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Join Date: May 2010
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Solar Beam Welding Using Fresnel Lens Focal Spot

03/02/2016 6:57 AM

Wanted to try some metal surfacing say Stelliting on valve seat rings and plugs with Solar Powered energy beam as in the case of a Fresnel focused beam. Is any one familiar with any available welding power source already to this application?

If not..can some one direct me to the best options of Fresnel aqua or glass Lens or Fresnel Mirror.

How much power we need for the stellite surfacing at 3kJ /mm Heat input @ rotating rpm of 3 to 4.

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#1

Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/02/2016 8:04 AM

you wont come close to enough BTU"s....not close, you can get a pinpoint over 200 degrees F but not a seam

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#3
In reply to #1

Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/02/2016 1:49 PM

I meant 2000

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#2

Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/02/2016 1:22 PM

Stellite alloys tend to have extremely high melting points due to the cobalt and chromium content (thanks Wikipedia).

Perhaps your thinking of a laser, you won't be welding Stellite alloy with focused sunlight.

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#4

Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/02/2016 3:56 PM
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#8
In reply to #4

Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/07/2016 6:32 AM

THANKS IT WAS REALLY CONCLUSIVE..YOUR GUIDANCE..

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#9
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Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/16/2016 2:37 AM

Picture is of Mirror and not of lens.

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#10
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Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/16/2016 12:45 PM

Not true. I have eight. I've framed six as in the picture. The mirrors look NOTHING like this. Notice the concentric light shining THROUGH the image. It is not concentric and does not shine thru the mirrror's image, when photographed.

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#11
In reply to #10

Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/16/2016 3:14 PM

That is shadow in a mirror caused by blocking the light. These are concave metal mirrors and not perfect polished one but of partial reflections, partial diffusion and partial absorption. Lens never sends back light and only mirrors do. Prisms can send back light.

If you think that over the metal mirror surface there is thin lens over it then that may be a different reason to believe so.

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#5

Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/02/2016 8:55 PM

Old style projection TVs used a large fresnel lens and you can buy used ones (some blemishes) on EBay and other places surplus for not too much.

The maximum amount of solar power available is P = AL x 1000 W/square meter. So, the larger your lens area, AL, the more power you have available.

The spot size depends on the focal length, f. The sun subtends an angle of 1/2 degree, so you can figure the minimum spot diameter, d, with simple trig: d=pi/360 x f.

So the minimum spot area AS=pi x d squared / 4. Your maximum power per area would be P/AS.

At equilibrium, the amount of power leaving the spot (radiation, conduction, and reflection) equals the amount received. So to achieve the maximum temperature, you need to minimize conduction (insulate the target) and minimize reflection. (Shiny metals are difficult to heat because they reflect a lot of the energy.)

If the target were perfectly insulated and a black body, the temperature would theoretically reach the temperature of the sun, at which point the power radiated would equal the power received.

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#6

Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/03/2016 1:21 AM

And even if you get the power you still have to deal with flux or shielding gas to prevent oxide build up that would create defects.

You will also have to look at crystallization and warping issues are caused by a change in how you heat the metal.

There may be a need for a post heat to normalize the heat affected zone and a slower heat will increase the size of this zone.

Looks like good place to start.

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#7

Re: Solar Beam Welding Using Fresnel Lens Focal Spot

03/03/2016 10:33 AM

I thought that the installation of stellite valve seats into cylinders is performed by heating the cylinder while cooling the stellite seat so that at ambient temperature there is an interference fit between the two parts.

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Balakrishnanpullat (1); Fredski (2); jack of all trades (1); micahd02 (1); Rixter (1); Shyam (2); SolarEagle (1); U V (1); welderman (1)

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