Hi, if u are an artificier armored, with ur arcane armor, infuses etc. And u find a magic piece of armor,  u have the properties that let say the gaunlets already have + all ur staff? Let say u find a gauntlet that provides u with fire resistance, y can add to it be an arcane armore piece and ad an infuse to the piece, like being simple magic weapon? 

Not quite following you so I'm going to try and break this down to answer your questions: 

if u are an artificier armored, with ur arcane armor, infuses etc. And u find a magic piece of armor,  u have the properties that let say the gaunlets already have + all ur staff?

Artificers can create a suite of magical armor, individual pieces of this armor: Helment, gauntlets, etc. count as the whole of the armor but still have individual requirements for attunement. 

Let say u find a gauntlet that provides u with fire resistance, y can add to it be an arcane armore piece and ad an infuse to the piece, like being simple magic weapon? 

Infusions can not be added to magic weapons, an artificers infusion turns a Mundane item into a magical item,  

Does that answer you questions?

Srry, but gauntlets are not weapons, msybe im using the wrong word. If i find a fire resistance chest, i can mane it an arcane armor and infuse it? 

I think the whole point is, if in the campaing u find a magic armor piece, armored artificier can use it whithout losing thei class benefits? 

yes, Your arcane armor can be a mundane or magical armor

Thx a lot. I wish to give u all likes, but from my movilphone i dont find a way to do it.