shape factor y helical gears standard agma

[meccanicamg]

Here we are with a question that I need to solve.

I am preparing an excel sheet for calculating a pair of external cylindrical wheels and I am using the ansi/agma 2101-d04 metric standard. to say the truth I have also consulted the previous agma and the din 3990 but history changes radically.

with the term y is indicated for the Americans the form factor that is not the factor of lewis, so says the norm and is less than 1.

I had the values calculated by kisssoft and I'm sure they're inconfutable. I can't count by hand.

♪
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mn=6
pressure angle = 20°
helical angle = 12°
interasse = 270mm
x1=+0,41730 profile shift with present subtitles
x2=+0,13268 profile shift

provided that I still have to find to correctly calculate the parable of lewis, I used thickness and height of the tooth in the critical section with the base beams of the tooth obtained from kisssoft.

with the following formula I come y1=2,96 al post di y1=0,596and should be like this:Can anyone help me out, please?

already in the formulas of kf I found that in a norm the radiants and other degrees are used.... Who knows that's something trivial. . .

other formula provides me y1=0,418 but still we are not:Of course, for geometry, I'm using agma-908-b89, but it's not that I'm getting out of it a lot.

 

[Stan9411]

in the first formula there is something that does not come back to dimensional level.
what is “ch”? the only way to make subtraction dimensionally possible in square brackets is that it is a pure number (adimensional). waiting for your answer, I suppose it is a pure number; means that the result of subtraction has size [1/m]; the multiply for a relationship between things, therefore nothing changes; Then I divide a k_psi (suppose) coefficient for the value I obtained; the result is that y is not a coefficient (which I suppose should be adimensional), but has size [m].
Unfortunately I am not practical with these norms, so I would not be able to find mistakes that go beyond pure mathematics.

 

[meccanicamg]

ch is the helix factor of wellauer & seireg and as such is adimensional.

 

[Stan9411]

I therefore agree with me that in the first formula y comes a dimensional quantity (a length ) . is right ? I think not, calling y “form coefficient”.
So I wouldn't trust that formula, so it seems to me to be the one that gives you the most distant result from what you want.

 

[exxon]

for me, in the first formula lacks the module to the denominator.
inserting it, the dimensions go to place and the results come very close.

 

[meccanicamg]

I also have the doubt that m. I just didn't find a wrong courier of this formula. Maybe she ran away. deepen your search.
in the meantime I thank for the availability and who first comes....post the news?

 

[antonio_sc]

Hello mechanicalmg,

if it can be useful I found the following document
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1023.8460&rep=rep1&type=pdfalso here in the formula is not present the module "m"

 

[exxon]

in the document linked in #7, yc has size [1]/[L], (the reverse of a length) and these dimensions are consistent with the others in the document.

the formula is the same reported in #1 less than the numbering factor (from here probably the difference between y and yc).

in these formulas, where grouped numerical factors appear (1.5, 6, 0.95, etc.), it is essential to know with certainty the units of measurement. in the document (data 1960...) linked to #7 and of imperial origin, the pressure is expressed in psi and certainly the lengths are in inches, while in other more recent documents that probably make head to the system yes, the same pressure could be expressed in pa and the lengths in meters, with upheaval of the final result.

 

[meccanicamg]

In fact with the history that the Agma was born with imperial units of measurement and then made the rule in metric is a disaster to make the right accounts.

At this point I should try to put the imperial values on this formula I found...and yet it is not right yet because it does y1=0,64 But better than before.

 

[+forte]

I had pdfs... even if you have already done

 

[meccanicamg]

honda i pdf is the original norms on the glossy white paper but I think it is missing a piece at all this or wrong something because it is not possible that in all these years no one has noticed.

some formulas predicted the value of "grades" in radiant ....think you that pumpkin they had

 

[exxon]

Actually, the radiant must be used in analytical treatment to indicate the anomaly (the corner) of the trigonometric functions. Therefore the derivatives, speed and angular acceleration, are expressed in radiants to the second and second-square, and all the sizes are consistent. when you start using degrees and rpm, normally everything goes to prostitutes.

 

[meccanicamg]

Actually, the radiant must be used in analytical treatment to indicate the anomaly (the corner) of the trigonometric functions. Therefore the derivatives, speed and angular acceleration, are expressed in radiants to the second and second-square, and all the sizes are consistent. when you start using degrees and rpm, normally everything goes to prostitutes.

strange because for all the rest of the norm uses the degrees and not the radiants.... less than a formula.

