Model based simulation of broaching operation: cutting mechanics, surface integrity, and process optimization
Date
2013-04-01
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Abstract
Machining operations are widely used to produce parts with different shapes
and complicated profiles. As a machining operation, broaching is commonly used
for the machining of a broad range of complex internal and external profiles either
circular or non-circular such as holes, keyways, guide ways, and slots on turbine
discs having fir-tree shape. Broaching is performed by pushing or pulling a tapered
tool through the workpiece to remove the unwanted material and produce the
required profile. Broaching is also acknowledged because of its high productivity
and attainable surface quality in comparison to the other machining processes.
The objective of this thesis is to simulate the broaching operation and use the
results to present a methodology for optimum design of the broaching tools. In the
course of the presented thesis, a new B-spline based geometric model is developed
for broaching cutting edges followed by model validation using 3D ACIS modeller.
To study the mechanics of cutting and generated cutting forces during
broaching operation, an energy based force model is presented which can predict
the cutting forces based on the power spent in the cutting system. An experimental
investigation is conducted in order to confirm the estimated forces.
The integrity of the broached surface is also investigated by focusing on
surface roughness, subsurface microhardness, and subsurface microstructure as
three major parameters of surface integrity.
An optimization procedure for broaching tools design is presented in this
thesis. A mathematical representation of broaching tooth geometry is also
presented which is used to simulate the tooth as a cantilevered beam subjected to
a distributed load. The beam is solved considering the given design constraints to
achieve optimum geometric parameters for maximum durability and performance.
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Keywords
Broaching operation, Tool design, Surface integrity, Optimization, Solid modelling