[Laser] Contentof Laser Digest, Vol 77, Issue 1, LASER Cutter

Tue Mar 1 16:28:00 EST 2011

I agree about the power estimates.  I had the same question.  The other 
aspect  I'd worry about is the stray light (laser beam).  Anything 
capable of cutting steel at these levels would cut human flesh in 
microseconds and blind in the same time frames.  Even reflections would 
be very intense at these power levels..  So what do they do -- fill the 
vehicle with light adsorbing/scattering foam?  Maybe the students are 
doing their dissertation in science fiction.
Regards,
Charles Patton K6PIP

Dieter Palme wrote:
> It must be a very big batt!
>
> 300 ft lenght x 1/2" thickness x 1/20" cut = approx. 90 inch ^3 volumen
> to melt, Fe -> 131 gr/inch^3 -> 11.8 kg Fe.
>
> Heat of fusion (Fe) 14 kWs/mol, specific weight of Fe ~19 g/mol. 11,8 kg
> Fe -> 620 mol, needed Power 620 mol x 14 kWs/mol = 8700 kWs. In 6 min =
> 360 sec, 8700 kWsec /360sec = 24 kWatt optical Power for 6 Minutes. The
> electrical power for the laser must many times the optical power.
>
> If the cut is down of 1/200" (a very sharp focus) the needed Power
> decreases by 1/10. P -> 2.5 kW optical Power. Many kWatt's electrical
> power also.
>
> The efficiency of lasers differs from 3 to 40 %. For cutting is a stream
> of oxygen helpfull the iron burns in O2-gas and produces additional heat
> for melting.
>
> This system should be possible. Not more then 5 kW for 6 min are needed.
>
> Dieter - dl7udp -
>
>
>
> -----Ursprüngliche Nachricht-----
> Von: laser-bounces at mailman.qth.net
> [mailto:laser-bounces at mailman.qth.net] Im Auftrag von
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> Gesendet: Dienstag, 1. März 2011 18:01
> An: laser at mailman.qth.net
> Betreff: Laser Digest, Vol 77, Issue 1
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> Today's Topics:
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>    1. Battery-powered LASER cutter could save car accident victims
>       (bernieS)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 01 Mar 2011 11:40:45 -0500
> From: bernieS <bernies at netaxs.com>
> Subject: [Laser] Battery-powered LASER cutter could save car accident
> 	victims
> To: laser at mailman.qth.net
> Message-ID: <20110301164054.A73BC88011 at mailman.qth.net>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
>
> Does anyone here besides me think it's a bogus claim that this thing 
> can "cut 300 feet of half-inch-thick steel in six minutes on a single 
> (50lb) battery charge"?
>
> -Ed
>
>
> http://www.emergencymgmt.com/health/Beam-Life-DeviceCar-Accident-022511.
> html
>
> Beam of Life Device Could Save Car Accident Victims
> By: Corey McKenna on February 25, 2011
>
> Two students at Ball State University in Muncie, Ind., are working on 
> commercializing a battery-operated laser cutter that could help first 
> responders shave minutes off the time it takes to free someone 
> trapped in a crashed vehicle. The students, Adam Odgaard and John 
> Benjamin, say the device is quieter and generates fewer sparks than 
> hydraulic cutters currently used by rescue workers.
>
> The tool, dubbed the Beam of Life Device (BOLD), can cut 300 feet of 
> half-inch-thick steel in six minutes on a single battery charge. 
> Odgaard said he and Benjamin found that an average extrication takes 
> nine to 15 minutes. Odgaard said the BOLD could be at least three 
> minutes faster than that. A proposed backpack design could help 
> rescuers get into tighter spaces than hydraulic tools.
>
> The current prototype, a desktop model, was developed by Tim Bradley, 
> an engineer at the Naval Surface Warfare Center in Crane, Ind. The 
> next step is for Odgaard and Benjamin to secure funding to develop a 
> smaller prototype in which the power supply fits in a 50-pound 
> backpack connected to a wand that a firefighter could operate single 
> handedly. The target weight for the device is comparable to the 
> weight of similar tools on the market, such as the Hurst Jaws of Life 
> line of tools, to which the BOLD is being positioned as an alternative.
>
> "You have to be able to get the shears in there, and then when the 
> shears are going it will work against you and tire out most of the 
> rescue responders trying to cut through steel," Benjamin said. With 
> the BOLD, "you don't have to create an entry for your cutters to be 
> placed inside the vehicle."
>
> The BOLD also does away with carbon dioxide emissions so rescue 
> workers won't have exhaust from the device blowing back at them.
>
> Odgaard and Benjamin, who both study entrepreneurship, expect 
> development of a smaller prototype to take about six months. That 
> will be followed by a year of testing and evaluation with fire 
> departments. The BOLD could be available for purchase by the end of
> 2012.
>
> In 2009, more than 8,600 people were involved in motor vehicle 
> crashes that required extrication, according to the National Highway 
> Traffic Safety Administration. That number has been steadily rising, 
> according to Frank Pintar, a professor in the Department of 
> Neurosurgery at the Medical College of Wisconsin. Pintar is part of a 
> team that's studying how to improve extrication methods.
>
> There have been instances, Pintar said, where firefighters have 
> endangered themselves or each other while attempting extrications. He 
> sees a place in the field for a device like the BOLD if it can reduce 
> the likelihood of those injuries.
>
> "I don't see this taking the place of the Jaws of Life," he said. "It 
> sounds like it's obviously a quieter device, and it might work just 
> as well as a Sawzall without the dust flying all over the place and 
> that kind of thing."
>
> One advantage of hydraulic tools is that they support portions of a 
> vehicle being cut. "In extrication you can't just cut metal," he 
> said, "because sometimes a crumpled [piece of] metal that you cut 
> will collapse the rest of the car and you'll actually endanger the 
> occupant or other firefighters by doing that. So a hydraulic device 
> actually adds stability to a crumpled car as opposed to just cutting 
> things away."
>
> Hydraulic cutters and spreaders are useful, Pintar said, when an 
> occupant's limb is trapped in some kind of sheet metal. Where the 
> BOLD would be useful is when an occupant is trapped in a car without 
> being entangled by metal. "Let's say you would cut all the A-pillars 
> of the car and just take the roof off, and then extricate the 
> occupant from the top of the roof," he said. "Then this device might 
> come in handy, but essentially that's what a Sawzall will do as well."
>
> Odgaard and Benjamin are not the only ones attempting to market a 
> battery-powered rescue tool. Both Hurst and Milwaukee Electric Tool 
> Corp., maker of the Sawzall reciprocating saw, market battery-powered
> tools.
>    
>
>
>
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