design of a stirrer 1

[kchiguvari]

i would like to enquire how the design of a stirrer mechanism for powder material in a conical hopper can be done. is this the same theory you would find in fan design.

 

[plasgears]

If you are talking about powder and fines, a steep conical shape would be best. Also, consider a vibratory bridge break like they use in chemical equipt. It's a shaker that loosens compacted fines over the outlet.

 

[kchiguvari]

the problem that is to be solved is to ensure reliable flow of material on an existing extrusion machine. the problem is that material(PVC mixed with rechip) is not moving freely in the hopper due to the heat content from the rechip material. this requires a disturbing mechanism like a stirrer to ensure lumping does not occur. i would like to ask whether there are existing stirrers for such problems

 

[Soupcat]

kchiguvari,

I had a similar problem a number of years ago when involved in the design of a material feed system for a Rotational moulding machine. Whilst I didn't investigate stirrers available at the time, I did come up with a good solution. I piped compressed air into the hopper and pulsed it using a solenoid valve on the pipe. This worked very well for me as it agitated the material enough to prevent bridging. Hope it provides you with soome food for thought!

Regards

Kieran Fegan.

http://www.moulddesigner.com

 

[funnelguy]

It is possible that a simple bent rod swept around the interior of the hopper will do the job. Find a suitable gearmotor build a bracket to support it and have at it. Also, are you cooling the feed throat sufficiently?

 

[patprimmer]

I like Soupcat's idea of air pulses. Also give it time to cool after regrinding, before useing.

Also, sometimes it turns out to br more economical to resquirt and peletise your regrind, if you include effect of chip on stoppage and reject rates.

Remember when calculating cycle times and yeilds, to only include the mouldings you actualy get paid for.

Regards
pat