Patent ID: 7930956
Filing Date: 2011-04-26
Classification: B23B,F16C,Y10T

Abstract:
1. A multi-spindle automatic screw machine having a tool arm mounted on a shaft for rotational movement relative to a revolving head cap, said shaft being journalled on said head cap at two axially-spaced locations on said shaft, one of said locations being closer to said tool arm and the other of said locations being farther from said tool arm, wherein the improvement comprises: said shaft having an enlarged portion proximate said one location that has a diameter greater than the diameters of the adjacent shaft portions on either side thereof; said shaft enlarged portion having a hardened surface; a needle bearing operatively arranged between said shaft enlarged portion and a portion of said revolving head cap such that said bearing is radially loaded with the individual needles of said needle bearing being elastically deformed; whereby said tool arm has the capability of reduced tool chatter, increased tool life, tighter part tolerances, more aggressive relative speeds and fees between the said tool and a workpiece, and substantially extended service intervals.