US 5,336,024 A · Precision drilling method

Abstract

In a precision drilling method for drilling a straight hole in a work with a drill, a drill unit for rotating the drill is supported to a housing in suspension by an electromagnetic force consisting of separately controllable restoring and damping elements. The drill unit is supported by first restoring and damping elements such that a positional displacement of the drill unit is permitted to relieve a contacting pressure applied to the drill unit when the drill comes into contact with the work. The positional displacement of the drill unit is monitored by sensors. When a force applied to the drill unit, which is determined according to thus monitored displacement, is greater than a critical value, the first restoring element is increased to give a relatively strong support capable of rapidly restoring the position of the drill unit, and preferably the first damping element is also increased to rapidly damp a vibration of the drill unit induced by the positional displacement. Subsequently, the straight hole is drilled in the work with the drill by feeding the housing toward the work. As a result, it is possible to form the straight hole precisely at a desired position in the work without causing a breakage of the drill.

Claims19

Dependent claims

A precision drilling method for drilling a hole in a work with a drill unit having a drill bit, said drill unit being movably supported to a housing by electromagnetic force consisting of separately controllable restoring and damping elements, said method being characterized to vary at least one of stiffness of said restoring element and damping factor of said damping element between before and after said drill bit comes into engagement into said work.

A precision drilling method for drilling a hole in a work with a drill unit having a drill bit, said drill unit being movably supported to a housing by electromagnetic force consisting of separately controllable restoring and damping elements, said housing having a vertical axis along which it is advanced toward said work for drilling, said method comprising the steps of:

setting a stiffness of said restoring element to a first stiffness value and a damping factor of said damping element to a first damping value in order to give a relatively weak support of permitting said drill unit to displace by a relatively great extent in a direction of relieving a contacting pressure applied to said drill unit when said drill bit first comes into contact with said work;
monitoring a force applied to said drill unit when said drill bit first comes into contact with said work with respect to at least one of the directions along and about three mutually perpendicular axes including said vertical axis;
increasing said stiffness from said first stiffness value to a second stiffness value in response to said monitored force becoming greater than a critical value to thereby give a relatively strong support capable of rapidly restoring the position of said drill unit and holding said drill unit stably for proceeding the drilling of the hole.

A precision drilling method for drilling a hole in a work with a drill unit having a drill bit, said drill unit being movably supported to a housing by electromagnetic force consisting of separately controllable restoring and damping elements, said housing having a vertical axis along which it is advanced toward said work for drilling, said method comprising the steps of:

setting a stiffness of said restoring element to a first stiffness value and a damping factor of said damping element to a first damping value in order to give a relatively weak support of permitting said drill unit to displace by a relatively great extent in a direction of relieving a contacting pressure applied to said drill unit when said drill bit first comes into contact with said work;
monitoring a force applied to said drill unit when said drill bit first comes into contact with said work with respect to at least one of the directions along and about three mutually perpendicular axes including said vertical axis;
increasing said stiffness from said first stiffness value to a second stiffness value as well as varying said damping factor from said first damping value to a second damping value in response to said force becoming greater than a critical value to thereby give a relatively strong support capable of rapidly restoring the position of said drill unit without causing substantial vibration and holding said drill unit stably for proceeding the drilling of the hole.

Dependencies are inferred from the claim text.

Precision drilling method

Life of this patent

Precision drilling method

Life of this patent

Abstract

Claims19