9

Unigraphics Data Transfer

In This Section:

• Unigrapics Direct Connect Overview 184
• Using Unigrapics Direct Connect: Alias To Unigraphics 185
• Using Unigraphics Direct Connect: Unigraphics to Alias 195

Unigrapics Direct Connect Overview

Purpose

Alias Unigrapics Direct Connect is a stand-alone utility that allows the exchange of 3D model data between Alias and Unigraphics.

Software Requirements

• version 13 or 14 of Unigraphics

• ALIAS Designer, Studio or AutoStudio Version 9.0

Workflows

Before transferring geometry between Alias and Unigraphics , you should consider the purpose of the transfer in order to plan an appropriate workflow.

Two common workflows are:

• Geometry (describing mechanical components) is transferred from Unigraphics to Alias for concept design surfacing, then transferred back to Unigraphics.

• An Alias model is transferred to Unigraphics , and both Alias and Unigrapics Databases are developed independently. Later, the modified Alias model is transferred again to Unigraphics, replacing the Alias geometry from the first transfer. In this scenario, all work done in Unigraphics on the first Alias model transfer will affect the new, modified geometry.

There are many variations on these two examples. Whatever the transfer scenario, you should carefully plan the transfer process, to ensure that the appropriate data is written out and is useful.

Using Unigrapics Direct Connect: Alias To Unigraphics

This section describes the process of transferring an Alias model to Unigraphics:

• Creating the Unigraphics Part File in Alias on page 185

• Importing the Unigraphics Part File into Unigraphics on page 187

• Using a Sheet in Unigraphics on page 190

• Working in Unigraphics with Geometry Imported from Alias on page 191

• Summary on page 193

Creating the Unigraphics Part File in Alias

Follow these steps to create a Unigraphics part file in Alias for transfer to Unigraphics:

1

Select the object you want to export, to make it active.

2

Select File > Export > Active As-

3

The Save Active Options window appears. Select Unigraphics from the File Format menu under Basic Save Options.

If you want include data in the Attribute Information file to be included with the Unigraphics part file, select Edit Attribute Data from the Unigraphics Attribute Information window.

4

Click Save and specify the Unigraphics part file name. The file is now ready to be read into Unigraphics.

A log file documenting the conversion of the Alias wire file to the Unigraphics part file is generated and can be found in the directory where Unigraphics was started.

Importing the Unigraphics Part File into Unigraphics

The following sections describe how to import Unigraphics part files into Unigraphics, view them and prepare them to be used in downstream Unigraphics operations.

To import a 3D Alias file into Unigraphics and create useful geometry for the Unigraphics engineer, you must follow two main steps:

1

The Alias-created Unigraphics file is read into Unigraphics, where a .prt file is generated on import.

2

The model's surface geometry is converted into a sheet, depending on available data in the Alias Unigraphics file, by joining surfaces and trimmed surfaces (or faces). The skin can then be used for a variety of downstream processes in Unigraphics.

Step 1: Creating an Alias Unigraphics part file

Create the Alias Unigraphics part file as described previously in the section Creating the Unigraphics Part File in Alias on page 185.

Step 2: Creating a Unigraphics .prt file

Everything imported from the Alias Unigraphics part file will be transferred to make up the Unigraphics .prt file. Follow these steps to import the Alias Unigraphics part file into Unigraphics and create a .prt file:

1

Start the Unigraphics session.

2

When Unigraphics is running, the following window and menu areas are displayed. The main Graphics window is the area where you work with the model and its associated menus.

3

From the menu bar select File > Open. The Open Part File window appears:

4

Define the path to the directory containing the part files.

Step 3: Creating a Sheet

Before using the imported Alias-created Unigraphics part file in many of the downstream Unigraphics operations, a sheet must be generated from Unigraphics face entities.

A Unigraphics model file that has been created in Alias is made up of surfaces, curves and faces (trimmed surfaces). If, upon creation of the Unigraphics part file, the Alias user has selected to create a sheet from the Alias model, and the geometry has been exported successfully, then a Unigraphics sheet is automatically created.

Getting a Unigraphics sheet:

If the geometry in the Unigraphics part file does not describe a sheet, you can create the sheet from the imported faces.

To join faces into a Unigraphics sheet, do the following:

1

From the Toolbox menu select Feature . Select the Sew operation. At the prompt, select the target sheet by selecting one face from the set of faces you intend to use to create the sheet.

2

When prompted, select the remainder of the faces to be included in the sheet.

Eligibility for selection using Sew depends on the adjacent face's positional continuity in relation to the original face.

3

When the desired configuration of faces is highlighted, select the OK button from the option box. A sheet will be created (defined by all of the selected faces) and added to the work session in the present workspace.

Once you have created a sheet from the available geometry, you can then define the sheet as either a solid body (volume), or a sheet body.

• Solid Body - Solid features can be added to the solid part and manipulated parametrically.

• Sheet Body - Multiple surfaces or faces which have been used to create a sheet. A sheet body model can be converted to a solid body model by creating a shell from the surface model.

Using a Sheet in Unigraphics

Once the sheet has been created, it can then be used for a variety of downstream applications:

• performing Finite Element Analysis (FEA) functions

• performing moldflow analysis

• creating solid imaging (SLA) files

• creating 2D and 3D drawing sets

• generating CNC toolpaths

• passing the model back to Alias for further design iterations.

Creating a Solid

For some downstream operations (for example, FEA and the creation of 2D and 3D drawings) you may be required to create solid geometry from the Unigraphics sheet. This can be done using one of two techniques:

• assembling a series of sheets and creating a solid, or

• offsetting a sheet to create a solid.

