upward cycle may get the benefit of static friction and the downward cycle of sliding friction - perhaps!

You could be right Jorrie, I have seen the steel plate & violin bow experiment where sand sprinkled on the surface makes pretty patterns. Now as I recall, the plate was horizontal, I wish I had asked "What happens if we tilt the plate"?

As an undergrad at, London Uni, my first assignment was with the Rolls Royce Vibration Engineers Subsidiary, 'Delany Galley'. There was a fabulous suspeded, &,enclosed chamber. with a 'XYZ' .....AND......Axial......'Test Bed' Huge great stainless steel thermionic valves the size of supermarket wheely-bins in Class A Amplification configuration. They were testing chopper blade mountings to destruction when I was there as a visitor.

On the wall was an origional drawing by 'Rowland Emett' (a fanciful cartoon representation)

http://www.mech.mcmaster.ca/~nyet/emett/

Up-down-round-n-round-n-back-n-forth?

Orbital vivrations, in a preferential rotational direction, at the circumferance of any bowl, with a spiral 'causeway' will ensure objects travel up. Those in sympathetic vibration go 'Up' those not, go 'down'...... I wonder where that lovely drawing by Rowland is now. It had to be framed in perspex

I have yet to peek at the answer, but that's my guess how this contraption works?

"Up-down-round-n-round-n-back-n-forth" is a pretty good description of what happens, but it has nothing to do with "sympathetic vibrations" . Check out dkwarner's post #13 or my replies to Jorrie's post #1 for the most correct answer. My published answer needed a little amplification and clarification.

I remember those funny inventions in Chitty-chitty Bang-bang! Now I wonder who came up with the inventions of Dr. Emmett Brown (played by Christopher Lloyd) in the Back to the Future movie series?

STL Engineer, Thanks for that great Challenge. Dr. Emmett Brown, indeed his inventions may well have come from Rowland Emmet? I think the London Earls Court Motor Show, circa 1969/70 had a Moon Lander Sculpture by Rowland, It had all sorts of whimsical additions, like a teas-made to welcome Moonmen with a hot cuppa. It was quite a laugh, all sorts of things that NASA forgot to include. No 13 got it right, but then I suspect he plays ping-pong. Maybe I am wrong, but if the orbital vibration caught the bounce on the 'down' cycle, it would send the components/abrasive down the chute? instead of up....where is my ping pong bat, I have loads of ping pong balls?

Don't forget Professor 'Caracticus Potts' Played by Dick Van Dyke, What a lovely pseudonym for a CR4 'Tag'...... I might like to adopt it myself, as a Engineering 'Groupie' ..... Amateur I fear. I moved from Industrial Design tp Applied Mathematics.

I happened to catch an episode of "As Time Goes By",the BBC comedy, on the tellie last night (that's what my Grammie called the TV!), . It was a "play within the play" sort of thing as an American film crew was shooting a "mini-series" based on the central character's life. The main characters were deriding the awful dialogue and horrible English accent of at least one of the American actors in the cast, and their friend, who was being employed as "Executive associate deputy assistant to the co-executive producer" or something like that, tried to explain, that since it was for an American TV audience it was all right, "something like when Dick Van Dyke did his Cockney accent in Mary Poppins" I guess the British like American actors better when they don't try to be British! As I recall, Van Dyke's Potts had British children but he himself was American (or Canadian? That's always a good way for American actors to explain their presence in the British Military in films!)

Jorrie,

Your answer is basically correct, except for the bit about it being a "shaped" vibration, "where the downward movement of the vibrating plane is more abrupt (higher acceleration) than the upward part of the cycle."

You are correct that the upward cycle gets the benefit of static friction. Springs mounted at an angle propel the parts forward when the electromagnet pushes upward, then the stored energy in the spring returns the bowl/track downward and backward to its original position. There are actually two modes in effect, hopping and sliding. My "official" answer describes the hopping effect, most common in small, lightweight parts. In this mode, the parts are NOT in contact with the surface during the downward, reverse acting part of the cycle, but essentially "hop" relative to the surface moving underneath them.

