We all know that the Rewrap command is useful for interpolating mesh data as well as smoothing noisy data. This post continues our look at the command with a second example. The first example can be found by visiting this post.


Example #2

Autosurfacing a mesh for CAD operations: If you are creating an auto-surface of a model, it is usually said that a majority of the editing must be done to the mesh since you are creating a verbatim model. But with XOR, you have the added ability to create a hybrid model, that is, performing CAD operations on a verbatim model to create a model that has both the accuracy from the scan as well as the design intent of a designed model.

In this example, we have an autosurface of a bottom of a bottle. What if the scan of the bottom of the bottle isn’t flat? Well then our autosurface of the bottom of the bottle may not be flat either.

Using the rewrap command, we can extend the mesh in a natural way, create our autosurfaced solid model, then create a perfectly flat surface.

We can also change the height of the bottle by using a different cutting plane!

More Examples…

We’ll be posting the final example of how this command can be applied soon! If you missed the first example, check it out here!.

Generally, when you model a sheet metal body with finite thickness, you create one side and using offset command you can create the other side.

This modeling method is used to create a sheet metal body with thickness even when you have only its upper side surface. Then you can check the interference between inner side of the surface body and another part. However, if you have a surface body with some complex shape, it is not easy to create it using above mentioned method.

XOR helps you to easily convert a surface data to mesh in order to complete the inner shape from the converted mesh using offset operation. You can quickly create a surface body on the mesh using Auto Surfacing command and complete the whole shape connecting the inner and the outer surface body on the boundary of model.

Through this document, you will understand how to create a complex inner side of body from the existing design data using the Convert Body, Auto Surfacing commands.

Method

First of all, you need to prepare a mesh from the existing design data in order to apply the offset operation.
1. Go to Mesh mode and select Tools > Mesh Tools > Convert body in the menu. Click the Ok button.

The design data is converted to a mesh and the copied mesh data will be registered in the Model Tree as shown in the image below.

Now extract a curve along the boundary of upper body using Convert Entities command. Then extract a curve along the boundary of the converted mesh using Boundary command as well.

1. Go to the Mesh mode, select Tools > Mesh Tools > Offset in the menu

2. Select the Surface Method as offset method and input a thickness value in the Distance box

3. Choose offset direction using Flip button so that it is offset to the inside of the part

Note
You can choose offset direction by just clicking the (Flip) button. If you want to turn over the current direction to the opposite direction, click the Flip button and the copied mesh will be offset along the selected direction. Also if you click this button again, the offset direction will be reversed again.

4. Go to the 3D Mesh Sketch mode, or select Tools > 3D Sketch Entities > Boundary in the menu

5. Select the option Interactively-Split Curve Segments From Single Boundary and select an edge as Boundary. Then pick nodes to create partial boundary curves as shown in the image below

6. Go to the 3D Sketch mode, or select Tools > 3D Sketch Tools > Convert Entities in the menu

7. Extract a curve along the boundary of upper body using Convert Entities command as shown in the image below

8. Try to merge between the split splines using Merge command

Finally, connect the curves that are extracted from the upper side of body and the inner side of mesh using the Surface Loft command. You can also easily and quickly create an inner side of body from the mesh using Auto Surfacing command.

1. Try to execute the Surface Loft command. Click the Surface Loft button in the main toolbar

2. Select two sketch chains as Profiles and click the OK button

3. You can also create other lofting surfaces by the same way as shown in the image below

4. Try to apply Auto Surfacing command to the offset mesh. Click the Auto Surfacing button in the main toolbar

5. Select the mesh and set the value for No. Of Surfaces as shown in the image below

A surface body will be created on the offset mesh as shown in the image below

6. Try to execute the Sew command. Click the Sew button in the main toolbar

7. Select all surface bodies and click the next button

8. Click the OK button. The split boundaries of the surface bodies are sewed. Then you will get a solid model which has thickness as shown in the image below.

Rapidform XOR/XOS can create a body on a mesh using “Auto Surfacing” command. This method can quickly and automatically wrap the mesh and create a surface/solid body with just one click of a button, but it might be possible for gaps to be created between patches on complicated and sharp areas of a mesh. So in such cases if you want to export the created model from XOR/XOS to other CAD system such as CATIA, UGS NX or PRO/E Wildfire, you need to perform additional processes to heal the gaps after transferring to other CAD system.

This technical tip is useful when you export a surface / solid body as neutral format (IGES or STEP) into CATIA to create a complete watertight solid model.

As you see the model tree as shown in the image above, the patches are broken after importing a body into CATIA. If you want to create a complete body, you need to use healing Process in CATIA such as heal and join in Healing Assistant.

Method

This method is used in the Healing Assistant Workbench or Part Design Workbench. If created model has many patches and curves, this model has highly possibility of error occurrence. Therefore it needs to be healed for broken patches.

In Assistant Workbench
1. Click Start > Mechanical Design > Healing Assistant in the menu and click the (Heal) button in the Tool bar. Select all imported surfaces and click OK button as shown in the image below. If CATIA cannot heal some edges, these edges are displayed in green. In that case, increase the tolerance value little by little (max. 0.1) and try to heal again.

Note
The Heal command improves surface connection condition. If adjacent surfaces are completely connected and closed within the given allowable tolerance, then you can skip this stage.

Note
If you skip the above healing process, you can create a combined body by clicking the (Join) button in the tool bar as shown in the image below. Click the OK button.

In Part Design Workbench
1. Click the Start > Mechanical Design > Part Design in the menu and click the (Close Surface) button in the Tool bar and select the joined body in the Model Tree as shown in the image below. Click the OK button.

2. This command transfers the surface body to a solid body and registers it in the model tree. Finally, you will obtain a Closed Solid body.

This technical tip is useful when you export a surface or solid body as a neutral format (IGES or STEP) into CATIA to create a complete, watertight solid model.

As you can see in the model tree as shown in the image above, the patches are broken after importing a body into CATIA. If you want to create a complete body, you need to use healing processes in CATIA, such as heal and join in the Healing Assistant.

Method:
This method is used in the Healing Assistant Workbench or Part Design Workbench. If the model has many patches and curves, it has a higher probability of producing errors. Therefore, it needs to be healed for broken patches.

In the Assistant Workbench:
1. Click Start > Mechanical Design > Healing Assistant in the menu, and click the “Heal” button in the toolbar. Select all imported surfaces and click the OK button, as shown in the image below. If CATIA cannot heal some edges, these edges are displayed in green. In that case, increase the tolerance value little by little (max. 0.1), and try to heal again.

Note
The Heal command improves surface connecting conditions. If surface connections are completely closed within the allowable tolerance, you can skip this stage.

Note
If you skip above the healing process, you can create a combined body by clicking the “Join” button in the tool bar as shown in the image below. Click the OK button.

In the Part Design Workbench:
1. Click Start > Mechanical Design > Part Design in the menu, and click the “Close Surface” button in the toolbar. Select the joined body in the model tree, as shown in the below image. Click the OK button.

2. This command converts the surface body to a solid body and registers it in the model tree. Finally, you will have created a closed solid body.

Objective:

This example primarily focuses on how to autosurface a part. one of the quickest way to get NURBS from a mesh data. The airbag part is first aligned using interactive alignment method and then autosurfaced to get NURBS as displayed in the image above.

Pre-requisites:

Align

Estimated Time:

30 minutes

Files Available for Download:

File Name:	File Type:	Size
Autosurfacing.pdf Autosurfacing.stl Autosurfacing.avi	Pdf Document Mesh File Video	0.66 MB 3.08 MB 95.5 MB