注塑成型塑料部件设计英文文献和翻译(8)

of the speciﬁed evaluation criteria is then selected and reported.
All these tasks are performed automatically as well.And since the
shapemodiﬁcation variables are included in the enhanced integra-
tion model, the system will be able to modify the part geometry
automatically and in a uniformway, regardless ofwhich feature or
features or overall part thickness are to be modiﬁed.
5 Case study
The ﬁrst design case is a part with its initial shape shown in
Fig. 4. The CAD model was created interactively by using the501
modelling tools provided by Solid Edge. A circle sketch was also
created which is used by the CAD-CAE integration model as the
injection location. Using the tools provided by the implemented
software prototype, the designers can then specify analysis infor-
mation, including:
• Part material:
– Type: PP (Polypropylene);
– Manufacturer: Borealis [BOREALIS];
– Trade name: P170CC [ST111].
• Boundary condition: the injection location is deﬁned by the
centre of the circle sketch shown in Fig. 4.
• Moulding conditions:
– Melt temperature: 250 ◦C;
– Mould temperature: 40 ◦C;
– Injection time: 1.8s.
• Criteria construction variables:
– v1 = maximum shear stress (MPa);
– v2 = uniform end-of-ﬁll temperature (SD).
• Evaluation criteria:
– v1(0.5);
– v2(0.5).
It is assumed that the designer wishes to modify the hole lo-
cation on its proﬁle face so that the two speciﬁed criteria may
attain optimal values, or that the weighted objective function will
be minimized. Thus, by using the user interface shown in Fig. 6,
the attribute “shape modiﬁcation variables” of the enhanced in-
tegration model is assigned with the two positional modiﬁcation
variables of the hole feature, namely, the 2D coordinates of the
centre of the circle on the hole’s proﬁle face.
In this example, the origin of the 2D coordinates is the initial
position of the hole feature. The intended region of variation for
the hole location is a rectangle, as is shown in Fig. 8. The hole
feature at the four extreme corner positions of the rectangle is
also shown.Since the part shape is symmetrical, and the injection loca-
tion is also speciﬁed on the symmetrical plane (Fig. 6), we may
only vary the hole location over half of this region. The values of
the two modiﬁcation variables are thus assigned as (all units are
in millimetres):
• X coordinate:
– Starting: −30;
– Ending: 30;
– Step: 4.
• Y coordinate:
– Starting: −20;
– Ending: 0;
– Step: 4.
There are in total 16×6 = 96 iterations. The actual time
taken depends on how reﬁned the mesh model is and the com-
puter used. It can range from over one hour to several hours on
a Pentium III PC. The values of the weighted objective function
from the analysis results are also calculated.
Figure 9 shows the contour chart of the weighted objective
function values. In terms of the speciﬁed evaluation criteria, the
low objective function values (0 – 0.2) happen at a number of
places, which are mostly along the symmetrical line of the hole’s
proﬁle face, namely, when the modiﬁcation variable Y coordi-
nate = 0. The system reported that the optimal hole location is:
• X coordinate = 2,
• Y coordinate = 0,
which is quite close to the original hole position.
If the injection location was not assigned at the symmetrical
plane of the part, then the whole region of variation should be
used. In the following, we discuss this as another case study: the 注塑成型塑料部件设计英文文献和翻译(8):http://www.751com.cn/fanyi/lunwen_759.html