Browse Prior Art Database

Extrusion Tip Drill

IP.com Disclosure Number: IPCOM000121172D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 55K

Publishing Venue

IBM

Related People

Houser, DE: AUTHOR

Abstract

Disclosed is a twist drill with unique web geometry designed to minimize total chip drag on the hole wall during drilling. This should decrease heat generation, thereby improving hole wall quality and decreasing drill breakage.

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Extrusion Tip Drill

      Disclosed is a twist drill with unique web geometry designed to
minimize total chip drag on the hole wall during drilling.  This
should decrease heat generation, thereby improving hole wall quality
and decreasing drill breakage.

      Fig. 1 shows a conventional straight web drill.  The torque in
the drill increases from the point of the drill upwards because of
the friction of the increasing length of chips against the hole wall.
As higher and higher chip loads and aspect ratios are attempted,
these drills will start to break due to the increased torque loading
caused by the increased friction against the hole wall.

      The conventional way to reach higher aspect ratios and chip
loads is to use a tapered web drill as is shown in Fig. 2 to
match the increasing torque loading with increasing strength along
the length of the drill.  This is somewhat self-defeating, however,
because the chips are forced to flow through a smaller and smaller
area and so the loading increases even further along with the
strength.  A penalty must also be paid in hole quality because more
heat is generated which can cause more smear, gouging, roughness,
etc.

      A better way to reach higher aspect ratios may be to use an
extrusion tip drill as shown in Fig. 3.  This drill utilizes a web as
shown in the diagram to size the chips near the tip of the drill.
The web thickness decreases above the sizing area to relieve the
pressure of the chips agai...