Inductive heating for hardening of gear teeth and components alike

Abstract

An apparatus ( 1 ) for heat treating the surfaces ( 32 b ) of gear teeth ( 32 a ) via magnetic inductive heating comprises a magnet assembly ( 40 ) and a workpiece (or gear) holder ( 30 ) operatively mounted on a base ( 12 ). The magnet assembly ( 40 ) is rotatable in a first plane about a first axis (A 1 ), and the work-piece holder ( 30 ) (on which a gear ( 32 ) can be removably mounted) is rotatable about a second axis (A 2 ) in a second plane. The first and second axes (A 1 , A 2 ) are spaced apart from each other and the first and second planes intersect each other. The apparatus ( 10 ) includes a mechanism ( 16, 22 ) to move one (or both) of the magnet assembly ( 40 ) and the workpiece holder ( 30 ) relative to each other, such that the magnet assembly ( 40 ) and work piece holder ( 30 ) can be moved between a position in which the magnet assembly ( 40 ) and the gear ( 32 ) mounted on the work-piece holder ( 30 ) are in heating proximity to each other and a second position in which the magnet assembly ( 40 ) and gear ( 32 ) are out of heating proximity with each other.

1 . An apparatus ( 10 ) for heat treatment of gear teeth ( 32   a ) via magnetic inductive heating; the apparatus comprising:
 a magnet assembly ( 40 ); said magnet assembly comprising a disk ( 44 ) having a plurality of permanent magnets ( 58 ) or groups of magnets positioned around a circumference of said disk; said magnets or groups of magnets having opposed outer faces ( 58   a,b ) defining north and south poles of said magnets or group of magnets; said magnets or groups of magnets being arranged about said disk such that the poles alternate; said magnet assembly ( 40 ) being concentric with and rotatable about a first axis (A 1 ); said magnet assembly being rotatable in a first plane;   a spindle drive ( 22 ) operatively connected to said magnet assembly ( 40 ) to rotate said magnet assembly about said first axis (A 1 ) in said first plane;   a work-piece holder ( 30 ) adapted to removably hold a gear ( 32 ) having tooth surfaces ( 32   b ) to be heat treated; said work-piece holder being concentric with, and rotatable about, a second axis (A 2 ); said first axis (A 1 ) being spaced from said second axis (A 2 );   a work-piece drive operatively connected to said work-piece holder to rotate said work-piece about said second axis in said second plane; and   means ( 16 ,  22 ) for moving one or both said magnet assembly ( 40 ) and work-piece holder ( 30 ) relative to each other to bring said magnet assembly and gear tooth surfaces into heating proximity with each other; such that rotation of said magnet assembly induces heating of said gear tooth surfaces.   
     
     
         2 . The apparatus of  claim 1  wherein said work-piece holder ( 30 ) is rotatable in a second plane; said second plane intersecting said first plane. 
     
     
         3 . The apparatus of  claim 1  comprising a base ( 12 ); said means ( 16 ,  22 ) for moving comprising a slide block ( 16 ) movable along said base parallel to said first axis (A 1 ) and a spindle block ( 22 ) movable relative to said slide block parallel to said second axis (A 2 ); said magnet assembly ( 40 ) being rotatably mounted to said spindle block ( 22 ). 
     
     
         4 . The apparatus of  claim 1  wherein said magnet assembly disk ( 44 ) comprises an inner portion ( 46 ) and a cage ( 48 ) extending radially from a radial outer surface of the inner portion;
 said inner portion ( 46 ) having front and back surfaces ( 50 ); said front and back surface each having an inner portion ( 50   a ) and a sloped outer portion ( 50   b ); the sloped outer portions ( 50   b ) sloping toward each other such that said disk ( 44 ) reduces in thickness; 
 said cage ( 48 ) comprising a plurality of trapezoidally shaped dividers ( 52 ) extending radially outwardly from said radial outer surface of said inner portion ( 50 ) and a circumferential rail ( 54 ) extending around said dividers; said dividers and rail, in combination, defining a plurality of pockets ( 56 ); said magnets ( 58 ) being received in said pockets. 
 
