注塑成型塑料部件设计英文文献和翻译(3)
collectively referred to as the component features. The treatment
features are features acting as the treatment of other compon-
ent features, such as chamfer, fillet, and round features. These
features are defined by both their geometric and topological in-
formation from the part CAD model, as well as the relevant CAE
analysis data. They are referred to as the CAD-CAE features.
Figure 1 illustrates the integration model. The thick grey lines
show the relationships between the CAD-CAE features. The
dashed line links the part feature to its corresponding CAD
geometry, while the thin dark lines link the features to their re-
spective CAE data.
The model uses existing CAD and CAE systems as its under-
lying platforms. The part geometry data is stored in the part CAD
database, which is established by the CAD platform. ActiveX au-
tomation from the CAD system is employed for the model to
access the part geometry data as well as the operations on these
data. That is to say, the integration model only holds pointers to
the part geometry. The model can directly use the exposed func-
tionalities of the CAD system through its automation server.
The analysis data include those that are related to the overall
part, as well as those that are related to the component features
of the part. For example, part material, boundary conditions,
processing conditions, etc. are the overall CAE analysis informa-
tion. Thus, they are stored in the part feature. Suppressibility is
used to suppress a feature of the CAD model to prevent it from
being incorporated in the CAE analysis model. It is used to sim-
plify the CAE model and applies to features such as rib, boss,
hole and treatment. Wall, rib, boss (not hole) features have an
attribute of thickness.
Fig. 1. Illustration of CAD-CAE integration modelNote that depending on the underlying CAD system, the
thickness attribute may or may not be provided by the CAD sys-
tem. For example, for Solid Edge, a wall feature is defined by an
extruded protrusion feature from the system. As such, the thick-
ness may be obtained by the extrusion distance, or a dimension
of the profile that was used to define the CAD feature, depending
on how the CAD feature was created in the CAD system. Fig-
ure 2 illustrates how the wall thickness is defined depending on
the ways that the CAD geometry is created, with the thickness
in Fig. 2a defined by the extrusion distance, and the thickness in
Fig. 2b defined by one dimension of the profile.
These features also hold constraints on their respective rele-
vant attributes. For example, the desired part-quality criteria may
be defined as a constraint of the part feature, while the constraint
on the gate location on a wall feature may be defined as the con-
straint of the corresponding wall feature.
Given that such an integration model is created and fully
specified, the relevant subroutines of the underlying CAE sys-
tem can be activated to generate an analysis model (mesh) and
perform CAE analysis. The analysis results are then examined to
check whether any of the pre-defined criteria are violated. And
if more than one design satisfies all constraints, then evaluations
may be performed so that the optimal one can be selected.
3 The enhanced integration model
As has been elaborated, it is an important part of injection-
moulded-part design to modify the part shape to take account
of mouldability and other quality requirements. This section de-
scribes extensions to the CAD-CAE integration model to address
this issue. The extensions have been made to both the part feature
and the component features.
3.1 Shape modification variables
A new attribute, namely, a list of shape modification variables,
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