Crankshaft broaching machine and method

A broaching lathe for use in machining a plurality of bearings on a crankshaft or the like comprising rotatable work holder means rotatably supporting a crankshaft on a rotational axis, said crankshaft having front and rear main bearings at opposite ends thereof, said rotatable work holder means including a first center at one end of said crankshaft and a second center at the other end of said crankshaft, at least one of said centers being a driven center and said lathe being free of any center drive chuck that drivingly engages said crankshaft intermediate of the front and rear main bearings, a machine tool carrier mounted on said machine for movement in a first direction along a first path perpendicular to and spaced radially from said axis, a first plurality of at least about eight to twelve cutting tools mounted on said carrier in a first row with cutting edges projecting toward said axis to machine a bearing when said carrier moves in said first direction, and a second plurality of at least about eight to twelve cutting tools mounted on said carrier in a second row with cutting edges projecting toward said axis to machine a second bearing when said carrier moves in said first direction, said cutting tools in said first and said second rows comprising disposable inserts that are individually and removably mounted, and wherein the cutting tools in each row at a rear end of said carrier project deeper into said crankshaft than do the cutting tools at a front end of said carrier to thereby distribute machining forces between the cutting tools in each row during a machining operation, the cutting tools in each row have cutting edges inclined to said first direction to provide a leading cutting edge portion and a trailing cutting edge portion so that the cutting edges feed progressively into said bearings to thereby distribute cutting forces along said cutting edges, and wherein the leading cutting edge portions of the cutting tools in said first row are offset in the direction of travel of said slide from the leading edge portions of the cutting tools in said second row so as to further distribute machining forces between the cutting tools in said first and second rows.

A method of making a crankshaft or the like having a plurality of bearings concentric about a common axis extending longitudinally of the crankshaft comprising rotating the crankshaft on said axis while moving at least a first series and a second series of cutting tools in a first direction along respective first and second paths perpendicular to and spaced radially from said axis and in progressive machining engagement with respective bearings so as to substantially simultaneously turn a plurality of bearings concentric to said axis while distributing machining forces over a machining operation, said crankshaft having front and rear main bearings at opposite ends thereof and being rotated by drivingly engaging said crankshaft at at least one end and not at a location intermediate said front and rear main bearings, and wherein said machining forces are distributed over the machining operation by disposing a first plurality of at least about eight to twelve disposable cutting tool inserts that are individually and removably mounted in a first row extending in said direction perpendicular to said axis at a position longitudinally of said axis at a first bearing while simultaneously disposing a second plurality of at least about eight to twelve disposable cutting tool inserts that are individually and removably mounted in a second row extending in said direction perpendicular to said axis at a position longitudinally of said axis at a second bearing with the cutting tools at a rear end of each row projecting deeper into the crankshaft than the cutting tools at a front end of the row so that when the cutting tools are moved rectilinearly, the cutting tools in each row sequentially and progressively machine said bearings to thereby distribute the machining forces between the cutting tools in each row relative to other cutting tools in that row, said tools also being moved rectilinearly while being disposed at an inclined angle to the direction of motion so that leading cutting edge portions of said tools machine before trailing cutting edge portions to thereby distribute machining forces over each cutting tool, and wherein the leading cutting edge portions of the cutting tools in one row are machiningly engaged with a bearing before the leading cutting edge portions of the cutting tools in the other row are machiningly engaged with another bearing to thereby further distribute machining forces during a machining operation.

A method of machining crankshafts or the like having a plurality of bearings concentric about a common axis extending longitudinally of the shaft and including at least front and rear bearings at opposite ends thereof, comprising removably mounting a first plurality of at least eight to twelve individual disposable cutting tool inserts in a first row on a reciprocal slide, removably mounting at least eight to twelve individual disposable cutting tool inserts in a second row on said slide, said inserts being mounted on said slide so as to substantially optimize the distribution of machining forces during a machining operation by arranging and disposing the inserts to be progressively higher in a front-to-rear direction of slide so that machining forces are distributed between the inserts in each row, with the inserts having cutting edges inclined to the direction of travel of said slide to distribute machining forces over said cutting edges as they move progressively into a bearing, and with leading edges of the inserts in one row offset relative to leading edges of the inserts in the other row so as to distribute machining forces between the rows, and then supporting said shaft between a pair of spaced apart centers at opposite ends of said shaft, rotating said shaft on said axis by drivingly engaging said shaft at an end thereof and without drivingly engaging said shaft intermediate said front and rear main bearings, reciprocating said slide while said shaft is rotating to machiningly engage said inserts with said shaft and substantially simultaneously turn a plurality of bearings concentric to said axis while distributing cutting forces between the cutting tool inserts, and wherein said method further comprises sequentially machining a plurality of shafts until said inserts are to be periodically changed, removing said slide, removing worn inserts from said slide and replacing the worn inserts with new inserts and then remounting said slide and then machining a second plurality of shafts.

