I guess I'm back in the shaker business again. I posted a while back about some shaker conveyors, and you guys were very helpful. We built two conveyors, and I guess the customer liked them so much, they want us to build them a sieve shaker. We have only built trommel screens so this is a new challenge. This is what the customer requires.

They want to build a sieve shaker similar to fig 1.7, chapter 4, in the VSMA Handbook. It will have a total of ten shelves, with perforated plate screens. The screens will have square openings in the following sizes: 3",2.5",2",1.5",1.25",1",0.75",0.5",0.25" and the last drawer will be solid. They want to dump the product in at the top, run the machine for some period of time, an then measure the amount of materail in each drawer.

The material is the waste product from a scrap yard. The material (mostly cars) goes through a shredder. The material then passes under a large drum magnet and most of the ferrous material is removed. It proceeds to a trommel and the material is seperated into 3 or 4 sizes. Each size then goes down onto a shaker conveyor, over another drum magnet to remove more ferrous material, over another shaker then onto an eddy current separator. The eddy current separators typically have a long throw, short throw and then the rest goes into a waste pile. The customer wants to take this waste material and further process it to extract more "good" material. I don't really know the details of how they plan to process this material, but they want the sieve to determine the particle size that they are working with. So the material is primarily "fluff" (foam, plasitc, rubber, dirt), some nonferrous material and traces of ferrous material. I really can't give you a definite materail density since it varies greatly with moisture content (due to the large amounts of foam from car seats). If I had to guess, I would say it ranges from 15 to 40 lbs/ft^3.

I consulted the chart for the stroke and speed in the VSMA handbook for a horizontal screen w/ dry 100 lb/ft^3 material. (fig 1.2 ch 6) It appears that I should be running at 800 to 850 rpms, 1/2" to 5/8" stroke, and 5 to 6 g's. How do I adjust for material weight and moisture content?

Here is where I run into a problem. The customer is trying to save money by supplying two electric rotary vibrators, that he has on hand. I am stuck designing around these vibrators. The vibrators are Vibtec model MVSI 10/1110-S90 operating at 60 Hz. They have adjustable eccentric weights ranging from 0 lb in. to 62 lb in. each. They produce a max force of 2538 lbs at a a nomimal RPM of 1200 rpm. Each vibrator weighs 131 lbs.

I don't think that this is the right drive setup for this application. In order to achieve a 1/2" stroke I would have to limit the entire weight of my setup to around 500 lbs. That is not likely since my motors weigh in at 262 lbs. I am looking for some advice on this problem. Are my stroke and speed estimates correct.

Another problem I am having is determining the proper way to arrange the vibrators. Here are the arrangements that I am considering.

1) Mounting the vibrators on opposite sides, with the shafts horizontal, so that all of my force, and stroke, is in the vertical direction. I worry that the larger pieces will just bounce straight up and down and plug the holes.

2) I thought about tilting the drawers a few degrees and rotating the the motors slightly so that material will have "walk" uphill. I am not sure what angle would be best for the screens and the vibrators.

3) I thought about putting the motors on opposite sides, but turning the shafts 45 degrees off of vertical. I wanted to tilt the motors in opposite directions to create a twisting motion. I was afraid that this motion would just be erratic and would just twist itself apart.

4) I thought turning the shafts vertically and just shaking the screen back and forth. I am still worried about plugging since I will not be tossing the material.

5) I thought about a single vibrator mounted verticals to "swirl" the screen, but same problem as #4.

Sorry about the long winded post, but I wanted to give you as much detail as possible. I would appreciate any help, as I am not typically a shaker man.

Thanks,

Rob Brooker

Covington, Ky ■