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Ch23-I044963.fm Page 109 Tuesday, August 1, 2006 9:09 PM
1, 2006
Tuesday, August
Page 109
9:09 PM
Ch23-I044963.fm
109
109
DETECTION OF UNCUT REGIONS IN POCKET MACHINING

1
1
Manseung Seo , Haeryung Kim and Masahiko Onosato 2
1
Department of Robot System Engineering, College of Engineering, Tongmyong University,
535 Yongdang-dong, Nam-gu, Busan 608-711, Korea
Graduate School of Information Science and Technology, Hokkaido University,
Kita-14, Nishi-9, Kita-ku, Sapporo, Hokkaido 060-0814, Japan

ABSTRACT

Upon realization of the fact that uncut regions exist if there is an intersection between a previous tool
envelope and a current tool envelope, this study is initiated. As a key concept, the Tool envelope Loop
Entity (TLE) is devised to treat every trajectory made by the tool radius as an ordinary offset loop. The
TLE concept enables the offset curve generation method to be extended further as a distinctive method
in which uncut region detection is done through an identical way of offsetting. To ensure the method
works, a prototype system is implemented and evaluated with the tool path generation obviating uncut
regions. The result verifies that the proposed method fulfils technological requirements for uncut free
pocketing.

KEYWORDS

Pocket, Offset, Offset Loops, Uncut Region, Clean up Curve, Tool Path.

INTRODUCTION

It is not easy to find an efficient method for tool path generation free from uncut regions. In the
literature, to solve uncut problems, Held et al. (1994) employed a specific adjustment on successive
offset distance through the Voronoi diagram approach and Park & Choi (2001) took local care on tool
trajectories through the pair-wise intersection approach. Recently, for offset curve generation, Seo et al.
(2004) proposed the Offset-loop Dissection Method (ODM) based on the Offset Loop Entity (OLE)
concept, which enables the method to be implemented easily into the system at any condition,
regardless of the number of offsets, the number of intersections, and even the number of islands.
Recognizing the robustness and flexibility of the ODM and realizing the fact that uncut regions exist if
there is an intersection between a previous tool envelope and a current tool envelope, we extend the
ODM to uncut region detection. For the adoption of the ODM, we define the Tool envelope Loop