Week 8 - Challenge 5 - Door Trim Lower

OBJECTIVE:

To create the Door Trim Lower's Plastic Component using the Class A Surface that is provided. Desired Thickness of the Plastic Component is 2.5mm with 3.2 degrees as the Draft Angle.

First, we have to create the required Tooling-Axis for the given Class A Surface while meeting the requirements of the necessary Draft Angle & then perform the Draft-Analysis Operation on the Class A Surface itself.

After that, we have to create the required Class B & Class C Surfaces using which we have to make the Final Plastic Component and perform Draft Analysis on it as well.

INTRODUCTION:

CLASS A SURFACE:

Types of Surfaces and their importance for an Automotive Plastic Designer:

• Class A Surface: Class A is an aesthetic surface with the highest quality finish. Most Class A Surfaces for an Automotive Component are made using 'Autodesk-Alias' based on the final Concept-Sketch. All Class A surfaces should have 'Curvature-Continuity', meaning the continuity between the surfaces should share the same boundary. It is taken as a reference by the Automotive Plastic Designer to create 'Class B' and 'Class C' Surfaces.
• Class B Surface: The Class B Surface resides below the Class A Surface at a certain thickness. It is created using Engineering Principles that consist of all the necessary features such as Ribs, Bosses, Snaps, etc. This surface isn't visible to the observer from the outside.
• Class C Surface: The Class C Surface is the surface created between the Class A and Class B surfaces to join them.

Now, we will begin by checking the State of Connectivity for the Class A Surface and ensure that there are no gaps between the surfaces as all the surfaces should be joined well together with each other and shouldn't consist of any discontinuities between them.

By using the 'Boundary' Command' from the Operations Toolbar:

In this case, we have to click on the 'Boundary' command and then select the Class-A Surface. After that, we'll click on the 'Preview' button to highlight all the boundaries that are on the Class-A surface and check if there are any internal boundaries other than the outer edge boundaries.

In our case, there are two boundaries present on the Class-A Surface one of which is the Outer-Edge Boundary & the other is the Inner Hole-Boundary. Hence, we can conclude that all the surfaces are well connected.

TOOLING DIRECTION:

From y axis tool is cleared,So the tooling axis is created with line command along y axis

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CONSTRUCTION OF THE CLASS B SURFACE:

We'll start the procedure by creating an offset for the entire Class A Surface at a distance of 2.5mm as that is the desired thickness for our final plastic component.
As this is a complex surface hence the offset will fail to offset every element according to our necessity. It'll select some sub-elements that belong to the filleted regions by themselves that we have to remove to get the rest of the surface that is offset.

This warning will be shown when we'll try to offset the Class A Surface.

These 'Sub-Elements' will get selected by themselves to be removed if we want to obtain the rest of the offset surface.

In the above image, CATIA is showing us the filleted regions where these sub-elements are located that are going to be removed after the offset operation.

To fix all these Patches, we will use the JOIN command in which uncheck the CHECK CONNEXIVITY and in SUB-ELEMENTS TO REMOVE option we will select the filleted surface to remove and click OK. We will do the same for all PATCHES REGION.

After removing the filleted surface, we will disassemble the surface body by using the DISASSEMBLE command. Once the 2 surface domain created we will create the BOUNDARY curve for both surfaces.

After creating the boundary curves, we will use EXTRAPOLATE command to extend the surfaces till the intersection then we will use the TRIM command to remove the extra surfaces and they will be joined together automatically.

The same procedure is followed for all REGION PATCHES, and the final result is below with no PATCH REGION.

PROCEDURE TO CREATE THE CLASS C SURFACE:

We'll create the Class C Surface with respect to the Class A Surface and provide draft angles to those surfaces that are parallel to the Main Tooling Axis. Surfaces at the bottom won't be needing any draft angle as they'll get cleared by the core itself. To create the Class C Surface we have to use various commands such as Sweep with Reference Surface and With Draft-Direction depending upon the necessity and at places where it'll be difficult for us to create a surface using Sweep, we'll use Multi-Sections Surface to create those surfaces.

We've to create two Class C Surfaces, one is for the outer surfaces and the other is for the holed region inside the component and both of them are shown below:

A) Outer Class C Surface:

B) Inner Class C Surface:

Now, we're going to Join the Class A Surface with both inner and outer Class C SurfacesAfter that, we've to trim these joined surfaces with the Class B Surface but before that, we'll create an intersection between these two surfaces and see whether they're feasible to be trimmed with one another. We'll extrapolate those regions where they aren't intersecting and use the intersection command again to inspect whether the intersection is successful or not. When we'll obtain a complete intersection between these two surfaces we'll trim them together to obtain the final closed body

FINAL SURFACE BODY:

Finally, we'll go to the Part Workbench and use the option 'Closed Surface' from the 'Surface-based Features' toolbar to convert the final trimmed body into a solid body as shown below:

FINAL SOLID BODY:

After that, we’ll perform a Draft Analysis on the Final Part in Part Workbench.

Draft analysis

Tree Structure