 

[exxon]

the degrees are used (and menomal which is so...) to the extent of mechanical angles.

in formulas, when they appear solo as an anomaly of a trigonometric function, it is indifferent to use degrees or radiants (i.e. the breast function is different depending on the topic is expressed in one way or another; who applies the formula chooses (often unconsciously) the right coupling).

if the corners are instead used in transcendent functions different from the trigonometrics as well, appear in differential or integral form, then must have be expressed in radiants (i.e. the calculation of the torque resistant to angular acceleration t=iα).

 

[brn]

mechanical a question.. .
I was implementing an excel sheet for the calculation of gears according to agma according to the steps on the shigley.
is reported the following table of the geometric coefficient where from the notation it seems all in imperial units but I have the doubt that it is in metric units (which would solve me a lot of problems!) from the values shown in the table comparing with your what it comes out?

already that there are not well understood the difference between a grade 1, grade 2, grade 3 of a steel, I think it depends on the degree of goodness of the material, for example a c40 will be a grade 2 and a 39nicromo3 will be a 3 (numbers randomly)
Thanks

 

[meccanicamg]

mechanical a question.. .
I was implementing an excel sheet for the calculation of gears according to agma according to the steps on the shigley.
is reported the following table of the geometric coefficient where from the notation it seems all in imperial units but I have the doubt that it is in metric units (which would solve me a lot of problems!) from the values shown in the table comparing with your what it comes out?

already that there are not well understood the difference between a grade 1, grade 2, grade 3 of a steel, I think it depends on the degree of goodness of the material, for example a c40 will be a grade 2 and a 39nicromo3 will be a 3 (numbers randomly)
ThanksView attachment 59143

First of all, the curves you have attached are adimensional and therefore are good for metric and imperial.
on the shigley there are indicated coefficients that are used and formulas for the metric system and those for the imperial.

the degree of sae steels is to indicate the type of chemical composition that corresponds to the mechanical resistance of steels. you can see the classification qui.

If you look well on the forum there is a post where a student used these curves and we also built a curve that was missing.....the discussion is This is what.

 

[meccanicamg]

The question should be examined better, but the three degrees correspond to the treatment and quality of the material.

the grade 1 is the cementing steel. has a superficial hardness of rockwell c (hrc) 61-63 and a hardness of the core of 45-46 hrc.

the grade 2 is a deep nitroration steel. after normalization, tempering, tempering and nitruption with conventional methods, grade 2 has the depth of hardness up to 0.5mm reaching 760-800hv and hardness of the core of hrc 46-48; a tensile strength (uts) of 1550-1625mpa.

the grade 3 is a high strength steel. after heart tempering, grade 3 has a surface and internal hardness of hrc 58-60, and a breaking load of 2245-2310 mpa.

 

[brn]

So I have to say you confused me a little...

the book reports j in in inches and yj metric so if you tell me that I'm the same thing is just a round notation?

on the degrees the book brings me two linear curves that bind the hb hardness to the admissible sigma of lewis according to agma, the two curves are different depending on grade 1 or2 and refer both to hardened bonifica steels to heart, for nitrides there are other similar curves with grade 1 and 2

 

[meccanicamg]

So I have to say you confused me a little...

the book reports j in in inches and yj metric so if you tell me that I'm the same thing is just a round notation?

on the degrees the book brings me two linear curves that bind the hb hardness to the admissible sigma of lewis according to agma, the two curves are different depending on grade 1 or2 and refer both to hardened bonifica steels to heart, for nitrides there are other similar curves with grade 1 and 2

the curves are built using number of teeth that is adimensional and the result j or yj is the same in the two systems....his be uses inches or mm.
simply the two systems have the names of this different coefficient but it is a... equal number.There are a myriad of coefficients with double names in the norm....if you go ahead you will run them....one for all reliability....that has no unit of measurement...that is and remains.
if there are different formulas for equal coefficients, it is explicit directly:in the curves below for example refers to:- nitrate steel grade 1
- nitrate steel grade 2
- chromium steel grade 1
- grade 2 chrome steel
- chrome grade 3 steel
like all Anglo-Saxon things there is always a big mess in explanations and translations.

the reality is that the three degrees correspond to those indicated in iso 6336 the characteristics of supply:
ml= grade 1 = minimum characteristics
m2 = grade 2 = average characteristics
me = grade 3 = high characteristics
mx = - = special characteristics

Besides having different heat treatment for the heart, there are also a series of certificates, tests and guarantees on the material that distinguishes the three cases. is explained well on iso 6336-5