45 degree 4

[okjim]

In a design for a scraper that is to skive off flooring, such as linoleum, tile etc, I am trying to prove that a 45 degree angled blade is the best choice for wear and capability. The blade will be flat to the floor and the leading edge is 45 degrees. Does anyone know how I can prove this to be true? Calculations or any other means would be very helpful. Thanks
Jim

 

[MiketheEngineer]

Not completely satisfied that this is correct. Yes - it will allow both the horizontal and vertical forces to be about equal.... but that may not be correct for the situation..

If you had say a 30 degree slope that would allow for more "shoving" or "pushing" power and maybe just enough "uplift" to break the bond. It does not take much to break the bond --- but obviousy depends on many unknowns...

Will this be power or man driven.

 

[telecomguy]

Usually, you let the engineering decide what is the best angle, rather than decide the angle and try to make the engineering prove it. I'm with Mike. It depends on the bonding forces, available 'pushing' power, friction coefficients, etc.

<tg>

 

[okjim]

The pushing power will come from hydraulic driven wheels, giving high pushing force.

Lets assume that the bonding of the material to be removed to be high also. If it were not, any angle would work (other than 90).

We can probably disregard the friction (although I realize it is there). I am trying to determine that when using the blade, the leading angle could be more or less than 45 degrees but to get a compromise between its wearability and its usefulness, 45 would be equally good for both.

Jim

 

[waross]

You would probably save a lot of time and gain a lot of functionality by supplying three blades, 30 deg, 45 deg, and 60 deg and letting the operator select and use the one he likes best.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[vc66]

At 45 degrees, you'd probably damage the underlying floor.

I would tend to go, floor to blade angle of 30° maximum.

You're trying to pry the linoleum/tile off the floor, not jack hammer it downwards. That's a whole different tool.

V

 

[Zapster]

I think you are oversimplifying the problem. How ridged is the equipment that holds the blade flat to the floor? What is the hardness of the base floor: is it wood or concrete? The hardness of the floor covering material should be considered as well. The problem becomes oversimplified if you assume that the blade is infinitely ridged. Wouldn’t the flexibility in the blade along with the angle and relative hardness of the materials involved tend to drive the blade into the floor base material or cause the blade to climb into the floor covering? That is why I like waross answer where you could have several blades to accommodate the various conditions where the tool could be used.

 

[griffengm]

While a 45 may be appropriate, I think that a look at the rake angle data for various materials for cutting tools might improve your chances of being close on the first try. See Machinery's Handbook.

Griffy

 

[okjim]

Before I go any farther, you need to know that this design was implemented, before I came along. I have been charged with finding a way to prove that the 45 degree lead angle is what will resist wear as well as skive the floor effectively.

The underlying floor is generally concrete and the overlay can be just about anything. The blade is ridged enough (1/2" thick) to be considered ridged. The blade can ride up and over the overlay, on occasion.

I have read in the cutting tool section of Machinery's Handbook but the application isn't exactly the same. The blade I am working with sits flat on the floor and the 45 degree leading angle separates the overlay from the concrete.

I understand this may seem to be oversimplified with all of the variables present, but I had thought there may be some known rule or way to calculate edge wear and/or edge effectiveness, for knives, scrapers, chisels etc.

 

[unclesyd]

The type blade you are proposing is considered expendable or possibly a regrind.

From what little I've seen of these blades working I would go with a compound angle and let the wear go where it may.

http://www.innovatechproducts.com/p...-removal.php?gclid=CJeOgpiBqJkCFQZinAodohEbow

 

[TenPenny]

I would think that you don't want the blade to be flat to the floor. I would think you'd want a small, maybe 5-10 deg angle there. 45 is probably too blunt for the blade edge, too.

It will probably matter also what flooring you're removing - is it flexible, ie, linoleum, or rigid, ie, tile?

 

[telecomguy]

Getting a little off topic since you're just wanting a proof of the 45 degree angle, but it seems to me that a serrated edge would perform better due to the concentrated force at the points and then the gradual lifting of the flooring.

<tg>

 

[ornerynorsk]

Go look at a wood plane and see what angle the blade sits at. This might be a good starting point, from which you may have to deviate in order to optimize the cut.

 

[IRstuff]

Seems to me that the objective, once the leading edge is broken free, is to minimize the "lift" i.e., the bending upwards of the material already dislodged. That would suggest that 45° is too high.

TTFN

FAQ731-376

 

[MiketheEngineer]

If you have the time and money - try a few samples...

You might be in for a surprise.

 

[ewh]

Come on, people. Read the question!

...this design was implemented, before I came along. I have been charged with finding a way to prove that the 45 degree lead angle is what will resist wear as well as skive the floor effectively.

The OP is not asking how to find the optimum angle, but how to prove that the existing angle is adequate.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[vc66]

Before I go any farther, you need to know that this design was implemented, before I came along. I have been charged with finding a way to prove that the 45 degree lead angle is what will resist wear as well as skive the floor effectively.

Can't help you, because I don't think that's correct.

V

 

[telecomguy]

I guess you'll have to setup the wear equations as a function of angle to determine if the 45 degrees is truely proving to resist wear to an acceptable level.(

http://en.wikipedia.org/wiki/Archard_equation)

<tg>

 

[MiketheEngineer]

Sometimes disproving it leads to better designs and the correct answer.

 

[KENAT]

Or to being fired for not being a team player.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?