Browse Prior Art Database

Compliancy of Dimensions with Changes to the Underlying Objects

IP.com Disclosure Number: IPCOM000105158D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 102K

Publishing Venue

IBM

Related People

Fitzgerald, WJ: AUTHOR [+3]

Abstract

The system to be described reduces the time involved in making changes to engineering drawings and preserves the integrity of the design by automatically changing the dimensions when changes are made to the model. Recently 3D CAD systems have become available and this application will be described in that environment, but it could also be described in a 2D environment as well.

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Compliancy of Dimensions with Changes to the Underlying Objects

      The system to be described reduces the time involved in making
changes to engineering drawings and preserves the integrity of the
design by automatically changing the dimensions when changes are made
to the model.  Recently 3D CAD systems have become available and this
application will be described in that environment, but it could also
be described in a 2D environment as well.

      A reduction in the time required to bring out a new product or
to bring out modifications to a product represents a significant
competitive advantage.  Major factors are the times required to
perform the mechanical design, documentation and engineering changes.

      A major part of the time consumed in these processes involves
the dimensions and associated tolerances used on these drawings.
There must be enough dimensions to be able to locate every vertex and
line on the drawing with respect to every other vertex or line on the
drawing; but there should not be extra dimensions which produce
conflicting ways of locating these vertices or lines.  Each dimension
must include a tolerance (perhaps implicitly by a default value in
the titleblock) that guarantees interchangability of parts and proper
performance of the part.  Determining these values is often the most
difficult part of the design.

      Fig. 1 shows various types of dimensions applied to an object.
Assume a change is made to the object which moves the hole in the
part and rotates the entire object (with respect to other lines in
the same view) as shown in Fig. 2.  The system automatically updates
the values in the dimensions to the center of the hole (while
retaining the tolerance), repositions the diameter dimension and
rotates all of the dimensions to accommodate the changes in the
object.

      The dimensions which comply with these changes must have
special properties.  They are associated with a matrix that defines
the horizontal and vertical directions in global space.  They are
defined relative to the dimensioned vertices and/or edges; pointers
are kept to these vertices and/or edges.  Horizontal and Vertical
dimens...