Narrow shoe journal microfinishing apparatus and method

Abstract

A microfinishing machine and method especially adapted for processing of internal combustion engine crankshafts and other workpieces. Microfinishing is achieved by tooling having abrasive inserts or which present abrasive coated film against the journal to be machined. The tooling has a width less than one-half the length of the journal being machined. The narrow width tooling allows a range of workpiece configurations to be processed with common tooling, and through control of one or more of machining parameters including clamping pressure acting on the tooling, oscillation of the tooling, and stroking schedule of the tooling, desired journal contour profiles can be produced.

1 . A microfinishing process for processing journal bearing surfaces of a crankshaft, the crankshaft of a type having bearing journals including at least one main bearing journal and at least one pin bearing journal, one or more of the bearing journals bound on axial ends by crankshaft webs or other radial obstructions, each of the bearing journals defining an axial length, comprising the steps of;
 providing tooling in the form of at least a pair of microfinishing shoes adapted to be clamped and unclamped from the bearing journal,   providing the tooling having an axial width of less than 50% of the bearing journal axial length and greater than 20% of the bearing journal axial length,   rotating the crankshaft relative to the tooling to provide a machining effect on the journal bearing surface, and   causing the tooling to stroke along the axial length of the bearing journal between the axial ends when rotating the crankshaft relative to the tooling providing the machining effect.   
     
     
         2 . A microfinishing process in accordance with  claim 1  further comprising providing the bearing journals includes providing the bearing journals having a range of the axial lengths. 
     
     
         3 . A microfinishing process in accordance with  claim 1  further comprising varying a machining parameter while providing the machining effect including one or more of; clamping pressure of the tooling, oscillation of the tooling, and dwell time or stroking velocity of the tooling. 
     
     
         4 . A microfinishing process in accordance with  claim 1  further comprising varying a machining parameter while providing the machining effect as a function of the axial position of the tooling along the axial length of the journal bearing. 
     
     
         5 . A microfinishing process in accordance with  claim 1  further comprising varying a machining parameter by adjusting the clamping pressure exerted on the tooling as a function of the position of the tooling along the axial length of the journal surface. 
     
     
         6 . A microfinishing process in accordance with  claim 1  further comprising varying a machining parameter by adjusting the oscillation frequency of the tooling as a function of the position of the tooling along the axial length of the journal surface. 
     
     
         7 . A microfinishing process in accordance with  claim 1  further comprising varying a machining parameter by adjusting the oscillation displacement of the tooling as a function of the position of the tooling along the axial length of the journal surface. 
     
     
         8 . A microfinishing process in accordance with  claim 1  further comprising varying a machining parameter by adjusting the stroking schedule of the tooling as a function of the position of the tooling along the axial length of the journal surface. 
     
     
         9 . A microfinishing process in accordance with  claim 1  further comprising rotating the crankshaft relative to the tooling during the microfinishing process. 
     
     
         10 . A microfinishing process in accordance with  claim 1  further comprising wherein the tooling pressing an abrasive coated film against the bearing journal when the tooling is clamped against the bearing journal. 
     
     
         11 . A microfinishing process in accordance with  claim 1  further comprising providing the tooling in the form of a pair of shoes supported by clamping arms. 
     
     
         12 . A microfinishing process in accordance with  claim 1  further comprising the step of causing the tooling to stroke along the axial length of the bearing journal including the tooling crossing the axial center of the journal bearing surface and at positions of the tooling at the axial ends of the bearing journal, the tooling is not acting on the bearing journal surface at the axial center. 
     
     
         13 . A microfinishing process in accordance with  claim 1  further comprising the step of providing a desired profile shape for the bearing journal surface including one of a constant diameter form, a barrel shape form, an hourglass shape form, and a double barrel shape form by varying a machining parameter while providing the machining effect as a function of the axial position of the tooling along the axial length of the journal bearing. 
     
     
         14 . A microfinishing apparatus for processing journal bearing surfaces of a crankshaft, the crankshaft of a type having bearing journals including at least one main bearing journal and at least one pin bearing journal, one or more of the bearing journals bound on axial ends by crankshaft webs or other radial projections, each of the bearing journals defining an axial length, comprising;
 tooling in the form of at least a pair of microfinishing shoes adapted to be clamped and unclamped from the bearing journals, the tooling having an axial width of less than 50% of the bearing journal axial length and greater than 20% of the bearing journal axial length,   a drive for rotating the crankshaft relative to the tooling to provide a machining effect on the journal bearing surface,   clamping arms which position the tooling to engage the bearing journal surface and press the tooling against the bearing journal surface,   a shuttle for causing the tooling to oscillate along the axial length of the bearing journal, and   an arm stroking actuator for causing the tooling to stroke along the axial length of the bearing journal along the axial length of the journal when the drive is rotating the crankshaft relative to the tooling providing the machining effect.   
     
     
         15 . A microfinishing machine in accordance with  claim 14  further comprising the bearing journals includes providing the bearing journals having a range of the axial lengths. 
     
     
         16 . A microfinishing machine in accordance with  claim 14  further comprising a controller for varying a machining parameter while providing the machining effect including one or more of; clamping pressure of the tooling, oscillation of the tooling, and dwell time of the tooling. 
     
     
         17 . A microfinishing machine in accordance with  claim 14  further comprising a controller for varying a machining parameter while providing the machining effect by varying as a function of the axial position of the tooling along the axial length of the journal bearing. 
     
     
         18 . A microfinishing machine in accordance with  claim 14  further comprising a controller varying a machining parameter by adjusting the clamping pressure exerted on the tooling as a function of the position of the tooling along the axial length of the journal surface. 
     
     
         19 . A microfinishing machine in accordance with  claim 14  further comprising a controller for varying a machining parameter by adjusting the oscillation frequency of the tooling as a function of the position of the tooling along the axial length of the journal surface. 
     
     
         20 . A microfinishing machine in accordance with  claim 14  further comprising a controller for varying a machining parameter by adjusting the oscillation displacement of the tooling as a function of the position of the tooling along the axial length of the journal surface. 
     
     
         21 . A microfinishing machine in accordance with  claim 14  further comprising a controller for varying a machining parameter by adjusting the stroking schedule of the tooling as a function of the position of the tooling along the axial length of the journal surface. 
     
     
         22 . A microfinishing machine in accordance with  claim 14  further comprising the drive rotating the crankshaft relative to the tooling during the microfinishing process. 
     
     
         23 . A microfinishing machine in accordance with  claim 14  further comprising wherein the tooling pressing an abrasive coated film against the bearing journal when the tooling is clamped against the bearing journal. 
     
     
         24 . A microfinishing machine in accordance with  claim 14  further comprising the tooling in the form of a pair of shoes supported by clamping arms. 
     
     
         25 . A microfinishing machine in accordance with  claim 14  further comprising the stroking actuator configured for causing the tooling to stroke along the axial length of the bearing journal including the tooling crossing the axial center of the journal bearing surface and at positions of the tooling at the axial ends of the bearing journal, the tooling is not acting on the bearing journal surface at the axial center. 
     
     
         26 . A microfinishing machine in accordance with  claim 14  further comprising a controller to configured for providing a desired profile shape for the bearing journal surface including one of a constant diameter form, a barrel shape form, an hourglass shape form, and a double barrel shape form by varying a machining parameter while providing the machining effect as a function of the axial position of the tooling along the axial length of the journal bearing.