factor k development sheet.

[xxfast]

It seems that I will go to work in a workshop where I will take care of cutting and bending sheets.
I have searched on the forum and read so many things.
Now I would like to ask a practical question, just to begin to understand the matter well. . .
suppose to draw a piece to l 50x50 from 2 mm and internal radius 2mm. then I cut it to the laser and piego in the workshop. I mix the piece and see that the l is shorter than 0.1 mm on each side.
how do I understand the right value of the k factor to set up on sw to achieve correct development?
Thank you.

 

[Mr.Rio]

In this case you should increase k so that the sheet has a development of 0.2mm greater than the previous development.
greetings

 

[Mike1967]

It seems that I will go to work in a workshop where I will take care of cutting and bending sheets.
I have searched on the forum and read so many things.
Now I would like to ask a practical question, just to begin to understand the matter well. . .
suppose to draw a piece to l 50x50 from 2 mm and internal radius 2mm. then I cut it to the laser and piego in the workshop. I mix the piece and see that the l is shorter than 0.1 mm on each side.
how do I understand the right value of the k factor to set up on sw to achieve correct development?
Thank you.

Bye.
As you have already written, the matter has been dealt with many times, but I can give you my experience.
to establish the fk we have tested with various materials and thicknesses.
the difference between real quota and theoretical factor k "adjusted" them with the handle (= to attempts) inserting appropriate values in the field "factor k".
I put the table I use, there are also the measurements of the fold caves.

 

[xxfast]

Okay, thank you.
the k is set to attempts, as I imagined.
I wanted to know if there was a formula or a guideline for setting this value.

 

[maxopus]

It seems that I will go to work in a workshop where I will take care of cutting and bending sheets.
I have searched on the forum and read so many things.
Now I would like to ask a practical question, just to begin to understand the matter well. . .
suppose to draw a piece to l 50x50 from 2 mm and internal radius 2mm. then I cut it to the laser and piego in the workshop. I mix the piece and see that the l is shorter than 0.1 mm on each side.
how do I understand the right value of the k factor to set up on sw to achieve correct development?
Thank you.

Welcome to the hell of the thieves.

in truth since I am in my own I do always less, but I do not forget.
1) an error of 0.1 out of 50 is more than acceptable in this sector and it is very difficult to determine from what it derives, it could also be a machine/operator error or a very light cutting board.
2) normally for ductile materials (low carbon steel) it can reasonably be said that the k factor is close to 1/3 , for harder materials the value ranges from 0.4 to 0.5.
Obviously on pieces with many high folds and thicknesses the margin of error increases and it is absolutely advisable to do tests by using test.
each batch of steel has a different hardness depending on the chemical composition of casting and the rolling process

 

[radio]

......
1) an error of 0.1 out of 50 is more than acceptable in this sector and it is very difficult to determine from what it derives, it could also be a machine/operator error or a very light cutting board.
....
each batch of steel has a different hardness depending on the chemical composition of casting and the rolling process

quoto, you will hardly be able to get errors of lower entity, the only positioning for the fold can give you different errors on multiple equal pieces from the same sheet of sheet; if you then put sheet of different production batches, or different manufacturers a 0.1mm error (intensive as maximum dimensional difference between the measured pieces) is as little.


Bye.

 

[Marco74]

quoto, you will hardly be able to get errors of lower entity, the only positioning for the fold can give you different errors on multiple equal pieces from the same sheet of sheet; if you then put sheet of different production batches, or different manufacturers a 0.1mm error (intensive as maximum dimensional difference between the measured pieces) is as little.


Bye.

I fully agree, practically impossible even to stand in the tolerance of +/- 2/10.

 

[xxfast]

Thank you again to all.
tomorrow I attack and see what they're gonna do to me.
However, as far as I am concerned, I believe that the margin of error on the pieces I will develop will be quite wide.
I will certainly have other problems with the plates, anyway we feel here...:angry:

 

[alex_cm]

Hi.
as an indication in our company we use these values:

for sheets thickness 1-3mm and normal folds with radius r= sheet thickness (by approximation) the factor k is 0.273/0.275

for sheet thickness 1-3mm and rolling processing (so "foot" with very wide rays) the k factor is 0.8

we directly pass the dxf of developments (so no detailed quota: only the maximum size, bending and indication of threads, rigging or other).
And we don't have any big trouble in the end.

for all thicknesses above 3mm instead the k factor always remains the usual above, but we also provide the full quotation with the placement odds of holes and other processing.
the carpenters think about adjusting developments at the time of cutting.

 

[Mike1967]

Hi.
as an indication in our company we use these values:

for sheets thickness 1-3mm and normal folds with radius r= sheet thickness (by approximation) the factor k is 0.273/0.275

for sheet thickness 1-3mm and rolling processing (so "foot" with very wide rays) the k factor is 0.8

we directly pass the dxf of developments (so no detailed quota: only the maximum size, bending and indication of threads, rigging or other).
And we don't have any big trouble in the end.

for all thicknesses above 3mm instead the k factor always remains the usual above, but we also provide the full quotation with the placement odds of holes and other processing.
the carpenters think about adjusting developments at the time of cutting.

by default the calculators to fk 0.5, as I would do in the raltaà, of the rest.

 

[ceschi1959]

Okay, thank you.
the k is set to attempts, as I imagined.
I wanted to know if there was a formula or a guideline for setting this value.

the factor k is not set for attempts but is obtained from experimental data as I try to explain in the annexed pdf.

 

[xxfast]

the factor k is not set for attempts but is obtained from experimental data as I try to explain in the annexed pdf.

:finger:
Thank you very much.

