Method of grinding the teeth of bevel gears having longitudinally curved teeth

A method of grinding rough-cut longitudinally curved gear teeth of a bevel gear blank by means of a tool driven in rotation about a tool axis and entailing the performance of at least one relative feed motion between the bevel gear blank and the tool, comprising the steps of:

• employing for the tool a helical bevel gear hypoidally related to the rough-cut longitudinally curved gear teeth to be ground of the bevel gear blank;
• said helical bevel gear having a predetermined number of teeth;
• each tooth of said predetermined number of teeth having at least one tooth flank provided with an abrading surface;
• arranging said helical bevel gear in a hypoidally displaced relationship to the rough-cut longitudinally curved gear teeth to be ground of the bevel gear blank;
• said step of arranging said helical bevel gear in said hypoidally displaced relationship entails arranging said helical bevel gear relative to the rough-cut longitudinally curved gear teeth to be ground of the bevel gear blank such that said helical bevel gear and the rough-cut longitudinally curved teeth to be ground conjointly define a skewed hypoid gear transmission;
• arranging said helical bevel gear in mesh with the rough cut longitudinally curved gear teeth to be ground of the bevel gear blank;
• positively driving said helical bevel gear and the bevel gear blank in a synchronous relationship at rotary speeds proportional to their respective numbers of teeth;
• selecting said hypoidally displaced relationship of said helical bevel gear to the rough-cut longitudinally curved gear teeth to be ground and selecting said rotary speeds such that a relative sliding velocity arising therebetween falls in the range of predetermined surface speeds for grinding;
• and
• continuously grinding in a single operation and with said at least one relative feed motion at least a selected set of the set of all concave tooth flanks and the set of all convex tooth flanks of the rough-cut longitudinally curved gear teeth to be ground.

A method of using an apparatus for grinding tooth flanks of a first number of longitudinally curved teeth of a rough machined bevel gear blank for a hypoid gear pair of by means of a rotary form tool having a second number of gear teeth, comprising the steps of:

• mounting the rough machined bevel gear blank in a first spindle of the apparatus to rotate about a first axis of rotation;
• employing as the rotary form tool a rotary form tool having a second number of teeth and at least one abrading surface;
• mounting the rotary form tool in a second spindle of the apparatus to rotate about a second axis of rotation;
• adjusting a selected one of said first spindle and said second spindle such that the rough machined bevel gear blank and the rotary form tool mesh such that said first axis of rotation and said second axis of rotation mutually define a hypoidally displaced relationship with said first and second axis defining an angle less than 90.degree. or greater than 90.degree. with respect to one another and in which conjoint rotation of said first spindle and said second spindle produces relative sliding between tooth flanks of the rough machined bevel gear blank and the rotary form tool;
• selecting said hypoidally displaced relationship and a first speed of rotation for said second spindle such that said relative sliding has a velocity lying within the range of predetermined surface speeds for abrading operations;
• employing first rotary drive means to rotate said first spindle at said first speed of rotation;
• employing second rotary drive means conjointly with regulation means to rotate said second spindle in synchronism with said first spindle at a second speed of rotation related to said first speed of rotation by the ratio of said first number of longitudinally curved teeth to said second number of gear teeth;
• and
• effecting a relative feed motion between said first spindle and said second spindle.