Drill

Details Drill Drill

1995-05-17

1997-07-22

Bishop, Steven C.

Cutting by use of rotating axially moving tool

With work-engaging structure other than tool or tool-support

Frictionally engaging sides of opening in work

408181, 408233, 408713, B23B 5100

Patent

active

056497946

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a drill having a base body, a groove provided in an end face for receiving a bit, a clamping device for retaining the bit, and guide strips provided in the circumference of the base body.
Drills serve for drilling bores in workpieces and can drill a solid material, so that the preliminary machining of a bore is not necessary. To this end, they are provided with cutting edges on the end face which cut off the workpiece material. However, a drawback turned up consisting in that the dimension of so produced bores, on one hand, is very imprecise, i.e. deviates from the desired dimension accuracy and, on the other hand, the surface has an unsatisfactory quality. Therefore, often a further machining of the bore was required before it could be subjected to precise machining. This necessitates use of numerous operational phases, the effecting of which is time-consuming and expensive.
Accordingly, the object of the invention is to provide a drill for machining bores in a solid material the dimensional accuracy and surface quality of which meet very high requirements so that at least some of the finishing steps can be eliminated.


SUMMARY OF THE INVENTION

This object is achieved in a drill of the above-discussed type by providing, according to the present invention, the drill with a bit having a side cutting edge projecting beyond the circumference of the base body. Opposite, it a first guide strip is provided. The width of the bit is so selected that it, in order to form two end face cutting edges, extends beyond the rotational axis of the drill which coincides with the central axis. Thereby, the drill is provided with two end-face cutting edges able to drill bores in a solid material. At least one of these end-face cutting edges extends sideways outwardly of the circumference of the base body of the drill and serves for machining the surface of the formed bore. At that, the forces applied to the bit or to the drill are taken up by the oppositely located first guide strip, whereby a very precise machining of the bore surface is insured so that, on one hand, a very good dimensional accuracy and, on the other hand, a very good surface quality are achieved.
According to an advantageous embodiment of the invention, it is provided that the bit is arranged in the groove for radial displacement relative to the rotational axis. Thereby, it becomes advantageously possible to displace the bit radially relative to the base body, whereby the position of the bit with respect to the oppositely arranged guide strip can be exactly provided. In particular, thereby the bore dimension can be exactly set as a distance between the guide strip and the oppositely located cutting edge. Also, thereby, the change of the dimension because of wear can be compensated.
According to a further advantageous embodiment of the invention it is provided that the bit has an extension extending axially into the base body and cooperating with a clamping and/or adjusting device. Thereby it becomes possible to provide the bit with an area which simultaneously can be used for fixing the bit in the base body and for effecting the radial displacement of the bit. The bit can thereby be formed very simply because additional locking surfaces for the bit need not be provided.
According to a further preferred embodiment of the invention, it is provided that the extension has active surfaces which, advantageously, extend at an angle, different from a right angle, to a radial plane extending through the groove, and further preferably extend at an angle to the rotational axis. By this particular shaping of the clamping surfaces, it is possible to achieve a reliable tightening of the bit because the tightening forces, which act on the bit, do not coincide with the possible displacement directions of the bit in the groove.
A particularly preferred embodiment of the drill is one in which the first guide strip is so arranged that it extends practically over the entire height of the bit measured in the direction of t

REFERENCES:
patent: 3033062 (1962-05-01), Carlstedt
patent: 3203493 (1965-08-01), Bergstrom
patent: 4279550 (1981-07-01), Kress et al.
patent: 4954024 (1990-09-01), Kress et al.

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