The second mode, sliding, is more common with heavier parts, and relies, as you noted, on the benefit of sliding (or dynamic) friction being less than static friction. In this case, as in the first, the parts are propelled upward and forward by magnetic and spring action with static friction holding them in place relative to the surface which also moves the same way. Then on the return portion of the cycle, with the parts remaining in contact with the surface, their forward momentum, and less weight, being more or less in free fall, allows them to slide relative to the surface.

In reality, many parts are fed with a combination of hopping and sliding, depending on weight, vibratory amplitude, geometry of the part surface, and co-efficients of friction between the parts and the bowl.

One more note, my "official" answer says the springs are "compressed or expanded", which is not the best terminology, since leaf springs are the most common type of spring in use, not coil springs, so the terms "loaded and unloaded" would probably be better.

I said, "Springs mounted at an angle propel the parts forward when the electromagnet pushes upward, then the stored energy in the spring returns the bowl/track downward and backward to its original position."

Well, I ran out of time to edit my post, so let me add this: "Or is it the other way around (magnet pulls downward, pushing spring and bowl/track backward, stored energy returns bowl/track upward and forward)? Oh, well the effect is the same!"

It might be possible to do this with bristles cut to the proper length, and with the proper orientation, couild act like a ratchet of sorts.The bristles could be vibrated in such a manner as to create a "Wave" effect.The bristle rigidity would have to be selected according to weight and size of objects to be moved.The objects could "surf" the "wave" as it moved. I have noticed objects moving uphill on carpet when the carpet cleaner is several inches away, so the proper pile orientation of carpet might also work as well as bristles.

I've also noticed this effect when I vacuum, but these feeders and conveyors are different. They are preferred by the food industry, for example, because they are smooth and easier to clean. They also tend to be easier on food items which have fragile coatings.

-e

I've seen this but don't really understand how it works. I'm just guessing but I guess the shape of the floor of the vibrating conveyor might have something to do with it. It probably has a series of ripples arranged like steps on a stairway but the angles are not perpendicular or horizontal. The particle is cast into the air on the upward movement, bringing it up a little on the conveyor. When the movement is downward, the incline of the ripple keeps the particle where it is or slides it onto the next ripple above. This keeps the particle moving upward whether the vibration is in the upward or downward direction. Illustration provided (in case I didn't make any sense ).

I've seen these feeders and conveyors myself, and the surfaces are smooth. Not even micro-ridges. Jorrie's post is by far the closest yet...

-e

I was just wishing for such a contraption, easy to clean, high temp rating, 316L Stainless Steel, four vibes per minute,min., to move whole kernel shelled corn up slightly in elevation with each vibe. Help!

What is needed here, is a load of mug investors, hire a swimming pool for a pseudo-science convention, and have a canoe (recovered from a creek) without a paddle.

Line the bottom of the canoe with a preferentially directed 'velvet' (Top Hat Silk Velvet) and have a solenoid with an internal rod magnet do the back-n-forth vibration.

Then tell your captive audience that you have disproved Sir Isaac's 'action-n-reaction' but now you plan to reach for the 'stars' with an anti-gravity machine. Set up a 'Pyramid Sales' operation, and just sit back till the Lawyers knock on your door. Buy them off with the contingency fund.

Oh, I forgot, have a suitcase packed and an open airline ticket handy, as one of those lawyers might not take the bait.

Lawyer decoys at your door are a sure bet to bring the others in like...well...ducks.

Just make sure the decoys are wearing Armani suits.

And be sure to use a lawyer call for the wary ones. It works like a duck call when you blow into it, but instead of "quacking," it quacks, "MONEY!"

-e

In a paper published by the IEAust (Instittution of Engineers. Australia) entitiled "Mechanisims and Prevention of Vibration Loosening in Bolted Joints" a refence is made to this being similar to "...the mechanism of a vibratory conveyor transporting a particle up a ramp. " The paper uses theory taken from a book :

3. Bykhovsky, I., Fundamentals of Vibration Engineering, Mir Publishers, Moscow, Jan 1972. where the theory is apparantly given or developed.

I tried, in vain, to get a loan copy from one of the universities in South Australia. If you are able to find a copy or arrange for a loan copy I would be interested know where from.

