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Need a shear for cutting 3" aluminum bar

motion guru

Diamond
Joined
Dec 8, 2003
Location
Yacolt, WA
I am working on a flying shear to add to a continuous casting line that we did a few years ago. I need to cut through a 3" square aluminum bar at about 800 deg F and the cut needs to be complete in less than 1 second and at the shortest desired lengths, the cut would occur every 3 seconds.

I am thinking something like an Iron Worker Shearing action that would leave a nice square cut and we would mount this on a carriage that synched up with the bar as it was coming out of the caster (we are driving the casting wheel and have an accurate sense of position at all times). Based on similar systems we should be able to achieve +/- 0.030 inch cut accuracy if we comp for temps.

Anyone have a lead on a small form factor shear that we could integrate into a reciprocating carriage like this?

This is a flying shear for sheet metal - we are looking to emulate something similar to this with 3" bar stock.

 
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thanks for the links . . . I am space constrained. (This customer came to us because they realized that they would probably need something custom designed from scratch, we have the carriage and controls figured out - the shear is another animal)
 
I certainly would think 'sawing' before I thought 'shearing'. A stout motor and well designed carbide blade with a water spray mounted on a carriage moving with the flow of material. The 3 second time limit could be tough one to meet.

Stuart
 
Is standard guillotine shear configuration acceptable, or does each blade need to confine two sides to minimize distortion? For curiosity's sake, what is the shear strength of 800F aluminum straight from the concaster?
 
sawing is out of the question - no water allowed in the area and chips not wanted either.

Distortion is not that critical - these bars will be melted down again and used to alloy larger batches. A decently square cut would be nice for crating / shipping purposes.

I reached out to these guys with a query and will see what they might have to say . . . Advanced Machine Design
 
how about a standard shear section from a iron worked in a custom built hydralic press frame. lots of flow needed to get that cycle rate, but tonnage not a problem and it should be compact.
 
We can occupy only 6 feet of line length between caster and reducing mill. I don’t know what the shear strength is . . . Researching.
 
I would go with a mechanical punch press (new style with clutch/brake) for the speed needed.
But....sliding that mass back/forth on the flying cut-off carriage is tough.

Hydraulic ?
Look at what the hydraulic press makers came up with for "rapid forging" in the 1960's....IIRC Pacific press made one.

Basically a large nail gun.

But hydraulics are used to return the ram, compressing the nitrogen filled piston.
Actuation is by lifting the head off the top of the cylinder, so the whole top allows the inrush of the nitrogen.

Double opposing ram designs are also used to counteract any movement of the press.
CeCo name comes to mind.
 
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So, while I was killing time looking up the strength of aluminum at 800 degrees, I ran across this write-up:

800-Degree Aluminum Spill: Forklift Driver Puts Colleagues in Mortal Danger | foundry-planet.com - B2B Portal

If the aluminum in the story "exploded" when it hit a lesser-temp surface, could you leverage that thermal sensitivity for faster cutting -- as long as you can contain the shrapnel?

I think they were talking about 800 degrees C in that article... Not 800 degrees Fahrenheit :)
 
swatkins and gbent - yup, C vs. F, as noted by being molten. At 800F the aluminum will likely not yet be in a "sorta like toothpaste" state, but that can vary depending on silicon content, and perhaps other alloys. I'm going to guess shear and tensile will be pretty low, which should help with slicing, perhaps like pure lead.

I'd be looking at a flying pivoting chopper blade, with a not-cutting counterbalance to reduce vibration, both as compact to the structure as possible to minimize overturning forces. I asked about envelope not just for length, but also for width and height, and what is in the area for linear guiding (such as profile rails, which if not present would need to be added).
 








 
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