Torque requirement for a sand mixer / motor selection
Torque requirement for a sand mixer / motor selection
(OP)
Hi everyone,
I am in the process of designing a sand mixer and could use some help with calculating the motor torque requirements.
Some details:
It is silica sand in a small mixing vessel that is inclined at 60 degrees from horizontal. The vessel is 11.2 inches in height and 8 inches in diameter and will be half filled with sand, it will have blades that rotate on the inside of the vessel that are similar to the ones in the image attached. I have calculated (also attached) the acceleration torque and the load torque (only from the drag on the blades due to the sand). I used the formula for drag force (F = 0.5 C ρ A V^2) (using the bulk density of silica) even though I know this is for drag force for fluids. For granular material should I try to calculate this a different way? At the end of my calculations I ended up with around 50 N.m as the required torque. Is this a reasonable value for the situation described? Is there a better way to figure this out for this situation?
Additionally, lets say that I do need about 50 N.m of torque with some uncertainty and I were to apply a safety factor of 2. So now my goal is to find a motor/gearbox assembly that will output 100 N.m of torque at an operating speed of 60 rpm (so 0.84 hp). What would the best kind of motor be for this application? Should I go for a DC/AC motor? Any suggestions for suppliers?
Thanks!
http://files.engineering.com/getfile.aspx?folder=5...
http://files.engineering.com/getfile.aspx?folder=8...
http://files.engineering.com/getfile.aspx?folder=c...
I am in the process of designing a sand mixer and could use some help with calculating the motor torque requirements.
Some details:
It is silica sand in a small mixing vessel that is inclined at 60 degrees from horizontal. The vessel is 11.2 inches in height and 8 inches in diameter and will be half filled with sand, it will have blades that rotate on the inside of the vessel that are similar to the ones in the image attached. I have calculated (also attached) the acceleration torque and the load torque (only from the drag on the blades due to the sand). I used the formula for drag force (F = 0.5 C ρ A V^2) (using the bulk density of silica) even though I know this is for drag force for fluids. For granular material should I try to calculate this a different way? At the end of my calculations I ended up with around 50 N.m as the required torque. Is this a reasonable value for the situation described? Is there a better way to figure this out for this situation?
Additionally, lets say that I do need about 50 N.m of torque with some uncertainty and I were to apply a safety factor of 2. So now my goal is to find a motor/gearbox assembly that will output 100 N.m of torque at an operating speed of 60 rpm (so 0.84 hp). What would the best kind of motor be for this application? Should I go for a DC/AC motor? Any suggestions for suppliers?
Thanks!
http://files.engineering.com/getfile.aspx?folder=5...
http://files.engineering.com/getfile.aspx?folder=8...
http://files.engineering.com/getfile.aspx?folder=c...





RE: Torque requirement for a sand mixer / motor selection
RE: Torque requirement for a sand mixer / motor selection
Once that is known I would design for that load to be safe.
RE: Torque requirement for a sand mixer / motor selection
We used to mix specialty foundry sands in one that also had a fixed blade that was inserted into the open end.
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P.E. Metallurgy, Plymouth Tube
RE: Torque requirement for a sand mixer / motor selection
http://www.harborfreight.com/1-1-4-quarter-cubic-f...
Just sayin, for less than what a day of head scratching will cost, you got it.
RE: Torque requirement for a sand mixer / motor selection
"Even,if you are a minority of one, truth is the truth."
Mahatma Gandhi.
RE: Torque requirement for a sand mixer / motor selection