Method for treating surfaces of hollow parts, tank for carrying out a method of this type, installation for continuously treating surfaces comprising such a tank

Abstract

The invention relates to a method for treating surfaces of hollow parts, this method being a conversion treatment such as an anodizing, and to a method according to which the hollow pieces are completely immersed inside at least one treatment tank containing a liquid, characterized in that each hollow piece is immersed while making it execute at least one rotational movement so that air bubbles likely to be created inside the tank are removed from the inner wall of the hollow part.

1 . A process for a surface treatment of parts, in which process the parts are immersed in at least one treatment liquid contained in a treatment tank, wherein said parts are fixed on a rotating structure, rotatably mounted inside said treatment tank, wherein said parts are completely immersed in said treatment liquid by means of a rotational movement of said rotating structure, said rotational movement being chosen so that air bubbles liable to be created by the immersion of said parts are expelled from the surfaces of said parts. 
     
     
         2 . The process as claimed in  claim 1 , wherein each part is made to undergo at least one rotational movement of at least 90. 
     
     
         3 . The process as claimed in  claim 1 , wherein each part is made to undergo one or several rotational movements of 360. 
     
     
         4 . The process as claimed in  claim 1 , wherein a predetermined number of said parts are placed beforehand on a support which includes at least one retaining member capable of immobilizing each of said parts relatively to said support, wherein said support for the parts is introduced into an immersion zone located in the upper portion of said treatment tank and fastened to said rotating structure by fastening means, wherein said support for the parts is carried along said rotational movement by said rotating structure and carried to an exit zone located in the upper portion of said treatment tank where the said support for the parts is removed from said treatment tank. 
     
     
         5 . The process as claimed in  claim 4 , wherein said support for the parts is positioned by conveying means at the same height as and in front of said immersion zone and introduced by thrust means, along an horizontal path, into said immersion zone and wherein the support for the treated parts is removed by extracting means along an horizontal extraction path from said exit zone onto a conveying means placed at the same height as the exit zone. 
     
     
         6 . The process as claimed in  claim 4 , wherein said process is continuous and wherein the following various steps are carried out:
 positioning a plurality of supports for the parts on a first conveyor chain placed at the same height as said immersion zone,   conveying said supports for the parts and delivering them, by means of a horizontal thrust, from the first conveyor chain into the immersion zone,   successively immersing and rotating said supports for the parts in the treatment liquid contained in said treatment tank,   removing the supports for the treated parts successively, by horizontal extraction from said exit zone onto a second conveyor chain placed at the same height as the exit zone.   
     
     
         7 . The process as claimed in  claim 4 , wherein the supports for the parts are immersed in the treatment tank while making them follow a helical path between the immersion zone and the exit zone of said treatment tank. 
     
     
         8 . The process as claimed in  claim 6 , wherein a said support is introduced into the tank so that it pushes at least one other support ( 2   x ) immersed and rotated beforehand in said tank, so as to discharge at least one other support ( 2   x ) onto the second conveyor chain. 
     
     
         9 . The process as claimed in  claim 5 , wherein at least a second complementary treatment tank containing a complementary treatment liquid, having also an immersion zone at the same height as the second conveyor chain, is used, and wherein the parts removed from a first treatment tank are delivered by means of horizontal thrust from the second conveyor chain into the immersion zone of the second complementary treatment tank. 
     
     
         10 . The process as claimed in  claim 9 , wherein the parts treated in said second complementary treatment tank are discharged by horizontal extraction from an exit zone of said complementary treatment tank onto said first conveyor chain conveying in the same direction (SC) as in the case of the delivery of the parts into the preceding treatment tank. 
     
     
         11 . The process as claimed in  claim 10 , wherein at least one rinsing step is carried out by spraying water onto at least one of the two conveyor chains. 
     
     
         12 . The process as claimed in  claim 1  for a surface treatment of hollow parts. 
     
     
         13 . The process as claimed in  claims 1  for an electrochemical surface treatment of metallic parts. 
     
     
         14 . The process as claimed in  claim 1  for an anodizing treatment of parts made of aluminum or an aluminum based alloy. 
     
     
         15 . The process as claimed in  claim 14 , comprising the immersion of the parts in five different active liquid solutions (LS, LB, LN, LO, LC) in successive steps so as to anodize said parts. 
     
     
         16 . A device for implementing a surface treatment process as claimed in  claim 1 , wherein at least one treatment tank configured to contain a treatment solution, a first conveyor chain, placed at the same height as an immersion zone (IZ) of the tank and configured to deliver each support for a plurality of hollow parts into said immersion zone, thrust means for horizontally thrusting each support for the hollow parts from the first conveyor chain into the immersion zone of the tank, extraction means for horizontally extracting each support for the treated parts from an exit zone (EZ) of the tank and delivering it to a second chain, placed at the same height as the exit zone of the tank and configured to move each support for the treated parts away from the tank. 
     
     
         17 . A device for implementing a surface treatment process as claimed in  claim 16 , wherein the thrust means comprises at least one hydraulic cylinder. 
     
     
         18 . A device for implementing a surface treatment process as claimed in  claim 1 , in which the parts are immersed in at least one treatment liquid contained in a treatment tank, wherein said parts are fixed on a rotating structure, rotatably mounted inside said treatment tank, wherein said parts are completely immersed in said treatment liquid by means of a rotational movement of said rotating structure, said rotational movement being chosen so that air bubbles liable to be created by the immersion of said parts are expelled from the surfaces of said parts,
 wherein said treatment tank includes a drum, mounted so as to rotate inside said treatment tank, said drum comprising, on its external periphery, at least one housing track configured to house and fasten a support for one or more parts, wherein the support is fastened by fastening means.   
     
     
         19 . A device for implementing a surface treatment process as claimed in  claim 18 , comprising at the tank's uppermost portion an opening, defining an immersion zone and an exit zone. 
     
     
         20 . A device for implementing a surface treatment process as claimed in  claim 1 , in which the parts are immersed in at least one treatment liquid contained in a treatment tank, wherein said parts are fixed on a rotating structure, rotatably mounted inside said treatment tank, wherein said parts are completely immersed in said treatment liquid by means of a rotational movement of said rotating structure, said rotational movement being chosen so that air bubbles liable to be created by the immersion of said parts are expelled from the surfaces of said parts,
 wherein said installation comprises at least one treatment tank, a first conveyor chain, placed at the same height as an immersion zone of said treatment tank and configured to deliver supports for the parts in front of said immersion zone, thrust means for horizontally thrusting each support for the parts from the first conveyor chain into the immersion zone of said treatment tank, extraction means for horizontally extracting each support for the treated parts from an exit zone of said treatment tank and delivering it to a second chain, placed at the same height as said exit zone of the said treatment tank and configured to move each support for the treated parts away from the treatment tank.