Title:
DRILL
Document Type and Number:
Japanese Patent JP2012056055
Kind Code:
A
Abstract:
To provide a drill which can be suitably used as drill for separating a spot welded portion of a chassis of an automobile, and can increase the number of drilled holes for spot welding separation up to four times that of a conventional one.
The drill has two cutting edges which are formed symmetrically with respect to a rotation axis, and a secondary spiral concave groove formed along the spiral grooves forming the cutting edges. In the secondary spiral groove, a contour line is an arc shape when seen from a drill tip end side or a substantially arc shape, from the projection portion of the drill tip end to a heel portion.
Inventors:
ARAI KOICHI
ARAI GIICHI
KIMURA KATSUYO
ARAI GIICHI
KIMURA KATSUYO
Application Number:
JP2010203777A
Publication Date:
March 22, 2012
Filing Date:
September 10, 2010
Export Citation:
Assignee:
BIG TOOL CO LTD
International Classes:
B23B51/00
Attorney, Agent or Firm:
Kazuhiro Kiyohara