Data processing: structural design – modeling – simulation – and em – Structural design
Reexamination Certificate
2000-08-16
2003-04-08
Ingberg, Todd (Department: 2123)
Data processing: structural design, modeling, simulation, and em
Structural design
C703S002000, C703S006000, C703S007000
Reexamination Certificate
active
06546362
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Filed of the Invention
This invention relates to a mold design system for designing, based on a given product shape, a shape of a mold used to manufacture molded articles, and more particularly, to a mold design system for deriving a parting line and an undercut necessary for designing such a mold shape.
2. Description of the Related Art
Process of molding plastics includes injection molding. In injection molding, a fixed quantity of a molten plastic material is injected into an injection mold to mold the plastic into shape. The plastic is thereafter removed from the mold, thus obtaining a product (including a component part etc.). When a plastic product or the like is designed, therefore, it is necessary that a mold for making the product should also be designed at the same time. Present-day product design is in most cases carried out by means of CAD (Computer Aided Design), and accordingly, molds also are designed based on CAD data of products.
A general procedure for designing a mold is as follows:
1) The direction of withdrawing a product is determined, and an undercut is checked.
2) The product is positioned relative to a mold base, and the undercut is dealt with by a slide arrangement or the like.
3) A parting line of the product is set. In this case, outer peripheral edges of the product need to be obtained as the parting line. In cases where the product has a hole therein, peripheral edges of the hole also need to be obtained as a parting line.
4) Based on the parting line thus obtained, a parting face is obtained.
5) The product part is removed from the mold base, which is then divided at the parting face.
FIG. 20
shows parting lines of a product, by way of example. A product model
100
shown in the figure is in the form of a box having a cavity therein. The box opens at its bottom and has a rectangular hole in its top face. When designing a mold base corresponding to this product model
100
, a parting line
101
for the outer peripheral portion of the box and a parting line
102
for the hole in the top face are determined. Once the parting lines are determined, parting faces of the mold base can be determined based on the parting lines.
FIG. 21
shows the parting faces of the mold base. The mold base
200
comprises at least two parts
210
and
220
positioned above and below (in Z-axis direction). The upper part
210
is called cavity-side part, and the lower part
220
is called core-side part. A parting face
201
for the outer peripheral portion is determined by the corresponding parting line
101
, and a parting face
202
for the hole is determined by the corresponding parting line
102
.
Thus, when designing a mold, how to determine the parting line is a matter of importance. In a conventional mold design system, therefore, when an edge which is to constitute the parting line is selected by the designer, edges connected with the selected edge are distinctively shown on screen, thereby assisting the work of deciding the parting line. The designer successively selects suitable edges from among those shown on screen, whereupon the parting line is determined.
FIG. 22
illustrates the method of determining a parting line in the conventional system. In the product model
100
, an edge
111
connecting points T
3
and T
2
, for example, is selected, whereupon the edges continuous with point T
2
are shown distinctively as selectable edges. In the illustrated example, an edge
112
connecting points T
2
and T
6
and an edge
113
connecting points T
2
and T
1
are distinctively shown. When a plurality of edges are shown, which edge is to be selected as the parting line is left to the designer's judgment.
However, if the product shape is complicated, the parting line is constituted by a large number of edges, and the manual selection of edges consumes much time.
Also, after the parting line is determined, it is necessary to make a check as to whether an undercut exists or not. In a conventional method of determining whether or not an undercut exists, a straight line extending in the withdrawing direction is randomly generated and a portion where the straight line intersects the product twice or more is detected. To increase the detection accuracy, an increased number of straight lines need to be generated, but this requires correspondingly prolonged time.
Thus, the conventional mold design method is associated with a problem that the decision of a parting line consumes much time and labor, imposing a heavy load on the mold designer.
SUMMARY OF THE INVENTION
Taking the above into consideration, an object of the present invention is to automate the parting line decision process, thereby improving the efficiency of mold design.
To solve the aforementioned problems, a mold design system for designing a mold for making molded articles is provided which comprises face orientation acquiring means for obtaining orientations of faces constituting a shape of an article to be produced using the mold, face classifying means for classifying the faces into a plurality of sets according to the respective orientations obtained by the face orientation acquiring means, and parting line determining means for determining, as a parting line of the mold for forming the article shape, a boundary between faces that are classified into different sets by the face classifying means.
With this mold design system, the face orientation acquiring means obtains the orientations of faces that constitute the shape of an article to be produced using the mold. Then, according to the orientations of the faces obtained by the face orientation acquiring means, the face classifying means classifies the faces into a plurality of sets. The parting line determining means determines, as the parting line of the mold for forming the article shape, a boundary between faces that are classified into different sets by the face classifying means.
REFERENCES:
patent: 09231410 (1997-05-01), None
Nee, A.Y.C., et al., “Automatic Determination of 3-D Parting Lines and Surfaces in Plastic Injection Mould Design,” CIRP ANNALS, vol. 47, No. 1(1998), pp. 95-98.
Guo Fu
Yoshikawa Tadakatsu
Fujitsu Limited
Ingberg Todd
Staas & Halsey , LLP
Thomson W
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