Ken S

It seems to me that with the vibratory feeder, in which a cylinder is fitted inside a bowl, and a helix climbs the inside wall of the cylinder, it might be that the objects are induced to climb--essentially--by eliminating any path other than via the selective holes and off-chutes by which they could descend. Think of the old trick whereby one can obtain a greater share of Brazil nuts in a cylindrical (or any other shaped) container/tin of mixed nuts. In that scenario, it is (let us say) agreed as a matter of fair play that no partaker of the "nut tin" will dig down or spill out the can, but, rather, must select from those nuts which are on top of the pile in the tin as one's turn comes around. When the nut tin comes to the "cheater," he would then place the cap on and quickly shake the can and, upon removing the cap, find disproportionately many Brazil nuts to be "harvested." Having "randomly" captured his overshare of nuts, he might be willing then to explain to the others, that by shaking the can it is easier for the smaller nuts to fall down though the available space between the larger nuts that it is for the larger nuts to fall down through the space afforded between the more closely packed (because they or smaller) smaller nuts. To the effect that disproportionately more smaller nuts will fall and (working in tandem, as if were) prevent the larger nuts from also falling....so that the larger nuts will wind up on top...and so long as larger nuts and smaller nuts could be added to the tin, the larger nuts would continue "falling" (falling because of vibrations which are attempting to send them in more or less random directions) to the top.

Now, if St.L's vibratory feeder was so designed and operated that (1) it was continuously replenished with mixed stock and (2) the selector holes and off-chutes were permitting too-small or too-small-profile objects to fall (to go to the end of the line so to speak), then there would be a continuing supply of relatively smaller items (those newly fed and those that were selectively (or, one might say, deselectively) dropped back)--enough to ensure that relatively largest items (or largest presenting profiles) arrived at the top (or at the level specified for them to be conveyed out of the feeder). Furthermore, the feeder mechanism might eventually reach a point where different sizes of components (or components with certain profiles as well) became stratified (or reached a point where a nearly-stratified condition was emerging continuously). Properly designed, this stratification tendency could be exploited to sort (to off load), not only largest and smallest, but all sizes (or all presenting profiles) in between. Such a devise would only work, or only work to best effect, provided that the sorting bowl remained significantly filled with objects to be sorted. (Batches after must overlap batches before in the production flow, that is.) At a certain point of diminished fill level of the sorter--or (perhaps) when all remaining objects were the same size and profile--the sorter would no longer function to sort...except that any objects within it could be deemed to be the final sort group and be simply dumped or scooped out.

PS: Another example of the "falling up" dynamic can be used with a newly opened box of, say, raisin bran cereal. Hold the box upright--not inverted as many might think--and shake. More raisins will be near the top. Sorry for going off on a tangent.

Sorry, but in a feeder bowl, parts can fall off the track back into the bottom of the bowl. This is necessary to prevent jam-ups that might happen due to parts tangling or debris that got into the bowl with the parts.

There is another kind of vibratory machine that may use a principle similar to what you describe. This is a vibratory finishing machine that is used to smooth and polish objects, usually metal or plastic, using naturally hard and abrasive materials like walnet or pecan shell particles. The larger parts are placed in the bowls (usually hemi-spherical, unlike the cylindrical bowls of the challenge question) and are scrubbed by the smaller shell particles moving down, while the larger parts "float" up where they can be retreived with a nice shiny surface. In this way metals are often cleaned of oxides without using harsh acids or super-abrasive materials that scratch or wear away the metal surface itself.

I too think Jorrie is the closest so far (11/12 7AM PST), but... Having seen (and heard) these devices in operation several times, I'm fairly confident that the exciting current is ordinary sinusoidal AC (which can be varied in intensity to change the feed rate). I don't remember for sure, but it may be that the supporting springs are mounted at opposite angles on opposite sides of the bowl, with the magnet simply pulling straight down, so that there is a rotary component as well as a vertical component of vibration. This would throw the objects upward at an angle in the desired direction, and the reverse motion would occur at least partially while the objects are not in contact with the bowl, so no or reduced friction in the reverse direction.

The linear devices would again have the springs mounted at an angle, so the objects are thrown upward at an angle in the desired direction, and the reverse motion would occur at least partially while the objects are not in contact with the track.

Normally, when we think of this vibration, we think of it as unidirectional.

However, if the vibration is made to be circular, that is

a point on the surface transcibes a circle or ellipse, then

at the top of the circular vibration, there is a horizontal motion.

Since the objects being vibrated only contact the device at the top of the vibration,

they will have imparted on them a lateral force to produce lateral motion.

