tolerance on welded sheets

[Teo-77]

Bye to all,
I have a 6m square on the side made by 4 matching plates measuring 1500x6000 thickness 3 mm aisi 304. The plates are combined longitudinally by welding bench. for the whole side I applied a tolerance ± 1/2 it 13, ~1,6 mm every 1000 therefore ± 5 mm. while for the welded side I considered the lamination tolerance - 0.25 + 0.5 of the 1500 format, obtained a long time ago from a mill catalog, thus obtaining a tolerance of -1 + 2 (summatory of the tolerances of the 4 plates). I wanted to know that to give the welds to be added in turn to that of the plates in order to obtain the tolerance on the welded side. I initially thought the usual ± 1/2 it 13 on both sides, then I considered that the 4 sheets from 1500 can become also 6 from 1000, everything depends on what is purchased. Thank you very much in advance

 

[meccanicamg]

I would say that you have to give tolerances according to what you need then this big frame. Lamination tolerances are usually wide to allow trade of non-quality material.
I don't think the 3 mm stainless steel sheet is just rolled. who provides you with the sheet will certainly have a finishing line that makes sanding and detaining the fibers and maybe it is also a line of threading and then the 1500 gives you +|- 0.5 mm even if the tolerance of the cesoia rifilabordibé of about half the tolerance compared to what I indicated you.
regarding the length, I would say that if the plant is equipped with rotating shears or unfortunately flying shears, using a good encoder on the measuring wheel you can have on 6000mm +- 2mm because normally the 5 mm are given on 12000mm.
If the things you've written are true you're buying poor material, cut on an unsuitable line, and maybe by a trick....or you're inventing numbers because you've never required certificates to the metal cutting service centers.

 

[meccanicamg]

As for the automatic or manual welding process that is, you should know that the plates to be joined should according to the various norms of cyanphrine or preparation of lembi, have a distance between zero and the thickness of the sheet, then 3 mm. At this point you have to take strips not from 1500mm....according to me you better deepen the process of manufacture and production sheet strips, then you can decide what to do.
but then what changes to you if it is bigger or smaller? What function does it have? explains....then we see if it is right or if you can then intervene on the components to be mounted inside.

 

[Teo-77]

ciao "Mechanical",
Thank you very much for your kind answer. as soon as possible I will write more exhaustively the situation. As regards the suggestion of deepening the lamination process, I fully agree with the fact that, if you point out, it means that there is a shortage. hi and good work

 

[Teo-77]

Hi.
below I turn the comments to the previous post:

- the 6000x6000 sheet is a true measure and serves to produce a virola of a cistern. After performing the intermediate joints, a calculator is made and a last longitudinal union, thus obtaining a hollow cylinder where the respective bombed funds are soldered.
- the displacement is perpendicular to the welding
- the dimensions of the plates are the result of the diameter-length duet but not represented a constant as, both the diameter, and the length can vary and also of much, conditioning the shape (quadrato-retangle) and the size of the handkerchief.
- the number of sheets and sizes are a consequence of the previous point and depend on what is purchased and can happen to take also second choice sheets.
- tolerance - 0.25 + 0.5 of 1500 format has been recovered from an internet catalog and is applied to width and not to length. could be that this is the production standard only of that specific company and that it does not represent a unified standard. generally in order to make a reasoning that is concrete, I need to have some starting points. If, at a later date, more knowledge and/or experience, these points prove to be incorrect, they can still be changed by developing new conclusions.
- against this last statement. ... excellent tip to check the certificates....I will see what I can recover.
- if the mill provides on the 6000 mm tolerances on the length of ± 2mm against the ± 5 mm indicated by me..... better I will have a greater precision but on the length I have no particular requirements was only to have an order of magnitude. It would have been worse a reverse condition, with my closer tolerance and a wider tolerance of the supplier. when a supply finds very demanding tolerances compared to its standards, it tends to have 3 behaviors: I don't do the job, I do as I can or, I do as you want, but don't complain about the price. all three conditions are in my opinion to avoid.

This long premise, we come to the core of the matter. The objective I would like to achieve is to create a table that is able to generate enough truthful tolerance on the inner diameter of the virola whatever it is, taking into account the actual composition of the sheets. to do this I need to understand how his development behaves. being this result of 2 variables, the width of the sheet and the welding cord I necessarily need to attribute a numerical value to both. if the first unknown I can use the questionable tollenza - 0.25 + 0.5 previously mentioned, what is the value to attribute to the second? I have speculated that each welding cord can generate an approximate tolerance of ± 1 mm. this value is the result of the following reasoning:

- if I have a gap between the plates, the weld tends to pull to fill the distance producing a shortening (negative cost)
- if the gap between the sheets is worth zero, the welding will tend to remove the plates as I add the material (positive cost)
- 1 mm I think it is an appropriate value to the context

I still asked the boys about the production to measure the welded handkerchief before the displacement in order to have real data. with a dozen values on different compositions you could get an empirical indication.

I hope I have been clear and precise in the dictates. Thank you/I await your considerations.
Good job

 

[meccanicamg]

to determine the tolerance on the width of the material strips you should make an offer request to the service centers asking you to supply the manufacturing tolerance. Surely they will give you different values. try to ask gavinox, lsi, csi etc. you will see that they will not give you the same values. Then you do a search for second-order service centers and tell me what they give you... other than second-choice....can the third.

for welding I would say that if you need to leave blank equal to the thickness to carry out full penetration welding without inclusion of slags and blows, you will have to leave 3 mm that will be at least 0 if you move the sheet one against the other to a maximum of 4mm if you do control with a caliber or dima before welding ... to be good. It is also true that you can adjust the game between two side plates to recover the width tolerance error of the strips...and then reduce the total error on total development.

I repeat: Depending on suppliers you can get a total tolerance value of zero. depends mainly on how the welder adjusts the edges

 

[Teo-77]

thanks for the answer,
As soon as the workshop gives me a fairly considerable number of reliefs I will publish a table with n° formats, theoretical development and real development so that everyone can make considerations about it.
Hi.