Method for treating the surface of metal workpieces with compressive and tensile stresses

Abstract

Disclosed is a method for surface treatment of workpieces of aluminum and/or alloyed aluminum in which the workpiece ( 12, 12′, 12″ ) is worked at least in part by at least one roll ( 16, 16′, 16′″, 74′, 74″, 86′, 86 ″) provided at least in part with an outer profile ( 22, 22′, 76, 76′, 78, 78′ ) having the form of annular beads and recesses, the method including the steps of exposing the treated surface ( 14, 14′, 14″ ) of the workpiece to compressive stresses and exposing zones located beneath said treated surface of the workpiece to tensile stresses axially and tangentially through contact with the annular beads.

1 . A method for surface treatment of workpieces of aluminum, alloyed aluminum, or a combination thereof in which a workpiece ( 12 ,  12 ′,  12 ″) is worked at least in part by at least one roll ( 16 ,  16 ′,  16 ″,  74 ′,  74 ″,  86 ′,  86 ″) provided at least in part with an outer profile ( 22 ,  22 ′,  76 ,  76 ′,  78 ,  78 ′) having the form of annular beads and recesses, comprising the steps of: increasing the strength and hardness of the workpiece by exposing the surface ( 14 ,  14 ′,  14 ″) of the workpiece ( 12 ,  12 ′,  12 ″) to compressive and tensile stresses; and exposing zones located beneath said treated surface ( 14 ,  14 ′,  14 ″) of said workpiece ( 12 ,  12 ′,  12 ″) to tensile stresses axially and tangentially through contact with said annular beads; wherein said workpiece is worked by said at least one roll in sequence in opposite directions.  
   
   
       2 . The method as set forth in  claim 1 , wherein said workpiece ( 12 ,  12 ′,  12 ″) is moved in an axial direction by said at least one roll ( 16 ,  16 ′,  16 ″′,  74 ′,  74 ″,  86 ′,  86 ″ ) provided with said annular beads.  
   
   
       3 . The method as set forth in  claim 1 , wherein said workpiece ( 12 ) has a round treated surface ( 14 ) and is worked by at least one roll ( 16 ,  16 ′,  16 ″′) provided at least in part with an outer profile ( 22 ,  22 ′) arranged parallel to said workpiece ( 12 ) and which is rotatable about the longitudinal centerline ( 18 ,  18 ′,  18 ″′) thereof as well as about said workpiece ( 12 ).  
   
   
       4 . The method as set forth in  claim 1 , wherein said workpiece ( 12 ″) has a treated surface that includes at least one bore ( 14 ″) and is worked by at least one roll ( 16 ,  16 ′,  16 ″′,  74 ′,  74 ″,  86 ′,  86 ″) provided at least in part with an outer profile ( 22 ,  22 ′) arranged parallel to said at least one bore ( 14 ″) and which is rotatable about said longitudinal centerline ( 18 ,  18 ″) as well as about said at least one bore ( 14 ″).  
   
   
       5 . The method as set forth in  claim 3 , wherein said workpiece ( 12 ,  12 ″) is worked by a roll ( 16 ,  16 ′,  16 ″′) provided at least in part with an outer profile ( 22 ,  22 ′) and at least two, substantially non-profiled rolls ( 16 ″) that are arranged on the outside of said workpiece ( 12 ) or within at least one bore ( 14 ″) in said workpiece.  
   
   
       6 . The method as set forth in  claim 5 , wherein said workpiece ( 12 ,  12 ) or said at least one bore is worked by a roll ( 16 ′″) having an outer profile ( 22 ,  22 ′) in the form of annular beads ( 24 ) and recesses arranged at a first angle and a second angle to said longitudinal centerline ( 18 ,  18 ′,  18 ′′′) of said roll ( 16 ,  16 ′,  16 ′′′,  74 ′,  74 ″,  86 ′,  86 ″), wherein either the first angle is positive and the second angle is negative or the first angle is negative and the second angle is positive.  
   
   
       7 . The method as set forth in  claim 3 , wherein said workpiece ( 12 ,  12 ″) is worked by two rolls ( 16 ,  16 ′) each provided at least in part with an outer profile ( 22 ,  22 ′) and a substantially non-profiled roll ( 16 ″ ) that is arranged on the outside of said workpiece ( 12 ) or within at least one bore ( 14 ″) in said workpiece.  
   
   
       8 . The method as set forth in  claim 7 , wherein said workpiece ( 12 ,  12 ″) or said at least one bore is worked by two rolls ( 16 ,  16 ′) having an outer profile ( 22 ,  22 ″) in the form of annular beads ( 24 ) and recesses ( 26 ) arranged at an angle (α, α′) to said longitudinal centerlines ( 18 ,  18 ′) of said rolls ( 16 ,  16 ′).  
   
   
       9 . The method as set forth in  claim 8 , wherein said two rolls ( 16 ,  16 ′) are powered in the same direction of rotation when said annular beads ( 24 ) and recesses ( 26 ) are arranged at a first angle and a second angle to said longitudinal centerlines ( 18 ,  18 ′) of said two rolls ( 16 ,  16 ′), wherein either the first angle is positive and the second angle is negative or the first angle is negative and the second angle is positive.  
   
   
       10 . The method as set forth in  claim 8 , wherein said two rolls ( 16 ,  16 ′) are powered in the opposite direction of rotation when said annular beads ( 24 ) and recesses ( 26 ) are arranged at a first angle and a second angle to said longitudinal centerlines ( 18 ,  18 ′) of said two rolls ( 16 ,  16 ′), wherein the first angle and the second angle are either both positive or both negative.  
   