If the lateral motion happens to be up hill you can get them to defy gravity.

Theres a new breed of motor out there called a piezo wave motor, that

works this way ultrasonically on a shaft within a piezoelectric sleeve.

They, are capable of decent speed and outrageous precision (nM), plus

they have natural friction for holding torque with no power applied.

I've seen some of these upward-moving vibratory feeders and they don't look to be that sophisticated. It's possible that it is a natural consequence of the shapes of the parts. If so, they go up the incline for much a similar reason that wheels on rounded railway tracks seek to run along the apex of the track - i.e. that the highest position gives the lowest energy potential energy under dynaic conditions. Of course, the running of wheels on railway tracks is wheel position is susceptible to continuous analysis...

Take an inclined plane (board), and produce a vertical impulse at the lower end, the force will travel up the plane, in a wave motion. this impulse, acting on any item on the plane, will be transmitted to the item, because of the frictive connection between the two. (friction is an essential component, regardless of how smooth the surface.) The shape of the wave, as Jorrie pointed out, added to the originating source, is what will cause the item to move in the desired direction. If the plane is curved into a helix, the effect is still the same.

If the wave originated from a horizontal source, I doubt you can make the waveform work.

Chris

As is the case in nature, the objects follow the path of least resistance.The vibrations are created in such a manner as to produce more angular movement in the uphill direction.This could be accomplished by "polarizing" the direction of vibration with the shape of the mounts that attach to the vibratory source.This could also be done with slanted bristles under the workpiece.The bristles would act as a "ratchet"

I liked ChrisG's answer, following Jorrie. If we had a long roll of carpet, let us say, and we got hold of one end and made a wave in the carpet by oscilating it, objects on the carpet wold move forward with the wave, even uphill. The 'nap' of the bristles is a good idea for the canoe without a paddle, care to join me in that pseudo-science convention? we could clean up with that Anti-Gravity machine! I quite fancy Globe-trotting, we might be on the run, but we could do it in style.

There are materials who have a very low friction in one direction and much higher friction in other direction. They generally have tiny, microscopic ridges oriented toward a single direction, like hair. I would guess that this is something to do this with it. Like a self-locking jack, the piece is free to go up with little perturbations but can't go down.

I just remembered something from my childhood. The older kids would sometimes impress the younger kids with a plant that had hundreds of bristles. These bristles were lying at an angle to the body of the plant (actually I think it was the flower but I wouldn't know). When you insert the plant inside your sleeve or up the inside of your pant leg and shake, the thing would creep up inside your sleeve or pants.

It looked something like the drawing below. I think the bristles would flatten somewhat when you shook it inside your pants. The orientation of the bristles kept it from sliding down so there was no way to go but up.

I don't think this is what the challenge question is about but I just wanted to add it .

Could this be a physical property related to surface area (relative to the normal axis or not)? When vibration occurs, the small surface area pieces move down faster, thus pushing the larger pieces upward-much like vibration of a box of Raisin Bran will actually move the raisins to the top. The same analogy might be applied to for E-M properties or EM surface areas sizes (ie - field density). Any thoughts?

In practice, single items also climb.

The maximum distance of the parts above the surface is extremely small (I'd guess a few thousandths of an inch). At those distances, and at the low travel speeds involved (a fraction of an inch per second), any effects of air (buoyancy, air friction, etc.) are exceedingly small. Under these conditions surface area has no effect on rise or fall times.

As Guest (#21) indicates, single items climb; and in my limited observations, all parts climb at essentially the same rate, regardless of orientation ( and therefore surface area). I don't believe I've ever seen one operating with a mix of parts of different sizes, so I can't say about that...

Reiterating what at least one other post indicated, the surfaces of both the bowl and the helix are normal sheet metal - no fibers nor specially shaped indentations.

Quite a lot of mixed scrap containing 'brittle' plastic and metal, can be crushed with standard equipment, and separated by vibration. but I have only seen downward shutes not up. If pvc coated copper electric flex is fed into a 'chopper' [A 1 inch twist drill, in a steel block with a suitable side hole to feed the wire in, will give you the working principle] and the length of each 'chop' is 'under-square' the copper will drop out from the PVC sleeve as granules, the machinery itself provides enough vibration. The shute just needs to be 'flexibly' mounted.

I'm sure I saw one of these in Spencer Gifts along with the other marital aids.

I have really enjoyed reading your responses. At the moment there is only one posting that "hit the nail on the head", and maybe a couple others that were close, although in one case the wording was a bit twisted and hard to follow.

The idea of the oriented bristles IS used in SOME conveying systems, usually as an aid to move hard to feed parts, but is NOT used for MOST of the feeders. Also, as noted by some, nearly always the conveyors are used to feed identical parts or families of similar parts. Rarely, might they be used to separate parts and even then do not use the same principle as in the "Brazil nut" example.

For anyone who cannot wait to see the answer, I will post it (or at least part of it) in my member profile. Otherwise, the complete answer will be published on Thursday.

I hope you found this one interesting. Since this is a real world example, hopefully the answer will not seem "lame" to you as some of the other "challenges".

Those of you with other ideas, try it! Maybe you will invent something new!

The Upward cycle is much slower (longer effecting) than the downward. The efffect being slower means the friction has a longer time to accelerate the item in the direction it is going as compared to the much faster downward cycle. The item is tossed upward off the conveyor surface and the conveyor moves downward, when the item lands on the conveyor it moves upwards again and is tossed forward in the air and then conveyor moves backwards under it.....etc....the slower acting forward cycle moves the item upward more than the faster cycle moves downwards...some systems offer little or no Tossing effect which I can speculate uses a very fast backward motion to sort of slip under the item and a longer forward cycle to drag the item upward....this is useful in the food industry to keep the coatings etc... from falling off food items on the way to packing...my best guess

You, and others, are close, but there is an element, or elements, in your answer that is/are entirely false and misleading. Remove that/those element(s) and you will have a virtually correct answer!

If this is not enough of a hint, see the correct answer on my user profile.

Mmmmm.....Vibrations? in the X? Y? or Z? axis or possibly rotary vibrations, with sympathetic phased linear vibrations......I am just going to wait till Thursday.

I agree with HiTekRedNek on his answer. Some years back I purchased one of these devices at a Motorola auction. The bowl is aluminum with an elastomeric coating. The coating acts as HiTekRedNek's brushes allowing for friction when something is on the surface. The motion of the bowl in the first part of the vibration cycle lifts a particle (or part) slightly above the surface of the bowl as the bowl is moved in one direction, then gravity keeps the particle in its new place when the bowl moves back. As an aside around the year 1900 there was an industrial tractor that used this principle for its motion.

You are very close, but there are a few things wrong with your answer:

"The coating acts as HiTekRedNek's brushes allowing for friction when something is on the surface."

Brushes are NOT used for most of these feeders, but can be used for especially hard to feed parts. Orientation of the surface makes no difference. Yes, coated bowls are often used for greater friction, but more often just for sound reduction. Hard parts on vibrating steel make for high decibels.

The motion of the bowl in the first part of the vibration cycle lifts a particle (or part) slightly above the surface of the bowl as the bowl is moved in one direction, then gravity keeps the particle in its new place when the bowl moves back.

Your explanation is close but a little backwards. You still have not touched on HOW this works.

1. Frequency is tuned so that the energy being added to the part occurs at just the right time to make it jump again. It is directly related to the mass of the part being moved.

2. The coefficient of friction should be tuned to the part being moved as well. Too much friction will slow the part, and too little will also slow the part. not much friction is required.. but it is in a certain range, defined by the interaction of the part with the vibrator.

On a slightly different subject, in a book on Nikola Tesla, there is a very interesting story about him building a device that could produce a mechanical pulse, much like a bell on a fire alarm. He goes into a building that is being erected one evening, and it is mostly steel framework. He attaches the device to a column in the basement, and it is tuned to the 'frequency of the building' but he says it basically adds energy on each cycle. He lets it run for a few minutes. and with every pulse, it is adding energy to the vibration.. soon the the whole building begins to shake violently.. till he removes it... He says he was sure that the building would have collapsed if he had let it run.

Chris

WOW! How simply Awesome, a 1900 Tractor moved by vibration? In Scotland we still use Heavy Horse to plough a not inconsiderable acreage, But as they are Grey's and tend to give birth to Grey Foals (Baby Tractors) and there just happens to be a very fine Brigade of Horse, A.K.A. The 'Dalyells' http://en.wikipedia.org/wiki/Tam_Dalyell

A.K.A. the 'Heavy Brigade', A.K.A. 'The Greys' etc. There is a very good reason.

Tam is a regular contributer to New Scientist. and also held the distinction of being 'Father' to our House of Parliament.

Lionel used this principle in the 40's on their Log Loader accessory. AC power(from your genuine Lionel transformer!) drove an electromagnetic below a sheet metal ramp. The ramp was "U-shaped" and the wooden barrels were round and had ribs. The ramp was loosely mounted and I don't remember if springs were involved.

The result was that the barrels moved up the ramp and then fell into a gondola car.

The guys at Lionel were downright geniuses in coming up with ways to use the vibrations that could be induced by an AC-driven electromagnetic.

Congrats to dkwarner in post #13. He hit the nail squarely on the head! Wait for CR4 to post the full answer today or click on my username to see my user profile which contains the same full answer.

Others came close, but either were missing something, or added extra bits that made no sense or were just wrong.

I hope this challenge was enjoyable or at least interesting. Maybe I will come up with some other "real world" challenge!

I believe that the vibrating frequency and material used are the key.

As the incline is vibrated at or near resonance then micro movement of the incline (or feeder bowl or whatever) occurs. The vibration creates standing (vibration) waves in the incline and depending on the vibration frequency these standing waves can move up or down (or left or right). The standing waves "carry" whatever is on the incline up or down depending on the frequency of operation.

I am also guessing that the vibration frequency used is dependent on the size of the item to move. Lower frequency for large items and a higher frequency for small items so that the standing wave is sized for the item that is to be moved. Possibly the standing waves could be sized to only move certain sized parts in a particular direction? Maybe this is how the described sorter works. Correct sized parts go up while wrong sized parts go down.

Based on my electronics background using oscillators and resonance my explanation seems plausible. Time will tell!

Jim,

That was a darned good try, but wrong. Check my answer to Jorrie's post #1, and dkwarner's post #13 for the right answer. Current vibratory feeder technology does not use frequency variation. Mostly all use AC line frequency, 60 Hz in US and some other countries, and 50 Hz in Europe and other places.

However, you may be on to something, perhaps a "new" way to feed parts!

It could be similar to certain connectors which use a weak racheting action to give an unequal force response in a given direction. The vibration if random or equally distributed will on average move the connector in the direction of least resistance. If its possible to make the friction or track assymetric with respect to friction then random vibration could lead the part on average to follow the path of least resistance even if this means moving upward. Just like on the connectors where the vibration would tend lead the connector stay on rather the back off.

What you are describing is used in a small number of feeder designs, e.g. the idea of the oriented brushes described by others above. However, this is NOT the principle behind the majority of vibratory feeders. Please scan this thread for the correct answer in post #13 above and various replies of mine.

If anyone was wondering, as I was, exactly how the electromagnet in a vibratory feeder is powered I found this:

"Old–style electromagnetic vibratory equipment operates with an inefficient attract release system: a spring–mounted moving mass is alternately attracted by a rectified pulsating DC electromagnet and returned to its original position solely by the springs.

The Eriez Hi–Vi system, on the other hand, incorporates a lifetime permanent magnet (part of a spring–mounted moving mass) whose poles are intermeshed with those of an electromagnet powered directly by an AC line. This results in the spring–mounted moving mass being both attracted and repelled by the AC electromagnet equally on each half of the AC cycle."

Hmmmm, very nice.....

Well, despite what Eriez says about efficiency (usually Hi-efficiency = Hi-cost and may be unneccessary), there are plenty of "old style" feeders still being made, although some improvements are being made, as some controllers now offer full-wave rectification (120 DC pulses per second), as well as the older half-wave (60 DC pulses per second) system, including dual-mode control "at the flip of a switch".

Half-wave rectification would also be a 50% duty cycle, so half of the mechanical cycle would be powered and the other half would be a spring energy return. The mechanical cycle would then by 60 Hz. I wonder what part of the mechanical cycle is used for return if full-wave rectification (120 pps) provides 100% duty cycle? It seems like return can only take place against the lower magnetic force as the power drops to near zero and before it has peaked again on the next DC pulse, (assuming the original sinusoidal wave form is still in effect after rectification).

That should result in a higher frequency (120 Hz), but also less travel (amplitude) of the mechanical cycle. For the same part feed rate (considering you may have to adjust the electrical power amplitude to acheive non-varying feed), would changing to full-wave rectification be less efficient, more efficient, or the same with respect to energy usage?

Hmmmm....might make for a good challenge, eh?

STL, There are loads of old Stereo Class AB Hi Fi amplifiers at car boot sales. Anybody with a mind to make one of these, could well find it a handy power source. 55 volts needed for the MOSFETS, as a rule. I can envisage a machine with four knobs. Two sinusoidal wave generators that one could tune the frequency, and two 'volume' knobs? A notebook computer for the stereo output wave generator/ volume knob and all one would need would be the Amplifier. Class AB Metal Oxide Field Effect Transistors are Self regulating, if they get too hot, they draw less current. Very efficient. They use them on our Channell Tunnel trains. Made by GEC. I have looked at those MOSFETs and thought ROCK CONCERT...... JIMMY HENDRIX..... STAR SPANGLED BANNER.....like you never heard it before!

Postscript:- "Where there is Muck, there is Brass" Old English Proverb. Any Inventors with a mind to cash in on refuse, it's a gigantic business, could well profit by vibrational separation, following drying and pulverisation?

STL I just now noticed your 'avatar'. I don't think I've ever seen a cowboy carrying a pick and a slide rule before...

I'm of slide rule vintage myself; still have several, but it has been a while since I used one...

With a full-wave rectified DC system, there will be a short time while the diodes are below their threshold conducting voltage (longer time at lower AC voltages) to release the magnetic attraction. It should be much more efficient to use modern magnets that both attract and repel, than simply attracting a piece of steel with pulsating DC.

Thanks DKWarner for pointing out the 'Sly-Drule' well spotted, mine is a 'Thornton' and still gets used from time to time. 3 significant figures is often OK by me. Our intrepid Engineer has persuaded me to don my thinking cap. A Sheet of Fool's Cap paper....+ sticky tape to make the cone. Check out, PVDF :-> http://www.texloc.com/closet/cl_pvdf_properties.htm < Also :-> http://en.wikipedia.org/wiki/PVDF < KYNAR as it is known is both Piezo & Pyro- Electric. Now that all things seem to be going micro & nano, why not just metalise a pre-formed sheet of PVDF?......Suck-it-n-see? I don't know if the induced vibrations would be strong enough, but it might be worth a try?

Thanks for noticing the "avatar", but that's no Cowboy! That is Joe the Miner, or just plain Joe Miner, as he is affectionately known at my Alma Mater, where he is the school Mascot. You see, UM-Rolla used to be the Missouri School of Mines and Metallurgy (MSM for short). Back in the early 1880's when the first 3 engineers graduated, although they had all studied the same curriculum, they were allowed to choose what degree they received. Two opted for Mining Engineering and one for Mechanical Engineering.

Back then, the American West was still full of scruffy "varmints" like Joe. Sometimes they were known as "prospectors", but they were actually Miners, looking for gold, silver, copper, etc. Notice that his boots are flat-heeled, rounded-toe Engineer boots, needed for sure footing on hillsides and steep Mine tunnels, not high-heeled, pointy-toed "Cowboy" boots, which they needed to keep their feet in the stirrups, kick their horse in the ribs to make him go, and "dig their heels in" when roping a stray calf on the ground for branding. His six-gun is slung low on his waist, primarily to protect himself from "snakes", the two-legged kind, claim-jumpers! Notice also that he carries a pick-axe, one of the primary tools of mining. A pick-axe is also one of the two tools, with a hammer, that are crossed, like swords, behind a huge gear, the "big iron wheel", on the school's official emblem.

But Joe is no ordinary Miner, since he carries a big slide rule, so he can crunch big numbers, obviously! At one time in the early 1980's there was an attempt to replace the slide rule with a digital calculator, but it just wasn't the same thing. There is also a cleaned up image which is supposed to display better on computers than this old hand drawing, but, like the slide rule, I think the hand drawing has more "character".

Here are the two side-by-side. Tell me what you think!

I like the one on the right, as the one on the left looks to be a little too 'sanitized.' Even the one on the right is pretty clean-cut for 19th-century miner, but you've got to draw the line somewhere!

