10 Tube Hydro-Forming Process Design Based …
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components: a case base for retrieving similar previous similar cases, reusing the
solution for the new problem, revising the feasibility of the solution in this case and
incorporating the solution into case base as a existed one for future problems [5].
Tor [6] represented a CBR approach with a new indexing and retrieval strategy for
stamping die design. a feature relation graph representation scheme used for retrieval
mechanism, w. A dual-step similarity analysis was proposed to shorten down the
search time, and it performed well in multi-stage non-axisymmetric deep drawing
[7]. Tsai [8] utilized the CBR methodology to plan stamping process and design
stamping dies for automotive panels reusing existing designs to develop new designs.
With the discussion mentioned above, however, few similar attempts have been made
for the tube hydro-forming process planning. This paper is mainly concerned about:
(1) a tube hydro-forming process design method with a KBE system using CBR; (2)
a feature representation of tubular part; (3) using the self-organized map algorithm
for CBR; (4) data preprocessing method for case retrieval; (5) and a case study to
verify the effectiveness of this methodology.
10.2 Feature-Based Tube Hydro-Forming Process Design
The principal objectives of a KBE system are to solve a particular problem by reusing
experience and knowledge in a flexible way meanwhile retain the new ones for future
problems. In tube hydro-forming domain, the proposed KBE attempts to become an
essential tool for improving design effectiveness and guiding the design engineers.
The schematic diagram of it can be found in Fig. 10.2.
In a complete process sequence of tube hydro-forming, it contains bending,
crushing, pre-forming, hydro-forming and calibrating as well as several minor intermediate and complementary operations [9]. Pre-forming is necessary when processes
cannot be formed safely without preliminary operations which is most important in
process planning. Especially, when the outer dimeter of the initial tubular blank is
larger than the die allowance, there should be a crushing process. So that the blank
can be loaded into the die cavity and the pinch must be avoided [10], seeing Fig. 10.3.
Accordingly, although bending and calibrating relate to the final part geometry,
they are not very critical. Bending operations can be determined on the number
and severity on the centerline. If there are mild bends that lie on a vertical plane
or fall within expanded area, the hydro-forming process can make them formed in
one step. Calibrating process is the foundation of fittability to the cavity surface and
the pressure mainly depends on the smallest fillet radius on the part, as defined in
Eq. (10.1) [11]:
p cal =
2
√
3
t i σ b
RC min − t i
2
(10.1)
117
components: a case base for retrieving similar previous similar cases, reusing the
solution for the new problem, revising the feasibility of the solution in this case and
incorporating the solution into case base as a existed one for future problems [5].
Tor [6] represented a CBR approach with a new indexing and retrieval strategy for
stamping die design. a feature relation graph representation scheme used for retrieval
mechanism, w. A dual-step similarity analysis was proposed to shorten down the
search time, and it performed well in multi-stage non-axisymmetric deep drawing
[7]. Tsai [8] utilized the CBR methodology to plan stamping process and design
stamping dies for automotive panels reusing existing designs to develop new designs.
With the discussion mentioned above, however, few similar attempts have been made
for the tube hydro-forming process planning. This paper is mainly concerned about:
(1) a tube hydro-forming process design method with a KBE system using CBR; (2)
a feature representation of tubular part; (3) using the self-organized map algorithm
for CBR; (4) data preprocessing method for case retrieval; (5) and a case study to
verify the effectiveness of this methodology.
10.2 Feature-Based Tube Hydro-Forming Process Design
The principal objectives of a KBE system are to solve a particular problem by reusing
experience and knowledge in a flexible way meanwhile retain the new ones for future
problems. In tube hydro-forming domain, the proposed KBE attempts to become an
essential tool for improving design effectiveness and guiding the design engineers.
The schematic diagram of it can be found in Fig. 10.2.
In a complete process sequence of tube hydro-forming, it contains bending,
crushing, pre-forming, hydro-forming and calibrating as well as several minor intermediate and complementary operations [9]. Pre-forming is necessary when processes
cannot be formed safely without preliminary operations which is most important in
process planning. Especially, when the outer dimeter of the initial tubular blank is
larger than the die allowance, there should be a crushing process. So that the blank
can be loaded into the die cavity and the pinch must be avoided [10], seeing Fig. 10.3.
Accordingly, although bending and calibrating relate to the final part geometry,
they are not very critical. Bending operations can be determined on the number
and severity on the centerline. If there are mild bends that lie on a vertical plane
or fall within expanded area, the hydro-forming process can make them formed in
one step. Calibrating process is the foundation of fittability to the cavity surface and
the pressure mainly depends on the smallest fillet radius on the part, as defined in
Eq. (10.1) [11]:
p cal =
2
√
3
t i σ b
RC min − t i
2
(10.1)