shell core machine question

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todd goff
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Joined: Fri Jun 12, 2009 12:59 pm
Location: South Carolina

shell core machine question

Post by todd goff » Mon Feb 22, 2010 8:31 pm

I have been working on a couple of shell core machines that use propane to heat resin coated sands for foundry work to make cores but I think that I have finally hit a road block. The burners use valves to regulate the flow of air on the propane when it is burning thus giving some control over the temperature. Also, though it uses air to blow the resin coated sand into the core box packing it tighter. Well, when I dump the air going into the sand hopper it makes the pressure on my two air valves used in controlling the combustion go to zip. My question is this; if I mount an accumulator near the hopper to store some excess air would that fix the problem or should the accumulator be mounted on the side that has the 2 air valves that control the combustion? By the way, I had a brain storm and came up with a way to mount an asco 115 volt valve to dump the air pressure to the sand hopper and boy it sure does work sweet; flip a light switch and then she dumps. If only I could figure out a way to fix the air pressure dilema. :?:

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Shell core

Post by steamin10 » Mon Feb 22, 2010 9:34 pm

If I get your drift, your problem is your supply is too small. Your machine is set up with a hungry air operation, and goes flat just at a critical time. If you cant afford to get a LOT bigger supply, you will have to work around it by isolating your burner circuit, with a check, and storage, so no backflow occurs during your 'heavy need' dump timing. Some capacity like 10-20 gallons to smooth over the cycle may work, or get one of those annoying diaphram pumps and pull your burner circuit from that.

Another route is to get a BIG buffer tank to smooth out the presure drop, and give you reserve capacity. This will slo=w the reocery rate too. A second air compressor could be used for more recovery AND storage, I know of many furniture and bead blasters that have to do this for long blast times. They only have to stagger motor starts, to prevent voltage sag from causing a stall, by putting one 5 lbs away from each other on the cut in.

Figure which way you want to go, there are more ways to skin a cat, ya know.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
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