 

[CIARLY]

the factor k is not set for attempts but is obtained from experimental data as I try to explain in the annexed pdf.

agree but since it changes according to material, equipment, with thickness .... you have to make some attempts and create your tables as rightly did mike, maxopus, radio ....

then as mentioned above at the end it is bent pieces, which if it is okay are measured with the meter, you can not claim tolerances of +- 1 tenth.
however depends so much on the brush up to 2-3 mmt. it is reasoned over the bandages increase fortunately it does not touch me.

Unfortunately there is no unique formula :biggrin:

 

[sampom]

by default the calculators to fk 0.5, as I would do in the raltaà, of the rest.

:biggrin: As the old carpenters have always done.

the factor k does not set for attempts ma si ricava da experimental data as I try to explain in the attached pdf.

look that you are saying the same things of all; in this case for attempts è sinonimo di experimental data.
go to the workshop, do "tentatives" (proves, experiments) of fold to get the "experimental data" to be brought back to the cad system.

greetings
Marco:smile:

 

[Mike1967]

the factor k is not set for attempts but is obtained from experimental data as I try to explain in the annexed pdf.

... and yes, the theor... The theory... If it were as you say it would be a perfect world.
from your pdf you notice (who bended a few linear km of plates immediately notices) that the fold radius is regular, tangent on the two sides... but in reality it is not exactly like this is a hyperbole, therefore the maximum of diametric irregularities.
I don't know your experience and I don't doubt it, but I speak for myself and my experience, I think that 24 years in the field give me the chance to affirm a proven theory on the field.
variables that sink the "theory" are infinite, fiber sense, non-regular thickness of materials, temperatures and equipment used.
in fact the punches for the fold can have very variable angles and connection rays, if I bend with a mold with radius 0.4 or 0.8 or 1.2, the withdrawal changes.
even the penetration of the punch in the material (look carefully the inside of a fold, you will find a small "solco" that will be deeper with the decrease of the hardness of the material) has a primary role.
we have carried out those tests with specific types of punch/matrix.
the table is the simplified standard (series of matrice punches we usually use, the accurate one besides identifying the type of quarry, also indicates the punch used).
fold in the air... fold in line... turn radius... vabbè, the speech is long and since in mathematics I am not a genius I have leaned on the eperience rather than to calculations with 5-10 decimals after the comma, I certainly have mistaken, but for 12 years I use swx entrusting me to that table that, among other things is never complete... in fact new processing or need to use moulds, perhaps self-constructed, force me to update it with always new data that adapt to new needs.

I am yours 3 mm lam (iron) with 50x50 side cutting to 94,6 (r3 and fk 0.4) and once folded measures 50,0 x 50,0... with a tolerance under the tenth of mm per side.
with my molds I have a pick-up from 0.6 mm to fold.

if it were in ac inox 304 cutting to 93.7 (r3 and fk to 0.21).
with my molds I have a retreat negative from 0.3 mm to fold.

I could post the data for aluminum, but maybe you can post the formula that after we compare with the actual value that I would use in reality.
purtoppo this is a trite and retrite theme, cyclically reproposes and every time to make understand the reasons of a difference between theory and practice is never easy.
I hope you understand the tone of my post that does not want to be the bible of the folder or the manual of the good caddist...:finger:
to live I arrange to find developments to tons of plates that others "will distort"...:biggrin:




Hi:

 

[sampom]

...as I try to explain in the attached pdf.

we know well what kf is (it is however useful to remember it..), and more simply it is that factor that multiplied by the thickness gives you the position of the "neutral line" regarding the inner face of the fold.
Unfortunately it is very variable (as correctly explained by mike), exaggerating almost exclusively for every single piece (and sometimes piego). so if you want to do the very precise (at the practical "in machine", not on paper) you can not always and only lead to the result of a mathematical formula. "provines" are mandatory; based on these and considering all variables, then draw the bending tables. certainly these are "infinite" and constantly evolving, however they are all data that you remain for the future.

Moreover, to quote examples of folds that have a real meaning, it is necessary to specify the equipment used (as well as the material).
we do a little bit of everything (in the air), but only with standard equipment (obviously within 90° or less) consisting of simple matrix to x 60x60 to 4 quarries of 85°, 16 22 35 and 50 mm; knife/punzone of 60° r=0.8
for aisi304 (practically we only work that) that 50x50 sp. 3 would give me a development of 94 mm to bend it in quarry 2 and 92.8 in quarry 3. obviously changes the radius, r4 in the first case and r6 in the second.
the rays (as it always says very correct mike) are "appearing", but I consider the external one that instead is a fairly regular arc and subtracting the thickness I echo the inside (I need to have the curved profile as much as possible, even on the drawing).

so see on the same piece (dimensionally speaking) how many differences can there be? ..all detectable "for attempts" in "experimental mode".

greetings
Marco:smile:

 

[xxfast]

I knew if I took out this argument, it was a mess. :3553:
However you understood... you want experience in qiesto field.

 

[Mike1967]

I knew if I took out this argument, it was a mess. :3553:
However you understood... you want experience in qiesto field.

But I think that these discussions are very constructive.
contributes to deepening a theme, that of the sheet, which is really
ostic and variable bringing professional experiences as well as theoretical. :finger:

 

[giorgioff]

I also quote in full the speech of the mike
(cut) do the tests with the equipment that the operator (because then it's he who counts:mixed usually uses to fold the required thickness and sets the k for every sheet thickness you will use.
Now I speak without ever seeing the sw settings, we just bought it and it's not yet arrived, but with solid-edge I had made templates for every thickness and material with set rays, k, weight, info for rendering etc. so as not to insert the data every time.

you have to arrange....:frown:

 

[derrik]

good morning to all .some could send me a table to insert in sw2011 with factors k? so far I have done everything to attempts, but they are adding too many mistakes.I tried to download those found on the forum but I am not with the developments.thanks to the possible help derrik