Induction heat treatment of complex-shaped workpieces

A method of heat treating pre-selected components of a metal workpiece comprising at least two first substantially cylindrical components arranged coaxially along the main axis of said workpiece, one or more second substantially cylindrical components interposed between said at least two first substantially cylindrical components, each one of said one or more second substantially cylindrical components having an independent axis offset from and in parallel with said main axis, each one of said first and second substantially cylindrical components connected to an adjacent non-heat treated irregularly-shaped component, the method comprising:

• engaging said metal workpiece;
• transporting said metal workpiece to an induction heat treatment station;
• rotating said metal workpiece to angularly orient each one of said pre-selected second substantially cylindrical components for siting within a stationary partial inductor opening for each one of said pre-selected second substantially cylindrical components in said induction heat treatment station;
• translating said metal workpiece to axially orient each one of said pre-selected first and second substantially cylindrical components for siting within a stationary partial inductor opening for each one of said pre-selected first and second substantially cylindrical components in said induction heat treatment station;
• seating said metal workpiece in said induction heat treatment station;
• positioning a non-stationary partial inductor adjacent to each one of said stationary partial inductor openings to form a substantially closed inductor around each one of said pre-selected first and second substantially cylindrical components;
• applying an ac high frequency current to each one of said stationary partial inductors;
• inductively coupling said ac high frequency current to each one of said non-stationary partial inductors;
• inductively heating said pre-selected first and second substantially cylindrical components by imposing a magnetic field established by said ac high frequency current on said pre-selected first and second substantially cylindrical components;
• positioning each one of said non-stationary partial inductors away from each one of said stationary partial inductors;
• and
• transporting said metal workpiece from said induction heat treatment station.

An inductor for heating at least one substantially cylindrical component of a metal workpiece, said substantially cylindrical component attached on at least one side to an irregularly-shaped component, a fillet formed between said irregularly-shaped component and said substantially cylindrical component, the inductor formed from a first inductor segment and a second inductor segment, said first and second inductor segments having means for magnetically coupling to said second inductor segment an ac high frequency current supplied to said first inductor, a substantially closed opening formed partially in said first inductor segment and partially in said second inductor segment for placement of said substantially cylindrical component for heating by application of a magnetic field generated by said first and second inductor segments in response to excitation by said ac high frequency current to said component, the improvement comprising:

• said first inductor segment formed from a solid electrically conductive material, said first inductor segment further comprising:
• a first facing surface;
• a through opening forming a first coil segment and a second coil segment disposed on opposing sides of said through opening;
• and
• a first partial opening in either said first or second coil segment, said first partial opening having an arcuate coil surface divided by an orifice, said orifice dividing said arcuate coil surface into a first pair of coil lips, said first pair of coil lips forming an interface region with adjoining said first facing surface wherein said first pair of coil lips are profiled to selectively compensate for the irregular mass of said irregularly-shaped component, an opening on the surface of said substantially cylindrical component, or selective heating of said fillet;
• and
• said second inductor segment formed from a solid electrically conductive material, said second inductor segment further comprising:
• a second facing surface, said second facing surface disposed substantially adjacent to and electrically isolated from said first facing surface;
• a through opening forming a third coil segment and a fourth coil segment disposed on opposing sides of said through opening;
• and
• a second partial opening in either said third or fourth coil segment, said second partial opening having an arcuate coil surface divided by an orifice, said orifice dividing said arcuate coil surface into a second pair of coil lips, said second pair of coil lips forming an interface region with adjoining said second facing surface wherein said second pair of coil lips are profiled to selectively compensate for the irregular mass of said irregularly-shaped component, an opening on the surface of said substantially cylindrical component, or selective heating of said fillet, said first and second partial openings forming said substantially closed opening.

An inductor for heating at least one substantially cylindrical component of a metal workpiece, said substantially cylindrical component attached on at least one side to an irregularly-shaped component, a fillet formed between said irregularly-shaped component and said substantially cylindrical component, the inductor comprising:

• an active partial inductor formed from an electrically conductive material, said active partial inductor comprising:
• an active facing surface;
• a through opening forming a first active coil segment and a second active coil segment disposed on opposing sides of said through opening;
• an active partial opening in either said first or second active coil segment, said first partial opening having an arcuate surface divided by an orifice, said orifice dividing said arcuate coil surface into a first pair of coil lips, said first pair of coil lips forming an interface region with adjoining said first facing surface wherein said first pair of coil lips are profiled to selectively compensate for the irregular mass of said irregularly-shaped component, an opening on the surface of said substantially cylindrical component, or selective heating of said fillet;
• means for connecting to the output of an ac high frequency power supply;
• and
• an at least one first magnetic flux concentrator segment having at least two facing surfaces, each one of said at least one first magnetic flux concentrator segment disposed partially around a flux concentrator area of said active partial inductor;
• and
• a first passive partial inductor comprising:
• a first passive facing surface;
• a through opening forming a first passive coil segment and a second passive coil segment disposed on opposing sides of said through opening;
• and
• a first passive partial opening in either said first or second passive coil segment, said first passive partial opening having an arcuate surface;
• a second passive partial inductor, said second passive partial inductor disposed within said first passive partial inductor and electrically isolated from said first passive partial comprising:
• a second passive facing surface, said first and second passive facing surfaces in combination disposed substantially adjacent to and electrically isolated from said active facing surface;
• a through opening forming a third passive coil segment and a fourth passive coil segment disposed on opposing sides of said through opening;
• a second passive partial opening in either said third or fourth passive coil segment adjacently disposed with said first passive partial opening in either said first or second passive coil segment, said first passive partial opening having an arcuate surface, said first and second passive partial openings in combination disposed substantially adjacent to said active partial opening to form a substantially closed coil opening around said at least one substantially cylindrical component;
• and
• an at least one second magnetic flux concentrator segment having at least two facing surfaces, each one of said least one second magnetic flux concentrator segment disposed partially around a flux concentrator area of said first and second passive partial inductors;
• each one of said at least two facing surfaces having a corresponding opposing one of said at least two facing surfaces on one of said at least one first magnetic flux concentrator segment, whereby said active partial inductor is inductively coupled with said first and second passive partial inductors.

