Camshaft bore machining method and apparatus

A machine tool for machining in a workpiece a series of longitudinally spaced apart journals for a camshaft for an engine comprising:

• a base, a drive carried by said base for rotating a boring bar and longitudinally reciprocating the boring bar relative to the base, a boring bar having an axially elongate body having a single cutting insert immediately adjacent one end of said body for machining one at a time the journals of the series of longitudinally spaced apart journals of the workpiece, said elongate body being constructed and arranged to be connected adjacent its other end to said drive to rotate said cutting insert about an axis of rotation, and a plurality of longitudinally extending bearing pads circumferentially spaced about the periphery of said body, carried by said body and extending longitudinally from adjacent such one end of said body at least one half of the longitudinal extent of said body, and bearing pads having arcuate peripheral surfaces with a center coincident with an axis of rotation of said cutter insert and a diameter not greater than and only slightly smaller than the diameter of the bore machined by the cutting insert when rotated by said drive, a workpiece locator carried by the base, a clamp mechanism associated with said locator and constructed and arranged to clamp the located workpiece with the axes of its series of journals to be machined substantially coincident with the axis of rotation of said cutting insert of said boring bar, and an actuator associated with said drive and constructed and arranged to in-feed the cutting insert of the boring bar toward and through each of the workpieces while the insert is rotating to sequentially machine one at a time a bore through each of journals of the series with the same cutting insert and to dispose the bearing pads in at least the immediately preceding journal machined by the cutting insert to radially constrain and support the boring bar while the cutting insert is machining at least the immediately succeeding journal of the series.

A boring bar for machining in a workpiece a series of longitudinally spaced apart journals for a camshaft of an engine, comprising:

• an axially elongate and generally cylindrical body, a single cutting insert carried by said body immediately adjacent one end thereof and constructed and arranged to machine a bore through one journal at a time when said body is rotated and in-fed through such journals, connector means adjacent the other end of said body constructed and arranged for coupling said body to a spindle for rotating said body and in-feeding said cutting insert through each of the journals one at a time to machine with the same cutting insert a bore through each of the journals of the series of the workpiece, a plurality of bearing pads circumferentially spaced about and carried by said body with each pad extending longitudinally from adjacent said one end of said body at least one half of the longitudinal extent of said body, and said bearing pads having arcuate outer peripheral surfaces concentric with the axis of rotation of the boring bar and having a diameter not greater than and only slightly less than the diameter of the bore machined by said cutting insert of the boring bar so that when said cutting insert machines each journal in the series said pads extend through all the preceding journals machined by said cutting insert to radially constrain and support the boring bar while said cutting insert machines such each journal.