Week 10 - Challenge 2- Attachment Feature Creation (Dog House)
AIM
Create the Dog House for the door trim considering the design rule.
INTRODUCTION
DOG HOUSE
Dog house is an engineering feature used in plastic design. Dog house are used as support features. Sometimes other engineering features like snaps, locators, and screw bosses are mounted on them to increase their strength.
Dog surface are subjected to draft analysis to prevent breakage of the component during ejection from the mold cavity. Dog house and other engineering components are built on B-surface.
OBJECTIVE
- Create a Tooling axis for the given Class A surface.
- Create the Class B and C surfaces of door trim using the given Class A-surface.
- Create the final surface model and convert it into a solid body using the close surface command in the part design workbench.
- Create a side core axis for the dog house.
- Create a Dog house on the B surface by considering the design rule.
- Perform draft analysis for both Class A and the final part body.
Design Methodology
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.
Given Class A-surface.
Check for the continuity of the given surface using Join Boundary commands.
If there is no gap then proceed to create the Tooling Axis.
TOOLING AXIS
Procedure for the Tooling Axis Creation
Check the best possible tooling direction by manually adjusting the compass.
By analysing it is found that the y-axis as tooling direction would clear most of the faces without any difficulties.
Now extract any surface and create mid point on it.
Then create a dummy axis creating a line on the point and direction along y axis.
Perform draft analysis to find whether the given axis clearing the draft analysis. If not create a new tooling axis.
Draft Analysis of Class A-surface
CLASS B-SURFACE CREATION
Class B-surface means the thickness of a part is not visible and the 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.
Create an Offset surface of Class A-surface about 2.5mm inward direction.
Check for discontinuity and rework on the offset surface using extract, boundary, and multi-section surface.
Join the surfaces and ensure the final Class B surface created has no gaps.
CLASS C-SURFACE CREATION
The surface that joins Class A-surface and Class B-surface 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.
Create the sweep surface with reference to the surface and tooling axis by multi-extracting Class A boundary.
CREATING FINAL SURFACE
For creating the final door trim surface, join the Class A, Class B, and Class C surface all together.
Check for any discontinuity in the Fianl surface by clicking on the boundary command.
If there is no discontinuity in the final join then will create the solid body of the final join.
DOG HOUSE Creation
Dog house are designed to avoid SINK MARKS created on 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.
C thickness should be 40% of the main wall thickness T.
The minimum width of the dog house is 12mm.
The height of B should be 3-6mm.
The minimum draft for the dog house is 1.5 degrees to die draw.
The procedure of creating the DOG HOUSE
- First step is to create a side core axis.
- Create an axis by choosing the normal-to-point method.
Create the dog house by creating a positioned sketch on the z-x plane and extracting the plane.
Then use the extrude command and extrude the sketch to create dog house outer walls.
Now close the upper wall by using the boundary, line, and fill commands.
Using the thicken command in the part workbench, create a solid part of the dog house.
Give proper draft angles and fillets by considering the design rules.
Using Boolean operation, Union trim the dog house body part with the door trim component.
3D Part model in various orientations(Isometric, Front Side and Top View)
DRAFT ANALYSIS
The drafted 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 color 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.
Procedures for performing the draft analysis are as follows.
Change the view mode of the component to be in customised parameter mode and than select the shading mode as materials.
Then open the featured draft analysis tool from the insert menu.
Then click on the compass to define the current drafting direction and then drag and align the compass on the Tooling axis.
Then lock the draft direction and perform draft analysis by clicking on the component.
Colour Range Representation
GREEN Color - Positive Draft/Over the Given Draft Value
BLUE Color - Draft is Between the given draft value
RED Color - Negative Draft
Draft Analysis of DOG HOUSE using the side core axis
Draft Analysis of Final Door Trim Component
The Expanded Tree Structure for the Geometrical Set and the Part Body
