Process for drilling a bore and corresponding tool

1. A tool for drilling a bore, wherein the tool comprises:

a casing;

a tool-holder spindle which extends along an axis and which is to carry a drilling tool; and

a drive mechanism for driving the tool-holder spindle, wherein the drive mechanism is capable of driving the drilling tool simultaneously in rotation about an axis and in translation along the axis in accordance with an advance movement, the drive mechanism being suitable for combining the advance movement of the spindle with an oscillating movement along the axis of an amplitude sufficient to break up swarf formed, while at the same time keeping the drilling tool in the bore which is in the process of being drilled, the drive mechanism comprising:

a first drive member for driving the spindle in rotation about its axis relative to the casing;

a second drive member for driving the spindle in translation along its axis relative to the casing, the second drive member being screwed onto a threaded portion of the spindle, so that the spindle advances or returns along the axis as a function of a relative rate of rotation of the first drive member and the second drive member, wherein the second drive member is movably coupled to a clutch at a first end of the second drive member; and

a cam/cam follower unit for ensuring the oscillating movement of the spindle, the cam/cam follower unit comprising a cam and a cam follower, the cam being fixed for rotation with the spindle, and the cam follower being fixed for rotation with the second drive member, wherein the second drive member includes the cam follower at a second end of the second drive member and wherein the cam is distinct from the second drive member and positioned adjacent to the cam follower.

2. The tool according to claim 1 , wherein a relief in a form of a recess is formed in a surface of the second drive member.

3. The tool according to claim 1 , wherein the oscillating movement has an amplitude greater than or equal to the advance of the spindle in the course of one revolution of the second drive member about the axis relative to the first drive member.

4. The tool according to claim 1 , wherein the second drive member is axially mobile relative to the casing between an advanced position and a returned position.

5. The tool according to claim 1 , wherein the drive mechanism comprises a mechanism for an axial bearing of the cam/cam follower unit on the second member.

6. The tool according to claim 5 , wherein the axial bearing mechanism comprises resilient means bearing at the rear on the casing and at the front on the cam.

7. The tool according to claim 6 , wherein resilient means is a thrust spring.

8. The tool according to claim 6 , further comprising a roller bearing positioned between the cam and the resilient means.

9. The tool according to claim 5 , wherein:

the axial bearing mechanism comprises resilient means bearing at the rear on the casing and at the front on the cam;

the first drive member is a first gear wheel slipped onto the spindle and fixed for rotation with the spindle;

the drive mechanism comprises a mechanism for an axial bearing of the cam/cam follower unit on the second member and a second gear wheel surmounting the first gear wheel, wherein the second gear wheel is free in rotation relative to the spindle,

the second gear wheel is extended by a rotary positive clutch fixed for rotation with the second gear wheel,

the second drive member is a dog/positive clutch comprising coupling teeth, the coupling teeth enabling the second drive member to be form-fitted to the rotary positive clutch, wherein the height of the coupling teeth and of those of the rotary positive clutch enable the form-fit to be maintained when the dog/positive clutch is displace axially between its advanced position and its returned position.

10. The tool according to claim 1 , further comprising a gap between a portion of a surface of the cam and a portion of a surface of the cam follower.

11. The tool according to claim 1 , wherein the second drive member is coupled to the clutch when the second drive member is in a raised position relative to the clutch and wherein the second drive member is coupled to the clutch when the second drive member is in a lowered position relative to the clutch.