Assembling a Solid

The skin that has been created can be "capped" to define a solid. You can then use this solid in Boolean operations.

Offsetting to Create a Solid

You can perform this operation using the Unigraphics offset functionality (Toolbox > FreeForm Feature > Thicken Sheet).

There is no guarantee that the sheet will meet all Unigraphics prerequisites for an offset. Underlying adjacent faces (and by extension, the surfaces) must not self-intersect during the offset. As well, the continuity between faces must be of a certain standard in order for Unigraphics to successfully offset the eventual sheet.

Creating a Mesh

From the sheet body or solid body the user can create a mesh which can be used for a varity of downstream operations in Unigraphics. Solid Imaging files (such as .stl) can be created from the Unigraphics sheet. Then, using the Unigraphics solid imaging functionality, the user can offset the mesh to create a solid mesh. You can then send this file to the solid imaging technology operator for creation of the physical part.

Creating a Toolpath

From the skin, you can generate a toolpath to send to a CNC milling machine. This is usually the way in which prototype tooling is analyzed.

Working in Unigraphics with Geometry Imported from Alias

The following sections describe how to verify imported geometry for use in downstream processes such as offsetting and the creation of toolpaths.

Confirming Topology Status

When the Studio-created Unigraphics part has been opened in Unigraphics, the user will want to confirm exactly what the status of the geometry is. Even though the Unigraphics user selected to have a sheet created from the Studio surfaces or shell, the actual status of the topology of the part can be confirmed in Unigraphics.

1

Select Info > Object.

2

When the Class Selection window is displayed, select the option called Type.

3

In the Select by Type window, select Sheet Body or Solid Body, depending on what you expect to be the status of the new part.

4

Move the cursor over the model in the geometry window.

As the cursor is passed over the model in the geometry window, the geometry that falls into the category of the selection, in this case Sheet Body, will be highlighted. If the geometry class that was selected does not result in any geometry being highlighted, then the new model failed to describe that topology class.

Confirming Geometry Status

To confirm that the surface geometry imported from Alias exhibits a degree of curvature that allows it to be milled or offset, use the following two evaluation tools:

• Info > Analysis > Face Analysis

• Info > Analysis > Examine Geometry

Using the Face Analysis functionality

1

Using the right mouse button select Display Mode > Face Analysis. This will enable the display of the query of the various curvature evaluations.

2

Select Info > Analysis > Face Analysis.

3

In the Face Analysis window, set the parameters you wish to investigate.

4

Select the geometry that you wish to display results of the investigation and from the Face Analysis window select Apply.

The results of the investigation will be displayed as long as you remain in the Face Analysis mode of the Display modes.

Using the Examine Geometry functionality

1

Select Info > Analysis > Examine Geometry.

The Examine Geometry window is displayed.

2

From the Examine Geometry window select the parameters you wish to investigate and select OK.

3

The Select Geometry window will be displayed. Select the geometry for which you wish to display results of the investigation and select OK.

The Information window will be displayed. The data in this window will describe the investigations selected to be carried out. Also displayed in the lower left corner of the screen will be the Highlight Results window. This window will enable you to locate where the descriptions described in the Information Window are actually located on the model.

4

Of the selections that are displayed in the Highlight Results window, select the instances of results of investigations that you wish to see highlighted in the geometry window, and select OK.

In the geometry window you can see instances where the model exhibited problems with the investigation being carried out.

You can continue to select different combinations of queries and update the display in the geometry window.

Summary

Use the following summarized list of modeling practices discussed in this section as a quick reference guide if problems arise.

Before you create the model

• Units should be set to mm.

In the Construction Settings window:

• The Rational geometry flag can be toggled OFF.

Tolerances should be set as follows:

• Curve Fit Distance =.01 mm (lower as necessary)

• Curve Fit Checkpoints = 10

• Max Gap Distance = .01 mm (this value should remain the same as Curve Fit Distance)

• Trim Curve Fit =.005 mm (lower as necessary)

While you create the model

See NURBS Modeling in Alias for a description of these tools.

• Use degree 5 curves and surfaces to achieve curvature continuity between surfaces and successful data transfer.

• Surfaces should be overbuilt and trimmed back before export.

• Fillets and other detail geometry should be deleted from the Alias model before export. Fillets and detail geometry should be built in Unigraphics to improve the success of the transfer and give you parametric control of the fillet and detail geometry while using Unigraphics.

• Models should be transferred periodically from Alias to Unigraphics during construction to manage the quality of the model being created.

• The Alias model must be successfully stitched before export, but you should also periodically stitch the geometry to ensure that the model meets all tolerance requirements.

• Avoid using Attach and Join curve since these functions create multiknots in Alias geometry that are not supported by Unigraphics.

• Avoid using Skin and Patch functions between trimmed surface boundaries, since excessive amounts of data are created in the resulting surface. If Skin and Patch are used between trim boundaries, the resulting surfaces should be checked for multiknots before export.

• Use surface building tools such as Square and Birail to ensure and control curvature continuity between surfaces.

Using Unigraphics Direct Connect: Unigraphics to Alias

This section describes the process of reading aUnigraphics file into Studio.

Creating the Unigraphics file in Unigraphics

Follow these steps to create a Unigraphics file in Unigraphics for transfer to Alias:

1

Select File > Save Part as. The Save Part File As window appears.

2

Specify the file name and select OK.

The Unigraphics part file is created.