Core & Cavity Modeling in Pro-Engineer.

USEFUL FOR COMPLEX MOLDED PARTS

  • Approaches part modeling from a tooling perspective.
  •     Uses 3 basic parts to create a final product
  •         Core – the male part of a mold
  •         Cavity – the female part of a mold
  •         Part Body – the solid that the core and cavity act upon
  •     This approach simplifies modeling irregular and complex geometries

DEFAULT COORDINATE SYSTEM DEFINES THE GLOBAL ZERO

  • This is necessary when using the “Design in Place” approach.
  •     All major components have the same Zero
  •     Assembly placement is within parts by the relationship between the geometry and the Zero
  •         Global Zero is not used for:
  •         Assemblies that rely on constraints
  •     Components shared between multiple assemblies, for instance screws

PART COORDINATE SYSTEM DEFINES THE LOCAL ZERO

  • Create a Local Zero Coordinate System
  •         Defined by the Global Zero
  •         Defines the position of geometry to Global Zero
  •         May be offset or rotated
  •         Define axis directions based on project conventions
  •     Create Local Datum Planes
  •         Based on Local Zero Coordinate System
  •         Base of all part geometry
  •         Name them after the axis that define them
  •     Alternate Approach
  •         Use skeleton geometry to define and control the part coordinate system and planes from the parent assembly

USE ONLY THE LOCAL DATUM PLANES

  •     HIDE THE GLOBAL DATUMS, FRONT, TOP, & RIGHT AND THE COORDINATE SYSTEM IN THE LAYERS AND SAVE THAT STATUS.
  •     DO NOT CREATE ANY LINKS TO GLOBAL DATUMS OR COORDINATE SYSTEMS!

DEFINE REFERENCE GEOMETRY FOR THE PART

  •     Points, Datum Planes, and Axis in Addition to the Local Zero features
  •         Define major features of the part
  •             Parting lines
  •             Screw boss levels and locations
  •             Interfaces to other parts
  •             Screen center
  •     Alternate Approach
  •         Use skeleton geometry to define and control the part coordinate system and planes from the parent assembly

CORE PART START

  •     Extrude a block from the parting line
  •     Make the block bigger than the final part will be
  •     Add the basic internal shape of the part to the block on the parting line side

CORE PART DETAILS

  •     Add draft and rounds to features as you go
  •     The earlier they are added, the better the chance of them working properly

CREATE COMPLEX FEATURES AS SEPARATE PARTS

Designing as a separate part has many advantages:

  •     Drafts and rounds are performed on a simpler part and are more likely to work
  •     Common features like bosses and snaps are easier to reuse in different parts
  •     It is easier to swap out or remove a feature from the part model
  •     Interactions between the feature and complex surfaces on the part are not part of the modeling process
  •     The resulting part model tree is much cleaner and easier to understand

ADD SECONDARY FEATURES TO CORE PART

  •     Cut the secondary features from the core part
  •     Add rounds and drafts to surfaces created by this operation

FINISH ADDING FEATURES TO THE CORE

  •     Cut features like ribs past the outside of the core
  •         This will ensure that they conform with the contours of the housing without relying on complex surface operations or rib commands
  •     When the core is complete, create a publish geometry feature of the solid surfaces

CUT THE CORE FROM THE PART

  •     The part is a separate model
  •         It starts out with a base block, just like the core did
  •         Make the block slightly larger than the desired part in all directions
  •     Use the cutout from other model feature
  •         Select the publish geometry feature from the core as the cutter
  •     Add any features that rely on surfaces resulting from the cutting operation

CUT THE CAVITY FROM THE PART

  •     Create the Cavity Part with the same techniques as the core part
  •         The cavity base block extrudes to the opposite side of the parting line from the core
  •     Separate features between the core and cavity based on their draft direction
  •     Add any finishing features

 

WORKING WITH MULTI-PART MODELS

  •     In order to modify a subpart it must be in either the working directory or the path
  •     To change a subpart such as the core, right click on it in the model tree and select open base
  •     The main part must be regenerated before the changes to a subpart will appear
  •     In order to create a copy of a part in another location, open the part and all subparts and use the backup command