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

ATTACHMENT FEATURE CREATION (DOG HOUSE)

AIM:

To create a dog house for the door trim considering the design rules.

INTRODUCTION:

DOG HOUSE:

Dog house is an engineering feature used in plastic design. Dog house are used as support feature. Sometimes other engineering features like snaps, locators, serew bosses are mounted on them to increase the strength.

Dog house are subjected to draft analysis to prevent breakage of the component during ejection from the mould cavity. Dog house and other engineering components are built on the B-surface.

OBJECTIVE:

• Create tooling axis for the given class-A surface.
• Create the class-B and class-C surfaces of door trim using the given class-A surface.
• Create final surface model and convert it into solid body using close surface command in the part design work bench.
• Create side core axis for dog house.
• Create dog house on the B-surface by considering the design rules.
• Perform draft analysis for both class-A surface and final part body.

CREATING TOOLING AXIS:

• Check the best possible tooling direction by manually adjusting the compass.
• By analysing it is found that 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 tooling axis creating a line on the point and direction along the Y axis.
• Create a new tooling axis by intersection method.
• Create intersection along ZX direction.
• Take the first intersection and create the lines which are considering the curves having a draft angleangle. Then create bisecting line 1 with respect to the lines Created.
• Follow the same procedure for the second intersection and create the bisecting line 2.
• Using the bisecting line 1, bisecting line 2, create new bisecting line and if it clear the draft analysis test, rename it as tooling axis.

DRAFT ANALYSIS FOR CLASS-A SURFACE:

CLASS-B SURFACE CREATION:

• Class-B surface means thickness of a part it is not visible and it is inside part.
• Create ofset surface of class-A about 2.5mm inward direction.
• Check for the discontinuity and rework on the ofset surface using extract, multiple extract, multi section surface.
• Join the surface and ensure the final class-B surface created has no gaps.

CLASS-C SURFACE CREATION:

• surface that joins class-A and class-B surfaces is class-C surface.Class-C is often specified for interior surface not readily Visible, surfaces that will be covered by another part when assembled.
• Create the sweep surfaces with reference to the surface and tooling axis by multi extracting the class-A boundary.
• Join the sweep surface by using command like extrapolate, trim, multi section surface.
• Finally join the sweep surfaces and ensure the continuity of the class-C surface.

CREATING THE FINAL SURFACE:

• For creating the final door trim surface. Join the class-A and class-C surface together.
• Then extrapolate the B surface little bit onward direction to make sure that there would not be any gap when trimming with joined surface.
• Then trim the Extrapolated class-B surface with join surface.
• Make a solid part body by using close surface command in the part design work bench.

DOG HOUSE CREATION:

• Dog house are designed to avoid sink Mark created on the class-A surface by screw bosses and to solve the length issues when giving screw boss which need to be assembled to other components.
• It is also useful when perpendicular screw bosses are required on the part to the tooling direction.

• C thickness should be 40% of the main wall thickness T.
• Minimum width of the dog house is 12mm
• Height of B should be 3-6mm.
• Minimum draft for the dog house is 1.5 degree to die draw.

PROCEDURE FOR CREATING THE DOG HOUSE:

• First step is to create a side core axis.
• I have chosen normal to the point method for creating the side core tooling axis.
• Create the dog house by creating the positioned sketch on the ZX plane. Using extrude or sweep method to create dog house outer walls.
• Now close the top wall by using the multi section surface command.
• Using thicken command in the part design work bench, create a solid part of a dog house.
• Give proper draft angle and fillets by considering the design rules.

DRAFT ANALYSIS OF DOG HOUSE:

FINAL COMPONENT DRAFT ANALYSIS: