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wierdscience
01-01-2006, 08:29 PM
I have a job coming up for a customer that will require a variable speed setup on a small conveyor.

I plan on using a 1/2hp VFD and a 1/2hp 3~ TEFC gearmotor for power simple enough.My only concern is the motor cooling since the machine may spend 50% of it's time running below 900 rpm.
I'm thinking that I need to remove the cooling fan on the motor and install a large muffin fan on the fan guard so the motor has maximum air flow even at low speed.

Do I need to go to that trouble or not?

Dawai
01-01-2006, 08:30 PM
use a 1.15SF motor if possible... difference is heat rating on the windings and cooling.. ohh.. sorry.. 1.0 duty factor is 100% rating load and run time..

Most the time a motor only heats according to load and cooling.. if it is sized properly, ie never pulls full current it will cool fine.. probably...

[This message has been edited by David E Cofer (edited 01-01-2006).]

CCWKen
01-01-2006, 08:36 PM
I'd gear or sprocket it down to the most used speed with the motor at 90-100% rpm. The VFD will allow higher speeds when needed. The gear-down will also provide more torque when the speed is lowered.

Just a thought.

Forrest Addy
01-02-2006, 12:27 AM
The muffin fan is a good way to go for plain air over shell cooling independent of the motor. The others mentioned re-rationing so the most frequently run speed is in the "dat zone" of the motor/VFD sharacteristics.

Look carefully at conveyor product load Vs speed. Gravity hopper fed conveyors tend to stck up the load on the belt when the belt slows down. If you're thinking of using converging conveyors as a continuous proportioning system, this stuff has been worked out already to whatever degree you can afford to implement from basic weigh/proportion to a system that feeds ingredients to a continuous food prep line.

For now, look for complicating factors before you simply install a VFD to proportion beet pulp to cattle feed or sand to gravel for example.

I'd strongly reccommend you install a snap action thermostatic switch internally on the motor's stator and bring out leads to a motor O/H annunciator light, the PLC, or what ever you have controlling the line.

wierdscience
01-02-2006, 11:46 PM
<font face="Verdana, Arial" size="2">Originally posted by Forrest Addy:
The muffin fan is a good way to go for plain air over shell cooling independent of the motor. The others mentioned re-rationing so the most frequently run speed is in the "dat zone" of the motor/VFD sharacteristics.

Look carefully at conveyor product load Vs speed. Gravity hopper fed conveyors tend to stck up the load on the belt when the belt slows down. If you're thinking of using converging conveyors as a continuous proportioning system, this stuff has been worked out already to whatever degree you can afford to implement from basic weigh/proportion to a system that feeds ingredients to a continuous food prep line.

For now, look for complicating factors before you simply install a VFD to proportion beet pulp to cattle feed or sand to gravel for example.

I'd strongly reccommend you install a snap action thermostatic switch internally on the motor's stator and bring out leads to a motor O/H annunciator light, the PLC, or what ever you have controlling the line. </font>

I usually put a plug-in fusable link nested in the windings for just such occasions.If the windings hit more than 190f the link melts and drops power to the control whatever it maybe.

In reality it's not going on a conveyor,that was the simplest description I could come up with.What this is intended to do is pull a rubberized fabric away from an industrial sewing machine the primary requirement being to maintain roughly approximate tension to the material.

The feed rate between runs is pretty consistant,but it does vary between batches of material.My plan is to shoot for the middle using a gear reducer to make up the bulk of the ratio.Te motor will be about 2x's the power the unit will ever actually require so there is a saftey factor.Basically the only reason I am considering adding the cooling fan is as a belt and suspenders measure.Once I deliver and setup a machine I don't want any reason for the customer to call me unless they want more stuff built.

Dawai
01-03-2006, 12:18 AM
It's your lucky day.. Them Stepping sychronous motors I got, they be on a sewing arm with a small conveyor toothed belt turned down. Made to pull a sewing fabric away.

Fixed rpm thou. I can get you a picture if you want one or two, or three, or.. They also have some solonoids and air cylinders for something? I think they came from a jeans plant. I also have some air lift tables.. somewhere.. (*bought at auction)

The sewing machine I have here? I moved the arm on the pedal to make more pedal depression for full speed-lever stroke. Since it is a clutch and not a transmission or variable speed motor it is still hard to sew on the leather and pad. Get it to start piercing and it takes off like a jet. It is a consew 226R? I am still learning, but about sewed all my leather up. Not happy with anything I have made yet. I did make my wife a purse out of purple leather, two sandbags for smacking sheet on.. a roll and tuck piece that is useless, and some rolled cushions for a bike seat.

If it was my sewing machine? I'd buy one of the vary-speed dc motors off ebay.. right now at $145.. I got a old 122 singer.. I wish someone else had it. It's old.. Like using a antique dump truck.. it will haul gravel, but don't get in a hurry.

wierdscience
01-03-2006, 12:52 AM
Thanks for the offer David.Did I mention that these panels they are sewing are 100'x150'? http://bbs.homeshopmachinist.net//biggrin.gif
The suckers wiegh about 450lbs when finished.

The machine they use is also a Consew,don't know what model,but it's got a 36 or 40" throat on it,bout a 2-3hp clutch motor too.

In order for it to maintain tension,but still slip when the machine stops or slows I'm going to use a fluid coupling on one sprocket.I can set the break away torque that way I hope so when the machine feeds the puller will maintain a tug on it,but when it slows it will slip and not break a needle.

Dawai
01-03-2006, 01:32 AM
Sounds like you need all of them then.. he he..

Seriously? They put a lot more engineering into this than you think. They used the synch-stepping motors cause they would apply torque, then over-step when stalled out. It does not affect the motor in the least to stall out while under power. When the foot feeds, it pulls and accellerates to keep torque on fabric.

I think I have four, five or six already together and on arms and assembled. Is this for you or a customer?

I'm as broke as a church mouse at the moment, if you gotta have one right now you gotta pay shipping up front. I can get you a picture and a number of how many I got tommorrow.

Is this a Katrina-tent job?

You got my phone number don'cha?

Dawai
01-03-2006, 01:25 PM
http://img.photobucket.com/albums/v85/ibewgypsie/Sscn1300.jpg
http://img.photobucket.com/albums/v85/ibewgypsie/Sscn1299.jpg
http://img.photobucket.com/albums/v85/ibewgypsie/Sscn1298.jpg

This is what the engineers came up with to pull fabric across a sewing table.

I done decided I am keeping at least two, so three are yours if you can make us a buck.

No clue what it takes to make the tiny dc motor run there at the rollers, the synch stepper requires a resistor and capacitor across the two windings, a neutral and a hot switched forward, reverse. Motor has no cooling, Motor is not hurt by stalling out, Motor is 72rpm geared up by toothed belts. Belt is like a bulldozer drive.

It should pull canvas or rubberized fabric, if you need more pull, use more than one.

Some of these used air motors, I done cannabilized all them, most the motors off these too to make room.

wierdscience
01-04-2006, 12:38 AM
Nah,not for me,what they are doing is making fabric(rubberized kevlar 1/16" thick) mats to lay on the ground underneath colapseable tanks.The tanks can hold 35,000 and 65,000 gallons of liquid anything from water to diesel fuel,but will fold up to fit in a 4x4x8' box.

They have tried similar units to what you have there,but moving this stuff is a bear.The system that works for them is a traction belt covered roller 60" wide with several pressure wheels on top pinching the fabric between the two.I've already built the unit that feeds the material to the machine operator while he is sewing,this next one will eliminate and man who's job it is now to pull the stitched seam through 10' at a time.

I'll post picks when I'm through.

Dawai
01-04-2006, 12:48 AM
Okie..

Yeah sounds like you need torque drives, not actually speed controlled.. some vfd's have it in thier setup. You just turn the knob to vary the torque. Speed is independent.

Digital followers is what I used on paper machines, I did one machine that had a drive on each side, one was master, other followed. It tuned in so good the paper would not rip. You could do skew and bow correction too.

Sounds like a nightmare. I saw a hydraulic press roller that a man went through at E&B, he came out other end of the oven 1" thick. They said a steel toe shoe would have prevented it.. his foot got caught. Pneumatic roller ejectors at shaw carpet, I put them in and they crushed a guy, he got around there to help press out a roll by hand. All they had to do was turn up the air..
Anyways, be careful.

I was tryin to help ya..

wierdscience
01-04-2006, 01:17 AM
<font face="Verdana, Arial" size="2">Originally posted by David E Cofer:
Okie..


I was tryin to help ya.. </font>

I know and I appreciate it brother.