Challenge

Week 10 - Challenge 2- Attachment Feature Creation (Dog House)

VV.Balasekar V3 Jul 2023

DESIGN

OBJECTIVE

To design dog house for the Door Trim as per automotive industry Standard.
Create tooling axis for the given CLASS-A surface.
Create B Class and C Class surfaces.
Create final surface model and convert it into solid body using close surface command in the part design workbench.
Create Side core tooling axis for the dog house.
Perform draft analysis for Class-A surface , Final part body and dog house .

DESIGN METHODOLOGY

Skin data would be provided to us by the styling team.
Class-A surface means visible surface. It gives the aesthetic of the component which is created by the styling team and gives to the part design engineer to create the part with all engineering aspects.

The first step is to check the continuity of the class A surface. This is to ensure that there is no gap between surfaces. If we find any then we should fix that first.
Class-A continuity check.
Analyse the class A surface through visual inspection.
To make sure that the given surface has no gap in between them. We can check it also with the help of Join or boundary commands.

Procedure for creating the tooling axis

Tooling axis represents the opening and closing of the mold core and cavity during the manufacturing of the components. A plastic product designer should consider the best tooling direction to cutdown the cost of the component very less.

Method opted for creating tooling axis for the door handle

Check the best tooling direction for the given surface.
We can find out the best tooling direction by cross checking all the three axes.

Here we can find out that the best tooling direction for the pumper class-A surface is along Y-axis direction.

Creating tooling axis

We should create a Dummy tooling axis first by creating point and line.

Select the curve in existing class A surface and create a dummy tooling axis for reference.Highlighted pink colour is tooling axis.

Draft analysis for the given CLASS-A surface

The Draft Analysis is a command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on colour ranges identifying zones on the analysed element where the deviation from the draft direction at any point, corresponds to specified values.

Draft analysis is done after determining the tooling axis, draft analysis is used to check whether the minimum draft (3 degrees) is maintained or not.

Procedure for performing the draft analysis are as follows
Change the view mode of the component to be in customized parameter mode and then select the shading mode as materials.
Then open the featured draft analysis tool from the insert menu.
Then click on use the compass to define the current drafting direction without activation the compass and then activate the compass in the dialogue box drag and align the compass on the Tooling axis.

Then lock the draft direction and perform draft analysis by clicking on the component
The green colour shows the positive daft tooling direction and the given surface passes the draft analysis.
Click on the analysis under the running point to check the draft analysis on the individual faces. It shows how much draft on specific points when we move the cursor point.

SURFACE-B CREATION

Class-B surface means thickness of a part it is not visible and is inside part. In other words, Class-B surface is a surface below a certain thickness from the class-A surface. This is the surface that contains engineering aspects of a model.

Offset the class-A surface to 2.5mm inward direction.
After offset ,There will be some open patches in the fillet area ,Found an open patches as shown in below images.

Procedure for rework on the patches and discontinuity of the offset surfaces using the features like Boundary, extract, multi-extract,extrapolate,Trim and edge fillet.

Working on first patch

First extract the surfaces and extropolate the surface and trim the two elements to make corner

After trim

Working on bottom and side wall patches

Extract the surfaces,untrim, extropolate the surface and trim the elements to make corner.

After trim

Working on vertical wall patches

Extract the surfaces,Split ,untrim, extropolate the surface and trim the elements to make corner.

After trim of top,bottom and vertical wall

Joining the bucket surface from offseted surface to bottom surface

Multiple extract and split the surface

Extrapolate the bucket surface and trim

Final trim surface

Applying fillet radius

To find the radius ,the radius surface has been extracted and untrimmed from the class A surface and thus radius value is obtained by measuring tools.

Finally, the required corners have been filleted by even wall thickness to avoid the mould flow marks.

B-Surface

To ensure the continuity of the Class-B surfaces check the boundary command to find out the boundary.
Hence class-B surface creation is done.

Creation of C Surface

Surface that joins class-A and class-B surfaces is class-C surface. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled
Since it is a complex class-A surface with several sharp corneres, we cannot simply create the class-A boundary curve and sweep it at one shot.
Hence, we need to create smaller boundary and then create sweep,Multi section surface.
If the surface is perpendicular to the tooling axis we have to provide 3 degree draft with reference to the tooling direction.

The surface which is parrallel to the tooling axis we have to provide 90 degree with reference to the surface option.

Use Multi surface command to close the gap between the two elements

Final part of C surface

After sweep creation we have to extrpolate and trim the sharp corners to make it into single trim.

Creating the final surface of Door Trim

First step is to join the CLASS-A surface with CLASS-C surface.

Then Trim the Joined surface with CLASS-B surface to achieve the final Door handle surface.

Go to the part design work bench and using the close surface command create the door handle solid part body

Creating Dog House on B Surface

Dog houses are designed to avoid Sink marks created on the CLASS-A surface by screw bosses and to solve the length issues when giving screw bosses which need to be assembled to other components. It is also useful when perpendicular screw bosses are required on the part of the tooling direction.

The dog house is an engineering feature used in the plastic trim design. Dog houses are used as supporting features. Sometimes other engineering features like snaps, locators, etc. are mounded on them to increase their strength. Dog house and other engineering Features are built on B-surface.