Model Based Simulation of Broaching Operation: Cutting Mechanics, Surface Integrity, and Process Optimization

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.

Year	Entry
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2003	Rincón Kohli L. Identification of a Multiaxial Failure Criterion for Human Trabecular Bone [PhD thesis]. Lausanne, Switzerland: École Polytechnique Fédérale de Lausanne; 2003.
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Year

Entry

1998

Silva MJ, Keaveny TM, Hayes WC. Computed tomography-based finite element analysis predicts failure loads and fracture patterns for vertebral sections. J Orthop Res. May 1998;16(3):300-308.

1985

Cann CE, Genant HK, Kolb FO, Ettinger B. Quantitative computed tomography for prediction of vertebral fracture risk. Bone. 1985;6(1):1-7.

2009

Rincón-Kohli L, Zysset PK. Multi-axial mechanical properties of human trabecular bone. Biomech Model Mechanobiol. June 2009;8(3):195-208.

1997

Silva MJ, Gibson LJ. Modeling the mechanical behavior of vertebral trabecular bone: effects of age-related changes in microstructure. Bone. 1997;21(2):191-199.

2003

Rincón Kohli L. Identification of a Multiaxial Failure Criterion for Human Trabecular Bone [PhD thesis]. Lausanne, Switzerland: École Polytechnique Fédérale de Lausanne; 2003.