     
     
         5 . A method for heat treating a gear ( 32 ) having gear teeth ( 32   a ); said method including:
 (a) removably mounting said gear ( 32 ) on a work piece holder ( 30 );   (b) moving one of either a magnet assembly ( 40 ) or said work-piece holder ( 30 ) to bring said gear ( 32 ) and said magnet assembly ( 40 ) into heating proximity; said magnet assembly ( 40 ) comprising a disk ( 44 ) having a circumferential surface and a plurality of magnets ( 58 ) or groups of magnets extending from said surface; said magnets or groups of magnets having opposed faces ( 58   a,b ) defining north and south poles; said magnets ( 58 ) or groups of magnets being arranged about said disk ( 44 ) such that the poles alternate; said step of moving one of said magnet assembly ( 40 ) and said work piece holder ( 30 ) comprising positioning said magnet assembly ( 40 ) and said work piece holder  30  relative to each other such that said opposed faces ( 58   a,b ) of said magnets or groups of magnets of said magnet assembly face surfaces ( 32   b ) of said gear teeth ( 32   a ) to be treated;   (c) rotating said magnet assembly ( 40 ) for a desired amount of time while said magnet assembly ( 40 ) and gear ( 32 ) are in heating proximity to each other to heat treat the surfaces ( 32   b ) of said gear teeth ( 32   a ) in heating proximity to said magnet assembly; and   (d) moving one of either said magnet assembly ( 40 ) or said work-piece holder ( 30 ) relative to the other to bring different surfaces of said gear ( 32 ) into heating proximity with said magnet assembly ( 40 ); and   (e) repeating steps (b)-(d) for each opposed pair of gear teeth surfaces ( 32   b ) until all said gear teeth surfaces are heat treated.   
     
     
         6 . The method of  claim 5  wherein said step (d) comprises moving one of said magnet assembly and said work-piece relative to the other to separate said magnet assembly and said gear such that said magnet assembly and gear are no longer in heat treating proximity to each other; rotating said work-piece holder ( 30 ) to bring untreated gear teeth surfaces ( 32   b ) into position to be heated; and then moving one of said magnet assembly and said work-piece relative to the other to bring different surfaces of said gear into heating proximity with said magnet assembly 
     
     
         7 . The method of  claim 5  wherein said step of moving of steps (b) and (d) comprise moving said magnet assembly ( 40 ) relative to said work piece holder ( 30 ). 
     
     
         8 . The method of  claim 7  wherein said wherein said step of moving said magnet assembly ( 40 ) comprises moving said magnet assembly in a vertical plane. 
     
     
         9 . The method of  claim 7  wherein said magnet assembly ( 40 ) is continuously moved in a reciprocating fashion passed said gear teeth surfaces ( 32   b ); said magnet assembly being moved at a rate which will allow for said gear teeth surfaces to be heat treated a desired amount; 
     
     
         10 . The method of  claim 9  wherein said work-piece holder ( 30 ) is rotated in a step wise fashion, said work-piece holder being rotated when said magnet assembly ( 40 ) is out of heating proximity with said gear ( 32 ), to move untreated gear teeth surfaces into the path of said magnet assembly to heat treat said gear teeth surfaces. 
     
     
         11 . An apparatus for heat treatment of a work piece via magnetic inductive heating; the apparatus comprising:
 a magnet assembly including a plurality of magnetic regions positioned around a circumference of a disk, said magnetic regions defining alternating north and south poles on at least one face of said disk adjacent to said disk outer circumference;   a drive operatively connected to said magnet assembly to rotate said magnet assembly about a transverse axis of said disc;   a work-piece holder adapted to removably hold a work piece having surfaces to be heat treated; and   means for moving one or both said magnet assembly and work-piece holder relative to each other to bring said magnet assembly and work piece surfaces into heating proximity with each other; such that rotation of said magnet assembly about said axis induces heating of said work piece surfaces through magnetic inductive heating.   
     
     
         12 . The apparatus of  claim 11  wherein each of said plurality of magnetic regions consist of a group of permanent magnets, each group of permanent magnets having magnetic poles aligned opposite to the magnetic poles of adjacent groups of permanent magnets. 
     
     
         13 . The apparatus of  claim 11  wherein each of said plurality of magnetic regions consists of a permanent magnet, and wherein said plurality of magnetic regions defines an alternating magnetic pole. 
     
     
         14 . The apparatus of  claim 11  wherein said work piece is a toothed gear, and wherein said disk of said magnetic assembly is configured with radially tapered surfaces for alignment between adjacent teeth of said toothed gear, whereby said plurality of magnetic regions are disposed in heating proximity to said gear tooth surfaces during said magnetic inductive heating.