The International Journal of Advanced Manufacturing Technology (2018) 97:3751–3760
https://doi.org/10.1007/s00170-018-2221-5
ORIGINAL ARTICLE
Model-based analysis in finish broaching of inconel 718
Martin Seimann
1
· Bingxiao Peng
1
· Andreas Fischersworring-Bunk
2
· Stefan Rauch
1
· Fritz Klocke
1
·
Benjamin D
¨
obbeler
1
Received: 3 April 2018 / Accepted: 17 May 2018 / Published online: 30 May 2018
© Springer-Verlag London Ltd., part of Springer Nature 2018
Abstract
Broaching is still state of the art for manufacturing profiled slots in turbine discs. The broaching processes can be divided
into roughing, semi-finishing, and finishing. The functionality of the manufactured slot is mainly determined by the finishing
process with regard to the groove geometry and the surface integrity. Since the broaching tool is in contact with the entire
fir tree slot in the finishing process, the highest process forces are expected in finishing and semi-finishing. In case of
dedicate geometries, the high process forces can lead to the deformation of work piece material, and thus to geometrical
inaccuracies. The process and tool design in turbine discs broaching processes are based mainly on experiences. Therefore,
the new process and tool design are time- and cost-consuming by means of experiences-based design, for example, by
implementation of new cutting material, such as carbide broaching tool. To predict the process forces in dependence on the
slot geometry in broaching process, an analytical force model and a FEM model with coupled Eulerian-Lagrangian(CEL)
formulation are introduced in this work. The investigated parameter range is based on the typical range for broaching with
high speed steel for v
c
= 2.5 to 5 m/min, rise per tooth h = 0.02 mm. By means of the new model based approach, the
broaching process and tools can be designed and optimized on the model level.
Keywords Broaching · Inconel 718 · FEM simulation · Cutting force
1 Introduction
The manufacturing of parts with high accuracy requires
high surface quality and process reliability, especially in
the automotive and aerospace industry. For this reason,
broaching is still state of the art for manufacturing profiled
slots in turbine discs. Apart from that, the work piece
materials in the aerospace sector are very demanding [7,
19, 20, 24]. Due to the high toughness, the process stability
and low material costs compared to cemented carbide [38],
high speed steel (HSS) is widely used as tool material for
many broaching applications. However, the usage of HSS
results in low cutting speeds compared to other machining
processes. During broaching of high-strength materials,
Martin Seimann
m.seimann@wzl.rwth-aachen.de
1
Laboratory for Machine Tools and Production Engineering
(WZL), RWTH Aachen University, Steinbachstrasse 19,
52074 Aachen, Germany
1
MTU Aero Engines AG, Dachauer Str. 665,
80995 M
¨
unchen, Germany
such as Inconel 718, a high thermo-mechanical load affects
the tool and the workpiece surface [3, 26, 35]. Part of
the effects could be investigated in fundamental cutting
tests, but these tests always represent a simplification [9,
18]. These simplifications are necessary, because of the
measurement for the specific process forces in all directions
being still not possible with a dynamometer for a complex
broach profile. This applies in particular to the normal force,
which always acts orthogonally to the cutting edge. Thus,
the process and tool design in broaching process are mainly
based on experiences. This paper presents an new approach
to determine the cutting force and cutting normal force in
broaching process of a complex tool profile by an analytical
model and a FEM model, which is normally underrated in
the FEM simulations for metal cutting [40]. By means of
this approach, the process and tool design of broaching can
be performed on the model level.
1.1 Process force models in broaching
Due to many aspects, the knowledge of the process forces
is of crucial importance for broaching. Compared to other
cutting processes like turning, milling, or drilling, process
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