An induction heat treatment system for the heat treatment of a crankshaft having an arrangement of substantially cylindrical mains and pins separated from each other by an irregularly-shaped web and axially terminated with one or more end elements, a fillet formed between each one of said irregularly-shaped web and adjacent main or pin, said mains and end elements coaxially arranged along the main axis of the crankshaft, and each one of said pins having an independent axis offset from and in parallel with the main axis, the induction heat treatment system comprising:

• at least one ac high frequency power supply;
• a plurality of induction heat treatment stations, each one of said plurality of heat treatment stations inductively heating one or more pre-selected mains, pins and end elements, each of said plurality of induction heat treatment stations comprising:
• a first pallet assembly comprising:
• a first base plate;
• at least one first inductor segment formed from a solid electrically conductive material, each of said at least one first inductor segment having a first facing surface and an interior through opening, said through opening forming a first coil segment and a second coil segment, the side of each one of said at least one first inductor segment opposing said first facing surface adjoining said first base plate, either one of said first or said second coil segments having a first partial crankshaft component opening, said first partial crankshaft component opening having a generally arcuate coil surface, each of said at least one first inductor segment having means for connecting said first inductor segment to the output of one of said at least one ac high frequency power supply;
• an at least one first magnetic flux concentrator segment having at least two facing surfaces, each of said at least one first magnetic flux concentrator segment disposed partially around a flux concentrator area of said at least one first inductor segment;
• means for positive axial location of said crankshaft;
• and
• means for seating said crankshaft in first pallet assembly;
• a second pallet assembly comprising:
• a second base plate;
• at least one second inductor segment formed from a solid electrically conductive material, each of said at least one second inductor segment having a second facing surface and an interior through opening, said interior through opening forming a third coil segment and a fourth coil segment, the side of each one of said at least one second inductor segment opposing said second facing surface adjoining said second base plate, either one of said third or said fourth coil segments having a second partial crankshaft component opening, the facing surface and interior through opening of each one of said at least one second inductor segment having a corresponding opposing first facing surface and interior opening in said at least one first inductor segment, said second partial crankshaft component opening having a generally arcuate coil surface, each of said second partial crankshaft component opening having a corresponding opposing first partial crankshaft component opening in said at least one first inductor segment;
• and
• an at least one second magnetic flux concentrator segment having at least two facing surfaces, each one of said at least two facing surfaces having an opposing facing surface in said at least one first magnetic flux concentrator segment, each one of said least one second magnetic flux concentrator segment disposed partially around a flux concentrator area of said at least one second inductor segment;
• and
• a dielectric material disposed on the facing surface of each one of said at least one first inductor segment or said at least one second inductor segment;
• and
• a crankshaft transport system to move said crankshaft between said plurality of heat treatment stations, said crankshaft transport system cooperatively engaging said crankshaft with said means for positive axial location of said crankshaft to axially locate said crankshaft in said first pallet assembly;
• a crankshaft positioning system to rotatively orient each one of said one or more pre-selected pins for heat treatment;
• and
• means for selectively moving said second pallet assembly adjacent to said first pallet assembly whereby all faces of said at least one second inductor segment and said at least one second magnetic flux concentrator segment are adjacent to said corresponding opposing facing surfaces of said at least one first inductor segment and said at least one first magnetic flux concentrator segment, respectively, and each of said first partial crankshaft component opening and corresponding opposing second partial crankshaft component opening form a substantially closed inductor within which one of said pre-selected mains, pins and end elements is heated by a magnetic field generated by said substantially closed inductor in response to excitation by high frequency ac current from said at least one ac high frequency supply.

A method of heat treating pre-selected components of a crankshaft having a main axis, said crankshaft comprising two or more mains, two or more pins, a plurality of non-heat treated webs having an unsymmetrical and irregular shape, one of said plurality of non-heat treated webs attached to each adjacent main or pin to form a fillet between each one of said plurality of non-heat treated webs and attaching main or pin, and one or more end elements, said mains and end elements coaxially arranged along the main axis, each one of said pins having an independent axis offset from and in parallel with the main axis, said mains, pins and webs having one or more skewed through passages, each of said passages terminating in an opening on the surface of one of said mains or pins, the method comprising:

• engaging said crankshaft;
• transporting said crankshaft to an induction heat treatment station;
• rotating said crankshaft to properly orient said pre-selected pins for siting within stationary partial inductor openings in said induction heat treatment station;
• translating said crankshaft to properly orient said pre-selected mains, pins and end elements for siting within stationary partial inductor openings;
• seating said crankshaft in said induction heat treatment station;
• positioning non-stationary partial inductors adjacent to the stationary partial inductor openings to form a substantially closed inductor around each one of said pre-selected mains, pins and end elements;
• applying an ac high frequency current to each one of said stationary partial inductors;
• inductively coupling said ac high frequency current to each one of said non-stationary partial inductors;
• inductively heating said pre-selected mains, pins and end elements by a magnetic field established by said ac high frequency current and formed to compensate for the unsymmetrical and irregular shape of a web adjacent to one of said pre-selected mains, pins or end elements and said opening on the surface of one of said mains or pins to produce a substantially uniform heat treatment of said surface;
• positioning non-stationary partial inductors away from said stationary partial inductors;
• and
• transporting said crankshaft from said induction heat treatment station.