Week 9 - Attachment Feature Creation - Challenge 2

AIM

Create the Dog House for the Door Trim considering the design rules

INTRODUCTION

DOG HOUSE

The dog house is an engineering feature used in plastic design. Dog houses are used as support features. Sometimes other engineering features like snaps, locators, and screw bosses are mounted on them to increase their strength.

Dog houses 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 the 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 a 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 rules.
• Perform draft analysis for both Class-A surface and 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 continuity of the given surface using Join or Boundary commands.

If there are no gaps on the A surface, create a tooling axis.

Procedure for Tooling axis creation

• Check the best possible tooling direction by manually adjusting the compass.
• By analyzing 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 a mid-point on it.
• Then create a dummy axis creating a line on the point and direction along the y-axis.
• Perform draft analysis to find whether the given axis clears the draft analysis. If not create a new tooling axis.

Intersection method

• Create a new tooling axis by intersection method.
• Create an intersection along z and x directions.
• Take the first intersection and Create lines which are coinciding the curves having a draft angle. Then create bisecting line 1 concerning the lines created.
• Follow the same procedure for the second intersection and create a bisecting line 2.
• Using the bisecting line 1 and bisecting line 2, create a new bisecting line and if it clears the draft analysis test, rename it as the tooling axis.

Draft analysis of CLASS-A surface

CLASS-B surface creation

Class-B surface means the thickness of a part it is not visible and is inside part. In other words, the 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.

• Create an offset surface of CLASS-A in about 2.5mm inward direction.
• Check for the discontinuity and rework on the offset surface using extract, multi-extract, multi sections surfaces.

CLASS-C surface creation

The surface that joins class-A and class-B surfaces are the class-C surfaces. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled

• Create the sweep surfaces concerning the surface and tooling axis by multi-extracting the CLASS-A boundary
• Join the sweep surfaces by using commands like extrapolating, trim, and multi-section surfaces.
• Finally, join all the sweep surfaces and ensure the continuity of the CLASS-C surface.

Creating the Final surface

• For creating the Finals door trim surface, join the CLASS-A and CLASS-C surfaces together.
• Then Extrapolate the B surface a little bit outward direction to make sure that there would not be any gap when trimming with the joined surface.
• Then trim the extrapolated CLASS-B surface with the Join surface (CLASS-A and CLASS-C)

Make a solid part body using the close surface command in the part design workbench

DOG HOUSE Creation

• Dog houses are designed to avoid SINK MARK 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.

• C thickness should be 40% of the main wall thickness T
• The minimum width of the dog house is 12 mm.
• The height of B should be 3-6 mm
• The minimum draft for the do house is 1.5 degrees to die drawing.

Procedure for creating the DOG HOUSE

• The first step is to create a side core axis.
• I have chosen the normal to-the-point method for creating the side core tooling axis.

• Create the dog house by creating a positioned sketch on the z-x plane. Using extrude or sweep method create dog hose outer walls.

• Now close the top wall using the multi-section surface command.
• Using 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.