   
       11 . The method as set forth in  claim 1 , wherein the treated surface of said workpiece ( 12 ′) includes at least one flat surface ( 14 ′) and is worked by at least one roll ( 74 ′,  74 ″,  86 ′,  86 ″) provided at least in part with an outer profile ( 76 ,  76 ′,  78 ,  78 ′) arranged substantially perpendicular or at an angle β to said workpiece ( 12 ′) and rotatable about the longitudinal centerline ( 80 ) thereof.  
   
   
       12 . The method as set forth in  claim 11 , wherein said workpiece ( 12 ′) is worked by at least one roll ( 74 ′,  74 ″) provided at least in part with an outer profile ( 76 ,  76 ′,  78 ,  78 ′) and is worked or supported by at least one further roll ( 86 ′,  86 ″) provided at least in part with an outer profile ( 76 ,  76 ′,  78 ,  78 ′) or a non-profiled roll ( 86 ,  86 ″′) or similar supporting means located spaced away and opposite said at least one roll ( 74 ′,  74 ″).  
   
   
       13 . The method as set forth in  claim 12 , wherein said at least one flat surface ( 14 ′) to be treated of said workpiece ( 12 ′) is worked by said at least one roll ( 74 ′,  74 ″,  86 ′,  86 ″) including an outer profile ( 76 ,  76 ′,  78 ,  78 ′) in the form of annular beads ( 24 ) and recesses ( 26 ).  
   
   
       14 . The method as set forth in  claim 13 , wherein said at least one flat surface ( 14 ′) of said workpiece ( 12 ′) to be treated is worked by several rolls ( 74 ′,  74 ″,  86 ′,  86 ″) having an outer profile ( 76 ,  76 ′,  78 ,  78 ′) in the form of annular beads ( 94 ) and recesses ( 96 ), whereby said annular beads ( 94 ) and recesses ( 96 ) of adjoining rolls ( 74 ′,  74 ″,  86 ′,  86 ″) differ from each other in their configuration and arrangement or each of said adjoining rolls ( 74 ′,  74 ″,  86 ′,  86 ″) is powered in a different direction of rotation.  
   
   
       15 . The method as set forth in  claim 13 , wherein said at least one flat surface ( 14 ′) of said workpiece ( 12 ′) to be treated is worked by rolls ( 74 ″,  86 ″) having an outer profile ( 78 ,  78 ′) in the form of annular beads ( 24 ) and recesses ( 26 ) arranged at an angle (α, α′) to said longitudinal centerlines ( 80 ) of said rolls ( 74 ″,  86 ″), whereby said rolls ( 74 ″,  86 ″) are powered in the same direction of rotation for a substantially opposite lead position of said beads ( 24 ) and recesses ( 26 ) or in the opposite direction of rotation for a substantially same lead position of said beads ( 24 ) and recesses ( 26 ).  
   
   
       16 . The method as set forth in  claim 14 , wherein said at least one flat surface ( 14 ′) of said workpiece ( 12 ′) to be treated is worked by rolls ( 74 ′,  86 ′) having an outer profile ( 76 ,  76 ′) in the form of annular beads ( 94 ) and recesses ( 96 ) arranged perpendicular to their longitudinal centerlines ( 80 ), said rolls being axially staggered relative to each other.  
   
   
       17 . The method as set forth in  claim 1 , wherein said workpiece ( 12 ,  12 ′,  12 ″) or said treated surface ( 14 ,  14 ′,  14 ″) is coated with a covering of metal, a metal alloy, a paint, plastics, is anodized, galvanized or pickled.  
   
   
       18 . A method as set forth in  claim 1 , for surface treatment of workpieces ( 12 ,  12 ′,  12 ″) of base metals such as aluminum, lead, chromium, iron, cobalt, nickel, copper, manganese, molybdenum, silicon, tungsten, tin, zinc or alloys thereof including brass, steel, aluminum or alloyed aluminum including AlMg 4.5 Mn, AlMgSi 0.5 , AlMgSi, AlMg 5 , AlZn 4.5 Mg, AlCuMg, AlCuMg 2 , AlZnMgCu 0.5 , AlZnMgCu 1.5 , AlCuMgPb or of noble metals including gold, palladium, platinum, silver or alloys thereof, or of combinations of base and noble metals.  
   
   
       19 . The method as set forth in  claim 1 , for producing elongated sections ( 12 ,  12 ′) of solid metal, selected from wires, rods and strip or tubular material for headrest brackets in automobiles.  
   
   
       20 . The method as set forth in  claim 1 , for producing coiled, or hardened or coated workpieces for coiled springs.  21 . The method as set forth in  claim 1 , wherein the surface of the workpiece that is treated is an interior surface of a bore, a through-hole or a blind hole in an automotive engine.  22 . The method as set forth in  claim 1 , for producing elongated sections ( 12 ′) of solid metal including at least one flat surface ( 14 ′) for headrest brackets in automobiles.  23 . The method as set forth in  claim 1 , wherein said metal includes base metals selected from aluminum, lead, chromium, iron, cobalt, nickel, copper, manganese, molybdenum, silicon, tungsten, tin, zinc or alloys thereof including brass, steel, aluminum or alloyed aluminum selected from AlMg 4.5 Mn, AlMgSi 0.5 , AlMgSi, AlMg 5 , AlZn 4.5 Mg, AlCuMg, AlCuMg 2 , AlZnMgCu 0.5 , AlZnMgCu 1.5 , AlCuMgPb or of noble metals selected from gold, palladium, platinum, silver or alloys thereof, or of combinations of base and noble metals.  24 . The method as set forth in  claim 1 , wherein the workpiece is worked by two rolls.  25 . The method according to  claim 1 , wherein the workpieces are aluminum or alloyed aluminum.