Method and apparatus for producing a hole in a workpiece

A method for machining in a workpiece a hole having a curved wall by using a cutting tool having a substantially cylindrical cutting head, said method comprising the steps of:

• positioning a longitudinal center axis of said cutting tool at an angle, which is offset from a normal to a flat surface of said workpiece;
• rotating the cutting tool about its longitudinal center axis;
• moving the cutting tool in a circular path about a principal axis corresponding to a longitudinal center axis of the hole to be formed;
• and
• varying the angle of inclination of the longitudinal center axis of the cutting tool while simultaneously feeding the cutting tool axially in its longitudinal direction towards and into the workpiece to form a curved section of a hole therein.

An apparatus for producing a conical hole in workpiece by using a cutting tool having a substantially cylindrical cutting head, said apparatus comprising:

• a first actuator including a spindle unit configured for carrying and rotating said cutting tool about a longitudinal center axis thereof;
• a second actuator configured for moving the cutting tool in an axial feed direction;
• a mechanism configured for rotating the cutting tool eccentrically about a principal axis corresponding to a longitudinal center axis of the hole to be formed;
• a mechanism configured for setting the angle of inclination of the longitudinal axis of the cutting tool relative to the principal axis;
• and
• a mechanism configured for setting a radial offset of the cutting tool relative to the principal axis;
• wherein said mechanism for setting the angle of inclination of the cutting tool comprises an inner cylindrical sleeve having a longitudinal through-hole, a longitudinal center axis of said through-hole being inclined an angle relative to a longitudinal center axis of said inner cylindrical sleeve, said through-hole of the inner sleeve being arranged to radially and axially guide a spindle unit for rotating said cutting tool about its longitudinal center axis;
• and an outer cylindrical sleeve having a hole with a longitudinal center axis that is inclined an angle relative to a longitudinal center axis of said outer cylindrical sleeve, said inner cylindrical sleeve being rotatably supported within said hole of the outer cylindrical sleeve so as to set the angle of inclination of the longitudinal center axis of the cutting tool.

An apparatus for producing a conical hole in workpiece by using a cutting tool having a substantially cylindrical cutting head, said apparatus comprising:

• a first actuator including a spindle unit configured for carrying and rotating said cutting tool about a longitudinal center axis thereof;
• a second actuator configured for moving the cutting tool in an axial feed direction;
• a mechanism configured for rotating the cutting tool eccentrically about a principal axis corresponding to a longitudinal center axis of the hole to be formed;
• a mechanism configured for setting the angle of inclination of the longitudinal axis of the cutting tool relative to the principal axis;
• and
• a mechanism configured for setting a radial offset of the cutting tool relative to the principal axis;
• wherein said mechanism for setting the angle of inclination of the cutting tool comprises an exchangeable member which has a flat surface oriented at a fixed angle of inclination relative to a plane perpendicular to said principal axis, said angle corresponding to the desired inclination of said cutting tool axis.