Mechanical component and method of surface hardening

Abstract

Mechanical component ( 10 ) having a hole ( 12 ) extending therethrough and having a minimum thickness (T) of 7 mm, measured from an interior surface ( 12 a, 12 b ) constituting the outer perimeter of the hole ( 12 ) radially outwards to an outer surface of said mechanical component ( 10 ). The maximum transverse dimension (d) of said hole ( 12 ) is 31.75 mm or less and that at least one part ( 22 ) of interior surface ( 12 a, 12 b ) material of the mechanical component ( 10 ) constituting the outer perimeter of said hole ( 12 ) comprises a martensitic microstructure produced by induction hardening using an electromagnetic induction coil ( 14 ) positioned inside said hole ( 12 ) followed by immediate quenching using a quenching device ( 16 ) that is positioned inside said hole ( 12 ) when the electromagnetic induction coil ( 14 ) has been removed from said hole ( 12 ) or while the electromagnetic induction coil ( 14 ) is being removed from said hole ( 12 ).

1 . A mechanical component comprising
 a cylindrically shaped body having a hole extending therethrough and having a minimum thickness of 7 mm, measured from an interior surface constituting the outer perimeter of the hole radially outwards to an outer surface of said cylindrically shaped body,   of said hole is having a maximum transverse dimension of 31.75 mm or less, and   at least one part of interior surface material of the cylindrically shaped body constituting the outer perimeter of said hole comprises a martensitic microstructure produced by induction hardening using an electromagnetic induction coil positioned inside said hole followed by immediate quenching using a quenching device that is positioned inside said hole when one of:   a) the electromagnetic induction coil has been removed from said hole, or   b) while the electromagnetic induction coil is being removed from said hole.   
     
     
         2 . The mechanical component according to  claim 1 , wherein said at least one part of the interior surface extends to a depth that is of one of 0.2, 0.3, 0.4, 0.5, 0.75, 1.0 mm below said interior surface. 
     
     
         3 . The mechanical component according to  claim 1 , wherein the maximum transverse dimension of the hole is between 5 and 31.75 mm. 
     
     
         4 . The mechanical component according to  claim 1  wherein the minimum thickness of the mechanical component measured from said interior surface radially outwards towards the outer surface of said mechanical component is one of 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, and greater than 100 mm. 
     
     
         5 . The mechanical component according to  claim 1 , wherein at least one part of said interior surface constituting the outer perimeter of the hole comprises a thread. 
     
     
         6 . The mechanical component according to  claim 1 , said mechanical component is formed into a rotationally symmetrical mechanical component. 
     
     
         7 . The mechanical component according to  claim 1 , said mechanical component is formed into one of a roller and a component for an application in which is subjected to alternating Hertzian stresses, including at least one of a rolling contact and a sliding contact. 
     
     
         8 . A method for surface hardening at least one part of an interior surface of a mechanical component having a hole maximum transverse dimension of 31.75 mm or less extending therethrough, whereby the mechanical component has a minimum thickness of 7 mm, measured from an interior surface constituting the outer perimeter of the hole radially outwards to an outer surface of said mechanical component, the method comprises the steps of:
 inserting an electromagnetic induction coil within said hole,   heating said at least one part of the interior surface to at least the ferrite/austenite transformation temperature by induction heating,   removing said electromagnetic induction coil from said hole and   one of simultaneously and subsequently inserting a quenching device within said hole to immediately quench said at least one part of the interior surface.   
     
     
         9 . The method according to  claim 8 , further comprising steps of:
 removing said electromagnetic induction coil from said hole via the same end of the said hole, and   inserting said quenching device from the other end of said hole.   
     
     
         10 . The method according to  claim 8 , further comprising a step of also providing at least one external quenching device on the outside of said mechanical component to immediately quench said at least one part of the interior surface. 
     
     
         11 . The method according to  claim 8 , wherein the step of heating said at least one part of the interior surface is further limited to heating said at least one part of said interior surface to a depth of one of 0.2, 0.3, 0.4, 0.5, 0.75, and 1.0 mm below said interior surface. 
     
     
         12 . The method according to  claim 8 , wherein the maximum transverse dimension of the hole is between 5 and 31.75 mm. 
     
     
         13 . The method according to  claim 8 , wherein the minimum thickness of the mechanical component measured from said interior surface radially outwards towards the outer surface of said mechanical component is one of 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, and greater than 100 mm. 
     
     
         14 . The method according to  claim 8 , wherein at least one part of said interior surface constituting the outer perimeter of the hole comprises a thread. 
     
     
         15 . The method according to  claim 8 , further comprising a step of forming said mechanical component constitutes into a rotationally symmetrical mechanical component. 
     
     
         16 . The method according to  claim 8 , further comprising a step of forming said mechanical component into one of a roller and a component for an application in which is subjected to alternating Hertzian stresses, including at least one of a rolling contact and a sliding contact. 
     
     
         17 . The mechanical component according to  claim 1 , wherein the maximum transverse dimension of the hole is between 10 and 30 mm. 
     
     
         18 . The method according to  claim 8 , wherein the maximum transverse dimension of the hole is between 10 and 30 mm.