A lathe for use in machining a plurality of bearings on a shaft comprising a rotatable work holder means for rotatably supporting a shaft on a rotational axis, said shaft having front and rear bearings at opposite ends thereof, said rotatable work holder means including a first center at one end of said shaft and a second center at the other end of said shaft, at least one of said centers being a driven center and said lathe being free of any center drive chuck that drivingly engages said shaft intermediate of the front and rear main bearings, and a machine tool carrier having cutting tools mounted thereon with said carrier in turn being mounted on said machine for movement in a first direction to move said cutting tools tangentially across said shaft at a plurality of bearing locations, said cutting tools including a first plurality of cutting tools mounted on said carrier in a first row with cutting edges projecting toward said axis to machine a first bearing when said carrier moves in said first direction past said shaft, and a second plurality of cutting tools mounted on said carrier in a second row with cutting edges projecting toward said axis to machine a second bearing when said carrier moves in said first direction past said shaft, and wherein said cutting tools in said first and said second rows include removably mounted disposable inserts arranged and disposed relative to each other so as to distribute machining forces between each other as said cutting tools move across said shaft during a machining operation.

A method of machining shafts or the like having a plurality of bearings concentric about a common axis extending longitudinally of the shaft and including at least front and rear bearings at opposite ends thereof, comprising removably mounting a first plurality of individual disposable cutting tool inserts in a first row on a reciprocating slide, removably mounting a second plurality of individual disposable cutting tool inserts in a second row on said slide, said inserts being arranged and disposed on said slide so as to substantially optimize the distribution of machining forces between said cutting tool inserts during a machining operation, and then supporting said shaft between a pair of spaced apart centers at opposite ends of said shaft, rotating said shaft on said axis by drivingly engaging said shaft at an end thereof and without drivingly engaging said shaft intermediate said front and rear main bearings, reciprocating said slide while said shaft is rotating to machiningly engage said inserts with said shaft and substantially simultaneously turn a plurality of bearings concentric to said axis while distributing cutting forces between the cutting tool inserts, and wherein said method further comprises sequentially machining a plurality of shafts until said inserts are worn, removing said slide, removing the worn inserts from said slide and replacing the worn inserts with new inserts, remounting said slide with the new inserts thereon and then machining a second plurality of shafts with said new inserts.

A lathe for use in machining a plurality of bearings on a shaft comprising rotatable work holder means for rotatably supporting a shaft on a rotational axis and a machine tool carrier having cutting tools mounted thereon with said carrier in turn being mounted on said machine for movement in a first direction to move said cutting tools across said shaft at a plurality of bearing locations, said cutting tools including a first plurality of at least about eight to twelve individual disposable inserts removably mounted on said carrier in a first row with cutting edges projecting toward said axis to machine a bearing when said carrier moves in said first direction past said shaft and a second plurality of at least about eight to twelve individual disposable inserts removably mounted on said carrier in a second row with cutting edges projecting toward said axis to machine a second bearing when said carrier moves in said first direction, and wherein the cutting edges in each row at a trailing end of said carrier project deeper into said crankshaft than do the cutting edges at a leading end of said carrier to thereby distribute machining forces between the cutting edges in each row during a machining operation, the cutting edges in each row are inclined to said first direction to provide a leading cutting edge portion and a trailing cutting edge portion so that the cutting edges feed progressively into said bearings to thereby distribute cutting forces along said cutting edges, and wherein the leading cutting edge portions of the cutting tools in said first row are offset in the direction of travel of said carrier from the leading edge portions of the cutting tools in said second row so as to further distribute machining forces between the cutting tools in said first and second rows.