I noticed that in the 1880s only three guys graduated - out of a class of 600! Just kidding! (If you'd like, you can make fun of my Alma Mater, the University of Colorado (Buffaloes). 1800s miners ate buffalo, btw.

I also did a short stint at Harvard University, but you can't eat those types - unless you're a cannibal with a craving for 17th-century faux Pilgrims.

No, but with a six-gun, (doing my best John Wayne impression) you can sure shoot 'em, Pilgrim!

I've et buffalo. It's pretty good! Taste is sweeter than beef, without being nauseating like horsemeat.

Don't forget another item of the Miner's diet, but only as a last resort, he could eat his donkey! After all, the Spanish word for donkey is burro, from which comes the word burrito, or "little donkey"! I guess that is what they originally filled them with, a litttle donkey meat!

I stand corrected! I hadn't noticed the boots...

I agree with guest and you, STL; the one on the right is more appropriate. I suspect that the higher contrast also makes it display better at low resolutions.

Dick

I prefer the one on the right with more detail as well. It is the hand drawn original. However, apparently, all that detail, with multiple color shades, make it less "computer friendly" and so the newer "sanitized" version was created. You can see that Joe still has that "5 O'Clock Shadow" in the new version, but it reminds me more of Fred Flintstone than a grizzled old prospector! I like the really scruffy look of the original much better. Even his clothes look bedraggled. That is why I choose that one for my "avatar". Although the University seems to prefer New Joe, I still like Old Joe better!

Just Done a Compromise Version in Windows 'Edit' How do I get it to you? STL Engineer, I can do half a dozen or so to choose from.

Vibrating spiral elevators are common equipment in the material handling industry.

Click http://www.carmanindustries.com/Pages/spiralelev.html for more info.

Regards, Delmar Schmidt
Melfi Technologies Houston
www.melfitechnologies.com

Thanks Delmar,

Just the ticket for a 'Shot Blasting/Peening room. Now let's make the 'Floor' sweep all that 'Shot/Abrasive' into the corner, all by itself? But have something to stand on that does not vibrate, 'White Finger' is bad enough, 'White Toe' would be a nightmare.

You can always use an industrial vacuum cleaner to pickup the shot from the floor.

Click http://www.hi-vac.com/hihome.htm

Regards, Delmar Schmidt
Melfi Technologies Houston
www.melfitechnologies.com

Quite So Delma, Thanks again, magnetic brushes will preferentially pick up the shot as well. but vacuums also tend to pick up a lot of things one does not want. OK one can filter them out etc. I just thought it would be 'Neat' to vibrate the shot one way and the dirt another. Coin Slot machines rely on 'bounce' to reject duff coin. perhaps 'bounce' could sort shot/abrasive? I am 'Pipe-Dreaming' Delma

You are a Saint Delmar ... The 'pipe dream' is taking shape. why not use both vibration and vacuum. Floor Tiles with internal vibration to 'sort' the shot/abrasive and dual channel suction to deliver the tackle to the right destination. Each 'Tile' made to interlink so no external plumbing required? Much easier said than done, but much better use of 'grey matter' than fretting about the News! I can think of numerous solutions for creating the vibrations. now that you can buy strong flexible magnetic strip in rolls. Fleming's LEFT hand rule applies.

You are quite correct that a vacuum will pickup the shot plus all other available trash in the area. However once the shot is in the vacuum it will be tremendously easy to separate the heavy shot from the light trash.

All materials require a certain velocity to stay airborne. Once inside the vacuum there will be a large volume to slow down the airflow, be it the collection hopper or cyclone. The shot will quickly fall out of the airstream while the trash will be carried out.

Regards, Delmar Schmidt
Melfi Technologies Houston
www.melfitechnologies.com

Combine Harvester does much the same thing. You would be amazed what a variety of abrasives and peening materials are employed. Dry Ice peening, Corn Fakes for cleaning Food Equipment. walnut and pecan shells, the mind boggles. Sharp glass/grit followed by round shot to 'bash' peaks and create overhangs for mechanical adhesion of obstinate coatings. First they can't get a coating to stick, then they complain they can't get it off! This is Pendle Witch Country....."Eye of Newt & Wings of Bat" for cleaning Cauldrons.