Effect of tool geometry and nose profile micro-deviation on surface roughness in finish turning
Loading...
Date
2015-08-01
Authors
Sung Aun Naa
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The roughness of a machined surface in finish turning is determined mainly by
the feed rate and nose edge profile of the cutting tool at the tool-workpiece interface.
The geometry of the tool-workpiece interface, in turn, is determined by the tool
geometries, such as nose radius, side cutting edge angle (SCEA), inclination angle,
rake angle and as well as the nose profile micro-deviation. In this study, the effect of
nose radius, SCEA, inclination angle, rake angle as well as the nose profile microdeviation
on surface roughness of a finished workpiece was investigated. New
analytical models for Ra and Rq by considering nose radius, SCEA and feed rate are
proposed. A simulation method to generate Rt, Ra and Rq based on the ideal (circular)
nose profile by considering the nose radius, SCEA, inclination angle, rake angle and
feed rate is proposed. Using the simulation method, the combined effect of SCEA,
inclination angle and rake angle on the surface roughness was investigated. The
simulation method was extended by using the actual nose profile obtained from an
image of the tool nose of a new cutting insert to include the effect of the nose profile
micro-deviation on surface roughness. To study the nose profile micro-deviation by
considering the effect of chatter vibration and nose wear on surface roughness,
additional input data, namely the vibration signal and image of the worn insert, were
considered in the simulation. A method to obtain the 95% roughness prediction
interval based on the simulation data is also proposed. The roughness data obtained
from the newly developed analytical models were found to agree more closely with
the experimental data compared to those obtained from the existing analytical models
that consider only nose radius and feed rate. The Ra and Rq data obtained from the
simulation method based on the ideal nose profile showed the closest agreement with
the experimental results compared to the new and existing analytical models.
Comparison of the roughness data from the simulations based on the ideal nose profile
and the actual nose profile showed the influence of the nose profile micro-deviation on
the surface roughness. Although the nose radii of the tools are within the 10%
tolerance allowed in the ISO3685 standard, from simulation the nose profile microdeviation
caused Rt, Ra and Rq to deviate as much as 42%, 27% and 29% respectively.
Based on the 95% roughness prediction interval it was found that 100%, 96% and 96%
of the Rt, Ra and Rq values, respectively, obtained experimentally fell within the
prediction interval. Using the proposed simulation method based on actual nose profile,
tool manufacturer can monitor the quality of the tool nose based on the predicted
surface roughness of the workpiece in finish turning.